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Sample records for ubiquitination inhibitor inhibits

  1. GS143, an IκB ubiquitination inhibitor, inhibits allergic airway inflammation in mice

    International Nuclear Information System (INIS)

    Hirose, Koichi; Wakashin, Hidefumi; Oki, Mie; Kagami, Shin-ichiro; Suto, Akira; Ikeda, Kei; Watanabe, Norihiko; Iwamoto, Itsuo; Furuichi, Yasuhiro; Nakajima, Hiroshi

    2008-01-01

    Asthma is characterized by airway inflammation with intense eosinophil infiltration and mucus hyper-production, in which antigen-specific Th2 cells play critical roles. Nuclear factor-κB (NF-κB) pathway has been demonstrated to be essential for the production of Th2 cytokines and chemokines in the airways in murine asthma models. In the present study, we examined the effect of GS143, a novel small-molecule inhibitor of IκB ubiquitination, on antigen-induced airway inflammation and Th2 cytokine production in mice. Intranasal administration of GS143 prior to antigen challenge suppressed antigen-induced NF-κB activation in the lung of sensitized mice. Intranasal administration of GS143 also inhibited antigen-induced eosinophil and lymphocyte recruitment into the airways as well as the expression of Th2 cytokines and eotaxin in the airways. Moreover, GS143 inhibited antigen-induced differentiation of Th2 cells but not of Th1 cells in vitro. Taken together, these results suggest that IκB ubiquitination inhibitor may have therapeutic potential against asthma

  2. Puromycin induces SUMO and ubiquitin redistribution upon proteasome inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, Hotaru [Course for Biological Sciences, Faculty of Science, Kumamoto University, Kumamoto (Japan); Saitoh, Hisato, E-mail: hisa@kumamoto-u.ac.jp [Course for Biological Sciences, Faculty of Science, Kumamoto University, Kumamoto (Japan); Department of Biological Sciences, Graduate School of Science and Technology, Kumamoto University, Kumamoto (Japan)

    2016-07-29

    We have previously reported the co-localization of O-propargyl-puromycin (OP-Puro) with SUMO-2/3 and ubiquitin at promyelocytic leukemia-nuclear bodies (PML-NBs) in the presence of the proteasome inhibitor MG132, implying a role for the ubiquitin family in sequestering OP-puromycylated immature polypeptides to the nucleus during impaired proteasome activity. Here, we found that as expected puromycin induced SUMO-1/2/3 accumulation with ubiquitin at multiple nuclear foci in HeLa cells when co-exposed to MG132. Co-administration of puromycin and MG132 also facilitated redistribution of PML and the SUMO-targeted ubiquitin ligase RNF4 concurrently with SUMO-2/3. As removal of the drugs from the medium led to disappearance of the SUMO-2/3-ubiquitin nuclear foci, our findings indicated that nuclear assembly/disassembly of SUMO-2/3 and ubiquitin was pharmacologically manipulable, supporting our previous observation on OP-Puro, which predicted the ubiquitin family function in sequestrating aberrant proteins to the nucleus. -- Highlights: •Puromycin exhibits the O-propargyl-puromycin effect. •Puromycin induces SUMO redistribution upon proteasome inhibition. •Ubiquitin and RNF4 accumulate at PML-nuclear bodies with SUMO-2/3. •The ubiquitin family may function in nuclear sequestration of immature proteins.

  3. Puromycin induces SUMO and ubiquitin redistribution upon proteasome inhibition

    International Nuclear Information System (INIS)

    Matsumoto, Hotaru; Saitoh, Hisato

    2016-01-01

    We have previously reported the co-localization of O-propargyl-puromycin (OP-Puro) with SUMO-2/3 and ubiquitin at promyelocytic leukemia-nuclear bodies (PML-NBs) in the presence of the proteasome inhibitor MG132, implying a role for the ubiquitin family in sequestering OP-puromycylated immature polypeptides to the nucleus during impaired proteasome activity. Here, we found that as expected puromycin induced SUMO-1/2/3 accumulation with ubiquitin at multiple nuclear foci in HeLa cells when co-exposed to MG132. Co-administration of puromycin and MG132 also facilitated redistribution of PML and the SUMO-targeted ubiquitin ligase RNF4 concurrently with SUMO-2/3. As removal of the drugs from the medium led to disappearance of the SUMO-2/3-ubiquitin nuclear foci, our findings indicated that nuclear assembly/disassembly of SUMO-2/3 and ubiquitin was pharmacologically manipulable, supporting our previous observation on OP-Puro, which predicted the ubiquitin family function in sequestrating aberrant proteins to the nucleus. -- Highlights: •Puromycin exhibits the O-propargyl-puromycin effect. •Puromycin induces SUMO redistribution upon proteasome inhibition. •Ubiquitin and RNF4 accumulate at PML-nuclear bodies with SUMO-2/3. •The ubiquitin family may function in nuclear sequestration of immature proteins.

  4. A small-molecule inhibitor of the ubiquitin activating enzyme for cancer treatment.

    Science.gov (United States)

    Hyer, Marc L; Milhollen, Michael A; Ciavarri, Jeff; Fleming, Paul; Traore, Tary; Sappal, Darshan; Huck, Jessica; Shi, Judy; Gavin, James; Brownell, Jim; Yang, Yu; Stringer, Bradley; Griffin, Robert; Bruzzese, Frank; Soucy, Teresa; Duffy, Jennifer; Rabino, Claudia; Riceberg, Jessica; Hoar, Kara; Lublinsky, Anya; Menon, Saurabh; Sintchak, Michael; Bump, Nancy; Pulukuri, Sai M; Langston, Steve; Tirrell, Stephen; Kuranda, Mike; Veiby, Petter; Newcomb, John; Li, Ping; Wu, Jing Tao; Powe, Josh; Dick, Lawrence R; Greenspan, Paul; Galvin, Katherine; Manfredi, Mark; Claiborne, Chris; Amidon, Benjamin S; Bence, Neil F

    2018-02-01

    The ubiquitin-proteasome system (UPS) comprises a network of enzymes that is responsible for maintaining cellular protein homeostasis. The therapeutic potential of this pathway has been validated by the clinical successes of a number of UPS modulators, including proteasome inhibitors and immunomodulatory imide drugs (IMiDs). Here we identified TAK-243 (formerly known as MLN7243) as a potent, mechanism-based small-molecule inhibitor of the ubiquitin activating enzyme (UAE), the primary mammalian E1 enzyme that regulates the ubiquitin conjugation cascade. TAK-243 treatment caused depletion of cellular ubiquitin conjugates, resulting in disruption of signaling events, induction of proteotoxic stress, and impairment of cell cycle progression and DNA damage repair pathways. TAK-243 treatment caused death of cancer cells and, in primary human xenograft studies, demonstrated antitumor activity at tolerated doses. Due to its specificity and potency, TAK-243 allows for interrogation of ubiquitin biology and for assessment of UAE inhibition as a new approach for cancer treatment.

  5. Ubiquitin-aldehyde: a general inhibitor of ubiquitin-recycling processes

    International Nuclear Information System (INIS)

    Hershko, A.; Rose, I.A.

    1987-01-01

    The generation and characterization of ubiquitin (Ub)-aldehyde, a potent inhibitor of Ub-C-terminal hydrolase, has previously been reported. The authors examine the action of this compound on the Ub-mediated proteolytic pathway using the system derived from rabbit reticulocytes. Addition of Ub-aldehyde was found to strongly inhibit breakdown of added 125 I-labeled lysozyme, but inhibition was overcome by increasing concentrations of Ub. The following evidence shows the effect of Ub-aldehyde on protein breakdown to be indirectly caused by its interference with the recycling of Ub, leading to exhaustion of the supply of free Ub: (i) Ub-aldehyde markedly increased the accumulation of Ub-protein conjugates coincident with a much decreased rate of conjugate breakdown; (ii) release of Ub from isolated Ub-protein conjugates in the absence of ATP (and therefore not coupled to protein degradation) is markedly inhibited by Ub-aldehyde. On the other hand, the ATP-dependent degradation of the protein moiety of Ub conjugates, which is an integral part of the proteolytic process, is not inhibited by this agent; (iii) direct measurement of levels of free Ub showed a rapid disappearance caused by the inhibitor. The Ub is found to be distributed in derivatives of a wide range of molecular weight classes. It thus seems that Ub-aldehyde, previously demonstrated to inhibit the hydrolysis of Ub conjugates of small molecules, also inhibits the activity of a series of enzymes that regenerate free Ub from adducts with proteins and intermediates in protein breakdown

  6. Stressing the ubiquitin-proteasome system without 20S proteolytic inhibition selectively kills cervical cancer cells.

    Directory of Open Access Journals (Sweden)

    Ravi K Anchoori

    Full Text Available Cervical cancer cells exhibit an increased requirement for ubiquitin-dependent protein degradation associated with an elevated metabolic turnover rate, and for specific signaling pathways, notably HPV E6-targeted degradation of p53 and PDZ proteins. Natural compounds with antioxidant properties including flavonoids and triterpenoids hold promise as anticancer agents by interfering with ubiquitin-dependent protein degradation. An increasing body of evidence indicates that their α-β unsaturated carbonyl system is the molecular determinant for inhibition of ubiquitin-mediated protein degradation up-stream of the catalytic sites of the 20S proteasome. Herein we report the identification and characterization of a new class of chalcone-based, potent and cell permeable chemical inhibitors of ubiquitin-dependent protein degradation, and a lead compound RAMB1. RAMB1 inhibits ubiquitin-dependent protein degradation without compromising the catalytic activities of the 20S proteasome, a mechanism distinct from that of Bortezomib. Treatment of cervical cancer cells with RAMB1 triggers unfolded protein responses, including aggresome formation and Hsp90 stabilization, and increases p53 steady state levels. RAMB1 treatment results in activation of lysosomal-dependent degradation pathways as a mechanism to compensate for increasing levels of poly-ubiquitin enriched toxic aggregates. Importantly, RAMB1 synergistically triggers cell death of cervical cancer cells when combined with the lysosome inhibitor Chloroquine.

  7. The mechanism of OTUB1-mediated inhibition of ubiquitination

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    Wiener, Reuven; Zhang, Xiangbin; Wang, Tao; Wolberger, Cynthia (JHU)

    2013-04-08

    Histones are ubiquitinated in response to DNA double-strand breaks (DSB), promoting recruitment of repair proteins to chromatin. UBC13 (also known as UBE2N) is a ubiquitin-conjugating enzyme (E2) that heterodimerizes with UEV1A (also known as UBE2V1) and synthesizes K63-linked polyubiquitin (K63Ub) chains at DSB sites in concert with the ubiquitin ligase (E3), RNF168 (ref. 3). K63Ub synthesis is regulated in a non-canonical manner by the deubiquitinating enzyme, OTUB1 (OTU domain-containing ubiquitin aldehyde-binding protein 1), which binds preferentially to the UBC13-Ub thiolester. Residues amino-terminal to the OTU domain, which had been implicated in ubiquitin binding, are required for binding to UBC13-Ub and inhibition of K63Ub synthesis. Here we describe structural and biochemical studies elucidating how OTUB1 inhibits UBC13 and other E2 enzymes. We unexpectedly find that OTUB1 binding to UBC13-Ub is allosterically regulated by free ubiquitin, which binds to a second site in OTUB1 and increases its affinity for UBC13-Ub, while at the same time disrupting interactions with UEV1A in a manner that depends on the OTUB1 N terminus. Crystal structures of an OTUB1-UBC13 complex and of OTUB1 bound to ubiquitin aldehyde and a chemical UBC13-Ub conjugate show that binding of free ubiquitin to OTUB1 triggers conformational changes in the OTU domain and formation of a ubiquitin-binding helix in the N terminus, thus promoting binding of the conjugated donor ubiquitin in UBC13-Ub to OTUB1. The donor ubiquitin thus cannot interact with the E2 enzyme, which has been shown to be important for ubiquitin transfer. The N-terminal helix of OTUB1 is positioned to interfere with UEV1A binding to UBC13, as well as with attack on the thiolester by an acceptor ubiquitin, thereby inhibiting K63Ub synthesis. OTUB1 binding also occludes the RING E3 binding site on UBC13, thus providing a further component of inhibition. The general features of the inhibition mechanism explain how OTUB1

  8. Nickel compounds induce histone ubiquitination by inhibiting histone deubiquitinating enzyme activity

    International Nuclear Information System (INIS)

    Ke Qingdong; Ellen, Thomas P.; Costa, Max

    2008-01-01

    Nickel (Ni) compounds are known carcinogens but underlying mechanisms are not clear. Epigenetic changes are likely to play an important role in nickel ion carcinogenesis. Previous studies have shown epigenetic effects of nickel ions, including the loss of histone acetylation and a pronounced increase in dimethylated H3K9 in nickel-exposed cells. In this study, we demonstrated that both water-soluble and insoluble nickel compounds induce histone ubiquitination (uH2A and uH2B) in a variety of cell lines. Investigations of the mechanism by which nickel increases histone ubiquitination in cells reveal that nickel does not affect cellular levels of the substrates of this modification, i.e., ubiquitin, histones, and other non-histone ubiquitinated proteins. In vitro ubiquitination and deubiquitination assays have been developed to further investigate possible effects of nickel on enzymes responsible for histone ubiquitination. Results from the in vitro assays demonstrate that the presence of nickel did not affect the levels of ubiquitinated histones in the ubiquitinating assay. Instead, the addition of nickel significantly prevents loss of uH2A and uH2B in the deubiquitinating assay, suggesting that nickel-induced histone ubiquitination is the result of inhibition of (a) putative deubiquitinating enzyme(s). Additional supporting evidence comes from the comparison of the response to nickel ions with a known deubiquitinating enzyme inhibitor, iodoacetamide (IAA). This study is the first to demonstrate such effects of nickel ions on histone ubiquitination. It also sheds light on the possible mechanisms involved in altering the steady state of this modification. The study provides further evidence that supports the notion that nickel ions alter epigenetic homeostasis in cells, which may lead to altered programs of gene expression and carcinogenesis

  9. Generation and Validation of Intracellular Ubiquitin Variant Inhibitors for USP7 and USP10

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wei; Sartori, Maria A.; Makhnevych, Taras; Federowicz, Kelly E.; Dong, Xiaohui; Liu, Li; Nim, Satra; Dong, Aiping; Yang, Jingsong; Li, Yanjun; Haddad, Dania; Ernst, Andreas; Heerding, Dirk; Tong, Yufeng; Moffat, Jason; Sidhu, Sachdev S.

    2017-11-01

    Post-translational modification of the p53 signaling pathway plays an important role in cell cycle progression and stress-induced apoptosis. Indeed, a large body of work has shown that dysregulation of p53 and its E3 ligase MDM2 by the ubiquitin-proteasome system (UPS) promotes carcinogenesis and malignant transformation. Thus, drug discovery efforts have focused on the restoration of wild-type p53 activity or inactivation of oncogenic mutant p53 by targeted inhibition of UPS components, particularly key deubiquitinases (DUBs) of the ubiquitin-specific protease (USP) class. However, development of selective small-molecule USP inhibitors has been challenging, partly due to the highly conserved structural features of the catalytic sites across the class. To tackle this problem, we devised a protein engineering strategy for rational design of inhibitors for DUBs and other UPS proteins. We employed a phage-displayed ubiquitin variant (UbV) library to develop inhibitors targeting the DUBs USP7 and USP10, which are involved in regulating levels of p53 and MDM2. We were able to identify UbVs that bound USP7 or USP10 with high affinity and inhibited deubiquitination activity. We solved the crystal structure of UbV.7.2 and rationalized the molecular basis for enhanced affinity and specificity for USP7. Finally, cell death was increased significantly by UbV.7.2 expression in a colon cancer cell line that was treated with the chemotherapy drug cisplatin, demonstrating the therapeutic potential of inhibiting USP7 by this approach

  10. ABA-dependent inhibition of the ubiquitin proteasome system during germination at high temperature in Arabidopsis.

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    Chiu, Rex Shun; Pan, Shiyue; Zhao, Rongmin; Gazzarrini, Sonia

    2016-12-01

    During germination, endogenous and environmental factors trigger changes in the transcriptome, translatome and proteome to break dormancy. In Arabidopsis thaliana, the ubiquitin proteasome system (UPS) degrades proteins that promote dormancy to allow germination. While research on the UPS has focused on the identification of proteasomal substrates, little information is known about the regulation of its activity. Here we characterized the activity of the UPS during dormancy release and maintenance by monitoring protein ubiquitination and degradation of two proteasomal substrates: Suc-LLVY-AMC, a well characterized synthetic substrate, and FUSCA3 (FUS3), a dormancy-promoting transcription factor degraded by the 26S proteasome. Our data indicate that proteasome activity and protein ubiquitination increase during imbibition at optimal temperature (21°C), and are required for seed germination. However, abscisic acid (ABA) and supraoptimal temperature (32°C) inhibit germination by dampening both protein ubiquitination and proteasome activity. Inhibition of UPS function by high temperature is reduced by the ABA biosynthesis inhibitor, fluridone, and in ABA biosynthetic mutants, suggesting that it is ABA dependent. Accordingly, inhibition of FUS3 degradation at 32°C is also dependent on ABA. Native gels show that inhibition of proteasome activity is caused by interference with the 26S/30S ratio as well as free 19S and 20S levels, impacting the proteasome degradation cycle. Transfer experiments show that ABA-mediated inhibition of proteasome activity at 21°C is restricted to the first 2 days of germination, a time window corresponding to seed sensitivity to environmental and ABA-mediated growth inhibition. Our data show that ABA and high temperature inhibit germination under unfavourable growth conditions by repressing the UPS. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.

  11. DMPD: Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 16982211 Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. Wullaer...vg) (.html) (.csml) Show Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. PubmedID 1698221...1 Title Ubiquitin: tool and target for intracellular NF-kappaB inhibitors. Author

  12. Linear ubiquitin chain induces apoptosis and inhibits tumor growth.

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    Qin, Zhoushuai; Jiang, Wandong; Wang, Guifen; Sun, Ying; Xiao, Wei

    2018-01-01

    Ubiquitination of proliferating cell nuclear antigen (PCNA) plays an important role in DNA damage response. Ectopic expression of PCNA fused at either terminus with ubiquitin (Ub) lacking two C-terminal glycine residues induces translesion DNA synthesis which resembles synthesis mediated by PCNA monoubiquitination. PCNA fused with Ub containing the C-terminal Gly residues at the C-terminus can be further polyubiquitinated in a Gly-dependent manner, which inhibits cell proliferation and induces ATR-dependent replication checkpoint. In this study, we surprisingly found that PCNA fused to a head-to-tail linear Ub chain induces apoptosis in a Ub chain length-dependent manner. Further investigation revealed that the apoptotic effect is actually induced by the linear Ub chain independently from PCNA, as the Ub chain fused to GFP or an epitope tag still efficiently induces apoptosis. It is revealed that the artificial linear Ub chain differs from endogenously encoded linear Ub chains in that its Ubs contain a Ub-G76S substitution, making the Ub chain resistant to cleavage by deubiquitination enzymes. We demonstrated in this study that ectopic expression of the artificial Ub chain alone in cultured human cancer cells is sufficient to inhibit tumor growth in a xenograft mouse model, making the linear Ub chain a putative anti-cancer agent.

  13. Inhibition of Siah2 ubiquitin ligase by vitamin K3 (menadione) attenuates hypoxia and MAPK signaling and blocks melanoma tumorigenesis.

    Science.gov (United States)

    Shah, Meera; Stebbins, John L; Dewing, Antimone; Qi, Jianfei; Pellecchia, Maurizio; Ronai, Ze'ev A

    2009-12-01

    The E3 ubiquitin ligase Siah2 has been implicated in the regulation of the hypoxia response, as well as in the control of Ras, JNK/p38/NF-kappaB signaling pathways. Both Ras/mitogen-activated protein kinase (MAPK) and hypoxia pathways are important for melanoma development and progression, pointing to the possible use of Siah2 as target for treatment of this tumor type. In the present study, we have established a high-throughput electro-chemiluninescent-based assay in order to screen and identify inhibitors of Siah2 ubiquitin ligase activity. Of 1840 compounds screened, we identified and characterized menadione (MEN) as a specific inhibitor of Siah2 ligase activity. MEN attenuated Siah2 self-ubiquitination, and increased expression of its substrates PHD3 and Sprouty2, with concomitant decrease in levels of HIF-1alpha and pERK, the respective downstream effectors. MEN treatment no longer affected PHD3 or Sprouty2 in Siah-KO cells, pointing to its Siah-dependent effects. Further, MEN inhibition of Siah2 was not attenuated by free radical scavenger, suggesting it is ROS-independent. Significantly, growth of xenograft melanoma tumors was inhibited following the administration of MEN or its derivative. These findings reveal an efficient platform for the identification of Siah inhibitors while identifying and characterizing MEN as Siah inhibitor that attenuates hypoxia and MAPK signaling, and inhibits melanoma tumorigenesis.

  14. Inhibition of Siah2 ubiquitin ligase by vitamin K3 (menadione) attenuates hypoxia and MAPK signaling and blocks melanoma tumorigenesis

    Science.gov (United States)

    Shah, Meera; Stebbins, John L.; Dewing, Antimone; Qi, Jianfei; Pellecchia, Maurizio; Ronai, Ze’ev A.

    2010-01-01

    Summary The E3 ubiquitin ligase Siah2 has been implicated in the regulation of the hypoxia response, as well as in the control of Ras, JNK/p38/NF-κB signaling pathways. Both Ras/mitogen-activated protein kinase (MAPK) and hypoxia pathways are important for melanoma development and progression, pointing to the possible use of Siah2 as target for treatment of this tumor type. In the present study, we have established a high-throughput electro-chemiluninescent-based assay in order to screen and identify inhibitors of Siah2 ubiquitin ligase activity. Of 1840 compounds screened, we identified and characterized menadione (MEN) as a specific inhibitor of Siah2 ligase activity. MEN attenuated Siah2 self-ubiquitination, and increased expression of its substrates PHD3 and Sprouty2, with concomitant decrease in levels of HIF-1α and pERK, the respective downstream effectors. MEN treatment no longer affected PHD3 or Sprouty2 in Siah-KO cells, pointing to its Siah-dependent effects. Further, MEN inhibition of Siah2 was not attenuated by free radical scavenger, suggesting it is ROS-independent. Significantly, growth of xenograft melanoma tumors was inhibited following the administration of MEN or its derivative. These findings reveal an efficient platform for the identification of Siah inhibitors while identifying and characterizing MEN as Siah inhibitor that attenuates hypoxia and MAPK signaling, and inhibits melanoma tumorigenesis. PMID:19712206

  15. Ubiquitin

    DEFF Research Database (Denmark)

    Vinther-Jensen, T.; Simonsen, A. H.; Budtz-Jorgensen, E.

    2015-01-01

    -expansion negative individuals using surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry. Differences in peak intensity from SELDI-TOF spectra were evaluated. RESULTS: Levels of 10 peaks were statistically significantly different between manifest gene-expansion carriers...... and controls. One of them identified as ubiquitin was shown to be dependent on the Unified Huntington Disease Rating Scale Total Functional Capacity, a pseudo-measure of disease severity (P = 0.001), and the Symbol Digit Modalities Test (0.04) in manifest and CAG-age product score (P = 0.019) in all gene......-expansion carriers. CONCLUSIONS AND RELEVANCE: Multiple studies have shown that the ubiquitin-proteasome system is involved in Huntington's disease pathogenesis and understanding of this involvement may have therapeutic potential in humans. This is the first study on cerebrospinal fluid to confirm the involvement...

  16. Chemotherapy inhibits skeletal muscle ubiquitin-proteasome-dependent proteolysis.

    Science.gov (United States)

    Tilignac, Thomas; Temparis, Sandrine; Combaret, Lydie; Taillandier, Daniel; Pouch, Marie-Noëlle; Cervek, Matjaz; Cardenas, Diana M; Le Bricon, Thierry; Debiton, Eric; Samuels, Susan E; Madelmont, Jean-Claude; Attaix, Didier

    2002-05-15

    Chemotherapy has cachectic effects, but it is unknown whether cytostatic agents alter skeletal muscle proteolysis. We hypothesized that chemotherapy-induced alterations in protein synthesis should result in the increased incidence of abnormal proteins, which in turn should stimulate ubiquitin-proteasome-dependent proteolysis. The effects of the nitrosourea cystemustine were investigated in skeletal muscles from both healthy and colon 26 adenocarcinoma-bearing mice, an appropriate model for testing the impact of cytostatic agents. Muscle wasting was seen in both groups of mice 4 days after a single cystemustine injection, and the drug further increased the loss of muscle proteins already apparent in tumor-bearing animals. Cystemustine cured the tumor-bearing mice with 100% efficacy. Surprisingly, within 11 days of treatment, rates of muscle proteolysis progressively decreased below basal levels observed in healthy control mice and contributed to the cessation of muscle wasting. Proteasome-dependent proteolysis was inhibited by mechanisms that include reduced mRNA levels for 20S and 26S proteasome subunits, decreased protein levels of 20S proteasome subunits and the S14 non-ATPase subunit of the 26S proteasome, and impaired chymotrypsin- and trypsin-like activities of the enzyme. A combination of cisplatin and ifosfamide, two drugs that are widely used in the treatment of cancer patients, also depressed the expression of proteasomal subunits in muscles from rats bearing the MatB adenocarcinoma below basal levels. Thus, a down-regulation of ubiquitin-proteasome-dependent proteolysis is observed with various cytostatic agents and contributes to reverse the chemotherapy-induced muscle wasting.

  17. Cycle Inhibiting Factors (Cifs: Cyclomodulins That Usurp the Ubiquitin-Dependent Degradation Pathway of Host Cells

    Directory of Open Access Journals (Sweden)

    Eric Oswald

    2011-03-01

    Full Text Available Cycle inhibiting factors (Cifs are type III secreted effectors produced by diverse pathogenic bacteria. Cifs are “cyclomodulins” that inhibit the eukaryotic host cell cycle and also hijack other key cellular processes such as those controlling the actin network and apoptosis. This review summarizes current knowledge on Cif since its first characterization in enteropathogenic Escherichia coli, the identification of several xenologues in distant pathogenic bacteria, to its structure elucidation and the recent deciphering of its mode of action. Cif impairs the host ubiquitin proteasome system through deamidation of ubiquitin or the ubiquitin-like protein NEDD8 that regulates Cullin-Ring-ubiquitin Ligase (CRL complexes. The hijacking of the ubiquitin-dependent degradation pathway of host cells results in the modulation of various cellular functions such as epithelium renewal, apoptosis and immune response. Cif is therefore a powerful weapon in the continuous arm race that characterizes host-bacteria interactions.

  18. Histone deacetylase inhibitor, Trichostatin A induces ubiquitin-dependent cyclin D1 degradation in MCF-7 breast cancer cells

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    Charles Coombes R

    2006-02-01

    Full Text Available Abstract Background Cyclin D1 is an important regulator of G1-S phase cell cycle transition and has been shown to be important for breast cancer development. GSK3β phosphorylates cyclin D1 on Thr-286, resulting in enhanced ubiquitylation, nuclear export and degradation of the cyclin in the cytoplasm. Recent findings suggest that the development of small-molecule cyclin D1 ablative agents is of clinical relevance. We have previously shown that the histone deacetylase inhibitor trichostatin A (TSA induces the rapid ubiquitin-dependent degradation of cyclin D1 in MCF-7 breast cancer cells prior to repression of cyclin D1 gene (CCND1 transcription. TSA treatment also resulted in accumulation of polyubiquitylated GFP-cyclin D1 species and reduced levels of the recombinant protein within the nucleus. Results Here we provide further evidence for TSA-induced ubiquitin-dependent degradation of cyclin D1 and demonstrate that GSK3β-mediated nuclear export facilitates this activity. Our observations suggest that TSA treatment results in enhanced cyclin D1 degradation via the GSK3β/CRM1-dependent nuclear export/26S proteasomal degradation pathway in MCF-7 cells. Conclusion We have demonstrated that rapid TSA-induced cyclin D1 degradation in MCF-7 cells requires GSK3β-mediated Thr-286 phosphorylation and the ubiquitin-dependent 26S proteasome pathway. Drug induced cyclin D1 repression contributes to the inhibition of breast cancer cell proliferation and can sensitize cells to CDK and Akt inhibitors. In addition, anti-cyclin D1 therapy may be highly specific for treating human breast cancer. The development of potent and effective cyclin D1 ablative agents is therefore of clinical relevance. Our findings suggest that HDAC inhibitors may have therapeutic potential as small-molecule cyclin D1 ablative agents.

  19. Systemic insulin sensitivity is regulated by GPS2 inhibition of AKT ubiquitination and activation in adipose tissue.

    Science.gov (United States)

    Cederquist, Carly T; Lentucci, Claudia; Martinez-Calejman, Camila; Hayashi, Vanessa; Orofino, Joseph; Guertin, David; Fried, Susan K; Lee, Mi-Jeong; Cardamone, M Dafne; Perissi, Valentina

    2017-01-01

    Insulin signaling plays a unique role in the regulation of energy homeostasis and the impairment of insulin action is associated with altered lipid metabolism, obesity, and Type 2 Diabetes. The main aim of this study was to provide further insight into the regulatory mechanisms governing the insulin signaling pathway by investigating the role of non-proteolytic ubiquitination in insulin-mediated activation of AKT. The molecular mechanism of AKT regulation through ubiquitination is first dissected in vitro in 3T3-L1 preadipocytes and then validated in vivo using mice with adipo-specific deletion of GPS2, an endogenous inhibitor of Ubc13 activity (GPS2-AKO mice). Our results indicate that K63 ubiquitination is a critical component of AKT activation in the insulin signaling pathway and that counter-regulation of this step is provided by GPS2 preventing AKT ubiquitination through inhibition of Ubc13 enzymatic activity. Removal of this negative checkpoint, through GPS2 downregulation or genetic deletion, results in sustained activation of insulin signaling both in vitro and in vivo . As a result, the balance between lipid accumulation and utilization is shifted toward storage in the adipose tissue and GPS2-AKO mice become obese under normal laboratory chow diet. However, the adipose tissue of GPS2-AKO mice is not inflamed, the levels of circulating adiponectin are elevated, and systemic insulin sensitivity is overall improved. Our findings characterize a novel layer of regulation of the insulin signaling pathway based on non-proteolytic ubiquitination of AKT and define GPS2 as a previously unrecognized component of the insulin signaling cascade. In accordance with this role, we have shown that GPS2 presence in adipocytes modulates systemic metabolism by restricting the activation of insulin signaling during the fasted state, whereas in absence of GPS2, the adipose tissue is more efficient at lipid storage, and obesity becomes uncoupled from inflammation and insulin

  20. E3 Ubiquitin Ligase c-cbl Inhibits Microglia Activation After Chronic Constriction Injury.

    Science.gov (United States)

    Xue, Pengfei; Liu, Xiaojuan; Shen, Yiming; Ju, Yuanyuan; Lu, Xiongsong; Zhang, Jinlong; Xu, Guanhua; Sun, Yuyu; Chen, Jiajia; Gu, Haiyan; Cui, Zhiming; Bao, Guofeng

    2018-06-22

    E3 ubiquitin ligase c-Caritas B cell lymphoma (c-cbl) is associated with negative regulation of receptor tyrosine kinases, signal transduction of antigens and cytokine receptors, and immune response. However, the expression and function of c-cbl in the regulation of neuropathic pain after chronic constriction injury (CCI) are unknown. In rat CCI model, c-cbl inhibited the activation of spinal cord microglia and the release of pro-inflammatory factors including tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β) and interleukin 6 (IL-6), which alleviated mechanical and heat pain through down-regulating extracellular signal-regulated kinase (ERK) pathway. Additionally, exogenous TNF-α inhibited c-cbl protein level vice versa. In the primary microglia transfected with c-cbl siRNA, when treated with TNF-α or TNF-α inhibitor, the corresponding secretion of IL-1β and IL-6 did not change. In summary, CCI down-regulated c-cbl expression and induced the activation of microglia, then activated microglia released inflammatory factors via ERK signaling to cause pain. Our data might supply a novel molecular target for the therapy of CCI-induced neuropathic pain.

  1. Potent and selective inhibition of pathogenic viruses by engineered ubiquitin variants.

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2017-05-01

    Full Text Available The recent Middle East respiratory syndrome coronavirus (MERS-CoV, Ebola and Zika virus outbreaks exemplify the continued threat of (re-emerging viruses to human health, and our inability to rapidly develop effective therapeutic countermeasures. Many viruses, including MERS-CoV and the Crimean-Congo hemorrhagic fever virus (CCHFV encode deubiquitinating (DUB enzymes that are critical for viral replication and pathogenicity. They bind and remove ubiquitin (Ub and interferon stimulated gene 15 (ISG15 from cellular proteins to suppress host antiviral innate immune responses. A variety of viral DUBs (vDUBs, including the MERS-CoV papain-like protease, are responsible for cleaving the viral replicase polyproteins during replication, and are thereby critical components of the viral replication cycle. Together, this makes vDUBs highly attractive antiviral drug targets. However, structural similarity between the catalytic cores of vDUBs and human DUBs complicates the development of selective small molecule vDUB inhibitors. We have thus developed an alternative strategy to target the vDUB activity through a rational protein design approach. Here, we report the use of phage-displayed ubiquitin variant (UbV libraries to rapidly identify potent and highly selective protein-based inhibitors targeting the DUB domains of MERS-CoV and CCHFV. UbVs bound the vDUBs with high affinity and specificity to inhibit deubiquitination, deISGylation and in the case of MERS-CoV also viral replicative polyprotein processing. Co-crystallization studies further revealed critical molecular interactions between UbVs and MERS-CoV or CCHFV vDUBs, accounting for the observed binding specificity and high affinity. Finally, expression of UbVs during MERS-CoV infection reduced infectious progeny titers by more than four orders of magnitude, demonstrating the remarkable potency of UbVs as antiviral agents. Our results thereby establish a strategy to produce protein-based inhibitors

  2. Protection against murine osteoarthritis by inhibition of the 26S proteasome and lysine-48 linked ubiquitination.

    Science.gov (United States)

    Radwan, Marta; Wilkinson, David J; Hui, Wang; Destrument, Auriane P M; Charlton, Sarah H; Barter, Matt J; Gibson, Beth; Coulombe, Josée; Gray, Douglas A; Rowan, Andrew D; Young, David A

    2015-08-01

    To determine whether the process of ubiquitination and/or activity of the 26S proteasome are involved in the induction of osteoarthritis (OA). Bovine cartilage resorption assays, chondrocyte cell-line SW1353 and primary human articular chondrocytes were used with the general proteasome inhibitor MG132 or vehicle to identify a role of the ubiquitin-proteasome system (UPS) in cartilage destruction and matrix metalloproteinase-13 (MMP13) expression. In vivo, MG132 or vehicle, were delivered subcutaneously to mice following destabilisation of the medial meniscus (DMM)-induced OA. Subsequently, DMM was induced in Lys-to-Arg (K48R and K63R) mutant ubiquitin (Ub) transgenic mice. Cytokine signalling in SW1353s was monitored by immunoblotting and novel ubiquitinated substrates identified using Tandem Ubiquitin Binding Entities purification followed by mass spectrometry. The ubiquitination of TRAFD1 was assessed via immunoprecipitation and immunoblotting and its role in cytokine signal-transduction determined using RNA interference and real-time RT-PCR for MMP13 and interleukin-6 (IL6). Supplementation with the proteasome inhibitor MG132 protected cartilage from cytokine-mediated resorption and degradation in vivo in mice following DMM-induced OA. Using transgenic animals only K48R-mutated Ub partially protected against OA compared to wild-type or wild-type Ub transgenic mice, and this was only evident on the medial femoral condyle. After confirming ubiquitination was vital for NF-κB signalling and MMP13 expression, a screen for novel ubiquitinated substrates involved in cytokine-signalling identified TRAFD1; the depletion of which reduced inflammatory mediator-induced MMP13 and IL6 expression. Our data for the first time identifies a role for ubiquitination and the proteasome in the induction of OA via regulation of inflammatory mediator-induced MMP13 expression. These data open avenues of research to determine whether the proteasome, or K48-linked ubiquitination, are

  3. ISG15 inhibits Nedd4 ubiquitin E3 activity and enhances the innate antiviral response.

    Science.gov (United States)

    Malakhova, Oxana A; Zhang, Dong-Er

    2008-04-04

    Interferons regulate diverse immune functions through the transcriptional activation of hundreds of genes involved in anti-viral responses. The interferon-inducible ubiquitin-like protein ISG15 is expressed in cells in response to a variety of stress conditions like viral or bacterial infection and is present in its free form or is conjugated to cellular proteins. In addition, protein ubiquitination plays a regulatory role in the immune system. Many viruses modulate the ubiquitin (Ub) pathway to alter cellular signaling and the antiviral response. Ubiquitination of retroviral group-specific antigen precursors and matrix proteins of the Ebola, vesicular stomatitis, and rabies viruses by Nedd4 family HECT domain E3 ligases is an important step in facilitating viral release. We found that Nedd4 is negatively regulated by ISG15. Free ISG15 specifically bound to Nedd4 and blocked its interaction with Ub-E2 molecules, thus preventing further Ub transfer from E2 to E3. Furthermore, overexpression of ISG15 diminished the ability of Nedd4 to ubiquitinate viral matrix proteins and led to a decrease in the release of Ebola VP40 virus-like particles from the cells. These results point to a mechanistically novel function of ISG15 in the enhancement of the innate anti-viral response through specific inhibition of Nedd4 Ub-E3 activity. To our knowledge, this is the first example of a Ub-like protein with the ability to interfere with Ub-E2 and E3 interaction to inhibit protein ubiquitination.

  4. RYBP Is a K63-Ubiquitin-Chain-Binding Protein that Inhibits Homologous Recombination Repair

    Directory of Open Access Journals (Sweden)

    Mohammad A.M. Ali

    2018-01-01

    Full Text Available Summary: Ring1-YY1-binding protein (RYBP is a member of the non-canonical polycomb repressive complex 1 (PRC1, and like other PRC1 members, it is best described as a transcriptional regulator. However, several PRC1 members were recently shown to function in DNA repair. Here, we report that RYBP preferentially binds K63-ubiquitin chains via its Npl4 zinc finger (NZF domain. Since K63-linked ubiquitin chains are assembled at DNA double-strand breaks (DSBs, we examined the contribution of RYBP to DSB repair. Surprisingly, we find that RYBP is K48 polyubiquitylated by RNF8 and rapidly removed from chromatin upon DNA damage by the VCP/p97 segregase. High expression of RYBP competitively inhibits recruitment of BRCA1 repair complex to DSBs, reducing DNA end resection and homologous recombination (HR repair. Moreover, breast cancer cell lines expressing high endogenous RYBP levels show increased sensitivity to DNA-damaging agents and poly ADP-ribose polymerase (PARP inhibition. These data suggest that RYBP negatively regulates HR repair by competing for K63-ubiquitin chain binding. : Ali et al. find that RYBP binds K63-linked ubiquitin chains and is removed from DNA damage sites. This K63-ubiquitin binding allows RYBP to hinder the recruitment of BRCA1 and Rad51 to DNA double-strand breaks, thus inhibiting homologous recombination repair. Accordingly, cancer cells expressing high RYBP are more sensitive to DNA-damaging therapies. Keywords: DNA damage response, homologous recombination, ubiquitylation, RYBP, polycomb proteins, double-strand break repair, chromatin, histone modification

  5. Ubiquitin-dependent system controls radiation induced apoptosis

    International Nuclear Information System (INIS)

    Delic, J.; Magdelenat, H.; Glaisner, S.; Magdelenat, H.; Maciorowski, Z.

    1997-01-01

    The selective proteolytic pathway, dependent upon 'N-end rule' protein recognition/ubiquitination and on the subsequent proteasome dependent processing of ubiquitin conjugates, operates in apoptosis induced by γ-irradiation. The proteasome inhibitor peptide aldehyde, MG132, efficiently induced apoptosis and was also able (at doses lower than those required for apoptosis induction) to potentiate apoptosis induced by DNA damage. Its specificity is suggested by the induction of the ubiquitin (UbB and UbC) and E1 (ubiquitin activating enzyme) genes and by an altered ubiquitination pattern. More selectively, a di-peptide competitor of the 'N-end rule' of ubiquitin dependent protein processing inhibited radiation induced apoptosis. This inhibition is also followed by an altered ubiquitination pattern and by activation of Poly (ADP-ribose) polymerase (PARP). These data strongly suggest that early apoptosis radiation induced events are controlled by ubiquitin-dependent proteolytic processing. (author)

  6. Inhibition of Ubc13-mediated Ubiquitination by GPS2 Regulates Multiple Stages of B Cell Development.

    Science.gov (United States)

    Lentucci, Claudia; Belkina, Anna C; Cederquist, Carly T; Chan, Michelle; Johnson, Holly E; Prasad, Sherry; Lopacinski, Amanda; Nikolajczyk, Barbara S; Monti, Stefano; Snyder-Cappione, Jennifer; Tanasa, Bogdan; Cardamone, M Dafne; Perissi, Valentina

    2017-02-17

    Non-proteolytic ubiquitin signaling mediated by Lys 63 ubiquitin chains plays a critical role in multiple pathways that are key to the development and activation of immune cells. Our previous work indicates that GPS2 (G-protein Pathway Suppressor 2) is a multifunctional protein regulating TNFα signaling and lipid metabolism in the adipose tissue through modulation of Lys 63 ubiquitination events. However, the full extent of GPS2-mediated regulation of ubiquitination and the underlying molecular mechanisms are unknown. Here, we report that GPS2 is required for restricting the activation of TLR and BCR signaling pathways and the AKT/FOXO1 pathway in immune cells based on direct inhibition of Ubc13 enzymatic activity. Relevance of this regulatory strategy is confirmed in vivo by B cell-targeted deletion of GPS2, resulting in developmental defects at multiple stages of B cell differentiation. Together, these findings reveal that GPS2 genomic and non-genomic functions are critical for the development and cellular homeostasis of B cells. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  7. Curcumin ameliorates skeletal muscle atrophy in type 1 diabetic mice by inhibiting protein ubiquitination.

    Science.gov (United States)

    Ono, Taisuke; Takada, Shingo; Kinugawa, Shintaro; Tsutsui, Hiroyuki

    2015-09-01

    What is the central question of this study? We sought to examine whether curcumin could ameliorate skeletal muscle atrophy in diabetic mice by inhibiting protein ubiquitination, inflammatory cytokines and oxidative stress. What is the main finding and its importance? We found that curcumin ameliorated skeletal muscle atrophy in streptozotocin-induced diabetic mice by inhibiting protein ubiquitination without affecting protein synthesis. This favourable effect of curcumin was possibly due to the inhibition of inflammatory cytokines and oxidative stress. Curcumin may be beneficial for the treatment of muscle atrophy in type 1 diabetes mellitus. Skeletal muscle atrophy develops in patients with diabetes mellitus (DM), especially in type 1 DM, which is associated with chronic inflammation. Curcumin, the active ingredient of turmeric, has various biological actions, including anti-inflammatory and antioxidant properties. We hypothesized that curcumin could ameliorate skeletal muscle atrophy in mice with streptozotocin-induced type 1 DM. C57BL/6 J mice were injected with streptozotocin (200 mg kg(-1) i.p.; DM group) or vehicle (control group). Each group of mice was randomly subdivided into two groups of 10 mice each and fed a diet with or without curcumin (1500 mg kg(-1) day(-1)) for 2 weeks. There were significant decreases in body weight, skeletal muscle weight and cellular cross-sectional area of the skeletal muscle in DM mice compared with control mice, and these changes were significantly attenuated in DM+Curcumin mice without affecting plasma glucose and insulin concentrations. Ubiquitination of protein was increased in skeletal muscle from DM mice and decreased in DM+Curcumin mice. Gene expressions of muscle-specific ubiquitin E3 ligase atrogin-1/MAFbx and MuRF1 were increased in DM and inhibited in DM+Curcumin mice. Moreover, nuclear factor-κB activation, concentrations of the inflammatory cytokines tumour necrosis factor-α and interleukin-1β and oxidative

  8. Insulin alleviates degradation of skeletal muscle protein by inhibiting the ubiquitin-proteasome system in septic rats.

    Science.gov (United States)

    Chen, Qiyi; Li, Ning; Zhu, Weiming; Li, Weiqin; Tang, Shaoqiu; Yu, Wenkui; Gao, Tao; Zhang, Juanjuan; Li, Jieshou

    2011-06-03

    Hypercatabolism is common under septic conditions. Skeletal muscle is the main target organ for hypercatabolism, and this phenomenon is a vital factor in the deterioration of recovery in septic patients. In skeletal muscle, activation of the ubiquitin-proteasome system plays an important role in hypercatabolism under septic status. Insulin is a vital anticatabolic hormone and previous evidence suggests that insulin administration inhibits various steps in the ubiquitin-proteasome system. However, whether insulin can alleviate the degradation of skeletal muscle protein by inhibiting the ubiquitin-proteasome system under septic condition is unclear. This paper confirmed that mRNA and protein levels of the ubiquitin-proteasome system were upregulated and molecular markers of skeletal muscle proteolysis (tyrosine and 3-methylhistidine) simultaneously increased in the skeletal muscle of septic rats. Septic rats were infused with insulin at a constant rate of 2.4 mU.kg-1.min-1 for 8 hours. Concentrations of mRNA and proteins of the ubiquitin-proteasome system and molecular markers of skeletal muscle proteolysis were mildly affected. When the insulin infusion dose increased to 4.8 mU.kg-1.min-1, mRNA for ubiquitin, E2-14 KDa, and the C2 subunit were all sharply downregulated. At the same time, the levels of ubiquitinated proteins, E2-14KDa, and the C2 subunit protein were significantly reduced. Tyrosine and 3-methylhistidine decreased significantly. We concluded that the ubiquitin-proteasome system is important skeletal muscle hypercatabolism in septic rats. Infusion of insulin can reverse the detrimental metabolism of skeletal muscle by inhibiting the ubiquitin-proteasome system, and the effect is proportional to the insulin infusion dose.

  9. Formation of distinct inclusion bodies by inhibition of ubiquitin-proteasome and autophagy-lysosome pathways

    International Nuclear Information System (INIS)

    Lee, Junho; Yang, Kyu-Hwan; Joe, Cheol O.; Kang, Seok-Seong

    2011-01-01

    Research highlights: → Distinct inclusion bodies are developed by inhibition of UPP and ALP. → The inclusion bodies differ in morphology, localization and formation process. → The inclusion bodies are distinguishable by the localization of TSC2. → Inhibition of both UPP and ALP simultaneously induces those inclusion bodies. -- Abstract: Accumulation of misfolded proteins is caused by the impairment of protein quality control systems, such as ubiquitin-proteasome pathway (UPP) and autophagy-lysosome pathway (ALP). In this study, the formation of inclusion bodies was examined after the blockade of UPP and/or ALP in A549 cells. UPP inhibition induced a single and large inclusion body localized in microtubule-organizing center. Interestingly, however, ALP inhibition generated dispersed small inclusion bodies in the cytoplasm. Tuberous sclerosis complex 2 was selectively accumulated in the inclusion bodies of UPP-inhibited cells, but not those of ALP-inhibited cells. Blockade of transcription and translation entirely inhibited the formation of inclusion body induced by UPP inhibition, but partially by ALP inhibition. Moreover, the simultaneous inhibition of two protein catabolic pathways independently developed two distinct inclusion bodies within a single cell. These findings clearly demonstrated that dysfunction of each catabolic pathway induced formation and accumulation of unique inclusion bodies on the basis of morphology, localization and formation process in A549 cells.

  10. Formation of distinct inclusion bodies by inhibition of ubiquitin-proteasome and autophagy-lysosome pathways.

    Science.gov (United States)

    Lee, Junho; Yang, Kyu-Hwan; Joe, Cheol O; Kang, Seok-Seong

    2011-01-14

    Accumulation of misfolded proteins is caused by the impairment of protein quality control systems, such as ubiquitin-proteasome pathway (UPP) and autophagy-lysosome pathway (ALP). In this study, the formation of inclusion bodies was examined after the blockade of UPP and/or ALP in A549 cells. UPP inhibition induced a single and large inclusion body localized in microtubule-organizing center. Interestingly, however, ALP inhibition generated dispersed small inclusion bodies in the cytoplasm. Tuberous sclerosis complex 2 was selectively accumulated in the inclusion bodies of UPP-inhibited cells, but not those of ALP-inhibited cells. Blockade of transcription and translation entirely inhibited the formation of inclusion body induced by UPP inhibition, but partially by ALP inhibition. Moreover, the simultaneous inhibition of two protein catabolic pathways independently developed two distinct inclusion bodies within a single cell. These findings clearly demonstrated that dysfunction of each catabolic pathway induced formation and accumulation of unique inclusion bodies on the basis of morphology, localization and formation process in A549 cells. Copyright © 2010 Elsevier Inc. All rights reserved.

  11. Nitric oxide prodrug JS-K inhibits ubiquitin E1 and kills tumor cells retaining wild-type p53.

    Science.gov (United States)

    Kitagaki, J; Yang, Y; Saavedra, J E; Colburn, N H; Keefer, L K; Perantoni, A O

    2009-01-29

    Nitric oxide (NO) is a major effector molecule in cancer prevention. A number of studies have shown that NO prodrug JS-K (O(2)-(2,4-dinitrophenyl) 1-[(4-ethoxycarbonyl)piperazin-1-yl]diazen-1-ium-1,2-diolate) induces apoptotic cell death in vitro and in vivo, indicating that it is a promising new therapeutic for cancer. However, the mechanism of its tumor-killing activity remains unclear. Ubiquitin plays an important role in the regulation of tumorigenesis and cell apoptosis. Our earlier report has shown that inactivation of the ubiquitin system through blocking E1 (ubiquitin-activating enzyme) activity preferentially induces apoptosis in p53-expressing transformed cells. As E1 has an active cysteine residue that could potentially interact with NO, we hypothesized that JS-K could inactivate E1 activity. E1 activity was evaluated by detecting ubiquitin-E1 conjugates through immunoblotting. JS-K strikingly inhibits the ubiquitin-E1 thioester formation in cells in a dose-dependent manner with an IC(50) of approximately 2 microM, whereas a JS-K analog that cannot release NO did not affect these levels in cells. Moreover, JS-K decreases total ubiquitylated proteins and increases p53 levels, which is mainly regulated by ubiquitin and proteasomal degradation. Furthermore, JS-K preferentially induces cell apoptosis in p53-expressing transformed cells. These findings indicate that JS-K inhibits E1 activity and kills transformed cells harboring wild-type p53.

  12. Fab-based inhibitors reveal ubiquitin independent functions for HIV Vif neutralization of APOBEC3 restriction factors.

    Directory of Open Access Journals (Sweden)

    Jennifer M Binning

    2018-01-01

    Full Text Available The lentiviral protein Viral Infectivity Factor (Vif counteracts the antiviral effects of host APOBEC3 (A3 proteins and contributes to persistent HIV infection. Vif targets A3 restriction factors for ubiquitination and proteasomal degradation by recruiting them to a multi-protein ubiquitin E3 ligase complex. Here, we describe a degradation-independent mechanism of Vif-mediated antagonism that was revealed through detailed structure-function studies of antibody antigen-binding fragments (Fabs to the Vif complex. Two Fabs were found to inhibit Vif-mediated A3 neutralization through distinct mechanisms: shielding A3 from ubiquitin transfer and blocking Vif E3 assembly. Combined biochemical, cell biological and structural studies reveal that disruption of Vif E3 assembly inhibited A3 ubiquitination but was not sufficient to restore its packaging into viral particles and antiviral activity. These observations establish that Vif can neutralize A3 family members in a degradation-independent manner. Additionally, this work highlights the potential of Fabs as functional probes, and illuminates how Vif uses a multi-pronged approach involving both degradation dependent and independent mechanisms to suppress A3 innate immunity.

  13. Active site-targeted covalent irreversible inhibitors of USP7 impair the functions of Foxp3+ T-regulatory cells by promoting ubiquitination of Tip60.

    Directory of Open Access Journals (Sweden)

    Feng Wang

    Full Text Available Accumulation of Foxp3+ T-regulatory (Treg cells in the tumor microenvironment is associated with tumor immune evasion and poor patient outcome in the case of many solid tumors. Current therapeutic strategies for blocking Treg functions are not Treg-specific, and display only modest and transient efficacy. Recent studies revealed that ubiquitin-specific protease 7 (USP7 is essential for Treg functions by stabilizing expression of Tip60 and Foxp3, which together are central to the development and maintenance of the Treg cell lineage. Pharmacological inhibition of USP7 is therefore a promising strategy for suppressing Treg functions and promoting anti-tumor immunity. Previously, we reported the P5091 series of small molecule USP7 inhibitors and demonstrated their direct anti-tumor activity in vivo using xenograft models. However, the precise mechanism of action of these compounds was not well defined. In this study, we report the development and characterization of P217564, a second-generation USP7 inhibitor with improved potency and selectivity. P217564 selectively targets the catalytic cleft of USP7 and modifies its active site cysteine (C223 by forming a covalent adduct. Irreversible inhibition of USP7 results in durable downstream biological responses in cells, including down-regulation of Tip60 and consequent impairment of Treg suppressive function. In addition, we demonstrate that both USP7 and various USP7 substrates are subjected to Lys48-mediated ubiquitin modification, consistent with increased proteasomal degradation of these proteins because of USP7 inhibition.

  14. Inhibition of xanthine oxidase by allopurinol prevents skeletal muscle atrophy: role of p38 MAPKinase and E3 ubiquitin ligases.

    Directory of Open Access Journals (Sweden)

    Frederic Derbre

    Full Text Available Alterations in muscle play an important role in common diseases and conditions. Reactive oxygen species (ROS are generated during hindlimb unloading due, at least in part, to the activation of xanthine oxidase (XO. The major aim of this study was to determine the mechanism by which XO activation causes unloading-induced muscle atrophy in rats, and its possible prevention by allopurinol, a well-known inhibitor of this enzyme. For this purpose we studied one of the main redox sensitive signalling cascades involved in skeletal muscle atrophy i.e. p38 MAPKinase, and the expression of two well known muscle specific E3 ubiquitin ligases involved in proteolysis, the Muscle atrophy F-Box (MAFbx; also known as atrogin-1 and Muscle RING (Really Interesting New Gene Finger-1 (MuRF-1. We found that hindlimb unloading induced a significant increase in XO activity and in the protein expression of the antioxidant enzymes CuZnSOD and Catalase in skeletal muscle. The most relevant new fact reported in this paper is that inhibition of XO with allopurinol, a drug widely used in clinical practice, prevents soleus muscle atrophy by ~20% after hindlimb unloading. This was associated with the inhibition of the p38 MAPK-MAFbx pathway. Our data suggest that XO was involved in the loss of muscle mass via the activation of the p38MAPK-MAFbx pathway in unloaded muscle atrophy. Thus, allopurinol may have clinical benefits to combat skeletal muscle atrophy in bedridden, astronauts, sarcopenic, and cachexic patients.

  15. Complementary genetic screens identify the E3 ubiquitin ligase CBLC, as a modifier of PARP inhibitor sensitivity

    Czech Academy of Sciences Publication Activity Database

    Frankum, J.; Moudrý, P.; Brough, R.; Hodný, Zdeněk; Ashworth, A.; Bartek, Jiří; Lord, C.J.

    2015-01-01

    Roč. 6, č. 13 (2015), s. 10746-10758 ISSN 1949-2553 R&D Projects: GA ČR GA13-17555S EU Projects: European Commission HEALTH-F2-2010-259893 Grant - others:Lundbeck Foundation(DK) R93-A8990; Danish Council for Independent Research(DK) DFF-1331-00262 Institutional support: RVO:68378050 Keywords : DNA damage response * ubiquitin-proteasome system * RNA interference screens * PARP inhibitors * CBLC Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 5.008, year: 2015

  16. N-myristoylated ubiquitin ligase Cbl-b inhibitor prevents on glucocorticoid-induced atrophy in mouse skeletal muscle.

    Science.gov (United States)

    Ochi, Arisa; Abe, Tomoki; Nakao, Reiko; Yamamoto, Yoriko; Kitahata, Kanako; Takagi, Marina; Hirasaka, Katsuya; Ohno, Ayako; Teshima-Kondo, Shigetada; Taesik, Gwag; Choi, Inho; Kawamura, Tomoyuki; Nemoto, Hisao; Mukai, Rie; Terao, Junji; Nikawa, Takeshi

    2015-03-15

    A DGpYMP peptide mimetic of tyrosine(608)-phosphorylated insulin receptor substrate-1 (IRS-1), named Cblin, was previously shown to significantly inhibit Cbl-b-mediated IRS-1 ubiquitination. In the present study, we developed N-myristoylated Cblin and investigated whether it was effective in preventing glucocorticoid-induced muscle atrophy. Using HEK293 cells overexpressing Cbl-b, IRS-1 and ubiquitin, we showed that the 50% inhibitory concentrations of Cbl-b-mediated IRS-1 ubiquitination by N-myristoylated Cblin and Cblin were 30 and 120 μM, respectively. Regarding the DEX-induced atrophy of C2C12 myotubes, N-myristoylated Cblin was more effective than Cblin for inhibiting the DEX-induced decreases in C2C12 myotube diameter and IRS-1 degradation. The inhibitory efficacy of N-myristoylated Cblin on IRS-1 ubiquitination in C2C12 myotubes was approximately fourfold larger than that of Cblin. Furthermore, N-myristoylation increased the incorporation of Cblin into HEK293 cells approximately 10-folds. Finally, we demonstrated that N-myristoylated Cblin prevented the wet weight loss, IRS-1 degradation, and MAFbx/atrogin-1 and MuRF-1 expression in gastrocnemius muscle of DEX-treated mice approximately fourfold more effectively than Cblin. Taken together, these results suggest that N-myristoylated Cblin prevents DEX-induced skeletal muscle atrophy in vitro and in vivo, and that N-myristoylated Cblin more effectively prevents muscle atrophy than unmodified Cblin. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Histone Deacetylase Inhibitors Increase p27Kip1 by Affecting Its Ubiquitin-Dependent Degradation through Skp2 Downregulation

    Directory of Open Access Journals (Sweden)

    Adriana Borriello

    2016-01-01

    Full Text Available Histone deacetylase inhibitors (HDACIs represent an intriguing class of pharmacologically active compounds. Currently, some HDACIs are FDA approved for cancer therapy and many others are in clinical trials, showing important clinical activities at well tolerated doses. HDACIs also interfere with the aging process and are involved in the control of inflammation and oxidative stress. In vitro, HDACIs induce different cellular responses including growth arrest, differentiation, and apoptosis. Here, we evaluated the effects of HDACIs on p27Kip1, a key cyclin-dependent kinase inhibitor (CKI. We observed that HDACI-dependent antiproliferative activity is associated with p27Kip1 accumulation due to a reduced protein degradation. p27Kip1 removal requires a preliminary ubiquitination step due to the Skp2-SCF E3 ligase complex. We demonstrated that HDACIs increase p27Kip1 stability through downregulation of Skp2 protein levels. Skp2 decline is only partially due to a reduced Skp2 gene expression. Conversely, the protein decrease is more profound and enduring compared to the changes of Skp2 transcript. This argues for HDACIs effects on Skp2 protein posttranslational modifications and/or on its removal. In summary, we demonstrate that HDACIs increase p27Kip1 by hampering its nuclear ubiquitination/degradation. The findings might be of relevance in the phenotypic effects of these compounds, including their anticancer and aging-modulating activities.

  18. Inflammatory Signaling by NOD-RIPK2 Is Inhibited by Clinically Relevant Type II Kinase Inhibitors.

    Science.gov (United States)

    Canning, Peter; Ruan, Qui; Schwerd, Tobias; Hrdinka, Matous; Maki, Jenny L; Saleh, Danish; Suebsuwong, Chalada; Ray, Soumya; Brennan, Paul E; Cuny, Gregory D; Uhlig, Holm H; Gyrd-Hansen, Mads; Degterev, Alexei; Bullock, Alex N

    2015-09-17

    RIPK2 mediates pro-inflammatory signaling from the bacterial sensors NOD1 and NOD2, and is an emerging therapeutic target in autoimmune and inflammatory diseases. We observed that cellular RIPK2 can be potently inhibited by type II inhibitors that displace the kinase activation segment, whereas ATP-competitive type I inhibition was only poorly effective. The most potent RIPK2 inhibitors were the US Food and Drug Administration-approved drugs ponatinib and regorafenib. Their mechanism of action was independent of NOD2 interaction and involved loss of downstream kinase activation as evidenced by lack of RIPK2 autophosphorylation. Notably, these molecules also blocked RIPK2 ubiquitination and, consequently, inflammatory nuclear factor κB signaling. In monocytes, the inhibitors selectively blocked NOD-dependent tumor necrosis factor production without affecting lipopolysaccharide-dependent pathways. We also determined the first crystal structure of RIPK2 bound to ponatinib, and identified an allosteric site for inhibitor development. These results highlight the potential for type II inhibitors to treat indications of RIPK2 activation as well as inflammation-associated cancers. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. End-joining inhibition at telomeres requires the translocase and polySUMO-dependent ubiquitin ligase Uls1.

    Science.gov (United States)

    Lescasse, Rachel; Pobiega, Sabrina; Callebaut, Isabelle; Marcand, Stéphane

    2013-03-20

    In eukaryotes, permanent inhibition of the non-homologous end joining (NHEJ) repair pathway at telomeres ensures that chromosome ends do not fuse. In budding yeast, binding of Rap1 to telomere repeats establishes NHEJ inhibition. Here, we show that the Uls1 protein is required for the maintenance of NHEJ inhibition at telomeres. Uls1 protein is a non-essential Swi2/Snf2-related translocase and a Small Ubiquitin-related Modifier (SUMO)-Targeted Ubiquitin Ligase (STUbL) with unknown targets. Loss of Uls1 results in telomere-telomere fusions. Uls1 requirement is alleviated by the absence of poly-SUMO chains and by rap1 alleles lacking SUMOylation sites. Furthermore, Uls1 limits the accumulation of Rap1 poly-SUMO conjugates. We propose that one of Uls1 functions is to clear non-functional poly-SUMOylated Rap1 molecules from telomeres to ensure the continuous efficiency of NHEJ inhibition. Since Uls1 is the only known STUbL with a translocase activity, it can be the general molecular sweeper for the clearance of poly-SUMOylated proteins on DNA in eukaryotes.

  20. Sorafenib enhances proteasome inhibitor-mediated cytotoxicity via inhibition of unfolded protein response and keratin phosphorylation

    International Nuclear Information System (INIS)

    Honma, Yuichi; Harada, Masaru

    2013-01-01

    Hepatocellular carcinoma (HCC) is highly resistant to conventional systemic therapies and prognosis for advanced HCC patients remains poor. Recent studies of the molecular mechanisms responsible for tumor initiation and progression have identified several potential molecular targets in HCC. Sorafenib is a multi-kinase inhibitor shown to have survival benefits in advanced HCC. It acts by inhibiting the serine/threonine kinases and the receptor type tyrosine kinases. In preclinical experiments sorafenib had anti-proliferative activity in hepatoma cells and it reduced tumor angiogenesis and increased apoptosis. Here, we demonstrate for the first time that the cytotoxic mechanisms of sorafenib include its inhibitory effects on protein ubiquitination, unfolded protein response (UPR) and keratin phosphorylation in response to endoplasmic reticulum (ER) stress. Moreover, we show that combined treatment with sorafenib and proteasome inhibitors (PIs) synergistically induced a marked increase in cell death in hepatoma- and hepatocyte-derived cells. These observations may open the way to potentially interesting treatment combinations that may augment the effect of sorafenib, possibly including drugs that promote ER stress. Because sorafenib blocked the cellular defense mechanisms against hepatotoxic injury not only in hepatoma cells but also in hepatocyte-derived cells, we must be careful to avoid severe liver injury. -- Graphical abstract: Display Omitted -- Highlights: •We examined the cytotoxic mechanisms of sorafenib in hepatoma cells. •Sorafenib induces cell death via apoptotic and necrotic fashion. •Sorafenib inhibits protein ubiquitination and unfolded protein response. •Autophagy induced by sorafenib may affect its cytotoxicity. •Sorafenib inhibits keratin phosphorylation and cytoplasmic inclusion formation

  1. Dietary flavonoids bind to mono-ubiquitinated annexin A1 in nuclei, and inhibit chemical induced mutagenesis

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, Fusao, E-mail: fhirata@wayne.edu; Harada, Takasuke; Corcoran, George B.; Hirata, Aiko

    2014-01-15

    Highlight: • Nuclear mono-ubiquitinated annexin A1 is involved in DNA damage induced mutagenesis. • Dietary flavonoids bind to and inhibit purified mono-ubiquitinated annexin A1 helicase. • Dietary flavonoids show anti-mutagenic action. • Annexin A1 may serve as a putative target of cancer chemoprevention by flavonoids. - Abstract: In order to investigate the mechanisms of anti-mutagenic action by dietary flavonoids, we investigated if they inhibit mutation of the thymidine kinase (tk) gene in L5178Ytk(±) lymphoma cells. Silibinin, quercetin and genistein suppressed mutation of the tk gene induced in L5178Ytk(±) lymphoma cells by methyl methanesulfonate (MMS) and As{sup 3+}. Flavone and flavonol were less effective. To establish that mutation of the tk gene in L5178Ytk(±) lymphoma cells by MMS and As{sup 3+} is mediated through mono-ubiquitinated annexin A1, L5178Ytk(±) lymphoma cells were treated with annexin A1 anti-sense oligonucleotide. The treatment reduced mRNA as well as protein levels of annexin A1, and suppressed mutation of the tk gene. Nuclear extracts from L5178Ytk(±) lymphoma cells catalyzed translesion DNA synthesis with an oligonucleotide template containing 8-oxo-guanosine in an annexin A1 dependent manner. This translesion DNA synthesis was inhibited by the anti-mutagenic flavonoids, silibinin, quercetin and genistein, in a concentration dependent manner, but only slightly by flavone and flavonol. Because these observations implicate involvement of annexin A1 in mutagenesis, we examined if flavonoids suppress nuclear annexin A1 helicase activity. Silibinin, quercetin and genistein inhibited ssDNA binding, DNA chain annealing and DNA unwinding activities of purified nuclear mono-ubiquitinated annexin A1. Flavone and flavonol were ineffective. The apparent direct binding of anti-mutagenic flavonoids to the annexin A1 molecule was supported by fluorescence quenching. Taken together, these findings illustrate that nuclear annexin A1 may be

  2. Dietary flavonoids bind to mono-ubiquitinated annexin A1 in nuclei, and inhibit chemical induced mutagenesis

    International Nuclear Information System (INIS)

    Hirata, Fusao; Harada, Takasuke; Corcoran, George B.; Hirata, Aiko

    2014-01-01

    Highlight: • Nuclear mono-ubiquitinated annexin A1 is involved in DNA damage induced mutagenesis. • Dietary flavonoids bind to and inhibit purified mono-ubiquitinated annexin A1 helicase. • Dietary flavonoids show anti-mutagenic action. • Annexin A1 may serve as a putative target of cancer chemoprevention by flavonoids. - Abstract: In order to investigate the mechanisms of anti-mutagenic action by dietary flavonoids, we investigated if they inhibit mutation of the thymidine kinase (tk) gene in L5178Ytk(±) lymphoma cells. Silibinin, quercetin and genistein suppressed mutation of the tk gene induced in L5178Ytk(±) lymphoma cells by methyl methanesulfonate (MMS) and As 3+ . Flavone and flavonol were less effective. To establish that mutation of the tk gene in L5178Ytk(±) lymphoma cells by MMS and As 3+ is mediated through mono-ubiquitinated annexin A1, L5178Ytk(±) lymphoma cells were treated with annexin A1 anti-sense oligonucleotide. The treatment reduced mRNA as well as protein levels of annexin A1, and suppressed mutation of the tk gene. Nuclear extracts from L5178Ytk(±) lymphoma cells catalyzed translesion DNA synthesis with an oligonucleotide template containing 8-oxo-guanosine in an annexin A1 dependent manner. This translesion DNA synthesis was inhibited by the anti-mutagenic flavonoids, silibinin, quercetin and genistein, in a concentration dependent manner, but only slightly by flavone and flavonol. Because these observations implicate involvement of annexin A1 in mutagenesis, we examined if flavonoids suppress nuclear annexin A1 helicase activity. Silibinin, quercetin and genistein inhibited ssDNA binding, DNA chain annealing and DNA unwinding activities of purified nuclear mono-ubiquitinated annexin A1. Flavone and flavonol were ineffective. The apparent direct binding of anti-mutagenic flavonoids to the annexin A1 molecule was supported by fluorescence quenching. Taken together, these findings illustrate that nuclear annexin A1 may be a novel

  3. The E3 ubiquitin ligases β-TrCP and FBXW7 cooperatively mediates GSK3-dependent Mcl-1 degradation induced by the Akt inhibitor API-1, resulting in apoptosis.

    Science.gov (United States)

    Ren, Hui; Koo, Junghui; Guan, Baoxiang; Yue, Ping; Deng, Xingming; Chen, Mingwei; Khuri, Fadlo R; Sun, Shi-Yong

    2013-11-22

    The novel Akt inhibitor, API-1, induces apoptosis through undefined mechanisms. The current study focuses on revealing the mechanisms by which API-1 induces apoptosis. API-1 rapidly and potently reduced the levels of Mcl-1 primarily in API-1-senstive lung cancer cell lines. Ectopic expression of Mcl-1 protected cells from induction of apoptosis by API-1. API-1 treatment decreased the half-life of Mcl-1, whereas inhibition of the proteasome with MG132 rescued Mcl-1 reduction induced by API-1. API-1 decreased Mcl-1 levels accompanied with a rapid increase in Mcl-1 phosphorylation (S159/T163). Moreover, inhibition of GSK3 inhibited Mcl-1 phosphorylation and reduction induced by API-1 and antagonized the effect of API-1 on induction of apoptosis. Knockdown of either FBXW7 or β-TrCP alone, both of which are E3 ubiquitin ligases involved in Mcl-1 degradation, only partially rescued Mcl-1 reduction induced by API-1. However, double knockdown of both E3 ubiquitin ligases enhanced the rescue of API-1-induced Mcl-1 reduction. API-1 induces GSK3-dependent, β-TrCP- and FBXW7-mediated Mcl-1 degradation, resulting in induction of apoptosis.

  4. The chimeric ubiquitin ligase SH2-U-box inhibits the growth of imatinib-sensitive and resistant CML by targeting the native and T315I-mutant BCR-ABL.

    Science.gov (United States)

    Ru, Yi; Wang, Qinhao; Liu, Xiping; Zhang, Mei; Zhong, Daixing; Ye, Mingxiang; Li, Yuanchun; Han, Hua; Yao, Libo; Li, Xia

    2016-06-22

    Chronic myeloid leukemia (CML) is characterized by constitutively active fusion protein tyrosine kinase BCR-ABL. Although the tyrosine kinase inhibitor (TKI) against BCR-ABL, imatinib, is the first-line therapy for CML, acquired resistance almost inevitably emerges. The underlying mechanism are point mutations within the BCR-ABL gene, among which T315I is notorious because it resists to almost all currently available inhibitors. Here we took use of a previously generated chimeric ubiquitin ligase, SH2-U-box, in which SH2 from the adaptor protein Grb2 acts as a binding domain for activated BCR-ABL, while U-box from CHIP functions as an E3 ubiquitin ligase domain, so as to target the ubiquitination and degradation of both native and T315I-mutant BCR-ABL. As such, SH2-U-box significantly inhibited proliferation and induced apoptosis in CML cells harboring either the wild-type or T315I-mutant BCR-ABL (K562 or K562R), with BCR-ABL-dependent signaling pathways being repressed. Moreover, SH2-U-box worked in concert with imatinib in K562 cells. Importantly, SH2-U-box-carrying lentivirus could markedly suppress the growth of K562-xenografts in nude mice or K562R-xenografts in SCID mice, as well as that of primary CML cells. Collectively, by degrading the native and T315I-mutant BCR-ABL, the chimeric ubiquitin ligase SH2-U-box may serve as a potential therapy for both imatinib-sensitive and resistant CML.

  5. Inhibition of matrix metalloproteinase-2 by PARP inhibitors

    International Nuclear Information System (INIS)

    Nicolescu, Adrian C.; Holt, Andrew; Kandasamy, Arulmozhi D.; Pacher, Pal; Schulz, Richard

    2009-01-01

    Matrix metalloproteinase-2 (MMP-2), a ubiquitously expressed zinc-dependent endopeptidase, and poly(ADP-ribosyl) polymerase (PARP), a nuclear enzyme regulating DNA repair, are activated by nitroxidative stress associated with various pathologies. As MMP-2 plays a detrimental role in heart injuries resulting from enhanced nitroxidative stress, where PARP and MMP inhibitors are beneficial, we hypothesized that PARP inhibitors may affect MMP-2 activity. Using substrate degradation assays to determine MMP-2 activity we found that four PARP inhibitors (3-AB, PJ-34, 5-AIQ, and EB-47) inhibited 64 kDa MMP-2 in a concentration-dependent manner. The IC 50 values of PJ-34 and 5-AIQ were in the high micromolar range and comparable to those of known MMP-2 inhibitors doxycycline, minocycline or o-phenanthroline, whereas those for 3-AB and EB-47 were in the millimolar range. Co-incubation of PARP inhibitors with doxycycline showed an additive inhibition of MMP-2 that was significant for 3-AB alone. These data demonstrate that the protective effects of some PARP inhibitors may include inhibition of MMP-2 activity.

  6. Inhibition of matrix metalloproteinase-2 by PARP inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Nicolescu, Adrian C.; Holt, Andrew; Kandasamy, Arulmozhi D. [Departments of Pharmacology and Pediatrics, Cardiovascular Research Centre, University of Alberta, Edmonton, Alta., Canada T6G 2S2 (Canada); Pacher, Pal [National Institutes of Health, NIAAA, Laboratory of Physiologic Studies, Bethesda, MD (United States); Schulz, Richard, E-mail: richard.schulz@ualberta.ca [Departments of Pharmacology and Pediatrics, Cardiovascular Research Centre, University of Alberta, Edmonton, Alta., Canada T6G 2S2 (Canada)

    2009-10-02

    Matrix metalloproteinase-2 (MMP-2), a ubiquitously expressed zinc-dependent endopeptidase, and poly(ADP-ribosyl) polymerase (PARP), a nuclear enzyme regulating DNA repair, are activated by nitroxidative stress associated with various pathologies. As MMP-2 plays a detrimental role in heart injuries resulting from enhanced nitroxidative stress, where PARP and MMP inhibitors are beneficial, we hypothesized that PARP inhibitors may affect MMP-2 activity. Using substrate degradation assays to determine MMP-2 activity we found that four PARP inhibitors (3-AB, PJ-34, 5-AIQ, and EB-47) inhibited 64 kDa MMP-2 in a concentration-dependent manner. The IC{sub 50} values of PJ-34 and 5-AIQ were in the high micromolar range and comparable to those of known MMP-2 inhibitors doxycycline, minocycline or o-phenanthroline, whereas those for 3-AB and EB-47 were in the millimolar range. Co-incubation of PARP inhibitors with doxycycline showed an additive inhibition of MMP-2 that was significant for 3-AB alone. These data demonstrate that the protective effects of some PARP inhibitors may include inhibition of MMP-2 activity.

  7. Inhibition of Siah2 Ubiquitin Ligase by Vitamin K3 Attenuates Chronic Myeloid Leukemia Chemo-Resistance in Hypoxic Microenvironment.

    Science.gov (United States)

    Huang, Jixian; Lu, Ziyuan; Xiao, Yajuan; He, Bolin; Pan, Chengyun; Zhou, Xuan; Xu, Na; Liu, Xiaoli

    2018-02-05

    BACKGROUND A hypoxic microenvironment is associated with resistance to tyrosine kinase inhibitors (TKIs) and a poor prognosis in chronic myeloid leukemia (CML). The E3 ubiquitin ligase Siah2 plays a vital role in the regulation of hypoxia response, as well as in leukemogenesis. However, the role of Siah2 in CML resistance is unclear, and it is unknown whether vitaminK3 (a Siah2 inhibitor) can improve the chemo-sensitivity of CML cells in a hypoxic microenvironment. MATERIAL AND METHODS The expression of Siah2 was detected in CML patients (CML-CP and CML-BC), K562 cells, and K562-imatinib-resistant cells (K562-R cells). We measured the expression of PHD3, HIF-1α, and VEGF in both cell lines under normoxia and hypoxic conditions, and the degree of leukemic sensitivity to imatinib and VitaminK3 were evaluated. RESULTS Siah2 was overexpressed in CML-BC patients (n=9) as compared to CML-CP patients (n=13). Similarly, K562-imatinib-resistant cells (K562-R cells) showed a significantly higher expression of Siah2 as compared to K562 cells in a hypoxic microenvironment. Compared to normoxia, under hypoxic conditions, both cell lines had lower PHD3, higher HIF-1α, and higher VEGF expression. Additionally, Vitamin K3 (an inhibitor of Siah2) reversed these changes and promoted a higher degree of leukemic sensitivity to imatinib. CONCLUSIONS Our findings indicate that the Siah2-PHD3- HIF-1α-VEGF axis is an important hypoxic signaling pathway in a leukemic microenvironment. An inhibitor of Siah2, combined with TKIs, might be a promising therapy for relapsing and refractory CML patients.

  8. Proton pump inhibitors inhibit pancreatic secretion

    DEFF Research Database (Denmark)

    Wang, Jing; Barbuskaite, Dagne; Tozzi, Marco

    2015-01-01

    +/K+-ATPases are expressed and functional in human pancreatic ducts and whether proton pump inhibitors (PPIs) have effect on those. Here we show that the gastric HKα1 and HKβ subunits (ATP4A; ATP4B) and non-gastric HKα2 subunits (ATP12A) of H+/K+-ATPases are expressed in human pancreatic cells. Pumps have similar...... of major ions in secretion follow similar excretory curves in control and PPI treated animals. In addition to HCO3-, pancreas also secretes K+. In conclusion, this study calls for a revision of the basic model for HCO3- secretion. We propose that proton transport is driving secretion, and that in addition...

  9. Calmodulin promotes matrix metalloproteinase 9 production and cell migration by inhibiting the ubiquitination and degradation of TBC1D3 oncoprotein in human breast cancer cells.

    Science.gov (United States)

    Zhao, Huzi; Zhang, Lina; Zhang, Yongchen; Zhao, Lei; Wan, Qing; Wang, Bei; Bu, Xiaodong; Wan, Meiling; Shen, Chuanlu

    2017-05-30

    The hominoid oncoprotein TBC1D3 enhances growth factor (GF) signaling and GF signaling, conversely, induces the ubiquitination and subsequent degradation of TBC1D3. However, little is known regarding the regulation of this degradation, and the role of TBC1D3 in the progression of tumors has also not been defined. In the present study, we demonstrated that calmodulin (CaM), a ubiquitous cellular calcium sensor, specifically interacted with TBC1D3 in a Ca2+-dependent manner and inhibited GF signaling-induced ubiquitination and degradation of the oncoprotein in both cytoplasm and nucleus of human breast cancer cells. The CaM-interacting site of TBC1D3 was mapped to amino acids 157~171, which comprises two 1-14 hydrophobic motifs and one lysine residue (K166). Deletion of these motifs was shown to abolish interaction between TBC1D3 and CaM. Surprisingly, this deletion mutation caused inability of GF signaling to induce the ubiquitination and subsequent degradation of TBC1D3. In agreement with this, we identified lysine residue 166 within the CaM-interacting motifs of TBC1D3 as the actual site for the GF signaling-induced ubiquitination using mutational analysis. Point mutation of this lysine residue exhibited the same effect on TBC1D3 as the deletion mutant, suggesting that CaM inhibits GF signaling-induced degradation of TBC1D3 by occluding its ubiquitination at K166. Notably, we found that TBC1D3 promoted the expression and activation of MMP-9 and the migration of MCF-7 cells. Furthermore, interaction with CaM considerably enhanced such effect of TBC1D3. Taken together, our work reveals a novel model by which CaM promotes cell migration through inhibiting the ubiquitination and degradation of TBC1D3.

  10. Maintaining glycogen synthase kinase-3 activity is critical for mTOR kinase inhibitors to inhibit cancer cell growth.

    Science.gov (United States)

    Koo, Junghui; Yue, Ping; Gal, Anthony A; Khuri, Fadlo R; Sun, Shi-Yong

    2014-05-01

    mTOR kinase inhibitors that target both mTORC1 and mTORC2 are being evaluated in cancer clinical trials. Here, we report that glycogen synthase kinase-3 (GSK3) is a critical determinant for the therapeutic response to this class of experimental drugs. Pharmacologic inhibition of GSK3 antagonized their suppressive effects on the growth of cancer cells similarly to genetic attenuation of GSK3. Conversely, expression of a constitutively activated form of GSK3β sensitized cancer cells to mTOR inhibition. Consistent with these findings, higher basal levels of GSK3 activity in a panel of human lung cancer cell lines correlated with more efficacious responses. Mechanistic investigations showed that mTOR kinase inhibitors reduced cyclin D1 levels in a GSK3β-dependent manner, independent of their effects on suppressing mTORC1 signaling and cap binding. Notably, selective inhibition of mTORC2 triggered proteasome-mediated cyclin D1 degradation, suggesting that mTORC2 blockade is responsible for GSK3-dependent reduction of cyclin D1. Silencing expression of the ubiquitin E3 ligase FBX4 rescued this reduction, implicating FBX4 in mediating this effect of mTOR inhibition. Together, our findings define a novel mechanism by which mTORC2 promotes cell growth, with potential implications for understanding the clinical action of mTOR kinase inhibitors. ©2014 AACR.

  11. Shigella IpaH0722 E3 Ubiquitin Ligase Effector Targets TRAF2 to Inhibit PKC–NF-κB Activity in Invaded Epithelial Cells

    Science.gov (United States)

    Ashida, Hiroshi; Nakano, Hiroyasu; Sasakawa, Chihiro

    2013-01-01

    NF-κB plays a central role in modulating innate immune responses to bacterial infections. Therefore, many bacterial pathogens deploy multiple mechanisms to counteract NF-κB activation. The invasion of and subsequent replication of Shigella within epithelial cells is recognized by various pathogen recognition receptors as pathogen-associated molecular patterns. These receptors trigger innate defense mechanisms via the activation of the NF-κB signaling pathway. Here, we show the inhibition of the NF-κB activation by the delivery of the IpaH E3 ubiquitin ligase family member IpaH0722 using Shigella's type III secretion system. IpaH0722 dampens the acute inflammatory response by preferentially inhibiting the PKC-mediated activation of NF-κB by ubiquitinating TRAF2, a molecule downstream of PKC, and by promoting its proteasome-dependent degradation. PMID:23754945

  12. An extract of Artemisia dracunculus L. inhibits ubiquitin-proteasome activity and preserves skeletal muscle mass in a murine model of diabetes.

    Directory of Open Access Journals (Sweden)

    Heather Kirk-Ballard

    Full Text Available Impaired insulin signaling is a key feature of type 2 diabetes and is associated with increased ubiquitin-proteasome-dependent protein degradation in skeletal muscle. An extract of Artemisia dracunculus L. (termed PMI5011 improves insulin action by increasing insulin signaling in skeletal muscle. We sought to determine if the effect of PMI5011 on insulin signaling extends to regulation of the ubiquitin-proteasome system. C2C12 myotubes and the KK-A(y murine model of type 2 diabetes were used to evaluate the effect of PMI5011 on steady-state levels of ubiquitylation, proteasome activity and expression of Atrogin-1 and MuRF-1, muscle-specific ubiquitin ligases that are upregulated with impaired insulin signaling. Our results show that PMI5011 inhibits proteasome activity and steady-state ubiquitylation levels in vitro and in vivo. The effect of PMI5011 is mediated by PI3K/Akt signaling and correlates with decreased expression of Atrogin-1 and MuRF-1. Under in vitro conditions of hormonal or fatty acid-induced insulin resistance, PMI5011 improves insulin signaling and reduces Atrogin-1 and MuRF-1 protein levels. In the KK-A(y murine model of type 2 diabetes, skeletal muscle ubiquitylation and proteasome activity is inhibited and Atrogin-1 and MuRF-1 expression is decreased by PMI5011. PMI5011-mediated changes in the ubiquitin-proteasome system in vivo correlate with increased phosphorylation of Akt and FoxO3a and increased myofiber size. The changes in Atrogin-1 and MuRF-1 expression, ubiquitin-proteasome activity and myofiber size modulated by PMI5011 in the presence of insulin resistance indicate the botanical extract PMI5011 may have therapeutic potential in the preservation of muscle mass in type 2 diabetes.

  13. Renoprotective Effects of SGLT2 Inhibitors: Beyond Glucose Reabsorption Inhibition.

    Science.gov (United States)

    Tsimihodimos, V; Filippatos, T D; Filippas-Ntekouan, S; Elisaf, M

    2017-01-01

    Sodium-glucose co-transporter 2 (SGLT2) inhibitors are a new class of antidiabetic drugs that inhibit glucose and sodium reabsorption at proximal tubules. These drugs may exhibit renoprotective properties, since they prevent the deterioration of the glomerular filtration rate and reduce the degree of albuminuria in patients with diabetes-associated kidney disease. In this review we consider the pathophysiologic mechanisms that have been recently implicated in the renoprotective properties of SGLT2 inhibitors. The beneficial effects of SGLT2 inhibitors on the conventional risk factors for kidney disease (such as blood pressure, hyperglycaemia, body weight and serum uric acid levels) may explain, at least in part, the observed renal-protecting properties of these compounds. However, it has been hypothesized that the most important mechanisms for this phenomenon include the reduction in the intraglomerular pressure, the changes in the local and systemic degree of activation of the renin-aldosterone-angiotensin system and a shift in renal fuel consumption towards more efficient energy substrates such as ketone bodies. The beneficial effects of SGLT2 inhibitors on various aspects of renal function make them an attractive choice in patients with (and possibly without) diabetes-associated renal impairment. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  14. Ubiquitin-specific protease 14 regulates cell proliferation and apoptosis in oral squamous cell carcinoma.

    Science.gov (United States)

    Chen, Xiangyun; Wu, Jingjing; Chen, Yitian; Ye, Dongxia; Lei, Hu; Xu, Hanzhang; Yang, Li; Wu, Yingli; Gu, Wenli

    2016-10-01

    Ubiquitin-specific protease 14, a deubiquitinating enzyme, has been implicated in the tumorigenesis and progression of several cancers, but its role in oral squamous cell carcinoma remains to be elucidated. The aim of this study was to explore the expression pattern and roles of Ubiquitin-specific protease 14 in the occurrence and development of oral squamous cell carcinoma. Interestingly, Ubiquitin-specific protease 14 was overexpressed in oral cancer tissues and cell lines at both mRNA and protein levels. b-AP15, a specific inhibitor of Ubiquitin-specific protease 14, significantly inhibited the growth of cancer cells and increased cell apoptosis in a dose-dependent manner. Moreover, knockdown of Ubiquitin-specific protease 14 by shRNA significantly inhibited the proliferation and migration of cancer cells in vitro. Finally, using a xenograft mouse model of oral squamous cell carcinoma, knockdown of Ubiquitin-specific protease 14 markedly inhibited tumor growth and triggered the cancer cell apoptosis in vivo, supporting previous results. In conclusion, for the first time we have demonstrated the expression pattern of Ubiquitin-specific protease 14 in oral squamous cell carcinoma and verified a relationship with tumor growth and metastasis. These results may highlight new therapeutic strategies for tumor treatment, application of Ubiquitin-specific protease 14 selective inhibitor, such as b-AP15, or knockdown by shRNA. Collectively, Ubiquitin-specific protease 14 could be a potential therapeutic target for oral squamous cell carcinoma patients. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Novel mechanisms to inhibit HIV reservoir seeding using Jak inhibitors.

    Directory of Open Access Journals (Sweden)

    Christina Gavegnano

    2017-12-01

    Full Text Available Despite advances in the treatment of HIV infection with ART, elucidating strategies to overcome HIV persistence, including blockade of viral reservoir establishment, maintenance, and expansion, remains a challenge. T cell homeostasis is a major driver of HIV persistence. Cytokines involved in regulating homeostasis of memory T cells, the major hub of the HIV reservoir, trigger the Jak-STAT pathway. We evaluated the ability of tofacitinib and ruxolitinib, two FDA-approved Jak inhibitors, to block seeding and maintenance of the HIV reservoir in vitro. We provide direct demonstration for involvement of the Jak-STAT pathway in HIV persistence in vivo, ex vivo, and in vitro; pSTAT5 strongly correlates with increased levels of integrated viral DNA in vivo, and in vitro Jak inhibitors reduce the frequency of CD4+ T cells harboring integrated HIV DNA. We show that Jak inhibitors block viral production from infected cells, inhibit γ-C receptor cytokine (IL-15-induced viral reactivation from latent stores thereby preventing transmission of infectious particles to bystander activated T cells. These results show that dysregulation of the Jak-STAT pathway is associated with viral persistence in vivo, and that Jak inhibitors target key events downstream of γ-C cytokine (IL-2, IL-7 and IL-15 ligation to their receptors, impacting the magnitude of the HIV reservoir in all memory CD4 T cell subsets in vitro and ex vivo. Jak inhibitors represent a therapeutic modality to prevent key events of T cell activation that regulate HIV persistence and together, specific, potent blockade of these events may be integrated to future curative strategies.

  16. DNA methyltransferase inhibitor CDA-II inhibits myogenic differentiation

    International Nuclear Information System (INIS)

    Chen, Zirong; Jin, Guorong; Lin, Shuibin; Lin, Xiumei; Gu, Yumei; Zhu, Yujuan; Hu, Chengbin; Zhang, Qingjiong; Wu, Lizi; Shen, Huangxuan

    2012-01-01

    Highlights: ► CDA-II inhibits myogenic differentiation in a dose-dependent manner. ► CDA-II repressed expression of muscle transcription factors and structural proteins. ► CDA-II inhibited proliferation and migration of C2C12 myoblasts. -- Abstract: CDA-II (cell differentiation agent II), isolated from healthy human urine, is a DNA methyltransferase inhibitor. Previous studies indicated that CDA-II played important roles in the regulation of cell growth and certain differentiation processes. However, it has not been determined whether CDA-II affects skeletal myogenesis. In this study, we investigated effects of CDA-II treatment on skeletal muscle progenitor cell differentiation, migration and proliferation. We found that CDA-II blocked differentiation of murine myoblasts C2C12 in a dose-dependent manner. CDA-II repressed expression of muscle transcription factors, such as Myogenin and Mef2c, and structural proteins, such as myosin heavy chain (Myh3), light chain (Mylpf) and MCK. Moreover, CDA-II inhibited C1C12 cell migration and proliferation. Thus, our data provide the first evidence that CDA-II inhibits growth and differentiation of muscle progenitor cells, suggesting that the use of CDA-II might affect skeletal muscle functions.

  17. Stabilization versus inhibition of TAFIa by competitive inhibitors in vitro

    NARCIS (Netherlands)

    Walker, J.B.; Hughes, B.; James, I.; Haddock, P.; Kluft, C.; Bajzar, L.

    2003-01-01

    Two competitive inhibitors of TAFIa (activated thrombin-activable fibrinolysis inhibitor), 2-guanidinoethyl-mercaptosuccinic acid and potato tuber carboxypeptidase inhibitor, variably affect fibrinolysis of clotted human plasma. Depending on their concentration, the inhibitors shortened, prolonged,

  18. E1AF degradation by a ubiquitin-proteasome pathway

    International Nuclear Information System (INIS)

    Takahashi, Akiko; Higashino, Fumihiro; Aoyagi, Mariko; Yoshida, Koichi; Itoh, Miyuki; Kobayashi, Masanobu; Totsuka, Yasunori; Kohgo, Takao; Shindoh, Masanobu

    2005-01-01

    E1AF is a member of the ETS family of transcription factors. In mammary tumors, overexpression of E1AF is associated with tumorigenesis, but E1AF protein has hardly been detected and its degradation mechanism is not yet clear. Here we show that E1AF protein is stabilized by treatment with the 26S protease inhibitor MG132. We found that E1AF was modified by ubiquitin through the C-terminal region and ubiquitinated E1AF aggregated in nuclear dots, and that the inhibition of proteasome-activated transcription from E1AF target promoters. These results suggest that E1AF is degraded via the ubiquitin-proteasome pathway, which has some effect on E1AF function

  19. Structural basis for c-KIT inhibition by the suppressor of cytokine signaling 6 (SOCS6) ubiquitin ligase

    DEFF Research Database (Denmark)

    Zadjali, Fahad; Pike, Ashley C W; Vesterlund, Mattias

    2011-01-01

    to substrate residue position pY+6 and envelopes the c-KIT phosphopeptide with a large BG loop insertion that contributes significantly to substrate interaction. We demonstrate that SOCS6 has ubiquitin ligase activity toward c-KIT and regulates c-KIT protein turnover in cells. Our data support a role of SOCS6...

  20. Systemic insulin sensitivity is regulated by GPS2 inhibition of AKT ubiquitination and activation in adipose tissue

    Directory of Open Access Journals (Sweden)

    Carly T. Cederquist

    2017-01-01

    Conclusions: Our findings characterize a novel layer of regulation of the insulin signaling pathway based on non-proteolytic ubiquitination of AKT and define GPS2 as a previously unrecognized component of the insulin signaling cascade. In accordance with this role, we have shown that GPS2 presence in adipocytes modulates systemic metabolism by restricting the activation of insulin signaling during the fasted state, whereas in absence of GPS2, the adipose tissue is more efficient at lipid storage, and obesity becomes uncoupled from inflammation and insulin resistance.

  1. The novel Akt inhibitor API-1 induces c-FLIP degradation and synergizes with TRAIL to augment apoptosis independent of Akt inhibition.

    Science.gov (United States)

    Li, Bo; Ren, Hui; Yue, Ping; Chen, Mingwei; Khuri, Fadlo R; Sun, Shi-Yong

    2012-04-01

    API-1 (pyrido[2,3-d]pyrimidines) is a novel small-molecule inhibitor of Akt, which acts by binding to Akt and preventing its membrane translocation and has promising preclinical antitumor activity. In this study, we reveal a novel function of API-1 in regulation of cellular FLICE-inhibitory protein (c-FLIP) levels and TRAIL-induced apoptosis, independent of Akt inhibition. API-1 effectively induced apoptosis in tested cancer cell lines including activation of caspase-8 and caspase-9. It reduced the levels of c-FLIP without increasing the expression of death receptor 4 (DR4) or DR5. Accordingly, it synergized with TRAIL to induce apoptosis. Enforced expression of ectopic c-FLIP did not attenuate API-1-induced apoptosis but inhibited its ability to enhance TRAIL-induced apoptosis. These data indicate that downregulation of c-FLIP mediates enhancement of TRAIL-induced apoptosis by API-1 but is not sufficient for API-1-induced apoptosis. API-1-induced reduction of c-FLIP could be blocked by the proteasome inhibitor MG132. Moreover, API-1 increased c-FLIP ubiquitination and decreased c-FLIP stability. These data together suggest that API-1 downregulates c-FLIP by facilitating its ubiquitination and proteasome-mediated degradation. Because other Akt inhibitors including API-2 and MK2206 had minimal effects on reducing c-FLIP and enhancement of TRAIL-induced apoptosis, it is likely that API-1 reduces c-FLIP and enhances TRAIL-induced apoptosis independent of its Akt-inhibitory activity. 2012 AACR

  2. F-box protein FBXL2 targets cyclin D2 for ubiquitination and degradation to inhibit leukemic cell proliferation

    Science.gov (United States)

    Chen, Bill B.; Glasser, Jennifer R.; Coon, Tiffany A.; Zou, Chunbin; Miller, Hannah L.; Fenton, Moon; McDyer, John F.; Boyiadzis, Michael

    2012-01-01

    Hematologic maligancies exhibit a growth advantage by up-regulation of components within the molecular apparatus involved in cell-cycle progression. The SCF (Skip-Cullin1-F-box protein) E3 ligase family provides homeostatic feedback control of cell division by mediating ubiquitination and degradation of cell-cycle proteins. By screening several previously undescribed E3 ligase components, we describe the behavior of a relatively new SCF subunit, termed FBXL2, that ubiquitinates and destabilizes cyclin D2 protein leading to G0 phase arrest and apoptosis in leukemic and B-lymphoblastoid cell lines. FBXL2 expression was strongly suppressed, and yet cyclin D2 protein levels were robustly expressed in acute myelogenous leukemia (AML) and acute lymphoblastic leukemia (ALL) patient samples. Depletion of endogenous FBXL2 stabilized cyclin D2 levels, whereas ectopically expressed FBXL2 decreased cyclin D2 lifespan. FBXL2 did not bind a phosphodegron within its substrate, which is typical of other F-box proteins, but uniquely targeted a calmodulin-binding signature within cyclin D2 to facilitate its polyubiquitination. Calmodulin competes with the F-box protein for access to this motif where it bound and protected cyclin D2 from FBXL2. Calmodulin reversed FBXL2-induced G0 phase arrest and attenuated FBXL2-induced apoptosis of lymphoblastoid cells. These results suggest an antiproliferative effect of SCFFBXL2 in lymphoproliferative malignancies. PMID:22323446

  3. Impact of High Glucose and Proteasome Inhibitor MG132 on Histone H2A and H2B Ubiquitination in Rat Glomerular Mesangial Cells

    Directory of Open Access Journals (Sweden)

    Chenlin Gao

    2013-01-01

    Full Text Available Background. Hyperglycemia plays a pivotal role in the development of diabetic nephropathy (DN and may be related to epigenetic metabolic memory. One of the most crucial epigenetic mechanisms is histone modification, which is associated with the expression of a fibrosis factor in vascular injury. Aim .In this study, we investigated the ubiquitination of histones H2A and H2B to explore the epigenetic mechanisms of DN. Materials and Methods. The GMCs were cultured as follows: normal group, high glucose group, mannitol group, and intervention group. After 12 hr, 24 hr, and 48 hr, histones ubiquitination, transforming growth factor-β (TGF-β, and fibronectin (FN were measured using WB, RT-PCR, and IF. Result. High glucose can induce the upregulation of FN. H2A ubiquitination in GMCs increased in high glucose group (P<0.01, whereas it decreased significantly in intervention group (P<0.05. In contrast, H2B ubiquitination decreased with an increasing concentration of glucose, but it was recovered in the intervention group (P<0.05. Expression of TGF-β changed in response to abnormal histone ubiquitination. Conclusions. The high glucose may induce H2A ubiquitination and reduce H2B ubiquitination in GMCs. The changes of histone ubiquitination may be due in part to DN by activating TGF-β signaling pathway.

  4. Ubiquitin-specific Protease-7 Inhibition Impairs Tip60-dependent Foxp3+ T-regulatory Cell Function and Promotes Antitumor Immunity

    Directory of Open Access Journals (Sweden)

    Liqing Wang

    2016-11-01

    Full Text Available Foxp3+ T-regulatory (Treg cells are known to suppress protective host immune responses to a wide variety of solid tumors, but their therapeutic targeting is largely restricted to their transient depletion or “secondary” modulation, e.g. using anti-CTLA-4 monoclonal antibody. Our ongoing studies of the post-translational modifications that regulate Foxp3 demonstrated that the histone/protein acetyltransferase, Tip60, plays a dominant role in promoting acetylation, dimerization and function in Treg cells. We now show that the ubiquitin-specific protease, Usp7, controls Treg function largely by stabilizing the expression and promoting the multimerization of Tip60 and Foxp3. Genetic or pharmacologic targeting of Usp7 impairs Foxp3+ Treg suppressive functions, while conventional T cell responses remain intact. As a result, pharmacologic inhibitors of Usp7 can limit tumor growth in immunocompetent mice, and promote the efficacy of antitumor vaccines and immune checkpoint therapy with anti-PD1 monoclonal antibody in murine models. Hence, pharmacologic therapy with Usp7 inhibitors may have an important role in future cancer immunotherapy.

  5. The Ubiquitin-Conjugating Enzyme E2-EPF Is Overexpressed in Primary Breast Cancer and Modulates Sensitivity to Topoisomerase II Inhibition1

    Science.gov (United States)

    Tedesco, Donato; Zhang, Jianhuan; Trinh, Lan; Lalehzadeh, Guita; Meisner, Rene; Yamaguchi, Ken D; Ruderman, Daniel L; Dinter, Harald; Zajchowski, Deborah A

    2007-01-01

    We identified the ubiquitin-conjugating enzyme E2-EPF mRNA as differentially expressed in breast tumors relative to normal tissues and performed studies to elucidate its putative role in cancer. We demonstrated that overexpression of E2-EPF protein correlated with estrogen receptor (ER) negativity in breast cancer specimens and that its expression is cell cycle-regulated, suggesting a potential function for E2-EPF in cell cycle progression. However, reduction of E2-EPF protein levels by > 80% using RNAi had no significant effects on the proliferation of HeLa cervical cancer cells or ER- MDA-MB-231 or MDA-MB-453 breast cancer cells. Because E2-EPF protein levels were elevated during the G2/M phase of the cell cycle and because E2-EPF mRNA in tumor specimens was frequently coexpressed with genes involved in cell cycle control, spindle assembly, and mitotic surveillance, the possibility that E2-EPF might have a function in the cellular response to agents that induce a G2 checkpoint or an M checkpoint was investigated. E2-EPF knockdown sensitized HeLa cells to the topoisomerase (topo) II inhibitors etoposide and doxorubicin and also increased topo IIα protein levels. These data suggest that combined administration of topo II-directed drugs and E2-EPF inhibitors may enhance their clinical effectiveness. PMID:17710163

  6. The Ubiquitin-Conjugating Enzyme E2-EPF Is Overexpressed in Primary Breast Cancer and Modulates Sensitivity to Topoisomerase II Inhibition

    Directory of Open Access Journals (Sweden)

    Donato Tedesco

    2007-07-01

    Full Text Available We identified the ubiquitin-conjugating enzyme E2EPF mRNA as differentially expressed in breast tumors relative to normal tissues and performed studies to elucidate its putative role in cancer. We demonstrated that overexpression of E2-EPF protein correlated with estrogen receptor (ER negativity in breast cancer specimens and that its expression is cell cycleregulated, suggesting a potential function for E2-EPF in cell cycle progression. However, reduction of E2EPF protein levels by > 80% using RNAi had no significant effects on the proliferation of HeLa cervical cancer cells or ER- MDA-MB-231 or MDA-MB-453 breast cancer cells. Because E2-EPF protein levels were elevated during the G2/M phase of the cell cycle and because E2-EPF mRNA in tumor specimens was frequently coexpressed with genes involved in cell cycle control, spindle assembly, and mitotic surveillance, the possibility that E2-EPF might have a function in the cellular response to agents that induce a G2 checkpoint or an M checkpoint was investigated. E2-EPF knockdown sensitized HeLa cells to the topoisomerase (topo II inhibitors etoposide and doxorubicin and also increased topo IIα protein levels. These data suggest that combined administration of topo II-directed drugs and E2-EPF inhibitors may enhance their clinical effectiveness.

  7. The ubiquitin-conjugating enzyme E2-EPF is overexpressed in primary breast cancer and modulates sensitivity to topoisomerase II inhibition.

    Science.gov (United States)

    Tedesco, Donato; Zhang, Jianhuan; Trinh, Lan; Lalehzadeh, Guita; Meisner, Rene; Yamaguchi, Ken D; Ruderman, Daniel L; Dinter, Harald; Zajchowski, Deborah A

    2007-07-01

    We identified the ubiquitin-conjugating enzyme E2-EPF mRNA as differentially expressed in breast tumors relative to normal tissues and performed studies to elucidate its putative role in cancer. We demonstrated that overexpression of E2-EPF protein correlated with estrogen receptor (ER) negativity in breast cancer specimens and that its expression is cell cycle-regulated, suggesting a potential function for E2-EPF in cell cycle progression. However, reduction of E2-EPF protein levels by > 80% using RNAi had no significant effects on the proliferation of HeLa cervical cancer cells or ER(-) MDA-MB-231 or MDA-MB-453 breast cancer cells. Because E2-EPF protein levels were elevated during the G(2)/M phase of the cell cycle and because E2-EPF mRNA in tumor specimens was frequently coexpressed with genes involved in cell cycle control, spindle assembly, and mitotic surveillance, the possibility that E2-EPF might have a function in the cellular response to agents that induce a G(2) checkpoint or an M checkpoint was investigated. E2-EPF knockdown sensitized HeLa cells to the topoisomerase (topo) II inhibitors etoposide and doxorubicin and also increased topo IIalpha protein levels. These data suggest that combined administration of topo II-directed drugs and E2-EPF inhibitors may enhance their clinical effectiveness.

  8. Bean polygalacturonase inhibitor protein-1 (PGIP-1) inhibits polygalacturonases from Stenocarpella maydis

    CSIR Research Space (South Africa)

    Berger, DK

    2000-07-01

    Full Text Available Stenocarpella maydis, a fungal pathogen of maize, produced polygalacturonases (PGs) when grown on pectin or maize cell walls. An extract from bean (Phaseolus vulgaris L.) which contained an active inhibitor of Aspergillus niger PG, also inhibited S...

  9. Oligopeptidase B from Serratia proteamaculans. III. Inhibition analysis. Specific interactions with metalloproteinase inhibitors.

    Science.gov (United States)

    Mikhailova, A G; Khairullin, R F; Kolomijtseva, G Ya; Rumsh, L D

    2012-03-01

    Inhibition of the novel oligopeptidase B from Serratia proteamaculans (PSP) by basic pancreatic trypsin inhibitor, Zn2+ ions, and o- and m-phenanthroline was investigated. A pronounced effect of calcium ions on the interaction of PSP with inhibitors was demonstrated. Inversion voltamperometry and atomic absorption spectrometry revealed no zinc ions in the PSP molecule. Hydrophobic nature of the enzyme inhibition by o- and m-phenanthroline was established.

  10. Terminating protein ubiquitination: Hasta la vista, ubiquitin.

    Science.gov (United States)

    Stringer, Daniel K; Piper, Robert C

    2011-09-15

    Ubiquitination is a post-translational modification that generally directs proteins for degradation by the proteasome or by lysosomes. However, ubiquitination has been implicated in many other cellular processes, including transcriptional regulation, DNA repair, regulation of protein-protein interactions and association with ubiquitin-binding scaffolds. Ubiquitination is a dynamic process. Ubiquitin is added to proteins by E3 ubiquitin ligases as a covalent modification to one or multiple lysine residues as well as non-lysine amino acids. Ubiquitin itself contains seven lysines, each of which can also be ubiquitinated, leading to polyubiquitin chains that are best characterized for linkages occurring through K48 and K63. Ubiquitination can also be reversed by the action of deubiquitination enzymes (DUbs). Like E3 ligases, DUbs play diverse and critical roles in cells. ( 1) Ubiquitin is expressed as a fusion protein, as a linear repeat or as a fusion to ribosomal subunits, and DUbs are necessary to liberate free ubiquitin, making them the first enzyme of the ubiquitin cascade. Proteins destined for degradation by the proteasome or by lysosomes are deubiquitinated prior to their degradation, which allows ubiquitin to be recycled by the cell, contributing to the steady-state pool of free ubiquitin. Proteins destined for degradation by lysosomes are also acted upon by both ligases and DUbs. Deubiquitination can also act as a means to prevent protein degradation, and many proteins are thought to undergo rounds of ubiquitination and deubiquitination, ultimately resulting in either the degradation or stabilization of those proteins. Despite years of study, examining the effects of the ubiquitination of proteins remains quite challenging. This is because the methods that are currently being employed to study ubiquitination are limiting. Here, we briefly examine current strategies to study the effects of ubiquitination and describe an additional novel approach that we have

  11. Inhibition of hydrogenase synthesis by DNA gyrase inhibitors in Bradyrhizobium japonicum

    International Nuclear Information System (INIS)

    Novak, P.D.; Maier, R.J.

    1987-01-01

    Derepression of an uptake hydrogenase in Bradyrhizobium japonicum is dependent on a microaerophilic environment. Addition of DNA gyrase inhibitors during derepression of hydrogenase specifically prevented expression of the hydrogenase enzyme. Antibodies to individual hydrogenase subunits failed to detect the protein after derepression in the presence of inhibitors, although there was no general inhibition of protein synthesis. The general pattern of proteins synthesized from 14 C-labeled amino acids during derepression was no significantly different whether proteins were labeled in the presence or in the absence of gyrase inhibitors. In contrast, if transcription or translation was inhibited by addition of inhibitors of those functions, virtually no proteins were labeled during derepression. This indicated that most of the 14 C-labeled proteins were synthesized de novo during derepression, synthesis of most proteins was unaffected by gyrase inhibitors, and the dependence of hydrogenase synthesis on gyrase activity was a specific one

  12. Inhibition of neuraminidase by Ganoderma triterpenoids and implications for neuraminidase inhibitor design

    Science.gov (United States)

    Zhu, Qinchang; Bang, Tran Hai; Ohnuki, Koichiro; Sawai, Takashi; Sawai, Ken; Shimizu, Kuniyoshi

    2015-01-01

    Neuraminidase (NA) inhibitors are the dominant antiviral drugs for treating influenza in the clinic. Increasing prevalence of drug resistance makes the discovery of new NA inhibitors a high priority. Thirty-one triterpenoids from the medicinal mushroom Ganoderma lingzhi were analyzed in an in vitro NA inhibition assay, leading to the discovery of ganoderic acid T-Q and TR as two inhibitors of H5N1 and H1N1 NAs. Structure-activity relationship studies revealed that the corresponding triterpenoid structure is a potential scaffold for the design of NA inhibitors. Using these triterpenoids as probes we found, through further in silico docking and interaction analysis, that interactions with the amino-acid residues Arg292 and/or Glu119 of NA are critical for the inhibition of H5N1 and H1N1. These findings should prove valuable for the design and development of NA inhibitors. PMID:26307417

  13. Why Do SGLT2 inhibitors inhibit only 30-50% of renal glucose reabsorption in humans?

    Science.gov (United States)

    Liu, Jiwen Jim; Lee, TaeWeon; DeFronzo, Ralph A

    2012-09-01

    Sodium glucose cotransporter 2 (SGLT2) inhibition is a novel and promising treatment for diabetes under late-stage clinical development. It generally is accepted that SGLT2 mediates 90% of renal glucose reabsorption. However, SGLT2 inhibitors in clinical development inhibit only 30-50% of the filtered glucose load. Why are they unable to inhibit 90% of glucose reabsorption in humans? We will try to provide an explanation to this puzzle in this perspective analysis of the unique pharmacokinetic and pharmacodynamic profiles of SGLT2 inhibitors in clinical trials and examine possible mechanisms and molecular properties that may be responsible.

  14. Why Do SGLT2 Inhibitors Inhibit Only 30–50% of Renal Glucose Reabsorption in Humans?

    Science.gov (United States)

    Liu, Jiwen (Jim); Lee, TaeWeon; DeFronzo, Ralph A.

    2012-01-01

    Sodium glucose cotransporter 2 (SGLT2) inhibition is a novel and promising treatment for diabetes under late-stage clinical development. It generally is accepted that SGLT2 mediates 90% of renal glucose reabsorption. However, SGLT2 inhibitors in clinical development inhibit only 30–50% of the filtered glucose load. Why are they unable to inhibit 90% of glucose reabsorption in humans? We will try to provide an explanation to this puzzle in this perspective analysis of the unique pharmacokinetic and pharmacodynamic profiles of SGLT2 inhibitors in clinical trials and examine possible mechanisms and molecular properties that may be responsible. PMID:22923645

  15. Non-degradative Ubiquitination of Protein Kinases.

    Directory of Open Access Journals (Sweden)

    K Aurelia Ball

    2016-06-01

    Full Text Available Growing evidence supports other regulatory roles for protein ubiquitination in addition to serving as a tag for proteasomal degradation. In contrast to other common post-translational modifications, such as phosphorylation, little is known about how non-degradative ubiquitination modulates protein structure, dynamics, and function. Due to the wealth of knowledge concerning protein kinase structure and regulation, we examined kinase ubiquitination using ubiquitin remnant immunoaffinity enrichment and quantitative mass spectrometry to identify ubiquitinated kinases and the sites of ubiquitination in Jurkat and HEK293 cells. We find that, unlike phosphorylation, ubiquitination most commonly occurs in structured domains, and on the kinase domain, ubiquitination is concentrated in regions known to be important for regulating activity. We hypothesized that ubiquitination, like other post-translational modifications, may alter the conformational equilibrium of the modified protein. We chose one human kinase, ZAP-70, to simulate using molecular dynamics with and without a monoubiquitin modification. In Jurkat cells, ZAP-70 is ubiquitinated at several sites that are not sensitive to proteasome inhibition and thus may have other regulatory roles. Our simulations show that ubiquitination influences the conformational ensemble of ZAP-70 in a site-dependent manner. When monoubiquitinated at K377, near the C-helix, the active conformation of the ZAP-70 C-helix is disrupted. In contrast, when monoubiquitinated at K476, near the kinase hinge region, an active-like ZAP-70 C-helix conformation is stabilized. These results lead to testable hypotheses that ubiquitination directly modulates kinase activity, and that ubiquitination is likely to alter structure, dynamics, and function in other protein classes as well.

  16. Plasminogen activator inhibitor-1 is an independent prognostic factor of ovarian cancer and IMD-4482, a novel plasminogen activator inhibitor-1 inhibitor, inhibits ovarian cancer peritoneal dissemination.

    Science.gov (United States)

    Nakatsuka, Erika; Sawada, Kenjiro; Nakamura, Koji; Yoshimura, Akihito; Kinose, Yasuto; Kodama, Michiko; Hashimoto, Kae; Mabuchi, Seiji; Makino, Hiroshi; Morii, Eiichi; Yamaguchi, Yoichi; Yanase, Takeshi; Itai, Akiko; Morishige, Ken-Ichirou; Kimura, Tadashi

    2017-10-27

    In the present study, the therapeutic potential of targeting plasminogen activator inhibitor-1 (PAI-1) in ovarian cancer was tested. Tissues samples from 154 cases of ovarian carcinoma were immunostained with anti-PAI-1 antibody, and the prognostic value was analyzed. Among the samples, 67% (104/154) showed strong PAI-1 expression; this was significantly associated with poor prognosis (progression-free survival: 20 vs. 31 months, P = 0.0033). In particular, among patients with stage II-IV serous adenocarcinoma, PAI-1 expression was an independent prognostic factor. The effect of a novel PAI-1 inhibitor, IMD-4482, on ovarian cancer cell lines was assessed and its therapeutic potential was examined using a xenograft mouse model of ovarian cancer. IMD-4482 inhibited in vitro cell adhesion to vitronectin in PAI-1-positive ovarian cancer cells, followed by the inhibition of extracellular signal-regulated kinase and focal adhesion kinase phosphorylation through dissociation of the PAI-urokinase receptor complex from integrin αVβ3. IMD-4482 caused G0/G1 cell arrest and inhibited the proliferation of PAI-1-positive ovarian cancer cells. In the xenograft model, IMD-4482 significantly inhibited peritoneal dissemination with the reduction of PAI-1 expression and the inhibition of focal adhesion kinase phosphorylation. Collectively, the functional inhibition of PAI-1 significantly inhibited ovarian cancer progression, and targeting PAI-1 may be a potential therapeutic strategy in ovarian cancer.

  17. Severe energy deficit at high altitude inhibits skeletal muscle mTORC1-mediated anabolic signaling without increased ubiquitin proteasome activity.

    Science.gov (United States)

    Margolis, Lee M; Carbone, John W; Berryman, Claire E; Carrigan, Christopher T; Murphy, Nancy E; Ferrando, Arny A; Young, Andrew J; Pasiakos, Stefan M

    2018-06-07

    Muscle loss at high altitude (HA) is attributable to energy deficit and a potential dysregulation of anabolic signaling. Exercise and protein ingestion can attenuate the effects of energy deficit on muscle at sea level (SL). Whether these effects are observed when energy deficit occurs at HA is unknown. To address this, muscle obtained from lowlanders ( n = 8 males) at SL, acute HA (3 h, 4300 m), and chronic HA (21 d, -1766 kcal/d energy balance) before [baseline (Base)] and after 80 min of aerobic exercise followed by a 2-mile time trial [postexercise (Post)] and 3 h into recovery (Rec) after ingesting whey protein (25 g) were analyzed using standard molecular techniques. At SL, Post, and REC, p-mechanistic target of rapamycin (mTOR) Ser2448 , p-p70 ribosomal protein S6 kinase (p70S6K) Ser424/421 , and p-ribosomal protein S6 (rpS6) Ser235/236 were similar and higher ( P anabolic resistance that is exacerbated by energy deficit during acclimatization, with no change in proteolysis.-Margolis, L. M., Carbone, J. W., Berryman, C. E., Carrigan, C. T., Murphy, N. E., Ferrando, A. A., Young, A. J., Pasiakos, S. M. Severe energy deficit at high altitude inhibits skeletal muscle mTORC1-mediated anabolic signaling without increased ubiquitin proteasome activity.

  18. BET Bromodomain Inhibition Synergizes with PARP Inhibitor in Epithelial Ovarian Cancer

    Directory of Open Access Journals (Sweden)

    Sergey Karakashev

    2017-12-01

    Full Text Available PARP inhibition is known to be an effective clinical strategy in BRCA mutant cancers, but PARP inhibition has not been applied to BRCA-proficient tumors. Here, we show the synergy of BET bromodomain inhibition with PARP inhibition in BRCA-proficient ovarian cancers due to mitotic catastrophe. Treatment of BRCA-proficient ovarian cancer cells with the BET inhibitor JQ1 downregulated the G2-M cell-cycle checkpoint regulator WEE1 and the DNA-damage response factor TOPBP1. Combining PARP inhibitor Olaparib with the BET inhibitor, we observed a synergistic increase in DNA damage and checkpoint defects, which allowed cells to enter mitosis despite the accumulation of DNA damage, ultimately causing mitotic catastrophe. Moreover, JQ1 and Olaparib showed synergistic suppression of growth of BRCA-proficient cancer in vivo in a xenograft ovarian cancer mouse model. Our findings indicate that a combination of BET inhibitor and PARP inhibitor represents a potential therapeutic strategy for BRCA-proficient cancers.

  19. The "SWOT" of BRAF inhibition in melanoma: RAF inhibitors, MEK inhibitors or both?

    Science.gov (United States)

    Nissan, Moriah H; Solit, David B

    2011-12-01

    Activating mutations in the BRAF gene are among the most prevalent kinase mutations in human cancer. BRAF mutations are most frequent in patients with melanoma where they occur in approximately 50% of patients with advanced disease. Remarkable clinical activity has recently been reported with highly selective RAF inhibitors in melanoma patients whose tumors harbor V600E BRAF mutations. The response rates of RAF inhibitors in patients with BRAF-mutant melanomas far exceed the activity level of any prior therapy studied in this disease. The results suggest that we have entered an era of personalized therapy for patients with metastatic melanoma in which treatment selection will be guided by BRAF mutational status. This review will discuss the strengths, weaknesses, opportunities and threats ("SWOT") of developing RAF and MEK selective inhibitors as anti-cancer therapies, recent insights into the mechanisms of intrinsic and acquired resistance to these agents, and current efforts to develop mechanism-based combination therapies.

  20. Inhibition of natural gas hydrates by means of kinetic inhibitors; Inhibierung von Erdgashydraten mit kinetischen Inhibitoren

    Energy Technology Data Exchange (ETDEWEB)

    Eberhardt, E.; Froemmel, J.; Hase, A. [Inst. fuer Erdoel- und Erdgasforschung, Clausthal-Zellerfeld (Germany)

    1997-12-31

    The use of kinetic inhibitors saves considerable costs as compared with thermodynamic inhibition. The effectivity of kinetic inhibitors can be examined by means of screening tests using an agitated autoclave. This contribution describes the experimental set-up and measuring methods used for this purpose and discusses the results obtained. (MSK) [Deutsch] Der Einsatz von kinetischen Inhibitoren fuehrt im Vergleich zur thermodynamischen Inhibition zu einer erheblichen Kostenreduzierung. Die Effektivitaet wird anhand von Screening-Versuchen in einem Ruehrautoklaven geprueft.Im Folgenden werden die Versuchsapparatur und die Messmethodik beschrieben. Ebenso werden die Ergebnisse diskutiert.

  1. Inhibition of bacterial multidrug resistance by celecoxib, a cyclooxygenase-2 inhibitor.

    Science.gov (United States)

    Kalle, Arunasree M; Rizvi, Arshad

    2011-01-01

    Multidrug resistance (MDR) is a major problem in the treatment of infectious diseases and cancer. Accumulating evidence suggests that the cyclooxygenase-2 (COX-2)-specific inhibitor celecoxib would not only inhibit COX-2 but also help in the reversal of drug resistance in cancers by inhibiting the MDR1 efflux pump. Here, we demonstrate that celecoxib increases the sensitivity of bacteria to the antibiotics ampicillin, kanamycin, chloramphenicol, and ciprofloxacin by accumulating the drugs inside the cell, thus reversing MDR in bacteria.

  2. N-acetyl lysyltyrosylcysteine amide inhibits myeloperoxidase, a novel tripeptide inhibitor1[S

    OpenAIRE

    Zhang, Hao; Jing, Xigang; Shi, Yang; Xu, Hao; Du, Jianhai; Guan, Tongju; Weihrauch, Dorothee; Jones, Deron W.; Wang, Weiling; Gourlay, David; Oldham, Keith T.; Hillery, Cheryl A.; Pritchard, Kirkwood A.

    2013-01-01

    Myeloperoxidase (MPO) plays important roles in disease by increasing oxidative and nitrosative stress and oxidizing lipoproteins. Here we report N-acetyl lysyltyrosylcysteine amide (KYC) is an effective inhibitor of MPO activity. We show KYC inhibits MPO-mediated hypochlorous acid (HOCl) formation and nitration/oxidation of LDL. Disulfide is the major product of MPO-mediated KYC oxidation. KYC (⩽4,000 μM) does not induce cytotoxicity in bovine aortic endothelial cells (BAECs). KYC inhibits HO...

  3. The PDE4 inhibitor CHF-6001 and LAMAs inhibit bronchoconstriction-induced remodeling in lung slices.

    Science.gov (United States)

    Kistemaker, Loes E M; Oenema, Tjitske A; Baarsma, Hoeke A; Bos, I Sophie T; Schmidt, Martina; Facchinetti, Fabrizio; Civelli, Maurizio; Villetti, Gino; Gosens, Reinoud

    2017-09-01

    Combination therapy of PDE4 inhibitors and anticholinergics induces bronchoprotection in COPD. Mechanical forces that arise during bronchoconstriction may contribute to airway remodeling. Therefore, we investigated the impact of PDE4 inhibitors and anticholinergics on bronchoconstriction-induced remodeling. Because of the different mechanism of action of PDE4 inhibitors and anticholinergics, we hypothesized functional interactions of these two drug classes. Guinea pig precision-cut lung slices were preincubated with the PDE4 inhibitors CHF-6001 or roflumilast and/or the anticholinergics tiotropium or glycopyorrolate, followed by stimulation with methacholine (10 μM) or TGF-β 1 (2 ng/ml) for 48 h. The inhibitory effects on airway smooth muscle remodeling, airway contraction, and TGF-β release were investigated. Methacholine-induced protein expression of smooth muscle-myosin was fully inhibited by CHF-6001 (0.3-100 nM), whereas roflumilast (1 µM) had smaller effects. Tiotropium and glycopyrrolate fully inhibited methacholine-induced airway remodeling (0.1-30 nM). The combination of CHF-6001 and tiotropium or glycopyrrolate, in concentrations partially effective by themselves, fully inhibited methacholine-induced remodeling in combination. CHF-6001 did not affect airway closure and had limited effects on TGF-β 1 -induced remodeling, but rather, it inhibited methacholine-induced TGF-β release. The PDE4 inhibitor CHF-6001, and to a lesser extent roflumilast, and the LAMAs tiotropium and glycopyrrolate inhibit bronchoconstriction-induced remodeling. The combination of CHF-6001 and anticholinergics was more effective than the individual compounds. This cooperativity might be explained by the distinct mechanisms of action inhibiting TGF-β release and bronchoconstriction. Copyright © 2017 the American Physiological Society.

  4. Functional inhibition of Ubiquitin conjugating Enzyme (UBE2C) reduces proliferation and sensitizes cervical and breast cancer cells to radiation, doxorubicin, tamoxifen and letrozole

    International Nuclear Information System (INIS)

    Bose, Mayil Vahanan; Rawat, Akhilesh; Gopisetty, Gopal; Thangarajan, Rajkumar; Ganesharaja, Selvaluxmy

    2014-01-01

    Cervical cancer is the second most common cancer in women, worldwide. About 80% of cervical cancer cases occur in developing countries. Breast cancer has overtaken cervical cancer in most of the urban centers in India. In recent years, interest in the role of Ubiquitin conjugating Enzyme E2C (UBE2C) in cancer has shown a dramatic increase. Several studies have reported UBE2C as a potential oncogene and therapeutic target. The objective of the study was to elucidate radiation and chemo-sensitivity in response to functional inhibition of UBE2C in cervical and breast cancer cell lines. Taqman Real time PCR was performed to measure UBE2C levels in cervical and breast cancer cell lines. A dominant negative form of UBE2C (DN-UBE2C) was used to functionally inhibit wild type UBE2C. Cell proliferation and anchorage independent growth were measured by colorimetric assay and soft agar assay respectively. Radiation and chemo response of cell lines were assessed by colorimetric assay and clonogenic assay. Difference in sensitivity to radiation was observed among the cervical cancer cell lines studied. The growth rate of SiHa and HeLa transfected with DN- UBE2C was significantly reduced compared to vector control. Further, DN-UBE2C mediated radio-sensitivity was correlated with a significant decrease in resistance to radiation by SiHa and HeLa cells after transfection when compared to control cultures. Similarly, both the growth rate and the anchorage independent growth of MCF7 and MDAMB231 cells transfected with DN-UBE2C were significantly reduced compared to cells transfected with vector alone. MCF7 and MDAMB231 cells expressing DN-UBE2C were significantly more sensitive to different doses of radiation and doxorubicin compared to controls. In addition, DN-UBE2C transfected MCF7 cells were more sensitive to inhibition by tamoxifen and letrozole compared to vector controls. These results suggest that UBE2C can be used as a potential therapeutic target for cervical and breast

  5. Ubiquitin-specific peptidase 22 inhibits colon cancer cell invasion by suppressing the signal transducer and activator of transcription 3/matrix metalloproteinase 9 pathway.

    Science.gov (United States)

    Ao, Ning; Liu, Yanyan; Bian, Xiaocui; Feng, Hailiang; Liu, Yuqin

    2015-08-01

    Colon cancer is associated with increased cell migration and invasion. In the present study, the role of ubiquitin-specific peptidase 22 (USP22) in signal transducer and activator of transcription 3 (STAT3)-mediated colon cancer cell invasion was investigated. The messenger RNA levels of STAT3 target genes were measured by reverse transcription-quantitative polymerase chain reaction, following USP22 knockdown by RNA interference in SW480 colon cancer cells. The matrix metalloproteinase 9 (MMP9) proteolytic activity and invasion potential of SW480 cells were measured by zymography and Transwell assay, respectively, following combined USP22 and STAT3 short interfering (si)RNA treatment or STAT3 siRNA treatment alone. Similarly, a cell counting kit-8 assay was used to detect the proliferation potential of SW480 cells. The protein expression levels of USP22, STAT3 and MMP9 were detected by immunohistochemistry in colon cancer tissue microarrays (TMAs) and the correlation between USP22, STAT3 and MMP9 was analyzed. USP22/STAT3 co-depletion partly rescued the MMP9 proteolytic activity and invasion of SW480 cells, compared with that of STAT3 depletion alone. However, the proliferation of USP22/STAT3si-SW480 cells was decreased compared with that of STAT3si-SW480 cells. USP22 expression was positively correlated with STAT3 and MMP9 expression in colon cancer TMAs. In conclusion, USP22 attenuated the invasion capacity of colon cancer cells by inhibiting the STAT3/MMP9 signaling pathway.

  6. IGF-1 prevents ANG II-induced skeletal muscle atrophy via Akt- and Foxo-dependent inhibition of the ubiquitin ligase atrogin-1 expression

    Science.gov (United States)

    Yoshida, Tadashi; Semprun-Prieto, Laura; Sukhanov, Sergiy

    2010-01-01

    Congestive heart failure is associated with activation of the renin-angiotensin system and skeletal muscle wasting. Angiotensin II (ANG II) has been shown to increase muscle proteolysis and decrease circulating and skeletal muscle IGF-1. We have shown previously that skeletal muscle-specific overexpression of IGF-1 prevents proteolysis and apoptosis induced by ANG II. These findings indicated that downregulation of IGF-1 signaling in skeletal muscle played an important role in the wasting effect of ANG II. However, the signaling pathways and mechanisms whereby IGF-1 prevents ANG II-induced skeletal muscle atrophy are unknown. Here we show ANG II-induced transcriptional regulation of two ubiquitin ligases atrogin-1 and muscle ring finger-1 (MuRF-1) that precedes the reduction of skeletal muscle IGF-1 expression, suggesting that activation of atrogin-1 and MuRF-1 is an initial mechanism leading to skeletal muscle atrophy in response to ANG II. IGF-1 overexpression in skeletal muscle prevented ANG II-induced skeletal muscle wasting and the expression of atrogin-1, but not MuRF-1. Dominant-negative Akt and constitutively active Foxo-1 blocked the ability of IGF-1 to prevent ANG II-mediated upregulation of atrogin-1 and skeletal muscle wasting. Our findings demonstrate that the ability of IGF-1 to prevent ANG II-induced skeletal muscle wasting is mediated via an Akt- and Foxo-1-dependent signaling pathway that results in inhibition of atrogin-1 but not MuRF-1 expression. These data suggest strongly that atrogin-1 plays a critical role in mechanisms of ANG II-induced wasting in vivo. PMID:20228261

  7. Protein C inhibitor acts as a procoagulant by inhibiting the thrombomodulin-induced activation of protein C in human plasma

    NARCIS (Netherlands)

    Elisen, M. G.; von dem Borne, P. A.; Bouma, B. N.; Meijers, J. C.

    1998-01-01

    Protein C inhibitor (PCI), which was originally identified as an inhibitor of activated protein C, also efficiently inhibits coagulation factors such as factor Xa and thrombin. Recently it was found, using purified proteins, that the anticoagulant thrombin-thrombomodulin complex was also inhibited

  8. Suramin Inhibits Osteoarthritic Cartilage Degradation by Increasing Extracellular Levels of Chondroprotective Tissue Inhibitor of Metalloproteinases 3.

    Science.gov (United States)

    Chanalaris, Anastasios; Doherty, Christine; Marsden, Brian D; Bambridge, Gabriel; Wren, Stephen P; Nagase, Hideaki; Troeberg, Linda

    2017-10-01

    Osteoarthritis is a common degenerative joint disease for which no disease-modifying drugs are currently available. Attempts to treat the disease with small molecule inhibitors of the metalloproteinases that degrade the cartilage matrix have been hampered by a lack of specificity. We aimed to inhibit cartilage degradation by augmenting levels of the endogenous metalloproteinase inhibitor, tissue inhibitor of metalloproteinases (TIMP)-3, through blocking its interaction with the endocytic scavenger receptor, low-density lipoprotein receptor-related protein 1 (LRP1). We discovered that suramin (C 51 H 40 N 6 O 23 S 6 ) bound to TIMP-3 with a K D value of 1.9 ± 0.2 nM and inhibited its endocytosis via LRP1, thus increasing extracellular levels of TIMP-3 and inhibiting cartilage degradation by the TIMP-3 target enzyme, adamalysin-like metalloproteinase with thrombospondin motifs 5. NF279 (8,8'-[carbonyl bis (imino-4,1-phenylenecarbonylimino-4,1-phenylenecarbonylimino)] bis -1,3,5-naphthalenetrisulfonic acid hexasodium salt), a structural analog of suramin, has an increased affinity for TIMP-3 and increased ability to inhibit TIMP-3 endocytosis and protect cartilage. Suramin is thus a promising scaffold for the development of novel therapeutics to increase TIMP-3 levels and inhibit cartilage degradation in osteoarthritis. Copyright © 2017 by The Author(s).

  9. Selective inhibition of influenza virus protein synthesis by inhibitors of DNA function

    International Nuclear Information System (INIS)

    Minor, P.D.; Dimmock, N.J.

    1977-01-01

    Various known inhibitors of cellular DNA function were shown to inhibit cellular RNA synthesis and influenza (fowl plague) virus multiplication. The drugs were investigated for their effect upon the synthesis of influenza virus proteins. According to this effect they could be classified with previously studied compounds as follows: Group I (ethidium bromide, proflavine, and N-nitroquinoline-N-oxide) inhibited both viral and cellular protein synthesis; Group II (nogalomycin, daunomycin and α-amanitin) inhibited viral but not cellular protein synthesis, and all viral proteins were inhibited coordinately; Group III (mithramycin, echinomycin, and actinomycin D) inhibited all viral but not cellular protein synthesis at high concentrations, but at a lower critical concentration inhibited the synthesis of viral haemagglutinin, neuraminidase, and M protein preferentially; Group IV(uv irradiation and camptothecin) inhibited the synthesis of viral haemagglutinin, neuraminidase, and M protein, but not other viral proteins, even at high doses. The mode of action of these inhibitors is discussed in relation to the mechanism of the nuclear events upon which influenza virus multiplication is dependent

  10. General amyloid inhibitors? A critical examination of the inhibition of IAPP amyloid formation by inositol stereoisomers.

    Directory of Open Access Journals (Sweden)

    Hui Wang

    Full Text Available Islet amyloid polypeptide (IAPP or amylin forms amyloid deposits in the islets of Langerhans; a process that is believed to contribute to the progression of type 2 diabetes and to the failure of islet transplants. An emerging theme in amyloid research is the hypothesis that the toxic species produced during amyloid formation by different polypeptides share common features and exert their effects by common mechanisms. If correct, this suggests that inhibitors of amyloid formation by one polypeptide might be effective against other amyloidogenic sequences. IAPP and Aβ, the peptide responsible for amyloid formation in Alzheimer's disease, are particularly interesting in this regard as they are both natively unfolded in their monomeric states and share some common characteristics. Comparatively little effort has been expended on the design of IAPP amyloid inhibitors, thus it is natural to inquire if Aβ inhibitors are effective against IAPP, especially since no IAPP inhibitors have been clinically approved. A range of compounds inhibit Aβ amyloid formation, including various stereoisomers of inositol. Myo-, scyllo-, and epi-inositol have been shown to induce conformational changes in Aβ and prevent Aβ amyloid fibril formation by stabilizing non-fibrillar β-sheet structures. We investigate the ability of inositol stereoisomers to inhibit amyloid formation by IAPP. The compounds do not induce a conformational change in IAPP and are ineffective inhibitors of IAPP amyloid formation, although some do lead to modest apparent changes in IAPP amyloid fibril morphology. Thus not all classes of Aβ inhibitors are effective against IAPP. This work provides a basis of comparison to work on polyphenol based inhibitors of IAPP amyloid formation and helps provide clues as to the features which render them effective. The study also helps provide information for further efforts in rational inhibitor design.

  11. The amine oxidase inhibitor phenelzine limits lipogenesis in adipocytes without inhibiting insulin action on glucose uptake.

    Science.gov (United States)

    Carpéné, Christian; Grès, Sandra; Rascalou, Simon

    2013-06-01

    The antidepressant phenelzine is a monoamine oxidase inhibitor known to inhibit various other enzymes, among them semicarbazide-sensitive amine oxidase (currently named primary amine oxidase: SSAO/PrAO), absent from neurones but abundant in adipocytes. It has been reported that phenelzine inhibits adipocyte differentiation of cultured preadipocytes. To further explore the involved mechanisms, our aim was to study in vitro the acute effects of phenelzine on de novo lipogenesis in mature fat cells. Therefore, glucose uptake and incorporation into lipid were measured in mouse adipocytes in response to phenelzine, other hydrazine-based SSAO/PrAO-inhibitors, and reference agents. None of the inhibitors was able to impair the sevenfold activation of 2-deoxyglucose uptake induced by insulin. Phenelzine did not hamper the effect of lower doses of insulin. However, insulin-stimulated glucose incorporation into lipids was dose-dependently inhibited by phenelzine and pentamidine, but not by semicarbazide or BTT2052. In contrast, all these SSAO/PrAO inhibitors abolished the transport and lipogenesis stimulation induced by benzylamine. These data indicate that phenelzine does not inhibit glucose transport, the first step of lipogenesis, but inhibits at 100 μM the intracellular triacylglycerol assembly, consistently with its long-term anti-adipogenic effect and such rapid action was not found with all the hydrazine derivatives tested. Therefore, the alterations of body weight control consecutive to the use of this antidepressant drug might be not only related to central effects on food intake/energy expenditure, but could also depend on its direct action in adipocytes. Nonetheless, phenelzine antilipogenic action is not merely dependent on SSAO/PrAO inhibition.

  12. The phosphatase inhibitor menadione (vitamin K3) protects cells from EGFR inhibition by erlotinib and cetuximab.

    Science.gov (United States)

    Perez-Soler, Roman; Zou, Yiyu; Li, Tianhong; Ling, Yi He

    2011-11-01

    Skin toxicity is the main side effect of epidermal growth factor receptor (EGFR) inhibitors, often leading to dose reduction or discontinuation. We hypothesized that phosphatase inhibition in the skin keratinocytes may prevent receptor dephosphorylation caused by EGFR inhibitors and be used as a new potential strategy for the prevention or treatment of this side effect. Menadione (Vitamin K3) was used as the prototype compound to test our hypothesis. HaCat human skin keratinocyte cells and A431 human squamous carcinoma cells were used. EGFR inhibition was measured by Western blotting and immunofluorescence. Phosphatase inhibition and reactive oxygen species (ROS) generation were measured by standard ELISA and fluorescence assays. Menadione caused significant and reversible EGFR activation in a dose-dependent manner starting at nontoxic concentrations. EGFR activation by menadione was associated with reversible protein tyrosine phosphatase inhibition, which seemed to be mediated by ROS generation as exposure to antioxidants prevented both menadione-induced ROS generation and phosphatase inhibition. Short-term coincubation of cells with nontoxic concentrations of menadione and the EGFR inhibitors erlotinib or cetuximab prevented EGFR dephosphorylation. Seventy-two-hour coincubation of cells with the highest nontoxic concentration of menadione and erlotinib provided for a fourfold cell growth inhibitory protection in HaCat human keratinocyte cells. Menadione at nontoxic concentrations causes EGFR activation and prevents EGFR dephosphorylation by erlotinib and cetuximab. This effect seems to be mediated by ROS generation and secondary phosphatase inhibition. Mild oxidative stress in skin keratinocytes by topical menadione may protect the skin from the toxicity secondary to EGFR inhibitors without causing cytotoxicity. ©2011 AACR

  13. MEK inhibition potentiates the activity of Hsp90 inhibitor 17-AAG against pancreatic cancer cells.

    Science.gov (United States)

    Zhang, Tao; Li, Yanyan; Zhu, Zhenkun; Gu, Mancang; Newman, Bryan; Sun, Duxin

    2010-10-04

    The Ras/Raf/MEK/ERK signaling has been implicated in uncontrolled cell proliferation and tumor progression in pancreatic cancer. The purpose of this study is to evaluate the antitumor activity of MEK inhibitor U0126 in combination with Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) in pancreatic cancer cells. Western blotting showed that 17-AAG caused a 2- to 3-fold transient activation of MEK/ERK signaling in pancreatic cancer cells. The activation sustained for 6 h before phospho-ERK (p-ERK) destabilization. The selective MEK inhibitor U0126 completely abolished 17-AAG induced ERK1/2 activation and resulted in more than 80% of phospho-ERK degradation after only 15 min treatment. Moreover, U0126 had complementary effect on 17-AAG regulated oncogenic and cell cycle related proteins. Although 17-AAG downregulated cyclin D1, cyclin E, CDK4 and CDK6, it led to cyclin A and CDK2 accumulation, which was reversed by the addition of U0126. Antiproliferation assay showed that combination of U0126 and 17-AAG resulted in synergistic cytotoxic effect. More importantly, 17-AAG alone only exhibited moderate inhibition of cell migration in vitro, while addition of U0126 dramatically enhanced the inhibitory effect by 2- to 5-fold. Taken together, these data demonstrate that MEK inhibitor U0126 potentiates the activity of Hsp90 inhibitor 17-AAG against pancreatic cancer cells. The combination of Hsp90 and MEK inhibition could provide a promising avenue for the treatment of pancreatic cancer.

  14. The human ubiquitin-conjugating enzyme Cdc34 controls cellular proliferation through regulation of p27Kip1 protein levels

    International Nuclear Information System (INIS)

    Butz, Nicole; Ruetz, Stephan; Natt, Francois; Hall, Jonathan; Weiler, Jan; Mestan, Juergen; Ducarre, Monique; Grossenbacher, Rita; Hauser, Patrick; Kempf, Dominique; Hofmann, Francesco

    2005-01-01

    Ubiquitin-mediated degradation of the cyclin-dependent kinase inhibitor p27 Kip1 was shown to be required for the activation of key cyclin-dependent kinases, thereby triggering the onset of DNA replication and cell cycle progression. Although the SCF Skp2 ubiquitin ligase has been reported to mediate p27 Kip1 degradation, the nature of the human ubiquitin-conjugating enzyme involved in this process has not yet been determined at the cellular level. Here, we show that antisense oligonucleotides targeting the human ubiquitin-conjugating enzyme Cdc34 downregulate its expression, inhibit the degradation of p27 Kip1 , and prevent cellular proliferation. Elevation of p27 Kip1 protein level is found to be the sole requirement for the inhibition of cellular proliferation induced upon downregulation of Cdc34. Indeed, reducing the expression of p27 Kip1 with a specific antisense oligonucleotide is sufficient to reverse the anti-proliferative phenotype elicited by the Cdc34 antisense. Furthermore, downregulation of Cdc34 is found to specifically increase the abundance of the SCF Skp2 ubiquitin ligase substrate p27 Kip1 , but has no concomitant effect on the level of IkBα and β-catenin, which are known substrates of a closely related SCF ligase

  15. Protease inhibitors and indoleamines selectively inhibit cholinesterases in the histopathologic structures of Alzheimer disease.

    Science.gov (United States)

    Wright, C I; Guela, C; Mesulam, M M

    1993-01-01

    Neurofibrillary tangles and amyloid plaques express acetylcholinesterase and butyrylcholinesterase activity in Alzheimer disease. We previously reported that traditional acetylcholinesterase inhibitors such as BW284C51, tacrine, and physostigmine were more potent inhibitors of the acetylcholinesterase in normal axons and cell bodies than of the acetylcholinesterase in plaques and tangles. We now report that the reverse pattern is seen with indoleamines (such as serotonin and its precursor 5-hydroxytryptophan), carboxypeptidase inhibitor, and the nonspecific protease inhibitor bacitracin. These substances are more potent inhibitors of the cholinesterases in plaques and tangles than of those in normal axons and cell bodies. These results show that the enzymatic properties of plaque and tangle-associated cholinesterases diverge from those of normal axons and cell bodies. The selective susceptibility to bacitracin and carboxypeptidase inhibitor indicates that the catalytic sites of plaque and tangle-bound cholinesterases are more closely associated with peptidase or protease-like properties than the catalytic sites of cholinesterases in normal axons and cell bodies. This shift in enzymatic affinity may lead to the abnormal protein processing that is thought to play a major role in the pathogenesis of Alzheimer disease. The availability of pharmacological and dietary means for altering brain indoleamines raises therapeutic possibilities for inhibiting the abnormal cholinesterase activity associated with Alzheimer disease. Images PMID:8421706

  16. N-acetyl lysyltyrosylcysteine amide inhibits myeloperoxidase, a novel tripeptide inhibitor1[S

    Science.gov (United States)

    Zhang, Hao; Jing, Xigang; Shi, Yang; Xu, Hao; Du, Jianhai; Guan, Tongju; Weihrauch, Dorothee; Jones, Deron W.; Wang, Weiling; Gourlay, David; Oldham, Keith T.; Hillery, Cheryl A.; Pritchard, Kirkwood A.

    2013-01-01

    Myeloperoxidase (MPO) plays important roles in disease by increasing oxidative and nitrosative stress and oxidizing lipoproteins. Here we report N-acetyl lysyltyrosylcysteine amide (KYC) is an effective inhibitor of MPO activity. We show KYC inhibits MPO-mediated hypochlorous acid (HOCl) formation and nitration/oxidation of LDL. Disulfide is the major product of MPO-mediated KYC oxidation. KYC (⩽4,000 μM) does not induce cytotoxicity in bovine aortic endothelial cells (BAECs). KYC inhibits HOCl generation by phorbol myristate acetate (PMA)-stimulated neutrophils and human promyelocytic leukemia (HL-60) cells but not superoxide generation by PMA-stimulated HL-60 cells. KYC inhibits MPO-mediated HOCl formation in BAEC culture and protects BAECs from MPO-induced injury. KYC inhibits MPO-mediated lipid peroxidation of LDL whereas tyrosine (Tyr) and tryptophan (Trp) enhance oxidation. KYC is unique as its isomers do not inhibit MPO activity, or are much less effective. Ultraviolet-visible spectral studies indicate KYC binds to the active site of MPO and reacts with compounds I and II. Docking studies show the Tyr of KYC rests just above the heme of MPO. Interestingly, KYC increases MPO-dependent H2O2 consumption. These data indicate KYC is a novel and specific inhibitor of MPO activity that is nontoxic to endothelial cell cultures. Accordingly, KYC may be useful for treating MPO-mediated vascular disease. PMID:23883583

  17. N-acetyl lysyltyrosylcysteine amide inhibits myeloperoxidase, a novel tripeptide inhibitor.

    Science.gov (United States)

    Zhang, Hao; Jing, Xigang; Shi, Yang; Xu, Hao; Du, Jianhai; Guan, Tongju; Weihrauch, Dorothee; Jones, Deron W; Wang, Weiling; Gourlay, David; Oldham, Keith T; Hillery, Cheryl A; Pritchard, Kirkwood A

    2013-11-01

    Myeloperoxidase (MPO) plays important roles in disease by increasing oxidative and nitrosative stress and oxidizing lipoproteins. Here we report N-acetyl lysyltyrosylcysteine amide (KYC) is an effective inhibitor of MPO activity. We show KYC inhibits MPO-mediated hypochlorous acid (HOCl) formation and nitration/oxidation of LDL. Disulfide is the major product of MPO-mediated KYC oxidation. KYC (≤4,000 μM) does not induce cytotoxicity in bovine aortic endothelial cells (BAECs). KYC inhibits HOCl generation by phorbol myristate acetate (PMA)-stimulated neutrophils and human promyelocytic leukemia (HL-60) cells but not superoxide generation by PMA-stimulated HL-60 cells. KYC inhibits MPO-mediated HOCl formation in BAEC culture and protects BAECs from MPO-induced injury. KYC inhibits MPO-mediated lipid peroxidation of LDL whereas tyrosine (Tyr) and tryptophan (Trp) enhance oxidation. KYC is unique as its isomers do not inhibit MPO activity, or are much less effective. Ultraviolet-visible spectral studies indicate KYC binds to the active site of MPO and reacts with compounds I and II. Docking studies show the Tyr of KYC rests just above the heme of MPO. Interestingly, KYC increases MPO-dependent H₂O₂ consumption. These data indicate KYC is a novel and specific inhibitor of MPO activity that is nontoxic to endothelial cell cultures. Accordingly, KYC may be useful for treating MPO-mediated vascular disease.

  18. Dihydrocoumarin, an HDAC Inhibitor, Increases DNA Damage Sensitivity by Inhibiting Rad52

    Directory of Open Access Journals (Sweden)

    Chin-Chuan Chen

    2017-12-01

    Full Text Available Effective DNA repair enables cancer cells to survive DNA damage induced by chemotherapeutic or radiotherapeutic treatments. Therefore, inhibiting DNA repair pathways is a promising therapeutic strategy for increasing the efficacy of such treatments. In this study, we found that dihydrocoumarin (DHC, a flavoring agent, causes deficiencies in double-stand break (DSB repair and prolonged DNA damage checkpoint recovery in yeast. Following DNA damage, Rad52 recombinase was revealed to be inhibited by DHC, which results in deficiencies in DSB repair and prolonged DNA damage checkpoint recovery. The deletion of RPD3, a class I histone deacetylase (HDAC, was found to mimic DHC-induced suppression of Rad52 expression, suggesting that the HDAC inhibitor activity of DHC is critical to DSB repair and DNA damage sensitivity. Overall, our findings delineate the regulatory mechanisms of DHC in DSB repair and suggest that it might potentially be used as an inhibitor of the DNA repair pathway in human cells.

  19. An Ectosteric Inhibitor of Cathepsin K Inhibits Bone Resorption in Ovariectomized Mice

    DEFF Research Database (Denmark)

    Panwar, Preety; Xue, Liming; Søe, Kent

    2017-01-01

    The potent cathepsin K (CatK) inhibitor, Tanshinone IIA sulfonic sodium (T06), was tested for its in vitro and in vivo antiresorptive activities. T06 binds in an ectosteric site of CatK remote from its active site and selectively inhibits collagen degradation with an IC50 value of 2.7±0.2μM (CatK...

  20. Inhibition of herpes simplex virus type 1 entry by chloride channel inhibitors tamoxifen and NPPB

    International Nuclear Information System (INIS)

    Zheng, Kai; Chen, Maoyun; Xiang, Yangfei; Ma, Kaiqi; Jin, Fujun; Wang, Xiao; Wang, Xiaoyan; Wang, Shaoxiang; Wang, Yifei

    2014-01-01

    Highlights: • We analyze the anti-HSV potential of chloride channel inhibitors. • Tamoxifen and NPPB show anti-HSV-1 and anti-ACV-resistant HSV-1 activities. • HSV-1 infection induces intracellular chloride concentration increasing. • Tamoxifen and NPPB inhibit HSV-1 early infection. • Tamoxifen and NPPB prevent the fusion process of HSV-1. - Abstract: Herpes simplex virus type 1 (HSV-1) infection is very common worldwide and can cause significant health problems from periodic skin and corneal lesions to encephalitis. Appearance of drug-resistant viruses in clinical therapy has made exploring novel antiviral agents emergent. Here we show that chloride channel inhibitors, including tamoxifen and 5-nitro-2-(3-phenyl-propylamino) benzoic acid (NPPB), exhibited extensive antiviral activities toward HSV-1 and ACV-resistant HSV viruses. HSV-1 infection induced chloride ion influx while treatment with inhibitors reduced the increase of intracellular chloride ion concentration. Pretreatment or treatment of inhibitors at different time points during HSV-1 infection all suppressed viral RNA synthesis, protein expression and virus production. More detailed studies demonstrated that tamoxifen and NPPB acted as potent inhibitors of HSV-1 early entry step by preventing viral binding, penetration and nuclear translocation. Specifically the compounds appeared to affect viral fusion process by inhibiting virus binding to lipid rafts and interrupting calcium homeostasis. Taken together, the observation that tamoxifen and NPPB can block viral entry suggests a stronger potential for these compounds as well as other ion channel inhibitors in antiviral therapy against HSV-1, especially the compound tamoxifen is an immediately actionable drug that can be reused for treatment of HSV-1 infections

  1. Inhibition of herpes simplex virus type 1 entry by chloride channel inhibitors tamoxifen and NPPB

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Kai [Guangzhou Jinan Biomedicine Research and Development Center, National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou (China); College of Life Science and Technology, Jinan University, Guangzhou (China); Chen, Maoyun [Guangzhou Jinan Biomedicine Research and Development Center, National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou (China); College of pharmacy, Jinan University, Guangzhou (China); Xiang, Yangfei; Ma, Kaiqi [Guangzhou Jinan Biomedicine Research and Development Center, National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou (China); Jin, Fujun [Guangzhou Jinan Biomedicine Research and Development Center, National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou (China); College of pharmacy, Jinan University, Guangzhou (China); Wang, Xiao [School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou 510006 (China); Wang, Xiaoyan; Wang, Shaoxiang [Guangzhou Jinan Biomedicine Research and Development Center, National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou (China); Wang, Yifei, E-mail: twang-yf@163.com [Guangzhou Jinan Biomedicine Research and Development Center, National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou (China)

    2014-04-18

    Highlights: • We analyze the anti-HSV potential of chloride channel inhibitors. • Tamoxifen and NPPB show anti-HSV-1 and anti-ACV-resistant HSV-1 activities. • HSV-1 infection induces intracellular chloride concentration increasing. • Tamoxifen and NPPB inhibit HSV-1 early infection. • Tamoxifen and NPPB prevent the fusion process of HSV-1. - Abstract: Herpes simplex virus type 1 (HSV-1) infection is very common worldwide and can cause significant health problems from periodic skin and corneal lesions to encephalitis. Appearance of drug-resistant viruses in clinical therapy has made exploring novel antiviral agents emergent. Here we show that chloride channel inhibitors, including tamoxifen and 5-nitro-2-(3-phenyl-propylamino) benzoic acid (NPPB), exhibited extensive antiviral activities toward HSV-1 and ACV-resistant HSV viruses. HSV-1 infection induced chloride ion influx while treatment with inhibitors reduced the increase of intracellular chloride ion concentration. Pretreatment or treatment of inhibitors at different time points during HSV-1 infection all suppressed viral RNA synthesis, protein expression and virus production. More detailed studies demonstrated that tamoxifen and NPPB acted as potent inhibitors of HSV-1 early entry step by preventing viral binding, penetration and nuclear translocation. Specifically the compounds appeared to affect viral fusion process by inhibiting virus binding to lipid rafts and interrupting calcium homeostasis. Taken together, the observation that tamoxifen and NPPB can block viral entry suggests a stronger potential for these compounds as well as other ion channel inhibitors in antiviral therapy against HSV-1, especially the compound tamoxifen is an immediately actionable drug that can be reused for treatment of HSV-1 infections.

  2. STRUCTURAL ASPECTS OF STRONG INHIBITION AND ROLE OF SCAFFOLD FOR SERINE PROTEASE INHIBITORS

    Directory of Open Access Journals (Sweden)

    Jhimli Dasgupta

    2011-12-01

    Full Text Available Canonical serine protease inhibitors inhibit their cognate enzymes by binding tightly at the enzyme active site in a substrate-like manner, being cleaved extremely slowly compared to a true substrate. They interact with cognate enzymes through P3-P2 region of the inhibitory loop while the scaffold hardly makes any contact. Neighbouring scaffolding residues like arginine or asparagine shape-up the inhibitory loop and religate the cleaved scissile bond. The specificity of the inhibitor can be altered by mutating the hyper solvent accessible P1 residue without changing loop-scaffold interactions. To understand the loop-scaffold compatibility, we prepared three chimeric proteins ECIL-WCIS , ETIL-WCIS , and STIL-WCIS , where the inhibitory loops of ECI, ETI, and STI were placed on the scaffold of their homologue WCI. Results showed that although ECIL-WCIS and STIL-WCIS behave like inhibitors, ETIL-WCIS behaves like a substrate. Crystal structure of ETIL-WCIS and its comparison with ETI indicated that three novel scaffolding residues Trp88, Arg74, and Tyr113 in ETI act as barrier to confine the inhibitory loop to canonical conformation. Absence of this barrier in the scaffold of WCI makes the inhibitory loop flexible in ETIL-WCIS leading to a loss of canonical conformation, explaining its substrate-like behaviour. Furthermore, complex structures of the inhibitors with their cognate enzymes indicate that rigidification of the inhibitory loop at the enzyme active site is necessary for efficient inhibition.

  3. Proteasome inhibitors activate autophagy involving inhibition of PI3K-Akt-mTOR pathway as an anti-oxidation defense in human RPE cells.

    Directory of Open Access Journals (Sweden)

    Bingrong Tang

    Full Text Available The two major intracellular protein degradation systems, the ubiquitin-proteasome system (UPS and autophagy, work collaboratively in many biological processes including development, apoptosis, aging, and countering oxidative injuries. We report here that, in human retinal pigment epithelial cells (RPE, ARPE-19 cells, proteasome inhibitors, clasto-lactacystinβ-lactone (LA or epoxomicin (Epo, at non-lethal doses, increased the protein levels of autophagy-specific genes Atg5 and Atg7 and enhanced the conversion of microtubule-associated protein light chain (LC3 from LC3-I to its lipidative form, LC3-II, which was enhanced by co-addition of the saturated concentration of Bafilomycin A1 (Baf. Detection of co-localization for LC3 staining and labeled-lysosome further confirmed autophagic flux induced by LA or Epo. LA or Epo reduced the phosphorylation of the protein kinase B (Akt, a downstream target of phosphatidylinositol-3-kinases (PI3K, and mammalian target of rapamycin (mTOR in ARPE-19 cells; by contrast, the induced changes of autophagy substrate, p62, showed biphasic pattern. The autophagy inhibitor, Baf, attenuated the reduction in oxidative injury conferred by treatment with low doses of LA and Epo in ARPE-19 cells exposed to menadione (VK3 or 4-hydroxynonenal (4-HNE. Knockdown of Atg7 with siRNA in ARPE-19 cells reduced the protective effects of LA or Epo against VK3. Overall, our results suggest that treatment with low levels of proteasome inhibitors confers resistance to oxidative injury by a pathway involving inhibition of the PI3K-Akt-mTOR pathway and activation of autophagy.

  4. Inhibition of protease-inhibitor resistant hepatitis C virus replicons and infectious virus by intracellular intrabodies

    Science.gov (United States)

    Gal-Tanamy, Meital; Zemel, Romy; Bachmatov, Larissa; Jangra, Rohit K.; Shapira, Assaf; Villanueva, Rodrigo; Yi, MinKyung; Lemon, Stanley M.; Benhar, Itai; Tur-Kaspa, Ran

    2015-01-01

    Hepatitis C virus (HCV) infection is a common cause of chronic liver disease and a serious threat to human health. The HCV NS3/4A serine protease is necessary for viral replication and innate immune evasion, and represents a well-validated target for specific antiviral therapy. We previously reported the isolation of single-chain antibodies (scFvs) that inhibit NS3/4A protease activity in vitro. Expressed intracellularly (intrabodies), these scFvs blocked NS3-mediated proliferation of NS3-transfected cells. Here we show that anti-NS3 scFvs suppress HCV RNA replication when expressed intracellularly in Huh7 hepatoma cells bearing either subgenomic or genome-length HCV RNA replicons. The expression of intrabodies directed against NS3 inhibited the autonomous amplification of HCV replicons resistant to small molecule inhibitors of the NS3/4A protease, and replicons derived from different HCV genotypes. The combination of intrabodies and interferon-α had an additive inhibitory effect on RNA replication in the replicon model. Intrabody expression also inhibited production of infectious HCV in a cell culture system. The NS3 protease activity was inhibited by the intrabodies in NS3-expressing cells. In contrast, cell-free synthesis of HCV RNA by preformed replicase complexes was not inhibited by intrabodies, suggesting that the major mode of inhibition of viral replication is inhibition of NS3/4A protease activity and subsequent suppression of viral polyprotein processing. PMID:20705106

  5. Linear ubiquitination in immunity.

    Science.gov (United States)

    Shimizu, Yutaka; Taraborrelli, Lucia; Walczak, Henning

    2015-07-01

    Linear ubiquitination is a post-translational protein modification recently discovered to be crucial for innate and adaptive immune signaling. The function of linear ubiquitin chains is regulated at multiple levels: generation, recognition, and removal. These chains are generated by the linear ubiquitin chain assembly complex (LUBAC), the only known ubiquitin E3 capable of forming the linear ubiquitin linkage de novo. LUBAC is not only relevant for activation of nuclear factor-κB (NF-κB) and mitogen-activated protein kinases (MAPKs) in various signaling pathways, but importantly, it also regulates cell death downstream of immune receptors capable of inducing this response. Recognition of the linear ubiquitin linkage is specifically mediated by certain ubiquitin receptors, which is crucial for translation into the intended signaling outputs. LUBAC deficiency results in attenuated gene activation and increased cell death, causing pathologic conditions in both, mice, and humans. Removal of ubiquitin chains is mediated by deubiquitinases (DUBs). Two of them, OTULIN and CYLD, are constitutively associated with LUBAC. Here, we review the current knowledge on linear ubiquitination in immune signaling pathways and the biochemical mechanisms as to how linear polyubiquitin exerts its functions distinctly from those of other ubiquitin linkage types. © 2015 The Authors. Immunological Reviews Published by John Wiley & Sons Ltd.

  6. The human otubain2-ubiquitin structure provides insights into the cleavage specificity of poly-ubiquitin-linkages.

    Directory of Open Access Journals (Sweden)

    Mikael Altun

    Full Text Available Ovarian tumor domain containing proteases cleave ubiquitin (Ub and ubiquitin-like polypeptides from proteins. Here we report the crystal structure of human otubain 2 (OTUB2 in complex with a ubiquitin-based covalent inhibitor, Ub-Br2. The ubiquitin binding mode is oriented differently to how viral otubains (vOTUs bind ubiquitin/ISG15, and more similar to yeast and mammalian OTUs. In contrast to OTUB1 which has exclusive specificity towards Lys48 poly-ubiquitin chains, OTUB2 cleaves different poly-Ub linked chains. N-terminal tail swapping experiments between OTUB1 and OTUB2 revealed how the N-terminal structural motifs in OTUB1 contribute to modulating enzyme activity and Ub-chain selectivity, a trait not observed in OTUB2, supporting the notion that OTUB2 may affect a different spectrum of substrates in Ub-dependent pathways.

  7. Inhibition of influenza virus infection and hemagglutinin cleavage by the protease inhibitor HAI-2

    Energy Technology Data Exchange (ETDEWEB)

    Hamilton, Brian S.; Chung, Changik; Cyphers, Soreen Y.; Rinaldi, Vera D.; Marcano, Valerie C.; Whittaker, Gary R., E-mail: grw7@cornell.edu

    2014-07-25

    Highlights: • Biochemical and cell biological analysis of HAI-2 as an inhibitor of influenza HA cleavage activation. • Biochemical and cell biological analysis of HAI-2 as an inhibitor of influenza virus infection. • Comparative analysis of HAI-2 for vesicular stomatitis virus and human parainfluenza virus type-1. • Analysis of the activity of HAI-2 in a mouse model of influenza. - Abstract: Influenza virus remains a significant concern to public health, with the continued potential for a high fatality pandemic. Vaccination and antiviral therapeutics are effective measures to circumvent influenza virus infection, however, multiple strains have emerged that are resistant to the antiviral therapeutics currently on the market. With this considered, investigation of alternative antiviral therapeutics is being conducted. One such approach is to inhibit cleavage activation of the influenza virus hemagglutinin (HA), which is an essential step in the viral replication cycle that permits viral-endosome fusion. Therefore, targeting trypsin-like, host proteases responsible for HA cleavage in vivo may prove to be an effective therapeutic. Hepatocyte growth factor activator inhibitor 2 (HAI-2) is naturally expressed in the respiratory tract and is a potent inhibitor of trypsin-like serine proteases, some of which have been determined to cleave HA. In this study, we demonstrate that HAI-2 is an effective inhibitor of cleavage of HA from the human-adapted H1 and H3 subtypes. HAI-2 inhibited influenza virus H1N1 infection in cell culture, and HAI-2 administration showed protection in a mouse model of influenza. HAI-2 has the potential to be an effective, alternative antiviral therapeutic for influenza.

  8. Inhibition of influenza virus infection and hemagglutinin cleavage by the protease inhibitor HAI-2

    International Nuclear Information System (INIS)

    Hamilton, Brian S.; Chung, Changik; Cyphers, Soreen Y.; Rinaldi, Vera D.; Marcano, Valerie C.; Whittaker, Gary R.

    2014-01-01

    Highlights: • Biochemical and cell biological analysis of HAI-2 as an inhibitor of influenza HA cleavage activation. • Biochemical and cell biological analysis of HAI-2 as an inhibitor of influenza virus infection. • Comparative analysis of HAI-2 for vesicular stomatitis virus and human parainfluenza virus type-1. • Analysis of the activity of HAI-2 in a mouse model of influenza. - Abstract: Influenza virus remains a significant concern to public health, with the continued potential for a high fatality pandemic. Vaccination and antiviral therapeutics are effective measures to circumvent influenza virus infection, however, multiple strains have emerged that are resistant to the antiviral therapeutics currently on the market. With this considered, investigation of alternative antiviral therapeutics is being conducted. One such approach is to inhibit cleavage activation of the influenza virus hemagglutinin (HA), which is an essential step in the viral replication cycle that permits viral-endosome fusion. Therefore, targeting trypsin-like, host proteases responsible for HA cleavage in vivo may prove to be an effective therapeutic. Hepatocyte growth factor activator inhibitor 2 (HAI-2) is naturally expressed in the respiratory tract and is a potent inhibitor of trypsin-like serine proteases, some of which have been determined to cleave HA. In this study, we demonstrate that HAI-2 is an effective inhibitor of cleavage of HA from the human-adapted H1 and H3 subtypes. HAI-2 inhibited influenza virus H1N1 infection in cell culture, and HAI-2 administration showed protection in a mouse model of influenza. HAI-2 has the potential to be an effective, alternative antiviral therapeutic for influenza

  9. Apyrase inhibitors enhance the ability of diverse fungicides to inhibit the growth of different plant-pathogenic fungi.

    Science.gov (United States)

    Kumar Tripathy, Manas; Weeraratne, Gayani; Clark, Greg; Roux, Stanley J

    2017-09-01

    A previous study has demonstrated that the treatment of Arabidopsis plants with chemical inhibitors of apyrase enzymes increases their sensitivity to herbicides. In this study, we found that the addition of the same or related apyrase inhibitors could potentiate the ability of different fungicides to inhibit the growth of five different pathogenic fungi in plate growth assays. The growth of all five fungi was partially inhibited by three commonly used fungicides: copper octanoate, myclobutanil and propiconazole. However, when these fungicides were individually tested in combination with any one of four different apyrase inhibitors (AI.1, AI.10, AI.13 or AI.15), their potency to inhibit the growth of five fungal pathogens was increased significantly relative to their application alone. The apyrase inhibitors were most effective in potentiating the ability of copper octanoate to inhibit fungal growth, and least effective in combination with propiconazole. Among the five pathogens assayed, that most sensitive to the fungicide-potentiating effects of the inhibitors was Sclerotinia sclerotiorum. Overall, among the 60 treatment combinations tested (five pathogens, four apyrase inhibitors, three fungicides), the addition of apyrase inhibitors increased significantly the sensitivity of fungi to the fungicide treatments in 53 of the combinations. Consistent with their predicted mode of action, inhibitors AI.1, AI.10 and AI.13 each increased the level of propiconazole retained in one of the fungi, suggesting that they could partially block the ability of efflux transporters to remove propiconazole from these fungi. © 2016 BSPP AND JOHN WILEY & SONS LTD.

  10. The histone deacetylase inhibitor butyrate inhibits melanoma cell invasion of Matrigel.

    Science.gov (United States)

    Kuwajima, Akiko; Iwashita, Jun; Murata, Jun; Abe, Tatsuya

    2007-01-01

    Histone deacetylase (HDAC) inhibitors have anticancer effects. Their effects on expression of cell adhesion molecules might be related to their effects on tumor cell invasion. Murine B16-BL6 cells were treated with the HDAC inhibitors, butyrate or trichostatin A. Melanoma cell invasion of the artificial basement membrane, Matrigel, was examined by Transwell chamber assay. Butyrate as well as trichostatin A inhibited the cell growth mainly by arresting the cell cycle. The cell invasion of Matrigel was inhibited by butyrate and trichostatin A. The butyrate treatment increased the cell-cell aggregation, although neither E-cadherin nor N-cadherin mRNA were up-regulated. Both mRNA expression and protein levels of the immunoglobulin superfamily cell adhesion molecules, Mel-CAM and L1-CAM, were increased in the butyrate-treated cells. The HDAC inhibitor butyrate blocked the B16-BL6 melanoma cell invasion of Matrigel, although it increased the expression of Mel-CAM and L1-CAM which are important to the metastatic potential.

  11. Level of ubiquitinated histone H2B in chromatin is coupled to ongoing transcription

    International Nuclear Information System (INIS)

    Davie, J.R.; Murphy, L.C.

    1990-01-01

    The relationship between transcription and ubiquitination of the histones was investigated. Previous studies have shown that ubiquitinated (u) histone H2B and, to a lesser extend, mono- and polyubiquitinated histone H2A are enriched in transcriptionally active gene-enriched chromatin fractions. Here, the authors show that treatment of T-47D-5 human breast cancer cells with actinomycin D or 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole, inhibitors of heterogeneous nuclear RNA synthesis, selectively reduced the level of uH2B, but not uH2A, uH2A.Z, or polyubiquitinated H2A, in chromatin. Treatment of the cells with low levels of actinomycin D slightly reduced the level of uH2B, suggesting that inhibition of ribosomal RNA synthesis does not have a profound effect on the level of uH2B in chromatin. These results demonstrate that maintenance of the levels of uH2B in chromatin is dependent upon ongoing transcription, particularly the synthesis of hnRNA. Thus, histone H2B would be ubiquitinated when the nucleosome was opened during transcription. Ubiquitination of histone H2B may impede nucleosome refolding, facilitating subsequent rounds of transcription

  12. Atomic structure of the APC/C and its mechanism of protein ubiquitination

    Science.gov (United States)

    Yang, Jing; McLaughlin, Stephen H.; Barford, David

    2015-01-01

    The anaphase-promoting complex (APC/C) is a multimeric RING E3 ubiquitin ligase that controls chromosome segregation and mitotic exit. Its regulation by coactivator subunits, phosphorylation, the mitotic checkpoint complex, and interphase inhibitor Emi1 ensures the correct order and timing of distinct cell cycle transitions. Here, we used cryo-electron microscopy to determine atomic structures of APC/C-coactivator complexes with either Emi1 or a UbcH10-ubiquitin conjugate. These structures define the architecture of all APC/C subunits, the position of the catalytic module, and explain how Emi1 mediates inhibition of the two E2s UbcH10 and Ube2S. Definition of Cdh1 interactions with the APC/C indicates how they are antagonized by Cdh1 phosphorylation. The structure of the APC/C with UbcH10-ubiquitin reveals insights into the initiating ubiquitination reaction. Our results provide a quantitative framework for the design of experiments to further investigate APC/C functions in vivo. PMID:26083744

  13. Assessing Subunit Dependency of the Plasmodium Proteasome Using Small Molecule Inhibitors and Active Site Probes

    NARCIS (Netherlands)

    Li, H.; Linden, W.A. van der; Verdoes, M.; Florea, B.I.; McAllister, F.E.; Govindaswamy, K.; Elias, J.E.; Bhanot, P.; Overkleeft, H.S.; Bogyo, M.

    2014-01-01

    The ubiquitin-proteasome system (UPS) is a potential pathway for therapeutic intervention for pathogens such as Plasmodium, the causative agent of malaria. However, due to the essential nature of this proteolytic pathway, proteasome inhibitors must avoid inhibition of the host enzyme complex to

  14. Deubiquitinase inhibitor b-AP15 activates endoplasmic reticulum (ER) stress and inhibits Wnt/Notch1 signaling pathway leading to the reduction of cell survival in hepatocellular carcinoma cells.

    Science.gov (United States)

    Ding, Youming; Chen, Xiaoyan; Wang, Bin; Yu, Bin; Ge, Jianhui

    2018-04-15

    b-AP15, a potent and selective inhibitor of the ubiquitin-specific peptidase 14 (USP14), displays in vitro and in vivo antitumor abilities on some types of cancer cells. However, the mechanism underlying its action is not well elucidated. The purposes of the present study are to observe the potential impacts of b-AP15 on cell survival of hepatocellular carcinoma cells and to investigate whether and how this compound inhibits some survival-promoting signaling pathways. We found that b-AP15 significantly decreased cell viability and increased cell apoptosis in a dose-dependent manner in hepatocellular carcinoma cells, along with the perturbation of cell cycle and the decreased expressions of cell cycle-related proteins. We also demonstrated that the endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) were enhanced by b-AP15 supplementation. The inhibition of ER stress/UPR only partly attenuated the cytotoxicity of b-AP15 on hepatocellular carcinoma cells. In addition, b-AP15 treatment inhibited Wnt/β-catenin and Notch1 signaling pathways, and suppressed phosphorylation of STAT3, Akt, and Erk1/2, which were not restored by the inhibition of ER stress/UPR. Furthermore, the expression levels of signaling molecules in Notch1 were reduced by specific inhibitor of Wnt/β-catenin pathway. Notably, either Wnt or Notch1 signaling inhibitor mitigated phosphorylation of STAT3, Akt, and Erk1/2, and mimicked the cytotoxicity of b-AP15 on hepatocellular carcinoma cells. These results clearly indicate that b-AP15 induced cytotoxic response to hepatocellular carcinoma cells by augmenting ER stress/UPR and inhibiting Wnt/Notch1 signaling pathways. This new finding provides a novel mechanism by which b-AP15 produces its antitumor therapeutic effects. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Characteristics of the Inhibition of Potato (Solanum tuberosum) Invertase by an Endogenous Proteinaceous Inhibitor in Potatoes

    Science.gov (United States)

    Bracho, Geracimo E.; Whitaker, John R.

    1990-01-01

    Effect of several parameters on inhibition of potato (Solanum tuberosum) invertase by its endogenous proteinaceous inhibitor was determined using homogeneous preparations of both proteins. The inhibitor and invertase formed an inactive complex with an observed association rate constant at pH 4.70 and 37°C of 8.82 × 102 per molar per second and a dissociation rate constant of 3.3 × 10−3 per minute. The inhibitor appeared to bind to invertase in more than one step. Initial interaction (measured by loss of invertase activity) was rapid, relatively weak, readily reversible (Ki of 2 × 10−6 molar) and noncompetitive with substrate at pH 4.70. Initial interaction was probably followed by isomerization to a tighter (Ki of 6.23 × 10−8 molar) complex, which dissociated slowly with a half-time of 3.5 hour. Interaction between enzyme and inhibitor appeared to be of ionic character and essentially pH independent between pH 3.5 and 7.4. PMID:16667286

  16. Inhibition of growth hormone and prolactin secretion by a serine proteinase inhibitor

    International Nuclear Information System (INIS)

    Rappay, G.; Nagy, I.; Makara, G.B.; Horvath, G.; Karteszi, M.; Bacsy, E.; Stark, E.

    1984-01-01

    The action of the tripeptide aldehyde t-butyloxycarbonyl-DPhe-Pro-Arg-H (boc-fPR-H), belonging to a family of serine proteinase inhibitors, on the release of immunoreactive prolactin (iPRL) and growth hormone (iGH) has been studied. In rat anterior pituitary cell cultures and pituitary quarters 1 mM boc-fPR-H inhibited basal iPRL and iGH release. Thyroliberin-induced iPRL release by cultured cells was also markedly inhibited with a concomitant accumulation of intracellular iPRL. During the short- and long-term exposure of cells to boc-fPR-H there were no changes in total cell protein contents and in activities of some lysosomal marker enzymes. The marked inhibition of basal as well as stimulated hormone release in the presence of the enzyme inhibitor might suggest that at least a portion of the hormones is released via a proteolytic enzyme-dependent process

  17. The histone deacetylase inhibitor, Vorinostat, represses hypoxia inducible factor 1 alpha expression through translational inhibition.

    Directory of Open Access Journals (Sweden)

    Darren M Hutt

    Full Text Available Hypoxia inducible factor 1α (HIF-1α is a master regulator of tumor angiogenesis being one of the major targets for cancer therapy. Previous studies have shown that Histone Deacetylase Inhibitors (HDACi block tumor angiogenesis through the inhibition of HIF-1α expression. As such, Vorinostat (Suberoylanilide Hydroxamic Acid/SAHA and Romidepsin, two HDACis, were recently approved by the Food and Drug Administration (FDA for the treatment of cutaneous T cell lymphoma. Although HDACis have been shown to affect HIF-1α expression by modulating its interactions with the Hsp70/Hsp90 chaperone axis or its acetylation status, the molecular mechanisms by which HDACis inhibit HIF-1α expression need to be further characterized. Here, we report that the FDA-approved HDACi Vorinostat/SAHA inhibits HIF-1α expression in liver cancer-derived cell lines, by a new mechanism independent of p53, prolyl-hydroxylases, autophagy and proteasome degradation. We found that SAHA or silencing of HDAC9 mechanism of action is due to inhibition of HIF-1α translation, which in turn, is mediated by the eukaryotic translation initiation factor--eIF3G. We also highlighted that HIF-1α translation is dramatically inhibited when SAHA is combined with eIF3H silencing. Taken together, we show that HDAC activity regulates HIF-1α translation, with HDACis such as SAHA representing a potential novel approach for the treatment of hepatocellular carcinoma.

  18. Cysteine protease inhibition by nitrile-based inhibitors: a computational study

    Science.gov (United States)

    Quesne, Matthew G.; Ward, Richard A.; de Visser, Sam P.

    2013-01-01

    Cysteine protease enzymes are important for human physiology and catalyze key protein degradation pathways. These enzymes react via a nucleophilic reaction mechanism that involves a cysteine residue and the proton of a proximal histidine. Particularly efficient inhibitors of these enzymes are nitrile-based, however, the details of the catalytic reaction mechanism currently are poorly understood. To gain further insight into the inhibition of these molecules, we have performed a combined density functional theory and quantum mechanics/molecular mechanics study on the reaction of a nitrile-based inhibitor with the enzyme active site amino acids. We show here that small perturbations to the inhibitor structure can have dramatic effects on the catalysis and inhibition processes. Thus, we investigated a range of inhibitor templates and show that specific structural changes reduce the inhibitory efficiency by several orders of magnitude. Moreover, as the reaction takes place on a polar surface, we find strong differences between the DFT and QM/MM calculated energetics. In particular, the DFT model led to dramatic distortions from the starting structure and the convergence to a structure that would not fit the enzyme active site. In the subsequent QM/MM study we investigated the use of mechanical vs. electronic embedding on the kinetics, thermodynamics and geometries along the reaction mechanism. We find minor effects on the kinetics of the reaction but large geometric and thermodynamics differences as a result of inclusion of electronic embedding corrections. The work here highlights the importance of model choice in the investigation of this biochemical reaction mechanism. PMID:24790966

  19. Corrosion inhibition by inorganic cationic inhibitors on the high strength alumunium alloy, 2024-T3

    Science.gov (United States)

    Chilukuri, Anusha

    The toxicity and carcinogenic nature of chromates has led to the investigation of environmentally friendly compounds that offer good corrosion resistance to AA 2024-T3. Among the candidate inhibitors are rare earth metal cationic (REM) and zinc compounds, which have received much of attention over the past two decades. A comparative study on the corrosion inhibition caused by rare earth metal cations, Ce3+, Pr3+, La3+ and Zn2+ cations on the alloy was done. Cathodic polarization showed that these inhibitor ions suppress the oxygen reduction reaction (ORR) to varying extents with Zn2+ providing the best inhibition. Pr3+ exhibited windows of concentration (100-300 ppm) in which the corrosion rate is minimum; similar to the Ce3+ cation. Scanning Electron Microscopy (SEM) studies showed that the mechanism of inhibition of the Pr3+ ion is also similar to that of the Ce3+ ion. Potentiodynamic polarization experiments after 30 min immersion time showed greatest suppression of oxygen reduction reaction in neutral chloride solutions (pH 7), which reached a maximum at a Zn2+ ion concentration of 5 mM. Anodic polarization experiments after 30 min immersion time, showed no anodic inhibition by the inhibitor in any concentration (0.1 mM - 10 mM) and at any pH. However, anodic polarization of samples immersed after longer immersion times (upto 4 days) in mildly acidic Zn2+ (pH 4) solutions showed significant reduction in anodic kinetics indicating that zinc also acts as a “slow anodic inhibitor”. In contrast to the polarization experiments, coupons exposed to inhibited acidic solutions at pH 4 showed complete suppression of dissolution of Al2CuMg particles compared to zinc-free solutions in the SEM studies. Samples exposed in pH 4 Zn2+-bearing solution exhibited highest polarization resistance which was also observed to increase with time. In deaerated solutions, the inhibition by Zn2+ at pH 4 is not observed as strongly. The ability to make the interfacial electrolyte

  20. Structural Basis for Specific Inhibition of tRNA Synthetase by an ATP Competitive Inhibitor

    OpenAIRE

    Fang, Pengfei; Han, Hongyan; Wang, Jing; Chen, Kaige; Chen, Xin; Guo, Min

    2015-01-01

    Pharmaceutical inhibitors of aminoacyl-tRNA synthetases demand high species and family specificity. The antimalarial ATP-mimetic cladosporin selectively inhibits P. falciparum LysRS (PfLysRS). How the binding to a universal ATP site achieves the specificity is unknown. Here we report 3 crystal structures of cladosporin with human LysRS, PfLysRS, and a Pf-like human LysRS mutant. In all 3 structures, cladosporin occupies the class defining ATP-binding pocket, replacing the adenosine portion of...

  1. Ubiquitination in apoptosis signaling

    NARCIS (Netherlands)

    van de Kooij, L.W.

    2014-01-01

    The work described in this thesis focuses on ubiquitination and protein degradation, with an emphasis on how these processes regulate apoptosis signaling. More specifically, our aims were: 1. To increase the understanding of ubiquitin-mediated regulation of apoptosis signaling. 2. To identify the E3

  2. The M358R variant of α{sub 1}-proteinase inhibitor inhibits coagulation factor VIIa

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, William P., E-mail: sheffiel@mcmaster.ca [Canadian Blood Services, Centre for Innovation, Hamilton, Ontario (Canada); Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario (Canada); Bhakta, Varsha [Canadian Blood Services, Centre for Innovation, Hamilton, Ontario (Canada)

    2016-02-12

    The naturally occurring M358R mutation of the plasma serpin α{sub 1}-proteinase inhibitor (API) changes both its cleavable reactive centre bond to Arg–Ser and the efficacy with which it inhibits different proteases, reducing the rate of inhibition of neutrophil elastase, and enhancing that of thrombin, factor XIa, and kallikrein, by several orders of magnitude. Although another plasma serpin with an Arg–Ser reactive centre, antithrombin (AT), has been shown to inhibit factor VIIa (FVIIa), no published data are available with respect to FVIIa inhibition by API M358R. Recombinant bacterially-expressed API M358R and plasma-derived AT were therefore compared using gel-based and kinetic assays of FVIIa integrity and activity. Under pseudo-first order conditions of excess serpin over protease, both AT and API M358R formed denaturation-resistant inhibitory complexes with FVIIa in reactions accelerated by TF; AT, but not API M358R, also required heparin for maximal activity. The second order rate constant for heparin-independent API M358R-mediated FVIIa inhibition was determined to be 7.8 ± 0.8 × 10{sup 2} M{sup −1}sec{sup −1}. We conclude that API M358R inhibits FVIIa by forming inhibitory complexes of the serpin type more rapidly than AT in the absence of heparin. The likely 20-fold excess of API M358R over AT in patient plasma during inflammation raises the possibility that it could contribute to the hemorrhagic tendencies manifested by rare individuals expressing this mutant serpin. - Highlights: • The inhibitory specificity of the serpin alpha-1-proteinase inhibitor (API) is sharply altered in the M358R variant. • API M358R forms denaturation-resistant complexes with coagulation factor VIIa at a rate accelerated by tissue factor but unaffected by heparin. • Complex formation was shown by gel-based assays and quantified kinetically by inhibition of FVIIa-dependent amidolysis.

  3. The M358R variant of α_1-proteinase inhibitor inhibits coagulation factor VIIa

    International Nuclear Information System (INIS)

    Sheffield, William P.; Bhakta, Varsha

    2016-01-01

    The naturally occurring M358R mutation of the plasma serpin α_1-proteinase inhibitor (API) changes both its cleavable reactive centre bond to Arg–Ser and the efficacy with which it inhibits different proteases, reducing the rate of inhibition of neutrophil elastase, and enhancing that of thrombin, factor XIa, and kallikrein, by several orders of magnitude. Although another plasma serpin with an Arg–Ser reactive centre, antithrombin (AT), has been shown to inhibit factor VIIa (FVIIa), no published data are available with respect to FVIIa inhibition by API M358R. Recombinant bacterially-expressed API M358R and plasma-derived AT were therefore compared using gel-based and kinetic assays of FVIIa integrity and activity. Under pseudo-first order conditions of excess serpin over protease, both AT and API M358R formed denaturation-resistant inhibitory complexes with FVIIa in reactions accelerated by TF; AT, but not API M358R, also required heparin for maximal activity. The second order rate constant for heparin-independent API M358R-mediated FVIIa inhibition was determined to be 7.8 ± 0.8 × 10"2 M"−"1sec"−"1. We conclude that API M358R inhibits FVIIa by forming inhibitory complexes of the serpin type more rapidly than AT in the absence of heparin. The likely 20-fold excess of API M358R over AT in patient plasma during inflammation raises the possibility that it could contribute to the hemorrhagic tendencies manifested by rare individuals expressing this mutant serpin. - Highlights: • The inhibitory specificity of the serpin alpha-1-proteinase inhibitor (API) is sharply altered in the M358R variant. • API M358R forms denaturation-resistant complexes with coagulation factor VIIa at a rate accelerated by tissue factor but unaffected by heparin. • Complex formation was shown by gel-based assays and quantified kinetically by inhibition of FVIIa-dependent amidolysis.

  4. Dengue Virus Genome Uncoating Requires Ubiquitination

    Directory of Open Access Journals (Sweden)

    Laura A. Byk

    2016-06-01

    Full Text Available The process of genome release or uncoating after viral entry is one of the least-studied steps in the flavivirus life cycle. Flaviviruses are mainly arthropod-borne viruses, including emerging and reemerging pathogens such as dengue, Zika, and West Nile viruses. Currently, dengue virus is one of the most significant human viral pathogens transmitted by mosquitoes and is responsible for about 390 million infections every year around the world. Here, we examined for the first time molecular aspects of dengue virus genome uncoating. We followed the fate of the capsid protein and RNA genome early during infection and found that capsid is degraded after viral internalization by the host ubiquitin-proteasome system. However, proteasome activity and capsid degradation were not necessary to free the genome for initial viral translation. Unexpectedly, genome uncoating was blocked by inhibiting ubiquitination. Using different assays to bypass entry and evaluate the first rounds of viral translation, a narrow window of time during infection that requires ubiquitination but not proteasome activity was identified. In this regard, ubiquitin E1-activating enzyme inhibition was sufficient to stabilize the incoming viral genome in the cytoplasm of infected cells, causing its retention in either endosomes or nucleocapsids. Our data support a model in which dengue virus genome uncoating requires a nondegradative ubiquitination step, providing new insights into this crucial but understudied viral process.

  5. Inhibitors

    Science.gov (United States)

    ... JM, and the Hemophilia Inhibitor Research Study Investigators. Validation of Nijmegen-Bethesda assay modifications to allow inhibitor ... webinars on blood disorders Language: English (US) Español (Spanish) File Formats Help: How do I view different ...

  6. Isthmin is a novel secreted angiogenesis inhibitor that inhibits tumour growth in mice

    Science.gov (United States)

    Xiang, Wei; Ke, Zhiyuan; Zhang, Yong; Ho-Yuet Cheng, Grace; Irwan, Ishak Darryl; Sulochana, K N; Potturi, Padma; Wang, Zhengyuan; Yang, He; Wang, Jingyu; Zhuo, Lang; Kini, R Manjunatha; Ge, Ruowen

    2011-01-01

    Abstract Anti-angiogenesis represents a promising therapeutic strategy for the treatment of various malignancies. Isthmin (ISM) is a gene highly expressed in the isthmus of the midbrain–hindbrain organizer in Xenopus with no known functions. It encodes a secreted 60 kD protein containing a thrombospondin type 1 repeat domain in the central region and an adhesion-associated domain in MUC4 and other proteins (AMOP) domain at the C-terminal. In this work, we demonstrate that ISM is a novel angiogenesis inhibitor. Recombinant mouse ISM inhibited endothelial cell (EC) capillary network formation on Matrigel through its C-terminal AMOP domain. It also suppressed vascular endothelial growth factor (VEGF)-basic fibroblast growth factor (bFGF) induced in vivo angiogenesis in mouse. It mitigated VEGF-stimulated EC proliferation without affecting EC migration. Furthermore, ISM induced EC apoptosis in the presence of VEGF through a caspase-dependent pathway. ISM binds to αvβ5 integrin on EC surface and supports EC adhesion. Overexpression of ISM significantly suppressed mouse B16 melanoma tumour growth through inhibition of tumour angiogenesis without affecting tumour cell proliferation. Knockdown of isthmin in zebrafish embryos using morpholino antisense oligonucleotides led to disorganized intersegmen-tal vessels in the trunk. Our results demonstrate that ISM is a novel endogenous angiogenesis inhibitor with functions likely in physiological as well as pathological angiogenesis. PMID:19874420

  7. Inhibition of human carboxylesterases hCE1 and hiCE by cholinesterase inhibitors.

    Science.gov (United States)

    Tsurkan, Lyudmila G; Hatfield, M Jason; Edwards, Carol C; Hyatt, Janice L; Potter, Philip M

    2013-03-25

    Carboxylesterases (CEs) are ubiquitously expressed proteins that are responsible for the detoxification of xenobiotics. They tend to be expressed in tissues likely to be exposed to such agents (e.g., lung and gut epithelia, liver) and can hydrolyze numerous agents, including many clinically used drugs. Due to the considerable structural similarity between cholinesterases (ChE) and CEs, we have assessed the ability of a series of ChE inhibitors to modulate the activity of the human liver (hCE1) and the human intestinal CE (hiCE) isoforms. We observed inhibition of hCE1 and hiCE by carbamate-containing small molecules, including those used for the treatment of Alzheimer's disease. For example, rivastigmine resulted in greater than 95% inhibition of hiCE that was irreversible under the conditions used. Hence, the administration of esterified drugs, in combination with these carbamates, may inadvertently result in decreased hydrolysis of the former, thereby limiting their efficacy. Therefore drug:drug interactions should be carefully evaluated in individuals receiving ChE inhibitors. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  8. Isthmin is a novel secreted angiogenesis inhibitor that inhibits tumour growth in mice.

    Science.gov (United States)

    Xiang, Wei; Ke, Zhiyuan; Zhang, Yong; Cheng, Grace Ho-Yuet; Irwan, Ishak Darryl; Sulochana, K N; Potturi, Padma; Wang, Zhengyuan; Yang, He; Wang, Jingyu; Zhuo, Lang; Kini, R Manjunatha; Ge, Ruowen

    2011-02-01

    Anti-angiogenesis represents a promising therapeutic strategy for the treatment of various malignancies. Isthmin (ISM) is a gene highly expressed in the isthmus of the midbrain-hindbrain organizer in Xenopus with no known functions. It encodes a secreted 60 kD protein containing a thrombospondin type 1 repeat domain in the central region and an adhesion-associated domain in MUC4 and other proteins (AMOP) domain at the C-terminal. In this work, we demonstrate that ISM is a novel angiogenesis inhibitor. Recombinant mouse ISM inhibited endothelial cell (EC) capillary network formation on Matrigel through its C-terminal AMOP domain. It also suppressed vascular endothelial growth factor (VEGF)-basic fibroblast growth factor (bFGF) induced in vivo angiogenesis in mouse. It mitigated VEGF-stimulated EC proliferation without affecting EC migration. Furthermore, ISM induced EC apoptosis in the presence of VEGF through a caspase-dependent pathway. ISM binds to αvβ(5) integrin on EC surface and supports EC adhesion. Overexpression of ISM significantly suppressed mouse B16 melanoma tumour growth through inhibition of tumour angiogenesis without affecting tumour cell proliferation. Knockdown of isthmin in zebrafish embryos using morpholino antisense oligonucleotides led to disorganized intersegmental vessels in the trunk. Our results demonstrate that ISM is a novel endogenous angiogenesis inhibitor with functions likely in physiological as well as pathological angiogenesis. © 2011 The Authors Journal of Cellular and Molecular Medicine © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.

  9. Inhibition of hydrate formation by kinetic inhibitors. Literature study; Inhibierung von Erdgashydraten durch kinetische Inhibitoren. Literaturstudie

    Energy Technology Data Exchange (ETDEWEB)

    Eberhardt, E.; Meyn, V.; Rahimian, I. [Institut fuer Erdoel- und Erdgasforschung, Clausthal-Zellerfeld (Germany)

    2000-04-01

    The aim of this study was to represent the state-of-the art of the inhibition of gas hydrates. Corresponding to recent publications the kinetic inhibition was considered in particular. Special inhibitors were validated using a set of criteria derived from different experimental test methods. Best results were obtained by the application of terpolymer VC-713 especially in relation to nucleation and crystal growth, followed by PVCap (polyvinylcaprolactame) and THI (threshold hydrate inhibitor), the chemical structure of which is derived from the antifreeze glycopeptids of antarcitc winter flounder. (orig.) [German] Die vorliegende Literaturstudie gibt den derzeitigen Stand der Kenntnis zur Inhibierung von Gashydraten wieder. Entsprechend der neueren Literatur wird insbesondere auf die kinetische Inhibierung eingegangen. Zur Beurteilung der verschiedenen Inhibitoren werden Bewertungskriterien zur Validierung der mit unterschiedlichen Untersuchungsmethoden erzielten experimentellen Ergebnisse angegeben. Anhand dieser Vorgehensweise zeigte sich, dass mit dem Terpolymer VC-713 die besten Ergebnisse, insbesondere im Hinblick auf Keimbildung und Wachstum, erzielt werden konnten. Sehr gute Ergebnisse wurden auch mit dem Polyvinylcaprolactam (PVCap) und den aus den Antigefrierpeptiden der antarktischen Winterflunder abgeleiteten Threshold Hydrate Inhibitoren (THI) erhalten. (orig.)

  10. A novel HDAC inhibitor, CG200745, inhibits pancreatic cancer cell growth and overcomes gemcitabine resistance.

    Science.gov (United States)

    Lee, Hee Seung; Park, Soo Been; Kim, Sun A; Kwon, Sool Ki; Cha, Hyunju; Lee, Do Young; Ro, Seonggu; Cho, Joong Myung; Song, Si Young

    2017-01-30

    Pancreatic cancer is predominantly lethal, and is primarily treated using gemcitabine, with increasing resistance. Therefore, novel agents that increase tumor sensitivity to gemcitabine are needed. Histone deacetylase (HDAC) inhibitors are emerging therapeutic agents, since HDAC plays an important role in cancer initiation and progression. We evaluated the antitumor effect of a novel HDAC inhibitor, CG200745, combined with gemcitabine/erlotinib on pancreatic cancer cells and gemcitabine-resistant pancreatic cancer cells. Three pancreatic cancer-cell lines were used to evaluate the antitumor effect of CG200745 combined with gemcitabine/erlotinib. CG200745 induced the expression of apoptotic proteins (PARP and caspase-3) and increased the levels of acetylated histone H3. CG200745 with gemcitabine/erlotinib showed significant growth inhibition and synergistic antitumor effects in vitro. In vivo, gemcitabine/erlotinib and CG200745 reduced tumor size up to 50%. CG200745 enhanced the sensitivity of gemcitabine-resistant pancreatic cancer cells to gemcitabine, and decreased the level of ATP-binding cassette-transporter genes, especially multidrug resistance protein 3 (MRP3) and MRP4. The novel HDAC inhibitor, CG200745, with gemcitabine/erlotinib had a synergistic anti-tumor effect on pancreatic cancer cells. CG200745 significantly improved pancreatic cancer sensitivity to gemcitabine, with a prominent antitumor effect on gemcitabine-resistant pancreatic cancer cells. Therefore, improved clinical outcome is expected in the future.

  11. Inhibition of xyloglucanase from an alkalothermophilic Thermomonospora sp. by a peptidic aspartic protease inhibitor from Penicillium sp. VM24.

    Science.gov (United States)

    Menon, Vishnu; Rao, Mala

    2012-11-01

    A bifunctional inhibitor from Penicillium sp VM24 causing inactivation of xyloglucanase from Thermomonospora sp and an aspartic protease from Aspergillus saitoi was identified. Steady state kinetics studies of xyloglucanase and the inhibitor revealed an irreversible, non-competitive, two-step inhibition mechanism with IC(50) and K(i) values of 780 and 500nM respectively. The interaction of o-phthalaldehyde (OPTA)-labeled xyloglucanase with the inhibitor revealed that the inhibitor binds to the active site of the enzyme. Far- and near-UV spectrophotometric analysis suggests that the conformational changes induced in xyloglucanase by the inhibitor may be due to irreversible denaturation of enzyme. The bifunctional inhibitor may have potential as a biocontrol agent for the protection of plants against phytopathogenic fungi. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Mechanisms of mono- and poly-ubiquitination: Ubiquitination specificity depends on compatibility between the E2 catalytic core and amino acid residues proximal to the lysine

    Directory of Open Access Journals (Sweden)

    Sadowski Martin

    2010-08-01

    Full Text Available Abstract Ubiquitination involves the attachment of ubiquitin to lysine residues on substrate proteins or itself, which can result in protein monoubiquitination or polyubiquitination. Ubiquitin attachment to different lysine residues can generate diverse substrate-ubiquitin structures, targeting proteins to different fates. The mechanisms of lysine selection are not well understood. Ubiquitination by the largest group of E3 ligases, the RING-family E3 s, is catalyzed through co-operation between the non-catalytic ubiquitin-ligase (E3 and the ubiquitin-conjugating enzyme (E2, where the RING E3 binds the substrate and the E2 catalyzes ubiquitin transfer. Previous studies suggest that ubiquitination sites are selected by E3-mediated positioning of the lysine toward the E2 active site. Ultimately, at a catalytic level, ubiquitination of lysine residues within the substrate or ubiquitin occurs by nucleophilic attack of the lysine residue on the thioester bond linking the E2 catalytic cysteine to ubiquitin. One of the best studied RING E3/E2 complexes is the Skp1/Cul1/F box protein complex, SCFCdc4, and its cognate E2, Cdc34, which target the CDK inhibitor Sic1 for K48-linked polyubiquitination, leading to its proteasomal degradation. Our recent studies of this model system demonstrated that residues surrounding Sic1 lysines or lysine 48 in ubiquitin are critical for ubiquitination. This sequence-dependence is linked to evolutionarily conserved key residues in the catalytic region of Cdc34 and can determine if Sic1 is mono- or poly-ubiquitinated. Our studies indicate that amino acid determinants in the Cdc34 catalytic region and their compatibility to those surrounding acceptor lysine residues play important roles in lysine selection. This may represent a general mechanism in directing the mode of ubiquitination in E2 s.

  13. Small Quaternary Inhibitors K298 and K524: Cholinesterases Inhibition, Absorption, Brain Distribution, and Toxicity.

    Science.gov (United States)

    Karasova, Jana Zdarova; Hroch, Milos; Musilek, Kamil; Kuca, Kamil

    2016-02-01

    Inhibitors of acetylcholinesterase (AChE) may be used in the treatment of various cholinergic deficits, among them being myasthenia gravis (MG). This paper describes the first in vivo data for promising small quaternary inhibitors (K298 and K524): acute toxicity study, cholinesterase inhibition, absorption, and blood-brain barrier penetration. The newly prepared AChE inhibitors (bis-quinolinium and quinolinium compounds) possess a positive charge in the molecule which ensures that anti-AChE action is restricted to peripheral effect. HPLC-MS was used for determination of real plasma and brain concentration in the pharmacokinetic part of the study, and standard non-compartmental analysis was performed. The maximum plasma concentrations were attained at 30 min (K298; 928.76 ± 115.20 ng/ml) and 39 min (K524; 812.40 ± 54.96 ng/ml) after i.m. Both compounds are in fact able to target the central nervous system. It seems that the difference in the CNS distribution profile depends on an active efflux system. The K524 brain concentration was actively decreased to below an effective level; in contrast, K298 progressively accumulated in brain tissue. Peripheral AChE inhibitors are still first-line treatment in the mild forms of MG. Commonly prescribed carbamates have many severe side effects related to AChE carbamylation. The search for new treatment strategies is still important. Unlike carbamates, these new compounds target AChE via apparent π-π or π-cationic interaction aside at the AChE catalytic site.

  14. Gimeracil, an inhibitor of dihydropyrimidine dehydrogenase, inhibits the early step in homologous recombination

    International Nuclear Information System (INIS)

    Sakata, Koh-ichi; Someya, Masanori; Matsumoto, Yoshihisa; Takagi, Masaru; Hareyama, Masato; Tauchi, Hiroshi; Kai, Masahiro; Toyota, Minoru; Fukushima, Masakazu

    2011-01-01

    Gimeracil (5-chloro-2, 4-dihydroxypyridine) is an inhibitor of dihydropyrimidine dehydrogenase (DPYD), which degrades pyrimidine including 5-fluorouracil in the blood. Gimeracil was originally added to an oral fluoropyrimidine derivative S-1 to yield prolonged 5-fluorouracil concentrations in serum and tumor tissues. We have already reported that gimeracil had radiosensitizing effects by partially inhibiting homologous recombination (HR) in the repair of DNA double strand breaks. We investigated the mechanisms of gimeracil radiosensitization. Comet assay and radiation-induced focus formation of various kinds of proteins involved in HR was carried out. Small interfering RNA (siRNA) for DPYD were transfected to HeLa cells to investigate the target protein for radiosensitization with gimeracil. SCneo assay was carried out to examine whether DPYD depletion by siRNA inhibited HR repair of DNA double strand breaks. Tail moments in neutral comet assay increased in gimeracil-treated cells. Gimeracil restrained the formation of foci of Rad51 and replication protein A (RPA), whereas it increased the number of foci of Nbs1, Mre11, Rad50, and FancD2. When HeLa cells were transfected with the DPYD siRNA before irradiation, the cells became more radiosensitive. The degree of radiosensitization by transfection of DPYD siRNA was similar to that of gimeracil. Gimeracil did not sensitize DPYD-depleted cells. Depletion of DPYD by siRNA significantly reduced the frequency of neopositive clones in SCneo assay. Gimeracil partially inhibits the early step in HR. It was found that DPYD is the target protein for radiosensitization by gimeracil. The inhibitors of DPYD, such as gimeracil, could enhance the efficacy of radiotherapy through partial suppression of HR-mediated DNA repair. (author)

  15. Discovery of Ubiquitin Deamidases in the Pathogenic Arsenal of Legionella pneumophila

    Directory of Open Access Journals (Sweden)

    Dylan Valleau

    2018-04-01

    Full Text Available Summary: Legionella pneumophila translocates the largest known arsenal of over 330 pathogenic factors, called “effectors,” into host cells during infection, enabling L. pneumophila to establish a replicative niche inside diverse amebas and human macrophages. Here, we reveal that the L. pneumophila effectors MavC (Lpg2147 and MvcA (Lpg2148 are structural homologs of cycle inhibiting factor (Cif effectors and that the adjacent gene, lpg2149, produces a protein that directly inhibits their activity. In contrast to canonical Cifs, both MavC and MvcA contain an insertion domain and deamidate the residue Gln40 of ubiquitin but not Gln40 of NEDD8. MavC and MvcA are functionally diverse, with only MavC interacting with the human E2-conjugating enzyme UBE2N (Ubc13. MavC deamidates the UBE2N∼Ub conjugate, disrupting Lys63 ubiquitination and dampening NF-κB signaling. Combined, our data reveal a molecular mechanism of host manipulation by pathogenic bacteria and highlight the complex regulatory mechanisms integral to L. pneumophila’s pathogenic strategy. : Legionella pneumophila, possessing the largest known arsenal of effectors, continues to reveal unique approaches to host cell control. Valleau et al. decrypt the functions of a trio of effectors, discovering a pair of ubiquitin-specific deamidases, their regulation by a neighboring dual-specificity protein inhibitor, and a mechanism of NF-κB suppression. Keywords: pathogen-host interaction, ubiquitination, Legionella, UBE2N/Ubc13, NF-κB signaling, Type IV secretion system, effectors, metaeffector, cycle inhibiting factor

  16. Ubiquitination dynamics in the early-branching eukaryote Giardia intestinalis

    Science.gov (United States)

    Niño, Carlos A; Chaparro, Jenny; Soffientini, Paolo; Polo, Simona; Wasserman, Moises

    2013-01-01

    Ubiquitination is a highly dynamic and versatile posttranslational modification that regulates protein function, stability, and interactions. To investigate the roles of ubiquitination in a primitive eukaryotic lineage, we utilized the early-branching eukaryote Giardia intestinalis. Using a combination of biochemical, immunofluorescence-based, and proteomics approaches, we assessed the ubiquitination status during the process of differentiation in Giardia. We observed that different types of ubiquitin modifications present specific cellular and temporal distribution throughout the Giardia life cycle from trophozoites to cyst maturation. Ubiquitin signal was detected in the wall of mature cysts, and enzymes implicated in cyst wall biogenesis were identified as substrates for ubiquitination. Interestingly, inhibition of proteasome activity did not affect trophozoite replication and differentiation, while it caused a decrease in cyst viability, arguing for proteasome involvement in cyst wall maturation. Using a proteomics approach, we identified around 200 high-confidence ubiquitinated candidates that vary their ubiquitination status during differentiation. Our results indicate that ubiquitination is critical for several cellular processes in this primitive eukaryote. PMID:23613346

  17. Inhibition of chlorine-induced lung injury by the type 4 phosphodiesterase inhibitor rolipram

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Weiyuan; Chen, Jing; Schlueter, Connie F. [Department of Environmental and Occupational Health Sciences, School of Public Health and Information Sciences, University of Louisville, Louisville, KY (United States); Rando, Roy J. [Department of Environmental Health Sciences, School of Public Health and Tropical Medicine, Tulane University Health Sciences Center, New Orleans, LA (United States); Pathak, Yashwant V. [College of Pharmacy, University of South Florida, Tampa, FL (United States); Hoyle, Gary W., E-mail: Gary.Hoyle@louisville.edu [Department of Environmental and Occupational Health Sciences, School of Public Health and Information Sciences, University of Louisville, Louisville, KY (United States)

    2012-09-01

    Chlorine is a highly toxic respiratory irritant that when inhaled causes epithelial cell injury, alveolar-capillary barrier disruption, airway hyperreactivity, inflammation, and pulmonary edema. Chlorine is considered a chemical threat agent, and its release through accidental or intentional means has the potential to result in mass casualties from acute lung injury. The type 4 phosphodiesterase inhibitor rolipram was investigated as a rescue treatment for chlorine-induced lung injury. Rolipram inhibits degradation of the intracellular signaling molecule cyclic AMP. Potential beneficial effects of increased cyclic AMP levels include inhibition of pulmonary edema, inflammation, and airway hyperreactivity. Mice were exposed to chlorine (whole body exposure, 228–270 ppm for 1 h) and were treated with rolipram by intraperitoneal, intranasal, or intramuscular (either aqueous or nanoemulsion formulation) delivery starting 1 h after exposure. Rolipram administered intraperitoneally or intranasally inhibited chlorine-induced pulmonary edema. Minor or no effects were observed on lavage fluid IgM (indicative of plasma protein leakage), KC (Cxcl1, neutrophil chemoattractant), and neutrophils. All routes of administration inhibited chlorine-induced airway hyperreactivity assessed 1 day after exposure. The results of the study suggest that rolipram may be an effective rescue treatment for chlorine-induced lung injury and that both systemic and targeted administration to the respiratory tract were effective routes of delivery. -- Highlights: ► Chlorine causes lung injury when inhaled and is considered a chemical threat agent. ► Rolipram inhibited chlorine-induced pulmonary edema and airway hyperreactivity. ► Post-exposure rolipram treatments by both systemic and local delivery were effective. ► Rolipram shows promise as a rescue treatment for chlorine-induced lung injury.

  18. Cellular Cholesterol Regulates Ubiquitination and Degradation of the Cholesterol Export Proteins ABCA1 and ABCG1*

    Science.gov (United States)

    Hsieh, Victar; Kim, Mi-Jurng; Gelissen, Ingrid C.; Brown, Andrew J.; Sandoval, Cecilia; Hallab, Jeannette C.; Kockx, Maaike; Traini, Mathew; Jessup, Wendy; Kritharides, Leonard

    2014-01-01

    The objective of this study was to examine the influence of cholesterol in post-translational control of ABCA1 and ABCG1 protein expression. Using CHO cell lines stably expressing human ABCA1 or ABCG1, we observed that the abundance of these proteins is increased by cell cholesterol loading. The response to increased cholesterol is rapid, is independent of transcription, and appears to be specific for these membrane proteins. The effect is mediated through cholesterol-dependent inhibition of transporter protein degradation. Cell cholesterol loading similarly regulates degradation of endogenously expressed ABCA1 and ABCG1 in human THP-1 macrophages. Turnover of ABCA1 and ABCG1 is strongly inhibited by proteasomal inhibitors and is unresponsive to inhibitors of lysosomal proteolysis. Furthermore, cell cholesterol loading inhibits ubiquitination of ABCA1 and ABCG1. Our findings provide evidence for a rapid, cholesterol-dependent, post-translational control of ABCA1 and ABCG1 protein levels, mediated through a specific and sterol-sensitive mechanism for suppression of transporter protein ubiquitination, which in turn decreases proteasomal degradation. This provides a mechanism for acute fine-tuning of cholesterol transporter activity in response to fluctuations in cell cholesterol levels, in addition to the longer term cholesterol-dependent transcriptional regulation of these genes. PMID:24500716

  19. Inhibition and reversal of nickel-induced transformation by the histone deacetylase inhibitor trichostatin A

    International Nuclear Information System (INIS)

    Zhang Qunwei; Salnikow, Konstantin; Kluz, Thomas; Chen, L.C.; Su, W.C.; Costa, Max

    2003-01-01

    The carcinogenic process initiated by nongenotoxic carcinogens involves modulation of gene expression. Nickel compounds have low mutagenic activity, but are highly carcinogenic. In vitro both mouse and human cells can be efficiently transformed by soluble and insoluble nickel compounds to anchorage-independent growth. Because previous studies have shown that carcinogenic nickel compounds silence genes by inhibiting histone acetylation and enhancing DNA methylation, we investigated the effect of enhancing histone acetylation on cell transformation. The exposure of nickel-transformed cells to the histone deacetylase inhibitor trichostatin A (TSA) resulted in the appearance of significant number of revertants measured by their inability to grow in soft agar. Using the Affymetrix GeneChip we found that the level of expression of a significant number of genes was changed (suppressed or upregulated) in nickel-transformed clones but returned to a normal level in revertants obtained following TSA treatment. Moreover, we found that treatment of cells with TSA inhibited the ability of nickel to transform mouse PW cells to anchorage-independent growth. Treatment with TSA also inhibited the ability of nickel to transform human HOS cells, although to a lesser extent. In contrast, treatment with TSA was not able to revert established cancer cell lines as readily as the nickel-transformed cells. These data indicated that modulation of gene expression is important for nickel-induced transformation

  20. Structural Basis for Specific Inhibition of tRNA Synthetase by an ATP Competitive Inhibitor.

    Science.gov (United States)

    Fang, Pengfei; Han, Hongyan; Wang, Jing; Chen, Kaige; Chen, Xin; Guo, Min

    2015-06-18

    Pharmaceutical inhibitors of aminoacyl-tRNA synthetases demand high species and family specificity. The antimalarial ATP-mimetic cladosporin selectively inhibits Plasmodium falciparum LysRS (PfLysRS). How the binding to a universal ATP site achieves the specificity is unknown. Here we report three crystal structures of cladosporin with human LysRS, PfLysRS, and a Pf-like human LysRS mutant. In all three structures, cladosporin occupies the class defining ATP-binding pocket, replacing the adenosine portion of ATP. Three residues holding the methyltetrahydropyran moiety of cladosporin are critical for the specificity of cladosporin against LysRS over other class II tRNA synthetase families. The species-exclusive inhibition of PfLysRS is linked to a structural divergence beyond the active site that mounts a lysine-specific stabilizing response to binding cladosporin. These analyses reveal that inherent divergence of tRNA synthetase structural assembly may allow for highly specific inhibition even through the otherwise universal substrate binding pocket and highlight the potential for structure-driven drug development. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Inhibition of plasminogen activator inhibitor-1 activity results in promotion of endogenous thrombolysis and inhibition of thrombus extension in models of experimental thrombosis

    NARCIS (Netherlands)

    Levi, M. [=Marcel M.; Biemond, B. J.; van Zonneveld, A. J.; ten Cate, J. W.; Pannekoek, H.

    1992-01-01

    We investigated the effect of inhibition of plasminogen activator inhibitor-1 (PAI-1) activity by a murine monoclonal anti-human PAI-1 antibody (MAI-12) on in vitro thrombolysis and on in vivo thrombolysis and thrombus extension in an experimental animal model for thrombosis. Thrombolysis, mediated

  2. MK-2206, an AKT Inhibitor, Promotes Caspase-Independent Cell Death and Inhibits Leiomyoma Growth

    Science.gov (United States)

    Sefton, Elizabeth C.; Qiang, Wenan; Serna, Vanida; Kurita, Takeshi; Wei, Jian-Jun; Chakravarti, Debabrata

    2013-01-01

    Uterine leiomyomas (ULs), benign tumors of the myometrium, are the number one indication for hysterectomies in the United States due to a lack of an effective alternative therapy. ULs show activation of the pro-survival AKT pathway compared with normal myometrium; however, substantial data directly linking AKT to UL cell survival are lacking. We hypothesized that AKT promotes UL cell survival and that it is a viable target for inhibiting UL growth. We used the investigational AKT inhibitor MK-2206, currently in phase II trials, on cultured primary human UL and myometrial cells, immortalized leiomyoma cells, and in leiomyoma grafts grown under the kidney capsule in mice. MK-2206 inhibited AKT and PRAS40 phosphorylation but did not regulate serum- and glucocorticoid-induced kinase and ERK1/2, demonstrating its specificity for AKT. MK-2206 reduced UL cell viability and decreased UL tumor volumes. UL cells exhibited disruption of mitochondrial structures and underwent cell death that was independent of caspases. Additionally, mammalian target of rapamycin and p70S6K phosphorylation were reduced, indicating that mammalian target of rapamycin complex 1 signaling was compromised by AKT inhibition in UL cells. MK-2206 also induced autophagy in UL cells. Pretreatment of primary UL cells with 3-methyladenine enhanced MK-2206-mediated UL cell death, whereas knockdown of ATG5 and/or ATG7 did not significantly influence UL cell viability in the presence of MK-2206. Our data provide molecular evidence for the involvement of AKT in UL cell survival and suggest that AKT inhibition by MK-2206 may be a viable option to consider for the treatment of ULs. PMID:24002033

  3. Kinetic analysis of the inhibition of matrix metalloproteinases: lessons from the study of tissue inhibitors of metalloproteinases.

    Science.gov (United States)

    Willenbrock, Frances; Thomas, Daniel A; Amour, Augustin

    2010-01-01

    Tissue inhibitors of metalloproteinases (TIMPs) are a group of highly potent inhibitors of matrix metalloproteinases (MMPs) and disintegrin metalloproteinases (ADAMs). The high affinity and "tight-binding" nature of the inhibition of MMPs or ADAMs by TIMPs presents challenges for the determination of both equilibrium and dissociation rate constants of these inhibitory events. Methodologies that enable some of these challenges to be overcome are described in this chapter and represent valuable lessons for the in vitro assessment of MMP or ADAM inhibitors within a drug discovery context.

  4. Oral administration of FAK inhibitor TAE226 inhibits the progression of peritoneal dissemination of colorectal cancer

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Hui-fang [Department of Gastroenterological Surgery, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikatacho, Kita-ku, Okayama 700-8558 (Japan); Takaoka, Munenori [Department of General Surgery, Kawasaki Medical School, 2-1-80 Nakasange, Kita-ku, Okayama 700-8505 (Japan); Bao, Xiao-hong [Department of Gastroenterological Surgery, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikatacho, Kita-ku, Okayama 700-8558 (Japan); Wang, Zhi-gang [College of Life Science, Inner Mongolia University, The Key Laboratory of Mammal Reproductive Biology and Biotechnology, Ministry of Education, Hohhot 010021 (China); Tomono, Yasuko [Division of Molecular and Cell Biology, Shigei Medical Research Institute, 2117 Yamada, Okayama 700-0202 (Japan); Sakurama, Kazufumi; Ohara, Toshiaki [Department of Gastroenterological Surgery, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikatacho, Kita-ku, Okayama 700-8558 (Japan); Fukazawa, Takuya; Yamatsuji, Tomoki [Department of General Surgery, Kawasaki Medical School, 2-1-80 Nakasange, Kita-ku, Okayama 700-8505 (Japan); Fujiwara, Toshiyoshi [Department of Gastroenterological Surgery, Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama University, 2-5-1 Shikatacho, Kita-ku, Okayama 700-8558 (Japan); Naomoto, Yoshio, E-mail: ynaomoto@med.kawasaki-m.ac.jp [Department of General Surgery, Kawasaki Medical School, 2-1-80 Nakasange, Kita-ku, Okayama 700-8505 (Japan)

    2012-07-13

    Highlights: Black-Right-Pointing-Pointer A novel FAK inhibitor TAE226 suppressed FAK activity in HCT116 colon cancer cells. Black-Right-Pointing-Pointer TAE226 suppressed proliferation and migration, with a modest effect on adhesion. Black-Right-Pointing-Pointer Silencing of FAK by siRNA made no obvious difference on cancer cell attachment. Black-Right-Pointing-Pointer TAE226 treatment suppressed the progression of peritoneal dissemination. Black-Right-Pointing-Pointer Oral administration of TAE226 prolonged the survival of tumor-bearing mice. -- Abstract: Peritoneal dissemination is one of the most terrible types of colorectal cancer progression. Focal adhesion kinase (FAK) plays a crucial role in the biological processes of cancer, such as cell attachment, migration, proliferation and survival, all of which are essential for the progression of peritoneal dissemination. Since we and other groups have reported that the inhibition of FAK activity exhibited a potent anticancer effect in several cancer models, we hypothesized that TAE226, a novel ATP-competitive tyrosine kinase inhibitor designed to target FAK, can prevent the occurrence and progression of peritoneal dissemination. In vitro, TAE226 greatly inhibited the proliferation and migration of HCT116 colon cancer cells, while their adhesion on the matrix surface was minimally inhibited when FAK activity and expression was suppressed by TAE226 and siRNA. In vivo, when HCT116 cells were intraperitoneally inoculated in mice, the cells could attach to the peritoneum and begin to grow within 24 h regardless of the pretreatment of cells with TAE226 or FAK-siRNA, suggesting that FAK is not essential, at least for the initial integrin-matrix contact. Interestingly, the treatment of mice before and after inoculation significantly suppressed cell attachment to the peritoneum. Furthermore, oral administration of TAE226 greatly reduced the size of disseminated tumors and prolonged survival in tumor-bearing mice. Taken

  5. Oral administration of FAK inhibitor TAE226 inhibits the progression of peritoneal dissemination of colorectal cancer

    International Nuclear Information System (INIS)

    Hao, Hui-fang; Takaoka, Munenori; Bao, Xiao-hong; Wang, Zhi-gang; Tomono, Yasuko; Sakurama, Kazufumi; Ohara, Toshiaki; Fukazawa, Takuya; Yamatsuji, Tomoki; Fujiwara, Toshiyoshi; Naomoto, Yoshio

    2012-01-01

    Highlights: ► A novel FAK inhibitor TAE226 suppressed FAK activity in HCT116 colon cancer cells. ► TAE226 suppressed proliferation and migration, with a modest effect on adhesion. ► Silencing of FAK by siRNA made no obvious difference on cancer cell attachment. ► TAE226 treatment suppressed the progression of peritoneal dissemination. ► Oral administration of TAE226 prolonged the survival of tumor-bearing mice. -- Abstract: Peritoneal dissemination is one of the most terrible types of colorectal cancer progression. Focal adhesion kinase (FAK) plays a crucial role in the biological processes of cancer, such as cell attachment, migration, proliferation and survival, all of which are essential for the progression of peritoneal dissemination. Since we and other groups have reported that the inhibition of FAK activity exhibited a potent anticancer effect in several cancer models, we hypothesized that TAE226, a novel ATP-competitive tyrosine kinase inhibitor designed to target FAK, can prevent the occurrence and progression of peritoneal dissemination. In vitro, TAE226 greatly inhibited the proliferation and migration of HCT116 colon cancer cells, while their adhesion on the matrix surface was minimally inhibited when FAK activity and expression was suppressed by TAE226 and siRNA. In vivo, when HCT116 cells were intraperitoneally inoculated in mice, the cells could attach to the peritoneum and begin to grow within 24 h regardless of the pretreatment of cells with TAE226 or FAK-siRNA, suggesting that FAK is not essential, at least for the initial integrin-matrix contact. Interestingly, the treatment of mice before and after inoculation significantly suppressed cell attachment to the peritoneum. Furthermore, oral administration of TAE226 greatly reduced the size of disseminated tumors and prolonged survival in tumor-bearing mice. Taken together, a possible strategy for inhibiting peritoneal dissemination by targeting FAK with TAE226 appears to be applicable

  6. Second Generation Grp94-Selective Inhibitors Provide Opportunities for the Inhibition of Metastatic Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Crowley, Vincent M. [Department of Medicinal Chemistry, The University of Kansas, 1251 Wescoe Hall Dr. Malott 4070 Lawrence KS 66045 USA; Huard, Dustin J. E. [School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta GA 30332 USA; Lieberman, Raquel L. [School of Chemistry & Biochemistry, Georgia Institute of Technology, Atlanta GA 30332 USA; Blagg, Brian S. J. [Warren Family Research Center for Drug Discovery and Development, and Department of Chemistry & Biochemistry, University of Notre Dame, 305 McCourtney Hall Notre Dame IN 46556 USA

    2017-09-27

    Glucose regulated protein 94 (Grp94) is the endoplasmic reticulum (ER) resident isoform of the 90 kDa heat shock protein (Hsp90) family and its inhibition represents a promising therapeutic target for the treatment of many diseases. Modification of the first generation cis-amide bioisostere imidazole to alter the angle between the resorcinol ring and the benzyl side chain via cis-amide replacements produced compounds with improved Grp94 affinity and selectivity. Structure–activity relationship studies led to the discovery of compound 30, which exhibits 540 nm affinity and 73-fold selectivity towards Grp94. Grp94 is responsible for the maturation and trafficking of proteins associated with cell signaling and motility, including select integrins. The Grp94-selective inhibitor 30 was shown to exhibit potent anti-migratory effects against multiple aggressive and metastatic cancers.

  7. Synergistic Inhibition of Carbon Steel Corrosion by Inhibitor-Blends in Chloride-Containing Simulated Cooling Water

    Energy Technology Data Exchange (ETDEWEB)

    Shaban, Abdul; Felhosi, Ilona [Hungarian Academy of Sciences, Budapest (Hungary); Vastag, Gyongyi [University of Novi Sad, Novi Sad (Serbia)

    2017-06-15

    The objective of this work was to develop efficient synergistic inhibitor combinations comprising sodium nitrite (NaNO{sub 2}) and an inhibitor-blend code named (SN-50), keeping in view of their application in industrial cooling water systems. The electrochemical characteristics of the carbon steel working electrode in simulated cooling water (SCW), without and with the addition of different combinations of the inhibitors, were investigated using electrochemical impedance spectroscopy (EIS), open circuit potential (OCP). The electrode surface changes were followed by visual characterization methods. It was demonstrated in this study that all the combinations of the inhibitors exhibited synergistic benefit and higher inhibition efficiencies than did either of the individual inhibitors. The addition of SN-50 inhibitor to the SCW shifted the OCP to more anodic values and increased the polarization resistance (R{sub p}) values of carbon steel at all applied concentrations. The higher the applied sodium nitrite concentration (in the protection concentration range), the higher the obtained R{sub p} values and the inhibition efficiency improved by increasing the inhibitor concentration.

  8. Soybean-derived Bowman-Birk inhibitor inhibits neurotoxicity of LPS-activated macrophages

    Directory of Open Access Journals (Sweden)

    Persidsky Yuri

    2011-02-01

    Full Text Available Abstract Background Lipopolysaccharide (LPS, the major component of the outer membrane of gram-negative bacteria, can activate immune cells including macrophages. Activation of macrophages in the central nervous system (CNS contributes to neuronal injury. Bowman-Birk inhibitor (BBI, a soybean-derived protease inhibitor, has anti-inflammatory properties. In this study, we examined whether BBI has the ability to inhibit LPS-mediated macrophage activation, reducing the release of pro-inflammatory cytokines and subsequent neurotoxicity in primary cortical neural cultures. Methods Mixed cortical neural cultures from rat were used as target cells for testing neurotoxicity induced by LPS-treated macrophage supernatant. Neuronal survival was measured using a cell-based ELISA method for expression of the neuronal marker MAP-2. Intracellular reactive oxygen species (ROS production in macrophages was measured via 2', 7'-dichlorofluorescin diacetate (DCFH2DA oxidation. Cytokine expression was determined by quantitative real-time PCR. Results LPS treatment of macrophages induced expression of proinflammatory cytokines (IL-1β, IL-6 and TNF-α and of ROS. In contrast, BBI pretreatment (1-100 μg/ml of macrophages significantly inhibited LPS-mediated induction of these cytokines and ROS. Further, supernatant from BBI-pretreated and LPS-activated macrophage cultures was found to be less cytotoxic to neurons than that from non-BBI-pretreated and LPS-activated macrophage cultures. BBI, when directly added to the neuronal cultures (1-100 μg/ml, had no protective effect on neurons with or without LPS-activated macrophage supernatant treatment. In addition, BBI (100 μg/ml had no effect on N-methyl-D-aspartic acid (NMDA-mediated neurotoxicity. Conclusions These findings demonstrate that BBI, through its anti-inflammatory properties, protects neurons from neurotoxicity mediated by activated macrophages.

  9. Anomalous inhibition of c-Met by the kinesin inhibitor aurintricarboxylic acid.

    Science.gov (United States)

    Milanovic, Mina; Radtke, Simone; Peel, Nick; Howell, Michael; Carrière, Virginie; Joffre, Carine; Kermorgant, Stéphanie; Parker, Peter J

    2012-03-01

    c-Met [the hepatocyte growth factor (HGF) receptor] is a receptor tyrosine kinase playing a role in various biological events. Overexpression of the receptor has been observed in a number of cancers, correlating with increased metastatic tendency and poor prognosis. Additionally, activating mutations in c-Met kinase domain have been reported in a subset of familial cancers causing resistance to treatment. Receptor trafficking, relying on the integrity of the microtubule network, plays an important role in activation of downstream targets and initiation of signalling events. Aurintricarboxylic acid (ATA) is a triphenylmethane derivative that has been reported to inhibit microtubule motor proteins kinesins. Additional reported properties of this inhibitor include inhibition of protein tyrosine phosphatases, nucleases and members of the Jak family. Here we demonstrate that ATA prevents HGF-induced c-Met phosphorylation, internalisation, subsequent receptor trafficking and degradation. In addition, ATA prevented HGF-induced downstream signalling which also affected cellular function, as assayed by collective cell migration of A549 cells. Surprisingly, the inhibitory effect of ATA on HGF-induced phosphorylation and signalling in vivo was associated with an increase in basal c-Met kinase activity in vitro. It is concluded that the inhibitory effects of ATA on c-Met in vivo is an allosteric effect mediated through the kinase domain of the receptor. As the currently tested adenosine triphosphate competitive tyrosine kinase inhibitors (TKIs) may lead to tumor resistance (McDermott U, et al., Cancer Res 2010;70:1625-34), our findings suggest that novel anti-c-Met therapies could be developed in the future for cancer treatment. Copyright © 2011 UICC.

  10. Glycolytic inhibitors 2-deoxyglucose and 3-bromopyruvate synergize with photodynamic therapy respectively to inhibit cell migration.

    Science.gov (United States)

    Feng, Xiaolan; Wang, Pan; Liu, Quanhong; Zhang, Ting; Mai, Bingjie; Wang, Xiaobing

    2015-06-01

    Most cancer cells have the specially increased glycolytic phenotype, which makes this pathway become an attractive therapeutic target. Although glycolytic inhibitor 2-deoxyglucose (2-DG) has been demonstrated to potentiate the cytotoxicity of photodynamic therapy (PDT), the impacts on cell migration after the combined treatment has never been reported yet. The present study aimed to analyze the influence of glycolytic inhibitors 2-DG and 3-bromopyruvate (3-BP) combined with Ce6-PDT on cell motility of Triple Negative Breast Cancer MDA-MB-231 cells. As determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltertrazolium-bromide-Tetraz-olium (MTT) assay, more decreased cell viability was observed in 2-DG + PDT and 3-BP + PDT groups when compared with either monotherapy. Under optimal conditions, synergistic potentiation on cell membrane destruction and the decline of cell adhesion and cells migratory ability were observed in both 2-DG + PDT and 3-BP + PDT by electron microscope observation (SEM), wound healing and trans-well assays. Besides, serious microfilament network collapses as well as impairment of matrix metalloproteinases-9 (MMP-9) were notably improved after the combined treatments by immunofluorescent staining. These results suggest that 2-DG and 3-BP can both significantly potentiated Ce6-PDT efficacy of cell migration inhibition.

  11. Allosteric Inhibition of SHP2: Identification of a Potent, Selective, and Orally Efficacious Phosphatase Inhibitor

    Energy Technology Data Exchange (ETDEWEB)

    Fortanet, Jorge Garcia; Chen, Christine Hiu-Tung; Chen, Ying-Nan P.; Chen, Zhouliang; Deng, Zhan; Firestone, Brant; Fekkes, Peter; Fodor, Michelle; Fortin, Pascal D.; Fridrich, Cary; Grunenfelder, Denise; Ho, Samuel; Kang, Zhao B.; Karki, Rajesh; Kato, Mitsunori; Keen, Nick; LaBonte, Laura R.; Larrow, Jay; Lenoir, Francois; Liu, Gang; Liu, Shumei; Lombardo, Franco; Majumdar, Dyuti; Meyer, Matthew J.; Palermo, Mark; Perez, Lawrence; Pu, Minying; Ramsey, Timothy; Sellers, William R.; Shultz, Michael D.; Stams, Travis; Towler, Christopher; Wang, Ping; Williams, Sarah L.; Zhang, Ji-Hu; LaMarche, Matthew J. (Novartis)

    2016-09-08

    SHP2 is a nonreceptor protein tyrosine phosphatase (PTP) encoded by the PTPN11 gene involved in cell growth and differentiation via the MAPK signaling pathway. SHP2 also purportedly plays an important role in the programmed cell death pathway (PD-1/PD-L1). Because it is an oncoprotein associated with multiple cancer-related diseases, as well as a potential immunomodulator, controlling SHP2 activity is of significant therapeutic interest. Recently in our laboratories, a small molecule inhibitor of SHP2 was identified as an allosteric modulator that stabilizes the autoinhibited conformation of SHP2. A high throughput screen was performed to identify progressable chemical matter, and X-ray crystallography revealed the location of binding in a previously undisclosed allosteric binding pocket. Structure-based drug design was employed to optimize for SHP2 inhibition, and several new protein–ligand interactions were characterized. These studies culminated in the discovery of 6-(4-amino-4-methylpiperidin-1-yl)-3-(2,3-dichlorophenyl)pyrazin-2-amine (SHP099, 1), a potent, selective, orally bioavailable, and efficacious SHP2 inhibitor.

  12. Farnesyltransferase inhibitor tipifarnib (R115777) preferentially inhibits in vitro autonomous erythropoiesis of polycythemia vera patient cells.

    Science.gov (United States)

    Larghero, Jérôme; Gervais, Nathalie; Cassinat, Bruno; Rain, Jean-Didier; Schlageter, Marie-Hélène; Padua, Rose Ann; Chomienne, Christine; Rousselot, Philippe

    2005-05-01

    Polycythemia vera (PV) is an acquired myeloproliferative disorder with primary expansion of the red cell mass leading to an increased risk of thrombosis and less frequently to myelofibrosis and secondary acute leukemia. Standard therapies include cytoreduction with either phlebotomy or chemotherapeutic agents and antithrombotic drugs. Because long-term exposure to cytotoxic chemotherapy may increase the risk of acute transformation, new therapeutic options are needed. Tipifarnib is a nonpeptidomimetic inhibitor of farnesyl transferase that was developed as a potential inhibitor of RAS signaling. In the present study we report that tipifarnib used at pharmacologically achievable concentrations strongly inhibits the erythroid burst-forming unit (BFU-E) autonomous growth that characterizes patients with PV. Moreover, at low tipifarnib concentrations (0.15 muM), the inhibitory effect was preferentially observed in PV BFU-E progenitors and not in normal BFU-E progenitors and was not rescued by erythropoietin (EPO). Thus tipifarnib may specifically target PV stem cells and may be of clinical interest in the treatment of patients with PV.

  13. mTOR inhibitors alone and in combination with JAK2 inhibitors effectively inhibit cells of myeloproliferative neoplasms.

    Directory of Open Access Journals (Sweden)

    Costanza Bogani

    Full Text Available BACKGROUND: Dysregulated signaling of the JAK/STAT pathway is a common feature of chronic myeloproliferative neoplasms (MPN, usually associated with JAK2V617F mutation. Recent clinical trials with JAK2 inhibitors showed significant improvements in splenomegaly and constitutional symptoms in patients with myelofibrosis but meaningful molecular responses were not documented. Accordingly, there remains a need for exploring new treatment strategies of MPN. A potential additional target for treatment is represented by the PI3K/AKT/mammalian target of rapamycin (mTOR pathway that has been found constitutively activated in MPN cells; proof-of-evidence of efficacy of the mTOR inhibitor RAD001 has been obtained recently in a Phase I/II trial in patients with myelofibrosis. The aim of the study was to characterize the effects in vitro of mTOR inhibitors, used alone and in combination with JAK2 inhibitors, against MPN cells. FINDINGS: Mouse and human JAK2V617F mutated cell lines and primary hematopoietic progenitors from MPN patients were challenged with an allosteric (RAD001 and an ATP-competitive (PP242 mTOR inhibitor and two JAK2 inhibitors (AZD1480 and ruxolitinib. mTOR inhibitors effectively reduced proliferation and colony formation of cell lines through a slowed cell division mediated by changes in cell cycle transition to the S-phase. mTOR inhibitors also impaired the proliferation and prevented colony formation from MPN hematopoietic progenitors at doses significantly lower than healthy controls. JAK2 inhibitors produced similar antiproliferative effects in MPN cell lines and primary cells but were more potent inducers of apoptosis, as also supported by differential effects on cyclinD1, PIM1 and BcLxL expression levels. Co-treatment of mTOR inhibitor with JAK2 inhibitor resulted in synergistic activity against the proliferation of JAK2V617F mutated cell lines and significantly reduced erythropoietin-independent colony growth in patients with

  14. Concurrent Autophagy Inhibition Overcomes the Resistance of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in Human Bladder Cancer Cells.

    Science.gov (United States)

    Kang, Minyong; Lee, Kyoung-Hwa; Lee, Hye Sun; Jeong, Chang Wook; Kwak, Cheol; Kim, Hyeon Hoe; Ku, Ja Hyeon

    2017-02-04

    Despite the potential therapeutic efficacy of epithelial growth factor receptor (EGFR) inhibitors in the treatment of advanced stage bladder cancer, there currently is no clear evidence to support this hypothesis. In this study, we investigate whether the concurrent treatment of autophagy-blocking agents with EGFR inhibitors exerts synergistic anti-cancer effects in T24 and J82 human bladder cancer cells. Lapatinib and gefitinib were used as EGFR inhibitors, and bafilomycin A1 (BFA1), chloroquine (CQ) and 3-methyladenine (3-MA) were used as the pharmacologic inhibitors of autophagy activities. To assess the proliferative and self-renewal capabilities, the Cell Counting Kit-8 (CCK-8) assay and a clonogenic assay were performed, respectively. To examine apoptotic cell death, flow cytometry using annexin-V/propidium iodide (PI) was used. To measure the autophagy activities, the expression levels of LC3I and II was determined by Western blot analysis. To validate the synergistic effects of autophagy inhibition with EGFR inhibitors, we specifically blocked key autophagy regulatory gene ATG12 by transfection of small interference RNA and examined the phenotypic changes. Of note, lapatinib and gefitinib triggered autophagy activities in T24 and J82 human bladder cancer cells, as indicated by upregulation of LC3II. More importantly, inhibiting autophagy activities with pharmacologic inhibitors (BFA1, CQ or 3-MA) remarkably reduced the cell viabilities and clonal proliferation of T24 and J82 cells, compared to those treated with either of the agents alone. We also obtained similar results of the enhanced anti-cancer effects of EGFR inhibitors by suppressing the expression of ATG12. Notably, the apoptotic assay showed that synergistic anti-cancer effects were induced via the increase of apoptotic cell death. In summary, concomitant inhibition of autophagy activities potentiated the anti-cancer effects of EGFR inhibitors in human bladder cancer cells, indicating a novel

  15. Concurrent Autophagy Inhibition Overcomes the Resistance of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitors in Human Bladder Cancer Cells

    Directory of Open Access Journals (Sweden)

    Minyong Kang

    2017-02-01

    Full Text Available Despite the potential therapeutic efficacy of epithelial growth factor receptor (EGFR inhibitors in the treatment of advanced stage bladder cancer, there currently is no clear evidence to support this hypothesis. In this study, we investigate whether the concurrent treatment of autophagy-blocking agents with EGFR inhibitors exerts synergistic anti-cancer effects in T24 and J82 human bladder cancer cells. Lapatinib and gefitinib were used as EGFR inhibitors, and bafilomycin A1 (BFA1, chloroquine (CQ and 3-methyladenine (3-MA were used as the pharmacologic inhibitors of autophagy activities. To assess the proliferative and self-renewal capabilities, the Cell Counting Kit-8 (CCK-8 assay and a clonogenic assay were performed, respectively. To examine apoptotic cell death, flow cytometry using annexin-V/propidium iodide (PI was used. To measure the autophagy activities, the expression levels of LC3I and II was determined by Western blot analysis. To validate the synergistic effects of autophagy inhibition with EGFR inhibitors, we specifically blocked key autophagy regulatory gene ATG12 by transfection of small interference RNA and examined the phenotypic changes. Of note, lapatinib and gefitinib triggered autophagy activities in T24 and J82 human bladder cancer cells, as indicated by upregulation of LC3II. More importantly, inhibiting autophagy activities with pharmacologic inhibitors (BFA1, CQ or 3-MA remarkably reduced the cell viabilities and clonal proliferation of T24 and J82 cells, compared to those treated with either of the agents alone. We also obtained similar results of the enhanced anti-cancer effects of EGFR inhibitors by suppressing the expression of ATG12. Notably, the apoptotic assay showed that synergistic anti-cancer effects were induced via the increase of apoptotic cell death. In summary, concomitant inhibition of autophagy activities potentiated the anti-cancer effects of EGFR inhibitors in human bladder cancer cells, indicating

  16. ROS inhibitor N-acetyl-L-cysteine antagonizes the activity of proteasome inhibitors.

    Science.gov (United States)

    Halasi, Marianna; Wang, Ming; Chavan, Tanmay S; Gaponenko, Vadim; Hay, Nissim; Gartel, Andrei L

    2013-09-01

    NAC (N-acetyl-L-cysteine) is commonly used to identify and test ROS (reactive oxygen species) inducers, and to inhibit ROS. In the present study, we identified inhibition of proteasome inhibitors as a novel activity of NAC. Both NAC and catalase, another known scavenger of ROS, similarly inhibited ROS levels and apoptosis associated with H₂O₂. However, only NAC, and not catalase or another ROS scavenger Trolox, was able to prevent effects linked to proteasome inhibition, such as protein stabilization, apoptosis and accumulation of ubiquitin conjugates. These observations suggest that NAC has a dual activity as an inhibitor of ROS and proteasome inhibitors. Recently, NAC was used as a ROS inhibitor to functionally characterize a novel anticancer compound, piperlongumine, leading to its description as a ROS inducer. In contrast, our own experiments showed that this compound depicts features of proteasome inhibitors including suppression of FOXM1 (Forkhead box protein M1), stabilization of cellular proteins, induction of ROS-independent apoptosis and enhanced accumulation of ubiquitin conjugates. In addition, NAC, but not catalase or Trolox, interfered with the activity of piperlongumine, further supporting that piperlongumine is a proteasome inhibitor. Most importantly, we showed that NAC, but not other ROS scavengers, directly binds to proteasome inhibitors. To our knowledge, NAC is the first known compound that directly interacts with and antagonizes the activity of proteasome inhibitors. Taken together, the findings of the present study suggest that, as a result of the dual nature of NAC, data interpretation might not be straightforward when NAC is utilized as an antioxidant to demonstrate ROS involvement in drug-induced apoptosis.

  17. A specific and potent inhibitor of glucosylceramide synthase for substrate inhibition therapy of Gaucher disease.

    Science.gov (United States)

    McEachern, Kerry Anne; Fung, John; Komarnitsky, Svetlana; Siegel, Craig S; Chuang, Wei-Lien; Hutto, Elizabeth; Shayman, James A; Grabowski, Gregory A; Aerts, Johannes M F G; Cheng, Seng H; Copeland, Diane P; Marshall, John

    2007-07-01

    An approach to treating Gaucher disease is substrate inhibition therapy which seeks to abate the aberrant lysosomal accumulation of glucosylceramide. We have identified a novel inhibitor of glucosylceramide synthase (Genz-112638) and assessed its activity in a murine model of Gaucher disease (D409V/null). Biochemical characterization of Genz-112638 showed good potency (IC(50) approximately 24nM) and specificity against the target enzyme. Mice that received drug prior to significant accumulation of substrate (10 weeks of age) showed reduced levels of glucosylceramide and number of Gaucher cells in the spleen, lung and liver when compared to age-matched control animals. Treatment of older mice that already displayed significant amounts of tissue glucosylceramide (7 months old) resulted in arrest of further accumulation of the substrate and appearance of additional Gaucher cells in affected organs. These data indicate that substrate inhibition therapy with Genz-112638 represents a viable alternate approach to enzyme therapy to treat the visceral pathology in Gaucher disease.

  18. Proton pump inhibitor-induced tumour cell death by inhibition of a detoxification mechanism.

    Science.gov (United States)

    Fais, S

    2010-05-01

    This review presents a possible new approach against cancer, as represented by inhibition of proton pumps, a mechanism used by tumour cells to avoid intracellular accumulation of toxic substances. Proton pump inhibitors (PPIs) belong to a family of pro-drugs that are currently used in the treatment of peptic diseases needing acidity to be activated. PPIs target the acidic tumour mass, where they are metabolized, thus blocking proton traffic. Proton pump inhibition triggers a rapid cell death as a result of intracellular acidification, caspase activation and early accumulation of reactive oxygen species into tumour cells. As a whole, the devastating effect of PPIs on tumour cells suggest the triggering of a fatal cell toxification. Many human tumours, including melanoma, osteosarcoma, lymphomas and various adenocarcinomas are responsive to PPIs. This appears highly conceivable, in as much as almost all human tumours are acidic and express high levels of proton pumps. Paradoxically, metastatic tumours appear to be more responsive to PPIs being more acidic than the majority of primary tumours. However, two clinical trials test the effectiveness of PPIs in chemosensitizing melanoma and osteosarcoma patients. Indeed, tumour acidity represents a very potent mechanism of chemoresistance. A majority of cytotoxic agents, being weak bases, are quickly protonated outside and do not enter the cells, thus preventing drugs to reach specific cellular targets. Clinical data will provide the proof of concept on the use of PPIs as a new class of antitumour agent with a very low level of systemic toxicity as compared with standard chemotherapeutic agents.

  19. The selective serotonin reuptake inhibitor, escitalopram, enhances inhibition of prepotent responding and spatial reversal learning

    Science.gov (United States)

    Brown, Holden D.; Amodeo, Dionisio A.; Sweeney, John A.; Ragozzino, Michael E.

    2011-01-01

    Previous findings indicate treatment with a selective serotonin reuptake inhibitor (SSRI) facilitates behavioral flexibility when conditions require inhibition of a learned response pattern. The present experiment investigated whether acute treatment with the SSRI, escitalopram, affects behavioral flexibility when conditions require inhibition of a naturally-biased response pattern (elevated conflict test) and/or reversal of a learned response pattern (spatial reversal learning). An additional experiment was carried out to determine whether escitalopram, at doses that affected behavioral flexibility, also reduced anxiety as tested in the elevated plus-maze. In each experiment, Long-Evans rats received an intraperitoneal injection of either saline or escitalopram (0.03, 0.3 or 1.0 mg/kg) 30 minutes prior to behavioral testing. Escitalopram, at all doses tested, enhanced acquisition in the elevated conflict test, but did not affect performance in the elevated plus-maze. Escitalopram (0.3 and 1.0 mg/kg) did not alter acquisition of the spatial discrimination, but facilitated reversal learning. In the elevated conflict and spatial reversal learning test, escitalopram enhanced the ability to maintain the relevant strategy after being initially selected. The present findings suggest that enhancing serotonin transmission with a SSRI facilitates inhibitory processes when conditions require a shift away from either a naturally-biased response pattern or a learned choice pattern. PMID:22219222

  20. Novel Midkine Inhibitor iMDK Inhibits Tumor Growth and Angiogenesis in Oral Squamous Cell Carcinoma.

    Science.gov (United States)

    Masui, Masanori; Okui, Tatsuo; Shimo, Tsuyoshi; Takabatake, Kiyofumi; Fukazawa, Takuya; Matsumoto, Kenichi; Kurio, Naito; Ibaragi, Soichiro; Naomoto, Yoshio; Nagatsuka, Hitoshi; Sasaki, Akira

    2016-06-01

    Midkine is a heparin-binding growth factor highly expressed in various human malignant tumors. However, its role in the growth of oral squamous cell carcinoma is not well understood. In this study, we analyzed the antitumor effect of a novel midkine inhibitor (iMDK) against oral squamous cell carcinoma. Administration of iMDK induced a robust antitumor response and suppressed cluster of differentiation 31 (CD31) expression in oral squamous cell carcinoma HSC-2 cells and SAS cells xenograft models. iMDK inhibited the proliferation of these cells dose-dependently, as well as the expression of midkine and phospho-extracellular signal-regulated kinase in HSC-2 and SAS cells. Moreover, iMDK significantly inhibited vascular endothelial growth factor and induced tube growth of human umbilical vein endothelial cells in a dose-dependent fashion. These findings suggest that midkine is critically involved in oral squamous cell carcinoma and iMDK can be effectively used for the treatment of oral squamous cell carcinoma. Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  1. Fasting potentiates the anticancer activity of tyrosine kinase inhibitors by strengthening MAPK signaling inhibition

    Science.gov (United States)

    Caffa, Irene; D'Agostino, Vito; Damonte, Patrizia; Soncini, Debora; Cea, Michele; Monacelli, Fiammetta; Odetti, Patrizio; Ballestrero, Alberto; Provenzani, Alessandro; Longo, Valter D.; Nencioni, Alessio

    2015-01-01

    Tyrosine kinase inhibitors (TKIs) are now the mainstay of treatment in many types of cancer. However, their benefit is frequently short-lived, mandating the search for safe potentiation strategies. Cycles of fasting enhance the activity of chemo-radiotherapy in preclinical cancer models and dietary approaches based on fasting are currently explored in clinical trials. Whether combining fasting with TKIs is going to be potentially beneficial remains unknown. Here we report that starvation conditions increase the ability of commonly administered TKIs, including erlotinib, gefitinib, lapatinib, crizotinib and regorafenib, to block cancer cell growth, to inhibit the mitogen-activated protein kinase (MAPK) signaling pathway and to strengthen E2F-dependent transcription inhibition. In cancer xenografts models, both TKIs and cycles of fasting slowed tumor growth, but, when combined, these interventions were significantly more effective than either type of treatment alone. In conclusion, cycles of fasting or of specifically designed fasting-mimicking diets should be evaluated in clinical studies as a means to potentiate the activity of TKIs in clinical use. PMID:25909220

  2. New strategy for renal fibrosis: Targeting Smad3 proteins for ubiquitination and degradation.

    Science.gov (United States)

    Wang, Xin; Feng, Shaozhen; Fan, Jinjin; Li, Xiaoyan; Wen, Qiong; Luo, Ning

    2016-09-15

    Smad3 is a critical signaling protein in renal fibrosis. Proteolysis targeting chimeric molecules (PROTACs) are small molecules designed to degrade target proteins via ubiquitination. They have three components: (1) a recognition motif for E3 ligase; (2) a linker; and (3) a ligand for the target protein. We aimed to design a new PROTAC to prevent renal fibrosis by targeting Smad3 proteins and using hydroxylated pentapeptide of hypoxia-inducible factor-1α as the recognition motif for von Hippel-Lindau (VHL) ubiquitin ligase (E3). Computer-aided drug design was used to find a specific ligand targeting Smad3. Surface plasmon resonance (SPR) was used to verify and optimize screening results. Synthesized PROTAC was validated by two-stage mass spectrometry. The PROTAC's specificity for VHL (E3 ligase) was proved with two human renal carcinoma cell lines, 786-0 (VHL(-)) and ACHN (VHL(+)), and its anti-fibrosis effect was tested in renal fibrosis cell models. Thirteen small molecular compounds (SMCs) were obtained from the Enamine library using GLIDE molecular docking program. SPR results showed that #8 SMC (EN300-72284) combined best with Smad3 (KD=4.547×10(-5)M). Mass spectrometry showed that synthesized PROTAC had the correct peptide molecular weights. Western blot showed Smad3 was degraded by PROTAC with whole-cell lysate of ACHN but not 786-0. Degradation, but not ubiquitination, of Smad3 was inhibited by proteasome inhibitor MG132. The upregulation of fibronectin and Collagen I induced by TGF-β1 in both renal fibroblast and mesangial cells were inhibited by PROTAC. The new PROTAC might prevent renal fibrosis by targeting Smad3 for ubiquitination and degradation. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Ubiquitination is absolutely required for the degradation of hypoxia-inducible factor - 1 alpha protein in hypoxic conditions

    International Nuclear Information System (INIS)

    Wang, Ronghai; Zhang, Ping; Li, Jinhang; Guan, Hongzai; Shi, Guangjun

    2016-01-01

    The hypoxia-inducible factor (HIF) is recognized as the master regulator of hypoxia response. HIF-α subunits expression are tightly regulated. In this study, our data show that ts20 cells still expressed detectable E1 protein even at 39.5° C for 12 h, and complete depletion of E1 protein expression at 39.5° C by siRNA enhanced HIF-1α and P53 protein expression. Further inhibition of E1 at 39.5 °C by siRNA, or E1 inhibitor Ube1-41 completely blocked HIF-1α degradation. Moreover, immunoprecipitations of co-transfection of HA-ubiquitin and FLAG–HIF–1α plasmids directly confirmed the involvement of ubiquitin in the hypoxic degradation of HIF-1α. Additionally, hypoxic HIF-1 α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization. Taken together, our data suggest that constitutive HIF-1α protein degradation in hypoxia is absolutely ubiquitination-dependent, and unidentified E3 ligase may exist for this degradation pathway. - Highlights: • HIF-1α protein is constitutively degraded in hypoxic conditions. • Requirement of ubiquitination for HIF-1α degradation in hypoxia. • Hypoxic HIF-1α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization.

  4. Ubiquitination is absolutely required for the degradation of hypoxia-inducible factor - 1 alpha protein in hypoxic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ronghai [Department of Urology, Linzi District People' s Hospital, Zibo, 255400 (China); Zhang, Ping, E-mail: zpskx001@163.com [Department of Gynecology, Qingdao Municipal Hospital, Qingdao, 266011 (China); Li, Jinhang [Department of Gynecology, Qingdao Municipal Hospital, Qingdao, 266011 (China); Guan, Hongzai [Laboratory Department, School of Medicine, Qingdao University, Qingdao, 266071 (China); Shi, Guangjun, E-mail: qdmhshigj@yahoo.com [Department of Hepatobiliary Surgery, Qingdao Municipal Hospital, Qingdao, 266071 (China)

    2016-01-29

    The hypoxia-inducible factor (HIF) is recognized as the master regulator of hypoxia response. HIF-α subunits expression are tightly regulated. In this study, our data show that ts20 cells still expressed detectable E1 protein even at 39.5° C for 12 h, and complete depletion of E1 protein expression at 39.5° C by siRNA enhanced HIF-1α and P53 protein expression. Further inhibition of E1 at 39.5 °C by siRNA, or E1 inhibitor Ube1-41 completely blocked HIF-1α degradation. Moreover, immunoprecipitations of co-transfection of HA-ubiquitin and FLAG–HIF–1α plasmids directly confirmed the involvement of ubiquitin in the hypoxic degradation of HIF-1α. Additionally, hypoxic HIF-1 α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization. Taken together, our data suggest that constitutive HIF-1α protein degradation in hypoxia is absolutely ubiquitination-dependent, and unidentified E3 ligase may exist for this degradation pathway. - Highlights: • HIF-1α protein is constitutively degraded in hypoxic conditions. • Requirement of ubiquitination for HIF-1α degradation in hypoxia. • Hypoxic HIF-1α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization.

  5. Garcinol, a Histone Acetyltransferase Inhibitor, Radiosensitizes Cancer Cells by Inhibiting Non-Homologous End Joining

    Energy Technology Data Exchange (ETDEWEB)

    Oike, Takahiro [Division of Multistep Carcinogenesis, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Division of Genome Biology, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Ogiwara, Hideaki [Division of Genome Biology, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Torikai, Kohta [Gunma University Heavy Ion Medical Center, Maebashi, Gunma (Japan); Nakano, Takashi [Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma (Japan); Yokota, Jun [Division of Multistep Carcinogenesis, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan); Kohno, Takashi, E-mail: tkkohno@ncc.go.jp [Division of Genome Biology, National Cancer Center Research Institute, Chuo-ku, Tokyo (Japan)

    2012-11-01

    Purpose: Non-homologous end joining (NHEJ), a major pathway used to repair DNA double-strand breaks (DSBs) generated by ionizing radiation (IR), requires chromatin remodeling at DSB sites through the acetylation of histones by histone acetyltransferases (HATs). However, the effect of compounds with HAT inhibitory activities on the DNA damage response (DDR), including the NHEJ and cell cycle checkpoint, as well as on the radiosensitivity of cancer cells, remains largely unclear. Here, we investigated whether garcinol, a HAT inhibitor found in the rinds of Garcinia indica fruit (called mangosteens), has effects on DDR, and whether it can be used for radiosensitization. Methods and Materials: The following assays were used to examine the effect of garcinol on the inhibition of DSB repair, including the following: a conventional neutral comet assay; a cell-based assay recently developed by us, in which NHEJ repair of DSBs on chromosomal DNA was evaluated; the micrococcal nuclease sensitivity assay; and immunoblotting for autophosphorylation of DNA-dependent protein kinase catalytic subunit (DNA-PKcs). We assessed the effect of garcinol on the cell cycle checkpoint after IR treatment by analyzing the phosphorylation levels of checkpoint kinases CHK1 and CHK2 and histone H3, and by cell cycle profile analysis using flow cytometry. The radiosensitizing effect of garcinol was assessed by a clonogenic survival assay, whereas its effects on apoptosis and senescence were examined by annexin V and senescence-associated {beta}-galactosidase (SA-{beta}-Gal) staining, respectively. Results: We found that garcinol inhibits DSB repair, including NHEJ, without affecting cell cycle checkpoint. Garcinol radiosensitized A549 lung and HeLa cervical carcinoma cells with dose enhancement ratios (at 10% surviving fraction) of 1.6 and 1.5, respectively. Cellular senescence induced by IR was enhanced by garcinol. Conclusion: These results suggest that garcinol is a radiosensitizer that

  6. Promoters active in interphase are bookmarked during mitosis by ubiquitination

    Science.gov (United States)

    Arora, Mansi; Zhang, Jie; Heine, George F.; Ozer, Gulcin; Liu, Hui-wen; Huang, Kun; Parvin, Jeffrey D.

    2012-01-01

    We analyzed modification of chromatin by ubiquitination in human cells and whether this mark changes through the cell cycle. HeLa cells were synchronized at different stages and regions of the genome with ubiquitinated chromatin were identified by affinity purification coupled with next-generation sequencing. During interphase, ubiquitin marked the chromatin on the transcribed regions of ∼70% of highly active genes and deposition of this mark was sensitive to transcriptional inhibition. Promoters of nearly half of the active genes were highly ubiquitinated specifically during mitosis. The ubiquitination at the coding regions in interphase but not at promoters during mitosis was enriched for ubH2B and dependent on the presence of RNF20. Ubiquitin labeling of both promoters during mitosis and transcribed regions during interphase, correlated with active histone marks H3K4me3 and H3K36me3 but not a repressive histone modification, H3K27me3. The high level of ubiquitination at the promoter chromatin during mitosis was transient and was removed within 2 h after the cells exited mitosis and entered the next cell cycle. These results reveal that the ubiquitination of promoter chromatin during mitosis is a bookmark identifying active genes during chromosomal condensation in mitosis, and we suggest that this process facilitates transcriptional reactivation post-mitosis. PMID:22941662

  7. Novel Hypothesis to Explain Why SGLT2 Inhibitors Inhibit Only 30–50% of Filtered Glucose Load in Humans

    Science.gov (United States)

    Abdul-Ghani, Muhammad A.; DeFronzo, Ralph A.; Norton, Luke

    2013-01-01

    Inhibitors of sodium-glucose cotransporter 2 (SGLT2) are a novel class of antidiabetes drugs, and members of this class are under various stages of clinical development for the management of type 2 diabetes mellitus (T2DM). It is widely accepted that SGLT2 is responsible for >80% of the reabsorption of the renal filtered glucose load. However, maximal doses of SGLT2 inhibitors fail to inhibit >50% of the filtered glucose load. Because the clinical efficacy of this group of drugs is entirely dependent on the amount of glucosuria produced, it is important to understand why SGLT2 inhibitors inhibit <50% of the filtered glucose load. In this Perspective, we provide a novel hypothesis that explains this apparent puzzle and discuss some of the clinical implications inherent in this hypothesis. PMID:24065789

  8. Novel hypothesis to explain why SGLT2 inhibitors inhibit only 30-50% of filtered glucose load in humans.

    Science.gov (United States)

    Abdul-Ghani, Muhammad A; DeFronzo, Ralph A; Norton, Luke

    2013-10-01

    Inhibitors of sodium-glucose cotransporter 2 (SGLT2) are a novel class of antidiabetes drugs, and members of this class are under various stages of clinical development for the management of type 2 diabetes mellitus (T2DM). It is widely accepted that SGLT2 is responsible for >80% of the reabsorption of the renal filtered glucose load. However, maximal doses of SGLT2 inhibitors fail to inhibit >50% of the filtered glucose load. Because the clinical efficacy of this group of drugs is entirely dependent on the amount of glucosuria produced, it is important to understand why SGLT2 inhibitors inhibit <50% of the filtered glucose load. In this Perspective, we provide a novel hypothesis that explains this apparent puzzle and discuss some of the clinical implications inherent in this hypothesis.

  9. PKC-Dependent GlyT1 Ubiquitination Occurs Independent of Phosphorylation: Inespecificity in Lysine Selection for Ubiquitination.

    Directory of Open Access Journals (Sweden)

    Susana P Barrera

    Full Text Available Neurotransmitter transporter ubiquitination is emerging as the main mechanism for endocytosis and sorting of cargo into lysosomes. In this study, we demonstrate PKC-dependent ubiquitination of three different isoforms of the glycine transporter 1 (GlyT1. Incubation of cells expressing transporter with the PKC activator phorbol ester induced a dramatic, time-dependent increase in GlyT1 ubiquitination, followed by accumulation of GlyT1 in EEA1 positive early endosomes. This occurred via a mechanism that was abolished by inhibition of PKC. GlyT1 endocytosis was confirmed in both retinal sections and primary cultures of mouse amacrine neurons. Replacement of only all lysines in the N-and C-termini to arginines prevented ubiquitination and endocytosis, displaying redundancy in the mechanism of ubiquitination. Interestingly, a 40-50% reduction in glycine uptake was detected in phorbol-ester stimulated cells expressing the WT-GlyT1, whereas no significant change was for the mutant protein, demonstrating that endocytosis participates in the reduction of uptake. Consistent with previous findings for the dopamine transporter DAT, ubiquitination of GlyT1 tails functions as sorting signal to deliver transporter into the lysosome and removal of ubiquitination sites dramatically attenuated the rate of GlyT1 degradation. Finally, we showed for the first time that PKC-dependent GlyT1 phosphorylation was not affected by removal of ubiquitination sites, suggesting separate PKC-dependent signaling events for these posttranslational modifications.

  10. The Bruton tyrosine kinase inhibitor PCI-32765 ameliorates autoimmune arthritis by inhibition of multiple effector cells

    Science.gov (United States)

    2011-01-01

    Introduction The aim was to determine the effect of the Bruton tyrosine kinase (Btk)-selective inhibitor PCI-32765, currently in Phase I/II studies in lymphoma trials, in arthritis and immune-complex (IC) based animal models and describe the underlying cellular mechanisms. Methods PCI-32765 was administered in a series of murine IC disease models including collagen-induced arthritis (CIA), collagen antibody-induced arthritis (CAIA), reversed passive anaphylactic reaction (RPA), and passive cutaneous anaphylaxis (PCA). Clinical and pathologic features characteristic of each model were examined following treatment. PCI-32765 was then examined in assays using immune cells relevant to the pathogenesis of arthritis, and where Btk is thought to play a functional role. These included proliferation and calcium mobilization in B cells, cytokine and chemokine production in monocytes/macrophages, degranulation of mast cells and its subsequent cytokine/chemokine production. Results PCI-32765 dose-dependently and potently reversed arthritic inflammation in a therapeutic CIA model with an ED50 of 2.6 mg/kg/day. PCI-32765 also prevented clinical arthritis in CAIA models. In both models, infiltration of monocytes and macrophages into the synovium was completely inhibited and importantly, the bone and cartilage integrity of the joints were preserved. PCI-32765 reduced inflammation in the Arthus and PCA assays. In vitro, PCI-32765 inhibited BCR-activated primary B cell proliferation (IC50 = 8 nM). Following FcγR stimulation, PCI-32765 inhibited TNFα, IL-1β and IL-6 production in primary monocytes (IC50 = 2.6, 0.5, 3.9 nM, respectively). Following FcεRI stimulation of cultured human mast cells, PCI-32765 inhibited release of histamine, PGD2, TNF-α, IL-8 and MCP-1. Conclusions PCI-32765 is efficacious in CIA, and in IC models that do not depend upon autoantibody production from B cells. Thus PCI-32765 targets not only B lymphocytes but also monocytes, macrophages and mast cells

  11. Kinetics of Corrosion Inhibition of Aluminum in Acidic Media by Water-Soluble Natural Polymeric Pectates as Anionic Polyelectrolyte Inhibitors.

    Science.gov (United States)

    Hassan, Refat M; Zaafarany, Ishaq A

    2013-06-17

    Corrosion inhibition of aluminum (Al) in hydrochloric acid by anionic polyeletrolyte pectates (PEC) as a water-soluble natural polymer polysaccharide has been studied using both gasometric and weight loss techniques. The results drawn from these two techniques are comparable and exhibit negligible differences. The inhibition efficiency was found to increase with increasing inhibitor concentration and decrease with increasing temperature. The inhibition action of PEC on Al metal surface was found to obey the Freundlich isotherm. Factors such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and temperature affecting the corrosion rates were examined. The kinetic parameters were evaluated and a suitable corrosion mechanism consistent with the kinetic results is discussed in the paper.

  12. Kinetics of Corrosion Inhibition of Aluminum in Acidic Media by Water-Soluble Natural Polymeric Pectates as Anionic Polyelectrolyte Inhibitors

    Directory of Open Access Journals (Sweden)

    Refat M. Hassan

    2013-06-01

    Full Text Available Corrosion inhibition of aluminum (Al in hydrochloric acid by anionic polyeletrolyte pectates (PEC as a water-soluble natural polymer polysaccharide has been studied using both gasometric and weight loss techniques. The results drawn from these two techniques are comparable and exhibit negligible differences. The inhibition efficiency was found to increase with increasing inhibitor concentration and decrease with increasing temperature. The inhibition action of PEC on Al metal surface was found to obey the Freundlich isotherm. Factors such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and temperature affecting the corrosion rates were examined. The kinetic parameters were evaluated and a suitable corrosion mechanism consistent with the kinetic results is discussed in the paper.

  13. High potency inhibition of hERG potassium channels by the sodium–calcium exchange inhibitor KB-R7943

    Science.gov (United States)

    Cheng, Hongwei; Zhang, Yihong; Du, Chunyun; Dempsey, Christopher E; Hancox, Jules C

    2012-01-01

    BACKGROUND AND PURPOSE KB-R7943 is an isothiourea derivative that is used widely as a pharmacological inhibitor of sodium–calcium exchange (NCX) in experiments on cardiac and other tissue types. This study investigated KB-R7943 inhibition of hERG (human ether-à-go-go-related gene) K+ channels that underpin the cardiac rapid delayed rectifier potassium current, IKr. EXPERIMENTAL APPROACH Whole-cell patch-clamp measurements were made of hERG current (IhERG) carried by wild-type or mutant hERG channels and of native rabbit ventricular IKr. Docking simulations utilized a hERG homology model built on a MthK-based template. KEY RESULTS KB-R7943 inhibited both IhERG and native IKr rapidly on membrane depolarization with IC50 values of ∼89 and ∼120 nM, respectively, for current tails at −40 mV following depolarizing voltage commands to +20 mV. Marked IhERG inhibition also occurred under ventricular action potential voltage clamp. IhERG inhibition by KB-R7943 exhibited both time- and voltage-dependence but showed no preference for inactivated over activated channels. Results of alanine mutagenesis and docking simulations indicate that KB-R7943 can bind to a pocket formed of the side chains of aromatic residues Y652 and F656, with the compound's nitrobenzyl group orientated towards the cytoplasmic side of the channel pore. The structurally related NCX inhibitor SN-6 also inhibited IhERG, but with a markedly reduced potency. CONCLUSIONS AND IMPLICATIONS KB-R7943 inhibits IhERG/IKr with a potency that exceeds that reported previously for acute cardiac NCX inhibition. Our results also support the feasibility of benzyloxyphenyl-containing NCX inhibitors with reduced potential, in comparison with KB-R7943, to inhibit hERG. PMID:21950687

  14. New comprehensive studies of a gold(III) Dithiocarbamate complex with proven anticancer properties: Aqueous dissolution with cyclodextrins, pharmacokinetics and upstream inhibition of the ubiquitin-proteasome pathway.

    Science.gov (United States)

    Tomasello, Marianna F; Nardon, Chiara; Lanza, Valeria; Di Natale, Giuseppe; Pettenuzzo, Nicolò; Salmaso, Stefano; Milardi, Danilo; Caliceti, Paolo; Pappalardo, Giuseppe; Fregona, Dolores

    2017-09-29

    The gold(III)-dithiocarbamate complex AuL12 (dibromo [ethyl-N-(dithiocarboxy-kS,kS')-N-methylglycinate] gold(III)), is endowed with promising in vitro/in vivo antitumor activity and toxicological profile. Here, we report our recent strategies to improve its water solubility and stability under physiological conditions along with our efforts for unravelling its tangled mechanism of action. We used three types of α-cyclodextrins (CDs), namely β-CD, Me-β-CD and HP-β-CD to prepare aqueous solutions of AuL12. The ability of these natural oligosaccharide carriers to enhance water solubility of hydrophobic compounds, allowed drug stability of AuL12 to be investigated. Moreover, pharmacokinetic experiments were first carried out for a gold(III) coordination compound, after i.v. injection of the nanoformulation AuL12/HP-β-CD to female mice. The gold content in the blood samples was detected at scheduled times by AAS (atomic absorption spectrometry) analysis, highlighting a fast biodistribution with a t β1/2 of few minutes and a slow escretion (t α1/2 of 14.3 h). The in vitro cytotoxic activity of AuL12 was compared with the AuL12/HP-β-CD mixture against a panel of three human tumor cell lines (i.e., HeLa, KB and MCF7). Concerning the mechanism of action, we previously reported the proteasome-inhibitory activity of some our gold(III)-based compounds. In this work, we moved from the proteasome target to upstream of the important ubiquitin-proteasome pathway, testing the effects of AuL12 on the polyubiquitination reactions involving the Ub-activating (E1) and -conjugating (E2) enzymes. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  15. The ubiquitin ligase tripartite-motif-protein 32 is induced in Duchenne muscular dystrophy.

    Science.gov (United States)

    Assereto, Stefania; Piccirillo, Rosanna; Baratto, Serena; Scudieri, Paolo; Fiorillo, Chiara; Massacesi, Manuela; Traverso, Monica; Galietta, Luis J; Bruno, Claudio; Minetti, Carlo; Zara, Federico; Gazzerro, Elisabetta

    2016-08-01

    Activation of the proteasome pathway is one of the secondary processes of cell damage, which ultimately lead to muscle degeneration and necrosis in Duchenne muscular dystrophy (DMD). In mdx mice, the proteasome inhibitor bortezomib up-regulates the membrane expression of members of the dystrophin complex and reduces the inflammatory reaction. However, chronic inhibition of the 26S proteasome may be toxic, as indicated by the systemic side-effects caused by this drug. Therefore, we sought to determine the components of the ubiquitin-proteasome pathway that are specifically activated in human dystrophin-deficient muscles. The analysis of a cohort of patients with genetically determined DMD or Becker muscular dystrophy (BMD) unveiled a selective up-regulation of the ubiquitin ligase tripartite motif-containing protein 32 (TRIM32). The induction of TRIM32 was due to a transcriptional effect and it correlated with disease severity in BMD patients. In contrast, atrogin1 and muscle RING-finger protein-1 (MuRF-1), which are strongly increased in distinct types of muscular atrophy, were not affected by the DMD dystrophic process. Knock-out models showed that TRIM32 is involved in ubiquitination of muscle cytoskeletal proteins as well as of protein inhibitor of activated STAT protein gamma (Piasγ) and N-myc downstream-regulated gene, two inhibitors of satellite cell proliferation and differentiation. Accordingly, we showed that in DMD/BMD muscle tissue, TRIM32 induction was more pronounced in regenerating myofibers rather than in necrotic muscle cells, thus pointing out a role of this protein in the regulation of human myoblast cell fate. This finding highlights TRIM32 as a possible therapeutic target to favor skeletal muscle regeneration in DMD patients.

  16. The c-Met Inhibitor MSC2156119J Effectively Inhibits Tumor Growth in Liver Cancer Models

    Energy Technology Data Exchange (ETDEWEB)

    Bladt, Friedhelm, E-mail: Friedhelm.Bladt@merckgroup.com; Friese-Hamim, Manja; Ihling, Christian; Wilm, Claudia; Blaukat, Andree [EMD Serono, and Merck Serono Research and Development, Merck KGaA, Darmstadt 64293 (Germany)

    2014-08-19

    The mesenchymal-epithelial transition factor (c-Met) is a receptor tyrosine kinase with hepatocyte growth factor (HGF) as its only high-affinity ligand. Aberrant activation of c-Met is associated with many human malignancies, including hepatocellular carcinoma (HCC). We investigated the in vivo antitumor and antimetastatic efficacy of the c-Met inhibitor MSC2156119J (EMD 1214063) in patient-derived tumor explants. BALB/c nude mice were inoculated with MHCC97H cells or with tumor fragments of 10 patient-derived primary liver cancer explants selected according to c-Met/HGF expression levels. MSC2156119J (10, 30, and 100 mg/kg) and sorafenib (50 mg/kg) were administered orally as single-agent treatment or in combination, with vehicle as control. Tumor response, metastases formation, and alpha fetoprotein (AFP) levels were measured. MSC2156119J inhibited tumor growth and induced complete regression in mice bearing subcutaneous and orthotopic MHCC97H tumors. AFP levels were undetectable after 5 weeks of MSC2156119J treatment, and the number of metastatic lung foci was reduced. Primary liver explant models with strong c-Met/HGF activation showed increased responsiveness to MSC2156119J, with MSC2156119J showing similar or superior activity to sorafenib. Tumors characterized by low c-Met expression were less sensitive to MSC2156119J. MSC2156119J was better tolerated than sorafenib, and combination therapy did not improve efficacy. These findings indicate that selective c-Met/HGF inhibition with MSC2156119J is associated with marked regression of c-Met high-expressing tumors, supporting its clinical development as an antitumor treatment for HCC patients with active c-Met signaling.

  17. Hepatocellular Toxicity Associated with Tyrosine Kinase Inhibitors: Mitochondrial Damage and Inhibition of Glycolysis

    Directory of Open Access Journals (Sweden)

    Franziska Paech

    2017-06-01

    Full Text Available Tyrosine kinase inhibitors (TKIs are anticancer drugs with a lesser toxicity than classical chemotherapeutic agents but still with a narrow therapeutic window. While hepatotoxicity is known for most TKIs, underlying mechanisms remain mostly unclear. We therefore aimed at investigating mechanisms of hepatotoxicity for imatinib, sunitinib, lapatinib and erlotinib in vitro. We treated HepG2 cells, HepaRG cells and mouse liver mitochondria with TKIs (concentrations 1–100 μM for different periods of time and assessed toxicity. In HepG2 cells maintained with glucose (favoring glycolysis, all TKIs showed a time- and concentration-dependent cytotoxicity and, except erlotinib, a drop in intracellular ATP. In the presence of galactose (favoring mitochondrial metabolism, imatinib, sunitinib and erlotinib showed a similar toxicity profile as for glucose whereas lapatinib was less toxic. For imatinib, lapatinib and sunitinib, cytotoxicity increased in HepaRG cells induced with rifampicin, suggesting formation of toxic metabolites. In contrast, erlotinib was more toxic in HepaRG cells under basal than CYP-induced conditions. Imatinib, sunitinib and lapatinib reduced the mitochondrial membrane potential in HepG2 cells and in mouse liver mitochondria. In HepG2 cells, these compounds increased reactive oxygen species production, impaired glycolysis, and induced apoptosis. In addition, imatinib and sunitinib impaired oxygen consumption and activities of complex I and III (only imatinib, and reduced the cellular GSH pool. In conclusion, imatinib and sunitinib are mitochondrial toxicants after acute and long-term exposure and inhibit glycolysis. Lapatinib affected mitochondria only weakly and inhibited glycolysis, whereas the cytotoxicity of erlotinib could not be explained by a mitochondrial mechanism.

  18. Flower inhibition in Kalanchoe blossfeldiana. Bioassay of an endogenous long-day inhibitor and inhibition by (±) abscisic acid and xanthoxin.

    Science.gov (United States)

    Schwabe, W W

    1972-03-01

    The inhibition of flowering in Kalanchoe by crude sap expressed from leaves held in non-inductive long-day conditions is described, using a bioassay technique of leaf injection, which confirms the existence of a transferable inhibitor.This technique has also revealed that ± abscisic acid and Xanthoxin are inhibitory to flowering at 50 and 100 ppm respectively. The previously known inhibitory effects of gibberellic acid on flowering have also been confirmed.

  19. Proteomic characterization of an isolated fraction of synthetic proteasome inhibitor (PSI-induced inclusions in PC12 cells might offer clues to aggresomes as a cellular defensive response against proteasome inhibition by PSI

    Directory of Open Access Journals (Sweden)

    Li Xing'an

    2010-08-01

    Full Text Available Abstract Background Cooperation of constituents of the ubiquitin proteasome system (UPS with chaperone proteins in degrading proteins mediate a wide range of cellular processes, such as synaptic function and neurotransmission, gene transcription, protein trafficking, mitochondrial function and metabolism, antioxidant defence mechanisms, and apoptotic signal transduction. It is supposed that constituents of the UPS and chaperone proteins are recruited into aggresomes where aberrant and potentially cytotoxic proteins may be sequestered in an inactive form. Results To determinate the proteomic pattern of synthetic proteasome inhibitor (PSI-induced inclusions in PC12 cells after proteasome inhibition by PSI, we analyzed a fraction of PSI-induced inclusions. A proteomic feature of the isolated fraction was characterized by identification of fifty six proteins including twenty previously reported protein components of Lewy bodies, twenty eight newly identified proteins and eight unknown proteins. These proteins, most of which were recognized as a profile of proteins within cellular processes mediated by the UPS, a profile of constituents of the UPS and a profile of chaperone proteins, are classed into at least nine accepted categories. In addition, prolyl-4-hydroxylase beta polypeptide, an endoplasmic reticulum member of the protein disulfide isomerase family, was validated in the developmental process of PSI-induced inclusions in the cells. Conclusions It is speculated that proteomic characterization of an isolated fraction of PSI-induced inclusions in PC12 cells might offer clues to appearance of aggresomes serving as a cellular defensive response against proteasome inhibition.

  20. NAD+-dependent HDAC inhibitor stimulates Monascus pigment production but inhibit citrinin.

    Science.gov (United States)

    Hu, Yan; Zhou, Youxiang; Mao, Zejing; Li, Huihui; Chen, Fusheng; Shao, Yanchun

    2017-08-23

    Monascus species are edible fungi due to the production of food colorant and other beneficial compounds. Hence, it has been an attractive thesis to improve their productivities. Increasing numbers of investigations revealed that regulating the activities of histone deacetylases can significantly perturb secondary metabolites (SM) production at a global level. In this study, dihydrocoumarin (DHC, an inhibitor of the Sirtuin family of NAD + -dependent deacetylases) was used to treat Monascus ruber for evaluating its effects on organism growth and SM production. The results revealed that the variation trends of colonial sizes, biomass and mycotoxin were in a dose-dependent manner. Generally, they decreased with the increased DHC concentrations in the designed range. But the variation trend of pigment was different. Comparison of SM profile, three new peaks occurred to the mycelia extractions from DHC-treated strain corresponding to molecular weights 402, 416 and 444, respectively. These three compounds were identified as Monasfluol B, Monascus azaphilone C and acetyl-monasfluol B (a new Monascus chemical pigment structure). In short, DHC can stimulate M. ruber strain to produce more pigment-like polyketides but inhibition of mycotoxin (citrinin).

  1. Inhibition of endothelial cell expression of plasminogen activator inhibitor type-1 by gemfibrozil.

    Science.gov (United States)

    Fujii, S; Sawa, H; Sobel, B E

    1993-10-18

    Increased concentrations of plasminogen activator inhibitor type-1 (PAI-1) in plasma are associated with impaired fibrinolysis and venous and arterial thrombo-embolic disease. In pilot studies designed to identify pharmacologic approaches capable of diminishing such increases, we found that gemfibrozil attenuated the stimulation of synthesis of PAI-1 in a human, immortal, hepatoma cell line (Hep G2) induced by platelets. The present study was performed to determine whether it exerts analogous effects in non-immortal endothelial cells and whether it may therefore facilitate fibrinolysis locally in vivo. Human umbilical vein endothelial cells were incubated with pharmacologic concentrations of gemfibrozil. Gemfibrozil, 100 microM, suppressed basal PAI-1 production by 15% and attenuated the augmentation of synthesis of PAI-1 induced by lysates from platelets (4 x 10(7)/ml) by 36% over 24 h without inhibiting overall protein synthesis. In addition, the increases in PAI-1 mRNA otherwise induced by platelet lysates over 6 h were suppressed by 49% (Northern blots) without any demonstrable change in the intracellular half-life of PAI-1 mRNA. Pulse-chase experiments demonstrated diminution of PAI-1 protein synthesis in parallel with the changes observed in PAI-1 mRNA. To determine whether these effects of gemfibrozil on endothelial cells in vitro were paralleled by consistent changes in the concentrations of PAI-1 in plasma in vivo, we studied rabbits with induced carotid artery thrombosis and thrombolysis.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. Multi-step inhibition explains HIV-1 protease inhibitor pharmacodynamics and resistance

    Science.gov (United States)

    Rabi, S. Alireza; Laird, Gregory M.; Durand, Christine M.; Laskey, Sarah; Shan, Liang; Bailey, Justin R.; Chioma, Stanley; Moore, Richard D.; Siliciano, Robert F.

    2013-01-01

    HIV-1 protease inhibitors (PIs) are among the most effective antiretroviral drugs. They are characterized by highly cooperative dose-response curves that are not explained by current pharmacodynamic theory. An unresolved problem affecting the clinical use of PIs is that patients who fail PI-containing regimens often have virus that lacks protease mutations, in apparent violation of fundamental evolutionary theory. Here, we show that these unresolved issues can be explained through analysis of the effects of PIs on distinct steps in the viral life cycle. We found that PIs do not affect virion release from infected cells but block entry, reverse transcription, and post–reverse transcription steps. The overall dose-response curves could be reconstructed by combining the curves for each step using the Bliss independence principle, showing that independent inhibition of multiple distinct steps in the life cycle generates the highly cooperative dose-response curves that make these drugs uniquely effective. Approximately half of the inhibitory potential of PIs is manifest at the entry step, likely reflecting interactions between the uncleaved Gag and the cytoplasmic tail (CT) of the Env protein. Sequence changes in the CT alone, which are ignored in current clinical tests for PI resistance, conferred PI resistance, providing an explanation for PI failure without resistance. PMID:23979165

  3. The PDE4 inhibitor CHF-6001 and LAMAs inhibit bronchoconstriction-induced remodeling in lung slices

    NARCIS (Netherlands)

    Kistemaker, Loes E M; Oenema, Tjitske A; Baarsma, Hoeke A; Bos, I. Sophie T.; Schmidt, Martina; Facchinetti, Fabrizio; Civelli, Maurizio; Villetti, Gino; Gosens, Reinoud

    2017-01-01

    Combination therapy of PDE4 inhibitors and anticholinergics induces bronchoprotection in COPD. Mechanical forces that arise during bronchoconstriction may contribute to airway remodeling. Therefore, we investigated the impact of PDE4 inhibitors and anticholinergics on bronchoconstriction-induced

  4. Suppression of Homologous Recombination by insulin-like growth factor-1 inhibition sensitizes cancer cells to PARP inhibitors

    International Nuclear Information System (INIS)

    Amin, Oreekha; Beauchamp, Marie-Claude; Nader, Paul Abou; Laskov, Ido; Iqbal, Sanaa; Philip, Charles-André; Yasmeen, Amber; Gotlieb, Walter H.

    2015-01-01

    Impairment of homologous recombination (HR) is found in close to 50 % of ovarian and breast cancer. Tumors with BRCA1 mutations show increased expression of the Insulin-like growth factor type 1 receptor (IGF-1R). We previously have shown that inhibition of IGF-1R results in growth inhibition and apoptosis of ovarian tumor cells. In the current study, we aimed to investigate the correlation between HR and sensitivity to IGF-1R inhibition. Further, we hypothesized that IGF-1R inhibition might sensitize HR proficient cancers to Poly ADP ribose polymerase (PARP) inhibitors. Using ovarian and breast cancer cellular models with known BRCA1 status, we evaluated their HR functionality by RAD51 foci formation assay. The 50 % lethal concentration (LC50) of Insulin-like growth factor type 1 receptor kinase inhibitor (IGF-1Rki) in these cells was assessed, and western immunoblotting was performed to determine the expression of proteins involved in the IGF-1R pathway. Moreover, IGF-1R inhibitors were added on HR proficient cell lines to assess mRNA and protein expression of RAD51 by qPCR and western blot. Also, we explored the interaction between RAD51 and Insulin receptor substance 1 (IRS-1) by immunoprecipitation. Next, combination effect of IGF-1R and PARP inhibitors was evaluated by clonogenic assay. Cells with mutated/methylated BRCA1 showed an impaired HR function, and had an overactivation of the IGF-1R pathway. These cells were more sensitive to IGF-1R inhibition compared to HR proficient cells. In addition, the IGF-IR inhibitor reduced RAD51 expression at mRNA and protein levels in HR proficient cells, and sensitized these cells to PARP inhibitor. Targeting IGF-1R might lead to improved personalized therapeutic approaches in cancer patients with HR deficiency. Targeting both PARP and IGF-1R might increase the clinical efficacy in HR deficient patients and increase the population of patients who may benefit from PARP inhibitors

  5. Dengue Virus Genome Uncoating Requires Ubiquitination.

    Science.gov (United States)

    Byk, Laura A; Iglesias, Néstor G; De Maio, Federico A; Gebhard, Leopoldo G; Rossi, Mario; Gamarnik, Andrea V

    2016-06-28

    The process of genome release or uncoating after viral entry is one of the least-studied steps in the flavivirus life cycle. Flaviviruses are mainly arthropod-borne viruses, including emerging and reemerging pathogens such as dengue, Zika, and West Nile viruses. Currently, dengue virus is one of the most significant human viral pathogens transmitted by mosquitoes and is responsible for about 390 million infections every year around the world. Here, we examined for the first time molecular aspects of dengue virus genome uncoating. We followed the fate of the capsid protein and RNA genome early during infection and found that capsid is degraded after viral internalization by the host ubiquitin-proteasome system. However, proteasome activity and capsid degradation were not necessary to free the genome for initial viral translation. Unexpectedly, genome uncoating was blocked by inhibiting ubiquitination. Using different assays to bypass entry and evaluate the first rounds of viral translation, a narrow window of time during infection that requires ubiquitination but not proteasome activity was identified. In this regard, ubiquitin E1-activating enzyme inhibition was sufficient to stabilize the incoming viral genome in the cytoplasm of infected cells, causing its retention in either endosomes or nucleocapsids. Our data support a model in which dengue virus genome uncoating requires a nondegradative ubiquitination step, providing new insights into this crucial but understudied viral process. Dengue is the most significant arthropod-borne viral infection in humans. Although the number of cases increases every year, there are no approved therapeutics available for the treatment of dengue infection, and many basic aspects of the viral biology remain elusive. After entry, the viral membrane must fuse with the endosomal membrane to deliver the viral genome into the cytoplasm for translation and replication. A great deal of information has been obtained in the last decade

  6. MDM2 binds and inhibits vitamin D receptor

    OpenAIRE

    Heyne, Kristina; Heil, Tessa-Carina; Bette, Birgit; Reichrath, Jörg; Roemer, Klaus

    2015-01-01

    The E3 ubiquitin ligase and transcriptional repressor MDM2 is a potent inhibitor of the p53 family of transcription factors and tumor suppressors. Herein, we report that vitamin D receptor (VDR), another transcriptional regulator and probably, tumor suppressor, is also bound and inhibited by MDM2. This interaction was not affected by vitamin D ligand. VDR was ubiquitylated in the cell and its steady-state level was controlled by the proteasome. Strikingly, overproduced MDM2 reduced the level ...

  7. Neural stem cells inhibit melanin production by activation of Wnt inhibitors.

    Science.gov (United States)

    Hwang, Insik; Park, Ju-Hwang; Park, Hang-Soo; Choi, Kyung-Ah; Seol, Ki-Cheon; Oh, Seung-Ick; Kang, Seongman; Hong, Sunghoi

    2013-12-01

    Melanin for skin pigmentation is synthesized from tyrosine via an enzymatic cascade that is controlled by tyrosinase (TYR), tyrosinase-related protein 1 (TRP1), and dopachrome tautomerase/tyrosinase related protein 2 (Dct/TRP2), which are the targets of microphthalmia-associated transcription factor (MITF). MITF is a master regulator of pigmentation and a target of β-catenin in Wnt/β-catenin signaling during melanocyte differentiation. Stem cells have been used in skin pigmentation studies, but the mechanisms were not determined for the conditioned medium (CM)-mediated effects. In this study, the inhibition and mechanisms of melanin synthesis were elucidated in B16 melanoma cells and UV-B irradiated C57/BL-6 mice that were treated with human neural stem cell-conditioned medium (NSC-CM). B16-F10 melanoma cells (1.5×10(4)cells/well) and the shaved dorsal skin of mice were pretreated with various amount (5, 10, 20, 50, and 100%) of NSC-CM. Melanin contents and TYR activity were measured by a Spectramax spectrophotometer. The expression of TYR, TRP1, Dct/TRP2, MITF, β-catenin and Wnt inhibitors were evaluated by RT-PCR and western blot. The dorsal skin samples were analyzed by immunofluorescence with various antibodies and compared with that control of tissues. Marked decreases were evident in melanin content and TYR, TRP1, DCT/TRP2, MITF, and β-catenin expression in B16 cells and C57/BL-6 mice. NSC-CM negatively regulated Wnt/β-catenin signaling by decreasing the expression of β-catenin protein, which resulted from robust expression of Wnt inhibitors Dickkopf-1 (DKK1) and secreted frizzled-related protein 2 (sFRP2). These results demonstrate that NSC-CM suppresses melanin production in vitro and in vivo, suggesting that factors in NSC-CM may play an important role in deregulation of epidermal melanogenesis. Copyright © 2013 Japanese Society for Investigative Dermatology. All rights reserved.

  8. Organic compounds as corrosion inhibitors for mild steel in acidic media: correlation between inhibition efficiency and chemical structure

    Energy Technology Data Exchange (ETDEWEB)

    Elias, Elizandra C.S.; Chrisman, Erika C.A.N. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil). Escola de Quimica

    2009-12-19

    The use of inhibitors for mild steels corrosion control which are in contact with aggressive environment is an accepted practice in acid treatment of oil-wells. Organic compounds have been studied to evaluate their corrosion inhibition potential. Film-forming corrosion inhibitors, commonly used to protect oil-field equipment, can be absorbed on the steel surface to give structurally ordered layers. Therefore, the electrons should act as an important role for this adsorption. Studies reveal that organic compounds show significant inhibition efficiency. For this purpose, their molecules should contain N, O and S heteroatoms in various functional groups, long hydrocarbon linear or branched radical and anion and cation active components. However, most of these compounds are not only expensive but also toxic to living beings. According to the 'Green Chemistry' rules, corrosion inhibitors based on organic compounds should be cheap, with low toxicity and have high inhibition efficiency. In this study, the effects of some organic compounds with different groups such as amide, ether, phenyldiamine, anime and aminophenol on the corrosion behavior of mild steel in acidic media have been investigated. The experimental data were obtained by gravimetric measurements. The results show that these compounds reveal a promising corrosion inhibition where phenyldiamine is the most efficient. The effect of molecular structure on the corrosion inhibition efficiency was investigated by semi-empirical quantum chemical calculations. The electronic properties such as highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) energy levels, and LUMO-HOMO energy gap orbital density were calculated. The relations between the inhibition efficiency and some quantum parameters are discussed and correlations are proposed. The highest values for the HOMO densities were found in the vicinity nitrogen atom, indicating that it is the most probable adsorption center

  9. Inhibitors of the mitochondrial cytochrome b-c1 complex inhibit the cyanide-insensitive respiration of Trypanosoma brucei.

    Science.gov (United States)

    Turrens, J F; Bickar, D; Lehninger, A L

    1986-06-01

    The cyanide-insensitive respiration of bloodstream trypomastigote forms of Trypanosoma brucei (75 +/- 8 nmol O2 min-1(mg protein)-1) is completely inhibited by the mitochondrial ubiquinone-like inhibitors 2-hydroxy-3-undecyl-1,4-naphthoquinone (UHNQ) and 5-n-undecyl-6-hydroxy-4,7-dioxobenzothiazole (UHDBT). The Ki values for UHDBT (30 nM) and UHNQ (2 microM) are much lower than the reported Ki for salicylhydroxamic acid (SHAM) (5 microM), a widely used inhibitor of the cyanide-insensitive oxidase. UHNQ also stimulated the glycerol-3-phosphate-dependent reduction of phenazine methosulfate, demonstrating that the site of UHNQ inhibition is on the terminal oxidase of the cyanide-insensitive respiration of T. brucei. These results suggest that a ubiquinone-like compound may act as an electron carrier between the two enzymatic components of the cyanide-insensitive glycerol-3-phosphate oxidase.

  10. Human monoamine oxidase is inhibited by tobacco smoke: β-carboline alkaloids act as potent and reversible inhibitors

    International Nuclear Information System (INIS)

    Herraiz, Tomas; Chaparro, Carolina

    2005-01-01

    Monoamine oxidase (MAO) is a mitochondrial outer-membrane flavoenzyme involved in brain and peripheral oxidative catabolism of neurotransmitters and xenobiotic amines, including neurotoxic amines, and a well-known target for antidepressant and neuroprotective drugs. Recently, positron emission tomography imaging has shown that smokers have a much lower activity of peripheral and brain MAO-A (30%) and -B (40%) isozymes compared to non-smokers. This MAO inhibition results from a pharmacological effect of smoke, but little is known about its mechanism. Working with mainstream smoke collected from commercial cigarettes we confirmed that cigarette smoke is a potent inhibitor of human MAO-A and -B isozymes. MAO inhibition was partly reversible, competitive for MAO-A, and a mixed-type inhibition for MAO-B. Two β-carboline alkaloids, norharman (β-carboline) and harman (1-methyl-β-carboline), were identified by GC-MS, quantified, and isolated from the mainstream smoke by solid phase extraction and HPLC. Kinetics analysis revealed that β-carbolines from cigarette smoke were competitive, reversible, and potent inhibitors of MAO enzymes. Norharman was an inhibitor of MAO-A (K i = 1.2 ± 0.18 μM) and MAO-B (K i = 1.12 ± 0.19 μM), and harman of MAO-A (K i = 55.54 ± 5.3 nM). β-Carboline alkaloids are psychopharmacologically active compounds that may occur endogenously in human tissues, including the brain. These results suggest that β-carboline alkaloids from cigarette smoke acting as potent reversible inhibitors of MAO enzymes may contribute to the MAO-reduced activity produced by tobacco smoke in smokers. The presence of MAO inhibitors in smoke like β-carbolines and others may help us to understand some of the purported neuropharmacological effects associated with smoking

  11. Skp2 regulates androgen receptor through ubiquitin-mediated degradation independent of Akt/mTOR pathways in prostate cancer.

    Science.gov (United States)

    Li, Bo; Lu, Wenfu; Yang, Qing; Yu, Xiuping; Matusik, Robert J; Chen, Zhenbang

    2014-04-01

    The intervention of advanced prostate cancer (PCa) in patients has been commonly depending on androgen deprivation therapy. Despite of tremendous research efforts, however, molecular mechanisms on AR regulation remain poorly understood, particularly for castration resistant prostate cancer (CRPC). Targeting AR and associated factors is considered an effective strategy in PCa treatment. Human prostate cancer cells were used in this study. Manipulations of Skp2 expression were achieved by Skp2 shRNA/siRNA or overexpression of plasmids. Dual luciferase reporter assay was applied for AR activity assessment. Western blot, ubiquitination assay, immunoprecipitation, and immunofluorescence were applied to detect the proteins. Our results demonstrated that Skp2 directly involves the regulation of AR expression through ubiquitination-mediated degradation. Skp2 interacted with AR protein in PCa cells, and enforced expression of Skp2 resulted in a decreased level and activity of AR. By contrast, Skp2 knockdown increased the protein accumulation and activity of AR. Importantly, changes of AR contributed by Skp2 led to subsequent alterations of PSA level in PCa cells. AR ubiquitination was significantly increased upon Skp2 overexpression but greatly reduced upon Skp2 knockdown. AR mutant at K847R abrogated Skp2-mediated ubiquitination of AR. NVP-BEZ235, a dual PI3K/mTOR inhibitor, remarkably inhibited Skp2 level with a striking elevation of AR. The results indicate that Skp2 is an E3 ligase for proteasome-dependent AR degradation, and K847 on AR is the recognition site for Skp2-mediated ubiquitination. Our findings reveal an essential role of Skp2 in AR signaling. © 2013 Wiley Periodicals, Inc.

  12. Inhibition of SRC-3 enhances sensitivity of human cancer cells to histone deacetylase inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Zou, Zhengzhi, E-mail: zouzhengzhi@m.scnu.edu.cn [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510000 (China); Luo, Xiaoyong [Department of Oncology, The Affiliated Luoyang Central Hospital of Zhengzhou University, Luoyang 471000 (China); Nie, Peipei [KingMed Diagnostics and KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou 510000 (China); Wu, Baoyan; Zhang, Tao; Wei, Yanchun [MOE Key Laboratory of Laser Life Science and Institute of Laser Life Science, College of Biophotonics, South China Normal University, Guangzhou 510000 (China); Wang, Wenyi [Xiamen Cancer Center, Department of Medical Oncology, The First Affiliated Hospital of Xiamen University, Xiamen 361000 (China); Geng, Guojun; Jiang, Jie [Xiamen Cancer Center, Department of Thoracic Surgery, The First Affiliated Hospital of Xiamen University, Xiamen 361000 (China); Mi, Yanjun, E-mail: myjgj_77@163.com [Xiamen Cancer Center, Department of Medical Oncology, The First Affiliated Hospital of Xiamen University, Xiamen 361000 (China)

    2016-09-09

    SRC-3 is widely expressed in multiple tumor types and involved in cancer cell proliferation and apoptosis. Histone deacetylase (HDAC) inhibitors are promising antitumor drugs. However, the poor efficacy of HDAC inhibitors in solid tumors has restricted its further clinical application. Here, we reported the novel finding that depletion of SRC-3 enhanced sensitivity of breast and lung cancer cells to HDAC inhibitors (SAHA and romidepsin). In contrast, overexpression of SRC-3 decreased SAHA-induced cancer cell apoptosis. Furthermore, we found that SRC-3 inhibitor bufalin increased cancer cell apoptosis induced by HDAC inhibitors. The combination of bufalin and SAHA was particular efficient in attenuating AKT activation and reducing Bcl-2 levels. Taken together, these accumulating data might guide development of new breast and lung cancer therapies. - Highlights: • Depletion of SRC-3 enhanced sensitivity of breast and lung cancer cells to HDAC inhibitors. • Overexpression of SRC-3 enhanced cancer cell resistance to HDAC inhibitors. • SRC-3 inhibitor bufalin increased cancer cell apoptosis induced by HDAC inhibitors. • Bufalin synergized with HDAC inhibitor attenuated AKT activation and reduced Bcl-2 levels in human cancer cell.

  13. A Revisit to the Corrosion Inhibition of Aluminum in Aqueous Alkaline Solutions by Water-Soluble Alginates and Pectates as Anionic Polyelectrolyte Inhibitors

    Directory of Open Access Journals (Sweden)

    Refat Hassan

    2013-01-01

    Full Text Available The corrosion behavior of aluminum (Al in alkaline media in presence of some natural polymer inhibitors has been reinvestigated. The inhibition action of the tested inhibitors was found to obey both Langmuir and Freundlich isotherms models. The inhibition efficiency was found to increase with increasing the inhibitors concentration and decrease with increasing the temperature, suggesting physical adsorption mechanism. Factors such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and temperature affecting the corrosion rates were examined. The kinetic parameters were evaluated, and a suitable corrosion mechanism consistent with the kinetic results obtained is suggested and discussed.

  14. Aurora B kinase inhibition in mitosis: strategies for optimising the use of aurora kinase inhibitors such as AT9283.

    Science.gov (United States)

    Curry, Jayne; Angove, Hayley; Fazal, Lynsey; Lyons, John; Reule, Matthias; Thompson, Neil; Wallis, Nicola

    2009-06-15

    Aurora kinases play a key role in regulating mitotic division and are attractive oncology targets. AT9283, a multi-targeted kinase inhibitor with potent activity against Aurora A and B kinases, inhibited growth and survival of multiple solid tumor cell lines and was efficacious in mouse xenograft models. AT9283-treatment resulted in endoreduplication and ablation of serine-10 histone H3 phosphorylation in both cells and tumor samples, confirming that in these models it acts as an Aurora B kinase inhibitor. In vitro studies demonstrated that exposure to AT9283 for one complete cell cycle committed an entire population of p53 checkpoint-compromised cells (HCT116) to multinucleation and death whereas treatment of p53 checkpoint-competent cells (HMEC, A549) for a similar length of time led to a reversible arrest of cells with 4N DNA. Further studies in synchronized cell populations suggested that exposure to AT9283 during mitosis was critical for optimal cytotoxicity. We therefore investigated ways in which these properties might be exploited to optimize the efficacy and therapeutic index of Aurora kinase inhibitors for p53 checkpoint compromised tumors in vivo. Combining Aurora B kinase inhibition with paclitaxel, which arrests cells in mitosis, in a xenograft model resulted in promising efficacy without additional toxicity. These findings have implications for optimizing the efficacy of Aurora kinase inhibitors in clinical practice.

  15. LACTB, a novel epigenetic silenced tumor suppressor, inhibits colorectal cancer progression by attenuating MDM2-mediated p53 ubiquitination and degradation.

    Science.gov (United States)

    Zeng, Kaixuan; Chen, Xiaoxiang; Hu, Xiuxiu; Liu, Xiangxiang; Xu, Tao; Sun, Huiling; Pan, Yuqin; He, Bangshun; Wang, Shukui

    2018-06-13

    Colorectal cancer (CRC) is one of the most common aggressive malignancies. Like other solid tumors, inactivation of tumor suppressor genes and activation of oncogenes occur during CRC development and progression. Recently, a novel tumor suppressor, LACTB, was proposed to inhibit tumor progression, but the functional and clinical significance of this tumor suppressor in CRC remains unexplored. Herein, we found LACTB was significantly downregulated in CRC due to promoter methylation and histone deacetylation, which was associated with metastasis and advanced clinical stage. CRC patients with low LACTB expression had poorer overall survival and LACTB also determined to be an independent prognostic factor for poorer outcome. Ectopic expression of LACTB suppressed CRC cells proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) in vitro and inhibited CRC growth and metastasis in vivo, while knockout of LACTB by CRISPR/Cas9 gene editing technique resulted in an opposite phenotype. Interestingly, LACTB could exert antitumorigenic effect only in HCT116 and HCT8 cells harboring wild-type TP53, but not in HT29 and SW480 cells harboring mutant TP53 or HCT116 p53 -/- cells. Mechanistic studies demonstrated that LACTB could directly bind to the C terminus of p53 to inhibit p53 degradation by preventing MDM2 from interacting with p53. Moreover, ablation of p53 attenuated the antitumorigenic effects of LACTB overexpression in CRC. Collectively, our findings successfully demonstrate for the first time that LACTB is a novel epigenetic silenced tumor suppressor through modulating the stability of p53, supporting the pursuit of LACTB as a potential therapeutic target for CRC.

  16. Switch in Site of Inhibition: A Strategy for Structure-Based Discovery of Human Topoisomerase IIα Catalytic Inhibitors

    Science.gov (United States)

    2015-01-01

    A study of structure-based modulation of known ligands of hTopoIIα, an important enzyme involved in DNA processes, coupled with synthesis and in vitro assays led to the establishment of a strategy of rational switch in mode of inhibition of the enzyme’s catalytic cycle. 6-Arylated derivatives of known imidazopyridine ligands were found to be selective inhibitors of hTopoIIα, while not showing TopoI inhibition and DNA binding. Interestingly, while the parent imidazopyridines acted as ATP-competitive inhibitors, arylated derivatives inhibited DNA cleavage similar to merbarone, indicating a switch in mode of inhibition from ATP-hydrolysis to the DNA-cleavage stage of catalytic cycle of the enzyme. The 6-aryl-imidazopyridines were relatively more cytotoxic than etoposide in cancer cells and less toxic to normal cells. Such unprecedented strategy will encourage research on “choice-based change” in target-specific mode of action for rapid drug discovery. PMID:25941559

  17. Mitochondrial toxicity of selective COX-2 inhibitors via inhibition of oxidative phosphorylation (ATP synthesis) in rat liver mitochondria

    DEFF Research Database (Denmark)

    Syed, Muzeeb; Skonberg, Christian; Hansen, Steen Honoré

    2016-01-01

    Cyclooxygenase-2 (COX-2) inhibitors (coxibs) are non-steroidal anti-inflammatory drugs (NSAIDs) designed to selectively inhibit COX-2. However, drugs of this therapeutic class are associated with drug induced liver injury (DILI) and mitochondrial injury is likely to play a role. The effects...... of selective COX-2 inhibitors on inhibition of oxidative phosphorylation (ATP synthesis) in rat liver mitochondria were investigated. The order of potency of inhibition of ATP synthesis was: lumiracoxib (IC50: 6.48 ± 2.74 μM)>celecoxib (IC50: 14.92 ± 6.40 μM)>valdecoxib (IC50: 161.4 ± 28.6 μM)>rofecoxib (IC50...... correlation (with r(2)=0.921) was observed between the potency of inhibition of ATP synthesis and the log P values. The in vitro metabolism of coxibs in rat liver mitochondria yielded for each drug substance a major single metabolite and identified a hydroxy metabolite with each of the coxibs...

  18. Ubiquitin Proteasome System in Parkinson Disease: a keeper or a witness?

    Science.gov (United States)

    Martins-Branco, Diogo; Esteves, Ana R.; Santos, Daniel; Arduino, Daniela M.; Swerdlow, Russell H.; Oliveira, Catarina R.; Januario, Cristina; Cardoso, Sandra M.

    2014-01-01

    Objective The aim of this work was to evaluate the role of Ubiquitin-Proteasome System (UPS) on mitochondrial-driven alpha-synuclein (aSN) clearance in in vitro, ex vivo and in vivo Parkinson disease (PD) cellular models. Method We used SH-SY5Y ndufa2 knock-down (KD) cells, PD cybrids and peripheral blood mononuclear cells (PBMC) from patients meeting the diagnostic criteria for PD. We quantified aSN aggregation, proteasome activity and protein ubiquitination levels. In PBMC of PD patients population we evaluated aSN levels in plasma and the influence of several demographic characteristics in the above mentioned determinations. Results We found that ubiquitin-independent proteasome activity was up-regulated in SH-SY5Y ndufa2 KD cells while a down regulation was observed in PD cybrids and PBMC. Moreover, we observed an increase in protein ubiquitination that correlates with a decrease in ubiquitin-dependent proteasome activity. Accordingly, proteasome inhibition prevented ubiquitin-dependent aSN clearance. Ubiquitin-independent proteasome activity was positively correlated with ubiquitination in PBMC. We also report a negative correlation of chymotrypsin-like activity with age in control and late-onset PD groups. Total ubiquitin content is positively correlated with aSN oligomers levels, which leads to an age-dependent increase of aSN ubiquitination in LOPD. Moreover, aSN levels are increased in the plasma of PD patients. Interpretation aSN oligomers are ubiquitinated and we identified an ubiquitin-dependent clearance insufficiency with accumulation of both aSN and ubiquitin. However, SH-SY5Y ndufa2 KD cells showed a significant up-regulation of ubiquitin-independent proteasomal enzymatic activity that could mean a cell rescue attempt. Moreover, we identified that UPS function is age-dependent in PBMC. PMID:22921536

  19. Env-glycoprotein heterogeneity as a source of apparent synergy and enhanced cooperativity in inhibition of HIV-1 infection by neutralizing antibodies and entry inhibitors

    Science.gov (United States)

    Ketas, Thomas J.; Holuigue, Sophie; Matthews, Katie; Moore, John P.

    2011-01-01

    We measured the inhibition of infectivity of HIV-1 isolates and derivative clones by combinations of neutralizing antibodies (NAbs) and other entry inhibitors in a single-cycle-replication assay. Synergy was analyzed both by the current linear and a new nonlinear method. The new method reduced spurious indications of synergy and antagonism. Synergy between NAbs was overall weaker than between other entry inhibitors, and no stronger where one ligand is known to enhance the binding of another. However, synergy was stronger for a genetically heterogeneous HIV-1 R5 isolate than for its derivative clones. Enhanced cooperativity in inhibition by combinations, compared with individual inhibitors, correlated with increased synergy at higher levels of inhibition, while being less variable. Again, cooperativity enhancement was stronger for isolates than clones. We hypothesize that genetic, post-translational or conformational heterogeneity of the Env protein and of other targets for inhibitors can yield apparent synergy and increased cooperativity between inhibitors. PMID:22018634

  20. Inhibition of TLR2 signaling by small molecule inhibitors targeting a pocket within the TLR2 TIR domain

    Science.gov (United States)

    Mistry, Pragnesh; Laird, Michelle H. W.; Schwarz, Ryan S.; Greene, Shannon; Dyson, Tristan; Snyder, Greg A.; Xiao, Tsan Sam; Chauhan, Jay; Fletcher, Steven; Toshchakov, Vladimir Y.; MacKerell, Alexander D.; Vogel, Stefanie N.

    2015-01-01

    Toll-like receptor (TLR) signaling is initiated by dimerization of intracellular Toll/IL-1 receptor resistance (TIR) domains. For all TLRs except TLR3, recruitment of the adapter, myeloid differentiation primary response gene 88 (MyD88), to TLR TIR domains results in downstream signaling culminating in proinflammatory cytokine production. Therefore, blocking TLR TIR dimerization may ameliorate TLR2-mediated hyperinflammatory states. The BB loop within the TLR TIR domain is critical for mediating certain protein–protein interactions. Examination of the human TLR2 TIR domain crystal structure revealed a pocket adjacent to the highly conserved P681 and G682 BB loop residues. Using computer-aided drug design (CADD), we sought to identify a small molecule inhibitor(s) that would fit within this pocket and potentially disrupt TLR2 signaling. In silico screening identified 149 compounds and 20 US Food and Drug Administration-approved drugs based on their predicted ability to bind in the BB loop pocket. These compounds were screened in HEK293T-TLR2 transfectants for the ability to inhibit TLR2-mediated IL-8 mRNA. C16H15NO4 (C29) was identified as a potential TLR2 inhibitor. C29, and its derivative, ortho-vanillin (o-vanillin), inhibited TLR2/1 and TLR2/6 signaling induced by synthetic and bacterial TLR2 agonists in human HEK-TLR2 and THP-1 cells, but only TLR2/1 signaling in murine macrophages. C29 failed to inhibit signaling induced by other TLR agonists and TNF-α. Mutagenesis of BB loop pocket residues revealed an indispensable role for TLR2/1, but not TLR2/6, signaling, suggesting divergent roles. Mice treated with o-vanillin exhibited reduced TLR2-induced inflammation. Our data provide proof of principle that targeting the BB loop pocket is an effective approach for identification of TLR2 signaling inhibitors. PMID:25870276

  1. A novel dual inhibitor of microtubule and Bruton's tyrosine kinase inhibits survival of multiple myeloma and osteoclastogenesis.

    Science.gov (United States)

    Pandey, Manoj K; Gowda, Krishne; Sung, Shen-Shu; Abraham, Thomas; Budak-Alpdogan, Tulin; Talamo, Giampolo; Dovat, Sinisa; Amin, Shantu

    2017-09-01

    Bruton's tyrosine kinase (BTK) regulates many vital signaling pathways and plays a critical role in cell proliferation, survival, migration, and resistance. Previously, we reported that a small molecule, KS99, is an inhibitor of tubulin polymerization. In the present study, we explored whether KS99 is a dual inhibitor of BTK and tubulin polymerization. Although it is known that BTK is required for clonogenic growth and resistance, and microtubules are essential for cancer cell growth, dual targeting of these two components has not been explored previously. Through docking studies, we predicted that KS99 interacts directly with the catalytic domain of BTK and inhibits phosphorylation at the Y223 residue and kinase activities. Treatment of KS99 reduces the cell viability of multiple myeloma (MM) and CD138 + cells, with an IC 50 of between 0.5 and 1.0 μmol/L. We found that KS99 is able to induce apoptosis in MM cells in a caspase-dependent manner. KS99 suppressed the receptor activator of NF-κB ligand (RANKL)-induced differentiation of macrophages to osteoclasts in a dose-dependent manner and, importantly, inhibited the expression of cytokines associated with bone loss. Finally, we found that KS99 inhibits the in vivo tumor growth of MM cells through the inhibition of BTK and tubulin. Overall, our results show that dual inhibition of BTK and tubulin polymerization by KS99 is a viable option in MM treatment, particularly in the inhibition of refraction and relapse. Copyright © 2017 ISEH - International Society for Experimental Hematology. Published by Elsevier Inc. All rights reserved.

  2. Inhibition of post-transcriptional RNA processing by CDK inhibitors and its implication in anti-viral therapy.

    Directory of Open Access Journals (Sweden)

    Jitka Holcakova

    Full Text Available Cyclin-dependent kinases (CDKs are key regulators of the cell cycle and RNA polymerase II mediated transcription. Several pharmacological CDK inhibitors are currently in clinical trials as potential cancer therapeutics and some of them also exhibit antiviral effects. Olomoucine II and roscovitine, purine-based inhibitors of CDKs, were described as effective antiviral agents that inhibit replication of a broad range of wild type human viruses. Olomoucine II and roscovitine show high selectivity for CDK7 and CDK9, with important functions in the regulation of RNA polymerase II transcription. RNA polymerase II is necessary for viral transcription and following replication in cells. We analyzed the effect of inhibition of CDKs by olomoucine II on gene expression from viral promoters and compared its effect to widely-used roscovitine. We found that both roscovitine and olomoucine II blocked the phosphorylation of RNA polymerase II C-terminal domain. However the repression of genes regulated by viral promoters was strongly dependent on gene localization. Both roscovitine and olomoucine II inhibited expression only when the viral promoter was not integrated into chromosomal DNA. In contrast, treatment of cells with genome-integrated viral promoters increased their expression even though there was decreased phosphorylation of the C-terminal domain of RNA polymerase II. To define the mechanism responsible for decreased gene expression after pharmacological CDK inhibitor treatment, the level of mRNA transcription from extrachromosomal DNA was determined. Interestingly, our results showed that inhibition of RNA polymerase II C-terminal domain phosphorylation increased the number of transcribed mRNAs. However, some of these mRNAs were truncated and lacked polyadenylation, which resulted in decreased translation. These results suggest that phosphorylation of RNA polymerase II C-terminal domain is critical for linking transcription and posttrancriptional

  3. Inhibitors of the proteasome reduce the accelerated proteolysis in atrophying rat skeletal muscles.

    OpenAIRE

    Tawa, N E; Odessey, R; Goldberg, A L

    1997-01-01

    Several observations have suggested that the enhanced proteolysis and atrophy of skeletal muscle in various pathological states is due primarily to activation of the ubiquitin-proteasome pathway. To test this idea, we investigated whether peptide aldehyde inhibitors of the proteasome, N-acetyl-leucyl-leucyl-norleucinal (LLN), or the more potent CBZ-leucyl-leucyl-leucinal (MG132) suppressed proteolysis in incubated rat skeletal muscles. These agents (e.g., MG132 at 10 microM) inhibited nonlyso...

  4. Ubiquitin-specific Protease 11 (USP11) Deubiquitinates Hybrid Small Ubiquitin-like Modifier (SUMO)-Ubiquitin Chains to Counteract RING Finger Protein 4 (RNF4)

    DEFF Research Database (Denmark)

    Hendriks, Ivo A; Schimmel, Joost; Eifler, Karolin

    2015-01-01

    of RNF4 as a counterbalancing factor. In response to DNA damage induced by methyl methanesulfonate, USP11 could counteract RNF4 to inhibit the dissolution of nuclear bodies. Thus, we provide novel insight into cross-talk between ubiquitin and SUMO and uncover USP11 and RNF4 as a balanced SUMO...

  5. Mastermind-Like 1 Is Ubiquitinated: Functional Consequences for Notch Signaling.

    Directory of Open Access Journals (Sweden)

    Mozhgan Farshbaf

    Full Text Available Early studies demonstrated the involvement of ubiquitination of the Notch intracellular domain for rapid turnover of the transcriptional complex at Notch target genes. It was shown that this ubiquitination was promoted by the co-activator Mastermind like 1 (MAML1. MAML1 also contains numerous lysine residues that may also be ubiquitinated and necessary for protein regulation. In this study, we show that over-expressed MAML1 is ubiquitinated and identify eight conserved lysine residues which are required for ubiquitination. We also show that p300 stimulates ubiquitination and that Notch inhibits ubiquitination. Furthermore, we show that a mutant MAML1 that has decreased ubiquitination shows increased output from a HES1 reporter gene assay. Therefore, we speculate that ubiquitination of MAML1 might be a mechanism to maintain low levels of the protein until needed for transcriptional activation. In summary, this study identifies that MAML1 is ubiquitinated in the absence of Notch signaling to maintain low levels of MAML1 in the cell. Our data supports the notion that a precise and tight regulation of the Notch pathway is required for this signaling pathway.

  6. A novel HDAC inhibitor, CG200745, inhibits pancreatic cancer cell growth and overcomes gemcitabine resistance

    OpenAIRE

    Lee, Hee Seung; Park, Soo Been; Kim, Sun A; Kwon, Sool Ki; Cha, Hyunju; Lee, Do Young; Ro, Seonggu; Cho, Joong Myung; Song, Si Young

    2017-01-01

    Pancreatic cancer is predominantly lethal, and is primarily treated using gemcitabine, with increasing resistance. Therefore, novel agents that increase tumor sensitivity to gemcitabine are needed. Histone deacetylase (HDAC) inhibitors are emerging therapeutic agents, since HDAC plays an important role in cancer initiation and progression. We evaluated the antitumor effect of a novel HDAC inhibitor, CG200745, combined with gemcitabine/erlotinib on pancreatic cancer cells and gemcitabine-resis...

  7. The inhibition of human T cell proliferation by the caspase inhibitor z-VAD-FMK is mediated through oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Rajah, T.; Chow, S.C., E-mail: chow.sek.chuen@monash.edu

    2014-07-15

    The caspase inhibitor benzyloxycarbony (Cbz)-L-Val-Ala-Asp (OMe)-fluoromethylketone (z-VAD-FMK) has recently been shown to inhibit T cell proliferation without blocking caspase-8 and caspase-3 activation in primary T cells. We showed in this study that z-VAD-FMK treatment leads to a decrease in intracellular glutathione (GSH) with a concomitant increase in reactive oxygen species (ROS) levels in activated T cells. The inhibition of anti-CD3-mediated T cell proliferation induced by z-VAD-FMK was abolished by the presence of low molecular weight thiols such as GSH, N-acetylcysteine (NAC) and L-cysteine, whereas D-cysteine which cannot be metabolised to GSH has no effect. These results suggest that the depletion of intracellular GSH is the underlying cause of z-VAD-FMK-mediated inhibition of T cell activation and proliferation. The presence of exogenous GSH also attenuated the inhibition of anti-CD3-induced CD25 and CD69 expression mediated by z-VAD-FMK. However, none of the low molecular weight thiols were able to restore the caspase-inhibitory properties of z-VAD-FMK in activated T cells where caspase-8 and caspase-3 remain activated and processed into their respective subunits in the presence of the caspase inhibitor. This suggests that the inhibition of T cell proliferation can be uncoupled from the caspase-inhibitory properties of z-VAD-FMK. Taken together, the immunosuppressive effects in primary T cells mediated by z-VAD-FMK are due to oxidative stress via the depletion of GSH.

  8. The inhibition of human T cell proliferation by the caspase inhibitor z-VAD-FMK is mediated through oxidative stress

    International Nuclear Information System (INIS)

    Rajah, T.; Chow, S.C.

    2014-01-01

    The caspase inhibitor benzyloxycarbony (Cbz)-L-Val-Ala-Asp (OMe)-fluoromethylketone (z-VAD-FMK) has recently been shown to inhibit T cell proliferation without blocking caspase-8 and caspase-3 activation in primary T cells. We showed in this study that z-VAD-FMK treatment leads to a decrease in intracellular glutathione (GSH) with a concomitant increase in reactive oxygen species (ROS) levels in activated T cells. The inhibition of anti-CD3-mediated T cell proliferation induced by z-VAD-FMK was abolished by the presence of low molecular weight thiols such as GSH, N-acetylcysteine (NAC) and L-cysteine, whereas D-cysteine which cannot be metabolised to GSH has no effect. These results suggest that the depletion of intracellular GSH is the underlying cause of z-VAD-FMK-mediated inhibition of T cell activation and proliferation. The presence of exogenous GSH also attenuated the inhibition of anti-CD3-induced CD25 and CD69 expression mediated by z-VAD-FMK. However, none of the low molecular weight thiols were able to restore the caspase-inhibitory properties of z-VAD-FMK in activated T cells where caspase-8 and caspase-3 remain activated and processed into their respective subunits in the presence of the caspase inhibitor. This suggests that the inhibition of T cell proliferation can be uncoupled from the caspase-inhibitory properties of z-VAD-FMK. Taken together, the immunosuppressive effects in primary T cells mediated by z-VAD-FMK are due to oxidative stress via the depletion of GSH

  9. BOT-4-one attenuates NLRP3 inflammasome activation: NLRP3 alkylation leading to the regulation of its ATPase activity and ubiquitination.

    Science.gov (United States)

    Shim, Do-Wan; Shin, Woo-Young; Yu, Sang-Hyeun; Kim, Byung-Hak; Ye, Sang-Kyu; Koppula, Sushruta; Won, Hyung-Sik; Kang, Tae-Bong; Lee, Kwang-Ho

    2017-11-08

    The ATPase activity of NLRP3 has pivotal role in inflammasome activation and is recognized as a good target for the development of the NLRP3 inflammasome-specific inhibitor. However, signals in the vicinity of the ATPase activity of NLRP3 have not been fully elucidated. Here, we demonstrate NLRP3 inflammasome-specific action of a benzoxathiole derivative, BOT-4-one. BOT-4-one exhibited an inhibition of NLRP3 inflammasome activation, which was attributable to its alkylating capability to NLRP3. In particular, the NLRP3 alkylation by BOT-4-one led to an impaired ATPase activity of NLRP3, thereby obstructing the assembly of the NLRP3 inflammasome. Additionally, we found that NLRP3 alkylators, including BOT-4-one, enhance the ubiquitination level of NLRP3, which might also contribute to the inhibition of NLRP3 inflammasome activation. Finally, BOT-4-one appeared to be superior to other known NLRP3 alkylators in inhibiting the functionality of the NLRP3 inflammasome and its resulting anti-inflammatory activity was confirmed in vivo using a monosodium urate-induced peritonitis mouse model. Collectively, the results suggest that NLRP3 alkylators function by inhibiting ATPase activity and increasing the ubiquitination level of NLRP3, and BOT-4-one could be the type of NLRP3 inhibitor that may be potentially useful for the novel development of a therapeutic agent in controlling NLRP3 inflammasome-related diseases.

  10. Ubiquitination is absolutely required for the degradation of hypoxia-inducible factor--1 alpha protein in hypoxic conditions.

    Science.gov (United States)

    Wang, Ronghai; Zhang, Ping; Li, Jinhang; Guan, Hongzai; Shi, Guangjun

    2016-01-29

    The hypoxia-inducible factor (HIF) is recognized as the master regulator of hypoxia response. HIF-α subunits expression are tightly regulated. In this study, our data show that ts20 cells still expressed detectable E1 protein even at 39.5° C for 12 h, and complete depletion of E1 protein expression at 39.5° C by siRNA enhanced HIF-1α and P53 protein expression. Further inhibition of E1 at 39.5 °C by siRNA, or E1 inhibitor Ube1-41 completely blocked HIF-1α degradation. Moreover, immunoprecipitations of co-transfection of HA-ubiquitin and FLAG-HIF-1α plasmids directly confirmed the involvement of ubiquitin in the hypoxic degradation of HIF-1α. Additionally, hypoxic HIF-1 α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization. Taken together, our data suggest that constitutive HIF-1α protein degradation in hypoxia is absolutely ubiquitination-dependent, and unidentified E3 ligase may exist for this degradation pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Use of proteasome inhibitors in anticancer therapy

    Directory of Open Access Journals (Sweden)

    Sara M. Schmitt

    2011-10-01

    Full Text Available The importance of the ubiquitin-proteasome pathway to cellular function has brought it to the forefront in the search for new anticancer therapies. The ubiquitin-proteasome pathway has proven promising in targeting various human cancers. The approval of the proteasome inhibitor bortezomib for clinical treatment of relapsed/refractory multiple myeloma and mantle cell lymphoma has validated the ubiquitin-proteasome as a rational target. Bortezomib has shown positive results in clinical use but some toxicity and side effects, as well as resistance, have been observed, indicating that further development of novel, less toxic drugs is necessary. Because less toxic drugs are necessary and drug development can be expensive and time-consuming, using existing drugs that can target the ubiquitin-proteasome pathway in new applications, such as cancer therapy, may be effective in expediting the regulatory process and bringing new drugs to the clinic. Toward this goal, previously approved drugs, such as disulfiram, as well as natural compounds found in common foods, such as green tea polyphenol (--EGCG and the flavonoid apigenin, have been investigated for their possible proteasome inhibitory and cell death inducing abilities. These compounds proved quite promising in preclinical studies and have now moved into clinical trials, with preliminary results that are encouraging. In addition to targeting the catalytic activity of the proteasome pathway, upstream regulators, such as the 19S regulatory cap, as well as E1, E2, and E3, are now being investigated as potential drug targets. This review outlines the development of novel proteasome inhibitors from preclinical to clinical studies, highlighting their abilities to inhibit the tumor proteasome and induce apoptosis in several human cancers.

  12. Density functional theory and quantum mechanics/molecular mechanics study of cysteine protease inhibition by nitrile-based inhibitors.

    Directory of Open Access Journals (Sweden)

    Sam P De Visser

    2013-12-01

    Full Text Available Cysteine protease enzymes are important for human physiology and catalyze key protein degradation pathways. These enzymes react via a nucleophilic reaction mechanism that involves a cysteine residue and the proton of a proximal histidine. Particularly efficient inhibitors of these enzymes are nitrile-based, however, the details of the catalytic reaction mechanism currently are poorly understood. To gain further insight into the inhibition of these molecules, we have performed a combined density functional theory and quantum mechanics/molecular mechanics study on the reaction of a nitrile-based inhibitor with the enzyme active site amino acids. We show here that small perturbations to the inhibitor structure can have dramatic effects on the catalysis and inhibition processes. Thus, we investigated a range of inhibitor templates and show that specific structural changes reduce the inhibitory efficiency by several orders of magnitude. Moreover, as the reaction takes place on a polar surface, we find strong differences between the DFT and QM/MM calculated energetics. In particular, the DFT model led to dramatic distortions from the starting structure and the convergence to a structure that would not fit the enzyme active site. In the subsequent QM/MM study we investigated the use of mechanical versus electronic embedding on the kinetics, thermodynamics and geometries along the reaction mechanism. We find minor effects on the kinetics of the reaction but large geometric and thermodynamics differences as a result of inclusion of electronic embedding corrections. The work here highlights the importance of model choice in the investigation of this biochemical reaction mechanism.

  13. Regulatory T-Cell Augmentation or Interleukin-17 Inhibition Prevents Calcineurin Inhibitor-Induced Hypertension in Mice.

    Science.gov (United States)

    Chiasson, Valorie L; Pakanati, Abhinandan R; Hernandez, Marcos; Young, Kristina J; Bounds, Kelsey R; Mitchell, Brett M

    2017-07-01

    The immunosuppressive calcineurin inhibitors cyclosporine A and tacrolimus alter T-cell subsets and can cause hypertension, vascular dysfunction, and renal toxicity. We and others have reported that cyclosporine A and tacrolimus decrease anti-inflammatory regulatory T cells and increase proinflammatory interleukin-17-producing T cells; therefore, we hypothesized that inhibition of these effects using noncellular therapies would prevent the hypertension, endothelial dysfunction, and renal glomerular injury induced by calcineurin inhibitor therapy. Daily treatment of mice with cyclosporine A or tacrolimus for 1 week significantly decreased CD4 + /FoxP3 + regulatory T cells in the spleen and lymph nodes, as well as induced hypertension, vascular injury and dysfunction, and glomerular mesangial expansion in mice. Daily cotreatment with all-trans retinoic acid reported to increase regulatory T cells and decrease interleukin-17-producing T cells, prevented all of the detrimental effects of cyclosporine A and tacrolimus. All-trans retinoic acid also increased regulatory T cells and prevented the hypertension, endothelial dysfunction, and glomerular injury in genetically modified mice that phenocopy calcineurin inhibitor-treated mice (FKBP12-Tie2 knockout). Treatment with an interleukin-17-neutralizing antibody also increased regulatory T-cell levels and prevented the hypertension, endothelial dysfunction, and glomerular injury in cyclosporine A-treated and tacrolimus-treated mice and FKBP12-Tie2 knockout mice, whereas an isotype control had no effect. Augmenting regulatory T cells and inhibiting interleukin-17 signaling using noncellular therapies prevents the cardiovascular and renal toxicity of calcineurin inhibitors in mice. © 2017 American Heart Association, Inc.

  14. Discovery of a highly selective chemical inhibitor of matrix metalloproteinase-9 (MMP-9) that allosterically inhibits zymogen activation.

    Science.gov (United States)

    Scannevin, Robert H; Alexander, Richard; Haarlander, Tara Mezzasalma; Burke, Sharon L; Singer, Monica; Huo, Cuifen; Zhang, Yue-Mei; Maguire, Diane; Spurlino, John; Deckman, Ingrid; Carroll, Karen I; Lewandowski, Frank; Devine, Eric; Dzordzorme, Keli; Tounge, Brett; Milligan, Cindy; Bayoumy, Shariff; Williams, Robyn; Schalk-Hihi, Celine; Leonard, Kristi; Jackson, Paul; Todd, Matthew; Kuo, Lawrence C; Rhodes, Kenneth J

    2017-10-27

    Aberrant activation of matrix metalloproteinases (MMPs) is a common feature of pathological cascades observed in diverse disorders, such as cancer, fibrosis, immune dysregulation, and neurodegenerative diseases. MMP-9, in particular, is highly dynamically regulated in several pathological processes. Development of MMP inhibitors has therefore been an attractive strategy for therapeutic intervention. However, a long history of failed clinical trials has demonstrated that broad-spectrum MMP inhibitors have limited clinical utility, which has spurred the development of inhibitors selective for individual MMPs. Attaining selectivity has been technically challenging because of sequence and structural conservation across the various MMPs. Here, through a biochemical and structural screening paradigm, we have identified JNJ0966, a highly selective compound that inhibited activation of MMP-9 zymogen and subsequent generation of catalytically active enzyme. JNJ0966 had no effect on MMP-1, MMP-2, MMP-3, MMP-9, or MMP-14 catalytic activity and did not inhibit activation of the highly related MMP-2 zymogen. The molecular basis for this activity was characterized as an interaction of JNJ0966 with a structural pocket in proximity to the MMP-9 zymogen cleavage site near Arg-106, which is distinct from the catalytic domain. JNJ0966 was efficacious in reducing disease severity in a mouse experimental autoimmune encephalomyelitis model, demonstrating the viability of this therapeutic approach. This discovery reveals an unprecedented pharmacological approach to MMP inhibition, providing an opportunity to improve selectivity of future clinical drug candidates. Targeting zymogen activation in this manner may also allow for pharmaceutical exploration of other enzymes previously viewed as intractable drug targets. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Ubiquitin domain proteins in disease

    DEFF Research Database (Denmark)

    Klausen, Louise Kjær; Schulze, Andrea; Seeger, Michael

    2007-01-01

    The human genome encodes several ubiquitin-like (UBL) domain proteins (UDPs). Members of this protein family are involved in a variety of cellular functions and many are connected to the ubiquitin proteasome system, an essential pathway for protein degradation in eukaryotic cells. Despite...... and cancer. Publication history: Republished from Current BioData's Targeted Proteins database (TPdb; http://www.targetedproteinsdb.com)....

  16. The ubiquitin-proteasome system

    Indian Academy of Sciences (India)

    ... the discovery of protein ubiquitination has led to the recognition of cellular proteolysis as a central area of research in biology. Eukaryotic proteins targeted for degradation by this pathway are first 'tagged' by multimers of a protein known as ubiquitin and are later proteolyzed by a giant enzyme known as the proteasome.

  17. Reversible Inhibitors of Monoamine Oxidase-A (RIMAs): Robust, Reversible Inhibition of Human Brain MAO-A by CX157

    Science.gov (United States)

    Fowler, Joanna S; Logan, Jean; Azzaro, Albert J; Fielding, Robert M; Zhu, Wei; Poshusta, Amy K; Burch, Daniel; Brand, Barry; Free, James; Asgharnejad, Mahnaz; Wang, Gene-Jack; Telang, Frank; Hubbard, Barbara; Jayne, Millard; King, Payton; Carter, Pauline; Carter, Scott; Xu, Youwen; Shea, Colleen; Muench, Lisa; Alexoff, David; Shumay, Elena; Schueller, Michael; Warner, Donald; Apelskog-Torres, Karen

    2010-01-01

    Reversible inhibitors of monoamine oxidase-A (RIMA) inhibit the breakdown of three major neurotransmitters, serotonin, norepinephrine and dopamine, offering a multi-neurotransmitter strategy for the treatment of depression. CX157 (3-fluoro-7-(2,2,2-trifluoroethoxy)phenoxathiin-10,10-dioxide) is a RIMA, which is currently in development for the treatment of major depressive disorder. We examined the degree and reversibility of the inhibition of brain monoamine oxidase-A (MAO-A) and plasma CX157 levels at different times after oral dosing to establish a dosing paradigm for future clinical efficacy studies, and to determine whether plasma CX157 levels reflect the degree of brain MAO-A inhibition. Brain MAO-A levels were measured with positron emission tomography (PET) imaging and [11C]clorgyline in 15 normal men after oral dosing of CX157 (20–80 mg). PET imaging was conducted after single and repeated doses of CX157 over a 24-h time course. We found that 60 and 80 mg doses of CX157 produced a robust dose-related inhibition (47–72%) of [11C]clorgyline binding to brain MAO-A at 2 h after administration and that brain MAO-A recovered completely by 24 h post drug. Plasma CX157 concentration was highly correlated with the inhibition of brain MAO-A (EC50: 19.3 ng/ml). Thus, CX157 is the first agent in the RIMA class with documented reversible inhibition of human brain MAO-A, supporting its classification as a RIMA, and the first RIMA with observed plasma levels that can serve as a biomarker for the degree of brain MAO-A inhibition. These data were used to establish the dosing regimen for a current clinical efficacy trial with CX157. PMID:19890267

  18. Inhibition of nitric oxide and inflammatory cytokines in LPS-stimulated murine macrophages by resveratrol, a potent proteasome inhibitor

    Directory of Open Access Journals (Sweden)

    Qureshi Asaf A

    2012-07-01

    Full Text Available Abstract Background Altered immune function during ageing results in increased production of nitric oxide (NO and other inflammatory mediators. Recently, we have reported that NO production was inhibited by naturally-occurring proteasome inhibitors (quercetin, δ-tocotrienol, and riboflavin in lipopolysaccharide (LPS-stimulated RAW264.7 cells, and thioglycolate-elicited peritoneal macrophages from C57BL/6 mice. In a continuous effort to find more potent, non-toxic, commercially available, naturally-occurring proteasome inhibitors that suppress inflammation, the present study was carried out to describe the inhibition of NF-κB activation and NO, TNF-α, IL-6, IL-1β, and iNOS expression by trans-resveratrol, trans-pterostilbene, morin hydrate, and nicotinic acid in LPS-induced RAW 264.7 cells and thioglycolate-elicited peritoneal macrophages from C57BL/6 and BALB/c mice. Results The present results indicate that resveratrol, pterostilbene, and morin hydrate caused significant inhibition (>70% to 90%; P 40%; P 60%; P 40%; P P  Conclusions The present results clearly demonstrate that resveratrol and pterostilbene are particularly potent proteasome inhibitors that suppress expression of genes, and production of inflammatory products in LPS-stimulated RAW 264.7 cells, and macrophages from C57BL/6 and BALB/c mice. Resveratrol and pterostilbene which are present in grapes, blueberries, and red wine, have been implicated as contributing factors to the lower incidence of cardiovascular disease in the French population, despite their relatively high dietary fat intake. Consequently, it appears likely that the beneficial nutritional effects of resveratrol and pterostilbene are due at least in part, to their ability to inhibit NF-κB activation by the proteasome, thereby suppressing activation of pro-inflammatory cytokines and iNOS genes, resulting in decreased secretion of TNF-α, IL-1β, IL-6, and NO levels, in response to inflammatory stimuli

  19. Cardiovascular risk and inhibition of cyclooxygenase: traditional nonsteroidal anti-inflammatory drugs and cyclooxygenase-2 inhibitors

    Directory of Open Access Journals (Sweden)

    M. Campanini

    2013-05-01

    Full Text Available BACKGROUND The development of non-selective nonsteroidal anti-inflammatory drugs (tNSAIDs and, more recently, of selective inhibitors of the cycloooxygenase-2 isoform (COXIBs, has contributed greatly towards the effective management of patients with arthritis and pain complaints. Although COXIBs have demonstrated an improved gastrointestinal tolerability compared with tNSAIDs, the cardiovascular effects of the two drugs types are much controversial. By blocking prostacyclin formation but leaving platelet-derived thromboxane A2 generation unopposed, the potential gastrointestinal benefit of COXIBs may come at cost of increased thrombotic risk. AIM OF THE STUDY This review aims at analysing the cardiovascular effects of the tNSAIDs and COXIBs. METHOD This review addresses the controversy of effects of COXIBs and tNSAIDs in 4 segments. It begins with a discussion about pathophysiological effects of cyclooxygenase inhibition on cardiovascular system. This is followed by a systematic review and meta-analysis of a control, randomized, double blind study and population-based matched case-control study to compare the risk of serious cardiovascular events with tNSAIDs and COXIBs. Then it answers to key questions with the aim to assist the clinicians for a systematic approach to evaluate the risk-benefit-ratio of NSAIDs in the clinical practice. Finally we analyse the open questions associated with the use of NSAIDs and the cardiovascular events. RESULTS The use of rofecoxib demonstrated an increase in adverse cardiovascular events. This toxic effect is not dose-related. The relationship between celecoxib and cardiovascular risk is less clear. The results of different clinical trials are conflicting: some didn’t demonstrate increase in cardiovascular toxicity but the APC study and recently a metanalysis reported a significant incidence of adverse cardiovascular events. Also valdecoxib and parecoxib appear to have increased risk for cardiovascular

  20. Reduction of mouse atherosclerosis by urokinase inhibition or with a limited-spectrum matrix metalloproteinase inhibitor

    DEFF Research Database (Denmark)

    Hu, Jie Hong; Touch, Phanith; Zhang, Jingwan

    2015-01-01

    -accelerated atherosclerosis) to investigate whether systemic inhibition of proteolytic activity of uPA or a subset of MMPs can reduce protease-induced atherosclerosis and aortic dilation. METHODS AND RESULTS: SR-uPA mice were fed a high-fat diet for 10 weeks and treated either with an antibody inhibiting mouse uPA (mU1...... surface lesion coverage. Several lines of evidence identified MMP-13 as a mediator of uPA-induced aortic MMP activity. CONCLUSIONS: Pharmacological inhibition of either uPA or selected MMPs decreased atherosclerosis in SR-uPA mice. uPA inhibition decreased aortic dilation. Differential effects of both...... agents on aortic root vs. distal aortic atherosclerosis suggest prevention of atherosclerosis progression vs. initiation. Systemic inhibition of uPA or a subset of MMPs shows promise for treating atherosclerosis....

  1. Binding and Inhibition of Spermidine Synthase from Plasmodium falciparum and Implications for In Vitro Inhibitor Testing.

    Directory of Open Access Journals (Sweden)

    Janina Sprenger

    Full Text Available The aminopropyltransferase spermidine synthase (SpdS is a promising drug target in cancer and in protozoan diseases including malaria. Plasmodium falciparum SpdS (PfSpdS transfers the aminopropyl group of decarboxylated S-adenosylmethionine (dcAdoMet to putrescine or to spermidine to form spermidine or spermine, respectively. In an effort to understand why efficient inhibitors of PfSpdS have been elusive, the present study uses enzyme activity assays and isothermal titration calorimetry with verified or predicted inhibitors of PfSpdS to analyze the relationship between binding affinity as assessed by KD and inhibitory activity as assessed by IC50. The results show that some predicted inhibitors bind to the enzyme with high affinity but are poor inhibitors. Binding studies with PfSpdS substrates and products strongly support an ordered sequential mechanism in which the aminopropyl donor (dcAdoMet site must be occupied before the aminopropyl acceptor (putrescine site can be occupied. Analysis of the results also shows that the ordered sequential mechanism adequately accounts for the complex relationship between IC50 and KD and may explain the limited success of previous efforts at structure-based inhibitor design for PfSpdS. Based on PfSpdS active-site occupancy, we suggest a classification of ligands that can help to predict the KD-IC50 relations in future design of new inhibitors. The present findings may be relevant for other drug targets that follow an ordered sequential mechanism.

  2. The digestion of phagocytosed collagen is inhibited by the proteinase inhibitors leupeptin and E-64

    NARCIS (Netherlands)

    Everts, V.; Beertsen, W.; Tigchelaar-Gutter, W.

    1985-01-01

    Using morphometric methods the effects of the thiol-proteinase inhibitors leupeptin and E-64 on the digestion of intracytoplasmic collagen fibrils were studied in cultured mouse bone explants. Both drugs caused a dose-dependent increase of lysosomal structures containing cross-banded collagen

  3. Rates of ubiquitin conjugation increase when muscles atrophy, largely through activation of the N-end rule pathway

    Science.gov (United States)

    Solomon, V.; Baracos, V.; Sarraf, P.; Goldberg, A. L.

    1998-01-01

    The rapid loss of muscle mass that accompanies many disease states, such as cancer or sepsis, is primarily a result of increased protein breakdown in muscle, and several observations have suggested an activation of the ubiquitin-proteasome system. Accordingly, in extracts of atrophying muscles from tumor-bearing or septic rats, rates of 125I-ubiquitin conjugation to endogenous proteins were found to be higher than in control extracts. On the other hand, in extracts of muscles from hypothyroid rats, where overall proteolysis is reduced below normal, the conjugation of 125I-ubiquitin to soluble proteins decreased by 50%, and treatment with triiodothyronine (T3) restored ubiquitination to control levels. Surprisingly, the N-end rule pathway, which selectively degrades proteins with basic or large hydrophobic N-terminal residues, was found to be responsible for most of these changes in ubiquitin conjugation. Competitive inhibitors of this pathway that specifically block the ubiquitin ligase, E3alpha, suppressed most of the increased ubiquitin conjugation in the muscle extracts from tumor-bearing and septic rats. These inhibitors also suppressed ubiquitination in normal extracts toward levels in hypothyroid extracts, which showed little E3alpha-dependent ubiquitination. Thus, the inhibitors eliminated most of the differences in ubiquitination under these different pathological conditions. Moreover, 125I-lysozyme, a model N-end rule substrate, was ubiquitinated more rapidly in extracts from tumor-bearing and septic rats, and more slowly in those from hypothyroid rats, than in controls. Thus, the rate of ubiquitin conjugation increases in atrophying muscles, and these hormone- and cytokine-dependent responses are in large part due to activation of the N-end rule pathway.

  4. Inhibition of the metastatic spread and growth of B16-BL6 murine melanoma by a synthetic matrix metalloproteinase inhibitor.

    Science.gov (United States)

    Chirivi, R G; Garofalo, A; Crimmin, M J; Bawden, L J; Stoppacciaro, A; Brown, P D; Giavazzi, R

    1994-08-01

    The synthetic matrix metalloproteinase inhibitor batimastat was tested for its ability to inhibit growth and metastatic spread of the B16-BL6 murine melanoma in syngeneic C57BL/6N mice. Intraperitoneal administration of batimastat resulted in a significant inhibition in the number of lung colonies produced by B16-BL6 cells injected i.v. The effect of batimastat on spontaneous metastases was examined in mice inoculated in the hind footpad with B16-BL6 melanoma. The primary tumor was removed surgically after 26-28 days. Batimastat was administered twice a day from day 14 to day 28 (pre-surgery) or from day 26 to day 44 (post-surgery). With both protocols, the median number of lung metastases was not significantly affected, but there was a significant reduction in the weight of the metastases. Finally, the effect of batimastat was examined on s.c. growth of B16-BL6 melanoma. Batimastat administered daily, starting at day of tumor transplantation, resulted in a significant growth delay, whereas treatment starting at advanced stage tumor only reduced tumor growth marginally. Our results indicate that a matrix metalloproteinase inhibitor can not only prevent the colonization of secondary organs by B16-BL6 cells but also limit the growth of solid tumors.

  5. Screening of E. coli β-clamp Inhibitors Revealed that Few Inhibit Helicobacter pylori More Effectively: Structural and Functional Characterization

    Directory of Open Access Journals (Sweden)

    Preeti Pandey

    2018-01-01

    Full Text Available The characteristic of interaction with various enzymes and processivity-promoting nature during DNA replication makes β-clamp an important drug target. Helicobacter pylori (H. pylori have several unique features in DNA replication machinery that makes it different from other microorganisms. To find out whether difference in DNA replication proteins behavior accounts for any difference in drug response when compared to E. coli, in the present study, we have tested E. coli β-clamp inhibitor molecules against H. pylori β-clamp. Various approaches were used to test the binding of inhibitors to H. pylori β-clamp including docking, surface competition assay, complex structure determination, as well as antimicrobial assay. Out of five shortlisted inhibitor molecules on the basis of docking score, three molecules, 5-chloroisatin, carprofen, and 3,4-difluorobenzamide were co-crystallized with H. pylori β-clamp and the structures show that they bind at the protein-protein interaction site as expected. In vivo studies showed only two molecules, 5-chloroisatin, and 3,4-difluorobenzamide inhibited the growth of the pylori with MIC values in micro molar range, which is better than the inhibitory effect of the same drugs on E. coli. Therefore, the evaluation of such drugs against H. pylori may explore the possibility to use to generate species-specific pharmacophore for development of new drugs against H. pylori.

  6. Suppression of complement regulatory protein C1 inhibitor in vascular endothelial activation by inhibiting vascular cell adhesion molecule-1 action

    International Nuclear Information System (INIS)

    Zhang, Haimou; Qin, Gangjian; Liang, Gang; Li, Jinan; Chiu, Isaac; Barrington, Robert A.; Liu, Dongxu

    2007-01-01

    Increased expression of adhesion molecules by activated endothelium is a critical feature of vascular inflammation associated with the several diseases such as endotoxin shock and sepsis/septic shock. Our data demonstrated complement regulatory protein C1 inhibitor (C1INH) prevents endothelial cell injury. We hypothesized that C1INH has the ability of an anti-endothelial activation associated with suppression of expression of adhesion molecule(s). C1INH blocked leukocyte adhesion to endothelial cell monolayer in both static assay and flow conditions. In inflammatory condition, C1INH reduced vascular cell adhesion molecule (VCAM-1) expression associated with its cytoplasmic mRNA destabilization and nuclear transcription level. Studies exploring the underlying mechanism of C1INH-mediated suppression in VCAM-1 expression were related to reduction of NF-κB activation and nuclear translocation in an IκBα-dependent manner. The inhibitory effects were associated with reduction of inhibitor IκB kinase activity and stabilization of the NF-κB inhibitor IκB. These findings indicate a novel role for C1INH in inhibition of vascular endothelial activation. These observations could provide the basis for new therapeutic application of C1INH to target inflammatory processes in different pathologic situations

  7. Screening of E. coli β-clamp Inhibitors Revealed that Few Inhibit Helicobacter pylori More Effectively: Structural and Functional Characterization.

    Science.gov (United States)

    Pandey, Preeti; Verma, Vijay; Dhar, Suman Kumar; Gourinath, Samudrala

    2018-01-11

    The characteristic of interaction with various enzymes and processivity-promoting nature during DNA replication makes β-clamp an important drug target. Helicobacter pylori ( H. pylori ) have several unique features in DNA replication machinery that makes it different from other microorganisms. To find out whether difference in DNA replication proteins behavior accounts for any difference in drug response when compared to E. coli , in the present study, we have tested E. coli β-clamp inhibitor molecules against H. pylori β-clamp. Various approaches were used to test the binding of inhibitors to H. pylori β-clamp including docking, surface competition assay, complex structure determination, as well as antimicrobial assay. Out of five shortlisted inhibitor molecules on the basis of docking score, three molecules, 5-chloroisatin, carprofen, and 3,4-difluorobenzamide were co-crystallized with H. pylori β-clamp and the structures show that they bind at the protein-protein interaction site as expected. In vivo studies showed only two molecules, 5-chloroisatin, and 3,4-difluorobenzamide inhibited the growth of the pylori with MIC values in micro molar range, which is better than the inhibitory effect of the same drugs on E. coli . Therefore, the evaluation of such drugs against H. pylori may explore the possibility to use to generate species-specific pharmacophore for development of new drugs against H. pylori .

  8. When ubiquitin meets NF-κB: a trove for anti-cancer drug development.

    Science.gov (United States)

    Wu, Zhao-Hui; Shi, Yuling

    2013-01-01

    During the last two decades, the studies on ubiquitination in regulating transcription factor NF-κB activation have elucidated the expanding role of ubiquitination in modulating cellular events by non-proteolytic mechanisms, as well as by proteasomal degradation. The significance of ubiquitination has also been recognized in regulating gene transcription, epigenetic modifications, kinase activation, DNA repair and subcellular translocation. This progress has been translated into novel strategies for developing anti-cancer therapeutics, exemplified by the success of the first FDA-approved proteasome inhibitor drug Bortezomib. Here we discuss the current understanding of the ubiquitin-proteasome system and how it is involved in regulating NF-κB signaling pathways in response to a variety of stimuli. We also focus on the recent progress of anti-cancer drug development targeting various steps of ubiquitination process, and the potential of these drugs in cancer treatment as related to their impact on NF-κB activation.

  9. The ubiquitin ligase ASB4 promotes trophoblast differentiation through the degradation of ID2.

    Directory of Open Access Journals (Sweden)

    W H Davin Townley-Tilson

    Full Text Available Vascularization of the placenta is a critical developmental process that ensures fetal viability. Although the vascular health of the placenta affects both maternal and fetal well being, relatively little is known about the early stages of placental vascular development. The ubiquitin ligase Ankyrin repeat, SOCS box-containing 4 (ASB4 promotes embryonic stem cell differentiation to vascular lineages and is highly expressed early in placental development. The transcriptional regulator Inhibitor of DNA binding 2 (ID2 negatively regulates vascular differentiation during development and is a target of many ubiquitin ligases. Due to their overlapping spatiotemporal expression pattern in the placenta and contrasting effects on vascular differentiation, we investigated whether ASB4 regulates ID2 through its ligase activity in the placenta and whether this activity mediates vascular differentiation. In mouse placentas, ASB4 expression is restricted to a subset of cells that express both stem cell and endothelial markers. Placentas that lack Asb4 display immature vascular patterning and retain expression of placental progenitor markers, including ID2 expression. Using JAR placental cells, we determined that ASB4 ubiquitinates and represses ID2 expression in a proteasome-dependent fashion. Expression of ASB4 in JAR cells and primary isolated trophoblast stem cells promotes the expression of differentiation markers. In functional endothelial co-culture assays, JAR cells ectopically expressing ASB4 increased endothelial cell turnover and stabilized endothelial tube formation, both of which are hallmarks of vascular differentiation within the placenta. Co-transfection of a degradation-resistant Id2 mutant with Asb4 inhibits both differentiation and functional responses. Lastly, deletion of Asb4 in mice induces a pathology that phenocopies human pre-eclampsia, including hypertension and proteinuria in late-stage pregnant females. These results indicate that

  10. Application of calculated NMR parameters, aromaticity indices and wavefunction properties for evaluation of corrosion inhibition efficiency of pyrazine inhibitors

    Science.gov (United States)

    Behzadi, Hadi; Manzetti, Sergio; Dargahi, Maryam; Roonasi, Payman; Khalilnia, Zahra

    2018-01-01

    In light of the importance of developing novel corrosion inhibitors, a series of quantum chemical calculations were carried out to evaluate 15N chemical shielding CS tensors as well as aromaticity indexes including NICS, HOMA, FLU, and PDI of three pyrazine derivatives, 2-methylpyrazine (MP), 2-aminopyrazine (AP) and 2-amino-5-bromopyrazine (ABP). The NICS parameters have been shown in previous studies to be paramount to the prediction of anti-corrosion properties, and have been combined here with HOMA, FLU and PDI and detailed wavefunction analysis to determine the effects from bromination and methylation on pyrazine. The results show that the electron density around the nitrogens, represented by CS tensors, can be good indicators of anti-corrosion efficiency. Additionally, the NICS, FLU and PDI, as aromaticity indicators of molecule, are well correlated with experimental corrosion inhibition efficiencies of the studied inhibitors. Bader sampling and detailed wavefunction analysis shows that the major effects from bromination on the pyrazine derivatives affect the Laplacian of the electron density of the ring, delocalizing the aromatic electrons of the carbon atoms into lone pairs and increasing polarization of the Laplacian values. This feature is well agreement with empirical studies, which show that ABP is the most efficient anti-corrosion compound followed by AP and MP, a property which can be attributed and predicted by derivation of the Laplacian of the electron density of the ring nuclei. This study shows the importance of devising DFT methods for development of new corrosion inhibitors, and the strength of electronic and nuclear analysis, and depicts most importantly how corrosion inhibitors composed of aromatic moieties may be modified to increase anti-corrosive properties.

  11. Functional interchangeability of late domains, late domain cofactors and ubiquitin in viral budding.

    Directory of Open Access Journals (Sweden)

    Maria Zhadina

    2010-10-01

    Full Text Available The membrane scission event that separates nascent enveloped virions from host cell membranes often requires the ESCRT pathway, which can be engaged through the action of peptide motifs, termed late (L- domains, in viral proteins. Viral PTAP and YPDL-like L-domains bind directly to the ESCRT-I and ALIX components of the ESCRT pathway, while PPxY motifs bind Nedd4-like, HECT-domain containing, ubiquitin ligases (e.g. WWP1. It has been unclear precisely how ubiquitin ligase recruitment ultimately leads to particle release. Here, using a lysine-free viral Gag protein derived from the prototypic foamy virus (PFV, where attachment of ubiquitin to Gag can be controlled, we show that several different HECT domains can replace the WWP1 HECT domain in chimeric ubiquitin ligases and drive budding. Moreover, artificial recruitment of isolated HECT domains to Gag is sufficient to stimulate budding. Conversely, the HECT domain becomes dispensable if the other domains of WWP1 are directly fused to an ESCRT-1 protein. In each case where budding is driven by a HECT domain, its catalytic activity is essential, but Gag ubiquitination is dispensable, suggesting that ubiquitin ligation to trans-acting proteins drives budding. Paradoxically, however, we also demonstrate that direct fusion of a ubiquitin moiety to the C-terminus of PFV Gag can also promote budding, suggesting that ubiquitination of Gag can substitute for ubiquitination of trans-acting proteins. Depletion of Tsg101 and ALIX inhibits budding that is dependent on ubiquitin that is fused to Gag, or ligated to trans-acting proteins through the action of a PPxY motif. These studies underscore the flexibility in the ways that the ESCRT pathway can be engaged, and suggest a model in which the identity of the protein to which ubiquitin is attached is not critical for subsequent recruitment of ubiquitin-binding components of the ESCRT pathway and viral budding to proceed.

  12. Effects of Pharmacological Inhibition and Genetic Deficiency of Plasminogen Activator Inhibitor-1 in Radiation-Induced Intestinal Injury

    International Nuclear Information System (INIS)

    Abderrahmani, Rym; Francois, Agnes; Buard, Valerie; Benderitter, Marc; Sabourin, Jean-Christophe; Crandall, David L.; Milliat, Fabien

    2009-01-01

    Purpose: To investigate effects of plasminogen activator inhibitor 1 (PAI-1) genetic deficiency and pharmacological PAI-1 inhibition with PAI-039 in a mouse model of radiation-induced enteropathy. Methods and Materials: Wild-type (Wt) and PAI-1 -/- knockout mice received a single dose of 19 Gy to an exteriorized localized intestinal segment. Sham and irradiated Wt mice were treated orally with 1 mg/g of PAI-039. Histological modifications were quantified using a radiation injury score. Moreover, intestinal gene expression was monitored by real-time PCR. Results: At 3 days after irradiation, PAI-039 abolished the radiation-induced increase in the plasma active form of PAI-1 and limited the radiation-induced gene expression of transforming growth factor β1 (TGF-β1), CTGF, PAI-1, and COL1A2. Moreover, PAI-039 conferred temporary protection against early lethality. PAI-039 treatment limited the radiation-induced increase of CTGF and PAI-1 at 2 weeks after irradiation but had no effect at 6 weeks. Radiation injuries were less severe in PAI-1 -/- mice than in Wt mice, and despite the beneficial effect, 3 days after irradiation, PAI-039 had no effects on microscopic radiation injuries compared to untreated Wt mice. Conclusions: A genetic deficiency of PAI-1 is associated with amelioration of late radiation enteropathy. Pharmacological inhibition of PAI-1 by PAI-039 positively impacts the early, acute phase increase in plasma PAI-1 and the associated radiation-induced gene expression of inflammatory/extracellular matrix proteins. Since PAI-039 has been shown to inhibit the active form of PAI-1, as opposed to the complete loss of PAI-1 in the knockout animals, these data suggest that a PAI-1 inhibitor could be beneficial in treating radiation-induced tissue injury in acute settings where PAI-1 is elevated.

  13. pH-dependent antitumor activity of proton pump inhibitors against human melanoma is mediated by inhibition of tumor acidity.

    Science.gov (United States)

    De Milito, Angelo; Canese, Rossella; Marino, Maria Lucia; Borghi, Martina; Iero, Manuela; Villa, Antonello; Venturi, Giulietta; Lozupone, Francesco; Iessi, Elisabetta; Logozzi, Mariantonia; Della Mina, Pamela; Santinami, Mario; Rodolfo, Monica; Podo, Franca; Rivoltini, Licia; Fais, Stefano

    2010-07-01

    Metastatic melanoma is associated with poor prognosis and still limited therapeutic options. An innovative treatment approach for this disease is represented by targeting acidosis, a feature characterizing tumor microenvironment and playing an important role in cancer malignancy. Proton pump inhibitors (PPI), such as esomeprazole (ESOM) are prodrugs functionally activated by acidic environment, fostering pH neutralization by inhibiting proton extrusion. We used human melanoma cell lines and xeno-transplated SCID mice to provide preclinical evidence of ESOM antineoplastic activity. Human melanoma cell lines, characterized by different mutation and signaling profiles, were treated with ESOM in different pH conditions and evaluated for proliferation, viability and cell death. SCID mice engrafted with human melanoma were used to study ESOM administration effects on tumor growth and tumor pH by magnetic resonance spectroscopy (MRS). ESOM inhibited proliferation of melanoma cells in vitro and induced a cytotoxicity strongly boosted by low pH culture conditions. ESOM-induced tumor cell death occurred via rapid intracellular acidification and activation of several caspases. Inhibition of caspases activity by pan-caspase inhibitor z-vad-fmk completely abrogated the ESOM-induced cell death. ESOM administration (2.5 mg kg(-1)) to SCID mice engrafted with human melanoma reduced tumor growth, consistent with decrease of proliferating cells and clear reduction of pH gradients in tumor tissue. Moreover, systemic ESOM administration dramatically increased survival of human melanoma-bearing animals, in absence of any relevant toxicity. These data show preclinical evidence supporting the use of PPI as novel therapeutic strategy for melanoma, providing the proof of concept that PPI target human melanoma modifying tumor pH gradients.

  14. Inhibiting AMPylation: a novel screen to identify the first small molecule inhibitors of protein AMPylation.

    Science.gov (United States)

    Lewallen, Daniel M; Sreelatha, Anju; Dharmarajan, Venkatasubramanian; Madoux, Franck; Chase, Peter; Griffin, Patrick R; Orth, Kim; Hodder, Peter; Thompson, Paul R

    2014-02-21

    Enzymatic transfer of the AMP portion of ATP to substrate proteins has recently been described as an essential mechanism of bacterial infection for several pathogens. The first AMPylator to be discovered, VopS from Vibrio parahemolyticus, catalyzes the transfer of AMP onto the host GTPases Cdc42 and Rac1. Modification of these proteins disrupts downstream signaling events, contributing to cell rounding and apoptosis, and recent studies have suggested that blocking AMPylation may be an effective route to stop infection. To date, however, no small molecule inhibitors have been discovered for any of the AMPylators. Therefore, we developed a fluorescence-polarization-based high-throughput screening assay and used it to discover the first inhibitors of protein AMPylation. Herein we report the discovery of the first small molecule VopS inhibitors (e.g., calmidazolium, GW7647, and MK886) with Ki's ranging from 6 to 50 μM and upward of 30-fold selectivity versus HYPE, the only known human AMPylator.

  15. Triterpenoids from Ganoderma lucidum inhibit the activation of EBV antigens as telomerase inhibitors.

    Science.gov (United States)

    Zheng, Dong-Shu; Chen, Liang-Shu

    2017-10-01

    Nasopharyngeal carcinoma (NPC) is a malignant disease that threatens the health of humans. To find effective agents for the inhibition of Epstein-Barr virus (EBV) infection, which is associated with NPC, a phytochemical investigation of Ganoderma lucidum was carried out in the present study. Five triterpenoids were identified, including ganoderic acid A (compound 1), ganoderic acid B (compound 2), ganoderol B (compound 3), ganodermanontriol (compound 4), and ganodermanondiol (compound 5), on the basis of spectroscopic analysis. An inhibition of EBV antigens activation assay was implemented to elucidate the triterpenoids from G. lucidum and potentially prevent NPC. All the triterpenoids showed significant inhibitory effects on both EBV EA and CA activation at 16 nmol. At 3.2 nmol, all the compounds moderately inhibited the activation of the two antigens. The activity of telomerase was inhibited by these triterpenoids at 10 µM. Molecular docking demonstrated that compound 1 was able to inhibit telomerase as a ligand. In addition, the physicochemical properties of these compounds were calculated to elucidate their drug-like properties. These results provided evidence for the application of these triterpenoids and whole G. lucidum in the treatment of NPC.

  16. Inhibitors of poly (ADP-ribose) synthesis inhibit the two types of repair of potentially lethal damage

    International Nuclear Information System (INIS)

    Utsumi, Hiroshi; Elkind, M.M.

    1994-01-01

    The purpose of this study was to examine whether 3-amino-benzamide (3ABA), an inhibitor of poly (ADP-ribose) synthesis, inhibits the two types of potentially lethal damage (PLD) repair, termed slow and fast. The fast-type PLD repair was measured by the decrease in survival of V79 Chinese hamster cells by postirradiation treatment with 3ABA. The slow-type PLD repair was measured by the increase in survival by posttreatment with conditioned medium (CM), which became conditioned by growing a crowed culture of cells and supports the slow-type PLD repair. Up to 1 mM 3-ABA inhibited the slow type repair; at doses of 2 mM and above, it inhibited the fast type of PLD repair. There are quantitative differences in cellular effects of 3ABA dependent on concentration. Poly (ADP-ribose) appears to play an important role in the PLD repairs and has little effect on the repair of sublethal damage. 10 refs., 2 figs

  17. SUMO-targeted ubiquitin ligases.

    Science.gov (United States)

    Sriramachandran, Annie M; Dohmen, R Jürgen

    2014-01-01

    Covalent posttranslational modification with SUMO (small ubiquitin-related modifier) modulates functions of a wide range of proteins in eukaryotic cells. Sumoylation affects the activity, interaction properties, subcellular localization and the stability of its substrate proteins. The recent discovery of a novel class of ubiquitin ligases (E3), termed ULS (E3-S) or STUbL, that recognize sumoylated proteins, links SUMO modification to the ubiquitin/proteasome system. Here we review recent insights into the properties and function of these ligases and their roles in regulating sumoylated proteins. This article is part of a Special Issue entitled: Ubiquitin-Proteasome System. Guest Editors: Thomas Sommer and Dieter H. Wolf. © 2013. Published by Elsevier B.V. All rights reserved.

  18. A broad range quorum sensing inhibitor working through sRNA inhibition

    DEFF Research Database (Denmark)

    Jakobsen, Tim H.; Warming, Anders N.; Vejborg, Rebecca M.

    2017-01-01

    that the repressing effect of ajoene on quorum sensing occurs by inhibition of small regulatory RNAs (sRNA) in P. aeruginosa as well as in Staphylococcus aureus, another important human pathogen that employs quorum sensing to control virulence gene expression. Using various reporter constructs, we found that ajoene......-spectrum compounds transcending the Gram negative-positive borderline....

  19. Checkpoint Inhibition: Programmed Cell Death 1 and Programmed Cell Death 1 Ligand Inhibitors in Hodgkin Lymphoma.

    Science.gov (United States)

    Villasboas, Jose Caetano; Ansell, Stephen

    2016-01-01

    Hodgkin lymphoma (HL) is a lymphoid malignancy characterized by a reactive immune infiltrate surrounding relatively few malignant cells. In this scenario, active immune evasion seems to play a central role in allowing tumor progression. Immune checkpoint inhibitor pathways are normal mechanisms of T-cell regulation that suppress immune effector function following an antigenic challenge. Hodgkin lymphoma cells are able to escape immune surveillance by co-opting these mechanisms. The programmed cell death 1 (PD-1) pathway in particular is exploited in HL as the malignant Hodgkin and Reed-Sternberg cells express on their surface cognate ligands (PD-L1/L2) for the PD-1 receptor and thereby dampen the T-cell-mediated antitumoral response. Monoclonal antibodies that interact with and disrupt the PD-1:PD-L1/L2 axis have now been developed and tested in early-phase clinical trials in patients with advanced HL with encouraging results. The remarkable clinical activity of PD-1 inhibitors in HL highlights the importance of immune checkpoint pathways as therapeutic targets in HL. In this review, we discuss the rationale for targeting PD-1 and PD-L1 in the treatment of HL. We will evaluate the published clinical data on the different agents and highlight the safety profile of this class of agents. We discuss the available evidence on the use of biomarkers as predictors of response to checkpoint blockade and summarize the areas under active investigation in the use of PD-1/PD-L1 inhibitors for the treatment of HL.

  20. Inhibition of hydrogen sulfide generation from disposed gypsum drywall using chemical inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Xu Qiyong [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); School of Environment and Energy, Shenzhen Graduate School of Peking University, 518055, (China); Townsend, Timothy, E-mail: ttown@ufl.edu [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States); Bitton, Gabriel [Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL 32611 (United States)

    2011-07-15

    Disposal of gypsum drywall in landfills has been demonstrated to elevate hydrogen sulfide (H{sub 2}S) concentrations in landfill gas, a problem with respect to odor, worker safety, and deleterious effect on gas-to-energy systems. Since H{sub 2}S production in landfills results from biological activity, the concept of inhibiting H{sub 2}S production through the application of chemical agents to drywall during disposal was studied. Three possible inhibition agents - sodium molybdate (Na{sub 2}MoO{sub 4}), ferric chloride (FeCl{sub 3}), and hydrated lime (Ca(OH){sub 2}) - were evaluated using flask and column experiments. All three agents inhibited H{sub 2}S generation, with Na{sub 2}MoO{sub 4} reducing H{sub 2}S generation by interrupting the biological sulfate reduction process and Ca(OH){sub 2} providing an unfavorable pH for biological growth. Although FeCl{sub 3} was intended to provide an electron acceptor for a competing group of bacteria, the mechanism found responsible for inhibiting H{sub 2}S production in the column experiment was a reduction in pH. Application of both Na{sub 2}MoO{sub 4} and FeCl{sub 3} inhibited H{sub 2}S generation over a long period (over 180 days), but the impact of Ca(OH){sub 2} decreased with time as the alkalinity it contributed was neutralized by the generated H{sub 2}S. Practical application and potential environmental implications need additional exploration.

  1. The Ca2+ pump inhibitor, thapsigargin, inhibits root gravitropism in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    DANIELA C URBINA

    2006-01-01

    Full Text Available Thapsigargin, a specific inhibitor of most animal intracellular SERCA-type Ca2+ pumps present in the sarcoplasmic/endoplasmic reticulum, was originally isolated from the roots of the Mediterranean plant Thapsia gargancia L. Here, we demonstrate that this root-derived compound is capable of altering root gravitropism in Arabidopsis thaliana. Thapsigargin concentrations as low as 0.1 µM alter root gravitropism whereas under similar conditions cyclopiazonic acid does not. Furthermore, a fluorescently conjugated thapsigargin (BODIPY FL thapsigargin suggests that target sites for thapsigargin are located in intracellular organelles in the root distal elongation zone and the root cap, regions known to regulate root gravitropism

  2. FANCL ubiquitinates β-catenin and enhances its nuclear function.

    Science.gov (United States)

    Dao, Kim-Hien T; Rotelli, Michael D; Petersen, Curtis L; Kaech, Stefanie; Nelson, Whitney D; Yates, Jane E; Hanlon Newell, Amy E; Olson, Susan B; Druker, Brian J; Bagby, Grover C

    2012-07-12

    Bone marrow failure is a nearly universal complication of Fanconi anemia. The proteins encoded by FANC genes are involved in DNA damage responses through the formation of a multisubunit nuclear complex that facilitates the E3 ubiquitin ligase activity of FANCL. However, it is not known whether loss of E3 ubiquitin ligase activity accounts for the hematopoietic stem cell defects characteristic of Fanconi anemia. Here we provide evidence that FANCL increases the activity and expression of β-catenin, a key pluripotency factor in hematopoietic stem cells. We show that FANCL ubiquitinates β-catenin with atypical ubiquitin chain extension known to have nonproteolytic functions. Specifically, β-catenin modified with lysine-11 ubiquitin chain extension efficiently activates a lymphocyte enhancer-binding factor-T cell factor reporter. We also show that FANCL-deficient cells display diminished capacity to activate β-catenin leading to reduced transcription of Wnt-responsive targets c-Myc and Cyclin D1. Suppression of FANCL expression in normal human CD34(+) stem and progenitor cells results in fewer β-catenin active cells and inhibits expansion of multilineage progenitors. Together, these results suggest that diminished Wnt/β-catenin signaling may be an underlying molecular defect in FANCL-deficient hematopoietic stem cells leading to their accelerated loss.

  3. HIV protease inhibitors disrupt lipid metabolism by activating endoplasmic reticulum stress and inhibiting autophagy activity in adipocytes.

    Directory of Open Access Journals (Sweden)

    Beth S Zha

    Full Text Available HIV protease inhibitors (PI are core components of Highly Active Antiretroviral Therapy (HAART, the most effective treatment for HIV infection currently available. However, HIV PIs have now been linked to lipodystrophy and dyslipidemia, which are major risk factors for cardiovascular disease and metabolic syndrome. Our previous studies have shown that HIV PIs activate endoplasmic reticulum (ER stress and disrupt lipid metabolism in hepatocytes and macrophages. Yet, little is known on how HIV PIs disrupt lipid metabolism in adipocytes, a major cell type involved in the pathogenesis of metabolic syndrome.Cultured and primary mouse adipocytes and human adipocytes were used to examine the effect of frequently used HIV PIs in the clinic, lopinavir/ritonavir, on adipocyte differentiation and further identify the underlying molecular mechanism of HIV PI-induced dysregulation of lipid metabolism in adipocytes. The results indicated that lopinavir alone or in combination with ritonavir, significantly activated the ER stress response, inhibited cell differentiation, and induced cell apoptosis in adipocytes. In addition, HIV PI-induced ER stress was closely linked to inhibition of autophagy activity. We also identified through the use of primary adipocytes of CHOP(-/- mice that CHOP, the major transcriptional factor of the ER stress signaling pathway, is involved in lopinavir/ritonavir-induced inhibition of cell differentiation in adipocytes. In addition, lopinavir/ritonavir-induced ER stress appears to be associated with inhibition of autophagy activity in adipocytes.Activation of ER stress and impairment of autophagy activity are involved in HIV PI-induced dysregulation of lipid metabolism in adipocytes. The key components of ER stress and autophagy signaling pathways are potential therapeutic targets for HIV PI-induced metabolic side effects in HIV patients.

  4. The multi-targeted kinase inhibitor sorafenib inhibits enterovirus 71 replication by regulating IRES-dependent translation of viral proteins.

    Science.gov (United States)

    Gao, Meng; Duan, Hao; Liu, Jing; Zhang, Hao; Wang, Xin; Zhu, Meng; Guo, Jitao; Zhao, Zhenlong; Meng, Lirong; Peng, Yihong

    2014-06-01

    The activation of ERK and p38 signal cascade in host cells has been demonstrated to be essential for picornavirus enterovirus 71 (EV71) replication and up-regulation of virus-induced cyclooxygenase-2 (COX-2)/prostaglandins E2 (PGE2) expression. The aim of this study was to examine the effects of sorafenib, a clinically approved anti-cancer multi-targeted kinase inhibitor, on the propagation and pathogenesis of EV71, with a view to its possible mechanism and potential use in the design of therapy regimes for Hand foot and mouth disease (HFMD) patients with life threatening neurological complications. In this study, non-toxic concentrations of sorafenib were shown to inhibit the yield of infectious progeny EV71 (clinical BC08 strain) by about 90% in three different cell types. A similar inhibitory effect of sorafenib was observed on the synthesis of both viral genomic RNA and the VP1 protein. Interestingly, sorafenib exerted obvious inhibition of the EV71 internal ribosomal entry site (IRES)-mediated translation, the first step in picornavirus replication, by linking it to a firefly luciferase reporter gene. Sorafenib was also able to prevent both EV71-induced CPE and the activation of ERK and p38, which contributes to up-regulation COX-2/PGE2 expression induced by the virus. Overall, this study shows that sorafenib strongly inhibits EV71 replication at least in part by regulating viral IRES-dependent translation of viral proteins, indicating a novel potential strategy for the treatment of HFMD patients with severe neurological complications. To our knowledge, this is the first report that investigates the mechanism by which sorafenib inhibits EV71 replication. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Inhibition of G-Protein-Activated Inwardly Rectifying K+ Channels by the Selective Norepinephrine Reuptake Inhibitors Atomoxetine and Reboxetine

    Science.gov (United States)

    Kobayashi, Toru; Washiyama, Kazuo; Ikeda, Kazutaka

    2010-01-01

    Atomoxetine and reboxetine are commonly used as selective norepinephrine reuptake inhibitors (NRIs) for the treatment of attention-deficit/hyperactivity disorder and depression, respectively. Furthermore, recent studies have suggested that NRIs may be useful for the treatment of several other psychiatric disorders. However, the molecular mechanisms underlying the various effects of NRIs have not yet been sufficiently clarified. G-protein-activated inwardly rectifying K+ (GIRK or Kir3) channels have an important function in regulating neuronal excitability and heart rate, and GIRK channel modulation has been suggested to be a potential treatment for several neuropsychiatric disorders and cardiac arrhythmias. In this study, we investigated the effects of atomoxetine and reboxetine on GIRK channels using the Xenopus oocyte expression assay. In oocytes injected with mRNA for GIRK1/GIRK2, GIRK2, or GIRK1/GIRK4 subunits, extracellular application of atomoxetine or reboxetine reversibly reduced GIRK currents. The inhibitory effects were concentration-dependent, but voltage-independent, and time-independent during each voltage pulse. However, Kir1.1 and Kir2.1 channels were insensitive to atomoxetine and reboxetine. Atomoxetine and reboxetine also inhibited GIRK currents induced by activation of cloned A1 adenosine receptors or by intracellularly applied GTPγS, a nonhydrolyzable GTP analogue. Furthermore, the GIRK currents induced by ethanol were concentration-dependently inhibited by extracellularly applied atomoxetine but not by intracellularly applied atomoxetine. The present results suggest that atomoxetine and reboxetine inhibit brain- and cardiac-type GIRK channels, revealing a novel characteristic of clinically used NRIs. GIRK channel inhibition may contribute to some of the therapeutic effects of NRIs and adverse side effects related to nervous system and heart function. PMID:20393461

  6. Radicicol, a heat shock protein 90 inhibitor, inhibits differentiation and adipogenesis in 3T3-L1 preadipocytes

    Energy Technology Data Exchange (ETDEWEB)

    He, Yonghan [Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, 157 Baojian Road, Harbin 150081 (China); Aquatic and Crop Resource Development, Life Sciences Branch, National Research Council Canada, Charlottetown, PE, Canada C1A 4P3 (Canada); State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223 (China); Li, Ying [Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, 157 Baojian Road, Harbin 150081 (China); Zhang, Shuocheng [Aquatic and Crop Resource Development, Life Sciences Branch, National Research Council Canada, Charlottetown, PE, Canada C1A 4P3 (Canada); Perry, Ben [Aquatic and Crop Resource Development, Life Sciences Branch, National Research Council Canada, Charlottetown, PE, Canada C1A 4P3 (Canada); Department of Biomedical Sciences, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE, Canada C1A 4P3 (Canada); Zhao, Tiantian [Aquatic and Crop Resource Development, Life Sciences Branch, National Research Council Canada, Charlottetown, PE, Canada C1A 4P3 (Canada); Department of Psychology, University of Toronto, 1265 Military Trail, Toronto, ON, Canada M1C 1A4 (Canada); Wang, Yanwen, E-mail: yanwen.wang@nrc.ca [Aquatic and Crop Resource Development, Life Sciences Branch, National Research Council Canada, Charlottetown, PE, Canada C1A 4P3 (Canada); Department of Biomedical Sciences, University of Prince Edward Island, 550 University Avenue, Charlottetown, PE, Canada C1A 4P3 (Canada); Sun, Changhao, E-mail: sun2002changhao@yahoo.com [Department of Nutrition and Food Hygiene, Public Health College, Harbin Medical University, 157 Baojian Road, Harbin 150081 (China)

    2013-06-28

    Highlights: •Radicicol suppressed intracellular fat accumulation in 3T3-L1 adipocytes. •Radicicol inhibited the expression of FAS and FABP4. •Radicicol blocked cell cycle at the G1-S phase during cell differentiation. •Radicicol inhibited the PDK1/Akt pathway in adipocyte differentiation. -- Abstract: Heat shock protein 90 (Hsp90) is involved in various cellular processes, such as cell proliferation, differentiation and apoptosis. As adipocyte differentiation plays a critical role in obesity development, the present study investigated the effect of an Hsp90 inhibitor radicicol on the differentiation of 3T3-L1 preadipocytes and potential mechanisms. The cells were treated with different concentrations of radicicol during the first 8 days of cell differentiation. Adipogenesis, the expression of adipogenic transcriptional factors, differentiation makers and cell cycle were determined. It was found that radicicol dose-dependently decreased intracellular fat accumulation through down-regulating the expression of peroxisome proliferator-activated receptor γ (PPAR{sub γ}) and CCAAT element binding protein α (C/EBP{sub α}), fatty acid synthase (FAS) and fatty acid-binding protein 4 (FABP4). Flow cytometry analysis revealed that radicicol blocked cell cycle at G1-S phase. Radicicol redcued the phosphorylation of Akt while showing no effect on β-catenin expression. Radicicol decreased the phosphorylation of phosphoinositide-dependent kinase 1 (PDK1). The results suggest that radicicol inhibited 3T3-L1 preadipocyte differentiation through affecting the PDK1/Akt pathway and subsequent inhibition of mitotic clonal expansion and the expression/activity of adipogenic transcriptional factors and their downstream adipogenic proteins.

  7. Radicicol, a heat shock protein 90 inhibitor, inhibits differentiation and adipogenesis in 3T3-L1 preadipocytes

    International Nuclear Information System (INIS)

    He, Yonghan; Li, Ying; Zhang, Shuocheng; Perry, Ben; Zhao, Tiantian; Wang, Yanwen; Sun, Changhao

    2013-01-01

    Highlights: •Radicicol suppressed intracellular fat accumulation in 3T3-L1 adipocytes. •Radicicol inhibited the expression of FAS and FABP4. •Radicicol blocked cell cycle at the G1-S phase during cell differentiation. •Radicicol inhibited the PDK1/Akt pathway in adipocyte differentiation. -- Abstract: Heat shock protein 90 (Hsp90) is involved in various cellular processes, such as cell proliferation, differentiation and apoptosis. As adipocyte differentiation plays a critical role in obesity development, the present study investigated the effect of an Hsp90 inhibitor radicicol on the differentiation of 3T3-L1 preadipocytes and potential mechanisms. The cells were treated with different concentrations of radicicol during the first 8 days of cell differentiation. Adipogenesis, the expression of adipogenic transcriptional factors, differentiation makers and cell cycle were determined. It was found that radicicol dose-dependently decreased intracellular fat accumulation through down-regulating the expression of peroxisome proliferator-activated receptor γ (PPAR γ ) and CCAAT element binding protein α (C/EBP α ), fatty acid synthase (FAS) and fatty acid-binding protein 4 (FABP4). Flow cytometry analysis revealed that radicicol blocked cell cycle at G1-S phase. Radicicol redcued the phosphorylation of Akt while showing no effect on β-catenin expression. Radicicol decreased the phosphorylation of phosphoinositide-dependent kinase 1 (PDK1). The results suggest that radicicol inhibited 3T3-L1 preadipocyte differentiation through affecting the PDK1/Akt pathway and subsequent inhibition of mitotic clonal expansion and the expression/activity of adipogenic transcriptional factors and their downstream adipogenic proteins

  8. Peptide Inhibitor of Complement C1 (PIC1 Rapidly Inhibits Complement Activation after Intravascular Injection in Rats.

    Directory of Open Access Journals (Sweden)

    Julia A Sharp

    Full Text Available The complement system has been increasingly recognized to play a pivotal role in a variety of inflammatory and autoimmune diseases. Consequently, therapeutic modulators of the classical, lectin and alternative pathways of the complement system are currently in pre-clinical and clinical development. Our laboratory has identified a peptide that specifically inhibits the classical and lectin pathways of complement and is referred to as Peptide Inhibitor of Complement C1 (PIC1. In this study, we determined that the lead PIC1 variant demonstrates a salt-dependent binding to C1q, the initiator molecule of the classical pathway. Additionally, this peptide bound to the lectin pathway initiator molecule MBL as well as the ficolins H, M and L, suggesting a common mechanism of PIC1 inhibitory activity occurs via binding to the collagen-like tails of these collectin molecules. We further analyzed the effect of arginine and glutamic acid residue substitution on the complement inhibitory activity of our lead derivative in a hemolytic assay and found that the original sequence demonstrated superior inhibitory activity. To improve upon the solubility of the lead derivative, a pegylated, water soluble variant was developed, structurally characterized and demonstrated to inhibit complement activation in mouse plasma, as well as rat, non-human primate and human serum in vitro. After intravenous injection in rats, the pegylated derivative inhibited complement activation in the blood by 90% after 30 seconds, demonstrating extremely rapid function. Additionally, no adverse toxicological effects were observed in limited testing. Together these results show that PIC1 rapidly inhibits classical complement activation in vitro and in vivo and is functional for a variety of animal species, suggesting its utility in animal models of classical complement-mediated diseases.

  9. [Arginase inhibitor nor-NOHA induces apoptosis and inhibits invasion and migration of HepG2 cells].

    Science.gov (United States)

    Li, Xiangnan; Zhu, Fangyu; He, Yongsong; Luo, Fang

    2017-04-01

    Objective To investigate the cell inhibitory effect of arginase inhibitor nor-NOHA on HepG2 hepatocellular carcinoma cells and related mechanism. Methods CCK-8 assay was used to detect the cell proliferation and flow cytometry to detect the apoptosis of HepG2 cells treated with (0, 0.5, 1.0, 2.0, 3.0) ng/μL nor-NOHA. The protein levels of arginase 1 (Arg1), P53, matrix metalloproteinase-2 (MMP-2), E-cadherin (ECD) were determined by Western blotting. Real time quantitative PCR was employed to examine the changes in the mRNA level of inducible nitric oxide synthase (iNOS). Griess assay was used to measure the concentration of nitric oxide (NO) in HepG2 cells. Transwell TM assay and wound-healing assay were performed to evaluate the changes of the cell invasion and migration ability, respectively. Results nor-NOHA inhibited the proliferation and induced the apoptosis of HepG2 cells. It also decreased the expression levels of Arg1 and MMP-2, increased the expression levels of P53 and ECD as well as the production of NO; in addition, nor-NOHA inhibited the invasion and migration of HepG2 cells. Conclusion Nor-NOHA can induce cell apoptosis and inhibit the ability of invasion and migration of HepG2 cells by inhibiting Arg1, which is related with the increase of iNOS expression and the high concentration of NO.

  10. Experimental in vivo and in vitro treatment with a new histone deacetylase inhibitor belinostat inhibits the growth of pancreatic cancer

    International Nuclear Information System (INIS)

    Dovzhanskiy, Dmitriy I; Arnold, Stefanie M; Hackert, Thilo; Oehme, Ina; Witt, Olaf; Felix, Klaus; Giese, Nathalia; Werner, Jens

    2012-01-01

    Treatment options for pancreatic ductal adenocarcinoma (PDAC) are limited. Histone deacetylase inhibitors are a new and promising drug family with strong anticancer activity. The aim of this study was to examine the efficacy of in vitro and in vivo treatment with the novel pan-HDAC inhibitor belinostat on the growth of human PDAC cells. The proliferation of tumour cell lines (T3M4, AsPC-1 and Panc-1) was determined using an MTT assay. Apoptosis was analysed using flow cytometry. Furthermore, p21 Cip1/Waf1 and acetylated histone H4 (acH4) expression were confirmed by immunoblot analysis. The in vivo effect of belinostat was studied in a chimeric mouse model. Antitumoural activity was assessed by immunohistochemistry for Ki-67. Treatment with belinostat resulted in significant in vitro and in vivo growth inhibition of PDAC cells. This was associated with a dose-dependent induction of tumour cell apoptosis. The apoptotic effect of gemcitabine was further enhanced by belinostat. Moreover, treatment with belinostat increased expression of the cell cycle regulator p21 Cip1/Waf1 in Panc-1, and of acH4 in all cell lines tested. The reductions in xenograft tumour volumes were associated with inhibition of cell proliferation. Experimental treatment of human PDAC cells with belinostat is effective in vitro and in vivo and may enhance the efficacy of gemcitabine. A consecutive study of belinostat in pancreatic cancer patients alone, and in combination with gemcitabine, could further clarify these effects in the clinical setting

  11. A small molecule inhibitor of signal peptide peptidase inhibits Plasmodium development in the liver and decreases malaria severity.

    Directory of Open Access Journals (Sweden)

    Iana Parvanova

    Full Text Available The liver stage of Plasmodium's life cycle is the first, obligatory step in malaria infection. Decreasing the hepatic burden of Plasmodium infection decreases the severity of disease and constitutes a promising strategy for malaria prophylaxis. The efficacy of the gamma-secretase and signal peptide peptidase inhibitor LY411,575 in targeting Plasmodium liver stages was evaluated both in human hepatoma cell lines and in mouse primary hepatocytes. LY411,575 was found to prevent Plasmodium's normal development in the liver, with an IC(50 of approximately 80 nM, without affecting hepatocyte invasion by the parasite. In vivo results with a rodent model of malaria showed that LY411,575 decreases the parasite load in the liver and increases by 55% the resistance of mice to cerebral malaria, one of the most severe malaria-associated syndromes. Our data show that LY411,575 does not exert its effect via the Notch signaling pathway suggesting that it may interfere with Plasmodium development through an inhibition of the parasite's signal peptide peptidase. We therefore propose that selective signal peptide peptidase inhibitors could be potentially used for preventive treatment of malaria in humans.

  12. SNX-25a, a novel Hsp90 inhibitor, inhibited human cancer growth more potently than 17-AAG.

    Science.gov (United States)

    Wang, Shaoxiang; Wang, Xiao; Du, Zhan; Liu, Yuting; Huang, Dane; Zheng, Kai; Liu, Kaisheng; Zhang, Yi; Zhong, Xueyun; Wang, Yifei

    2014-07-18

    17-Allylamino-17-demethoxygeldanamycin (17-AAG), a typical Hsp90 inhibitor derived from geldanamycin (GA), has entered Phase III clinical trials for cancer therapy. However, it has several significant limitations such as poor solubility, limited bioavailability and unacceptable hepatotoxicity. In this study, the anticancer activity and mechanism of SNX-25a, a novel Hsp90 inhibitor, was investigated comparing with that of 17-AAG. We showed that SNX-25a triggered growth inhibition more sensitively than 17-AAG against many human cancer cells, including K562, SW-620, A375, Hep-2, MCF-7, HepG2, HeLa, and A549 cell lines, especially at low concentrations (AAG, SNX-25a was more potent in arresting the cell cycle at G2 phase, and displayed more potent effects on human cancer cell apoptosis and Hsp90 client proteins. It also exhibited a stronger binding affinity to Hsp90 than 17-AAG using molecular docking. Considering the superiority effects on Hsp90 affinity, cell growth, cell cycle, apoptosis, and Hsp90 client proteins, SNX-25a is supposed as a potential anticancer agent that needs to be explored in detail. Copyright © 2014 Elsevier Inc. All rights reserved.

  13. Glyceroneogenesis is inhibited through HIV protease inhibitor-induced inflammation in human subcutaneous but not visceral adipose tissue

    Science.gov (United States)

    Leroyer, Stéphanie; Vatier, Camille; Kadiri, Sarah; Quette, Joëlle; Chapron, Charles; Capeau, Jacqueline; Antoine, Bénédicte

    2011-01-01

    Glyceroneogenesis, a metabolic pathway that participates during lipolysis in the recycling of free fatty acids to triglycerides into adipocytes, contributes to the lipid-buffering function of adipose tissue. We investigated whether glyceroneogenesis could be affected by human immunodeficiency virus (HIV) protease inhibitors (PIs) responsible or not for dyslipidemia in HIV-infected patients. We treated explants obtained from subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) depots from lean individuals. We observed that the dyslipidemic PIs nelfinavir, lopinavir and ritonavir, but not the lipid-neutral PI atazanavir, increased lipolysis and decreased glyceroneogenesis, leading to an increased release of fatty acids from SAT but not from VAT. At the same time, dyslipidemic PIs decreased the amount of perilipin and increased interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) secretion in SAT but not in VAT. Parthenolide, an inhibitor of the NFκB pathway, counteracted PI-induced increased inflammation and decreased glyceroneogenesis. IL-6 (100 ng) inhibited the activity of phosphoenolpyruvate carboxykinase, the key enzyme of glyceroneogenesis, in SAT but not in VAT. Our data show that dyslipidemic but not lipid-neutral PIs decreased glyceroneogenesis as a consequence of PI-induced increased inflammation in SAT that could have an affect on adipocytes and/or macrophages. These results add a new link between fat inflammation and increased fatty acids release and suggest a greater sensitivity of SAT than VAT to PI-induced inflammation. PMID:21068005

  14. Implication of altered ubiquitin-proteasome system and ER stress in the muscle atrophy of diabetic rats.

    Science.gov (United States)

    Reddy, S Sreenivasa; Shruthi, Karnam; Prabhakar, Y Konda; Sailaja, Gummadi; Reddy, G Bhanuprakash

    2018-02-01

    Skeletal muscle is adversely affected in type-1 diabetes, and excessively stimulated ubiquitin-proteasome system (UPS) was found to be a leading cause of muscle wasting or atrophy. The role of endoplasmic reticulum (ER) stress in muscle atrophy of type-1 diabetes is not known. Hence, we investigated the role of UPS and ER stress in the muscle atrophy of chronic diabetes rat model. Diabetes was induced with streptozotocin (STZ) in male Sprague-Dawley rats and were sacrificed 2- and 4-months thereafter to collect gastrocnemius muscle. In another experiment, 2-months post-STZ-injection diabetic rats were treated with MG132, a proteasome inhibitor, for the next 2-months and gastrocnemius muscle was collected. The muscle fiber cross-sectional area was diminished in diabetic rats. The expression of UPS components: E1, MURF1, TRIM72, UCHL1, UCHL5, ubiquitinated proteins, and proteasome activity were elevated in the diabetic rats indicating activated UPS. Altered expression of ER-associated degradation (ERAD) components and increased ER stress markers were detected in 4-months diabetic rats. Proteasome inhibition by MG132 alleviated alterations in the UPS and ER stress in diabetic rat muscle. Increased UPS activity and ER stress were implicated in the muscle atrophy of diabetic rats and proteasome inhibition exhibited beneficiary outcome. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Inhibition of polar calcium movement and gravitropism in roots treated with auxin-transport inhibitors

    Science.gov (United States)

    Lee, J. S.; Mulkey, T. J.; Evans, M. L.

    1984-01-01

    Primary roots of maize (Zea mays L.) and pea (Pisum sativum L.) exhibit strong positive gravitropism. In both species, gravistimulation induces polar movement of calcium across the root tip from the upper side to the lower side. Roots of onion (Allium cepa L.) are not responsive to gravity and gravistimulation induces little or no polar movement of calcium across the root tip. Treatment of maize or pea roots with inhibitors of auxin transport (morphactin, naphthylphthalamic acid, 2,3,5-triiodobenzoic acid) prevents both gravitropism and gravity-induced polar movement of calcium across the root tip. The results indicate that calcium movement and auxin movement are closely linked in roots and that gravity-induced redistribution of calcium across the root cap may play an important role in the development of gravitropic curvature.

  16. Molecular modeling study on the allosteric inhibition mechanism of HIV-1 integrase by LEDGF/p75 binding site inhibitors.

    Directory of Open Access Journals (Sweden)

    Weiwei Xue

    Full Text Available HIV-1 integrase (IN is essential for the integration of viral DNA into the host genome and an attractive therapeutic target for developing antiretroviral inhibitors. LEDGINs are a class of allosteric inhibitors targeting LEDGF/p75 binding site of HIV-1 IN. Yet, the detailed binding mode and allosteric inhibition mechanism of LEDGINs to HIV-1 IN is only partially understood, which hinders the structure-based design of more potent anti-HIV agents. A molecular modeling study combining molecular docking, molecular dynamics simulation, and binding free energy calculation were performed to investigate the interaction details of HIV-1 IN catalytic core domain (CCD with two recently discovered LEDGINs BI-1001 and CX14442, as well as the LEDGF/p75 protein. Simulation results demonstrated the hydrophobic domain of BI-1001 and CX14442 engages one subunit of HIV-1 IN CCD dimer through hydrophobic interactions, and the hydrophilic group forms hydrogen bonds with HIV-1 IN CCD residues from other subunit. CX14442 has a larger tert-butyl group than the methyl of BI-1001, and forms better interactions with the highly hydrophobic binding pocket of HIV-1 IN CCD dimer interface, which can explain the stronger affinity of CX14442 than BI-1001. Analysis of the binding mode of LEDGF/p75 with HIV-1 IN CCD reveals that the LEDGF/p75 integrase binding domain residues Ile365, Asp366, Phe406 and Val408 have significant contributions to the binding of the LEDGF/p75 to HIV1-IN. Remarkably, we found that binding of BI-1001 and CX14442 to HIV-1 IN CCD induced the structural rearrangements of the 140 s loop and oration displacements of the side chains of the three conserved catalytic residues Asp64, Asp116, and Glu152 located at the active site. These results we obtained will be valuable not only for understanding the allosteric inhibition mechanism of LEDGINs but also for the rational design of allosteric inhibitors of HIV-1 IN targeting LEDGF/p75 binding site.

  17. Synthesis of 3-alkyl enol mimics inhibitors of type II dehydroquinase: factors influencing their inhibition potency.

    Science.gov (United States)

    Blanco, Beatriz; Sedes, Antía; Peón, Antonio; Lamb, Heather; Hawkins, Alastair R; Castedo, Luis; González-Bello, Concepción

    2012-05-14

    Several 3-alkylaryl mimics of the enol intermediate in the reaction catalyzed by type II dehydroquinase were synthesized to investigate the effect on the inhibition potency of replacing the oxygen atom in the side chain by a carbon atom. The length and the rigidity of the spacer was also studied. The inhibitory properties of the reported compounds against type II dehydroquinase from Mycobacterium tuberculosis and Helicobacter pylori are also reported. The binding modes of these analogs in the active site of both enzymes were studied by molecular docking using GOLD 5.0 and dynamic simulations studies.

  18. Inhibition of protease-inhibitor resistant hepatitis C virus replicons and infectious virus by intracellular intrabodies

    OpenAIRE

    Gal-Tanamy, Meital; Zemel, Romy; Bachmatov, Larissa; Jangra, Rohit K.; Shapira, Assaf; Villanueva, Rodrigo; Yi, MinKyung; Lemon, Stanley M.; Benhar, Itai; Tur-Kaspa, Ran

    2010-01-01

    Hepatitis C virus (HCV) infection is a common cause of chronic liver disease and a serious threat to human health. The HCV NS3/4A serine protease is necessary for viral replication and innate immune evasion, and represents a well-validated target for specific antiviral therapy. We previously reported the isolation of single-chain antibodies (scFvs) that inhibit NS3/4A protease activity in vitro. Expressed intracellularly (intrabodies), these scFvs blocked NS3-mediated proliferation of NS3-tra...

  19. Discovery of small-molecule HIV-1 fusion and integrase inhibitors oleuropein and hydroxytyrosol: Part II. Integrase inhibition

    International Nuclear Information System (INIS)

    Lee-Huang, Sylvia; Huang, Philip Lin; Zhang Dawei; Lee, Jae Wook; Bao Ju; Sun Yongtao; Chang, Young-Tae; Zhang, John; Huang, Paul Lee

    2007-01-01

    We report molecular modeling and functional confirmation of Ole and HT binding to HIV-1 integrase. Docking simulations identified two binding regions for Ole within the integrase active site. Region I encompasses the conserved D64-D116-E152 motif, while region II involves the flexible loop region formed by amino acid residues 140-149. HT, on the other hand, binds to region II. Both Ole and HT exhibit favorable interactions with important amino acid residues through strong H-bonding and van der Waals contacts, predicting integrase inhibition. To test and confirm modeling predictions, we examined the effect of Ole and HT on HIV-1 integrase activities including 3'-processing, strand transfer, and disintegration. Ole and HT exhibit dose-dependent inhibition on all three activities, with EC 50 s in the nanomolar range. These studies demonstrate that molecular modeling of target-ligand interaction coupled with structural-activity analysis should facilitate the design and identification of innovative integrase inhibitors and other therapeutics

  20. Inhibition of hydroxycinnamoyl-CoA thioesterases in ginger (Zingiber officinale Rosc.) and turmeric (Curcuma longa L.) by lipase inhibitors.

    Science.gov (United States)

    Flores-Sanchez, Isvett Josefina; Gang, David Roger

    2013-11-01

    Ginger (Zingiber officinale Rosc.) and turmeric (Curcuma longa L.), members of the Zingiberaceae, are widely used in traditional Asian cuisines and herbal medicine. Gingerols and diarylheptanoids, important compounds from these plants, appear to be produced by enzymes of the type III polyketide synthase class. Previous efforts to detect activity of such enzymes in tissues from these plants were only marginally successful in turmeric and completely unsuccessful in ginger because of very rapid hydrolysis of the hydroxycinnamoyl-CoA substrates (p-coumaroyl-CoA, feruloyl-CoA and caffeoyl-CoA) in these assays, presumably due to the presence of thioesterases in these tissues. In order to determine whether such thioesterase activities were specific and could be reduced so that the polyketide synthase activities could be better characterized, three inhibitors of the thioesterase domain of fatty acid synthase were tested in assays with leaf and rhizome crude protein extracts from these plants: orlistat, a reduced form of lipstatin, and peptide 1 and peptide 2 from hydrolysates of soybean β-conglycinin. Results of these analyses indicated that specific thioesterases do exist in these plants and that they could indeed be inhibited, with highest inhibition occurring with a mixture of these three compounds, leading for example to a reduction of caffeoyl-CoA hydrolysis in leaves and rhizomes of ginger by 40-fold and 27-fold, respectively. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  1. Inhibition of homologous recombination repair in irradiated tumor cells pretreated with Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin

    International Nuclear Information System (INIS)

    Noguchi, Miho; Yu, Dong; Hirayama, Ryoichi; Ninomiya, Yasuharu; Sekine, Emiko; Kubota, Nobuo; Ando, Koichi; Okayasu, Ryuichi

    2006-01-01

    In order to investigate the mechanism of radio-sensitization by an Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG), we studied repair of DNA double strand breaks (DSBs) in irradiated human cells pre-treated with 17-AAG. DSBs are thought to be the critical target for radiation-induced cell death. Two human tumor cell lines DU145 and SQ-5 which showed clear radio-sensitization by 17-AAG revealed a significant inhibition of DSB repair, while normal human cells which did not show radio-sensitization by the drug indicated no change in the DSB repair kinetics with 17-AAG. We further demonstrated that BRCA2 was a novel client protein for Hsp90, and 17-AAG caused the degradation of BRCA2 and in turn altered the behavior of Rad51, a critical protein for homologous recombination (HR) pathway of DSB repair. Our data demonstrate for the first time that 17-AAG inhibits the HR repair process and could provide a new therapeutic strategy to selectively result in higher tumor cell killing

  2. Hsp90 inhibitor 17-AAG inhibits progression of LuCaP35 xenograft prostate tumors to castration resistance.

    Science.gov (United States)

    O'Malley, Katherine J; Langmann, Gabrielle; Ai, Junkui; Ramos-Garcia, Raquel; Vessella, Robert L; Wang, Zhou

    2012-07-01

    Advanced prostate cancer is currently treated with androgen deprivation therapy (ADT). ADT initially results in tumor regression; however, all patients eventually relapse with castration-resistant prostate cancer. New approaches to delay the progression of prostate cancer to castration resistance are in desperate need. This study addresses whether targeting Heat shock protein 90 (HSP90) regulation of androgen receptor (AR) can inhibit prostate cancer progression to castration resistance. The HSP90 inhibitor 17-AAG was injected intraperitoneally into nude mice bearing LuCaP35 xenograft tumors to determine the effect of HSP90 inhibition on prostate cancer progression to castration resistance and host survival. Administration of 17-AAG maintained androgen-sensitivity, delayed the progression of LuCaP35 xenograft tumors to castration resistance, and prolonged the survival of host. In addition, 17-AAG prevented nuclear localization of endogenous AR in LuCaP35 xenograft tumors in castrated nude mice. Targeting Hsp90 or the mechanism by which HSP90 regulates androgen-independent AR nuclear localization and activation may lead to new approaches to prevent and/or treat castration-resistant prostate cancer. Copyright © 2011 Wiley Periodicals, Inc.

  3. Inhibition of multiple pathogenic pathways by histone deacetylase inhibitor SAHA in a corneal alkali-burn injury model

    Science.gov (United States)

    Li, Xinyu; Zhou, Qinbo; Hanus, Jakub; Anderson, Chastain; Zhang, Hongmei; Dellinger, Michael; Brekken, Rolf; Wang, Shusheng

    2013-01-01

    Neovascularization (NV) in the cornea is a major cause of vision impairment and corneal blindness. Hemangiogenesis and lymphangiogenesis induced by inflammation underlie the pathogenesis of corneal NV. The current mainstay treatment, corticosteroid, treats the inflammation associated with corneal NV, but is not satisfactory due to such side effects as cataract and the increase in intraocular pressure. It is imperative to develop a novel therapy that specifically targets the hemangiogenesis, lymphangiogenesis and inflammation pathways underlying corneal NV. Histone deacetylase inhibitors (HDACi) have been in clinical trials for cancer and other diseases. In particular, HDACi suberoylanilide hydroxamic acid (SAHA, vorinostat, Zolinza) has been approved by the FDA for the treatment of cutaneous T-cell lymphoma. The functional mechanism of SAHA in cancer and especially in corneal NV remains unclear. Here, we show that topical application of SAHA inhibits neovascularization in an alkali-burn corneal injury model. Mechanistically, SAHA inhibits corneal NV by repressing hemangiogenesis, inflammation pathways and previously overlooked lymphangiogenesis. Topical SAHA is well tolerated on the ocular surface. In addition, the potency of SAHA in corneal NV appears to be comparable to the current steroid therapy. SAHA may possess promising therapeutic potential in alkali-burn corneal injury and other inflammatory neovascularization disorders. PMID:23186311

  4. The ATM and ATR inhibitors CGK733 and caffeine suppress cyclin D1 levels and inhibit cell proliferation

    International Nuclear Information System (INIS)

    Alao, John P; Sunnerhagen, Per

    2009-01-01

    The ataxia telangiectasia mutated (ATM) and the ATM- related (ATR) kinases play a central role in facilitating the resistance of cancer cells to genotoxic treatment regimens. The components of the ATM and ATR regulated signaling pathways thus provide attractive pharmacological targets, since their inhibition enhances cellular sensitivity to chemo- and radiotherapy. Caffeine as well as more specific inhibitors of ATM (KU55933) or ATM and ATR (CGK733) have recently been shown to induce cell death in drug-induced senescent tumor cells. Addition of these agents to cancer cells previously rendered senescent by exposure to genotoxins suppressed the ATM mediated p21 expression required for the survival of these cells. The precise molecular pharmacology of these agents however, is not well characterized. Herein, we report that caffeine, CGK733, and to a lesser extent KU55933, inhibit the proliferation of otherwise untreated human cancer and non-transformed mouse fibroblast cell lines. Exposure of human cancer cell lines to caffeine and CGK733 was associated with a rapid decline in cyclin D1 protein levels and a reduction in the levels of both phosphorylated and total retinoblastoma protein (RB). Our studies suggest that observations based on the effects of these compounds on cell proliferation and survival must be interpreted with caution. The differential effects of caffeine/CGK733 and KU55933 on cyclin D1 protein levels suggest that these agents will exhibit dissimilar molecular pharmacological profiles

  5. Bacterial Effectors and Their Functions in the Ubiquitin-Proteasome System: Insight from the Modes of Substrate Recognition

    Directory of Open Access Journals (Sweden)

    Minsoo Kim

    2014-08-01

    Full Text Available Protein ubiquitination plays indispensable roles in the regulation of cell homeostasis and pathogenesis of neoplastic, infectious, and neurodegenerative diseases. Given the importance of this modification, it is to be expected that several pathogenic bacteria have developed the ability to utilize the host ubiquitin system for their own benefit. Modulation of the host ubiquitin system by bacterial effector proteins inhibits innate immune responses and hijacks central signaling pathways. Bacterial effectors mimic enzymes of the host ubiquitin system, but may or may not be structurally similar to the mammalian enzymes. Other effectors bind and modify components of the host ubiquitin system, and some are themselves subject to ubiquitination. This review will describe recent findings, based on structural analyses, regarding how pathogens use post-translational modifications of proteins to establish an infection.

  6. Bacterial effectors and their functions in the ubiquitin-proteasome system: insight from the modes of substrate recognition.

    Science.gov (United States)

    Kim, Minsoo; Otsubo, Ryota; Morikawa, Hanako; Nishide, Akira; Takagi, Kenji; Sasakawa, Chihiro; Mizushima, Tsunehiro

    2014-08-18

    Protein ubiquitination plays indispensable roles in the regulation of cell homeostasis and pathogenesis of neoplastic, infectious, and neurodegenerative diseases. Given the importance of this modification, it is to be expected that several pathogenic bacteria have developed the ability to utilize the host ubiquitin system for their own benefit. Modulation of the host ubiquitin system by bacterial effector proteins inhibits innate immune responses and hijacks central signaling pathways. Bacterial effectors mimic enzymes of the host ubiquitin system, but may or may not be structurally similar to the mammalian enzymes. Other effectors bind and modify components of the host ubiquitin system, and some are themselves subject to ubiquitination. This review will describe recent findings, based on structural analyses, regarding how pathogens use post-translational modifications of proteins to establish an infection.

  7. Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin inhibits the proliferation of ARPE-19 cells

    Directory of Open Access Journals (Sweden)

    Wang Lin

    2010-04-01

    Full Text Available Abstract Background The antiproliferative effect of the Hsp90 inhibitor 17-AAG (17-allylamino-17-demethoxygeldanamycin on human retinal pigment epithelial cells is investigated. Methods MTT and flow cytometry were used to study the antiproliferative effects of the 17-AAG treatment of ARPE-19 cells. 2D gel electrophoresis (2-DE and mass spectrometry were applied to detect the altered expression of proteins, which was verified by real-time PCR. Gene Ontology analysis and Ingenuity Pathway Analysis (IPA were utilized to analyze the signaling pathways, cellular location, function, and network connections of the identified proteins. And SOD assay was employed to confirm the analysis. Results 17-AAG suppressed the proliferation of ARPE-19 cells by inducing cell cycle arrest and apoptosis. Proteomic analysis revealed that the expression of 94 proteins was altered by a factor of more than 1.5 following exposure to 17-AAG. Of these 94, 87 proteins were identified. Real-time PCR results indicated that Hsp90 and Hsp70, which were not identified by proteomic analysis, were both upregulated upon 17-AAG treatment. IPA revealed that most of the proteins have functions that are related to oxidative stress, as verified by SOD assay, while canonical pathway analysis revealed glycolysis/gluconeogenesis. Conclusions 17-AAG suppressed the proliferation of ARPE-19 cells by inducing cell cycle arrest and apoptosis, and possibly by oxidative stress.

  8. Inhibitors of the proteasome reduce the accelerated proteolysis in atrophying rat skeletal muscles.

    Science.gov (United States)

    Tawa, N E; Odessey, R; Goldberg, A L

    1997-07-01

    Several observations have suggested that the enhanced proteolysis and atrophy of skeletal muscle in various pathological states is due primarily to activation of the ubiquitin-proteasome pathway. To test this idea, we investigated whether peptide aldehyde inhibitors of the proteasome, N-acetyl-leucyl-leucyl-norleucinal (LLN), or the more potent CBZ-leucyl-leucyl-leucinal (MG132) suppressed proteolysis in incubated rat skeletal muscles. These agents (e.g., MG132 at 10 microM) inhibited nonlysosomal protein breakdown by up to 50% (P protein synthesis or amino acid pools, but improved overall protein balance in the muscle. Upon treatment with MG132, ubiquitin-conjugated proteins accumulated in the muscle. The inhibition of muscle proteolysis correlated with efficacy against the proteasome, although these agents could also inhibit calpain-dependent proteolysis induced with Ca2+. These inhibitors had much larger effects on proteolysis in atrophying muscles than in controls. In the denervated soleus undergoing atrophy, the increase in ATP-dependent proteolysis was reduced 70% by MG132 (P muscle proteolysis induced by administering thyroid hormones was reduced 40-70% by the inhibitors. Finally, in rats made septic by cecal puncture, the increase in muscle proteolysis was completely blocked by MG132. Thus, the enhanced proteolysis in many catabolic states (including denervation, hyperthyroidism, and sepsis) is due to a proteasome-dependent pathway, and inhibition of proteasome function may be a useful approach to reduce muscle wasting.

  9. SphK1 inhibitor II (SKI-II) inhibits acute myelogenous leukemia cell growth in vitro and in vivo

    International Nuclear Information System (INIS)

    Yang, Li; Weng, Wei; Sun, Zhi-Xin; Fu, Xian-Jie; Ma, Jun; Zhuang, Wen-Fang

    2015-01-01

    Previous studies have identified sphingosine kinase 1 (SphK1) as a potential drug target for treatment of acute myeloid leukemia (AML). In the current study, we investigated the potential anti-leukemic activity of a novel and specific SphK1 inhibitor, SKI-II. We demonstrated that SKI-II inhibited growth and survival of human AML cell lines (HL-60 and U937 cells). SKI-II was more efficient than two known SphK1 inhibitors SK1-I and FTY720 in inhibiting AML cells. Meanwhile, it induced dramatic apoptosis in above AML cells, and the cytotoxicity by SKI-II was almost reversed by the general caspase inhibitor z-VAD-fmk. SKI-II treatment inhibited SphK1 activation, and concomitantly increased level of sphingosine-1-phosphate (S1P) precursor ceramide in AML cells. Conversely, exogenously-added S1P protected against SKI-II-induced cytotoxicity, while cell permeable short-chain ceramide (C6) aggravated SKI-II's lethality against AML cells. Notably, SKI-II induced potent apoptotic death in primary human AML cells, but was generally safe to the human peripheral blood mononuclear cells (PBMCs) isolated from healthy donors. In vivo, SKI-II administration suppressed growth of U937 leukemic xenograft tumors in severe combined immunodeficient (SCID) mice. These results suggest that SKI-II might be further investigated as a promising anti-AML agent. - Highlights: • SKI-II inhibits proliferation and survival of primary and transformed AML cells. • SKI-II induces apoptotic death of AML cells, but is safe to normal PBMCs. • SKI-II is more efficient than two known SphK1 inhibitors in inhibiting AML cells. • SKI-II inhibits SphK1 activity, while increasing ceramide production in AML cells. • SKI-II dose-dependently inhibits U937 xenograft growth in SCID mice

  10. SphK1 inhibitor II (SKI-II) inhibits acute myelogenous leukemia cell growth in vitro and in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Li; Weng, Wei; Sun, Zhi-Xin; Fu, Xian-Jie; Ma, Jun, E-mail: majuntongrensh1@126.com; Zhuang, Wen-Fang, E-mail: wenfangzhuangmd@163.com

    2015-05-15

    Previous studies have identified sphingosine kinase 1 (SphK1) as a potential drug target for treatment of acute myeloid leukemia (AML). In the current study, we investigated the potential anti-leukemic activity of a novel and specific SphK1 inhibitor, SKI-II. We demonstrated that SKI-II inhibited growth and survival of human AML cell lines (HL-60 and U937 cells). SKI-II was more efficient than two known SphK1 inhibitors SK1-I and FTY720 in inhibiting AML cells. Meanwhile, it induced dramatic apoptosis in above AML cells, and the cytotoxicity by SKI-II was almost reversed by the general caspase inhibitor z-VAD-fmk. SKI-II treatment inhibited SphK1 activation, and concomitantly increased level of sphingosine-1-phosphate (S1P) precursor ceramide in AML cells. Conversely, exogenously-added S1P protected against SKI-II-induced cytotoxicity, while cell permeable short-chain ceramide (C6) aggravated SKI-II's lethality against AML cells. Notably, SKI-II induced potent apoptotic death in primary human AML cells, but was generally safe to the human peripheral blood mononuclear cells (PBMCs) isolated from healthy donors. In vivo, SKI-II administration suppressed growth of U937 leukemic xenograft tumors in severe combined immunodeficient (SCID) mice. These results suggest that SKI-II might be further investigated as a promising anti-AML agent. - Highlights: • SKI-II inhibits proliferation and survival of primary and transformed AML cells. • SKI-II induces apoptotic death of AML cells, but is safe to normal PBMCs. • SKI-II is more efficient than two known SphK1 inhibitors in inhibiting AML cells. • SKI-II inhibits SphK1 activity, while increasing ceramide production in AML cells. • SKI-II dose-dependently inhibits U937 xenograft growth in SCID mice.

  11. AP24534, a Pan-BCR-ABL Inhibitor for Chronic Myeloid Leukemia, Potently Inhibits the T315I Mutant and Overcomes Mutation-Based Resistance

    Science.gov (United States)

    O’Hare, Thomas; Shakespeare, William C.; Zhu, Xiaotian; Eide, Christopher A.; Rivera, Victor M.; Wang, Frank; Adrian, Lauren T.; Zhou, Tianjun; Huang, Wei-Sheng; Xu, Qihong; Metcalf, Chester A.; Tyner, Jeffrey W.; Loriaux, Marc M.; Corbin, Amie S.; Wardwell, Scott; Ning, Yaoyu; Keats, Jeffrey A.; Wang, Yihan; Sundaramoorthi, Raji; Thomas, Mathew; Zhou, Dong; Snodgrass, Joseph; Commodore, Lois; Sawyer, Tomi K.; Dalgarno, David C.; Deininger, Michael W.N.; Druker, Brian J.; Clackson, Tim

    2009-01-01

    SUMMARY Inhibition of BCR-ABL by imatinib induces durable responses in many patients with chronic myeloid leukemia (CML), but resistance attributable to kinase domain mutations can lead to relapse and a switch to second-line therapy with nilotinib or dasatinib. Despite three approved therapeutic options, the cross-resistant BCR-ABLT315I mutation and compound mutants selected on sequential inhibitor therapy remain major clinical challenges. We report design and pre-clinical evaluation of AP24534, a potent, orally available multi-targeted kinase inhibitor active against T315I and other BCR-ABL mutants. AP24534 inhibited all tested BCR-ABL mutants in cellular and biochemical assays, suppressed BCR-ABLT315I-driven tumor growth in mice, and completely abrogated resistance in cell-based mutagenesis screens. Our work supports clinical evaluation of AP24534 as a pan-BCR-ABL inhibitor for treatment of CML. PMID:19878872

  12. AP24534, a Pan-BCR-ABL Inhibitor for Chronic Myeloid Leukemia, Potently Inhibits the T315I Mutant and Overcomes Mutation-Based Resistance

    Energy Technology Data Exchange (ETDEWEB)

    O’Hare, Thomas; Shakespeare, William C.; Zhu, Xiaotian; Eide, Christopher A.; Rivera, Victor M.; Wang, Frank; Adrian, Lauren T.; Zhou, Tianjun; Huang, Wei-Sheng; Xu, Qihong; Metcalf, III, Chester A.; Tyner, Jeffrey W.; Loriaux, Marc M.; Corbin, Amie S.; Wardwell, Scott; Ning, Yaoyu; Keats, Jeffrey A.; Wang, Yihan; Sundaramoorthi, Raji; Thomas, Mathew; Zhou, Dong; Snodgrass, Joseph; Commodore, Lois; Sawyer, Tomi K.; Dalgarno, David C.; Deininger, Michael W.N.; Druker, Brian J.; Clackson, Tim; (OHSU- Cancer Instit.); (ARIAD)

    2010-09-07

    Inhibition of BCR-ABL by imatinib induces durable responses in many patients with chronic myeloid leukemia (CML), but resistance attributable to kinase domain mutations can lead to relapse and a switch to second-line therapy with nilotinib or dasatinib. Despite three approved therapeutic options, the cross-resistant BCR-ABL{sup T315I} mutation and compound mutants selected on sequential inhibitor therapy remain major clinical challenges. We report design and preclinical evaluation of AP24534, a potent, orally available multitargeted kinase inhibitor active against T315I and other BCR-ABL mutants. AP24534 inhibited all tested BCR-ABL mutants in cellular and biochemical assays, suppressed BCR-ABL{sup T315I}-driven tumor growth in mice, and completely abrogated resistance in cell-based mutagenesis screens. Our work supports clinical evaluation of AP24534 as a pan-BCR-ABL inhibitor for treatment of CML.

  13. Preparation of ubiquitin-conjugated proteins using an insect cell-free protein synthesis system.

    Science.gov (United States)

    Suzuki, Takashi; Ezure, Toru; Ando, Eiji; Nishimura, Osamu; Utsumi, Toshihiko; Tsunasawa, Susumu

    2010-01-01

    Ubiquitination is one of the most significant posttranslational modifications (PTMs). To evaluate the ability of an insect cell-free protein synthesis system to carry out ubiquitin (Ub) conjugation to in vitro translated proteins, poly-Ub chain formation was studied in an insect cell-free protein synthesis system. Poly-Ub was generated in the presence of Ub aldehyde (UA), a de-ubiquitinating enzyme inhibitor. In vitro ubiquitination of the p53 tumor suppressor protein was also analyzed, and p53 was poly-ubiquitinated when Ub, UA, and Mdm2, an E3 Ub ligase (E3) for p53, were added to the in vitro reaction mixture. These results suggest that the insect cell-free protein synthesis system contains enzymatic activities capable of carrying out ubiquitination. CBB-detectable ubiquitinated p53 was easily purified from the insect cell-free protein synthesis system, allowing analysis of the Ub-conjugated proteins by mass spectrometry (MS). Lys 305 of p53 was identified as one of the Ub acceptor sites using this strategy. Thus, we conclude that the insect cell-free protein synthesis system is a powerful tool for studying various PTMs of eukaryotic proteins including ubiqutination presented here.

  14. The Janus kinase inhibitor tofacitinib inhibits TNF-α-induced gliostatin expression in rheumatoid fibroblast-like synoviocytes.

    Science.gov (United States)

    Kawaguchi, Yohei; Waguri-Nagaya, Yuko; Tatematsu, Naoe; Oguri, Yusuke; Kobayashi, Masaaki; Nozaki, Masahiro; Asai, Kiyofumi; Aoyama, Mineyoshi; Otsuka, Takanobu

    2018-01-15

    Gliostatin (GLS) is known to have angiogenic and arthritogenic activity, and GLS expression levels in serum from patients with rheumatoid arthritis (RA) are significantly correlated with the disease activity. Tofacitinib is a novel oral Janus kinase (JAK) inhibitor and is effective in treating RA. However, the mechanism of action of tofacitinib in fibroblast-like synoviocytes (FLSs) has not been elucidated. The purpose of this study was to investigate the modulatory effects of tofacitinib on serum GLS levels in patients with RA and GLS production in FLSs derived from patients with RA. Six patients with RA who had failed therapy with at least one TNF inhibitor and were receiving tofacitinib therapy were included in the study. Serum samples were collected to measure CRP, MMP-3 and GLS expression. FLSs derived from patients with RA were cultured and stimulated by TNFα with or without tofacitinib. GLS expression levels were determined using reverse transcription-polymerase chain reaction (RT-PCR), EIA and immunocytochemistry, and signal transducer and activator of transcription (STAT) protein phosphorylation levels were determined by western blotting. Treatment with tofacitinib decreased serum GLS levels in all patients. GLS mRNA and protein expression levels were significantly increased by treatment with TNF-α alone, and these increases were suppressed by treatment with tofacitinib, which also inhibited TNF-α-induced STAT1 phosphorylation. JAK/STAT activation plays a pivotal role in TNF-α-mediated GLS up-regulation in RA. Suppression of GLS expression in FLSs has been suggested to be one of the mechanisms through which tofacitinib exerts its anti-inflammatory effects.

  15. Kinetics of corrosion inhibition of aluminum in acidic media by water-soluble natural polymeric chondroitin-4-sulfate as anionic polyelectrolyte inhibitor.

    Science.gov (United States)

    Hassan, Refat M; Ibrahim, Samia M; Takagi, Hideo D; Sayed, Suzan A

    2018-07-15

    Corrosion inhibition of aluminum (Al) in hydrochloric acid by anionic polyelectrolyte chondroitin-4-sulfate (CS) polysaccharide has been studied using both gasometrical and weight-loss techniques. The results drawn from these two techniques are comparable and exhibit negligible differences. The inhibition efficiency was found to increase with increasing the inhibitor concentration and decreased with increasing temperature. The inhibition action of CS on Al metal surface was found to obey both of Langmuir and Freundlich isotherms. The factors affecting the corrosion rates such as the concentration and geometrical structure of the inhibitor, concentration of the corrosive medium, and the temperature were examined. The kinetic parameters were evaluated and a suitable corrosion mechanism consistent with the results obtained is discussed. Copyright © 2018. Published by Elsevier Ltd.

  16. Linear ubiquitination signals in adaptive immune responses.

    Science.gov (United States)

    Ikeda, Fumiyo

    2015-07-01

    Ubiquitin can form eight different linkage types of chains using the intrinsic Met 1 residue or one of the seven intrinsic Lys residues. Each linkage type of ubiquitin chain has a distinct three-dimensional topology, functioning as a tag to attract specific signaling molecules, which are so-called ubiquitin readers, and regulates various biological functions. Ubiquitin chains linked via Met 1 in a head-to-tail manner are called linear ubiquitin chains. Linear ubiquitination plays an important role in the regulation of cellular signaling, including the best-characterized tumor necrosis factor (TNF)-induced canonical nuclear factor-κB (NF-κB) pathway. Linear ubiquitin chains are specifically generated by an E3 ligase complex called the linear ubiquitin chain assembly complex (LUBAC) and hydrolyzed by a deubiquitinase (DUB) called ovarian tumor (OTU) DUB with linear linkage specificity (OTULIN). LUBAC linearly ubiquitinates critical molecules in the TNF pathway, such as NEMO and RIPK1. The linear ubiquitin chains are then recognized by the ubiquitin readers, including NEMO, which control the TNF pathway. Accumulating evidence indicates an importance of the LUBAC complex in the regulation of apoptosis, development, and inflammation in mice. In this article, I focus on the role of linear ubiquitin chains in adaptive immune responses with an emphasis on the TNF-induced signaling pathways. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Pim kinase inhibition sensitizes FLT3-ITD acute myeloid leukemia cells to topoisomerase 2 inhibitors through increased DNA damage and oxidative stress

    Science.gov (United States)

    Doshi, Kshama A.; Trotta, Rossana; Natarajan, Karthika; Rassool, Feyruz V.; Tron, Adriana E.; Huszar, Dennis; Perrotti, Danilo; Baer, Maria R.

    2016-01-01

    Internal tandem duplication of fms-like tyrosine kinase-3 (FLT3-ITD) is frequent (30 percent) in acute myeloid leukemia (AML), and is associated with short disease-free survival following chemotherapy. The serine threonine kinase Pim-1 is a pro-survival oncogene transcriptionally upregulated by FLT3-ITD that also promotes its signaling in a positive feedback loop. Thus inhibiting Pim-1 represents an attractive approach in targeting FLT3-ITD cells. Indeed, co-treatment with the pan-Pim kinase inhibitor AZD1208 or expression of a kinase-dead Pim-1 mutant sensitized FLT3-ITD cell lines to apoptosis triggered by chemotherapy drugs including the topoisomerase 2 inhibitors daunorubicin, etoposide and mitoxantrone, but not the nucleoside analog cytarabine. AZD1208 sensitized primary AML cells with FLT3-ITD to topoisomerase 2 inhibitors, but did not sensitize AML cells with wild-type FLT3 or remission bone marrow cells, supporting a favorable therapeutic index. Mechanistically, the enhanced apoptosis observed with AZD1208 and topoisomerase 2 inhibitor combination treatment was associated with increased DNA double-strand breaks and increased levels of reactive oxygen species (ROS), and co-treatment with the ROS scavenger N-acetyl cysteine rescued FLT3-ITD cells from AZD1208 sensitization to topoisomerase 2 inhibitors. Our data support testing of Pim kinase inhibitors with topoisomerase 2 inhibitors, but not with cytarabine, to improve treatment outcomes in AML with FLT3-ITD. PMID:27374090

  18. L-carnitine is an endogenous HDAC inhibitor selectively inhibiting cancer cell growth in vivo and in vitro.

    Science.gov (United States)

    Huang, Hongbiao; Liu, Ningning; Guo, Haiping; Liao, Siyan; Li, Xiaofen; Yang, Changshan; Liu, Shouting; Song, Wenbin; Liu, Chunjiao; Guan, Lixia; Li, Bing; Xu, Li; Zhang, Change; Wang, Xuejun; Dou, Q Ping; Liu, Jinbao

    2012-01-01

    L-carnitine (LC) is generally believed to transport long-chain acyl groups from fatty acids into the mitochondrial matrix for ATP generation via the citric acid cycle. Based on Warburg's theory that most cancer cells mainly depend on glycolysis for ATP generation, we hypothesize that, LC treatment would lead to disturbance of cellular metabolism and cytotoxicity in cancer cells. In this study, Human hepatoma HepG2, SMMC-7721 cell lines, primary cultured thymocytes and mice bearing HepG2 tumor were used. ATP content was detected by HPLC assay. Cell cycle, cell death and cell viability were assayed by flow cytometry and MTS respectively. Gene, mRNA expression and protein level were detected by gene microarray, Real-time PCR and Western blot respectively. HDAC activities and histone acetylation were detected both in test tube and in cultured cells. A molecular docking study was carried out with CDOCKER protocol of Discovery Studio 2.0 to predict the molecular interaction between L-carnitine and HDAC. Here we found that (1) LC treatment selectively inhibited cancer cell growth in vivo and in vitro; (2) LC treatment selectively induces the expression of p21(cip1) gene, mRNA and protein in cancer cells but not p27(kip1); (4) LC increases histone acetylation and induces accumulation of acetylated histones both in normal thymocytes and cancer cells; (5) LC directly inhibits HDAC I/II activities via binding to the active sites of HDAC and induces histone acetylation and lysine-acetylation accumulation in vitro; (6) LC treatment induces accumulation of acetylated histones in chromatin associated with the p21(cip1) gene but not p27(kip1) detected by ChIP assay. These data support that LC, besides transporting acyl group, works as an endogenous HDAC inhibitor in the cell, which would be of physiological and pathological importance.

  19. Inhibition of P-glycoprotein by HIV protease inhibitors increases intracellular accumulation of berberine in murine and human macrophages.

    Directory of Open Access Journals (Sweden)

    Weibin Zha

    Full Text Available HIV protease inhibitor (PI-induced inflammatory response in macrophages is a major risk factor for cardiovascular diseases. We have previously reported that berberine (BBR, a traditional herbal medicine, prevents HIV PI-induced inflammatory response through inhibiting endoplasmic reticulum (ER stress in macrophages. We also found that HIV PIs significantly increased the intracellular concentrations of BBR in macrophages. However, the underlying mechanisms of HIV PI-induced BBR accumulation are unknown. This study examined the role of P-glycoprotein (P-gp in HIV PI-mediated accumulation of BBR in macrophages.Cultured mouse RAW264.7 macrophages, human THP-1-derived macrophages, Wild type MDCK (MDCK/WT and human P-gp transfected (MDCK/P-gp cells were used in this study. The intracellular concentration of BBR was determined by HPLC. The activity of P-gp was assessed by measuring digoxin and rhodamine 123 (Rh123 efflux. The interaction between P-gp and BBR or HIV PIs was predicated by Glide docking using Schrodinger program. The results indicate that P-gp contributed to the efflux of BBR in macrophages. HIV PIs significantly increased BBR concentrations in macrophages; however, BBR did not alter cellular HIV PI concentrations. Although HIV PIs did not affect P-gp expression, P-gp transport activities were significantly inhibited in HIV PI-treated macrophages. Furthermore, the molecular docking study suggests that both HIV PIs and BBR fit the binding pocket of P-gp, and HIV PIs may compete with BBR to bind P-gp.HIV PIs increase the concentration of BBR by modulating the transport activity of P-gp in macrophages. Understanding the cellular mechanisms of potential drug-drug interactions is critical prior to applying successful combinational therapy in the clinic.

  20. Cannabinoids inhibit angiogenic capacities of endothelial cells via release of tissue inhibitor of matrix metalloproteinases-1 from lung cancer cells.

    Science.gov (United States)

    Ramer, Robert; Fischer, Sascha; Haustein, Maria; Manda, Katrin; Hinz, Burkhard

    2014-09-15

    Cannabinoids inhibit tumor neovascularization as part of their tumorregressive action. However, the underlying mechanism is still under debate. In the present study the impact of cannabinoids on potential tumor-to-endothelial cell communication conferring anti-angiogenesis was studied. Cellular behavior of human umbilical vein endothelial cells (HUVEC) associated with angiogenesis was evaluated by Boyden chamber, two-dimensional tube formation and fibrin bead assay, with the latter assessing three-dimensional sprout formation. Viability was quantified by the WST-1 test. Conditioned media (CM) from A549 lung cancer cells treated with cannabidiol, Δ(9)-tetrahydrocannabinol, R(+)-methanandamide or the CB2 agonist JWH-133 elicited decreased migration as well as tube and sprout formation of HUVEC as compared to CM of vehicle-treated cancer cells. Inhibition of sprout formation was further confirmed for cannabinoid-treated A549 cells co-cultured with HUVEC. Using antagonists to cannabinoid-activated receptors the antimigratory action was shown to be mediated via cannabinoid receptors or transient receptor potential vanilloid 1. SiRNA approaches revealed a cannabinoid-induced expression of tissue inhibitor of matrix metalloproteinases-1 (TIMP-1) as well as its upstream trigger, the intercellular adhesion molecule-1, to be causally linked to the observed decrease of HUVEC migration. Comparable anti-angiogenic effects were not detected following direct exposure of HUVEC to cannabinoids, but occurred after addition of recombinant TIMP-1 to HUVEC. Finally, antimigratory effects were confirmed for CM of two other cannabinoid-treated lung cancer cell lines (H460 and H358). Collectively, our data suggest a pivotal role of the anti-angiogenic factor TIMP-1 in intercellular tumor-endothelial cell communication resulting in anti-angiogenic features of endothelial cells. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. SAR405, a PIK3C3/Vps34 inhibitor that prevents autophagy and synergizes with MTOR inhibition in tumor cells.

    Science.gov (United States)

    Pasquier, Benoit

    2015-04-03

    Autophagy plays an important role in cancer and it has been suggested that it functions not only as a tumor suppressor pathway to prevent tumor initiation, but also as a prosurvival pathway that helps tumor cells endure metabolic stress and resist death triggered by chemotherapeutic agents. We recently described the discovery of inhibitors of PIK3C3/Vps34 (phosphatidylinositol 3-kinase, catalytic subunit type 3), the lipid kinase component of the class III phosphatidylinositol 3-kinase (PtdIns3K). This PtdIns3K isoform has attracted significant attention in recent years because of its role in autophagy. Following chemical optimization we identified SAR405, a low molecular mass kinase inhibitor of PIK3C3, highly potent and selective with regard to other lipid and protein kinases. We demonstrated that inhibiting the catalytic activity of PIK3C3 disrupts vesicle trafficking from late endosomes to lysosomes. SAR405 treatment also inhibits autophagy induced either by starvation or by MTOR (mechanistic target of rapamycin) inhibition. Finally our results show that combining SAR405 with everolimus, the FDA-approved MTOR inhibitor, results in a significant synergy on the reduction of cell proliferation using renal tumor cells. This result indicates a potential therapeutic application for PIK3C3 inhibitors in cancer.

  2. The Ubiquitin E3 Ligase TRAF6 Exacerbates Ischemic Stroke by Ubiquitinating and Activating Rac1.

    Science.gov (United States)

    Li, Tao; Qin, Juan-Juan; Yang, Xia; Ji, Yan-Xiao; Guo, Fangliang; Cheng, Wen-Lin; Wu, Xiaolin; Gong, Fu-Han; Hong, Ying; Zhu, Xue-Yong; Gong, Jun; Wang, Zhihua; Huang, Zan; She, Zhi-Gang; Li, Hongliang

    2017-12-13

    Stroke is one of the leading causes of morbidity and mortality worldwide. Inflammation, oxidative stress, apoptosis, and excitotoxicity contribute to neuronal death during ischemic stroke; however, the mechanisms underlying these complicated pathophysiological processes remain to be fully elucidated. Here, we found that the expression of tumor necrosis factor receptor-associated factor 6 (TRAF6) was markedly increased after cerebral ischemia/reperfusion (I/R) in mice. TRAF6 ablation in male mice decreased the infarct volume and neurological deficit scores and decreased proinflammatory signaling, oxidative stress, and neuronal death after cerebral I/R, whereas transgenic overexpression of TRAF6 in male mice exhibited the opposite effects. Mechanistically, we demonstrated that TRAF6 induced Rac1 activation and consequently promoted I/R injury by directly binding and ubiquitinating Rac1. Either functionally mutating the TRAF6 ubiquitination site on Rac1 or inactivating Rac1 with a specific inhibitor reversed the deleterious effects of TRAF6 overexpression during I/R injury. In conclusion, our study demonstrated that TRAF6 is a key promoter of ischemic signaling cascades and neuronal death after cerebral I/R injury. Therefore, the TRAF6/Rac1 pathway might be a promising target to attenuate cerebral I/R injury. SIGNIFICANCE STATEMENT Stroke is one of the most severe and devastating neurological diseases globally. The complicated pathophysiological processes restrict the translation of potential therapeutic targets into medicine. Further elucidating the molecular mechanisms underlying cerebral ischemia/reperfusion injury may open a new window for pharmacological interventions to promote recovery from stroke. Our study revealed that ischemia-induced tumor necrosis factor receptor-associated factor 6 (TRAF6) upregulation binds and ubiquitinates Rac1 directly, which promotes neuron death through neuroinflammation and neuro-oxidative signals. Therefore, precisely targeting

  3. Insight to structural subsite recognition in plant thiol protease-inhibitor complexes : Understanding the basis of differential inhibition and the role of water

    Directory of Open Access Journals (Sweden)

    Mukhopadhayay Bishnu P

    2001-09-01

    Full Text Available Abstract Background This work represents an extensive MD simulation / water-dynamics studies on a series of complexes of inhibitors (leupeptin, E-64, E-64-C, ZPACK and plant cysteine proteases (actinidin, caricain, chymopapain, calotropin DI of papain family to understand the various interactions, water binding mode, factors influencing it and the structural basis of differential inhibition. Results The tertiary structure of the enzyme-inhibitor complexes were built by visual interactive modeling and energy minimization followed by dynamic simulation of 120 ps in water environment. DASA study with and without the inhibitor revealed the potential subsite residues involved in inhibition. Though the interaction involving main chain atoms are similar, critical inspection of the complexes reveal significant differences in the side chain interactions in S2-P2 and S3-P3 pairs due to sequence differences in the equivalent positions of respective subsites leading to differential inhibition. Conclusion The key finding of the study is a conserved site of a water molecule near oxyanion hole of the enzyme active site, which is found in all the modeled complexes and in most crystal structures of papain family either native or complexed. Conserved water molecules at the ligand binding sites of these homologous proteins suggest the structural importance of the water, which changes the conventional definition of chemical geometry of inhibitor binding domain, its shape and complimentarity. The water mediated recognition of inhibitor to enzyme subsites (Pn...H2O....Sn of leupeptin acetyl oxygen to caricain, chymopapain and calotropinDI is an additional information and offer valuable insight to potent inhibitor design.

  4. Suppression of human T cell proliferation by the caspase inhibitors, z-VAD-FMK and z-IETD-FMK is independent of their caspase inhibition properties

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence, C.P. [Medical Research Council Toxicology Unit, Hodgkin Building, Lancaster Road, University of Leicester, Leicester LE1 9HN (United Kingdom); Chow, S.C., E-mail: chow.sek.chuen@monash.edu [School of Science, Monash University Sunway Campus, Jalan Lagoon Selatan, Bandar Sunway, 46150 Selangor Darul Ehsan (Malaysia)

    2012-11-15

    The caspase inhibitors, benzyloxycarbony (Cbz)-l-Val-Ala-Asp (OMe)-fluoromethylketone (z-VAD-FMK) and benzyloxycarbonyl (Cbz)-Ile-Glu (OMe)-Thr-Asp (OMe)-FMK (z-IETD-FMK) at non-toxic doses were found to be immunosuppressive and inhibit human T cell proliferation induced by mitogens and IL-2 in vitro. Both caspase inhibitors were shown to block NF-κB in activated primary T cells, but have little inhibitory effect on the secretion of IL-2 and IFN-γ during T cell activation. However, the expression of IL-2 receptor α-chain (CD25) in activated T cells was inhibited by both z-VAD-FMK and z-IETD-FMK, whereas the expression of the early activated T cell marker, CD69 was unaffected. During primary T cell activation via the antigen receptor, both caspase-8 and caspase-3 were activated and processed to their respective subunits, but neither caspase inhibitors had any effect on the processing of these two caspases. In sharp contrast both caspase inhibitors readily blocked apoptosis and the activation of caspases during FasL-induced apoptosis in activated primary T cells and Jurkat T cells. Collectively, the results demonstrate that both z-VAD-FMK and z-IETD-FMK are immunosuppressive in vitro and inhibit T cell proliferation without blocking the processing of caspase-8 and caspase-3. -- Highlights: ► Caspase-8 and caspase-3 were activated during T cell activation and proliferation. ► T cell proliferation was blocked by caspase inhibitors. ► Caspase activation during T cell proliferation was not block by caspase inhibitors.

  5. Dynamic survey of mitochondria by ubiquitin

    Science.gov (United States)

    Escobar-Henriques, Mafalda; Langer, Thomas

    2014-01-01

    Ubiquitin is a post-translational modifier with proteolytic and non-proteolytic roles in many biological processes. At mitochondria, it performs regulatory homeostatic functions and contributes to mitochondrial quality control. Ubiquitin is essential for mitochondrial fusion, regulates mitochondria-ER contacts, and participates in maternal mtDNA inheritance. Under stress, mitochondrial dysfunction induces ubiquitin-dependent responses that involve mitochondrial proteome remodeling and culminate in organelle removal by mitophagy. In addition, many ubiquitin-dependent mechanisms have been shown to regulate innate immune responses and xenophagy. Here, we review the emerging roles of ubiquitin at mitochondria. PMID:24569520

  6. Inhibition of potentially lethal radiation damage repair in normal and neoplastic human cells by 3-aminobenzamide: an inhibitor of poly(ADP-ribosylation)

    International Nuclear Information System (INIS)

    Thraves, P.J.; Mossman, K.L.; Frazier, D.T.; Dritschilo, A.

    1986-01-01

    The effect of 3-aminobenzamide (3AB), an inhibitor of poly(ADP-ribose) synthetase, on potentially lethal damage repair (PLDR) was investigated in normal human fibroblasts and four human tumor cell lines from tumors with varying degrees of radiocurability. The tumor lines selected were: Ewing's sarcoma, a bone tumor considered radiocurable and, human lung adenocarcinoma, osteosarcoma, and melanoma, three tumors considered nonradiocurable. PLDR was measured by comparing cell survival when cells were irradiated in a density-inhibited state and replated at appropriate cell numbers at specified times following irradiation to cell survival when cells were replated immediately following irradiation. 3AB was added to cultures 2 hr prior to irradiation and removed at the time of replating. Different test radiation doses were used for the various cell lines to obtain equivalent levels of cell survival. In the absence of inhibitor, PLDR was similar in all cell lines tested. In the presence of 8 mM 3AB, differential inhibition of PLDR was observed. PLDR was almost completely inhibited in Ewing's sarcoma cells and partially inhibited in normal fibroblast cells and osteosarcoma cells. No inhibition of PLDR was observed in the lung adenocarcinoma or melanoma cells. Except for the osteosarcoma cells, inhibition of PLDR by 3AB correlated well with radiocurability

  7. Discovery of small-molecule HIV-1 fusion and integrase inhibitors oleuropein and hydroxytyrosol: Part I. Integrase inhibition

    International Nuclear Information System (INIS)

    Lee-Huang, Sylvia; Huang, Philip Lin; Zhang Dawei; Lee, Jae Wook; Bao Ju; Sun Yongtao; Chang, Young-Tae; Zhang, John; Huang, Paul Lee

    2007-01-01

    We have identified oleuropein (Ole) and hydroxytyrosol (HT) as a unique class of HIV-1 inhibitors from olive leaf extracts effective against viral fusion and integration. We used molecular docking simulation to study the interactions of Ole and HT with viral targets. We find that Ole and HT bind to the conserved hydrophobic pocket on the surface of the HIV-gp41 fusion domain by hydrogen bonds with Q577 and hydrophobic interactions with I573, G572, and L568 on the gp41 N-terminal heptad repeat peptide N36, interfering with formation of the gp41 fusion-active core. To test and confirm modeling predications, we examined the effect of Ole and HT on HIV-1 fusion complex formation using native polyacrylamide gel electrophoresis and circular dichroism spectroscopy. Ole and HT exhibit dose-dependent inhibition on HIV-1 fusion core formation with EC 50 s of 66-58 nM, with no detectable toxicity. Our findings on effects of HIV-1 integrase are reported in the subsequent article

  8. 17-AAG, an Hsp90 inhibitor, causes kinetochore defects: a novel mechanism by which 17-AAG inhibits cell proliferation.

    Science.gov (United States)

    Niikura, Y; Ohta, S; Vandenbeldt, K J; Abdulle, R; McEwen, B F; Kitagawa, K

    2006-07-13

    The Hsp90 inhibitor 17-allylaminogeldanamycin (17-AAG), which is currently in clinical trials, is thought to exert antitumor activity by simultaneously targeting several oncogenic signaling pathways. Here we report a novel mechanism by which 17-AAG inhibits cell proliferation, and we provide the first evidence that HSP90 is required for the assembly of kinetochore protein complexes in humans. 17-AAG caused delocalization of several kinetochore proteins including CENP-I and CENP-H but excluding CENP-B and CENP-C. Consistently, 17-AAG induced a mitotic arrest that depends on the spindle checkpoint and induced misalignment of chromosomes and aneuploidy. We found that HSP90 associates with SGT1 (suppressor of G2 allele of skp1; SUGT1) in human cells and that depletion of SGT1 sensitizes HeLa cells to 17-AAG. Overexpression of SGT1 restored the localization of specific kinetochore proteins and chromosome alignment in cells treated with 17-AAG. Biochemical and genetic results suggest that HSP90, through its interaction with SGT1 (SUGT1), is required for kinetochore assembly. Furthermore, time-course experiments revealed that transient treatment with 17-AAG between late S and G2/M phases causes substantial delocalization of CENP-H and CENP-I, a finding that strongly suggests that HSP90 participates in kinetochore assembly in a cell cycle-dependent manner.

  9. Inhibition of 5-Lipoxygenase inhibitor zileuton in high-fat diet-induced nonalcoholic fatty liver disease progression model

    Directory of Open Access Journals (Sweden)

    Kuifen Ma

    2017-11-01

    Full Text Available Objective(s: Arachidonic Acid/5-lipoxygenase (AA/5-LOX pathway connects lipid metabolism and proinflammatory cytokine, which are both related to the development and progression of nonalcoholic fatty liver disease (NAFLD. Therefore, the present study was designed to investigate the role of AA/5-LOX pathway in progression of NAFLD, and the effect of zileuton, an inhibitor of 5-LOX, in this model. Materials and Methods: Animal model for progression of NAFLD was established via feeding high saturated fat diet (HFD. Liver function, HE staining, NAFLD activity score (NAS were used to evaluate NAFLD progression. We detected the lipid metabolism substrates: free fatty acids (FFA and AA, products: cysteinyl-leukotrienes (CysLTs, and changes in gene and protein level of key enzyme in AA/5-LOX pathway including PLA2 and 5-LOX. Furthermore, we determined whether NAFLD progression pathway was delayed or reversed when zileuton (1-[1-(1-benzothiophen-2-ylethyl]-1-hydroxyurea was administrated. Results: Rat model for progression of NAFLD was well established as analyzed by liver transaminase activities, hematoxylin-eosin (HE staining and NAS. The concentrations of substrates and products in AA/5-LOX pathway were increased with the progression of NAFLD. mRNA and protein expression of PLA2 and 5-LOX were all enhanced. Moreover, administration of zileuton inhibited AA/5-LOX pathway and reversed the increased transamine activities and NAS. Conclusion: AA/5-LOX pathway promotes the progression of NAFLD, which can be reversed by zileuton.

  10. Inhibition of human immunodeficiency virus type 1 infection by the candidate microbicide dapivirine, a nonnucleoside reverse transcriptase inhibitor.

    Science.gov (United States)

    Fletcher, P; Harman, S; Azijn, H; Armanasco, N; Manlow, P; Perumal, D; de Bethune, M-P; Nuttall, J; Romano, J; Shattock, R

    2009-02-01

    Heterosexual transmission of human immunodeficiency virus (HIV) remains the major route of infection worldwide; thus, there is an urgent need for additional prevention strategies, particularly strategies that could be controlled by women, such as topical microbicides. Potential microbicide candidates must be both safe and effective. Using cellular and tissue explant models, we have evaluated the activity of the nonnucleoside reverse transcriptase inhibitor (NNRTI) dapivirine as a vaginal microbicide. In tissue compatibility studies, dapivirine was well tolerated by epithelial cells, T cells, macrophages, and cervical tissue explants. Dapivirine demonstrated potent dose-dependent inhibitory effects against a broad panel of HIV type 1 isolates from different clades. Furthermore, dapivirine demonstrated potent activity against a wide range of NNRTI-resistant isolates. In human cervical explant cultures, dapivirine was able not only to inhibit direct infection of mucosal tissue but also to prevent the dissemination of the virus by migratory cells. Activity was retained in the presence of semen or a cervical mucus simulant. Furthermore, dapivirine demonstrated prolonged inhibitory effects: it was able to prevent both localized and disseminated infection for as long as 6 days posttreatment. The prolonged protection observed following pretreatment of genital tissue and the lack of observable toxicity suggest that dapivirine has considerable promise as a potential microbicide candidate.

  11. Celecoxib promotes c-FLIP degradation through Akt-independent inhibition of GSK3.

    Science.gov (United States)

    Chen, Shuzhen; Cao, Wei; Yue, Ping; Hao, Chunhai; Khuri, Fadlo R; Sun, Shi-Yong

    2011-10-01

    Celecoxib is a COX-2 inhibitor that reduces the risk of colon cancer. However, the basis for its cancer chemopreventive activity is not fully understood. In this study, we defined a mechanism of celecoxib action based on degradation of cellular FLICE-inhibitory protein (c-FLIP), a major regulator of the death receptor pathway of apoptosis. c-FLIP protein levels are regulated by ubiquitination and proteasome-mediated degradation. We found that celecoxib controlled c-FLIP ubiquitination through Akt-independent inhibition of glycogen synthase kinase-3 (GSK3), itself a candidate therapeutic target of interest in colon cancer. Celecoxib increased the levels of phosphorylated GSK3, including the α and β forms, even in cell lines, where phosphorylated Akt levels were not increased. Phosphoinositide 3-kinase inhibitors abrogated Akt phosphorylation as expected but had no effect on celecoxib-induced GSK3 phosphorylation. In contrast, protein kinase C (PKC) inhibitors abolished celecoxib-induced GSK3 phosphorylation, implying that celecoxib influenced GSK3 phosphorylation through a mechanism that relied upon PKC and not Akt. GSK3 blockade either by siRNA or kinase inhibitors was sufficient to attenuate c-FLIP levels. Combining celecoxib with GSK3 inhibition enhanced attenuation of c-FLIP and increased apoptosis. Proteasome inhibitor MG132 reversed the effects of GSK3 inhibition and increased c-FLIP ubiquitination, confirming that c-FLIP attenuation was mediated by proteasomal turnover as expected. Our findings reveal a novel mechanism through which the regulatory effects of c-FLIP on death receptor signaling are controlled by GSK3, which celecoxib acts at an upstream level to control independently of Akt.

  12. Prevention of wear particle-induced osteolysis by a novel V-ATPase inhibitor saliphenylhalamide through inhibition of osteoclast bone resorption.

    Directory of Open Access Journals (Sweden)

    An Qin

    Full Text Available Wear particle-induced peri-implant loosening (Aseptic prosthetic loosening is one of the most common causes of total joint arthroplasty. It is well established that extensive bone destruction (osteolysis by osteoclasts is responsible for wear particle-induced peri-implant loosening. Thus, inhibition of osteoclastic bone resorption should prevent wear particle induced osteolysis and may serve as a potential therapeutic avenue for prosthetic loosening. Here, we demonstrate for the first time that saliphenylhalamide, a new V-ATPase inhibitor attenuates wear particle-induced osteolysis in a mouse calvarial model. In vitro biochemical and morphological assays revealed that the inhibition of osteolysis is partially attributed to a disruption in osteoclast acidification and polarization, both a prerequisite for osteoclast bone resorption. Interestingly, the V-ATPase inhibitor also impaired osteoclast differentiation via the inhibition of RANKL-induced NF-κB and ERK signaling pathways. In conclusion, we showed that saliphenylhalamide affected multiple physiological processes including osteoclast differentiation, acidification and polarization, leading to inhibition of osteoclast bone resorption in vitro and wear particle-induced osteolysis in vivo. The results of the study provide proof that the new generation V-ATPase inhibitors, such as saliphenylhalamide, are potential anti-resorptive agents for treatment of peri-implant osteolysis.

  13. [Dexamethasone and vorinostat cooperatively promote differentiation and apoptosis in Kasumi-1 leukemia cells through ubiquitination and degradation of AML1-ETO].

    Science.gov (United States)

    Chen, Li-ping; Zhang, Jian-wei; Xu, Fa-mei; Xing, Hai-yan; Tian, Zheng; Wang, Min; Wang, Jian-xiang

    2013-09-01

    To probe the effects of dexamethasone (DEX) combined with histone deacetylase (HDAC) inhibitor vorinostat on inhibiting proliferation and inducing differentiation and apoptosis in Kasumi-1 leukemia cells, and its possible mechanisms in order to provide a theoretical basis for the treatment of AML1-ETO positive AML. The cell survival, differentiation and apoptosis rates were tested by MTT or flow cytometry analysis after Kasumi-1 cells were treated by DMSO, DEX (20 nmol/L), vorinostat (1 μmol/L) or DEX (20 nmol/L) in combination with vorinostat (1 μmol/L). WB and IP-WB were performed to detect AML1-ETO and its ubiquitination. Treatment with the combination of DEX and vorinostat for 48 h led to statistically significant differences of inhibited proliferation [(42.06±8.20)%], increased differentiation [(52.83±8.97)%] and apoptosis [(52.92±2.53)%] of Kasumi-1 cells when compared with vorinostat [(33.82±9.41)%, (43.93±9.04)% and (42.98±3.01)%, respectively], DEX [(17.30±3.49)%, (22.53±4.51)% and (19.57±2.17)%, respectively] or control [(6.96±0.39)%, (21.73±2.03)% and (6.96±0.39)%, respectively]. Also significant ubiquitination and decreased AML1-ETO protein in Kasumi-1 cells after the combination treatment over single agent or control were observed. The results indicated that DEX and vorinostat could synergistically inhibit the Kasumi-1 cells proliferation, induce Kasumi-1 cells differentiation and apoptosis through ubiquitination and degradation of AML1-ETO.

  14. Withaferin A disrupts ubiquitin-based NEMO reorganization induced by canonical NF-κB signaling

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Shawn S. [McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, 6159 Wisconsin Institute for Medical Research, 1111 Highland Avenue, Madison, WI 53705 (United States); Medical Scientist Training Program, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705 (United States); Cellular and Molecular Biology Program, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705 (United States); Oberley, Christopher [McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, 6159 Wisconsin Institute for Medical Research, 1111 Highland Avenue, Madison, WI 53705 (United States); Hooper, Christopher P. [McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, 6159 Wisconsin Institute for Medical Research, 1111 Highland Avenue, Madison, WI 53705 (United States); Cellular and Molecular Biology Program, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705 (United States); Grindle, Kreg [Department of Medicine, Division of Hematology and Oncology, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705 (United States); Wuerzberger-Davis, Shelly [McArdle Laboratory for Cancer Research, Department of Oncology, University of Wisconsin-Madison, 6159 Wisconsin Institute for Medical Research, 1111 Highland Avenue, Madison, WI 53705 (United States); Wolff, Jared [Department of Medicine, Division of Hematology and Oncology, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705 (United States); and others

    2015-02-01

    The NF-κB family of transcription factors regulates numerous cellular processes, including cell proliferation and survival responses. The constitutive activation of NF-κB has also emerged as an important oncogenic driver in many malignancies, such as activated B-cell like diffuse large B cell lymphoma, among others. In this study, we investigated the impact and mechanisms of action of Withaferin A, a naturally produced steroidal lactone, against both signal-inducible as well as constitutive NF-κB activities. We found that Withaferin A is a robust inhibitor of canonical and constitutive NF-κB activities, leading to apoptosis of certain lymphoma lines. In the canonical pathway induced by TNF, Withaferin A did not disrupt RIP1 polyubiquitination or NEMO–IKKβ interaction and was a poor direct IKKβ inhibitor, but prevented the formation of TNF-induced NEMO foci which colocalized with TNF ligand. While GFP-NEMO efficiently formed TNF-induced foci, a GFP-NEMO{sup Y308S} mutant that is defective in binding to polyubiquitin chains did not form foci. Our study reveals that Withaferin A is a novel type of IKK inhibitor which acts by disrupting NEMO reorganization into ubiquitin-based signaling structures in vivo. - Highlights: • Withaferin A, a NF-κB inhibitor, disrupts signaling induced NEMO localization, a novel point of inhibition. • NEMO can be localized to distinct signaling foci after treatment with TNF. • ABC-type DLCBL cells can be sensitized to apoptosis after treatment with Withaferin A.

  15. Release Profile and Inhibition Test of The Nanoparticles A. Paniculata Extract as Inhibitor of α-Glucosidase in The Process of Carbohydrates Breakdown Into Glucose Diabetes Mellitus

    Science.gov (United States)

    Imansari, Farisa; Sahlan, Muhammad; Arbianti, Rita

    2017-07-01

    Andrographis paniculata (A.paniculata) contain the main active substances Andrographolide which helps lower glucose levels in diabetics by inhibiting the enzyme α-glucosidase. The ability of the extract A.paniculata in lowering glucose levels will increase with the technique encapsulation with a coating of composition Chitosan-STPP as a drug delivery to the target organ. This study aimed to get an overview of A.paniculata release profile of nanoparticles in a synthetic fluid media with various concentrations of coating and inhibition testing nasty shard extract in inhibiting the enzyme α-glucosidase. This research resulted in nanoparticles by coating efficiency and loading capacity of chitosan greatest variation of 2% and 1% STPP 60% and 46.29%. chitosan greatest variation of 2% and 1% STPP 60% and 46.29%. The ability of A.paniculata extracts as α-glucosidase enzyme inhibitors has been demonstrated in this study, the percent inhibition of 33.17%.

  16. Inhibition of X-ray and doxorubicin-induced apoptosis by butyrolactone I, a CDK-specific inhibitor, in human tumor cells

    International Nuclear Information System (INIS)

    Lu Yanjun; Takebe, Hiraku; Yagi, Takashi

    2000-01-01

    Cell-cycle progression is coordinately regulated by cyclin-dependent kinases (CDKs). The inhibition of CDKs by p21 wafl/Cipl/Sdil prevents the apoptosis of cells treated with DNA-damaging agents. In this study, we found that butyrolactone I, a specific inhibitor of CDC2 family kinases, blocks the X-ray- or doxorubicin-induced apoptosis of DLD1 (p21 +/+) human colorectal carcinoma cells in a dose-dependent manner. We also found that butyrolactone I inhibits the CDK2 activity and enhances cell survival after an X-ray irradiation or doxorubicin treatment in both DLD1 (p21 -/-) and DLD1 (p21 +/+) cells. These findings suggest that butyrolactone I prevents apoptosis by the direct inhibition of CDK and also, possibly, by CDK-inhibition through p53-independent p21-induction. Our findings indicate that CDK activity is required for DNA-damaging agent-induced apoptosis. (author)

  17. Inhibition of gamma-ray dose-rate effects by D2O and inhibitors of poly(ADP-ribose) synthetase in cultured mammalian L5178Y cells

    International Nuclear Information System (INIS)

    Ueno, A.M.; Tanaka, O.; Matsudaira, H.

    1984-01-01

    Effects of deuterium oxide (D 2 O) and 3-aminobenzamide, an inhibitor of poly(ADP-ribose) synthetase, on cell proliferation and survival were studied in cultured mammalian L5178Y cells under growing conditions and after acute and low-dose-rate irradiation at about 0.1 to 0.4 Gy/hr of γ rays. Growth of irradiated and unirradiated cells was inhibited by 45% D 2 O but not by 3-aminobenzamide at 10mM, except for treatments longer than 30 hr. The presence of these agents either alone or in combination during irradiation at low dose rates suppressed almost totally the decrease in cell killing due to the decrease in dose rate. Among other inhibitors tested, theobromine and theophylline were found to be effective in eliminating the dose-rate effects of γ rays. Possible mechanisms underlying the inhibition are discussed

  18. Inhibition of peripheral aromatization in baboons by an enzyme-activated aromatase inhibitor (MDL 18,962)

    International Nuclear Information System (INIS)

    Longcope, C.; Femino, A.; Johnston, J.O.

    1988-01-01

    The peripheral aromatization ([rho]BM) of androstenedione (A) and testosterone (T) was measured before and after administration of the aromatase inhibitor 10-(2 propynyl)estr-4-ene-3,17-dione (MDL-18,962) to five mature female baboons, Papio annubis. The measurements were made by infusing [3H]androstenedione/[14C]estrone or [3H]testosterone/[14C]estradiol for 3.5 h and collecting blood samples during the infusions and all urine for 96 h from the start of the infusion. Blood samples were analyzed for radioactivity as infused and product steroids, and the data were used to calculate MCRs. An aliquot of the pooled urine was analyzed for the glucuronides of estrone and estradiol and used to calculate the [rho]BM. MDL-18,962 was administered as a pulse in polyethylene glycol-400 (1-5 ml) either iv or via gastric tube 30 min before administration of the radiolabeled steroids. Control studies were done with and without polyethylene glycol-400 administration. When MDL-18,962 was given iv at 4 mg/kg, the aromatization of A was decreased 91.8 +/- 0.9% from the control value of 1.23 +/- 0.13% to 0.11 +/- 0.01%. At the same dose, aromatization of T was decreased 82.0 +/- 7.1%, from a control value of 0.20 +/- 0.03% to 0.037 +/- 0.018%. When MDL-18,962 was given iv at doses of 0.4, 0.1, 0.04, and 0.01 mg/kg, the values for aromatization of A were 0.16 +/- 0.03%, 0.18 +/- 0.06%, 0.37 +/- 11%, and 0.65 +/- 0.09%, respectively. The administration of MDL-18,962 via gastric tube at 4 mg/kg as a pulse decreased the aromatization of A from 1.35 +/- 0.06% to 0.43 +/- 0.12%, an inhibition of 67.2 +/- 10.7%. When administered via gastric tube daily for 5 days at 4 mg/kg, the aromatization of A fell from 1.35 +/- 0.06% to 0.063 +/- 0.003%, an inhibition of 84.4 +/- 0.5%

  19. The phosphatidylinositol 3-kinase inhibitor, wortmannin, inhibits insulin-induced activation of phosphatidylcholine hydrolysis and associated protein kinase C translocation in rat adipocytes.

    OpenAIRE

    Standaert, M L; Avignon, A; Yamada, K; Bandyopadhyay, G; Farese, R V

    1996-01-01

    We questioned whether phosphatidylinositol 3-kinase (PI 3-kinase) and protein kinase C (PKC) function as interrelated signalling mechanisms during insulin action in rat adipocytes. Insulin rapidly activated a phospholipase D that hydrolyses phosphatidylcholine (PC), and this activation was accompanied by increases in diacylglycerol and translocative activation of PKC-alpha and PKC-beta in the plasma membrane. Wortmannin, an apparently specific PI 3-kinase inhibitor, inhibited insulin-stimulat...

  20. Tau protein degradation is catalyzed by the ATP/ubiquitin-independent 20S proteasome under normal cell conditions

    OpenAIRE

    Grune, Tilman; Botzen, Diana; Engels, Martina; Voss, Peter; Kaiser, Barbara; Jung, Tobias; Grimm, Stefanie; Ermak, Gennady; Davies, Kelvin J. A.

    2010-01-01

    Tau is the major protein exhibiting intracellular accumulation in Alzheimer disease. The mechanisms leading to its accumulation are not fully understood. It has been proposed that the proteasome is responsible for degrading tau but, since proteasomal inhibitors block both the ubiquitin-dependent 26S proteasome and the ubiqutin-independent 20S proteasome pathways, it is not clear which of these pathways is involved in tau degradation. Some involvement of the ubiquitin ligase, CHIP in tau degra...

  1. AT-406, an orally active antagonist of multiple inhibitor of apoptosis proteins, inhibits progression of human ovarian cancer.

    Science.gov (United States)

    Brunckhorst, Melissa K; Lerner, Dimitry; Wang, Shaomeng; Yu, Qin

    2012-07-01

    Ovarian carcinoma is the most deadly gynecological malignancy. Current chemotherapeutic drugs are only transiently effective and patients with advance disease often develop resistance despite significant initial responses. Mounting evidence suggests that anti-apoptotic proteins, including those of the inhibitor of apoptosis protein (IAP) family, play important roles in the chemoresistance. There has been a recent emergence of compounds that block the IAP functions. Here, we evaluated AT-406, a novel and orally active antagonist of multiple IAP proteins, in ovarian cancer cells as a single agent and in the combination with carboplatin for therapeutic efficacy and mechanism of action. We demonstrate that AT-406 has significant single agent activity in 60% of human ovarian cancer cell lines examined in vitro and inhibits ovarian cancer progression in vivo and that 3 out of 5 carboplatin-resistant cell lines are sensitive to AT-406, highlighting the therapeutic potential of AT-406 for patients with inherent or acquired platinum resistance. Additionally, our in vivo studies show that AT-406 enhances the carboplatin-induced ovarian cancer cell death and increases survival of the experimental mice, suggesting that AT-406 sensitizes the response of these cells to carboplatin. Mechanistically, we demonstrate that AT-406 induced apoptosis is correlated with its ability to down-regulate XIAP whereas AT-406 induces cIAP1 degradation in both AT-406 sensitive and resistance cell lines. Together, these results demonstrate, for the first time, the anti-ovarian cancer efficacy of AT-406 as a single agent and in the combination with carboplatin, suggesting that AT-406 has potential as a novel therapy for ovarian cancer patients, especially for patients exhibiting resistance to the platinum-based therapies.

  2. Shutdown of interferon signaling by a viral-hijacked E3 ubiquitin ligase

    Directory of Open Access Journals (Sweden)

    Kaitlin A. Davis

    2017-11-01

    Full Text Available Viruses manipulate cellular processes to create an environment favorable to replication. For most viruses, this includes subverting the expression of interferon (IFN, a signaling molecule that can stimulate production of a vast array of antiviral gene products. Rotavirus, a segmented double-stranded RNA virus that causes acute gastroenteritis in infants and young children, inhibits IFN expression through its nonstructural protein NSP1. This viral protein stifles IFN expression by inducing the degradation of host factors that are necessary for upregulating the activity of IFN genes. In the case of nearly all human and porcine rotavirus strains, NSP1 induces the ubiquitination-dependent proteasomal degradation of β-transducin repeat containing protein (β-TrCP, a host factor that plays an essential role in activating the IFN-transcription factor, NF-κB. Key to the process is the presence of a decoy sequence (degron at the C-terminus of NSP1 that causes β-TrCP to mistakenly bind NSP1 instead of its natural target, inhibitor-of-κB (IκB. In a recent report published by Davis et al [2017; mBio 8(4: e01213-17], we describe molecular requirements that govern NSP1 recognition of β-TrCP, including an essential degron phosphorylation event, and the step-wise incorporation of NSP1 into hijacked cullin-RING E3 ligases (CRLs that ubiquitinate and tag β-TrCP for degradation. Notably, although β-TrCP is chiefly recognized for its role as a master regulator of NF-κB signaling and IFN expression, β-TrCP also controls the stability of checkpoint proteins implicated in numerous other cellular pathways with antiviral activities, including autophagy and apoptosis. Thus, the impact of NSP1 on creating an intracellular environment favorable to virus replication may extend well beyond the IFN signaling pathway.

  3. ERK5 signaling gets XIAPed: a role for ubiquitin in the disassembly of a MAPK cascade

    Science.gov (United States)

    Klein, Aileen M; Cobb, Melanie H

    2014-01-01

    Mitogen-activated protein kinase (MAPK) cascades are tightly controlled through a series of well-characterized phospho-regulatory events. In this issue, Takeda et al (2014) identify the inhibitor of apoptosis protein, XIAP, as a key regulator of ERK5 activation via uncoupling of upstream kinase activity by non-degradative ubiquitination. PMID:25012518

  4. Inhibiting properties and adsorption of an amine based fatty acid corrosion inhibitor on carbon steel in aqueous carbon dioxide solutions

    Energy Technology Data Exchange (ETDEWEB)

    Buchweishaija, Joseph

    1997-12-31

    Carbon dioxide corrosion is a major corrosion problem in oil and gas production systems and many organic inhibitors have been tested and used to protect the substrate from corrosion. This thesis studies the mechanism of interaction of the inhibitor molecule with the metallic substrate and how this affects the dissolution rate of the metal. The performance of a commercial amine based fatty acid corrosion inhibitor has been investigated using rotating cylinder electrodes and carbon steel electrodes in CO{sub 2} saturated formation water in the temperature range between 35 to 80{sup o}C. The corrosion process was monitored by electrochemical impedance measurements, and at the end of each experiment full polarization curves were recorded. When the inhibitor was applied on noncorroded electrodes, high inhibitor performance, over 99.7%, was observed independent of temperature. On precorroded electrodes inhibitor performance was found to depend on temperature and time of precorrosion. Above 60{sup o}C, the inhibitor performance decreased with increasing time of precorrosion, presumably because of the formation of a corrosion film of either iron carbonate or a combination of iron carbonate and iron carbide which prevent the inhibitor from reaching the surface. The inhibitor protection efficiency was assumed to be associated with the degree of inhibitor coverage at the material surface, and adsorption isotherms have been calculated in the concentration range between 0.1 ppm and 100 ppm. A Langmuir isotherm was found to give the best fit. The inhibitor performance on a 2 days precorroded rotating electrode was investigated at different solution pH ranging between 4.5 and 6.5 at 35{sup o}C. 130 refs., 80 figs., 22 tabs.

  5. The phosphatidylinositol 3-kinase inhibitor, wortmannin, inhibits insulin-induced activation of phosphatidylcholine hydrolysis and associated protein kinase C translocation in rat adipocytes.

    Science.gov (United States)

    Standaert, M L; Avignon, A; Yamada, K; Bandyopadhyay, G; Farese, R V

    1996-02-01

    We questioned whether phosphatidylinositol 3-kinase (PI 3-kinase) and protein kinase C (PKC) function as interrelated signalling mechanisms during insulin action in rat adipocytes. Insulin rapidly activated a phospholipase D that hydrolyses phosphatidylcholine (PC), and this activation was accompanied by increases in diacylglycerol and translocative activation of PKC-alpha and PKC-beta in the plasma membrane. Wortmannin, an apparently specific PI 3-kinase inhibitor, inhibited insulin-stimulated, phospholipase D-dependent PC hydrolysis and subsequent translocation of PKC-alpha and PKC-beta to the plasma membrane. Wortmannin did not inhibit PKC directly in vitro, or the PKC-dependent effects of phorbol esters on glucose transport in intact adipocytes. The PKC inhibitor RO 31-8220 did not inhibit PI 3-kinase directly or its activation in situ by insulin, but inhibited both insulin-stimulated and phorbol ester-stimulated glucose transport. Our findings suggest that insulin acts through PI 3-kinase to activate a PC-specific phospholipase D and causes the translocative activation of PKC-alpha and PKC-beta in plasma membranes of rat adipocytes.

  6. L-Chicoric acid inhibits human immunodeficiency virus type 1 integration in vivo and is a noncompetitive but reversible inhibitor of HIV-1 integrase in vitro

    International Nuclear Information System (INIS)

    Reinke, Ryan A.; Lee, Deborah J.; McDougall, Brenda R.; King, Peter J.; Victoria, Joseph; Mao Yingqun; Lei Xiangyang; Reinecke, Manfred G.; Robinson, W. Edward

    2004-01-01

    The human immunodeficiency virus (HIV) integrase (IN) must covalently join the viral cDNA into a host chromosome for productive HIV infection. L-Chicoric acid (L-CA) enters cells poorly but is a potent inhibitor of IN in vitro. Using quantitative real-time polymerase chain reaction (PCR), L-CA inhibits integration at concentrations from 500 nM to 10 μM but also inhibits entry at concentrations above 1 μM. Using recombinant HIV IN, steady-state kinetic analyses with L-CA were consistent with a noncompetitive or irreversible mechanism of inhibition. IN, in the presence or absence of L-CA, was successively washed. Inhibition of IN diminished, demonstrating that L-CA was reversibly bound to the protein. These data demonstrate that L-CA is a noncompetitive but reversible inhibitor of IN in vitro and of HIV integration in vivo. Thus, L-CA likely interacts with amino acids other than those which bind substrate

  7. IFT20 modulates ciliary PDGFRα signaling by regulating the stability of Cbl E3 ubiquitin ligases

    DEFF Research Database (Denmark)

    Schmid, Fabian Marc; Schou, Kenneth Bødtker; Vilhelm, Martin Juel

    2018-01-01

    ciliogenesis, and ciliary localization of the receptor is required for its appropriate ligand-mediated activation by PDGF-AA. However, the mechanisms regulating sorting of PDGFRα and feedback inhibition of PDGFRα signaling at the cilium are unknown. Here, we provide evidence that intraflagellar transport...... protein 20 (IFT20) interacts with E3 ubiquitin ligases c-Cbl and Cbl-b and is required for Cbl-mediated ubiquitination and internalization of PDGFRα for feedback inhibition of receptor signaling. In wild-type cells treated with PDGF-AA, c-Cbl becomes enriched in the cilium, and the receptor...

  8. Ubiquitination in Periodontal Disease: A Review.

    Science.gov (United States)

    Tsuchida, Sachio; Satoh, Mamoru; Takiwaki, Masaki; Nomura, Fumio

    2017-07-10

    Periodontal disease (periodontitis) is a chronic inflammatory condition initiated by microbial infection that leads to gingival tissue destruction and alveolar bone resorption. The periodontal tissue's response to dental plaque is characterized by the accumulation of polymorphonuclear leukocytes, macrophages, and lymphocytes, all of which release inflammatory mediators and cytokines to orchestrate the immunopathogenesis of periodontal disease. Ubiquitination is achieved by a mechanism that involves a number of factors, including an ubiquitin-activating enzyme, ubiquitin-conjugating enzyme, and ubiquitin-protein ligase. Ubiquitination is a post-translational modification restricted to eukaryotes that are involved in essential host processes. The ubiquitin system has been implicated in the immune response, development, and programmed cell death. Increasing numbers of recent reports have provided evidence that many approaches are delivering promising reports for discovering the relationship between ubiquitination and periodontal disease. The scope of this review was to investigate recent progress in the discovery of ubiquitinated protein in diseased periodontium and to discuss the ubiquitination process in periodontal diseases.

  9. Auto-ubiquitination of Mdm2 Enhances Its Substrate Ubiquitin Ligase Activity*

    Science.gov (United States)

    Ranaweera, Ruchira S.; Yang, Xiaolu

    2013-01-01

    The RING domain E3 ubiquitin ligase Mdm2 is the master regulator of the tumor suppressor p53. It targets p53 for proteasomal degradation, restraining the potent activity of p53 and enabling cell survival and proliferation. Like most E3 ligases, Mdm2 can also ubiquitinate itself. How Mdm2 auto-ubiquitination may influence its substrate ubiquitin ligase activity is undefined. Here we show that auto-ubiquitination of Mdm2 is an activating event. Mdm2 that has been conjugated to polyubiquitin chains, but not to single ubiquitins, exhibits substantially enhanced activity to polyubiquitinate p53. Mechanistically, auto-ubiquitination of Mdm2 facilitates the recruitment of the E2 ubiquitin-conjugating enzyme. This occurs through noncovalent interactions between the ubiquitin chains on Mdm2 and the ubiquitin binding domain on E2s. Mutations that diminish the noncovalent interactions render auto-ubiquitination unable to stimulate Mdm2 substrate E3 activity. These results suggest a model in which polyubiquitin chains on an E3 increase the local concentration of E2 enzymes and permit the processivity of substrate ubiquitination. They also support the notion that autocatalysis may be a prevalent mode for turning on the activity of latent enzymes. PMID:23671280

  10. Multi-tyrosine kinase inhibitors in preclinical studies for pediatric CNS AT/RT: Evidence for synergy with Topoisomerase-I inhibition

    Directory of Open Access Journals (Sweden)

    Jayanthan Aarthi

    2011-12-01

    Full Text Available Abstract Background Currently, Atypical Teratoid Rhabdoid Tumor (AT/RT constitutes one of the most difficult to treat malignancies in pediatrics. Hence, new knowledge of potential targets for therapeutics and the development of novel treatment approaches are urgently needed. We have evaluated the presence of cytokine pathways and the effects of two clinically available multi-tyrosine kinase inhibitors for cytotoxicity, target modulation and drug combinability against AT/RT cell lines. Results AT/RT cell lines expressed measurable quantities of VEGF, FGF, PDGF and SDF-1, although the absolute amounts varied between the cell lines. The targeted receptor tyrosine kinase inhibitor sorafenib inhibited the key signaling molecule Erk, which was activated following the addition of own conditioned media, suggesting the existence of autocrine/paracrine growth stimulatory pathways. The multi-tyrosine kinase inhibitors sorafenib and sunitinib also showed significant growth inhibition of AT/RT cells and their activity was enhanced by combination with the topoisomerase inhibitor, irinotecan. The loss of cytoplasmic NF-kappa-B in response to irinotecan was diminished by sorafenib, providing evidence for a possible benefit for this drug combination. Conclusions In addition to previously described involvement of insulin like growth factor (IGF family of cytokines, a multitude of other growth factors may contribute to the growth and survival of AT/RT cells. However, consistent with the heterogeneous nature of this tumor, quantitative and qualitative differences may exist among different tumor samples. Multi-tyrosine kinase inhibitors appear to have effective antitumor activity against all cell lines studied. In addition, the target modulation studies and drug combinability data provide the groundwork for additional studies and support the evaluation of these agents in future treatment protocols.

  11. Administration of PDE4 Inhibitors Suppressed the Pannus-Like Inflammation by Inhibition of Cytokine Production by Macrophages and Synovial Fibroblast Proliferation

    Directory of Open Access Journals (Sweden)

    Katsuya Kobayashi

    2007-01-01

    Full Text Available A marked proliferation of synovial fibroblasts in joints leads to pannus formation in rheumatoid arthritis (RA. Various kinds of cytokines are produced in the pannus. The purpose of this study is to elucidate the effects of phosphodiesterase 4 (PDE4 inhibitors in a new animal model for the evaluation of pannus formation and cytokine production in the pannus. Mice sensitized with methylated bovine serum albumin (mBSA were challenged by subcutaneous implantation of a membrane filter soaked in mBSA solution in the back of the mice. Drugs were orally administered for 10 days. The granuloma formed around the filter was collected on day 11. It was chopped into pieces and cultured in vitro for 24 hr. The cytokines were measured in the supernatants. The type of cytokines produced in the granuloma was quite similar to those produced in pannus in RA. Both PDE4 inhibitors, KF66490 and SB207499, suppressed the production of IL-1β, TNF-α, and IL-12, and the increase in myeloperoxidase activity, a marker enzyme for neutrophils and hydroxyproline content. Compared to leflunomide, PDE4 inhibitors more strongly suppressed IL-12 production and the increase in myeloperoxidase activity. PDE4 inhibitors also inhibited lipopolysaccharide-induced TNF-α and IL-12 production from thioglycolate-induced murine peritoneal macrophages and the proliferation of rat synovial fibroblasts. These results indicate this model makes it easy to evaluate the effect of drugs on various cytokine productions in a granuloma without any purification step and may be a relevant model for evaluating novel antirheumatic drugs on pannus formation in RA. PDE4 inhibitors could have therapeutic effects on pannus formation in RA by inhibition of cytokine production by macrophages and synovial fibroblast proliferation.

  12. Administration of PDE4 inhibitors suppressed the pannus-like inflammation by inhibition of cytokine production by macrophages and synovial fibroblast proliferation.

    Science.gov (United States)

    Kobayashi, Katsuya; Suda, Toshio; Manabe, Haruhiko; Miki, Ichiro

    2007-01-01

    A marked proliferation of synovial fibroblasts in joints leads to pannus formation in rheumatoid arthritis (RA). Various kinds of cytokines are produced in the pannus. The purpose of this study is to elucidate the effects of phosphodiesterase 4 (PDE4) inhibitors in a new animal model for the evaluation of pannus formation and cytokine production in the pannus. Mice sensitized with methylated bovine serum albumin (mBSA) were challenged by subcutaneous implantation of a membrane filter soaked in mBSA solution in the back of the mice. Drugs were orally administered for 10 days. The granuloma formed around the filter was collected on day 11. It was chopped into pieces and cultured in vitro for 24 hr. The cytokines were measured in the supernatants. The type of cytokines produced in the granuloma was quite similar to those produced in pannus in RA. Both PDE4 inhibitors, KF66490 and SB207499, suppressed the production of IL-1beta, TNF-alpha, and IL-12, and the increase in myeloperoxidase activity, a marker enzyme for neutrophils and hydroxyproline content. Compared to leflunomide, PDE4 inhibitors more strongly suppressed IL-12 production and the increase in myeloperoxidase activity. PDE4 inhibitors also inhibited lipopolysaccharide-induced TNF-alpha and IL-12 production from thioglycolate-induced murine peritoneal macrophages and the proliferation of rat synovial fibroblasts. These results indicate this model makes it easy to evaluate the effect of drugs on various cytokine productions in a granuloma without any purification step and may be a relevant model for evaluating novel antirheumatic drugs on pannus formation in RA. PDE4 inhibitors could have therapeutic effects on pannus formation in RA by inhibition of cytokine production by macrophages and synovial fibroblast proliferation.

  13. New in vitro model for proarrhythmia safety screening: IKs inhibition potentiates the QTc prolonging effect of IKr inhibitors in isolated guinea pig hearts.

    Science.gov (United States)

    Kui, Péter; Orosz, Szabolcs; Takács, Hedvig; Sarusi, Annamária; Csík, Norbert; Rárosi, Ferenc; Csekő, Csongor; Varró, András; Papp, Julius Gy; Forster, Tamás; Farkas, Attila S; Farkas, András

    2016-01-01

    Preclinical in vivo QT measurement as a proarrhythmia essay is expensive and not reliable enough. The aim of the present study was to develop a sensitive, cost-effective, Langendorff perfused guinea pig heart model for proarrhythmia safety screening. Low concentrations of dofetilide and cisapride (inhibitors of the rapid delayed rectifier potassium current, IKr) were tested alone and co-perfused with HMR-1556 (inhibitor of the slow delayed rectifier potassium current, IKs) in Langendorff perfused guinea pig hearts. The electrocardiographic rate corrected QT (QTc) interval, the Tpeak-Tend interval and the beat-to-beat variability and instability (BVI) of the QT interval were determined in sinus rhythm. Dofetilide and HMR-1556 alone or co-perfused, prolonged the QTc interval by 20±2%, 10±1% and 55±10%, respectively. Similarly, cisapride and HMR-1556 alone or co-perfused, prolonged the QTc interval by 11±3%, 11±4% and 38±6%, respectively. Catecholamine-induced fast heart rate abolished the QTc prolonging effects of the IKr inhibitors, but augmented the QTc prolongation during IKs inhibition. None of the drug perfusions increased significantly the Tpeak-Tend interval and the sinus BVI of the QT interval. IKs inhibition increased the QTc prolonging effect of IKr inhibitors in a super-additive (synergistic) manner, and the QTc interval was superior to other proarrhythmia biomarkers measured in sinus rhythm in isolated guinea pig hearts. The effect of catecholamines on the QTc facilitated differentiation between IKr and IKs inhibitors. Thus, QTc measurement in Langendorff perfused guinea pig hearts with pharmacologically attenuated repolarization reserve and periodic catecholamine perfusion seems to be suitable for preclinical proarrhythmia screening. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Regulation of synaptic structure by ubiquitin C-terminal hydrolase L1.

    Science.gov (United States)

    Cartier, Anna E; Djakovic, Stevan N; Salehi, Afshin; Wilson, Scott M; Masliah, Eliezer; Patrick, Gentry N

    2009-06-17

    Ubiquitin C-terminal hydrolase L1 (UCH-L1) is a deubiquitinating enzyme that is selectively and abundantly expressed in the brain, and its activity is required for normal synaptic function. Here, we show that UCH-L1 functions in maintaining normal synaptic structure in hippocampal neurons. We found that UCH-L1 activity is rapidly upregulated by NMDA receptor activation, which leads to an increase in the levels of free monomeric ubiquitin. Conversely, pharmacological inhibition of UCH-L1 significantly reduces monomeric ubiquitin levels and causes dramatic alterations in synaptic protein distribution and spine morphology. Inhibition of UCH-L1 activity increases spine size while decreasing spine density. Furthermore, there is a concomitant increase in the size of presynaptic and postsynaptic protein clusters. Interestingly, however, ectopic expression of ubiquitin restores normal synaptic structure in UCH-L1-inhibited neurons. These findings point to a significant role of UCH-L1 in synaptic remodeling, most likely by modulating free monomeric ubiquitin levels in an activity-dependent manner.

  15. Regulation of Synaptic Structure by the Ubiquitin C-terminal Hydrolase UCH-L1

    Science.gov (United States)

    Cartier, Anna E.; Djakovic, Stevan N.; Salehi, Afshin; Wilson, Scott M.; Masliah, Eliezer; Patrick, Gentry N.

    2009-01-01

    UCH-L1 is a de-ubiquitinating enzyme that is selectively and abundantly expressed in the brain, and its activity is required for normal synaptic function. Here, we show that UCH-L1 functions in maintaining normal synaptic structure in hippocampal neurons. We have found that UCH-L1 activity is rapidly up-regulated by NMDA receptor activation which leads to an increase in the levels of free monomeric ubiquitin. Conversely, pharmacological inhibition of UCH-L1 significantly reduces monomeric ubiquitin levels and causes dramatic alterations in synaptic protein distribution and spine morphology. Inhibition of UCH-L1 activity increases spine size while decreasing spine density. Furthermore, there is a concomitant increase in the size of pre and postsynaptic protein clusters. Interestingly, however, ectopic expression of ubiquitin restores normal synaptic structure in UCH-L1 inhibited neurons. These findings point to a significant role of UCH-L1 in synaptic remodeling most likely by modulating free monomeric ubiquitin levels in an activity-dependent manner. PMID:19535597

  16. The calmodulin inhibitor CGS 9343B inhibits voltage-dependent K{sup +} channels in rabbit coronary arterial smooth muscle cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongliang; Hong, Da Hye; Kim, Han Sol; Kim, Hye Won [Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 200-701 (Korea, Republic of); Jung, Won-Kyo [Department of Biomedical Engineering, Center for Marine-Integrated Biomedical Technology (BK21 Plus), Pukyong National University, Busan 608-737 (Korea, Republic of); Na, Sung Hun [Institute of Medical Sciences, Department of Obstetrics and Gynecology, Kangwon National University Hospital, School of Medicine, Kangwon National University, Chuncheon, 200-701 (Korea, Republic of); Jung, In Duk; Park, Yeong-Min [Department of Immunology, Lab of Dendritic Cell Differentiation and Regulation, College of Medicine, Konkuk University, Chungju 380-701 (Korea, Republic of); Choi, Il-Whan, E-mail: cihima@inje.ac.kr [Department of Microbiology, Inje University College of Medicine, Busan, 614-735 (Korea, Republic of); Park, Won Sun, E-mail: parkws@kangwon.ac.kr [Institute of Medical Sciences, Department of Physiology, Kangwon National University School of Medicine, Chuncheon, 200-701 (Korea, Republic of)

    2015-06-15

    We investigated the effects of the calmodulin inhibitor CGS 9343B on voltage-dependent K{sup +} (Kv) channels using whole-cell patch clamp technique in freshly isolated rabbit coronary arterial smooth muscle cells. CGS 9343B inhibited Kv currents in a concentration-dependent manner, with a half-maximal inhibitory concentration (IC{sub 50}) value of 0.81 μM. The decay rate of Kv channel inactivation was accelerated by CGS 9343B. The rate constants of association and dissociation for CGS 9343B were 2.77 ± 0.04 μM{sup −1} s{sup −1} and 2.55 ± 1.50 s{sup −1}, respectively. CGS 9343B did not affect the steady-state activation curve, but shifted the inactivation curve toward to a more negative potential. Train pulses (1 or 2 Hz) application progressively increased the CGS 9343B-induced Kv channel inhibition. In addition, the inactivation recovery time constant was increased in the presence of CGS 9343B, suggesting that CGS 9343B-induced inhibition of Kv channel was use-dependent. Another calmodulin inhibitor, W-13, did not affect Kv currents, and did not change the inhibitory effect of CGS 9343B on Kv current. Our results demonstrated that CGS 9343B inhibited Kv currents in a state-, time-, and use-dependent manner, independent of calmodulin inhibition. - Highlights: • We investigated the effects of CGS 9394B on Kv channels. • CGS 9394B inhibited Kv current in a state-, time-, and use-dependent manner. • Caution is required when using CGS 9394B in vascular function studies.

  17. Sensitization of multidrug-resistant human cancer cells to Hsp90 inhibitors by down-regulation of SIRT1

    Science.gov (United States)

    Kim, Hak-Bong; Lee, Su-Hoon; Um, Jee-Hyun; Oh, Won Keun; Kim, Dong-Wan; Kang, Chi-Dug; Kim, Sun-Hee

    2015-01-01

    The effectiveness of Hsp90 inhibitors as anticancer agents was limited in multidrug-resistant (MDR) human cancer cells due to induction of heat shock proteins (Hsps) such as Hsp70/Hsp27 and P-glycoprotein (P-gp)-mediated efflux. In the present study, we showed that resistance to Hsp90 inhibitors of MDR human cancer cells could be overcome with SIRT1 inhibition. SIRT1 knock-down or SIRT1 inhibitors (amurensin G and EX527) effectively suppressed the resistance to Hsp90 inhibitors (17-AAG and AUY922) in several MDR variants of human lymphoblastic leukemia and human breast cancer cell lines. SIRT1 inhibition down-regulated the expression of heat shock factor 1 (HSF1) and subsequently Hsps and facilitated Hsp90 multichaperone complex disruption via hyperacetylation of Hsp90/Hsp70. These findings were followed by acceleration of ubiquitin ligase CHIP-mediated mutant p53 (mut p53) degradation and subsequent down-regulation of P-gp in 17-AAG-treated MDR cancer cells expressing P-gp and mut p53 after inhibition of SIRT1. Therefore, combined treatment with Hsp90 inhibitor and SIRT1 inhibitor could be a more effective therapeutic approach for Hsp90 inhibitor-resistant MDR cells via down-regulation of HSF1/Hsps, mut p53 and P-gp. PMID:26416354

  18. Allosteric inhibition enhances the efficacy of ABL kinase inhibitors to target unmutated BCR-ABL and BCR-ABL-T315I

    Directory of Open Access Journals (Sweden)

    Mian Afsar

    2012-09-01

    Full Text Available Abstract Background Chronic myelogenous leukemia (CML and Philadelphia chromosome-positive (Ph+ acute lymphatic leukemia (Ph + ALL are caused by the t(9;22, which fuses BCR to ABL resulting in deregulated ABL-tyrosine kinase activity. The constitutively activated BCR/ABL-kinase “escapes” the auto-inhibition mechanisms of c-ABL, such as allosteric inhibition. The ABL-kinase inhibitors (AKIs Imatinib, Nilotinib or Dasatinib, which target the ATP-binding site, are effective in Ph + leukemia. Another molecular therapy approach targeting BCR/ABL restores allosteric inhibition. Given the fact that all AKIs fail to inhibit BCR/ABL harboring the ‘gatekeeper’ mutation T315I, we investigated the effects of AKIs in combination with the allosteric inhibitor GNF2 in Ph + leukemia. Methods The efficacy of this approach on the leukemogenic potential of BCR/ABL was studied in Ba/F3 cells, primary murine bone marrow cells, and untransformed Rat-1 fibroblasts expressing BCR/ABL or BCR/ABL-T315I as well as in patient-derived long-term cultures (PDLTC from Ph + ALL-patients. Results Here, we show that GNF-2 increased the effects of AKIs on unmutated BCR/ABL. Interestingly, the combination of Dasatinib and GNF-2 overcame resistance of BCR/ABL-T315I in all models used in a synergistic manner. Conclusions Our observations establish a new approach for the molecular targeting of BCR/ABL and its resistant mutants using a combination of AKIs and allosteric inhibitors.

  19. Molecular insights into human monoamine oxidase (MAO) inhibition by 1,4-naphthoquinone: evidences for menadione (vitamin K3) acting as a competitive and reversible inhibitor of MAO.

    Science.gov (United States)

    Coelho Cerqueira, Eduardo; Netz, Paulo Augusto; Diniz, Cristiane; Petry do Canto, Vanessa; Follmer, Cristian

    2011-12-15

    Monoamine oxidase (MAO) catalyzes the oxidative deamination of biogenic and exogenous amines and its inhibitors have therapeutic value for several conditions including affective disorders, stroke, neurodegenerative diseases and aging. The discovery of 2,3,6-trimethyl-1,4-naphthoquinone (TMN) as a nonselective and reversible inhibitor of MAO, has suggested 1,4-naphthoquinone (1,4-NQ) as a potential scaffold for designing new MAO inhibitors. Combining molecular modeling tools and biochemical assays we evaluate the kinetic and molecular details of the inhibition of human MAO by 1,4-NQ, comparing it with TMN and menadione. Menadione (2-methyl-1,4-naphthoquinone) is a multitarget drug that acts as a precursor of vitamin K and an inducer of mitochondrial permeability transition. Herein we show that MAO-B was inhibited competitively by 1,4-NQ (K(i)=1.4 μM) whereas MAO-A was inhibited by non-competitive mechanism (K(i)=7.7 μM). Contrasting with TMN and 1,4-NQ, menadione exhibited a 60-fold selectivity for MAO-B (K(i)=0.4 μM) in comparison with MAO-A (K(i)=26 μM), which makes it as selective as rasagiline. Fluorescence and molecular modeling data indicated that these inhibitors interact with the flavin moiety at the active site of the enzyme. Additionally, docking studies suggest the phenyl side groups of Tyr407 and Tyr444 (for MAO-A) or Tyr398 and Tyr435 (for MAO-B) play an important role in the interaction of the enzyme with 1,4-NQ scaffold through forces of dispersion as verified for menadione, TMN and 1,4-NQ. Taken together, our findings reveal the molecular details of MAO inhibition by 1,4-NQ scaffold and show for the first time that menadione acts as a competitive and reversible inhibitor of human MAO. Copyright © 2011 Elsevier Ltd. All rights reserved.

  20. Ubiquitin-Like Protein from Human Placental Extract Exhibits Collagenase Activity

    Science.gov (United States)

    De, Debashree; Datta Chakraborty, Piyali; Mitra, Jyotirmoy; Sharma, Kanika; Mandal, Somnath; Das, Aneesha; Chakrabarti, Saikat; Bhattacharyya, Debasish

    2013-01-01

    An aqueous extract of human placenta exhibits strong gelatinase/collagenase activity in zymography. 2-D gel electrophoresis of the extract with gelatin zymography in the second dimension displayed a single spot, identified as ubiquitin-like component upon MALDI/TOF MS/MS analysis. Immunoblot indicated presence of ubiquitin and absence of collagenase in the extract. Collagenase activity of the ubiquitin-like component was confirmed from the change in solubility of collagen in aqueous buffer, degradation of collagen by size-exclusion HPLC and atomic force microscopy. Quantification with DQ-gelatin showed that the extract contains 0.04 U/ml of collagenase activity that was inhibited up to 95% by ubiquitin antibody. Ubiquitin from bovine erythrocytes demonstrated mild collagenase activity. Bioinformatics studies suggest that placental ubiquitin and collagenase follow structurally divergent evolution. This thermostable intrinsic collagenase activity of placental extract might have wide physiological relevance in degrading and remodeling collagen as it is used as a drug for wound healing and pelvic inflammatory diseases. PMID:23555718

  1. Inhibition of colony-stimulating-factor-1 signaling in vivo with the orally bioavailable cFMS kinase inhibitor GW2580.

    Science.gov (United States)

    Conway, James G; McDonald, Brad; Parham, Janet; Keith, Barry; Rusnak, David W; Shaw, Eva; Jansen, Marilyn; Lin, Peiyuan; Payne, Alan; Crosby, Renae M; Johnson, Jennifer H; Frick, Lloyd; Lin, Min-Hwa Jasmine; Depee, Scott; Tadepalli, Sarva; Votta, Bart; James, Ian; Fuller, Karen; Chambers, Timothy J; Kull, Frederick C; Chamberlain, Stanley D; Hutchins, Jeff T

    2005-11-01

    Colony-stimulating-factor-1 (CSF-1) signaling through cFMS receptor kinase is increased in several diseases. To help investigate the role of cFMS kinase in disease, we identified GW2580, an orally bioavailable inhibitor of cFMS kinase. GW2580 completely inhibited human cFMS kinase in vitro at 0.06 microM and was inactive against 26 other kinases. GW2580 at 1 microM completely inhibited CSF-1-induced growth of mouse M-NFS-60 myeloid cells and human monocytes and completely inhibited bone degradation in cultures of human osteoclasts, rat calvaria, and rat fetal long bone. In contrast, GW2580 did not affect the growth of mouse NS0 lymphoblastoid cells, human endothelial cells, human fibroblasts, or five human tumor cell lines. GW2580 also did not affect lipopolysaccharide (LPS)-induced TNF, IL-6, and prostaglandin E2 production in freshly isolated human monocytes and mouse macrophages. After oral administration, GW2580 blocked the ability of exogenous CSF-1 to increase LPS-induced IL-6 production in mice, inhibited the growth of CSF-1-dependent M-NFS-60 tumor cells in the peritoneal cavity, and diminished the accumulation of macrophages in the peritoneal cavity after thioglycolate injection. Unexpectedly, GW2580 inhibited LPS-induced TNF production in mice, in contrast to effects on monocytes and macrophages in vitro. In conclusion, GW2580's selective inhibition of monocyte growth and bone degradation is consistent with cFMS kinase inhibition. The ability of GW2580 to chronically inhibit CSF-1 signaling through cFMS kinase in normal and tumor cells in vivo makes GW2580 a useful tool in assessing the role of cFMS kinase in normal and disease processes.

  2. A new class of HIV-1 protease inhibitor: the crystallographic structure, inhibition and chemical synthesis of an aminimide peptide isostere.

    Science.gov (United States)

    Rutenber, E E; McPhee, F; Kaplan, A P; Gallion, S L; Hogan, J C; Craik, C S; Stroud, R M

    1996-09-01

    The essential role of HIV-1 protease (HIV-1 PR) in the viral life cycle makes it an attractive target for the development of substrate-based inhibitors that may find efficacy as anti-AIDS drugs. However, resistance has arisen to potent peptidomimetic drugs necessitating the further development of novel chemical backbones for diversity based chemistry focused on probing the active site for inhibitor interactions and binding modes that evade protease resistance. AQ148 is a potent inhibitor of HIV-1 PR and represents a new class of transition state analogues incorporating an aminimide peptide isostere. A 3-D crystallographic structure of AQ148, a tetrapeptide isostere, has been determined in complex with its target HIV-1 PR to a resolution of 2.5 A and used to evaluate the specific structural determinants of AQ148 potency and to correlate structure-activity relationships within the class of related compounds. AQ148 is a competitive inhibitor of HIV-1 PR with a Ki value of 137 nM. Twenty-nine derivatives have been synthesized and chemical modifications have been made at the P1, P2, P1', and P2' sites. The atomic resolution structure of AQ148 bound to HIV-1 PR reveals both an inhibitor binding mode that closely resembles that of other peptidomimetic inhibitors and specific protein/inhibitor interactions that correlate with structure-activity relationships. The structure provides the basis for the design, synthesis and evaluation of the next generation of hydroxyethyl aminimide inhibitors. The aminimide peptide isostere is a scaffold with favorable biological properties well suited to both the combinatorial methods of peptidomimesis and the rational design of potent and specific substrate-based analogues.

  3. Inhibition of ErbB2 by receptor tyrosine kinase inhibitors causes myofibrillar structural damage without cell death in adult rat cardiomyocytes

    International Nuclear Information System (INIS)

    Pentassuglia, Laura; Graf, Michael; Lane, Heidi; Kuramochi, Yukio; Cote, Gregory; Timolati, Francesco; Sawyer, Douglas B.; Zuppinger, Christian; Suter, Thomas M.

    2009-01-01

    Inhibition of ErbB2 (HER2) with monoclonal antibodies, an effective therapy in some forms of breast cancer, is associated with cardiotoxicity, the pathophysiology of which is poorly understood. Recent data suggest, that dual inhibition of ErbB1 (EGFR) and ErbB2 signaling is more efficient in cancer therapy, however, cardiac safety of this therapeutic approach is unknown. We therefore tested an ErbB1-(CGP059326) and an ErbB1/ErbB2-(PKI166) tyrosine kinase inhibitor in an in-vitro system of adult rat ventricular cardiomyocytes and assessed their effects on 1. cell viability, 2. myofibrillar structure, 3. contractile function, and 4. MAPK- and Akt-signaling alone or in combination with Doxorubicin. Neither CGP nor PKI induced cardiomyocyte necrosis or apoptosis. PKI but not CGP caused myofibrillar structural damage that was additive to that induced by Doxorubicin at clinically relevant doses. These changes were associated with an inhibition of excitation-contraction coupling. PKI but not CGP decreased p-Erk1/2, suggesting a role for this MAP-kinase signaling pathway in the maintenance of myofibrils. These data indicate that the ErbB2 signaling pathway is critical for the maintenance of myofibrillar structure and function. Clinical studies using ErbB2-targeted inhibitors for the treatment of cancer should be designed to include careful monitoring for cardiac dysfunction.

  4. Didymin Alleviates Hepatic Fibrosis Through Inhibiting ERK and PI3K/Akt Pathways via Regulation of Raf Kinase Inhibitor Protein

    Directory of Open Access Journals (Sweden)

    Xing Lin

    2016-12-01

    Full Text Available Background: Didymin has been reported to have anti-cancer potential. However, the effect of didymin on liver fibrosis remains illdefined. Methods: Hepatic fibrosis was induced by CCl4 in rats. The effects of didymin on liver pathology and collagen accumulation were observed by hematoxylin-eosin and Masson's trichrome staining, respectively. Serum transaminases activities and collagen-related indicators levels were determined by commercially available kits. Moreover, the effects of didymin on hepatic stellate cell apoptosis and cell cycle were analyzed by flow cytometry. Mitochondrial membrane potential was detected by using rhodamine-123 dye. The expression of Raf kinase inhibitor protein (RKIP and the phosphorylation of the ERK/MAPK and PI3K/Akt pathways were assessed by Western blot. Results: Didymin significantly ameliorated chronic liver injury and collagen deposition. It strongly inhibited hepatic stellate cells proliferation, induced apoptosis and caused cell cycle arrest in G2/M phase. Moreover, didymin notably attenuated mitochondrial membrane potential, accompanied by release of cytochrome C. Didymin significantly inhibited the ERK/MAPK and PI3K/Akt pathways. The effects of didymin on the collagen accumulation in rats and on the biological behaviors of hepatic stellate cells were largely abolished by the specific RKIP inhibitor locostatin. Conclusion: Didymin alleviates hepatic fibrosis by inhibiting ERK/MAPK and PI3K/Akt pathways via regulation of RKIP expression.

  5. N-ω-chloroacetyl-l-ornithine, a new competitive inhibitor of ornithine decarboxylase, induces selective growth inhibition and cytotoxicity on human cancer cells versus normal cells.

    Science.gov (United States)

    Medina-Enríquez, Miriam Marlene; Alcántara-Farfán, Verónica; Aguilar-Faisal, Leopoldo; Trujillo-Ferrara, José Guadalupe; Rodríguez-Páez, Lorena; Vargas-Ramírez, Alba Laura

    2015-06-01

    Many cancer cells have high expression of ornithine decarboxylase (ODC) and there is a concerted effort to seek new inhibitors of this enzyme. The aim of the study was to initially characterize the inhibition properties, then to evaluate the cytotoxicity/antiproliferative cell based activity of N-ω-chloroacetyl-l-ornithine (NCAO) on three human cancer cell lines. Results showed NCAO to be a reversible competitive ODC inhibitor (Ki = 59 µM) with cytotoxic and antiproliferative effects, which were concentration- and time-dependent. The EC50,72h of NCAO was 15.8, 17.5 and 10.1 µM for HeLa, MCF-7 and HepG2 cells, respectively. NCAO at 500 µM completely inhibited growth of all cancer cells at 48 h treatment, with almost no effect on normal cells. Putrescine reversed NCAO effects on MCF-7 and HeLa cells, indicating that this antiproliferative activity is due to ODC inhibition.

  6. Combination Treatment with PPARγ Ligand and Its Specific Inhibitor GW9662 Downregulates BIS and 14-3-3 Gamma, Inhibiting Stem-Like Properties in Glioblastoma Cells.

    Science.gov (United States)

    Im, Chang-Nim

    2017-01-01

    PPAR γ is a nuclear receptor that regulates differentiation and proliferation and is highly expressed in many cancer cells. Its synthetic ligands, such as rosiglitazone and ciglitazone, and its inhibitor GW9662, were shown to induce cellular differentiation, inhibit proliferation, and lead to apoptosis. Glioblastoma is a common brain tumor with poor survival prospects. Recently, glioblastoma stem cells (GSCs) have been examined as a potential target for anticancer therapy; however, little is known about the combined effect of various agents on GSCs. In this study, we found that cotreatment with PPAR γ ligands and GW9662 inhibited stem-like properties in GSC-like spheres, which significantly express SOX2. In addition, this treatment decreased the activation of STAT3 and AKT and decreased the amounts of 14-3-3 gamma and BIS proteins. Moreover, combined administration of small-interfering RNA (siRNA) transfection with PPAR γ ligands induced downregulation of SOX2 and MMP2 activity together with inhibition of sphere-forming activity regardless of poly(ADP-ribose) polymerase (PARP) cleavage. Taken together, our findings suggest that a combination therapy using PPAR γ ligands and its inhibitor could be a potential therapeutic strategy targeting GSCs.

  7. Combination Treatment with PPARγ Ligand and Its Specific Inhibitor GW9662 Downregulates BIS and 14-3-3 Gamma, Inhibiting Stem-Like Properties in Glioblastoma Cells

    Directory of Open Access Journals (Sweden)

    Chang-Nim Im

    2017-01-01

    Full Text Available PPARγ is a nuclear receptor that regulates differentiation and proliferation and is highly expressed in many cancer cells. Its synthetic ligands, such as rosiglitazone and ciglitazone, and its inhibitor GW9662, were shown to induce cellular differentiation, inhibit proliferation, and lead to apoptosis. Glioblastoma is a common brain tumor with poor survival prospects. Recently, glioblastoma stem cells (GSCs have been examined as a potential target for anticancer therapy; however, little is known about the combined effect of various agents on GSCs. In this study, we found that cotreatment with PPARγ ligands and GW9662 inhibited stem-like properties in GSC-like spheres, which significantly express SOX2. In addition, this treatment decreased the activation of STAT3 and AKT and decreased the amounts of 14-3-3 gamma and BIS proteins. Moreover, combined administration of small-interfering RNA (siRNA transfection with PPARγ ligands induced downregulation of SOX2 and MMP2 activity together with inhibition of sphere-forming activity regardless of poly(ADP-ribose polymerase (PARP cleavage. Taken together, our findings suggest that a combination therapy using PPARγ ligands and its inhibitor could be a potential therapeutic strategy targeting GSCs.

  8. The kunitz protease inhibitor domain of protease nexin-2 inhibits factor XIa and murine carotid artery and middle cerebral artery thrombosis

    Science.gov (United States)

    Wu, Wenman; Li, Hongbo; Navaneetham, Duraiswamy; Reichenbach, Zachary W.; Tuma, Ronald F.

    2012-01-01

    Coagulation factor XI (FXI) plays an important part in both venous and arterial thrombosis, rendering FXIa a potential target for the development of antithrombotic therapy. The kunitz protease inhibitor (KPI) domain of protease nexin-2 (PN2) is a potent, highly specific inhibitor of FXIa, suggesting its possible role in the inhibition of FXI-dependent thrombosis in vivo. Therefore, we examined the effect of PN2KPI on thrombosis in the murine carotid artery and the middle cerebral artery. Intravenous administration of PN2KPI prolonged the clotting time of both human and murine plasma, and PN2KPI inhibited FXIa activity in both human and murine plasma in vitro. The intravenous administration of PN2KPI into WT mice dramatically decreased the progress of FeCl3-induced thrombus formation in the carotid artery. After a similar initial rate of thrombus formation with and without PN2KPI treatment, the propagation of thrombus formation after 10 minutes and the amount of thrombus formed were significantly decreased in mice treated with PN2KPI injection compared with untreated mice. In the middle cerebral artery occlusion model, the volume and fraction of ischemic brain tissue were significantly decreased in PN2KPI-treated compared with untreated mice. Thus, inhibition of FXIa by PN2KPI is a promising approach to antithrombotic therapy. PMID:22674803

  9. Inhibition of neurotensin-stimulated mast cell secretion and carboxypeptidase A activity by the peptide inhibitor of carboxypeptidase A and neurotensin-receptor antagonist SR 48692.

    Science.gov (United States)

    Miller, L A; Cochrane, D E; Feldberg, R S; Carraway, R E

    1998-06-01

    Neurotensin (NT), a peptide found in brain and several peripheral tissues, is a potent stimulus for mast cell secretion and its actions are blocked by the specific NT receptor antagonist, SR 48692. Subsequent to stimulation, NT is rapidly degraded by mast cell carboxypeptidase A (CPA). In the experiments described here, we tested for the involvement of CPA activity in the activation of mast cell secretion by the peptide, NT. Mast cells were isolated from the peritoneal and pleural cavities of rats, purified over metrizamide gradients and incubated at 37 degrees C in Locke solution or Locke containing the appropriate inhibitors. For some experiments, media derived from mast cells stimulated by compound 48/80 were used as a source of mast cell CPA activity. Treatment of mast cells with the highly specific peptide inhibitor of CPA derived from potato (PCI) inhibited histamine release in response to NT and NT8-13 (the biologically active region of NT). This inhibition required some 20 min to develop and was only partially reversed by a 20-min wash period. PCI (10 microM) did not inhibit histamine release in response to NT1-12, bradykinin, compound 48/80, the calcium ionophore, A23187, or anti-IgE serum. PCI also inhibited mast cell CPA activity. SR 48692, a highly selective antagonist of the brain NT receptor and of NT-stimulated mast cell secretion, also inhibited mast cell CPA activity as well as bovine pancreatic CPA activity in a concentration-dependent manner. It is suggested that the mast cell binding site for NT and the active site for CPA may share similar characteristics. The results are discussed in terms of NT mechanism of action on the mast cell.

  10. Higher insulin sensitivity in EDL muscle of rats fed a low-protein, high-carbohydrate diet inhibits the caspase-3 and ubiquitin-proteasome proteolytic systems but does not increase protein synthesis.

    Science.gov (United States)

    Dos Santos, Maísa Pavani; Batistela, Emanuele; Pereira, Mayara Peron; Paula-Gomes, Silvia; Zanon, Neusa Maria; Kettelhut, Isis do Carmo; Karatzaferi, Christina; Andrade, Claudia Marlise Balbinotti; de França, Suélem Aparecida; Baviera, Amanda Martins; Kawashita, Nair Honda

    2016-08-01

    Compared with the extensor digitorum longus (EDL) muscle of control rats (C), the EDL muscle of rats fed a low-protein, high-carbohydrate diet (LPHC) showed a 36% reduction in mass. Muscle mass is determined by the balance between protein synthesis and proteolysis; thus, the aim of this work was to evaluate the components involved in these processes. Compared with the muscle from C rats, the EDL muscle from LPHC diet-fed rats showed a reduction (34%) in the in vitro basal protein synthesis and a 22% reduction in the in vitro basal proteolysis suggesting that the reduction in the mass can be associated with a change in the rate of the two processes. Soon after euthanasia, in the EDL muscles of the rats fed the LPHC diet for 15days, the activity of caspase-3 and that of components of the ubiquitin-proteasome system (atrogin-1 content and chymotrypsin-like activity) were decreased. The phosphorylation of p70(S6K) and 4E-BP1, proteins involved in protein synthesis, was also decreased. We observed an increase in the insulin-stimulated protein content of p-Akt. Thus, the higher insulin sensitivity in the EDL muscle of LPHC rats seemed to contribute to the lower proteolysis in LPHC rats. However, even with the higher insulin sensitivity, the reduction in p-E4-BP1 and p70(S6K) indicates a reduction in protein synthesis, showing that factors other than insulin can have a greater effect on the control of protein synthesis. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Ubiquitin--conserved protein or selfish gene?

    Science.gov (United States)

    Catic, André; Ploegh, Hidde L

    2005-11-01

    The posttranslational modifier ubiquitin is encoded by a multigene family containing three primary members, which yield the precursor protein polyubiquitin and two ubiquitin moieties, Ub(L40) and Ub(S27), that are fused to the ribosomal proteins L40 and S27, respectively. The gene encoding polyubiquitin is highly conserved and, until now, those encoding Ub(L40) and Ub(S27) have been generally considered to be equally invariant. The evolution of the ribosomal ubiquitin moieties is, however, proving to be more dynamic. It seems that the genes encoding Ub(L40) and Ub(S27) are actively maintained by homologous recombination with the invariant polyubiquitin locus. Failure to recombine leads to deterioration of the sequence of the ribosomal ubiquitin moieties in several phyla, although this deterioration is evidently constrained by the structural requirements of the ubiquitin fold. Only a few amino acids in ubiquitin are vital for its function, and we propose that conservation of all three ubiquitin genes is driven not only by functional properties of the ubiquitin protein, but also by the propensity of the polyubiquitin locus to act as a 'selfish gene'.

  12. Inhibition properties of self-assembled corrosion inhibitor talloil diethylenetriamine imidazoline for mild steel corrosion in chloride solution saturated with carbon dioxide

    International Nuclear Information System (INIS)

    Jevremović, Ivana; Singer, Marc; Nešić, Srđan; Mišković-Stanković, Vesna

    2013-01-01

    Highlights: •Corrosion inhibitor talloil diethylenetriamine imidazoline effectively protects mild steel from CO 2 corrosion. •Quartz crystal microbalance measurements were used to the investigate kinetics of corrosion inhibitor adsorption. •Adsorption of talloil diethylenetriamine imidazoline can be described by Langmuir adsorption isotherm. -- Abstract: The inhibition effect of talloil diethylenetriamine imidazoline (TOFA/DETA imidazoline) on corrosion of mild steel in chloride solutions saturated with CO 2 was investigated by weight loss measurements (WL) and atomic force microscopy (AFM). Adsorption mechanism and kinetics of self-assembled (TOFA/DETA imidazoline) monolayers formation on gold were studied using the quartz crystal microbalance measurements (QCM). WL and AFM results demonstrated that TOFA/DETA imidazoline can effectively protect mild steel surface from corrosion. QCM measurements shown that the adsorption of TOFA/DETA imidazoline onto gold follows Langmuir adsorption isotherm and further investigation of the adsorption process will be carried out on a corroding metal surface

  13. The corrosion inhibition of aluminum and its copper alloys in 1.0 M H2SO4 solution using linear-sodium dodecyl benzene sulfonate as inhibitor

    International Nuclear Information System (INIS)

    Abd El Rehim, Sayed S.; Amin, Mohammed A.; Moussa, S.O.; Ellithy, Abdallah S.

    2008-01-01

    The corrosion inhibition of Al and its two copper alloys are the subject of tremendous technological importance due to the increased industrial applications of these materials. This paper reports the results of potentiodynamic polarization and electrochemical impedance spectroscopic (EIS) measurements on the corrosion inhibition of Al (Al-2.5% Cu and Al-7.0% Cu) alloys in 1.0 M H 2 SO 4 solution carried out in different concentrations of linear-sodium dodecyl benzene sulfonate as an anionic surfactant (LAS) and temperature range from 10 to 60 deg. C. The data revealed that the inhibition efficiency increases with increasing surfactant concentration and time of immersion, and decreases with solution temperature. Energy dispersion X-ray (EDX) observations of the electrode surface confirmed the existence of LAS adsorbed film on the electrode surface. The surfactant acted mainly as cathodic inhibitor. Maximum inhibition efficiency of the surfactant is observed at concentration around its critical micelle concentration (CMC). The inhibition occurs through adsorption of the surfactant on the metal surface without modifying the mechanism of the corrosion process, which tested by UV-spectroscopy. The potential of zero charge (PZC) of aluminum and Al-7.0% Cu was studied by ac-impedance, and the mechanism of adsorption is discussed. The adsorption isotherm is described by Temkin adsorption isotherm. Thermodynamic functions for activation and adsorption process were determined

  14. Ubiquitin regulates TORC1 in yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Hu, Kejin; Guo, Shuguang; Yan, Gonghong; Yuan, Wenjie; Zheng, Yin; Jiang, Yu

    2016-04-01

    In the yeast Saccharomyces cerevisiae the TOR complex 1 (TORC1) controls many growth-related cellular processes and is essential for cell growth and proliferation. Macrolide antibiotic rapamycin, in complex with a cytosol protein named FKBP12, specifically inhibits TORC1, causing growth arrest. The FKBP12-rapamycin complex interferes with TORC1 function by binding to the FRB domain of the TOR proteins. In an attempt to understand the role of the FRB domain in TOR function, we identified a single point mutation (Tor2(W2041R) ) in the FRB domain of Tor2 that renders yeast cells rapamycin resistant and temperature sensitive. At the permissive temperature, the Tor2 mutant protein is partially defective for binding with Kog1 and TORC1 is impaired for membrane association. At the restrictive temperature, Kog1 but not the Tor2 mutant protein, is rapidly degraded. Overexpression of ubiquitin stabilizes Kog1 and suppresses the growth defect associated with the tor2 mutant at the nonpremissive temperature. We find that ubiquitin binds non-covalently to Kog1, prevents Kog1 from degradation and stabilizes TORC1. Our data reveal a unique role for ubiquitin in regulation of TORC1 and suggest that Kog1 requires association with the Tor proteins for stabilization. © 2016 John Wiley & Sons Ltd.

  15. Regulation of nucleotide excision repair through ubiquitination

    Institute of Scientific and Technical Information of China (English)

    Jia Li; Audesh Bhat; Wei Xiao

    2011-01-01

    Nucleotide excision repair (NER) is the most versatile DNA-repair pathway in all organisms.While bacteria require only three proteins to complete the incision step of NER,eukaryotes employ about 30 proteins to complete the same step.Here we summarize recent studies demonstrating that ubiquitination,a post-translational modification,plays critical roles in regulating the NER activity either dependent on or independent of ubiquitin-proteolysis.Several NER components have been shown as targets of ubiquitination while others are actively involved in the ubiquitination process.We argue through this analysis that ubiquitination serves to coordinate various steps of NER and meanwhile connect NER with other related pathways to achieve the efficient global DNA-damage response.

  16. Discovery of Highly Selective and Nanomolar Carbamate-Based Butyrylcholinesterase Inhibitors by Rational Investigation into Their Inhibition Mode.

    Science.gov (United States)

    Sawatzky, Edgar; Wehle, Sarah; Kling, Beata; Wendrich, Jan; Bringmann, Gerhard; Sotriffer, Christoph A; Heilmann, Jörg; Decker, Michael

    2016-03-10

    Butyrylcholinesterase (BChE) is a promising target for the treatment of later stage cognitive decline in Alzheimer's disease. A set of pseudo-irreversible BChE inhibitors with high selectivity over hAChE was synthesized based on carbamates attached to tetrahydroquinazoline scaffolds with the 2-thiophenyl compound 2p as the most potent inhibitor of eqBChE (KC = 14.3 nM) and also of hBChE (KC = 19.7 nM). The inhibitors transfer the carbamate moiety onto the active site under release of the phenolic tetrahydroquinazoline scaffolds that themselves act as neuroprotectants. By combination of kinetic data with molecular docking studies, a plausible binding model was probed describing how the tetrahydroquinazoline scaffold guides the carbamate into a close position to the active site. The model explains the influence of the carrier scaffold onto the affinity of an inhibitor just before carbamate transfer. This strategy can be used to utilize the binding mode of other carbamate-based inhibitors.

  17. A group-specific inhibitor of lysosomal cysteine proteinases selectively inhibits both proteolytic degradation and presentation of the antigen dinitrophenyl-poly-L-lysine by guinea pig accessory cells to T cells

    DEFF Research Database (Denmark)

    Buus, S; Werdelin, O

    1986-01-01

    of antigens by guinea pig accessory cells. The proteinase inhibitor benzyloxycarbonyl-phenylalanylalanine-diazomethyl-ketone, which selectively inhibits cysteine proteinases, was used to block this set of enzymes in cultured cells. We demonstrate that the selective inhibition of the cysteine proteinases...

  18. Structures of a bi-functional Kunitz-type STI family inhibitor of serine and aspartic proteases: Could the aspartic protease inhibition have evolved from a canonical serine protease-binding loop?

    Science.gov (United States)

    Guerra, Yasel; Valiente, Pedro A; Pons, Tirso; Berry, Colin; Rudiño-Piñera, Enrique

    2016-08-01

    Bi-functional inhibitors from the Kunitz-type soybean trypsin inhibitor (STI) family are glycosylated proteins able to inhibit serine and aspartic proteases. Here we report six crystal structures of the wild-type and a non-glycosylated mutant of the bifunctional inhibitor E3Ad obtained at different pH values and space groups. The crystal structures show that E3Ad adopts the typical β-trefoil fold of the STI family exhibiting some conformational changes due to pH variations and crystal packing. Despite the high sequence identity with a recently reported potato cathepsin D inhibitor (PDI), three-dimensional structures obtained in this work show a significant conformational change in the protease-binding loop proposed for aspartic protease inhibition. The E3Ad binding loop for serine protease inhibition is also proposed, based on structural similarity with a novel non-canonical conformation described for the double-headed inhibitor API-A from the Kunitz-type STI family. In addition, structural and sequence analyses suggest that bifunctional inhibitors of serine and aspartic proteases from the Kunitz-type STI family are more similar to double-headed inhibitor API-A than other inhibitors with a canonical protease-binding loop. Copyright © 2016. Published by Elsevier Inc.

  19. The Role of Factor XIa (FXIa) Catalytic Domain Exosite Residues in Substrate Catalysis and Inhibition by the Kunitz Protease Inhibitor Domain of Protease Nexin 2*

    Science.gov (United States)

    Su, Ya-Chi; Miller, Tara N.; Navaneetham, Duraiswamy; Schoonmaker, Robert T.; Sinha, Dipali; Walsh, Peter N.

    2011-01-01

    To select residues in coagulation factor XIa (FXIa) potentially important for substrate and inhibitor interactions, we examined the crystal structure of the complex between the catalytic domain of FXIa and the Kunitz protease inhibitor (KPI) domain of a physiologically relevant FXIa inhibitor, protease nexin 2 (PN2). Six FXIa catalytic domain residues (Glu98, Tyr143, Ile151, Arg3704, Lys192, and Tyr5901) were subjected to mutational analysis to investigate the molecular interactions between FXIa and the small synthetic substrate (S-2366), the macromolecular substrate (factor IX (FIX)) and inhibitor PN2KPI. Analysis of all six Ala mutants demonstrated normal Km values for S-2366 hydrolysis, indicating normal substrate binding compared with plasma FXIa; however, all except E98A and K192A had impaired values of kcat for S-2366 hydrolysis. All six Ala mutants displayed deficient kcat values for FIX hydrolysis, and all were inhibited by PN2KPI with normal values of Ki except for K192A, and Y5901A, which displayed increased values of Ki. The integrity of the S1 binding site residue, Asp189, utilizing p-aminobenzamidine, was intact for all FXIa mutants. Thus, whereas all six residues are essential for catalysis of the macromolecular substrate (FIX), only four (Tyr143, Ile151, Arg3704, and Tyr5901) are important for S-2366 hydrolysis; Glu98 and Lys192 are essential for FIX but not S-2366 hydrolysis; and Lys192 and Tyr5901 are required for both inhibitor and macromolecular substrate interactions. PMID:21778227

  20. Identification of a small-molecule inhibitor of the PICK1 PDZ domain that inhibits hippocampal LTP and LTD

    DEFF Research Database (Denmark)

    Thorsen, Thor S; Madsen, Kenneth L; Rebola, Nelson

    2010-01-01

    interacting protein 1 (GRIP1). Pretreatment of cultured hippocampal neurons with FSC231 inhibited coimmunopreciptation of the AMPA receptor GluR2 subunit with PICK1. In agreement with inhibiting the role of PICK1 in GluR2 trafficking, FSC231 accelerated recycling of pHluorin-tagged GluR2 in hippocampal...

  1. INHIBITION OF THE GROWTH OF TOLERANT YEAST Saccharomyces cerevisiae STRAIN I136 BY A MIXTURE OF SYNTHETIC INHIBITORS

    Directory of Open Access Journals (Sweden)

    Eny Ida Riyanti

    2017-09-01

    Full Text Available Biomass from lignocellulosic wastes is a potential source for biobased products.  However, one of the constraints in utilization of biomass hydrolysate is the presence of inhibitors. Therefore, the use of inhibitor-tolerant microorganisms in the fermentation is required. The study aimed to investigate the effect of a mixture of inhibitors on the growth of Saccharomyces cerevisiae strain I136 grown in medium containing synthetic inhibitors (acetic acid, formic acid, furfural, 5-hydroxymethyl furfural/5-HMF, and levulinic acid in four different concentrations with a mixture of carbon sources, glucose  (50 g.l-1 and xylose (50 g.l-1 at 30oC. The parameters related to growth and fermentation products were observed. Results showed that the strain was able to grow in media containing natural inhibitors (BSL medium with µmax of 0.020/h. Higher level of synthetic inhibitors prolonged the lag phase, decreased the cell biomass and ethanol production, and specific growth rate. The strain could detoxify furfural and 5-HMF and produced the highest ethanol (Y(p/s of 0.32 g.g-1 when grown in BSL. Glucose was utilized as its level decreased in a result of increase in cell biomass, in contrast to xylose which was not consumed. The highest cell biomass was produced in YNB with Y (x/s value of 0.25 g.g-1. The strain produced acetic acid as a dominant side product and could convert furfural into a less toxic compound, hydroxyl furfural. This robust tolerant strain provides basic information on resistance mechanism and would be useful for bio-based cell factory using lignocellulosic materials. 

  2. Selective inhibition of ADAM12 catalytic activity through engineering of tissue inhibitor of metalloproteinase 2 (TIMP-2)

    DEFF Research Database (Denmark)

    Kveiborg, Marie; Jacobsen, Jonas; Lee, Meng-Huee

    2010-01-01

    activity may be of great value therapeutically and as an investigative tool to elucidate its mechanisms of action. We have previously reported the inhibitory profile of TIMPs (tissue inhibitor of metalloproteinases) against ADAM12, demonstrating in addition to TIMP-3, a unique ADAM-inhibitory activity...... activity of TIMPs against the transmembrane ADAM12-L (full-length ADAM12), verifying the distinctive inhibitory abilities of N-TIMP-2 and engineered N-TIMP-2 mutants in a cellular environment. Taken together, our findings support the idea that a distinctive ADAM12 inhibitor with future therapeutic...

  3. A PKA survival pathway inhibited by DPT-PKI, a new specific cell permeable PKA inhibitor, is induced by T. annulata in parasitized B-lymphocytes.

    Science.gov (United States)

    Guergnon, Julien; Dessauge, Frederic; Traincard, François; Cayla, Xavier; Rebollo, Angelita; Bost, Pierre Etienne; Langsley, Gordon; Garcia, Alphonse

    2006-08-01

    T. annulata, an intracellular pathogenic parasite of the Aplicomplexa protozoan family infects bovine B-lymphocytes and macrophages. Parasitized cells that become transformed survive and proliferate independently of exogenous growth factors. In the present study, we used the isogenic non parasitized BL3 and parasitized TBL3 B cell lines, as a model to evaluate the contribution of two-major PI3-K- and PKA-dependent anti-apoptotic pathways in the survival of T. annulata parasitized B lymphocytes. We found that T. annulata increases PKA activity, induces over-expression of the catalytic subunit and down-regulates the pro-survival phosphorylation state of Akt/PKB. Consistent with a role of PKA activation in survival, two pharmacological inhibitors H89 and KT5720 ablate PKA-dependent survival of parasitized cells. To specifically inhibit PKA pro-survival pathways we linked the DPTsh1 peptide shuttle sequence to PKI(5-24) and we generated DPT-PKI, a cell permeable PKI. DPT-PKI specifically inhibited PKA activity in bovine cell extracts and, as expected, also inhibited the PKA-dependent survival of T. annulata parasitized TBL3 cells. Thus, parasite-dependent constitutive activation of PKA in TBL3 cells generates an anti-apoptotic pathway that can protect T. annulata-infected B cells from apoptosis. These results also indicate that DPT-PKI could be a powerful tool to inhibit PKA pathways in other cell types.

  4. Studies on the mechanism of fibrate-inhibited expression of plasminogen activator inhibitor-1 in cultured hepatocytes from cynomolgus monkey

    NARCIS (Netherlands)

    Arts, J.; Kooistra, T.

    1997-01-01

    Fibrates are widely used drugs in hyperlipidemic disorders. In addition to lowering serum triglyceride levels, fibrates have also been shown to reduce elevated plasma plasminogen activator inhibitor-1 (PAI-1) levels in vivo. We demonstrate that fibrates suppress PAI-1 synthesis in cultured

  5. Inhibition of Post-Transcriptional RNA Processing by CDK Inhibitors and Its Implication in Anti-Viral Therapy

    Czech Academy of Sciences Publication Activity Database

    Holčáková, J.; Müller, P.; Tomasec, P.; Hrstka, R.; Nekulová, M.; Kryštof, Vladimír; Strnad, Miroslav; Wilkinson, G. W. G.; Vojtěšek, B.

    2014-01-01

    Roč. 9, č. 2 (2014) E-ISSN 1932-6203 R&D Projects: GA ČR GBP206/12/G151 Institutional support: RVO:61389030 Keywords : IMMUNODEFICIENCY-VIRUS TYPE-1 * DEPENDENT KINASE INHIBITORS * LARGE T-ANTIGEN Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.234, year: 2014

  6. Inhibition of canonical WNT signaling pathway by β-catenin/CBP inhibitor ICG-001 ameliorates liver fibrosis in vivo through suppression of stromal CXCL12.

    Science.gov (United States)

    Akcora, Büsra Öztürk; Storm, Gert; Bansal, Ruchi

    2018-03-01

    Quiescent hepatic stellate cells (HSCs), in response to liver injury, undergo characteristic morphological transformation into proliferative, contractile and ECM-producing myofibroblasts. In this study, we investigated the implication of canonical Wnt signaling pathway in HSCs and liver fibrogenesis. Canonical Wnt signaling pathway activation and inhibition using β-catenin/CBP inhibitor ICG001 was examined in-vitro in TGFβ-activated 3T3, LX2, primary human HSCs, and in-vivo in CCl 4 -induced acute liver injury mouse model. Fibroblasts-conditioned medium studies were performed to assess the Wnt-regulated paracrine factors involved in crosstalk between HSCs-macrophages and HSCs-endothelial cells. Canonical Wnt signaling pathway components were significantly up-regulated in-vitro and in-vivo. In-vitro, ICG-001 significantly inhibited fibrotic parameters, 3D-collagen contractility and wound healing. Conditioned medium induced fibroblasts-mediated macrophage and endothelial cells activation was significantly inhibited by ICG-001. In-vivo, ICG-001 significantly attenuated collagen accumulation and HSC activation. Interestingly, ICG-001 drastically inhibited macrophage infiltration, intrahepatic inflammation and angiogenesis. We further analyzed the paracrine factors involved in Wnt-mediated effects and found CXCL12 was significantly suppressed both in-vitro and in-vivo following Wnt inhibition. Wnt-regulated CXCL12 secretion from activated HSCs potentiated macrophage infiltration and activation, and angiogenesis. Pharmacological inhibition of canonical Wnt signaling pathway via suppression of stromal CXCL12 suggests a potential therapeutic approach targeting activated HSCs in liver fibrosis. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  7. Calcineurin inhibitor-induced complement system activation via ERK1/2 signalling is inhibited by SOCS-3 in human renal tubule cells.

    Science.gov (United States)

    Loeschenberger, Beatrix; Niess, Lea; Würzner, Reinhard; Schwelberger, Hubert; Eder, Iris E; Puhr, Martin; Guenther, Julia; Troppmair, Jakob; Rudnicki, Michael; Neuwirt, Hannes

    2018-02-01

    One factor that significantly contributes to renal allograft loss is chronic calcineurin inhibitor (CNI) nephrotoxicity (CIN). Among other factors, the complement (C-) system has been proposed to be involved CIN development. Hence, we investigated the impact of CNIs on intracellular signalling and the effects on the C-system in human renal tubule cells. In a qPCR array, CNI treatment upregulated C-factors and downregulated SOCS-3 and the complement inhibitors CD46 and CD55. Additionally, ERK1/-2 was required for these regulations. Following knock-down and overexpression of SOCS-3, we found that SOCS-3 inhibits ERK1/-2 signalling. Finally, we assessed terminal complement complex formation, cell viability and apoptosis. Terminal complement complex formation was induced by CNIs. Cell viability was significantly decreased, whereas apoptosis was increased. Both effects were reversed under complement component-depleted conditions. In vivo, increased ERK1/-2 phosphorylation and SOCS-3 downregulation were observed at the time of transplantation in renal allograft patients who developed a progressive decline of renal function in the follow-up compared to stable patients. The progressive cohort also had lower total C3 levels, suggesting higher complement activity at baseline. In conclusion, our data suggest that SOCS-3 inhibits CNI-induced ERK1/-2 signalling, thereby blunting the negative control of C-system activation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Discovery of novel PDE9 inhibitors capable of inhibiting Aβ aggregation as potential candidates for the treatment of Alzheimer’s disease

    Science.gov (United States)

    Su, Tao; Zhang, Tianhua; Xie, Shishun; Yan, Jun; Wu, Yinuo; Li, Xingshu; Huang, Ling; Luo, Hai-Bin

    2016-02-01

    Recently, phosphodiesterase-9 (PDE9) inhibitors and biometal-chelators have received much attention as potential therapeutics for the treatment of Alzheimer’s disease (AD). Here, we designed, synthesized, and evaluated a novel series of PDE9 inhibitors with the ability to chelate metal ions. The bioassay results showed that most of these molecules strongly inhibited PDE9 activity. Compound 16 showed an IC50 of 34 nM against PDE9 and more than 55-fold selectivity against other PDEs. In addition, this compound displayed remarkable metal-chelating capacity and a considerable ability to halt copper redox cycling. Notably, in comparison to the reference compound clioquinol, it inhibited metal-induced Aβ1-42 aggregation more effectively and promoted greater disassembly of the highly structured Aβ fibrils generated through Cu2+-induced Aβ aggregation. These activities of 16, together with its favorable blood-brain barrier permeability, suggest that 16 may be a promising compound for treatment of AD.

  9. Structural basis for the inhibition of poly(ADP-ribose) polymerases 1 and 2 by BMN 673, a potent inhibitor derived from dihydropyridophthalazinone

    Energy Technology Data Exchange (ETDEWEB)

    Aoyagi-Scharber, Mika, E-mail: maoyagi@bmrn.com [BioMarin Pharmaceutical Inc., 105 Digital Drive, Novato, CA 94949 (United States); Gardberg, Anna S. [Emerald BioStructures, 7869 NE Day Road West, Bainbridge Island, WA 98110 (United States); Yip, Bryan K.; Wang, Bing; Shen, Yuqiao; Fitzpatrick, Paul A. [BioMarin Pharmaceutical Inc., 105 Digital Drive, Novato, CA 94949 (United States)

    2014-08-29

    BMN 673, a novel PARP1/2 inhibitor in clinical development with substantial tumor cytotoxicity, forms extensive hydrogen-bonding and π-stacking in the nicotinamide pocket, with its unique disubstituted scaffold extending towards the less conserved edges of the pocket. These interactions might provide structural insight into the ability of BMN 673 to both inhibit catalysis and affect DNA-binding activity. Poly(ADP-ribose) polymerases 1 and 2 (PARP1 and PARP2), which are involved in DNA damage response, are targets of anticancer therapeutics. BMN 673 is a novel PARP1/2 inhibitor with substantially increased PARP-mediated tumor cytotoxicity and is now in later-stage clinical development for BRCA-deficient breast cancers. In co-crystal structures, BMN 673 is anchored to the nicotinamide-binding pocket via an extensive network of hydrogen-bonding and π-stacking interactions, including those mediated by active-site water molecules. The novel di-branched scaffold of BMN 673 extends the binding interactions towards the outer edges of the pocket, which exhibit the least sequence homology among PARP enzymes. The crystallographic structural analyses reported here therefore not only provide critical insights into the molecular basis for the exceptionally high potency of the clinical development candidate BMN 673, but also new opportunities for increasing inhibitor selectivity.

  10. Structural basis for the inhibition of poly(ADP-ribose) polymerases 1 and 2 by BMN 673, a potent inhibitor derived from dihydropyridophthalazinone

    International Nuclear Information System (INIS)

    Aoyagi-Scharber, Mika; Gardberg, Anna S.; Yip, Bryan K.; Wang, Bing; Shen, Yuqiao; Fitzpatrick, Paul A.

    2014-01-01

    BMN 673, a novel PARP1/2 inhibitor in clinical development with substantial tumor cytotoxicity, forms extensive hydrogen-bonding and π-stacking in the nicotinamide pocket, with its unique disubstituted scaffold extending towards the less conserved edges of the pocket. These interactions might provide structural insight into the ability of BMN 673 to both inhibit catalysis and affect DNA-binding activity. Poly(ADP-ribose) polymerases 1 and 2 (PARP1 and PARP2), which are involved in DNA damage response, are targets of anticancer therapeutics. BMN 673 is a novel PARP1/2 inhibitor with substantially increased PARP-mediated tumor cytotoxicity and is now in later-stage clinical development for BRCA-deficient breast cancers. In co-crystal structures, BMN 673 is anchored to the nicotinamide-binding pocket via an extensive network of hydrogen-bonding and π-stacking interactions, including those mediated by active-site water molecules. The novel di-branched scaffold of BMN 673 extends the binding interactions towards the outer edges of the pocket, which exhibit the least sequence homology among PARP enzymes. The crystallographic structural analyses reported here therefore not only provide critical insights into the molecular basis for the exceptionally high potency of the clinical development candidate BMN 673, but also new opportunities for increasing inhibitor selectivity

  11. Partial contribution of Rho-kinase inhibition to the bioactivity of Ganoderma lingzhi and its isolated compounds: insights on discovery of natural Rho-kinase inhibitors.

    Science.gov (United States)

    Amen, Yhiya; Zhu, Qinchang; Tran, Hai-Bang; Afifi, Mohamed S; Halim, Ahmed F; Ashour, Ahmed; Shimizu, Kuniyoshi

    2017-04-01

    Recent studies identified Rho-kinase enzymes (ROCK-I and ROCK-II) as important targets that are involved in a variety of diseases. Synthetic Rho-kinase inhibitors have emerged as potential therapeutic agents to treat disorders such as hypertension, stroke, cancer, diabetes, glaucoma, etc. Our study is the first to screen the total ethanol extract of the medicinal mushroom Ganoderma lingzhi with thirty-five compounds for Rho-kinase inhibitory activity. Moreover, a molecular binding experiment was designed to investigate the binding affinity of the compounds at the active sites of Rho-kinase enzymes. The structure-activity relationship analysis was investigated. Our results suggest that the traditional uses of G. lingzhi might be in part due to the ROCK-I and ROCK-II inhibitory potential of this mushroom. Structure-activity relationship studies revealed some interesting features of the lanostane triterpenes that potentiate their Rho-kinase inhibition. These findings would be helpful for further studies on the design of Rho-kinase inhibitors from natural sources and open the door for contributions from other researchers for optimizing the development of natural Rho-kinase inhibitors.

  12. Glycogen synthase kinase-3 inhibitors suppress the AR-V7-mediated transcription and selectively inhibit cell growth in AR-V7-positive prostate cancer cells.

    Science.gov (United States)

    Nakata, Daisuke; Koyama, Ryokichi; Nakayama, Kazuhide; Kitazawa, Satoshi; Watanabe, Tatsuya; Hara, Takahito

    2017-06-01

    Recent evidence suggests that androgen receptor (AR) splice variants, including AR-V7, play a pivotal role in resistance to androgen blockade in prostate cancer treatment. The development of new therapeutic agents that can suppress the transcriptional activities of AR splice variants has been anticipated as the next generation treatment of castration-resistant prostate cancer. High-throughput screening of AR-V7 signaling inhibitors was performed using an AR-V7 reporter system. The effects of a glycogen synthase kinase-3 (GSK3) inhibitor, LY-2090314, on endogenous AR-V7 signaling were evaluated in an AR-V7-positive cell line, JDCaP-hr, by quantitative reverse transcription polymerase chain reaction. The relationship between AR-V7 signaling and β-catenin signaling was assessed using RNA interference. The effect of LY-2090314 on cell growth in various prostate cancer cell lines was also evaluated. We identified GSK3 inhibitors as transcriptional suppressors of AR-V7 using a high-throughput screen with an AR-V7 reporter system. LY-2090314 suppressed the reporter activity and endogenous AR-V7 activity in JDCaP-hr cells. Because silencing of β-catenin partly rescued the suppression, it was evident that the suppression was mediated, at least partially, via the activation of β-catenin signaling. AR-V7 signaling and β-catenin signaling reciprocally regulate each other in JDCaP-hr cells, and therefore, GSK3 inhibition can repress AR-V7 transcriptional activity by accumulating intracellular β-catenin. Notably, LY-2090314 selectively inhibited the growth of AR-V7-positive prostate cancer cells in vitro. Our findings demonstrate the potential of GSK3 inhibitors in treating advanced prostate cancer driven by AR splice variants. In vivo evaluation of AR splice variant-positive prostate cancer models will help illustrate the overall significance of GSK3 inhibitors in treating prostate cancer. © 2017 Wiley Periodicals, Inc.

  13. SYVN1, an ERAD E3 Ubiquitin Ligase, Is Involved in GABAAα1 Degradation Associated with Methamphetamine-Induced Conditioned Place Preference

    Directory of Open Access Journals (Sweden)

    Dong-Liang Jiao

    2017-10-01

    Full Text Available Abuse of methamphetamine (METH, a powerful addictive amphetamine-type stimulants (ATS, is becoming a global public health problem. The gamma-aminobutyric acid (GABAergic system plays a critical role in METH use disorders. By using rat METH conditioned place preference (CPP model, we previously demonstrated that METH-associated rewarding memory formation was associated with the reduction of GABAAα1 expression in the dorsal straitum (Dstr, however, the underlying mechanism was unclear. In the present study, we found that METH-induced CPP formation was accompanied by a significant increase in the expression of Synovial apoptosis inhibitor 1 (SYVN1, an endoplasmic reticulum (ER-associated degradation (ERAD E3 ubiquitin ligase, in the Dstr. The siRNA knockdown of SYVN1 significantly increased GABAAα1 protein levels in both primary cultured neurons and rodent Dstr. Inhibition of proteasomal activity by MG132 and Lactacystin significantly increased GABAAα1 protein levels. We further found that SYVN1 knockdown increased GABAAα1 in the intra-ER, but not in the extra-ER. Accordingly, endoplasmic reticulum stress (ERS-associated Glucose-regulated protein 78 (GRP78 and C/EBP homologous protein (CHOP increased. Thus, this study revealed that SYVN1, as the ERAD E3 ubiquitin ligase, was associated with Dstr GABAAα1 degradation induced by METH conditioned pairing.

  14. A novel small molecular STAT3 inhibitor, LY5, inhibits cell viability, cell migration, and angiogenesis in medulloblastoma cells.

    Science.gov (United States)

    Xiao, Hui; Bid, Hemant Kumar; Jou, David; Wu, Xiaojuan; Yu, Wenying; Li, Chenglong; Houghton, Peter J; Lin, Jiayuh

    2015-02-06

    Signal transducers and activators of transcription 3 (STAT3) signaling is persistently activated and could contribute to tumorigenesis of medulloblastoma. Numerous studies have demonstrated that inhibition of the persistent STAT3 signaling pathway results in decreased proliferation and increased apoptosis in human cancer cells, indicating that STAT3 is a viable molecular target for cancer therapy. In this study, we investigated a novel non-peptide, cell-permeable small molecule, named LY5, to target STAT3 in medulloblastoma cells. LY5 inhibited persistent STAT3 phosphorylation and induced apoptosis in human medulloblastoma cell lines expressing constitutive STAT3 phosphorylation. The inhibition of STAT3 signaling by LY5 was confirmed by down-regulating the expression of the downstream targets of STAT3, including cyclin D1, bcl-XL, survivin, and micro-RNA-21. LY5 also inhibited the induction of STAT3 phosphorylation by interleukin-6 (IL-6), insulin-like growth factor (IGF)-1, IGF-2, and leukemia inhibitory factor in medulloblastoma cells, but did not inhibit STAT1 and STAT5 phosphorylation stimulated by interferon-γ (IFN-γ) and EGF, respectively. In addition, LY5 blocked the STAT3 nuclear localization induced by IL-6, but did not block STAT1 and STAT5 nuclear translocation mediated by IFN-γ and EGF, respectively. A combination of LY5 with cisplatin or x-ray radiation also showed more potent effects than single treatment alone in the inhibition of cell viability in human medulloblastoma cells. Furthermore, LY5 demonstrated a potent inhibitory activity on cell migration and angiogenesis. Taken together, these findings indicate LY5 inhibits persistent and inducible STAT3 phosphorylation and suggest that LY5 is a promising therapeutic drug candidate for medulloblastoma by inhibiting persistent STAT3 signaling. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Met1-linked Ubiquitination in Immune Signalling

    DEFF Research Database (Denmark)

    Fiil, Berthe Katrine; Gyrd-Hansen, Mads

    2014-01-01

    Methionine 1-linked ubiquitin chains (Met1-Ub), or linear ubiquitin, has emerged as a central post-translational modification in innate immune signalling. Molecular machinery that assembles, senses and, more recently, disassembles Met1-Ub has been identified, and technical advances have enabled...... identification of physiological substrates for Met1-Ub in response to activation of innate immune receptors. These discoveries have significantly advanced our understanding of how non-degradative ubiquitin modifications control pro-inflammatory responses mediated by nuclear factor κB and mitogen...

  16. The canonical wnt signal restricts the glycogen synthase kinase 3/fbw7-dependent ubiquitination and degradation of eya1 phosphatase.

    Science.gov (United States)

    Sun, Ye; Li, Xue

    2014-07-01

    Haploinsufficiency of Eya1 causes the branchio-oto-renal (BOR) syndrome, and abnormally high levels of Eya1 are linked to breast cancer progression and poor prognosis. Therefore, regulation of Eya1 activity is key to its tissue-specific functions and oncogenic activities. Here, we show that Eya1 is posttranslationally modified by ubiquitin and that its ubiquitination level is self-limited to prevent premature degradation. Eya1 has an evolutionarily conserved CDC4 phosphodegron (CPD) signal, a target site of glycogen synthase kinase 3 (GSK3) kinase and Fbw7 ubiquitin ligase, which is required for Eya1 ubiquitination. Genetic deletion of Fbw7 and pharmacological inhibition of GSK3 significantly decrease Eya1 ubiquitination. Conversely, activation of the phosphatidylinositol 3-kinase (PI3K)/Akt and the canonical Wnt signal suppresses Eya1 ubiquitination. Compound Eya1(+/-); Wnt9b(+/-) mutants exhibit an increased penetrance of renal defect, indicating that they function in the same genetic pathway in vivo. Together, these findings reveal that the canonical Wnt and PI3K/Akt signal pathways restrain the GSK3/Fbw7-dependent Eya1 ubiquitination, and they further suggest that dysregulation of this novel axis contributes to tumorigenesis. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  17. Plasminogen-induced aggregation of PANC-1 cells requires conversion to plasmin and is inhibited by endogenous plasminogen activator inhibitor-1.

    Science.gov (United States)

    Deshet, Naamit; Lupu-Meiri, Monica; Espinoza, Ingrid; Fili, Oded; Shapira, Yuval; Lupu, Ruth; Gershengorn, Marvin C; Oron, Yoram

    2008-09-01

    PANC-1 cells express proteinase-activated receptors (PARs)-1, -2, and respond to their activation by transient elevation of cytosolic [Ca(2+)] and accelerated aggregation (Wei et al., 2006, J Cell Physiol 206:322-328). We studied the effect of plasminogen (PGN), an inactive precursor of the PAR-1-activating protease, plasmin (PN) on aggregation of pancreatic adenocarcinoma (PDAC) cells. A single dose of PGN time- and dose-dependently promoted PANC-1 cells aggregation in serum-free medium, while PN did not. PANC-1 cells express urokinase plasminogen activator (uPA), which continuously converted PGN to PN. This activity and PGN-induced aggregation were inhibited by the uPA inhibitor amiloride. PGN-induced aggregation was also inhibited by alpha-antiplasmin and by the PN inhibitor epsilon-aminocaproic acid (EACA). Direct assay of uPA activity revealed very low rate, markedly enhanced in the presence of PGN. Moreover, in PGN activator inhibitor 1-deficient PANC-1 cells, uPA activity and PGN-induced aggregation were markedly potentiated. Two additional human PDAC cell lines, MiaPaCa and Colo347, were assayed for PGN-induced aggregation. Both cell lines responded by aggregation and exhibited PGN-enhanced uPA activity. We hypothesized that the continuous conversion of PGN to PN by endogenous uPA is limited by PN's degradation and negatively controlled by endogenously produced PAI-1. Indeed, we found that PANC-1 cells inactivate PN with t1/2 of approximately 7 h, while the continuous addition of PN promoted aggregation. Our data suggest that PANC-1 cells possess intrinsic, PAI-1-sensitive mechanism for promotion of aggregation and differentiation by prolonged exposure to PGN and, possibly, additional precursors of PARs agonists.

  18. Novel multifunctional neuroprotective iron chelator-monoamine oxidase inhibitor drugs for neurodegenerative diseases: in vitro studies on antioxidant activity, prevention of lipid peroxide formation and monoamine oxidase inhibition.

    Science.gov (United States)

    Zheng, Hailin; Gal, Shunit; Weiner, Lev M; Bar-Am, Orit; Warshawsky, Abraham; Fridkin, Mati; Youdim, Moussa B H

    2005-10-01

    Iron-dependent oxidative stress, elevated levels of iron and of monoamine oxidase (MAO)-B activity, and depletion of antioxidants in the brain may be major pathogenic factors in Parkinson's disease, Alzheimer's disease and related neurodegenerative diseases. Accordingly, iron chelators, antioxidants and MAO-B inhibitors have shown efficacy in a variety of cellular and animal models of CNS injury. In searching for novel antioxidant iron chelators with potential MAO-B inhibitory activity, a series of new iron chelators has been designed, synthesized and investigated. In this study, the novel chelators were further examined for their activity as antioxidants, MAO-B inhibitors and neuroprotective agents in vitro. Three of the selected chelators (M30, HLA20 and M32) were the most effective in inhibiting iron-dependent lipid peroxidation in rat brain homogenates with IC50 values (12-16 microM), which is comparable with that of desferal, a prototype iron chelator that is not has orally active. Their antioxidant activities were further confirmed using electron paramagnetic resonance spectroscopy. In PC12 cell culture, the three novel chelators at 0.1 microM were able to attenuate cell death induced by serum deprivation and by 6-hydroxydopamine. M30 possessing propargyl, the MAO inhibitory moiety of the anti-Parkinson drug rasagiline, displayed greater neuroprotective potency than that of rasagiline. In addition, in vitro, M30 was a highly potent non-selective MAO-A and MAO-B inhibitor (IC50 < 0.1 microM). However, HLA20 was more selective for MAO-B but had poor MAO inhibition, with an IC50 value of 64.2 microM. The data suggest that M30 and HLA20 might serve as leads in developing drugs with multifunctional activities for the treatment of various neurodegenerative disorders.

  19. Activated thrombin-activatable fibrinolysis inhibitor (TAFIa) attenuates breast cancer cell metastatic behaviors through inhibition of plasminogen activation and extracellular proteolysis

    International Nuclear Information System (INIS)

    Bazzi, Zainab A.; Lanoue, Danielle; El-Youssef, Mouhanned; Romagnuolo, Rocco; Tubman, Janice; Cavallo-Medved, Dora; Porter, Lisa A.; Boffa, Michael B.

    2016-01-01

    Thrombin activatable fibrinolysis inhibitor (TAFI) is a plasma zymogen, which can be converted to activated TAFI (TAFIa) through proteolytic cleavage by thrombin, plasmin, and most effectively thrombin in complex with the endothelial cofactor thrombomodulin (TM). TAFIa is a carboxypeptidase that cleaves carboxyl terminal lysine and arginine residues from protein and peptide substrates, including plasminogen-binding sites on cell surface receptors. Carboxyl terminal lysine residues play a pivotal role in enhancing cell surface plasminogen activation to plasmin. Plasmin has many critical functions including cleaving components of the extracellular matrix (ECM), which enhances invasion and migration of cancer cells. We therefore hypothesized that TAFIa could act to attenuate metastasis. To assess the role of TAFIa in breast cancer metastasis, in vitro migration and invasion assays, live cell proteolysis and cell proliferation using MDA-MB-231 and SUM149 cells were carried out in the presence of a TAFIa inhibitor, recombinant TAFI variants, or soluble TM. Inhibition of TAFIa with potato tuber carboxypeptidase inhibitor increased cell invasion, migration and proteolysis of both cell lines, whereas addition of TM resulted in a decrease in all these parameters. A stable variant of TAFIa, TAFIa-CIIYQ, showed enhanced inhibitory effects on cell invasion, migration and proteolysis. Furthermore, pericellular plasminogen activation was significantly decreased on the surface of MDA-MB-231 and SUM149 cells following treatment with various concentrations of TAFIa. Taken together, these results indicate a vital role for TAFIa in regulating pericellular plasminogen activation and ultimately ECM proteolysis in the breast cancer microenvironment. Enhancement of TAFI activation in this microenvironment may be a therapeutic strategy to inhibit invasion and prevent metastasis of breast cancer cells

  20. Stereoselective Inhibition of CYP2C19 and CYP3A4 by Fluoxetine and Its Metabolite: Implications for Risk Assessment of Multiple Time-Dependent Inhibitor Systems

    Science.gov (United States)

    Lutz, Justin D.; VandenBrink, Brooke M.; Babu, Katipudi N.; Nelson, Wendel L.; Kunze, Kent L.

    2013-01-01

    Recent guidance on drug-drug interaction (DDI) testing recommends evaluation of circulating metabolites. However, there is little consensus on how to quantitatively predict and/or assess the risk of in vivo DDIs by multiple time-dependent inhibitors (TDIs) including metabolites from in vitro data. Fluoxetine was chosen as the model drug to evaluate the role of TDI metabolites in DDI prediction because it is a TDI of both CYP3A4 and CYP2C19 with a circulating N-dealkylated inhibitory metabolite, norfluoxetine. In pooled human liver microsomes, both enantiomers of fluoxetine and norfluoxetine were TDIs of CYP2C19, (S)-norfluoxetine was the most potent inhibitor with time-dependent inhibition affinity constant (KI) of 7 μM, and apparent maximum time-dependent inhibition rate (kinact,app) of 0.059 min−1. Only (S)-fluoxetine and (R)-norfluoxetine were TDIs of CYP3A4, with (R)-norfluoxetine being the most potent (KI = 8 μM, and kinact,app = 0.011 min−1). Based on in-vitro-to-in-vivo predictions, (S)-norfluoxetine plays the most important role in in vivo CYP2C19 DDIs, whereas (R)-norfluoxetine is most important in CYP3A4 DDIs. Comparison of two multiple TDI prediction models demonstrated significant differences between them in in-vitro-to-in-vitro predictions but not in in-vitro-to-in-vivo predictions. Inclusion of all four inhibitors predicted an in vivo decrease in CYP2C19 (95%) and CYP3A4 (60–62%) activity. The results of this study suggest that adequate worst-case risk assessment for in vivo DDIs by multiple TDI systems can be achieved by incorporating time-dependent inhibition by both parent and metabolite via simple addition of the in vivo time-dependent inhibition rate/cytochrome P450 degradation rate constant (λ/kdeg) values, but quantitative DDI predictions will require a more thorough understanding of TDI mechanisms. PMID:23785064

  1. Structural basis for ubiquitin recognition by ubiquitin-binding zinc finger of FAAP20.

    Directory of Open Access Journals (Sweden)

    Aya Toma

    Full Text Available Several ubiquitin-binding zinc fingers (UBZs have been reported to preferentially bind K63-linked ubiquitin chains. In particular, the UBZ domain of FAAP20 (FAAP20-UBZ, a member of the Fanconi anemia core complex, seems to recognize K63-linked ubiquitin chains, in order to recruit the complex to DNA interstrand crosslinks and mediate DNA repair. By contrast, it is reported that the attachment of a single ubiquitin to Rev1, a translesion DNA polymerase, increases binding of Rev1 to FAAP20. To clarify the specificity of FAAP20-UBZ, we determined the crystal structure of FAAP20-UBZ in complex with K63-linked diubiquitin at 1.9 Å resolution. In this structure, FAAP20-UBZ interacts only with one of the two ubiquitin moieties. Consistently, binding assays using surface plasmon resonance spectrometry showed that FAAP20-UBZ binds ubiquitin and M1-, K48- and K63-linked diubiquitin chains with similar affinities. Residues in the vicinity of Ala168 within the α-helix and the C-terminal Trp180 interact with the canonical Ile44-centered hydrophobic patch of ubiquitin. Asp164 within the α-helix and the C-terminal loop mediate a hydrogen bond network, which reinforces ubiquitin-binding of FAAP20-UBZ. Mutations of the ubiquitin-interacting residues disrupted binding to ubiquitin in vitro and abolished the accumulation of FAAP20 to DNA damage sites in vivo. Finally, structural comparison among FAAP20-UBZ, WRNIP1-UBZ and RAD18-UBZ revealed distinct modes of ubiquitin binding. UBZ family proteins could be divided into at least three classes, according to their ubiquitin-binding modes.

  2. Inhibition of p70S6K1 Activation by Pdcd4 Overcomes the Resistance to an IGF-1R/IR Inhibitor in Colon Carcinoma Cells.

    Science.gov (United States)

    Zhang, Yan; Wang, Qing; Chen, Li; Yang, Hsin-Sheng

    2015-03-01

    Agents targeting insulin-like growth factor 1 receptor (IGF-1R) are being actively examined in clinical trials. Although there has been some initial success of single-agent targeting IGF-1R, attempts in later studies failed because of resistance. This study aimed to understand the effects of programmed cell death 4 (Pdcd4) on the chemosensitivity of the IGF-1R inhibitor OSI-906 in colorectal cancer cells and the mechanism underlying this impact. Using OSI-906-resistant and -sensitive colorectal cancer cells, we found that the Pdcd4 level directly correlates with cell chemosensitivity to OSI-906. In addition, tumors derived from Pdcd4 knockdown cells resist the growth inhibitory effect of OSI-906 in a colorectal cancer xenograft mouse model. Moreover, Pdcd4 enhances the antiproliferative effect of OSI-906 in resistant cells through suppression of p70S6K1 activation. Knockdown of p70S6K1, but not p70S6K2, significantly increases the chemosensitivity of OSI-906 in cultured colorectal cancer cells. Furthermore, the combination of OSI-906 and PF-4708671, a p70S6K1 inhibitor, efficiently suppresses the growth of OSI-906-resistant colon tumor cells in vitro and in vivo. Taken together, activation of p70S6K1 that is inhibited by Pdcd4 is essential for resistance to the IGF-1R inhibitor in colon tumor cells, and the combinational treatment of OSI-906 and PF-4708671 results in enhanced antiproliferation effects in colorectal cancer cells in vitro and in vivo, providing a novel venue to overcome the resistance to the IGF-1R inhibitor in treating colorectal cancer. ©2015 American Association for Cancer Research.

  3. Structural Basis for the Inhibition of RNase H Activity of HIV-1 Reverse Transcriptase by RNase H Active Site-Directed Inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Su, Hua-Poo; Yan, Youwei; Prasad, G. Sridhar; Smith, Robert F.; Daniels, Christopher L.; Abeywickrema, Pravien D.; Reid, John C.; Loughran, H. Marie; Kornienko, Maria; Sharma, Sujata; Grobler, Jay A.; Xu, Bei; Sardana, Vinod; Allison, Timothy J.; Williams, Peter D.; Darke, Paul L.; Hazuda, Daria J.; Munshi, Sanjeev (Merck)

    2010-09-02

    HIV/AIDS continues to be a menace to public health. Several drugs currently on the market have successfully improved the ability to manage the viral burden in infected patients. However, new drugs are needed to combat the rapid emergence of mutated forms of the virus that are resistant to existing therapies. Currently, approved drugs target three of the four major enzyme activities encoded by the virus that are critical to the HIV life cycle. Although a number of inhibitors of HIV RNase H activity have been reported, few inhibit by directly engaging the RNase H active site. Here, we describe structures of naphthyridinone-containing inhibitors bound to the RNase H active site. This class of compounds binds to the active site via two metal ions that are coordinated by catalytic site residues, D443, E478, D498, and D549. The directionality of the naphthyridinone pharmacophore is restricted by the ordering of D549 and H539 in the RNase H domain. In addition, one of the naphthyridinone-based compounds was found to bind at a second site close to the polymerase active site and non-nucleoside/nucleotide inhibitor sites in a metal-independent manner. Further characterization, using fluorescence-based thermal denaturation and a crystal structure of the isolated RNase H domain reveals that this compound can also bind the RNase H site and retains the metal-dependent binding mode of this class of molecules. These structures provide a means for structurally guided design of novel RNase H inhibitors.

  4. Inhibition of iron uptake is responsible for differential sensitivity to V-ATPase inhibitors in several cancer cell lines.

    Directory of Open Access Journals (Sweden)

    Sarah Straud

    2010-07-01

    Full Text Available Many cell lines derived from tumors as well as transformed cell lines are far more sensitive to V-ATPase inhibitors than normal counterparts. The molecular mechanisms underlying these differences in sensitivity are not known. Using global gene expression data, we show that the most sensitive responses to HeLa cells to low doses of V-ATPase inhibitors involve genes responsive to decreasing intracellular iron or decreasing cholesterol and that sensitivity to iron uptake is an important determinant of V-ATPase sensitivity in several cancer cell lines. One of the most sensitive cell lines, melanoma derived SK-Mel-5, over-expresses the iron efflux transporter ferroportin and has decreased expression of proteins involved in iron uptake, suggesting that it actively suppresses cytoplasmic iron. SK-Mel-5 cells have increased production of reactive oxygen species and may be seeking to limit additional production of ROS by iron.

  5. Inhibition of cornifins and up-regulation of protease inhibitors in cervicovaginal lavage imparts resistance to heterosexual HIV transmission

    Directory of Open Access Journals (Sweden)

    Sushama Rokade

    2017-12-01

    Full Text Available HIV-exposed seronegative individuals (HESNs are persons who remain seronegative despite repeated exposure to HIV, suggesting an in vivo resistance mechanism to HIV. Elucidation of endogenous factors responsible for this phenomenon may aid in the development of new classes of microbicides and therapeutics. The genital mucosal secretions of both men and women are known to contain a spectrum of antimicrobials and immune mediators that may contribute to resistance against HIV-1. Existence of HIV serodiscordant couples is a testimony to mucosal factors in the genital tract that prevent sexual transmission of the virus. We attempted to map such mucosal factors in female genital secretions of the serodiscordant couples in comparison with HIV infected and healthy participants using quantitative proteomics. The cervico vaginal lavage (CVL samples were collected from three groups of study participants (HIV infected, n=30; Un-infected Controls, n=10; Serodiscordant, n=24. Abundant proteins, albumin and globulins were removed from the pooled samples using multiple affinity removal spin cartridge (Agilent to enhance the sensitivity of iTRAQ proteomics analysis. Initial analysis identified a total of 135 proteins and associated 497 peptide matches. Serodiscordant females showed significantly down regulated levels of Cornifin A, B and C, Neutrophil gelatinase, myeloperoxidase and eosinophil peroxidase. Cornifins are cross-linked envelope protein of keratinocytes and are upregulated during inflammation. Downregulation of oxidative stress inducing enzymes and cornifins suggests immune-quiescence in serodiscordant females. CVL of these women showed significantly upregulated levels of Mucin 5B, S100A7, Alpha-2-macroglobulin, Cystatin A (protease inhibitor, Lacto-transferrin, SLPI (anti-leukoproteinase inhibitor and SERPIN G1 (protease inhibitor.  Significantly elevated levels of Cystatin B and Elafin in the CVL of serodiscordant females were confirmed by ELISA

  6. A novel PKB/Akt inhibitor, MK-2206, effectively inhibits insulin-stimulated glucose metabolism and protein synthesis in isolated rat skeletal muscle.

    Science.gov (United States)

    Lai, Yu-Chiang; Liu, Yang; Jacobs, Roxane; Rider, Mark H

    2012-10-01

    PKB (protein kinase B), also known as Akt, is a key component of insulin signalling. Defects in PKB activation lead to insulin resistance and metabolic disorders, whereas PKB overactivation has been linked to tumour growth. Small-molecule PKB inhibitors have thus been developed for cancer treatment, but also represent useful tools to probe the roles of PKB in insulin action. In the present study, we examined the acute effects of two allosteric PKB inhibitors, MK-2206 and Akti 1/2 (Akti) on PKB signalling in incubated rat soleus muscles. We also assessed the effects of the compounds on insulin-stimulated glucose uptake, glycogen and protein synthesis. MK-2206 dose-dependently inhibited insulin-stimulated PKB phosphorylation, PKBβ activity and phosphorylation of PKB downstream targets (including glycogen synthase kinase-3α/β, proline-rich Akt substrate of 40 kDa and Akt substrate of 160 kDa). Insulin-stimulated glucose uptake, glycogen synthesis and glycogen synthase activity were also decreased by MK-2206 in a dose-dependent manner. Incubation with high doses of MK-2206 (10 μM) inhibited insulin-induced p70 ribosomal protein S6 kinase and 4E-BP1 (eukaryotic initiation factor 4E-binding protein-1) phosphorylation associated with increased eEF2 (eukaryotic elongation factor 2) phosphorylation. In contrast, Akti only modestly inhibited insulin-induced PKB and mTOR (mammalian target of rapamycin) signalling, with little or no effect on glucose uptake and protein synthesis. MK-2206, rather than Akti, would thus be the tool of choice for studying the role of PKB in insulin action in skeletal muscle. The results point to a key role for PKB in mediating insulin-stimulated glucose uptake, glycogen synthesis and protein synthesis in skeletal muscle.

  7. Assessment of vandetanib as an inhibitor of various human renal transporters: inhibition of multidrug and toxin extrusion as a possible mechanism leading to decreased cisplatin and creatinine clearance.

    Science.gov (United States)

    Shen, Hong; Yang, Zheng; Zhao, Weiping; Zhang, Yueping; Rodrigues, A David

    2013-12-01

    Vandetanib was evaluated as an inhibitor of human organic anion transporter 1 (OAT1), OAT3, organic cation transporter 2 (OCT2), and multidrug and toxin extrusion (MATE1 and MATE2K) transfected (individually) into human embryonic kidney 293 cells (HEK293). Although no inhibition of OAT1 and OAT3 was observed, inhibition of OCT2-mediated uptake of 1-methyl-4-phenylpyridinium (MPP(+)) and metformin was evident (IC(50) of 73.4 ± 14.8 and 8.8 ± 1.9 µM, respectively). However, vandetanib was an even more potent inhibitor of MATE1- and MATE2K-mediated uptake of MPP(+) (IC(50) of 1.23 ± 0.05 and 1.26 ± 0.06 µM, respectively) and metformin (IC(50) of 0.16 ± 0.05 and 0.30 ± 0.09 µM, respectively). Subsequent cytotoxicity studies demonstrated that transport inhibition by vandetanib (2.5 µM) significantly decreased the sensitivity [right shift in concentration of cisplatin giving rise to 50% cell death; IC(50(CN))] of MATE1-HEK and MATE2K-HEK cells to cisplatin [IC(50(CN)) of 1.12 ± 0.13 versus 2.39 ± 0.44 µM; 0.85 ± 0.09 versus 1.99 ± 0.16 µM; P cisplatin nephrotoxicity (reduced cisplatin clearance), in some subjects receiving vandetanib therapy.

  8. MCPIP1 contributes to the toxicity of proteasome inhibitor MG-132 in HeLa cells by the inhibition of NF-κB.

    Science.gov (United States)

    Skalniak, Lukasz; Dziendziel, Monika; Jura, Jolanta

    2014-10-01

    Recently, we have shown that the treatment of cells with proteasome inhibitor MG-132 results in the induction of expression of monocyte chemotactic protein-1 induced protein 1 (MCPIP1). MCPIP1 is a ribonuclease, responsible for the degradation of transcripts encoding certain pro-inflammatory cytokines. The protein is also known as an inhibitor of NF-κB transcription factor. Thanks to its molecular properties, MCPIP1 is considered as a regulator of inflammation, differentiation, and survival. Using siRNA technology, we show here that MCPIP1 expression contributes to the toxic properties of MG-132 in HeLa cells. The inhibition of proteasome by MG-132 and epoxomicin markedly increased MCPIP1 expression. While MG-132 induces HeLa cell death, down-regulation of MCPIP1 expression by siRNA partially protects HeLa cells from MG-132 toxicity and restores Nuclear factor-κB (NF-κB) activity, inhibited by MG-132 treatment. Inversely, overexpression of MCPIP1 decreased constitutive activity of NF-κB and limited the survival of HeLa cells, as we have shown in the previous study. Interestingly, although MG-132 decreased the expression of IκBα and increased p65 phosphorylation, the inhibition of constitutive NF-κB activity was observed in MG-132-treated cells. Since the elevated constitutive activity of NF-κB is one of the mechanisms providing increased survival of cancer cells, including HeLa cells, we propose that death-promoting properties of MCPIP1 in MG-132-treated HeLa cells may, at least partially, derive from the negative effect on the constitutive NF-κB activity.

  9. The phosphodiesterase 3 inhibitor ORG 9935 inhibits oocyte maturation in the naturally selected dominant follicle in rhesus macaques.

    Science.gov (United States)

    Jensen, Jeffrey T; Zelinski, Mary B; Stanley, Jessica E; Fanton, John W; Stouffer, Richard L

    2008-04-01

    The study was conducted to determine whether the phosphodiesterase (PDE) 3 inhibitor ORG 9935 prevents the resumption of meiosis in primate oocytes during natural menstrual cycles. Regularly cycling adult female macaques (n=8) were followed during the follicular phase and then started on a 2-day treatment regimen of human recombinant gonadotropins to control the timing of ovulation. Monkeys received no further treatment (controls) or ORG 9935. Oocytes were recovered by laparoscopic follicle aspiration 27 h after an ovulatory stimulus, cultured in vitro in the absence of inhibitor and inseminated. The primary outcome was the meiotic stage of the oocyte. In six ORG 9935 cycles, five of the recovered oocytes were germinal vesicle (GV)-intact, and one exhibited GV breakdown (GVBD). In contrast, all three oocytes that recovered during control cycles were GVBD (pORG 9935-treated oocytes underwent fertilization compared with 2/3 (67%) from controls. These results demonstrate that ORG 9935 blocks resumption of meiosis in the naturally selected dominant follicle in primates and suggest that PDE3 inhibitors have potential clinical use as contraceptives in women.

  10. Ergopeptines bromocriptine and ergovaline and the dopamine type-2 receptor inhibitor domperidone inhibit bovine equilibrative nucleoside transporter 1-like activity.

    Science.gov (United States)

    Miles, Edwena D; Xue, Yan; Strickland, James R; Boling, James A; Matthews, James C

    2011-09-14

    Neotyphodium coenophialum-infected tall fescue contains ergopeptines. Except for interactions with biogenic amine receptors (e.g., dopamine type-2 receptor, D2R), little is known about how ergopeptines affect animal metabolism. The effect of ergopeptines on bovine nucleoside transporters (NT) was evaluated using Madin-Darby bovine kidney (MDBK) cells. Equilibrative NT1 (ENT1)-like activity accounted for 94% of total NT activity. Inhibitory competition (IC(50)) experiments found that this activity was inhibited by both bromocriptine (a synthetic model ergopeptine and D2R agonist) and ergovaline (a predominant ergopeptine of tall fescue). Kinetic inhibition analysis indicated that bromocriptine inhibited ENT1-like activity through a competitive and noncompetitive mechanism. Domperidone (a D2R antagonist) inhibited ENT1 activity more in the presence than in the absence of bromocriptine and displayed an IC(50) value lower than that of bromocriptine or ergovaline, suggesting that inhibition was not through D2R-mediated events. These novel mechanistic findings imply that cattle consuming endophyte-infected tall fescue have reduced ENT1 activity and, thus, impaired nucleoside metabolism.

  11. Transport inhibition of digoxin using several common P-gp expressing cell lines is not necessarily reporting only on inhibitor binding to P-gp.

    Directory of Open Access Journals (Sweden)

    Annie Albin Lumen

    Full Text Available We have reported that the P-gp substrate digoxin required basolateral and apical uptake transport in excess of that allowed by digoxin passive permeability (as measured in the presence of GF120918 to achieve the observed efflux kinetics across MDCK-MDR1-NKI (The Netherlands Cancer Institute confluent cell monolayers. That is, GF120918 inhibitable uptake transport was kinetically required. Therefore, IC50 measurements using digoxin as a probe substrate in this cell line could be due to inhibition of P-gp, of digoxin uptake transport, or both. This kinetic analysis is now extended to include three additional cell lines: MDCK-MDR1-NIH (National Institute of Health, Caco-2 and CPT-B2 (Caco-2 cells with BCRP knockdown. These cells similarly exhibit GF120918 inhibitable uptake transport of digoxin. We demonstrate that inhibition of digoxin transport across these cell lines by GF120918, cyclosporine, ketoconazole and verapamil is greater than can be explained by inhibition of P-gp alone. We examined three hypotheses for this non-P-gp inhibition. The inhibitors can: (1 bind to a basolateral digoxin uptake transporter, thereby inhibiting digoxin's cellular uptake; (2 partition into the basolateral membrane and directly reduce membrane permeability; (3 aggregate with digoxin in the donor chamber, thereby reducing the free concentration of digoxin, with concomitant reduction in digoxin uptake. Data and simulations show that hypothesis 1 was found to be uniformly acceptable. Hypothesis 2 was found to be uniformly unlikely. Hypothesis 3 was unlikely for GF120918 and cyclosporine, but further studies are needed to completely adjudicate whether hetero-dimerization contributes to the non-P-gp inhibition for ketoconazole and verapamil. We also find that P-gp substrates with relatively low passive permeability such as digoxin, loperamide and vinblastine kinetically require basolateral uptake transport over that allowed by +GF120918 passive permeability, while

  12. Btk Inhibitor RN983 Delivered by Dry Powder Nose-only Aerosol Inhalation Inhibits Bronchoconstriction and Pulmonary Inflammation in the Ovalbumin Allergic Mouse Model of Asthma.

    Science.gov (United States)

    Phillips, Jonathan E; Renteria, Lorena; Burns, Lisa; Harris, Paul; Peng, Ruoqi; Bauer, Carla M T; Laine, Dramane; Stevenson, Christopher S

    2016-06-01

    In allergen-induced asthma, activated mast cells start the lung inflammatory process with degranulation, cytokine synthesis, and mediator release. Bruton's tyrosine kinase (Btk) activity is required for the mast cell activation during IgE-mediated secretion. This study characterized a novel inhaled Btk inhibitor RN983 in vitro and in ovalbumin allergic mouse models of the early (EAR) and late (LAR) asthmatic response. RN983 potently, selectively, and reversibly inhibited the Btk enzyme. RN983 displayed functional activities in human cell-based assays in multiple cell types, inhibiting IgG production in B-cells with an IC50 of 2.5 ± 0.7 nM and PGD2 production from mast cells with an IC50 of 8.3 ± 1.1 nM. RN983 displayed similar functional activities in the allergic mouse model of asthma when delivered as a dry powder aerosol by nose-only inhalation. RN983 was less potent at inhibiting bronchoconstriction (IC50(RN983) = 59 μg/kg) than the β-agonist salbutamol (IC50(salbutamol) = 15 μg/kg) in the mouse model of the EAR. RN983 was more potent at inhibiting the antigen induced increase in pulmonary inflammation (IC50(RN983) = <3 μg/kg) than the inhaled corticosteroid budesonide (IC50(budesonide) = 27 μg/kg) in the mouse model of the LAR. Inhalation of aerosolized RN983 may be effective as a stand-alone asthma therapy or used in combination with inhaled steroids and β-agonists in severe asthmatics due to its potent inhibition of mast cell activation.

  13. JAK-inhibitor tofacitinib suppresses interferon alfa production by plasmacytoid dendritic cells and inhibits arthrogenic and antiviral effects of interferon alfa.

    Science.gov (United States)

    Boor, Patrick P C; de Ruiter, Petra E; Asmawidjaja, Patrick S; Lubberts, Erik; van der Laan, Luc J W; Kwekkeboom, Jaap

    2017-10-01

    Tofacitinib is an oral Janus kinase inhibitor that is effective for the treatment of rheumatoid arthritis and shows encouraging therapeutic effects in several other autoimmune diseases. A prominent adverse effect of tofacitinib therapy is the increased risk of viral infections. Despite its advanced stage of clinical development, the modes of action that mediate the beneficial and adverse effects of tofacitinib in autoimmune diseases remain unclear. Interferon alfa (IFNα) produced by plasmacytoid dendritic cells (PDCs) is critically involved in the pathogenesis of many systemic autoimmune diseases and in immunity to viral infections. Using in vitro culture models with human cells, we studied the effects of tofacitinib on PDC survival and IFNα production, and on arthrogenic and antiviral effects of IFNα. Tofacitinib inhibited the expression of antiapoptotic BCL-A1 and BCL-XL in human PDC and induced PDC apoptosis. TLR7 stimulation upregulated the levels of antiapoptotic Bcl-2 family members and prevented the induction of PDC apoptosis by tofacitinib. However, tofacitinib robustly inhibited the production of IFNα by toll like receptor-stimulated PDC. In addition, tofacitinib profoundly suppressed IFNα-induced upregulation of TLR3 on synovial fibroblasts, thereby inhibiting their cytokine and protease production in response to TLR3 ligation. Finally, tofacitinib counteracted the suppressive effects of IFNα on viral replication. Tofacitinib inhibits PDC survival and IFNα production and suppresses arthrogenic and antiviral effects of IFNα signaling. Inhibition of the IFNα pathway at 2 levels may contribute to the beneficial effects of tofacitinib in autoimmune diseases and explain the increased viral infection rates observed during tofacitinib treatment. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. The novel orally bioavailable inhibitor of phosphoinositol-3-kinase and mammalian target of rapamycin, NVP-BEZ235, inhibits growth and proliferation in multiple myeloma

    International Nuclear Information System (INIS)

    Baumann, Philipp; Mandl-Weber, Sonja; Oduncu, Fuat; Schmidmaier, Ralf

    2009-01-01

    NVP-BEZ235 is a new inhibitor of phosphoinositol-3-kinase (PI3 kinase) and mammalian target of rapamycin (mTOR) whose efficacy in advanced solid tumours is currently being evaluated in a phase I/II clinical trial. Here we show that NVP-BEZ235 inhibits growth in common myeloma cell lines as well as primary myeloma cells at nanomolar concentrations in a time and dose dependent fashion. Further experiments revealed induction of apoptosis in three of four cell lines. Inhibition of cell growth was mainly due to inhibition of myeloma cell proliferation, as shown by the BrdU assay. Cell cycle analysis revealed induction of cell cycle arrest in the G1 phase, which was due to downregulation of cyclin D1, pRb and cdc25a. NVP-BEZ235 inhibited phosphorylation of protein kinase B (Akt), P70S6k and 4E-BP-1. Furthermore we show that the stimulatory effect of CD40-ligand (CD40L), insulin-like growth factor 1 (IGF-1), interleukin-6 (IL-6) and conditioned medium of HS-5 stromal cells on myeloma cell growth is completely abrogated by NVP-BEZ235. In addition, synergism studies revealed synergistic and additive activity of NVP-BEZ235 together with melphalan, doxorubicin and bortezomib. Taken together, inhibition of PI3 kinase/mTOR by NVP-BEZ235 is highly effective and NVP-BEZ235 represents a potential new candidate for targeted therapy in multiple myeloma

  15. Ubiquitination of specific mitochondrial matrix proteins

    International Nuclear Information System (INIS)

    Lehmann, Gilad; Ziv, Tamar; Braten, Ori; Admon, Arie; Udasin, Ronald G.; Ciechanover, Aaron

    2016-01-01

    Several protein quality control systems in bacteria and/or mitochondrial matrix from lower eukaryotes are absent in higher eukaryotes. These are transfer-messenger RNA (tmRNA), The N-end rule ATP-dependent protease ClpAP, and two more ATP-dependent proteases, HslUV and ClpXP (in yeast). The lost proteases resemble the 26S proteasome and the role of tmRNA and the N-end rule in eukaryotic cytosol is performed by the ubiquitin proteasome system (UPS). Therefore, we hypothesized that the UPS might have substituted these systems – at least partially – in the mitochondrial matrix of higher eukaryotes. Using three independent experimental approaches, we demonstrated the presence of ubiquitinated proteins in the matrix of isolated yeast mitochondria. First, we show that isolated mitochondria contain ubiquitin (Ub) conjugates, which remained intact after trypsin digestion. Second, we demonstrate that the mitochondrial soluble fraction contains Ub-conjugates, several of which were identified by mass spectrometry and are localized to the matrix. Third, using immunoaffinity enrichment by specific antibodies recognizing digested ubiquitinated peptides, we identified a group of Ub-modified matrix proteins. The modification was further substantiated by separation on SDS-PAGE and immunoblots. Last, we attempted to identify the ubiquitin ligase(s) involved, and identified Dma1p as a trypsin-resistant protein in our mitochondrial preparations. Taken together, these data suggest a yet undefined role for the UPS in regulation of the mitochondrial matrix proteins. -- Highlights: •Mitochondrial matrix contains ubiquitinated proteins. •Ubiquitination occurs most probably in the matrix. •Dma1p is a ubiquitin ligase present in mitochondrial preparations.

  16. Ubiquitination of specific mitochondrial matrix proteins

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, Gilad [The Janet and David Polak Tumor and Vascular Biology Research Center and the Technion Integrated Cancer Center (TICC), The Rappaport Faculty of Medicine and Research Institute, Haifa, 31096 (Israel); Ziv, Tamar [The Smoler Proteomics Center, Faculty of Biology – Technion-Israel Institute of Technology, Haifa, 32000 (Israel); Braten, Ori [The Janet and David Polak Tumor and Vascular Biology Research Center and the Technion Integrated Cancer Center (TICC), The Rappaport Faculty of Medicine and Research Institute, Haifa, 31096 (Israel); Admon, Arie [The Smoler Proteomics Center, Faculty of Biology – Technion-Israel Institute of Technology, Haifa, 32000 (Israel); Udasin, Ronald G. [The Janet and David Polak Tumor and Vascular Biology Research Center and the Technion Integrated Cancer Center (TICC), The Rappaport Faculty of Medicine and Research Institute, Haifa, 31096 (Israel); Ciechanover, Aaron, E-mail: aaroncie@tx.technion.ac.il [The Janet and David Polak Tumor and Vascular Biology Research Center and the Technion Integrated Cancer Center (TICC), The Rappaport Faculty of Medicine and Research Institute, Haifa, 31096 (Israel)

    2016-06-17

    Several protein quality control systems in bacteria and/or mitochondrial matrix from lower eukaryotes are absent in higher eukaryotes. These are transfer-messenger RNA (tmRNA), The N-end rule ATP-dependent protease ClpAP, and two more ATP-dependent proteases, HslUV and ClpXP (in yeast). The lost proteases resemble the 26S proteasome and the role of tmRNA and the N-end rule in eukaryotic cytosol is performed by the ubiquitin proteasome system (UPS). Therefore, we hypothesized that the UPS might have substituted these systems – at least partially – in the mitochondrial matrix of higher eukaryotes. Using three independent experimental approaches, we demonstrated the presence of ubiquitinated proteins in the matrix of isolated yeast mitochondria. First, we show that isolated mitochondria contain ubiquitin (Ub) conjugates, which remained intact after trypsin digestion. Second, we demonstrate that the mitochondrial soluble fraction contains Ub-conjugates, several of which were identified by mass spectrometry and are localized to the matrix. Third, using immunoaffinity enrichment by specific antibodies recognizing digested ubiquitinated peptides, we identified a group of Ub-modified matrix proteins. The modification was further substantiated by separation on SDS-PAGE and immunoblots. Last, we attempted to identify the ubiquitin ligase(s) involved, and identified Dma1p as a trypsin-resistant protein in our mitochondrial preparations. Taken together, these data suggest a yet undefined role for the UPS in regulation of the mitochondrial matrix proteins. -- Highlights: •Mitochondrial matrix contains ubiquitinated proteins. •Ubiquitination occurs most probably in the matrix. •Dma1p is a ubiquitin ligase present in mitochondrial preparations.

  17. High-Resolution Inhibition Profiling Combined with HPLC-HRMS-SPE-NMR for Identification of PTP1B Inhibitors from Vietnamese Plants.

    Science.gov (United States)

    Trinh, Binh Thi Dieu; Jäger, Anna K; Staerk, Dan

    2017-07-20

    Protein tyrosine phosphatase 1B (PTP1B) plays a key role as a negative regulator in insulin signal transduction by deactivating the insulin receptor. Thus, PTP1B inhibition has emerged as a potential therapeutic strategy for curing insulin resistance. In this study, 40 extracts from 18 different plant species were investigated for PTP1B inhibitory activity in vitro. The most promising one, the EtOAc extract of Ficus racemosa , was investigated by high-resolution PTP1B inhibition profiling combined with HPLC-HRMS-SPE-NMR analysis. This led to the identification of isoderrone ( 1 ), derrone ( 2 ), alpinumisoflavone ( 3 ) and mucusisoflavone B ( 4 ) as PTP1B inhibitors. IC 50 of these compounds were 22.7 ± 1.7, 12.6 ± 1.6, 21.2 ± 3.8 and 2.5 ± 0.2 µM, respectively. Kinetics analysis revealed that these compounds inhibited PTP1B non-competitively with K i values of 21.3 ± 2.8, 7.9 ± 1.9, 14.3 ± 2.0, and 3.0 ± 0.5 µM, respectively. These findings support the important role of F. racemosa as a novel source of new drugs and/or as a herbal remedy for treatment of type 2 diabetes.

  18. High-Resolution Inhibition Profiling Combined with HPLC-HRMS-SPE-NMR for Identification of PTP1B Inhibitors from Vietnamese Plants

    Directory of Open Access Journals (Sweden)

    Binh Thi Dieu Trinh

    2017-07-01

    Full Text Available Protein tyrosine phosphatase 1B (PTP1B plays a key role as a negative regulator in insulin signal transduction by deactivating the insulin receptor. Thus, PTP1B inhibition has emerged as a potential therapeutic strategy for curing insulin resistance. In this study, 40 extracts from 18 different plant species were investigated for PTP1B inhibitory activity in vitro. The most promising one, the EtOAc extract of Ficus racemosa, was investigated by high-resolution PTP1B inhibition profiling combined with HPLC-HRMS-SPE-NMR analysis. This led to the identification of isoderrone (1, derrone (2, alpinumisoflavone (3 and mucusisoflavone B (4 as PTP1B inhibitors. IC50 of these compounds were 22.7 ± 1.7, 12.6 ± 1.6, 21.2 ± 3.8 and 2.5 ± 0.2 µM, respectively. Kinetics analysis revealed that these compounds inhibited PTP1B non-competitively with Ki values of 21.3 ± 2.8, 7.9 ± 1.9, 14.3 ± 2.0, and 3.0 ± 0.5 µM, respectively. These findings support the important role of F. racemosa as a novel source of new drugs and/or as a herbal remedy for treatment of type 2 diabetes.

  19. Flurbiprofen, a Cyclooxygenase Inhibitor, Protects Mice from Hepatic Ischemia/Reperfusion Injury by Inhibiting GSK-3β Signaling and Mitochondrial Permeability Transition

    Science.gov (United States)

    Fu, Hailong; Chen, Huan; Wang, Chengcai; Xu, Haitao; Liu, Fang; Guo, Meng; Wang, Quanxing; Shi, Xueyin

    2012-01-01

    Flurbiprofen acts as a nonselective inhibitor for cyclooxygenases (COX-1 and COX-2), but its impact on hepatic ischemia/reperfusion (I/R) injury remains unclear. Mice were randomized into sham, I/R and flurbiprofen (Flurb) groups. The hepatic artery and portal vein to the left and median liver lobes were occluded for 90 min and unclamped for reperfusion to establish a model of segmental (70%) warm hepatic ischemia. Pretreatment of animals with flurbiprofen prior to I/R insult significantly decreased serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH), and prevented hepatocytes from I/R-induced apoptosis/necrosis. Moreover, flurbiprofen dramatically inhibited mitochondrial permeability transition (MPT) pore opening, and thus prevented mitochondrial-related cell death and apoptosis. Mechanistic studies revealed that flurbiprofen markedly inhibited glycogen synthase kinase (GSK)-3β activity and increased phosphorylation of GSK-3β at Ser9, which, consequently, could modulate the adenine nucleotide translocase (ANT)–cyclophilin D (CyP-D) complex and the susceptibility to MPT induction. Therefore, administration of flurbiprofen prior to hepatic I/R ameliorates mitochondrial and hepatocellular damage through inhibition of MPT and inactivation of GSK-3β, and provides experimental evidence for clinical use of flurbiprofen to protect liver function in surgical settings in addition to its conventional use for pain relief. PMID:22714712

  20. Ochratoxin A inhibits the production of tissue factor and plasminogen activator inhibitor-2 by human blood mononuclear cells: Another potential mechanism of immune-suppression

    International Nuclear Information System (INIS)

    Rossiello, Maria R.; Rotunno, Crescenzia; Coluccia, Addolorata; Carratu, Maria R.; Di Santo, Angelomaria; Evangelista, Virgilio; Semeraro, Nicola; Colucci, Mario

    2008-01-01

    The mycotoxin ochratoxin A (OTA), an ubiquitous contaminant of food products endowed with a wide spectrum of toxicity, affects several functions of mononuclear leukocytes. Monocytes/macrophages play a major role in fibrin accumulation associated with immune-inflammatory processes through the production of tissue factor (TF) and plasminogen activator inhibitor 2 (PAI-2). We studied the effect of OTA on TF and PAI-2 production by human blood mononuclear cells (MNC). The cells were incubated for 3 or 18 h at 37 deg. C with non toxic OTA concentrations in the absence and in the presence of lipopolysaccharide (LPS) or other inflammatory agents. TF activity was measured by a one-stage clotting test. Antigen assays were performed by specific ELISAs in cell extracts or conditioned media and specific mRNAs were assessed by RT-PCR. OTA had no direct effect on TF and PAI-2 production by MNC. However, OTA caused a dose-dependent reduction in LPS-induced TF (activity, antigen and mRNA) and PAI-2 (antigen and mRNA) production with > 85% inhibition at 1 μg/ml. Similar results were obtained when monocyte-enriched preparations were used instead of MNC. TF production was also impaired by OTA (1 μg/ml) when MNC were stimulated with phorbol myristate acetate (98% inhibition), IL-1β (83%) or TNF-α (62%). The inhibition of TF and PAI-2 induction might represent a hitherto unrecognized mechanism whereby OTA exerts immunosuppressant activity

  1. Development of Classification Models for Identifying “True” P-glycoprotein (P-gp Inhibitors Through Inhibition, ATPase Activation and Monolayer Efflux Assays

    Directory of Open Access Journals (Sweden)

    Anna Maria Bianucci

    2012-06-01

    Full Text Available P-glycoprotein (P-gp is an efflux pump involved in the protection of tissues of several organs by influencing xenobiotic disposition. P-gp plays a key role in multidrug resistance and in the progression of many neurodegenerative diseases. The development of new and more effective therapeutics targeting P-gp thus represents an intriguing challenge in drug discovery. P-gp inhibition may be considered as a valid approach to improve drug bioavailability as well as to overcome drug resistance to many kinds of tumours characterized by the over-expression of this protein. This study aims to develop classification models from a unique dataset of 59 compounds for which there were homogeneous experimental data on P-gp inhibition, ATPase activation and monolayer efflux. For each experiment, the dataset was split into a training and a test set comprising 39 and 20 molecules, respectively. Rational splitting was accomplished using a sphere-exclusion type algorithm. After a two-step (internal/external validation, the best-performing classification models were used in a consensus predicting task for the identification of compounds named as “true” P-gp inhibitors, i.e., molecules able to inhibit P-gp without being effluxed by P-gp itself and simultaneously unable to activate the ATPase function.

  2. Inhibition of adipose triglyceride lipase (ATGL) by the putative tumor suppressor G0S2 or a small molecule inhibitor attenuates the growth of cancer cells.

    Science.gov (United States)

    Zagani, Rachid; El-Assaad, Wissal; Gamache, Isabelle; Teodoro, Jose G

    2015-09-29

    The G0/G1 switch gene 2 (G0S2) is methylated and silenced in a wide range of human cancers. The protein encoded by G0S2 is an endogenous inhibitor of lipid catabolism that directly binds adipose triglyceride lipase (ATGL). ATGL is the rate-limiting step in triglyceride metabolism. Although the G0S2 gene is silenced in cancer, the impact of ATGL in the growth and survival of cancer cells has never been addressed. Here we show that ectopic expression of G0S2 in non-small cell lung carcinomas (NSCL) inhibits triglyceride catabolism and results in lower cell growth. Similarly, knockdown of ATGL increased triglyceride levels, attenuated cell growth and promoted apoptosis. Conversely, knockdown of endogenous G0S2 enhanced the growth and invasiveness of cancer cells. G0S2 is strongly induced in acute promyelocytic leukemia (APL) cells in response to all trans retinoic acid (ATRA) and we show that inhibition of ATGL in these cells by G0S2 is required for efficacy of ATRA treatment. Our data uncover a novel tumor suppressor mechanism by which G0S2 directly inhibits activity of a key intracellular lipase. Our results suggest that elevated ATGL activity may be a general property of many cancer types and potentially represents a novel target for chemotherapy.

  3. The Host E3-Ubiquitin Ligase TRIM6 Ubiquitinates the Ebola Virus VP35 Protein and Promotes Virus Replication.

    Science.gov (United States)

    Bharaj, Preeti; Atkins, Colm; Luthra, Priya; Giraldo, Maria Isabel; Dawes, Brian E; Miorin, Lisa; Johnson, Jeffrey R; Krogan, Nevan J; Basler, Christopher F; Freiberg, Alexander N; Rajsbaum, Ricardo

    2017-09-15

    Ebola virus (EBOV), a member of the Filoviridae family, is a highly pathogenic virus that causes severe hemorrhagic fever in humans and is responsible for epidemics throughout sub-Saharan, central, and West Africa. The EBOV genome encodes VP35, an important viral protein involved in virus replication by acting as an essential cofactor of the viral polymerase as well as a potent antagonist of the host antiviral type I interferon (IFN-I) system. By using mass spectrometry analysis and coimmunoprecipitation assays, we show here that VP35 is ubiquitinated on lysine 309 (K309), a residue located on its IFN antagonist domain. We also found that VP35 interacts with TRIM6, a member of the E3-ubiquitin ligase tripartite motif (TRIM) family. We recently reported that TRIM6 promotes the synthesis of unanchored K48-linked polyubiquitin chains, which are not covalently attached to any protein, to induce efficient antiviral IFN-I-mediated responses. Consistent with this notion, VP35 also associated noncovalently with polyubiquitin chains and inhibited TRIM6-mediated IFN-I induction. Intriguingly, we also found that TRIM6 enhances EBOV polymerase activity in a minigenome assay and TRIM6 knockout cells have reduced replication of infectious EBOV, suggesting that VP35 hijacks TRIM6 to promote EBOV replication through ubiquitination. Our work provides evidence that TRIM6 is an important host cellular factor that promotes EBOV replication, and future studies will focus on whether TRIM6 could be targeted for therapeutic intervention against EBOV infection. IMPORTANCE EBOV belongs to a family of highly pathogenic viruses that cause severe hemorrhagic fever in humans and other mammals with high mortality rates (40 to 90%). Because of its high pathogenicity and lack of licensed antivirals and vaccines, EBOV is listed as a tier 1 select-agent risk group 4 pathogen. An important mechanism for the severity of EBOV infection is its suppression of innate immune responses. The EBOV VP35

  4. Ubiquitin-mediated proteolysis in Xenopus extract.

    Science.gov (United States)

    McDowell, Gary S; Philpott, Anna

    2016-01-01

    The small protein modifier, ubiquitin, can be covalently attached to proteins in the process of ubiquitylation, resulting in a variety of functional outcomes. In particular, the most commonly-associated and well-studied fate for proteins modified with ubiquitin is their ultimate destruction: degradation by the 26S proteasome via the ubiquitin-proteasome system, or digestion in lysosomes by proteolytic enzymes. From the earliest days of ubiquitylation research, a reliable and versatile "cell-in-a-test-tube" system has been employed in the form of cytoplasmic extracts from the eggs and embryos of the frog Xenopus laevis. Biochemical studies of ubiquitin and protein degradation using this system have led to significant advances particularly in the study of ubiquitin-mediated proteolysis, while the versatility of Xenopus as a developmental model has allowed investigation of the in vivo consequences of ubiquitylation. Here we describe the use and history of Xenopus extract in the study of ubiquitin-mediated protein degradation, and highlight the versatility of this system that has been exploited to uncover mechanisms and consequences of ubiquitylation and proteolysis.

  5. Ubiquitin-fusion as a strategy to modulate protein half-life: A3G antiviral activity revisited

    International Nuclear Information System (INIS)

    Cadima-Couto, Iris; Freitas-Vieira, Acilino; Nowarski, Roni; Britan-Rosich, Elena; Kotler, Moshe; Goncalves, Joao

    2009-01-01

    The human APOBEC3G (A3G) is a potent inhibitor of HIV-1 replication and its activity is suppressed by HIV-1 virion infectivity factor (Vif). Vif neutralizes A3G mainly by inducing its degradation in the proteasome and blocking its incorporation into HIV-1 virions. Assessing the time needed for A3G incorporation into virions is, therefore, important to determine how quickly Vif must act to induce its degradation. We show that modelling the intracellular half-life of A3G can induce its Vif-independent targeting to the ubiquitin-proteasome system. By using various amino acids (X) in a cleavable ubiquitin-X-A3G fusion, we demonstrate that the half-life (t1/2) of X-A3G can be manipulated. We show that A3G molecules with a half-life of 13 min are incorporated into virions, whereas those with a half-life shorter than 5 min were not. The amount of X-A3G incorporated into virions increases from 13 min (Phe-A3G) to 85 min (Asn-A3G) and remains constant after this time period. Interestingly, despite the presence of similar levels of Arg-A3G (t1/2 = 28 min) and Asp-A3G (t1/2 = 65 min) into HIV-1 Δvif virions, inhibition of viral infectivity was only evident in the presence of A3G proteins with a longer half-life (t1/2 ≥ 65 min).

  6. Heat shock protein 90 inhibitor enhances apoptosis by inhibiting the AKT pathway in thermal-stimulated SK-MEL-2 human melanoma cell line.

    Science.gov (United States)

    Shin, Min Kyung; Jeong, Ki-Heon; Choi, Hyeongwon; Ahn, Hye-Jin; Lee, Mu-Hyoung

    2018-02-08

    Heat shock proteins (Hsps) are chaperone proteins, which are upregulated after various stresses. Hsp90 inhibitors have been investigated as adjuvant therapies for the treatment of melanoma. Thermal ablation could be a treatment option for surgically unresectable melanoma or congenital nevomelanocytic nevi, however, there is a limitation such as the possibility of recurrence. We evaluated apoptosis in a melanoma cell line treated with the Hsp90 inhibitor 17-Dimethylaminoethylamino-17-demethoxygeldanamycin (17-DMAG), in hyperthermic conditions. SK-MEL-2 cells were stimulated at 43 °C for 1 h and treated with 0, 0.1 and 1 μM 17-DMAG. We evaluated the cell viability using MTT and apoptosis with HSP 90 inhibitor. We studied the protein expression of AKT, phospho-AKT, ERK, phospho-ERK, MAPK, and phospho-MAPK, caspase 3,7,9, and anti-poly (ADP-ribose) polymerase. 17-DMAG significantly inhibited the proliferation of the SK-MEL-2 cells at 37 °C (0.1 μM: 44.47% and 1 μM: 61.23%) and 43 °C (0.1 μM: 49.21% and 1 μM: 63.60%), suggesting synergism between thermal stimulation and 17-DMAG. 17-DMAG treatment increased the frequency of apoptotic cell populations to 2.17% (0.1 μM) and 3.05% (1 μM) in 37 °C controls, and 4.40% (0.1 μM) and 4.97% (1 μM) in the group stimulated at 43 °C. AKT phosphorylation were activated by thermal stimulation and inhibited by 17-DMAG. Hsp90 inhibitor treatment may be clinically applicable to enhance the apoptosis of melanoma cells in hyperthermic condition. Copyright © 2018 Japanese Society for Investigative Dermatology. Published by Elsevier B.V. All rights reserved.

  7. A noncovalent class of papain-like protease/deubiquitinase inhibitors blocks SARS virus replication

    Energy Technology Data Exchange (ETDEWEB)

    Ratia, Kiira; Pegan, Scott; Takayama, Jun; Sleeman, Katrina; Coughlin, Melissa; Baliji, Surendranath; Chaudhuri, Rima; Fu, Wentao; Prabhakar, Bellur S.; Johnson, Michael E.; Baker, Susan C.; Ghosh, Arun K.; Mesecar, Andrew D. (Loyola); (Purdue); (UIC)

    2008-10-27

    We report the discovery and optimization of a potent inhibitor against the papain-like protease (PLpro) from the coronavirus that causes severe acute respiratory syndrome (SARS-CoV). This unique protease is not only responsible for processing the viral polyprotein into its functional units but is also capable of cleaving ubiquitin and ISG15 conjugates and plays a significant role in helping SARS-CoV evade the human immune system. We screened a structurally diverse library of 50,080 compounds for inhibitors of PLpro and discovered a noncovalent lead inhibitor with an IC{sub 50} value of 20 {mu}M, which was improved to 600 nM via synthetic optimization. The resulting compound, GRL0617, inhibited SARS-CoV viral replication in Vero E6 cells with an EC{sub 50} of 15 {mu}M and had no associated cytotoxicity. The X-ray structure of PLpro in complex with GRL0617 indicates that the compound has a unique mode of inhibition whereby it binds within the S4-S3 subsites of the enzyme and induces a loop closure that shuts down catalysis at the active site. These findings provide proof-of-principle that PLpro is a viable target for development of antivirals directed against SARS-CoV, and that potent noncovalent cysteine protease inhibitors can be developed with specificity directed toward pathogenic deubiquitinating enzymes without inhibiting host DUBs.

  8. Glycosphingolipid synthesis inhibitor AMP-DNM lowers plasma cholesterol levels by promoting fecal cholesterol excretion without inhibiting cholesterol absorption

    NARCIS (Netherlands)

    Vrins, Carlos L. J.; Bietrix, Florence; Lombardo, Elisa; van Roomen, Cindy P. A. A.; Ottenhoff, Roelof; Overkleeft, Herman S.; Aerts, Johannes M.

    2012-01-01

    Inhibition of glycosphingolipid synthesis with iminosugar N-(5'-adamantane-1'-yl-methoxy)-pentyl-1-deoxynojirimycin (AMP-DNM) increases fecal neutral sterol output in mice. To investigate which pathways were involved in this increase, C57BI/6J mice were treated with AMP-DNM and/or ezetimibe. Fecal

  9. Assessing subunit dependency of the Plasmodium proteasome using small molecule inhibitors and active site probes.

    Science.gov (United States)

    Li, Hao; van der Linden, Wouter A; Verdoes, Martijn; Florea, Bogdan I; McAllister, Fiona E; Govindaswamy, Kavitha; Elias, Joshua E; Bhanot, Purnima; Overkleeft, Herman S; Bogyo, Matthew

    2014-08-15

    The ubiquitin-proteasome system (UPS) is a potential pathway for therapeutic intervention for pathogens such as Plasmodium, the causative agent of malaria. However, due to the essential nature of this proteolytic pathway, proteasome inhibitors must avoid inhibition of the host enzyme complex to prevent toxic side effects. The Plasmodium proteasome is poorly characterized, making rational design of inhibitors that induce selective parasite killing difficult. In this study, we developed a chemical probe that labels all catalytic sites of the Plasmodium proteasome. Using this probe, we identified several subunit selective small molecule inhibitors of the parasite enzyme complex. Treatment with an inhibitor that is specific for the β5 subunit during blood stage schizogony led to a dramatic decrease in parasite replication while short-term inhibition of the β2 subunit did not affect viability. Interestingly, coinhibition of both the β2 and β5 catalytic subunits resulted in enhanced parasite killing at all stages of the blood stage life cycle and reduced parasite levels in vivo to barely detectable levels. Parasite killing was achieved with overall low host toxicity, something that has not been possible with existing proteasome inhibitors. Our results highlight differences in the subunit dependency of the parasite and human proteasome, thus providing a strategy for development of potent antimalarial drugs with overall low host toxicity.

  10. Inhibitors of the proteasome suppress homologous DNA recombination in mammalian cells.

    Science.gov (United States)

    Murakawa, Yasuhiro; Sonoda, Eiichiro; Barber, Louise J; Zeng, Weihua; Yokomori, Kyoko; Kimura, Hiroshi; Niimi, Atsuko; Lehmann, Alan; Zhao, Guang Yu; Hochegger, Helfrid; Boulton, Simon J; Takeda, Shunichi

    2007-09-15

    Proteasome inhibitors are novel antitumor agents against multiple myeloma and other malignancies. Despite the increasing clinical application, the molecular basis of their antitumor effect has been poorly understood due to the involvement of the ubiquitin-proteasome pathway in multiple cellular metabolisms. Here, we show that treatment of cells with proteasome inhibitors has no significant effect on nonhomologous end joining but suppresses homologous recombination (HR), which plays a key role in DNA double-strand break (DSB) repair. In this study, we treat human cells with proteasome inhibitors and show that the inhibition of the proteasome reduces the efficiency of HR-dependent repair of an artificial HR substrate. We further show that inhibition of the proteasome interferes with the activation of Rad51, a key factor for HR, although it does not affect the activation of ATM, gammaH2AX, or Mre11. These data show that the proteasome-mediated destruction is required for the promotion of HR at an early step. We suggest that the defect in HR-mediated DNA repair caused by proteasome inhibitors contributes to antitumor effect, as HR plays an essential role in cellular proliferation. Moreover, because HR plays key roles in the repair of DSBs caused by chemotherapeutic agents such as cisplatin and by radiotherapy, proteasome inhibitors may enhance the efficacy of these treatments through the suppression of HR-mediated DNA repair pathways.

  11. Effects of 17β-estradiol on radiation transformation in vitro; inhibition of effects by protease inhibitors

    International Nuclear Information System (INIS)

    Kennedy, A.R.; Weichselbaum, R.R.

    1981-01-01

    The effects of 17β-estradiol, given either alone or with X-radiation, on the induction of malignant transformation were investigated in vitro. Treatment with 10 -6 M 17β-estradiol for 6 weeks, or 10 -5 M 17β-estradiol for only 5 days, induced malignant transformation in C3H 10T1/2 cells. Estradiol also acted as a cocarcinogen for X-ray induced transformation; the results indicated an additive effect when the cells were exposed to both agents together. The protease inhibitors antipain and leupeptin suppressed estradiol induced transformation as well as the additive effect observed for estradiol-radiation transformation. (author)

  12. A Review on Ubiquitination of Neurotrophin Receptors: Facts and Perspectives

    Science.gov (United States)

    Sánchez-Sánchez, Julia; Arévalo, Juan Carlos

    2017-01-01

    Ubiquitination is a reversible post-translational modification involved in a plethora of different physiological functions. Among the substrates that are ubiquitinated, neurotrophin receptors (TrkA, TrkB, TrkC, and p75NTR) have been studied recently. TrkA is the most studied receptor in terms of its ubiquitination, and different E3 ubiquitin ligases and deubiquitinases have been implicated in its ubiquitination, whereas not much is known about the other neurotrophin receptors aside from their ubiquitination. Additional studies are needed that focus on the ubiquitination of TrkB, TrkC, and p75NTR in order to further understand the role of ubiquitination in their physiological and pathological functions. Here we review what is currently known regarding the ubiquitination of neurotrophin receptors and its physiological and pathological relevance. PMID:28335430

  13. Siah1/2 Ubiquitin Ligases in ER Stress Signaling in Melanoma

    Science.gov (United States)

    2016-12-01

    enriched (and downregulated) upon Siah2 KD (Fig 4). RNAseq to identify genes and pathways that are deregulated in the Siah2 KD melanomas, led us...June 2016), Signgene Symposium (Berlin, Germany ; Sept. 2016), European Society for Pigment Cell Research (Milano, Italy; Sept. 2016), Centre National...Flaherty KT, Ronai ZA. Downregulation of the Ubiquitin Ligase RNF125 Underlies Resistance of Melanoma Cells to BRAF Inhibitors via JAK1 Deregulation

  14. Inhibition of autophagy induced by proteasome inhibition increases cell death in human SHG-44 glioma cells.

    Science.gov (United States)

    Ge, Peng-Fei; Zhang, Ji-Zhou; Wang, Xiao-Fei; Meng, Fan-Kai; Li, Wen-Chen; Luan, Yong-Xin; Ling, Feng; Luo, Yi-Nan

    2009-07-01

    The ubiquitin-proteasome system (UPS) and lysosome-dependent macroautophagy (autophagy) are two major intracellular pathways for protein degradation. Recent studies suggest that proteasome inhibitors may reduce tumor growth and activate autophagy. Due to the dual roles of autophagy in tumor cell survival and death, the effect of autophagy on the destiny of glioma cells remains unclear. In this study, we sought to investigate whether inhibition of the proteasome can induce autophagy and the effects of autophagy on the fate of human SHG-44 glioma cells. The proteasome inhibitor MG-132 was used to induce autophagy in SHG-44 glioma cells, and the effect of autophagy on the survival of SHG-44 glioma cells was investigated using an autophagy inhibitor 3-MA. Cell viability was measured by MTT assay. Apoptosis and cell cycle were detected by flow cytometry. The expression of autophagy related proteins was determined by Western blot. MG-132 inhibited cell proliferation, induced cell death and cell cycle arrest at G(2)/M phase, and activated autophagy in SHG-44 glioma cells. The expression of autophagy-related Beclin-1 and LC3-I was significantly up-regulated and part of LC3-I was converted into LC3-II. However, when SHG-44 glioma cells were co-treated with MG-132 and 3-MA, the cells became less viable, but cell death and cell numbers at G(2)/M phase increased. Moreover, the accumulation of acidic vesicular organelles was decreased, the expression of Beclin-1 and LC3 was significantly down-regulated and the conversion of LC3-II from LC3-I was also inhibited. Inhibition of the proteasome can induce autophagy in human SHG-44 glioma cells, and inhibition of autophagy increases cell death. This discovery may shed new light on the effect of autophagy on modulating the fate of SHG-44 glioma cells.Acta Pharmacologica Sinica (2009) 30: 1046-1052; doi: 10.1038/aps.2009.71.

  15. Epidermal Growth Factor Cytoplasmic Domain Affects ErbB Protein Degradation by the Lysosomal and Ubiquitin-Proteasome Pathway in Human Cancer Cells

    Directory of Open Access Journals (Sweden)

    Aleksandra Glogowska

    2012-05-01

    Full Text Available The cytoplasmic domains of EGF-like ligands, including EGF cytoplasmic domain (EGFcyt, have important biological functions. Using specific constructs and peptides of human EGF cytoplasmic domain, we demonstrate that EGFcyt facilitates lysosomal and proteasomal protein degradation, and this coincided with growth inhibition of human thyroid and glioma carcinoma cells. EGFcyt and exon 22–23-encoded peptide (EGF22.23 enhanced procathepsin B (procathB expression and procathB-mediated lysosomal degradation of EGFR/ErbB1 as determined by inhibitors for procathB and the lysosomal ATPase inhibitor BafA1. Presence of mbEGFctF, EGFcyt, EGF22.23, and exon 23-encoded peptides suppressed the expression of the deubiqitinating enzyme ubiquitin C-terminal hydrolase-L1 (UCH-L1. This coincided with hyperubiquitination of total cellular proteins and ErbB1/2 and reduced proteasome activity. Upon small interfering RNA-mediated silencing of endogenously expressed UCH-L1, a similar hyperubiquitinylation phenotype, reduced ErbB1/2 content, and attenuated growth was observed. The exon 23-encoded peptide region of EGFcyt was important for these biologic actions. Structural homology modeling of human EGFcyt showed that this molecular region formed an exposed surface loop. Peptides derived from this EGFcyt loop structure may aid in the design of novel peptide therapeutics aimed at inhibiting growth of cancer cells.

  16. Regulation of DNA double-strand break repair by ubiquitin and ubiquitin-like modifiers

    DEFF Research Database (Denmark)

    Schwertman, Petra; Bekker-Jensen, Simon; Mailand, Niels

    2016-01-01

    DNA double-strand breaks (DSBs) are highly cytotoxic DNA lesions. The swift recognition and faithful repair of such damage is crucial for the maintenance of genomic stability, as well as for cell and organismal fitness. Signalling by ubiquitin, SUMO and other ubiquitin-like modifiers (UBLs...

  17. ETS transcription factor ELF5 induces lumen formation in a 3D model of mammary morphogenesis and its expression is inhibited by Jak2 inhibitor TG101348.

    Science.gov (United States)

    Chean, Jennifer; Chen, Charng-Jui; Shively, John E

    2017-10-01

    The loss of expression of a single gene can revert normal tissue to a malignant phenotype. For example, while normal breast has high lumenal expression of CEACAM1, the majority of breast cancers exhibit the early loss of this gene with the concurrent loss of their lumenal phenotype. MCF7 cells that lack CEACAM1 expression and fail to form lumena in 3D culture, regain the normal phenotype when transfected with CEACAM1. In order to probe the mechanism of this gain of function, we treated these cells with the clinically relevant Jak2 inhibitor TG101348 (TG), expecting that disruption of the prolactin receptor signaling pathway would interfere with the positive effects of transfection of MCF7 cells with CEACAM1. Indeed, lumen formation was inhibited, resulting in the down regulation of a set of genes, likely involved in the complex process of lumen formation. As expected, inhibition of the expression of many of these genes also inhibited lumen formation, confirming their involvement in a single pathway. Among the genes identified by the inhibition assay, ETS transcription factor ELF5 stood out, since it has been identified as a master regulator of mammary morphogenesis, and is associated with prolactin receptor signaling. When ELF5 was transfected into the parental MCF7 cells that lack CEACAM1, lumen formation was restored, indicating that ELF5 can replace CEACAM1 in this model system of lumenogenesis. We conclude that the event(s) that led to the loss of expression of CEACAM1 is epistatic in that multiple genes associated with a critical pathway were affected, but that restoration of the normal phenotype can be achieved with reactivation of certain genes at various nodal points in tissue morphogenesis. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Repression of protein translation and mTOR signaling by proteasome inhibitor in colon cancer cells

    International Nuclear Information System (INIS)

    Wu, William Ka Kei; Volta, Viviana; Cho, Chi Hin; Wu, Ya Chun; Li, Hai Tao; Yu, Le; Li, Zhi Jie; Sung, Joseph Jao Yiu

    2009-01-01

    Protein homeostasis relies on a balance between protein synthesis and protein degradation. The ubiquitin-proteasome system is a major catabolic pathway for protein degradation. In this respect, proteasome inhibition has been used therapeutically for the treatment of cancer. Whether inhibition of protein degradation by proteasome inhibitor can repress protein translation via a negative feedback mechanism, however, is unknown. In this study, proteasome inhibitor MG-132 lowered the proliferation of colon cancer cells HT-29 and SW1116. In this connection, MG-132 reduced the phosphorylation of mammalian target of rapamycin (mTOR) at Ser2448 and Ser2481 and the phosphorylation of its downstream targets 4E-BP1 and p70/p85 S6 kinases. Further analysis revealed that MG-132 inhibited protein translation as evidenced by the reductions of 35 S-methionine incorporation and polysomes/80S ratio. Knockdown of raptor, a structural component of mTOR complex 1, mimicked the anti-proliferative effect of MG-132. To conclude, we demonstrate that the inhibition of protein degradation by proteasome inhibitor represses mTOR signaling and protein translation in colon cancer cells.

  19. PHA665752, a small-molecule inhibitor of c-Met, inhibits hepatocyte growth factor-stimulated migration and proliferation of c-Met-positive neuroblastoma cells

    International Nuclear Information System (INIS)

    Crosswell, Hal E; Dasgupta, Anindya; Alvarado, Carlos S; Watt, Tanya; Christensen, James G; De, Pradip; Durden, Donald L; Findley, Harry W

    2009-01-01

    c-Met is a tyrosine kinase receptor for hepatocyte growth factor/scatter factor (HGF/SF), and both c-Met and its ligand are expressed in a variety of tissues. C-Met/HGF/SF signaling is essential for normal embryogenesis, organogenesis, and tissue regeneration. Abnormal c-Met/HGF/SF signaling has been demonstrated in different tumors and linked to aggressive and metastatic tumor phenotypes. In vitro and in vivo studies have demonstrated inhibition of c-Met/HGF/SF signaling by the small-molecule inhibitor PHA665752. This study investigated c-Met and HGF expression in two neuroblastoma (NBL) cell lines and tumor tissue from patients with NBL, as well as the effects of PHA665752 on growth and motility of NBL cell lines. The effect of the tumor suppressor protein PTEN on migration and proliferation of tumor cells treated with PHA665752 was also evaluated. Expression of c-Met and HGF in NBL cell lines SH-EP and SH-SY5Y and primary tumor tissue was assessed by immunohistochemistry and quantitative RT-PCR. The effect of PHA665752 on c-Met/HGF signaling involved in NBL cell proliferation and migration was evaluated in c-Met-positive cells and c-Met-transfected cells. The transwell chemotaxis assay and the MTT assay were used to measure migration and proliferation/cell-survival of tumor cells, respectively. The PPAR-γ agonist rosiglitazone was used to assess the effect of PTEN on PHA665752-induced inhibition of NBL cell proliferation/cell-survival and migration High c-Met expression was detected in SH-EP cells and primary tumors from patients with advanced-stage disease. C-Met/HGF signaling induced both migration and proliferation of SH-EP cells. Migration and proliferation/cell-survival were inhibited by PHA665752 in a dose-dependent manner. We also found that induced overexpression of PTEN following treatment with rosiglitazone significantly enhanced the inhibitory effect of PHA665752 on NBL-cell migration and proliferation. c-Met is highly expressed in most tumors from

  20. Locostatin, a disrupter of Raf kinase inhibitor protein, inhibits extracellular matrix production, proliferation, and migration in human uterine leiomyoma and myometrial cells.

    Science.gov (United States)

    Janjusevic, Milijana; Greco, Stefania; Islam, Md Soriful; Castellucci, Clara; Ciavattini, Andrea; Toti, Paolo; Petraglia, Felice; Ciarmela, Pasquapina

    2016-11-01

    To investigate the presence of Raf kinase inhibitor protein (RKIP) in human myometrium and leiomyoma as well as to determine the effect of locostatin (RKIP inhibitor) on extracellular matrix (ECM) production, proliferation, and migration in human myometrial and leiomyoma cells. Laboratory study. Human myometrium and leiomyoma. Thirty premenopausal women who were admitted to the hospital for myomectomy or hysterectomy. Myometrial and leiomyoma tissues were used to investigate the localization and the expression level of RKIP through immunohistochemistry and Western blotting. Myometrial and leiomyoma cells were treated with locostatin (10 μM) to measure ECM expression by real-time polymerase chain reaction, GSK3β expression by Western blotting, cell migration by wound-healing assay, and cell proliferation by MTT assay and immunocytochemistry. The expression of RKIP in human myometrial and leiomyoma tissue; ECM components and GSK3β expression, migration, and proliferation in myometrial and leiomyoma cells. RKIP is expressed in human myometrial and leiomyoma tissue. Locostatin treatment resulted in the activation of the mitogen-activated protein kinase (MAPK) signal pathway (ERK phosphorylation), providing a powerful validation of our targeting protocol. Further, RKIP inhibition by locostatin reduces ECM components. Moreover, the inhibition of RKIP by locostatin impaired cell proliferation and migration in both leiomyoma and myometrial cells. Finally, locostatin treatment reduced GSK3β expression. Therefore, even if the activation of MAPK pathway should increase proliferation and migration, the destabilization of GSK3β leads to the reduction of proliferation and migration of myometrial and leiomyoma cells. Our results indicate that RKIP may be involved in leiomyoma pathophysiology. Copyright © 2016 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

  1. The guanylhydrazone CNI-1493: an inhibitor with dual activity against malaria-inhibition of host cell pro-inflammatory cytokine release and parasitic deoxyhypusine synthase.

    Science.gov (United States)

    Specht, Sabine; Sarite, Salem Ramadan; Hauber, Ilona; Hauber, Joachim; Görbig, Ulf F; Meier, Chris; Bevec, Dorian; Hoerauf, Achim; Kaiser, Annette

    2008-05-01

    Malaria is still a major cause of death in the tropics. There is an urgent need for new anti-malarial drugs because drug-resistant plasmodia frequently occur. Over recent years, we elucidated the biosynthesis of hypusine, a novel amino acid contained in eukaryotic initiation factor 5A (eIF-5A) in Plasmodium. Hypusine biosynthesis involves catalysis of deoxyhypusine synthase (DHS) in the first step of post-translational modification. In a screen for new inhibitors of purified plasmodium DHS, CNI-1493, a novel selective pro-inflammatory cytokine inhibitor used in clinical phase II for the treatment of Crohn's disease, inhibited the enzyme of the parasite 3-fold at a concentration of 2 microM. In vitro experiments with 200 microM CNI-1493 in Plasmodium-infected erythrocytes, which lack nuclei and DHS protein, showed a parasite clearance within 2 days. This can presumably be attributed to an anti-proliferating effect because of the inhibition of DHS by the parasite. The determined IC50 of CNI-1493 was 135.79 microM after 72 h. In vivo application of this substance in Plasmodium berghei ANKA-infected C57BL/6 mice significantly reduced parasitemia after dosage of 1 mg/kg or 4 mg/kg/body weight and prevented death of mice with cerebral malaria. This effect was paralleled by a decrease in serum TNF levels of the mice. We suggest that the new mechanism of CNI-1493 is caused by a decrease in modified eIF-5A biosynthesis with a downstream effect on the TNF synthesis of the host. From the current data, we consider CNI-1493 to be a promising drug for anti-malarial therapy because of its combined action, i.e., the decrease in eIF-5A biosynthesis of the parasite and host cell TNF biosynthesis.

  2. A trypsin inhibitor from Tecoma stans leaves inhibits growth and promotes ATP depletion and lipid peroxidation in Candida albicans and Candida krusei

    Directory of Open Access Journals (Sweden)

    Leydianne Leite de Siqueira Patriota

    2016-04-01

    Full Text Available Tecoma stans (yellow elder has shown medicinal properties and antimicrobial activity. Previous reports on antifungal activity of T. stans preparations and presence of trypsin inhibitor activity from T. stans leaves stimulated the investigation reported here. In this work, we proceeded to the purification and characterization of a trypsin inhibitor (TesTI, which was investigated for anti-Candida activity. Finally, in order to determine the potential of TesTI as a new natural chemotherapeutic product, its cytotoxicity to human peripheral blood mononuclear cells (PBMCs was evaluated. TesTI was isolated from saline extract by ammonium sulphate fractionation followed by ion exchange and gel filtration chromatographies. Antifungal activity was evaluated by determining the minimal inhibitory (MIC and fungicide (MFC concentrations using fungal cultures containing only yeast form or both yeast and hyphal forms. Candida cells treated with TesTI were evaluated for intracellular ATP levels and lipid peroxidation. Cytotoxicity of TesTI to PBMCs was evaluated by MTT assay. TesTI (39.8 kDa, pI 3.41, Ki 43 nM inhibited similarly the growth of both C. albicans and C. krusei culture types at MIC of 100 µg/mL. The MFCs were 200 µg/mL for C. albicans and C. krusei. Time-response curves revealed that TesTI (at MIC was more effective at inhibiting the replication of C. albicans cells. At MIC, TesTI promoted reduction of ATP levels and lipid peroxidation in the Candida cells, being not cytotoxic to PBMCs. In conclusion, TesTI is an antifungal agent against C. albicans and C. krusei, without toxicity to human cells.

  3. Galectin-1 Inhibitor OTX008 Induces Tumor Vessel Normalization and Tumor Growth Inhibition in Human Head and Neck Squamous Cell Carcinoma Models.

    Science.gov (United States)

    Koonce, Nathan A; Griffin, Robert J; Dings, Ruud P M

    2017-12-09

    Galectin-1 is a hypoxia-regulated protein and a prognostic marker in head and neck squamous cell carcinomas (HNSCC). Here we assessed the ability of non-peptidic galectin-1 inhibitor OTX008 to improve tumor oxygenation levels via tumor vessel normalization as well as tumor growth inhibition in two human HNSCC tumor models, the human laryngeal squamous carcinoma SQ20B and the human epithelial type 2 HEp-2. Tumor-bearing mice were treated with OTX008, Anginex, or Avastin and oxygen levels were determined by fiber-optics and molecular marker pimonidazole binding. Immuno-fluorescence was used to determine vessel normalization status. Continued OTX008 treatment caused a transient reoxygenation in SQ20B tumors peaking on day 14, while a steady increase in tumor oxygenation was observed over 21 days in the HEp-2 model. A >50% decrease in immunohistochemical staining for tumor hypoxia verified the oxygenation data measured using a partial pressure of oxygen (pO₂) probe. Additionally, OTX008 induced tumor vessel normalization as tumor pericyte coverage increased by approximately 40% without inducing any toxicity. Moreover, OTX008 inhibited tumor growth as effectively as Anginex and Avastin, except in the HEp-2 model where Avastin was found to suspend tumor growth. Galectin-1 inhibitor OTX008 transiently increased overall tumor oxygenation via vessel normalization to various degrees in both HNSCC models. These findings suggest that targeting galectin-1-e.g., by OTX008-may be an effective approach to treat cancer patients as stand-alone therapy or in combination with other standards of care.

  4. The dual mTORC1 and mTORC2 inhibitor AZD8055 inhibits head and neck squamous cell carcinoma cell growth in vivo and in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qiang; Song, Xin-mao; Ji, Yang-yang; Jiang, Hui; Xu, Lin-gen, E-mail: drlingenxu@126.com

    2013-11-01

    Highlights: •AZD8055 induces significant cytotoxic effects in cultured HNSCC cells. •AZD8055 blocks mTORC1 and mTORC2 activation in cultured HNSCC cells. •JNK activation is required for AZD8055-induced HNSCC cell death. •AZD8055 inhibits Hep-2 cell growth in vivo, and was more efficient than rapamycin. -- Abstract: The serine/threonine kinase mammalian target of rapamycin (mTOR) promotes cell survival and proliferation, and is constitutively activated in head and neck squamous cell carcinoma (HNSCC). Thus mTOR is an important target for drug development in this disease. Here we tested the anti-tumor ability of AZD8055, the novel mTOR inhibitor, in HNSCC cells. AZD8055 induced dramatic cell death of HNSCC lines (Hep-2 and SCC-9) through autophagy. AZD8055 blocked both mTOR complex (mTORC) 1 and mTORC2 activation without affecting Erk in cultured HNSCC cells. Meanwhile, AZD8055 induced significant c-Jun N-terminal kinase (JNK) activation, which was also required for cancer cell death. JNK inhibition by its inhibitors (SP 600125 and JNK-IN-8), or by RNA interference (RNAi) alleviated AZD8055-induced cell death. Finally, AZD8055 markedly increased the survival of Hep-2 transplanted mice through a significant reduction of tumor growth, without apparent toxicity, and its anti-tumor ability was more potent than rapamycin. Meanwhile, AZD8055 administration activated JNK while blocking mTORC1/2 in Hep-2 tumor engrafts. Our current results strongly suggest that AZD8055 may be further investigated for HNSCC treatment in clinical trials.

  5. Role of the ubiquitin-proteasome system in brain ischemia: friend or foe?

    Science.gov (United States)

    Caldeira, Margarida V; Salazar, Ivan L; Curcio, Michele; Canzoniero, Lorella M T; Duarte, Carlos B

    2014-01-01

    The ubiquitin-proteasome system (UPS) is a catalytic machinery that targets numerous cellular proteins for degradation, thus being essential to control a wide range of basic cellular processes and cell survival. Degradation of intracellular proteins via the UPS is a tightly regulated process initiated by tagging a target protein with a specific ubiquitin chain. Neurons are particularly vulnerable to any change in protein composition, and therefore the UPS is a key regulator of neuronal physiology. Alterations in UPS activity may induce pathological responses, ultimately leading to neuronal cell death. Brain ischemia triggers a complex series of biochemical and molecular mechanisms, such as an inflammatory response, an exacerbated production of misfolded and oxidized proteins, due to oxidative stress, and the breakdown of cellular integrity mainly mediated by excitotoxic glutamatergic signaling. Brain ischemia also damages protein degradation pathways which, together with the overproduction of damaged proteins and consequent upregulation of ubiquitin-conjugated proteins, contribute to the accumulation of ubiquitin-containing proteinaceous deposits. Despite recent advances, the factors leading to deposition of such aggregates after cerebral ischemic injury remain poorly understood. This review discusses the current knowledge on the role of the UPS in brain function and the molecular mechanisms contributing to UPS dysfunction in brain ischemia with consequent accumulation of ubiquitin-containing proteins. Chemical inhibitors of the proteasome and small molecule inhibitors of deubiquitinating enzymes, which promote the degradation of proteins by the proteasome, were both shown to provide neuroprotection in brain ischemia, and this apparent contradiction is also discussed in this review. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. α-Amylase inhibitor-1 gene from Phaseolus vulgaris expressed in Coffea arabica plants inhibits α-amylases from the coffee berry borer pest

    Directory of Open Access Journals (Sweden)

    Oliveira-Neto Osmundo B

    2010-06-01

    Full Text Available Abstract Background Coffee is an important crop and is crucial to the economy of many developing countries, generating around US$70 billion per year. There are 115 species in the Coffea genus, but only two, C. arabica and C. canephora, are commercially cultivated. Coffee plants are attacked by many pathogens and insect-pests, which affect not only the production of coffee but also its grain quality, reducing the commercial value of the product. The main insect-pest, the coffee berry borer (Hypotheneumus hampei, is responsible for worldwide annual losses of around US$500 million. The coffee berry borer exclusively damages the coffee berries, and it is mainly controlled by organochlorine insecticides that are both toxic and carcinogenic. Unfortunately, natural resistance in the genus Coffea to H. hampei has not been documented. To overcome these problems, biotechnological strategies can be used to introduce an α-amylase inhibitor gene (α-AI1, which confers resistance against the coffee berry borer insect-pest, into C. arabica plants. Results We transformed C. arabica with the α-amylase inhibitor-1 gene (α-AI1 from the common bean, Phaseolus vulgaris, under control of the seed-specific phytohemagglutinin promoter (PHA-L. The presence of the α-AI1 gene in six regenerated transgenic T1 coffee plants was identified by PCR and Southern blotting. Immunoblotting and ELISA experiments using antibodies against α-AI1 inhibitor showed a maximum α-AI1 concentration of 0.29% in crude seed extracts. Inhibitory in vitro assays of the α-AI1 protein against H. hampei α-amylases in transgenic seed extracts showed up to 88% inhibition of enzyme activity. Conclusions This is the first report showing the production of transgenic coffee plants with the biotechnological potential to control the coffee berry borer, the most important insect-pest of crop coffee.

  7. Alpha-amylase inhibitor-1 gene from Phaseolus vulgaris expressed in Coffea arabica plants inhibits alpha-amylases from the coffee berry borer pest.

    Science.gov (United States)

    Barbosa, Aulus E A D; Albuquerque, Erika V S; Silva, Maria C M; Souza, Djair S L; Oliveira-Neto, Osmundo B; Valencia, Arnubio; Rocha, Thales L; Grossi-de-Sa, Maria F

    2010-06-17

    Coffee is an important crop and is crucial to the economy of many developing countries, generating around US$70 billion per year. There are 115 species in the Coffea genus, but only two, C. arabica and C. canephora, are commercially cultivated. Coffee plants are attacked by many pathogens and insect-pests, which affect not only the production of coffee but also its grain quality, reducing the commercial value of the product. The main insect-pest, the coffee berry borer (Hypotheneumus hampei), is responsible for worldwide annual losses of around US$500 million. The coffee berry borer exclusively damages the coffee berries, and it is mainly controlled by organochlorine insecticides that are both toxic and carcinogenic. Unfortunately, natural resistance in the genus Coffea to H. hampei has not been documented. To overcome these problems, biotechnological strategies can be used to introduce an alpha-amylase inhibitor gene (alpha-AI1), which confers resistance against the coffee berry borer insect-pest, into C. arabica plants. We transformed C. arabica with the alpha-amylase inhibitor-1 gene (alpha-AI1) from the common bean, Phaseolus vulgaris, under control of the seed-specific phytohemagglutinin promoter (PHA-L). The presence of the alpha-AI1 gene in six regenerated transgenic T1 coffee plants was identified by PCR and Southern blotting. Immunoblotting and ELISA experiments using antibodies against alpha-AI1 inhibitor showed a maximum alpha-AI1 concentration of 0.29% in crude seed extracts. Inhibitory in vitro assays of the alpha-AI1 protein against H. hampei alpha-amylases in transgenic seed extracts showed up to 88% inhibition of enzyme activity. This is the first report showing the production of transgenic coffee plants with the biotechnological potential to control the coffee berry borer, the most important insect-pest of crop coffee.

  8. Nitrifier-induced denitrification is an important source of soil nitrous oxide and can be inhibited by a nitrification inhibitor 3,4-dimethylpyrazole phosphate.

    Science.gov (United States)

    Shi, Xiuzhen; Hu, Hang-Wei; Zhu-Barker, Xia; Hayden, Helen; Wang, Juntao; Suter, Helen; Chen, Deli; He, Ji-Zheng

    2017-12-01

    Soil ecosystem represents the largest contributor to global nitrous oxide (N 2 O) production, which is regulated by a wide variety of microbial communities in multiple biological pathways. A mechanistic understanding of these N 2 O production biological pathways in complex soil environment is essential for improving model performance and developing innovative mitigation strategies. Here, combined approaches of the 15 N- 18 O labelling technique, transcriptome analysis, and Illumina MiSeq sequencing were used to identify the relative contributions of four N 2 O pathways including nitrification, nitrifier-induced denitrification (nitrifier denitrification and nitrification-coupled denitrification) and heterotrophic denitrification in six soils (alkaline vs. acid soils). In alkaline soils, nitrification and nitrifier-induced denitrification were the dominant pathways of N 2 O production, and application of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) significantly reduced the N 2 O production from these pathways; this is probably due to the observed reduction in the expression of the amoA gene in ammonia-oxidizing bacteria (AOB) in the DMPP-amended treatments. In acid soils, however, heterotrophic denitrification was the main source for N 2 O production, and was not impacted by the application of DMPP. Our results provide robust evidence that the nitrification inhibitor DMPP can inhibit the N 2 O production from nitrifier-induced denitrification, a potential significant source of N 2 O production in agricultural soils. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

  9. CyclinG1 Amplification Enhances Aurora Kinase Inhibitor-Induced Polyploid Resistance and Inhibition of Bcl-2 Pathway Reverses the Resistance

    Directory of Open Access Journals (Sweden)

    Wenfeng Zhang

    2017-08-01

    Full Text Available Background/Aims: CyclinG1 (CycG1 is frequently overexpressed in solid tumors and overexpression of CycG1 promotes cell survival upon paclitaxel exposure by inducing polyploidy. Whether and how CycG1 regulates polyploidization caused by small molecular targeted inhibitors remains unclear. Methods: Immunohistochemistry and immunoblotting were utilized to examine protein expression. Cell proliferation was measured by ATPlite assay, and cell cycle distribution and apoptosis were measured by flow cytometry and/or DNA fragmentation assays. Results: Overexpression of CycG1 in breast cancer cells caused apoptosis-resistant polyploidy upon treatment with Aurora kinase inhibitor, ZM447439 (ZM. Addition of ABT-263, a small-molecule BH3 mimetic, to ZM, produced a synergistic loss of cell viability with greater sustained tumor growth inhibition in breast cancer cell lines. Decrease of Mcl-1 and increase of NOXA caused by ZM treatment, were responsible for the synergy. Furthermore, CycG1 was highly expressed in Triple-Negative-Breast-Cancer patients treated with paclitaxel and was paralleled by decreased cell survival. Conclusion: CycG1 is a crucial factor in ZM-induced polyploidy resistance, and ABT-263/ZM combination hold therapeutic utility in the CycG1-amplified subset of breast cancer and CycG1, thus, is a promising target in breast cancer.

  10. The H+/K+ ATPase Inhibitor SCH-28080 Inhibits Insulin Secretion and Induces Cell Death in INS-1E Rat Insulinoma Cells

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    Martin Jakab

    2017-10-01

    Full Text Available Background/Aims: Glucose-stimulated insulin secretion (GSIS of pancreatic β-cells involves glucose uptake and metabolism, closure of KATP channels and depolarization of the cell membrane potential (Vmem, activation of voltage-activated Ca2+ currents (ICav and influx of Ca2+, which eventually triggers hormone exocytosis. Beside this classical pathway, KATP-independent mechanisms such as changes in intracellular pH (pHi or cell volume, which also affect β-cell viability, can elicit or modify insulin release. In β-cells the regulation of pHi is mainly accomplished by Na+/H+ exchangers (NHEs. To investigate if other proton extrusion mechanisms than NHEs are involved in pH regulation, we tested for the presence of the non-gastric H+/K+ ATPase in rat insulinoma cells and assessed effects of the H+/K+ ATPase inhibitor SCH-28080 on insulin secretion, cell viability and apoptosis. Methods: In INS-1E cell cultures, H+/K+ ATPase gene and protein expression was analyzed by reverse transcription PCR and Western blotting. Intracellular pH (pHi recovery after acute acidic load was measured by NH4Cl prepulsing using BCECF. Insulin secretion was determined by ELISA from the cell culture supernatant. Vmem, K+ and Ca2+ currents were recorded using patch clamp. Overall cell responses were determined using resazurin (viability and cytotoxicity assays. The mean cell volume (MCV, cell granularity (side-scatter; SSC, phosphatidylserine (PS exposure, cell membrane integrity, caspase activity and the mitochondrial membrane potential (ΔΨm were measured by flow cytometry. Results: We found that the α-subunit of the non-gastric H+/K+ ATPase (HKα2 is expressed on mRNA and protein level. However, compared to rat colon tissue, in INS-1E cells mRNA abundance was very low. In NH4Cl prepulsing experiments no K+-dependent pHi recovery was observed under Na+-free extracellular conditions. Nonetheless within 1 h, 20 µM SCH-28080 inhibited GSIS by ∼50%, while basal release

  11. Effects of 17 beta-estradiol on radiation transformation in vitro; inhibition of effects by protease inhibitors

    International Nuclear Information System (INIS)

    Kennedy, A.R.; Weichselbaum, R.R.

    1981-01-01

    We have investigated the effects of 17 beta-estradiol, given both alone and with X-irradiation, on the induction of malignant transformation in vitro. Treatment with 10(-6)M 17 beta-estradiol for 6 weeks, or 10(-5)M 17 beta-estradiol for only 5 days, induced malignant transformation in C3H 10T1/2 cells. Estradiol also acted as a cocarcinogen for X-ray induced transformation; the results indicate an additive effect when the cells were exposed to both agents together. The protease inhibitors antipain and leupeptin suppressed estradiol induced transformation as well as the additive effect observed for estradiol-radiation transformation

  12. Effects of 17 beta-estradiol on radiation transformation in vitro; inhibition of effects by protease inhibitors

    Energy Technology Data Exchange (ETDEWEB)

    Kennedy, A.R.; Weichselbaum, R.R.

    1981-01-01

    We have investigated the effects of 17 beta-estradiol, given both alone and with X-irradiation, on the induction of malignant transformation in vitro. Treatment with 10(-6)M 17 beta-estradiol for 6 weeks, or 10(-5)M 17 beta-estradiol for only 5 days, induced malignant transformation in C3H 10T1/2 cells. Estradiol also acted as a cocarcinogen for X-ray induced transformation; the results indicate an additive effect when the cells were exposed to both agents together. The protease inhibitors antipain and leupeptin suppressed estradiol induced transformation as well as the additive effect observed for estradiol-radiation transformation.

  13. Ubiquitination-Linked Phosphorylation of the FANCI S/TQ Cluster Contributes to Activation of the Fanconi Anemia I/D2 Complex

    Directory of Open Access Journals (Sweden)

    Ronald S. Cheung

    2017-06-01

    Full Text Available Repair of interstrand crosslinks by the Fanconi anemia (FA pathway requires both monoubiquitination and de-ubiquitination of the FANCI/FANCD2 (FANCI/D2 complex. In the standing model, the phosphorylation of six sites in the FANCI S/TQ cluster domain occurs upstream of, and promotes, FANCI/D2 monoubiquitination. We generated phospho-specific antibodies against three different S/TQ cluster sites (serines 556, 559, and 565 on human FANCI and found that, in contrast to the standing model, distinct FANCI sites were phosphorylated either predominantly upstream (ubiquitination independent; serine 556 or downstream (ubiquitination-linked; serines 559 and 565 of FANCI/D2 monoubiquitination. Ubiquitination-linked FANCI phosphorylation inhibited FANCD2 de-ubiquitination and bypassed the need to de-ubiquitinate FANCD2 to achieve effective interstrand crosslink repair. USP1 depletion suppressed ubiquitination-linked FANCI phosphorylation despite increasing FANCI/D2 monoubiquitination, providing an explanation of why FANCD2 de-ubiquitination is important for function of the FA pathway. Our work results in a refined model of how FANCI phosphorylation activates the FANCI/D2 complex.

  14. The lysine deacetylase inhibitor givinostat inhibits ß-cell IL-1ß induced IL-1ß transcription and processing

    DEFF Research Database (Denmark)

    Dahllöf, Mattias Salling; Christensen, Dan P; Lundh, Morten

    2012-01-01

    . Further, IL-1R antagonism improves normoglycemia and ß-cell function in type 2 diabetic patients. Inhibition of lysine deacetylases (KDACi) counteracts ß-cell toxicity induced by the combination of IL-1 and IFN¿ and reduces diabetes incidence in non-obese diabetic (NOD) mice. We hypothesized that KDACi......Aims: Pro-inflammatory cytokines and chemokines, in particular IL-1ß, IFN¿, and CXCL10, contribute to ß-cell failure and loss in DM via IL-1R, IFN¿R, and TLR4 signaling. IL-1 signaling deficiency reduces diabetes incidence, islet IL-1ß secretion, and hyperglycemia in animal models of diabetes...

  15. Heat shock induced change in protein ubiquitination in Chlamydomonas

    International Nuclear Information System (INIS)

    Shimogawara, K.; Muto, S.

    1989-01-01

    Ubiquitin was purified from pea (Pisum sativum L.) and its antibody was produced. Western blot analysis showed that the antibody cross-reacted with ubiquitins from a green alga Chlamydomonas reinhardtii, a brown alga Laminaria angustata and a red alga Porphyridium cruentum but not with ubiquitin from a blue-green alga Synechococcus sp. In Chlamydomonas, the antibody also reacted with some ubiquitinated proteins including 28- and 31-kDa polypeptides. The isoelectric points of Chlamydomonas ubiquitin and the 28- and 31-kDa ubiquitinated proteins were 8.0, 8.9 and 10.3, respectively. The ubiquitinated proteins, including the 28- and 31-kDa polypeptides were detected after in vitro ATP-dependent ubiquitination of Chlamydomonas cell extract with l25 I-labeled bovine ubiquitin. Heat treatment of Chlamydomonas cells (>40°C) caused drastic increase of ubiquitinated proteins with high mol wt (>60kDa), and coordinated redistribution or decrease of other ubiquitinated proteins and free ubiquitin. Quantitative analysis revealed that the 28- and 31-kDa ubiquitinated proteins showed different responses against heat stress, i.e. the former being more sensitive than the latter. (author)

  16. Enzyme inhibition by iminosugars

    DEFF Research Database (Denmark)

    López, Óscar; Qing, Feng-Ling; Pedersen, Christian Marcus

    2013-01-01

    Imino- and azasugar glycosidase inhibitors display pH dependant inhibition reflecting that both the inhibitor and the enzyme active site have groups that change protonation state with pH. With the enzyme having two acidic groups and the inhibitor one basic group, enzyme-inhibitor complexes...

  17. The receptor tyrosine kinase inhibitor amuvatinib (MP470) sensitizes tumor cells to radio- and chemo-therapies in part by inhibiting homologous recombination

    International Nuclear Information System (INIS)

    Zhao, Helen; Luoto, Kaisa R.; Meng, Alice X.; Bristow, Robert G.

    2011-01-01

    Background and purpose: RAD51 is a key protein involved in homologous recombination (HR) and a potential target for radiation- and chemotherapies. Amuvatinib (formerly known as MP470) is a novel receptor tyrosine kinase inhibitor that targets c-KIT and PDGFRα and can sensitize tumor cells to ionizing radiation (IR). Here, we studied amuvatinib mechanism on RAD51 and functional HR. Materials and methods: Protein and RNA analyses, direct repeat green fluorescent protein (DR-GFP) assay and polysomal fractioning were used to measure HR efficiency and global translation in amuvatinib-treated H1299 lung carcinoma cells. Synergy of amuvatinib with IR or mitomycin c (MMC) was assessed by clonogenic survival assay. Results: Amuvaninib inhibited RAD51 protein expression and HR. This was associated with reduced ribosomal protein S6 phosphorylation and inhibition of global translation. Amuvatinib sensitized cells to IR and MMC, agents that are selectively toxic to HR-deficient cells. Conclusions: Amuvatinib is a promising agent that may be used to decrease tumor cell resistance. Our work suggests that this is associated with decreased RAD51 expression and function and supports the further study of amuvatinib in combination with chemotherapy and radiotherapy.

  18. 1-L-MT, an IDO inhibitor, prevented colitis-associated cancer by inducing CDC20 inhibition-mediated mitotic death of colon cancer cells.

    Science.gov (United States)

    Liu, Xiuting; Zhou, Wei; Zhang, Xin; Ding, Yang; Du, Qianming; Hu, Rong

    2018-04-01

    Indoleamine 2,3-dioxygenase 1 (IDO1), known as IDO, catabolizes tryptophan through kynurenine pathway, whose activity is correlated with impaired clinical outcome of colorectal cancer. Here we showed that 1-L-MT, a canonical IDO inhibitor, suppressed proliferation of human colorectal cancer cells through inducing mitotic death. Our results showed that inhibition of IDO decreased the transcription of CDC20, which resulted in G2/M cycle arrest of HCT-116 and HT-29. Furthermore, 1-L-MT induced mitochondria injuries and caused apoptotic cancer cells. Importantly, 1-L-MT protected mice from azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced colon carcinogenesis, with reduced mortality, tumor number and size. What is more, IDO1-/- mice exhibited fewer tumor burdens and reduced proliferation in the neoplastic epithelium, while, 1-L-MT did not exhibit any further protective effects on IDO-/- mice, confirming the critical role of IDO and the protective effect of 1-L-MT-mediated IDO inhibition in CRC. Furthermore, 1-L-MT also alleviated CRC in Rag1-/- mice, demonstrating the modulatory effects of IDO independent of its role in modulating adaptive immunity. Taken together, our findings validated that the anti-proliferation effect of 1-L-MT in vitro and the prevention of CRC in vivo were through IDO-induced cell cycle disaster of colon cancer cells. Our results identified 1-L-MT as a promising candidate for the chemoprevention of CRC. © 2018 UICC.

  19. [HSP90 Inhibitor 17-AAG Inhibits Multiple Myeloma Cell Proliferation by Down-regulating Wnt/β-Catenin Signaling Pathway].

    Science.gov (United States)

    Chen, Kan-Kan; He, Zheng-Mei; Ding, Bang-He; Chen, Yue; Zhang, Li-Juan; Yu, Liang; Gao, Jian

    2016-02-01

    To investigate the inhibitory effect of HSP90 inhibitory 17-AAG on proliferation of multiple myeloma cells and its main mechanism. The multiple myeloma cells U266 were treated with 17-AAG of different concentrations (200, 400, 600 and 800 nmol/L) for 24, 48, and 72 hours respectively, then the proliferation rate, expression levels of β-catenin and C-MYC protein, as well as cell cycle of U266 cells were treated with 17-AAG and were detected by MTT method, Western blot and flow cytometry, respectively. The 17-AAG showed inhibitory effect on the proliferation of U266 cells in dose- and time-depetent manners (r = -0.518, P AAG displayed no inhibitory effect on proliferation of U266 cells (P > 0.05). The result of culturing U266 cells for 72 hours by 17-AAG of different concentrations showed that the more high of 17-AAG concentration, the more low level of β-catenin and C-MYC proteins (P AAG concentration, the more high of cell ratio in G1 phase (P AAG, the more long time of culture, the more high of cell ratio in G1 phase (P AAG can inhibit the proliferation of multiple myeloma cells, the down-regulation of Wnt/β-catenin signaling pathway and inhibition of HSP90 expression may be the main mechnisms of 17-AAG effect.

  20. Ubiquitin Accumulation on Disease Associated Protein Aggregates Is Correlated with Nuclear Ubiquitin Depletion, Histone De-Ubiquitination and Impaired DNA Damage Response.

    Directory of Open Access Journals (Sweden)

    Adi Ben Yehuda

    Full Text Available Deposition of ubiquitin conjugates on inclusion bodies composed of protein aggregates is a definitive cytopathological hallmark of neurodegenerative diseases. We show that accumulation of ubiquitin on polyQ IB, associated with Huntington's disease, is correlated with extensive depletion of nuclear ubiquitin and histone de-ubiquitination. Histone ubiquitination plays major roles in chromatin regulation and DNA repair. Accordingly, we observe that cells expressing IB fail to respond to radiomimetic DNA damage, to induce gamma-H2AX phosphorylation and to recruit 53BP1 to damaged foci. Interestingly ubiquitin depletion, histone de-ubiquitination and impaired DNA damage response are not restricted to PolyQ aggregates and are associated with artificial aggregating luciferase mutants. The longevity of brain neurons depends on their capacity to respond to and repair extensive ongoing DNA damage. Impaired DNA damage response, even modest one, could thus lead to premature neuron aging and mortality.

  1. Inhibition of cell proliferation by a selective inhibitor of the Ca{sup 2+}-activated Cl{sup -} channel, Ano1

    Energy Technology Data Exchange (ETDEWEB)

    Mazzone, Amelia; Eisenman, Seth T.; Strege, Peter R. [Enteric NeuroScience Program, Mayo Clinic, Rochester, MN (United States); Yao, Zhen [Laboratory of Molecular Genetics, UCSF, San Francisco, CA (United States); Ordog, Tamas; Gibbons, Simon J. [Enteric NeuroScience Program, Mayo Clinic, Rochester, MN (United States); Farrugia, Gianrico, E-mail: farrugia.gianrico@mayo.edu [Enteric NeuroScience Program, Mayo Clinic, Rochester, MN (United States)

    2012-10-19

    Highlights: Black-Right-Pointing-Pointer T16A{sub inh}-A01 blocked Ano1 currents in HEK cells expressing Ano1. Black-Right-Pointing-Pointer T16A{sub inh}-A01 reduced proliferation in ICC primary cultures and CFPAC-1 cell line. Black-Right-Pointing-Pointer T16A{sub inh}-A01 reduced proliferation of ICC in intact smooth muscle strips. -- Abstract: Background: Ion channels play important roles in regulation of cellular proliferation. Ano1 (TMEM16A) is a Ca{sup 2+}-activated Cl{sup -} channel expressed in several tumors and cell types. In the muscle layers of the gastrointestinal tract Ano1 is selectively expressed in interstitial cells of Cajal (ICC) and appears to be required for normal gastrointestinal slow wave electrical activity. However, Ano1 is expressed in all classes of ICC, including those that do not generate slow waves suggesting that Ano1 may have other functions. Indeed, a role for Ano1 in regulating proliferation of tumors and ICC has been recently suggested. Recently, a high-throughput screen identified a small molecule, T16A{sub inh}-A01 as a specific inhibitor of Ano1. Aim: To investigate the effect of the T16A{sub inh}-A01 inhibitor on proliferation in ICC and in the Ano1-expressing human pancreatic cancer cell line CFPAC-1. Methods: Inhibition of Ano1 was demonstrated by whole cell voltage clamp recordings of currents in cells transfected with full-length human Ano1. The effect of T16A{sub inh}-A01 on ICC proliferation was examined in situ in organotypic cultures of intact mouse small intestinal smooth muscle strips and in primary cell cultures prepared from these tissues. ICC were identified by Kit immunoreactivity. Proliferating ICC and CFPAC-1 cells were identified by immunoreactivity for the nuclear antigen Ki67 or EdU incorporation, respectively. Results: T16A{sub inh}-A01 inhibited Ca{sup 2+}-activated Cl{sup -} currents by 60% at 10 {mu}M in a voltage-independent fashion. Proliferation of ICC was significantly reduced in primary cultures

  2. Sphingosine kinase inhibitor suppresses IL-18-induced interferon-gamma production through inhibition of p38 MAPK activation in human NK cells

    International Nuclear Information System (INIS)

    Cheon, Soyoung; Song, Seok Bean; Jung, Minkyung; Park, Yoorim; Bang, Jung-Wook; Kim, Tae Sung; Park, Hyunjeong; Kim, Cherl-hyun; Yang, Yool-hee; Bang, Sa Ik; Cho, Daeho

    2008-01-01

    Natural killer (NK) cells play an important role in the innate immune response. Interleukin-18 (IL-18) is a well-known interferon-gamma (IFN-γ inducing factor, which stimulates immune response in NK and T cells. Sphingosine kinase (SPHK) catalyzes the formation of sphingosine 1-phosphate (S1P), which acts as a second messenger to function as an anti-apoptotic factor and proliferation stimulator of immune cells. In this study, to elucidate whether SPHK is involved in IL-18-induced IFN-γ production, we measured IL-18-induced IFN-γ production after pre-treatment with SPHK inhibitor (SKI) in NK-92MI cells. We found that IL-18-induced IFN-γ expression was blocked by SKI pre-treatment in both mRNA and protein levels. In addition, the increased IFN-γ production by stimulation with IL-18 is mediated through both SPHK and p38 MAPK. To determine the upstream signals of SKI and p38 MAPK in IL-18-induced IFN-γ production, phosphorylation levels of p38 MAPK was measured after SKI pre-treatment. As a result, inhibition of SPHK by SKI blocked phosphorylation of p38 MAPK, showing that SPHK activation by IL-18 is an upstream signal of p38 MAPK activation. Inhibition of SPHK by SKI also inhibited IL-18-induced IFN-γ production in human primary NK cells. In conclusion, SPHK activation is an essential factor for IL-18-induced IFN-γ production via p38 MAPK

  3. Adenosine 3',5'-cyclic monophosphate (cAMP)-dependent phosphoregulation of mitochondrial complex I is inhibited by nucleoside reverse transcriptase inhibitors

    International Nuclear Information System (INIS)

    Lund, Kaleb C.; Wallace, Kendall B.

    2008-01-01

    Nucleoside analog reverse transcriptase inhibitors (NRTIs) are known to directly inhibit mitochondrial complex I activity as well as various mitochondrial kinases. Recent observations that complex I activity and superoxide production are modulated through cAMP-dependent phosphorylation suggests a mechanism through which NRTIs may affect mitochondrial respiration via kinase-dependent protein phosphorylation. In the current study, we examine the potential for NRTIs to inhibit the cAMP-dependent phosphorylation of complex I and the associated NADH:CoQ oxidoreductase activities and rates of superoxide production using HepG2 cells. Phosphoprotein staining of immunocaptured complex I revealed that 3'-azido-3'-deoxythymidine (AZT; 10 and 50 μM), AZT monophosphate (150 μM), and 2',3'-dideoxycytidine (ddC; 1 μM) prevented the phosphorylation of the NDUFB11 subunit of complex I. This was associated with a decrease in complex I activity with AZT and AZT monophosphate only. In the presence of succinate, superoxide production was increased with 2',3'-dideoxyinosine (ddI; 10 μM) and ddC (1 μM). In the presence of succinate + cAMP, AZT showed an inverse dose-dependent effect on superoxide production. None of the NRTIs examined inhibit PKA activity suggesting that the observed effects are due to a direct interaction with complex I. These data demonstrate a direct effect of NRTIs on cAMP-dependent regulation of mitochondrial bioenergetics independent of DNA polymerase-γ activity; in the case of AZT, these observations may provide a mechanism for the observed long-term toxicity with this drug

  4. KB-R7943, an inhibitor of the reverse Na+/Ca2+ exchanger, blocks N-methyl-D-aspartate receptor and inhibits mitochondrial complex I

    Science.gov (United States)

    Brustovetsky, Tatiana; Brittain, Matthew K; Sheets, Patrick L; Cummins, Theodore R; Pinelis, Vsevolod; Brustovetsky, Nickolay

    2011-01-01

    BACKGROUND AND PURPOSE An isothiourea derivative (2-[2-[4-(4-nitrobenzyloxy)phenyl]ethyl]isothiourea methane sulfonate (KB-R7943), a widely used inhibitor of the reverse Na+/Ca2+ exchanger (NCXrev), was instrumental in establishing the role of NCXrev in glutamate-induced Ca2+ deregulation in neurons. Here, the effects of KB-R7943 on N-methyl-D-aspartate (NMDA) receptors and mitochondrial complex I were tested. EXPERIMENTAL APPROACH Fluorescence microscopy, electrophysiological patch-clamp techniques and cellular respirometry with Seahorse XF24 analyzer were used with cultured hippocampal neurons; membrane potential imaging, respirometry and Ca2+ flux measurements were made in isolated rat brain mitochondria. KEY RESULTS KB-R7943 inhibited NCXrev with IC50= 5.7 ± 2.1 µM, blocked NMDAR-mediated ion currents, and inhibited NMDA-induced increase in cytosolic Ca2+ with IC50= 13.4 ± 3.6 µM but accelerated calcium deregulation and mitochondrial depolarization in glutamate-treated neurons. KB-R7943 depolarized mitochondria in a Ca2+-independent manner. Stimulation of NMDA receptors caused NAD(P)H oxidation that was coupled or uncoupled from ATP synthesis depending on the presence of Ca2+ in the bath solution. KB-R7943, or rotenone, increased NAD(P)H autofluorescence under resting conditions and suppressed NAD(P)H oxidation following glutamate application. KB-R7943 inhibited 2,4-dinitrophenol-stimulated respiration of cultured neurons with IC50= 11.4 ± 2.4 µM. With isolated brain mitochondria, KB-R7943 inhibited respiration, depolarized organelles and suppressed Ca2+ uptake when mitochondria oxidized complex I substrates but was ineffective when mitochondria were supplied with succinate, a complex II substrate. CONCLUSIONS AND IMPLICATIONS KB-R7943, in addition to NCXrev, blocked NMDA receptors in cultured hippocampal neurons and inhibited complex I in the mitochondrial respiratory chain. These findings are critical for the correct interpretation of experimental

  5. Nuclear import inhibitor N-(4-hydroxyphenyl) retinamide targets Zika virus (ZIKV) nonstructural protein 5 to inhibit ZIKV infection.

    Science.gov (United States)

    Wang, Chunxiao; Yang, Sundy N Y; Smith, Kate; Forwood, Jade K; Jans, David A

    2017-12-02

    In the absence of approved therapeutics, Zika virus (ZIKV)'s recent prolific outbreaks in the Americas, together with impacts on unborn fetuses of infected mothers, make it a pressing human health concern worldwide. Although a key player in viral replication in the infected host cell cytoplasm, ZIKV non-structural protein 5 (NS5) appears to contribute integrally to pathogenesis by localising in the host cell nucleus, in similar fashion to NS5 from Dengue virus (DENV). We show here for the first time that ZIKV NS5 is recognized with high nanomolar affinity by the host cell importin α/β1 heterodimer, and that this interaction can be blocked by the novel DENV NS5 targeting inhibitor N-(4-hydroxyphenyl) retinamide (4-HPR). Importantly, we show that 4-HPR has potent anti-ZIKV activity at low μM concentrations. With an established safety profile for human use, 4-HPR represents an exciting possibility as an anti-ZIKV agent. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Aurora kinase inhibitors attached to iron oxide nanoparticles enhances inhibition of the growth of liver cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiquan [Southeast University, State Key Laboratory of Bioelectronics and Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science & Medical Engineering (China); Xie, Li [Southeast University, Zhongda Hospital, School of Medicine (China); Zheng, Ming; Yao, Juan [Jiangsu Chai Tai Tianqing Pharmaceutical Co. Ltd. (China); Song, Lina [Southeast University, State Key Laboratory of Bioelectronics and Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science & Medical Engineering (China); Chang, Weiwei [Jiangsu Chai Tai Tianqing Pharmaceutical Co. Ltd. (China); Zhang, Yu; Ji, Min, E-mail: minji888@hotmail.com; Gu, Ning, E-mail: guning@seu.edu.cn [Southeast University, State Key Laboratory of Bioelectronics and Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science & Medical Engineering (China); Zhan, Xi, E-mail: zhan01@gmail.com [University of Maryland School of Medicine, The Center of Vascular and Inflammatory Diseases, The Department of Pathology (United States)

    2015-06-15

    We have developed a novel Aurora kinase inhibitor (AKI) AM-005, an analogue of pan-AKI AT-9283. To improve the intracellular efficacy of AM-005 and AT-9283, we utilized magnetite nanoparticles (NPs) to deliver AM-005 and AT-9283 into human SMMC-7721 and HepG2 liver cancer cells. The drug-loaded NPs were prepared through quasi-emulsion solvent diffusion of magnetite NPs with AM-005 or AT-9283. The encapsulated drugs were readily released from NPs, preferentially at low pHs. Upon exposure, cancer cells effectively internalized drug-loaded NPs into lysosome-like vesicles, which triggered a series of cellular changes, including the formation of enlarged cytoplasm, the significant increase of membrane permeability, and the generation of reactive oxygen species (ROS). The increased ROS synthesis sustained over 72 h, whereas that in the cells treated with free-form drugs declined rapidly after 48 h. However, chemical sequestration of the iron core of NPs had a minor influence on the generation of intracellular ROS. On the other hand, uncoupling of AM-005 uptake with NP internalization into cells failed to induce ROS synthesis. Overall, our approach achieved two-fold increase in suppressing the viability of tumor cells in vitro and the growth of tumors in vivo. We conclude that magnetite NPs can be used as pH responsive nanocarriers that are able to improve the efficacy of AKIs.

  7. The Plasmodium PI(4)K inhibitor KDU691 selectively inhibits dihydroartemisinin-pretreated Plasmodium falciparum ring-stage parasites.

    Science.gov (United States)

    Dembele, L; Ang, X; Chavchich, M; Bonamy, G M C; Selva, J J; Lim, M Yi-Xiu; Bodenreider, C; Yeung, B K S; Nosten, F; Russell, B M; Edstein, M D; Straimer, J; Fidock, D A; Diagana, T T; Bifani, P

    2017-05-24

    Malaria control and elimination are threatened by the emergence and spread of resistance to artemisinin-based combination therapies (ACTs). Experimental evidence suggests that when an artemisinin (ART)-sensitive (K13 wild-type) Plasmodium falciparum strain is exposed to ART derivatives such as dihydroartemisinin (DHA), a small population of the early ring-stage parasites can survive drug treatment by entering cell cycle arrest or dormancy. After drug removal, these parasites can resume growth. Dormancy has been hypothesized to be an adaptive physiological mechanism that has been linked to recrudescence of parasites after monotherapy with ART and, possibly contributes to ART resistance. Here, we evaluate the in vitro drug sensitivity profile of normally-developing P. falciparum ring stages and DHA-pretreated dormant rings (DP-rings) using a panel of antimalarial drugs, including the Plasmodium phosphatidylinositol-4-OH kinase (PI4K)-specific inhibitor KDU691. We report that while KDU691 shows no activity against rings, it is highly inhibitory against DP-rings; a drug effect opposite to that of ART. Moreover, we provide evidence that KDU691 also kills DP-rings of P. falciparum ART-resistant strains expressing mutant K13.

  8. Ubiquitin Signaling: Extreme Conservation as a Source of Diversity

    Directory of Open Access Journals (Sweden)

    Alice Zuin

    2014-07-01

    Full Text Available Around 2 × 103–2.5 × 103 million years ago, a unicellular organism with radically novel features, ancestor of all eukaryotes, dwelt the earth. This organism, commonly referred as the last eukaryotic common ancestor, contained in its proteome the same functionally capable ubiquitin molecule that all eukaryotic species contain today. The fact that ubiquitin protein has virtually not changed during all eukaryotic evolution contrasts with the high expansion of the ubiquitin system, constituted by hundreds of enzymes, ubiquitin-interacting proteins, protein complexes, and cofactors. Interestingly, the simplest genetic arrangement encoding a fully-equipped ubiquitin signaling system is constituted by five genes organized in an operon-like cluster, and is found in archaea. How did ubiquitin achieve the status of central element in eukaryotic physiology? We analyze here the features of the ubiquitin molecule and the network that it conforms, and propose notions to explain the complexity of the ubiquitin signaling system in eukaryotic cells.

  9. Inhibition of PAF-induced expression of CD11b and shedding of L-selectin on human neutrophils and eosinophils by the type IV selective PDE inhibitor, rolipram

    NARCIS (Netherlands)

    Dijkhuizen, B; deMonchy, JGR; Dubois, AEJ; Gerritsen, J; Kauffman, HF

    We quantitatively determined whether the selective phosphodiesterase (PDE) inhibitor, rolipram, inhibits changes in the adhesion molecules CD11b and L-selectin on platelet-activating factor (PAF)-stimulated human neutrophils and eosinophils in vitro. Incubations were performed in human whole blood

  10. Principles of ubiquitin and SUMO modifications in DNA repair

    NARCIS (Netherlands)

    Bergink, Steven; Jentsch, Stefan

    2009-01-01

    With the discovery in the late 1980s that the DNA-repair gene RAD6 encodes a ubiquitin-conjugating enzyme, it became clear that protein modification by ubiquitin conjugation has a much broader significance than had previously been assumed. Now, two decades later, ubiquitin and its cousin SUMO are

  11. Inhibition of dengue virus replication by novel inhibitors of RNA-dependent RNA polymerase and protease activities.

    Science.gov (United States)

    Pelliccia, Sveva; Wu, Yu-Hsuan; Coluccia, Antonio; La Regina, Giuseppe; Tseng, Chin-Kai; Famiglini, Valeria; Masci, Domiziana; Hiscott, John; Lee, Jin-Ching; Silvestri, Romano

    2017-12-01

    Dengue virus (DENV) is the leading mosquito-transmitted viral infection in the world. With more than 390 million new infections annually, and up to 1 million clinical cases with severe disease manifestations, there continues to be a need to develop new antiviral agents against dengue infection. In addition, there is no approved anti-DENV agents for treating DENV-infected patients. In the present study, we identified new compounds with anti-DENV replication activity by targeting viral replication enzymes - NS5, RNA-dependent RNA polymerase (RdRp) and NS3 protease, using cell-based reporter assay. Subsequently, we performed an enzyme-based assay to clarify the action of these compounds against DENV RdRp or NS3 protease activity. Moreover, these compounds exhibited anti-DENV activity in vivo in the ICR-suckling DENV-infected mouse model. Combination drug treatment exhibited a synergistic inhibition of DENV replication. These results describe novel prototypical small anti-DENV molecules for further development through compound modification and provide potential antivirals for treating DENV infection and DENV-related diseases.

  12. Pertussis toxin, an inhibitor of G(αi PCR, inhibits bile acid- and cytokine-induced apoptosis in primary rat hepatocytes.

    Directory of Open Access Journals (Sweden)

    Golnar Karimian

    Full Text Available Excessive hepatocyte apoptosis is a common event in acute and chronic liver diseases leading to loss of functional liver tissue. Approaches to prevent apoptosis have therefore high potential for the treatment of liver disease. G-protein coupled receptors (GPCR play crucial roles in cell fate (proliferation, cell death and act through heterotrimeric G-proteins. G(αiPCRs have been shown to regulate lipoapoptosis in hepatocytes, but their role in inflammation- or bile acid-induced apoptosis is unknown. Here, we analyzed the effect of inhibiting G(αiPCR function, using pertussis toxin (PT, on bile acid- and cytokine-induced apoptosis in hepatocytes. Primary rat hepatocytes, HepG2-rNtcp cells (human hepatocellular carcinoma cells or H-4-II-E cells (rat hepatoma cells were exposed to glycochenodeoxycholic acid (GCDCA or tumor necrosis factor-α (TNFα/actinomycin D (ActD. PT (50-200 nmol/L was added 30 minutes prior to the apoptotic stimulus. Apoptosis (caspase-3 activity, acridine orange staining and necrosis (sytox green staining were assessed. PT significantly reduced GCDCA- and TNFα/ActD-induced apoptosis in rat hepatocytes (-60%, p<0.05 in a dose-dependent manner (with no shift to necrosis, but not in HepG2-rNtcp cells or rat H-4-II-E cells. The protective effect of pertussis toxin was independent of the activation of selected cell survival signal transduction pathways, including ERK, p38 MAPK, PI3K and PKC pathways, as specific protein kinase inhibitors did not reverse the protective effects of pertussis toxin in GCDCA-exposed hepatocytes.Pertussis toxin, an inhibitor of G(αiPCRs, protects hepatocytes, but not hepatocellular carcinoma cells, against bile acid- and cytokine-induced apoptosis and has therapeutic potential as primary hepatoprotective drug, as well as adjuvant in anti-cancer therapy.

  13. HET0016, a selective inhibitor of 20-HETE synthesis, decreases pro-angiogenic factors and inhibits growth of triple negative breast cancer in mice.

    Directory of Open Access Journals (Sweden)

    Thaiz Ferraz Borin

    Full Text Available A selective inhibitor of 20-HETE synthesis, HET0016, has been reported to inhibit angiogenesis. 20-HETE has been known as a second mitogenic messenger of angiogenesis inducing growth factors. HET0016 effects were analyzed on MDA-MB-231 derived breast cancer in mouse and in vitro cell line. MDA-MB-231 tumor cells were implanted in animals' right flank and randomly assigned to early (1 and 2, starting treatments on day 0, or delayed groups (3 and 4 on day 8 after implantation of tumor. Animals received HET0016 (10 mg/kg treatment via intraperitoneal injection for 5 days/week for either 3 or 4 weeks. Control group received vehicle treatment. Tumor sizes were measured on days 7, 14, 21, and 28 and the animals were euthanized on day 22 and 29. Proteins were extracted from the whole tumor and from cells treated with 10 µM HET0016 for 4 and 24 hrs. Protein array kits of 20 different cytokines/factors were used. ELISA was performed to observe the HIF-1α and MMP-2 protein expression. Other markers were confirmed by IHC. HET0016 significantly inhibited tumor growth in all treatment groups at all-time points compared to control (p<0.05. Tumor growth was completely inhibited on three of ten animals on early treatment group. Treatment groups showed significantly lower expression of pro-angiogenic factors compared to control at 21 days; however, there was no significant difference in HIF-1α expression after treatments. Similar results were found in vitro at 24 hrs of HET0016 treatment. After 28 days, significant increase of angiogenin, angiopoietin-1/2, EGF-R and IGF-1 pro-angiogenic factors were found (p<0.05 compared to control, as well as an higher intensity of all factors were found when compared to that of 21 day's data, suggesting a treatment resistance. HET0016 inhibited tumor growth by reducing expression of different set of pro-angiogenic factors; however, a resistance to treatment seemed to happen after 21 days.

  14. Role of 5'TG3'-interacting factors (TGIFs) in Vorinostat (HDAC inhibitor)-mediated Corneal Fibrosis Inhibition.

    Science.gov (United States)

    Sharma, Ajay; Sinha, Nishant R; Siddiqui, Saad; Mohan, Rajiv R

    2015-01-01

    We have previously reported that vorinostat, an FDA-approved, clinically used histone deacetylase (HDAC) inhibitor, attenuates corneal fibrosis in vivo in rabbits by blocking transforming growth factor β (TGFβ). The 5'TG3'-interacting factors (TGIFs) are transcriptional repressors of TGFβ1 signaling via the Smad pathway. The present study was designed to explore the expression of TGIFs in human corneal fibroblasts and to investigate their role in mediating the antifibrotic effect of vorinostat. Human corneal fibroblast cultures were generated from donor corneas. RNA isolation, cDNA preparation, and PCR were performed to detect the presence of TGIF1 and TGIF2 transcripts. The cultures were exposed to vorinostat (2.5 µM) to test its effect on TGIF mRNA and protein levels using qPCR and immunoblotting. Myofibroblast formation was induced with TGFβ1 (5 ng/ml) treatment under serum-free conditions. The changes in fibrosis parameters were quantified by measuring fibrosis marker α-smooth muscle actin (αSMA) mRNA and protein levels with qPCR, immunostaining, and immunoblotting. Smad2/3/4 and TGIF knockdowns were performed using pre-validated RNAi/siRNAs and a commercially available transfection reagent. Human corneal fibroblasts showed the expression of TGIF1 and TGIF2. Vorinostat (2.5 µM) caused a 2.8-3.3-fold increase in TGIF1 and TGIF2 mRNA levels and a 1.4-1.8-fold increase in TGIF1 and TGIF2 protein levels. Vorinostat treatment also caused a significant increase in acetylhistone H3 and acetylhistone H4. Vorinostat-induced increases in TGIF1 and TGIF2 were accompanied by a concurrent decrease in corneal fibrosis, as indicated by a decrease in αSMA mRNA by 83±7.7% and protein levels by 97±5%. The RNAi-mediated knockdown of Smad2, Smad3, and Smad4 markedly attenuated TGFβ1-evoked transdifferentiation of fibroblasts to myofibroblasts. The siRNA-mediated knockdown of TGIF1 and TGIF2 neutralized vorinostat-evoked decreases in αSMA mRNA by 31%-45% and protein

  15. Myostatin Activates the Ubiquitin-Proteasome and Autophagy-Lysosome Systems Contributing to Muscle Wasting in Chronic Kidney Disease

    Science.gov (United States)

    Wang, Dong-Tao; Yang, Ya-Jun; Huang, Ren-Hua; Zhang, Zhi-Hua; Lin, Xin

    2015-01-01

    Our evidence demonstrated that CKD upregulated the expression of myostatin, TNF-α, and p-IkBa and downregulated the phosphorylation of PI3K, Akt, and FoxO3a, which were also associated with protein degradation and muscle atrophy. The autophagosome formation and protein expression of autophagy-related genes were increased in muscle of CKD rats. The mRNA level and protein expression of MAFbx and MuRF-1 were also upregulated in CKD rats, as well as proteasome activity of 26S. Moreover, activation of myostatin elicited by TNF-α induces C2C12 myotube atrophy via upregulating the expression of autophagy-related genes, including MAFbx and MuRF1 and proteasome subunits. Inactivation of FoxO3a triggered by PI3K inhibitor LY294002 prevented the myostatin-induced increase of expression of MuRF1, MAFbx, and LC3-II protein in C2C12 myotubes. The findings were further consolidated by using siRNA interference and overexpression of myostatin. Additionally, expression of myostatin was activated by TNF-α via a NF-κB dependent pathway in C2C12 myotubes, while inhibition of NF-κB activity suppressed myostatin and improved myotube atrophy. Collectively, myostatin mediated CKD-induced muscle catabolism via coordinate activation of the autophagy and the ubiquitin-proteasome systems. PMID:26448817

  16. The E3 ubiquitin ligase RNF146 promotes colorectal cancer by activating the Wnt/β-catenin pathway via ubiquitination of Axin1.

    Science.gov (United States)

    Shen, Jiangli; Yu, Zhaohui; Li, Na

    2018-06-20

    The E3 ubiquitin ligase ring finger protein 146 (RNF146) has been implicated in tumor development. However, the role and clinical significance of RNF146 in colorectal cancer (CRC) remain unknown. In this study, we reported for the first time that RNF146 was upregulated in CRC tissues as well as in cell lines. Further, RNF146 expression was independent prognostic factor for poor outcome of CRC patients. RNF146 knockdown in cell lines inhibited cell growth, promoted cell apoptosis in vitro and suppressed colorectal tumor growth in vivo. Mechanistic investigations revealed that RNF146 exerted oncogenic role through ubiquitination of Axin1 to activate β-catenin signalling. In addition, RNF146 expression was positively correlated with β-catenin expression in CRC tissues. Collectively, our data suggest that RNF146 might function as a oncogene in human CRC, and represent a promising prognostic factor and a valuable therapeutic target for CRC. Copyright © 2018. Published by Elsevier Inc.

  17. The ubiquitin ligase SCFFBXW7α promotes GATA3 degradation.

    Science.gov (United States)

    Song, Nan; Cao, Cheng; Tang, Yiman; Bi, Liyuan; Jiang, Yong; Zhou, Yongsheng; Song, Xin; Liu, Ling; Ge, Wenshu

    2018-03-01

    GATA3 is a key transcription factor in cell fate determination and its dysregulation has been implicated in various types of malignancies. However, how the abundance and function of GATA3 are regulated remains unclear. Here, we report that GATA3 is physically associated with FBXW7α, and FBXW7α destabilizes GATA3 through assembly of a SKP1-CUL1-F-box E3 ligase complex. Importantly, we showed that FBXW7α promotes GATA3 ubiquitination and degradation in a GSK3 dependent manner. Furthermore, we demonstrated that FBXW7α inhibits breast cancer cells survival through destabilizing GATA3, and the expression level of FBXW7α is negatively correlated with that of GATA3 in breast cancer samples. This study indicated that FBXW7α is a critical negative regulator of GATA3 and revealed a pathway for the maintenance of GATA3 abundance in breast cancer cells. © 2017 Wiley Periodicals, Inc.

  18. TRIM65 negatively regulates p53 through ubiquitination

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yang [Department of Respiration, The First Hospital of Jilin University, Changchun 130021 (China); Ma, Chengyuan [Department of Neurosurgery, The First Hospital of Jilin University, Changchun 130021 (China); Zhou, Tong [Department of Endocrinology, The First Hospital of Jilin University, Changchun 130021 (China); Liu, Ying [Department of Respiration, The First Hospital of Jilin University, Changchun 130021 (China); Sun, Luyao [Department of Infectious Diseases, The First Hospital of Jilin University, Changchun 130021 (China); Yu, Zhenxiang, E-mail: zhenxiangyu2015@gmail.com [Department of Respiration, The First Hospital of Jilin University, Changchun 130021 (China)

    2016-04-22

    Tripartite-motif protein family member 65 (TRIM65) is an important protein involved in white matter lesion. However, the role of TRIM65 in human cancer remains less understood. Through the Cancer Genome Atlas (TCGA) gene alteration database, we found that TRIM65 is upregulated in a significant portion of non-small cell lung carcinoma (NSCLC) patients. Our cell growth assay revealed that TRIM65 overexpression promotes cell proliferation, while knockdown of TRIM65 displays opposite effect. Mechanistically, TRIM65 binds to p53, one of the most critical tumor suppressors, and serves as an E3 ligase toward p53. Consequently, TRIM65 inactivates p53 through facilitating p53 poly-ubiquitination and proteasome-mediated degradation. Notably, chemotherapeutic reagent cisplatin induction of p53 is markedly attenuated in response to ectopic expression of TRIM65. Cell growth inhibition by TRIM65 knockdown is more significant in p53 positive H460 than p53 negative H1299 cells, and knockdown of p53 in H460 cells also shows compromised cell growth inhibition by TRIM65 knockdown, indicating that p53 is required, at least in part, for TRIM65 function. Our findings demonstrate TRIM65 as a potential oncogenic protein, highly likely through p53 inactivation, and provide insight into development of novel approaches targeting TRIM65 for NSCLC treatment, and also overcoming chemotherapy resistance. - Highlights: • TRIM65 expression is elevated in NSCLC. • TRIM65 inactivates p53 through mediating p53 ubiquitination and degradation. • TRIM65 attenuates the response of NSCLC cells to cisplatin.

  19. Effective intracellular inhibition of the cAMP-dependent protein kinase by microinjection of a modified form of the specific inhibitor peptide PKi in living fibroblasts.

    Science.gov (United States)

    Fernandez, A; Mery, J; Vandromme, M; Basset, M; Cavadore, J C; Lamb, N J

    1991-08-01

    In order to obtain a peptide retaining its biological activity following microinjection into living cells, we have modified a synthetic peptide [PKi(m)(6-24)], derived from the specific inhibitor protein of the cAMP-dependent protein kinase (A-kinase) in two ways: (1) substitution of the arginine at position 18 for a D-arginine; (2) blockade of the side chain on the C-terminal aspartic acid by a cyclohexyl ester group. In an in vitro assay, PKi(m) has retained a specific inhibitory activity against A-kinase as assessed against six other kinases, with similar efficiency to that of the unmodified PKi(5-24) peptide. Microinjection of PKi(m) into living fibroblasts reveals its capacity to prevent the changes in cell morphology and cytoskeleton induced by drugs which activate endogenous A-kinase, whereas the original PKi peptide failed to do so. This inhibition of A-kinase in vivo by PKi(m) lasts between 4 and 6 h after injection. In light of its effective half-life, this modified peptide opens a route for the use of biologically active peptides in vivo, an approach which has been hampered until now by the exceedingly short half-life of peptides inside living cells. By providing a direct means of inhibiting A-kinase activity for sufficiently long periods to observe effects on cellular functions in living cells, PKi(m) represents a powerful tool in studying the potential role of cAMP-dependent phosphorylation in vivo.