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Sample records for antiviral signaling protein

  1. Negative regulation of RIG-I-mediated antiviral signaling by TRK-fused gene (TFG) protein

    International Nuclear Information System (INIS)

    Lee, Na-Rae; Shin, Han-Bo; Kim, Hye-In; Choi, Myung-Soo; Inn, Kyung-Soo

    2013-01-01

    Highlights: •TRK-fused gene product (TFG) interacts with TRIM25 upon viral infection. •TFG negatively regulates RIG-I mediated antiviral signaling. •TFG depletion leads to enhanced viral replication. •TFG act downstream of MAVS. -- Abstract: RIG-I (retinoic acid inducible gene I)-mediated antiviral signaling serves as the first line of defense against viral infection. Upon detection of viral RNA, RIG-I undergoes TRIM25 (tripartite motif protein 25)-mediated K63-linked ubiquitination, leading to type I interferon (IFN) production. In this study, we demonstrate that TRK-fused gene (TFG) protein, previously identified as a TRIM25-interacting protein, binds TRIM25 upon virus infection and negatively regulates RIG-I-mediated type-I IFN signaling. RIG-I-mediated IFN production and nuclear factor (NF)-κB signaling pathways were upregulated by the suppression of TFG expression. Furthermore, vesicular stomatitis virus (VSV) replication was significantly inhibited by small inhibitory hairpin RNA (shRNA)-mediated knockdown of TFG, supporting the suppressive role of TFG in RIG-I-mediated antiviral signaling. Interestingly, suppression of TFG expression increased not only RIG-I-mediated signaling but also MAVS (mitochondrial antiviral signaling protein)-induced signaling, suggesting that TFG plays a pivotal role in negative regulation of RNA-sensing, RIG-I-like receptor (RLR) family signaling pathways

  2. Lab-Attenuated Rabies Virus Causes Abortive Infection and Induces Cytokine Expression in Astrocytes by Activating Mitochondrial Antiviral-Signaling Protein Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Bin Tian

    2018-01-01

    Full Text Available Rabies is an ancient disease but remains endemic in most parts of the world and causes approximately 59,000 deaths annually. The mechanism through which the causative agent, rabies virus (RABV, evades the host immune response and infects the host central nervous system (CNS has not been completely elucidated thus far. Our previous studies have shown that lab-attenuated, but not wild-type (wt, RABV activates the innate immune response in the mouse and dog models. In this present study, we demonstrate that lab-attenuated RABV causes abortive infection in astrocytes, the most abundant glial cells in the CNS. Furthermore, we found that lab-attenuated RABV produces more double-stranded RNA (dsRNA than wt RABV, which is recognized by retinoic acid-inducible gene I (RIG-I or melanoma differentiation-associated protein 5 (MDA5. Activation of mitochondrial antiviral-signaling protein (MAVS, the common adaptor molecule for RIG-I and MDA5, results in the production of type I interferon (IFN and the expression of hundreds of IFN-stimulated genes, which suppress RABV replication and spread in astrocytes. Notably, lab-attenuated RABV replicates in a manner identical to that of wt RABV in MAVS−/− astrocytes. It was also found that lab-attenuated, but not wt, RABV induces the expression of inflammatory cytokines via the MAVS- p38/NF-κB signaling pathway. These inflammatory cytokines increase the blood–brain barrier permeability and thus enable immune cells and antibodies infiltrate the CNS parenchyma, resulting in RABV control and elimination. In contrast, wt RABV restricts dsRNA production and thus evades innate recognition by RIG-I/MDA5 in astrocytes, which could be one of the mechanisms by which wt RABV evades the host immune response in resident CNS cells. Our findings suggest that astrocytes play a critical role in limiting the replication of lab-attenuated RABV in the CNS.

  3. An antiviral protein from Bougainvillea spectabilis roots; purification and characterisation.

    Science.gov (United States)

    Balasaraswathi, R; Sadasivam, S; Ward, M; Walker, J M

    1998-04-01

    An antiviral protein active against mechanical transmission of tomato spotted wilt virus was identified in the root tissues of Bougainvillea spectabilis Willd. Bougainvillea Antiviral Protein I (BAP I) was purified to apparent homogeneity from the roots of Bougainvillea by ammonium sulphate precipitation, CM- and DEAE-Sepharose chromatography and reverse phase HPLC. BAP I is a highly basic protein (pI value > 8.6) with an Mr of 28,000. The N-terminal sequence of BAP I showed homology with other plant antiviral proteins. Preliminary tests suggest that purified BAP I is capable of interfering with in vitro protein synthesis.

  4. Antiviral and Inflammatory Cellular Signaling Associated with Enterovirus 71 Infection

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    Yuefei Jin

    2018-03-01

    Full Text Available Enterovirus 71 (EV71 infection has become a major threat to global public health, especially in infants and young children. Epidemiological studies have indicated that EV71 infection is responsible for severe and even fatal cases of hand, foot, and mouth disease (HFMD. Accumulated evidence indicates that EV71 infection triggers a plethora of interactive signaling pathways, resulting in host immune evasion and inflammatory response. This review mainly covers the effects of EV71 infection on major antiviral and inflammatory cellular signal pathways. EV71 can activate cellular signaling networks including multiple cell surface and intracellular receptors, intracellular kinases, calcium flux, and transcription factors that regulate antiviral innate immunity and inflammatory response. Cellular signaling plays a critical role in the regulation of host innate immune and inflammatory pathogenesis. Elucidation of antiviral and inflammatory cellular signaling pathways initiated by EV71 will not only help uncover the potential mechanisms of EV71 infection-induced pathogenesis, but will also provide clues for the design of therapeutic strategies against EV71 infection.

  5. DMPD: Regulation of mitochondrial antiviral signaling pathways. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 18549796 Regulation of mitochondrial antiviral signaling pathways. Moore CB, Ting J...P. Immunity. 2008 Jun;28(6):735-9. (.png) (.svg) (.html) (.csml) Show Regulation of mitochondrial antiviral ...signaling pathways. PubmedID 18549796 Title Regulation of mitochondrial antiviral signaling pathways. Author

  6. DMPD: Negative regulation of cytoplasmic RNA-mediated antiviral signaling. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 18703349 Negative regulation of cytoplasmic RNA-mediated antiviral signaling. Komur...Show Negative regulation of cytoplasmic RNA-mediated antiviral signaling. PubmedID 18703349 Title Negative r...egulation of cytoplasmic RNA-mediated antiviral signaling. Authors Komuro A, Bamm

  7. Testing of disease-resistance of pokeweed antiviral protein gene ...

    African Journals Online (AJOL)

    Transformation of pokeweed antiviral protein gene (PAP) into plants was shown to improve plant resistance to several viruses or fungi pathogens with no much negative effect on plant growth. The non-virulent defective PAP inhibits only the virus but does not interfere with the host. A non-virulent defective PAP gene ...

  8. Identification of DreI as an antiviral factor regulated by RLR signaling pathway.

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    Shun Li

    Full Text Available BACKGROUND: Retinoic acid-inducible gene I (RIG-I-like receptors (RLRs had been demonstrated to prime interferon (IFN response against viral infection via the conserved RLR signaling in fish, and a novel fish-specific gene, the grass carp reovirus (GCRV-induced gene 2 (Gig2, had been suggested to play important role in host antiviral response. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we cloned and characterized zebrafish Gig2 homolog (named Danio rerio Gig2-I, DreI, and revealed its antiviral role and expressional regulation signaling pathway. RT-PCR, Western blot and promoter activity assay indicate that DreI can be induced by poly I:C, spring viremia of carp virus (SVCV and recombinant IFN (rIFN, showing that DreI is a typical ISG. Using the pivotal signaling molecules of RLR pathway, including RIG-I, MDA5 and IRF3 from crucian carp, it is found that DreI expression is regulated by RLR cascade and IRF3 plays an important role in this regulation. Furthermore, promoter mutation assay confirms that the IFN-stimulated regulatory elements (ISRE in the 5' flanking region of DreI is essential for its induction. Finally, overexpression of DreI leads to establish a strong antiviral state against SVCV and Rana grylio virus (RGV infection in EPC (Epithelioma papulosum cyprinid cells. CONCLUSIONS/SIGNIFICANCE: These data indicate that DreI is an antiviral protein, which is regulated by RLR signaling pathway.

  9. Zinc-finger antiviral protein inhibits XMRV infection.

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    Xinlu Wang

    Full Text Available BACKGROUND: The zinc-finger antiviral protein (ZAP is a host factor that specifically inhibits the replication of certain viruses, including Moloney murine leukemia virus (MoMLV, HIV-1, and certain alphaviruses and filoviruses. ZAP binds to specific viral mRNAs and recruits cellular mRNA degradation machinery to degrade the target RNA. The common features of ZAP-responsive RNA sequences remain elusive and thus whether a virus is susceptible to ZAP can only be determined experimentally. Xenotropic murine leukemia virus-related virus (XMRV is a recently identified γ-retrovirus that was originally thought to be involved in prostate cancer and chronic fatigue syndrome but recently proved to be a laboratory artefact. Nonetheless, XMRV as a new retrovirus has been extensively studied. Since XMRV and MoMLV share only 67.9% sequence identity in the 3'UTRs, which is the target sequence of ZAP in MoMLV, whether XMRV is susceptible to ZAP remains to be determined. FINDINGS: We constructed an XMRV-luc vector, in which the coding sequences of Gag-Pol and part of Env were replaced with luciferase-coding sequence. Overexpression of ZAP potently inhibited the expression of XMRV-luc in a ZAP expression-level-dependent manner, while downregulation of endogenous ZAP rendered cells more sensitive to infection. Furthermore, ZAP inhibited the spreading of replication-competent XMRV. Consistent with the previously reported mechanisms by which ZAP inhibits viral infection, ZAP significantly inhibited the accumulation of XMRV-luc mRNA in the cytoplasm. The ZAP-responsive element in XMRV mRNA was mapped to the 3'UTR. CONCLUSIONS: ZAP inhibits XMRV replication by preventing the accumulation of viral mRNA in the cytoplasm. Documentation of ZAP inhibiting XMRV helps to broaden the spectrum of ZAP's antiviral activity. Comparison of the target sequences of ZAP in XMRV and MoMLV helps to better understand the features of ZAP-responsive elements.

  10. Virus-Heat Shock Protein Interaction and a Novel Axis for Innate Antiviral Immunity

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    Michael Oglesbee

    2012-09-01

    Full Text Available Virus infections induce heat shock proteins that in turn enhance virus gene expression, a phenomenon that is particularly well characterized for the major inducible 70 kDa heat shock protein (hsp70. However, hsp70 is also readily induced by fever, a phylogenetically conserved response to microbial infections, and when released from cells, hsp70 can stimulate innate immune responses through toll like receptors 2 and 4 (TLR2 and 4. This review examines how the virus-hsp70 relationship can lead to host protective innate antiviral immunity, and the importance of hsp70 dependent stimulation of virus gene expression in this host response. Beginning with the well-characterized measles virus-hsp70 relationship and the mouse model of neuronal infection in brain, we examine data indicating that the innate immune response is not driven by intracellular sensors of pathogen associated molecular patterns, but rather by extracellular ligands signaling through TLR2 and 4. Specifically, we address the relationship between virus gene expression, extracellular release of hsp70 (as a damage associated molecular pattern, and hsp70-mediated induction of antigen presentation and type 1 interferons in uninfected macrophages as a novel axis of antiviral immunity. New data are discussed that examines the more broad relevance of this protective mechanism using vesicular stomatitis virus, and a review of the literature is presented that supports the probable relevance to both RNA and DNA viruses and for infections both within and outside of the central nervous system.

  11. La protéine CG4572 de Drosophile et la propagation du signal ARNi immun antiviral

    OpenAIRE

    Karlikow , Margot

    2015-01-01

    During viral infection, cell survival will depend on adequately giving, receiving and processing information to establish an efficient antiviral immune response. Cellular communication is therefore essential to allow the propagation of immune signals that will confer protection to the entire organism.The major antiviral defense in insects is the RNA interference (RNAi) mechanism that is activated by detection of viral double-stranded RNA (dsRNA). The antiviral RNAi mechanism can be divided in...

  12. RIG-I antiviral signaling drives interleukin-23 production and psoriasis-like skin disease.

    Science.gov (United States)

    Zhu, Huiyuan; Lou, Fangzhou; Yin, Qianqian; Gao, Yuanyuan; Sun, Yang; Bai, Jing; Xu, Zhenyao; Liu, Zhaoyuan; Cai, Wei; Ke, Fang; Zhang, Lingyun; Zhou, Hong; Wang, Hong; Wang, Gang; Chen, Xiang; Zhang, Hongxin; Wang, Zhugang; Ginhoux, Florent; Lu, Chuanjian; Su, Bing; Wang, Honglin

    2017-05-01

    Retinoic acid inducible-gene I (RIG-I) functions as one of the major sensors of RNA viruses. DDX58 , which encodes the RIG-I protein, has been newly identified as a susceptibility gene in psoriasis. Here, we show that the activation of RIG-I by 5'ppp-dsRNA, its synthetic ligand, directly causes the production of IL-23 and triggers psoriasis-like skin disease in mice. Repeated injections of IL-23 to the ears failed to induce IL-23 production and a full psoriasis-like skin phenotype, in either germ-free or RIG-I-deficient mice. RIG-I is also critical for a full development of skin inflammation in imiquimod (IMQ)-induced psoriasis-like mouse model. Furthermore, RIG-I-mediated endogenous IL-23 production was mainly confined to the CD11c + dendritic cells (DCs) via nuclear factor-kappa B (NF-κB) signaling, and stimulated RIG-I expression in an auto-regulatory feedback loop. Thus, our data suggest that the dysregulation in the antiviral immune responses of hosts through the innate pattern recognition receptors may trigger the skin inflammatory conditions in the pathophysiology of psoriasis. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  13. An antiviral disulfide compound blocks interaction between arenavirus Z protein and cellular promyelocytic leukemia protein

    International Nuclear Information System (INIS)

    Garcia, C.C.; Topisirovic, I.; Djavani, M.; Borden, K.L.B.; Damonte, E.B.; Salvato, M.S.

    2010-01-01

    The promyelocytic leukemia protein (PML) forms nuclear bodies (NB) that can be redistributed by virus infection. In particular, lymphocytic choriomeningitis virus (LCMV) influences disruption of PML NB through the interaction of PML with the arenaviral Z protein. In a previous report, we have shown that the disulfide compound NSC20625 has antiviral and virucidal properties against arenaviruses, inducing unfolding and oligomerization of Z without affecting cellular RING-containing proteins such as the PML. Here, we further studied the effect of the zinc-finger-reactive disulfide NSC20625 on PML-Z interaction. In HepG2 cells infected with LCMV or transiently transfected with Z protein constructs, treatment with NSC20625 restored PML distribution from a diffuse-cytoplasmic pattern to punctate, discrete NB which appeared identical to NB found in control, uninfected cells. Similar results were obtained in cells transfected with a construct expressing a Z mutant in zinc-binding site 2 of the RING domain, confirming that this Z-PML interaction requires the integrity of only one zinc-binding site. Altogether, these results show that the compound NSC20625 suppressed Z-mediated PML NB disruption and may be used as a tool for designing novel antiviral strategies against arenavirus infection.

  14. Multifunctional roles of leader protein of foot-and-mouth disease viruses in suppressing host antiviral responses.

    Science.gov (United States)

    Liu, Yingqi; Zhu, Zixiang; Zhang, Miaotao; Zheng, Haixue

    2015-10-28

    Foot-and-mouth disease virus (FMDV) leader protein (L(pro)) is a papain-like proteinase, which plays an important role in FMDV pathogenesis. L(pro) exists as two forms, Lab and Lb, due to translation being initiated from two different start codons separated by 84 nucleotides. L(pro) self-cleaves from the nascent viral polyprotein precursor as the first mature viral protein. In addition to its role as a viral proteinase, L(pro) also has the ability to antagonize host antiviral effects. To promote FMDV replication, L(pro) can suppress host antiviral responses by three different mechanisms: (1) cleavage of eukaryotic translation initiation factor 4 γ (eIF4G) to shut off host protein synthesis; (2) inhibition of host innate immune responses through restriction of interferon-α/β production; and (3) L(pro) can also act as a deubiquitinase and catalyze deubiquitination of innate immune signaling molecules. In the light of recent functional and biochemical findings regarding L(pro), this review introduces the basic properties of L(pro) and the mechanisms by which it antagonizes host antiviral responses.

  15. Type I interferon production during herpes simplex virus infection is controlled by cell-type-specific viral recognition through Toll-like receptor 9, the mitochondrial antiviral signaling protein pathway, and novel recognition systems

    DEFF Research Database (Denmark)

    Rasmussen, Simon Brandtoft; Sørensen, Louise Nørgaard; Malmgaard, Lene

    2007-01-01

    Recognition of viruses by germ line-encoded pattern recognition receptors of the innate immune system is essential for rapid production of type I interferon (IFN) and early antiviral defense. We investigated the mechanisms of viral recognition governing production of type I IFN during herpes...... simplex virus (HSV) infection. We show that early production of IFN in vivo is mediated through Toll-like receptor 9 (TLR9) and plasmacytoid dendritic cells, whereas the subsequent alpha/beta IFN (IFN-alpha/beta) response is derived from several cell types and induced independently of TLR9...

  16. Immune evasion of porcine enteric coronaviruses and viral modulation of antiviral innate signaling.

    Science.gov (United States)

    Zhang, Qingzhan; Yoo, Dongwan

    2016-12-02

    Porcine epidemic diarrhea virus (PEDV) and porcine deltacoronavirus (PDCoV) are emerged and reemerging viruses in pigs, and together with transmissible gastroenteritis virus (TGEV), pose significant economic concerns to the swine industry. These viruses infect epithelial cells of the small intestine and cause watery diarrhea, dehydration, and a high mortality in neonatal piglets. Type I interferons (IFN-α/β) are major antiviral cytokines forming host innate immunity, and in turn, these enteric coronaviruses have evolved to modulate the host innate immune signaling during infection. Accumulating evidence however suggests that IFN induction and signaling in the intestinal epithelial cells differ from other epithelial cells, largely due to distinct features of the gut epithelial mucosal surface and commensal microflora, and it appears that type III interferon (IFN-λ) plays a key role to maintain the antiviral state in the gut. This review describes the recent understanding on the immune evasion strategies of porcine enteric coronaviruses and the role of different types of IFNs for intestinal antiviral innate immunity. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Protein-Protein Interactions of Viroporins in Coronaviruses and Paramyxoviruses: New Targets for Antivirals?

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    Jaume Torres

    2015-06-01

    Full Text Available Viroporins are members of a rapidly growing family of channel-forming small polypeptides found in viruses. The present review will be focused on recent structural and protein-protein interaction information involving two viroporins found in enveloped viruses that target the respiratory tract; (i the envelope protein in coronaviruses and (ii the small hydrophobic protein in paramyxoviruses. Deletion of these two viroporins leads to viral attenuation in vivo, whereas data from cell culture shows involvement in the regulation of stress and inflammation. The channel activity and structure of some representative members of these viroporins have been recently characterized in some detail. In addition, searches for protein-protein interactions using yeast-two hybrid techniques have shed light on possible functional roles for their exposed cytoplasmic domains. A deeper analysis of these interactions should not only provide a more complete overview of the multiple functions of these viroporins, but also suggest novel strategies that target protein-protein interactions as much needed antivirals. These should complement current efforts to block viroporin channel activity.

  18. Antiviral and antitumor activities of the protein fractions from the ...

    African Journals Online (AJOL)

    In this study, we present the extraction and purification of protein fractions from the larvae of the housefly, Musca domestica. The bioactivities of the protein fractions were indicated by pseudorabies virus (PRV) and human lung cancer cell line A 549. The crude protein fractions had no toxicity to chick embryo fibroblast-like ...

  19. Nuclear trafficking of proteins from RNA viruses: potential target for antivirals?

    Science.gov (United States)

    Caly, Leon; Wagstaff, Kylie M; Jans, David A

    2012-09-01

    A key aspect of the infectious cycle of many viruses is the transport of specific viral proteins into the host cell nucleus to perturb the antiviral response. Examples include a number of RNA viruses that are significant human pathogens, such as human immunodeficiency virus (HIV)-1, influenza A, dengue, respiratory syncytial virus and rabies, as well agents that predominantly infect livestock, such as Rift valley fever virus and Venezuelan equine encephalitis virus. Inhibiting the nuclear trafficking of viral proteins as a therapeutic strategy offers an attractive possibility, with important recent progress having been made with respect to HIV-1 and dengue. The results validate nuclear protein import as an antiviral target, and suggest the identification and development of nuclear transport inhibitors as a viable therapeutic approach for a range of human and zoonotic pathogenic viruses. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. A single WAP domain (SWD)-containing protein with antiviral activity from Pacific white shrimp Litopenaeus vannamei.

    Science.gov (United States)

    Yang, Linwei; Niu, Shengwen; Gao, Jiefeng; Zuo, Hongliang; Yuan, Jia; Weng, Shaoping; He, Jianguo; Xu, Xiaopeng

    2018-02-01

    The single whey acidic protein (WAP) domain (SWD)-containing proteins, also called type III crustins, are a group of antimicrobial peptides (AMPs) in crustaceans. At present, a number of SWDs have been identified in shrimp, which showed essential antibacterial activities. However, the roles of SWDs in antiviral immune responses have not been reported up to now. In this study, a novel SWD (LvSWD3) was identified from Pacific white shrimp, Litopenaeus vannamei, which contained a typical single WAP domain homologous to those of other crustacean SWDs. Although lacking the pro and arg-rich region between the signal peptide and the WAP domain, LvSWD3 was closely clustered with other shrimp SWDs in the phylogenetic tree. Similar to many shrimp SWDs, the highest expression of LvSWD3 was detected in hemocytes. The LvSWD3 expression exhibited only limited changes after challenges with Vibrio parahaemolyticus, Poly (I:C) and lipopolysaccharide, but was significantly up-regulated after white spot syndrome virus (WSSV) infection. Silencing of LvSWDs significantly accelerated the death of the WSSV-infected but not the V. parahaemolyticus-infected shrimp. The recombinant LvSWD3 protein did not show proteinase inhibitory and antibacterial activities but could significantly postpone the death of WSSV-infected shrimp and reduce the viral load in tissues. These suggested that LvSWD3 was a novel SWD with antiviral activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Antiviral and antitumor activities of the protein fractions from the ...

    African Journals Online (AJOL)

    AJL

    2012-05-15

    May 15, 2012 ... embryo fibroblast-like (CEF) cells but effective to PRV at the concentration of 100 µg/ml .... The in vitro inhibitory effect of the purified protein fractions on ... (DMSO) with 10% fetal bovine serum was plated on 96-well plates.

  2. Pokeweed Antiviral Protein: Its Cytotoxicity Mechanism and Applications in Plant Disease Resistance

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    Rong Di

    2015-03-01

    Full Text Available Pokeweed antiviral protein (PAP is a 29 kDa type I ribosome inactivating protein (RIP found in pokeweed plants. Pokeweed produces different forms of PAP. This review focuses on the spring form of PAP isolated from Phytolacca americana leaves. PAP exerts its cytotoxicity by removing a specific adenine from the α-sarcin/ricin loop of the large ribosomal RNA. Besides depurination of the rRNA, PAP has additional activities that contribute to its cytotoxicity. The mechanism of PAP cytotoxicity is summarized based on evidence from the analysis of transgenic plants and the yeast model system. PAP was initially found to be anti-viral when it was co-inoculated with plant viruses onto plants. Transgenic plants expressing PAP and non-toxic PAP mutants have displayed broad-spectrum resistance to both viral and fungal infection. The mechanism of PAP-induced disease resistance in transgenic plants is summarized.

  3. Antiviral RNA silencing suppression activity of Tomato spotted wilt virus NSs protein.

    Science.gov (United States)

    Ocampo Ocampo, T; Gabriel Peralta, S M; Bacheller, N; Uiterwaal, S; Knapp, A; Hennen, A; Ochoa-Martinez, D L; Garcia-Ruiz, H

    2016-06-17

    In addition to regulating gene expression, RNA silencing is an essential antiviral defense system in plants. Triggered by double-stranded RNA, silencing results in degradation or translational repression of target transcripts. Viruses are inducers and targets of RNA silencing. To condition susceptibility, most plant viruses encode silencing suppressors that interfere with this process, such as the Tomato spotted wilt virus (TSWV) NSs protein. The mechanism by which NSs suppresses RNA silencing and its role in viral infection and movement remain to be determined. We cloned NSs from the Hawaii isolate of TSWV and using two independent assays show for the first time that this protein restored pathogenicity and supported the formation of local infection foci by suppressor-deficient Turnip mosaic virus and Turnip crinkle virus. Demonstrating the suppression of RNA silencing directed against heterologous viruses establishes the foundation to determine the means used by NSs to block this antiviral process.

  4. Antiviral Protein of Momordica charantia L. Inhibits Different Subtypes of Influenza A

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    Viroj Pongthanapisith

    2013-01-01

    Full Text Available The new antiviral activity of the protein extracted from Momordica charantia was determined with different subtypes of influenza A. The protein was purified from the seed of M. charantia using an anion exchanger and a Fast Protein Liquid Chromatography (FPLC system. At the concentration of 1.401 mg/mL, the protein did not exhibit cytotoxicity in Madin-Darby canine kidney cells (MDCK but inhibited FFU influenza A/PR/8/34 H1N1 virus at 56.50%, 65.72%, and 100% inhibition by the protein treated before the virus (pretreated, the protein treated alongside with the virus (simultaneously treated, and the protein treated after the virus (posttreated during incubation, respectively. Using 5, 25, and 100 TCID50 of influenza A/New Caledonia/20/99 H1N1, A/Fujian/411/01 H3N2 and A/Thailand/1(KAN-1/2004 H5N1, the IC50 was calculated to be 100, 150, and 200; 75, 175, and 300; and 40, 75, and 200 μg/mL, respectively. Our present finding indicated that the plant protein inhibited not only H1N1 and H3N2 but also H5N1 subtype. As a result of the broad spectrum of its antiviral activity, this edible plant can be developed as an effective therapeutic agent against various and even new emerging subtypes of influenza A.

  5. Human cytomegaloviruses expressing yellow fluorescent fusion proteins--characterization and use in antiviral screening.

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    Sarah Straschewski

    Full Text Available Recombinant viruses labelled with fluorescent proteins are useful tools in molecular virology with multiple applications (e.g., studies on intracellular trafficking, protein localization, or gene activity. We generated by homologous recombination three recombinant cytomegaloviruses carrying the enhanced yellow fluorescent protein (EYFP fused with the viral proteins IE-2, ppUL32 (pp150, and ppUL83 (pp65. In growth kinetics, the three viruses behaved all like wild type, even at low multiplicity of infection (MOI. The expression of all three fusion proteins was detected, and their respective localizations were the same as for the unmodified proteins in wild-type virus-infected cells. We established the in vivo measurement of fluorescence intensity and used the recombinant viruses to measure inhibition of viral replication by neutralizing antibodies or antiviral substances. The use of these viruses in a pilot screen based on fluorescence intensity and high-content analysis identified cellular kinase inhibitors that block viral replication. In summary, these viruses with individually EYFP-tagged proteins will be useful to study antiviral substances and the dynamics of viral infection in cell culture.

  6. HIV-1 accessory proteins VPR and Vif modulate antiviral response by targeting IRF-3 for degradation

    International Nuclear Information System (INIS)

    Okumura, Atsushi; Alce, Tim; Lubyova, Barbora; Ezelle, Heather; Strebel, Klaus; Pitha, Paula M.

    2008-01-01

    The activation of IRF-3 during the early stages of viral infection is critical for the initiation of the antiviral response; however the activation of IRF-3 in HIV-1 infected cells has not yet been characterized. We demonstrate that the early steps of HIV-1 infection do not lead to the activation and nuclear translocation of IRF-3; instead, the relative levels of IRF-3 protein are decreased due to the ubiquitin-associated proteosome degradation. Addressing the molecular mechanism of this effect we show that the degradation is independent of HIV-1 replication and that virion-associated accessory proteins Vif and Vpr can independently degrade IRF-3. The null mutation of these two genes reduced the capacity of the HIV-1 virus to down modulate IRF-3 levels. The degradation was associated with Vif- and Vpr-mediated ubiquitination of IRF-3 and was independent of the activation of IRF-3. N-terminal lysine residues were shown to play a critical role in the Vif- and Vpr-mediated degradation of IRF-3. These data implicate Vif and Vpr in the disruption of the initial antiviral response and point to the need of HIV-1 to circumvent the antiviral response during the very early phase of replication

  7. SUMO Ligase Protein Inhibitor of Activated STAT1 (PIAS1) Is a Constituent Promyelocytic Leukemia Nuclear Body Protein That Contributes to the Intrinsic Antiviral Immune Response to Herpes Simplex Virus 1.

    Science.gov (United States)

    Brown, James R; Conn, Kristen L; Wasson, Peter; Charman, Matthew; Tong, Lily; Grant, Kyle; McFarlane, Steven; Boutell, Chris

    2016-07-01

    Aspects of intrinsic antiviral immunity are mediated by promyelocytic leukemia nuclear body (PML-NB) constituent proteins. During herpesvirus infection, these antiviral proteins are independently recruited to nuclear domains that contain infecting viral genomes to cooperatively promote viral genome silencing. Central to the execution of this particular antiviral response is the small ubiquitin-like modifier (SUMO) signaling pathway. However, the participating SUMOylation enzymes are not fully characterized. We identify the SUMO ligase protein inhibitor of activated STAT1 (PIAS1) as a constituent PML-NB protein. We show that PIAS1 localizes at PML-NBs in a SUMO interaction motif (SIM)-dependent manner that requires SUMOylated or SUMOylation-competent PML. Following infection with herpes simplex virus 1 (HSV-1), PIAS1 is recruited to nuclear sites associated with viral genome entry in a SIM-dependent manner, consistent with the SIM-dependent recruitment mechanisms of other well-characterized PML-NB proteins. In contrast to that of Daxx and Sp100, however, the recruitment of PIAS1 is enhanced by PML. PIAS1 promotes the stable accumulation of SUMO1 at nuclear sites associated with HSV-1 genome entry, whereas the accumulation of other evaluated PML-NB proteins occurs independently of PIAS1. We show that PIAS1 cooperatively contributes to HSV-1 restriction through mechanisms that are additive to those of PML and cooperative with those of PIAS4. The antiviral mechanisms of PIAS1 are counteracted by ICP0, the HSV-1 SUMO-targeted ubiquitin ligase, which disrupts the recruitment of PIAS1 to nuclear domains that contain infecting HSV-1 genomes through mechanisms that do not directly result in PIAS1 degradation. Adaptive, innate, and intrinsic immunity cooperatively and efficiently restrict the propagation of viral pathogens. Intrinsic immunity mediated by constitutively expressed cellular proteins represents the first line of intracellular defense against infection. PML

  8. High throughput screening for small molecule enhancers of the interferon signaling pathway to drive next-generation antiviral drug discovery.

    Directory of Open Access Journals (Sweden)

    Dhara A Patel

    Full Text Available Most of current strategies for antiviral therapeutics target the virus specifically and directly, but an alternative approach to drug discovery might be to enhance the immune response to a broad range of viruses. Based on clinical observation in humans and successful genetic strategies in experimental models, we reasoned that an improved interferon (IFN signaling system might better protect against viral infection. Here we aimed to identify small molecular weight compounds that might mimic this beneficial effect and improve antiviral defense. Accordingly, we developed a cell-based high-throughput screening (HTS assay to identify small molecules that enhance the IFN signaling pathway components. The assay is based on a phenotypic screen for increased IFN-stimulated response element (ISRE activity in a fully automated and robust format (Z'>0.7. Application of this assay system to a library of 2240 compounds (including 2160 already approved or approvable drugs led to the identification of 64 compounds with significant ISRE activity. From these, we chose the anthracycline antibiotic, idarubicin, for further validation and mechanism based on activity in the sub-µM range. We found that idarubicin action to increase ISRE activity was manifest by other members of this drug class and was independent of cytotoxic or topoisomerase inhibitory effects as well as endogenous IFN signaling or production. We also observed that this compound conferred a consequent increase in IFN-stimulated gene (ISG expression and a significant antiviral effect using a similar dose-range in a cell-culture system inoculated with encephalomyocarditis virus (EMCV. The antiviral effect was also found at compound concentrations below the ones observed for cytotoxicity. Taken together, our results provide proof of concept for using activators of components of the IFN signaling pathway to improve IFN efficacy and antiviral immune defense as well as a validated HTS approach to identify

  9. Fusion protein of tapasin and hepatitis B core antigen 18‑27 enhances T helper cell type 1/2 cytokine ratio and antiviral immunity by inhibiting suppressors of cytokine signaling family members 1/3 in hepatitis B virus transgenic mice.

    Science.gov (United States)

    Tang, Yuyan; Chen, Xiaohua; Zhang, Yi; Tang, Zhenghao; Zhuo, Meng; Li, Dan; Wang, Peng; Zang, Guoqing; Yu, Yongsheng

    2014-04-01

    Persistent hepatitis B virus (HBV) infection is characterized by a weak adaptive immune response, which is considered to be due to an imbalance of T helper cell types 1 and 2 (Th1/Th2). Suppressors of cytokine signaling (SOCS) family members, particularly SOCS1 and SOCS3, have been demonstrated to be important in the regulation of T cell differentiation. Previous studies by our group showed that the expressed and purified fusion protein of cytoplasmic transduction peptide (CTP) and HBV core antigen 18‑27 (HBcAg18‑27)‑tapasin was able to enter the cytoplasm of bone marrow‑derived dendritic cells (BMDCs), promoting the maturation of BMDCs and efficiently enhancing T cell immune responses in vitro. In the present study, HBcAg‑specific immune responses induced by CTP‑HBcAg18‑27‑tapasin in HBV were assessed in transgenic mice, and SOCS1 and SOCS3 were identified as negative regulators of this response. The Th1/Th2 cytokine ratio was analyzed by ELISA. The expression of T cell‑specific T‑box transcription factor (T‑bet) and GATA‑binding protein 3 (GATA‑3), SOCS1 and SOCS3 were detected by real‑time quantitative polymerase chain reaction and western blot analysis. The results demonstrated that CTP‑HBcAg18‑27‑tapasin significantly increased the Th1/Th2 cytokine ratio in HBV transgenic mice. CTP‑HBcAg18‑27‑tapasin immunization more efficiently suppressed the expression of serum hepatitis B surface antigen (HBsAg), HBV DNA as well as liver HBsAg and HBcAg in HBV transgenic mice. Furthermore, CTP‑HBcAg18‑27‑tapasin promotes T‑bet but reduces GATA‑3 expression. In addition, the expression of SOCS1 and SOCS3 was significantly downregulated in the CTP‑HBcAg18‑27‑tapasin group compared with the control groups. In conclusion, the present study demonstrated that CTP‑HBcAg18‑27‑tapasin enhanced the Th1/Th2 cytokine ratio and antiviral immunity by suppressing SOCS1/3 in HBV transgenic mice.

  10. NSs protein of Schmallenberg virus counteracts the antiviral response of the cell by inhibiting its transcriptional machinery.

    Science.gov (United States)

    Barry, Gerald; Varela, Mariana; Ratinier, Maxime; Blomström, Anne-Lie; Caporale, Marco; Seehusen, Frauke; Hahn, Kerstin; Schnettler, Esther; Baumgärtner, Wolfgang; Kohl, Alain; Palmarini, Massimo

    2014-08-01

    Bunyaviruses have evolved a variety of strategies to counteract the antiviral defence systems of mammalian cells. Here we show that the NSs protein of Schmallenberg virus (SBV) induces the degradation of the RPB1 subunit of RNA polymerase II and consequently inhibits global cellular protein synthesis and the antiviral response. In addition, we show that the SBV NSs protein enhances apoptosis in vitro and possibly in vivo, suggesting that this protein could be involved in SBV pathogenesis in different ways. © 2014 The Authors.

  11. Evasion of antiviral innate immunity by Theiler's virus L* protein through direct inhibition of RNase L.

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    Frédéric Sorgeloos

    Full Text Available Theiler's virus is a neurotropic picornavirus responsible for chronic infections of the central nervous system. The establishment of a persistent infection and the subsequent demyelinating disease triggered by the virus depend on the expression of L*, a viral accessory protein encoded by an alternative open reading frame of the virus. We discovered that L* potently inhibits the interferon-inducible OAS/RNase L pathway. The antagonism of RNase L by L* was particularly prominent in macrophages where baseline oligoadenylate synthetase (OAS and RNase L expression levels are elevated, but was detectable in fibroblasts after IFN pretreatment. L* mutations significantly affected Theiler's virus replication in primary macrophages derived from wild-type but not from RNase L-deficient mice. L* counteracted the OAS/RNase L pathway through direct interaction with the ankyrin domain of RNase L, resulting in the inhibition of this enzyme. Interestingly, RNase L inhibition was species-specific as Theiler's virus L* protein blocked murine RNase L but not human RNase L or RNase L of other mammals or birds. Direct RNase L inhibition by L* and species specificity were confirmed in an in vitro assay performed with purified proteins. These results demonstrate a novel viral mechanism to elude the antiviral OAS/RNase L pathway. By targeting the effector enzyme of this antiviral pathway, L* potently inhibits RNase L, underscoring the importance of this enzyme in innate immunity against Theiler's virus.

  12. Inhibition of enterovirus 71 (EV-71 infections by a novel antiviral peptide derived from EV-71 capsid protein VP1.

    Directory of Open Access Journals (Sweden)

    Chee Wah Tan

    Full Text Available Enterovirus 71 (EV-71 is the main causative agent of hand, foot and mouth disease (HFMD. In recent years, EV-71 infections were reported to cause high fatalities and severe neurological complications in Asia. Currently, no effective antiviral or vaccine is available to treat or prevent EV-71 infection. In this study, we have discovered a synthetic peptide which could be developed as a potential antiviral for inhibition of EV-71. Ninety five synthetic peptides (15-mers overlapping the entire EV-71 capsid protein, VP1, were chemically synthesized and tested for antiviral properties against EV-71 in human Rhabdomyosarcoma (RD cells. One peptide, SP40, was found to significantly reduce cytopathic effects of all representative EV-71 strains from genotypes A, B and C tested, with IC(50 values ranging from 6-9.3 µM in RD cells. The in vitro inhibitory effect of SP40 exhibited a dose dependent concentration corresponding to a decrease in infectious viral particles, total viral RNA and the levels of VP1 protein. The antiviral activity of SP40 peptide was not restricted to a specific cell line as inhibition of EV-71 was observed in RD, HeLa, HT-29 and Vero cells. Besides inhibition of EV-71, it also had antiviral activities against CV-A16 and poliovirus type 1 in cell culture. Mechanism of action studies suggested that the SP40 peptide was not virucidal but was able to block viral attachment to the RD cells. Substitutions of arginine and lysine residues with alanine in the SP40 peptide at positions R3A, R4A, K5A and R13A were found to significantly decrease antiviral activities, implying the importance of positively charged amino acids for the antiviral activities. The data demonstrated the potential and feasibility of SP40 as a broad spectrum antiviral agent against EV-71.

  13. Type I and Type III Interferons Display Different Dependency on Mitogen-Activated Protein Kinases to Mount an Antiviral State in the Human Gut.

    Science.gov (United States)

    Pervolaraki, Kalliopi; Stanifer, Megan L; Münchau, Stephanie; Renn, Lynnsey A; Albrecht, Dorothee; Kurzhals, Stefan; Senís, Elena; Grimm, Dirk; Schröder-Braunstein, Jutta; Rabin, Ronald L; Boulant, Steeve

    2017-01-01

    Intestinal epithelial cells (IECs) are constantly exposed to commensal flora and pathogen challenges. How IECs regulate their innate immune response to maintain gut homeostasis remains unclear. Interferons (IFNs) are cytokines produced during infections. While type I IFN receptors are ubiquitously expressed, type III IFN receptors are expressed only on epithelial cells. This epithelium specificity strongly suggests exclusive functions at epithelial surfaces, but the relative roles of type I and III IFNs in the establishment of an antiviral innate immune response in human IECs are not clearly defined. Here, we used mini-gut organoids to define the functions of types I and III IFNs to protect the human gut against viral infection. We show that primary non-transformed human IECs, upon viral challenge, upregulate the expression of both type I and type III IFNs at the transcriptional level but only secrete type III IFN in the supernatant. However, human IECs respond to both type I and type III IFNs by producing IFN-stimulated genes that in turn induce an antiviral state. Using genetic ablation of either type I or type III IFN receptors, we show that either IFN can independently restrict virus infection in human IECs. Importantly, we report, for the first time, differences in the mechanisms by which each IFN establishes the antiviral state. Contrary to type I IFN, the antiviral activity induced by type III IFN is strongly dependent on the mitogen-activated protein kinases signaling pathway, suggesting a pathway used by type III IFNs that non-redundantly contributes to the antiviral state. In conclusion, we demonstrate that human intestinal epithelial cells specifically regulate their innate immune response favoring type III IFN-mediated signaling, which allows for efficient protection against pathogens without producing excessive inflammation. Our results strongly suggest that type III IFN constitutes the frontline of antiviral response in the human gut. We propose that

  14. A general strategy to endow natural fusion-protein-derived peptides with potent antiviral activity.

    Directory of Open Access Journals (Sweden)

    Antonello Pessi

    Full Text Available Fusion between the viral and target cell membranes is an obligatory step for the infectivity of all enveloped virus, and blocking this process is a clinically validated therapeutic strategy.Viral fusion is driven by specialized proteins which, although specific to each virus, act through a common mechanism, the formation of a complex between two heptad repeat (HR regions. The HR regions are initially separated in an intermediate termed "prehairpin", which bridges the viral and cell membranes, and then fold onto each other to form a 6-helical bundle (6HB, driving the two membranes to fuse. HR-derived peptides can inhibit viral infectivity by binding to the prehairpin intermediate and preventing its transition to the 6HB.The antiviral activity of HR-derived peptides differs considerably among enveloped viruses. For weak inhibitors, potency can be increased by peptide engineering strategies, but sequence-specific optimization is time-consuming. In seeking ways to increase potency without changing the native sequence, we previously reported that attachment to the HR peptide of a cholesterol group ("cholesterol-tagging" dramatically increases its antiviral potency, and simultaneously increases its half-life in vivo. We show here that antiviral potency may be increased by combining cholesterol-tagging with dimerization of the HR-derived sequence, using as examples human parainfluenza virus, Nipah virus, and HIV-1. Together, cholesterol-tagging and dimerization may represent strategies to boost HR peptide potency to levels that in some cases may be compatible with in vivo use, possibly contributing to emergency responses to outbreaks of existing or novel viruses.

  15. High Expression of Antiviral Proteins in Mucosa from Individuals Exhibiting Resistance to Human Immunodeficiency Virus.

    Directory of Open Access Journals (Sweden)

    Sandra Milena Gonzalez

    Full Text Available Several soluble factors have been reported to have the capacity of inhibiting HIV replication at different steps of the virus life cycle, without eliminating infected cells and through enhancement of specific cellular mechanisms. Yet, it is unclear if these antiviral factors play a role in the protection from HIV infection or in the control of viral replication. Here we evaluated two cohorts: i one of 58 HIV-exposed seronegative individuals (HESNs who were compared with 59 healthy controls (HCs, and ii another of 13 HIV-controllers who were compared with 20 HIV-progressors. Peripheral blood, oral and genital mucosa and gut-associated lymphoid tissue (GALT samples were obtained to analyze the mRNA expression of ELAFIN, APOBEC3G, SAMHD1, TRIM5α, RNase 7 and SerpinA1 using real-time PCR.HESNs exhibited higher expression of all antiviral factors in peripheral blood mononuclear cells (PBMCs, oral or genital mucosa when compared with HCs. Furthermore, HIV-controllers exhibited higher levels of SerpinA1 in GALT.These findings suggest that the activity of these factors is compartmentalized and that these proteins have a predominant role depending on the tissue to avoid the infection, reduce the viral load and modulate the susceptibility to HIV infection.

  16. Antiviral activity of a small molecule deubiquitinase inhibitor occurs via induction of the unfolded protein response.

    Directory of Open Access Journals (Sweden)

    Jeffrey W Perry

    Full Text Available Ubiquitin (Ub is a vital regulatory component in various cellular processes, including cellular responses to viral infection. As obligate intracellular pathogens, viruses have the capacity to manipulate the ubiquitin (Ub cycle to their advantage by encoding Ub-modifying proteins including deubiquitinases (DUBs. However, how cellular DUBs modulate specific viral infections, such as norovirus, is poorly understood. To examine the role of DUBs during norovirus infection, we used WP1130, a small molecule inhibitor of a subset of cellular DUBs. Replication of murine norovirus in murine macrophages and the human norovirus Norwalk virus in a replicon system were significantly inhibited by WP1130. Chemical proteomics identified the cellular DUB USP14 as a target of WP1130 in murine macrophages, and pharmacologic inhibition or siRNA-mediated knockdown of USP14 inhibited murine norovirus infection. USP14 is a proteasome-associated DUB that also binds to inositol-requiring enzyme 1 (IRE1, a critical mediator of the unfolded protein response (UPR. WP1130 treatment of murine macrophages did not alter proteasome activity but activated the X-box binding protein-1 (XBP-1 through an IRE1-dependent mechanism. In addition, WP1130 treatment or induction of the UPR also reduced infection of other RNA viruses including encephalomyocarditis virus, Sindbis virus, and La Crosse virus but not vesicular stomatitis virus. Pharmacologic inhibition of the IRE1 endonuclease activity partially rescued the antiviral effect of WP1130. Taken together, our studies support a model whereby induction of the UPR through cellular DUB inhibition blocks specific viral infections, and suggest that cellular DUBs and the UPR represent novel targets for future development of broad spectrum antiviral therapies.

  17. Which Plant Proteins Are Involved in Antiviral Defense? Review on In Vivo and In Vitro Activities of Selected Plant Proteins against Viruses

    Directory of Open Access Journals (Sweden)

    Oskar Musidlak

    2017-11-01

    Full Text Available Plants have evolved a variety of defense mechanisms to tackle virus attack. Endogenous plant proteins can function as virus suppressors. Different types of proteins mediate defense responses against plant viruses. Pathogenesis-related (PR proteins are activated upon pathogen infections or in different stress situations and their production is one of many components in plant defense. Ribosome-inactivating proteins (RIPs suppress translation by enzymatically damaging ribosomes and they have been found to have antiviral activity. RNA-binding proteins (RBPs bind to target RNAs via specialized RNA-binding domain and can directly or indirectly function in plant defense system against RNA viruses. Proteins involved in silencing machinery, namely Dicer-like (DCL proteins, Argonaute (AGO proteins, and RNA-dependent RNA polymerases (RDRs confer innate antiviral defense in plants as they are able to degrade foreign RNA of viral origin. This review aims to provide a comprehensive and up-to-date picture of plant proteins participating in antiviral defense. As a result we discuss proteins conferring plant antiviral resistance and their potential future applications in different fields of life including agriculture and medicine.

  18. Glucose-6-Phosphate Dehydrogenase Enhances Antiviral Response through Downregulation of NADPH Sensor HSCARG and Upregulation of NF-κB Signaling

    Directory of Open Access Journals (Sweden)

    Yi-Hsuan Wu

    2015-12-01

    Full Text Available Glucose-6-phosphate dehydrogenase (G6PD-deficient cells are highly susceptible to viral infection. This study examined the mechanism underlying this phenomenon by measuring the expression of antiviral genes—tumor necrosis factor alpha (TNF-α and GTPase myxovirus resistance 1 (MX1—in G6PD-knockdown cells upon human coronavirus 229E (HCoV-229E and enterovirus 71 (EV71 infection. Molecular analysis revealed that the promoter activities of TNF-α and MX1 were downregulated in G6PD-knockdown cells, and that the IκB degradation and DNA binding activity of NF-κB were decreased. The HSCARG protein, a nicotinamide adenine dinucleotide phosphate (NADPH sensor and negative regulator of NF-κB, was upregulated in G6PD-knockdown cells with decreased NADPH/NADP+ ratio. Treatment of G6PD-knockdown cells with siRNA against HSCARG enhanced the DNA binding activity of NF-κB and the expression of TNF-α and MX1, but suppressed the expression of viral genes; however, the overexpression of HSCARG inhibited the antiviral response. Exogenous G6PD or IDH1 expression inhibited the expression of HSCARG, resulting in increased expression of TNF-α and MX1 and reduced viral gene expression upon virus infection. Our findings suggest that the increased susceptibility of the G6PD-knockdown cells to viral infection was due to impaired NF-κB signaling and antiviral response mediated by HSCARG.

  19. Identification of Secreted Proteins Involved in Nonspecific dsRNA-Mediated Lutzomyia longipalpis LL5 Cell Antiviral Response

    Directory of Open Access Journals (Sweden)

    Andrea Martins-da-Silva

    2018-01-01

    Full Text Available Hematophagous insects transmit infectious diseases. Sand flies are vectors of leishmaniasis, but can also transmit viruses. We have been studying immune responses of Lutzomyia longipalpis, the main vector of visceral leishmaniasis in the Americas. We identified a non-specific antiviral response in L. longipalpis LL5 embryonic cells when treated with non-specific double-stranded RNAs (dsRNAs. This response is reminiscent of interferon response in mammals. We are investigating putative effectors for this antiviral response. Secreted molecules have been implicated in immune responses, including interferon-related responses. We conducted a mass spectrometry analysis of conditioned medium from LL5 cells 24 and 48 h after dsRNA or mock treatment. We identified 304 proteins. At 24 h, 19 proteins had an abundance equal or greater than 2-fold change, while the levels of 17 proteins were reduced when compared to control cells. At the 48 h time point, these numbers were 33 and 71, respectively. The two most abundant secreted peptides at 24 h in the dsRNA-transfected group were phospholipid scramblase, an interferon-inducible protein that mediates antiviral activity, and forskolin-binding protein (FKBP, a member of the immunophilin family, which mediates the effect of immunosuppressive drugs. The transcription profile of most candidates did not follow the pattern of secreted protein abundance.

  20. The Adenovirus E1A C Terminus Suppresses a Delayed Antiviral Response and Modulates RAS Signaling.

    Science.gov (United States)

    Zemke, Nathan R; Berk, Arnold J

    2017-12-13

    The N-terminal half of adenovirus e1a assembles multimeric complexes with host proteins that repress innate immune responses and force host cells into S-phase. In contrast, the functions of e1a's C-terminal interactions with FOXK, DCAF7, and CtBP are unknown. We found that these interactions modulate RAS signaling, and that a single e1a molecule must bind all three of these host proteins to suppress activation of a subset of IFN-stimulated genes (ISGs). These ISGs were otherwise induced in primary respiratory epithelial cells at 12 hr p.i. This delayed activation of ISGs required IRF3 and coincided with an ∼10-fold increase in IRF3 from protein stabilization. The induced IRF3 bound to chromatin and localized to the promoters of activated ISGs. While IRF3, STAT1/2, and IRF9 all greatly increased in concentration, there were no corresponding mRNA increases, suggesting that e1a regulates the stabilities of these key activators of innate immune responses, as shown directly for IRF3. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Histophilus somni Stimulates Expression of Antiviral Proteins and Inhibits BRSV Replication in Bovine Respiratory Epithelial Cells.

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    C Lin

    Full Text Available Our previous studies showed that bovine respiratory syncytial virus (BRSV followed by Histophilus somni causes more severe bovine respiratory disease and a more permeable alveolar barrier in vitro than either agent alone. However, microarray analysis revealed the treatment of bovine alveolar type 2 (BAT2 epithelial cells with H. somni concentrated culture supernatant (CCS stimulated up-regulation of four antiviral protein genes as compared with BRSV infection or dual treatment. This suggested that inhibition of viral infection, rather than synergy, may occur if the bacterial infection occurred before the viral infection. Viperin (or radical S-adenosyl methionine domain containing 2--RSAD2 and ISG15 (IFN-stimulated gene 15--ubiquitin-like modifier were most up-regulated. CCS dose and time course for up-regulation of viperin protein levels were determined in treated bovine turbinate (BT upper respiratory cells and BAT2 lower respiratory cells by Western blotting. Treatment of BAT2 cells with H. somni culture supernatant before BRSV infection dramatically reduced viral replication as determined by qRT PCR, supporting the hypothesis that the bacterial infection may inhibit viral infection. Studies of the role of the two known H. somni cytotoxins showed that viperin protein expression was induced by endotoxin (lipooligosaccharide but not by IbpA, which mediates alveolar permeability and H. somni invasion. A naturally occurring IbpA negative asymptomatic carrier strain of H. somni (129Pt does not cause BAT2 cell retraction or permeability of alveolar cell monolayers, so lacks virulence in vitro. To investigate initial steps of pathogenesis, we showed that strain 129Pt attached to BT cells and induced a strong viperin response in vitro. Thus colonization of the bovine upper respiratory tract with an asymptomatic carrier strain lacking virulence may decrease viral infection and the subsequent enhancement of bacterial respiratory infection in vivo.

  2. CNS activity of Pokeweed Anti-viral Protein (PAP in mice infected with Lymphocytic Choriomeningitis Virus (LCMV

    Directory of Open Access Journals (Sweden)

    Tibbles Heather E

    2005-02-01

    Full Text Available Abstract Background Others and we have previously described the potent in vivo and in vitro activity of the broad-spectrum antiviral agent PAP (Pokeweed antiviral protein against a wide range of viruses. The purpose of the present study was to further elucidate the anti-viral spectrum of PAP by examining its effects on the survival of mice challenged with lymphocytic choriomeningitis virus (LCMV. Methods We examined the therapeutic effect of PAP in CBA mice inoculated with intracerebral injections of the WE54 strain of LCMV at a 1000 PFU dose level that is lethal to 100% of mice within 7–9 days. Mice were treated either with vehicle or PAP administered intraperitoneally 24 hours prior to, 1 hour prior to and 24 hours, 48 hours 72 hours and 96 hours after virus inoculation. Results PAP exhibits significant in vivo anti- LCMV activity in mice challenged intracerebrally with an otherwise invariably fatal dose of LCMV. At non-toxic dose levels, PAP significantly prolonged survival in the absence of the majority of disease-associated symptoms. The median survival time of PAP-treated mice was >21 days as opposed to 7 days median survival for the control (p = 0.0069. Conclusion Our results presented herein provide unprecedented experimental evidence that PAP exhibits antiviral activity in the CNS of LCMV-infected mice.

  3. Predicting Secretory Proteins with SignalP

    DEFF Research Database (Denmark)

    Nielsen, Henrik

    2017-01-01

    SignalP is the currently most widely used program for prediction of signal peptides from amino acid sequences. Proteins with signal peptides are targeted to the secretory pathway, but are not necessarily secreted. After a brief introduction to the biology of signal peptides and the history...

  4. Evolution and Antiviral Specificities of Interferon-Induced Mx Proteins of Bats against Ebola, Influenza, and Other RNA Viruses.

    Science.gov (United States)

    Fuchs, Jonas; Hölzer, Martin; Schilling, Mirjam; Patzina, Corinna; Schoen, Andreas; Hoenen, Thomas; Zimmer, Gert; Marz, Manja; Weber, Friedemann; Müller, Marcel A; Kochs, Georg

    2017-08-01

    Bats serve as a reservoir for various, often zoonotic viruses, including significant human pathogens such as Ebola and influenza viruses. However, for unknown reasons, viral infections rarely cause clinical symptoms in bats. A tight control of viral replication by the host innate immune defense might contribute to this phenomenon. Transcriptomic studies revealed the presence of the interferon-induced antiviral myxovirus resistance (Mx) proteins in bats, but detailed functional aspects have not been assessed. To provide evidence that bat Mx proteins might act as key factors to control viral replication we cloned Mx1 cDNAs from three bat families, Pteropodidae, Phyllostomidae, and Vespertilionidae. Phylogenetically these bat Mx1 genes cluster closely with their human ortholog MxA. Using transfected cell cultures, minireplicon systems, virus-like particles, and virus infections, we determined the antiviral potential of the bat Mx1 proteins. Bat Mx1 significantly reduced the polymerase activity of viruses circulating in bats, including Ebola and influenza A-like viruses. The related Thogoto virus, however, which is not known to infect bats, was not inhibited by bat Mx1. Further, we provide evidence for positive selection in bat Mx1 genes that might explain species-specific antiviral activities of these proteins. Together, our data suggest a role for Mx1 in controlling these viruses in their bat hosts. IMPORTANCE Bats are a natural reservoir for various viruses that rarely cause clinical symptoms in bats but are dangerous zoonotic pathogens, like Ebola or rabies virus. It has been hypothesized that the interferon system might play a key role in controlling viral replication in bats. We speculate that the interferon-induced Mx proteins might be key antiviral factors of bats and have coevolved with bat-borne viruses. This study evaluated for the first time a large set of bat Mx1 proteins spanning three major bat families for their antiviral potential, including activity

  5. Activation of Nrf2 Signaling Augments Vesicular Stomatitis Virus Oncolysis via Autophagy-Driven Suppression of Antiviral Immunity.

    Science.gov (United States)

    Olagnier, David; Lababidi, Rassin R; Hadj, Samar Bel; Sze, Alexandre; Liu, Yiliu; Naidu, Sharadha Dayalan; Ferrari, Matteo; Jiang, Yuan; Chiang, Cindy; Beljanski, Vladimir; Goulet, Marie-Line; Knatko, Elena V; Dinkova-Kostova, Albena T; Hiscott, John; Lin, Rongtuan

    2017-08-02

    Oncolytic viruses (OVs) offer a promising therapeutic approach to treat multiple types of cancer. In this study, we show that the manipulation of the antioxidant network via transcription factor Nrf2 augments vesicular stomatitis virus Δ51 (VSVΔ51) replication and sensitizes cancer cells to viral oncolysis. Activation of Nrf2 signaling by the antioxidant compound sulforaphane (SFN) leads to enhanced VSVΔ51 spread in OV-resistant cancer cells and improves the therapeutic outcome in different murine syngeneic and xenograft tumor models. Chemoresistant A549 lung cancer cells that display constitutive dominant hyperactivation of Nrf2 signaling are particularly vulnerable to VSVΔ51 oncolysis. Mechanistically, enhanced Nrf2 signaling stimulated viral replication in cancer cells and disrupted the type I IFN response via increased autophagy. This study reveals a previously unappreciated role for Nrf2 in the regulation of autophagy and the innate antiviral response that complements the therapeutic potential of VSV-directed oncolysis against multiple types of OV-resistant or chemoresistant cancer. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  6. Inhibition of CRM1-mediated nuclear export of influenza A nucleoprotein and nuclear export protein as a novel target for antiviral drug development

    Energy Technology Data Exchange (ETDEWEB)

    Chutiwitoonchai, Nopporn; Mano, Takafumi; Kakisaka, Michinori; Sato, Hirotaka [Viral Infectious Disease Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kondoh, Yasumitsu; Osada, Hiroyuki [Chemical Biology Research Group, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kotani, Osamu; Yokoyama, Masaru; Sato, Hironori [Laboratory of Viral Genomics, Pathogen Genomics Center, National Institute of Infectious Diseases, 4-7-1 Gakuen, Musashimurayama, Tokyo 208-0011 (Japan); Aida, Yoko, E-mail: aida@riken.jp [Viral Infectious Disease Unit, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2017-07-15

    An anti-influenza compound, DP2392-E10 based on inhibition of the nuclear export function of the viral nucleoprotein-nuclear export signal 3 (NP-NES3) domain was successfully identified by our previous high-throughput screening system. Here, we demonstrated that DP2392-E10 exerts its antiviral effect by inhibiting replication of a broad range of influenza A subtypes. In regard to the molecular mechanism, we revealed that DP2392-E10 inhibits nuclear export of both viral NP and nuclear export protein (NEP). More specifically, in vitro pull-down assays revealed that DP2392-E10 directly binds cellular CRM1, which mediates nuclear export of NP and NEP. In silico docking suggested that DP2392-E10 binds at a region close to the HEAT9 and HEAT10 domains of CRM1. Together, these results indicate that the CRM1-mediated nuclear export function of influenza virus represents a new potential target for antiviral drug development, and also provide a core structure for a novel class of inhibitors that target this function. - Highlights: •DP2392-E10 inhibits replication of a broad range of influenza A subtypes. •DP2392-E10 inhibits nuclear exports of NP and NEP via their NP-NES3 and NEP-NES2 domains, respectively. •DP2392-E10 is predicted to directly bind CRM1 in the region near the HEAT9 and HEAT10 repeats.

  7. Inhibition of CRM1-mediated nuclear export of influenza A nucleoprotein and nuclear export protein as a novel target for antiviral drug development

    International Nuclear Information System (INIS)

    Chutiwitoonchai, Nopporn; Mano, Takafumi; Kakisaka, Michinori; Sato, Hirotaka; Kondoh, Yasumitsu; Osada, Hiroyuki; Kotani, Osamu; Yokoyama, Masaru; Sato, Hironori; Aida, Yoko

    2017-01-01

    An anti-influenza compound, DP2392-E10 based on inhibition of the nuclear export function of the viral nucleoprotein-nuclear export signal 3 (NP-NES3) domain was successfully identified by our previous high-throughput screening system. Here, we demonstrated that DP2392-E10 exerts its antiviral effect by inhibiting replication of a broad range of influenza A subtypes. In regard to the molecular mechanism, we revealed that DP2392-E10 inhibits nuclear export of both viral NP and nuclear export protein (NEP). More specifically, in vitro pull-down assays revealed that DP2392-E10 directly binds cellular CRM1, which mediates nuclear export of NP and NEP. In silico docking suggested that DP2392-E10 binds at a region close to the HEAT9 and HEAT10 domains of CRM1. Together, these results indicate that the CRM1-mediated nuclear export function of influenza virus represents a new potential target for antiviral drug development, and also provide a core structure for a novel class of inhibitors that target this function. - Highlights: •DP2392-E10 inhibits replication of a broad range of influenza A subtypes. •DP2392-E10 inhibits nuclear exports of NP and NEP via their NP-NES3 and NEP-NES2 domains, respectively. •DP2392-E10 is predicted to directly bind CRM1 in the region near the HEAT9 and HEAT10 repeats.

  8. Inhibition of CRM1-mediated nuclear export of influenza A nucleoprotein and nuclear export protein as a novel target for antiviral drug development.

    Science.gov (United States)

    Chutiwitoonchai, Nopporn; Mano, Takafumi; Kakisaka, Michinori; Sato, Hirotaka; Kondoh, Yasumitsu; Osada, Hiroyuki; Kotani, Osamu; Yokoyama, Masaru; Sato, Hironori; Aida, Yoko

    2017-07-01

    An anti-influenza compound, DP2392-E10 based on inhibition of the nuclear export function of the viral nucleoprotein-nuclear export signal 3 (NP-NES3) domain was successfully identified by our previous high-throughput screening system. Here, we demonstrated that DP2392-E10 exerts its antiviral effect by inhibiting replication of a broad range of influenza A subtypes. In regard to the molecular mechanism, we revealed that DP2392-E10 inhibits nuclear export of both viral NP and nuclear export protein (NEP). More specifically, in vitro pull-down assays revealed that DP2392-E10 directly binds cellular CRM1, which mediates nuclear export of NP and NEP. In silico docking suggested that DP2392-E10 binds at a region close to the HEAT9 and HEAT10 domains of CRM1. Together, these results indicate that the CRM1-mediated nuclear export function of influenza virus represents a new potential target for antiviral drug development, and also provide a core structure for a novel class of inhibitors that target this function. Copyright © 2017 Elsevier Inc. All rights reserved.

  9. Middle East Respiratory Coronavirus Accessory Protein 4a Inhibits PKR-Mediated Antiviral Stress Responses

    NARCIS (Netherlands)

    Rabouw, Huib H; Langereis, Martijn A; Knaap, Robert C M; Dalebout, Tim J; Canton, Javier; Sola, Isabel; Enjuanes, Luis; Bredenbeek, Peter J; Kikkert, Marjolein; de Groot, Raoul J; van Kuppeveld, Frank J M

    2016-01-01

    Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe respiratory infections that can be life-threatening. To establish an infection and spread, MERS-CoV, like most other viruses, must navigate through an intricate network of antiviral host responses. Besides the well-known type I

  10. NEOGLYCOPROTEINS AS CARRIERS FOR ANTIVIRAL DRUGS - SYNTHESIS AND ANALYSIS OF PROTEIN DRUG CONJUGATES

    NARCIS (Netherlands)

    Molema, Grietje; Jansen, Robert W.; Visser, Jan; Herdewijn, Piet; Moolenaar, Frits; Meijer, Dirk K.F.

    In order to investigate whether neoglycoproteins can potentially act as carriers for targeting of antiviral drugs to certain cell types in the body, various neoglycoproteins were synthesized using thiophosgene-activated p-aminophenyl sugar derivatives. These neoglycoproteins were conjugated with the

  11. Anchoring Proteins as Regulators of Signaling Pathways

    Science.gov (United States)

    Perino, Alessia; Ghigo, Alessandra; Scott, John D.; Hirsch, Emilio

    2012-01-01

    Spatial and temporal organization of signal transduction is coordinated through the segregation of signaling enzymes in selected cellular compartments. This highly evolved regulatory mechanism ensures the activation of selected enzymes only in the vicinity of their target proteins. In this context, cAMP-responsive triggering of protein kinase A is modulated by a family of scaffold proteins referred to as A-kinase anchoring proteins. A-kinase anchoring proteins form the core of multiprotein complexes and enable simultaneous but segregated cAMP signaling events to occur in defined cellular compartments. In this review we will focus on the description of A-kinase anchoring protein function in the regulation of cardiac physiopathology. PMID:22859670

  12. Antiviral RNA silencing initiated in the absence of RDE-4, a double-stranded RNA binding protein, in Caenorhabditis elegans.

    Science.gov (United States)

    Guo, Xunyang; Zhang, Rui; Wang, Jeffrey; Lu, Rui

    2013-10-01

    Small interfering RNAs (siRNAs) processed from double-stranded RNA (dsRNA) of virus origins mediate potent antiviral defense through a process referred to as RNA interference (RNAi) or RNA silencing in diverse organisms. In the simple invertebrate Caenorhabditis elegans, the RNAi process is initiated by a single Dicer, which partners with the dsRNA binding protein RDE-4 to process dsRNA into viral siRNAs (viRNAs). Notably, in C. elegans this RNA-directed viral immunity (RDVI) also requires a number of worm-specific genes for its full antiviral potential. One such gene is rsd-2 (RNAi spreading defective 2), which was implicated in RDVI in our previous studies. In the current study, we first established an antiviral role by showing that rsd-2 null mutants permitted higher levels of viral RNA accumulation, and that this enhanced viral susceptibility was reversed by ectopic expression of RSD-2. We then examined the relationship of rsd-2 with other known components of RNAi pathways and established that rsd-2 functions in a novel pathway that is independent of rde-4 but likely requires the RNA-dependent RNA polymerase RRF-1, suggesting a critical role for RSD-2 in secondary viRNA biogenesis, likely through coordinated action with RRF-1. Together, these results suggest that RDVI in the single-Dicer organism C. elegans depends on the collective actions of both RDE-4-dependent and RDE-4-independent mechanisms to produce RNAi-inducing viRNAs. Our study reveals, for the first time, a novel siRNA-producing mechanism in C. elegans that bypasses the need for a dsRNA-binding protein.

  13. SH2/SH3 signaling proteins.

    Science.gov (United States)

    Schlessinger, J

    1994-02-01

    SH2 and SH3 domains are small protein modules that mediate protein-protein interactions in signal transduction pathways that are activated by protein tyrosine kinases. SH2 domains bind to short phosphotyrosine-containing sequences in growth factor receptors and other phosphoproteins. SH3 domains bind to target proteins through sequences containing proline and hydrophobic amino acids. SH2 and SH3 domain containing proteins, such as Grb2 and phospholipase C gamma, utilize these modules in order to link receptor and cytoplasmic protein tyrosine kinases to the Ras signaling pathway and to phosphatidylinositol hydrolysis, respectively. The three-dimensional structures of several SH2 and SH3 domains have been determined by NMR and X-ray crystallography, and the molecular basis of their specificity is beginning to be unveiled.

  14. Respiratory Syncytial Virus Nonstructural Proteins Upregulate SOCS1 and SOCS3 in the Different Manner from Endogenous IFN Signaling

    Directory of Open Access Journals (Sweden)

    Junwen Zheng

    2015-01-01

    Full Text Available Respiratory syncytial virus (RSV infection upregulates genes of the suppressor of cytokine signaling (SOCS family, which utilize a feedback loop to inhibit type I interferon dependent antiviral signaling pathway. Here, we reconstituted RSV nonstructural (NS protein expression plasmids (pNS1, pNS2, and pNS1/2 and tested whether NS1 or NS2 would trigger SOCS1 and SOCS3 protein expression. These NS proteins inhibited interferon- (IFN- α signaling through a mechanism involving the induction of SOCS1 and SOCS3, which appeared to be different from autocrine IFN dependent. NS1 induced both SOCS1 and SOCS3 upregulation, while NS2 only induced SOCS1 expression. The induced expression of SOCS1 and SOCS3 preceded endogenous IFN-signaling activation and inhibited the IFN-inducible antiviral response as well as chemokine induction. Treatments with INF-α and NS proteins both induced SOCS1 expression; however, they had opposing effects on IFN-α-dependent antiviral gene expression. Our results indicate that NS1 and NS2, which induce the expression of SOCS1 or SOCS3, might represent an independent pathway of stimulating endogenous IFN signaling.

  15. Proteolytic activation of the SARS-coronavirus spike protein: cutting enzymes at the cutting edge of antiviral research.

    Science.gov (United States)

    Simmons, Graham; Zmora, Pawel; Gierer, Stefanie; Heurich, Adeline; Pöhlmann, Stefan

    2013-12-01

    The severe acute respiratory syndrome (SARS) pandemic revealed that zoonotic transmission of animal coronaviruses (CoV) to humans poses a significant threat to public health and warrants surveillance and the development of countermeasures. The activity of host cell proteases, which cleave and activate the SARS-CoV spike (S) protein, is essential for viral infectivity and constitutes a target for intervention. However, the identities of the proteases involved have been unclear. Pioneer studies identified cathepsins and type II transmembrane serine proteases as cellular activators of SARS-CoV and demonstrated that several emerging viruses might exploit these enzymes to promote their spread. Here, we will review the proteolytic systems hijacked by SARS-CoV for S protein activation, we will discuss their contribution to viral spread in the host and we will outline antiviral strategies targeting these enzymes. This paper forms part of a series of invited articles in Antiviral Research on "From SARS to MERS: 10years of research on highly pathogenic human coronaviruses.'' Copyright © 2013 Elsevier B.V. All rights reserved.

  16. NSs Virulence Factor of Rift Valley Fever Virus Engages the F-Box Proteins FBXW11 and β-TRCP1 To Degrade the Antiviral Protein Kinase PKR.

    Science.gov (United States)

    Kainulainen, Markus; Lau, Simone; Samuel, Charles E; Hornung, Veit; Weber, Friedemann

    2016-07-01

    Rift Valley fever virus (RVFV, family Bunyaviridae, genus Phlebovirus) is a relevant pathogen of both humans and livestock in Africa. The nonstructural protein NSs is a major virulence factor known to suppress the type I interferon (IFN) response by inhibiting host cell transcription and by proteasomal degradation of a major antiviral IFN effector, the translation-inhibiting protein kinase PKR. Here, we identified components of the modular SCF (Skp1, Cul1, F-box protein)-type E3 ubiquitin ligases as mediators of PKR destruction by NSs. Small interfering RNAs (siRNAs) against the conserved SCF subunit Skp1 protected PKR from NSs-mediated degradation. Consequently, RVFV replication was severely reduced in Skp1-depleted cells when PKR was present. SCF complexes have a variable F-box protein subunit that determines substrate specificity for ubiquitination. We performed an siRNA screen for all (about 70) human F-box proteins and found FBXW11 to be involved in PKR degradation. The partial stabilization of PKR by FBXW11 depletion upregulated PKR autophosphorylation and phosphorylation of the PKR substrate eIF2α and caused a shutoff of host cell protein synthesis in RVFV-infected cells. To maximally protect PKR from the action of NSs, knockdown of structurally and functionally related FBXW1 (also known as β-TRCP1), in addition to FBXW11 deletion, was necessary. Consequently, NSs was found to interact with both FBXW11 and β-TRCP1. Thus, NSs eliminates the antiviral kinase PKR by recruitment of SCF-type E3 ubiquitin ligases containing FBXW11 and β-TRCP1 as substrate recognition subunits. This antagonism of PKR by NSs is essential for efficient RVFV replication in mammalian cells. Rift Valley fever virus is a pathogen of humans and animals that has the potential to spread from Africa and the Arabian Peninsula to other regions. A major virulence mechanism is the proteasomal degradation of the antiviral kinase PKR by the viral protein NSs. Here, we demonstrate that NSs

  17. Signal peptides and protein localization prediction

    DEFF Research Database (Denmark)

    Nielsen, Henrik

    2005-01-01

    In 1999, the Nobel prize in Physiology or Medicine was awarded to Gunther Blobel “for the discovery that proteins have intrinsic signals that govern their transport and localization in the cell”. Since the subcellular localization of a protein is an important clue to its function, the characteriz...

  18. Protein cysteine oxidation in redox signaling

    DEFF Research Database (Denmark)

    Forman, Henry Jay; Davies, Michael J; Krämer, Anna C

    2017-01-01

    Oxidation of critical signaling protein cysteines regulated by H2O2 has been considered to involve sulfenic acid (RSOH) formation. RSOH may subsequently form either a sulfenyl amide (RSNHR') with a neighboring amide, or a mixed disulfide (RSSR') with another protein cysteine or glutathione. Previ...

  19. Structure and Function of the Non-Structural Protein of Dengue Virus and its Applications in Antiviral Therapy.

    Science.gov (United States)

    Xie, Qian; Zhang, Bao; Yu, JianHai; Wu, Qinghua; Yang, Fangji; Cao, Hong; Zhao, Wei

    2017-01-01

    Dengue fever, a type of global and tropical infectious disease, and its prevention has become a challenging issue worldwide. Antibody-dependent enhancement effects and the virus pathogenic mechanism have not yet been fully elucidated, hindering the development of dengue fever prevention and suitable drug treatment. There is currently no specific prevention and therapy in clinical trials, however, in recent years, studies have focused on the pathogenesis and treatment of dengue. Research focusing on dengue virus nonstructural protein in special drugs for the prevention and control of dengue fever is a new progress leading to improved understanding regarding the prevention and control of dengue fever and suitable drugs for the treatment. The main challenges regarding the structure of dengue virus nonstructural protein and the drugs for antiviral therapy are summarized in this paper.

  20. Protein Translation and Signaling in Human Eosinophils

    Directory of Open Access Journals (Sweden)

    Stephane Esnault

    2017-09-01

    Full Text Available We have recently reported that, unlike IL-5 and GM-CSF, IL-3 induces increased translation of a subset of mRNAs. In addition, we have demonstrated that Pin1 controls the activity of mRNA binding proteins, leading to enhanced mRNA stability, GM-CSF protein production and prolonged eosinophil (EOS survival. In this review, discussion will include an overview of cap-dependent protein translation and its regulation by intracellular signaling pathways. We will address the more general process of mRNA post-transcriptional regulation, especially regarding mRNA binding proteins, which are critical effectors of protein translation. Furthermore, we will focus on (1 the roles of IL-3-driven sustained signaling on enhanced protein translation in EOS, (2 the mechanisms regulating mRNA binding proteins activity in EOS, and (3 the potential targeting of IL-3 signaling and the signaling leading to mRNA binding activity changes to identify therapeutic targets to treat EOS-associated diseases.

  1. Initiation of Antiviral B Cell Immunity Relies on Innate Signals from Spatially Positioned NKT Cells.

    Science.gov (United States)

    Gaya, Mauro; Barral, Patricia; Burbage, Marianne; Aggarwal, Shweta; Montaner, Beatriz; Warren Navia, Andrew; Aid, Malika; Tsui, Carlson; Maldonado, Paula; Nair, Usha; Ghneim, Khader; Fallon, Padraic G; Sekaly, Rafick-Pierre; Barouch, Dan H; Shalek, Alex K; Bruckbauer, Andreas; Strid, Jessica; Batista, Facundo D

    2018-01-25

    B cells constitute an essential line of defense from pathogenic infections through the generation of class-switched antibody-secreting cells (ASCs) in germinal centers. Although this process is known to be regulated by follicular helper T (TfH) cells, the mechanism by which B cells initially seed germinal center reactions remains elusive. We found that NKT cells, a population of innate-like T lymphocytes, are critical for the induction of B cell immunity upon viral infection. The positioning of NKT cells at the interfollicular areas of lymph nodes facilitates both their direct priming by resident macrophages and the localized delivery of innate signals to antigen-experienced B cells. Indeed, NKT cells secrete an early wave of IL-4 and constitute up to 70% of the total IL-4-producing cells during the initial stages of infection. Importantly, the requirement of this innate immunity arm appears to be evolutionarily conserved because early NKT and IL-4 gene signatures also positively correlate with the levels of neutralizing antibodies in Zika-virus-infected macaques. In conclusion, our data support a model wherein a pre-TfH wave of IL-4 secreted by interfollicular NKT cells triggers the seeding of germinal center cells and serves as an innate link between viral infection and B cell immunity. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  2. Elevation of intact and proteolytic fragments of acute phase proteins constitutes the earliest systemic antiviral response in HIV-1 infection.

    Directory of Open Access Journals (Sweden)

    Holger B Kramer

    2010-05-01

    Full Text Available The earliest immune responses activated in acute human immunodeficiency virus type 1 infection (AHI exert a critical influence on subsequent virus spread or containment. During this time frame, components of the innate immune system such as macrophages and DCs, NK cells, beta-defensins, complement and other anti-microbial factors, which have all been implicated in modulating HIV infection, may play particularly important roles. A proteomics-based screen was performed on a cohort from whom samples were available at time points prior to the earliest positive HIV detection. The ability of selected factors found to be elevated in the plasma during AHI to inhibit HIV-1 replication was analyzed using in vitro PBMC and DC infection models. Analysis of unique plasma donor panels spanning the eclipse and viral expansion phases revealed very early alterations in plasma proteins in AHI. Induction of acute phase protein serum amyloid A (A-SAA occurred as early as 5-7 days prior to the first detection of plasma viral RNA, considerably prior to any elevation in systemic cytokine levels. Furthermore, a proteolytic fragment of alpha-1-antitrypsin (AAT, termed virus inhibitory peptide (VIRIP, was observed in plasma coincident with viremia. Both A-SAA and VIRIP have anti-viral activity in vitro and quantitation of their plasma levels indicated that circulating concentrations are likely to be within the range of their inhibitory activity. Our results provide evidence for a first wave of host anti-viral defense occurring in the eclipse phase of AHI prior to systemic activation of other immune responses. Insights gained into the mechanism of action of acute-phase reactants and other innate molecules against HIV and how they are induced could be exploited for the future development of more efficient prophylactic vaccine strategies.

  3. Detection of the antiviral activity of epicatechin isolated from Salacia crassifolia (Celastraceae) against Mayaro virus based on protein C homology modelling and virtual screening.

    Science.gov (United States)

    Ferreira, P G; Ferraz, A C; Figueiredo, J E; Lima, C F; Rodrigues, V G; Taranto, A G; Ferreira, J M S; Brandão, G C; Vieira-Filho, S A; Duarte, L P; de Brito Magalhães, C L; de Magalhães, J C

    2018-02-24

    Mayaro fever, caused by Mayaro virus (MAYV) is a sub-lethal disease with symptoms that are easily confused with those of dengue fever, except for polyarthralgia, which may culminate in physical incapacitation. Recently, outbreaks of MAYV have been documented in metropolitan areas, and to date, there is no therapy or vaccine available. Moreover, there is no information regarding the three-dimensional structure of the viral proteins of MAYV, which is important in the search for antivirals. In this work, we constructed a three-dimensional model of protein C of MAYV by homology modelling, and this was employed in a manner similar to that of receptors in virtual screening studies to evaluate 590 molecules as prospective antiviral agents. In vitro bioassays were utilized to confirm the potential antiviral activity of the flavonoid epicatechin isolated from Salacia crassifolia (Celastraceae). The virtual screening showed that six flavonoids were promising ligands for protein C. The bioassays showed potent antiviral action of epicatechin, which protected the cells from almost all of the effects of viral infection. An effective concentration (EC 50 ) of 0.247 μmol/mL was observed with a selectivity index (SI) of 7. The cytotoxicity assay showed that epicatechin has low toxicity, with a 50% cytotoxic concentration (CC 50 ) greater than 1.723 µmol/mL. Epicatechin was found to be twice as potent as the reference antiviral ribavirin. Furthermore, a replication kinetics assay showed a strong inhibitory effect of epicatechin on MAYV growth, with a reduction of at least four logs in virus production. Our results indicate that epicatechin is a promising candidate for further testing as an antiviral agent against Mayaro virus and other alphaviruses.

  4. Depletion of elongation initiation factor 4E binding proteins by CRISPR/Cas9 genome editing enhances antiviral response in porcine cells

    Science.gov (United States)

    Type I interferons (IFN) are key mediators of the innate antiviral response in mammalian cells. Elongation initiation factor 4E binding proteins (4E-BPs) are translational controllers of interferon regulatory factor 7 (IRF7), the master regulator of IFN transcription. The role of 4EBPs in the negat...

  5. Myxoma Virus dsRNA Binding Protein M029  Inhibits the Type I IFN-Induced Antiviral State in a  Highly Species-Specific Fashion.

    Science.gov (United States)

    Rahman, Masmudur M; McFadden, Grant

    2017-02-02

    Myxoma virus (MYXV) is Leporipoxvirus that possesses a specific rabbit-restricted host tropism but exhibits a much broader  cellular host range in cultured cells. MYXV is able to efficiently  block all aspects of the type I interferon (IFN)-induced  antiviral  state  in rabbit cells, partially in  human  cells  and  very  poorly  in  mouse  cells.  The mechanism(s) of this species-specific inhibition of  type I IFN-induced antiviral state is not well understood. Here we demonstrate that MYXV encoded  protein  M029, a truncated relative of the vaccinia virus (VACV) E3 double-stranded RNA (dsRNA)  binding  protein  that  inhibits  protein  kinase  R (PKR),  can  also  antagonize the type I IFN-induced  antiviral state in a highly species-specific manner. In cells pre-treated with type I IFN prior to  infection,  MYXV  exploits  M029  to  overcome  the  induced  antiviral  state completely in rabbit cells,  partially  in  human  cells,  but  not at all in mouse cells. However, in cells pre-infected with MYXV,  IFN-induced  signaling  is fully  inhibited  even  in the  absence  of M029 in cells from all three species,  suggesting  that  other  MYXV  protein(s)  apart  from  M029  block  IFN  signaling  in  a  speciesindependent  manner.  We  also  show  that  the  antiviral  state  induced in rabbit, human or mouse cells  by  type  I IFN  can  inhibit M029-knockout MYXV even when PKR is genetically knocked-out, suggesting  that  M029  targets  other  host  proteins  for  this  antiviral state inhibition. Thus, the MYXV  dsRNA  binding  protein  M029  not  only  antagonizes  PKR  from  multiple  species  but  also blocks the  type I IFN antiviral state independently of PKR in a highly species-specific fashion.

  6. Stop codons in the hepatitis B surface proteins are enriched during antiviral therapy and are associated with host cell apoptosis

    International Nuclear Information System (INIS)

    Colledge, Danielle; Soppe, Sally; Yuen, Lilly; Selleck, Lucy; Walsh, Renae; Locarnini, Stephen; Warner, Nadia

    2017-01-01

    Premature stop codons in the hepatitis B virus (HBV) surface protein can be associated with nucleos(t)ide analogue resistance due to overlap of the HBV surface and polymerase genes. The aim of this study was to determine the effect of the replication of three common surface stop codon variants on the hepatocyte. Cell lines were transfected with infectious HBV clones encoding surface stop codons rtM204I/sW196*, rtA181T/sW172*, rtV191I/sW182*, and a panel of substitutions in the surface proteins. HBsAg was measured by Western blotting. Proliferation and apoptosis were measured using flow cytometry. All three surface stop codon variants were defective in HBsAg secretion. Cells transfected with these variants were less proliferative and had higher levels of apoptosis than those transfected with variants that did not encode surface stop codons. The most cytopathic variant was rtM204I/sW196*. Replication of HBV encoding surface stop codons was toxic to the cell and promoted apoptosis, exacerbating disease progression. - Highlights: •Under normal circumstances, HBV replication is not cytopathic. •Premature stop codons in the HBV surface protein can be selected and enriched during nucleos(t)ide analogue therapy. •Replication of these variants can be cytopathic to the cell and promote apoptosis. •Inadequate antiviral therapy may actually promote disease progression.

  7. Stop codons in the hepatitis B surface proteins are enriched during antiviral therapy and are associated with host cell apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Colledge, Danielle; Soppe, Sally; Yuen, Lilly; Selleck, Lucy; Walsh, Renae; Locarnini, Stephen, E-mail: stephen.locarnini@mh.org.au; Warner, Nadia

    2017-01-15

    Premature stop codons in the hepatitis B virus (HBV) surface protein can be associated with nucleos(t)ide analogue resistance due to overlap of the HBV surface and polymerase genes. The aim of this study was to determine the effect of the replication of three common surface stop codon variants on the hepatocyte. Cell lines were transfected with infectious HBV clones encoding surface stop codons rtM204I/sW196*, rtA181T/sW172*, rtV191I/sW182*, and a panel of substitutions in the surface proteins. HBsAg was measured by Western blotting. Proliferation and apoptosis were measured using flow cytometry. All three surface stop codon variants were defective in HBsAg secretion. Cells transfected with these variants were less proliferative and had higher levels of apoptosis than those transfected with variants that did not encode surface stop codons. The most cytopathic variant was rtM204I/sW196*. Replication of HBV encoding surface stop codons was toxic to the cell and promoted apoptosis, exacerbating disease progression. - Highlights: •Under normal circumstances, HBV replication is not cytopathic. •Premature stop codons in the HBV surface protein can be selected and enriched during nucleos(t)ide analogue therapy. •Replication of these variants can be cytopathic to the cell and promote apoptosis. •Inadequate antiviral therapy may actually promote disease progression.

  8. ORF7-encoded accessory protein 7a of feline infectious peritonitis virus as a counteragent against IFN-α-induced antiviral response.

    Science.gov (United States)

    Dedeurwaerder, Annelike; Olyslaegers, Dominique A J; Desmarets, Lowiese M B; Roukaerts, Inge D M; Theuns, Sebastiaan; Nauwynck, Hans J

    2014-02-01

    The type I IFN-mediated immune response is the first line of antiviral defence. Coronaviruses, like many other viruses, have evolved mechanisms to evade this innate response, ensuring their survival. Several coronavirus accessory genes play a central role in these pathways, but for feline coronaviruses this has never to our knowledge been studied. As it has been demonstrated previously that ORF7 is essential for efficient replication in vitro and virulence in vivo of feline infectious peritonitis virus (FIPV), the role of this ORF in the evasion of the IFN-α antiviral response was investigated. Deletion of ORF7 from FIPV strain 79-1146 (FIPV-Δ7) rendered the virus more susceptible to IFN-α treatment. Given that ORF7 encodes two proteins, 7a and 7b, it was further explored which of these proteins is active in this mechanism. Providing 7a protein in trans rescued the mutant FIPV-Δ7 from IFN sensitivity, which was not achieved by addition of 7b protein. Nevertheless, addition of protein 7a to FIPV-Δ3Δ7, a FIPV mutant deleted in both ORF3 and ORF7, could no longer increase the replication capacity of this mutant in the presence of IFN. These results indicate that FIPV 7a protein is a type I IFN antagonist and protects the virus from the antiviral state induced by IFN, but it needs the presence of ORF3-encoded proteins to exert its antagonistic function.

  9. Complementary roles of Fas-associated death domain (FADD) and receptor interacting protein kinase-3 (RIPK3) in T-cell homeostasis and antiviral immunity.

    Science.gov (United States)

    Lu, Jennifer V; Weist, Brian M; van Raam, Bram J; Marro, Brett S; Nguyen, Long V; Srinivas, Prathna; Bell, Bryan D; Luhrs, Keith A; Lane, Thomas E; Salvesen, Guy S; Walsh, Craig M

    2011-09-13

    Caspase-8 (casp8) is required for extrinsic apoptosis, and mice deficient in casp8 fail to develop and die in utero while ultimately failing to maintain the proliferation of T cells, B cells, and a host of other cell types. Paradoxically, these failures are not caused by a defect in apoptosis, but by a presumed proliferative function of this protease. Indeed, following mitogenic stimulation, T cells lacking casp8 or its adaptor protein FADD (Fas-associated death domain protein) develop a hyperautophagic morphology, and die a programmed necrosis-like death process termed necroptosis. Recent studies have demonstrated that receptor-interacting protein kinases (RIPKs) RIPK1 and RIPK3 together facilitate TNF-induced necroptosis, but the precise role of RIPKs in the demise of T cells lacking FADD or casp8 activity is unknown. Here we demonstrate that RIPK3 and FADD have opposing and complementary roles in promoting T-cell clonal expansion and homeostasis. We show that the defective proliferation of T cells bearing an interfering form of FADD (FADDdd) is rescued by crossing with RIPK3(-/-) mice, although such rescue ultimately leads to lymphadenopathy. Enhanced recovery of these double-mutant T cells following stimulation demonstrates that FADD, casp8, and RIPK3 are all essential for clonal expansion, contraction, and antiviral responses. Finally, we demonstrate that caspase-mediated cleavage of RIPK1-containing necrosis inducing complexes (necrosomes) is sufficient to prevent necroptosis in the face of death receptor signaling. These studies highlight the "two-faced" nature of casp8 activity, promoting clonal expansion in some situations and apoptotic demise in others.

  10. Rational design of highly potent HIV-1 fusion inhibitory proteins: Implication for developing antiviral therapeutics

    International Nuclear Information System (INIS)

    Ni Ling; Gao, George F.; Tien Po

    2005-01-01

    Recombinant protein containing one heptad-repeat 1 (HR1) segment and one HR2 segment of the HIV-1 gp41 (HR1-HR2) has been shown to fold into thermally stable six-helix bundle, representing the fusogenic core of gp41. In this study, we have used the fusogenic core as a scaffold to design HIV-1 fusion inhibitory proteins by linking another HR1 to the C terminus of HR1-HR2 (HR121) or additional HR2 to the N terminus of HR1-HR2 (HR212). Both recombinant proteins could be abundantly and solubly expressed and easily purified, exhibiting high stability and potent inhibitory activity on HIV-1 fusion with IC 50 values of 16.2 ± 2.8 and 2.8 ± 0.63 nM, respectively. These suggest that these rationally designed proteins can be further developed as novel anti-HIV-1 therapeutics

  11. Intracellular expression of IRF9 Stat fusion protein overcomes the defective Jak-Stat signaling and inhibits HCV RNA replication

    Directory of Open Access Journals (Sweden)

    Balart Luis A

    2010-10-01

    Full Text Available Abstract Interferon alpha (IFN-α binds to a cell surface receptor that activates the Jak-Stat signaling pathway. A critical component of this pathway is the translocation of interferon stimulated gene factor 3 (a complex of three proteins Stat1, Stat2 and IRF9 to the nucleus to activate antiviral genes. A stable sub-genomic replicon cell line resistant to IFN-α was developed in which the nuclear translocation of Stat1 and Stat2 proteins was prevented due to the lack of phosphorylation; whereas the nuclear translocation of IRF9 protein was not affected. In this study, we sought to overcome defective Jak-Stat signaling and to induce an antiviral state in the IFN-α resistant replicon cell line by developing a chimera IRF9 protein fused with the trans activating domain (TAD of either a Stat1 (IRF9-S1C or Stat2 (IRF9-S2C protein. We show here that intracellular expression of fusion proteins using the plasmid constructs of either IRF9-S1C or IRF9-S2C, in the IFN-α resistant cells, resulted in an increase in Interferon Stimulated Response Element (ISRE luciferase promoter activity and significantly induced HLA-1 surface expression. Moreover, we show that transient transfection of IRF9-S1C or IRF9-S2C plasmid constructs into IFN-α resistant replicon cells containing sub-genomic HCV1b and HCV2a viruses resulted in an inhibition of viral replication and viral protein expression independent of IFN-α treatment. The results of this study indicate that the recombinant fusion proteins of IRF9-S1C, IRF9-S2C alone, or in combination, have potent antiviral properties against the HCV in an IFN-α resistant cell line with a defective Jak-Stat signaling.

  12. Lopinavir up-regulates expression of the antiviral protein ribonuclease L in human papillomavirus-positive cervical carcinoma cells.

    Science.gov (United States)

    Batman, Gavin; Oliver, Anthony W; Zehbe, Ingeborg; Richard, Christina; Hampson, Lynne; Hampson, Ian N

    2011-01-01

    We have previously shown that the HIV protease inhibitor lopinavir has selective toxicity against human papillomavirus (HPV)-positive cervical carcinoma cells via an unknown mechanism. SiHa cervical carcinoma cells were stably transfected with the proteasome sensor vector pZsProSensor-1 to confirm lopinavir inhibits the proteasome in these cells. The Panorama Xpress profiler 725 antibody array was then used to analyse specific changes in protein expression in lopinavir-treated versus control untreated SiHa cells followed by PCR and western blotting. Colorimetric growth assays of lopinavir-treated E6/E7 immortalised versus control human keratinocytes were performed. Targeted small interfering RNA gene silencing followed by growth assay comparison of lopinavir-treated/untreated SiHa cells was also used. Lopinavir induced an increase in the fluorescence of pZsProSensor-1 transfected SiHa cells, indicative of proteasomal inhibition. Ribonuclease L (RNASEL) protein was shown to be up-regulated in lopinavir-treated SiHa cells, which was confirmed by PCR and western blot. Targeted silencing of RNASEL reduced the sensitivity of SiHa cells to lopinavir. Selective toxicity against E6/E7 immortalised keratinocytes versus control cells was also seen with lopinavir and was associated with up-regulated RNASEL expression. These data are consistent with the toxicity of lopinavir against HPV-positive cervical carcinoma cells being related to its ability to block viral proteasome activation and induce an up-regulation of the antiviral protein RNASEL. This is supported by the drug's selective toxicity and up-regulation of RNASEL in E6/E7 immortalised keratinocytes combined with the increased resistance to lopinavir observed in SiHa cells following silencing of RNASEL gene expression.

  13. Human Antiviral Protein IFIX Suppresses Viral Gene Expression during Herpes Simplex Virus 1 (HSV-1) Infection and Is Counteracted by Virus-induced Proteasomal Degradation.

    Science.gov (United States)

    Crow, Marni S; Cristea, Ileana M

    2017-04-01

    The interferon-inducible protein X (IFIX), a member of the PYHIN family, was recently recognized as an antiviral factor against infection with herpes simplex virus 1 (HSV-1). IFIX binds viral DNA upon infection and promotes expression of antiviral cytokines. How IFIX exerts its host defense functions and whether it is inhibited by the virus remain unknown. Here, we integrated live cell microscopy, proteomics, IFIX domain characterization, and molecular virology to investigate IFIX regulation and antiviral functions during HSV-1 infection. We find that IFIX has a dynamic localization during infection that changes from diffuse nuclear and nucleoli distribution in uninfected cells to discrete nuclear puncta early in infection. This is rapidly followed by a reduction in IFIX protein levels. Indeed, using immunoaffinity purification and mass spectrometry, we define IFIX interactions during HSV-1 infection, finding an association with a proteasome subunit and proteins involved in ubiquitin-proteasome processes. Using synchronized HSV-1 infection, microscopy, and proteasome-inhibition experiments, we demonstrate that IFIX co-localizes with nuclear proteasome puncta shortly after 3 h of infection and that its pyrin domain is rapidly degraded in a proteasome-dependent manner. We further demonstrate that, in contrast to several other host defense factors, IFIX degradation is not dependent on the E3 ubiquitin ligase activity of the viral protein ICP0. However, we show IFIX degradation requires immediate-early viral gene expression, suggesting a viral host suppression mechanism. The IFIX interactome also demonstrated its association with transcriptional regulatory proteins, including the 5FMC complex. We validate this interaction using microscopy and reciprocal isolations and determine it is mediated by the IFIX HIN domain. Finally, we show IFIX suppresses immediate-early and early viral gene expression during infection. Altogether, our study demonstrates that IFIX antiviral

  14. Interaction Research on the Antiviral Molecule Dufulin Targeting on Southern Rice Black Streaked Dwarf Virus P9-1 Nonstructural Protein

    Directory of Open Access Journals (Sweden)

    Zhenchao Wang

    2015-03-01

    Full Text Available ern rice black streaked dwarf virus (SRBSDV causes severe harm to rice production. Unfortunately, studies on effective antiviral drugs against SRBSDV and interaction mechanism of antiviral molecule targeting on SRBSDV have not been reported. This study found dufulin (DFL, an ideal anti-SRBSDV molecule, and investigated the interactions of DFL targeting on the nonstructural protein P9-1. The biological sequence information and bonding characterization of DFL to four kinds of P9-1 protein were described with fluorescence titration (FT and microscale thermophoresis (MST assays. The sequence analysis indicated that P9-1 had highly-conserved C- and N-terminal amino acid residues and a hypervariable region that differed from 131 aa to 160 aa. Consequently, wild-type (WT-His-P9-1, 23 C-terminal residues truncated (TR-ΔC23-His-P9-1, 6 N-terminal residues truncated (TR-ΔN6-His-P9-1, and Ser138 site-directed (MU-138-His-P9-1 mutant proteins were expressed. The FT and MST assay results indicated that DFL bounded to WT-His-P9-1 with micromole affinity and the 23 C-terminal amino acids were the potential targeting site. This system, which combines a complete sequence analysis, mutant protein expression, and binding action evaluating system, could further advance the understanding of the interaction abilities between antiviral drugs and their targets.

  15. Prion protein induced signaling cascades in monocytes

    International Nuclear Information System (INIS)

    Krebs, Bjarne; Dorner-Ciossek, Cornelia; Schmalzbauer, Ruediger; Vassallo, Neville; Herms, Jochen; Kretzschmar, Hans A.

    2006-01-01

    Prion proteins play a central role in transmission and pathogenesis of transmissible spongiform encephalopathies. The cellular prion protein (PrP C ), whose physiological function remains elusive, is anchored to the surface of a variety of cell types including neurons and cells of the lymphoreticular system. In this study, we investigated the response of a mouse monocyte/macrophage cell line to exposure with PrP C fusion proteins synthesized with a human Fc-tag. PrP C fusion proteins showed an attachment to the surface of monocyte/macrophages in nanomolar concentrations. This was accompanied by an increase of cellular tyrosine phosphorylation as a result of activated signaling pathways. Detailed investigations exhibited activation of downstream pathways through a stimulation with PrP fusion proteins, which include phosphorylation of ERK 1,2 and Akt kinase. Macrophages opsonize and present antigenic structures, contact lymphocytes, and deliver cytokines. The findings reported here may become the basis of understanding the molecular function of PrP C in monocytes and macrophages

  16. TRP channel proteins and signal transduction.

    Science.gov (United States)

    Minke, Baruch; Cook, Boaz

    2002-04-01

    TRP channel proteins constitute a large and diverse family of proteins that are expressed in many tissues and cell types. This family was designated TRP because of a spontaneously occurring Drosophila mutant lacking TRP that responded to a continuous light with a transient receptor potential (hence TRP). In addition to responses to light, TRPs mediate responses to nerve growth factor, pheromones, olfaction, mechanical, chemical, temperature, pH, osmolarity, vasorelaxation of blood vessels, and metabolic stress. Furthermore, mutations in several members of TRP-related channel proteins are responsible for several diseases, such as several tumors and neurodegenerative disorders. TRP-related channel proteins are found in a variety of organisms, tissues, and cell types, including nonexcitable, smooth muscle, and neuronal cells. The large functional diversity of TRPs is also reflected in their diverse permeability to ions, although, in general, they are classified as nonselective cationic channels. The molecular domains that are conserved in all members of the TRP family constitute parts of the transmembrane domains and in most members also the ankyrin-like repeats at the NH2 terminal of the protein and a "TRP domain" at the COOH terminal, which is a highly conserved 25-amino acid stretch with still unknown function. All of the above features suggest that members of the TRP family are "special assignment" channels, which are recruited to diverse signaling pathways. The channels' roles and characteristics such as gating mechanism, regulation, and permeability are determined by evolution according to the specific functional requirements.

  17. Acyclic nucleoside phosphonate antivirals activate gene expression of monocyte chemotactic protein 1 and 3.

    Czech Academy of Sciences Publication Activity Database

    Potměšil, Petr; Holý, Antonín; Kmoníčková, Eva; Křížková, Jana; Zídek, Zdeněk

    2007-01-01

    Roč. 14, č. 1 (2007), s. 59-66 ISSN 1021-7770 R&D Projects: GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z50390512; CEZ:AV0Z40550506 Keywords : Acyclic nucleoside phosponate * HIV * Monocyte chemotactic protein Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.024, year: 2007

  18. Inducible protein-10 as a predictive marker of antiviral hepatitis C treatment

    DEFF Research Database (Denmark)

    Neesgaard, Bastian; Ruhwald, Morten; Weis, Nina

    2017-01-01

    AIM: To investigate interferon-γ-inducible protein-10's (IP-10) potential to anticipate rapid (RVR)- and sustained virological responses (SVR) to chronic hepatitis C (CHC) treatment. METHODS: We included case series examining RVR or SVR in relation to 24 or 48 wk treatment for CHC, in patients...... treatment free for at least six months, with genotype 1 or 4, and in relation to 24 wk treatment for genotype 2 and 3, with pegylated interferon in combination with ribavirin. Patients had to have both a baseline IP-10 level as well as a hepatitis C virus (HCV)-RNA determination 4 wk after treatment...... initiation or 24 wk after end of treatment. Studies including patients with liver diseases other than CHC, human immunodeficiency virus-infection, treatment with immunosuppresents or cytostatica, alcohol dependency or active intravenous drug-use were excluded. We found 81 articles by searching the MEDLINE...

  19. Protein phosphorylation in bcterial signaling and regulation

    KAUST Repository

    Mijakovic, Ivan

    2016-01-26

    In 2003, it was demonstrated for the first time that bacteria possess protein-tyrosine kinases (BY-kinases), capable of phosphorylating other cellular proteins and regulating their activity. It soon became apparent that these kinases phosphorylate a number of protein substrates, involved in different cellular processes. More recently, we found out that BY-kinases can be activated by several distinct protein interactants, and are capable of engaging in cross-phosphorylation with other kinases. Evolutionary studies based on genome comparison indicate that BY-kinases exist only in bacteria. They are non-essential (present in about 40% bacterial genomes), and their knockouts lead to pleiotropic phenotypes, since they phosphorylate many substrates. Surprisingly, BY-kinase genes accumulate mutations at an increased rate (non-synonymous substitution rate significantly higher than other bacterial genes). One direct consequence of this phenomenon is no detectable co-evolution between kinases and their substrates. Their promiscuity towards substrates thus seems to be “hard-wired”, but why would bacteria maintain such promiscuous regulatory devices? One explanation is the maintenance of BY-kinases as rapidly evolving regulators, which can readily adopt new substrates when environmental changes impose selective pressure for quick evolution of new regulatory modules. Their role is clearly not to act as master regulators, dedicated to triggering a single response, but they might rather be employed to contribute to fine-tuning and improving robustness of various cellular responses. This unique feature makes BY-kinases a potentially useful tool in synthetic biology. While other bacterial kinases are very specific and their signaling pathways insulated, BY-kinase can relatively easily be engineered to adopt new substrates and control new biosynthetic processes. Since they are absent in humans, and regulate some key functions in pathogenic bacteria, they are also very promising

  20. Protein: MPA1 [TP Atlas

    Lifescience Database Archive (English)

    Full Text Available MPA1 TLR signaling molecules MAVS IPS1, KIAA1271, VISA VISA_(gene) Mitochondrial antiviral-signaling pr...otein CARD adapter inducing interferon beta, Interferon beta promoter stimulator protein... 1, Putative NF-kappa-B-activating protein 031N, Virus-induced-signaling adapter 9606 Homo sapiens Q7Z434 57506 2VGQ 57506 ...

  1. Neuronal Functions of Activators of G Protein Signaling

    Directory of Open Access Journals (Sweden)

    Man K. Tse

    2012-05-01

    Full Text Available G protein-coupled receptors (GPCRs are one of the most important gateways for signal transduction across the plasma membrane. Over the past decade, several classes of alternative regulators of G protein signaling have been identified and reported to activate the G proteins independent of the GPCRs. One group of such regulators is the activator of G protein signaling (AGS family which comprises of AGS1-10. They have entirely different activation mechanisms for G proteins as compared to the classic model of GPCR-mediated signaling and confer upon cells new avenues of signal transduction. As GPCRs are widely expressed in our nervous system, it is believed that the AGS family plays a major role in modulating the G protein signaling in neurons. In this article, we will review the current knowledge on AGS proteins in relation to their potential roles in neuronal regulations.

  2. The diverse functions of the hepatitis B core/capsid protein (HBc) in the viral life cycle: Implications for the development of HBc-targeting antivirals.

    Science.gov (United States)

    Diab, Ahmed; Foca, Adrien; Zoulim, Fabien; Durantel, David; Andrisani, Ourania

    2018-01-01

    Virally encoded proteins have evolved to perform multiple functions, and the core protein (HBc) of the hepatitis B virus (HBV) is a perfect example. While HBc is the structural component of the viral nucleocapsid, additional novel functions for the nucleus-localized HBc have recently been described. These results extend for HBc, beyond its structural role, a regulatory function in the viral life cycle and potentially a role in pathogenesis. In this article, we review the diverse roles of HBc in HBV replication and pathogenesis, emphasizing how the unique structure of this protein is key to its various functions. We focus in particular on recent advances in understanding the significance of HBc phosphorylations, its interaction with host proteins and the role of HBc in regulating the transcription of host genes. We also briefly allude to the emerging niche for new direct-acting antivirals targeting HBc, known as Core (protein) Allosteric Modulators (CAMs). Copyright © 2017 Elsevier B.V. All rights reserved.

  3. dsRNA-Dependent Protein Kinase PKR and its Role in Stress, Signaling and HCV Infection

    Directory of Open Access Journals (Sweden)

    Eliane F. Meurs

    2012-10-01

    Full Text Available The double-stranded RNA-dependent protein kinase PKR plays multiple roles in cells, in response to different stress situations. As a member of the interferon (IFN‑Stimulated Genes, PKR was initially recognized as an actor in the antiviral action of IFN, due to its ability to control translation, through phosphorylation, of the alpha subunit of eukaryotic initiation factor 2 (eIF2a. As such, PKR participates in the generation of stress granules, or autophagy and a number of viruses have designed strategies to inhibit its action. However, PKR deficient mice resist most viral infections, indicating that PKR may play other roles in the cell other than just acting as an antiviral agent. Indeed, PKR regulates several signaling pathways, either as an adapter protein and/or using its kinase activity. Here we review the role of PKR as an eIF2a kinase, its participation in the regulation of the NF-kB, p38MAPK and insulin pathways, and we focus on its role during infection with the hepatitis C virus (HCV. PKR binds the HCV IRES RNA, cooperates with some functions of the HCV core protein and may represent a target for NS5A or E2. Novel data points out for a role of PKR as a pro-HCV agent, both as an adapter protein and as an eIF2a-kinase, and in cooperation with the di-ubiquitin-like protein ISG15. Developing pharmaceutical inhibitors of PKR may help in resolving some viral infections as well as stress-related damages.

  4. Glycosaminoglycans mediate retention of the poxvirus type I interferon binding protein at the cell surface to locally block interferon antiviral responses

    Science.gov (United States)

    Montanuy, Imma; Alejo, Ali; Alcami, Antonio

    2011-01-01

    Eradication of smallpox was accomplished 30 yr ago, but poxviral infections still represent a public health concern due to the potential release of variola virus or the emergence of zoonotic poxviruses, such as monkeypox virus. A critical determinant of poxvirus virulence is the inhibition of interferons (IFNs) by the virus-encoded type I IFN-binding protein (IFNα/βBP). This immunomodulatory protein is secreted and has the unique property of interacting with the cell surface in order to prevent IFN-mediated antiviral responses. However, the mechanism of its attachment to the cell surface remains unknown. Using surface plasmon resonance and cell-binding assays, we report that the IFNα/βBP from vaccinia virus, the smallpox vaccine, interacts with cell surface glycosaminoglycans (GAGs). Analysis of the contribution of different regions of the protein to cell surface binding demonstrated that clusters of basic residues in the first immunoglobulin domain mediate GAG interactions. Furthermore, mutation of the GAG-interaction motifs does not affect its IFN-binding and -blocking capacity. Functional conservation of GAG-binding sites is demonstrated for the IFNα/βBP from variola and monkeypox viruses, extending our understanding of immune modulation by the most virulent human poxviruses. These results are relevant for the design of improved vaccines and intervention strategies.—Montanuy, I., Alejo, A., Alcami, A. Glycosaminoglycans mediate retention of the poxvirus type I interferon binding protein at the cell surface to locally block interferon antiviral responses. PMID:21372110

  5. The West Nile virus assembly process evades the conserved antiviral mechanism of the interferon-induced MxA protein

    Energy Technology Data Exchange (ETDEWEB)

    Hoenen, Antje [School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane (Australia); Gillespie, Leah [Department of Microbiology, La Trobe University, Melbourne (Australia); Department of Microbiology and Immunology, University of Melbourne, Melbourne (Australia); Morgan, Garry; Heide, Peter van der [Institute for Molecular Bioscience, University of Queensland, Brisbane (Australia); Khromykh, Alexander [School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane (Australia); Australian Infectious Diseases Research Centre, University of Queensland, Brisbane (Australia); Mackenzie, Jason, E-mail: jason.mackenzie@unimelb.edu.au [Department of Microbiology, La Trobe University, Melbourne (Australia); Department of Microbiology and Immunology, University of Melbourne, Melbourne (Australia)

    2014-01-05

    Flaviviruses have evolved means to evade host innate immune responses. Recent evidence suggests this is due to prevention of interferon production and signaling in flavivirus-infected cells. Here we show that the interferon-induced MxA protein can sequester the West Nile virus strain Kunjin virus (WNV{sub KUN}) capsid protein in cytoplasmic tubular structures in an expression-replication system. This sequestering resulted in reduced titers of secreted WNV{sub KUN} particles. We show by electron microscopy, tomography and 3D modeling that these cytoplasmic tubular structures form organized bundles. Additionally we show that recombinant ER-targeted MxA can restrict production of infectious WNV{sub KUN} under conditions of virus infection. Our results indicate a co-ordinated and compartmentalized WNV{sub KUN} assembly process may prevent recognition of viral components by MxA, particularly the capsid protein. This recognition can be exploited if MxA is targeted to intracellular sites of WNV{sub KUN} assembly. This results in further understanding of the mechanisms of flavivirus evasion from the immune system. - Highlights: • We show that the ISG MxA can recognize the West Nile virus capsid protein. • Interaction between WNV C protein and MxA induces cytoplasmic fibrils. • MxA can be retargeted to the ER to restrict WNV particle release. • WNV assembly process is a strategy to avoid MxA recognition.

  6. Control of striatal signaling by G protein regulators

    Directory of Open Access Journals (Sweden)

    Keqiang eXie

    2011-08-01

    Full Text Available Signaling via heterotrimeric G proteins plays a crucial role in modulating the responses of striatal neurons that ultimately shape core behaviors mediated by the basal ganglia circuitry, such as reward valuation, habit formation and movement coordination. Activation of G-protein-coupled receptors (GPCRs by extracellular signals activates heterotrimeric G proteins by promoting the binding of GTP to their α subunits. G proteins exert their effects by influencing the activity of key effector proteins in this region, including ion channels, second messenger enzymes and protein kinases. Striatal neurons express a staggering number of GPCRs whose activation results in the engagement of downstream signaling pathways and cellular responses with unique profiles but common molecular mechanisms. Studies over the last decade have revealed that the extent and duration of GPCR signaling are controlled by a conserved protein family named Regulator of G protein Signaling (RGS. RGS proteins accelerate GTP hydrolysis by the α subunits of G proteins, thus promoting deactivation of GPCR signaling. In this review, we discuss the progress made in understanding the roles of RGS proteins in controlling striatal G protein signaling and providing integration and selectivity of signal transmission. We review evidence on the formation of a macromolecular complex between RGS proteins and other components of striatal signaling pathways, their molecular regulatory mechanisms and impacts on GPCR signaling in the striatum obtained from biochemical studies and experiments involving genetic mouse models. Special emphasis is placed on RGS9-2, a member of the RGS family that is highly enriched in the striatum and plays critical roles in drug addiction and motor control.

  7. Interferon induced IFIT family genes in host antiviral defense.

    Science.gov (United States)

    Zhou, Xiang; Michal, Jennifer J; Zhang, Lifan; Ding, Bo; Lunney, Joan K; Liu, Bang; Jiang, Zhihua

    2013-01-01

    Secretion of interferons (IFNs) from virus-infected cells is a hallmark of host antiviral immunity and in fact, IFNs exert their antiviral activities through the induction of antiviral proteins. The IFN-induced protein with tetratricopeptide repeats (IFITs) family is among hundreds of IFN-stimulated genes. This family contains a cluster of duplicated loci. Most mammals have IFIT1, IFIT2, IFIT3 and IFIT5; however, bird, marsupial, frog and fish have only IFIT5. Regardless of species, IFIT5 is always adjacent to SLC16A12. IFIT family genes are predominantly induced by type I and type III interferons and are regulated by the pattern recognition and the JAK-STAT signaling pathway. IFIT family proteins are involved in many processes in response to viral infection. However, some viruses can escape the antiviral functions of the IFIT family by suppressing IFIT family genes expression or methylation of 5' cap of viral molecules. In addition, the variants of IFIT family genes could significantly influence the outcome of hepatitis C virus (HCV) therapy. We believe that our current review provides a comprehensive picture for the community to understand the structure and function of IFIT family genes in response to pathogens in human, as well as in animals.

  8. Regulation of G protein-coupled receptor signalling: focus on the cardiovascular system and regulator of G protein signalling proteins

    NARCIS (Netherlands)

    Hendriks-Balk, Mariëlle C.; Peters, Stephan L. M.; Michel, Martin C.; Alewijnse, Astrid E.

    2008-01-01

    G protein-coupled receptors (GPCRs) are involved in many biological processes. Therefore, GPCR function is tightly controlled both at receptor level and at the level of signalling components. Well-known mechanisms by which GPCR function can be regulated comprise desensitization/resensitization

  9. SOCS proteins in regulation of receptor tyrosine kinase signaling

    DEFF Research Database (Denmark)

    Kazi, Julhash U.; Kabir, Nuzhat N.; Flores Morales, Amilcar

    2014-01-01

    Receptor tyrosine kinases (RTKs) are a family of cell surface receptors that play critical roles in signal transduction from extracellular stimuli. Many in this family of kinases are overexpressed or mutated in human malignancies and thus became an attractive drug target for cancer treatment....... The signaling mediated by RTKs must be tightly regulated by interacting proteins including protein-tyrosine phosphatases and ubiquitin ligases. The suppressors of cytokine signaling (SOCS) family proteins are well-known negative regulators of cytokine receptors signaling consisting of eight structurally similar...

  10. Morbillivirus v proteins exhibit multiple mechanisms to block type 1 and type 2 interferon signalling pathways.

    Directory of Open Access Journals (Sweden)

    Senthil K Chinnakannan

    Full Text Available Morbilliviruses form a closely related group of pathogenic viruses which encode three non-structural proteins V, W and C in their P gene. Previous studies with rinderpest virus (RPV and measles virus (MeV have demonstrated that these non-structural proteins play a crucial role in blocking type I (IFNα/β and type II (IFNγ interferon action, and various mechanisms have been proposed for these effects. We have directly compared four important morbilliviruses, rinderpest (RPV, measles virus (MeV, peste des petits ruminants virus (PPRV and canine distemper virus (CDV. These viruses and their V proteins could all block type I IFN action. However, the viruses and their V proteins had varying abilities to block type II IFN action. The ability to block type II IFN-induced gene transcription correlated with co-precipitation of STAT1 with the respective V protein, but there was no correlation between co-precipitation of either STAT1 or STAT2 and the abilities of the V proteins to block type I IFN-induced gene transcription or the creation of the antiviral state. Further study revealed that the V proteins of RPV, MeV, PPRV and CDV could all interfere with phosphorylation of the interferon-receptor-associated kinase Tyk2, and the V protein of highly virulent RPV could also block the phosphorylation of another such kinase, Jak1. Co-precipitation studies showed that morbillivirus V proteins all form a complex containing Tyk2 and Jak1. This study highlights the ability of morbillivirus V proteins to target multiple components of the IFN signalling pathways to control both type I and type II IFN action.

  11. Biased and g protein-independent signaling of chemokine receptors

    DEFF Research Database (Denmark)

    Steen, Anne; Larsen, Olav; Thiele, Stefanie

    2014-01-01

    ), different receptors (with the same ligand), or different tissues or cells (for the same ligand-receptor pair). Most often biased signaling is differentiated into G protein-dependent and β-arrestin-dependent signaling. Yet, it may also cover signaling differences within these groups. Moreover, it may...

  12. Regulator of G-protein signaling - 5 (RGS5 is a novel repressor of hedgehog signaling.

    Directory of Open Access Journals (Sweden)

    William M Mahoney

    Full Text Available Hedgehog (Hh signaling plays fundamental roles in morphogenesis, tissue repair, and human disease. Initiation of Hh signaling is controlled by the interaction of two multipass membrane proteins, patched (Ptc and smoothened (Smo. Recent studies identify Smo as a G-protein coupled receptor (GPCR-like protein that signals through large G-protein complexes which contain the Gαi subunit. We hypothesize Regulator of G-Protein Signaling (RGS proteins, and specifically RGS5, are endogenous repressors of Hh signaling via their ability to act as GTPase activating proteins (GAPs for GTP-bound Gαi, downstream of Smo. In support of this hypothesis, we demonstrate that RGS5 over-expression inhibits sonic hedgehog (Shh-mediated signaling and osteogenesis in C3H10T1/2 cells. Conversely, signaling is potentiated by siRNA-mediated knock-down of RGS5 expression, but not RGS4 expression. Furthermore, using immuohistochemical analysis and co-immunoprecipitation (Co-IP, we demonstrate that RGS5 is present with Smo in primary cilia. This organelle is required for canonical Hh signaling in mammalian cells, and RGS5 is found in a physical complex with Smo in these cells. We therefore conclude that RGS5 is an endogenous regulator of Hh-mediated signaling and that RGS proteins are potential targets for novel therapeutics in Hh-mediated diseases.

  13. Mechanism of inhibition of growth hormone receptor signaling by suppressor of cytokine signaling proteins

    DEFF Research Database (Denmark)

    Hansen, J A; Lindberg, K; Hilton, D J

    1999-01-01

    In this study we have investigated the role of suppressor of cytokine signaling (SOCS) proteins in GH receptor-mediated signaling. GH-induced transcription was inhibited by SOCS-1 and SOCS-3, while SOCS-2 and cytokine inducible SH2-containing protein (CIS) had no effect By using chimeric SOCS pro...

  14. NSP-CAS Protein Complexes: Emerging Signaling Modules in Cancer.

    Science.gov (United States)

    Wallez, Yann; Mace, Peter D; Pasquale, Elena B; Riedl, Stefan J

    2012-05-01

    The CAS (CRK-associated substrate) family of adaptor proteins comprises 4 members, which share a conserved modular domain structure that enables multiple protein-protein interactions, leading to the assembly of intracellular signaling platforms. Besides their physiological role in signal transduction downstream of a variety of cell surface receptors, CAS proteins are also critical for oncogenic transformation and cancer cell malignancy through associations with a variety of regulatory proteins and downstream effectors. Among the regulatory partners, the 3 recently identified adaptor proteins constituting the NSP (novel SH2-containing protein) family avidly bind to the conserved carboxy-terminal focal adhesion-targeting (FAT) domain of CAS proteins. NSP proteins use an anomalous nucleotide exchange factor domain that lacks catalytic activity to form NSP-CAS signaling modules. Additionally, the NSP SH2 domain can link NSP-CAS signaling assemblies to tyrosine-phosphorylated cell surface receptors. NSP proteins can potentiate CAS function by affecting key CAS attributes such as expression levels, phosphorylation state, and subcellular localization, leading to effects on cell adhesion, migration, and invasion as well as cell growth. The consequences of these activities are well exemplified by the role that members of both families play in promoting breast cancer cell invasiveness and resistance to antiestrogens. In this review, we discuss the intriguing interplay between the NSP and CAS families, with a particular focus on cancer signaling networks.

  15. BAR domain proteins regulate Rho GTPase signaling.

    Science.gov (United States)

    Aspenström, Pontus

    2014-01-01

    BAR proteins comprise a heterogeneous group of multi-domain proteins with diverse biological functions. The common denominator is the Bin-Amphiphysin-Rvs (BAR) domain that not only confers targeting to lipid bilayers, but also provides scaffolding to mold lipid membranes into concave or convex surfaces. This function of BAR proteins is an important determinant in the dynamic reconstruction of membrane vesicles, as well as of the plasma membrane. Several BAR proteins function as linkers between cytoskeletal regulation and membrane dynamics. These links are provided by direct interactions between BAR proteins and actin-nucleation-promoting factors of the Wiskott-Aldrich syndrome protein family and the Diaphanous-related formins. The Rho GTPases are key factors for orchestration of this intricate interplay. This review describes how BAR proteins regulate the activity of Rho GTPases, as well as how Rho GTPases regulate the function of BAR proteins. This mutual collaboration is a central factor in the regulation of vital cellular processes, such as cell migration, cytokinesis, intracellular transport, endocytosis, and exocytosis.

  16. A Signal Processing Method to Explore Similarity in Protein Flexibility

    Directory of Open Access Journals (Sweden)

    Simina Vasilache

    2010-01-01

    Full Text Available Understanding mechanisms of protein flexibility is of great importance to structural biology. The ability to detect similarities between proteins and their patterns is vital in discovering new information about unknown protein functions. A Distance Constraint Model (DCM provides a means to generate a variety of flexibility measures based on a given protein structure. Although information about mechanical properties of flexibility is critical for understanding protein function for a given protein, the question of whether certain characteristics are shared across homologous proteins is difficult to assess. For a proper assessment, a quantified measure of similarity is necessary. This paper begins to explore image processing techniques to quantify similarities in signals and images that characterize protein flexibility. The dataset considered here consists of three different families of proteins, with three proteins in each family. The similarities and differences found within flexibility measures across homologous proteins do not align with sequence-based evolutionary methods.

  17. Temporal protein expression pattern in intracellular signalling ...

    Indian Academy of Sciences (India)

    Supplementary figure 1. Protein expression dynamics observed in Experiment, Synchronous and. Asynchronous simulation. .... molecular basis for T cell suppression by IL-10: CD28-asso- ciated IL-10 receptor inhibits CD28 tyrosine ...

  18. Thematic minireview series: cell biology of G protein signaling.

    Science.gov (United States)

    Dohlman, Henrik G

    2015-03-13

    This thematic series is on the topic of cell signaling from a cell biology perspective, with a particular focus on G proteins. G protein-coupled receptors (GPCRs, also known as seven-transmembrane receptors) are typically found at the cell surface. Upon agonist binding, these receptors will activate a GTP-binding G protein at the cytoplasmic face of the plasma membrane. Additionally, there is growing evidence that G proteins can also be activated by non-receptor binding partners, and they can signal from non-plasma membrane compartments. The production of second messengers at multiple, spatially distinct locations represents a type of signal encoding that has been largely neglected. The first minireview in the series describes biosensors that are being used to monitor G protein signaling events in live cells. The second describes the implementation of antibody-based biosensors to dissect endosome signaling by G proteins and their receptors. The third describes the function of a non-receptor, cytoplasmic activator of G protein signaling, called GIV (Girdin). Collectively, the advances described in these articles provide a deeper understanding and emerging opportunities for new pharmacology. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  19. Aryl hydrocarbon receptor signaling modulates antiviral immune responses: ligand metabolism rather than chemical source is the stronger predictor of outcome.

    Science.gov (United States)

    Boule, Lisbeth A; Burke, Catherine G; Jin, Guang-Bi; Lawrence, B Paige

    2018-01-29

    The aryl hydrocarbon receptor (AHR) offers a compelling target to modulate the immune system. AHR agonists alter adaptive immune responses, but the consequences differ across studies. We report here the comparison of four agents representing different sources of AHR ligands in mice infected with influenza A virus (IAV): TCDD, prototype exogenous AHR agonist; PCB126, pollutant with documented human exposure; ITE, novel pharmaceutical; and FICZ, degradation product of tryptophan. All four compounds diminished virus-specific IgM levels and increased the proportion of regulatory T cells. TCDD, PCB126 and ITE, but not FICZ, reduced virus-specific IgG levels and CD8 + T cell responses. Similarly, ITE, PCB126, and TCDD reduced Th1 and Tfh cells, whereas FICZ increased their frequency. In Cyp1a1-deficient mice, all compounds, including FICZ, reduced the response to IAV. Conditional Ahr knockout mice revealed that all four compounds require AHR within hematopoietic cells. Thus, differences in the immune response to IAV likely reflect variances in quality, magnitude, and duration of AHR signaling. This indicates that binding affinity and metabolism may be stronger predictors of immune effects than a compound's source of origin, and that harnessing AHR will require finding a balance between dampening immune-mediated pathologies and maintaining sufficient host defenses against infection.

  20. Transmembrane adaptor proteins: organizers of immunoreceptor signalling

    Czech Academy of Sciences Publication Activity Database

    Hořejší, Václav; Zhang, W.; Schraven, B.

    2004-01-01

    Roč. 4, č. 8 (2004), s. 603-616 ISSN 1474-1733 R&D Projects: GA MŠk LN00A026 Institutional research plan: CEZ:AV0Z5052915 Keywords : immunoreceptor * signalling Subject RIV: EC - Immunology Impact factor: 32.695, year: 2004

  1. Temporal protein expression pattern in intracellular signalling ...

    Indian Academy of Sciences (India)

    2015-09-28

    Sep 28, 2015 ... targets for the treatment of various T-cells, immune-related diseases. We hope ... signifies the alternative routes of signal propagation. The molecules kept in ...... growth factor, mitogens for vascular cells and fibroblasts: dif- ferential ..... tumor necrosis factor contributes to CD8(+) T cell survival in the transition ...

  2. Protein phosphorylation and its role in archaeal signal transduction

    Science.gov (United States)

    Esser, Dominik; Hoffmann, Lena; Pham, Trong Khoa; Bräsen, Christopher; Qiu, Wen; Wright, Phillip C.; Albers, Sonja-Verena; Siebers, Bettina

    2016-01-01

    Reversible protein phosphorylation is the main mechanism of signal transduction that enables cells to rapidly respond to environmental changes by controlling the functional properties of proteins in response to external stimuli. However, whereas signal transduction is well studied in Eukaryotes and Bacteria, the knowledge in Archaea is still rather scarce. Archaea are special with regard to protein phosphorylation, due to the fact that the two best studied phyla, the Euryarchaeota and Crenarchaeaota, seem to exhibit fundamental differences in regulatory systems. Euryarchaeota (e.g. halophiles, methanogens, thermophiles), like Bacteria and Eukaryotes, rely on bacterial-type two-component signal transduction systems (phosphorylation on His and Asp), as well as on the protein phosphorylation on Ser, Thr and Tyr by Hanks-type protein kinases. Instead, Crenarchaeota (e.g. acidophiles and (hyper)thermophiles) only depend on Hanks-type protein phosphorylation. In this review, the current knowledge of reversible protein phosphorylation in Archaea is presented. It combines results from identified phosphoproteins, biochemical characterization of protein kinases and protein phosphatases as well as target enzymes and first insights into archaeal signal transduction by biochemical, genetic and polyomic studies. PMID:27476079

  3. Ubiquitin in signaling and protein quality control

    DEFF Research Database (Denmark)

    Al-Saoudi, Sofie Vincents

    is related to the cancer-predisposition disease, Lynch syndrome. Of 24 different MSH2 variants, some of which have been linked to Lynch syndrome, we show that there is a strong correlation between the predicted structural stability and the protein half-life. We show that a predicted destabilization of 3 kcal....../mol is sufficient to cause proteasomal degradation of MSH2 variants. Importantly our calculations can, in addition to protein turnover, also predict pathogenicity of MSH2 variants, suggesting that this approach can be applied for Lynch syndrome diagnosis, and perhaps for other hereditary diseases....

  4. Bone morphogenetic protein signalling in colorectal cancer

    NARCIS (Netherlands)

    Hardwick, James C.; Kodach, Liudmila L.; Offerhaus, G. Johan; van den Brink, Gijs R.

    2008-01-01

    Much of the current understanding of colorectal cancer stems from the study of rare, inherited colorectal cancer syndromes. Mutations in the bone morphogenetic protein (BMP) pathway have been found in juvenile polyposis, an inherited polyposis syndrome that predisposes to colorectal cancer. The

  5. Protein kinase C alpha controls erythropoietin receptor signaling.

    NARCIS (Netherlands)

    M.M. von Lindern (Marieke); M. Parren-Van Amelsvoort (Martine); T.B. van Dijk (Thamar); E. Deiner; B. Löwenberg (Bob); E. van den Akker (Emile); S. van Emst-de Vries (Sjenet); P.J. Willems (Patrick); H. Beug (Hartmut)

    2000-01-01

    textabstractProtein kinase C (PKC) is implied in the activation of multiple targets of erythropoietin (Epo) signaling, but its exact role in Epo receptor (EpoR) signal transduction and in the regulation of erythroid proliferation and differentiation remained elusive. We

  6. Protein kinase C alpha controls erythropoietin receptor signaling

    NARCIS (Netherlands)

    von Lindern, M.; Parren-van Amelsvoort, M.; van Dijk, T.; Deiner, E.; van den Akker, E.; van Emst-de Vries, S.; Willems, P.; Beug, H.; Löwenberg, B.

    2000-01-01

    Protein kinase C (PKC) is implied in the activation of multiple targets of erythropoietin (Epo) signaling, but its exact role in Epo receptor (EpoR) signal transduction and in the regulation of erythroid proliferation and differentiation remained elusive. We analyzed the effect of PKC inhibitors

  7. The interferon response circuit in antiviral host defense.

    Science.gov (United States)

    Haller, O; Weber, F

    2009-01-01

    Viruses have learned to multiply in the face of a powerful innate and adaptive immune response of the host. They have evolved multiple strategies to evade the interferon (IFN) system which would otherwise limit virus growth at an early stage of infection. IFNs induce the synthesis of a range of antiviral proteins which serve as cell-autonomous intrinsic restriction factors. For example, the dynamin-like MxA GTPase inhibits the multiplication of influenza and bunyaviruses (such as La Crosse virus, Hantaan virus, Rift Valley Fever virus, and Crimean-Congo hemorrhagic fever virus) by binding and sequestering the nucleocapsid protein into large perinuclear complexes. To overcome such intracellular restrictions, virulent viruses either inhibit IFN synthesis, bind and inactivate secreted IFN molecules, block IFN-activated signaling, or disturb the action of IFN-induced antiviral proteins. Many viruses produce specialized proteins to disarm the danger signal or express virulence genes that target members of the IFN regulatory factor family (IRFs) or components of the JAK-STAT signaling pathway. An alternative evasion strategy is based on extreme viral replication speed which out-competes the IFN response. The identification of viral proteins with IFN antagonistic functions has great implications for disease prevention and therapy. Virus mutants lacking IFN antagonistic properties represent safe yet highly immunogenic candidate vaccines. Furthermore, novel drugs intercepting viral IFN-antagonists could be used to disarm the viral intruders.

  8. Human influenza is more effective than avian influenza at antiviral suppression in airway cells.

    Science.gov (United States)

    Hsu, Alan Chen-Yu; Barr, Ian; Hansbro, Philip M; Wark, Peter A

    2011-06-01

    Airway epithelial cells are the initial site of infection with influenza viruses. The innate immune responses of airway epithelial cells to infection are important in limiting virus replication and spread. However, relatively little is known about the importance of this innate antiviral response to infection. Avian influenza viruses are a potential source of future pandemics; therefore, it is critical to examine the effectiveness of the host antiviral system to different influenza viruses. We used a human influenza (H3N2) and a low-pathogenic avian influenza (H11N9) to assess and compare the antiviral responses of Calu-3 cells. After infection, H3N2 replicated more effectively than the H11N9 in Calu-3 cells. This was not due to differential expression of sialic acid residues on Calu-3 cells, but was attributed to the interference of host antiviral responses by H3N2. H3N2 induced a delayed antiviral signaling and impaired type I and type III IFN induction compared with the H11N9. The gene encoding for nonstructural (NS) 1 protein was transfected into the bronchial epithelial cells (BECs), and the H3N2 NS1 induced a greater inhibition of antiviral responses compared with the H11N9 NS1. Although the low-pathogenic avian influenza virus was capable of infecting BECs, the human influenza virus replicated more effectively than avian influenza virus in BECs, and this was due to a differential ability of the two NS1 proteins to inhibit antiviral responses. This suggests that the subversion of human antiviral responses may be an important requirement for influenza viruses to adapt to the human host and cause disease.

  9. Mitogen-activated protein kinase signaling in plants

    DEFF Research Database (Denmark)

    Rodriguez, Maria Cristina Suarez; Petersen, Morten; Mundy, John

    2010-01-01

    crossinhibition, feedback control, and scaffolding. Plant MAPK cascades regulate numerous processes, including stress and hormonal responses, innate immunity, and developmental programs. Genetic analyses have uncovered several predominant MAPK components shared by several of these processes including...... of substrate proteins, whose altered activities mediate a wide array of responses, including changes in gene expression. Cascades may share kinase components, but their signaling specificity is maintained by spaciotemporal constraints and dynamic protein-protein interactions and by mechanisms that include...

  10. La respuesta inmune antiviral

    Directory of Open Access Journals (Sweden)

    Rainel Sánchez de la Rosa

    1998-02-01

    Full Text Available Se expone que los virus son parásitos intracelulares obligados, puesto que no tienen metabolismo propio; esto obliga al sistema inmune a poner en marcha sus mecanismos más especializados para reconocer y eliminar, tanto a los virus libres, como a las células infectadas. Se señala que las células presentadoras de antígenos, los linfocitos B y los T unidos al complejo mayor de histocompatibilidad, forman parte de la organización de la respuesta inmune antiviral; la inducción de esta respuesta con proteínas, péptidos y ADN desnudo, son alternativas actuales tanto en la prevención como en el tratamiento de las infecciones viralesIt is explained that viruses are compulsory intracellular parasites, since they don't have their own metabolism, which makes the immune system to start its mest specialized mechanisms to recognize and eliminate the free viruses and the infected cells. It is stated that the cells presenting antigens, and the B and T lymphocytes together with the major histocompatibility complex, are part of the organization of the immune antiviral response. The induction of this response with proteins, peptides and naked DNA are the present alternatives for the prevention and treatment of viral infections

  11. The C proteins of human parainfluenza virus type 1 block IFN signaling by binding and retaining Stat1 in perinuclear aggregates at the late endosome.

    Directory of Open Access Journals (Sweden)

    Henrick Schomacker

    Full Text Available Interferons (IFNs play a crucial role in the antiviral immune response. Whereas the C proteins of wild-type human parainfluenza virus type 1 (WT HPIV1 inhibit both IFN-β induction and signaling, a HPIV1 mutant encoding a single amino acid substitution (F170S in the C proteins is unable to block either host response. Here, signaling downstream of the type 1 IFN receptor was examined in Vero cells to define at what stage WT HPIV1 can block, and F170S HPIV1 fails to block, IFN signaling. WT HPIV1 inhibited phosphorylation of both Stat1 and Stat2, and this inhibition was only slightly reduced for F170S HPIV1. Degradation of Stat1 or Stat2 was not observed. The HPIV1 C proteins were found to accumulate in the perinuclear space, often forming large granules, and co-localized with Stat1 and the cation-independent mannose 6-phosphate receptor (M6PR that is a marker for late endosomes. Upon stimulation with IFN-β, both the WT and F170S C proteins remained in the perinuclear space, but only the WT C proteins prevented Stat1 translocation to the nucleus. In addition, WT HPIV1 C proteins, but not F170S C proteins, co-immunoprecipitated both phosphorylated and unphosphorylated Stat1. Our findings suggest that the WT HPIV1 C proteins form a stable complex with Stat1 in perinuclear granules that co-localize with M6PR, and that this direct interaction between the WT HPIV1 C proteins and Stat1 is the basis for the ability of HPIV1 to inhibit IFN signaling. The F170S mutation in HPIV1 C did not prevent perinuclear co-localization with Stat1, but apparently weakened this interaction such that, upon IFN stimulation, Stat1 was translocated to the nucleus to induce an antiviral response.

  12. Rap G protein signal in normal and disordered lymphohematopoiesis.

    Science.gov (United States)

    Minato, Nagahiro

    2013-09-10

    Rap proteins (Rap1, Rap2a, b, c) are small molecular weight GTPases of the Ras family. Rap G proteins mediate diverse cellular events such as cell adhesion, proliferation, and gene activation through various signaling pathways. Activation of Rap signal is regulated tightly by several specific regulatory proteins including guanine nucleotide exchange factors and GTPase-activating proteins. Beyond cell biological studies, increasing attempts have been made in the past decade to define the roles of Rap signal in specific functions of normal tissue systems as well as in cancer. In the immune and hematopoietic systems, Rap signal plays crucial roles in the development and function of essentially all lineages of lymphocytes and hematopoietic cells, and importantly, deregulated Rap signal may lead to unique pathological conditions depending on the affected cell types, including various types of leukemia and autoimmunity. The phenotypical studies have unveiled novel, even unexpected functional aspects of Rap signal in cells from a variety of tissues, providing potentially important clues for controlling human diseases, including malignancy. © 2013 Elsevier Inc. All rights reserved.

  13. Linking proteins to signaling pathways for experiment design and evaluation.

    Directory of Open Access Journals (Sweden)

    Illés J Farkas

    Full Text Available Biomedical experimental work often focuses on altering the functions of selected proteins. These changes can hit signaling pathways, and can therefore unexpectedly and non-specifically affect cellular processes. We propose PathwayLinker, an online tool that can provide a first estimate of the possible signaling effects of such changes, e.g., drug or microRNA treatments. PathwayLinker minimizes the users' efforts by integrating protein-protein interaction and signaling pathway data from several sources with statistical significance tests and clear visualization. We demonstrate through three case studies that the developed tool can point out unexpected signaling bias in normal laboratory experiments and identify likely novel signaling proteins among the interactors of known drug targets. In our first case study we show that knockdown of the Caenorhabditis elegans gene cdc-25.1 (meant to avoid progeny may globally affect the signaling system and unexpectedly bias experiments. In the second case study we evaluate the loss-of-function phenotypes of a less known C. elegans gene to predict its function. In the third case study we analyze GJA1, an anti-cancer drug target protein in human, and predict for this protein novel signaling pathway memberships, which may be sources of side effects. Compared to similar services, a major advantage of PathwayLinker is that it drastically reduces the necessary amount of manual literature searches and can be used without a computational background. PathwayLinker is available at http://PathwayLinker.org. Detailed documentation and source code are available at the website.

  14. New ribosome-inactivating proteins with polynucleotide:adenosine glycosidase and antiviral activities from Basella rubra L. and bougainvillea spectabilis Willd.

    Science.gov (United States)

    Bolognesi, A; Polito, L; Olivieri, F; Valbonesi, P; Barbieri, L; Battelli, M G; Carusi, M V; Benvenuto, E; Del Vecchio Blanco, F; Di Maro, A; Parente, A; Di Loreto, M; Stirpe, F

    1997-12-01

    New single-chain (type 1) ribosome-inactivating proteins (RIPs) were isolated from the seeds of Basella rubra L. (two proteins) and from the leaves of Bougainvillea spectabilis Willd. (one protein). These RIPs inhibit protein synthesis both in a cell-free system, with an IC50 (concentration causing 50% inhibition) in the 10(-10) M range, and by various cell lines, with IC50S in the 10(-8)-10(-6) M range. All three RIPs released adenine not only from rat liver ribosomes but also from Escherichia coli rRNA, polyadenylic acid, herring sperm DNA, and artichoke mottled crinkle virus (AMCV) genomic RNA, thus being polynucleotide:adenosine glycosidases. The proteins from Basella rubra had toxicity to mice similar to that of most type 1 RIPs (Barbieri et al., 1993, Biochim Biophys Acta 1154: 237-282) with an LD50 (concentration that is 50% lethal) Bougainvillea spectabilis had an LD50 > 32 mg.kg-1. The N-terminal sequence of the two RIPs from Basella rubra had 80-93% identity, whereas it differed from the sequence of the RIP from Bougainvillea spectabilis. When tested with antibodies against various RIPs, the RIPs from Basella gave some cross-reactivity with sera against dianthin 32, and weak cross-reactivity with momordin I and momorcochin-S, whilst the RIP from Bougainvillea did not cross-react with any antiserum tested. An RIP from Basella rubra and one from Bougainvillea spectabilis were tested for antiviral activity, and both inhibited infection of Nicotiana benthamiana by AMCV.

  15. Protein and signaling networks in vertebrate photoreceptor cells

    Directory of Open Access Journals (Sweden)

    Karl-Wilhelm eKoch

    2015-11-01

    Full Text Available Vertebrate photoreceptor cells are exquisite light detectors operating under very dim and bright illumination. The photoexcitation and adaptation machinery in photoreceptor cells consists of protein complexes that can form highly ordered supramolecular structures and control the homeostasis and mutual dependence of the secondary messengers cGMP and Ca2+. The visual pigment in rod photoreceptors, the G protein-coupled receptor rhodopsin is organized in tracks of dimers thereby providing a signaling platform for the dynamic scaffolding of the G protein transducin. Illuminated rhodopsin is turned off by phosphorylation catalyzed by rhodopsin kinase GRK1 under control of Ca2+-recoverin. The GRK1 protein complex partly assembles in lipid raft structures, where shutting off rhodopsin seems to be more effective. Re-synthesis of cGMP is another crucial step in the recovery of the photoresponse after illumination. It is catalyzed by membrane bound sensory guanylate cyclases and is regulated by specific neuronal Ca2+-sensor proteins called GCAPs. At least one guanylate cyclase (ROS-GC1 was shown to be part of a multiprotein complex having strong interactions with the cytoskeleton and being controlled in a multimodal Ca2+-dependent fashion. The final target of the cGMP signaling cascade is a cyclic nucleotide-gated channel that is a hetero-oligomeric protein located in the plasma membrane and interacting with accessory proteins in highly organized microdomains. We summarize results and interpretations of findings related to the inhomogeneous organization of signaling units in photoreceptor outer segments.

  16. The Tudor domain protein Spindlin1 is involved in intrinsic antiviral defense against incoming hepatitis B Virus and herpes simplex virus type 1.

    Directory of Open Access Journals (Sweden)

    Aurélie Ducroux

    2014-09-01

    Full Text Available Hepatitis B virus infection (HBV is a major risk factor for the development of hepatocellular carcinoma. HBV replicates from a covalently closed circular DNA (cccDNA that remains as an episome within the nucleus of infected cells and serves as a template for the transcription of HBV RNAs. The regulatory protein HBx has been shown to be essential for cccDNA transcription in the context of infection. Here we identified Spindlin1, a cellular Tudor-domain protein, as an HBx interacting partner. We further demonstrated that Spindlin1 is recruited to the cccDNA and inhibits its transcription in the context of infection. Spindlin1 knockdown induced an increase in HBV transcription and in histone H4K4 trimethylation at the cccDNA, suggesting that Spindlin1 impacts on epigenetic regulation. Spindlin1-induced transcriptional inhibition was greater for the HBV virus deficient for the expression of HBx than for the HBV WT virus, suggesting that HBx counteracts Spindlin1 repression. Importantly, we showed that the repressive role of Spindlin1 is not limited to HBV transcription but also extends to other DNA virus that replicate within the nucleus such as Herpes Simplex Virus type 1 (HSV-1. Taken together our results identify Spindlin1 as a critical component of the intrinsic antiviral defense and shed new light on the function of HBx in HBV infection.

  17. The Importance of the KR-Rich Region of the Coat Protein of Ourmia melon virus for Host Specificity, Tissue Tropism, and Interference With Antiviral Defense.

    Science.gov (United States)

    Rossi, Marika; Vallino, Marta; Abbà, Simona; Ciuffo, Marina; Balestrini, Raffaella; Genre, Andrea; Turina, Massimo

    2015-01-01

    The N-terminal region of the Ourmia melon virus (OuMV) coat protein (CP) contains a short lysine/arginine-rich (KR) region. By alanine scanning mutagenesis, we showed that the KR region influences pathogenicity and virulence of OuMV without altering viral particle assembly. A mutant, called OuMV6710, with three basic residue substitutions in the KR region, was impaired in the ability to maintain the initial systemic infection in Nicotiana benthamiana and to infect both cucumber and melon plants systemically. The integrity of this protein region was also crucial for encapsidation of viral genomic RNA; in fact, certain mutations within the KR region partially compromised the RNA encapsidation efficiency of the CP. In Arabidopsis thaliana Col-0, OuMV6710 was impaired in particle accumulation; however, this phenotype was abolished in dcl2/dcl4 and dcl2/dcl3/dcl4 Arabidopsis mutants defective for antiviral silencing. Moreover, in contrast to CPwt, in situ immunolocalization experiments indicated that CP6710 accumulates efficiently in the spongy mesophyll tissue of infected N. benthamiana and A. thaliana leaves but only occasionally infects palisade tissues. These results provided strong evidence of a crucial role for OuMV CP during viral infection and highlighted the relevance of the KR region in determining tissue tropism, host range, pathogenicity, and RNA affinity, which may be all correlated with a possible CP silencing-suppression activity.

  18. Defective chemokine signal integration in leukocytes lacking activator of G protein signaling 3 (AGS3).

    Science.gov (United States)

    Branham-O'Connor, Melissa; Robichaux, William G; Zhang, Xian-Kui; Cho, Hyeseon; Kehrl, John H; Lanier, Stephen M; Blumer, Joe B

    2014-04-11

    Activator of G-protein signaling 3 (AGS3, gene name G-protein signaling modulator-1, Gpsm1), an accessory protein for G-protein signaling, has functional roles in the kidney and CNS. Here we show that AGS3 is expressed in spleen, thymus, and bone marrow-derived dendritic cells, and is up-regulated upon leukocyte activation. We explored the role of AGS3 in immune cell function by characterizing chemokine receptor signaling in leukocytes from mice lacking AGS3. No obvious differences in lymphocyte subsets were observed. Interestingly, however, AGS3-null B and T lymphocytes and bone marrow-derived dendritic cells exhibited significant chemotactic defects as well as reductions in chemokine-stimulated calcium mobilization and altered ERK and Akt activation. These studies indicate a role for AGS3 in the regulation of G-protein signaling in the immune system, providing unexpected venues for the potential development of therapeutic agents that modulate immune function by targeting these regulatory mechanisms.

  19. PDZ Protein Regulation of G Protein-Coupled Receptor Trafficking and Signaling Pathways.

    Science.gov (United States)

    Dunn, Henry A; Ferguson, Stephen S G

    2015-10-01

    G protein-coupled receptors (GPCRs) contribute to the regulation of every aspect of human physiology and are therapeutic targets for the treatment of numerous diseases. As a consequence, understanding the myriad of mechanisms controlling GPCR signaling and trafficking is essential for the development of new pharmacological strategies for the treatment of human pathologies. Of the many GPCR-interacting proteins, postsynaptic density protein of 95 kilodaltons, disc large, zona occludens-1 (PDZ) domain-containing proteins appear most abundant and have similarly been implicated in disease mechanisms. PDZ proteins play an important role in regulating receptor and channel protein localization within synapses and tight junctions and function to scaffold intracellular signaling protein complexes. In the current study, we review the known functional interactions between PDZ domain-containing proteins and GPCRs and provide insight into the potential mechanisms of action. These PDZ domain-containing proteins include the membrane-associated guanylate-like kinases [postsynaptic density protein of 95 kilodaltons; synapse-associated protein of 97 kilodaltons; postsynaptic density protein of 93 kilodaltons; synapse-associated protein of 102 kilodaltons; discs, large homolog 5; caspase activation and recruitment domain and membrane-associated guanylate-like kinase domain-containing protein 3; membrane protein, palmitoylated 3; calcium/calmodulin-dependent serine protein kinase; membrane-associated guanylate kinase protein (MAGI)-1, MAGI-2, and MAGI-3], Na(+)/H(+) exchanger regulatory factor proteins (NHERFs) (NHERF1, NHERF2, PDZ domain-containing kidney protein 1, and PDZ domain-containing kidney protein 2), Golgi-associated PDZ proteins (Gα-binding protein interacting protein, C-terminus and CFTR-associated ligand), PDZ domain-containing guanine nucleotide exchange factors (GEFs) 1 and 2, regulator of G protein signaling (RGS)-homology-RhoGEFs (PDZ domain-containing RhoGEF and

  20. 14-3-3 proteins in plant brassinosteroid signaling

    NARCIS (Netherlands)

    Vries, de S.C.

    2007-01-01

    Brassinosteroid (BR) signaling requires the BIN2 kinase-promoted interaction of 14-3-3 proteins with the transcriptional regulators BZR1 and BZR2, which are subsequently redistributed to the cytoplasm by BRs. In this issue of Developmental Cell, Gampala et al. show that this redistribution may

  1. Oncogenic Signaling by Leukemia-Associated Mutant Cbl Proteins

    Science.gov (United States)

    Nadeau, Scott; An, Wei; Palermo, Nick; Feng, Dan; Ahmad, Gulzar; Dong, Lin; Borgstahl, Gloria E. O.; Natarajan, Amarnath; Naramura, Mayumi; Band, Vimla; Band, Hamid

    2013-01-01

    Members of the Cbl protein family (Cbl, Cbl-b, and Cbl-c) are E3 ubiquitin ligases that have emerged as critical negative regulators of protein tyrosine kinase (PTK) signaling. This function reflects their ability to directly interact with activated PTKs and to target them as well as their associated signaling components for ubiquitination. Given the critical roles of PTK signaling in driving oncogenesis, recent studies in animal models and genetic analyses in human cancer have firmly established that Cbl proteins function as tumor suppressors. Missense mutations or small in-frame deletions within the regions of Cbl protein that are essential for its E3 activity have been identified in nearly 5% of leukemia patients with myelodysplastic/myeloproliferative disorders. Based on evidence from cell culture studies, in vivo models and clinical data, we discuss the potential signaling mechanisms of mutant Cbl-driven oncogenesis. Mechanistic insights into oncogenic Cbl mutants and associated animal models are likely to enhance our understanding of normal hematopoietic stem cell homeostasis and provide avenues for targeted therapy of mutant Cbl-driven cancers. PMID:23997989

  2. 14-3-3 Proteins in Guard Cell Signaling.

    Science.gov (United States)

    Cotelle, Valérie; Leonhardt, Nathalie

    2015-01-01

    Guard cells are specialized cells located at the leaf surface delimiting pores which control gas exchanges between the plant and the atmosphere. To optimize the CO2 uptake necessary for photosynthesis while minimizing water loss, guard cells integrate environmental signals to adjust stomatal aperture. The size of the stomatal pore is regulated by movements of the guard cells driven by variations in their volume and turgor. As guard cells perceive and transduce a wide array of environmental cues, they provide an ideal system to elucidate early events of plant signaling. Reversible protein phosphorylation events are known to play a crucial role in the regulation of stomatal movements. However, in some cases, phosphorylation alone is not sufficient to achieve complete protein regulation, but is necessary to mediate the binding of interactors that modulate protein function. Among the phosphopeptide-binding proteins, the 14-3-3 proteins are the best characterized in plants. The 14-3-3s are found as multiple isoforms in eukaryotes and have been shown to be involved in the regulation of stomatal movements. In this review, we describe the current knowledge about 14-3-3 roles in the regulation of their binding partners in guard cells: receptors, ion pumps, channels, protein kinases, and some of their substrates. Regulation of these targets by 14-3-3 proteins is discussed and related to their function in guard cells during stomatal movements in response to abiotic or biotic stresses.

  3. Epstein-Barr virus large tegument protein BPLF1 contributes to innate immune evasion through interference with toll-like receptor signaling.

    Directory of Open Access Journals (Sweden)

    Michiel van Gent

    2014-02-01

    Full Text Available Viral infection triggers an early host response through activation of pattern recognition receptors, including Toll-like receptors (TLR. TLR signaling cascades induce production of type I interferons and proinflammatory cytokines involved in establishing an anti-viral state as well as in orchestrating ensuing adaptive immunity. To allow infection, replication, and persistence, (herpesviruses employ ingenious strategies to evade host immunity. The human gamma-herpesvirus Epstein-Barr virus (EBV is a large, enveloped DNA virus persistently carried by more than 90% of adults worldwide. It is the causative agent of infectious mononucleosis and is associated with several malignant tumors. EBV activates TLRs, including TLR2, TLR3, and TLR9. Interestingly, both the expression of and signaling by TLRs is attenuated during productive EBV infection. Ubiquitination plays an important role in regulating TLR signaling and is controlled by ubiquitin ligases and deubiquitinases (DUBs. The EBV genome encodes three proteins reported to exert in vitro deubiquitinase activity. Using active site-directed probes, we show that one of these putative DUBs, the conserved herpesvirus large tegument protein BPLF1, acts as a functional DUB in EBV-producing B cells. The BPLF1 enzyme is expressed during the late phase of lytic EBV infection and is incorporated into viral particles. The N-terminal part of the large BPLF1 protein contains the catalytic site for DUB activity and suppresses TLR-mediated activation of NF-κB at, or downstream of, the TRAF6 signaling intermediate. A catalytically inactive mutant of this EBV protein did not reduce NF-κB activation, indicating that DUB activity is essential for attenuating TLR signal transduction. Our combined results show that EBV employs deubiquitination of signaling intermediates in the TLR cascade as a mechanism to counteract innate anti-viral immunity of infected hosts.

  4. Engineering signal peptides for enhanced protein secretion from Lactococcus lactis.

    Science.gov (United States)

    Ng, Daphne T W; Sarkar, Casim A

    2013-01-01

    Lactococcus lactis is an attractive vehicle for biotechnological production of proteins and clinical delivery of therapeutics. In many such applications using this host, it is desirable to maximize secretion of recombinant proteins into the extracellular space, which is typically achieved by using the native signal peptide from a major secreted lactococcal protein, Usp45. In order to further increase protein secretion from L. lactis, inherent limitations of the Usp45 signal peptide (Usp45sp) must be elucidated. Here, we performed extensive mutagenesis on Usp45sp to probe the effects of both the mRNA sequence (silent mutations) and the peptide sequence (amino acid substitutions) on secretion. We screened signal peptides based on their resulting secretion levels of Staphylococcus aureus nuclease and further evaluated them for secretion of Bacillus subtilis α-amylase. Silent mutations alone gave an increase of up to 16% in the secretion of α-amylase through a mechanism consistent with relaxed mRNA folding around the ribosome binding site and enhanced translation. Targeted amino acid mutagenesis in Usp45sp, combined with additional silent mutations from the best clone in the initial screen, yielded an increase of up to 51% in maximum secretion of α-amylase while maintaining secretion at lower induction levels. The best sequence from our screen preserves the tripartite structure of the native signal peptide but increases the positive charge of the n-region. Our study presents the first example of an engineered L. lactis signal peptide with a higher secretion yield than Usp45sp and, more generally, provides strategies for further enhancing protein secretion in bacterial hosts.

  5. Regulation of heterotrimeric G-protein signaling by NDPK/NME proteins and caveolins: an update.

    Science.gov (United States)

    Abu-Taha, Issam H; Heijman, Jordi; Feng, Yuxi; Vettel, Christiane; Dobrev, Dobromir; Wieland, Thomas

    2018-02-01

    Heterotrimeric G proteins are pivotal mediators of cellular signal transduction in eukaryotic cells and abnormal G-protein signaling plays an important role in numerous diseases. During the last two decades it has become evident that the activation status of heterotrimeric G proteins is both highly localized and strongly regulated by a number of factors, including a receptor-independent activation pathway of heterotrimeric G proteins that does not involve the classical GDP/GTP exchange and relies on nucleoside diphosphate kinases (NDPKs). NDPKs are NTP/NDP transphosphorylases encoded by the nme/nm23 genes that are involved in a variety of cellular events such as proliferation, migration, and apoptosis. They therefore contribute, for example, to tumor metastasis, angiogenesis, retinopathy, and heart failure. Interestingly, NDPKs are translocated and/or upregulated in human heart failure. Here we describe recent advances in the current understanding of NDPK functions and how they have an impact on local regulation of G-protein signaling.

  6. The antiviral protein human lactoferrin is distributed in the body to cytomegalovirus (CMV) infection-prone cells and tissues

    NARCIS (Netherlands)

    Beljaars, Leonie; Bakker, Hester I; van der Strate, Barry W A; Smit, Catharina; Duijvestijn, Adrian M; Meijer, Dirk K F; Molema, Grietje

    Purpose. Lactoferrin has anti-Cytomegalovirus (CMV) and -HIV properties in vitro. However, the pharmacokinetic behavior of the 80-kD protein has not been well defined. We, therefore, assessed the plasma decay and body distribution of lactoferrin after intravenous administration to freely moving

  7. The Human Cytomegalovirus Major Immediate-Early Proteins as Antagonists of Intrinsic and Innate Antiviral Host Responses

    Directory of Open Access Journals (Sweden)

    Michael Nevels

    2009-11-01

    Full Text Available The major immediate-early (IE gene of human cytomegalovirus (CMV is believed to have a decisive role in acute infection and its activity is an important indicator of viral reactivation from latency. Although a variety of gene products are expressed from this region, the 72-kDa IE1 and the 86-kDa IE2 nuclear phosphoproteins are the most abundant and important. Both proteins have long been recognized as promiscuous transcriptional regulators. More recently, a critical role of the IE1 and IE2 proteins in counteracting nonadaptive host cell defense mechanisms has been revealed. In this review we will briefly summarize the available literature on IE1- and IE2-dependent mechanisms contributing to CMV evasion from intrinsic and innate immune responses.

  8. Enhancing T cell activation and antiviral protection by introducing the HIV-1 protein transduction domain into a DNA vaccine.

    Science.gov (United States)

    Leifert, J A; Lindencrona, J A; Charo, J; Whitton, J L

    2001-10-10

    Protein transduction domains (PTD), which can transport proteins or peptides across biological membranes, have been identified in several proteins of viral, invertebrate, and vertebrate origin. Here, we evaluate the immunological and biological consequences of including PTD in synthetic peptides and in DNA vaccines that contain CD8(+) T cell epitopes from lymphocytic choriomeningitis virus (LCMV). Synthetic PTD-peptides did not induce detectable CD8(+) T cell responses. However, fusion of an open reading frame encoding a PTD to an epitope minigene caused transfected tissue culture cells to stimulate epitope-specific T cells much more effectively. Kinetic studies indicated that the epitope reached the surface of transfected cells more rapidly and that the number of transfected cells needed to stimulate T cell responses was reduced by 35- to 50-fold when compared to cells transfected with a standard minigene plasmid. The mechanism underlying the effect of PTD linkage is not clear, but transit of the PTD-attached epitope from transfected cells to nontransfected cells (cross presentation) seemed to play, at most, a minimal role. Mice immunized once with the plasmid encoding the PTD-linked epitope showed a markedly accelerated CD8(+) T cell response and, unlike mice immunized with a standard plasmid, were completely protected against a normally lethal LCMV challenge administered only 8 days post-immunization.

  9. Protein sensing by nanofluidic crystal and its signal enhancement

    Science.gov (United States)

    Sang, Jianming; Du, Hongtan; Wang, Wei; Chu, Ming; Wang, Yuedan; Li, Haichao; Alice Zhang, Haixia; Wu, Wengang; Li, Zhihong

    2013-01-01

    Nanofluidics has a unique property that ionic conductance across a nanometer-sized confined space is strongly affected by the space surface charge density, which can be utilized to construct electrical read-out biosensor. Based on this principle, this work demonstrated a novel protein sensor along with a sandwich signal enhancement approach. Nanoparticles with designed aptamer onside are assembled in a suspended micropore to form a 3-dimensional network of nanometer-sized interstices, named as nanofluidic crystal hereafter, as the basic sensing unit. Proteins captured by aptamers will change the surface charge density of nanoparticles and thereby can be detected by monitoring the ionic conductance across this nanofluidic crystal. Another aptamer can further enlarge the variations of the surface charge density by forming a sandwich structure (capturing aptamer/protein/signal enhancement aptamer) and the read-out conductance as well. The preliminary experimental results indicated that human α-thrombin was successfully detected by the corresponding aptamer modified nanofluidic crystal with the limit of detection of 5 nM (0.18 μg/ml) and the read-out signal was enhanced up to 3 folds by using another thrombin aptamer. Being easy to graft probe, facile and low-cost to prepare the nano-device, and having an electrical read-out, the present nanofluidic crystal scheme is a promising and universal strategy for protein sensing. PMID:24404017

  10. Molecular signaling involving intrinsically disordered proteins in prostate cancer

    Directory of Open Access Journals (Sweden)

    Anna Russo

    2016-01-01

    Full Text Available Investigations on cellular protein interaction networks (PINs reveal that proteins that constitute hubs in a PIN are notably enriched in Intrinsically Disordered Proteins (IDPs compared to proteins that constitute edges, highlighting the role of IDPs in signaling pathways. Most IDPs rapidly undergo disorder-to-order transitions upon binding to their biological targets to perform their function. Conformational dynamics enables IDPs to be versatile and to interact with a broad range of interactors under normal physiological conditions where their expression is tightly modulated. IDPs are involved in many cellular processes such as cellular signaling, transcriptional regulation, and splicing; thus, their high-specificity/low-affinity interactions play crucial roles in many human diseases including cancer. Prostate cancer (PCa is one of the leading causes of cancer-related mortality in men worldwide. Therefore, identifying molecular mechanisms of the oncogenic signaling pathways that are involved in prostate carcinogenesis is crucial. In this review, we focus on the aspects of cellular pathways leading to PCa in which IDPs exert a primary role.

  11. Identification and quantitation of signal molecule-dependent protein phosphorylation

    KAUST Repository

    Groen, Arnoud J.

    2013-09-03

    Phosphoproteomics is a fast-growing field that aims at characterizing phosphorylated proteins in a cell or a tissue at a given time. Phosphorylation of proteins is an important regulatory mechanism in many cellular processes. Gel-free phosphoproteome technique involving enrichment of phosphopeptide coupled with mass spectrometry has proven to be invaluable to detect and characterize phosphorylated proteins. In this chapter, a gel-free quantitative approach involving 15N metabolic labelling in combination with phosphopeptide enrichment by titanium dioxide (TiO2) and their identification by MS is described. This workflow can be used to gain insights into the role of signalling molecules such as cyclic nucleotides on regulatory networks through the identification and quantification of responsive phospho(proteins). © Springer Science+Business Media New York 2013.

  12. Regulation of protease-activated receptor 1 signaling by the adaptor protein complex 2 and R4 subfamily of regulator of G protein signaling proteins.

    Science.gov (United States)

    Chen, Buxin; Siderovski, David P; Neubig, Richard R; Lawson, Mark A; Trejo, Joann

    2014-01-17

    The G protein-coupled protease-activated receptor 1 (PAR1) is irreversibly proteolytically activated by thrombin. Hence, the precise regulation of PAR1 signaling is important for proper cellular responses. In addition to desensitization, internalization and lysosomal sorting of activated PAR1 are critical for the termination of signaling. Unlike most G protein-coupled receptors, PAR1 internalization is mediated by the clathrin adaptor protein complex 2 (AP-2) and epsin-1, rather than β-arrestins. However, the function of AP-2 and epsin-1 in the regulation of PAR1 signaling is not known. Here, we report that AP-2, and not epsin-1, regulates activated PAR1-stimulated phosphoinositide hydrolysis via two different mechanisms that involve, in part, a subset of R4 subfamily of "regulator of G protein signaling" (RGS) proteins. A significantly greater increase in activated PAR1 signaling was observed in cells depleted of AP-2 using siRNA or in cells expressing a PAR1 (420)AKKAA(424) mutant with defective AP-2 binding. This effect was attributed to AP-2 modulation of PAR1 surface expression and efficiency of G protein coupling. We further found that ectopic expression of R4 subfamily members RGS2, RGS3, RGS4, and RGS5 reduced activated PAR1 wild-type signaling, whereas signaling by the PAR1 AKKAA mutant was minimally affected. Intriguingly, siRNA-mediated depletion analysis revealed a function for RGS5 in the regulation of signaling by the PAR1 wild type but not the AKKAA mutant. Moreover, activation of the PAR1 wild type, and not the AKKAA mutant, induced Gαq association with RGS3 via an AP-2-dependent mechanism. Thus, AP-2 regulates activated PAR1 signaling by altering receptor surface expression and through recruitment of RGS proteins.

  13. Innate and intrinsic antiviral immunity in skin.

    Science.gov (United States)

    Kawamura, Tatsuyoshi; Ogawa, Youichi; Aoki, Rui; Shimada, Shinji

    2014-09-01

    As the body's most exposed interface with the environment, the skin is constantly challenged by potentially pathogenic microbes, including viruses. To sense the invading viruses, various types of cells resident in the skin express many different pattern-recognition receptors (PRRs) such as C-type lectin receptors (CLRs), Toll-like receptors (TLRs), nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs), retinoic acid-inducible gene I (RIG-I)-like receptors (RLRs) and cytosolic DNA sensors, that can detect the pathogen-associated molecular patterns (PAMPs) of the viruses. The detection of viral PAMPs initiates two major innate immune signaling cascades: the first involves the activation of the downstream transcription factors, such as interferon regulatory factors (IRFs), nuclear factor kappa B (NF-κB) and activator protein 1 (AP-1), which cooperate to induce the transcription of type I interferons and pro-inflammatory cytokines. The second signaling pathway involves the caspase-1-mediated processing of IL-1β and IL-18 through the formation of an inflammasome complex. Cutaneous innate immunity including the production of the innate cytokines constitutes the first line of host defence that limits the virus dissemination from the skin, and also plays an important role in the activation of adaptive immune response, which represents the second line of defence. More recently, the third immunity "intrinsic immunity" has emerged, that provides an immediate and direct antiviral defense mediated by host intrinsic restriction factors. This review focuses on the recent advances regarding the antiviral immune systems, highlighting the innate and intrinsic immunity against the viral infections in the skin, and describes how viral components are recognized by cutaneous immune systems. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  14. Nitrosothiol signaling and protein nitrosation in cell death.

    Science.gov (United States)

    Iyer, Anand Krishnan V; Rojanasakul, Yon; Azad, Neelam

    2014-11-15

    Nitric oxide, a reactive free radical, is an important signaling molecule that can lead to a plethora of cellular effects affecting homeostasis. A well-established mechanism by which NO manifests its effect on cellular functions is the post-translational chemical modification of cysteine thiols in substrate proteins by a process known as S-nitrosation. Studies that investigate regulation of cellular functions through NO have increasingly established S-nitrosation as the primary modulatory mechanism in their respective systems. There has been a substantial increase in the number of reports citing various candidate proteins undergoing S-nitrosation, which affects cell-death and -survival pathways in a number of tissues including heart, lung, brain and blood. With an exponentially growing list of proteins being identified as substrates for S-nitrosation, it is important to assimilate this information in different cell/tissue systems in order to gain an overall view of protein regulation of both individual proteins and a class of protein substrates. This will allow for broad mapping of proteins as a function of S-nitrosation, and help delineate their global effects on pathophysiological responses including cell death and survival. This information will not only provide a much better understanding of overall functional relevance of NO in the context of various disease states, it will also facilitate the generation of novel therapeutics to combat specific diseases that are driven by NO-mediated S-nitrosation. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Role of protein dynamics in transmembrane receptor signalling

    DEFF Research Database (Denmark)

    Wang, Yong; Bugge, Katrine Østergaard; Kragelund, Birthe Brandt

    2018-01-01

    Cells are dependent on transmembrane receptors to communicate and transform chemical and physical signals into intracellular responses. Because receptors transport 'information', conformational changes and protein dynamics play a key mechanistic role. We here review examples where experiment...... to function. Because the receptors function in a heterogeneous environment and need to be able to switch between distinct functional states, they may be particularly sensitive to small perturbations that complicate studies linking dynamics to function....

  16. Protein kinase C signaling and cell cycle regulation

    OpenAIRE

    Black, Adrian R.; Black, Jennifer D.

    2013-01-01

    A link between T cell proliferation and the protein kinase C (PKC) family of serine/threonine kinases has been recognized for about thirty years. However, despite the wealth of information on PKC-mediated control of T cell activation, understanding of the effects of PKCs on the cell cycle machinery in this cell type remains limited. Studies in other systems have revealed important cell cycle-specific effects of PKC signaling that can either positively or negatively impact proliferation. Th...

  17. Duplicate retention in signalling proteins and constraints from network dynamics.

    Science.gov (United States)

    Soyer, O S; Creevey, C J

    2010-11-01

    Duplications are a major driving force behind evolution. Most duplicates are believed to fix through genetic drift, but it is not clear whether this process affects all duplications equally or whether there are certain gene families that are expected to show neutral expansions under certain circumstances. Here, we analyse the neutrality of duplications in different functional classes of signalling proteins based on their effects on response dynamics. We find that duplications involving intermediary proteins in a signalling network are neutral more often than those involving receptors. Although the fraction of neutral duplications in all functional classes increase with decreasing population size and selective pressure on dynamics, this effect is most pronounced for receptors, indicating a possible expansion of receptors in species with small population size. In line with such an expectation, we found a statistically significant increase in the number of receptors as a fraction of genome size in eukaryotes compared with prokaryotes. Although not confirmative, these results indicate that neutral processes can be a significant factor in shaping signalling networks and affect proteins from different functional classes differently. © 2010 The Authors. Journal Compilation © 2010 European Society For Evolutionary Biology.

  18. P-Finder: Reconstruction of Signaling Networks from Protein-Protein Interactions and GO Annotations.

    Science.gov (United States)

    Young-Rae Cho; Yanan Xin; Speegle, Greg

    2015-01-01

    Because most complex genetic diseases are caused by defects of cell signaling, illuminating a signaling cascade is essential for understanding their mechanisms. We present three novel computational algorithms to reconstruct signaling networks between a starting protein and an ending protein using genome-wide protein-protein interaction (PPI) networks and gene ontology (GO) annotation data. A signaling network is represented as a directed acyclic graph in a merged form of multiple linear pathways. An advanced semantic similarity metric is applied for weighting PPIs as the preprocessing of all three methods. The first algorithm repeatedly extends the list of nodes based on path frequency towards an ending protein. The second algorithm repeatedly appends edges based on the occurrence of network motifs which indicate the link patterns more frequently appearing in a PPI network than in a random graph. The last algorithm uses the information propagation technique which iteratively updates edge orientations based on the path strength and merges the selected directed edges. Our experimental results demonstrate that the proposed algorithms achieve higher accuracy than previous methods when they are tested on well-studied pathways of S. cerevisiae. Furthermore, we introduce an interactive web application tool, called P-Finder, to visualize reconstructed signaling networks.

  19. S-Glutathionylation and Redox Protein Signaling in Drug Addiction.

    Science.gov (United States)

    Womersley, Jacqueline S; Uys, Joachim D

    2016-01-01

    Drug addiction is a chronic relapsing disorder that comes at a high cost to individuals and society. Therefore understanding the mechanisms by which drugs exert their effects is of prime importance. Drugs of abuse increase the production of reactive oxygen and nitrogen species resulting in oxidative stress. This change in redox homeostasis increases the conjugation of glutathione to protein cysteine residues; a process called S-glutathionylation. Although traditionally regarded as a protective mechanism against irreversible protein oxidation, accumulated evidence suggests a more nuanced role for S-glutathionylation, namely as a mediator in redox-sensitive protein signaling. The reversible modification of protein thiols leading to alteration in function under different physiologic/pathologic conditions provides a mechanism whereby change in redox status can be translated into a functional response. As such, S-glutathionylation represents an understudied means of post-translational protein modification that may be important in the mechanisms underlying drug addiction. This review will discuss the evidence for S-glutathionylation as a redox-sensing mechanism and how this may be involved in the response to drug-induced oxidative stress. The function of S-glutathionylated proteins involved in neurotransmission, dendritic spine structure, and drug-induced behavioral outputs will be reviewed with specific reference to alcohol, cocaine, and heroin. Copyright © 2016. Published by Elsevier Inc.

  20. 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).

  1. The Hedgehog Signal Induced Modulation of Bone Morphogenetic Protein Signaling: An Essential Signaling Relay for Urinary Tract Morphogenesis

    Science.gov (United States)

    Nakagata, Naomi; Miyagawa, Shinichi; Suzuki, Kentaro; Kitazawa, Sohei; Yamada, Gen

    2012-01-01

    Background Congenital diseases of the urinary tract are frequently observed in infants. Such diseases present a number of developmental anomalies such as hydroureter and hydronephrosis. Although some genetically-modified mouse models of growth factor signaling genes reproduce urinary phenotypes, the pathogenic mechanisms remain obscure. Previous studies suggest that a portion of the cells in the external genitalia and bladder are derived from peri-cloacal mesenchymal cells that receive Hedgehog (Hh) signaling in the early developmental stages. We hypothesized that defects in such progenitor cells, which give rise to urinary tract tissues, may be a cause of such diseases. Methodology/Principal Findings To elucidate the pathogenic mechanisms of upper urinary tract malformations, we analyzed a series of Sonic hedgehog (Shh) deficient mice. Shh−/− displayed hydroureter and hydronephrosis phenotypes and reduced expression of several developmental markers. In addition, we suggested that Shh modulation at an early embryonic stage is responsible for such phenotypes by analyzing the Shh conditional mutants. Tissue contribution assays of Hh-responsive cells revealed that peri-cloacal mesenchymal cells, which received Hh signal secreted from cloacal epithelium, could contribute to the ureteral mesenchyme. Gain- and loss-of-functional mutants for Hh signaling revealed a correlation between Hh signaling and Bone morphogenetic protein (Bmp) signaling. Finally, a conditional ablation of Bmp receptor type IA (BmprIA) gene was examined in Hh-responsive cell lineages. This system thus made it possible to analyze the primary functions of the growth factor signaling relay. The defective Hh-to-Bmp signaling relay resulted in severe urinary tract phenotypes with a decrease in the number of Hh-responsive cells. Conclusions/Significance This study identified the essential embryonic stages for the pathogenesis of urinary tract phenotypes. These results suggested that Hh

  2. Promotion of bone morphogenetic protein signaling by tetraspanins and glycosphingolipids.

    Directory of Open Access Journals (Sweden)

    Zhiyu Liu

    2015-05-01

    Full Text Available Bone morphogenetic proteins (BMPs belong to the transforming growth factor β (TGFβ superfamily of secreted molecules. BMPs play essential roles in multiple developmental and homeostatic processes in metazoans. Malfunction of the BMP pathway can cause a variety of diseases in humans, including cancer, skeletal disorders and cardiovascular diseases. Identification of factors that ensure proper spatiotemporal control of BMP signaling is critical for understanding how this pathway is regulated. We have used a unique and sensitive genetic screen to identify the plasma membrane-localized tetraspanin TSP-21 as a key new factor in the C. elegans BMP-like "Sma/Mab" signaling pathway that controls body size and postembryonic M lineage development. We showed that TSP-21 acts in the signal-receiving cells and genetically functions at the ligand-receptor level. We further showed that TSP-21 can associate with itself and with two additional tetraspanins, TSP-12 and TSP-14, which also promote Sma/Mab signaling. TSP-12 and TSP-14 can also associate with SMA-6, the type I receptor of the Sma/Mab pathway. Finally, we found that glycosphingolipids, major components of the tetraspanin-enriched microdomains, are required for Sma/Mab signaling. Our findings suggest that the tetraspanin-enriched membrane microdomains are important for proper BMP signaling. As tetraspanins have emerged as diagnostic and prognostic markers for tumor progression, and TSP-21, TSP-12 and TSP-14 are all conserved in humans, we speculate that abnormal BMP signaling due to altered expression or function of certain tetraspanins may be a contributing factor to cancer development.

  3. Induction of the unfolded protein response by constitutive G-protein signaling in rod photoreceptor cells.

    Science.gov (United States)

    Wang, Tian; Chen, Jeannie

    2014-10-17

    Phototransduction is a G-protein signal transduction cascade that converts photon absorption to a change in current at the plasma membrane. Certain genetic mutations affecting the proteins in the phototransduction cascade cause blinding disorders in humans. Some of these mutations serve as a genetic source of "equivalent light" that activates the cascade, whereas other mutations lead to amplification of the light response. How constitutive phototransduction causes photoreceptor cell death is poorly understood. We showed that persistent G-protein signaling, which occurs in rod arrestin and rhodopsin kinase knock-out mice, caused a rapid and specific induction of the PERK pathway of the unfolded protein response. These changes were not observed in the cGMP-gated channel knock-out rods, an equivalent light condition that mimics light-stimulated channel closure. Thus transducin signaling, but not channel closure, triggers rapid cell death in light damage caused by constitutive phototransduction. Additionally, we show that in the albino light damage model cell death was not associated with increase in global protein ubiquitination or unfolded protein response induction. Taken together, these observations provide novel mechanistic insights into the cell death pathway caused by constitutive phototransduction and identify the unfolded protein response as a potential target for therapeutic intervention. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  4. Systematic Prediction of Scaffold Proteins Reveals New Design Principles in Scaffold-Mediated Signal Transduction

    Science.gov (United States)

    Hu, Jianfei; Neiswinger, Johnathan; Zhang, Jin; Zhu, Heng; Qian, Jiang

    2015-01-01

    Scaffold proteins play a crucial role in facilitating signal transduction in eukaryotes by bringing together multiple signaling components. In this study, we performed a systematic analysis of scaffold proteins in signal transduction by integrating protein-protein interaction and kinase-substrate relationship networks. We predicted 212 scaffold proteins that are involved in 605 distinct signaling pathways. The computational prediction was validated using a protein microarray-based approach. The predicted scaffold proteins showed several interesting characteristics, as we expected from the functionality of scaffold proteins. We found that the scaffold proteins are likely to interact with each other, which is consistent with previous finding that scaffold proteins tend to form homodimers and heterodimers. Interestingly, a single scaffold protein can be involved in multiple signaling pathways by interacting with other scaffold protein partners. Furthermore, we propose two possible regulatory mechanisms by which the activity of scaffold proteins is coordinated with their associated pathways through phosphorylation process. PMID:26393507

  5. Activated protein synthesis and suppressed protein breakdown signaling in skeletal muscle of critically ill patients.

    Directory of Open Access Journals (Sweden)

    Jakob G Jespersen

    Full Text Available BACKGROUND: Skeletal muscle mass is controlled by myostatin and Akt-dependent signaling on mammalian target of rapamycin (mTOR, glycogen synthase kinase 3β (GSK3β and forkhead box O (FoxO pathways, but it is unknown how these pathways are regulated in critically ill human muscle. To describe factors involved in muscle mass regulation, we investigated the phosphorylation and expression of key factors in these protein synthesis and breakdown signaling pathways in thigh skeletal muscle of critically ill intensive care unit (ICU patients compared with healthy controls. METHODOLOGY/PRINCIPAL FINDINGS: ICU patients were systemically inflamed, moderately hyperglycemic, received insulin therapy, and showed a tendency to lower plasma branched chain amino acids compared with controls. Using Western blotting we measured Akt, GSK3β, mTOR, ribosomal protein S6 kinase (S6k, eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1, and muscle ring finger protein 1 (MuRF1; and by RT-PCR we determined mRNA expression of, among others, insulin-like growth factor 1 (IGF-1, FoxO 1, 3 and 4, atrogin1, MuRF1, interleukin-6 (IL-6, tumor necrosis factor α (TNF-α and myostatin. Unexpectedly, in critically ill ICU patients Akt-mTOR-S6k signaling was substantially higher compared with controls. FoxO1 mRNA was higher in patients, whereas FoxO3, atrogin1 and myostatin mRNAs and MuRF1 protein were lower compared with controls. A moderate correlation (r2=0.36, p<0.05 between insulin infusion dose and phosphorylated Akt was demonstrated. CONCLUSIONS/SIGNIFICANCE: We present for the first time muscle protein turnover signaling in critically ill ICU patients, and we show signaling pathway activity towards a stimulation of muscle protein synthesis and a somewhat inhibited proteolysis.

  6. Signal peptide of eosinophil cationic protein is toxic to cells lacking signal peptide peptidase

    International Nuclear Information System (INIS)

    Wu, C.-M.; Chang, Margaret Dah-Tsyr

    2004-01-01

    Eosinophil cationic protein (ECP) is a toxin secreted by activated human eosinophils. The properties of mature ECP have been well studied but those of the signal peptide of ECP (ECPsp) are not clear. In this study, several chimeric proteins containing N-terminal fusion of ECPsp were generated, and introduced into Escherichia coli, Pichia pastoris, and human epidermoid carcinoma cell line A431 to study the function of ECPsp. We found that expression of ECPsp chimeric proteins inhibited the growth of E. coli and P. pastoris but not A431 cells. Primary sequence analysis and in vitro transcription/translation of ECPsp have revealed that it is a potential substrate for human signal peptide peptidase (hSPP), an intramembrane protease located in endoplasmic reticulum. In addition, knockdown of the hSPP mRNA expression in ECPsp-eGFP/A431 cells caused the growth inhibitory effect, whereas complementally expression of hSPP in P. pastoris system rescued the cell growth. Taken together, we have demonstrated that ECPsp is a toxic signal peptide, and expression of hSPP protects the cells from growth inhibition

  7. Smallpox Antiviral Drug

    Science.gov (United States)

    2007-01-01

    Candida albicans] A G1L (590 aa) Flag VV(WR) 30/ENDIDEILGIAHLLEHLLISF/50 107/HIKELENEYYFRNEVFH/123 H41A 30/ENDIDEILGIAALLEHLLISF/50 107...RSV) (Table 1). Additional antiviral drug examples include the use of interferon for human papilloma virus ( HPV ) [Cantell, 1995]. Antivirals are most...low oral bioavailability, and quick elimination from plasma [Ghosn et al., 2004; Hostetler et al., 1994; Kempf et al., 1991; Matsumoto et al., 2001

  8. JNK Signaling: Regulation and Functions Based on Complex Protein-Protein Partnerships

    Science.gov (United States)

    Zeke, András; Misheva, Mariya

    2016-01-01

    SUMMARY The c-Jun N-terminal kinases (JNKs), as members of the mitogen-activated protein kinase (MAPK) family, mediate eukaryotic cell responses to a wide range of abiotic and biotic stress insults. JNKs also regulate important physiological processes, including neuronal functions, immunological actions, and embryonic development, via their impact on gene expression, cytoskeletal protein dynamics, and cell death/survival pathways. Although the JNK pathway has been under study for >20 years, its complexity is still perplexing, with multiple protein partners of JNKs underlying the diversity of actions. Here we review the current knowledge of JNK structure and isoforms as well as the partnerships of JNKs with a range of intracellular proteins. Many of these proteins are direct substrates of the JNKs. We analyzed almost 100 of these target proteins in detail within a framework of their classification based on their regulation by JNKs. Examples of these JNK substrates include a diverse assortment of nuclear transcription factors (Jun, ATF2, Myc, Elk1), cytoplasmic proteins involved in cytoskeleton regulation (DCX, Tau, WDR62) or vesicular transport (JIP1, JIP3), cell membrane receptors (BMPR2), and mitochondrial proteins (Mcl1, Bim). In addition, because upstream signaling components impact JNK activity, we critically assessed the involvement of signaling scaffolds and the roles of feedback mechanisms in the JNK pathway. Despite a clarification of many regulatory events in JNK-dependent signaling during the past decade, many other structural and mechanistic insights are just beginning to be revealed. These advances open new opportunities to understand the role of JNK signaling in diverse physiological and pathophysiological states. PMID:27466283

  9. Heartland virus NSs protein disrupts host defenses by blocking the TBK1 kinase-IRF3 transcription factor interaction and signaling required for interferon induction.

    Science.gov (United States)

    Ning, Yun-Jia; Feng, Kuan; Min, Yuan-Qin; Deng, Fei; Hu, Zhihong; Wang, Hualin

    2017-10-06

    Heartland virus (HRTV) is a pathogenic phlebovirus related to the severe fever with thrombocytopenia syndrome virus (SFTSV), another phlebovirus causing life-threatening disease in humans. Previous findings have suggested that SFTSV can antagonize the host interferon (IFN) system via viral nonstructural protein (NSs)-mediated sequestration of antiviral signaling proteins into NSs-induced inclusion bodies. However, whether and how HRTV counteracts the host innate immunity is unknown. Here, we report that HRTV NSs (HNSs) also antagonizes IFN and cytokine induction and bolsters viral replication, although no noticeable inclusion body formation was observed in HNSs-expressing cells. Furthermore, HNSs inhibited the virus-triggered activation of IFN-β promoter by specifically targeting the IFN-stimulated response element but not the NF-κB response element. Consistently, HNSs blocked the phosphorylation and nuclear translocation of IFN regulatory factor 3 (IRF3, an IFN-stimulated response element-activating transcription factor). Reporter gene assays next showed that HNSs blockades the antiviral signaling mediated by RIG-I-like receptors likely at the level of TANK-binding kinase 1 (TBK1). Indeed, HNSs strongly interacts with TBK1 as indicated by confocal microscopy and pulldown analyses, and we also noted that the scaffold dimerization domain of TBK1 is required for the TBK1-HNSs interaction. Finally, pulldown assays demonstrated that HNSs expression dose-dependently diminishes a TBK1-IRF3 interaction, further explaining the mechanism for HNSs function. Collectively, these data suggest that HNSs, an antagonist of host innate immunity, interacts with TBK1 and thereby hinders the association of TBK1 with its substrate IRF3, thus blocking IRF3 activation and transcriptional induction of the cellular antiviral responses. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. Direct-acting Antivirals in Kidney Transplant Patients: Successful Hepatitis C Treatment and Short Term Reduction in Urinary Protein/Creatinine Ratios

    Directory of Open Access Journals (Sweden)

    Michael R. Goetsch

    2017-09-01

    Full Text Available Introduction: The role of Hepatitis C Virus (HCV clearance in long-term kidney graft survival is unknown. In this study, we examined short-term trends of urinary protein/creatinine (P/C ratios in a cohort of HCV-infected kidney transplant recipients with stable graft function and treated with direct-acting antivirals (DAAs. Methods: We conducted a retrospective study of 19 kidney transplant patients with chronic HCV infection treated with DAAs at the University of Alabama at Birmingham 1917 Viral Hepatitis Clinic between January 2013 and June 2016. Markers of glomerular damage were assessed using average protein/creatinine (P/C ratios measured pre- and post-treatment. We also described treatment efficacy using sustained virologic response at 12 weeks post-HCV treatment (SVR12. Results: The median age of the 19 patients included was 59 years (Q1=58, Q3=64 at completion of treatment. Of these patients, 68% were African American, 32% were White and 63% were male. The median time between kidney transplant and initiation of DAA therapy was 2.25 years (Q1=0.79, Q3=3.79. Post-treatment P/C ratios (median=0.127, Q1=0.090, Q3=0.220 were significantly lower (p=0.01 than pre-treatment ratios (median=0.168, Q1=0.118, Q3=0.385. P/C ratios decreased in 14 of 19 patients (74% with median change of -0.072 (median percent change= -40%. Post-treatment eGFRs (median=58.9, Q1=48.9, Q3=72.3 were not significantly different (p=0.82 than the pre-treatment values (median=57.0, Q1=48.8, Q3=67.8. Conclusions: In this preliminary study, there was a statistically significant decrease in P/C ratios associated with HCV clearance, suggesting a potential role for DAAs in improving kidney graft survival. Larger cohort studies will be needed to assess the clinical and long-term benefits of DAAs in this special population of HCV infected patients.

  11. Integration of G protein α (Gα) signaling by the regulator of G protein signaling 14 (RGS14).

    Science.gov (United States)

    Brown, Nicole E; Goswami, Devrishi; Branch, Mary Rose; Ramineni, Suneela; Ortlund, Eric A; Griffin, Patrick R; Hepler, John R

    2015-04-03

    RGS14 contains distinct binding sites for both active (GTP-bound) and inactive (GDP-bound) forms of Gα subunits. The N-terminal regulator of G protein signaling (RGS) domain binds active Gαi/o-GTP, whereas the C-terminal G protein regulatory (GPR) motif binds inactive Gαi1/3-GDP. The molecular basis for how RGS14 binds different activation states of Gα proteins to integrate G protein signaling is unknown. Here we explored the intramolecular communication between the GPR motif and the RGS domain upon G protein binding and examined whether RGS14 can functionally interact with two distinct forms of Gα subunits simultaneously. Using complementary cellular and biochemical approaches, we demonstrate that RGS14 forms a stable complex with inactive Gαi1-GDP at the plasma membrane and that free cytosolic RGS14 is recruited to the plasma membrane by activated Gαo-AlF4(-). Bioluminescence resonance energy transfer studies showed that RGS14 adopts different conformations in live cells when bound to Gα in different activation states. Hydrogen/deuterium exchange mass spectrometry revealed that RGS14 is a very dynamic protein that undergoes allosteric conformational changes when inactive Gαi1-GDP binds the GPR motif. Pure RGS14 forms a ternary complex with Gαo-AlF4(-) and an AlF4(-)-insensitive mutant (G42R) of Gαi1-GDP, as observed by size exclusion chromatography and differential hydrogen/deuterium exchange. Finally, a preformed RGS14·Gαi1-GDP complex exhibits full capacity to stimulate the GTPase activity of Gαo-GTP, demonstrating that RGS14 can functionally engage two distinct forms of Gα subunits simultaneously. Based on these findings, we propose a working model for how RGS14 integrates multiple G protein signals in host CA2 hippocampal neurons to modulate synaptic plasticity. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  12. A membrane protein / signaling protein interaction network for Arabidopsis version AMPv2

    Directory of Open Access Journals (Sweden)

    Sylvie Lalonde

    2010-09-01

    Full Text Available Interactions between membrane proteins and the soluble fraction are essential for signal transduction and for regulating nutrient transport. To gain insights into the membrane-based interactome, 3,852 open reading frames (ORFs out of a target list of 8,383 representing membrane and signaling proteins from Arabidopsis thaliana were cloned into a Gateway compatible vector. The mating-based split-ubiquitin system was used to screen for potential protein-protein interactions (pPPIs among 490 Arabidopsis ORFs. A binary robotic screen between 142 receptor-like kinases, 72 transporters, 57 soluble protein kinases and phosphatases, 40 glycosyltransferases, 95 proteins of various functions and 89 proteins with unknown function detected 387 out of 90,370 possible PPIs. A secondary screen confirmed 343 (of 387 pPPIs between 179 proteins, yielding a scale-free network (r2=0.863. Eighty of 142 transmembrane receptor-like kinases (RLK tested positive, identifying three homomers, 63 heteromers and 80 pPPIs with other proteins. Thirty-one out of 142 RLK interactors (including RLKs had previously been found to be phosphorylated; thus interactors may be substrates for respective RLKs. None of the pPPIs described here had been reported in the major interactome databases, including potential interactors of G protein-coupled receptors, phospholipase C, and AMT ammonium transporters. Two RLKs found as putative interactors of AMT1;1 were independently confirmed using a split luciferase assay in Arabidopsis protoplasts. These RLKs may be involved in ammonium-dependent phosphorylation of the C-terminus and regulation of ammonium uptake activity. The robotic screening method established here will enable a systematic analysis of membrane protein interactions in fungi, plants and metazoa.

  13. Heat Shock Proteins as Danger Signals for Cancer Detection

    International Nuclear Information System (INIS)

    Seigneuric, Renaud; Mjahed, Hajare; Gobbo, Jessica; Joly, Anne-Laure; Berthenet, Kevin; Shirley, Sarah; Garrido, Carmen

    2011-01-01

    First discovered in 1962, heat shock proteins (HSPs) are highly studied with about 35,500 publications on the subject to date. HSPs are highly conserved, function as molecular chaperones for a large panel of “client” proteins and have strong cytoprotective properties. Induced by many different stress signals, they promote cell survival in adverse conditions. Therefore, their roles have been investigated in several conditions and pathologies where HSPs accumulate, such as in cancer. Among the diverse mammalian HSPs, some members share several features that may qualify them as cancer biomarkers. This review focuses mainly on three inducible HSPs: HSP27, HPS70, and HSP90. Our survey of recent literature highlights some recurring weaknesses in studies of the HSPs, but also identifies findings that indicate that some HSPs have potential as cancer biomarkers for successful clinical applications.

  14. Heparan sulfate proteoglycans: structure, protein interactions and cell signaling

    Directory of Open Access Journals (Sweden)

    Juliana L. Dreyfuss

    2009-09-01

    Full Text Available Heparan sulfate proteoglycans are ubiquitously found at the cell surface and extracellular matrix in all the animal species. This review will focus on the structural characteristics of the heparan sulfate proteoglycans related to protein interactions leading to cell signaling. The heparan sulfate chains due to their vast structural diversity are able to bind and interact with a wide variety of proteins, such as growth factors, chemokines, morphogens, extracellular matrix components, enzymes, among others. There is a specificity directing the interactions of heparan sulfates and target proteins, regarding both the fine structure of the polysaccharide chain as well precise protein motifs. Heparan sulfates play a role in cellular signaling either as receptor or co-receptor for different ligands, and the activation of downstream pathways is related to phosphorylation of different cytosolic proteins either directly or involving cytoskeleton interactions leading to gene regulation. The role of the heparan sulfate proteoglycans in cellular signaling and endocytic uptake pathways is also discussed.Proteoglicanos de heparam sulfato são encontrados tanto superfície celular quanto na matriz extracelular em todas as espécies animais. Esta revisão tem enfoque nas características estruturais dos proteoglicanos de heparam sulfato e nas interações destes proteoglicanos com proteínas que levam à sinalização celular. As cadeias de heparam sulfato, devido a sua variedade estrutural, são capazes de se ligar e interagir com ampla gama de proteínas, como fatores de crescimento, quimiocinas, morfógenos, componentes da matriz extracelular, enzimas, entreoutros. Existe uma especificidade estrutural que direciona as interações dos heparam sulfatos e proteínas alvo. Esta especificidade está relacionada com a estrutura da cadeia do polissacarídeo e os motivos conservados da cadeia polipeptídica das proteínas envolvidas nesta interação. Os heparam

  15. Two Chimeric Regulators of G-protein Signaling (RGS) Proteins Differentially Modulate Soybean Heterotrimeric G-protein Cycle*

    Science.gov (United States)

    Roy Choudhury, Swarup; Westfall, Corey S.; Laborde, John P.; Bisht, Naveen C.; Jez, Joseph M.; Pandey, Sona

    2012-01-01

    Heterotrimeric G-proteins and the regulator of G-protein signaling (RGS) proteins, which accelerate the inherent GTPase activity of Gα proteins, are common in animals and encoded by large gene families; however, in plants G-protein signaling is thought to be more limited in scope. For example, Arabidopsis thaliana contains one Gα, one Gβ, three Gγ, and one RGS protein. Recent examination of the Glycine max (soybean) genome reveals a larger set of G-protein-related genes and raises the possibility of more intricate G-protein networks than previously observed in plants. Stopped-flow analysis of GTP-binding and GDP/GTP exchange for the four soybean Gα proteins (GmGα1–4) reveals differences in their kinetic properties. The soybean genome encodes two chimeric RGS proteins with an N-terminal seven transmembrane domain and a C-terminal RGS box. Both GmRGS interact with each of the four GmGα and regulate their GTPase activity. The GTPase-accelerating activities of GmRGS1 and -2 differ for each GmGα, suggesting more than one possible rate of the G-protein cycle initiated by each of the Gα proteins. The differential effects of GmRGS1 and GmRGS2 on GmGα1–4 result from a single valine versus alanine difference. The emerging picture suggests complex regulation of the G-protein cycle in soybean and in other plants with expanded G-protein networks. PMID:22474294

  16. The V protein of Tioman virus is incapable of blocking type I interferon signaling in human cells.

    Directory of Open Access Journals (Sweden)

    Grégory Caignard

    Full Text Available The capacity of a virus to cross species barriers is determined by the development of bona fide interactions with cellular components of new hosts, and in particular its ability to block IFN-α/β antiviral signaling. Tioman virus (TioV, a close relative of mumps virus (MuV, has been isolated in giant fruit bats in Southeast Asia. Nipah and Hendra viruses, which are present in the same bat colonies, are highly pathogenic in human. Despite serological evidences of close contacts between TioV and human populations, whether TioV is associated to some human pathology remains undetermined. Here we show that in contrast to the V protein of MuV, the V protein of TioV (TioV-V hardly interacts with human STAT2, does not degrade STAT1, and cannot block IFN-α/β signaling in human cells. In contrast, TioV-V properly binds to human STAT3 and MDA5, and thus interferes with IL-6 signaling and IFN-β promoter induction in human cells. Because STAT2 binding was previously identified as a host restriction factor for some Paramyxoviridae, we established STAT2 sequence from giant fruit bats, and binding to TioV-V was tested. Surprisingly, TioV-V interaction with STAT2 from giant fruit bats is also extremely weak and barely detectable. Altogether, our observations question the capacity of TioV to appropriately control IFN-α/β signaling in both human and giant fruit bats that are considered as its natural host.

  17. Calcium-Dependent Protein Kinases in Phytohormone Signaling Pathways

    Directory of Open Access Journals (Sweden)

    Wuwu Xu

    2017-11-01

    Full Text Available Calcium-dependent protein kinases (CPKs/CDPKs are Ca2+-sensors that decode Ca2+ signals into specific physiological responses. Research has reported that CDPKs constitute a large multigene family in various plant species, and play diverse roles in plant growth, development, and stress responses. Although numerous CDPKs have been exhaustively studied, and many of them have been found to be involved in plant hormone biosynthesis and response mechanisms, a comprehensive overview of the manner in which CDPKs participate in phytohormone signaling pathways, regulating nearly all aspects of plant growth, has not yet been undertaken. In this article, we reviewed the structure of CDPKs and the mechanism of their subcellular localization. Some CDPKs were elucidated to influence the intracellular localization of their substrates. Since little work has been done on the interaction between CDPKs and cytokinin signaling pathways, or on newly defined phytohormones such as brassinosteroids, strigolactones and salicylic acid, this paper mainly focused on discussing the integral associations between CDPKs and five plant hormones: auxins, gibberellins, ethylene, jasmonates, and abscisic acid. A perspective on future work is provided at the end.

  18. Kinome signaling through regulated protein-protein interactions in normal and cancer cells.

    Science.gov (United States)

    Pawson, Tony; Kofler, Michael

    2009-04-01

    The flow of molecular information through normal and oncogenic signaling pathways frequently depends on protein phosphorylation, mediated by specific kinases, and the selective binding of the resulting phosphorylation sites to interaction domains present on downstream targets. This physical and functional interplay of catalytic and interaction domains can be clearly seen in cytoplasmic tyrosine kinases such as Src, Abl, Fes, and ZAP-70. Although the kinase and SH2 domains of these proteins possess similar intrinsic properties of phosphorylating tyrosine residues or binding phosphotyrosine sites, they also undergo intramolecular interactions when linked together, in a fashion that varies from protein to protein. These cooperative interactions can have diverse effects on substrate recognition and kinase activity, and provide a variety of mechanisms to link the stimulation of catalytic activity to substrate recognition. Taken together, these data have suggested how protein kinases, and the signaling pathways in which they are embedded, can evolve complex properties through the stepwise linkage of domains within single polypeptides or multi-protein assemblies.

  19. Antiviral Defense Mechanisms in Honey Bees

    Science.gov (United States)

    Brutscher, Laura M.; Daughenbaugh, Katie F.; Flenniken, Michelle L.

    2015-01-01

    Honey bees are significant pollinators of agricultural crops and other important plant species. High annual losses of honey bee colonies in North America and in some parts of Europe have profound ecological and economic implications. Colony losses have been attributed to multiple factors including RNA viruses, thus understanding bee antiviral defense mechanisms may result in the development of strategies that mitigate colony losses. Honey bee antiviral defense mechanisms include RNA-interference, pathogen-associated molecular pattern (PAMP) triggered signal transduction cascades, and reactive oxygen species generation. However, the relative importance of these and other pathways is largely uncharacterized. Herein we review the current understanding of honey bee antiviral defense mechanisms and suggest important avenues for future investigation. PMID:26273564

  20. Finding undetected protein associations in cell signaling by belief propagation.

    Science.gov (United States)

    Bailly-Bechet, M; Borgs, C; Braunstein, A; Chayes, J; Dagkessamanskaia, A; François, J-M; Zecchina, R

    2011-01-11

    External information propagates in the cell mainly through signaling cascades and transcriptional activation, allowing it to react to a wide spectrum of environmental changes. High-throughput experiments identify numerous molecular components of such cascades that may, however, interact through unknown partners. Some of them may be detected using data coming from the integration of a protein-protein interaction network and mRNA expression profiles. This inference problem can be mapped onto the problem of finding appropriate optimal connected subgraphs of a network defined by these datasets. The optimization procedure turns out to be computationally intractable in general. Here we present a new distributed algorithm for this task, inspired from statistical physics, and apply this scheme to alpha factor and drug perturbations data in yeast. We identify the role of the COS8 protein, a member of a gene family of previously unknown function, and validate the results by genetic experiments. The algorithm we present is specially suited for very large datasets, can run in parallel, and can be adapted to other problems in systems biology. On renowned benchmarks it outperforms other algorithms in the field.

  1. Activated protein synthesis and suppressed protein breakdown signaling in skeletal muscle of critically ill patients

    DEFF Research Database (Denmark)

    Jespersen, Jakob G; Nedergaard, Anders; Reitelseder, Søren

    2011-01-01

    Skeletal muscle mass is controlled by myostatin and Akt-dependent signaling on mammalian target of rapamycin (mTOR), glycogen synthase kinase 3β (GSK3β) and forkhead box O (FoxO) pathways, but it is unknown how these pathways are regulated in critically ill human muscle. To describe factors invol...... involved in muscle mass regulation, we investigated the phosphorylation and expression of key factors in these protein synthesis and breakdown signaling pathways in thigh skeletal muscle of critically ill intensive care unit (ICU) patients compared with healthy controls....

  2. Activated protein synthesis and suppressed protein breakdown signaling in skeletal muscle of critically ill patients

    DEFF Research Database (Denmark)

    Jespersen, Jakob G; Nedergaard, Anders; Reitelseder, Søren

    2011-01-01

    Skeletal muscle mass is controlled by myostatin and Akt-dependent signaling on mammalian target of rapamycin (mTOR), glycogen synthase kinase 3ß (GSK3ß) and forkhead box O (FoxO) pathways, but it is unknown how these pathways are regulated in critically ill human muscle. To describe factors invol...... involved in muscle mass regulation, we investigated the phosphorylation and expression of key factors in these protein synthesis and breakdown signaling pathways in thigh skeletal muscle of critically ill intensive care unit (ICU) patients compared with healthy controls....

  3. Ophthalmic antiviral chemotherapy : An overview

    Directory of Open Access Journals (Sweden)

    Athmanathan Sreedharan

    1997-01-01

    Full Text Available Antiviral drug development has been slow due to many factors. One such factor is the difficulty to block the viral replication in the cell without adversely affecting the host cell metabolic activity. Most of the antiviral compounds are analogs of purines and pyramidines. Currently available antiviral drugs mainly inhibit viral nucleic acid synthesis, hence act only on actively replicating viruses. This article presents an overview of some of the commonly used antiviral agents in clinical ophthalmology.

  4. Antiviral Drugs: Seasonal Flu

    Centers for Disease Control (CDC) Podcasts

    2010-09-29

    In this podcast, Dr. Joe Bresee explains the nature of antiviral drugs and how they are used for seasonal flu.  Created: 9/29/2010 by National Center for Immunization and Respiratory Diseases (NCIRD).   Date Released: 9/29/2010.

  5. Antiviral properties of photosensitizers

    International Nuclear Information System (INIS)

    Hudson, J.B.; Towers, G.H.N.

    1988-01-01

    We have studied the antiviral properties of three different groups of photo-sensitizers, viz. (i) various furyl compounds; (ii) β-carboline alkaloids; (iii) thiophenes and their acetylene derivatives. In general the antiviral potency of the furyl compounds correlated with their ability to produce DNA photoadducts. Among the naturally occurring β-carboline alkaloids, harmine was considerably more potent (in the presence of long wavelength UV radiation, UVA) than several other harmane-related compounds. Slight alterations in chemical structure had profound effects on their antiviral activities. Harmine was shown to inactivate the DNA-virus murine cytomegalovirus (MCMV) by inhibiting viral gene expression, although other targets may also exist. Several eudistomins, carboline derivatives isolated from a tunicate, were also photoactive against viruses. Various plant thiophenes and polyacetylenes were studied in detail. These compounds also required UVA for antiviral activity, and some of them were extremely potent against viruses with membranes, e.g. α-terthienyl, which showed significant activity at only 10 -5 μg/ml. When MCMV had been treated with α-terthienyl plus UVA, the virus retained its integrity and penetrated cells normally; but the virus did not replicate. (author)

  6. Protein kinase C signaling and cell cycle regulation

    Directory of Open Access Journals (Sweden)

    Adrian R Black

    2013-01-01

    Full Text Available A link between T cell proliferation and the protein kinase C (PKC family of serine/threonine kinases has been recognized for about thirty years. However, despite the wealth of information on PKC-mediated control of T cell activation, understanding of the effects of PKCs on the cell cycle machinery in this cell type remains limited. Studies in other systems have revealed important cell cycle-specific effects of PKC signaling that can either positively or negatively impact proliferation. The outcome of PKC activation is highly context-dependent, with the precise cell cycle target(s and overall effects determined by the specific isozyme involved, the timing of PKC activation, the cell type, and the signaling environment. Although PKCs can regulate all stages of the cell cycle, they appear to predominantly affect G0/G1 and G2. PKCs can modulate multiple cell cycle regulatory molecules, including cyclins, cyclin-dependent kinases (cdks, cdk inhibitors and cdc25 phosphatases; however, evidence points to Cip/Kip cdk inhibitors and D-type cyclins as key mediators of PKC-regulated cell cycle-specific effects. Several PKC isozymes can target Cip/Kip proteins to control G0/G1→S and/or G2→M transit, while effects on D-type cyclins regulate entry into and progression through G1. Analysis of PKC signaling in T cells has largely focused on its roles in T cell activation; thus, observed cell cycle effects are mainly positive. A prominent role is emerging for PKCθ, with non-redundant functions of other isozymes also described. Additional evidence points to PKCδ as a negative regulator of the cell cycle in these cells. As in other cell types, context-dependent effects of individual isozymes have been noted in T cells, and Cip/Kip cdk inhibitors and D-type cyclins appear to be major PKC targets. Future studies are anticipated to take advantage of the similarities between these various systems to enhance understanding of PKC-mediated cell cycle regulation in

  7. Molecular Mechanisms of Foot-and-Mouth Disease Virus Targeting the Host Antiviral Response.

    Science.gov (United States)

    Rodríguez Pulido, Miguel; Sáiz, Margarita

    2017-01-01

    Foot-and-mouth disease virus (FMDV) is the causative agent of an acute vesicular disease affecting pigs, cattle and other domestic, and wild animals worldwide. The aim of the host interferon (IFN) response is to limit viral replication and spread. Detection of the viral genome and products by specialized cellular sensors initiates a signaling cascade that leads to a rapid antiviral response involving the secretion of type I- and type III-IFNs and other antiviral cytokines with antiproliferative and immunomodulatory functions. During co-evolution with their hosts, viruses have acquired strategies to actively counteract host antiviral responses and the balance between innate response and viral antagonism may determine the outcome of disease and pathogenesis. FMDV proteases Lpro and 3C have been found to antagonize the host IFN response by a repertoire of mechanisms. Moreover, the putative role of other viral proteins in IFN antagonism is being recently unveiled, uncovering sophisticated immune evasion strategies different to those reported to date for other members of the Picornaviridae family. Here, we review the interplay between antiviral responses induced by FMDV infection and viral countermeasures to block them. Research on strategies used by viruses to modulate immunity will provide insights into the function of host pathways involved in defense against pathogens and will also lead to development of new therapeutic strategies to fight virus infections.

  8. Alveolar macrophage–derived type I interferons orchestrate innate immunity to RSV through recruitment of antiviral monocytes

    Science.gov (United States)

    Goritzka, Michelle; Makris, Spyridon; Kausar, Fahima; Durant, Lydia R.; Pereira, Catherine; Kumagai, Yutaro; Culley, Fiona J.; Mack, Matthias; Akira, Shizuo

    2015-01-01

    Type I interferons (IFNs) are important for host defense from viral infections, acting to restrict viral production in infected cells and to promote antiviral immune responses. However, the type I IFN system has also been associated with severe lung inflammatory disease in response to respiratory syncytial virus (RSV). Which cells produce type I IFNs upon RSV infection and how this directs immune responses to the virus, and potentially results in pathological inflammation, is unclear. Here, we show that alveolar macrophages (AMs) are the major source of type I IFNs upon RSV infection in mice. AMs detect RSV via mitochondrial antiviral signaling protein (MAVS)–coupled retinoic acid–inducible gene 1 (RIG-I)–like receptors (RLRs), and loss of MAVS greatly compromises innate immune restriction of RSV. This is largely attributable to loss of type I IFN–dependent induction of monocyte chemoattractants and subsequent reduced recruitment of inflammatory monocytes (infMo) to the lungs. Notably, the latter have potent antiviral activity and are essential to control infection and lessen disease severity. Thus, infMo recruitment constitutes an important and hitherto underappreciated, cell-extrinsic mechanism of type I IFN–mediated antiviral activity. Dysregulation of this system of host antiviral defense may underlie the development of RSV-induced severe lung inflammation. PMID:25897172

  9. Improving N-terminal protein annotation of Plasmodium species based on signal peptide prediction of orthologous proteins

    Directory of Open Access Journals (Sweden)

    Neto Armando

    2012-11-01

    Full Text Available Abstract Background Signal peptide is one of the most important motifs involved in protein trafficking and it ultimately influences protein function. Considering the expected functional conservation among orthologs it was hypothesized that divergence in signal peptides within orthologous groups is mainly due to N-terminal protein sequence misannotation. Thus, discrepancies in signal peptide prediction of orthologous proteins were used to identify misannotated proteins in five Plasmodium species. Methods Signal peptide (SignalP and orthology (OrthoMCL were combined in an innovative strategy to identify orthologous groups showing discrepancies in signal peptide prediction among their protein members (Mixed groups. In a comparative analysis, multiple alignments for each of these groups and gene models were visually inspected in search of misannotated proteins and, whenever possible, alternative gene models were proposed. Thresholds for signal peptide prediction parameters were also modified to reduce their impact as a possible source of discrepancy among orthologs. Validation of new gene models was based on RT-PCR (few examples or on experimental evidence already published (ApiLoc. Results The rate of misannotated proteins was significantly higher in Mixed groups than in Positive or Negative groups, corroborating the proposed hypothesis. A total of 478 proteins were reannotated and change of signal peptide prediction from negative to positive was the most common. Reannotations triggered the conversion of almost 50% of all Mixed groups, which were further reduced by optimization of signal peptide prediction parameters. Conclusions The methodological novelty proposed here combining orthology and signal peptide prediction proved to be an effective strategy for the identification of proteins showing wrongly N-terminal annotated sequences, and it might have an important impact in the available data for genome-wide searching of potential vaccine and drug

  10. Detection of amide I signals of interfacial proteins in situ using SFG.

    Science.gov (United States)

    Wang, Jie; Even, Mark A; Chen, Xiaoyun; Schmaier, Alvin H; Waite, J Herbert; Chen, Zhan

    2003-08-20

    In this Communication, we demonstrate the novel observation that it is feasible to collect amide signals from polymer/protein solution interfaces in situ using sum frequency generation (SFG) vibrational spectroscopy. Such SFG amide signals allow for acquisition of more detailed molecular level information of entire interfacial protein structures. Proteins investigated include bovine serum albumin, mussel protein mefp-2, factor XIIa, and ubiquitin. Our studies indicate that different proteins generate different SFG amide signals at the polystyrene/protein solution interface, showing that they have different interfacial coverage, secondary structure, or orientation.

  11. Identification of Two Protein-Signaling States Delineating Transcriptionally Heterogeneous Human Medulloblastoma

    Directory of Open Access Journals (Sweden)

    Walderik W. Zomerman

    2018-03-01

    Full Text Available Summary: The brain cancer medulloblastoma consists of different transcriptional subgroups. To characterize medulloblastoma at the phosphoprotein-signaling level, we performed high-throughput peptide phosphorylation profiling on a large cohort of SHH (Sonic Hedgehog, group 3, and group 4 medulloblastomas. We identified two major protein-signaling profiles. One profile was associated with rapid death post-recurrence and resembled MYC-like signaling for which MYC lesions are sufficient but not necessary. The second profile showed enrichment for DNA damage, as well as apoptotic and neuronal signaling. Integrative analysis demonstrated that heterogeneous transcriptional input converges on these protein-signaling profiles: all SHH and a subset of group 3 patients exhibited the MYC-like protein-signaling profile; the majority of the other group 3 subset and group 4 patients displayed the DNA damage/apoptotic/neuronal signaling profile. Functional analysis of enriched pathways highlighted cell-cycle progression and protein synthesis as therapeutic targets for MYC-like medulloblastoma. : Using peptide phosphorylation profiling, Zomerman et al. identify two medulloblastoma phosphoprotein-signaling profiles that have prognostic value and are potentially targetable. They find that these profiles extend across transcriptome-based subgroup borders. This suggests that diverse genetic information converges on common protein-signaling pathways and highlights protein-signaling as a unique information layer. Keywords: medulloblastoma, protein-signaling, protein synthesis, MYC, TP53, proteome, phosphoproteome

  12. Identification of diverse archaeal proteins with class III signal peptides cleaved by distinct archaeal prepilin peptidases

    NARCIS (Netherlands)

    Szabó, Zalán; Oliveira Stahl, Adriana; Albers, Sonja-V.; Kissinger, Jessica C.; Driessen, Arnold J.M.; Pohlschröder, Mechthild; Pohlschroder, M.

    2007-01-01

    Most secreted archaeal proteins are targeted to the membrane via a tripartite signal composed of a charged N terminus and a hydrophobic domain, followed by a signal peptidase-processing site. Signal peptides of archaeal flagellins, similar to class III signal peptides of bacterial type IV pilins,

  13. Mitogen activated protein kinase signaling in the kidney: Target for intervention?

    NARCIS (Netherlands)

    de Borst, M.H.; Wassef, L.; Kelly, D.J.; van Goor, H.; Navis, Ger Jan

    2006-01-01

    Mitogen activated protein kinases (MAPKs) are intracellular signal transduction molecules, which connect cell-surface receptor signals to intracellular processes. MAPKs regulate a range of cellular activities including cell proliferation, gene expression, apoptosis, cell differentiation and cytokine

  14. Unraveling the cellular context of cyclic nucleotide signaling proteins by chemical proteomics

    NARCIS (Netherlands)

    Corradini, E.

    2015-01-01

    Understanding the molecular mechanisms which regulate signal transduction is fundamental to the development of therapeutic molecules for the treatment of several diseases. In particular, signaling proteins, such as cyclic nucleotide dependent enzymes are the orchestrators of many tissue functions.

  15. SUMO-, MAPK- and resistance protein-signaling converge at transcription complexes that regulate plant innate immunity

    NARCIS (Netherlands)

    Burg, van den H.A.; Takken, F.L.W.

    2010-01-01

    Upon pathogen perception plant innate immune receptors activate various signaling pathways that trigger host defenses. PAMP-triggered defense signaling requires mitogen-activated protein kinase (MAPK) pathways, which modulate the activity of transcription factors through phosphorylation. Here, we

  16. SUMO-, MAPK-, and resistance protein-signaling converge at transcription complexes that regulate plant innate immunity

    NARCIS (Netherlands)

    van den Burg, H.A.; Takken, F.L.W.

    2010-01-01

    Upon pathogen perception plant innate immune receptors activate various signaling pathways that trigger host defenses. PAMP-triggered defense signaling requires mitogen-activated protein kinase (MAPK) pathways, which modulate the activity of transcription factors through phosphorylation. Here, we

  17. Protein tyrosine kinase and mitogen-activated protein kinase signalling pathways contribute to differences in heterophil-mediated innate immune responsiveness between two lines of broilers

    Science.gov (United States)

    Protein tyrosine phosphorylation mediates signal transduction of cellular processes, with protein tyrosine kinases (PTKs) regulating virtually all signaling events. The mitogen-activated protein kinase (MAPK) super-family consists of three conserved pathways that convert receptor activation into ce...

  18. Identification of novel components in microProtein signalling

    DEFF Research Database (Denmark)

    Rodrigues, Vandasue Lily

    characterization of smaller proteins. Using a computational approach, we identified putative microProteins that could target a diverse variety of protein classes. Using a synthetic microProtein approach, we demonstrate that miPs can target a diverse variety of target proteins, which makes them of interest...

  19. Proteolytic degradation of regulator of G protein signaling 2 facilitates temporal regulation of Gq/11 signaling and vascular contraction.

    Science.gov (United States)

    Kanai, Stanley M; Edwards, Alethia J; Rurik, Joel G; Osei-Owusu, Patrick; Blumer, Kendall J

    2017-11-24

    Regulator of G protein signaling 2 (RGS2) controls signaling by receptors coupled to the G q/11 class heterotrimeric G proteins. RGS2 deficiency causes several phenotypes in mice and occurs in several diseases, including hypertension in which a proteolytically unstable RGS2 mutant has been reported. However, the mechanisms and functions of RGS2 proteolysis remain poorly understood. Here we addressed these questions by identifying degradation signals in RGS2, and studying dynamic regulation of G q/11 -evoked Ca 2+ signaling and vascular contraction. We identified a novel bipartite degradation signal in the N-terminal domain of RGS2. Mutations disrupting this signal blunted proteolytic degradation downstream of E3 ubiquitin ligase binding to RGS2. Analysis of RGS2 mutants proteolyzed at various rates and the effects of proteasome inhibition indicated that proteolytic degradation controls agonist efficacy by setting RGS2 protein expression levels, and affecting the rate at which cells regain agonist responsiveness as synthesis of RGS2 stops. Analyzing contraction of mesenteric resistance arteries supported the biological relevance of this mechanism. Because RGS2 mRNA expression often is strikingly and transiently up-regulated and then down-regulated upon cell stimulation, our findings indicate that proteolytic degradation tightly couples RGS2 transcription, protein levels, and function. Together these mechanisms provide tight temporal control of G q/11 -coupled receptor signaling in the cardiovascular, immune, and nervous systems. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. Recognition of secretory proteins in Escherichia coli requires signals in addition to the signal sequence and slow folding

    Directory of Open Access Journals (Sweden)

    Flower Ann M

    2002-11-01

    Full Text Available Abstract Background The Sec-dependent protein export apparatus of Escherichia coli is very efficient at correctly identifying proteins to be exported from the cytoplasm. Even bacterial strains that carry prl mutations, which allow export of signal sequence-defective precursors, accurately differentiate between cytoplasmic and mutant secretory proteins. It was proposed previously that the basis for this precise discrimination is the slow folding rate of secretory proteins, resulting in binding by the secretory chaperone, SecB, and subsequent targeting to translocase. Based on this proposal, we hypothesized that a cytoplasmic protein containing a mutation that slows its rate of folding would be recognized by SecB and therefore targeted to the Sec pathway. In a Prl suppressor strain the mutant protein would be exported to the periplasm due to loss of ability to reject non-secretory proteins from the pathway. Results In the current work, we tested this hypothesis using a mutant form of λ repressor that folds slowly. No export of the mutant protein was observed, even in a prl strain. We then examined binding of the mutant λ repressor to SecB. We did not observe interaction by either of two assays, indicating that slow folding is not sufficient for SecB binding and targeting to translocase. Conclusions These results strongly suggest that to be targeted to the export pathway, secretory proteins contain signals in addition to the canonical signal sequence and the rate of folding.

  1. 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.

  2. The Role of Cgrp-Receptor Component Protein (Rcp in Cgrp-Mediated Signal Transduction

    Directory of Open Access Journals (Sweden)

    M. A. Prado

    2001-01-01

    Full Text Available The calcitonin gene-related peptide (CGRP-receptor component protein (RCP is a 17-kDa intracellular peripheral membrane protein required for signal transduction at CGRP receptors. To determine the role of RCP in CGRP-mediated signal transduction, RCP was depleted from NIH3T3 cells using antisense strategy. Loss of RCP protein correlated with loss of cAMP production by CGRP in the antisense cells. In contrast, loss of RCP had no effect on CGRP-mediated binding; therefore RCP is not acting as a chaperone for the CGRP receptor. Instead, RCP is a novel signal transduction molecule that couples the CGRP receptor to the cellular signal transduction machinery. RCP thus represents a prototype for a new class of signal transduction proteins that are required for regulation of G protein-coupled receptors.

  3. Signaling via G proteins mediates tumorigenic effects of GPR87

    DEFF Research Database (Denmark)

    Arfelt, Kristine Niss; Fares, Suzan; Sparre-Ulrich, Alexander H.

    2017-01-01

    G protein-coupled receptors (GPCRs) constitute a large protein family of seven transmembrane (7TM) spanning proteins that regulate multiple physiological functions. GPR87 is overexpressed in several cancers and plays a role in tumor cell survival. Here, the basal activity of GPR87 was investigated...

  4. Grass Carp Laboratory of Genetics and Physiology 2 Serves As a Negative Regulator in Retinoic Acid-Inducible Gene I- and Melanoma Differentiation-Associated Gene 5-Mediated Antiviral Signaling in Resting State and Early Stage of Grass Carp Reovirus Infection

    OpenAIRE

    Rao, Youliang; Wan, Quanyuan; Yang, Chunrong; Su, Jianguo

    2017-01-01

    Laboratory of genetics and physiology 2 (LGP2) is a key component of RIG-I-like receptors (RLRs). However, the lack of the caspase recruitment domains (CARDs) results in its controversial functional performance as a negative or positive regulator in antiviral responses. Especially, no sufficient evidence uncovers the functional mechanisms of LGP2 in RLR signaling pathways in teleost. Here, negative regulation mechanism of LGP2 in certain situations in retinoic acid-inducible gene I (RIG-I) an...

  5. La respuesta inmune antiviral

    OpenAIRE

    Sánchez de la Rosa, Rainel; Sánchez de la Rosa, Ernesto; Rodríguez Hernández, Néstor

    1998-01-01

    Se expone que los virus son parásitos intracelulares obligados, puesto que no tienen metabolismo propio; esto obliga al sistema inmune a poner en marcha sus mecanismos más especializados para reconocer y eliminar, tanto a los virus libres, como a las células infectadas. Se señala que las células presentadoras de antígenos, los linfocitos B y los T unidos al complejo mayor de histocompatibilidad, forman parte de la organización de la respuesta inmune antiviral; la inducción de esta respuesta c...

  6. Protein conservation and variation suggest mechanisms of cell type-specific modulation of signaling pathways.

    Directory of Open Access Journals (Sweden)

    Martin H Schaefer

    2014-06-01

    Full Text Available Many proteins and signaling pathways are present in most cell types and tissues and yet perform specialized functions. To elucidate mechanisms by which these ubiquitous pathways are modulated, we overlaid information about cross-cell line protein abundance and variability, and evolutionary conservation onto functional pathway components and topological layers in the pathway hierarchy. We found that the input (receptors and the output (transcription factors layers evolve more rapidly than proteins in the intermediary transmission layer. In contrast, protein expression variability decreases from the input to the output layer. We observed that the differences in protein variability between the input and transmission layer can be attributed to both the network position and the tendency of variable proteins to physically interact with constitutively expressed proteins. Differences in protein expression variability and conservation are also accompanied by the tendency of conserved and constitutively expressed proteins to acquire somatic mutations, while germline mutations tend to occur in cell type-specific proteins. Thus, conserved core proteins in the transmission layer could perform a fundamental role in most cell types and are therefore less tolerant to germline mutations. In summary, we propose that the core signal transmission machinery is largely modulated by a variable input layer through physical protein interactions. We hypothesize that the bow-tie organization of cellular signaling on the level of protein abundance variability contributes to the specificity of the signal response in different cell types.

  7. Protein Conformation Ensembles Monitored by HDX Reveal a Structural Rationale for Abscisic Acid Signaling Protein Affinities and Activities

    OpenAIRE

    West, Graham M.; Pascal, Bruce D.; Ng, Ley-Moy; Soon, Fen-Fen; Melcher, Karsten; Xu, H. Eric; Chalmers, Michael J.; Griffin, Patrick R.

    2013-01-01

    Plants regulate growth and respond to environmental stress through abscisic acid (ABA) regulated pathways, and as such these pathways are of primary interest for biological and agricultural research. The ABA response is first perceived by the PYR/PYL/RCAR class of START protein receptors. These ABA activated receptors disrupt phosphatase inhibition of Snf1-related kinases (SnRKs) enabling kinase signaling. Here, insights into the structural mechanism of proteins in the ABA signaling pathway (...

  8. Nucleocapsid-Independent Specific Viral RNA Packaging via Viral Envelope Protein and Viral RNA Signal

    OpenAIRE

    Narayanan, Krishna; Chen, Chun-Jen; Maeda, Junko; Makino, Shinji

    2003-01-01

    For any of the enveloped RNA viruses studied to date, recognition of a specific RNA packaging signal by the virus's nucleocapsid (N) protein is the first step described in the process of viral RNA packaging. In the murine coronavirus a selective interaction between the viral transmembrane envelope protein M and the viral ribonucleoprotein complex, composed of N protein and viral RNA containing a short cis-acting RNA element, the packaging signal, determines the selective RNA packaging into vi...

  9. Phosphotyrosine signaling proteins that drive oncogenesis tend to be highly interconnected.

    Science.gov (United States)

    Koytiger, Grigoriy; Kaushansky, Alexis; Gordus, Andrew; Rush, John; Sorger, Peter K; MacBeath, Gavin

    2013-05-01

    Mutation and overexpression of receptor tyrosine kinases or the proteins they regulate serve as oncogenic drivers in diverse cancers. To better understand receptor tyrosine kinase signaling and its link to oncogenesis, we used protein microarrays to systematically and quantitatively measure interactions between virtually every SH2 or PTB domain encoded in the human genome and all known sites of tyrosine phosphorylation on 40 receptor tyrosine kinases and on most of the SH2 and PTB domain-containing adaptor proteins. We found that adaptor proteins, like RTKs, have many high affinity bindings sites for other adaptor proteins. In addition, proteins that drive cancer, including both receptors and adaptor proteins, tend to be much more highly interconnected via networks of SH2 and PTB domain-mediated interactions than nononcogenic proteins. Our results suggest that network topological properties such as connectivity can be used to prioritize new drug targets in this well-studied family of signaling proteins.

  10. Regulation of Cellular Redox Signaling by Matricellular Proteins in Vascular Biology, Immunology, and Cancer.

    Science.gov (United States)

    Roberts, David D; Kaur, Sukhbir; Isenberg, Jeffrey S

    2017-10-20

    In contrast to structural elements of the extracellular matrix, matricellular proteins appear transiently during development and injury responses, but their sustained expression can contribute to chronic disease. Through interactions with other matrix components and specific cell surface receptors, matricellular proteins regulate multiple signaling pathways, including those mediated by reactive oxygen and nitrogen species and H 2 S. Dysregulation of matricellular proteins contributes to the pathogenesis of vascular diseases and cancer. Defining the molecular mechanisms and receptors involved is revealing new therapeutic opportunities. Recent Advances: Thrombospondin-1 (TSP1) regulates NO, H 2 S, and superoxide production and signaling in several cell types. The TSP1 receptor CD47 plays a central role in inhibition of NO signaling, but other TSP1 receptors also modulate redox signaling. The matricellular protein CCN1 engages some of the same receptors to regulate redox signaling, and ADAMTS1 regulates NO signaling in Marfan syndrome. In addition to mediating matricellular protein signaling, redox signaling is emerging as an important pathway that controls the expression of several matricellular proteins. Redox signaling remains unexplored for many matricellular proteins. Their interactions with multiple cellular receptors remains an obstacle to defining signaling mechanisms, but improved transgenic models could overcome this barrier. Therapeutics targeting the TSP1 receptor CD47 may have beneficial effects for treating cardiovascular disease and cancer and have recently entered clinical trials. Biomarkers are needed to assess their effects on redox signaling in patients and to evaluate how these contribute to their therapeutic efficacy and potential side effects. Antioxid. Redox Signal. 27, 874-911.

  11. G protein-coupled receptor kinase 2 negatively regulates chemokine signaling at a level downstream from G protein subunits

    NARCIS (Netherlands)

    Jimenez-Sainz, MC; Murga, C; Kavelaars, A; Jurado-Pueyo, M; Krakstad, BF; Heijnen, CJ; Mayor, F; Aragay, AM

    The G protein-coupled receptor kinase 2 (GRK2) phosphorylates and desensitizes ligand-activated G protein-coupled-receptors. Here, evidence is shown for a novel role of GRK2 in regulating chemokine-mediated signals. The presence of increased levels of GRK2 in human embryonic kidney (HEK) 293 cells

  12. Making Sense of G Proteins: Genetic analysis of sensory G protein signaling in the nematode C. elegans

    NARCIS (Netherlands)

    H. Lans (Hannes)

    2005-01-01

    textabstractAmong the key molecules involved in sensory perception are G proteins, which act in every cell to activate a cascade of signaling molecules in response to certain environmental cues. In this thesis, several studies on the role of G proteins in the sensory system of C. elegans are

  13. Conformational analysis of g protein-coupled receptor signaling by hydrogen/deuterium exchange mass spectrometry.

    Science.gov (United States)

    Li, Sheng; Lee, Su Youn; Chung, Ka Young

    2015-01-01

    Conformational change and protein-protein interactions are two major mechanisms of membrane protein signal transduction, including G protein-coupled receptors (GPCRs). Upon agonist binding, GPCRs change conformation, resulting in interaction with downstream signaling molecules such as G proteins. To understand the precise signaling mechanism, studies have investigated the structural mechanism of GPCR signaling using X-ray crystallography, nuclear magnetic resonance (NMR), or electron paramagnetic resonance. In addition to these techniques, hydrogen/deuterium exchange mass spectrometry (HDX-MS) has recently been used in GPCR studies. HDX-MS measures the rate at which peptide amide hydrogens exchange with deuterium in the solvent. Exposed or flexible regions have higher exchange rates and excluded or ordered regions have lower exchange rates. Therefore, HDX-MS is a useful tool for studying protein-protein interfaces and conformational changes after protein activation or protein-protein interactions. Although HDX-MS does not give high-resolution structures, it analyzes protein conformations that are difficult to study with X-ray crystallography or NMR. Furthermore, conformational information from HDX-MS can help in the crystallization of X-ray crystallography by suggesting highly flexible regions. Interactions between GPCRs and downstream signaling molecules are not easily analyzed by X-ray crystallography or NMR because of the large size of the GPCR-signaling molecule complexes, hydrophobicity, and flexibility of GPCRs. HDX-MS could be useful for analyzing the conformational mechanism of GPCR signaling. In this chapter, we discuss details of HDX-MS for analyzing GPCRs using the β2AR-G protein complex as a model system. © 2015 Elsevier Inc. All rights reserved.

  14. Methods for the Analysis of Protein Phosphorylation-Mediated Cellular Signaling Networks

    Science.gov (United States)

    White, Forest M.; Wolf-Yadlin, Alejandro

    2016-06-01

    Protein phosphorylation-mediated cellular signaling networks regulate almost all aspects of cell biology, including the responses to cellular stimulation and environmental alterations. These networks are highly complex and comprise hundreds of proteins and potentially thousands of phosphorylation sites. Multiple analytical methods have been developed over the past several decades to identify proteins and protein phosphorylation sites regulating cellular signaling, and to quantify the dynamic response of these sites to different cellular stimulation. Here we provide an overview of these methods, including the fundamental principles governing each method, their relative strengths and weaknesses, and some examples of how each method has been applied to the analysis of complex signaling networks. When applied correctly, each of these techniques can provide insight into the topology, dynamics, and regulation of protein phosphorylation signaling networks.

  15. MAVS protein is attenuated by rotavirus nonstructural protein 1.

    Directory of Open Access Journals (Sweden)

    Satabdi Nandi

    Full Text Available Rotavirus is the single, most important agent of infantile gastroenteritis in many animal species, including humans. In developing countries, rotavirus infection attributes approximately 500,000 deaths annually. Like other viruses it establishes an intimate and complex interaction with the host cell to counteract the antiviral responses elicited by the cell. Among various pattern recognition receptors (PAMPs of the host, the cytosolic RNA helicases interact with viral RNA to activate the Mitochondrial Antiviral Signaling protein (MAVS, which regulates cellular interferon response. With an aim to identify the role of different PAMPs in rotavirus infected cell, MAVS was found to degrade in a time dependent and strain independent manner. Rotavirus non-structural protein 1 (NSP1 which is a known IFN antagonist, interacted with MAVS and degraded it in a strain independent manner, resulting in a complete loss of RNA sensing machinery in the infected cell. To best of our knowledge, this is the first report on NSP1 functionality where a signaling protein is targeted unanimously in all strains. In addition NSP1 inhibited the formation of detergent resistant MAVS aggregates, thereby averting the antiviral signaling cascade. The present study highlights the multifunctional role of rotavirus NSP1 and reinforces the fact that the virus orchestrates the cellular antiviral response to its own benefit by various back up strategies.

  16. Application of native signal sequences for recombinant proteins secretion in Pichia pastoris

    DEFF Research Database (Denmark)

    Borodina, Irina; Do, Duy Duc; Eriksen, Jens C.

    Background Methylotrophic yeast Pichia pastoris is widely used for recombinant protein production, largely due to its ability to secrete correctly folded heterologous proteins to the fermentation medium. Secretion is usually achieved by cloning the recombinant gene after a leader sequence, where...... alpha‐mating factor (MF) prepropeptide from Saccharomyces cerevisiae is most commonly used. Our aim was to test whether signal peptides from P. pastoris native secreted proteins could be used to direct secretion of recombinant proteins. Results Eleven native signal peptides from P. pastoris were tested...... by optimization of expression of three different proteins in P. pastoris. Conclusions Native signal peptides from P. pastoris can be used to direct secretion of recombinant proteins. A novel USER‐based P. pastoris system allows easy cloning of protein‐coding gene with the promoter and leader sequence of choice....

  17. Regulator of G-Protein Signaling 7 Regulates Reward Behavior by Controlling Opioid Signaling in the Striatum.

    Science.gov (United States)

    Sutton, Laurie P; Ostrovskaya, Olga; Dao, Maria; Xie, Keqiang; Orlandi, Cesare; Smith, Roy; Wee, Sunmee; Martemyanov, Kirill A

    2016-08-01

    Morphine mediates its euphoric and analgesic effects by acting on the μ-opioid receptor (MOR). MOR belongs to the family of G-protein coupled receptors whose signaling efficiency is controlled by the regulator of G-protein signaling (RGS) proteins. Our understanding of the molecular diversity of RGS proteins that control MOR signaling, their circuit specific actions, and underlying cellular mechanisms is very limited. We used genetic approaches to ablate regulator of G-protein signaling 7 (RGS7) both globally and in specific neuronal populations. We used conditioned place preference and self-administration paradigms to examine reward-related behavior and a battery of tests to assess analgesia, tolerance, and physical dependence to morphine. Electrophysiology approaches were applied to investigate the impact of RGS7 on morphine-induced alterations in neuronal excitability and plasticity of glutamatergic synapses. At least three animals were used for each assessment. Elimination of RGS7 enhanced reward, increased analgesia, delayed tolerance, and heightened withdrawal in response to morphine administration. RGS7 in striatal neurons was selectively responsible for determining the sensitivity of rewarding and reinforcing behaviors to morphine without affecting analgesia, tolerance, and withdrawal. In contrast, deletion of RGS7 in dopaminergic neurons did not influence morphine reward. RGS7 exerted its effects by controlling morphine-induced changes in excitability of medium spiny neurons in nucleus accumbens and gating the compositional plasticity of α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid and N-methyl-D-aspartate receptors. This study identifies RGS7 as a novel regulator of MOR signaling by dissecting its circuit specific actions and pinpointing its role in regulating morphine reward by controlling the activity of nucleus accumbens neurons. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  18. Aciclovir: nuevo antiviral

    Directory of Open Access Journals (Sweden)

    G. Repetto

    2017-05-01

    Full Text Available El aciclovir es un antiviral útil en infecciones graves causadas por el virus varicela-zoster. Es bien tolerado con escasas reacciones adversas. En pacientes deshidratados, en insuficiencia renal o si la infusión endovenosa es muy rápida, puede ocacionar una "nefropatía obstructiva" transitoria. Existen preparados de uso tópico, oftálmico, endovenoso y oral; esta última vía constituye una ventaja sobre la vidarabina con la que tiene en común el espectro de actividad. En razón de su selectividad, riesgo de resistencia y número reducido de antivirales, su prescripción debe restringirse a infecciones graves causadas por los agentes inmunodeprimidos; excluyendo por lo tanto las comunes y autolimitadas, frecuentes en el individuo normal.

  19. Role of polarized G protein signaling in tracking pheromone gradients

    Science.gov (United States)

    McClure, Allison W.; Minakova, Maria; Dyer, Jayme M.; Zyla, Trevin R.; Elston, Timothy C.; Lew, Daniel J.

    2015-01-01

    Summary Yeast cells track gradients of pheromones to locate mating partners. Intuition suggests that uniform distribution of pheromone receptors over the cell surface would yield optimal gradient sensing. However, yeast cells display polarized receptors. The benefit of such polarization was unknown. During gradient tracking, cell growth is directed by a patch of polarity regulators that wanders around the cortex. Patch movement is sensitive to pheromone dose, with wandering reduced on the up-gradient side of the cell, resulting in net growth in that direction. Mathematical modeling suggests that active receptors and associated G proteins lag behind the polarity patch and act as an effective drag on patch movement. In vivo, the polarity patch is trailed by a G protein-rich domain, and this polarized distribution of G proteins is required to constrain patch wandering. Our findings explain why G protein polarization is beneficial, and illuminate a novel mechanism for gradient tracking. PMID:26609960

  20. Multistep Current Signal in Protein Translocation through Graphene Nanopores

    KAUST Repository

    Bonome, Emma Letizia; Lepore, Rosalba; Raimondo, Domenico; Cecconi, Fabio; Tramontano, Anna; Chinappi, Mauro

    2015-01-01

    of graphene constitute a major advantage for molecule characterization. Here we analyze the translocation pathway of the thioredoxin protein across a graphene nanopore, and the related ionic currents, by integrating two nonequilibrium molecular dynamics

  1. Human Cytomegalovirus Encoded miR-US25-1-5p Attenuates CD147/EMMPRIN-Mediated Early Antiviral Response

    Directory of Open Access Journals (Sweden)

    Jun Chen

    2017-12-01

    Full Text Available Cellular receptor-mediated signaling pathways play critical roles during the initial immune response to Human Cytomegalovirus (HCMV infection. However, the involvement of type-I transmembrane glycoprotein CD147/EMMPRIN (extracellular matrix metalloproteinase inducer in the antiviral response to HCMV infection is still unknown. Here, we demonstrated the specific knockdown of CD147 significantly decreased HCMV-induced activation of NF-κB and Interferon-beta (IFN-β, which contribute to the cellular antiviral responses. Next, we confirmed that HCMV-encoded miR-US25-1-5p could target the 3′ UTR (Untranslated Region of CD147 mRNA, and thus facilitate HCMV lytic propagation at a low multiplicity of infection (MOI. The expression and secretion of Cyclophilin A (sCyPA, as a ligand for CD147 and a proinflammatory cytokine, were up-regulated in response to HCMV stimuli. Finally, we confirmed that CD147 mediated HCMV-triggered antiviral signaling via the sCyPA-CD147-ERK (extracellular regulated protein kinases/NF-κB axis signaling pathway. These findings reveal an important HCMV mechanism for evading antiviral innate immunity through its encoded microRNA by targeting transmembrane glycoprotein CD147, and a potential cause of HCMV inflammatory disorders due to the secretion of proinflammatory cytokine CyPA.

  2. Engineering Synthetic Proteins to Generate Ca2+ Signals in Mammalian Cells.

    Science.gov (United States)

    Qudrat, Anam; Truong, Kevin

    2017-03-17

    The versatility of Ca 2+ signals allows it to regulate diverse cellular processes such as migration, apoptosis, motility and exocytosis. In some receptors (e.g., VEGFR2), Ca 2+ signals are generated upon binding their ligand(s) (e.g., VEGF-A). Here, we employed a design strategy to engineer proteins that generate a Ca 2+ signal upon binding various extracellular stimuli by creating fusions of protein domains that oligomerize to the transmembrane domain and the cytoplasmic tail of the VEGFR2. To test the strategy, we created chimeric proteins that generate Ca 2+ signals upon stimulation with various extracellular stimuli (e.g., rapamycin, EDTA or extracellular free Ca 2+ ). By coupling these chimeric proteins that generate Ca 2+ signals with proteins that respond to Ca 2+ signals, we rewired, for example, dynamic cellular blebbing to increases in extracellular free Ca 2+ . Thus, using this design strategy, it is possible to engineer proteins to generate a Ca 2+ signal to rewire a wide range of extracellular stimuli to a wide range of Ca 2+ -activated processes.

  3. Ric-8A, a Gα protein guanine nucleotide exchange factor potentiates taste receptor signaling

    Directory of Open Access Journals (Sweden)

    Claire J Fenech

    2009-10-01

    Full Text Available Taste receptors for sweet, bitter and umami tastants are G-protein coupled receptors (GPCRs. While much effort has been devoted to understanding G-protein-receptor interactions and identifying the components of the signalling cascade downstream of these receptors, at the level of the G-protein the modulation of receptor signal transduction remains relatively unexplored. In this regard a taste-specific regulator of G-protein signaling (RGS, RGS21, has recently been identified. To study whether guanine nucleotide exchange factors (GEFs are involved in the transduction of the signal downstream of the taste GPCRs we investigated the expression of Ric-8A and Ric-8B in mouse taste cells and their interaction with G-protein subunits found in taste buds. Mammalian Ric-8 proteins were initially identified as potent GEFs for a range of Gα subunits and Ric-8B has recently been shown to amplify olfactory signal transduction. We find that both Ric-8A and Ric-8B are expressed in a large portion of taste bud cells and that most of these cells contain IP3R-3 a marker for sweet, umami and bitter taste receptor cells. Ric-8A interacts with Gα-gustducin and Gαi2 through which it amplifies the signal transduction of hTas2R16, a receptor for bitter compounds. Overall, these findings are consistent with a role for Ric-8 in mammalian taste signal transduction.

  4. Extracting protein dynamics information from overlapped NMR signals using relaxation dispersion difference NMR spectroscopy.

    Science.gov (United States)

    Konuma, Tsuyoshi; Harada, Erisa; Sugase, Kenji

    2015-12-01

    Protein dynamics plays important roles in many biological events, such as ligand binding and enzyme reactions. NMR is mostly used for investigating such protein dynamics in a site-specific manner. Recently, NMR has been actively applied to large proteins and intrinsically disordered proteins, which are attractive research targets. However, signal overlap, which is often observed for such proteins, hampers accurate analysis of NMR data. In this study, we have developed a new methodology called relaxation dispersion difference that can extract conformational exchange parameters from overlapped NMR signals measured using relaxation dispersion spectroscopy. In relaxation dispersion measurements, the signal intensities of fluctuating residues vary according to the Carr-Purcell-Meiboon-Gill pulsing interval, whereas those of non-fluctuating residues are constant. Therefore, subtraction of each relaxation dispersion spectrum from that with the highest signal intensities, measured at the shortest pulsing interval, leaves only the signals of the fluctuating residues. This is the principle of the relaxation dispersion difference method. This new method enabled us to extract exchange parameters from overlapped signals of heme oxygenase-1, which is a relatively large protein. The results indicate that the structural flexibility of a kink in the heme-binding site is important for efficient heme binding. Relaxation dispersion difference requires neither selectively labeled samples nor modification of pulse programs; thus it will have wide applications in protein dynamics analysis.

  5. Extracting protein dynamics information from overlapped NMR signals using relaxation dispersion difference NMR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Konuma, Tsuyoshi [Icahn School of Medicine at Mount Sinai, Department of Structural and Chemical Biology (United States); Harada, Erisa [Suntory Foundation for Life Sciences, Bioorganic Research Institute (Japan); Sugase, Kenji, E-mail: sugase@sunbor.or.jp, E-mail: sugase@moleng.kyoto-u.ac.jp [Kyoto University, Department of Molecular Engineering, Graduate School of Engineering (Japan)

    2015-12-15

    Protein dynamics plays important roles in many biological events, such as ligand binding and enzyme reactions. NMR is mostly used for investigating such protein dynamics in a site-specific manner. Recently, NMR has been actively applied to large proteins and intrinsically disordered proteins, which are attractive research targets. However, signal overlap, which is often observed for such proteins, hampers accurate analysis of NMR data. In this study, we have developed a new methodology called relaxation dispersion difference that can extract conformational exchange parameters from overlapped NMR signals measured using relaxation dispersion spectroscopy. In relaxation dispersion measurements, the signal intensities of fluctuating residues vary according to the Carr-Purcell-Meiboon-Gill pulsing interval, whereas those of non-fluctuating residues are constant. Therefore, subtraction of each relaxation dispersion spectrum from that with the highest signal intensities, measured at the shortest pulsing interval, leaves only the signals of the fluctuating residues. This is the principle of the relaxation dispersion difference method. This new method enabled us to extract exchange parameters from overlapped signals of heme oxygenase-1, which is a relatively large protein. The results indicate that the structural flexibility of a kink in the heme-binding site is important for efficient heme binding. Relaxation dispersion difference requires neither selectively labeled samples nor modification of pulse programs; thus it will have wide applications in protein dynamics analysis.

  6. Protein Kinase Signalling in the Moss Physcomitrella patens

    DEFF Research Database (Denmark)

    Azevedo de Silva, Raquel

    Adaptation to environmental cues trigger a plethora of intracellular pathways capable of maintaining homeostasis. Receptors in the plasma membrane and in the cytosol recognize extracellular or intracellular signals initiating defense against pathogens or stress-adaptation. MAPK cascade are one...... of the pathways involved in stress signalling, phosphorylating several downstream substrates in order to produce appropriate responses. We report here that P. patens has a receptor-like kinase CERK1 responsible for chitin perception which can rescue Atcerk1 mutant. Activation of PpCERK1 triggers the activation...

  7. SH2 and SH3 domains: elements that control interactions of cytoplasmic signaling proteins.

    Science.gov (United States)

    Koch, C A; Anderson, D; Moran, M F; Ellis, C; Pawson, T

    1991-05-03

    Src homology (SH) regions 2 and 3 are noncatalytic domains that are conserved among a series of cytoplasmic signaling proteins regulated by receptor protein-tyrosine kinases, including phospholipase C-gamma, Ras GTPase (guanosine triphosphatase)-activating protein, and Src-like tyrosine kinases. The SH2 domains of these signaling proteins bind tyrosine phosphorylated polypeptides, implicated in normal signaling and cellular transformation. Tyrosine phosphorylation acts as a switch to induce the binding of SH2 domains, thereby mediating the formation of heteromeric protein complexes at or near the plasma membrane. The formation of these complexes is likely to control the activation of signal transduction pathways by tyrosine kinases. The SH3 domain is a distinct motif that, together with SH2, may modulate interactions with the cytoskeleton and membrane. Some signaling and transforming proteins contain SH2 and SH3 domains unattached to any known catalytic element. These noncatalytic proteins may serve as adaptors to link tyrosine kinases to specific target proteins. These observations suggest that SH2 and SH3 domains participate in the control of intracellular responses to growth factor stimulation.

  8. Optimizing the protein switch: altering nuclear import and export signals, and ligand binding domain

    Science.gov (United States)

    Kakar, Mudit; Davis, James R.; Kern, Steve E.; Lim, Carol S.

    2007-01-01

    Ligand regulated localization controllable protein constructs were optimized in this study. Several constructs were made from a classical nuclear export signal (HIV-rev, MAPKK, or progesterone receptor) in combination with a SV40 T-antigen type nuclear import signal. Different ligand binding domains (LBDs from glucocorticoid receptor or progesterone receptor) were also tested for their ability to impart control over localization of proteins. This study was designed to create constructs which are cytoplasmic in the absence of ligand and nuclear in the presence of ligand, and also to regulate the amount of protein translocating to the nucleus on ligand induction. The balance between the strengths of import and export signals was critical for overall localization of proteins. The amount of protein entering the nucleus was also affected by the dose of ligand (10-100nM). However, the overall import characteristics were determined by the strengths of localization signals and the inherent localization properties of the LBD used. This study established that the amount of protein present in a particular compartment can be regulated by the use of localization signals of various strengths. These optimized localization controllable protein constructs can be used to correct for diseases due to aberrant localization of proteins. PMID:17574289

  9. Solution structure of the human signaling protein RACK1

    Directory of Open Access Journals (Sweden)

    Papa Priscila F

    2010-06-01

    Full Text Available Abstract Background The adaptor protein RACK1 (receptor of activated kinase 1 was originally identified as an anchoring protein for protein kinase C. RACK1 is a 36 kDa protein, and is composed of seven WD repeats which mediate its protein-protein interactions. RACK1 is ubiquitously expressed and has been implicated in diverse cellular processes involving: protein translation regulation, neuropathological processes, cellular stress, and tissue development. Results In this study we performed a biophysical analysis of human RACK1 with the aim of obtaining low resolution structural information. Small angle X-ray scattering (SAXS experiments demonstrated that human RACK1 is globular and monomeric in solution and its low resolution structure is strikingly similar to that of an homology model previously calculated by us and to the crystallographic structure of RACK1 isoform A from Arabidopsis thaliana. Both sedimentation velocity and sedimentation equilibrium analytical ultracentrifugation techniques showed that RACK1 is predominantly a monomer of around 37 kDa in solution, but also presents small amounts of oligomeric species. Moreover, hydrodynamic data suggested that RACK1 has a slightly asymmetric shape. The interaction of RACK1 and Ki-1/57 was tested by sedimentation equilibrium. The results suggested that the association between RACK1 and Ki-1/57(122-413 follows a stoichiometry of 1:1. The binding constant (KB observed for RACK1-Ki-1/57(122-413 interaction was of around (1.5 ± 0.2 × 106 M-1 and resulted in a dissociation constant (KD of (0.7 ± 0.1 × 10-6 M. Moreover, the fluorescence data also suggests that the interaction may occur in a cooperative fashion. Conclusion Our SAXS and analytical ultracentrifugation experiments indicated that RACK1 is predominantly a monomer in solution. RACK1 and Ki-1/57(122-413 interact strongly under the tested conditions.

  10. Regulation of the Host Antiviral State by Intercellular Communications

    Directory of Open Access Journals (Sweden)

    Sonia Assil

    2015-08-01

    Full Text Available Viruses usually induce a profound remodeling of host cells, including the usurpation of host machinery to support their replication and production of virions to invade new cells. Nonetheless, recognition of viruses by the host often triggers innate immune signaling, preventing viral spread and modulating the function of immune cells. It conventionally occurs through production of antiviral factors and cytokines by infected cells. Virtually all viruses have evolved mechanisms to blunt such responses. Importantly, it is becoming increasingly recognized that infected cells also transmit signals to regulate innate immunity in uninfected neighboring cells. These alternative pathways are notably mediated by vesicular secretion of various virus- and host-derived products (miRNAs, RNAs, and proteins and non-infectious viral particles. In this review, we focus on these newly-described modes of cell-to-cell communications and their impact on neighboring cell functions. The reception of these signals can have anti- and pro-viral impacts, as well as more complex effects in the host such as oncogenesis and inflammation. Therefore, these “broadcasting” functions, which might be tuned by an arms race involving selective evolution driven by either the host or the virus, constitute novel and original regulations of viral infection, either highly localized or systemic.

  11. Arbidol: a broad-spectrum antiviral that inhibits acute and chronic HCV infection

    Directory of Open Access Journals (Sweden)

    Pécheur Eve-Isabelle

    2006-07-01

    Full Text Available Abstract Arbidol (ARB is an antiviral compound that was originally proven effective for treatment of influenza and several other respiratory viral infections. The broad spectrum of ARB anti-viral activity led us to evaluate its effect on hepatitis C virus (HCV infection and replication in cell culture. Long-term ARB treatment of Huh7 cells chronically replicating a genomic length genotype 1b replicon resulted in sustained reduction of viral RNA and protein expression, and eventually cured HCV infected cells. Pre-treatment of human hepatoma Huh7.5.1 cells with 15 μM ARB for 24 to 48 hours inhibited acute infection with JFH-1 virus by up to 1000-fold. The inhibitory effect of ARB on HCV was not due to generalized cytotoxicity, nor to augmentation of IFN antiviral signaling pathways, but involved impaired virus-mediated membrane fusion. ARB's affinity for membranes may inhibit several aspects of the HCV lifecycle that are membrane-dependent.

  12. How a mycoparasite employs g-protein signaling: using the example of trichoderma.

    Science.gov (United States)

    Omann, Markus; Zeilinger, Susanne

    2010-01-01

    Mycoparasitic Trichoderma spp. act as potent biocontrol agents against a number of plant pathogenic fungi, whereupon the mycoparasitic attack includes host recognition followed by infection structure formation and secretion of lytic enzymes and antifungal metabolites leading to the host's death. Host-derived signals are suggested to be recognized by receptors located on the mycoparasite's cell surface eliciting an internal signal transduction cascade which results in the transcription of mycoparasitism-relevant genes. Heterotrimeric G proteins of fungi transmit signals originating from G-protein-coupled receptors mainly to the cAMP and the MAP kinase pathways resulting in regulation of downstream effectors. Components of the G-protein signaling machinery such as Gα subunits and G-protein-coupled receptors were recently shown to play crucial roles in Trichoderma mycoparasitism as they govern processes such as the production of extracellular cell wall lytic enzymes, the secretion of antifungal metabolites, and the formation of infection structures.

  13. Mitogen-activated protein kinase and abscisic acid signal transduction

    NARCIS (Netherlands)

    Heimovaara-Dijkstra, S.; Testerink, C.; Wang, M.

    1998-01-01

    The phytohormone abscisic acid (ABA) is a classical plant hormone, responsible for regulation of abscission, diverse aspects of plant and seed development, stress responses and germination. It was found that ABA signal transduction in plants can involve the activity of type 2C-phosphatases (PP2C),

  14. Identification and quantitation of signal molecule-dependent protein phosphorylation

    KAUST Repository

    Groen, Arnoud J.; Thomas, Ludivine; Lilley, Kathryn S.; Marondedze, Claudius

    2013-01-01

    in combination with phosphopeptide enrichment by titanium dioxide (TiO2) and their identification by MS is described. This workflow can be used to gain insights into the role of signalling molecules such as cyclic nucleotides on regulatory networks through

  15. Neuronal Orphan G-Protein Coupled Receptor Proteins Mediate Plasmalogens-Induced Activation of ERK and Akt Signaling.

    Directory of Open Access Journals (Sweden)

    Md Shamim Hossain

    Full Text Available The special glycerophospholipids plasmalogens (Pls are enriched in the brain and reported to prevent neuronal cell death by enhancing phosphorylation of Akt and ERK signaling in neuronal cells. Though the activation of Akt and ERK was found to be necessary for the neuronal cells survival, it was not known how Pls enhanced cellular signaling. To answer this question, we searched for neuronal specific orphan GPCR (G-protein coupled receptor proteins, since these proteins were believed to play a role in cellular signal transduction through the lipid rafts, where both Pls and some GPCRs were found to be enriched. In the present study, pan GPCR inhibitor significantly reduced Pls-induced ERK signaling in neuronal cells, suggesting that Pls could activate GPCRs to induce signaling. We then checked mRNA expression of 19 orphan GPCRs and 10 of them were found to be highly expressed in neuronal cells. The knockdown of these 10 neuronal specific GPCRs by short hairpin (sh-RNA lentiviral particles revealed that the Pls-mediated phosphorylation of ERK was inhibited in GPR1, GPR19, GPR21, GPR27 and GPR61 knockdown cells. We further found that the overexpression of these GPCRs enhanced Pls-mediated phosphorylation of ERK and Akt in cells. Most interestingly, the GPCRs-mediated cellular signaling was reduced significantly when the endogenous Pls were reduced. Our cumulative data, for the first time, suggest a possible mechanism for Pls-induced cellular signaling in the nervous system.

  16. Protein Signaling Networks from Single Cell Fluctuations and Information Theory Profiling

    Science.gov (United States)

    Shin, Young Shik; Remacle, F.; Fan, Rong; Hwang, Kiwook; Wei, Wei; Ahmad, Habib; Levine, R.D.; Heath, James R.

    2011-01-01

    Protein signaling networks among cells play critical roles in a host of pathophysiological processes, from inflammation to tumorigenesis. We report on an approach that integrates microfluidic cell handling, in situ protein secretion profiling, and information theory to determine an extracellular protein-signaling network and the role of perturbations. We assayed 12 proteins secreted from human macrophages that were subjected to lipopolysaccharide challenge, which emulates the macrophage-based innate immune responses against Gram-negative bacteria. We characterize the fluctuations in protein secretion of single cells, and of small cell colonies (n = 2, 3,···), as a function of colony size. Measuring the fluctuations permits a validation of the conditions required for the application of a quantitative version of the Le Chatelier's principle, as derived using information theory. This principle provides a quantitative prediction of the role of perturbations and allows a characterization of a protein-protein interaction network. PMID:21575571

  17. G Protein-Coupled Receptor Signaling in Stem Cells and Cancer.

    Science.gov (United States)

    Lynch, Jennifer R; Wang, Jenny Yingzi

    2016-05-11

    G protein-coupled receptors (GPCRs) are a large superfamily of cell-surface signaling proteins that bind extracellular ligands and transduce signals into cells via heterotrimeric G proteins. GPCRs are highly tractable drug targets. Aberrant expression of GPCRs and G proteins has been observed in various cancers and their importance in cancer stem cells has begun to be appreciated. We have recently reported essential roles for G protein-coupled receptor 84 (GPR84) and G protein subunit Gαq in the maintenance of cancer stem cells in acute myeloid leukemia. This review will discuss how GPCRs and G proteins regulate stem cells with a focus on cancer stem cells, as well as their implications for the development of novel targeted cancer therapies.

  18. G Protein-Coupled Receptor Signaling in Stem Cells and Cancer

    Directory of Open Access Journals (Sweden)

    Jennifer R. Lynch

    2016-05-01

    Full Text Available G protein-coupled receptors (GPCRs are a large superfamily of cell-surface signaling proteins that bind extracellular ligands and transduce signals into cells via heterotrimeric G proteins. GPCRs are highly tractable drug targets. Aberrant expression of GPCRs and G proteins has been observed in various cancers and their importance in cancer stem cells has begun to be appreciated. We have recently reported essential roles for G protein-coupled receptor 84 (GPR84 and G protein subunit Gαq in the maintenance of cancer stem cells in acute myeloid leukemia. This review will discuss how GPCRs and G proteins regulate stem cells with a focus on cancer stem cells, as well as their implications for the development of novel targeted cancer therapies.

  19. Shc adaptor proteins are key transducers of mitogenic signaling mediated by the G protein-coupled thrombin receptor

    DEFF Research Database (Denmark)

    Chen, Y; Grall, D; Salcini, A E

    1996-01-01

    The serine protease thrombin activates G protein signaling systems that lead to Ras activation and, in certain cells, proliferation. Whereas the steps leading to Ras activation by G protein-coupled receptors are not well defined, the mechanisms of Ras activation by receptor tyrosine kinases have......-insensitive proteins appear to mediate this effect, since (i) pertussis toxin pre-treatment of cells does not blunt the action of thrombin and (ii) Shc phosphorylation on tyrosine can be stimulated by the muscarinic m1 receptor. Shc phosphorylation does not appear to involve protein kinase C, since the addition of 4...

  20. Bone morphogenetic protein 2 signaling negatively modulates lymphatic development in vertebrate embryos

    DEFF Research Database (Denmark)

    Dunworth, William P; Cardona-Costa, Jose; Bozkulak, Esra Cagavi

    2014-01-01

    : Our aim was to delineate the role of bone morphogenetic protein (BMP) 2 signaling in lymphatic development. METHODS AND RESULTS: BMP2 signaling negatively regulates the formation of LECs. Developing LECs lack any detectable BMP signaling activity in both zebrafish and mouse embryos, and excess BMP2...... signaling in zebrafish embryos and mouse embryonic stem cell-derived embryoid bodies substantially decrease the emergence of LECs. Mechanistically, BMP2 signaling induces expression of miR-31 and miR-181a in a SMAD-dependent mechanism, which in turn results in attenuated expression of prospero homeobox...

  1. A synthetic peptide derived from the animo acid sequence of canine parvovirus structural proteins which defines a B cell epitope and elicits antiviral antibody in BALB c mice.

    NARCIS (Netherlands)

    G.F. Rimmelzwaan (Guus); J. Carlson; F.G.C.M. Uytdehaag (Fons); A.D.M.E. Osterhaus (Albert)

    1990-01-01

    textabstractSynthetic peptides, recombinant fusion proteins and mouse monoclonal antibodies were used to delineate a B cell epitope of the VP'2 structural protein of canine parvovirus (CPV). Although this epitope is not preferentially recognized in the normal antibody response to CPV, virus-specific

  2. DMPD: Regulation of innate immunity by suppressor of cytokine signaling (SOCS)proteins. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 18406369 Regulation of innate immunity by suppressor of cytokine signaling (SOCS)proteins...svg) (.html) (.csml) Show Regulation of innate immunity by suppressor of cytokine signaling (SOCS)proteins. ...PubmedID 18406369 Title Regulation of innate immunity by suppressor of cytokine signaling (SOCS)proteins

  3. Cell signaling, post-translational protein modifications and NMR spectroscopy

    International Nuclear Information System (INIS)

    Theillet, Francois-Xavier; Smet-Nocca, Caroline; Liokatis, Stamatios; Thongwichian, Rossukon; Kosten, Jonas; Yoon, Mi-Kyung; Kriwacki, Richard W.; Landrieu, Isabelle; Lippens, Guy; Selenko, Philipp

    2012-01-01

    Post-translationally modified proteins make up the majority of the proteome and establish, to a large part, the impressive level of functional diversity in higher, multi-cellular organisms. Most eukaryotic post-translational protein modifications (PTMs) denote reversible, covalent additions of small chemical entities such as phosphate-, acyl-, alkyl- and glycosyl-groups onto selected subsets of modifiable amino acids. In turn, these modifications induce highly specific changes in the chemical environments of individual protein residues, which are readily detected by high-resolution NMR spectroscopy. In the following, we provide a concise compendium of NMR characteristics of the main types of eukaryotic PTMs: serine, threonine, tyrosine and histidine phosphorylation, lysine acetylation, lysine and arginine methylation, and serine, threonine O-glycosylation. We further delineate the previously uncharacterized NMR properties of lysine propionylation, butyrylation, succinylation, malonylation and crotonylation, which, altogether, define an initial reference frame for comprehensive PTM studies by high-resolution NMR spectroscopy.

  4. Molecular characterization and expression pattern of X box-binding protein-1 (XBP1) in common carp (Cyprinus carpio L.): Indications for a role of XBP1 in antibacterial and antiviral immunity.

    Science.gov (United States)

    Li, Ting; Li, Hua; Peng, Shaoqing; Zhang, Fumiao; An, Liguo; Yang, Guiwen

    2017-08-01

    X box-binding protein-1 (XBP1) is a transcription factor that is essential for the unfolded protein response (UPR) and the differentiation of plasma cells, and some findings have also uncovered its function in innate immunity. XBP1 typically has two different transcripts, un-spliced (XBP1u) and spliced forms (XBP1s), but XBP1s is an active transcription factor in the regulation of target genes. To date, there is no evidence about the identification and function of XBP1 in common carp. Moreover, no data are currently available regarding the role of fish XBP1 in innate immunity. Thus, to determine whether XBP1 is involved in innate immune response in common carp, we cloned CcXBP1s and examined the expression of XBP1s and a XBP1s stimulated gene (IL-6) after Aeromonas hydrophila (A. hydrophila) and polyinosinic-polycytidylic acid (polyI:C) challenges. The results imply that CcXBP1s, as an active transcription factor, might play regulation roles in the antibacterial and antiviral innate immune responses of common carp. This allows us to gain new insights into the immunological function of XBP1 in fish innate immunity and the evolution of this important class of genes across vertebrates. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Disabled is a putative adaptor protein that functions during signaling by the sevenless receptor tyrosine kinase.

    Science.gov (United States)

    Le, N; Simon, M A

    1998-08-01

    DRK, the Drosophila homolog of the SH2-SH3 domain adaptor protein Grb2, is required during signaling by the sevenless receptor tyrosine kinase (SEV). One role of DRK is to provide a link between activated SEV and the Ras1 activator SOS. We have investigated the possibility that DRK performs other functions by identifying additional DRK-binding proteins. We show that the phosphotyrosine-binding (PTB) domain-containing protein Disabled (DAB) binds to the DRK SH3 domains. DAB is expressed in the ommatidial clusters, and loss of DAB function disrupts ommatidial development. Moreover, reduction of DAB function attenuates signaling by a constitutively activated SEV. Our biochemical analysis suggests that DAB binds SEV directly via its PTB domain, becomes tyrosine phosphorylated upon SEV activation, and then serves as an adaptor protein for SH2 domain-containing proteins. Taken together, these results indicate that DAB is a novel component of the SEV signaling pathway.

  6. Identification of two functional nuclear localization signals in the capsid protein of duck circovirus

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Qi-Wang; Zou, Jin-Feng; Wang, Xin [Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Shandong, Taian 271018 (China); Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong, Taian 271018 (China); Sun, Ya-Ni [College of Veterinary Medicine, Northwest A and F University, Shanxi, Yangling 712100 (China); Gao, Ji-Ming; Xie, Zhi-Jing [Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Shandong, Taian 271018 (China); Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong, Taian 271018 (China); Wang, Yu [Department of Basic Medical Sciences, Taishan Medical College, Shandong, Taian 271000 (China); Zhu, Yan-Li [Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Shandong, Taian 271018 (China); Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong, Taian 271018 (China); Jiang, Shi-Jin, E-mail: sjjiang@sdau.edu.cn [Department of Preventive Veterinary Medicine, College of Veterinary Medicine, Shandong Agricultural University, Shandong, Taian 271018 (China); Shandong Provincial Key Laboratory of Animal Biotechnology and Disease Control and Prevention, Shandong, Taian 271018 (China)

    2013-02-05

    The capsid protein (CP) of duck circovirus (DuCV) is the major immunogenic protein and has a high proportion of arginine residues concentrated at the N terminus of the protein, which inhibits efficient mRNA translation in prokaryotic expression systems. In this study, we investigated the subcellular distribution of DuCV CP expressed via recombinant baculoviruses in Sf9 cells and the DNA binding activities of the truncated recombinant DuCV CPs. The results showed that two independent bipartite nuclear localization signals (NLSs) situated at N-terminal 1-17 and 18-36 amino acid residue of the CP. Moreover, two expression level regulatory signals (ELRSs) and two DNA binding signals (DBSs) were also mapped to the N terminus of the protein and overlapped with the two NLSs. The ability of CP to bind DNA, coupled with the karyophilic nature of this protein, strongly suggests that it may be responsible for nuclear targeting of the viral genome.

  7. Identification of two functional nuclear localization signals in the capsid protein of duck circovirus

    International Nuclear Information System (INIS)

    Xiang, Qi-Wang; Zou, Jin-Feng; Wang, Xin; Sun, Ya-Ni; Gao, Ji-Ming; Xie, Zhi-Jing; Wang, Yu; Zhu, Yan-Li; Jiang, Shi-Jin

    2013-01-01

    The capsid protein (CP) of duck circovirus (DuCV) is the major immunogenic protein and has a high proportion of arginine residues concentrated at the N terminus of the protein, which inhibits efficient mRNA translation in prokaryotic expression systems. In this study, we investigated the subcellular distribution of DuCV CP expressed via recombinant baculoviruses in Sf9 cells and the DNA binding activities of the truncated recombinant DuCV CPs. The results showed that two independent bipartite nuclear localization signals (NLSs) situated at N-terminal 1–17 and 18–36 amino acid residue of the CP. Moreover, two expression level regulatory signals (ELRSs) and two DNA binding signals (DBSs) were also mapped to the N terminus of the protein and overlapped with the two NLSs. The ability of CP to bind DNA, coupled with the karyophilic nature of this protein, strongly suggests that it may be responsible for nuclear targeting of the viral genome.

  8. Gα and regulator of G-protein signaling (RGS) protein pairs maintain functional compatibility and conserved interaction interfaces throughout evolution despite frequent loss of RGS proteins in plants.

    Science.gov (United States)

    Hackenberg, Dieter; McKain, Michael R; Lee, Soon Goo; Roy Choudhury, Swarup; McCann, Tyler; Schreier, Spencer; Harkess, Alex; Pires, J Chris; Wong, Gane Ka-Shu; Jez, Joseph M; Kellogg, Elizabeth A; Pandey, Sona

    2017-10-01

    Signaling pathways regulated by heterotrimeric G-proteins exist in all eukaryotes. The regulator of G-protein signaling (RGS) proteins are key interactors and critical modulators of the Gα protein of the heterotrimer. However, while G-proteins are widespread in plants, RGS proteins have been reported to be missing from the entire monocot lineage, with two exceptions. A single amino acid substitution-based adaptive coevolution of the Gα:RGS proteins was proposed to enable the loss of RGS in monocots. We used a combination of evolutionary and biochemical analyses and homology modeling of the Gα and RGS proteins to address their expansion and its potential effects on the G-protein cycle in plants. Our results show that RGS proteins are widely distributed in the monocot lineage, despite their frequent loss. There is no support for the adaptive coevolution of the Gα:RGS protein pair based on single amino acid substitutions. RGS proteins interact with, and affect the activity of, Gα proteins from species with or without endogenous RGS. This cross-functional compatibility expands between the metazoan and plant kingdoms, illustrating striking conservation of their interaction interface. We propose that additional proteins or alternative mechanisms may exist which compensate for the loss of RGS in certain plant species. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.

  9. G Protein-coupled Receptors and Resistance to Inhibitors of Cholinesterase-8A (Ric-8A) Both Regulate the Regulator of G Protein Signaling 14 (RGS14)·Gαi1 Complex in Live Cells*

    OpenAIRE

    Vellano, Christopher P.; Maher, Ellen M.; Hepler, John R.; Blumer, Joe B.

    2011-01-01

    Background: Regulator of G protein signaling 14 (RGS14) is a G protein regulatory (GPR) protein that participates in unconventional G protein signaling independent of G protein-coupled receptors (GPCRs).

  10. Presenilin dependence of phospholipase C and protein kinase C signaling

    DEFF Research Database (Denmark)

    Dehvari, Nodi; Cedazo-Minguez, Angel; Isacsson, Ola

    2007-01-01

    -stimulated phospholipase C (PLC) activity which was gamma-secretase dependent. To further evaluate the dependence of PLC on PSs we measured PLC activity and the activation of variant protein kinase C (PKC) isoforms in mouse embryonic fibroblasts (MEFs) lacking either PS1, PS2, or both. PLC activity and PKCalpha...

  11. A two-step recognition of signal sequences determines the translocation efficiency of proteins.

    OpenAIRE

    Belin, D; Bost, S; Vassalli, J D; Strub, K

    1996-01-01

    The cytosolic and secreted, N-glycosylated, forms of plasminogen activator inhibitor-2 (PAI-2) are generated by facultative translocation. To study the molecular events that result in the bi-topological distribution of proteins, we determined in vitro the capacities of several signal sequences to bind the signal recognition particle (SRP) during targeting, and to promote vectorial transport of murine PAI-2 (mPAI-2). Interestingly, the six signal sequences we compared (mPAI-2 and three mutated...

  12. Cross talk between insulin and bone morphogenetic protein signaling systems in brown adipogenesis

    DEFF Research Database (Denmark)

    Zhang, Hongbin; Schulz, Tim J; Espinoza, Daniel O

    2010-01-01

    Both insulin and bone morphogenetic protein (BMP) signaling systems are important for adipocyte differentiation. Analysis of gene expression in BMP7-treated fibroblasts revealed a coordinated change in insulin signaling components by BMP7. To further investigate the cross talk between insulin...... BMP7's suppressive effect on pref-1 transcription. Together, these data suggest cross talk between the insulin and BMP signaling systems by which BMP7 can rescue brown adipogenesis in cells with insulin resistance....

  13. Low birthweight is associated with specific changes in muscle insulin-signalling protein expression

    DEFF Research Database (Denmark)

    Ozanne, SE; Jensen, CB; Tingey, KJ

    2005-01-01

    muscle in a human cohort and a rat model. METHODS: We recruited 20 young men with low birthweight (mean birthweight 2702+/-202 g) and 20 age-matched control subjects (mean birthweight 3801+/-99 g). Biopsies were obtained from the vastus lateralis muscle and protein expression of selected insulin......-signalling proteins was determined. Rats used for this study were male offspring born to dams fed a standard (20%) protein diet or a low (8%) protein diet during pregnancy and lactation. Protein expression was determined in soleus muscle from adult offspring. RESULTS: Low-birthweight subjects showed reduced muscle...... expression of protein kinase C (PKC)zeta, p85alpha, p110beta and GLUT4. PKCzeta, GLUT4 and p85 were also reduced in the muscle of rats fed a low-protein diet. Other proteins studied were unchanged in low-birthweight humans and in rats fed a low-protein diet when compared with control groups. CONCLUSIONS...

  14. Membrane Recruitment of the Non-receptor Protein GIV/Girdin (Gα-interacting, Vesicle-associated Protein/Girdin) Is Sufficient for Activating Heterotrimeric G Protein Signaling.

    Science.gov (United States)

    Parag-Sharma, Kshitij; Leyme, Anthony; DiGiacomo, Vincent; Marivin, Arthur; Broselid, Stefan; Garcia-Marcos, Mikel

    2016-12-30

    GIV (aka Girdin) is a guanine nucleotide exchange factor that activates heterotrimeric G protein signaling downstream of RTKs and integrins, thereby serving as a platform for signaling cascade cross-talk. GIV is recruited to the cytoplasmic tail of receptors upon stimulation, but the mechanism of activation of its G protein regulatory function is not well understood. Here we used assays in humanized yeast models and G protein activity biosensors in mammalian cells to investigate the role of GIV subcellular compartmentalization in regulating its ability to promote G protein signaling. We found that in unstimulated cells GIV does not co-fractionate with its substrate G protein Gα i3 on cell membranes and that constitutive membrane anchoring of GIV in yeast cells or rapid membrane translocation in mammalian cells via chemically induced dimerization leads to robust G protein activation. We show that membrane recruitment of the GIV "Gα binding and activating" motif alone is sufficient for G protein activation and that it does not require phosphomodification. Furthermore, we engineered a synthetic protein to show that recruitment of the GIV "Gα binding and activating" motif to membranes via association with active RTKs, instead of via chemically induced dimerization, is also sufficient for G protein activation. These results reveal that recruitment of GIV to membranes in close proximity to its substrate G protein is a major mechanism responsible for the activation of its G protein regulatory function. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  15. Antiviral therapy: a perspective

    Directory of Open Access Journals (Sweden)

    Shahidi Bonjar AH

    2016-02-01

    s recovery to a large extent depends on their general health status. EVAC would be for single use and appropriately disposed of after each detoxification procedure. When sufficient research has yielded positive results in animal models, EVAC could be used as a supportive treatment in humans along with conventional antiviral therapies. EVAC would not be suitable for all viral infections, but could be expected to decrease the casualties resulting from blood-borne viral infections. The EVAC approach would be efficient in terms of time, effort, and expenditure in the research and treatment of blood-borne viral infections. Keywords: blood, virus, infection, antiviral, sepsis, HIV, Ebola

  16. Antiviral Drug Research Proposal Activity

    Directory of Open Access Journals (Sweden)

    Lisa Injaian

    2011-03-01

    Full Text Available The development of antiviral drugs provides an excellent example of how basic and clinical research must be used together in order to achieve the final goal of treating disease. A Research Oriented Learning Activity was designed to help students to better understand how basic and clinical research can be combined toward a common goal. Through this project students gained a better understanding of the process of scientific research and increased their information literacy in the field of virology. The students worked as teams to research the many aspects involved in the antiviral drug design process, with each student becoming an "expert" in one aspect of the project. The Antiviral Drug Research Proposal (ADRP culminated with students presenting their proposals to their peers and local virologists in a poster session. Assessment data showed increased student awareness and knowledge of the research process and the steps involved in the development of antiviral drugs as a result of this activity.

  17. Protein Phosphatase 2A Signaling in Human Prostate Cancer

    Science.gov (United States)

    2014-08-01

    phosphatidylinositol 3’-kinase and Akt/protein kinase B. Cancer Res 1999;59:1449-53. (14) Grethe S, Porn -Ares MI. p38 MAPK regulates phosphorylation of Bad...growth and sig- nalling. Biochem J 2001;353:417–39. 15. Grethe S, Porn -Ares MI. p38 MAPK regulates phosphorylation of Bad via PP2A-dependent suppression of

  18. CD25 and CD69 induction by α4β1 outside-in signalling requires TCR early signalling complex proteins

    Science.gov (United States)

    Cimo, Ann-Marie; Ahmed, Zamal; McIntyre, Bradley W.; Lewis, Dorothy E.; Ladbury, John E.

    2013-01-01

    Distinct signalling pathways producing diverse cellular outcomes can utilize similar subsets of proteins. For example, proteins from the TCR (T-cell receptor) ESC (early signalling complex) are also involved in interferon-α receptor signalling. Defining the mechanism for how these proteins function within a given pathway is important in understanding the integration and communication of signalling networks with one another. We investigated the contributions of the TCR ESC proteins Lck (lymphocyte-specific kinase), ZAP-70 (ζ-chain-associated protein of 70 kDa), Vav1, SLP-76 [SH2 (Src homology 2)-domain-containing leukocyte protein of 76 kDa] and LAT (linker for activation of T-cells) to integrin outside-in signalling in human T-cells. Lck, ZAP-70, SLP-76, Vav1 and LAT were activated by α4β1 outside-in signalling, but in a manner different from TCR signalling. TCR stimulation recruits ESC proteins to activate the mitogen-activated protein kinase ERK (extracellular-signal-regulated kinase). α4β1 outside-in-mediated ERK activation did not require TCR ESC proteins. However, α4β1 outside-in signalling induced CD25 and co-stimulated CD69 and this was dependent on TCR ESC proteins. TCR and α4β1 outside-in signalling are integrated through the common use of TCR ESC proteins; however, these proteins display functionally distinct roles in these pathways. These novel insights into the cross-talk between integrin outside-in and TCR signalling pathways are highly relevant to the development of therapeutic strategies to overcome disease associated with T-cell deregulation. PMID:23758320

  19. Phosphatidylcholine Transfer Protein Interacts with Thioesterase Superfamily Member 2 to Attenuate Insulin Signaling

    OpenAIRE

    Ersoy, Baran A.; Tarun, Akansha; D’Aquino, Katharine; Hancer, Nancy J.; Ukomadu, Chinweike; White, Morris F.; Michel, Thomas; Manning, Brendan D.; Cohen, David E.

    2013-01-01

    Phosphatidylcholine transfer protein (PC-TP) is a phospholipid-binding protein that is enriched in liver and that interacts with thioesterase superfamily member 2 (THEM2). Mice lacking either protein exhibit improved hepatic glucose homeostasis and are resistant to diet-induced diabetes. Insulin receptor substrate 2 (IRS2) and mammalian target of rapamycin complex 1 (mTORC1) are key effectors of insulin signaling, which is attenuated in diabetes. We found that PC-TP inhibited IRS2, as evidenc...

  20. Recent Advances on the Role of G Protein-Coupled Receptors in Hypoxia-Mediated Signaling

    OpenAIRE

    Lappano, Rosamaria; Rigiracciolo, Damiano; De Marco, Paola; Avino, Silvia; Cappello, Anna Rita; Rosano, Camillo; Maggiolini, Marcello; De Francesco, Ernestina Marianna

    2016-01-01

    G protein-coupled receptors (GPCRs) are cell surface proteins mainly involved in signal transmission; however, they play a role also in several pathophysiological conditions. Chemically heterogeneous molecules like peptides, hormones, lipids, and neurotransmitters activate second messengers and induce several biological responses by binding to these seven transmembrane receptors, which are coupled to heterotrimeric G proteins. Recently, additional molecular mechanisms have been involved in GP...

  1. Diverse Regulation of Temperature Sensation by Trimeric G-Protein Signaling in Caenorhabditis elegans.

    Directory of Open Access Journals (Sweden)

    Tomoyo Ujisawa

    Full Text Available Temperature sensation by the nervous system is essential for life and proliferation of animals. The molecular-physiological mechanisms underlying temperature signaling have not been fully elucidated. We show here that diverse regulatory machinery underlies temperature sensation through trimeric G-protein signaling in the nematode Caenorhabditis elegans. Molecular-genetic studies demonstrated that cold tolerance is regulated by additive functions of three Gα proteins in a temperature-sensing neuron, ASJ, which is also known to be a light-sensing neuron. Optical recording of calcium concentration in ASJ upon temperature-changes demonstrated that three Gα proteins act in different aspects of temperature signaling. Calcium concentration changes in ASJ upon temperature change were unexpectedly decreased in a mutant defective in phosphodiesterase, which is well known as a negative regulator of calcium increase. Together, these data demonstrate commonalities and differences in the molecular components concerned with light and temperature signaling in a single sensory neuron.

  2. Diverse Regulation of Temperature Sensation by Trimeric G-Protein Signaling in Caenorhabditis elegans

    Science.gov (United States)

    Ujisawa, Tomoyo; Ohta, Akane; Uda-Yagi, Misato

    2016-01-01

    Temperature sensation by the nervous system is essential for life and proliferation of animals. The molecular-physiological mechanisms underlying temperature signaling have not been fully elucidated. We show here that diverse regulatory machinery underlies temperature sensation through trimeric G-protein signaling in the nematode Caenorhabditis elegans. Molecular-genetic studies demonstrated that cold tolerance is regulated by additive functions of three Gα proteins in a temperature-sensing neuron, ASJ, which is also known to be a light-sensing neuron. Optical recording of calcium concentration in ASJ upon temperature-changes demonstrated that three Gα proteins act in different aspects of temperature signaling. Calcium concentration changes in ASJ upon temperature change were unexpectedly decreased in a mutant defective in phosphodiesterase, which is well known as a negative regulator of calcium increase. Together, these data demonstrate commonalities and differences in the molecular components concerned with light and temperature signaling in a single sensory neuron. PMID:27788246

  3. Exercise and Glycemic Control: Focus on Redox Homeostasis and Redox-Sensitive Protein Signaling

    Science.gov (United States)

    Parker, Lewan; Shaw, Christopher S.; Stepto, Nigel K.; Levinger, Itamar

    2017-01-01

    Physical inactivity, excess energy consumption, and obesity are associated with elevated systemic oxidative stress and the sustained activation of redox-sensitive stress-activated protein kinase (SAPK) and mitogen-activated protein kinase signaling pathways. Sustained SAPK activation leads to aberrant insulin signaling, impaired glycemic control, and the development and progression of cardiometabolic disease. Paradoxically, acute exercise transiently increases oxidative stress and SAPK signaling, yet postexercise glycemic control and skeletal muscle function are enhanced. Furthermore, regular exercise leads to the upregulation of antioxidant defense, which likely assists in the mitigation of chronic oxidative stress-associated disease. In this review, we explore the complex spatiotemporal interplay between exercise, oxidative stress, and glycemic control, and highlight exercise-induced reactive oxygen species and redox-sensitive protein signaling as important regulators of glucose homeostasis. PMID:28529499

  4. Time-dependent, glucose-regulated Arabidopsis Regulator of G-protein Signaling 1 network

    Directory of Open Access Journals (Sweden)

    Dinesh Kumar Jaiswal

    2016-04-01

    Full Text Available Plants lack 7-transmembrane, G-protein coupled receptors (GPCRs because the G alpha subunit of the heterotrimeric G protein complex is “self-activating”—meaning that it spontaneously exchanges bound GDP for GTP without the need of a GPCR. In lieu of GPCRs, most plants have a seven transmembrane receptor-like regulator of G-protein signaling (RGS protein, a component of the complex that keeps G-protein signaling in its non-activated state. The addition of glucose physically uncouples AtRGS1 from the complex through specific endocytosis leaving the activated G protein at the plasma membrane. The complement of proteins in the AtRGS1/G-protein complex over time from glucose-induced endocytosis was profiled by immunoprecipitation coupled to mass spectrometry (IP-MS. A total of 119 proteins in the AtRGS1 complex were identified. Several known interactors of the complex were identified, thus validating the approach, but the vast majority (93/119 were not known previously. AtRGS1 protein interactions were dynamically modulated by d-glucose. At low glucose levels, the AtRGS1 complex is comprised of proteins involved in transport, stress and metabolism. After glucose application, the AtRGS1 complex rapidly sheds many of these proteins and recruits other proteins involved in vesicular trafficking and signal transduction. The profile of the AtRGS1 components answers several questions about the type of coat protein and vesicular trafficking GTPases used in AtRGS1 endocytosis and the function of endocytic AtRGS1.

  5. Neurodegeneration in Alzheimer Disease: Role of Amyloid Precursor Protein and Presenilin 1 Intracellular Signaling

    Directory of Open Access Journals (Sweden)

    Mario Nizzari

    2012-01-01

    Full Text Available Alzheimer disease (AD is a heterogeneous neurodegenerative disorder characterized by (1 progressive loss of synapses and neurons, (2 intracellular neurofibrillary tangles, composed of hyperphosphorylated Tau protein, and (3 amyloid plaques. Genetically, AD is linked to mutations in few proteins amyloid precursor protein (APP and presenilin 1 and 2 (PS1 and PS2. The molecular mechanisms underlying neurodegeneration in AD as well as the physiological function of APP are not yet known. A recent theory has proposed that APP and PS1 modulate intracellular signals to induce cell-cycle abnormalities responsible for neuronal death and possibly amyloid deposition. This hypothesis is supported by the presence of a complex network of proteins, clearly involved in the regulation of signal transduction mechanisms that interact with both APP and PS1. In this review we discuss the significance of novel finding related to cell-signaling events modulated by APP and PS1 in the development of neurodegeneration.

  6. WRKY proteins: signaling and regulation of expression during abiotic stress responses.

    Science.gov (United States)

    Banerjee, Aditya; Roychoudhury, Aryadeep

    2015-01-01

    WRKY proteins are emerging players in plant signaling and have been thoroughly reported to play important roles in plants under biotic stress like pathogen attack. However, recent advances in this field do reveal the enormous significance of these proteins in eliciting responses induced by abiotic stresses. WRKY proteins act as major transcription factors, either as positive or negative regulators. Specific WRKY factors which help in the expression of a cluster of stress-responsive genes are being targeted and genetically modified to induce improved abiotic stress tolerance in plants. The knowledge regarding the signaling cascade leading to the activation of the WRKY proteins, their interaction with other proteins of the signaling pathway, and the downstream genes activated by them are altogether vital for justified targeting of the WRKY genes. WRKY proteins have also been considered to generate tolerance against multiple abiotic stresses with possible roles in mediating a cross talk between abiotic and biotic stress responses. In this review, we have reckoned the diverse signaling pattern and biological functions of WRKY proteins throughout the plant kingdom along with the growing prospects in this field of research.

  7. Critical role for cross-linking of trimeric lectin domains of surfactant protein D in antiviral activity against influenza A virus

    DEFF Research Database (Denmark)

    Tecle, Tesfaldet; White, Mitchell R; Sørensen, Grith Lykke

    2008-01-01

    binding activity for some ligands and mediate some functional activities. The lung collectin SP-D (surfactant protein D) has strong neutralizing activity for IAVs (influenza A viruses) in vitro and in vivo, however, the NCRD derived from SP-D has weak viral-binding ability and lacks neutralizing activity...

  8. Outer Membrane Protein 25 of Brucella Activates Mitogen-Activated Protein Kinase Signal Pathway in Human Trophoblast Cells

    Directory of Open Access Journals (Sweden)

    Jing Zhang

    2017-12-01

    Full Text Available Outer membrane protein 25 (OMP25, a virulence factor from Brucella, plays an important role in maintaining the structural stability of Brucella. Mitogen-activated protein kinase (MAPK signal pathway widely exists in eukaryotic cells. In this study, human trophoblast cell line HPT-8 and BALB/c mice were infected with Brucella abortus 2308 strain (S2308 and 2308ΔOmp25 mutant strain. The expression of cytokines and activation of MAPK signal pathway were detected. We found that the expressions of tumor necrosis factor-α, interleukin-1, and interleukin-10 (IL-10 were increased in HPT-8 cells infected with S2308 and 2308ΔOmp25 mutant. S2308 also activated p38 phosphorylation protein, extracellular-regulated protein kinases (ERK, and Jun-N-terminal kinase (JNK from MAPK signal pathway. 2308ΔOmp25 could not activate p38, ERK, and JNK branches. Immunohistochemistry experiments showed that S2308 was able to activate phosphorylation of p38 and ERK in BABL/c mice. However, 2308ΔOmp25 could weakly activate phosphorylation of p38 and ERK. These results suggest that Omp25 played an important role in the process of Brucella activation of the MAPK signal pathway.

  9. IFN regulatory factor 1 restricts hepatitis E virus replication by activating STAT1 to induce antiviral IFN-stimulated genes.

    Science.gov (United States)

    Xu, Lei; Zhou, Xinying; Wang, Wenshi; Wang, Yijin; Yin, Yuebang; Laan, Luc J W van der; Sprengers, Dave; Metselaar, Herold J; Peppelenbosch, Maikel P; Pan, Qiuwei

    2016-10-01

    IFN regulatory factor 1 (IRF1) is one of the most important IFN-stimulated genes (ISGs) in cellular antiviral immunity. Although hepatitis E virus (HEV) is a leading cause of acute hepatitis worldwide, how ISGs counteract HEV infection is largely unknown. This study was conducted to investigate the effect of IRF1 on HEV replication. Multiple cell lines were used in 2 models that harbor HEV. In different HEV cell culture systems, IRF1 effectively inhibited HEV replication. IRF1 did not trigger IFN production, and chromatin immunoprecipitation sequencing data analysis revealed that IRF1 bound to the promoter region of signal transducers and activators of transcription 1 (STAT1). Functional assay confirmed that IRF1 could drive the transcription of STAT1, resulting in elevation of total and phosphorylated STAT1 proteins and further activating the transcription of a panel of downstream antiviral ISGs. By pharmacological inhibitors and RNAi-mediated gene-silencing approaches, we revealed that antiviral function of IRF1 is dependent on the JAK-STAT cascade. Furthermore, induction of ISGs and the anti-HEV effect of IRF1 overlapped that of IFNα, but was potentiated by ribavirin. We demonstrated that IRF1 effectively inhibits HEV replication through the activation of the JAK-STAT pathway, and the subsequent transcription of antiviral ISGs, but independent of IFN production.-Xu, L., Zhou, X., Wang, W., Wang, Y., Yin, Y., van der Laan, L. J. W., Sprengers, D., Metselaar, H. J., Peppelenbosch, M. P., Pan, Q. IFN regulatory factor 1 restricts hepatitis E virus replication by activating STAT1 to induce antiviral IFN-stimulated genes. © FASEB.

  10. Multistep Current Signal in Protein Translocation through Graphene Nanopores

    KAUST Repository

    Bonome, Emma Letizia

    2015-05-07

    © 2015 American Chemical Society. In nanopore sensing experiments, the properties of molecules are probed by the variation of ionic currents flowing through the nanopore. In this context, the electronic properties and the single-layer thickness of graphene constitute a major advantage for molecule characterization. Here we analyze the translocation pathway of the thioredoxin protein across a graphene nanopore, and the related ionic currents, by integrating two nonequilibrium molecular dynamics methods with a bioinformatic structural analysis. To obtain a qualitative picture of the translocation process and to identify salient features we performed unsupervised structural clustering on translocation conformations. This allowed us to identify some specific and robust translocation intermediates, characterized by significantly different ionic current flows. We found that the ion current strictly anticorrelates with the amount of pore occupancy by thioredoxin residues, providing a putative explanation of the multilevel current scenario observed in recently published translocation experiments.

  11. Redox modification of caveolar proteins in the cardiovascular system- role in cellular signalling and disease.

    Science.gov (United States)

    Bubb, Kristen J; Birgisdottir, Asa Birna; Tang, Owen; Hansen, Thomas; Figtree, Gemma A

    2017-08-01

    Rapid and coordinated release of a variety of reactive oxygen species (ROS) such as superoxide (O 2 .- ), hydrogen peroxide (H 2 O 2 ) and peroxynitrite, in specific microdomains, play a crucial role in cell signalling in the cardiovascular system. These reactions are mediated by reversible and functional modifications of a wide variety of key proteins. Dysregulation of this oxidative signalling occurs in almost all forms of cardiovascular disease (CVD), including at the very early phases. Despite the heavily publicized failure of "antioxidants" to improve CVD progression, pharmacotherapies such as those targeting the renin-angiotensin system, or statins, exert at least part of their large clinical benefit via modulating cellular redox signalling. Over 250 proteins, including receptors, ion channels and pumps, and signalling proteins are found in the caveolae. An increasing proportion of these are being recognized as redox regulated-proteins, that reside in the immediate vicinity of the two major cellular sources of ROS, nicotinamide adenine dinucleotide phosphate oxidase (Nox) and uncoupled endothelial nitric oxide synthase (eNOS). This review focuses on what is known about redox signalling within the caveolae, as well as endogenous protective mechanisms utilized by the cell, and new approaches to targeting dysregulated redox signalling in the caveolae as a therapeutic strategy in CVD. Copyright © 2017. Published by Elsevier Inc.

  12. Atypical Diabetic Foot Ulcer Keratinocyte Protein Signaling Correlates with Impaired Wound Healing

    Science.gov (United States)

    Hoke, Glenn D.; Ramos, Corrine; Hoke, Nicholas N.; Crossland, Mary C.; Shawler, Lisa G.

    2016-01-01

    Diabetes mellitus is associated with chronic diabetic foot ulcers (DFUs) and wound infections often resulting in lower extremity amputations. The protein signaling architecture of the mechanisms responsible for impaired DFU healing has not been characterized. In this preliminary clinical study, the intracellular levels of proteins involved in signal transduction networks relevant to wound healing were non-biasedly measured using reverse-phase protein arrays (RPPA) in keratinocytes isolated from DFU wound biopsies. RPPA allows for the simultaneous documentation and assessment of the signaling pathways active in each DFU. Thus, RPPA provides for the accurate mapping of wound healing pathways associated with apoptosis, proliferation, senescence, survival, and angiogenesis. From the study data, we have identified potential diagnostic, or predictive, biomarkers for DFU wound healing derived from the ratios of quantified signaling protein expressions within interconnected pathways. These biomarkers may allow physicians to personalize therapeutic strategies for DFU management on an individual basis based upon the signaling architecture present in each wound. Additionally, we have identified altered, interconnected signaling pathways within DFU keratinocytes that may help guide the development of therapeutics to modulate these dysregulated pathways, many of which parallel the therapeutic targets which are the hallmarks of molecular therapies for treating cancer. PMID:27840833

  13. Atypical Diabetic Foot Ulcer Keratinocyte Protein Signaling Correlates with Impaired Wound Healing.

    Science.gov (United States)

    Hoke, Glenn D; Ramos, Corrine; Hoke, Nicholas N; Crossland, Mary C; Shawler, Lisa G; Boykin, Joseph V

    2016-01-01

    Diabetes mellitus is associated with chronic diabetic foot ulcers (DFUs) and wound infections often resulting in lower extremity amputations. The protein signaling architecture of the mechanisms responsible for impaired DFU healing has not been characterized. In this preliminary clinical study, the intracellular levels of proteins involved in signal transduction networks relevant to wound healing were non-biasedly measured using reverse-phase protein arrays (RPPA) in keratinocytes isolated from DFU wound biopsies. RPPA allows for the simultaneous documentation and assessment of the signaling pathways active in each DFU. Thus, RPPA provides for the accurate mapping of wound healing pathways associated with apoptosis, proliferation, senescence, survival, and angiogenesis. From the study data, we have identified potential diagnostic, or predictive, biomarkers for DFU wound healing derived from the ratios of quantified signaling protein expressions within interconnected pathways. These biomarkers may allow physicians to personalize therapeutic strategies for DFU management on an individual basis based upon the signaling architecture present in each wound. Additionally, we have identified altered, interconnected signaling pathways within DFU keratinocytes that may help guide the development of therapeutics to modulate these dysregulated pathways, many of which parallel the therapeutic targets which are the hallmarks of molecular therapies for treating cancer.

  14. Mechanosensitive molecular networks involved in transducing resistance exercise-signals into muscle protein accretion

    Directory of Open Access Journals (Sweden)

    Emil Rindom

    2016-11-01

    Full Text Available Loss of skeletal muscle myofibrillar protein with disease and/or inactivity can severely deteriorate muscle strength and function. Strategies to counteract wasting of muscle myofibrillar protein are therefore desirable and invite for considerations on the potential superiority of specific modes of resistance exercise and/or the adequacy of low load resistance exercise regimens as well as underlying mechanisms. In this regard, delineation of the potentially mechanosensitive molecular mechanisms underlying muscle protein synthesis (MPS, may contribute to understanding on how differentiated resistance exercise can transduce a mechanical signal into stimulation of muscle accretion. Recent findings suggest specific upstream exercise-induced mechano-sensitive myocellular signaling pathways to converge on mammalian target of rapamycin complex 1 (mTORC1, to influence MPS. This may e.g. implicate mechanical activation of signaling through a diacylglycerol kinase (DGKζ-phosphatidic acid (PA axis or implicate integrin deformation to signal through a Focal adhesion kinase (FAK-Tuberous Sclerosis Complex 2TSC2-Ras homolog enriched in brain (Rheb axis. Moreover, since initiation of translation is reliant on mRNA, it is also relevant to consider potentially mechanosensitive signaling pathways involved in muscle myofibrillar gene transcription and whether some of these pathways converge with those affecting mTORC1 activation for MPS. In this regard, recent findings suggest how mechanical stress may implicate integrin deformation and/or actin dynamics to signal through a Ras homolog gene family member A protein (RhoA-striated muscle activator of Rho signaling (STARS axis or how it may implicate deformation of Notch to affect Bone Morphogenetic Protein (BMP signaling through a small mother of decapentaplegic (Smad axis.

  15. Effect of Wnt-1 inducible signaling pathway protein-2 (WISP-2/CCN5), a downstream protein of Wnt signaling, on adipocyte differentiation

    International Nuclear Information System (INIS)

    Inadera, Hidekuni; Shimomura, Akiko; Tachibana, Shinjiro

    2009-01-01

    Wnt signaling negatively regulates adipocyte differentiation, and ectopic expression of Wnt-1 in 3T3-L1 cells induces several downstream molecules of Wnt signaling, including Wnt-1 inducible signaling pathway protein (WISP)-2. In this study, we examined the role of WISP-2 in the process of adipocyte differentiation using an in vitro cell culture system. In the differentiation of 3T3-L1 cells, WISP-2 expression was observed in growing cells and declined thereafter. In the mitotic clonal expansion phase of adipocyte differentiation, WISP-2 expression was transiently down-regulated concurrently with up-regulation of CCAAT/enhancer-binding protein δ expression. Treatment of 3T3-L1 cells in the differentiation medium with lithium, an activator of Wnt signaling, inhibited the differentiation process with concomitant induction of WISP-2. Treatment of differentiated cells with lithium induced de-differentiation as evidenced by profound reduction of peroxisome proliferator-activator receptor γ expression and concomitant induction of WISP-2. However, de-differentiation of differentiated cells induced by tumor necrosis factor-α did not induce WISP-2 expression. To directly examine the effect of WISP-2 on adipocyte differentiation, 3T3-L1 cells were infected with a retrovirus carrying WISP-2. Although forced expression of WISP-2 inhibited preadipocyte proliferation, it had no effect on adipocyte differentiation. Thus, although WISP-2 is a downstream protein of Wnt signaling, the role of WISP-2 on adipocyte differentiation may be marginal, at least in this in vitro culture model.

  16. L-Alanylglutamine inhibits signaling proteins that activate protein degradation, but does not affect proteins that activate protein synthesis after an acute resistance exercise.

    Science.gov (United States)

    Wang, Wanyi; Choi, Ran Hee; Solares, Geoffrey J; Tseng, Hung-Min; Ding, Zhenping; Kim, Kyoungrae; Ivy, John L

    2015-07-01

    Sustamine™ (SUS) is a dipeptide composed of alanine and glutamine (AlaGln). Glutamine has been suggested to increase muscle protein accretion; however, the underlying molecular mechanisms of glutamine on muscle protein metabolism following resistance exercise have not been fully addressed. In the present study, 2-month-old rats climbed a ladder 10 times with a weight equal to 75 % of their body mass attached at the tail. Rats were then orally administered one of four solutions: placebo (PLA-glycine = 0.52 g/kg), whey protein (WP = 0.4 g/kg), low dose of SUS (LSUS = 0.1 g/kg), or high dose of SUS (HSUS = 0.5 g/kg). An additional group of sedentary (SED) rats was intubated with glycine (0.52 g/kg) at the same time as the ladder-climbing rats. Blood samples were collected immediately after exercise and at either 20 or 40 min after recovery. The flexor hallucis longus (FHL), a muscle used for climbing, was excised at 20 or 40 min post exercise and analyzed for proteins regulating protein synthesis and degradation. All supplements elevated the phosphorylation of FOXO3A above SED at 20 min post exercise, but only the SUS supplements significantly reduced the phosphorylation of AMPK and NF-kB p65. SUS supplements had no effect on mTOR signaling, but WP supplementation yielded a greater phosphorylation of mTOR, p70S6k, and rpS6 compared with PLA at 20 min post exercise. However, by 40 min post exercise, phosphorylation of mTOR and rpS6 in PLA had risen to levels not different than WP. These results suggest that SUS blocks the activation of intracellular signals for MPB, whereas WP accelerates mRNA translation.

  17. Discovery of intramolecular signal transduction network based on a new protein dynamics model of energy dissipation.

    Directory of Open Access Journals (Sweden)

    Cheng-Wei Ma

    Full Text Available A novel approach to reveal intramolecular signal transduction network is proposed in this work. To this end, a new algorithm of network construction is developed, which is based on a new protein dynamics model of energy dissipation. A key feature of this approach is that direction information is specified after inferring protein residue-residue interaction network involved in the process of signal transduction. This enables fundamental analysis of the regulation hierarchy and identification of regulation hubs of the signaling network. A well-studied allosteric enzyme, E. coli aspartokinase III, is used as a model system to demonstrate the new method. Comparison with experimental results shows that the new approach is able to predict all the sites that have been experimentally proved to desensitize allosteric regulation of the enzyme. In addition, the signal transduction network shows a clear preference for specific structural regions, secondary structural types and residue conservation. Occurrence of super-hubs in the network indicates that allosteric regulation tends to gather residues with high connection ability to collectively facilitate the signaling process. Furthermore, a new parameter of propagation coefficient is defined to determine the propagation capability of residues within a signal transduction network. In conclusion, the new approach is useful for fundamental understanding of the process of intramolecular signal transduction and thus has significant impact on rational design of novel allosteric proteins.

  18. Regulator of G protein signaling 5 (RGS5) inhibits sonic hedgehog function in mouse cortical neurons.

    Science.gov (United States)

    Liu, Chuanliang; Hu, Qiongqiong; Jing, Jia; Zhang, Yun; Jin, Jing; Zhang, Liulei; Mu, Lili; Liu, Yumei; Sun, Bo; Zhang, Tongshuai; Kong, Qingfei; Wang, Guangyou; Wang, Dandan; Zhang, Yao; Liu, Xijun; Zhao, Wei; Wang, Jinghua; Feng, Tao; Li, Hulun

    2017-09-01

    Regulator of G protein signaling 5 (RGS5) acts as a GTPase-activating protein (GAP) for the Gαi subunit and negatively regulates G protein-coupled receptor signaling. However, its presence and function in postmitotic differentiated primary neurons remains largely uncharacterized. During neural development, sonic hedgehog (Shh) signaling is involved in cell signaling pathways via Gαi activity. In particular, Shh signaling is essential for embryonic neural tube patterning, which has been implicated in neuronal polarization involving neurite outgrowth. Here, we examined whether RGS5 regulates Shh signaling in neurons. RGS5 transcripts were found to be expressed in cortical neurons and their expression gradually declined in a time-dependent manner in culture system. When an adenovirus expressing RGS5 was introduced into an in vitro cell culture model of cortical neurons, RGS5 overexpression significantly reduced neurite outgrowth and FM4-64 uptake, while cAMP-PKA signaling was also affected. These findings suggest that RGS5 inhibits Shh function during neurite outgrowth and the presynaptic terminals of primary cortical neurons mature via modulation of cAMP. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. 14-3-3 Proteins in Plant Hormone Signaling: Doing Several Things at Once

    Directory of Open Access Journals (Sweden)

    Lorenzo Camoni

    2018-03-01

    Full Text Available In this review we highlight the advances achieved in the investigation of the role of 14-3-3 proteins in hormone signaling, biosynthesis, and transport. 14-3-3 proteins are a family of conserved molecules that target a number of protein clients through their ability to recognize well-defined phosphorylated motifs. As a result, they regulate several cellular processes, ranging from metabolism to transport, growth, development, and stress response. High-throughput proteomic data and two-hybrid screen demonstrate that 14-3-3 proteins physically interact with many protein clients involved in the biosynthesis or signaling pathways of the main plant hormones, while increasing functional evidence indicates that 14-3-3-target interactions play pivotal regulatory roles. These advances provide a framework of our understanding of plant hormone action, suggesting that 14-3-3 proteins act as hubs of a cellular web encompassing different signaling pathways, transducing and integrating diverse hormone signals in the regulation of physiological processes.

  20. Protein kinase D1 signaling in angiogenic gene expression and VEGF-mediated angiogenesis

    Directory of Open Access Journals (Sweden)

    Bin eRen MD, Phd, FAHA

    2016-05-01

    Full Text Available Protein kinase D 1 (PKD-1 is a signaling kinase important in fundamental cell functions including migration, proliferation and differentiation. PKD-1 is also a key regulator of gene expression and angiogenesis that is essential for cardiovascular development and tumor progression. Further understanding molecular aspects of PKD-1 signaling in the regulation of angiogenesis may have translational implications in obesity, cardiovascular disease and cancer. The author will summarize and provide the insights into molecular mechanisms by which PKD-1 regulates transcriptional expression of angiogenic genes, focusing on the transcriptional regulation of CD36 by PKD-1-FoxO1 signaling axis along with the potential implications of this axis in arterial differentiation and morphogenesis. He will also discuss a new concept of dynamic balance between proangiogenic and antiangiogenic signaling in determining angiogenic switch, and stress how PKD-1 signaling regulates VEGF signaling-mediated angiogenesis.

  1. Cell density signal protein suitable for treatment of connective tissue injuries and defects

    Science.gov (United States)

    Schwarz, Richard I.

    2002-08-13

    Identification, isolation and partial sequencing of a cell density protein produced by fibroblastic cells. The cell density signal protein comprising a 14 amino acid peptide or a fragment, variant, mutant or analog thereof, the deduced cDNA sequence from the 14 amino acid peptide, a recombinant protein, protein and peptide-specific antibodies, and the use of the peptide and peptide-specific antibodies as therapeutic agents for regulation of cell differentiation and proliferation. A method for treatment and repair of connective tissue and tendon injuries, collagen deficiency, and connective tissue defects.

  2. The Battle between Rotavirus and Its Host for Control of the Interferon Signaling Pathway

    Science.gov (United States)

    Arnold, Michelle M.; Sen, Adrish; Greenberg, Harry B.; Patton, John T.

    2013-01-01

    Viral pathogens must overcome innate antiviral responses to replicate successfully in the host organism. Some of the mechanisms viruses use to interfere with antiviral responses in the infected cell include preventing detection of viral components, perturbing the function of transcription factors that initiate antiviral responses, and inhibiting downstream signal transduction. RNA viruses with small genomes and limited coding space often express multifunctional proteins that modulate several aspects of the normal host response to infection. One such virus, rotavirus, is an important pediatric pathogen that causes severe gastroenteritis, leading to ∼450,000 deaths globally each year. In this review, we discuss the nature of the innate antiviral responses triggered by rotavirus infection and the viral mechanisms for inhibiting these responses. PMID:23359266

  3. Phospholipase D and phosphatidic acid in plant defence response: from protein-protein and lipid-protein interactions to hormone signalling.

    Science.gov (United States)

    Zhao, Jian

    2015-04-01

    Phospholipase Ds (PLDs) and PLD-derived phosphatidic acids (PAs) play vital roles in plant hormonal and environmental responses and various cellular dynamics. Recent studies have further expanded the functions of PLDs and PAs into plant-microbe interaction. The molecular diversities and redundant functions make PLD-PA an important signalling complex regulating lipid metabolism, cytoskeleton dynamics, vesicle trafficking, and hormonal signalling in plant defence through protein-protein and protein-lipid interactions or hormone signalling. Different PLD-PA signalling complexes and their targets have emerged as fast-growing research topics for understanding their numerous but not yet established roles in modifying pathogen perception, signal transduction, and downstream defence responses. Meanwhile, advanced lipidomics tools have allowed researchers to reveal further the mechanisms of PLD-PA signalling complexes in regulating lipid metabolism and signalling, and their impacts on jasmonic acid/oxylipins, salicylic acid, and other hormone signalling pathways that essentially mediate plant defence responses. This review attempts to summarize the progress made in spatial and temporal PLD/PA signalling as well as PLD/PA-mediated modification of plant defence. It presents an in-depth discussion on the functions and potential mechanisms of PLD-PA complexes in regulating actin filament/microtubule cytoskeleton, vesicle trafficking, and hormonal signalling, and in influencing lipid metabolism-derived metabolites as critical signalling components in plant defence responses. The discussion puts PLD-PA in a broader context in order to guide future research. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  4. LDL receptor-related protein 1 regulates the abundance of diverse cell-signaling proteins in the plasma membrane proteome.

    Science.gov (United States)

    Gaultier, Alban; Simon, Gabriel; Niessen, Sherry; Dix, Melissa; Takimoto, Shinako; Cravatt, Benjamin F; Gonias, Steven L

    2010-12-03

    LDL receptor-related protein 1 (LRP1) is an endocytic receptor, reported to regulate the abundance of other receptors in the plasma membrane, including uPAR and tissue factor. The goal of this study was to identify novel plasma membrane proteins, involved in cell-signaling, that are regulated by LRP1. Membrane protein ectodomains were prepared from RAW 264.7 cells in which LRP1 was silenced and control cells using protease K. Peptides were identified by LC-MS/MS. By analysis of spectral counts, 31 transmembrane and secreted proteins were regulated in abundance at least 2-fold when LRP1 was silenced. Validation studies confirmed that semaphorin4D (Sema4D), plexin domain-containing protein-1 (Plxdc1), and neuropilin-1 were more abundant in the membranes of LRP1 gene-silenced cells. Regulation of Plxdc1 by LRP1 was confirmed in CHO cells, as a second model system. Plxdc1 coimmunoprecipitated with LRP1 from extracts of RAW 264.7 cells and mouse liver. Although Sema4D did not coimmunoprecipitate with LRP1, the cell-surface level of Sema4D was increased by RAP, which binds to LRP1 and inhibits binding of other ligands. These studies identify Plxdc1, Sema4D, and neuropilin-1 as novel LRP1-regulated cell-signaling proteins. Overall, LRP1 emerges as a generalized regulator of the plasma membrane proteome.

  5. ANTI-VIRAL ACTIVITY OF GLYCIRRHETINIC AND GLYCIRRHIZIC ACIDS

    Directory of Open Access Journals (Sweden)

    V. V. Zarubaev

    2016-01-01

    Full Text Available Influenza is a highly contagious human disease. In the course of use of antiviral drugs drug-resistant strains of the virus are formed, resulting in reduced efficiency of the chemotherapy. The review describes the biological activity of glycirrhetinic (GLA and glycirrhizic (GA acids in terms of their use as a therapeutic agent for viral infections. So, these compounds are against a broad spectrum of viruses, including herpes, corona-, alphaand flaviviruses, human immunodeficiency virus, vaccinia virus, poliovirus type I, vesicular stomatitis virus and influenza A virus. These data indicate that anti-viral effect of these compounds is due to several types of activity — direct antiviral effects, effects on cellular proand anti-viral and immunomodulating pathways, in particular by activation of innate immunity system. GA interferes with early steps of the viral reproductive cycle such as virus binding to its receptor, the absorption of the virus by endocytosis or virus decapsidation in the cytoplasm. This is due to the effect of GA-induced reduction of membrane fluidity. Thus, one mechanism for the antiviral activity of GA is that GA molecule increases the rigidity of cellular and viral membranes after incorporation in there. This results in increasing of energy threshold required for the formation of negative curvature at the fusion zones, as well as difficult lateral migration of the virus-receptor complexes. In addition, glycyrrhizin prevents interaction of viral nucleoprotein with cellular protein HMGB1, which is necessary for the viral life cycle. Glycyrrhizin also inhibits the induction of oxidative stress during influenza infection, exhibiting antioxidant properties, which leads to a reduction of virus-induced production of cytokines/chemokines, without affecting the replication of the virus. A wide spectrum of biological activity and effect on various aspects of the viral pathogenesis substantiate the effect of GA and GLA as a component

  6. Leverage principle of retardation signal in titration of double protein via chip moving reaction boundary electrophoresis.

    Science.gov (United States)

    Zhang, Liu-Xia; Cao, Yi-Ren; Xiao, Hua; Liu, Xiao-Ping; Liu, Shao-Rong; Meng, Qing-Hua; Fan, Liu-Yin; Cao, Cheng-Xi

    2016-03-15

    In the present work we address a simple, rapid and quantitative analytical method for detection of different proteins present in biological samples. For this, we proposed the model of titration of double protein (TDP) and its relevant leverage theory relied on the retardation signal of chip moving reaction boundary electrophoresis (MRBE). The leverage principle showed that the product of the first protein content and its absolute retardation signal is equal to that of the second protein content and its absolute one. To manifest the model, we achieved theoretical self-evidence for the demonstration of the leverage principle at first. Then relevant experiments were conducted on the TDP-MRBE chip. The results revealed that (i) there was a leverage principle of retardation signal within the TDP of two pure proteins, and (ii) a lever also existed within these two complex protein samples, evidently demonstrating the validity of TDP model and leverage theory in MRBE chip. It was also showed that the proposed technique could provide a rapid and simple quantitative analysis of two protein samples in a mixture. Finally, we successfully applied the developed technique for the quantification of soymilk in adulterated infant formula. The TDP-MRBE opens up a new window for the detection of adulteration ratio of the poor food (milk) in blended high quality one. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Antiviral therapy: a perspective.

    Science.gov (United States)

    Shahidi Bonjar, Amir Hashem

    2016-01-01

    research has yielded positive results in animal models, EVAC could be used as a supportive treatment in humans along with conventional antiviral therapies. EVAC would not be suitable for all viral infections, but could be expected to decrease the casualties resulting from blood-borne viral infections. The EVAC approach would be efficient in terms of time, effort, and expenditure in the research and treatment of blood-borne viral infections.

  8. Signal Recognition Particle 54 kD Protein (SRP54 from the Marine Sponge Geodia cydonium

    Directory of Open Access Journals (Sweden)

    Sonja Durajlija-Žinić

    2002-01-01

    Full Text Available In the systematic search for phylogenetically conserved proteins in the simplest and most ancient extant metazoan phylum – Porifera, we have identified and analyzed a cDNA encoding the signal recognition particle 54 kD protein (SRP54 from the marine sponge Geodia cydonium (Demospongiae. The signal recognition particle (SRP is a universally conserved ribonucleoprotein complex of a very ancient origin, comprising SRP RNA and several proteins (six in mammals. The nucleotide sequence of the sponge cDNA predicts a protein of 499 amino acid residues with a calculated Mr of 55175. G. cydonium SRP54 displays unusually high overall similarity (90 % with human/mammalian SRP54 proteins, higher than with Drosophila melanogaster (88 %, or Caenorhabditis elegans (82 %. The same was found for the majority of known and phylogenetically conserved proteins from sponges, indicating that the molecular evolutionary rates in protein coding genes in Porifera as well as in highly developed mammals (vertebrates are slower, when compared with the rates in homologous genes from invertebrates (insects, nematodes. Therefore, genes/proteins from sponges might be the best candidates for the reconstruction of ancient structures of proteins and genome/proteome complexity in the ancestral organism, common to all multicellular animals.

  9. The Antiviral Effect of Baicalin on Enterovirus 71 In Vitro

    Directory of Open Access Journals (Sweden)

    Xiang Li

    2015-08-01

    Full Text Available Baicalin is a flavonoid compound extracted from Scutellaria roots that has been reported to possess antibacterial, anti-inflammatory, and antiviral activities. However, the antiviral effect of baicalin on enterovirus 71 (EV71 is still unknown. In this study, we found that baicalin showed inhibitory activity on EV71 infection and was independent of direct virucidal or prophylactic effect and inhibitory viral absorption. The expressions of EV71/3D mRNA and polymerase were significantly blocked by baicalin treatment at early stages of EV71 infection. In addition, baicalin could decrease the expressions of FasL and caspase-3, as well as inhibit the apoptosis of EV71-infected human embryonal rhabdomyosarcoma (RD cells. Altogether, these results indicate that baicalin exhibits potent antiviral effect on EV71 infection, probably through inhibiting EV71/3D polymerase expression and Fas/FasL signaling pathways.

  10. G protein-coupled receptor (GPCR) signaling via heterotrimeric G proteins from endosomes.

    Science.gov (United States)

    Tsvetanova, Nikoleta G; Irannejad, Roshanak; von Zastrow, Mark

    2015-03-13

    Some G protein-coupled receptors (GPCRs), in addition to activating heterotrimeric G proteins in the plasma membrane, appear to elicit a "second wave" of G protein activation after ligand-induced internalization. We briefly summarize evidence supporting this view and then discuss what is presently known about the functional significance of GPCR-G protein activation in endosomes. Endosomal activation can shape the cellular response temporally by prolonging its overall duration, and may shape the response spatially by moving the location of intracellular second messenger production relative to effectors. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. Improved Protein Arrays for Quantitative Systems Analysis of the Dynamics of Signaling Pathway Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chin-Rang [National Inst. of Health (NIH), Bethesda, MD (United States). National Heart, Lung and Blood Inst.

    2013-12-11

    Astronauts and workers in nuclear plants who repeatedly exposed to low doses of ionizing radiation (IR, <10 cGy) are likely to incur specific changes in signal transduction and gene expression in various tissues of their body. Remarkable advances in high throughput genomics and proteomics technologies enable researchers to broaden their focus from examining single gene/protein kinetics to better understanding global gene/protein expression profiling and biological pathway analyses, namely Systems Biology. An ultimate goal of systems biology is to develop dynamic mathematical models of interacting biological systems capable of simulating living systems in a computer. This Glue Grant is to complement Dr. Boothman’s existing DOE grant (No. DE-FG02-06ER64186) entitled “The IGF1/IGF-1R-MAPK-Secretory Clusterin (sCLU) Pathway: Mediator of a Low Dose IR-Inducible Bystander Effect” to develop sensitive and quantitative proteomic technology that suitable for low dose radiobiology researches. An improved version of quantitative protein array platform utilizing linear Quantum dot signaling for systematically measuring protein levels and phosphorylation states for systems biology modeling is presented. The signals are amplified by a confocal laser Quantum dot scanner resulting in ~1000-fold more sensitivity than traditional Western blots and show the good linearity that is impossible for the signals of HRP-amplification. Therefore this improved protein array technology is suitable to detect weak responses of low dose radiation. Software is developed to facilitate the quantitative readout of signaling network activities. Kinetics of EGFRvIII mutant signaling was analyzed to quantify cross-talks between EGFR and other signaling pathways.

  12. Integration of protein phosphorylation, acetylation, and methylation data sets to outline lung cancer signaling networks.

    Science.gov (United States)

    Grimes, Mark; Hall, Benjamin; Foltz, Lauren; Levy, Tyler; Rikova, Klarisa; Gaiser, Jeremiah; Cook, William; Smirnova, Ekaterina; Wheeler, Travis; Clark, Neil R; Lachmann, Alexander; Zhang, Bin; Hornbeck, Peter; Ma'ayan, Avi; Comb, Michael

    2018-05-22

    Protein posttranslational modifications (PTMs) have typically been studied independently, yet many proteins are modified by more than one PTM type, and cell signaling pathways somehow integrate this information. We coupled immunoprecipitation using PTM-specific antibodies with tandem mass tag (TMT) mass spectrometry to simultaneously examine phosphorylation, methylation, and acetylation in 45 lung cancer cell lines compared to normal lung tissue and to cell lines treated with anticancer drugs. This simultaneous, large-scale, integrative analysis of these PTMs using a cluster-filtered network (CFN) approach revealed that cell signaling pathways were outlined by clustering patterns in PTMs. We used the t-distributed stochastic neighbor embedding (t-SNE) method to identify PTM clusters and then integrated each with known protein-protein interactions (PPIs) to elucidate functional cell signaling pathways. The CFN identified known and previously unknown cell signaling pathways in lung cancer cells that were not present in normal lung epithelial tissue. In various proteins modified by more than one type of PTM, the incidence of those PTMs exhibited inverse relationships, suggesting that molecular exclusive "OR" gates determine a large number of signal transduction events. We also showed that the acetyltransferase EP300 appears to be a hub in the network of pathways involving different PTMs. In addition, the data shed light on the mechanism of action of geldanamycin, an HSP90 inhibitor. Together, the findings reveal that cell signaling pathways mediated by acetylation, methylation, and phosphorylation regulate the cytoskeleton, membrane traffic, and RNA binding protein-mediated control of gene expression. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  13. DMPD: Suppressor of cytokine signaling (SOCS) 2, a protein with multiple functions. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 17070092 Suppressor of cytokine signaling (SOCS) 2, a protein with multiple function...Epub 2006 Oct 27. (.png) (.svg) (.html) (.csml) Show Suppressor of cytokine signaling (SOCS) 2, a protein with multiple function...SOCS) 2, a protein with multiple functions. Authors Rico-Bautista E, Flores-Morales A, Fernandez-Perez L. Pu

  14. DMPD: G-protein-coupled receptor expression, function, and signaling in macrophages. [Dynamic Macrophage Pathway CSML Database

    Lifescience Database Archive (English)

    Full Text Available 17456803 G-protein-coupled receptor expression, function, and signaling in macropha...2007 Apr 24. (.png) (.svg) (.html) (.csml) Show G-protein-coupled receptor expression, function, and signali...ng in macrophages. PubmedID 17456803 Title G-protein-coupled receptor expression, function

  15. S1P receptor signalling and RGS proteins; expression and function in vascular smooth muscle cells and transfected CHO cells

    NARCIS (Netherlands)

    Hendriks-Balk, Mariëlle C.; van Loenen, Pieter B.; Hajji, Najat; Michel, Martin C.; Peters, Stephan L. M.; Alewijnse, Astrid E.

    2009-01-01

    Sphingosine-1-phosphate (S1P) signalling via G protein-coupled receptors is important for the regulation of cell function and differentiation. Specific Regulators of G protein Signalling (RGS) proteins modulate the function of these receptors in many cell types including vascular smooth muscle cells

  16. Jatropha curcas Protein Concentrate Stimulates Insulin Signaling, Lipogenesis, Protein Synthesis and the PKCα Pathway in Rat Liver.

    Science.gov (United States)

    León-López, Liliana; Márquez-Mota, Claudia C; Velázquez-Villegas, Laura A; Gálvez-Mariscal, Amanda; Arrieta-Báez, Daniel; Dávila-Ortiz, Gloria; Tovar, Armando R; Torres, Nimbe

    2015-09-01

    Jatropha curcas is an oil seed plant that belongs to the Euphorbiaceae family. Nontoxic genotypes have been reported in Mexico. The purpose of the present work was to evaluate the effect of a Mexican variety of J. curcas protein concentrate (JCP) on weight gain, biochemical parameters, and the expression of genes and proteins involved in insulin signaling, lipogenesis, cholesterol and protein synthesis in rats. The results demonstrated that short-term consumption of JCP increased serum glucose, insulin, triglycerides and cholesterol levels as well as the expression of transcription factors involved in lipogenesis and cholesterol synthesis (SREBP-1 and LXRα). Moreover, there was an increase in insulin signaling mediated by Akt phosphorylation and mTOR. JCP also increased PKCα protein abundance and the activation of downstream signaling pathway targets such as the AP1 and NF-κB transcription factors typically activated by phorbol esters. These results suggested that phorbol esters are present in JCP, and that they could be involved in the activation of PKC which may be responsible for the high insulin secretion and consequently the activation of insulin-dependent pathways. Our data suggest that this Mexican Jatropha variety contains toxic compounds that produce negative metabolic effects which require caution when using in the applications of Jatropha-based products in medicine and nutrition.

  17. Receptor density balances signal stimulation and attenuation in membrane-assembled complexes of bacterial chemotaxis signaling proteins

    Science.gov (United States)

    Besschetnova, Tatiana Y.; Montefusco, David J.; Asinas, Abdalin E.; Shrout, Anthony L.; Antommattei, Frances M.; Weis, Robert M.

    2008-01-01

    All cells possess transmembrane signaling systems that function in the environment of the lipid bilayer. In the Escherichia coli chemotaxis pathway, the binding of attractants to a two-dimensional array of receptors and signaling proteins simultaneously inhibits an associated kinase and stimulates receptor methylation—a slower process that restores kinase activity. These two opposing effects lead to robust adaptation toward stimuli through a physical mechanism that is not understood. Here, we provide evidence of a counterbalancing influence exerted by receptor density on kinase stimulation and receptor methylation. Receptor signaling complexes were reconstituted over a range of defined surface concentrations by using a template-directed assembly method, and the kinase and receptor methylation activities were measured. Kinase activity and methylation rates were both found to vary significantly with surface concentration—yet in opposite ways: samples prepared at high surface densities stimulated kinase activity more effectively than low-density samples, whereas lower surface densities produced greater methylation rates than higher densities. FRET experiments demonstrated that the cooperative change in kinase activity coincided with a change in the arrangement of the membrane-associated receptor domains. The counterbalancing influence of density on receptor methylation and kinase stimulation leads naturally to a model for signal regulation that is compatible with the known logic of the E. coli pathway. Density-dependent mechanisms are likely to be general and may operate when two or more membrane-related processes are influenced differently by the two-dimensional concentration of pathway elements. PMID:18711126

  18. Protein Phosphatase 2A in the Regulation of Wnt Signaling, Stem Cells, and Cancer.

    Science.gov (United States)

    Thompson, Joshua J; Williams, Christopher S

    2018-02-26

    Protein phosphorylation is a ubiquitous cellular process that allows for the nuanced and reversible regulation of protein activity. Protein phosphatase 2A (PP2A) is a heterotrimeric serine-threonine phosphatase-composed of a structural, regulatory, and catalytic subunit-that controls a variety of cellular events via protein dephosphorylation. While much is known about PP2A and its basic biochemistry, the diversity of its components-especially the multitude of regulatory subunits-has impeded the determination of PP2A function. As a consequence of this complexity, PP2A has been shown to both positively and negatively regulate signaling networks such as the Wnt pathway. Wnt signaling modulates major developmental processes, and is a dominant mediator of stem cell self-renewal, cell fate, and cancer stem cells. Because PP2A affects Wnt signaling both positively and negatively and at multiple levels, further understanding of this complex dynamic may ultimately provide insight into stem cell biology and how to better treat cancers that result from alterations in Wnt signaling. This review will summarize literature that implicates PP2A as a tumor suppressor, explore PP2A mutations identified in human malignancy, and focus on PP2A in the regulation of Wnt signaling and stem cells so as to better understand how aberrancy in this pathway can contribute to tumorigenesis.

  19. Arrestin-related proteins mediate pH signaling in fungi

    OpenAIRE

    Herranz, Silvia; Rodríguez, José M.; Bussink, Henk-Jan; Sánchez-Ferrero, Juan C.; Arst, Herbert N.; Peñalva, Miguel A.; Vincent, Olivier

    2005-01-01

    Metazoan arrestins bind to seven-transmembrane (7TM) receptors to regulate function. Aspergillus nidulans PalF, a protein involved in the fungal ambient pH signaling pathway, contains arrestin N-terminal and C-terminal domains and binds strongly to two different regions within the C-terminal cytoplasmic tail of the 7TM, putative pH sensor PalH. Upon exposure to alkaline ambient pH, PalF is phosphorylated and, like mammalian β-arrestins, ubiquitinated in a signal-dependent and 7TM protein-depe...

  20. Machines vs. ensembles: effective MAPK signaling through heterogeneous sets of protein complexes.

    Directory of Open Access Journals (Sweden)

    Ryan Suderman

    Full Text Available Despite the importance of intracellular signaling networks, there is currently no consensus regarding the fundamental nature of the protein complexes such networks employ. One prominent view involves stable signaling machines with well-defined quaternary structures. The combinatorial complexity of signaling networks has led to an opposing perspective, namely that signaling proceeds via heterogeneous pleiomorphic ensembles of transient complexes. Since many hypotheses regarding network function rely on how we conceptualize signaling complexes, resolving this issue is a central problem in systems biology. Unfortunately, direct experimental characterization of these complexes has proven technologically difficult, while combinatorial complexity has prevented traditional modeling methods from approaching this question. Here we employ rule-based modeling, a technique that overcomes these limitations, to construct a model of the yeast pheromone signaling network. We found that this model exhibits significant ensemble character while generating reliable responses that match experimental observations. To contrast the ensemble behavior, we constructed a model that employs hierarchical assembly pathways to produce scaffold-based signaling machines. We found that this machine model could not replicate the experimentally observed combinatorial inhibition that arises when the scaffold is overexpressed. This finding provides evidence against the hierarchical assembly of machines in the pheromone signaling network and suggests that machines and ensembles may serve distinct purposes in vivo. In some cases, e.g. core enzymatic activities like protein synthesis and degradation, machines assembled via hierarchical energy landscapes may provide functional stability for the cell. In other cases, such as signaling, ensembles may represent a form of weak linkage, facilitating variation and plasticity in network evolution. The capacity of ensembles to signal effectively

  1. Identification of a nuclear localization signal in the retinitis pigmentosa-mutated RP26 protein, ceramide kinase-like protein

    International Nuclear Information System (INIS)

    Inagaki, Yuichi; Mitsutake, Susumu; Igarashi, Yasuyuki

    2006-01-01

    Retinitis pigmentosa (RP) is a genetically heterogeneous disease characterized by degeneration of the retina. A mutation in a new ceramide kinase (CERK) homologous gene, named CERK-like protein (CERKL), was found to cause autosomal recessive retinitis pigmentosa (RP26). Here, we show a point mutation of one of two putative nuclear localization signal (NLS) sequences inhibited the nuclear localization of the protein. Furthermore, the tetra-GFP-tagged NLS, which cannot passively enter the nucleus, was observed not only in the nucleus but also in the nucleolus. Our results provide First evidence of the active nuclear import of CERKL and suggest that the identified NLS might be responsible for nucleolar retention of the protein. As recent studies have shown other RP-related proteins are localized in the nucleus or the nucleolus, our identification of NLS in CERKL suggests that CERKL likely plays important roles for retinal functions in the nucleus and the nucleolus

  2. Viral ancestors of antiviral systems.

    Science.gov (United States)

    Villarreal, Luis P

    2011-10-01

    All life must survive their corresponding viruses. Thus antiviral systems are essential in all living organisms. Remnants of virus derived information are also found in all life forms but have historically been considered mostly as junk DNA. However, such virus derived information can strongly affect host susceptibility to viruses. In this review, I evaluate the role viruses have had in the origin and evolution of host antiviral systems. From Archaea through bacteria and from simple to complex eukaryotes I trace the viral components that became essential elements of antiviral immunity. I conclude with a reexamination of the 'Big Bang' theory for the emergence of the adaptive immune system in vertebrates by horizontal transfer and note how viruses could have and did provide crucial and coordinated features.

  3. Viral Ancestors of Antiviral Systems

    Directory of Open Access Journals (Sweden)

    Luis P. Villarreal

    2011-10-01

    Full Text Available All life must survive their corresponding viruses. Thus antiviral systems are essential in all living organisms. Remnants of virus derived information are also found in all life forms but have historically been considered mostly as junk DNA. However, such virus derived information can strongly affect host susceptibility to viruses. In this review, I evaluate the role viruses have had in the origin and evolution of host antiviral systems. From Archaea through bacteria and from simple to complex eukaryotes I trace the viral components that became essential elements of antiviral immunity. I conclude with a reexamination of the ‘Big Bang’ theory for the emergence of the adaptive immune system in vertebrates by horizontal transfer and note how viruses could have and did provide crucial and coordinated features.

  4. 14-3-3 Proteins Buffer Intracellular Calcium Sensing Receptors to Constrain Signaling.

    Directory of Open Access Journals (Sweden)

    Michael P Grant

    Full Text Available Calcium sensing receptors (CaSR interact with 14-3-3 binding proteins at a carboxyl terminal arginine-rich motif. Mutations identified in patients with familial hypocalciuric hypercalcemia, autosomal dominant hypocalcemia, pancreatitis or idiopathic epilepsy support the functional importance of this motif. We combined total internal reflection fluorescence microscopy and biochemical approaches to determine the mechanism of 14-3-3 protein regulation of CaSR signaling. Loss of 14-3-3 binding caused increased basal CaSR signaling and plasma membrane levels, and a significantly larger signaling-evoked increase in plasma membrane receptors. Block of core glycosylation with tunicamycin demonstrated that changes in plasma membrane CaSR levels were due to differences in exocytic rate. Western blotting to quantify time-dependent changes in maturation of expressed wt CaSR and a 14-3-3 protein binding-defective mutant demonstrated that signaling increases synthesis to maintain constant levels of the immaturely and maturely glycosylated forms. CaSR thus operates by a feed-forward mechanism, whereby signaling not only induces anterograde trafficking of nascent receptors but also increases biosynthesis to maintain steady state levels of net cellular CaSR. Overall, these studies suggest that 14-3-3 binding at the carboxyl terminus provides an important buffering mechanism to increase the intracellular pool of CaSR available for signaling-evoked trafficking, but attenuates trafficking to control the dynamic range of responses to extracellular calcium.

  5. Hormone response element binding proteins: novel regulators of vitamin D and estrogen signaling.

    Science.gov (United States)

    Lisse, Thomas S; Hewison, Martin; Adams, John S

    2011-03-01

    Insights from vitamin D-resistant New World primates and their human homologues as models of natural and pathological insensitivity to sterol/steroid action have uncovered a family of novel intracellular vitamin D and estrogen regulatory proteins involved in hormone action. The proteins, known as "vitamin D or estrogen response element-binding proteins", behave as potent cis-acting, transdominant regulators to inhibit steroid receptor binding to DNA response elements and is responsible for vitamin D and estrogen resistances. This set of interactors belongs to the heterogeneous nuclear ribonucleoprotein (hnRNP) family of previously known pre-mRNA-interacting proteins. This review provides new insights into the mechanism by which these novel regulators of signaling and metabolism can act to regulate responses to vitamin D and estrogen. In addition the review also describes other molecules that are known to influence nuclear receptor signaling through interaction with hormone response elements. Copyright © 2011 Elsevier Inc. All rights reserved.

  6. Role of Cbl-associated protein/ponsin in receptor tyrosine kinase signaling and cell adhesion

    Directory of Open Access Journals (Sweden)

    Ritva Tikkanen

    2012-10-01

    Full Text Available The Cbl-associated protein/ponsin (CAP is an adaptor protein that contains a so-called Sorbin homology (SoHo domain and three Src homology 3 (SH3 domains which are engaged in diverse protein-protein interactions. CAP has been shown to function in the regulation of the actin cytoskeleton and cell adhesion and to be involved in the differentiation of muscle cells and adipocytes. In addition, it participates in signaling pathways through several receptor tyrosine kinases such as insulin and neurotrophin receptors. In the last couple of years, several studies have shed light on the details of these processes and identified novel interaction partners of CAP. In this review, we summarize these recent findings and provide an overview on the function of CAP especially in cell adhesion and membrane receptor signaling.

  7. The inhibition of IGF-1 signaling promotes proteostasis by enhancing protein aggregation and deposition.

    Science.gov (United States)

    Moll, Lorna; Ben-Gedalya, Tziona; Reuveni, Hadas; Cohen, Ehud

    2016-04-01

    The discovery that the alteration of aging by reducing the activity of the insulin/IGF-1 signaling (IIS) cascade protects nematodes and mice from neurodegeneration-linked, toxic protein aggregation (proteotoxicity) raises the prospect that IIS inhibitors bear therapeutic potential to counter neurodegenerative diseases. Recently, we reported that NT219, a highly efficient IGF-1 signaling inhibitor, protects model worms from the aggregation of amyloid β peptide and polyglutamine peptides that are linked to the manifestation of Alzheimer's and Huntington's diseases, respectively. Here, we employed cultured cell systems to investigate whether NT219 promotes protein homeostasis (proteostasis) in mammalian cells and to explore its underlying mechanisms. We found that NT219 enhances the aggregation of misfolded prion protein and promotes its deposition in quality control compartments known as "aggresomes." NT219 also elevates the levels of certain molecular chaperones but, surprisingly, reduces proteasome activity and impairs autophagy. Our findings show that IGF-1 signaling inhibitors in general and NT219 in particular can promote proteostasis in mammalian cells by hyperaggregating hazardous proteins, thereby bearing the potential to postpone the onset and slow the progression of neurodegenerative illnesses in the elderly.-Moll, L., Ben-Gedalya, T., Reuveni, H., Cohen, E. The inhibition of IGF-1 signaling promotes proteostasis by enhancing protein aggregation and deposition. © FASEB.

  8. Sequence analysis reveals how G protein-coupled receptors transduce the signal to the G protein.

    NARCIS (Netherlands)

    Oliveira, L.; Paiva, P.B.; Paiva, A.C.; Vriend, G.

    2003-01-01

    Sequence entropy-variability plots based on alignments of very large numbers of sequences-can indicate the location in proteins of the main active site and modulator sites. In the previous article in this issue, we applied this observation to a series of well-studied proteins and concluded that it

  9. A proteomics strategy to elucidate functional protein-protein interactions applied to EGF signaling

    DEFF Research Database (Denmark)

    Blagoev, B.; Kratchmarova, I.; Ong, S.E.

    2003-01-01

    Mass spectrometry-based proteomics can reveal protein-protein interactions on a large scale, but it has been difficult to separate background binding from functionally important interactions and still preserve weak binders. To investigate the epidermal growth factor receptor (EGFR) pathway, we em...

  10. Neuronal RING finger protein 11 (RNF11 regulates canonical NF-κB signaling

    Directory of Open Access Journals (Sweden)

    Pranski Elaine L

    2012-04-01

    Full Text Available Abstract Background The RING domain-containing protein RING finger protein 11 (RNF11 is a member of the A20 ubiquitin-editing protein complex and modulates peripheral NF-κB signaling. RNF11 is robustly expressed in neurons and colocalizes with a population of α-synuclein-positive Lewy bodies and neurites in Parkinson disease patients. The NF-κB pathway has an important role in the vertebrate nervous system, where the absence of NF-κB activity during development can result in learning and memory deficits, whereas chronic NF-κB activation is associated with persistent neuroinflammation. We examined the functional role of RNF11 with respect to canonical NF-κB signaling in neurons to gain understanding of the tight association of inflammatory pathways, including NF-κB, with the pathogenesis of neurodegenerative diseases. Methods and results Luciferase assays were employed to assess NF-κB activity under targeted short hairpin RNA (shRNA knockdown of RNF11 in human neuroblastoma cells and murine primary neurons, which suggested that RNF11 acts as a negative regulator of canonical neuronal NF-κB signaling. These results were further supported by analyses of p65 translocation to the nucleus following depletion of RNF11. Coimmunoprecipitation experiments indicated that RNF11 associates with members of the A20 ubiquitin-editing protein complex in neurons. Site-directed mutagenesis of the myristoylation domain, which is necessary for endosomal targeting of RNF11, altered the impact of RNF11 on NF-κB signaling and abrogated RNF11’s association with the A20 ubiquitin-editing protein complex. A partial effect on canonical NF-κB signaling and an association with the A20 ubiquitin-editing protein complex was observed with mutagenesis of the PPxY motif, a proline-rich region involved in Nedd4-like protein interactions. Last, shRNA-mediated reduction of RNF11 in neurons and neuronal cell lines elevated levels of monocyte chemoattractant protein 1 and

  11. Coordinated Regulation of Insulin Signaling by the Protein Tyrosine Phosphatases PTP1B and TCPTP

    Science.gov (United States)

    Galic, Sandra; Hauser, Christine; Kahn, Barbara B.; Haj, Fawaz G.; Neel, Benjamin G.; Tonks, Nicholas K.; Tiganis, Tony

    2005-01-01

    The protein tyrosine phosphatase PTP1B is a negative regulator of insulin signaling and a therapeutic target for type 2 diabetes. Our previous studies have shown that the closely related tyrosine phosphatase TCPTP might also contribute to the regulation of insulin receptor (IR) signaling in vivo (S. Galic, M. Klingler-Hoffmann, M. T. Fodero-Tavoletti, M. A. Puryer, T. C. Meng, N. K. Tonks, and T. Tiganis, Mol. Cell. Biol. 23:2096-2108, 2003). Here we show that PTP1B and TCPTP function in a coordinated and temporally distinct manner to achieve an overall regulation of IR phosphorylation and signaling. Whereas insulin-induced phosphatidylinositol 3-kinase/Akt signaling was prolonged in both TCPTP−/− and PTP1B−/− immortalized mouse embryo fibroblasts (MEFs), mitogen-activated protein kinase ERK1/2 signaling was elevated only in PTP1B-null MEFs. By using phosphorylation-specific antibodies, we demonstrate that both IR β-subunit Y1162/Y1163 and Y972 phosphorylation are elevated in PTP1B−/− MEFs, whereas Y972 phosphorylation was elevated and Y1162/Y1163 phosphorylation was sustained in TCPTP−/− MEFs, indicating that PTP1B and TCPTP differentially contribute to the regulation of IR phosphorylation and signaling. Consistent with this, suppression of TCPTP protein levels by RNA interference in PTP1B−/− MEFs resulted in no change in ERK1/2 signaling but caused prolonged Akt activation and Y1162/Y1163 phosphorylation. These results demonstrate that PTP1B and TCPTP are not redundant in insulin signaling and that they act to control both common as well as distinct insulin signaling pathways in the same cell. PMID:15632081

  12. Henipaviruses Employ a Multifaceted Approach to Evade the Antiviral Interferon Response

    Directory of Open Access Journals (Sweden)

    Megan L. Shaw

    2009-12-01

    Full Text Available Hendra and Nipah virus, which constitute the genus Henipavirus, are zoonotic paramyxoviruses that have been associated with sporadic outbreaks of severe disease and mortality in humans since their emergence in the late 1990s. Similar to other paramyxoviruses, their ability to evade the host interferon (IFN response is conferred by the P gene. The henipavirus P gene encodes four proteins; the P, V, W and C proteins, which have all been described to inhibit the antiviral response. Further studies have revealed that these proteins have overlapping but unique properties which enable the virus to block multiple signaling pathways in the IFN response. The best characterized of these is the JAK-STAT signaling pathway which is targeted by the P, V and W proteins via an interaction with the transcription factor STAT1. In addition the V and W proteins can both limit virus-induced induction of IFN but they appear to do this via distinct mechanisms that rely on unique sequences in their C-terminal domains. The ability to generate recombinant Nipah viruses now gives us the opportunity to determine the precise role for each of these proteins and address their contribution to pathogenicity. Additionally, the question of whether these multiple anti-IFN strategies are all active in the different mammalian hosts for henipaviruses, particularly the fruit bat reservoir, warrants further exploration.

  13. Phosphotyrosine Signaling Proteins that Drive Oncogenesis Tend to be Highly Interconnected*

    OpenAIRE

    Koytiger, Grigoriy; Kaushansky, Alexis; Gordus, Andrew; Rush, John; Sorger, Peter K.; MacBeath, Gavin

    2013-01-01

    Mutation and overexpression of receptor tyrosine kinases or the proteins they regulate serve as oncogenic drivers in diverse cancers. To better understand receptor tyrosine kinase signaling and its link to oncogenesis, we used protein microarrays to systematically and quantitatively measure interactions between virtually every SH2 or PTB domain encoded in the human genome and all known sites of tyrosine phosphorylation on 40 receptor tyrosine kinases and on most of the SH2 and PTB domain-cont...

  14. Wnt Signaling Translocates Lys48-Linked Polyubiquitinated Proteins to the Lysosomal Pathway

    Directory of Open Access Journals (Sweden)

    Hyunjoon Kim

    2015-05-01

    Full Text Available Cellular proteins are degraded in either proteasomes or lysosomes depending on the types of ubiquitin chains that covalently modify them. It is not known whether the choice between these two pathways is physiologically regulated. The Lys48-polyubiquitin chain is the major signal directing proteins for degradation in proteasomes. Here, we report the unexpected finding that canonical Wnt signaling translocates some K48-linked polyubiquitinated proteins to the endolysosomal pathway. Proteasomal target proteins, such as β-catenin, Smad1, and Smad4, were targeted into endolysosomes in a process dependent on GSK3 activity. Relocalization was also dependent on Axin1 and the multivesicular body (MVB proteins HRS/Vps27 and Vps4. The Wnt-induced accumulation of K48-linked polyubiquitinated proteins in endolysosomal organelles was accompanied by a transient decrease in cellular levels of free mono-ubiquitin, which may contribute to Wnt-regulated stabilization of proteins (Wnt/STOP. We conclude that Wnt redirects Lys48-polyubiquitinated proteins that are normally degraded in proteasomes to endolysosomes.

  15. Antiviral agents: structural basis of action and rational design.

    Science.gov (United States)

    Menéndez-Arias, Luis; Gago, Federico

    2013-01-01

    During the last 30 years, significant progress has been made in the development of novel antiviral drugs, mainly crystallizing in the establishment of potent antiretroviral therapies and the approval of drugs inhibiting hepatitis C virus replication. Although major targets of antiviral intervention involve intracellular processes required for the synthesis of viral proteins and nucleic acids, a number of inhibitors blocking virus assembly, budding, maturation, entry or uncoating act on virions or viral capsids. In this review, we focus on the drug discovery process while presenting the currently used methodologies to identify novel antiviral drugs by using a computer-based approach. We provide examples illustrating structure-based antiviral drug development, specifically neuraminidase inhibitors against influenza virus (e.g. oseltamivir and zanamivir) and human immunodeficiency virus type 1 protease inhibitors (i.e. the development of darunavir from early peptidomimetic compounds such as saquinavir). A number of drugs in preclinical development acting against picornaviruses, hepatitis B virus and human immunodeficiency virus and their mechanism of action are presented to show how viral capsids can be exploited as targets of antiviral therapy.

  16. Antiviral potency and functional analysis of tetherin orthologues encoded by horse and donkey.

    Science.gov (United States)

    Yin, Xin; Guo, Miaomiao; Gu, Qinyong; Wu, Xingliang; Wei, Ping; Wang, Xiaojun

    2014-08-27

    Tetherin is an interferon-inducible host cell factor that blocks the viral particle release of the enveloped viruses. Most knowledge regarding the interaction between tetherin and viruses has been obtained using the primate lentiviral system. However, much less is known about the functional roles of tetherin on other lentiviruses. Equine infectious anemia virus (EIAV) is an important macrophage-tropic lentivirus that has been widely used as a practical model for investigating the evolution of the host-virus relationship. The host range of EIAV is reported to include all members of the Equidae family. However, EIAV has different clinical responses in horse and donkey. It's intriguing to investigate the similarities and differences between the tetherin orthologues encoded by horse and donkey. We report here that there are two equine tetherin orthologues. Compared to horse tetherin, there are three valine amino acid deletions within the transmembrane domain and three distinct mutations within the ectodomain of donkey tetherin. However, the antiviral activity of donkey tetherin was not affected by amino acid deletion or substitution. In addition, both tetherin orthologues encoded by horse and donkey are similarly sensitive to EIAV Env protein, and equally activate NF-κB signaling. Our data suggest that both tetherin orthologues encoded by horse and donkey showed similar antiviral activities and abilities to induce NF-κB signaling. In addition, the phenomenon about the differential responses of horses and donkeys to infection with EIAV was not related with the differences in the structure of the corresponding tetherin orthologues.

  17. Posttranslational protein S-palmitoylation and the compartmentalization of signaling molecules in neurons

    Directory of Open Access Journals (Sweden)

    SEAN I PATTERSON

    2002-01-01

    Full Text Available Protein domains play a fundamental role in the spatial and temporal organization of intracellular signaling systems. While protein phosphorylation has long been known to modify the interactions that underlie this organization, the dynamic cycling of lipids should now be included amongst the posttranslational processes determining specificity in signal transduction. The characteristics of this process are reminiscent of the properties of protein and lipid phosphorylation in determining compartmentalization through SH2 or PH domains. Recent studies have confirmed the functional importance of protein S-palmitoylation in the compartmentalization of signaling molecules that support normal physiological function in cell division and apoptosis, and synaptic transmission and neurite outgrowth. In neurons, S-palmitoylation and targeting of proteins to rafts are regulated differentially in development by a number of processes, including some related to synaptogenesis and synaptic plasticity. Alterations in the S-palmitoylation state of proteins substantially affect their cellular function, raising the possibility of new therapeutic targets in cancer and nervous system injury and disease.

  18. Protein redox chemistry: post-translational cysteine modifications that regulate signal transduction and drug pharmacology

    Directory of Open Access Journals (Sweden)

    Revati eWani

    2014-10-01

    Full Text Available The perception of reactive oxygen species (ROS has evolved over the past decade from agents of cellular damage to secondary messengers which modify signaling proteins in physiology and the disease state (e.g. cancer. New protein targets of specific oxidation are rapidly being identified. One emerging class of redox modification occurs to the thiol side chain of cysteine residues which can produce multiple chemically-distinct alterations to the protein (e.g. sulfenic/sulfinic/sulfonic acid, disulfides. These post-translational modifications (PTM are shown to affect the protein structure and function. Because redox-sensitive proteins can traffic between subcellular compartments that have different redox environments, cysteine oxidation enables a spatio-temporal control to signaling. Understanding ramifications of these oxidative modifications to the functions of signaling proteins is crucial for understanding cellular regulation as well as for informed-drug discovery process. The effects of EGFR oxidation of Cys797 on inhibitor pharmacology are presented to illustrate the principle. Taken together, cysteine redox PTM can impact both cell biology and drug pharmacology.

  19. Suppressor of cytokine signaling 1 interacts with oncogenic lymphocyte-specific protein tyrosine kinase.

    Science.gov (United States)

    Venkitachalam, Srividya; Chueh, Fu-Yu; Leong, King-Fu; Pabich, Samantha; Yu, Chao-Lan

    2011-03-01

    Lymphocyte-specific protein tyrosine kinase (Lck) plays a key role in T cell signal transduction and is tightly regulated by phosphorylation and dephosphorylation. Lck can function as an oncoprotein when overexpressed or constantly activated by mutations. Our previous studies showed that Lck-induced cellular transformation could be suppressed by enforced expression of suppressor of cytokine signaling 1 (SOCS1), a SOCS family member involved in the negative feedback control of cytokine signaling. We observed attenuated Lck kinase activity in SOCS1-expressing cells, suggesting an important role of SOCS in regulating Lck functions. It remains largely unknown whether and how SOCS proteins interact with the oncogenic Lck kinase. Here, we report that among four SOCS family proteins, SOCS1, SOCS2, SOCS3 and CIS (cytokine-inducible SH2 domain containing protein), SOCS1 has the highest affinity in binding to the oncogenic Lck kinase. We identified the positive regulatory phosphotyrosine 394 residue in the kinase domain as the key interacting determinant in Lck. Additionally, the Lck kinase domain alone is sufficient to bind SOCS1. While the SH2 domain in SOCS1 is important in its association with the oncogenic Lck kinase, other functional domains may also contribute to overall binding affinity. These findings provide important mechanistic insights into the role of SOCS proteins as tumor suppressors in cells transformed by oncogenic protein tyrosine kinases.

  20. A single peroxisomal targeting signal mediates matrix protein import in diatoms.

    Directory of Open Access Journals (Sweden)

    Nicola H Gonzalez

    Full Text Available Peroxisomes are single membrane bound compartments. They are thought to be present in almost all eukaryotic cells, although the bulk of our knowledge about peroxisomes has been generated from only a handful of model organisms. Peroxisomal matrix proteins are synthesized cytosolically and posttranslationally imported into the peroxisomal matrix. The import is generally thought to be mediated by two different targeting signals. These are respectively recognized by the two import receptor proteins Pex5 and Pex7, which facilitate transport across the peroxisomal membrane. Here, we show the first in vivo localization studies of peroxisomes in a representative organism of the ecologically relevant group of diatoms using fluorescence and transmission electron microscopy. By expression of various homologous and heterologous fusion proteins we demonstrate that targeting of Phaeodactylum tricornutum peroxisomal matrix proteins is mediated only by PTS1 targeting signals, also for proteins that are in other systems imported via a PTS2 mode of action. Additional in silico analyses suggest this surprising finding may also apply to further diatoms. Our data suggest that loss of the PTS2 peroxisomal import signal is not reserved to Caenorhabditis elegans as a single exception, but has also occurred in evolutionary divergent organisms. Obviously, targeting switching from PTS2 to PTS1 across different major eukaryotic groups might have occurred for different reasons. Thus, our findings question the widespread assumption that import of peroxisomal matrix proteins is generally mediated by two different targeting signals. Our results implicate that there apparently must have been an event causing the loss of one targeting signal even in the group of diatoms. Different possibilities are discussed that indicate multiple reasons for the detected targeting switching from PTS2 to PTS1.

  1. Efficient secretory expression of recombinant proteins in Escherichia coli with a novel actinomycete signal peptide.

    Science.gov (United States)

    Cui, Yanbing; Meng, Yiwei; Zhang, Juan; Cheng, Bin; Yin, Huijia; Gao, Chao; Xu, Ping; Yang, Chunyu

    2017-01-01

    In well-established heterologous hosts, such as Escherichia coli, recombinant proteins are usually intracellular and frequently found as inclusion bodies-especially proteins possessing high rare codon content. In this study, successful secretory expression of three hydrolases, in a constructed inducible or constitutive system, was achieved by fusion with a novel signal peptide (Kp-SP) from an actinomycete. The signal peptide efficiently enabled extracellular protein secretion and also contributed to the active expression of the intracellular recombinant proteins. The thermophilic α-amylase gene of Bacillus licheniformis was fused with Kp-SP. Both recombinants, carrying inducible and constitutive plasmids, showed remarkable increases in extracellular and intracellular amylolytic activity. Amylase activity was observed to be > 10-fold in recombinant cultures with the constitutive plasmid, pBSPPc, compared to that in recombinants lacking Kp-SP. Further, the signal peptide enabled efficient secretion of a thermophilic cellulase into the culture medium, as demonstrated by larger halo zones and increased enzymatic activities detected in both constructs from different plasmids. For heterologous proteins with a high proportion of rare codons, it is difficult to obtain high expression in E. coli owing to the codon bias. Here, the fusion of an archaeal homologue of the amylase encoding gene, FSA, with Kp-SP resulted in > 5-fold higher extracellular activity. The successful extracellular expression of the amylase indicated that the signal peptide also contributed significantly to its active expression and signified the potential value of this novel and versatile signal peptide in recombinant protein production. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Signaling by Kit protein-tyrosine kinase--the stem cell factor receptor.

    Science.gov (United States)

    Roskoski, Robert

    2005-11-11

    Signaling by stem cell factor and Kit, its receptor, plays important roles in gametogenesis, hematopoiesis, mast cell development and function, and melanogenesis. Moreover, human and mouse embryonic stem cells express Kit transcripts. Stem cell factor exists as both a soluble and a membrane-bound glycoprotein while Kit is a receptor protein-tyrosine kinase. The complete absence of stem cell factor or Kit is lethal. Deficiencies of either produce defects in red and white blood cell production, hypopigmentation, and sterility. Gain-of-function mutations of Kit are associated with several human neoplasms including acute myelogenous leukemia, gastrointestinal stromal tumors, and mastocytomas. Kit consists of an extracellular domain, a transmembrane segment, a juxtamembrane segment, and a protein kinase domain that contains an insert of about 80 amino acid residues. Binding of stem cell factor to Kit results in receptor dimerization and activation of protein kinase activity. The activated receptor becomes autophosphorylated at tyrosine residues that serve as docking sites for signal transduction molecules containing SH2 domains. The adaptor protein APS, Src family kinases, and Shp2 tyrosyl phosphatase bind to phosphotyrosine 568. Shp1 tyrosyl phosphatase and the adaptor protein Shc bind to phosphotyrosine 570. C-terminal Src kinase homologous kinase and the adaptor Shc bind to both phosphotyrosines 568 and 570. These residues occur in the juxtamembrane segment of Kit. Three residues in the kinase insert domain are phosphorylated and attract the adaptor protein Grb2 (Tyr703), phosphatidylinositol 3-kinase (Tyr721), and phospholipase Cgamma (Tyr730). Phosphotyrosine 900 in the distal kinase domain binds phosphatidylinositol 3-kinase which in turn binds the adaptor protein Crk. Phosphotyrosine 936, also in the distal kinase domain, binds the adaptor proteins APS, Grb2, and Grb7. Kit has the potential to participate in multiple signal transduction pathways as a result of

  3. Proteomic analysis of the signaling pathway mediated by the heterotrimeric Gα protein Pga1 of Penicillium chrysogenum.

    Science.gov (United States)

    Carrasco-Navarro, Ulises; Vera-Estrella, Rosario; Barkla, Bronwyn J; Zúñiga-León, Eduardo; Reyes-Vivas, Horacio; Fernández, Francisco J; Fierro, Francisco

    2016-10-06

    The heterotrimeric Gα protein Pga1-mediated signaling pathway regulates the entire developmental program in Penicillium chrysogenum, from spore germination to the formation of conidia. In addition it participates in the regulation of penicillin biosynthesis. We aimed to advance the understanding of this key signaling pathway using a proteomics approach, a powerful tool to identify effectors participating in signal transduction pathways. Penicillium chrysogenum mutants with different levels of activity of the Pga1-mediated signaling pathway were used to perform comparative proteomic analyses by 2D-DIGE and LC-MS/MS. Thirty proteins were identified which showed differences in abundance dependent on Pga1 activity level. By modifying the intracellular levels of cAMP we could establish cAMP-dependent and cAMP-independent pathways in Pga1-mediated signaling. Pga1 was shown to regulate abundance of enzymes in primary metabolic pathways involved in ATP, NADPH and cysteine biosynthesis, compounds that are needed for high levels of penicillin production. An in vivo phosphorylated protein containing a pleckstrin homology domain was identified; this protein is a candidate for signal transduction activity. Proteins with possible roles in purine metabolism, protein folding, stress response and morphogenesis were also identified whose abundance was regulated by Pga1 signaling. Thirty proteins whose abundance was regulated by the Pga1-mediated signaling pathway were identified. These proteins are involved in primary metabolism, stress response, development and signal transduction. A model describing the pathways through which Pga1 signaling regulates different cellular processes is proposed.

  4. Spatial modeling of the membrane-cytosolic interface in protein kinase signal transduction.

    Directory of Open Access Journals (Sweden)

    Wolfgang Giese

    2018-04-01

    Full Text Available The spatial architecture of signaling pathways and the interaction with cell size and morphology are complex, but little understood. With the advances of single cell imaging and single cell biology, it becomes crucial to understand intracellular processes in time and space. Activation of cell surface receptors often triggers a signaling cascade including the activation of membrane-attached and cytosolic signaling components, which eventually transmit the signal to the cell nucleus. Signaling proteins can form steep gradients in the cytosol, which cause strong cell size dependence. We show that the kinetics at the membrane-cytosolic interface and the ratio of cell membrane area to the enclosed cytosolic volume change the behavior of signaling cascades significantly. We suggest an estimate of average concentration for arbitrary cell shapes depending on the cell volume and cell surface area. The normalized variance, known from image analysis, is suggested as an alternative measure to quantify the deviation from the average concentration. A mathematical analysis of signal transduction in time and space is presented, providing analytical solutions for different spatial arrangements of linear signaling cascades. Quantification of signaling time scales reveals that signal propagation is faster at the membrane than at the nucleus, while this time difference decreases with the number of signaling components in the cytosol. Our investigations are complemented by numerical simulations of non-linear cascades with feedback and asymmetric cell shapes. We conclude that intracellular signal propagation is highly dependent on cell geometry and, thereby, conveys information on cell size and shape to the nucleus.

  5. Nuclear localization signal regulates porcine circovirus type 2 capsid protein nuclear export through phosphorylation.

    Science.gov (United States)

    Hou, Qiang; Hou, Shaohua; Chen, Qing; Jia, Hong; Xin, Ting; Jiang, Yitong; Guo, Xiaoyu; Zhu, Hongfei

    2018-02-15

    The open reading frame 2 (ORF2) of Porcine circovirus type 2 (PCV2) encodes the major Capsid (Cap) protein, which self-assembles into virus-like particle (VLP) of similar morphology to the PCV2 virion and accumulates in the nucleus through the N-terminal arginine-rich nuclear localization signal (NLS). In this study, PCV2 Cap protein and its derivates were expressed via the baculovirus expression system, and the cellular localization of the recombinant proteins were investigated using anti-Cap mAb by imaging flow cytometry. Analysis of subcellular localization of Cap protein and its variants demonstrated that NLS mediated Cap protein nuclear export as well as nuclear import, and a phosphorylation site (S17) was identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the NLS domain to regulate Cap protein nuclear export. Phosphorylation of NLS regulating the PCV2 Cap protein nuclear export was also demonstrated in PK15 cells by fluorescence microscopy. Moreover, the influence of Rep and Rep' protein on Cap protein subcellular localization was investigated in PK15 cells. Phosphorylation of NLS regulating Cap protein nuclear export provides more detailed knowledge of the PCV2 viral life cycle. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Cooperation of an RNA Packaging Signal and a Viral Envelope Protein in Coronavirus RNA Packaging

    OpenAIRE

    Narayanan, Krishna; Makino, Shinji

    2001-01-01

    Murine coronavirus mouse hepatitis virus (MHV) produces a genome-length mRNA, mRNA 1, and six or seven species of subgenomic mRNAs in infected cells. Among these mRNAs, only mRNA 1 is efficiently packaged into MHV particles. MHV N protein binds to all MHV mRNAs, whereas envelope M protein interacts only with mRNA 1. This M protein-mRNA 1 interaction most probably determines the selective packaging of mRNA 1 into MHV particles. A short cis-acting MHV RNA packaging signal is necessary and suffi...

  7. Accessory factors of cytoplasmic viral RNA sensors required for antiviral innate immune response

    Directory of Open Access Journals (Sweden)

    Hiroyuki eOshiumi

    2016-05-01

    Full Text Available Type I interferon (IFN induces many antiviral factors in host cells. RIG-I-like receptors (RLRs are cytoplasmic viral RNA sensors that trigger the signal to induce the innate immune response that includes type I IFN production. RIG-I and MDA5 are RLRs that form nucleoprotein filaments along viral double-stranded RNA, resulting in the activation of MAVS adaptor molecule. The MAVS protein forms a prion-like aggregation structure, leading to type I IFN production. RIG-I and MDA5 undergo post-translational modification. TRIM25 and Riplet ubiquitin ligases deliver a K63-linked polyubiquitin moiety to the RIG-I N-terminal caspase activation and recruitment domains (CARDs and C-terminal region; the polyubiquitin chain then stabilizes the two-CARD tetramer structure required for MAVS assembly. MDA5 activation is regulated by phosphorylation. RIOK3 is a protein kinase that phosphorylates the MDA5 protein in a steady state, and PP1α/γ dephosphorylate this protein, resulting in its activation. RIG-I and MDA5 require cytoplasmic RNA helicases for their efficient activation. LGP2, another RLR, is an RNA helicase involved in RLR signaling. This protein does not possess N-terminal CARDs and thus cannot trigger downstream signaling by itself. Recent studies have revealed that this protein modulates MDA5 filament formation, resulting in enhanced type I IFN production. Several other cytoplasmic RNA helicases are involved in RLR signaling. DDX3, DHX29, DHX36, and DDX60 RNA helicases have been reported to be involved in RLR-mediated type I IFN production after viral infection. However, the underlying mechanism is largely unknown. Future studies are required to reveal the role of RNA helicases in the RLR signaling pathway.

  8. Association of atypical protein kinase C isotypes with the docker protein FRS2 in fibroblast growth factor signaling.

    Science.gov (United States)

    Lim, Y P; Low, B C; Lim, J; Wong, E S; Guy, G R

    1999-07-02

    FRS2 is a docker protein that recruits signaling proteins to the plasma membrane in fibroblast growth factor signal transduction. We report here that FRS2 was associated with PKC lambda when Swiss 3T3 cells were stimulated with basic fibroblast growth factor. PKC zeta, the other member of the atypical PKC subfamily, could also bind FRS2. The association between FRS2 and PKC lambda is likely to be direct as shown by yeast two-hybrid analysis. The C-terminal fragments of FRS2 (amino acid residues 300-508) and SNT2 (amino acids 281-492), an isoform bearing 50% identity to FRS2, interacted with PKC lambda at a region (amino acids 240-562) that encompasses the catalytic domain. In vitro kinase assays revealed neither FRS2 nor SNT2 was a substrate of PKC lambda or zeta. Mutation of the alanine residue (Ala-120) to glutamate in the pseudo-substrate region of PKC lambda results in a constitutively active kinase that exhibited more than 2-fold greater binding to FRS2 in vitro than its "closed" wild-type counterpart. Tyrosine phosphorylation of FRS2 did not affect its binding to the constitutively active PKC lambda mutant, suggesting that the activation of PKC lambda is necessary and sufficient for its association with FRS2. It is likely that FRS2 serves as an anchoring protein for targeting activated atypical PKCs to the cell plasma membrane in signaling pathways.

  9. VEGFR-3 signaling is regulated by a G-protein activator, activator of G-protein signaling 8, in lymphatic endothelial cells.

    Science.gov (United States)

    Sakima, Miho; Hayashi, Hisaki; Mamun, Abdullah Al; Sato, Motohiko

    2018-07-01

    Vascular endothelial growth factor C (VEGFC) and its cognate receptor VEGFR-3 play a key role in lymphangiogenesis. We previously reported that an ischemia-inducible Gβγ signal regulator, activator of G-protein signaling 8 (AGS8), regulated the subcellular distribution of vascular endothelial growth factor receptor-2 (VEGFR-2) and influenced VEGFA-induced signaling in vascular endothelial cells. Here, we report that AGS8 regulates VEGFR-3, which is another subtype of the VEGF receptor family, and mediates VEGFC signaling in human dermal lymphatic endothelial cells (HDLECs). VEGFC stimulated the proliferation of HDLECs and tube formation by HDLECs, which were inhibited by knocking down AGS8 by small interfering RNA (siRNA). AGS8 siRNA inhibited VEGFC-mediated phosphorylation of VEGFR-3 and its downstream molecules, including ERK1/2 and AKT. Analysis of fluorescence-activated cell sorting and immunofluorescence staining demonstrated that AGS8 knockdown was associated with a reduction of VEGFR-3 at the cell surface. Endocytosis inhibitors did not rescue the decrease of cell-surface VEGFR-3, suggesting that AGS8 regulated the trafficking of VEGFR-3 to the plasma membrane. An immunoprecipitation assay indicated that VEGFR-3 formed a complex including AGS8 and Gβγ in cells. These data suggest the novel regulation of VEGFC-VEGFR-3 by AGS8 in HDLECs and a potential role for AGS8 in lymphangiogenesis. Copyright © 2018 Elsevier Inc. All rights reserved.

  10. Vacuole Integrity Maintained by DUF300 Proteins Is Required for Brassinosteroid Signaling Regulation

    Czech Academy of Sciences Publication Activity Database

    Liu, Q.; Vain, T.; Viotti, C.; Doyle, S. M.; Tarkowská, Danuše; Novák, Ondřej; Zipfel, C.; Sitbon, F.; Robert, S.; Hofius, D.

    2018-01-01

    Roč. 11, č. 4 (2018), s. 553-567 ISSN 1674-2052 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Arabidopsis * brassinosteroid signaling * DUF300 proteins * tonoplast * vacuole integrity Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Plant sciences, botany Impact factor: 8.827, year: 2016

  11. Spatiotemporal aspects of G protein signaling : Where GPCRs and Rho GTPases meet

    NARCIS (Netherlands)

    van Unen, J.

    2017-01-01

    The experimental work conducted for this thesis is aimed towards a better understanding of the fundamental aspects of G protein signaling at the plasma membrane and beyond. The use of advanced microscopy techniques in living cells allows the collection of quantitative information on reaction

  12. Ca2+-calmodulin-dependent protein kinase expression and signalling in skeletal muscle during exercise

    DEFF Research Database (Denmark)

    Rose, Adam John; Kiens, Bente; Richter, Erik

    2006-01-01

    Ca2+ signalling is proposed to play an important role in skeletal muscle function during exercise. Here, we examined the expression of multifunctional Ca2+-calmodulin-dependent protein kinases (CaMK) in human skeletal muscle and show that CaMKII and CaMKK, but not CaMKI or CaMKIV, are expressed...

  13. Spatial Organization in Protein Kinase A Signaling Emerged at the Base of Animal Evolution

    NARCIS (Netherlands)

    Peng, Mao; Aye, Thin Thin; Snel, Berend; Van Breukelen, Bas; Scholten, Arjen; Heck, Albert J R

    2015-01-01

    In phosphorylation-directed signaling, spatial and temporal control is organized by complex interaction networks that diligently direct kinases toward distinct substrates to fine-tune specificity. How these protein networks originate and evolve into complex regulatory machineries are among the most

  14. Ciliopathy proteins regulate paracrine signaling by modulating proteasomal degradation of mediators

    Science.gov (United States)

    Liu, Yangfan P.; Tsai, I-Chun; Morleo, Manuela; Oh, Edwin C.; Leitch, Carmen C.; Massa, Filomena; Lee, Byung-Hoon; Parker, David S.; Finley, Daniel; Zaghloul, Norann A.; Franco, Brunella; Katsanis, Nicholas

    2014-01-01

    Cilia are critical mediators of paracrine signaling; however, it is unknown whether proteins that contribute to ciliopathies converge on multiple paracrine pathways through a common mechanism. Here, we show that loss of cilopathy-associated proteins Bardet-Biedl syndrome 4 (BBS4) or oral-facial-digital syndrome 1 (OFD1) results in the accumulation of signaling mediators normally targeted for proteasomal degradation. In WT cells, several BBS proteins and OFD1 interacted with proteasomal subunits, and loss of either BBS4 or OFD1 led to depletion of multiple subunits from the centrosomal proteasome. Furthermore, overexpression of proteasomal regulatory components or treatment with proteasomal activators sulforaphane (SFN) and mevalonolactone (MVA) ameliorated signaling defects in cells lacking BBS1, BBS4, and OFD1, in morphant zebrafish embryos, and in induced neurons from Ofd1-deficient mice. Finally, we tested the hypothesis that other proteasome-dependent pathways not known to be associated with ciliopathies are defective in the absence of ciliopathy proteins. We found that loss of BBS1, BBS4, or OFD1 led to decreased NF-κB activity and concomitant IκBβ accumulation and that these defects were ameliorated with SFN treatment. Taken together, our data indicate that basal body proteasomal regulation governs paracrine signaling pathways and suggest that augmenting proteasomal function might benefit ciliopathy patients. PMID:24691443

  15. Locating proteins in the cell using TargetP, SignalP and related tools

    DEFF Research Database (Denmark)

    Emanuelsson, O.; Brunak, Søren; von Heijne, G.

    2007-01-01

    of methods to predict subcellular localization based on these sorting signals and other sequence properties. We then outline how to use a number of internet-accessible tools to arrive at a reliable subcellular localization prediction for eukaryotic and prokaryotic proteins. In particular, we provide detailed...

  16. Interactions of Ras proteins with the plasma membrane and their roles in signaling.

    Science.gov (United States)

    Eisenberg, Sharon; Henis, Yoav I

    2008-01-01

    The complex dynamic structure of the plasma membrane plays critical roles in cellular signaling; interactions with the membrane lipid milieu, spatial segregation within and between cellular membranes and/or targeting to specific membrane-associated scaffolds are intimately involved in many signal transduction pathways. In this review, we focus on the membrane interactions of Ras proteins. These small GTPases play central roles in the regulation of cell growth and proliferation, and their excessive activation is commonly encountered in human tumors. Ras proteins associate with the membrane continuously via C-terminal lipidation and additional interactions in both their inactive and active forms; this association, as well as the targeting of specific Ras isoforms to plasma membrane microdomains and to intracellular organelles, have recently been implicated in Ras signaling and oncogenic potential. We discuss biochemical and biophysical evidence for the roles of specific domains of Ras proteins in mediating their association with the plasma membrane, and consider the potential effects of lateral segregation and interactions with membrane-associated protein assemblies on the signaling outcomes.

  17. Mechanism of protein tyrosine phosphatase 1B-mediated inhibition of leptin signalling

    DEFF Research Database (Denmark)

    Lund, I K; Hansen, J A; Andersen, H S

    2005-01-01

    Upon leptin binding, the leptin receptor is activated, leading to stimulation of the JAK/STAT signal transduction cascade. The transient character of the tyrosine phosphorylation of JAK2 and STAT3 suggests the involvement of protein tyrosine phosphatases (PTPs) as negative regulators...

  18. Intercellular signaling through secreted proteins induces free-energy gradient-directed cell movement.

    Science.gov (United States)

    Kravchenko-Balasha, Nataly; Shin, Young Shik; Sutherland, Alex; Levine, R D; Heath, James R

    2016-05-17

    Controlling cell migration is important in tissue engineering and medicine. Cell motility depends on factors such as nutrient concentration gradients and soluble factor signaling. In particular, cell-cell signaling can depend on cell-cell separation distance and can influence cellular arrangements in bulk cultures. Here, we seek a physical-based approach, which identifies a potential governed by cell-cell signaling that induces a directed cell-cell motion. A single-cell barcode chip (SCBC) was used to experimentally interrogate secreted proteins in hundreds of isolated glioblastoma brain cancer cell pairs and to monitor their relative motions over time. We used these trajectories to identify a range of cell-cell separation distances where the signaling was most stable. We then used a thermodynamics-motivated analysis of secreted protein levels to characterize free-energy changes for different cell-cell distances. We show that glioblastoma cell-cell movement can be described as Brownian motion biased by cell-cell potential. To demonstrate that the free-energy potential as determined by the signaling is the driver of motion, we inhibited two proteins most involved in maintaining the free-energy gradient. Following inhibition, cell pairs showed an essentially random Brownian motion, similar to the case for untreated, isolated single cells.

  19. The interferon-induced antiviral protein PML (TRIM19) promotes the restriction and transcriptional silencing of lentiviruses in a context-specific, isoform-specific fashion.

    Science.gov (United States)

    Masroori, Nasser; Merindol, Natacha; Berthoux, Lionel

    2016-03-22

    The promyelocytic leukemia (PML) protein, a type I interferon (IFN-I)-induced gene product and a member of the tripartite motif (TRIM) family, modulates the transcriptional activity of viruses belonging to various families. Whether PML has an impact on the replication of HIV-1 has not been fully addressed, but recent studies point to its possible involvement in the restriction of HIV-1 in human cells and in the maintenance of transcriptional latency in human cell lines in which HIV-1 is constitutively repressed. We investigated further the restriction of HIV-1 and a related lentivirus, SIVmac, by PML in murine cells and in a lymphocytic human cell line. In particular, we studied the relevance of PML to IFN-I-mediated inhibition and the role of individual human isoforms. We demonstrate that both human PML (hPML) and murine PML (mPML) inhibit the early post-entry stages of the replication of HIV-1 and a related lentivirus, SIVmac. In addition, HIV-1 was transcriptionally silenced by mPML and by hPML isoforms I, II, IV and VI in MEFs. This PML-mediated transcriptional repression was attenuated in presence of the histone deacetylase inhibitor SAHA. In contrast, depletion of PML had no effect on HIV-1 gene expression in a human T cell line. PML was found to contribute to the inhibition of HIV-1 by IFN-I. Specifically, IFN-α and IFN-β treatments of MEFs enhanced the PML-dependent inhibition of HIV-1 early replication stages. We show that PML can inhibit HIV-1 and other lentiviruses as part of the IFN-I-mediated response. The restriction takes place at two distinct steps, i.e. reverse transcription and transcription, and in an isoform-specific, cellular context-specific fashion. Our results support a model in which PML activates innate immune antilentiviral effectors. These data are relevant to the development of latency reversal-inducing pharmacological agents, since PML was previously proposed as a pharmacological target for such inhibitors. This study also has

  20. The future of antiviral immunotoxins

    DEFF Research Database (Denmark)

    Spiess, K.; Høy Jakobsen, Mette; Kledal, Thomas N

    2016-01-01

    There is a constant need for new therapeutic interventions in a wide range of infectious diseases. Over the past few years, the immunotoxins have entered the stage as promising antiviral treatments. Immunotoxins have been extensively explored in cancer treatment and have achieved FDA approval in ...

  1. Practical aspects of NMR signal assignment in larger and challenging proteins

    Science.gov (United States)

    Frueh, Dominique P.

    2014-01-01

    NMR has matured into a technique routinely employed for studying proteins in near physiological conditions. However, applications to larger proteins are impeded by the complexity of the various correlation maps necessary to assign NMR signals. This article reviews the data analysis techniques traditionally employed for resonance assignment and describes alternative protocols necessary for overcoming challenges in large protein spectra. In particular, simultaneous analysis of multiple spectra may help overcome ambiguities or may reveal correlations in an indirect manner. Similarly, visualization of orthogonal planes in a multidimensional spectrum can provide alternative assignment procedures. We describe examples of such strategies for assignment of backbone, methyl, and nOe resonances. We describe experimental aspects of data acquisition for the related experiments and provide guidelines for preliminary studies. Focus is placed on large folded monomeric proteins and examples are provided for 37, 48, 53, and 81 kDa proteins. PMID:24534088

  2. A mechanism for vertebrate Hedgehog signaling: recruitment to cilia and dissociation of SuFu–Gli protein complexes

    OpenAIRE

    Tukachinsky, Hanna; Lopez, Lyle V.; Salic, Adrian

    2010-01-01

    In vertebrates, Hedgehog (Hh) signaling initiated in primary cilia activates the membrane protein Smoothened (Smo) and leads to activation of Gli proteins, the transcriptional effectors of the pathway. In the absence of signaling, Gli proteins are inhibited by the cytoplasmic protein Suppressor of Fused (SuFu). It is unclear how Hh activates Gli and whether it directly regulates SuFu. We find that Hh stimulation quickly recruits endogenous SuFu–Gli complexes to cilia, suggesting a model in wh...

  3. SH2 Domains Serve as Lipid-Binding Modules for pTyr-Signaling Proteins.

    Science.gov (United States)

    Park, Mi-Jeong; Sheng, Ren; Silkov, Antonina; Jung, Da-Jung; Wang, Zhi-Gang; Xin, Yao; Kim, Hyunjin; Thiagarajan-Rosenkranz, Pallavi; Song, Seohyeon; Yoon, Youngdae; Nam, Wonhee; Kim, Ilshin; Kim, Eui; Lee, Dong-Gyu; Chen, Yong; Singaram, Indira; Wang, Li; Jang, Myoung Ho; Hwang, Cheol-Sang; Honig, Barry; Ryu, Sungho; Lorieau, Justin; Kim, You-Me; Cho, Wonhwa

    2016-04-07

    The Src-homology 2 (SH2) domain is a protein interaction domain that directs myriad phosphotyrosine (pY)-signaling pathways. Genome-wide screening of human SH2 domains reveals that ∼90% of SH2 domains bind plasma membrane lipids and many have high phosphoinositide specificity. They bind lipids using surface cationic patches separate from pY-binding pockets, thus binding lipids and the pY motif independently. The patches form grooves for specific lipid headgroup recognition or flat surfaces for non-specific membrane binding and both types of interaction are important for cellular function and regulation of SH2 domain-containing proteins. Cellular studies with ZAP70 showed that multiple lipids bind its C-terminal SH2 domain in a spatiotemporally specific manner and thereby exert exquisite spatiotemporal control over its protein binding and signaling activities in T cells. Collectively, this study reveals how lipids control SH2 domain-mediated cellular protein-protein interaction networks and suggest a new strategy for therapeutic modulation of pY-signaling pathways. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. 4EBP-Dependent Signaling Supports West Nile Virus Growth and Protein Expression

    Directory of Open Access Journals (Sweden)

    Katherine D. Shives

    2016-10-01

    Full Text Available West Nile virus (WNV is a (+ sense, single-stranded RNA virus in the Flavivirus genus. WNV RNA possesses an m7GpppNm 5′ cap with 2′-O-methylation that mimics host mRNAs preventing innate immune detection and allowing the virus to translate its RNA genome through the utilization of cap-dependent translation initiation effectors in a wide variety of host species. Our prior work established the requirement of the host mammalian target of rapamycin complex 1 (mTORC1 for optimal WNV growth and protein expression; yet, the roles of the downstream effectors of mTORC1 in WNV translation are unknown. In this study, we utilize gene deletion mutants in the ribosomal protein kinase called S6 kinase (S6K and eukaryotic translation initiation factor 4E-binding protein (4EBP pathways downstream of mTORC1 to define the role of mTOR-dependent translation initiation signals in WNV gene expression and growth. We now show that WNV growth and protein expression are dependent on mTORC1 mediated-regulation of the eukaryotic translation initiation factor 4E-binding protein/eukaryotic translation initiation factor 4E-binding protein (4EBP/eIF4E interaction and eukaryotic initiation factor 4F (eIF4F complex formation to support viral growth and viral protein expression. We also show that the canonical signals of mTORC1 activation including ribosomal protein s6 (rpS6 and S6K phosphorylation are not required for WNV growth in these same conditions. Our data suggest that the mTORC1/4EBP/eIF4E signaling axis is activated to support the translation of the WNV genome.

  5. 4EBP-Dependent Signaling Supports West Nile Virus Growth and Protein Expression.

    Science.gov (United States)

    Shives, Katherine D; Massey, Aaron R; May, Nicholas A; Morrison, Thomas E; Beckham, J David

    2016-10-18

    West Nile virus (WNV) is a (+) sense, single-stranded RNA virus in the Flavivirus genus. WNV RNA possesses an m7 GpppN m 5' cap with 2'- O -methylation that mimics host mRNAs preventing innate immune detection and allowing the virus to translate its RNA genome through the utilization of cap-dependent translation initiation effectors in a wide variety of host species. Our prior work established the requirement of the host mammalian target of rapamycin complex 1 (mTORC1) for optimal WNV growth and protein expression; yet, the roles of the downstream effectors of mTORC1 in WNV translation are unknown. In this study, we utilize gene deletion mutants in the ribosomal protein kinase called S6 kinase (S6K) and eukaryotic translation initiation factor 4E-binding protein (4EBP) pathways downstream of mTORC1 to define the role of mTOR-dependent translation initiation signals in WNV gene expression and growth. We now show that WNV growth and protein expression are dependent on mTORC1 mediated-regulation of the eukaryotic translation initiation factor 4E-binding protein/eukaryotic translation initiation factor 4E-binding protein (4EBP/eIF4E) interaction and eukaryotic initiation factor 4F (eIF4F) complex formation to support viral growth and viral protein expression. We also show that the canonical signals of mTORC1 activation including ribosomal protein s6 (rpS6) and S6K phosphorylation are not required for WNV growth in these same conditions. Our data suggest that the mTORC1/4EBP/eIF4E signaling axis is activated to support the translation of the WNV genome.

  6. A two-step recognition of signal sequences determines the translocation efficiency of proteins.

    Science.gov (United States)

    Belin, D; Bost, S; Vassalli, J D; Strub, K

    1996-02-01

    The cytosolic and secreted, N-glycosylated, forms of plasminogen activator inhibitor-2 (PAI-2) are generated by facultative translocation. To study the molecular events that result in the bi-topological distribution of proteins, we determined in vitro the capacities of several signal sequences to bind the signal recognition particle (SRP) during targeting, and to promote vectorial transport of murine PAI-2 (mPAI-2). Interestingly, the six signal sequences we compared (mPAI-2 and three mutated derivatives thereof, ovalbumin and preprolactin) were found to have the differential activities in the two events. For example, the mPAI-2 signal sequence first binds SRP with moderate efficiency and secondly promotes the vectorial transport of only a fraction of the SRP-bound nascent chains. Our results provide evidence that the translocation efficiency of proteins can be controlled by the recognition of their signal sequences at two steps: during SRP-mediated targeting and during formation of a committed translocation complex. This second recognition may occur at several time points during the insertion/translocation step. In conclusion, signal sequences have a more complex structure than previously anticipated, allowing for multiple and independent interactions with the translocation machinery.

  7. Increased signaling entropy in cancer requires the scale-free property of protein interaction networks

    Science.gov (United States)

    Teschendorff, Andrew E.; Banerji, Christopher R. S.; Severini, Simone; Kuehn, Reimer; Sollich, Peter

    2015-01-01

    One of the key characteristics of cancer cells is an increased phenotypic plasticity, driven by underlying genetic and epigenetic perturbations. However, at a systems-level it is unclear how these perturbations give rise to the observed increased plasticity. Elucidating such systems-level principles is key for an improved understanding of cancer. Recently, it has been shown that signaling entropy, an overall measure of signaling pathway promiscuity, and computable from integrating a sample's gene expression profile with a protein interaction network, correlates with phenotypic plasticity and is increased in cancer compared to normal tissue. Here we develop a computational framework for studying the effects of network perturbations on signaling entropy. We demonstrate that the increased signaling entropy of cancer is driven by two factors: (i) the scale-free (or near scale-free) topology of the interaction network, and (ii) a subtle positive correlation between differential gene expression and node connectivity. Indeed, we show that if protein interaction networks were random graphs, described by Poisson degree distributions, that cancer would generally not exhibit an increased signaling entropy. In summary, this work exposes a deep connection between cancer, signaling entropy and interaction network topology. PMID:25919796

  8. Uncovering molecular structural mechanisms of signaling mediated by the prion protein

    International Nuclear Information System (INIS)

    Romano, Sebastian A.; Linden, Rafael; Silva, Jerson L.; Foguel, Debora

    2009-01-01

    The glycosyl phosphatidylinositol (GPI) - anchored prion protein (PrP c ), usually associated with neurodegenerative diseases, modulates various cellular responses and may scaffold multiprotein cell surface signaling complexes. Engagement of PrP c with the secretable cochaperone hop/STI 1 induces neurotrophic transmembrane signals through unknown molecular mechanisms. We addressed whether interaction of Pr P c and hop STI 1 entails structural rearrangements relevant for signaling. Circular dichroism and fluorescence spectroscopy showed that PrP c :hop/STI 1 interaction triggers loss of PrP helical structures, involving at least a perturbation of the Pr P c 143-153 beta-helix. Novel SAXS models revealed a significant C-terminal compaction of hop/STI 1 when bound to PrP c . Differing from a recent dimeric model of human hop/STI 1, both size exclusion chromatography and SAXS data support a monomeric form of free murine hop/STI 1. Changes in the Pr P c 143-153 beta-helix may engage the transmembrane signaling protein laminin receptor precursor and neural cell adhesion molecule, both of which bind that domain of Pr P c , and further ligands may be engaged by the tertiary structural changes of hop/STI 1. These reciprocal structural modifications indicate a versatile mechanism for signaling mediated by Pr P c :hop/STI 1 interaction, consistent with the hypothesis that Pr P c scaffolds multiprotein signaling complexes at the cell surface. (author)

  9. Imaging of persistent cAMP signaling by internalized G protein-coupled receptors.

    Science.gov (United States)

    Calebiro, Davide; Nikolaev, Viacheslav O; Lohse, Martin J

    2010-07-01

    G protein-coupled receptors (GPCRs) are the largest family of plasma membrane receptors. They mediate the effects of several endogenous cues and serve as important pharmacological targets. Although many biochemical events involved in GPCR signaling have been characterized in great detail, little is known about their spatiotemporal dynamics in living cells. The recent advent of optical methods based on fluorescent resonance energy transfer allows, for the first time, to directly monitor GPCR signaling in living cells. Utilizing these methods, it has been recently possible to show that the receptors for two protein/peptide hormones, the TSH and the parathyroid hormone, continue signaling to cAMP after their internalization into endosomes. This type of intracellular signaling is persistent and apparently triggers specific cellular outcomes. Here, we review these recent data and explain the optical methods used for such studies. Based on these findings, we propose a revision of the current model of the GPCR-cAMP signaling pathway to accommodate receptor signaling at endosomes.

  10. Fringe proteins modulate Notch-ligand cis and trans interactions to specify signaling states.

    Science.gov (United States)

    LeBon, Lauren; Lee, Tom V; Sprinzak, David; Jafar-Nejad, Hamed; Elowitz, Michael B

    2014-09-25

    The Notch signaling pathway consists of multiple types of receptors and ligands, whose interactions can be tuned by Fringe glycosyltransferases. A major challenge is to determine how these components control the specificity and directionality of Notch signaling in developmental contexts. Here, we analyzed same-cell (cis) Notch-ligand interactions for Notch1, Dll1, and Jag1, and their dependence on Fringe protein expression in mammalian cells. We found that Dll1 and Jag1 can cis-inhibit Notch1, and Fringe proteins modulate these interactions in a way that parallels their effects on trans interactions. Fringe similarly modulated Notch-ligand cis interactions during Drosophila development. Based on these and previously identified interactions, we show how the design of the Notch signaling pathway leads to a restricted repertoire of signaling states that promote heterotypic signaling between distinct cell types, providing insight into the design principles of the Notch signaling system, and the specific developmental process of Drosophila dorsal-ventral boundary formation.

  11. A study on CT attenuation and MR signal intensity of protein solution

    International Nuclear Information System (INIS)

    Kim, Joung Hae; Choi, Dae Seob; Kim, Soon; Lee, Hyeon Kyeong; Oh, Hyeon Hee; Kim, Seung Hyeon; Lee, Sung Woo; Chang, Kee Hyun; Chung, Jun Ho

    2001-01-01

    To correlate CT attenuation and MR signal intensity with concentration of protein solution. CT and MR examinations of a phantom containing bovine serum albumin solutions of various concentrations ranging from 0 to 55% were performed. CT Hounsfield units(HUs), MR signal intensities, and apparent diffusion coefficients (ADCs) of each albumin solution were measured, and CT HUs and MR signal intensities of the solutions were compared with those of cerebrospinal fluid (CSF), white matter, and cortical gray matter. CT HU increased gradually with increasing albumin concentration. On T1-weighted images(T1WI), signal intensity increased with increasing albumin concentrations of up to 35% but then decreased. On T2-weighted images(T2Wl), gradually decreasing signal intensity and increasing albumin concentration were observed Fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted images (DWls) showed that signal intensity peaked at a concentration of 10% and then gradually decreased. The ADC of the solution gradually decreased as concentration increased. Compared with those of normal brain structures, the CT HUs of solutions at concentrations of over 20% were higher than those of white and gray matter. At T1WI, the signal intensities of 10-45% solutions were similar to or higher than that of the gray matter. At T2Wl, the signal intensities of solutions above 25, 35, and 40% were lower than those of CSF, gray matter, and white matter, respectively. FLAIR images showed that the signal intensities of 5-35% solutions were higher than that of gray matter. The CT attenuation of albumin solution increased gradually with increasing concentration. MR signal intensities peaked at 35% concentration on T1WI and at 10% on FLAIR and DW images, respectively, and then gradually decreased. T2Wl and ADC map images showed gradually decreasing signal intensity and ADC as albumin concentration increased

  12. Hepatitis C Virus Core Protein Modulates Endoglin (CD105) Signaling Pathway for Liver Pathogenesis.

    Science.gov (United States)

    Kwon, Young-Chan; Sasaki, Reina; Meyer, Keith; Ray, Ranjit

    2017-11-01

    Endoglin is part of the TGF-β receptor complex and has a crucial role in fibrogenesis and angiogenesis. It is also an important protein for tumor growth, survival, and cancer cell metastasis. In a previous study, we have shown that hepatitis C virus (HCV) infection induces epithelial-mesenchymal transition (EMT) state and cancer stem-like cell (CSC) properties in human hepatocytes. Our array data suggested that endoglin (CD105) mRNA is significantly upregulated in HCV-associated CSCs. In this study, we have observed increased endoglin expression on the cell surface of an HCV core-expressing hepatocellular carcinoma (HepG2) cell line or immortalized human hepatocytes (IHH) and activation of its downstream signaling molecules. The status of phospho-SMAD1/5 and the expression of inhibitor of DNA binding protein 1 (ID1) were upregulated in HCV-infected cells or viral core gene-transfected cells. Additionally, we observed upregulation of endoglin/ID1 mRNA expression in chronic HCV patient liver biopsy samples. CSC generation by HCV core protein was dependent on the endoglin signaling pathway using activin receptor-like kinase 1 (ALK1) Fc blocking peptide and endoglin small interfering RNA (siRNA). Further, follow-up from in vitro analysis suggested that the antiapoptosis Bcl2 protein, proliferation-related cyclin D1 protein, and CSC-associated Hes1, Notch1, Nanog, and Sox2 proteins are enhanced during infection or ectopic expression of HCV core protein. IMPORTANCE Endoglin plays a crucial role in fibrogenesis and angiogenesis and is an important protein for tumor growth, survival, and cancer cell metastasis. Endoglin enhances ALK1-SMAD1/5 signaling in different cell types, leading to increased proliferation and migration responses. We have observed endoglin expression on the HCV core-expressing cell surface of human hepatocyte origin and activation of phospho-SMAD1/5 and ID1 downstream signaling molecules. ID1 protein plays a role in CSC properties, and we found that

  13. 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.

  14. Determinants of cell-to-cell variability in protein kinase signaling.

    Science.gov (United States)

    Jeschke, Matthias; Baumgärtner, Stephan; Legewie, Stefan

    2013-01-01

    Cells reliably sense environmental changes despite internal and external fluctuations, but the mechanisms underlying robustness remain unclear. We analyzed how fluctuations in signaling protein concentrations give rise to cell-to-cell variability in protein kinase signaling using analytical theory and numerical simulations. We characterized the dose-response behavior of signaling cascades by calculating the stimulus level at which a pathway responds ('pathway sensitivity') and the maximal activation level upon strong stimulation. Minimal kinase cascades with gradual dose-response behavior show strong variability, because the pathway sensitivity and the maximal activation level cannot be simultaneously invariant. Negative feedback regulation resolves this trade-off and coordinately reduces fluctuations in the pathway sensitivity and maximal activation. Feedbacks acting at different levels in the cascade control different aspects of the dose-response curve, thereby synergistically reducing the variability. We also investigated more complex, ultrasensitive signaling cascades capable of switch-like decision making, and found that these can be inherently robust to protein concentration fluctuations. We describe how the cell-to-cell variability of ultrasensitive signaling systems can be actively regulated, e.g., by altering the expression of phosphatase(s) or by feedback/feedforward loops. Our calculations reveal that slow transcriptional negative feedback loops allow for variability suppression while maintaining switch-like decision making. Taken together, we describe design principles of signaling cascades that promote robustness. Our results may explain why certain signaling cascades like the yeast pheromone pathway show switch-like decision making with little cell-to-cell variability.

  15. Determinants of cell-to-cell variability in protein kinase signaling.

    Directory of Open Access Journals (Sweden)

    Matthias Jeschke

    Full Text Available Cells reliably sense environmental changes despite internal and external fluctuations, but the mechanisms underlying robustness remain unclear. We analyzed how fluctuations in signaling protein concentrations give rise to cell-to-cell variability in protein kinase signaling using analytical theory and numerical simulations. We characterized the dose-response behavior of signaling cascades by calculating the stimulus level at which a pathway responds ('pathway sensitivity' and the maximal activation level upon strong stimulation. Minimal kinase cascades with gradual dose-response behavior show strong variability, because the pathway sensitivity and the maximal activation level cannot be simultaneously invariant. Negative feedback regulation resolves this trade-off and coordinately reduces fluctuations in the pathway sensitivity and maximal activation. Feedbacks acting at different levels in the cascade control different aspects of the dose-response curve, thereby synergistically reducing the variability. We also investigated more complex, ultrasensitive signaling cascades capable of switch-like decision making, and found that these can be inherently robust to protein concentration fluctuations. We describe how the cell-to-cell variability of ultrasensitive signaling systems can be actively regulated, e.g., by altering the expression of phosphatase(s or by feedback/feedforward loops. Our calculations reveal that slow transcriptional negative feedback loops allow for variability suppression while maintaining switch-like decision making. Taken together, we describe design principles of signaling cascades that promote robustness. Our results may explain why certain signaling cascades like the yeast pheromone pathway show switch-like decision making with little cell-to-cell variability.

  16. Structure and Function of Vps15 in the Endosomal G Protein Signaling Pathway

    Energy Technology Data Exchange (ETDEWEB)

    Heenan, Erin J.; Vanhooke, Janeen L.; Temple, Brenda R.; Betts, Laurie; Sondek, John E.; Dohlman, Henrik G.; (UNC)

    2009-09-11

    G protein-coupled receptors mediate cellular responses to a wide variety of stimuli, including taste, light, and neurotransmitters. In the yeast Saccharomyces cerevisiae, activation of the pheromone pathway triggers events leading to mating. The view had long been held that the G protein-mediated signal occurs principally at the plasma membrane. Recently, it has been shown that the G protein {alpha} subunit Gpa1 can promote signaling at endosomes and requires two components of the sole phosphatidylinositol-3-kinase in yeast, Vps15 and Vps34. Vps15 contains multiple WD repeats and also binds to Gpa1 preferentially in the GDP-bound state; these observations led us to hypothesize that Vps15 may function as a G protein {beta} subunit at the endosome. Here we show an X-ray crystal structure of the Vps15 WD domain that reveals a seven-bladed propeller resembling that of typical G{beta} subunits. We show further that the WD domain is sufficient to bind Gpa1 as well as to Atg14, a potential G{gamma} protein that exists in a complex with Vps15. The Vps15 kinase domain together with the intermediate domain (linking the kinase and WD domains) also contributes to Gpa1 binding and is necessary for Vps15 to sustain G protein signaling. These findings reveal that the Vps15 G{beta}-like domain serves as a scaffold to assemble Gpa1 and Atg14, whereas the kinase and intermediate domains are required for proper signaling at the endosome.

  17. ER-to-plasma membrane tethering proteins regulate cell signaling and ER morphology.

    Science.gov (United States)

    Manford, Andrew G; Stefan, Christopher J; Yuan, Helen L; Macgurn, Jason A; Emr, Scott D

    2012-12-11

    Endoplasmic reticulum-plasma membrane (ER-PM) junctions are conserved structures defined as regions of the ER that tightly associate with the plasma membrane. However, little is known about the mechanisms that tether these organelles together and why such connections are maintained. Using a quantitative proteomic approach, we identified three families of ER-PM tethering proteins in yeast: Ist2 (related to mammalian TMEM16 ion channels), the tricalbins (Tcb1/2/3, orthologs of the extended synaptotagmins), and Scs2 and Scs22 (vesicle-associated membrane protein-associated proteins). Loss of all six tethering proteins results in the separation of the ER from the PM and the accumulation of cytoplasmic ER. Importantly, we find that phosphoinositide signaling is misregulated at the PM, and the unfolded protein response is constitutively activated in the ER in cells lacking ER-PM tether proteins. These results reveal critical roles for ER-PM contacts in cell signaling, organelle morphology, and ER function. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Cellular Antiviral Factors that Target Particle Infectivity of HIV-1.

    Science.gov (United States)

    Goffinet, Christine

    2016-01-01

    In the past decade, the identification and characterization of antiviral genes with the ability to interfere with virus replication has established cell-intrinsic innate immunity as a third line of antiviral defense in addition to adaptive and classical innate immunity. Understanding how cellular factors have evolved to inhibit HIV-1 reveals particularly vulnerable points of the viral replication cycle. Many, but not all, antiviral proteins share type I interferon-upregulated expression and sensitivity to viral counteraction or evasion measures. Whereas well-established restriction factors interfere with early post-entry steps and release of HIV-1, recent research has revealed a diverse set of proteins that reduce the infectious quality of released particles using individual, to date poorly understood modes of action. These include induction of paucity of mature glycoproteins in nascent virions or self-incorporation into the virus particle, resulting in poor infectiousness of the virion and impaired spread of the infection. A better understanding of these newly discovered antiviral factors may open new avenues towards the design of drugs that repress the spread of viruses whose genomes have already integrated.

  19. Identification of a functional, CRM-1-dependent nuclear export signal in hepatitis C virus core protein.

    Directory of Open Access Journals (Sweden)

    Andrea Cerutti

    Full Text Available Hepatitis C virus (HCV infection is a major cause of chronic liver disease worldwide. HCV core protein is involved in nucleocapsid formation, but it also interacts with multiple cytoplasmic and nuclear molecules and plays a crucial role in the development of liver disease and hepatocarcinogenesis. The core protein is found mostly in the cytoplasm during HCV infection, but also in the nucleus in patients with hepatocarcinoma and in core-transgenic mice. HCV core contains nuclear localization signals (NLS, but no nuclear export signal (NES has yet been identified.We show here that the aa(109-133 region directs the translocation of core from the nucleus to the cytoplasm by the CRM-1-mediated nuclear export pathway. Mutagenesis of the three hydrophobic residues (L119, I123 and L126 in the identified NES or in the sequence encoding the mature core aa(1-173 significantly enhanced the nuclear localisation of the corresponding proteins in transfected Huh7 cells. Both the NES and the adjacent hydrophobic sequence in domain II of core were required to maintain the core protein or its fragments in the cytoplasmic compartment. Electron microscopy studies of the JFH1 replication model demonstrated that core was translocated into the nucleus a few minutes after the virus entered the cell. The blockade of nucleocytoplasmic export by leptomycin B treatment early in infection led to the detection of core protein in the nucleus by confocal microscopy and coincided with a decrease in virus replication.Our data suggest that the functional NLS and NES direct HCV core protein shuttling between the cytoplasmic and nuclear compartments, with at least some core protein transported to the nucleus. These new properties of HCV core may be essential for virus multiplication and interaction with nuclear molecules, influence cell signaling and the pathogenesis of HCV infection.

  20. Identification of a functional, CRM-1-dependent nuclear export signal in hepatitis C virus core protein.

    Science.gov (United States)

    Cerutti, Andrea; Maillard, Patrick; Minisini, Rosalba; Vidalain, Pierre-Olivier; Roohvand, Farzin; Pecheur, Eve-Isabelle; Pirisi, Mario; Budkowska, Agata

    2011-01-01

    Hepatitis C virus (HCV) infection is a major cause of chronic liver disease worldwide. HCV core protein is involved in nucleocapsid formation, but it also interacts with multiple cytoplasmic and nuclear molecules and plays a crucial role in the development of liver disease and hepatocarcinogenesis. The core protein is found mostly in the cytoplasm during HCV infection, but also in the nucleus in patients with hepatocarcinoma and in core-transgenic mice. HCV core contains nuclear localization signals (NLS), but no nuclear export signal (NES) has yet been identified.We show here that the aa(109-133) region directs the translocation of core from the nucleus to the cytoplasm by the CRM-1-mediated nuclear export pathway. Mutagenesis of the three hydrophobic residues (L119, I123 and L126) in the identified NES or in the sequence encoding the mature core aa(1-173) significantly enhanced the nuclear localisation of the corresponding proteins in transfected Huh7 cells. Both the NES and the adjacent hydrophobic sequence in domain II of core were required to maintain the core protein or its fragments in the cytoplasmic compartment. Electron microscopy studies of the JFH1 replication model demonstrated that core was translocated into the nucleus a few minutes after the virus entered the cell. The blockade of nucleocytoplasmic export by leptomycin B treatment early in infection led to the detection of core protein in the nucleus by confocal microscopy and coincided with a decrease in virus replication.Our data suggest that the functional NLS and NES direct HCV core protein shuttling between the cytoplasmic and nuclear compartments, with at least some core protein transported to the nucleus. These new properties of HCV core may be essential for virus multiplication and interaction with nuclear molecules, influence cell signaling and the pathogenesis of HCV infection.

  1. Effects of protein-energy malnutrition on NF-kappaB signalling in murine peritoneal macrophages.

    Science.gov (United States)

    Fock, Ricardo Ambrósio; Rogero, Marcelo Macedo; Vinolo, Marco Aurélio Ramirez; Curi, Rui; Borges, Maria Carolina; Borelli, Primavera

    2010-04-01

    Protein-energy malnutrition (PEM) is an important public health problem affecting millions of people worldwide. PEM decreases resistance to infection, impairing a number of physiological processes. In unstimulated cells, NF-kappaB is kept from binding to its consensus sequence by the inhibitor I kappaB alpha, which retains NF-kappaB in the cytoplasm. Upon various signals, such as lipopolysaccharide (LPS), I kappaB alpha is rapidly degraded and NF-kappaB is induced to translocate into the nucleus, where it activates expression of various genes that participate in the inflammatory response, including those involved in the synthesis of TNF-alpha. TRAF-6 is a cytoplasmic adapter protein that links the stimulatory signal from Toll like receptor-4 to NF-kappaB. The aim of this study was to evaluate the effect of malnutrition on induction of TNF-alpha by LPS in murine peritoneal macrophages. We evaluated peritoneal cellularity, the expression of MyD88, TRAF-6, IKK, I kappaB alpha and NF-kappaB, NF-kappaB activation and TNF-alpha mRNA and protein synthesis in macrophages. Two-month-old male BALB/C mice were submitted to PEM with a low-protein diet that contained 2% protein, compared to 12% protein in the control diet. When the experimental group had lost about 20% of the original body weight, it was used in the subsequent experiments. Malnourished animals presented anemia, leucopenia and severe reduction in peritoneal cavity cellularity. TNF-alpha mRNA and protein levels of macrophages stimulated with LPS were significantly lower in malnourished animals. PEM also decreased TRAF-6 expression and NF-kappaB activation after LPS stimulation. These results led us to conclude that PEM changes NF-kB signalling pathway in macrophages to LPS stimulus.

  2. TGEV nucleocapsid protein induces cell cycle arrest and apoptosis through activation of p53 signaling

    International Nuclear Information System (INIS)

    Ding, Li; Huang, Yong; Du, Qian; Dong, Feng; Zhao, Xiaomin; Zhang, Wenlong; Xu, Xingang; Tong, Dewen

    2014-01-01

    Highlights: • TGEV N protein reduces cell viability by inducing cell cycle arrest and apoptosis. • TGEV N protein induces cell cycle arrest and apoptosis by regulating p53 signaling. • TGEV N protein plays important roles in TGEV-induced cell cycle arrest and apoptosis. - Abstract: Our previous studies showed that TGEV infection could induce cell cycle arrest and apoptosis via activation of p53 signaling in cultured host cells. However, it is unclear which viral gene causes these effects. In this study, we investigated the effects of TGEV nucleocapsid (N) protein on PK-15 cells. We found that TGEV N protein suppressed cell proliferation by causing cell cycle arrest at the S and G2/M phases and apoptosis. Characterization of various cellular proteins that are involved in regulating cell cycle progression demonstrated that the expression of N gene resulted in an accumulation of p53 and p21, which suppressed cyclin B1, cdc2 and cdk2 expression. Moreover, the expression of TGEV N gene promoted translocation of Bax to mitochondria, which in turn caused the release of cytochrome c, followed by activation of caspase-3, resulting in cell apoptosis in the transfected PK-15 cells following cell cycle arrest. Further studies showed that p53 inhibitor attenuated TGEV N protein induced cell cycle arrest at S and G2/M phases and apoptosis through reversing the expression changes of cdc2, cdk2 and cyclin B1 and the translocation changes of Bax and cytochrome c induced by TGEV N protein. Taken together, these results demonstrated that TGEV N protein might play an important role in TGEV infection-induced p53 activation and cell cycle arrest at the S and G2/M phases and apoptosis occurrence

  3. Interdependence of free zinc changes and protein complex assembly - insights into zinc signal regulation.

    Science.gov (United States)

    Kocyła, Anna; Adamczyk, Justyna; Krężel, Artur

    2018-01-24

    Cellular zinc (Zn(ii)) is bound with proteins that are part of the proteomes of all domains of life. It is mostly utilized as a catalytic or structural protein cofactor, which results in a vast number of binding architectures. The Zn(ii) ion is also important for the formation of transient protein complexes with a Zn(ii)-dependent quaternary structure that is formed upon cellular zinc signals. The mechanisms by which proteins associate with and dissociate from Zn(ii) and the connection with cellular Zn(ii) changes remain incompletely understood. In this study, we aimed to examine how zinc protein domains with various Zn(ii)-binding architectures are formed under free Zn(ii) concentration changes and how formation of the Zn(ii)-dependent assemblies is related to the protein concentration and reactivity. To accomplish these goals we chose four zinc domains with different Zn(ii)-to-protein binding stoichiometries: classical zinc finger (ZnP), LIM domain (Zn 2 P), zinc hook (ZnP 2 ) and zinc clasp (ZnP 1 P 2 ) folds. Our research demonstrated a lack of changes in the saturation level of intraprotein zinc binding sites, despite various peptide concentrations, while homo- and heterodimers indicated a concentration-dependent tendency. In other words, at a certain free Zn(ii) concentration, the fraction of a formed dimeric complex increases or decreases with subunit concentration changes. Secondly, even small or local changes in free Zn(ii) may significantly affect protein saturation depending on its architecture, function and subcellular concentration. In our paper, we indicate the importance of interdependence of free Zn(ii) availability and protein subunit concentrations for cellular zinc signal regulation.

  4. R7-binding protein targets the G protein β5/R7-regulator of G protein signaling complex to lipid rafts in neuronal cells and brain

    Directory of Open Access Journals (Sweden)

    Zhang Jian-Hua

    2007-09-01

    Full Text Available Abstract Background Heterotrimeric guanine nucleotide-binding regulatory proteins (G proteins, composed of Gα, Gβ, and Gγ subunits, are positioned at the inner face of the plasma membrane and relay signals from activated G protein-coupled cell surface receptors to various signaling pathways. Gβ5 is the most structurally divergent Gβ isoform and forms tight heterodimers with regulator of G protein signalling (RGS proteins of the R7 subfamily (R7-RGS. The subcellular localization of Gβ 5/R7-RGS protein complexes is regulated by the palmitoylation status of the associated R7-binding protein (R7BP, a recently discovered SNARE-like protein. We investigate here whether R7BP controls the targeting of Gβ5/R7-RGS complexes to lipid rafts, cholesterol-rich membrane microdomains where conventional heterotrimeric G proteins and some effector proteins are concentrated in neurons and brain. Results We show that endogenous Gβ5/R7-RGS/R7BP protein complexes are present in native neuron-like PC12 cells and that a fraction is targeted to low-density, detergent-resistant membrane lipid rafts. The buoyant density of endogenous raft-associated Gβ5/R7-RGS protein complexes in PC12 cells was similar to that of lipid rafts containing the palmitoylated marker proteins PSD-95 and LAT, but distinct from that of the membrane microdomain where flotillin was localized. Overexpression of wild-type R7BP, but not its palmitoylation-deficient mutant, greatly enriched the fraction of endogenous Gβ5/R7-RGS protein complexes in the lipid rafts. In HEK-293 cells the palmitoylation status of R7BP also regulated the lipid raft targeting of co-expressed Gβ5/R7-RGS/R7BP proteins. A fraction of endogenous Gβ5/R7-RGS/R7BP complexes was also present in lipid rafts in mouse brain. Conclusion A fraction of Gβ5/R7-RGS/R7BP protein complexes is targeted to low-density, detergent-resistant membrane lipid rafts in PC12 cells and brain. In cultured cells, the palmitoylation status of

  5. Identification of a tripartite import signal in the Ewing Sarcoma protein (EWS)

    International Nuclear Information System (INIS)

    Shaw, Debra J.; Morse, Robert; Todd, Adrian G.; Eggleton, Paul; Lorson, Christian L.; Young, Philip J.

    2009-01-01

    The Ewing Sarcoma (EWS) protein is a ubiquitously expressed RNA processing factor that localises predominantly to the nucleus. However, the mechanism through which EWS enters the nucleus remains unclear, with differing reports identifying three separate import signals within the EWS protein. Here we have utilized a panel of truncated EWS proteins to clarify the reported nuclear localisation signals. We describe three C-terminal domains that are important for efficient EWS nuclear localization: (1) the third RGG-motif; (2) the last 10 amino acids (known as the PY-import motif); and (3) the zinc-finger motif. Although these three domains are involved in nuclear import, they are not independently capable of driving the efficient import of a GFP-moiety. However, collectively they form a complex tripartite signal that efficiently drives GFP-import into the nucleus. This study helps clarify the EWS import signal, and the identification of the involvement of both the RGG- and zinc-finger motifs has wide reaching implications.

  6. Identification of a tripartite import signal in the Ewing Sarcoma protein (EWS)

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, Debra J.; Morse, Robert; Todd, Adrian G. [Clinical Neurobiology, IBCS, Peninsula College of Medicine and Dentistry, Exeter EX1 2LU (United Kingdom); Eggleton, Paul [Inflammation and Musculoskeletal Disease, IBCS, Peninsula College of Medicine and Dentistry, Exeter EX1 2LU (United Kingdom); MRC Immunochemistry Unit, University of Oxford, Oxford OX1 3QU (United Kingdom); Lorson, Christian L. [Department of Veterinary Pathobiology, Bond Life Sciences Center, 1201 Rollins Road, University of Missouri, Columbia, MO 65211 (United States); Young, Philip J., E-mail: philip.young@pms.ac.uk [Clinical Neurobiology, IBCS, Peninsula College of Medicine and Dentistry, Exeter EX1 2LU (United Kingdom)

    2009-12-25

    The Ewing Sarcoma (EWS) protein is a ubiquitously expressed RNA processing factor that localises predominantly to the nucleus. However, the mechanism through which EWS enters the nucleus remains unclear, with differing reports identifying three separate import signals within the EWS protein. Here we have utilized a panel of truncated EWS proteins to clarify the reported nuclear localisation signals. We describe three C-terminal domains that are important for efficient EWS nuclear localization: (1) the third RGG-motif; (2) the last 10 amino acids (known as the PY-import motif); and (3) the zinc-finger motif. Although these three domains are involved in nuclear import, they are not independently capable of driving the efficient import of a GFP-moiety. However, collectively they form a complex tripartite signal that efficiently drives GFP-import into the nucleus. This study helps clarify the EWS import signal, and the identification of the involvement of both the RGG- and zinc-finger motifs has wide reaching implications.

  7. cAMP-dependent Protein Kinase (PKA) Signaling Is Impaired in the Diabetic Heart.

    Science.gov (United States)

    Bockus, Lee B; Humphries, Kenneth M

    2015-12-04

    Diabetes mellitus causes cardiac dysfunction and heart failure that is associated with metabolic abnormalities and autonomic impairment. Autonomic control of ventricular function occurs through regulation of cAMP-dependent protein kinase (PKA). The diabetic heart has suppressed β-adrenergic responsiveness, partly attributable to receptor changes, yet little is known about how PKA signaling is directly affected. Control and streptozotocin-induced diabetic mice were therefore administered 8-bromo-cAMP (8Br-cAMP) acutely to activate PKA in a receptor-independent manner, and cardiac hemodynamic function and PKA signaling were evaluated. In response to 8Br-cAMP treatment, diabetic mice had impaired inotropic and lusitropic responses, thus demonstrating postreceptor defects. This impaired signaling was mediated by reduced PKA activity and PKA catalytic subunit content in the cytoplasm and myofilaments. Compartment-specific loss of PKA was reflected by reduced phosphorylation of discrete substrates. In response to 8Br-cAMP treatment, the glycolytic activator PFK-2 was robustly phosphorylated in control animals but not diabetics. Control adult cardiomyocytes cultured in lipid-supplemented media developed similar changes in PKA signaling, suggesting that lipotoxicity is a contributor to diabetes-induced β-adrenergic signaling dysfunction. This work demonstrates that PKA signaling is impaired in diabetes and suggests that treating hyperlipidemia is vital for proper cardiac signaling and function. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  8. cAMP-dependent Protein Kinase (PKA) Signaling Is Impaired in the Diabetic Heart*

    Science.gov (United States)

    Bockus, Lee B.; Humphries, Kenneth M.

    2015-01-01

    Diabetes mellitus causes cardiac dysfunction and heart failure that is associated with metabolic abnormalities and autonomic impairment. Autonomic control of ventricular function occurs through regulation of cAMP-dependent protein kinase (PKA). The diabetic heart has suppressed β-adrenergic responsiveness, partly attributable to receptor changes, yet little is known about how PKA signaling is directly affected. Control and streptozotocin-induced diabetic mice were therefore administered 8-bromo-cAMP (8Br-cAMP) acutely to activate PKA in a receptor-independent manner, and cardiac hemodynamic function and PKA signaling were evaluated. In response to 8Br-cAMP treatment, diabetic mice had impaired inotropic and lusitropic responses, thus demonstrating postreceptor defects. This impaired signaling was mediated by reduced PKA activity and PKA catalytic subunit content in the cytoplasm and myofilaments. Compartment-specific loss of PKA was reflected by reduced phosphorylation of discrete substrates. In response to 8Br-cAMP treatment, the glycolytic activator PFK-2 was robustly phosphorylated in control animals but not diabetics. Control adult cardiomyocytes cultured in lipid-supplemented media developed similar changes in PKA signaling, suggesting that lipotoxicity is a contributor to diabetes-induced β-adrenergic signaling dysfunction. This work demonstrates that PKA signaling is impaired in diabetes and suggests that treating hyperlipidemia is vital for proper cardiac signaling and function. PMID:26468277

  9. Translational control in plant antiviral immunity

    Directory of Open Access Journals (Sweden)

    João Paulo B. Machado

    Full Text Available Abstract Due to the limited coding capacity of viral genomes, plant viruses depend extensively on the host cell machinery to support the viral life cycle and, thereby, interact with a large number of host proteins during infection. Within this context, as plant viruses do not harbor translation-required components, they have developed several strategies to subvert the host protein synthesis machinery to produce rapidly and efficiently the viral proteins. As a countermeasure against infection, plants have evolved defense mechanisms that impair viral infections. Among them, the host-mediated translational suppression has been characterized as an efficient mean to restrict infection. To specifically suppress translation of viral mRNAs, plants can deploy susceptible recessive resistance genes, which encode translation initiation factors from the eIF4E and eIF4G family and are required for viral mRNA translation and multiplication. Additionally, recent evidence has demonstrated that, alternatively to the cleavage of viral RNA targets, host cells can suppress viral protein translation to silence viral RNA. Finally, a novel strategy of plant antiviral defense based on suppression of host global translation, which is mediated by the transmembrane immune receptor NIK1 (nuclear shuttle protein (NSP-Interacting Kinase1, is discussed in this review.

  10. Antiviral Polymer Therapeutics

    DEFF Research Database (Denmark)

    Smith, Anton Allen Abbotsford

    2014-01-01

    polymerized in a controlled manner with carrier monomers of historically proven biocompatible polymers. The carrier polymers, the loading of ribavirin as well as the size of the polymer were varied systematically with the aid of an automated synthesis platform. These polymers were tested in a cellular assay...... of reversible-addition-fragmentation chain transfer polymerization, which not only controls the size of polymer, but also allows the introduction of a terminal amine on the polymer which can be used for further conjugation. This has allowed for not only fluorescent labeling of the polymer, but also protein...... is mediated through specific transporters, it is thought that the accumulation can be alleviated through the attachment of ribavirin to a macromolecule. To this end, ribavirin was enzymatically modified into a monomer compatible with controlled polymerization techniques. The ribavirin monomers were...

  11. The essential role of G protein-coupled receptor (GPCR) signaling in regulating T cell immunity.

    Science.gov (United States)

    Wang, Dashan

    2018-06-01

    The aim of this paper is to clarify the critical role of GPCR signaling in T cell immunity. The G protein-coupled receptors (GPCRs) are the most common targets in current pharmaceutical industry, and represent the largest and most versatile family of cell surface communicating molecules. GPCRs can be activated by a diverse array of ligands including neurotransmitters, chemokines as well as sensory stimuli. Therefore, GPCRs are involved in many key cellular and physiological processes, such as sense of light, taste and smell, neurotransmission, metabolism, endocrine and exocrine secretion. In recent years, GPCRs have been found to play an important role in immune system. T cell is an important type of immune cell, which plays a central role in cell-mediated immunity. A variety of GPCRs and their signaling mediators (RGS proteins, GRKs and β-arrestin) have been found to express in T cells and involved T cell-mediated immunity. We will summarize the role of GPCR signaling and their regulatory molecules in T cell activation, homeostasis and function in this article. GPCR signaling plays an important role in T cell activation, homeostasis and function. GPCR signaling is critical in regulating T cell immunity.

  12. The depletion of protein signals in metabonomics analysis with the WET-CPMG pulse sequence

    International Nuclear Information System (INIS)

    Van, Que N.; Chmurny, Gwendolyn N.; Veenstra, Timothy D.

    2003-01-01

    Nuclear magnetic resonance (NMR) spectroscopy is a powerful analytical tool capable of providing a comprehensive metabolic profile of biofluids such as urine, plasma, and serum. Unfortunately, when measuring serum and plasma, the high protein concentration can obscure the signals originating from low molecular weight metabolites. We evaluated the use of different parameters within the Carr-Purcell-Meiboom-Gill (CPMG) pulse train of fast spin-echoes to remove the macromolecular signal contribution in one-dimensional proton ( 1 H) NMR spectra. Experimental parameters such as the refocusing delay in the CPMG pulse train, pulse miscalibration, and recycle time were examined to assess the ability to remove the protein signals from the spectrum without causing a deleterious effect on the signals originating from free, low molecular weight metabolites. The 1 H-NMR spectra of a variety of serum samples spiked with 2 ' -deoxyadenosine were acquired using various acquisition parameters. Our results show that the delay used in the CPMG spin-echo and the combination of the acquisition pulse flip angle and recycle time are the two major factors affecting the observed metabolite signal amplitudes in the resulting 1 H-NMR spectrum

  13. The Syk protein tyrosine kinase can function independently of CD45 or Lck in T cell antigen receptor signaling

    NARCIS (Netherlands)

    Chu, D. H.; Spits, H.; Peyron, J. F.; Rowley, R. B.; Bolen, J. B.; Weiss, A.

    1996-01-01

    The protein tyrosine phosphatase CD45 is a critical component of the T cell antigen receptor (TCR) signaling pathway, acting as a positive regulator of Src family protein tyrosine kinases (PTKs) such as Lck. Most CD45-deficient human and murine T cell lines are unable to signal through their TCRs.

  14. Identification of a functional nuclear export signal in the green fluorescent protein asFP499

    International Nuclear Information System (INIS)

    Mustafa, Huseyin; Strasser, Bernd; Rauth, Sabine; Irving, Robert A.; Wark, Kim L.

    2006-01-01

    The green fluorescent protein (GFP) asFP499 from Anemonia sulcata is a distant homologue of the GFP from Aequorea victoria. We cloned the asFP499 gene into a mammalian expression vector and showed that this protein was expressed in the human lymphoblast cell line Ramos RA1 and in the embryonic kidney 293T cell line (HEK 293T). In HEK 293T cells, asFP499 was localized mainly in the cytoplasm, suggesting that the protein was excluded from the nucleus. We identified 194 LRMEKLNI 201 as a candidate nuclear export signal in asFP499 and mutated the isoleucine at position 201 to an alanine. Unlike the wildtype form, the mutant protein was distributed throughout the cytoplasm and nucleus. This is First report of a GFP that contains a functional NES

  15. AKAP3 synthesis is mediated by RNA binding proteins and PKA signaling during mouse spermiogenesis.

    Science.gov (United States)

    Xu, Kaibiao; Yang, Lele; Zhao, Danyun; Wu, Yaoyao; Qi, Huayu

    2014-06-01

    Mammalian spermatogenesis is regulated by coordinated gene expression in a spatiotemporal manner. The spatiotemporal regulation of major sperm proteins plays important roles during normal development of the male gamete, of which the underlying molecular mechanisms are poorly understood. A-kinase anchoring protein 3 (AKAP3) is one of the major components of the fibrous sheath of the sperm tail that is formed during spermiogenesis. In the present study, we analyzed the expression of sperm-specific Akap3 and the potential regulatory factors of its protein synthesis during mouse spermiogenesis. Results showed that the transcription of Akap3 precedes its protein synthesis by about 2 wk. Nascent AKAP3 was found to form protein complex with PKA and RNA binding proteins (RBPs), including PIWIL1, PABPC1, and NONO, as revealed by coimmunoprecipitation and protein mass spectrometry. RNA electrophoretic gel mobility shift assay showed that these RBPs bind sperm-specific mRNAs, of which proteins are synthesized during the elongating stage of spermiogenesis. Biochemical and cell biological experiments demonstrated that PIWIL1, PABPC1, and NONO interact with each other and colocalize in spermatids' RNA granule, the chromatoid body. In addition, NONO was found in extracytoplasmic granules in round spermatids, whereas PIWIL1 and PABPC1 were diffusely localized in cytoplasm of elongating spermatids, indicating their participation at different steps of mRNA metabolism during spermatogenesis. Interestingly, type I PKA subunits colocalize with PIWIL1 and PABPC1 in the cytoplasm of elongating spermatids and cosediment with the RBPs in polysomal fractions on sucrose gradients. Further biochemical analyses revealed that activation of PKA positively regulates AKAP3 protein synthesis without changing its mRNA level in elongating spermatids. Taken together, these results indicate that PKA signaling directly participates in the regulation of protein translation in postmeiotic male germ cells

  16. Secretion of a recombinant protein without a signal peptide by the exocrine glands of transgenic rabbits.

    Directory of Open Access Journals (Sweden)

    Andrea Kerekes

    Full Text Available Transgenic rabbits carrying mammary gland specific gene constructs are extensively used for excreting recombinant proteins into the milk. Here, we report refined phenotyping of previously generated Venus transposon-carrying transgenic rabbits with particular emphasis on the secretion of the reporter protein by exocrine glands, such as mammary, salivary, tear and seminal glands. The Sleeping Beauty (SB transposon transgenic construct contains the Venus fluorophore cDNA, but without a signal peptide for the secretory pathway, driven by the ubiquitous CAGGS (CAG promoter. Despite the absence of a signal peptide, the fluorophore protein was readily detected in milk, tear, saliva and seminal fluids. The expression pattern was verified by Western blot analysis. Mammary gland epithelial cells of SB-CAG-Venus transgenic lactating does also showed Venus-specific expression by tissue histology and fluorescence microscopy. In summary, the SB-CAG-Venus transgenic rabbits secrete the recombinant protein by different glands. This finding has relevance not only for the understanding of the biological function of exocrine glands, but also for the design of constructs for expression of recombinant proteins in dairy animals.

  17. Secretion of a recombinant protein without a signal peptide by the exocrine glands of transgenic rabbits.

    Science.gov (United States)

    Kerekes, Andrea; Hoffmann, Orsolya Ivett; Iski, Gergely; Lipták, Nándor; Gócza, Elen; Kues, Wilfried A; Bősze, Zsuzsanna; Hiripi, László

    2017-01-01

    Transgenic rabbits carrying mammary gland specific gene constructs are extensively used for excreting recombinant proteins into the milk. Here, we report refined phenotyping of previously generated Venus transposon-carrying transgenic rabbits with particular emphasis on the secretion of the reporter protein by exocrine glands, such as mammary, salivary, tear and seminal glands. The Sleeping Beauty (SB) transposon transgenic construct contains the Venus fluorophore cDNA, but without a signal peptide for the secretory pathway, driven by the ubiquitous CAGGS (CAG) promoter. Despite the absence of a signal peptide, the fluorophore protein was readily detected in milk, tear, saliva and seminal fluids. The expression pattern was verified by Western blot analysis. Mammary gland epithelial cells of SB-CAG-Venus transgenic lactating does also showed Venus-specific expression by tissue histology and fluorescence microscopy. In summary, the SB-CAG-Venus transgenic rabbits secrete the recombinant protein by different glands. This finding has relevance not only for the understanding of the biological function of exocrine glands, but also for the design of constructs for expression of recombinant proteins in dairy animals.

  18. Budesonide and formoterol reduce early innate anti-viral immune responses in vitro.

    Directory of Open Access Journals (Sweden)

    Janet M Davies

    Full Text Available Asthma is a chronic inflammatory airways disease in which respiratory viral infections frequently trigger exacerbations. Current treatment of asthma with combinations of inhaled corticosteroids and long acting beta2 agonists improves asthma control and reduces exacerbations but what impact this might have on innate anti-viral immunity is unclear. We investigated the in vitro effects of asthma drugs on innate anti-viral immunity. Peripheral blood mononuclear cells (PBMC from healthy and asthmatic donors were cultured for 24 hours with the Toll-like receptor 7 agonist, imiquimod, or rhinovirus 16 (RV16 in the presence of budesonide and/or formoterol. Production of proinflammatory cytokines and expression of anti-viral intracellular signalling molecules were measured by ELISA and RT-PCR respectively. In PBMC from healthy donors, budesonide alone inhibited IP-10 and IL-6 production induced by imiquimod in a concentration-dependent manner and the degree of inhibition was amplified when budesonide and formoterol were used in combination. Formoterol alone had little effect on these parameters, except at high concentrations (10⁻⁶ M when IL-6 production increased. In RV16 stimulated PBMC, the combination of budesonide and formoterol inhibited IFNα and IP-10 production in asthmatic as well as healthy donors. Combination of budesonide and formoterol also inhibited RV16-stimulated expression of the type I IFN induced genes myxovirus protein A and 2', 5' oligoadenylate synthetise. Notably, RV16 stimulated lower levels of type Myxovirus A and oligoadenylate synthase in PBMC of asthmatics than control donors. These in vitro studies demonstrate that combinations of drugs commonly used in asthma therapy inhibit both early pro-inflammatory cytokines and key aspects of the type I IFN pathway. These findings suggest that budesonide and formoterol curtail excessive inflammation induced by rhinovirus infections in patients with asthma, but whether this inhibits

  19. Phosphorylation near nuclear localization signal regulates nuclear import of adenomatous polyposis coli protein

    OpenAIRE

    Zhang, Fang; White, Raymond L.; Neufeld, Kristi L.

    2000-01-01

    Mutation of the adenomatous polyposis coli (APC) gene is an early step in the development of colorectal carcinomas. APC protein is located in both the cytoplasm and the nucleus. The objective of this study was to define the nuclear localization signals (NLSs) in APC protein. APC contains two potential NLSs comprising amino acids 1767–1772 (NLS1APC) and 2048–2053 (NLS2APC). Both APC NLSs are well conserved among human, mouse, rat, and fly. NLS1APC and NLS2APC each w...

  20. The you gene encodes an EGF-CUB protein essential for Hedgehog signaling in zebrafish.

    Directory of Open Access Journals (Sweden)

    Ian G Woods

    2005-03-01

    Full Text Available Hedgehog signaling is required for many aspects of development in vertebrates and invertebrates. Misregulation of the Hedgehog pathway causes developmental abnormalities and has been implicated in certain types of cancer. Large-scale genetic screens in zebrafish have identified a group of mutations, termed you-class mutations, that share common defects in somite shape and in most cases disrupt Hedgehog signaling. These mutant embryos exhibit U-shaped somites characteristic of defects in slow muscle development. In addition, Hedgehog pathway mutations disrupt spinal cord patterning. We report the positional cloning of you, one of the original you-class mutations, and show that it is required for Hedgehog signaling in the development of slow muscle and in the specification of ventral fates in the spinal cord. The you gene encodes a novel protein with conserved EGF and CUB domains and a secretory pathway signal sequence. Epistasis experiments support an extracellular role for You upstream of the Hedgehog response mechanism. Analysis of chimeras indicates that you mutant cells can appropriately respond to Hedgehog signaling in a wild-type environment. Additional chimera analysis indicates that wild-type you gene function is not required in axial Hedgehog-producing cells, suggesting that You is essential for transport or stability of Hedgehog signals in the extracellular environment. Our positional cloning and functional studies demonstrate that You is a novel extracellular component of the Hedgehog pathway in vertebrates.

  1. A conserved PHD finger protein and endogenous RNAi modulate insulin signaling in Caenorhabditis elegans.

    Science.gov (United States)

    Mansisidor, Andres R; Cecere, Germano; Hoersch, Sebastian; Jensen, Morten B; Kawli, Trupti; Kennedy, Lisa M; Chavez, Violeta; Tan, Man-Wah; Lieb, Jason D; Grishok, Alla

    2011-09-01

    Insulin signaling has a profound effect on longevity and the oxidative stress resistance of animals. Inhibition of insulin signaling results in the activation of DAF-16/FOXO and SKN-1/Nrf transcription factors and increased animal fitness. By studying the biological functions of the endogenous RNA interference factor RDE-4 and conserved PHD zinc finger protein ZFP-1 (AF10), which regulate overlapping sets of genes in Caenorhabditis elegans, we identified an important role for these factors in the negative modulation of transcription of the insulin/PI3 signaling-dependent kinase PDK-1. Consistently, increased expression of pdk-1 in zfp-1 and rde-4 mutants contributed to their reduced lifespan and sensitivity to oxidative stress and pathogens due to the reduction in the expression of DAF-16 and SKN-1 targets. We found that the function of ZFP-1 in modulating pdk-1 transcription was important for the extended lifespan of the age-1(hx546) reduction-of-function PI3 kinase mutant, since the lifespan of the age-1; zfp-1 double mutant strain was significantly shorter compared to age-1(hx546). We further demonstrate that overexpression of ZFP-1 caused an increased resistance to oxidative stress in a DAF-16-dependent manner. Our findings suggest that epigenetic regulation of key upstream signaling components in signal transduction pathways through chromatin and RNAi may have a large impact on the outcome of signaling and expression of numerous downstream genes.

  2. Proteomes of the barley aleurone layer: A model system for plant signalling and protein secretion

    DEFF Research Database (Denmark)

    Finnie, Christine; Andersen, Birgit; Shahpiri, Azar

    2011-01-01

    molecules in an isolated system. These properties have led to its use as a model system for the study of plant signalling and germination. More recently, proteome analysis of the aleurone layer has provided new insight into this unique tissue including identification of plasma membrane proteins and targeted...... analysis of germination-related changes and the thioredoxin system. Here, analysis of intracellular and secreted proteomes reveals features of the aleurone layer system that makes it promising for investigations of plant protein secretion mechanisms....... to gibberellic acid produced by the embryo, the aleurone layer synthesises hydrolases that are secreted to the endosperm for the degradation of storage products. The barley aleurone layer can be separated from the other seed tissues and maintained in culture, allowing the study of the effect of added signalling...

  3. G Protein-Linked Signaling Pathways in Bipolar and Major Depressive Disorders

    Directory of Open Access Journals (Sweden)

    Hiroaki eTomita

    2013-12-01

    Full Text Available The G-protein linked signaling system (GPLS comprises a large number of G-proteins, G protein-coupled receptors (GPCRs, GPCR ligands, and downstream effector molecules. G-proteins interact with both GPCRs and downstream effectors such as cyclic adenosine monophosphate (cAMP, phosphatidylinositols, and ion channels. The GPLS is implicated in the pathophysiology and pharmacology of both major depressive disorder (MDD and bipolar disorder (BPD. This study evaluated whether GPLS is altered at the transcript level. The gene expression in the dorsolateral prefrontal (DLPFC and anterior cingulate (ACC were compared from MDD, BPD, and control subjects using Affymetrix Gene Chips and real time quantitative PCR. High quality brain tissue was used in the study to control for confounding effects of agonal events, tissue pH, RNA integrity, gender, and age. GPLS signaling transcripts were altered especially in the ACC of BPD and MDD subjects. Transcript levels of molecules which repress cAMP activity were increased in BPD and decreased in MDD. Two orphan GPCRs, GPRC5B and GPR37, showed significantly decreased expression levels in MDD, and significantly increased expression levels in BPD. Our results suggest opposite changes in BPD and MDD in the GPLS, ‘activated’ cAMP signaling activity in BPD and ‘blunted’ cAMP signaling activity in MDD. GPRC5B and GPR37 both appear to have behavioral effects, and are also candidate genes for neurodegenerative disorders. In the context of the opposite changes observed in BPD and MDD, these GPCRs warrant further study of their brain effects.

  4. Domain requirements for the Dock adapter protein in growth- cone signaling

    OpenAIRE

    Rao, Yong; Zipursky, S. Lawrence

    1998-01-01

    Tyrosine phosphorylation has been implicated in growth-cone guidance through genetic, biochemical, and pharmacological studies. Adapter proteins containing src homology 2 (SH2) domains and src homology 3 (SH3) domains provide a means of linking guidance signaling through phosphotyrosine to downstream effectors regulating growth-cone motility. The Drosophila adapter, Dreadlocks (Dock), the homolog of mammalian Nck containing three N-terminal SH3 domains and a single SH2 domain, is highly speci...

  5. Unfolded protein response (UPR) signaling regulates arsenic trioxide-mediated macrophage innate immune function disruption

    International Nuclear Information System (INIS)

    Srivastava, Ritesh K.; Li, Changzhao; Chaudhary, Sandeep C.; Ballestas, Mary E.; Elmets, Craig A.; Robbins, David J.; Matalon, Sadis; Deshane, Jessy S.; Afaq, Farrukh; Bickers, David R.; Athar, Mohammad

    2013-01-01

    Arsenic exposure is known to disrupt innate immune functions in humans and in experimental animals. In this study, we provide a mechanism by which arsenic trioxide (ATO) disrupts macrophage functions. ATO treatment of murine macrophage cells diminished internalization of FITC-labeled latex beads, impaired clearance of phagocytosed fluorescent bacteria and reduced secretion of pro-inflammatory cytokines. These impairments in macrophage functions are associated with ATO-induced unfolded protein response (UPR) signaling pathway characterized by the enhancement in proteins such as GRP78, p-PERK, p-eIF2α, ATF4 and CHOP. The expression of these proteins is altered both at transcriptional and translational levels. Pretreatment with chemical chaperon, 4-phenylbutyric acid (PBA) attenuated the ATO-induced activation in UPR signaling and afforded protection against ATO-induced disruption of macrophage functions. This treatment also reduced ATO-mediated reactive oxygen species (ROS) generation. Interestingly, treatment with antioxidant N-acetylcysteine (NAC) prior to ATO exposure, not only reduced ROS production and UPR signaling but also improved macrophage functions. These data demonstrate that UPR signaling and ROS generation are interdependent and are involved in the arsenic-induced pathobiology of macrophage. These data also provide a novel strategy to block the ATO-dependent impairment in innate immune responses. - Highlights: • Inorganic arsenic to humans and experimental animals disrupt innate immune responses. • The mechanism underlying arsenic impaired macrophage functions involves UPR signaling. • Chemical chaperon attenuates arsenic-mediated macrophage function impairment. • Antioxidant, NAC blocks impairment in arsenic-treated macrophage functions

  6. Rapamycin and Glucose-Target of Rapamycin (TOR) Protein Signaling in Plants*

    Science.gov (United States)

    Xiong, Yan; Sheen, Jen

    2012-01-01

    Target of rapamycin (TOR) kinase is an evolutionarily conserved master regulator that integrates energy, nutrients, growth factors, and stress signals to promote survival and growth in all eukaryotes. The reported land plant resistance to rapamycin and the embryo lethality of the Arabidopsis tor mutants have hindered functional dissection of TOR signaling in plants. We developed sensitive cellular and seedling assays to monitor endogenous Arabidopsis TOR activity based on its conserved S6 kinase (S6K) phosphorylation. Surprisingly, rapamycin effectively inhibits Arabidopsis TOR-S6K1 signaling and retards glucose-mediated root and leaf growth, mimicking estradiol-inducible tor mutants. Rapamycin inhibition is relieved in transgenic plants deficient in Arabidopsis FK506-binding protein 12 (FKP12), whereas FKP12 overexpression dramatically enhances rapamycin sensitivity. The role of Arabidopsis FKP12 is highly specific as overexpression of seven closely related FKP proteins fails to increase rapamycin sensitivity. Rapamycin exerts TOR inhibition by inducing direct interaction between the TOR-FRB (FKP-rapamycin binding) domain and FKP12 in plant cells. We suggest that variable endogenous FKP12 protein levels may underlie the molecular explanation for longstanding enigmatic observations on inconsistent rapamycin resistance in plants and in various mammalian cell lines or diverse animal cell types. Integrative analyses with rapamycin and conditional tor and fkp12 mutants also reveal a central role of glucose-TOR signaling in root hair formation. Our studies demonstrate the power of chemical genetic approaches in the discovery of previously unknown and pivotal functions of glucose-TOR signaling in governing the growth of cotyledons, true leaves, petioles, and primary and secondary roots and root hairs. PMID:22134914

  7. Unfolded protein response (UPR) signaling regulates arsenic trioxide-mediated macrophage innate immune function disruption

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Ritesh K.; Li, Changzhao; Chaudhary, Sandeep C. [Department of Dermatology and Skin Diseases Research Center, University of Alabama at Birmingham, Birmingham, AL (United States); Ballestas, Mary E. [Department of Pediatrics Infectious Disease, Children' s of Alabama, School of Medicine, University of Alabama at Birmingham, AL (United States); Elmets, Craig A. [Department of Dermatology and Skin Diseases Research Center, University of Alabama at Birmingham, Birmingham, AL (United States); Robbins, David J. [Department of Surgery, Molecular Oncology Program, Miller School of Medicine, University of Miami, Miami (United States); Matalon, Sadis [Department of Anesthesiology, University of Alabama at Birmingham, Birmingham, AL (United States); Deshane, Jessy S. [Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL (United States); Afaq, Farrukh [Department of Dermatology and Skin Diseases Research Center, University of Alabama at Birmingham, Birmingham, AL (United States); Bickers, David R. [Department of Dermatology, Columbia University Medical Center, New York (United States); Athar, Mohammad, E-mail: mathar@uab.edu [Department of Dermatology and Skin Diseases Research Center, University of Alabama at Birmingham, Birmingham, AL (United States)

    2013-11-01

    Arsenic exposure is known to disrupt innate immune functions in humans and in experimental animals. In this study, we provide a mechanism by which arsenic trioxide (ATO) disrupts macrophage functions. ATO treatment of murine macrophage cells diminished internalization of FITC-labeled latex beads, impaired clearance of phagocytosed fluorescent bacteria and reduced secretion of pro-inflammatory cytokines. These impairments in macrophage functions are associated with ATO-induced unfolded protein response (UPR) signaling pathway characterized by the enhancement in proteins such as GRP78, p-PERK, p-eIF2α, ATF4 and CHOP. The expression of these proteins is altered both at transcriptional and translational levels. Pretreatment with chemical chaperon, 4-phenylbutyric acid (PBA) attenuated the ATO-induced activation in UPR signaling and afforded protection against ATO-induced disruption of macrophage functions. This treatment also reduced ATO-mediated reactive oxygen species (ROS) generation. Interestingly, treatment with antioxidant N-acetylcysteine (NAC) prior to ATO exposure, not only reduced ROS production and UPR signaling but also improved macrophage functions. These data demonstrate that UPR signaling and ROS generation are interdependent and are involved in the arsenic-induced pathobiology of macrophage. These data also provide a novel strategy to block the ATO-dependent impairment in innate immune responses. - Highlights: • Inorganic arsenic to humans and experimental animals disrupt innate immune responses. • The mechanism underlying arsenic impaired macrophage functions involves UPR signaling. • Chemical chaperon attenuates arsenic-mediated macrophage function impairment. • Antioxidant, NAC blocks impairment in arsenic-treated macrophage functions.

  8. LIMPIC: a computational method for the separation of protein MALDI-TOF-MS signals from noise

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    Di Nicola Marta

    2007-03-01

    Full Text Available Abstract Background Mass spectrometry protein profiling is a promising tool for biomarker discovery in clinical proteomics. However, the development of a reliable approach for the separation of protein signals from noise is required. In this paper, LIMPIC, a computational method for the detection of protein peaks from linear-mode MALDI-TOF data is proposed. LIMPIC is based on novel techniques for background noise reduction and baseline removal. Peak detection is performed considering the presence of a non-homogeneous noise level in the mass spectrum. A comparison of the peaks collected from multiple spectra is used to classify them on the basis of a detection rate parameter, and hence to separate the protein signals from other disturbances. Results LIMPIC preprocessing proves to be superior than other classical preprocessing techniques, allowing for a reliable decomposition of the background noise and the baseline drift from the MALDI-TOF mass spectra. It provides lower coefficient of variation associated with the peak intensity, improving the reliability of the information that can be extracted from single spectra. Our results show that LIMPIC peak-picking is effective even in low protein concentration regimes. The analytical comparison with commercial and freeware peak-picking algorithms demonstrates its superior performances in terms of sensitivity and specificity, both on in-vitro purified protein samples and human plasma samples. Conclusion The quantitative information on the peak intensity extracted with LIMPIC could be used for the recognition of significant protein profiles by means of advanced statistic tools: LIMPIC might be valuable in the perspective of biomarker discovery.

  9. Global Screening of Antiviral Genes that Suppress Baculovirus Transgene Expression in Mammalian Cells.

    Science.gov (United States)

    Wang, Chia-Hung; Naik, Nenavath Gopal; Liao, Lin-Li; Wei, Sung-Chan; Chao, Yu-Chan

    2017-09-15

    Although baculovirus has been used as a safe and convenient gene delivery vector in mammalian cells, baculovirus-mediated transgene expression is less effective in various mammalian cell lines. Identification of the negative regulators in host cells is necessary to improve baculovirus-based expression systems. Here, we performed high-throughput shRNA library screening, targeting 176 antiviral innate immune genes, and identified 43 host restriction factor genes in a human A549 lung carcinoma cell line. Among them, suppression of receptor interaction protein kinase 1 (RIP1, also known as RIPK1) significantly increased baculoviral transgene expression without resulting in significant cell death. Silencing of RIP1 did not affect viral entry or cell viability, but it did inhibit nuclear translocation of the IRF3 and NF-κB transcription factors. Also, activation of downstream signaling mediators (such as TBK1 and IRF7) was affected, and subsequent interferon and cytokine gene expression levels were abolished. Further, Necrostatin-1 (Nec-1)-an inhibitor of RIP1 kinase activity-dramatically increased baculoviral transgene expression in RIP1-silenced cells. Using baculovirus as a model system, this study presents an initial investigation of large numbers of human cell antiviral innate immune response factors against a "nonadaptive virus." In addition, our study has made baculovirus a more efficient gene transfer vector for some of the most frequently used mammalian cell systems.

  10. The heterotrimeric G protein Gβ1 interacts with the catalytic subunit of protein phosphatase 1 and modulates G protein-coupled receptor signaling in platelets.

    Science.gov (United States)

    Pradhan, Subhashree; Khatlani, Tanvir; Nairn, Angus C; Vijayan, K Vinod

    2017-08-11

    Thrombosis is caused by the activation of platelets at the site of ruptured atherosclerotic plaques. This activation involves engagement of G protein-coupled receptors (GPCR) on platelets that promote their aggregation. Although it is known that protein kinases and phosphatases modulate GPCR signaling, how serine/threonine phosphatases integrate with G protein signaling pathways is less understood. Because the subcellular localization and substrate specificity of the catalytic subunit of protein phosphatase 1 (PP1c) is dictated by PP1c-interacting proteins, here we sought to identify new PP1c interactors. GPCRs signal via the canonical heterotrimeric Gα and Gβγ subunits. Using a yeast two-hybrid screen, we discovered an interaction between PP1cα and the heterotrimeric G protein Gβ 1 subunit. Co-immunoprecipitation studies with epitope-tagged PP1c and Gβ 1 revealed that Gβ 1 interacts with the PP1c α, β, and γ1 isoforms. Purified PP1c bound to recombinant Gβ 1 -GST protein, and PP1c co-immunoprecipitated with Gβ 1 in unstimulated platelets. Thrombin stimulation of platelets induced the dissociation of the PP1c-Gβ 1 complex, which correlated with an association of PP1c with phospholipase C β3 (PLCβ3), along with a concomitant dephosphorylation of the inhibitory Ser 1105 residue in PLCβ3. siRNA-mediated depletion of GNB1 (encoding Gβ 1 ) in murine megakaryocytes reduced protease-activated receptor 4, activating peptide-induced soluble fibrinogen binding. Thrombin-induced aggregation was decreased in PP1cα -/- murine platelets and in human platelets treated with a small-molecule inhibitor of Gβγ. Finally, disruption of PP1c-Gβ 1 complexes with myristoylated Gβ 1 peptides containing the PP1c binding site moderately decreased thrombin-induced human platelet aggregation. These findings suggest that Gβ 1 protein enlists PP1c to modulate GPCR signaling in platelets.

  11. UBXN1 Interferes with Rig-I-like Receptor-Mediated Antiviral Immune Response by Targeting MAVS

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    Penghua Wang

    2013-04-01

    Full Text Available RNA viruses are sensed by RIG-I-like receptors (RLRs, which signal through a mitochondria-associated adaptor molecule, MAVS, resulting in systemic antiviral immune responses. Although RLR signaling is essential for limiting RNA virus replication, it must be stringently controlled to prevent damage from inflammation. We demonstrate here that among all tested UBX-domain-containing protein family members, UBXN1 exhibits the strongest inhibitory effect on RNA-virus-induced type I interferon response. UBXN1 potently inhibits RLR- and MAVS-induced, but not TLR3-, TLR4-, or DNA-virus-induced innate immune responses. Depletion of UBXN1 enhances virus-induced innate immune responses, including those resulting from RNA viruses such as vesicular stomatitis, Sendai, West Nile, and dengue virus infection, repressing viral replication. Following viral infection, UBXN1 is induced, binds to MAVS, interferes with intracellular MAVS oligomerization, and disrupts the MAVS/TRAF3/TRAF6 signalosome. These findings underscore a critical role of UBXN1 in the modulation of a major antiviral signaling pathway.

  12. Angiotensin II regulation of neuromodulation: downstream signaling mechanism from activation of mitogen-activated protein kinase.

    Science.gov (United States)

    Lu, D; Yang, H; Raizada, M K

    1996-12-01

    Angiotensin II (Ang II) stimulates expression of tyrosine hydroxylase and norepinephrine transporter genes in brain neurons; however, the signal-transduction mechanism is not clearly defined. This study was conducted to determine the involvement of the mitogen-activated protein (MAP) kinase signaling pathway in Ang II stimulation of these genes. MAP kinase was localized in the perinuclear region of the neuronal soma. Ang II caused activation of MAP kinase and its subsequent translocation from the cytoplasmic to nuclear compartment, both effects being mediated by AT1 receptor subtype. Ang II also stimulated SRE- and AP1-binding activities and fos gene expression and its translocation in a MAP kinase-dependent process. These observations are the first demonstration of a downstream signaling pathway involving MAP kinase in Ang II-mediated neuromodulation in noradrenergic neurons.

  13. The adapter protein, Grb10, is a positive regulator of vascular endothelial growth factor signaling.

    Science.gov (United States)

    Giorgetti-Peraldi, S; Murdaca, J; Mas, J C; Van Obberghen, E

    2001-07-05

    Vascular endothelial growth factor (VEGF) is an important regulator of vasculogenesis and angiogenesis. Activation of VEGF receptors leads to the recruitment of SH2 containing proteins which link the receptors to the activation of signaling pathways. Here we report that Grb10, an adapter protein of which the biological role remains unknown, is tyrosine phosphorylated in response to VEGF in endothelial cells (HUVEC) and in 293 cells expressing the VEGF receptor KDR. An intact SH2 domain is required for Grb10 tyrosine phosphorylation in response to VEGF, and this phosphorylation is mediated in part through the activation of Src. In HUVEC, VEGF increases Grb10 mRNA level. Expression of Grb10 in HUVEC or in KDR expressing 293 cells results in an increase in the amount and in the tyrosine phosphorylation of KDR. In 293 cells, this is correlated with the activation of signaling molecules, such as MAP kinase. By expressing mutants of Grb10, we found that the positive action of Grb10 is independent of its SH2 domain. Moreover, these Grb10 effects on KDR seem to be specific since Grb10 has no effect on the insulin receptor, and Grb2, another adapter protein, does not mimic the effect of Grb10 on KDR. In conclusion, we propose that VEGF up-regulates Grb10 level, which in turn increases KDR molecules, suggesting that Grb10 could be involved in a positive feedback loop in VEGF signaling.

  14. Raf kinase inhibitory protein: a signal transduction modulator and metastasis suppressor.

    Science.gov (United States)

    Granovsky, Alexey E; Rosner, Marsha Rich

    2008-04-01

    Cells have a multitude of controls to maintain their integrity and prevent random switching from one biological state to another. Raf Kinase Inhibitory Protein (RKIP), a member of the phosphatidylethanolamine binding protein (PEBP) family, is representative of a new class of modulators of signaling cascades that function to maintain the "yin yang" or balance of biological systems. RKIP inhibits MAP kinase (Raf-MEK-ERK), G protein-coupled receptor (GPCR) kinase and NFkappaB signaling cascades. Because RKIP targets different kinases dependent upon its state of phosphorylation, RKIP also acts to integrate crosstalk initiated by multiple environmental stimuli. Loss or depletion of RKIP results in disruption of the normal cellular stasis and can lead to chromosomal abnormalities and disease states such as cancer. Since RKIP and the PEBP family have been reviewed previously, the goal of this analysis is to provide an update and highlight some of the unique features of RKIP that make it a critical player in the regulation of cellular signaling processes.

  15. Regulation of hedgehog signaling by Myc-interacting zinc finger protein 1, Miz1.

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    Jiuyi Lu

    Full Text Available Smoothened (Smo mediated Hedgehog (Hh signaling plays an essential role in regulating embryonic development and postnatal tissue homeostasis. Aberrant activation of the Hh pathway contributes to the formation and progression of various cancers. In vertebrates, however, key regulatory mechanisms responsible for transducing signals from Smo to the nucleus remain to be delineated. Here, we report the identification of Myc-interacting Zinc finger protein 1 (Miz1 as a Smo and Gli2 binding protein that positively regulates Hh signaling. Overexpression of Miz1 increases Gli luciferase reporter activity, whereas knockdown of endogenous Miz1 has the opposite effect. Activation of Smo induces translocation of Miz1 to the primary cilia together with Smo and Gli2. Furthermore, Miz1 is localized to the nucleus upon Hh activation in a Smo-dependent manner, and loss of Miz1 prevents the nuclear translocation of Gli2. More importantly, silencing Miz1 expression inhibits cell proliferation in vitro and the growth of Hh-driven medulloblastoma tumors allografted in SCID mice. Taken together, these results identify Miz1 as a novel regulator in the Hh pathway that plays an important role in mediating Smo-dependent oncogenic signaling.

  16. Fragile X mental retardation protein regulates trans-synaptic signaling in Drosophila

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    Samuel H. Friedman

    2013-11-01

    Fragile X syndrome (FXS, the most common inherited determinant of intellectual disability and autism spectrum disorders, is caused by loss of the fragile X mental retardation 1 (FMR1 gene product (FMRP, an mRNA-binding translational repressor. A number of conserved FMRP targets have been identified in the well-characterized Drosophila FXS disease model, but FMRP is highly pleiotropic in function and the full spectrum of FMRP targets has yet to be revealed. In this study, screens for upregulated neural proteins in Drosophila fmr1 (dfmr1 null mutants reveal strong elevation of two synaptic heparan sulfate proteoglycans (HSPGs: GPI-anchored glypican Dally-like protein (Dlp and transmembrane Syndecan (Sdc. Our recent work has shown that Dlp and Sdc act as co-receptors regulating extracellular ligands upstream of intracellular signal transduction in multiple trans-synaptic pathways that drive synaptogenesis. Consistently, dfmr1 null synapses exhibit altered WNT signaling, with changes in both Wingless (Wg ligand abundance and downstream Frizzled-2 (Fz2 receptor C-terminal nuclear import. Similarly, a parallel anterograde signaling ligand, Jelly belly (Jeb, and downstream ERK phosphorylation (dpERK are depressed at dfmr1 null synapses. In contrast, the retrograde BMP ligand Glass bottom boat (Gbb and downstream signaling via phosphorylation of the transcription factor MAD (pMAD seem not to be affected. To determine whether HSPG upregulation is causative for synaptogenic defects, HSPGs were genetically reduced to control levels in the dfmr1 null background. HSPG correction restored both (1 Wg and Jeb trans-synaptic signaling, and (2 synaptic architecture and transmission strength back to wild-type levels. Taken together, these data suggest that FMRP negatively regulates HSPG co-receptors controlling trans-synaptic signaling during synaptogenesis, and that loss of this regulation causes synaptic structure and function defects characterizing the FXS disease state.

  17. Uncovering molecular structural mechanisms of signaling mediated by the prion protein

    Energy Technology Data Exchange (ETDEWEB)

    Romano, Sebastian A.; Linden, Rafael [Universidade Federal do Rio de Janeiro (IBCCF/UFRl), RJ (Brazil). Inst. de Biofisica Carlos Chagas Filho; Cordeiro, Yraima; Rocha e Lima, Luis M.T. da [Universidade Federal do Rio de Janeiro (FF/UFRl), RJ (Brazil). Fac. de Farmacia; Lopes, Marilene H. [Instituto Ludwig de Pesquisa de Cancer, Sao Paulo, SP (Brazil); Silva, Jerson L.; Foguel, Debora [Universidade Federal do Rio de Janeiro (IBqM/UFRl), RJ (Brazil). Inst. de Bioquimica Medica

    2009-07-01

    The glycosyl phosphatidylinositol (GPI) - anchored prion protein (PrP{sup c}), usually associated with neurodegenerative diseases, modulates various cellular responses and may scaffold multiprotein cell surface signaling complexes. Engagement of PrP{sup c} with the secretable cochaperone hop/STI 1 induces neurotrophic transmembrane signals through unknown molecular mechanisms. We addressed whether interaction of Pr P{sup c} and hop STI 1 entails structural rearrangements relevant for signaling. Circular dichroism and fluorescence spectroscopy showed that PrP{sup c}:hop/STI 1 interaction triggers loss of PrP helical structures, involving at least a perturbation of the Pr P{sup c}{sub 143-153} beta-helix. Novel SAXS models revealed a significant C-terminal compaction of hop/STI 1 when bound to PrP{sup c}. Differing from a recent dimeric model of human hop/STI 1, both size exclusion chromatography and SAXS data support a monomeric form of free murine hop/STI 1. Changes in the Pr P{sup c}{sub 143-153} beta-helix may engage the transmembrane signaling protein laminin receptor precursor and neural cell adhesion molecule, both of which bind that domain of Pr P{sup c}, and further ligands may be engaged by the tertiary structural changes of hop/STI 1. These reciprocal structural modifications indicate a versatile mechanism for signaling mediated by Pr P{sup c}:hop/STI 1 interaction, consistent with the hypothesis that Pr P{sup c} scaffolds multiprotein signaling complexes at the cell surface. (author)

  18. Calcium-Oxidant Signaling Network Regulates AMP-activated Protein Kinase (AMPK) Activation upon Matrix Deprivation*

    Science.gov (United States)

    Sundararaman, Ananthalakshmy; Amirtham, Usha; Rangarajan, Annapoorni

    2016-01-01

    The AMP-activated protein kinase (AMPK) has recently been implicated in anoikis resistance. However, the molecular mechanisms that activate AMPK upon matrix detachment remain unexplored. In this study, we show that AMPK activation is a rapid and sustained phenomenon upon matrix deprivation, whereas re-attachment to the matrix leads to its dephosphorylation and inactivation. Because matrix detachment leads to loss of integrin signaling, we investigated whether integrin signaling negatively regulates AMPK activation. However, modulation of focal adhesion kinase or Src, the major downstream components of integrin signaling, failed to cause a corresponding change in AMPK signaling. Further investigations revealed that the upstream AMPK kinases liver kinase B1 (LKB1) and Ca2+/calmodulin-dependent protein kinase kinase β (CaMKKβ) contribute to AMPK activation upon detachment. In LKB1-deficient cells, we found AMPK activation to be predominantly dependent on CaMKKβ. We observed no change in ATP levels under detached conditions at early time points suggesting that rapid AMPK activation upon detachment was not triggered by energy stress. We demonstrate that matrix deprivation leads to a spike in intracellular calcium as well as oxidant signaling, and both these intracellular messengers contribute to rapid AMPK activation upon detachment. We further show that endoplasmic reticulum calcium release-induced store-operated calcium entry contributes to intracellular calcium increase, leading to reactive oxygen species production, and AMPK activation. We additionally show that the LKB1/CaMKK-AMPK axis and intracellular calcium levels play a critical role in anchorage-independent cancer sphere formation. Thus, the Ca2+/reactive oxygen species-triggered LKB1/CaMKK-AMPK signaling cascade may provide a quick, adaptable switch to promote survival of metastasizing cancer cells. PMID:27226623

  19. The photosensor protein Ppr of Rhodocista centenaria is linked to the chemotaxis signalling pathway

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    Kiefer Dorothee

    2010-11-01

    Full Text Available Abstract Background Rhodocista centenaria is a phototrophic α-proteobacterium exhibiting a phototactic behaviour visible as colony movement on agar plates directed to red light. As many phototrophic purple bacteria R. centenaria possesses a soluble photoactive yellow protein (Pyp. It exists as a long fusion protein, designated Ppr, consisting of three domains, the Pyp domain, a putative bilin binding domain (Bbd and a histidine kinase domain (Pph. The Ppr protein is involved in the regulation of polyketide synthesis but it is still unclear, how this is connected to phototaxis and chemotaxis. Results To elucidate the possible role of Ppr and Pph in the chemotactic network we studied the interaction with chemotactic proteins in vitro as well as in vivo. Matrix-assisted coelution experiments were performed to study the possible communication of the different putative binding partners. The kinase domain of the Ppr protein was found to interact with the chemotactic linker protein CheW. The formation of this complex was clearly ATP-dependent. Further results indicated that the Pph histidine kinase domain and CheW may form a complex with the chemotactic kinase CheAY suggesting a role of Ppr in the chemotaxis signalling pathway. In addition, when Ppr or Pph were expressed in Escherichia coli, the chemotactic response of the cells was dramatically affected. Conclusions The Ppr protein of Rhodocista centenaria directly interacts with the chemotactic protein CheW. This suggests a role of the Ppr protein in the regulation of the chemotactic response in addition to its role in chalcone synthesis.

  20. Evolutionary gradient of predicted nuclear localization signals (NLS)-bearing proteins in genomes of family Planctomycetaceae.

    Science.gov (United States)

    Guo, Min; Yang, Ruifu; Huang, Chen; Liao, Qiwen; Fan, Guangyi; Sun, Chenghang; Lee, Simon Ming-Yuen

    2017-04-04

    The nuclear envelope is considered a key classification marker that distinguishes prokaryotes from eukaryotes. However, this marker does not apply to the family Planctomycetaceae, which has intracellular spaces divided by lipidic intracytoplasmic membranes (ICMs). Nuclear localization signal (NLS), a short stretch of amino acid sequence, destines to transport proteins from cytoplasm into nucleus, and is also associated with the development of nuclear envelope. We attempted to investigate the NLS motifs in Planctomycetaceae genomes to demonstrate the potential molecular transition in the development of intracellular membrane system. In this study, we identified NLS-like motifs that have the same amino acid compositions as experimentally identified NLSs in genomes of 11 representative species of family Planctomycetaceae. A total of 15 NLS types and 170 NLS-bearing proteins were detected in the 11 strains. To determine the molecular transformation, we compared NLS-bearing protein abundances in the 11 representative Planctomycetaceae genomes with them in genomes of 16 taxonomically varied microorganisms: nine bacteria, two archaea and five fungi. In the 27 strains, 29 NLS types and 1101 NLS-bearing proteins were identified, principal component analysis showed a significant transitional gradient from bacteria to Planctomycetaceae to fungi on their NLS-bearing protein abundance profiles. Then, we clustered the 993 non-redundant NLS-bearing proteins into 181 families and annotated their involved metabolic pathways. Afterwards, we aligned the ten types of NLS motifs from the 13 families containing NLS-bearing proteins among bacteria, Planctomycetaceae or fungi, considering their diversity, length and origin. A transition towards increased complexity from non-planctomycete bacteria to Planctomycetaceae to archaea and fungi was detected based on the complexity of the 10 types of NLS-like motifs in the 13 NLS-bearing proteins families. The results of this study reveal that

  1. Comparative analysis of the lambda-interferons IL-28A and IL-29 regarding their transcriptome and their antiviral properties against hepatitis C virus.

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    Julia Diegelmann

    Full Text Available BACKGROUND: Specific differences in signaling and antiviral properties between the different Lambda-interferons, a novel group of interferons composed of IL-28A, IL-28B and IL-29, are currently unknown. This is the first study comparatively investigating the transcriptome and the antiviral properties of the Lambda-interferons IL-28A and IL-29. METHODOLOGY/PRINCIPAL FINDINGS: Expression studies were performed by microarray analysis, quantitative PCR (qPCR, reporter gene assays and immunoluminometric assays. Signaling was analyzed by Western blot. HCV replication was measured in Huh-7 cells expressing subgenomic HCV replicon. All hepatic cell lines investigated as well as primary hepatocytes expressed both IFN-λ receptor subunits IL-10R2 and IFN-λR1. Both, IL-28A and IL-29 activated STAT1 signaling. As revealed by microarray analysis, similar genes were induced by both cytokines in Huh-7 cells (IL-28A: 117 genes; IL-29: 111 genes, many of them playing a role in antiviral immunity. However, only IL-28A was able to significantly down-regulate gene expression (n = 272 down-regulated genes. Both cytokines significantly decreased HCV replication in Huh-7 cells. In comparison to liver biopsies of patients with non-viral liver disease, liver biopsies of patients with HCV showed significantly increased mRNA expression of IL-28A and IL-29. Moreover, IL-28A serum protein levels were elevated in HCV patients. In a murine model of viral hepatitis, IL-28 expression was significantly increased. CONCLUSIONS/SIGNIFICANCE: IL-28A and IL-29 are up-regulated in HCV patients and are similarly effective in inducing antiviral genes and inhibiting HCV replication. In contrast to IL-29, IL-28A is a potent gene repressor. Both IFN-λs may have therapeutic potential in the treatment of chronic HCV.

  2. The TOPCONS web server for consensus prediction of membrane protein topology and signal peptides.

    Science.gov (United States)

    Tsirigos, Konstantinos D; Peters, Christoph; Shu, Nanjiang; Käll, Lukas; Elofsson, Arne

    2015-07-01

    TOPCONS (http://topcons.net/) is a widely used web server for consensus prediction of membrane protein topology. We hereby present a major update to the server, with some substantial improvements, including the following: (i) TOPCONS can now efficiently separate signal peptides from transmembrane regions. (ii) The server can now differentiate more successfully between globular and membrane proteins. (iii) The server now is even slightly faster, although a much larger database is used to generate the multiple sequence alignments. For most proteins, the final prediction is produced in a matter of seconds. (iv) The user-friendly interface is retained, with the additional feature of submitting batch files and accessing the server programmatically using standard interfaces, making it thus ideal for proteome-wide analyses. Indicatively, the user can now scan the entire human proteome in a few days. (v) For proteins with homology to a known 3D structure, the homology-inferred topology is also displayed. (vi) Finally, the combination of methods currently implemented achieves an overall increase in performance by 4% as compared to the currently available best-scoring methods and TOPCONS is the only method that can identify signal peptides and still maintain a state-of-the-art performance in topology predictions. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  3. Insulin resistance enhances the mitogen-activated protein kinase signaling pathway in ovarian granulosa cells.

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    Linghui Kong

    Full Text Available The ovary is the main regulator of female fertility. Granulosa cell dysfunction may be involved in various reproductive endocrine disorders. Here we investigated the effect of insulin resistance on the metabolism and function of ovarian granulosa cells, and dissected the functional status of the mitogen-activated protein kinase signaling pathway in these cells. Our data showed that dexamethasone-induced insulin resistance in mouse granulosa cells reduced insulin sensitivity, accompanied with an increase in phosphorylation of p44/42 mitogen-activated protein kinase. Furthermore, up-regulation of cytochrome P450 subfamily 17 and testosterone and down-regulation of progesterone were observed in insulin-resistant mouse granulosa cells. Inhibition of p44/42 mitogen-activated protein kinase after induction of insulin resistance in mouse granulosa cells decreased phosphorylation of p44/42 mitogen-activated protein kinase, downregulated cytochrome P450 subfamily 17 and lowered progesterone production. This insulin resistance cell model can successfully demonstrate certain mechanisms such as hyperandrogenism, which may inspire a new strategy for treating reproductive endocrine disorders by regulating cell signaling pathways.

  4. Cyclic nucleotide dependent dephosphorylation of regulator of G-protein signaling 18 in human platelets.

    LENUS (Irish Health Repository)

    Gegenbauer, Kristina

    2013-11-01

    Regulator of G-protein signaling 18 (RGS18) is a GTPase-activating protein that turns off Gq signaling in platelets. RGS18 is regulated by binding to the adaptor protein 14-3-3 via phosphorylated serine residues S49 and S218 on RGS18. In this study we confirm that thrombin, thromboxane A2, or ADP stimulate the interaction of RGS18 and 14-3-3 by increasing the phosphorylation of S49. Cyclic AMP- and cyclic GMP-dependent kinases (PKA, PKG) inhibit the interaction of RGS18 and 14-3-3 by phosphorylating S216. To understand the effect of S216 phosphorylation we studied the phosphorylation kinetics of S49, S216, and S218 using Phos-tag gels and phosphorylation site-specific antibodies in transfected cells and in platelets. Cyclic nucleotide-induced detachment of 14-3-3 from RGS18 coincides initially with double phosphorylation of S216 and S218. This is followed by dephosphorylation of S49 and S218. Dephosphorylation of S49 and S218 might be mediated by protein phosphatase 1 (PP1) which is linked to RGS18 by the regulatory subunit PPP1R9B (spinophilin). We conclude that PKA and PKG induced S216 phosphorylation triggers the dephosphorylation of the 14-3-3 binding sites of RGS18 in platelets.

  5. Biosynthetically directed fractional 13C labeling facilitates identification of Phe and Tyr aromatic signals in proteins

    International Nuclear Information System (INIS)

    Jacob, Jaison; Louis, John M.; Nesheiwat, Issa; Torchia, Dennis A.

    2002-01-01

    Analysis of 2D [ 13 C, 1 H]-HSQC spectra of biosynthetic fractionally 13 C labeled proteins is a reliable, straightforward means to obtain stereospecific assignments of Val and Leu methyl sites in proteins. Herein we show that the same fractionally labeled protein sample facilitates observation and identification of Phe and Tyr aromatic signals. This is the case, in part, because the fractional 13 C labeling yields aromatic rings in which some of the 13 C- 13 C J-couplings, present in uniformly labeled samples, are absent. Also, the number of homonuclear J-coupling partners differs for the δ-, ε- and ζ-carbons. This enabled us to vary their signal intensities in distinctly different ways by appropriately setting the 13 C constant-time period in 2D [ 13 C, 1 H]-HSQC spectra. We illustrate the application of this approach to an 18 kDa protein, c-VIAF, a modulator of apoptosis. In addition, we show that cancellation of the aromatic 13 C CSA and 13 C- 1 H dipolar interactions can be fruitfully utilized in the case of the fractionally labeled sample to obtain high resolution 13 C constant-time spectra with good sensitivity

  6. ZNF383, a novel KRAB-containing zinc finger protein, suppresses MAPK signaling pathway

    International Nuclear Information System (INIS)

    Cao Lei; Wang Zhi; Zhu Chuanbing; Zhao Yulian; Yuan Wuzhou; Li Jing; Wang Yuequn; Ying Zhaochu; Li Yongqing; Yu Weishi; Wu Xiushan; Liu Mingyao

    2005-01-01

    Mitogen-activated protein kinases (MAPKs) are major components of pathways controlling embryogenesis, cell differentiation, cell proliferation, and cell death. One of the most explored functions of MAPK signaling is the regulation of gene expression by direct or indirect phosphorylation and subsequent activation of transcription factors. In this article, we isolated a novel KRAB-related zinc finger gene named ZNF383 from an early embryo heart cDNA library. The cDNA of ZNF383 is 2220 bp, encoding a protein of 475 amino acids. The protein is conserved in evolution across different species. Northern blot analysis indicates that a 2.2 kb transcript specific for ZNF383 is detected in most of the examined human adult and embryonic tissues with a higher level in skeletal muscle. In COS-7 cells, ZNF383 protein is localized to nucleus and cytoplasm. ZNF383 is a transcription repressor when fused to Gal-4 DNA-binding domain and cotransfected with VP-16. Deletion analysis indicates that the KRAB box of ZNF383 is responsible for the transcriptional repressor activity. Overexpression of ZNF383 in cells inhibits the transcriptional activities of AP-1 and SRE, suggesting that ZNF383 may act as a negative regulator in MAPK-mediated signaling pathways

  7. Dopamine D2L receptor-interacting proteins regulate dopaminergic signaling

    Directory of Open Access Journals (Sweden)

    Norifumi Shioda

    2017-10-01

    Full Text Available Dopamine receptor family proteins include seven transmembrane and trimeric GTP-binding protein-coupled receptors (GPCRs. Among them, the dopamine D2 receptor (D2R is most extensively studied. All clinically used antipsychotic drugs serve as D2R antagonists in the mesolimbic dopamine system, and their ability to block D2R signaling is positively correlated with antipsychotic efficiency. Human genetic studies also show a significant association of DRD2 polymorphisms with disorders including schizophrenia and Parkinson's disease. D2R exists as two alternatively spliced isoforms, the long isoform (D2LR and the short isoform (D2SR, which differ in a 29-amino acid (AA insert in the third cytoplasmic loop. Importantly, previous reports demonstrate functional diversity between the two isoforms in humans. In this review, we focus on binding proteins that specifically interact with the D2LR 29AA insert. We discuss how D2R activities are mediated not only by heterotrimeric G proteins but by D2LR-interacting proteins, which in part regulate diverse D2R activities. Keywords: Dopamine D2L receptor, Antipsychotic drugs, DRD2 polymorphisms, Alternatively spliced isoforms, D2LR-interacting proteins

  8. Sequencing and Characterization of Novel PII Signaling Protein Gene in Microalga Haematococcus pluvialis

    Directory of Open Access Journals (Sweden)

    Ruijuan Ma

    2017-10-01

    Full Text Available The PII signaling protein is a key protein for controlling nitrogen assimilatory reactions in most organisms, but little information is reported on PII proteins of green microalga Haematococcus pluvialis. Since H. pluvialis cells can produce a large amount of astaxanthin upon nitrogen starvation, its PII protein may represent an important factor on elevated production of Haematococcus astaxanthin. This study identified and isolated the coding gene (HpGLB1 from this microalga. The full-length of HpGLB1 was 1222 bp, including 621 bp coding sequence (CDS, 103 bp 5′ untranslated region (5′ UTR, and 498 bp 3′ untranslated region (3′ UTR. The CDS could encode a protein with 206 amino acids (HpPII. Its calculated molecular weight (Mw was 22.4 kDa and the theoretical isoelectric point was 9.53. When H. pluvialis cells were exposed to nitrogen starvation, the HpGLB1 expression was increased 2.46 times in 48 h, concomitant with the raise of astaxanthin content. This study also used phylogenetic analysis to prove that HpPII was homogeneous to the PII proteins of other green microalgae. The results formed a fundamental basis for the future study on HpPII, for its potential physiological function in Haematococcus astaxanthin biosysthesis.

  9. G Protein and β-arrestin signaling bias at the ghrelin receptor.

    Science.gov (United States)

    Evron, Tama; Peterson, Sean M; Urs, Nikhil M; Bai, Yushi; Rochelle, Lauren K; Caron, Marc G; Barak, Larry S

    2014-11-28

    The G protein-coupled ghrelin receptor GHSR1a is a potential pharmacological target for treating obesity and addiction because of the critical role ghrelin plays in energy homeostasis and dopamine-dependent reward. GHSR1a enhances growth hormone release, appetite, and dopamine signaling through G(q/11), G(i/o), and G(12/13) as well as β-arrestin-based scaffolds. However, the contribution of individual G protein and β-arrestin pathways to the diverse physiological responses mediated by ghrelin remains unknown. To characterize whether a signaling bias occurs for GHSR1a, we investigated ghrelin signaling in a number of cell-based assays, including Ca(2+) mobilization, serum response factor response element, stress fiber formation, ERK1/2 phosphorylation, and β-arrestin translocation, utilizing intracellular second loop and C-tail mutants of GHSR1a. We observed that GHSR1a and β-arrestin rapidly form metastable plasma membrane complexes following exposure to an agonist, but replacement of the GHSR1a C-tail by the tail of the vasopressin 2 receptor greatly stabilizes them, producing complexes observable on the plasma membrane and also in endocytic vesicles. Mutations of the contiguous conserved amino acids Pro-148 and Leu-149 in the GHSR1a intracellular second loop generate receptors with a strong bias to G protein and β-arrestin, respectively, supporting a role for conformation-dependent signaling bias in the wild-type receptor. Our results demonstrate more balance in GHSR1a-mediated ERK signaling from G proteins and β-arrestin but uncover an important role for β-arrestin in RhoA activation and stress fiber formation. These findings suggest an avenue for modulating drug abuse-associated changes in synaptic plasticity via GHSR1a and indicate the development of GHSR1a-biased ligands as a promising strategy for selectively targeting downstream signaling events. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. The Role of Unfolded Protein Response and Mitogen-Activated Protein Kinase Signaling in Neurodegenerative Diseases with Special Focus on Prion Diseases

    Directory of Open Access Journals (Sweden)

    Lifeng Yang

    2017-05-01

    Full Text Available Prion diseases are neurodegenerative pathologies characterized by the accumulation of a protease-resistant form of the cellular prion protein named prion protein scrapie (PrPSc in the brain. PrPSc accumulation in the endoplasmic reticulum (ER result in a dysregulated calcium (Ca2+ homeostasis and subsequent initiation of unfolded protein response (UPR leading to neuronal dysfunction and apoptosis. The molecular mechanisms for the transition between adaptation to ER stress and ER stress-induced apoptosis are still unclear. Mitogen-activated protein kinases (MAPKs are serine/threonine protein kinases that rule the signaling of many extracellular stimuli from plasma membrane to the nucleus. However the identification of numerous points of cross talk between the UPR and MAPK signaling pathways may contribute to our understanding of the consequences of ER stress in prion diseases. Indeed the MAPK signaling network is known to regulate cell cycle progression and cell survival or death responses following a variety of stresses including misfolded protein response stress. In this article, we review the UPR signaling in prion diseases and discuss the triad of MAPK signaling pathways. We also describe the role played by MAPK signaling cascades in Alzheimer’s (AD and Parkinson’s disease (PD. We will also overview the mechanisms of cell death and the role of MAPK signaling in prion disease progression and highlight potential avenues for therapeutic intervention.

  11. Non Linear Programming (NLP) formulation for quantitative modeling of protein signal transduction pathways.

    Science.gov (United States)

    Mitsos, Alexander; Melas, Ioannis N; Morris, Melody K; Saez-Rodriguez, Julio; Lauffenburger, Douglas A; Alexopoulos, Leonidas G

    2012-01-01

    Modeling of signal transduction pathways plays a major role in understanding cells' function and predicting cellular response. Mathematical formalisms based on a logic formalism are relatively simple but can describe how signals propagate from one protein to the next and have led to the construction of models that simulate the cells response to environmental or other perturbations. Constrained fuzzy logic was recently introduced to train models to cell specific data to result in quantitative pathway models of the specific cellular behavior. There are two major issues in this pathway optimization: i) excessive CPU time requirements and ii) loosely constrained optimization problem due to lack of data with respect to large signaling pathways. Herein, we address both issues: the former by reformulating the pathway optimization as a regular nonlinear optimization problem; and the latter by enhanced algorithms to pre/post-process the signaling network to remove parts that cannot be identified given the experimental conditions. As a case study, we tackle the construction of cell type specific pathways in normal and transformed hepatocytes using medium and large-scale functional phosphoproteomic datasets. The proposed Non Linear Programming (NLP) formulation allows for fast optimization of signaling topologies by combining the versatile nature of logic modeling with state of the art optimization algorithms.

  12. Non Linear Programming (NLP formulation for quantitative modeling of protein signal transduction pathways.

    Directory of Open Access Journals (Sweden)

    Alexander Mitsos

    Full Text Available Modeling of signal transduction pathways plays a major role in understanding cells' function and predicting cellular response. Mathematical formalisms based on a logic formalism are relatively simple but can describe how signals propagate from one protein to the next and have led to the construction of models that simulate the cells response to environmental or other perturbations. Constrained fuzzy logic was recently introduced to train models to cell specific data to result in quantitative pathway models of the specific cellular behavior. There are two major issues in this pathway optimization: i excessive CPU time requirements and ii loosely constrained optimization problem due to lack of data with respect to large signaling pathways. Herein, we address both issues: the former by reformulating the pathway optimization as a regular nonlinear optimization problem; and the latter by enhanced algorithms to pre/post-process the signaling network to remove parts that cannot be identified given the experimental conditions. As a case study, we tackle the construction of cell type specific pathways in normal and transformed hepatocytes using medium and large-scale functional phosphoproteomic datasets. The proposed Non Linear Programming (NLP formulation allows for fast optimization of signaling topologies by combining the versatile nature of logic modeling with state of the art optimization algorithms.

  13. DRAGON, a GPI-anchored membrane protein, inhibits BMP signaling in C2C12 myoblasts.

    Science.gov (United States)

    Kanomata, Kazuhiro; Kokabu, Shoichiro; Nojima, Junya; Fukuda, Toru; Katagiri, Takenobu

    2009-06-01

    Bone morphogenetic proteins (BMPs) induce osteoblastic differentiation of myoblasts via binding to cell surface receptors. Repulsive guidance molecules (RGMs) have been identified as BMP co-receptors. We report here that DRAGON/RGMb, a member of the RGM family, suppressed BMP signaling in C2C12 myoblasts via a novel mechanism. All RGMs were expressed in C2C12 cells that were differentiated into myocytes and osteoblastic cells, but RGMc was not detected in immature cells. In C2C12 cells, only DRAGON suppressed ALP and Id1 promoter activities induced by BMP-4 or by constitutively activated BMP type I receptors. This inhibition by DRAGON was dependent on the secretory form of the von Willbrand factor type D domain. DRAGON even suppressed BMP signaling induced by constitutively activated Smad1. Over-expression of neogenin did not alter the inhibitory capacity of DRAGON. Taken together, these findings indicate that DRAGON may be an inhibitor of BMP signaling in C2C12 myoblasts. We also suggest that a novel molecule(s) expressed on the cell membrane may mediate the signal transduction of DRAGON in order to suppress BMP signaling in C2C12 myoblasts.

  14. Role of adenosine 5'-monophosphate-activated protein kinase subunits in skeletal muscle mammalian target of rapamycin signaling

    DEFF Research Database (Denmark)

    Deshmukh, Atul S.; Treebak, Jonas Thue; Long, Yun Chau

    2008-01-01

    AMP-activated protein kinase (AMPK) is an important energy-sensing protein in skeletal muscle. Mammalian target of rapamycin (mTOR) mediates translation initiation and protein synthesis through ribosomal S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1). AMPK...... activation reduces muscle protein synthesis by down-regulating mTOR signaling, whereas insulin mediates mTOR signaling via Akt activation. We hypothesized that AMPK-mediated inhibitory effects on mTOR signaling depend on catalytic alpha2 and regulatory gamma3 subunits. Extensor digitorum longus muscle from...... (Thr37/46) (P mTOR targets, suggesting mTOR signaling is blocked by prior AMPK activation. The AICAR-induced inhibition was partly rescued...

  15. Transfer functions for protein signal transduction: application to a model of striatal neural plasticity.

    Directory of Open Access Journals (Sweden)

    Gabriele Scheler

    Full Text Available We present a novel formulation for biochemical reaction networks in the context of protein signal transduction. The model consists of input-output transfer functions, which are derived from differential equations, using stable equilibria. We select a set of "source" species, which are interpreted as input signals. Signals are transmitted to all other species in the system (the "target" species with a specific delay and with a specific transmission strength. The delay is computed as the maximal reaction time until a stable equilibrium for the target species is reached, in the context of all other reactions in the system. The transmission strength is the concentration change of the target species. The computed input-output transfer functions can be stored in a matrix, fitted with parameters, and even recalled to build dynamical models on the basis of state changes. By separating the temporal and the magnitudinal domain we can greatly simplify the computational model, circumventing typical problems of complex dynamical systems. The transfer function transformation of biochemical reaction systems can be applied to mass-action kinetic models of signal transduction. The paper shows that this approach yields significant novel insights while remaining a fully testable and executable dynamical model for signal transduction. In particular we can deconstruct the complex system into local transfer functions between individual species. As an example, we examine modularity and signal integration using a published model of striatal neural plasticity. The modularizations that emerge correspond to a known biological distinction between calcium-dependent and cAMP-dependent pathways. Remarkably, we found that overall interconnectedness depends on the magnitude of inputs, with higher connectivity at low input concentrations and significant modularization at moderate to high input concentrations. This general result, which directly follows from the properties of

  16. Characterization of wise protein and its molecular mechanism to interact with both Wnt and BMP signals.

    Science.gov (United States)

    Lintern, Katherine B; Guidato, Sonia; Rowe, Alison; Saldanha, José W; Itasaki, Nobue

    2009-08-21

    Cross-talk of BMP and Wnt signaling pathways has been implicated in many aspects of biological events during embryogenesis and in adulthood. A secreted protein Wise and its orthologs (Sostdc1, USAG-1, and Ectodin) have been shown to modulate Wnt signaling and also inhibit BMP signals. Modulation of Wnt signaling activity by Wise is brought about by an interaction with the Wnt co-receptor LRP6, whereas BMP inhibition is by binding to BMP ligands. Here we have investigated the mode of action of Wise on Wnt and BMP signals. It was found that Wise binds LRP6 through one of three loops formed by the cystine knot. The Wise deletion construct lacking the LRP6-interacting loop domain nevertheless binds BMP4 and inhibits BMP signals. Moreover, BMP4 does not interfere with Wise-LRP6 binding, suggesting separate domains for the physical interaction. Functional assays also show that the ability of Wise to block Wnt1 activity through LRP6 is not impeded by BMP4. In contrast, the ability of Wise to inhibit BMP4 is prevented by additional LRP6, implying a preference of Wise in binding LRP6 over BMP4. In addition to the interaction of Wise with BMP4 and LRP6, the molecular characteristics of Wise, such as glycosylation and association with heparan sulfate proteoglycans on the cell surface, are suggested. This study helps to understand the multiple functions of Wise at the molecular level and suggests a possible role for Wise in balancing Wnt and BMP signals.

  17. High pressure modulated transport and signaling functions of membrane proteins in models and in vivo

    International Nuclear Information System (INIS)

    Vogel, R F; Linke, K; Teichert, H; Ehrmann, M A

    2008-01-01

    Cellular membranes serve in the separation of compartments, recognition of the environment, selective transport and signal transduction. Membrane lipids and membrane proteins play distinct roles in these processes, which are affected by environmental chemical (e. g. pH) or physical (e. g. pressure and temperature) changes. High hydrostatic pressure (HHP) affects fluidity and integrity of bacterial membranes instantly during the ramp, resulting in a loss of membrane potential and vital membrane protein functions. We have used the multiple drug transporter LmrA from Lactococcus lactis and ToxR, a membrane protein sensor from Photobacterium profundum, a deep-sea bacterium, and Vibrio cholerae to study membrane protein interaction and functionality in proteolioposomes and by the use of in vivo reporter systems, respectively. Both proteins require dimerization in the phospholipid bilayer for their functionality, which was favoured in the liquid crystalline lipid phase with ToxR and LmrA. Whereas LmrA, which resides in liposomes consisting of DMPC, DMPC/cholesterol or natural lipids, lost its ATPase activity above 20 or 40 MPa, it maintained its active dimeric structure in DOPC/DPPC/cholesterol liposomes up to 120 MPa. By using a specific indicator strain in which the dimerisation of ToxR initiates the transcription of lacZ it was demonstrated, that the amino acid sequence of the transmembrane domain influences HHP stability of ToxR dimerization in vivo. Thus, both the lipid structure and the nature of the protein affect membrane protein interaction. It is suggested that the protein structure determines basic functionality, e.g. principle ability or kinetics to dimerize to a functional complex, while the lipid environment modulates this property

  18. High pressure modulated transport and signaling functions of membrane proteins in models and in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, R F; Linke, K; Teichert, H; Ehrmann, M A [Technische Universitaet Muenchen, Technische Mikrobiologie, Weihenstephaner Steig 16, 85350 Freising (Germany)], E-mail: rudi.vogel@wzw.tum.de

    2008-07-15

    Cellular membranes serve in the separation of compartments, recognition of the environment, selective transport and signal transduction. Membrane lipids and membrane proteins play distinct roles in these processes, which are affected by environmental chemical (e. g. pH) or physical (e. g. pressure and temperature) changes. High hydrostatic pressure (HHP) affects fluidity and integrity of bacterial membranes instantly during the ramp, resulting in a loss of membrane potential and vital membrane protein functions. We have used the multiple drug transporter LmrA from Lactococcus lactis and ToxR, a membrane protein sensor from Photobacterium profundum, a deep-sea bacterium, and Vibrio cholerae to study membrane protein interaction and functionality in proteolioposomes and by the use of in vivo reporter systems, respectively. Both proteins require dimerization in the phospholipid bilayer for their functionality, which was favoured in the liquid crystalline lipid phase with ToxR and LmrA. Whereas LmrA, which resides in liposomes consisting of DMPC, DMPC/cholesterol or natural lipids, lost its ATPase activity above 20 or 40 MPa, it maintained its active dimeric structure in DOPC/DPPC/cholesterol liposomes up to 120 MPa. By using a specific indicator strain in which the dimerisation of ToxR initiates the transcription of lacZ it was demonstrated, that the amino acid sequence of the transmembrane domain influences HHP stability of ToxR dimerization in vivo. Thus, both the lipid structure and the nature of the protein affect membrane protein interaction. It is suggested that the protein structure determines basic functionality, e.g. principle ability or kinetics to dimerize to a functional complex, while the lipid environment modulates this property.

  19. High pressure modulated transport and signaling functions of membrane proteins in models and in vivo

    Science.gov (United States)

    Vogel, R. F.; Linke, K.; Teichert, H.; Ehrmann, M. A.

    2008-07-01

    Cellular membranes serve in the separation of compartments, recognition of the environment, selective transport and signal transduction. Membrane lipids and membrane proteins play distinct roles in these processes, which are affected by environmental chemical (e. g. pH) or physical (e. g. pressure and temperature) changes. High hydrostatic pressure (HHP) affects fluidity and integrity of bacterial membranes instantly during the ramp, resulting in a loss of membrane potential and vital membrane protein functions. We have used the multiple drug transporter LmrA from Lactococcus lactis and ToxR, a membrane protein sensor from Photobacterium profundum, a deep-sea bacterium, and Vibrio cholerae to study membrane protein interaction and functionality in proteolioposomes and by the use of in vivo reporter systems, respectively. Both proteins require dimerization in the phospholipid bilayer for their functionality, which was favoured in the liquid crystalline lipid phase with ToxR and LmrA. Whereas LmrA, which resides in liposomes consisting of DMPC, DMPC/cholesterol or natural lipids, lost its ATPase activity above 20 or 40 MPa, it maintained its active dimeric structure in DOPC/DPPC/cholesterol liposomes up to 120 MPa. By using a specific indicator strain in which the dimerisation of ToxR initiates the transcription of lacZ it was demonstrated, that the amino acid sequence of the transmembrane domain influences HHP stability of ToxR dimerization in vivo. Thus, both the lipid structure and the nature of the protein affect membrane protein interaction. It is suggested that the protein structure determines basic functionality, e.g. principle ability or kinetics to dimerize to a functional complex, while the lipid environment modulates this property.

  20. PKA RIα/A-kinase anchoring proteins 10 signaling pathway and the prognosis of colorectal cancer.

    Science.gov (United States)

    Wang, Mojin; Li, Yuan; Wang, Rui; Wang, Ziqiang; Chen, Keling; Zhou, Bin; Zhou, Zongguang; Sun, Xiaofeng

    2015-03-01

    Previously study showed that the loss of the control of cAMP-dependent protein kinase A RIα (PKA RIα)/ A-kinase anchoring proteins 10 (AKAP10) signaling pathway initiate dysregulation of cellular healthy physiology leading to tumorigenesis. The aim of this study was to investigate the role of PKA RIα/AKAP10 signaling pathway in colorectal cancer (CRC). The AKAP10 expression at the mRNA and protein level have been analyzed in colon cancer cell lines, primary CRCs and matched normal mucosa samples, and compared in accordance with specific clinicopathological features of CRC. The correlation between expression of AKAP10 and PKA RIα were also analyzed. Compared with HCT116 and SW480 cells, the AKAP10 was significantly upregulated in the colon cell line KM12C and its metastatic counterparts, KM12SM and KM12L4A. Moreover, the KM12SM and KM12L4A having high metastatic potentials displayed the elevated levels of AKAP10 compared with KM12C having poor metastatic potential. A notably higher level of AKAP10 expression was found in CRC tissues at both mRNA and protein levels. Increased expression of AKAP10 in CRC patients was positively associated with the depth of invasion and the grade of differentiation. Univariate survival analysis showed that the increased expression of AKAP10 was related to poorer survival. Cox multivariate regression analysis confirmed that AKAP10 was an independent predictor of the overall survival of CRC patients. PKA RIα mRNA was also expressed at high levels in CRC. The correlation coefficient between mRNA expression of AKAP10 and PKA RIα in CRC was 0.417. AKAP10 mRNA overexpression was correlated significantly with PKA RIα. Our data indicated that PKA RIα/AKAP10 signaling pathway is associated with the progression and prognosis of CRC. © 2014 Journal of Gastroenterology and Hepatology Foundation and Wiley Publishing Asia Pty Ltd.

  1. Distinct Phosphorylation Clusters Determine the Signaling Outcome of Free Fatty Acid Receptor 4/G Protein-Coupled Receptor 120

    DEFF Research Database (Denmark)

    Prihandoko, Rudi; Alvarez-Curto, Elisa; Hudson, Brian D

    2016-01-01

    of these phosphoacceptor sites to alanine completely prevented phosphorylation of mFFA4 but did not limit receptor coupling to extracellular signal regulated protein kinase 1 and 2 (ERK1/2) activation. Rather, an inhibitor of Gq/11proteins completely prevented receptor signaling to ERK1/2. By contrast, the recruitment...... activation. These unique observations define differential effects on signaling mediated by phosphorylation at distinct locations. This hallmark feature supports the possibility that the signaling outcome of mFFA4 activation can be determined by the pattern of phosphorylation (phosphorylation barcode...

  2. EGF-CFC proteins are essential coreceptors for the TGF-β signals Vg1 and GDF1

    Science.gov (United States)

    Cheng, Simon K.; Olale, Felix; Bennett, James T.; Brivanlou, Ali H.; Schier, Alexander F.

    2003-01-01

    The TGF-β signals Nodal, Activin, GDF1, and Vg1 have been implicated in mesoderm induction and left-right patterning. Nodal and Activin both activate Activin receptors, but only Nodal requires EGF-CFC coreceptors for signaling. We report that Vg1 and GDF1 signaling in zebrafish also depends on EGF-CFC proteins, but not on Nodal signals. Correspondingly, we find that in Xenopus Vg1 and GDF1 bind to and signal through Activin receptors only in the presence of EGF-CFC proteins. These results establish that multiple TGF-β signals converge on Activin receptor/EGF-CFC complexes and suggest a more widespread requirement for coreceptors in TGF-β signaling than anticipated previously. PMID:12514096

  3. Systematic differences in signal emitting and receiving revealed by PageRank analysis of a human protein interactome.

    Directory of Open Access Journals (Sweden)

    Donglei Du

    Full Text Available Most protein PageRank studies do not use signal flow direction information in protein interactions because this information was not readily available in large protein databases until recently. Therefore, four questions have yet to be answered: A What is the general difference between signal emitting and receiving in a protein interactome? B Which proteins are among the top ranked in directional ranking? C Are high ranked proteins more evolutionarily conserved than low ranked ones? D Do proteins with similar ranking tend to have similar subcellular locations? In this study, we address these questions using the forward, reverse, and non-directional PageRank approaches to rank an information-directional network of human proteins and study their evolutionary conservation. The forward ranking gives credit to information receivers, reverse ranking to information emitters, and non-directional ranking mainly to the number of interactions. The protein lists generated by the forward and non-directional rankings are highly correlated, but those by the reverse and non-directional rankings are not. The results suggest that the signal emitting/receiving system is characterized by key-emittings and relatively even receivings in the human protein interactome. Signaling pathway proteins are frequent in top ranked ones. Eight proteins are both informational top emitters and top receivers. Top ranked proteins, except a few species-related novel-function ones, are evolutionarily well conserved. Protein-subunit ranking position reflects subunit function. These results demonstrate the usefulness of different PageRank approaches in characterizing protein networks and provide insights to protein interaction in the cell.

  4. Systematic differences in signal emitting and receiving revealed by PageRank analysis of a human protein interactome.

    Science.gov (United States)

    Du, Donglei; Lee, Connie F; Li, Xiu-Qing

    2012-01-01

    Most protein PageRank studies do not use signal flow direction information in protein interactions because this information was not readily available in large protein databases until recently. Therefore, four questions have yet to be answered: A) What is the general difference between signal emitting and receiving in a protein interactome? B) Which proteins are among the top ranked in directional ranking? C) Are high ranked proteins more evolutionarily conserved than low ranked ones? D) Do proteins with similar ranking tend to have similar subcellular locations? In this study, we address these questions using the forward, reverse, and non-directional PageRank approaches to rank an information-directional network of human proteins and study their evolutionary conservation. The forward ranking gives credit to information receivers, reverse ranking to information emitters, and non-directional ranking mainly to the number of interactions. The protein lists generated by the forward and non-directional rankings are highly correlated, but those by the reverse and non-directional rankings are not. The results suggest that the signal emitting/receiving system is characterized by key-emittings and relatively even receivings in the human protein interactome. Signaling pathway proteins are frequent in top ranked ones. Eight proteins are both informational top emitters and top receivers. Top ranked proteins, except a few species-related novel-function ones, are evolutionarily well conserved. Protein-subunit ranking position reflects subunit function. These results demonstrate the usefulness of different PageRank approaches in characterizing protein networks and provide insights to protein interaction in the cell.

  5. The Zn Finger protein Iguana impacts Hedgehog signaling by promoting ciliogenesis

    Science.gov (United States)

    Glazer, Andrew; Wilkinson, Alex; Backer, Chelsea B.; Lapan, Sylvain; Gutzman, Jennifer H.; Cheeseman, Iain M.; Reddien, Peter W.

    2009-01-01

    Hedgehog signaling is critical for metazoan development and requires cilia for pathway activity. The gene iguana was discovered in zebrafish as required for Hedgehog signaling, and encodes a novel Zn finger protein. Planarians are flatworms with robust regenerative capacities and that utilize epidermal cilia for locomotion. RNA interference of Smed-iguana in the planarian S. mediterranea caused cilia loss and failure to regenerate new cilia, but did not cause defects similar to those observed in hedgehog(RNAi) animals. Smed-iguana gene expression was also similar in pattern to the expression of multiple other ciliogenesis genes, but was not required for expression of these ciliogenesis genes. iguana-defective zebrafish had too few motile cilia in pronephric ducts and in Kupffer's vesicle. Kupffer's vesicle promotes left-right asymmetry and iguana mutant embryos had left-right asymmetry defects. Finally, human Iguana proteins (dZIP1 and dZIP1L) localize to the basal bodies of primary cilia and, together, are required for primary cilia formation. Our results indicate that a critical and broadly conserved function for Iguana is in ciliogenesis and that this function has come to be required for Hedgehog signaling in vertebrates. PMID:19852954

  6. A macrophage inflammatory protein homolog encoded by guinea pig cytomegalovirus signals via CC chemokine receptor 1

    International Nuclear Information System (INIS)

    Penfold, Mark; Miao Zhenhua; Wang Yu; Haggerty, Shannon; Schleiss, Mark R.

    2003-01-01

    Cytomegaloviruses encode homologs of cellular immune effector proteins, including chemokines (CKs) and CK receptor-like G protein-coupled receptors (GPCRs). Sequence of the guinea pig cytomegalovirus (GPCMV) genome identified an open reading frame (ORF) which predicted a 101 amino acid (aa) protein with homology to the macrophage inflammatory protein (MIP) subfamily of CC (β) CKs, designated GPCMV-MIP. To assess functionality of this CK, recombinant GPCMV-MIP was expressed in HEK293 cells and assayed for its ability to bind to and functionally interact with a variety of GPCRs. Specific signaling was observed with the hCCR1 receptor, which could be blocked with hMIP -1α in competition experiments. Migration assays revealed that GPCMV-MIP was able to induce chemotaxis in hCCR1-L1.2 cells. Antisera raised against a GST-MIP fusion protein immunoprecipitated species of ∼12 and 10 kDa from GPCMV-inoculated tissue culture lysates, and convalescent antiserum from GPCMV-infected animals was immunoreactive with GST-MIP by ELISA assay. These results represent the first substantive in vitro characterization of a functional CC CK encoded by a cytomegalovirus

  7. Herbaspirillum seropedicae signal transduction protein PII is structurally similar to the enteric GlnK.

    Science.gov (United States)

    Machado Benelli, Elaine; Buck, Martin; Polikarpov, Igor; Maltempi de Souza, Emanuel; Cruz, Leonardo M; Pedrosa, Fábio O

    2002-07-01

    PII-like proteins are signal transduction proteins found in bacteria, archaea and eukaryotes. They mediate a variety of cellular responses. A second PII-like protein, called GlnK, has been found in several organisms. In the diazotroph Herbaspirillum seropedicae, PII protein is involved in sensing nitrogen levels and controlling nitrogen fixation genes. In this work, the crystal structure of the unliganded H. seropedicae PII was solved by X-ray diffraction. H. seropedicae PII has a Gly residue, Gly108 preceding Pro109 and the main-chain forms a beta turn. The glycine at position 108 allows a bend in the C-terminal main-chain, thereby modifying the surface of the cleft between monomers and potentially changing function. The structure suggests that the C-terminal region of PII proteins may be involved in specificity of function, and nonenteric diazotrophs are found to have the C-terminal consensus XGXDAX(107-112). We are also proposing binding sites for ATP and 2-oxoglutarate based on the structural alignment of PII with PII-ATP/GlnK-ATP, 5-carboxymethyl-2-hydroxymuconate isomerase and 4-oxalocrotonate tautomerase bound to the inhibitor 2-oxo-3-pentynoate.

  8. GIT1/βPIX signaling proteins and PAK1 kinase regulate microtubule nucleation.

    Science.gov (United States)

    Černohorská, Markéta; Sulimenko, Vadym; Hájková, Zuzana; Sulimenko, Tetyana; Sládková, Vladimíra; Vinopal, Stanislav; Dráberová, Eduarda; Dráber, Pavel

    2016-06-01

    Microtubule nucleation from γ-tubulin complexes, located at the centrosome, is an essential step in the formation of the microtubule cytoskeleton. However, the signaling mechanisms that regulate microtubule nucleation in interphase cells are largely unknown. In this study, we report that γ-tubulin is in complexes containing G protein-coupled receptor kinase-interacting protein 1 (GIT1), p21-activated kinase interacting exchange factor (βPIX), and p21 protein (Cdc42/Rac)-activated kinase 1 (PAK1) in various cell lines. Immunofluorescence microscopy revealed association of GIT1, βPIX and activated PAK1 with centrosomes. Microtubule regrowth experiments showed that depletion of βPIX stimulated microtubule nucleation, while depletion of GIT1 or PAK1 resulted in decreased nucleation in the interphase cells. These data were confirmed for GIT1 and βPIX by phenotypic rescue experiments, and counting of new microtubules emanating from centrosomes during the microtubule regrowth. The importance of PAK1 for microtubule nucleation was corroborated by the inhibition of its kinase activity with IPA-3 inhibitor. GIT1 with PAK1 thus represent positive regulators, and βPIX is a negative regulator of microtubule nucleation from the interphase centrosomes. The regulatory roles of GIT1, βPIX and PAK1 in microtubule nucleation correlated with recruitment of γ-tubulin to the centrosome. Furthermore, in vitro kinase assays showed that GIT1 and βPIX, but not γ-tubulin, serve as substrates for PAK1. Finally, direct interaction of γ-tubulin with the C-terminal domain of βPIX and the N-terminal domain of GIT1, which targets this protein to the centrosome, was determined by pull-down experiments. We propose that GIT1/βPIX signaling proteins with PAK1 kinase represent a novel regulatory mechanism of microtubule nucleation in interphase cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Phloem proteomics reveals new lipid-binding proteins with a putative role in lipid-mediated signaling

    Directory of Open Access Journals (Sweden)

    Allison Marie Barbaglia

    2016-04-01

    Full Text Available Global climate changes inversely affect our ability to grow the food required for an increasing world population. To combat future crop loss due to abiotic stress, we need to understand the signals responsible for changes in plant development and the resulting adaptations, especially the signaling molecules traveling long-distance through the plant phloem. Using a proteomics approach, we had identified several putative lipid-binding proteins in the phloem exudates. Simultaneously, we identified several complex lipids as well as jasmonates. These findings prompted us to propose that phloem (phospho- lipids could act as long-distance developmental signals in response to abiotic stress, and that they are released, sensed, and moved by phloem lipid-binding proteins (Benning et al., 2012. Indeed, the proteins we identified include lipases that could release a signaling lipid into the phloem, putative receptor components, and proteins that could mediate lipid-movement. To test this possible protein-based lipid-signaling pathway, three of the proteins, which could potentially act in a relay, are characterized here: (I a putative GDSL-motif lipase (II a PIG-P-like protein, with a possible receptor-like function; (III and PLAFP (phloem lipid-associated family protein, a predicted lipid-binding protein of unknown function. Here we show that all three proteins bind lipids, in particular phosphatidic acid (PtdOH, which is known to participate in intracellular stress signaling. Genes encoding these proteins are expressed in the vasculature, a prerequisite for phloem transport. Cellular localization studies show that the proteins are not retained in the endoplasmic reticulum but surround the cell in a spotted pattern that has been previously observed with receptors and plasmodesmatal proteins. Abiotic signals that induce the production of PtdOH also regulate the expression of GDSL-lipase and PLAFP, albeit in opposite patterns. Our findings suggest that while

  10. The SH2 Domain–Containing Proteins in 21 Species Establish the Provenance and Scope of Phosphotyrosine Signaling in Eukaryotes

    Science.gov (United States)

    Liu, Bernard A.; Shah, Eshana; Jablonowski, Karl; Stergachis, Andrew; Engelmann, Brett; Nash, Piers D.

    2014-01-01

    The Src homology 2 (SH2) domains are participants in metazoan signal transduction, acting as primary mediators for regulated protein-protein interactions with tyrosine-phosphorylated substrates. Here, we describe the origin and evolution of SH2 domain proteins by means of sequence analysis from 21 eukaryotic organisms from the basal unicellular eukaryotes, where SH2 domains first appeared, through the multicellular animals and increasingly complex metazoans. On the basis of our results, SH2 domains and phosphotyrosine signaling emerged in the early Unikonta, and the numbers of SH2 domains expanded in the choanoflagellate and metazoan lineages with the development of tyrosine kinases, leading to rapid elaboration of phosphotyrosine signaling in early multicellular animals. Our results also indicated that SH2 domains coevolved and the number of the domains expanded alongside protein tyrosine kinases and tyrosine phosphatases, thereby coupling phosphotyrosine signaling to downstream signaling networks. Gene duplication combined with domain gain or loss produced novel SH2-containing proteins that function within phosphotyrosine signaling, which likely have contributed to diversity and complexity in metazoans. We found that intra- and intermolecular interactions within and between SH2 domain proteins increased in prevalence along with organismal complexity and may function to generate more highly connected and robust phosphotyrosine signaling networks. PMID:22155787

  11. Protein Kinase C alpha (PKCα) dependent signaling mediates endometrial cancer cell growth and tumorigenesis

    Science.gov (United States)

    Haughian, James M.; Reno, Elaine M.; Thorne, Alicia M.; Bradford, Andrew P.

    2009-01-01

    Endometrial cancer is the most common invasive gynecologic malignancy, yet molecular mechanisms and signaling pathways underlying its etiology and pathophysiology remain poorly characterized. We sought to define a functional role for the protein kinase C (PKC) isoform, PKCα, in an established cell model of endometrial adenocarcinoma. Ishikawa cells depleted of PKCα protein grew slower, formed fewer colonies in anchorage-independent growth assays and exhibited impaired xenograft tumor formation in nude mice. Consistent with impaired growth, PKCα knockdown increased levels of the cyclin dependent kinase (CDK) inhibitors p21Cip1/WAF1 (p21) and p27Kip1 (p27). Despite the absence of functional phosphatase and tensin homologue (PTEN) protein in Ishikawa cells, PKCα knockdown reduced Akt phosphorylation at serine 473 and concomitantly inhibited phosphorylation of the Akt target, glycogen synthase kinase-3β (GSK-3β). PKCα knockdown also resulted in decreased basal ERK phosphorylation and attenuated ERK activation following EGF stimulation. p21 and p27 expression was not increased by treatment of Ishikawa cells with ERK and Akt inhibitors, suggesting PKCα regulates CDK expression independently of Akt and ERK. Immunohistochemical analysis of grade 1 endometrioid adenocarcinoma revealed aberrant PKCα expression, with foci of elevated PKCα staining, not observed in normal endometrium. These studies demonstrate a critical role for PKCα signaling in endometrial tumorigenesis by regulating expression of CDK inhibitors p21 and p27 and activation of Akt and ERK dependent proliferative pathways. Thus, targeting PKCα may provide novel therapeutic options in endometrial tumors. PMID:19672862

  12. Acute fluoride poisoning alters myocardial cytoskeletal and AMPK signaling proteins in rats.

    Science.gov (United States)

    Panneerselvam, Lakshmikanthan; Raghunath, Azhwar; Perumal, Ekambaram

    2017-02-15

    Our previous findings revealed that increased oxidative stress, apoptosis and necrosis were implicated in acute fluoride (F - ) induced cardiac dysfunction apart from hypocalcemia and hyperkalemia. Cardiac intermediate filaments (desmin and vimentin) and cytoskeleton linker molecule vinculin plays an imperative role in maintaining the architecture of cardiac cytoskeleton. In addition, AMPK is a stress activated kinase that regulates the energy homeostasis during stressed state. The present study was aimed to examine the role of cytoskeletal proteins and AMPK signaling molecules in acute F - induced cardiotoxicity in rats. In order to study this, male Wistar rats were treated with single oral doses of 45 and 90mg/kgF - for 24h. Acute F - intoxicated rats showed declined cytoskeletal protein expression of desmin, vimentin and vinculin in a dose dependent manner compared to control. A significant increase in phosphorylation of AMPKα (Thr172), AMPKß1 (Ser108) and Acetyl-coA carboxylase (ACC) (Ser79) in the myocardium and associated ATP deprivation were found in acute F - intoxicated rats. Further, ultra-structural studies confirmed myofibril lysis with interruption of Z lines, dilated sarcoplasmic reticulum and damaged mitochondrion were observed in both the groups of F - intoxicated rats. Taken together, these findings reveal that acute F - exposure causes sudden heart failure by altering the expression of cytoskeletal proteins and AMPK signaling molecules. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  13. Mapping the nuclear localization signal in the matrix protein of potato yellow dwarf virus.

    Science.gov (United States)

    Anderson, Gavin; Jang, Chanyong; Wang, Renyuan; Goodin, Michael

    2018-05-01

    The ability of the matrix (M) protein of potato yellow dwarf virus (PYDV) to remodel nuclear membranes is controlled by a di-leucine motif located at residues 223 and 224 of its primary structure. This function can be uncoupled from that of its nuclear localization signal (NLS), which is controlled primarily by lysine and arginine residues immediately downstream of the LL motif. In planta localization of green fluorescent protein fusions, bimolecular fluorescence complementation assays with nuclear import receptor importin-α1 and yeast-based nuclear import assays provided three independent experimental approaches to validate the authenticity of the M-NLS. The carboxy terminus of M is predicted to contain a nuclear export signal, which is belived to be functional, given the ability of M to bind the Arabidopsis nuclear export receptor 1 (XPO1). The nuclear shuttle activity of M has implications for the cell-to-cell movement of PYDV nucleocapsids, based upon its interaction with the N and Y proteins.

  14. A set of enhanced green fluorescent protein concatemers for quantitative determination of nuclear localization signal strength.

    Science.gov (United States)

    Böhm, Jennifer; Thavaraja, Ramya; Giehler, Susanne; Nalaskowski, Marcus M

    2017-09-15

    Regulated transport of proteins between nucleus and cytoplasm is an important process in the eukaryotic cell. In most cases, active nucleo-cytoplasmic protein transport is mediated by nuclear localization signal (NLS) and/or nuclear export signal (NES) motifs. In this study, we developed a set of vectors expressing enhanced GFP (EGFP) concatemers ranging from 2 to 12 subunits (2xEGFP to 12xEGFP) for analysis of NLS strength. As shown by in gel GFP fluorescence analysis and αGFP Western blotting, EGFP concatemers are expressed as fluorescent full-length proteins in eukaryotic cells. As expected, nuclear localization of concatemeric EGFPs decreases with increasing molecular weight. By oligonucleotide ligation this set of EGFP concatemers can be easily fused to NLS motifs. After determination of intracellular localization of EGFP concatemers alone and fused to different NLS motifs we calculated the size of a hypothetic EGFP concatemer showing a defined distribution of EGFP fluorescence between nucleus and cytoplasm (n/c ratio = 2). Clear differences of the size of the hypothetic EGFP concatemer depending on the fused NLS motif were observed. Therefore, we propose to use the size of this hypothetic concatemer as quantitative indicator for comparing strength of different NLS motifs. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. A novel strategy to improve protein secretion via overexpression of the SppA signal peptide peptidase in Bacillus licheniformis.

    Science.gov (United States)

    Cai, Dongbo; Wang, Hao; He, Penghui; Zhu, Chengjun; Wang, Qin; Wei, Xuetuan; Nomura, Christopher T; Chen, Shouwen

    2017-04-24

    Signal peptide peptidases play an important role in the removal of remnant signal peptides in the cell membrane, a critical step for extracellular protein production. Although these proteins are likely a central component for extracellular protein production, there has been a lack of research on whether protein secretion could be enhanced via overexpression of signal peptide peptidases. In this study, both nattokinase and α-amylase were employed as prototypical secreted target proteins to evaluate the function of putative signal peptide peptidases (SppA and TepA) in Bacillus licheniformis. We observed dramatic decreases in the concentrations of both target proteins (45 and 49%, respectively) in a sppA deficient strain, while the extracellular protein yields of nattokinase and α-amylase were increased by 30 and 67% respectively in a strain overexpressing SppA. In addition, biomass, specific enzyme activities and the relative gene transcriptional levels were also enhanced due to the overexpression of sppA, while altering the expression levels of tepA had no effect on the concentrations of the secreted target proteins. Our results confirm that SppA, but not TepA, plays an important functional role for protein secretion in B. licheniformis. Our results indicate that the sppA overexpression strain, B. licheniformis BL10GS, could be used as a promising host strain for the industrial production of heterologous secreted proteins.

  16. Pathogenic Leptospires Modulate Protein Expression and Post-translational Modifications in Response to Mammalian Host Signals.

    Science.gov (United States)

    Nally, Jarlath E; Grassmann, Andre A; Planchon, Sébastien; Sergeant, Kjell; Renaut, Jenny; Seshu, Janakiram; McBride, Alan J; Caimano, Melissa J

    2017-01-01

    Pathogenic species of Leptospira cause leptospirosis, a bacterial zoonotic disease with a global distribution affecting over one million people annually. Reservoir hosts of leptospirosis, including rodents, dogs, and cattle, exhibit little to no signs of disease but shed large numbers of organisms in their urine. Transmission occurs when mucosal surfaces or abraded skin come into contact with infected urine or urine-contaminated water or soil. Whilst little is known about how Leptospira adapt to and persist within a reservoir host, in vitro studies suggest that leptospires alter their transcriptomic and proteomic profiles in response to environmental signals encountered during mammalian infection. We applied the dialysis membrane chamber (DMC) peritoneal implant model to compare the whole cell proteome of in vivo derived leptospires with that of leptospires cultivated in vitro at 30°C and 37°C by 2-dimensional difference in-gel electrophoresis (2-D DIGE). Of 1,735 protein spots aligned across 9 2-D DIGE gels, 202 protein spots were differentially expressed ( p 1.25 or expressed proteins were excised for identification by mass spectrometry. Data are available via ProteomeXchange with identifier PXD006995. The greatest differences were detected when DMC-cultivated leptospires were compared with IV30- or IV37-cultivated leptospires, including the increased expression of multiple isoforms of Loa22, a known virulence factor. Unexpectedly, 20 protein isoforms of LipL32 and 7 isoforms of LipL41 were uniformly identified by DIGE as differentially expressed, suggesting that unique post-translational modifications (PTMs) are operative in response to mammalian host conditions. To test this hypothesis, a rat model of persistent renal colonization was used to isolate leptospires directly from the urine of experimentally infected rats. Comparison of urinary derived leptospires to IV30 leptospires by 2-D immunoblotting confirmed that modification of proteins with

  17. Pathogenic Leptospires Modulate Protein Expression and Post-translational Modifications in Response to Mammalian Host Signals

    Directory of Open Access Journals (Sweden)

    Jarlath E. Nally

    2017-08-01

    Full Text Available Pathogenic species of Leptospira cause leptospirosis, a bacterial zoonotic disease with a global distribution affecting over one million people annually. Reservoir hosts of leptospirosis, including rodents, dogs, and cattle, exhibit little to no signs of disease but shed large numbers of organisms in their urine. Transmission occurs when mucosal surfaces or abraded skin come into contact with infected urine or urine-contaminated water or soil. Whilst little is known about how Leptospira adapt to and persist within a reservoir host, in vitro studies suggest that leptospires alter their transcriptomic and proteomic profiles in response to environmental signals encountered during mammalian infection. We applied the dialysis membrane chamber (DMC peritoneal implant model to compare the whole cell proteome of in vivo derived leptospires with that of leptospires cultivated in vitro at 30°C and 37°C by 2-dimensional difference in-gel electrophoresis (2-D DIGE. Of 1,735 protein spots aligned across 9 2-D DIGE gels, 202 protein spots were differentially expressed (p < 0.05, fold change >1.25 or < −1.25 across all three conditions. Differentially expressed proteins were excised for identification by mass spectrometry. Data are available via ProteomeXchange with identifier PXD006995. The greatest differences were detected when DMC-cultivated leptospires were compared with IV30- or IV37-cultivated leptospires, including the increased expression of multiple isoforms of Loa22, a known virulence factor. Unexpectedly, 20 protein isoforms of LipL32 and 7 isoforms of LipL41 were uniformly identified by DIGE as differentially expressed, suggesting that unique post-translational modifications (PTMs are operative in response to mammalian host conditions. To test this hypothesis, a rat model of persistent renal colonization was used to isolate leptospires directly from the urine of experimentally infected rats. Comparison of urinary derived leptospires to IV30

  18. Overexpression of protein O-fucosyltransferase 1 accelerates hepatocellular carcinoma progression via the Notch signaling pathway

    International Nuclear Information System (INIS)

    Ma, Lijie; Dong, Pingping; Liu, Longzi; Gao, Qiang; Duan, Meng; Zhang, Si; Chen, She; Xue, Ruyi; Wang, Xiaoying

    2016-01-01

    Aberrant activation of Notch signaling frequently occurs in liver cancer, and is associated with liver malignancies. However, the mechanisms regulating pathologic Notch activation in hepatocellular carcinoma (HCC) remain unclear. Protein O-fucosyltransferase 1 (Pofut1) catalyzes the addition of O-linked fucose to the epidermal growth factor-like repeats of Notch. In the present study, we detected the expression of Pofut1 in 8 HCC cell lines and 253 human HCC tissues. We reported that Pofut1 was overexpressed in HCC cell lines and clinical HCC tissues, and Pofut1 overexpression clinically correlated with the unfavorable survival and high disease recurrence in HCC. The in vitro assay demonstrated that Pofut1 overexpression accelerated the cell proliferation and migration in HCC cells. Furthermore, Pofut1 overexpression promoted the binding of Notch ligand Dll1 to Notch receptor, and hence activated Notch signaling pathway in HCC cells, indicating that Pofut1 overexpression could be a reason for the aberrant activation of Notch signaling in HCC. Taken together, our findings indicated that an aberrant activated Pofut1-Notch pathway was involved in HCC progression, and blockage of this pathway could be a promising strategy for the therapy of HCC. - Highlights: • Pofut1 overexpression in HCC was correlated with aggressive tumor behaviors. • Pofut1 overexpression in HCC was associated with poor prognosis. • Pofut1 promoted cell proliferation, migration and invasion in hepatoma cells. • Pofut1 activated Notch signaling pathway in hepatoma cells.

  19. Electrochemical detection of C-reactive protein using Copper nanoparticles and hybridization chain reaction amplifying signal.

    Science.gov (United States)

    Zhang, Junjun; Zhang, Wenjuan; Guo, Jinjin; Wang, Junchun; Zhang, Yuzhong

    2017-12-15

    In this study, a sandwich-type electrochemical immunosensor for the detection of C-reactive protein (CRP) is described. In design, Copper nanoparticles (Cu NPs) were used for signal tag and hybridization chain reaction (HCR)amplified output signal. The immunosensor fabrication involved three steps: (i) primary antibodies (Ab 1 ) were immobilized on the surface of gold nanoparticles (Au NPs); (ii) the sandwich-type structure formation contained "primary antibodies-antigen-secondary antibodies conjugated with primer (Ab 2 -S 0 )"; and (iii) long DNA concatemers intercalating amounts of Cu NPs was linked to the sandwich-type structure via hybridization reaction. Differential pulse voltammetry (DPV) was used to record the response signal of the immunosensor in phosphate-buffered saline (PBS). Under optimal conditions, the anodic peak currents of Cu NPs at the peak potential of about 0.08V(VS.SCE) were linear with the logarithm of CRP concentration in the range of 1.0 fg mL -1 to 100 ng mL -1 with a detection limit of 0.33 fg mL -1 (at signal/noise [S/N] = 3). In addition, the practical application of immunosensor was evaluated by analyzing CRP in real human serum samples, the recoveries obtained were within 95.3%-103.8%, indicating the immunosensor possessed potential application ability for practical disease diagnosis. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Increased bone morphogenetic protein signaling contributes to age-related declines in neurogenesis and cognition.

    Science.gov (United States)

    Meyers, Emily A; Gobeske, Kevin T; Bond, Allison M; Jarrett, Jennifer C; Peng, Chian-Yu; Kessler, John A

    2016-02-01

    Aging is associated with decreased neurogenesis in the hippocampus and diminished hippocampus-dependent cognitive functions. Expression of bone morphogenetic protein 4 (BMP4) increases with age by more than 10-fold in the mouse dentate gyrus while levels of the BMP inhibitor, noggin, decrease. This results in a profound 30-fold increase in phosphorylated-SMAD1/5/8, the effector of canonical BMP signaling. Just as observed in mice, a profound increase in expression of BMP4 is observed in the dentate gyrus of humans with no known cognitive abnormalities. Inhibition of BMP signaling either by overexpression of noggin or transgenic manipulation not only increases neurogenesis in aging mice, but remarkably, is associated with a rescue of cognitive deficits to levels comparable to young mice. Additive benefits are observed when combining inhibition of BMP signaling and environmental enrichment. These findings indicate that increased BMP signaling contributes significantly to impairments in neurogenesis and to cognitive decline associated with aging, and identify this pathway as a potential druggable target for reversing age-related changes in cognition. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. Cholesterol activates the G-protein coupled receptor Smoothened to promote Hedgehog signaling

    Science.gov (United States)

    Luchetti, Giovanni; Sircar, Ria; Kong, Jennifer H; Nachtergaele, Sigrid; Sagner, Andreas; Byrne, Eamon FX; Covey, Douglas F; Siebold, Christian; Rohatgi, Rajat

    2016-01-01

    Cholesterol is necessary for the function of many G-protein coupled receptors (GPCRs). We find that cholesterol is not just necessary but also sufficient to activate signaling by the Hedgehog (Hh) pathway, a prominent cell-cell communication system in development. Cholesterol influences Hh signaling by directly activating Smoothened (SMO), an orphan GPCR that transmits the Hh signal across the membrane in all animals. Unlike many GPCRs, which are regulated by cholesterol through their heptahelical transmembrane domains, SMO is activated by cholesterol through its extracellular cysteine-rich domain (CRD). Residues shown to mediate cholesterol binding to the CRD in a recent structural analysis also dictate SMO activation, both in response to cholesterol and to native Hh ligands. Our results show that cholesterol can initiate signaling from the cell surface by engaging the extracellular domain of a GPCR and suggest that SMO activity may be regulated by local changes in cholesterol abundance or accessibility. DOI: http://dx.doi.org/10.7554/eLife.20304.001 PMID:27705744

  2. Review: Mitogen-Activated Protein kinases in nutritional signaling in Arabidopsis

    KAUST Repository

    Chardin, Camille

    2017-04-14

    Mitogen-Activated Protein Kinase (MAPK) cascades are functional modules widespread among eukaryotic organisms. In plants, these modules are encoded by large multigenic families and are involved in many biological processes ranging from stress responses to cellular differentiation and organ development. Furthermore, MAPK pathways are involved in the perception of environmental and physiological modifications. Interestingly, some MAPKs play a role in several signaling networks and could have an integrative function for the response of plants to their environment. In this review, we describe the classification of MAPKs and highlight some of their biochemical actions. We performed an in silico analysis of MAPK gene expression in response to nutrients supporting their involvement in nutritional signaling. While several MAPKs have been identified as players in sugar, nitrogen, phosphate, iron and potassium-related signaling pathways, their biochemical functions are yet mainly unknown. The integration of these regulatory cascades in the current understanding of nutrient signaling is discussed and potential new avenues for approaches toward plants with higher nutrient use efficiencies are evoked.

  3. Review: Mitogen-Activated Protein kinases in nutritional signaling in Arabidopsis

    KAUST Repository

    Chardin, Camille; Schenk, Sebastian T.; Hirt, Heribert; Colcombet, Jean; Krapp, Anne

    2017-01-01

    Mitogen-Activated Protein Kinase (MAPK) cascades are functional modules widespread among eukaryotic organisms. In plants, these modules are encoded by large multigenic families and are involved in many biological processes ranging from stress responses to cellular differentiation and organ development. Furthermore, MAPK pathways are involved in the perception of environmental and physiological modifications. Interestingly, some MAPKs play a role in several signaling networks and could have an integrative function for the response of plants to their environment. In this review, we describe the classification of MAPKs and highlight some of their biochemical actions. We performed an in silico analysis of MAPK gene expression in response to nutrients supporting their involvement in nutritional signaling. While several MAPKs have been identified as players in sugar, nitrogen, phosphate, iron and potassium-related signaling pathways, their biochemical functions are yet mainly unknown. The integration of these regulatory cascades in the current understanding of nutrient signaling is discussed and potential new avenues for approaches toward plants with higher nutrient use efficiencies are evoked.

  4. Regulation of G-protein coupled receptor traffic by an evolutionary conserved hydrophobic signal.

    Science.gov (United States)

    Angelotti, Tim; Daunt, David; Shcherbakova, Olga G; Kobilka, Brian; Hurt, Carl M

    2010-04-01

    Plasma membrane (PM) expression of G-protein coupled receptors (GPCRs) is required for activation by extracellular ligands; however, mechanisms that regulate PM expression of GPCRs are poorly understood. For some GPCRs, such as alpha2c-adrenergic receptors (alpha(2c)-ARs), heterologous expression in non-native cells results in limited PM expression and extensive endoplasmic reticulum (ER) retention. Recently, ER export/retentions signals have been proposed to regulate cellular trafficking of several GPCRs. By utilizing a chimeric alpha(2a)/alpha(2c)-AR strategy, we identified an evolutionary conserved hydrophobic sequence (ALAAALAAAAA) in the extracellular amino terminal region that is responsible in part for alpha(2c)-AR subtype-specific trafficking. To our knowledge, this is the first luminal ER retention signal reported for a GPCR. Removal or disruption of the ER retention signal dramatically increased PM expression and decreased ER retention. Conversely, transplantation of this hydrophobic sequence into alpha(2a)-ARs reduced their PM expression and increased ER retention. This evolutionary conserved hydrophobic trafficking signal within alpha(2c)-ARs serves as a regulator of GPCR trafficking.

  5. Transmembrane signal transduction by peptide hormones via family B G protein-coupled receptors

    Directory of Open Access Journals (Sweden)

    Kelly J Culhane

    2015-11-01

    Full Text Available Although family B G protein-coupled receptors (GPCRs contain only 15 members, they play key roles in transmembrane signal transduction of hormones. Family B GPCRs are drug targets for developing therapeutics for diseases ranging from metabolic to neurological disorders. Despite their importance, the molecular mechanism of activation of family B GPCRs remains largely unexplored due to the challenges in expression and purification of functional receptors to the quantity for biophysical characterization. Currently, there is no crystal structure available of a full-length family B GPCR. However, structures of key domains, including the extracellular ligand binding regions and seven-helical transmembrane regions, have been solved by X-ray crystallography and NMR, providing insights into the mechanisms of ligand recognition and selectivity, and helical arrangements within the cell membrane. Moreover, biophysical and biochemical methods have been used to explore functions, key residues for signaling, and the kinetics and dynamics of signaling processes. This review summarizes the current knowledge of the signal transduction mechanism of family B GPCRs at the molecular level and comments on the challenges and outlook for mechanistic studies of family B GPCRs.

  6. Overexpression of protein O-fucosyltransferase 1 accelerates hepatocellular carcinoma progression via the Notch signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Lijie [Liver Surgery Department, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai (China); Dong, Pingping [Department of Gastroenterology and Hepatology, Shanghai Institute of Liver Diseases, Zhongshan Hospital of Fudan University, Shanghai (China); Liu, Longzi; Gao, Qiang; Duan, Meng [Liver Surgery Department, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai (China); Zhang, Si; Chen, She [Key Laboratory of Glycoconjugate Research Ministry of Public Health, Department of Biochemistry and Molecular Biology, Shanghai Medical College, Fudan University, Shanghai (China); Xue, Ruyi, E-mail: xue.ruyi@zs-hospital.sh.cn [Department of Gastroenterology and Hepatology, Shanghai Institute of Liver Diseases, Zhongshan Hospital of Fudan University, Shanghai (China); Wang, Xiaoying, E-mail: xiaoyingwang@fudan.edu.cn [Liver Surgery Department, Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of Education, Shanghai (China)

    2016-04-29

    Aberrant activation of Notch signaling frequently occurs in liver cancer, and is associated with liver malignancies. However, the mechanisms regulating pathologic Notch activation in hepatocellular carcinoma (HCC) remain unclear. Protein O-fucosyltransferase 1 (Pofut1) catalyzes the addition of O-linked fucose to the epidermal growth factor-like repeats of Notch. In the present study, we detected the expression of Pofut1 in 8 HCC cell lines and 253 human HCC tissues. We reported that Pofut1 was overexpressed in HCC cell lines and clinical HCC tissues, and Pofut1 overexpression clinically correlated with the unfavorable survival and high disease recurrence in HCC. The in vitro assay demonstrated that Pofut1 overexpression accelerated the cell proliferation and migration in HCC cells. Furthermore, Pofut1 overexpression promoted the binding of Notch ligand Dll1 to Notch receptor, and hence activated Notch signaling pathway in HCC cells, indicating that Pofut1 overexpression could be a reason for the aberrant activation of Notch signaling in HCC. Taken together, our findings indicated that an aberrant activated Pofut1-Notch pathway was involved in HCC progression, and blockage of this pathway could be a promising strategy for the therapy of HCC. - Highlights: • Pofut1 overexpression in HCC was correlated with aggressive tumor behaviors. • Pofut1 overexpression in HCC was associated with poor prognosis. • Pofut1 promoted cell proliferation, migration and invasion in hepatoma cells. • Pofut1 activated Notch signaling pathway in hepatoma cells.

  7. Chemogenetic Modulation of G Protein-Coupled Receptor Signalling in Visual Attention Research

    DEFF Research Database (Denmark)

    Jørgensen, Søren H; Fitzpatrick, Ciarán Martin; Gether, Ulrik

    2017-01-01

    Exclusively Activated by Designer Drugs (DREADDs). The DREADD technology is an emerging and transformative method that allows selective manipulation of G protein-coupled receptor (GPCR) signalling, and its broad-ranging usefulness in attention research is now beginning to emerge. We first describe......Attention is a fundamental cognitive process involved in nearly all aspects of life. Abnormal attentional control is a symptom of many neurological disorders, most notably recognized in ADHD (attention deficit hyperactivity disorder). Although attentional performance and its malfunction has been...... the different DREADDs available and explain how unprecedented specificity of neuronal signalling can be achieved using DREADDs. We next discuss various studies performed in animal models of visual attention, where different brain regions and neuronal populations have been probed by DREADDs. We highlight...

  8. Plant GSK3 proteins regulate xylem cell differentiation downstream of TDIF-TDR signalling

    Science.gov (United States)

    Kondo, Yuki; Ito, Tasuku; Nakagami, Hirofumi; Hirakawa, Yuki; Saito, Masato; Tamaki, Takayuki; Shirasu, Ken; Fukuda, Hiroo

    2014-03-01

    During plant radial growth typically seen in trees, procambial and cambial cells act as meristematic cells in the vascular system to self-proliferate and differentiate into xylem cells. These two processes are regulated by a signalling pathway composed of a peptide ligand and its receptor; tracheary element differentiation inhibitory factor (TDIF) and TDIF RECEPTOR (TDR). Here we show that glycogen synthase kinase 3 proteins (GSK3s) are crucial downstream components of the TDIF signalling pathway suppressing xylem differentiation from procambial cells. TDR interacts with GSK3s at the plasma membrane and activates GSK3s in a TDIF-dependent fashion. Consistently, a specific inhibitor of plant GSK3s strongly induces xylem cell differentiation through BRI1-EMS SUPPRESSOR 1 (BES1), a well-known target transcription factor of GSK3s. Our findings provide insight into the regulation of cell fate determination in meristem maintenance.

  9. Domain requirements for the Dock adapter protein in growth- cone signaling.

    Science.gov (United States)

    Rao, Y; Zipursky, S L

    1998-03-03

    Tyrosine phosphorylation has been implicated in growth-cone guidance through genetic, biochemical, and pharmacological studies. Adapter proteins containing src homology 2 (SH2) domains and src homology 3 (SH3) domains provide a means of linking guidance signaling through phosphotyrosine to downstream effectors regulating growth-cone motility. The Drosophila adapter, Dreadlocks (Dock), the homolog of mammalian Nck containing three N-terminal SH3 domains and a single SH2 domain, is highly specialized for growth-cone guidance. In this paper, we demonstrate that Dock can couple signals in either an SH2-dependent or an SH2-independent fashion in photoreceptor (R cell) growth cones, and that Dock displays different domain requirements in different neurons.

  10. Isolation and structure-function characterization of a signaling-active rhodopsin-G protein complex.

    Science.gov (United States)

    Gao, Yang; Westfield, Gerwin; Erickson, Jon W; Cerione, Richard A; Skiniotis, Georgios; Ramachandran, Sekar

    2017-08-25

    The visual photo-transduction cascade is a prototypical G protein-coupled receptor (GPCR) signaling system, in which light-activated rhodopsin (Rho*) is the GPCR catalyzing the exchange of GDP for GTP on the heterotrimeric G protein transducin (G T ). This results in the dissociation of G T into its component α T -GTP and β 1 γ 1 subunit complex. Structural information for the Rho*-G T complex will be essential for understanding the molecular mechanism of visual photo-transduction. Moreover, it will shed light on how GPCRs selectively couple to and activate their G protein signaling partners. Here, we report on the preparation of a stable detergent-solubilized complex between Rho* and a heterotrimer (G T *) comprising a Gα T /Gα i1 chimera (α T *) and β 1 γ 1 The complex was formed on native rod outer segment membranes upon light activation, solubilized in lauryl maltose neopentyl glycol, and purified with a combination of affinity and size-exclusion chromatography. We found that the complex is fully functional and that the stoichiometry of Rho* to Gα T * is 1:1. The molecular weight of the complex was calculated from small-angle X-ray scattering data and was in good agreement with a model consisting of one Rho* and one G T *. The complex was visualized by negative-stain electron microscopy, which revealed an architecture similar to that of the β 2 -adrenergic receptor-G S complex, including a flexible α T * helical domain. The stability and high yield of the purified complex should allow for further efforts toward obtaining a high-resolution structure of this important signaling complex. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. Phosphatidylcholine transfer protein interacts with thioesterase superfamily member 2 to attenuate insulin signaling.

    Science.gov (United States)

    Ersoy, Baran A; Tarun, Akansha; D'Aquino, Katharine; Hancer, Nancy J; Ukomadu, Chinweike; White, Morris F; Michel, Thomas; Manning, Brendan D; Cohen, David E

    2013-07-30

    Phosphatidylcholine transfer protein (PC-TP) is a phospholipid-binding protein that is enriched in liver and that interacts with thioesterase superfamily member 2 (THEM2). Mice lacking either protein exhibit improved hepatic glucose homeostasis and are resistant to diet-induced diabetes. Insulin receptor substrate 2 (IRS2) and mammalian target of rapamycin complex 1 (mTORC1) are key effectors of insulin signaling, which is attenuated in diabetes. We found that PC-TP inhibited IRS2, as evidenced by insulin-independent IRS2 activation after knockdown, genetic ablation, or chemical inhibition of PC-TP. In addition, IRS2 was activated after knockdown of THEM2, providing support for a role for the interaction of PC-TP with THEM2 in suppressing insulin signaling. Additionally, we showed that PC-TP bound to tuberous sclerosis complex 2 (TSC2) and stabilized the components of the TSC1-TSC2 complex, which functions to inhibit mTORC1. Preventing phosphatidylcholine from binding to PC-TP disrupted interactions of PC-TP with THEM2 and TSC2, and disruption of the PC-TP-THEM2 complex was associated with increased activation of both IRS2 and mTORC1. In livers of mice with genetic ablation of PC-TP or that had been treated with a PC-TP inhibitor, steady-state amounts of IRS2 were increased, whereas those of TSC2 were decreased. These findings reveal a phospholipid-dependent mechanism that suppresses insulin signaling downstream of its receptor.

  12. Expression of the Grb2-related protein of the lymphoid system in B cell subsets enhances B cell antigen receptor signaling through mitogen-activated protein kinase pathways.

    Science.gov (United States)

    Yankee, Thomas M; Solow, Sasha A; Draves, Kevin D; Clark, Edward A

    2003-01-01

    Adapter proteins play a critical role in regulating signals triggered by Ag receptor cross-linking. These small molecules link receptor proximal events with downstream signaling pathways. In this study, we explore the expression and function of the Grb2-related protein of the lymphoid system (GrpL)/Grb2-related adaptor downstream of Shc adapter protein in human B cells. GrpL is expressed in naive B cells and is down-regulated following B cell Ag receptor ligation. By contrast, germinal center and memory B cells express little or no GrpL. Using human B cell lines, we detected constitutive interactions between GrpL and B cell linker protein, Src homology (SH)2 domain-containing leukocyte protein of 76 kDa, hemopoietic progenitor kinase 1, and c-Cbl. The N-terminal SH3 domain of GrpL binds c-Cbl while the C-terminal SH3 domain binds B cell linker protein and SH2 domain-containing leukocyte protein of 76 kDa. Exogenous expression of GrpL in a GrpL-negative B cell line leads to enhanced Ag receptor-induced extracellular signal-related kinase and p38 mitogen-activated protein kinase phosphorylation. Thus, GrpL expression in human B cell subsets appears to regulate Ag receptor-mediated signaling events.

  13. The methylotrophic yeast Hansenula polymorpha contains an inducible import pathway for peroxisomal matrix proteins with an N-terminal targeting signal (PTS2 proteins)

    NARCIS (Netherlands)

    Faber, Klaas Nico; Haima, Pieter; Gietl, Christine; Harder, Willem; Ab, Geert; Veenhuis, Marten

    1994-01-01

    Two main types of peroxisomal targeting signals have been identified that reside either at the extreme C terminus (PTS1) or the N terminus (PTS2) of the protein. In the methylotrophic yeast Hansenula polymorpha the majority of peroxisomal matrix proteins are of the PTS1 type. Thus far, for H.

  14. Arabidopsis scaffold protein RACK1A modulates rare sugar D-allose regulated gibberellin signaling

    OpenAIRE

    Fennell, Herman; Olawin, Abdulquadri; Mizanur, Rahman M.; Izumori, Ken; Chen, Jin-Gui; Ullah, Hemayet

    2012-01-01

    As energy sources and structural components, sugars are the central regulators of plant growth and development. In addition to the abundant natural sugars in plants, more than 50 different kinds of rare sugars exist in nature, several of which show distinct roles in plant growth and development. Recently, one of the rare sugars, D-allose, an epimer of D-glucose at C3, is found to suppress plant hormone gibberellin (GA) signaling in rice. Scaffold protein RACK1A in the model plant Arabidopsis ...

  15. Heterotrimeric G Protein-coupled Receptor Signaling in Yeast Mating Pheromone Response.

    Science.gov (United States)

    Alvaro, Christopher G; Thorner, Jeremy

    2016-04-08

    The DNAs encoding the receptors that respond to the peptide mating pheromones of the budding yeastSaccharomyces cerevisiaewere isolated in 1985, and were the very first genes for agonist-binding heterotrimeric G protein-coupled receptors (GPCRs) to be cloned in any organism. Now, over 30 years later, this yeast and its receptors continue to provide a pathfinding experimental paradigm for investigating GPCR-initiated signaling and its regulation, as described in this retrospective overview. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  16. GIT1/beta PIX signaling proteins and PAK1 kinase regulate microtubule nucleation

    Czech Academy of Sciences Publication Activity Database

    Černohorská, Markéta; Sulimenko, Vadym; Hájková, Zuzana; Sulimenko, Tetyana; Sládková, Vladimíra; Vinopal, Stanislav; Dráberová, Eduarda; Dráber, Pavel

    2016-01-01

    Roč. 1863, č. 6 (2016), s. 1282-1297 ISSN 0167-4889 R&D Projects: GA ČR GAP302/12/1673; GA ČR GA15-22194S; GA MŠk LH12050; GA MZd NT14467; GA ČR GA16-23702S Institutional support: RVO:68378050 Keywords : Centrosome * Microtubule nucleation * gamma-tubulin * GIT1/beta PIX signaling proteins * PAK1 kinase Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.521, year: 2016

  17. What You Should Know about Flu Antiviral Drugs

    Science.gov (United States)

    ... Other What You Should Know About Flu Antiviral Drugs Language: English (US) Español Recommend on Facebook Tweet ... used to treat flu illness. What are antiviral drugs? Antiviral drugs are prescription medicines (pills, liquid, an ...

  18. Targeting G-Protein Signaling for the Therapeutics of Prostate Tumor Bone Metastases and the Associated Chronic Bone Pain

    Science.gov (United States)

    2015-09-01

    Cancer Bone Metastasis, heterotrimeric G protein  subunits, G protein-coupled receptors, signal transduction 16. SECURITY CLASSIFICATION OF: 17...TRPV1 expression/function in cultured mouse DRG sensory neurons. Accomplishments: we initially attempted to manipulate Gsignaling in isolated DRG ...increase in AKT activation. Since AKT activation will activate TRPV1 channel in DRG neurons, we cannot further assess the effect of G1 and Gt

  19. Turnover of amyloid precursor protein family members determines their nuclear signaling capability.

    Science.gov (United States)

    Gersbacher, Manuel T; Goodger, Zoë V; Trutzel, Annette; Bundschuh, Diana; Nitsch, Roger M; Konietzko, Uwe

    2013-01-01

    The amyloid precursor protein (APP) as well as its homologues, APP-like protein 1 and 2 (APLP1 and APLP2), are cleaved by α-, β-, and γ-secretases, resulting in the release of their intracellular domains (ICDs). We have shown that the APP intracellular domain (AICD) is transported to the nucleus by Fe65 where they jointly bind the histone acetyltransferase Tip60 and localize to spherical nuclear complexes (AFT complexes), which are thought to be sites of transcription. We have now analyzed the subcellular localization and turnover of the APP family members. Similarly to AICD, the ICD of APLP2 localizes to spherical nuclear complexes together with Fe65 and Tip60. In contrast, the ICD of APLP1, despite binding to Fe65, does not translocate to the nucleus. In addition, APLP1 predominantly localizes to the plasma membrane, whereas APP and APLP2 are detected in vesicular structures. APLP1 also demonstrates a much slower turnover of the full-length protein compared to APP and APLP2. We further show that the ICDs of all APP family members are degraded by the proteasome and that the N-terminal amino acids of ICDs determine ICD degradation rate. Together, our results suggest that different nuclear signaling capabilities of APP family members are due to different rates of full-length protein processing and ICD proteasomal degradation. Our results provide evidence in support of a common nuclear signaling function for APP and APLP2 that is absent in APLP1, but suggest that APLP1 has a regulatory role in the nuclear translocation of APP family ICDs due to the sequestration of Fe65.

  20. Wnt Signalling Promotes Actin Dynamics during Axon Remodelling through the Actin-Binding Protein Eps8.

    Directory of Open Access Journals (Sweden)

    Eleanna Stamatakou

    Full Text Available Upon arrival at their synaptic targets, axons slow down their growth and extensively remodel before the assembly of presynaptic boutons. Wnt proteins are target-derived secreted factors that promote axonal remodelling and synaptic assembly. In the developing spinal cord, Wnts secreted by motor neurons promote axonal remodelling of NT-3 responsive dorsal root ganglia neurons. Axon remodelling induced by Wnts is characterised by growth cone pausing and enlargement, processes that depend on the re-organisation of microtubules. However, the contribution of the actin cytoskeleton has remained unexplored. Here, we demonstrate that Wnt3a regulates the actin cytoskeleton by rapidly inducing F-actin accumulation in growth cones from rodent DRG neurons through the scaffold protein Dishevelled-1 (Dvl1 and the serine-threonine kinase Gsk3β. Importantly, these changes in actin cytoskeleton occurs before enlargement of the growth cones is evident. Time-lapse imaging shows that Wnt3a increases lamellar protrusion and filopodia velocity. In addition, pharmacological inhibition of actin assembly demonstrates that Wnt3a increases actin dynamics. Through a yeast-two hybrid screen, we identified the actin-binding protein Eps8 as a direct interactor of Dvl1, a scaffold protein crucial for the Wnt signalling pathway. Gain of function of Eps8 mimics Wnt-mediated axon remodelling, whereas Eps8 silencing blocks the axon remodelling activity of Wnt3a. Importantly, blockade of the Dvl1-Eps8 interaction completely abolishes Wnt3a-mediated axonal remodelling. These findings demonstrate a novel role for Wnt-Dvl1 signalling through Eps8 in the regulation of axonal remodeling.

  1. Regulation of Schistosoma mansoni development and reproduction by the mitogen-activated protein kinase signaling pathway.

    Science.gov (United States)

    Andrade, Luiza Freire de; Mourão, Marina de Moraes; Geraldo, Juliana Assis; Coelho, Fernanda Sales; Silva, Larissa Lopes; Neves, Renata Heisler; Volpini, Angela; Machado-Silva, José Roberto; Araujo, Neusa; Nacif-Pimenta, Rafael; Caffrey, Conor R; Oliveira, Guilherme

    2014-06-01

    Protein kinases are proven targets for drug development with an increasing number of eukaryotic Protein Kinase (ePK) inhibitors now approved as drugs. Mitogen-activated protein kinase (MAPK) family members connect cell-surface receptors to regulatory targets within cells and influence a number of tissue-specific biological activities such as cell proliferation, differentiation and survival. However, the contributions of members of the MAPK pathway to schistosome development and survival are unclear. We employed RNA interference (RNAi) to elucidate the functional roles of five S. mansoni genes (SmCaMK2, SmJNK, SmERK1, SmERK2 and SmRas) involved in MAPK signaling pathway. Mice were injected with post-infective larvae (schistosomula) subsequent to RNAi and the development of adult worms observed. The data demonstrate that SmJNK participates in parasite maturation and survival of the parasites, whereas SmERK are involved in egg production as infected mice had significantly lower egg burdens with female worms presenting underdeveloped ovaries. Furthermore, it was shown that the c-fos transcription factor was overexpressed in parasites submitted to RNAi of SmERK1, SmJNK and SmCaMK2 indicating its putative involvement in gene regulation in this parasite's MAPK signaling cascade. We conclude that MAPKs proteins play important roles in the parasite in vivo survival, being essential for normal development and successful survival and reproduction of the schistosome parasite. Moreover SmERK and SmJNK are potential targets for drug development.

  2. Differential Regulation of Hippocampal IGF-1-Associated Signaling Proteins by Dietary Restriction in Aging Mouse.

    Science.gov (United States)

    Hadem, Ibanylla Kynjai Hynniewta; Sharma, Ramesh

    2017-08-01

    Time-dependent alterations in several biological processes of an organism may be characterized as aging. One of the effects of aging is the decline in cognitive functions. Dietary restriction (DR), an intervention where the consumption of food is lessened but without malnutrition, is a well-established mechanism that has a wide range of important outcomes including improved health span, delayed aging, and extension of lifespan of various species. It also plays a beneficial role in protecting against age-dependent deterioration of cognitive functions, and has neuroprotective properties against neurodegenerative diseases. Insulin-like growth factor (IGF)-1 plays an important role in the regulation of cellular and tissue functions, and relating to the aging process the most important pathway of IGF-1 is the phosphatidylinositol 3-kinase (PI3K) and protein kinase B (Akt/PKB) signaling cascade. Although many have studied the changes in the level of IGF-1 and its effect on neural proliferation, the downstream signaling proteins have not been fully elucidated. Hence in the present investigation, the IGF-1 gene expression and the normal endogenous levels of IGF1R (IGF-1 receptor), PI3K, Akt, pAkt, and pFoxO in the hippocampus of young, adult, and old mice were determined using real-time PCR and Western blot analyses. The effects of DR on these protein levels were also studied. Results showed a decrease in the levels of IGF-1, IGF1R, PI3K, and pAkt, while pFoxO level increased with respect to age. Under DR, these protein levels are maintained in adult mice, but old mice displayed diminished expression levels of these proteins as compared to ad libitum-fed mice. Maintenance of PI3K/Akt pathway results in the phosphorylation of FoxOs, necessary for the enhancement of neural proliferation and survival in adult mice. The down-regulation of IGF-I signaling, as observed in old mice, leads to increasing the activity of FoxO factors that may be important for the neuroprotective

  3. Plasma Signaling Proteins in Persons at Genetic Risk for Alzheimer Disease

    Science.gov (United States)

    Ringman, John M.; Elashoff, David; Geschwind, Daniel H.; Welsh, Brian T.; Gylys, Karen H.; Lee, Cathy; Cummings, Jeffrey L.; Cole, Greg M.

    2013-01-01

    Objective To study the effect of familial Alzheimer disease (FAD) mutations and APOE genotype on plasma signaling protein levels. Design Cross-sectional comparison of plasma levels of 77 proteins measured using multiplex immune assays. Setting A tertiary referral dementia research center. Participants Thirty-three persons from families harboring PSEN1 or APP mutations, aged 19 to 59 years. Main Outcome Measures Protein levels were compared between FAD mutation carriers (MCs) and non-carriers (NCs) and among APOE genotype groups, using multiple linear regression models. Results Twenty-one participants were FAD MCs and 12 were NCs. Six had the APOE ε2/3, 6 had the ε3/4, and 21 had the ε3/3 genotype. Levels of 17 proteins differed among APOE genotype groups, and there were significant interactions between age and APOE genotype for 12 proteins. Plasma levels of apolipoprotein E and superoxide dismutase 1 were highest in the ε2 carriers, lowest in ε4 carriers, and intermediate in the ε3 carriers. Levels of multiple interleukins showed the opposite pattern and, among the ε4 carriers, demonstrated significant negative correlations with age. Although there were no significant differences between FAD MCs and NCs, there were interactions between mutation status and APOE genotype for 13 proteins. Conclusions We found different patterns of inflammatory markers in young and middle-aged persons among APOE genotype groups. The APOE ε4 carriers had the lowest levels of apolipoprotein E. Young ε4 carriers have increased inflammatory markers that diminish with age. We demonstrated altered inflammatory responses in young and middle adulthood in ε4 carriers that may relate to AD risk later in life. PMID:22689192

  4. Plasma signaling proteins in persons at genetic risk for Alzheimer disease: influence of APOE genotype.

    Science.gov (United States)

    Ringman, John M; Elashoff, David; Geschwind, Daniel H; Welsh, Brian T; Gylys, Karen H; Lee, Cathy; Cummings, Jeffrey L; Cole, Greg M

    2012-06-01

    To study the effect of familial Alzheimer disease (FAD) mutations and APOE genotype on plasma signaling protein levels. Cross-sectional comparison of plasma levels of 77 proteins measured using multiplex immune assays. A tertiary referral dementia research center. Thirty-three persons from families harboring PSEN1 or APP mutations, aged 19 to 59 years. Protein levels were compared between FAD mutation carriers (MCs) and noncarriers (NCs) and among APOE genotype groups, using multiple linear regression models. Twenty-one participants were FAD MCs and 12 were NCs. Six had the APOE ε2/3, 6 had the ε3/4, and 21 had the ε3/3 genotype. Levels of 17 proteins differed among APOE genotype groups, and there were significant interactions between age and APOE genotype for 12 proteins. Plasma levels of apolipoprotein E and superoxide dismutase 1 were highest in the ε2 carriers, lowest in ε4 carriers, and intermediate in the ε3 carriers. Levels of multiple interleukins showed the opposite pattern and, among the ε4 carriers, demonstrated significant negative correlations with age. Although there were no significant differences between FAD MCs and NCs, there were interactions between mutation status and APOE genotype for 13 proteins. We found different patterns of inflammatory markers in young and middle-aged persons among APOE genotype groups. The APOE ε4 carriers had the lowest levels of apolipoprotein E. Young ε4 carriers have increased inflammatory markers that diminish with age. We demonstrated altered inflammatory responses in young and middle adulthood in ε4 carriers that may relate to AD risk later in life.

  5. Randomly organized lipids and marginally stable proteins: a coupling of weak interactions to optimize membrane signaling.

    Science.gov (United States)

    Rice, Anne M; Mahling, Ryan; Fealey, Michael E; Rannikko, Anika; Dunleavy, Katie; Hendrickson, Troy; Lohese, K Jean; Kruggel, Spencer; Heiling, Hillary; Harren, Daniel; Sutton, R Bryan; Pastor, John; Hinderliter, Anne

    2014-09-01

    Eukaryotic lipids in a bilayer are dominated by weak cooperative interactions. These interactions impart highly dynamic and pliable properties to the membrane. C2 domain-containing proteins in the membrane also interact weakly and cooperatively giving rise to a high degree of conformational plasticity. We propose that this feature of weak energetics and plasticity shared by lipids and C2 domain-containing proteins enhance a cell's ability to transduce information across the membrane. We explored this hypothesis using information theory to assess the information storage capacity of model and mast cell membranes, as well as differential scanning calorimetry, carboxyfluorescein release assays, and tryptophan fluorescence to assess protein and membrane stability. The distribution of lipids in mast cell membranes encoded 5.6-5.8bits of information. More information resided in the acyl chains than the head groups and in the inner leaflet of the plasma membrane than the outer leaflet. When the lipid composition and information content of model membranes were varied, the associated C2 domains underwent large changes in stability and denaturation profile. The C2 domain-containing proteins are therefore acutely sensitive to the composition and information content of their associated lipids. Together, these findings suggest that the maximum flow of signaling information through the membrane and into the cell is optimized by the cooperation of near-random distributions of membrane lipids and proteins. This article is part of a Special Issue entitled: Interfacially Active Peptides and Proteins. Guest Editors: William C. Wimley and Kalina Hristova. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Characterization of a baculovirus nuclear localization signal domain in the late expression factor 3 protein

    International Nuclear Information System (INIS)

    Au, Victoria; Yu Mei; Carstens, Eric B.

    2009-01-01

    The baculovirus Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) single-stranded DNA binding protein LEF-3 is a multi-functional protein that is required to transport the helicase protein P143 into the nucleus of infected cells where they function to replicate viral DNA. The N-terminal 56 amino acid region of LEF-3 is required for nuclear transport. In this report, we analyzed the effect of site-specific mutagenesis of LEF-3 on its intracellular distribution. Fluorescence microscopy of expression plasmid-transfected cells demonstrated that the residues 28 to 32 formed the core nuclear localization signal, but other adjacent positively-charged residues augmented these sequences. Comparison with other group I Alphabaculoviruses suggested that this core region functionally duplicated residues including 18 and 19. This was demonstrated by the loss of nuclear localization when the equivalent residues (18 to 20) in Choristoneura fumiferana nucleopolyhedrovirus (CfMNPV) LEF-3 were mutated. The AcMNPV LEF-3 nuclear localization domain was also shown to drive nuclear transport in mammalian cells indicating that the protein nuclear import systems in insect and mammalian cells are conserved. We also demonstrated by mutagenesis that two conserved cysteine residues located at 82 and 106 were not essential for nuclear localization or for interaction with P143. However, by using a modified construct of P143 that localized on its own to the nucleus, we demonstrated that a functional nuclear localization domain on LEF-3 was required for interaction between LEF-3 and P143

  7. New pathogenic viruses and novel antiviral drugs

    NARCIS (Netherlands)

    Berkhout, Ben; Eggink, Dirk

    2011-01-01

    The journal Antiviral Research was conceived and born in 1980, and launched in 1981, a time when very few antiviral drugs were around. This 30-year celebration meeting was convened by the publisher Elsevier and chaired by Eric de Clercq (Leuven University), who has acted as editor-in-chief for the

  8. Gestational diabetes is characterized by reduced mitochondrial protein expression and altered calcium signaling proteins in skeletal muscle.

    Directory of Open Access Journals (Sweden)

    Kristen E Boyle

    Full Text Available The rising prevalence of gestational diabetes mellitus (GDM affects up to 18% of pregnant women with immediate and long-term metabolic consequences for both mother and infant. Abnormal glucose uptake and lipid oxidation are hallmark features of GDM prompting us to use an exploratory proteomics approach to investigate the cellular mechanisms underlying differences in skeletal muscle metabolism between obese pregnant women with GDM (OGDM and obese pregnant women with normal glucose tolerance (ONGT. Functional validation was performed in a second cohort of obese OGDM and ONGT pregnant women. Quantitative proteomic analysis in rectus abdominus skeletal muscle tissue collected at delivery revealed reduced protein content of mitochondrial complex I (C-I subunits (NDUFS3, NDUFV2 and altered content of proteins involved in calcium homeostasis/signaling (calcineurin A, α1-syntrophin, annexin A4 in OGDM (n = 6 vs. ONGT (n = 6. Follow-up analyses showed reduced enzymatic activity of mitochondrial complexes C-I, C-III, and C-IV (-60-75% in the OGDM (n = 8 compared with ONGT (n = 10 subjects, though no differences were observed for mitochondrial complex protein content. Upstream regulators of mitochondrial biogenesis and oxidative phosphorylation were not different between groups. However, AMPK phosphorylation was dramatically reduced by 75% in the OGDM women. These data suggest that GDM is associated with reduced skeletal muscle oxidative phosphorylation and disordered calcium homeostasis. These relationships deserve further attention as they may represent novel risk factors for development of GDM and may have implications on the effectiveness of physical activity interventions on both treatment strategies for GDM and for prevention of type 2 diabetes postpartum.

  9. Mitogen-activated protein kinase signaling pathways promote low-density lipoprotein receptor-related protein 1-mediated internalization of beta-amyloid protein in primary cortical neurons.

    Science.gov (United States)

    Yang, Wei-Na; Ma, Kai-Ge; Qian, Yi-Hua; Zhang, Jian-Shui; Feng, Gai-Feng; Shi, Li-Li; Zhang, Zhi-Chao; Liu, Zhao-Hui

    2015-07-01

    Mounting evidence suggests that the pathological hallmarks of Alzheimer's disease (AD) are caused by the intraneuronal accumulation of beta-amyloid protein (Aβ). Reuptake of extracellular Aβ is believed to contribute significantly to the intraneuronal Aβ pool in the early stages of AD. Published reports have claimed that the low-density lipoprotein receptor-related protein 1 (LRP1) mediates Aβ1-42 uptake and lysosomal trafficking in GT1-7 neuronal cells and mouse embryonic fibroblast non-neuronal cells. However, there is no direct evidence supporting the role of LRP1 in Aβ internalization in primary neurons. Our recent study indicated that p38 MAPK and ERK1/2 signaling pathways are involved in regulating α7 nicotinic acetylcholine receptor (α7nAChR)-mediated Aβ1-42 uptake in SH-SY5Y cells. This study was designed to explore the regulation of MAPK signaling pathways on LRP1-mediated Aβ internalization in neurons. We found that extracellular Aβ1-42 oligomers could be internalized into endosomes/lysosomes and mitochondria in cortical neurons. Aβ1-42 and LRP1 were also found co-localized in neurons during Aβ1-42 internalization, and they could form Aβ1-42-LRP1 complex. Knockdown of LRP1 expression significantly decreased neuronal Aβ1-42 internalization. Finally, we identified that p38 MAPK and ERK1/2 signaling pathways regulated the internalization of Aβ1-42 via LRP1. Therefore, these results demonstrated that LRP1, p38 MAPK and ERK1/2 mediated the internalization of Aβ1-42 in neurons and provided evidence that blockade of LRP1 or inhibitions of MAPK signaling pathways might be a potential approach to lowering brain Aβ levels and served a potential therapeutic target for AD. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Aroclor 1254, a developmental neurotoxicant, alters energy metabolism- and intracellular signaling-associated protein networks in rat cerebellum and hippocampus

    International Nuclear Information System (INIS)

    Kodavanti, Prasada Rao S.; Osorio, Cristina; Royland, Joyce E.; Ramabhadran, Ram; Alzate, Oscar

    2011-01-01

    The vast literature on the mode of action of polychlorinated biphenyls (PCBs) indicates that PCBs are a unique model for understanding the mechanisms of toxicity of environmental mixtures of persistent chemicals. PCBs have been shown to adversely affect psychomotor function and learning and memory in humans. Although the molecular mechanisms for PCB effects are unclear, several studies indicate that the disruption of Ca 2+ -mediated signal transduction plays significant roles in PCB-induced developmental neurotoxicity. Culminating events in signal transduction pathways include the regulation of gene and protein expression, which affects the growth and function of the nervous system. Our previous studies showed changes in gene expression related to signal transduction and neuronal growth. In this study, protein expression following developmental exposure to PCB is examined. Pregnant rats (Long Evans) were dosed with 0.0 or 6.0 mg/kg/day of Aroclor-1254 from gestation day 6 through postnatal day (PND) 21, and the cerebellum and hippocampus from PND14 animals were analyzed to determine Aroclor 1254-induced differential protein expression. Two proteins were found to be differentially expressed in the cerebellum following PCB exposure while 18 proteins were differentially expressed in the hippocampus. These proteins are related to energy metabolism in mitochondria (ATP synthase, sub unit β (ATP5B), creatine kinase, and malate dehydrogenase), calcium signaling (voltage-dependent anion-selective channel protein 1 (VDAC1) and ryanodine receptor type II (RyR2)), and growth of the nervous system (dihydropyrimidinase-related protein 4 (DPYSL4), valosin-containing protein (VCP)). Results suggest that Aroclor 1254-like persistent chemicals may alter energy metabolism and intracellular signaling, which might result in developmental neurotoxicity. -- Highlights: ► We performed brain proteomic analysis of rats exposed to the neurotoxicant, Aroclor 1254. ► Cerebellum and

  11. Proteomic analysis of the signaling pathway mediated by the heterotrimeric G? protein Pga1 of Penicillium chrysogenum

    OpenAIRE

    Carrasco-Navarro, Ulises; Vera-Estrella, Rosario; Barkla, Bronwyn J.; Z??iga-Le?n, Eduardo; Reyes-Vivas, Horacio; Fern?ndez, Francisco J.; Fierro, Francisco

    2016-01-01

    Background The heterotrimeric G? protein Pga1-mediated signaling pathway regulates the entire developmental program in Penicillium chrysogenum, from spore germination to the formation of conidia. In addition it participates in the regulation of penicillin biosynthesis. We aimed to advance the understanding of this key signaling pathway using a proteomics approach, a powerful tool to identify effectors participating in signal transduction pathways. Results Penicillium chrysogenum mutants with ...

  12. Hepatitis C Virus and Antiviral Drug Resistance.

    Science.gov (United States)

    Kim, Seungtaek; Han, Kwang-Hyub; Ahn, Sang Hoon

    2016-11-15

    Since its discovery in 1989, hepatitis C virus (HCV) has been intensively investigated to understand its biology and develop effective antiviral therapies. The efforts of the previous 25 years have resulted in a better understanding of the virus, and this was facilitated by the development of in vitro cell culture systems for HCV replication. Antiviral treatments and sustained virological responses have also improved from the early interferon monotherapy to the current all-oral regimens using direct-acting antivirals. However, antiviral resistance has become a critical issue in the treatment of chronic hepatitis C, similar to other chronic viral infections, and retreatment options following treatment failure have become important questions. Despite the clinical challenges in the management of chronic hepatitis C, substantial progress has been made in understanding HCV, which may facilitate the investigation of other closely related flaviviruses and lead to the development of antiviral agents against these human pathogens.

  13. Maize and Arabidopsis ARGOS Proteins Interact with Ethylene Receptor Signaling Complex, Supporting a Regulatory Role for ARGOS in Ethylene Signal Transduction[OPEN

    Science.gov (United States)

    Shi, Jinrui; Wang, Hongyu; Habben, Jeffrey E.

    2016-01-01

    The phytohormone ethylene regulates plant growth and development as well as plant response to environmental cues. ARGOS genes reduce plant sensitivity to ethylene when overexpressed in transgenic Arabidopsis (Arabidopsis thaliana) and maize (Zea mays). A previous genetic study suggested that the endoplasmic reticulum and Golgi-localized maize ARGOS1 targets the ethylene signal transduction components at or upstream of CONSTITUTIVE TRIPLE RESPONSE1, but the mechanism of ARGOS modulating ethylene signaling is unknown. Here, we demonstrate in Arabidopsis that ZmARGOS1, as well as the Arabidopsis ARGOS homolog ORGAN SIZE RELATED1, physically interacts with Arabidopsis REVERSION-TO-ETHYLENE SENSITIVITY1 (RTE1), an ethylene receptor interacting protein that regulates the activity of ETHYLENE RESPONSE1. The protein-protein interaction was also detected with the yeast split-ubiquitin two-hybrid system. Using the same yeast assay, we found that maize RTE1 homolog REVERSION-TO-ETHYLENE SENSITIVITY1 LIKE4 (ZmRTL4) and ZmRTL2 also interact with maize and Arabidopsis ARGOS proteins. Like AtRTE1 in Arabidopsis, ZmRTL4 and ZmRTL2 reduce ethylene responses when overexpressed in maize, indicating a similar mechanism for ARGOS regulating ethylene signaling in maize. A polypeptide fragment derived from ZmARGOS8, consisting of a Pro-rich motif flanked by two transmembrane helices that are conserved among members of the ARGOS family, can interact with AtRTE1 and maize RTL proteins in Arabidopsis. The conserved domain is necessary and sufficient to reduce ethylene sensitivity in Arabidopsis and maize. Overall, these results suggest a physical association between ARGOS and the ethylene receptor signaling complex via AtRTE1 and maize RTL proteins, supporting a role for ARGOS in regulating ethylene perception and the early steps of signal transduction in Arabidopsis and maize. PMID:27268962

  14. Antiviral effect of lithium chloride on infection of cells by canine parvovirus.

    Science.gov (United States)

    Zhou, Pei; Fu, Xinliang; Yan, Zhongshan; Fang, Bo; Huang, San; Fu, Cheng; Hong, Malin; Li, Shoujun

    2015-11-01

    Canine parvovirus type 2 causes significant viral disease in dogs, with high morbidity, high infectivity, and high mortality. Lithium chloride is a potential antiviral drug for viruses. We determined the antiviral effect of Lithium Chloride on canine parvovirus type 2 in feline kidney cells. The viral DNA and proteins of canine parvovirus were suppressed in a dose-dependent manner by lithium chloride. Further investigation verified that viral entry into cells was inhibited in a dose-dependent manner by lithium chloride. These results indicated that lithium chloride could be a potential antiviral drug for curing dogs with canine parvovirus infection. The specific steps of canine parvovirus entry into cells that are affected by lithium chloride and its antiviral effect in vivo should be explored in future studies.

  15. Antiviral Potential of Algae Polysaccharides Isolated from Marine Sources: A Review

    Directory of Open Access Journals (Sweden)

    Azin Ahmadi

    2015-01-01

    Full Text Available From food to fertilizer, algal derived products are largely employed in assorted industries, including agricultural, biomedical, food, and pharmaceutical industries. Among different chemical compositions isolated from algae, polysaccharides are the most well-established compounds, which were subjected to a variety of studies due to extensive bioactivities. Over the past few decades, the promising results for antiviral potential of algae-derived polysaccharides have advocated them as inordinate candidates for pharmaceutical research. Numerous studies have isolated various algal polysaccharides possessing antiviral activities, including carrageenan, alginate, fucan, laminaran, and naviculan. In addition, different mechanisms of action have been reported for these polysaccharides, such as inhibiting the binding or internalization of virus into the host cells or suppressing DNA replication and protein synthesis. This review strives for compiling previous antiviral studies of algae-derived polysaccharides and their mechanism of action towards their development as natural antiviral agents for future investigations.

  16. Fluorescent protein pair emit intracellular FRET signal suitable for FACS screening

    International Nuclear Information System (INIS)

    Johansson, Daniel X.; Brismar, Hjalmar; Persson, Mats A.A.

    2007-01-01

    The fluorescent proteins ECFP and HcRed were shown to give an easily resolved FRET-signal when expressed as a fusion inside mammalian cells. HeLa-tat cells expressing ECFP, pHcRed, or the fusion protein pHcRed-ECFP were analyzed by flow cytometry after excitation of ECFP. Cells expressing HcRed-ECFP, or ECFP and HcRed, were mixed and FACS-sorted for FRET positive cells: HcRed-ECFP cells were greatly enriched (72 times). Next, cloned human antibodies were fused with ECFP and expressed anchored to the ER membrane. Their cognate antigens (HIV-1 gp120 or gp41) were fused to HcRed and co-expressed in the ER. An increase of 13.5 ± 1.5% (mean ± SEM) and 8.0 ± 0.7% in ECFP fluorescence for the specific antibodies reacting with gp120 or gp41, respectively, was noted after photobleaching. A positive control (HcRed-ECFP) gave a 14.8 ± 2.6% increase. Surprisingly, the unspecific antibody (anti-TT) showed 12.1 ± 1.1% increase, possibly because overexpression in the limited ER compartment gave false FRET signals

  17. Nicotinic Acid Increases Adiponectin Secretion from Differentiated Bovine Preadipocytes through G-Protein Coupled Receptor Signaling

    Directory of Open Access Journals (Sweden)

    Christina Kopp

    2014-11-01

    Full Text Available The transition period in dairy cows (3 weeks prepartum until 3 weeks postpartum is associated with substantial mobilization of energy stores, which is often associated with metabolic diseases. Nicotinic acid (NA is an antilipolytic and lipid-lowering compound used to treat dyslipidaemia in humans, and it also reduces non-esterified fatty acids in cattle. In mice the G-protein coupled receptor 109A (GPR109A ligand NA positively affects the secretion of adiponectin, an important modulator of glucose and fat metabolism. In cattle, the corresponding data linking NA to adiponectin are missing. Our objective was to examine the effects of NA on adiponectin and AMPK protein abundance and the expression of mRNAs of related genes such as chemerin, an adipokine that enhances adiponectin secretion in vitro. Differentiated bovine adipocytes were incubated with pertussis toxin (PTX to verify the involvement of GPR signaling, and treated with 10 or 15 µM NA for 12 or 24 h. NA increased adiponectin concentrations (p ≤ 0.001 and the mRNA abundances of GPR109A (p ≤ 0.05 and chemerin (p ≤ 0.01. Pre-incubation with PTX reduced the adiponectin response to NA (p ≤ 0.001. The NA-stimulated secretion of adiponectin and the mRNA expression of chemerin in the bovine adipocytes were suggestive of GPR signaling-dependent improved insulin sensitivity and/or adipocyte metabolism in dairy cows.

  18. An unusual spliced variant of DELLA protein, a negative regulator of gibberellin signaling, in lettuce.

    Science.gov (United States)

    Sawada, Yoshiaki; Umetsu, Asami; Komatsu, Yuki; Kitamura, Jun; Suzuki, Hiroyuki; Asami, Tadao; Fukuda, Machiko; Honda, Ichiro; Mitsuhashi, Wataru; Nakajima, Masatoshi; Toyomasu, Tomonobu

    2012-01-01

    DELLA proteins are negative regulators of the signaling of gibberellin (GA), a phytohormone regulating plant growth. DELLA degradation is triggered by its interaction with GID1, a soluble GA receptor, in the presence of bioactive GA. We isolated cDNA from a spliced variant of LsDELLA1 mRNA in lettuce, and named it LsDELLA1sv. It was deduced that LsDELLA1sv encodes truncated LsDELLA1, which has DELLA and VHYNP motifs at the N terminus but lacks part of the C-terminal GRAS domain. The recombinant LsDELLA1sv protein interacted with both Arabidopsis GID1 and lettuce GID1s in the presence of GA. A yeast two-hybrid assay suggested that LsDELLA1sv interacted with LsDELLA1. The ratio of LsDELLA1sv to LsDELLA1 transcripts was higher in flower samples at the late reproductive stage and seed samples (dry seeds and imbibed seeds) than in the other organ samples examined. This study suggests that LsDELLA1sv is a possible modulator of GA signaling in lettuce.

  19. PASA - A Program for Automated Protein NMR Backbone Signal Assignment by Pattern-Filtering Approach

    International Nuclear Information System (INIS)

    Xu Yizhuang; Wang Xiaoxia; Yang Jun; Vaynberg, Julia; Qin Jun

    2006-01-01

    We present a new program, PASA (Program for Automated Sequential Assignment), for assigning protein backbone resonances based on multidimensional heteronuclear NMR data. Distinct from existing programs, PASA emphasizes a per-residue-based pattern-filtering approach during the initial stage of the automated 13 C α and/or 13 C β chemical shift matching. The pattern filter employs one or multiple constraints such as 13 C α /C β chemical shift ranges for different amino acid types and side-chain spin systems, which helps to rule out, in a stepwise fashion, improbable assignments as resulted from resonance degeneracy or missing signals. Such stepwise filtering approach substantially minimizes early false linkage problems that often propagate, amplify, and ultimately cause complication or combinatorial explosion of the automation process. Our program (http://www.lerner.ccf.org/moleccard/qin/) was tested on four representative small-large sized proteins with various degrees of resonance degeneracy and missing signals, and we show that PASA achieved the assignments efficiently and rapidly that are fully consistent with those obtained by laborious manual protocols. The results demonstrate that PASA may be a valuable tool for NMR-based structural analyses, genomics, and proteomics

  20. The potency of STAT (signal transducers and activators of transcription) 3 protein as growth promoter for chicken

    Science.gov (United States)

    Ma'ruf, Anwar; Iswati, Sri; Hidajati, Nove; Damayanti, Ratna

    2017-09-01

    The long-term objective of this study was to produce STAT synthetic protein in chicken during growth period resulting from the increase of growth hormone (GH) as growth promoter. This study used ten male chicken Lohman from PT. Multibreeder Indonesia. The chicken were kept within batteried cage, with a capacity of one chicken in each cage. The chickens were fed twice a day, at 6 a.m. and 6 p.m. with the amount of feed 10% less than standard. On day 21 the chicken were slaughtered to obtain the samples, i.e., adipose, liver and muscles for the following examinations (1) isolation of STAT-3 signaling protein from adipose, liver and muscles of the chicken, (2) analysis of STAT-3 signaling protein using SDS-PAGE method, and (3) identification of STAT-3 signaling protein using Western blot method by means of protein detection using electrophoresis with polyacrylamide gels. Results of examination on protein in hepatic, muscle and adipose of chickens in growth period revealed that STAT protein was positively present in those tissues. This finding was followed-up with SDS-PAGE examination, from which we found the presence of protein band between the markers of 116 kDa and 14.4 kDa. The protein band was supposedly the STAT-3 protein. To prove that protein band formed was the STAT-3, Western blot examination was conducted using rabbit polyclonal antibody STAT-3. The result showed the formation of the protein band, indicating the presence of reaction between antigen (STAT-3 protein) and STAT-3 protein antibody. In conclusion, STAT-3 protein is present in hepatic, muscular, and adipose tissues, with molecular weight of 59.4 kDa.

  1. Creating and analyzing pathway and protein interaction compendia for modelling signal transduction networks

    Directory of Open Access Journals (Sweden)

    Kirouac Daniel C

    2012-05-01

    Full Text Available Abstract Background Understanding the information-processing capabilities of signal transduction networks, how those networks are disrupted in disease, and rationally designing therapies to manipulate diseased states require systematic and accurate reconstruction of network topology. Data on networks central to human physiology, such as the inflammatory signalling networks analyzed here, are found in a multiplicity of on-line resources of pathway and interactome databases (Cancer CellMap, GeneGo, KEGG, NCI-Pathway Interactome Database (NCI-PID, PANTHER, Reactome, I2D, and STRING. We sought to determine whether these databases contain overlapping information and whether they can be used to construct high reliability prior knowledge networks for subsequent modeling of experimental data. Results We have assembled an ensemble network from multiple on-line sources representing a significant portion of all machine-readable and reconcilable human knowledge on proteins and protein interactions involved in inflammation. This ensemble network has many features expected of complex signalling networks assembled from high-throughput data: a power law distribution of both node degree and edge annotations, and topological features of a “bow tie” architecture in which diverse pathways converge on a highly conserved set of enzymatic cascades focused around PI3K/AKT, MAPK/ERK, JAK/STAT, NFκB, and apoptotic signaling. Individual pathways exhibit “fuzzy” modularity that is statistically significant but still involving a majority of “cross-talk” interactions. However, we find that the most widely used pathway databases are highly inconsistent with respect to the actual constituents and interactions in this network. Using a set of growth factor signalling networks as examples (epidermal growth factor, transforming growth factor-beta, tumor necrosis factor, and wingless, we find a multiplicity of network topologies in which receptors couple to downstream

  2. Structural basis for different phosphoinositide specificities of the PX domains of sorting nexins regulating G-protein signaling.

    Science.gov (United States)

    Mas, Caroline; Norwood, Suzanne J; Bugarcic, Andrea; Kinna, Genevieve; Leneva, Natalya; Kovtun, Oleksiy; Ghai, Rajesh; Ona Yanez, Lorena E; Davis, Jasmine L; Teasdale, Rohan D; Collins, Brett M

    2014-10-10

    Sorting nexins (SNXs) or phox homology (PX) domain containing proteins are central regulators of cell trafficking and signaling. A subfamily of PX domain proteins possesses two unique PX-associated domains, as well as a regulator of G protein-coupled receptor signaling (RGS) domain that attenuates Gαs-coupled G protein-coupled receptor signaling. Here we delineate the structural organization of these RGS-PX proteins, revealing a protein family with a modular architecture that is conserved in all eukaryotes. The one exception to this is mammalian SNX19, which lacks the typical RGS structure but preserves all other domains. The PX domain is a sensor of membrane phosphoinositide lipids and we find that specific sequence alterations in the PX domains of the mammalian RGS-PX proteins, SNX13, SNX14, SNX19, and SNX25, confer differential phosphoinositide binding preferences. Although SNX13 and SNX19 PX domains bind the early endosomal lipid phosphatidylinositol 3-phosphate, SNX14 shows no membrane binding at all. Crystal structures of the SNX19 and SNX14 PX domains reveal key differences, with alterations in SNX14 leading to closure of the binding pocket to prevent phosphoinositide association. Our findings suggest a role for alternative membrane interactions in spatial control of RGS-PX proteins in cell signaling and trafficking. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  3. Blunted hypothalamic ghrelin signaling reduces diet intake in rats fed a low-protein diet in late pregnancy

    Science.gov (United States)

    Diet intake in pregnant rats fed a low-protein (LP) diet was significantly reduced during late pregnancy despite elevated plasma levels of ghrelin. In this study, we hypothesized that ghrelin signaling in the hypothalamus is blunted under a low-protein diet condition and therefore, it does not stimu...

  4. Phosphorylation of Icariin Can Alleviate the Oxidative Stress Caused by the Duck Hepatitis Virus A through Mitogen-Activated Protein Kinases Signaling Pathways

    Directory of Open Access Journals (Sweden)

    Wen Xiong

    2017-09-01

    Full Text Available The duck virus hepatitis (DVH caused by the duck hepatitis virus A (DHAV has produced extensive economic losses to the duck industry. The currently licensed commercial vaccine has shown some defects and does not completely prevent the DVH. Accordingly, a new alternative treatment for this disease is urgently needed. Previous studies have shown that icariin (ICA and its phosphorylated derivative (pICA possessed good anti-DHAV effects through direct and indirect antiviral pathways, such as antioxidative stress. But the antioxidant activity showed some differences between ICA and pICA. The aim of this study is to prove that ICA and pICA attenuate oxidative stress caused by DHAV in vitro and in vivo, and to investigate their mechanism of action to explain their differences in antioxidant activities. In vivo, the dynamic deaths, oxidative evaluation indexes and hepatic pathological change scores were detected. When was added the hinokitiol which showed the pro-oxidative effect as an intervention method, pICA still possessed more treatment effect than ICA. The strong correlation between mortality and oxidative stress proves that ICA and pICA alleviate oxidative stress caused by DHAV. This was also demonstrated by the addition of hydrogen peroxide (H2O2 as an intervention method in vitro. pICA can be more effective than ICA to improve duck embryonic hepatocytes (DEHs viability and reduce the virulence of DHAV. The strong correlation between TCID50 and oxidative stress demonstrates that ICA and pICA can achieve anti-DHAV effects by inhibiting oxidative stress. In addition, the superoxide dismutase (SOD and glutathione peroxidase (GSH-Px of ICA and pICA showed significant difference. pICA could significantly inhibit the phosphorylation of p38, extra cellular signal regulated Kinase (ERK 1/2 and c-Jun N-terminal kinase (JNK, which were related to mitogen-activated protein kinases (MAPKs signaling pathways. Ultimately, compared to ICA, pICA exhibited more

  5. An Alzheimer Disease-linked Rare Mutation Potentiates Netrin Receptor Uncoordinated-5C-induced Signaling That Merges with Amyloid β Precursor Protein Signaling.

    Science.gov (United States)

    Hashimoto, Yuichi; Toyama, Yuka; Kusakari, Shinya; Nawa, Mikiro; Matsuoka, Masaaki

    2016-06-03

    A missense mutation (T835M) in the uncoordinated-5C (UNC5C) netrin receptor gene increases the risk of late-onset Alzheimer disease (AD) and also the vulnerability of neurons harboring the mutation to various insults. The molecular mechanisms underlying T835M-UNC5C-induced death remain to be elucidated. In this study, we show that overexpression of wild-type UNC5C causes low-grade death, which is intensified by an AD-linked mutation T835M. An AD-linked survival factor, calmodulin-like skin protein (CLSP), and a natural ligand of UNC5C, netrin1, inhibit this death. T835M-UNC5C-induced neuronal cell death is mediated by an intracellular death-signaling cascade, consisting of death-associated protein kinase 1/protein kinase D/apoptosis signal-regulating kinase 1 (ASK1)/JNK/NADPH oxidase/caspases, which merges at ASK1 with a death-signaling cascade, mediated by amyloid β precursor protein (APP). Notably, netrin1 also binds to APP and partially inhibits the death-signaling cascade, induced by APP. These results may provide new insight into the amyloid β-independent pathomechanism of AD. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  6. Rice early flowering1, a CKI, phosphorylates DELLA protein SLR1 to negatively regulate gibberellin signalling.

    Science.gov (United States)

    Dai, Cheng; Xue, Hong-Wei

    2010-06-02

    The plant hormone gibberellin (GA) is crucial for multiple aspects of plant growth and development. To study the relevant regulatory mechanisms, we isolated a rice mutant earlier flowering1, el1, which is deficient in a casein kinase I that has critical roles in both plants and animals. el1 had an enhanced GA response, consistent with the suppression of EL1 expression by exogenous GA(3). Biochemical characterization showed that EL1 specifically phosphorylates the rice DELLA protein SLR1, proving a direct evidence for SLR1 phosphorylation. Overexpression of SLR1 in wild-type plants caused a severe dwarf phenotype, which was significantly suppressed by EL1 deficiency, indicating the negative effect of SLR1 on GA signalling requires the EL1 function. Further studies showed that the phosphorylation of SLR1 is important for maintaining its activity and stability, and mutation of the candidate phosphorylation site of SLR1 results in the altered GA signalling. This study shows EL1 a novel and key regulator of the GA response and provided important clues on casein kinase I activities in GA signalling and plant development.

  7. FLOWERING LOCUS T protein may act as the long-distance florigenic signal in the cucurbits.

    Science.gov (United States)

    Lin, Ming-Kuem; Belanger, Helene; Lee, Young-Jin; Varkonyi-Gasic, Erika; Taoka, Ken-Ichiro; Miura, Eriko; Xoconostle-Cázares, Beatriz; Gendler, Karla; Jorgensen, Richard A; Phinney, Brett; Lough, Tony J; Lucas, William J

    2007-05-01

    Cucurbita moschata, a cucurbit species responsive to inductive short-day (SD) photoperiods, and Zucchini yellow mosaic virus (ZYMV) were used to test whether long-distance movement of FLOWERING LOCUS T (FT) mRNA or FT is required for floral induction. Ectopic expression of FT by ZYMV was highly effective in mediating floral induction of long-day (LD)-treated plants. Moreover, the infection zone of ZYMV was far removed from floral meristems, suggesting that FT transcripts do not function as the florigenic signal in this system. Heterografting demonstrated efficient transmission of a florigenic signal from flowering Cucurbita maxima stocks to LD-grown C. moschata scions. Real-time RT-PCR performed on phloem sap collected from C. maxima stocks detected no FT transcripts, whereas mass spectrometry of phloem sap proteins revealed the presence of Cm-FTL1 and Cm-FTL2. Importantly, studies on LD- and SD-treated C. moschata plants established that Cmo-FTL1 and Cmo-FTL2 are regulated by photoperiod at the level of movement into the phloem and not by transcription. Finally, mass spectrometry of florally induced heterografted C. moschata scions revealed that C. maxima FT, but not FT mRNA, crossed the graft union in the phloem translocation stream. Collectively, these studies are consistent with FT functioning as a component of the florigenic signaling system in the cucurbits.

  8. Arabidopsis scaffold protein RACK1A modulates rare sugar D-allose regulated gibberellin signaling.

    Science.gov (United States)

    Fennell, Herman; Olawin, Abdulquadri; Mizanur, Rahman M; Izumori, Ken; Chen, Jin-Gui; Ullah, Hemayet

    2012-11-01

    As energy sources and structural components, sugars are the central regulators of plant growth and development. In addition to the abundant natural sugars in plants, more than 50 different kinds of rare sugars exist in nature, several of which show distinct roles in plant growth and development. Recently, one of the rare sugars, D-allose, an epimer of D-glucose at C3, is found to suppress plant hormone gibberellin (GA) signaling in rice. Scaffold protein RACK1A in the model plant Arabidopsis is implicated in the GA pathway as rack1a knockout mutants show insensitivity to GA in GA-induced seed germination. Using genetic knockout lines and a reporter gene, the functional role of RACK1A in the D-allose pathway was investigated. It was found that the rack1a knockout seeds showed hypersensitivity to D-allose-induced inhibition of seed germination, implicating a role for RACK1A in the D-allose mediated suppression of seed germination. On the other hand, a functional RACK1A in the background of the double knockout mutations in the other two RACK1 isoforms, rack1b/rack1c, showed significant resistance to the D-allose induced inhibition of seed germination. The collective results implicate the RACK1A in the D-allose mediated seed germination inhibition pathway. Elucidation of the rare sugar signaling mechanism will help to advance understanding of this less studied but important cellular signaling pathway.

  9. The Hepatitis B Virus X Protein Elevates Cytosolic Calcium Signals by Modulating Mitochondrial Calcium Uptake

    Science.gov (United States)

    Yang, Bei

    2012-01-01

    Chronic hepatitis B virus (HBV) infections are associated with the development of hepatocellular carcinoma (HCC). The HBV X protein (HBx) is thought to play an important role in the development of HBV-associated HCC. One fundamental HBx function is elevation of cytosolic calcium signals; this HBx activity has been linked to HBx stimulation of cell proliferation and transcription pathways, as well as HBV replication. Exactly how HBx elevates cytosolic calcium signals is not clear. The studies described here show that HBx stimulates calcium entry into cells, resulting in an increased plateau level of inositol 1,4,5-triphosphate (IP3)-linked calcium signals. This increased calcium plateau can be inhibited by blocking mitochondrial calcium uptake and store-operated calcium entry (SOCE). Blocking SOCE also reduced HBV replication. Finally, these studies also demonstrate that there is increased mitochondrial calcium uptake in HBx-expressing cells. Cumulatively, these studies suggest that HBx can increase mitochondrial calcium uptake and promote increased SOCE to sustain higher cytosolic calcium and stimulate HBV replication. PMID:22031934

  10. Activation of GABAB receptors inhibits protein kinase B /Glycogen Synthase Kinase 3 signaling

    Directory of Open Access Journals (Sweden)

    Lu Frances Fangjia

    2012-11-01

    Full Text Available Abstract Accumulated evidence has suggested that potentiation of cortical GABAergic inhibitory neurotransmission may be a key mechanism in the treatment of schizophrenia. However, the downstream molecular mechanisms related to GABA potentiation remain unexplored. Recent studies have suggested that dopamine D2 receptor antagonists, which are used in the clinical treatment of schizophrenia, modulate protein kinase B (Akt/glycogen synthase kinase (GSK-3 signaling. Here we report that activation of GABAB receptors significantly inhibits Akt/GSK-3 signaling in a β-arrestin-dependent pathway. Agonist stimulation of GABAB receptors enhances the phosphorylation of Akt (Thr-308 and enhances the phosphorylation of GSK-3α (Ser-21/β (Ser-9 in both HEK-293T cells expressing GABAB receptors and rat hippocampal slices. Furthermore, knocking down the expression of β-arrestin2 using siRNA abolishes the GABAB receptor-mediated modulation of GSK-3 signaling. Our data may help to identify potentially novel targets through which GABAB receptor agents may exert therapeutic effects in the treatment of schizophrenia.

  11. Indian hedgehog signaling triggers Nkx3.2 protein degradation during chondrocyte maturation

    Science.gov (United States)

    Choi, Seung-Won; Jeong, Da-Un; Kim, Jeong-Ah; Lee, Boyoung; Joeng, Kyu Sang; Long, Fanxin; Kim, Dae-Won

    2015-01-01

    The Indian hedgehog (Ihh) pathway plays an essential role in facilitating chondrocyte hypertrophy and bone formation during skeletal development. Nkx3.2 is initially induced in chondrocyte precursor cells, maintained in early-stage chondrocytes, and down-regulated in terminal-stage chondrocytes. Consistent with these expression patterns, Nkx3.2 has been shown to enhance chondrocyte differentiation and cell survival, while inhibiting chondrocyte hypertrophy and apoptosis. Thus, in this work, we investigate whether Nkx3.2, an early stage chondrogenic factor, can be regulated by Ihh, a key regulator for chondrocyte hypertrophy. Here, we show that Ihh signaling can induce proteasomal degradation of Nkx3.2. In addition, we found that Ihh can suppress levels of Lrp (Wnt co-receptor) and Sfrp (Wnt antagonist) expression, which, in turn, may selectively enhance Lrp-independent non-canonical Wnt pathways in chondrocyte. In agreement with these findings, Ihh-induced Nkx3.2 degradation requires Wnt5a, which is capable of triggering Nkx3.2 degradation. Finally, we found that Nkx3.2 protein levels in chondrocytes are remarkably elevated in mice defective in Ihh signaling by deletion of either Ihh or Smoothened. Thus, these results suggest that Ihh/Wnt5a signaling may play a role in negative regulation of Nkx3.2 for appropriate progression of chondrocyte hypertrophy during chondrogenesis. PMID:22507129

  12. Isolation and structure–function characterization of a signaling-active rhodopsin–G protein complex

    Science.gov (United States)

    Gao, Yang; Westfield, Gerwin; Erickson, Jon W.; Cerione, Richard A.; Skiniotis, Georgios; Ramachandran, Sekar

    2017-01-01

    The visual photo-transduction cascade is a prototypical G protein–coupled receptor (GPCR) signaling system, in which light-activated rhodopsin (Rho*) is the GPCR catalyzing the exchange of GDP for GTP on the heterotrimeric G protein transducin (GT). This results in the dissociation of GT into its component αT–GTP and β1γ1 subunit complex. Structural information for the Rho*–GT complex will be essential for understanding the molecular mechanism of visual photo-transduction. Moreover, it will shed light on how GPCRs selectively couple to and activate their G protein signaling partners. Here, we report on the preparation of a stable detergent-solubilized complex between Rho* and a heterotrimer (GT*) comprising a GαT/Gαi1 chimera (αT*) and β1γ1. The complex was formed on native rod outer segment membranes upon light activation, solubilized in lauryl maltose neopentyl glycol, and purified with a combination of affinity and size-exclusion chromatography. We found that the complex is fully functional and that the stoichiometry of Rho* to GαT* is 1:1. The molecular weight of the complex was calculated from small-angle X-ray scattering data and was in good agreement with a model consisting of one Rho* and one GT*. The complex was visualized by negative-stain electron microscopy, which revealed an architecture similar to that of the β2-adrenergic receptor–GS complex, including a flexible αT* helical domain. The stability and high yield of the purified complex should allow for further efforts toward obtaining a high-resolution structure of this important signaling complex. PMID:28655769

  13. D1 dopamine receptor signaling is modulated by the R7 RGS protein EAT-16 and the R7 binding protein RSBP-1 in Caenoerhabditis elegans motor neurons.

    Directory of Open Access Journals (Sweden)

    Khursheed A Wani

    Full Text Available Dopamine signaling modulates voluntary movement and reward-driven behaviors by acting through G protein-coupled receptors in striatal neurons, and defects in dopamine signaling underlie Parkinson's disease and drug addiction. Despite the importance of understanding how dopamine modifies the activity of striatal neurons to control basal ganglia output, the molecular mechanisms that control dopamine signaling remain largely unclear. Dopamine signaling also controls locomotion behavior in Caenorhabditis elegans. To better understand how dopamine acts in the brain we performed a large-scale dsRNA interference screen in C. elegans for genes required for endogenous dopamine signaling and identified six genes (eat-16, rsbp-1, unc-43, flp-1, grk-1, and cat-1 required for dopamine-mediated behavior. We then used a combination of mutant analysis and cell-specific transgenic rescue experiments to investigate the functional interaction between the proteins encoded by two of these genes, eat-16 and rsbp-1, within single cell types and to examine their role in the modulation of dopamine receptor signaling. We found that EAT-16 and RSBP-1 act together to modulate dopamine signaling and that while they are coexpressed with both D1-like and D2-like dopamine receptors, they do not modulate D2 receptor signaling. Instead, EAT-16 and RSBP-1 act together to selectively inhibit D1 dopamine receptor signaling in cholinergic motor neurons to modulate locomotion behavior.