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Sample records for akt phosphorylation sites

  1. Interaction of hookworm 14-3-3 with the forkhead transcription factor DAF-16 requires intact Akt phosphorylation sites

    Directory of Open Access Journals (Sweden)

    Hawdon John M

    2009-04-01

    Full Text Available Abstract Background Third-stage infective larvae (L3 of hookworms are in an obligatory state of developmental arrest that ends upon entering the definitive host, where they receive a signal that re-activates development. Recovery from the developmentally arrested dauer stage of Caenorhabditis elegans is analogous to the resumption of development during hookworm infection. Insulin-like signaling (ILS mediates recovery from arrest in C. elegans and activation of hookworm dauer L3. In C. elegans, phosphorylation of the forkhead transcription factor DAF-16 in response to ILS creates binding cites for the 14-3-3 protein Ce-FTT-2, which translocates DAF-16 out of the nucleus, resulting in resumption of reproductive development. Results To determine if hookworm 14-3-3 proteins play a similar role in L3 activation, hookworm FTT-2 was identified and tested for its ability to interact with A. caninum DAF-16 in vitro. The Ac-FTT-2 amino acid sequence was 91% identical to the Ce-FTT-2, and was most closely related to FTT-2 from other nematodes. Ac-FTT-2 was expressed in HEK 293T cells, and was recognized by an antibody against human 14-3-3β isoform. Reciprocal co-immunoprecipitations using anti-epitope tag antibodies indicated that Ac-FTT-2 interacts with Ac-DAF-16 when co-expressed in serum-stimulated HEK 293T cells. This interaction requires intact Akt consensus phosphorylation sites at serine107 and threonine312, but not serine381. Ac-FTT-2 was undetectable by Western blot in excretory/secretory products from serum-stimulated (activated L3 or adult A. caninum. Conclusion The results indicate that Ac-FTT-2 interacts with DAF-16 in a phosphorylation-site dependent manner, and suggests that Ac-FTT-2 mediates activation of L3 by binding Ac-DAF-16 during hookworm infection.

  2. Akt2 influences glycogen synthase activity in human skeletal muscle through regulation of NH2-terminal (sites 2+2a) phosphorylation

    DEFF Research Database (Denmark)

    Friedrichsen, Martin; Birk, Jesper Bratz; Richter, Erik;

    2013-01-01

    was positively associated with pAkt-T308 (P=0.01) and Akt2 activity (P=0.04), but not pAkt-S473 or IRS-1-PI3K activity. Furthermore, pAkt-T308 and Akt2 activity were negatively associated with NH(2)-terminal GS phosphorylation (P=0.001 for both), which in turn was negatively associated with insulin-stimulated GS...

  3. A mathematical model of phosphorylation AKT in Acute Myeloid Leukemia

    Science.gov (United States)

    Adi, Y. A.; Kusumo, F. A.; Aryati, L.; Hardianti, M. S.

    2016-04-01

    In this paper we consider a mathematical model of PI3K/AKT signaling pathways in phosphorylation AKT. PI3K/AKT pathway is an important mediator of cytokine signaling implicated in regulation of hematopoiesis. Constitutive activation of PI3K/AKT signaling pathway has been observed in Acute Meyloid Leukemia (AML) it caused by the mutation of Fms-like Tyrosine Kinase 3 in internal tandem duplication (FLT3-ITD), the most common molecular abnormality associated with AML. Depending upon its phosphorylation status, protein interaction, substrate availability, and localization, AKT can phosphorylate or inhibite numerous substrates in its downstream pathways that promote protein synthesis, survival, proliferation, and metabolism. Firstly, we present a mass action ordinary differential equation model describing AKT double phosphorylation (AKTpp) in a system with 11 equations. Finally, under the asumtion enzyme catalyst constant and steady state equilibrium, we reduce the system in 4 equation included Michaelis Menten constant. Simulation result suggested that a high concentration of PI3K and/or a low concentration of phospatase increased AKTpp activation. This result also indicates that PI3K is a potential target theraphy in AML.

  4. Akt-dependent Girdin phosphorylation regulates repair processes after acute myocardial infarction.

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    Hayano, Shinji; Takefuji, Mikito; Maeda, Kengo; Noda, Tomonori; Ichimiya, Hitoshi; Kobayashi, Koichi; Enomoto, Atsushi; Asai, Naoya; Takahashi, Masahide; Murohara, Toyoaki

    2015-11-01

    Myocardial infarction is a leading cause of death, and cardiac rupture following myocardial infarction leads to extremely poor prognostic feature. A large body of evidence suggests that Akt is involved in several cardiac diseases. We previously reported that Akt-mediated Girdin phosphorylation is essential for angiogenesis and neointima formation. The role of Girdin expression and phosphorylation in myocardial infarction, however, is not understood. Therefore, we employed Girdin-deficient mice and Girdin S1416A knock-in (Girdin(SA/SA)) mice, replacing the Akt phosphorylation site with alanine, to address this question. We found that Girdin was expressed and phosphorylated in cardiac fibroblasts in vitro and that its phosphorylation was crucial for the proliferation and migration of cardiac fibroblasts. In vivo, Girdin was localized in non-cardiomyocyte interstitial cells and phosphorylated in α-smooth muscle actin-positive cells, which are likely to be cardiac myofibroblasts. In an acute myocardial infarction model, Girdin(SA/SA) suppressed the accumulation and proliferation of cardiac myofibroblasts in the infarcted area. Furthermore, lower collagen deposition in Girdin(SA/SA) mice impaired cardiac repair and resulted in increased mortality attributed to cardiac rupture. These findings suggest an important role of Girdin phosphorylation at serine 1416 in cardiac repair after acute myocardial infarction and provide insights into the complex mechanism of cardiac rupture through the Akt/Girdin-mediated regulation of cardiac myofibroblasts.

  5. SIN1/MIP1 maintains rictor-mTOR complex integrity and regulates Akt phosphorylation and substrate specificity.

    Science.gov (United States)

    Jacinto, Estela; Facchinetti, Valeria; Liu, Dou; Soto, Nelyn; Wei, Shiniu; Jung, Sung Yun; Huang, Qiaojia; Qin, Jun; Su, Bing

    2006-10-01

    Mammalian target of rapamycin (mTOR) controls cell growth and proliferation via the raptor-mTOR (TORC1) and rictor-mTOR (TORC2) protein complexes. Recent biochemical studies suggested that TORC2 is the elusive PDK2 for Akt/PKB Ser473 phosphorylation in the hydrophobic motif. Phosphorylation at Ser473, along with Thr308 of its activation loop, is deemed necessary for Akt function, although the regulatory mechanisms and physiological importance of each phosphorylation site remain to be fully understood. Here, we report that SIN1/MIP1 is an essential TORC2/PDK2 subunit. Genetic ablation of sin1 abolished Akt-Ser473 phosphorylation and disrupted rictor-mTOR interaction but maintained Thr308 phosphorylation. Surprisingly, defective Ser473 phosphorylation affected only a subset of Akt targets in vivo, including FoxO1/3a, while other Akt targets, TSC2 and GSK3, and the TORC1 effectors, S6K and 4E-BP1, were unaffected. Our findings reveal that the SIN1-rictor-mTOR function in Akt-Ser473 phosphorylation is required for TORC2 function in cell survival but is dispensable for TORC1 function. PMID:16962653

  6. Protein Kinase B/Akt Binds and Phosphorylates PED/PEA-15, Stabilizing Its Antiapoptotic Action

    OpenAIRE

    Trencia, Alessandra; Perfetti, Anna; Cassese, Angela; Vigliotta, Giovanni; Miele, Claudia; Oriente, Francesco; Santopietro, Stefania; Giacco, Ferdinando; Condorelli, Gerolama; Formisano, Pietro; Beguinot, Francesco

    2003-01-01

    The antiapoptotic protein PED/PEA-15 features an Akt phosphorylation motif upstream from Ser116. In vitro, recombinant PED/PEA-15 was phosphorylated by Akt with a stoichiometry close to 1. Based on Western blotting with specific phospho-Ser116 PED/PEA-15 antibodies, Akt phosphorylation of PED/PEA-15 occurred mainly at Ser116. In addition, a mutant of PED/PEA-15 featuring the substitution of Ser116→Gly (PEDS116→G) showed 10-fold-decreased phosphorylation by Akt. In intact 293 cells, Akt also i...

  7. Does progesterone show neuroprotective effects on traumatic brain injury through increasing phosphorylation of Akt in the hippocampus?

    Institute of Scientific and Technical Information of China (English)

    Richard Justin Garling; Lora Talley Watts; Shane Sprague; Lauren Fletcher; David F Jimenez; Murat Digicaylioglu

    2014-01-01

    There are currently no federally approved neuroprotective agents to treat traumatic brain injury. Progesterone, a hydrophobic steroid hormone, has been shown in recent studies to exhibit neu-roprotective effects in controlled cortical impact rat models. Akt is a protein kinase known to play a role in cell signaling pathways that reduce edema, inlfammation, apoptosis, and promote cell growth in the brain. This study aims to determine if progesterone modulates the phosphor-ylation of Aktvia its threonine 308 phosphorylation site. Phosphorylation at the threonine 308 site is one of several sites responsible for activating Akt and enabling the protein kinase to carry out its neuroprotective effects. To assess the effects of progesterone on Akt phosphorylation, C57BL/6 mice were treated with progesterone (8 mg/kg) at 1 (intraperitonally), 6, 24, and 48 hours (subcutaneously) post closed-skull traumatic brain injury. The hippocampus was harvest-ed at 72 hours post injury and prepared for western blot analysis. Traumatic brain injury caused a signiifcant decrease in Akt phosphorylation compared to sham operation. However, mice treat-ed with progesterone following traumatic brain injury had an increase in phosphorylation of Akt compared to traumatic brain injury vehicle. Our ifndings suggest that progesterone is a viable treatment option for activating neuroprotective pathways after traumatic brain injury.

  8. Increased level of phosphorylated akt measured by chemiluminescence-linked immunosorbent assay is a predictor of poor prognosis in primary breast cancer overexpressing ErbB-2

    International Nuclear Information System (INIS)

    Akt1, Akt2 and Akt3 kinases are downstream components of phosphoinositol 3-kinase derived signals from receptor tyrosine kinases, which influence cell growth, proliferation and survival. Akt2 overexpression and amplification have been described in breast, ovarian and pancreatic cancers. The present study was designed to investigate the prognostic significance of activated Akt in primary breast cancer and its association with other tumour biomarkers. Using a two-site chemiluminescence-linked immunosorbent assay, we measured the quantitative expression levels of total phosphorylated (P-S473) Akt (Akt1/Akt2/Akt3) on cytosol fractions obtained from fresh frozen tissue samples of 156 primary breast cancer patients. Akt phosphorylation was not associated with nodal status or ErbB-2 protein expression levels. High levels of phosphorylated Akt correlated (P < 0.01) with poor prognosis, and the significance of this correlation increased (P < 0.001) in the subset of patients with ErbB-2 overexpressing tumours. In addition, phosphorylated Akt was found to be associated with mRNA expression levels of several proliferation markers (e.g. thymidylate synthase), measured using quantitative real-time RT-PCR. Our findings demonstrate that, in breast cancer patients, Akt activation is associated with tumour proliferation and poor prognosis, particularly in the subset of patients with ErbB2-overexpressing tumours

  9. Protein kinase C betaII regulates Akt phosphorylation on Ser-473 in a cell type- and stimulus-specific fashion.

    OpenAIRE

    Kawakami, Y; Nishimoto, H; Kitaura, J.; Maeda-Yamamoto, M.; Kato, R.; Littman, D; Leitges, M.; Rawlings, D; Kawakami, T

    2004-01-01

    Akt (= protein kinase B), a subfamily of the AGC serine/threonine kinases, plays critical roles in survival, proliferation, glucose metabolism, and other cellular functions. Akt activation requires the recruitment of the enzyme to the plasma membrane by interacting with membrane-bound lipid products of phosphatidylinositol 3-kinase. Membrane-bound Akt is then phosphorylated at two sites for its full activation; Thr-308 in the activation loop of the kinase domain is phosphorylated by 3-phospho...

  10. Methylglyoxal mediates adipocyte proliferation by increasing phosphorylation of Akt1.

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    Xuming Jia

    Full Text Available Methylglyoxal (MG is a highly reactive metabolite physiologically presented in all biological systems. The effects of MG on diabetes and hypertension have been long recognized. In the present study, we investigated the potential role of MG in obesity, one of the most important factors to cause metabolic syndrome. An increased MG accumulation was observed in the adipose tissue of obese Zucker rats. Cell proliferation assay showed that 5-20 µM of MG stimulated the proliferation of 3T3-L1 cells. Further study suggested that accumulated-MG stimulated the phosphorylation of Akt1 and its targets including p21 and p27. The activated Akt1 then increased the activity of CDK2 and accelerated the cell cycle progression of 3T3-L1 cells. The effects of MG were efficiently reversed by advanced glycation end product (AGE breaker alagebrium and Akt inhibitor SH-6. In summary, our study revealed a previously unrecognized effect of MG in stimulating adipogenesis by up-regulation of Akt signaling pathway and this mechanism might offer a new approach to explain the development of obesity.

  11. Regulation of protein kinase B/Akt activity and Ser473 phosphorylation by protein kinase Calpha in endothelial cells.

    Science.gov (United States)

    Partovian, Chohreh; Simons, Michael

    2004-08-01

    Protein kinase Balpha (PKBalpha/Akt-1) is a key mediator of multiple signaling pathways involved in angiogenesis, cell proliferation and apoptosis among others. The unphosphorylated form of Akt-1 is virtually inactive and its full activation requires two phosphatidylinositol-3,4,5-triphosphate-dependent phosphorylation events, Thr308 by 3-phosphoinositide-dependent kinase-1 (PDK1) and Ser473 by an undefined kinase that has been termed PDK2. Recent studies have suggested that the Ser473 kinase is a plasma membrane raft-associated kinase. In this study we show that protein kinase Calpha (PKCalpha) translocates to the membrane rafts in response to insulin growth factor-1 (IGF-1) stimulation. Overexpression of PKCalpha increases Ser473 phosphorylation and Akt-1 activity, while inhibition of its activity or expression decreases IGF-1-dependent activation of Akt-1. Furthermore, in vitro, in the presence of phospholipids and calcium, PKCalpha directly phosphorylates Akt-1 at the Ser473 site. We conclude, therefore, that PKCalpha regulates Akt-1 activity via Ser473 phosphorylation and may function as PDK2 in endothelial cells. PMID:15157674

  12. TCR-Induced Akt Serine 473 Phosphorylation Is Regulated by Protein Kinase C-Alpha

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    Yang, Lifen; Qiao, Guilin; Ying, Haiyan; Zhang, Jian; Yin, Fei

    2010-01-01

    Akt signaling plays a central role in T cell functions, such as proliferation, apoptosis, and regulatory T cell development. Phosphorylation at Ser473 in the hydrophobic motif, along with Thr308 in its activation loop, is considered necessary for Akt function. It is widely accepted that Phosphoinositide-dependent kinase 1 (PDK-1) phosphorylates Akt at Thr308, but the kinase(s) responsible for phosphorylating Akt at Ser473 (PDK-2) remains elusive. The existence of PDK-2 is considered to be spe...

  13. Hypoxia activates Akt and induces phosphorylation of GSK-3 in PC12 cells.

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    Beitner-Johnson, D; Rust, R T; Hsieh, T C; Millhorn, D E

    2001-01-01

    Akt is a serine/threonine kinase that has been shown to play a central role in promoting cell survival and opposing apoptosis. We evaluated the effect of hypoxia on Akt in rat pheochromocytoma (PC12) cells. PC12 cells were exposed to varying levels of hypoxia, including 21%, 15%, 10%, 5%, and 1% O(2). Hypoxia dramatically increased phosphorylation of Akt (Ser(473)). This effect peaked after 6 h exposure to hypoxia, but persisted strongly for up to 24 h. Phosphorylation of Akt was paralleled with a progressive increase in phosphorylation of glycogen synthase kinase-3 (GSK-3), one of its downstream substrates. The effect of hypoxia on phosphorylation of Akt was completely blocked by pretreatment of the cells with wortmannin (100 nM), indicating that this effect is mediated by phosphatidylinositol 3-kinase (P13K). In contrast, whereas hypoxia also strongly induced phosphorylation of the transcription factors CREB and EPAS1, these effects persisted in the presence of wortmannin. Thus, hypoxia regulates both P13K-dependent and P13K-independent signaling pathways. Furthermore, activation of the P13K and Akt signaling pathways may be one mechanism by which cells adapt and survive under conditions of hypoxia. PMID:11257444

  14. Inhibition of Rb Phosphorylation Leads to mTORC2-Mediated Activation of Akt.

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    Zhang, Jinfang; Xu, Kai; Liu, Pengda; Geng, Yan; Wang, Bin; Gan, Wenjian; Guo, Jianping; Wu, Fei; Chin, Y Rebecca; Berrios, Christian; Lien, Evan C; Toker, Alex; DeCaprio, James A; Sicinski, Piotr; Wei, Wenyi

    2016-06-16

    The retinoblastoma (Rb) protein exerts its tumor suppressor function primarily by inhibiting the E2F family of transcription factors that govern cell-cycle progression. However, it remains largely elusive whether the hyper-phosphorylated, non-E2F1-interacting form of Rb has any physiological role. Here we report that hyper-phosphorylated Rb directly binds to and suppresses the function of mTORC2 but not mTORC1. Mechanistically, Rb, but not p107 or p130, interacts with Sin1 and blocks the access of Akt to mTORC2, leading to attenuated Akt activation and increased sensitivity to chemotherapeutic drugs. As such, inhibition of Rb phosphorylation by depleting cyclin D or using CDK4/6 inhibitors releases Rb-mediated mTORC2 suppression. This, in turn, leads to elevated Akt activation to confer resistance to chemotherapeutic drugs in Rb-proficient cells, which can be attenuated with Akt inhibitors. Therefore, our work provides a molecular basis for the synergistic usage of CDK4/6 and Akt inhibitors in treating Rb-proficient cancer. PMID:27237051

  15. PARP1 inhibitors attenuate AKT phosphorylation via the upregulation of PHLPP1

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shuai [State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025 (China); Division of Hematology and Oncology, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL 35205 (United States); Wang, Huibo; Davis, Ben C. [Division of Hematology and Oncology, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL 35205 (United States); Liang, Jiyong [Department of Systems Biology, University of Texas MD Anderson Cancer Center, Houston, TX 77054 (United States); Cui, Rutao [Department of Dermatology, Boston University School of Medicine, Boston, MA 02118 (United States); Chen, Sai-Juan, E-mail: sjchen@stn.sh.cn [State Key Laboratory of Medical Genomics, Shanghai Institute of Hematology, Rui Jin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025 (China); Xu, Zhi-Xiang, E-mail: zhi-xiang.xu@ccc.uab.edu [Division of Hematology and Oncology, Comprehensive Cancer Center, University of Alabama at Birmingham, Birmingham, AL 35205 (United States)

    2011-08-26

    Highlights: {yields} PARP1 inhibitors cause a cytotoxic effect independent of DNA repair impairment. {yields} PARP1 inhibitors attenuated AKT-FOXO3A signaling by activating PHLPP1. {yields} PHLPP1 regulates the sensitivity of cancer cells to PARP1 inhibitors. -- Abstract: Poly(ADP-ribose) polymerase-1 (PARP1) inhibitors are emerging as an important class of drugs for treating BRCA-deficient cancers. Recent discoveries have shown that PARP1 inhibitors may treat other cancer patients in addition to the relatively small proportion of patients carrying BRCA mutations. However, the additional targets by which PARP1 inhibitor-mediated tumor suppression remain poorly understood. In this study, we show that two PARP1 inhibitors, PJ-34 and 3-AB, attenuate AKT phosphorylation at serine 473 (S473) independent of DNA repair impairment. These inhibitors decrease the AKT-associated phosphorylation of FOXO3A, enhance the nuclear retention of FOXO3A, and activate its transcriptional activity. We further demonstrate that treatment with PJ-34 or 3-AB dramatically increases the level of PHLPP1. Overexpression of PHLPP1 enhances the PARP1 inhibitor-induced downregulation of AKT phosphorylation and increases tumor cell death. In contrast, knockdown of PHLPP1 abrogates the PARP1 inhibitor-mediated AKT inhibition and desensitizes cells to its treatment. Therefore, our findings not only show the robust role of PARP1 inhibitors in AKT inhibition but also develop a novel strategy to increase the effectiveness of cancer treatment via PARP1 inhibitor-induced PHLPP1 upregulation.

  16. Characterizing the Microenvironment Surrounding Phosphorylated Protein Sites

    Institute of Scientific and Technical Information of China (English)

    Shi-Cai Fan; Xue-Gong Zhang

    2005-01-01

    Protein phosphorylation plays an important role in various cellular processes. Due to its high complexity, the mechanism needs to be further studied. In the last few years, many methods have been contributed to this field, but almost all of them investigated the mechanism based on protein sequences around protein sites. In this study, we implement an exploration by characterizing the microenvironment surrounding phosphorylated protein sites with a modified shell model, and obtain some significant properties by the rank-sum test, such as the lack of some classes of residues, atoms, and secondary structures. Furthermore, we find that the depletion of some properties affects protein phosphorylation remarkably. Our results suggest that it is a meaningful direction to explore the mechanism of protein phosphorylation from microenvironment and we expect further findings along with the increasing size of phosphorylation and protein structure data.

  17. CD133 promotes gallbladder carcinoma cell migration through activating Akt phosphorylation

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    Zhen, Jiaojiao; Ai, Zhilong

    2016-01-01

    Gallbladder carcinoma (GBC) is the fifth most common malignancy of gastrointestinal tract. The prognosis of gallbladder carcinoma is extremely terrible partially due to metastasis. However, the mechanisms underlying gallbladder carcinoma metastasis remain largely unknown. CD133 is a widely used cancer stem cell marker including in gallbladder carcinoma. Here, we found that CD133 was highly expressed in gallbladder carcinoma as compared to normal tissues. CD133 was located in the invasive areas in gallbladder carcinoma. Down-regulation expression of CD133 inhibited migration and invasion of gallbladder carcinoma cell without obviously reducing cell proliferation. Mechanism analysis revealed that down-regulation expression of CD133 inhibited Akt phosphorylation and increased PTEN protein level. The inhibitory effect of CD133 down-regulation on gallbladder carcinoma cell migration could be rescued by Akt activation. Consistent with this, addition of Akt inhibitor Wortmannin markedly inhibited the migration ability of CD133-overexpressing cells. Thus, down-regulation of CD133 inhibits migration of gallbladder carcinoma cells through reducing Akt phosphorylation. These findings explore the fundamental biological aspect of CD133 in gallbladder carcinoma progression, providing insights into gallbladder carcinoma cell migration. PMID:26910892

  18. Pistacia chinensis Methanolic Extract Attenuated MAPK and Akt Phosphorylations in ADP Stimulated Rat Platelets In Vitro

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    Ji Young Park

    2012-01-01

    (2.5–20 μg/mL inhibited ADP-induced platelet aggregation. While PCME diminished [Ca2+]i, ATP, and TXA2 release in ADP-activated platelets, it enhanced cAMP production in resting platelets. Likewise, PCME inhibited fibrinogen binding to αIIbβ3 and downregulated JNK, ERK, and Akt phosphorylations. Thus, PCME contains potential antiplatelet compounds that could be deployed for their therapeutic values in cardiovascular pathology.

  19. Mapping of p140Cap phosphorylation sites

    DEFF Research Database (Denmark)

    Repetto, Daniele; Aramu, Simona; Boeri Erba, Elisabetta;

    2013-01-01

    protein, in which both EPLYA/EGLYA tyrosines were converted to phenylalanine, was no longer tyrosine phosphorylated, despite the presence of other tyrosine residues in p140Cap sequence. Moreover, this mutant lost its ability to bind the C-terminal Src kinase (Csk), previously shown to interact with p140...... phosphorylation and tunes its interactions with other regulatory molecules via post-translation modification. In this work, using mass spectrometry, we found that p140Cap is in vivo phosphorylated on tyrosine (Y) within the peptide GEGLpYADPYGLLHEGR (from now on referred to as EGLYA) as well as on three serine...... residues. Consistently, EGLYA has the highest score of in silico prediction of p140Cap phosphorylation. To further investigate the p140Cap function, we performed site specific mutagenesis on tyrosines inserted in EGLYA and EPLYA, a second sequence with the same highest score of phosphorylation. The mutant...

  20. Protein kinase C betaII regulates Akt phosphorylation on Ser-473 in a cell type- and stimulus-specific fashion.

    Science.gov (United States)

    Kawakami, Yuko; Nishimoto, Hajime; Kitaura, Jiro; Maeda-Yamamoto, Mari; Kato, Roberta M; Littman, Dan R; Leitges, Michael; Rawlings, David J; Kawakami, Toshiaki

    2004-11-12

    Akt (= protein kinase B), a subfamily of the AGC serine/threonine kinases, plays critical roles in survival, proliferation, glucose metabolism, and other cellular functions. Akt activation requires the recruitment of the enzyme to the plasma membrane by interacting with membrane-bound lipid products of phosphatidylinositol 3-kinase. Membrane-bound Akt is then phosphorylated at two sites for its full activation; Thr-308 in the activation loop of the kinase domain is phosphorylated by 3-phosphoinositide-dependent kinase-1 (PDK1) and Ser-473 in the C-terminal hydrophobic motif by a putative kinase PDK2. The identity of PDK2 has been elusive. Here we present evidence that conventional isoforms of protein kinase C (PKC), particularly PKCbetaII, can regulate Akt activity by directly phosphorylating Ser-473 in vitro and in IgE/antigen-stimulated mast cells. By contrast, PKCbeta is not required for Ser-473 phosphorylation in mast cells stimulated with stem cell factor or interleukin-3, in serum-stimulated fibroblasts, or in antigen receptor-stimulated T or B lymphocytes. Therefore, PKCbetaII appears to work as a cell type- and stimulus-specific PDK2. PMID:15364915

  1. Right-To-Left Ventricular Differences in the Expression of Mitochondrial Hexokinase and Phosphorylation of Akt

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    Petra Waskova-Arnostova

    2013-01-01

    Full Text Available Background/Aims: Hexokinase (HK is a key glycolytic enzyme which promotes the maintenance of glucose homeostasis in cardiomyocytes. HK1 isoform is predominantly bound to the outer mitochondrial membrane and highly supports oxidative phosphorylation by increasing the availability of ADP for complex V of the respiratory chain. HK2 isoform is under physiological conditions predominantly localized in the cytosol and upon stimulation of PI3K/ Akt pathway associates with mitochondria and thus can prevent apoptosis. The purpose of this study was to investigate expression and subcellular localization of both HK isoforms in left (LV and right (RV heart ventricles of adult male Wistar rats. Methods: Real-Time RT-PCR, Western blotting, and quantitative immunofluorescence microscopy were used. Results: Our results showed a significantly higher expression of both HK1 and HK2 at mRNA and protein levels in the RV compared to the LV. These findings were corroborated by immunofluorescence staining which revealed substantially higher fluorescence signals of both HKs in the RV than in the LV. The ratios of phospho-Ser473-Akt/non-phospho-Akt and phospho-Thr308-Akt/non-phospho-Akt were also markedly higher in the RV than in the LV. Conclusion: These results suggest that the RV has a higher activity of aerobic glycolytic metabolism and may be able to respond faster and more powerfully to stressful stimuli than the LV.

  2. Phosphorylation sites within Ebola virus nucleoprotein

    Institute of Scientific and Technical Information of China (English)

    Sora; Yasri; Viroj; Wiwanitkit

    2015-01-01

    To understand the infection process, the viral multiplication and entry to the cell is widely studied. The Ebola virus nucleoprotein is the important problem for the pathological process. Focusing on the specific biological process, the post translational modification is needed. Here, the authors used the bioinformatics study to find the phosphorylation sites within the Ebola virus nucleoprotein and could identify many new sites.

  3. Effects of Zinc on Glucose Consumption and AKT/GSK3β Phosphorylation in L6 Myotubes

    Institute of Scientific and Technical Information of China (English)

    Hui-zi LU; Yun-tang WU; Zhong SUN; Yong-zhe LIU; Yong-ming WANG; Qian SANG; Xin-yan LIU

    2014-01-01

    ObjectiveTo investigate the effects of zinc on glucose consumption in normal and insulin-resistant L6 myotubes and elucidate its association with AKT/GSK3β phosphorylation, two key components in the insulin-signaling pathway.Methods The insulin-resistant cell model was prepared by treating L6 myotubes with 0.4mmol/L palmitic acid for 24h and then exposed to different concentrations of zinc (0, 10, 20, 50, 100μmol/L) in the presence or absence of insulin (100 nmol/L) for 3h. Glucose consumption was determined by glucose oxidase method. AKT /GSK3β phosphorylation was detected by Western blotting method.ResultsIn normal L6 myotubes, zinc (10-50μmol/L) alone could significantly increase glucose consumption. In the presence or absence of insulin, zinc significantly enhanced AKT/GSK3β phosphorylation. In insulin-resistant L6 myotubes, zinc (10-50μmol/L) could increase glucose consumption and GSK3β phosphorylation, which was accompanied by enhanced AKT phosphorylation in the presence of insulin.ConclusionCollectively, these results showed that zinc at the concentrations of 10-50μmol/L could increase glucose consumption in L6 myotubes. The mechanism was related to the activation of the insulin signaling pathway by zinc through AKT/GSK3β phosphorylation.

  4. mTORC2 phosphorylation of Akt1: a possible mechanism for hydrogen sulfide-induced cardioprotection.

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    Yue Zhou

    Full Text Available Hydrogen sulfide (H2S is known to have cardiac protective effects through Akt activation. Akt acts as a 'central sensor' for myocyte survival or death; its activity is regulated by multiple kinases including PI3K, mTORC2, PDK1 and phosphatases including PTEN, PP2A and PHLPPL. Based on the previous finding that PI3K inhibitor LY294002 abolishes H2S-induced Akt phosphorylation and cardioprotection, it is accepted that PI3K is the mediator of H2S-induced Akt phosphorylation. However, LY294002 inhibits both PI3K and mTOR, and PI3K only recruits Akt to the membrane where Akt is phosphorylated by Akt kinases. We undertook a series of experiments to further evaluate the role of mTORC2, PDK1, PTEN, PP2A and PHLPPL in H2S-induced Akt phosphorylation and cardioprotection, which, we believe, has not been investigated before. Hearts from adult Sprague-Dawley rats were isolated and subjected to (i normoxia, (ii global ischemia and (iii ischemia/reperfusion in the presence or absence of 50 µM of H2S donor NaHS. Cardiac mechanical function and lactate dehydrogenase (LDH release were assessed. All hearts also were Western analyzed at the end of perfusion for Akt and a panel of appropriate Akt regulators and targets. Hearts pretreated with 50 µM NaHS had improved function at the end of reperfusion (Rate pressure product; 19±4×10(3 vs. 10±3×10(3 mmHg/min, p<0.05 and reduced cell injury (LDH release 19±10 vs. 170±87 mU/ml p<0.05 compared to untreated hearts. NaHS significantly increased phospho-Akt, phospho-mTOR, phospho-Bim and Bcl-2 in reperfused hearts (P<0.05. Furthermore using H9c2 cells we demonstrate that NaHS pretreatment reduces apoptosis following hypoxia/re-oxygenation. Importantly, PP242, a specific mTOR inhibitor, abolished both cardioprotection and protein phosphorylation in isolated heart and reduced apoptotic effects in H9c2 cells. Treating hearts with NaHS only during reperfusion produced less cardioprotection through a similar mechanism

  5. RASSF4 promotes EV71 replication to accelerate the inhibition of the phosphorylation of AKT.

    Science.gov (United States)

    Zhang, Fengfeng; Liu, Yongjuan; Chen, Xiong; Dong, Lanlan; Zhou, Bingfei; Cheng, Qingqing; Han, Song; Liu, Zhongchun; Peng, Biwen; He, Xiaohua; Liu, Wanhong

    2015-03-20

    Enterovirus 71 (EV71) is a neurotropic virus that causes hand, foot and mouth disease (HFMD), occasionally leading to death. As a member of the RAS association domain family (RASSFs), RASSF4 plays important roles in cell death, tumor development and signal transduction. However, little is known about the relationship between RASSF4 and EV71. Our study reveals for the first time that RASSF4 promotes EV71 replication and then accelerates AKT phosphorylation inhibition in EV71-infected 293T cells, suggesting that RASSF4 may be a potential new target for designing therapeutic measures to prevent and control EV71 infection.

  6. Phosphorylation sites within Ebola virus nucleoprotein

    Directory of Open Access Journals (Sweden)

    Sora Yasri

    2015-07-01

    Full Text Available To understand the infection process, the viral multiplication and entry to the cell is widely studied. The Ebola virus nucleoprotein is the important problem for the pathological process. Focusing on the specific biological process, the post translational modification is needed. Here, the authors used the bioinformatics study to find the phosphorylation sites within the Ebola virus nucleoprotein and could identify many new sites.

  7. Phospho-Akt immunoreactivity in prostate cancer: relationship to disease severity and outcome, Ki67 and phosphorylated EGFR expression.

    Directory of Open Access Journals (Sweden)

    Peter Hammarsten

    Full Text Available BACKGROUND: In the present study, we have investigated the prognostic usefulness of phosphorylated Akt immunoreactivity (pAkt-IR in prostate cancer using a well-characterised tissue microarray from men who had undergone transurethral resection due to lower urinary tract symptoms. METHODOLOGY/PRINCIPAL FINDINGS: pAkt-IR in prostate epithelial and tumour cells was assessed using a monoclonal anti-pAkt (Ser(473 antibody. Immunoreactive intensity was determined for 282 (tumour and 240 (non-malignant tissue cases. Tumour pAkt-IR scores correlated with Gleason score, tumour Ki67-IR (a marker of cell proliferation and tumour phosphorylated epidermal growth factor receptor (pEGFR-IR. For cases followed with expectancy, a high tumour pAkt-IR was associated with a poor disease-specific survival, and the prognostic information provided by this biomarker was additive to that provided by either (but not both tumour pEFGR-IR or Ki67-IR. Upon division of the cases with respect to their Gleason scores, the prognostic value of pAkt-IR was seen for patients with Gleason score 8-10, but not for patients with Gleason score 6-7. CONCLUSIONS/SIGNIFICANCE: Tumour pAkt-IR is associated with both disease severity and disease-specific survival. However, its clinical use as a biomarker is limited, since it does not provide prognostic information in patients with Gleason scores 6-7.

  8. Nitration of JAK-2 at the 1007Y-1008Y activation epitope impedes phosphorylation at this site: defining a GH, AKT/protein kinase B and nitric oxide synthase axis

    Science.gov (United States)

    Generalized liver protein tyrosine nitration (3’-nitrotyrosine, 3’-NT) increases in vivo after GH injection with immunohistocellular patterns strikingly similar to those we observed for a specific nitration of JAK2 at its 1007Y-1008Y regulatory phosphorylation epitope following proinflammatory chall...

  9. A novel AKT inhibitor, AZD5363, inhibits phosphorylation of AKT downstream molecules, and activates phosphorylation of mTOR and SMG-1 dependent on the liver cancer cell type

    Science.gov (United States)

    ZHANG, YUNCHENG; ZHENG, YUANWEN; FAHEEM, ALI; SUN, TIANTONG; LI, CHUNYOU; LI, ZHE; ZHAO, DIANTANG; WU, CHAO; LIU, JUN

    2016-01-01

    Due to frequent phosphoinositide 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling pathway dysregulation, AKT is typically accepted as a promising anticancer therapeutic target. mTOR, in particular, represents a suitable therapeutic target for hepatocellular carcinoma, whilst suppressor with morphogenetic effect on genitalia family member-1 (SMG-1) is believed to serve a potential tumor suppressor role in human cancer. Despite SMG-1 and mTOR belonging to the same PI3K-related kinase family, the interactions between them are not yet fully understood. In the present study, a novel pyrrolopyrimidine-derived compound, AZD5363, was observed to suppress proliferation in liver cancer Hep-G2 and Huh-7 cells by inhibiting the phosphorylation of downstream molecules in the AKT signal pathway, in a dose- and time-dependent manner. AZD5363 activated the phosphorylation of mTOR, dependent on the liver cancer cell type, as it may have differing effects in various liver cancer cell lines. Additionally, AZD5363 also activated SMG-1 within the same liver cancer cells types, which subsequently activated the phosphorylation of mTOR. In conclusion, the present study indicates that AZD5363 inhibited phosphorylation of AKT downstream molecules, and activated phosphorylation of mTOR and SMG-1, dependent on the liver cancer type. PMID:26998062

  10. Modulation of curcumin-induced Akt phosphorylation and apoptosis by PI3K inhibitor in MCF-7 cells

    International Nuclear Information System (INIS)

    Curcumin has been shown to induce apoptosis in various malignant cancer cell lines. One mechanism of curcumin-induced apoptosis is through the PI3K/Akt signaling pathway. Akt, also known as protein kinase B (PKB), is a member of the family of phosphatidylinositol 3-OH-kinase regulated Ser/Thr kinases. The active Akt regulates cell survival and proliferation; and inhibits apoptosis. In this study we found that curcumin induces apoptotic cell death in MCF-7 cells, as assessed by MTT assay, DNA ladder formation, PARP cleavage, p53 and Bax induction. At apoptotic inducing concentration, curcumin induces a dramatic Akt phosphorylation, accompanied by an increased phosphorylation of glycogen synthase kinase 3β (GSK3β), which has been considered to be a pro-growth signaling molecule. Combining curcumin with PI3K inhibitor, LY290042, synergizes the apoptotic effect of curcumin. The inhibitor LY290042 was capable of attenuating curcumin-induced Akt phosphorylation and activation of GSK3β. All together, our data suggest that blocking the PI3K/Akt survival pathway sensitizes the curcumin-induced apoptosis in MCF-7 cells.

  11. Modulation of curcumin-induced Akt phosphorylation and apoptosis by PI3K inhibitor in MCF-7 cells

    Energy Technology Data Exchange (ETDEWEB)

    Kizhakkayil, Jaleel; Thayyullathil, Faisal; Chathoth, Shahanas; Hago, Abdulkader; Patel, Mahendra [Cell Signaling Laboratory, Department of Biochemistry, Faculty of Medicine and Health Sciences, UAE University, P.O. Box 17666, Al Ain (United Arab Emirates); Galadari, Sehamuddin, E-mail: sehamuddin@uaeu.ac.ae [Cell Signaling Laboratory, Department of Biochemistry, Faculty of Medicine and Health Sciences, UAE University, P.O. Box 17666, Al Ain (United Arab Emirates)

    2010-04-09

    Curcumin has been shown to induce apoptosis in various malignant cancer cell lines. One mechanism of curcumin-induced apoptosis is through the PI3K/Akt signaling pathway. Akt, also known as protein kinase B (PKB), is a member of the family of phosphatidylinositol 3-OH-kinase regulated Ser/Thr kinases. The active Akt regulates cell survival and proliferation; and inhibits apoptosis. In this study we found that curcumin induces apoptotic cell death in MCF-7 cells, as assessed by MTT assay, DNA ladder formation, PARP cleavage, p53 and Bax induction. At apoptotic inducing concentration, curcumin induces a dramatic Akt phosphorylation, accompanied by an increased phosphorylation of glycogen synthase kinase 3{beta} (GSK3{beta}), which has been considered to be a pro-growth signaling molecule. Combining curcumin with PI3K inhibitor, LY290042, synergizes the apoptotic effect of curcumin. The inhibitor LY290042 was capable of attenuating curcumin-induced Akt phosphorylation and activation of GSK3{beta}. All together, our data suggest that blocking the PI3K/Akt survival pathway sensitizes the curcumin-induced apoptosis in MCF-7 cells.

  12. Mixed mechanisms of multi-site phosphorylation.

    Science.gov (United States)

    Suwanmajo, Thapanar; Krishnan, J

    2015-06-01

    Multi-site phosphorylation is ubiquitous in cell biology and has been widely studied experimentally and theoretically. The underlying chemical modification mechanisms are typically assumed to be distributive or processive. In this paper, we study the behaviour of mixed mechanisms that can arise either because phosphorylation and dephosphorylation involve different mechanisms or because phosphorylation and/or dephosphorylation can occur through a combination of mechanisms. We examine a hierarchy of models to assess chemical information processing through different mixed mechanisms, using simulations, bifurcation analysis and analytical work. We demonstrate how mixed mechanisms can show important and unintuitive differences from pure distributive and processive mechanisms, in some cases resulting in monostable behaviour with simple dose-response behaviour, while in other cases generating new behaviour-like oscillations. Our results also suggest patterns of information processing that are relevant as the number of modification sites increases. Overall, our work creates a framework to examine information processing arising from complexities of multi-site modification mechanisms and their impact on signal transduction. PMID:25972433

  13. Cigarette sidestream smoke induces histone H3 phosphorylation via JNK and PI3K/Akt pathways, leading to the expression of proto-oncogenes.

    Science.gov (United States)

    Ibuki, Yuko; Toyooka, Tatsushi; Zhao, Xiaoxu; Yoshida, Ikuma

    2014-06-01

    Post-translational modifications in histones have been associated with cancer. Although cigarette sidestream smoke (CSS) as well as mainstream smoke are carcinogens, the relationship between carcinogenicity and histone modifications has not yet been clarified. Here, we demonstrated that CSS induced phosphorylation of histones, involving a carcinogenic process. Treatment with CSS markedly induced the phosphorylation of histone H3 at serine 10 and 28 residues (H3S10 and H3S28), which was independent from the cell cycle, in the human pulmonary epithelial cell model, A549 and normal human lung fibroblasts, MRC-5 and WI-38. Using specific inhibitors and small interfering RNA, the phosphorylation of H3S10 was found to be mediated by c-jun N-terminal kinase (JNK) and phosphoinositide 3-kinase (PI3K)/Akt pathways. These pathways were different from that of the CSS-induced phosphorylation of histone H2AX (γ-H2AX) mediated by Ataxia telangiectasia-mutated (ATM) and ATM-Rad3-related (ATR) protein kinases. A chromatin immunoprecipitation assay revealed that the phosphorylation of H3S10 was increased in the promoter sites of the proto-oncogenes, c-fos and c-jun, which indicated that CSS plays a role in tumor promotion. Because the phosphorylation of H3S10 was decreased in the aldehyde-removed CSS and was significantly induced by treatment with formaldehyde, aldehydes are suspected to partially contribute to this phosphorylation. These findings suggested that any chemicals in CSS, including aldehydes, phosphorylate H3S10 via JNK and PI3K/Akt pathways, which is different from the DNA damage response, resulting in tumor promotion.

  14. EFFECTS OF ESTROGEN AND AGING ON THE SYNAPTIC DISTRIBUTION OF PHOSPHORYLATED AKT-IMMUNOREACTIVITY IN THE CA1 REGION OF THE FEMALE RAT HIPPOCAMPUS

    OpenAIRE

    Yildirim, Murat; JANSSEN, WILLIAM G.M.; Lou, W.Y. Wendy; Akama, Keith T.; McEwen, Bruce S.; Milner, Teresa A.; Morrison, John H.

    2010-01-01

    The estrogen 17β-estradiol (E) increases the axospinous synaptic density and plasticity in the hippocampal CA1 region of young female rats but fails to do so in aged female rats. This E stimulus on synaptic plasticity is associated with the phosphorylation-dependent activation of Akt kinase. Our previous findings demonstrated that increased estrogen levels subsequently increase phosphorylated Akt (pAkt)-immunoreactivity (-IR) within the dendritic shafts and spines of pyramidal neurons in youn...

  15. Neurogenesis and Increase in Differentiated Neural Cell Survival via Phosphorylation of Akt1 after Fluoxetine Treatment of Stem Cells

    Directory of Open Access Journals (Sweden)

    Anahita Rahmani

    2013-01-01

    Full Text Available Fluoxetine (FLX is a selective serotonin reuptake inhibitor (SSRI. Its action is possibly through an increase in neural cell survival. The mechanism of improved survival rate of neurons by FLX may relate to the overexpression of some kinases such as Akt protein. Akt1 (a serine/threonine kinase plays a key role in the modulation of cell proliferation and survival. Our study evaluated the effects of FLX on mesenchymal stem cell (MSC fate and Akt1 phosphorylation levels in MSCs. Evaluation tests included reverse transcriptase polymerase chain reaction, western blot, and immunocytochemistry assays. Nestin, MAP-2, and β-tubulin were detected after neurogenesis as neural markers. Ten μM of FLX upregulated phosphorylation of Akt1 protein in induced hEnSC significantly. Also FLX did increase viability of these MSCs. Continuous FLX treatment after neurogenesis elevated the survival rate of differentiated neural cells probably by enhanced induction of Akt1 phosphorylation. This study addresses a novel role of FLX in neurogenesis and differentiated neural cell survival that may contribute to explaining the therapeutic action of fluoxetine in regenerative pharmacology.

  16. Pistacia chinensis Methanolic Extract Attenuated MAPK and Akt Phosphorylations in ADP Stimulated Rat Platelets In Vitro.

    Science.gov (United States)

    Park, Ji Young; Hong, Mei; Jia, Qi; Lee, Young-Chul; Yayeh, Taddesse; Hyun, Eujin; Kwak, Dong-Mi; Cho, Jae Youl; Rhee, Man Hee

    2012-01-01

    Pistacia chinensis (Chinese pistache) is a widely grown plant in southern China where the galls extract is a common practice in folk medicine. However, extracts from this plant have never been attempted for their cardiovascular protective effects in experimental setting. Here therefore we aimed to investigate the antiplatelet activity of Pistacia chinensis methanolic extract (PCME) in ADP stimulated rat platelets in vitro. PCME (2.5-20 μg/mL) inhibited ADP-induced platelet aggregation. While PCME diminished [Ca(2+)]i, ATP, and TXA2 release in ADP-activated platelets, it enhanced cAMP production in resting platelets. Likewise, PCME inhibited fibrinogen binding to αIIbβ3 and downregulated JNK, ERK, and Akt phosphorylations. Thus, PCME contains potential antiplatelet compounds that could be deployed for their therapeutic values in cardiovascular pathology. PMID:22899962

  17. Impairments in site-specific AS160 phosphorylation and effects of exercise training

    DEFF Research Database (Denmark)

    Consitt, Leslie A; Van Meter, Jessica; Newton, Christopher A;

    2013-01-01

    The purpose of this study was to determine if site-specific phosphorylation at the level of Akt substrate of 160 kDa (AS160) is altered in skeletal muscle from sedentary humans across a wide range of the adult lifespan (18 to 84 years) and if endurance- and/or strength-oriented exercise training ...... population and that exercise training is an effective intervention for treating these impairments.......The purpose of this study was to determine if site-specific phosphorylation at the level of Akt substrate of 160 kDa (AS160) is altered in skeletal muscle from sedentary humans across a wide range of the adult lifespan (18 to 84 years) and if endurance- and/or strength-oriented exercise training...... in whole-body insulin action were associated with impairments in insulin-induced phosphorylation of skeletal muscle AS160 on sites Ser-588, Thr-642, Ser-666 and phospho-Akt substrate (PAS), but not Ser-318 or Ser-751. Twelve weeks of either endurance- or strength-oriented exercise training increased whole...

  18. Antiproliferative factor decreases Akt phosphorylation and alters gene expression via CKAP4 in T24 bladder carcinoma cells

    Directory of Open Access Journals (Sweden)

    Zhang Chen-Ou

    2010-12-01

    Full Text Available Abstract Background Urinary bladder cancer is a common malignancy worldwide, and outcomes for patients with advanced bladder cancer remain poor. Antiproliferative factor (APF is a potent glycopeptide inhibitor of epithelial cell proliferation that was discovered in the urine of patients with interstitial cystitis, a disorder with bladder epithelial thinning and ulceration. APF mediates its antiproliferative activity in primary normal bladder epithelial cells via cytoskeletal associated protein 4 (CKAP4. Because synthetic asialo-APF (as-APF has also been shown to inhibit T24 bladder cancer cell proliferation at nanomolar concentrations in vitro, and because the peptide segment of APF is 100% homologous to part of frizzled 8, we determined whether CKAP4 mediates as-APF inhibition of proliferation and/or downstream Wnt/frizzled signaling events in T24 cells. Methods T24 cells were transfected with double-stranded siRNAs against CKAP4 and treated with synthetic as-APF or inactive control peptide; cells that did not undergo electroporation and cells transfected with non-target (scrambled double-stranded siRNA served as negative controls. Cell proliferation was determined by 3H-thymidine incorporation. Expression of Akt, glycogen synthase kinase 3β (GSK3β, β-catenin, p53, and matrix metalloproteinase 2 (MMP2 mRNA was determined by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR. Akt, GSK-3β, MMP2, β-catenin, and p53 protein expression, plus Akt, GSK-3β, and β-catenin phosphorylation, were determined by Western blot. Results T24 cell proliferation, MMP2 expression, Akt ser473 and thr308 phosphorylation, GSK3β tyr216 phosphorylation, and β-catenin ser45/thr41 phosphorylation were all decreased by APF, whereas p53 expression, and β-catenin ser33,37/thr41 phosphorylation, were increased by APF treatment in non-electroporated and non-target siRNA-transfected cells. Neither mRNA nor total protein expression of Akt, GSK3β, or

  19. Human recombinant H2 relaxin induces AKT and GSK3β phosphorylation and HTR-8/SVneo cell proliferation.

    Science.gov (United States)

    Astuti, Yoni; Nakabayashi, Koji; Deguchi, Masashi; Ebina, Yasuhiko; Yamada, Hideto

    2015-01-01

    Relaxin is essential for trophoblast development during pregnancy. Evidence shows that relaxin increases trophoblast cell migration capacity. Here, we show the effect of relaxin on protein kinase B (AKT) activation and glycogen synthase kinase 3-beta (GSK3β) inactivation as well as on the proliferation of HTR-8/SVneo cells, a model of human extravillous trophoblast (EVT). HTR-8/SVneo cells were treated with different doses of human recombinant (rH2) relaxin in serum-deprived conditions and treated for increasing time with 1 ng/mL of rH2 relaxin. Western blot analysis was performed to detect pAKT, AKT, pGSK3β, GSK3β, and actin expression. Proliferation of HTR-8/SVneo cells was analyzed by MTS assay. rH2 relaxin treatment increased the ratio of pAKT/AKT, pGSK3β/GSK3β, and proliferation in HTR-8/SVneo cells. Furthermore, AKT and GSK3β activation by rH2 relaxin was inhibited by a phosphoinositide 3-kinase (PI3K) inhibitor. This study suggests that rH2 relaxin induces AKT and GSK3β phosphorylation as well as proliferation in HTR-8/SVneo cells. PMID:25868609

  20. Shear stress stimulates phosphorylation of endothelial nitric-oxide synthase at Ser1179 by Akt-independent mechanisms: role of protein kinase A

    Science.gov (United States)

    Boo, Yong Chool; Sorescu, George; Boyd, Nolan; Shiojima, Ichiro; Walsh, Kenneth; Du, Jie; Jo, Hanjoong

    2002-01-01

    Recently, we have shown that shear stress stimulates NO(*) production by the protein kinase B/Akt (Akt)-dependent mechanisms in bovine aortic endothelial cells (BAEC) (Go, Y. M., Boo, Y. C., Park, H., Maland, M. C., Patel, R., Pritchard, K. A., Jr., Fujio, Y., Walsh, K., Darley-Usmar, V., and Jo, H. (2001) J. Appl. Physiol. 91, 1574-1581). Akt has been believed to regulate shear-dependent production of NO(*) by directly phosphorylating endothelial nitric-oxide synthase (eNOS) at the Ser(1179) residue (eNOS-S(1179)), but a critical evaluation using specific inhibitors or dominant negative mutants (Akt(AA) or Akt(AAA)) has not been reported. In addition, other kinases, including protein kinase A (PKA) and AMP kinase have also shown to phosphorylate eNOS-S(1179). Here, we show that shear-dependent phosphorylation of eNOS-S(1179) is mediated by an Akt-independent, but a PKA-dependent, mechanism. Expression of Akt(AA) or Akt(AAA) in BAEC by using recombinant adenoviral constructs inhibited phosphorylation of eNOS-S(1179) if cells were stimulated by vascular endothelial growth factor (VEGF), but not by shear stress. As shown before, expression of Akt(AA) inhibited shear-dependent NO(*) production, suggesting that Akt is still an important regulator in NO production. Further studies showed that a selective inhibitor of PKA, H89, inhibited shear-dependent phosphorylation of eNOS-S(1179) and NO(*) production. In contrast, H89 did not inhibit phosphorylation of eNOS-S(1179) induced by expressing a constitutively active Akt mutant (Akt(Myr)) in BAEC, showing that the inhibitor did not affect the Akt pathway. 8-Bromo-cAMP alone phosphorylated eNOS-S(1179) within 5 min without activating Akt, in an H89-sensitive manner. Collectively, these results demonstrate that shear stimulates phosphorylation of eNOS-S(1179) in a PKA-dependent, but Aktindependent manner, whereas the NO(*) production is regulated by the mechanisms dependent on both PKA and Akt. A coordinated interaction

  1. Quantitative phosphoproteomics reveals widespread full phosphorylation site occupancy during mitosis

    DEFF Research Database (Denmark)

    Miller, Martin Lee; Brunak, Søren; Olsen, JV;

    2010-01-01

    ) or CDK2 were almost fully phosphorylated in mitotic cells. In particular, nuclear proteins and proteins involved in regulating metabolic processes have high phosphorylation site occupancy in mitosis. This suggests that these proteins may be inactivated by phosphorylation in mitotic cells....

  2. COX-2 activation is associated with Akt phosphorylation and poor survival in ER-negative, HER2-positive breast cancer

    Directory of Open Access Journals (Sweden)

    Goodman Julie E

    2010-11-01

    Full Text Available Abstract Background Inducible cyclooxgenase-2 (COX-2 is commonly overexpressed in breast tumors and is a target for cancer therapy. Here, we studied the association of COX-2 with breast cancer survival and how this association is influenced by tumor estrogen and HER2 receptor status and Akt pathway activation. Methods Tumor COX-2, HER2 and estrogen receptor α (ER expression and phosphorylation of Akt, BAD, and caspase-9 were analyzed immunohistochemically in 248 cases of breast cancer. Spearman's correlation and multivariable logistic regression analyses were used to examine the relationship between COX-2 and tumor characteristics. Kaplan-Meier survival and multivariable Cox proportional hazards regression analyses were used to examine the relationship between COX-2 and disease-specific survival. Results COX-2 was significantly associated with breast cancer outcome in ER-negative [Hazard ratio (HR = 2.72; 95% confidence interval (CI, 1.36-5.41; comparing high versus low COX-2] and HER2 overexpressing breast cancer (HR = 2.84; 95% CI, 1.07-7.52. However, the hazard of poor survival associated with increased COX-2 was highest among patients who were both ER-negative and HER2-positive (HR = 5.95; 95% CI, 1.01-34.9. Notably, COX-2 expression in the ER-negative and HER2-positive tumors correlated significantly with increased phosphorylation of Akt and of the two Akt targets, BAD at Ser136 and caspase-9 at Ser196. Conclusions Up-regulation of COX-2 in ER-negative and HER2-positive breast tumors is associated with Akt pathway activation and is a marker of poor outcome. The findings suggest that COX-2-specific inhibitors and inhibitors of the Akt pathway may act synergistically as anticancer drugs in the ER-negative and HER2-positive breast cancer subtype.

  3. PhosphoBase: a database of phosphorylation sites

    DEFF Research Database (Denmark)

    Blom, Nikolaj; Kreegipuu, Andres; Brunak, Søren

    1998-01-01

    PhosphoBase is a database of experimentally verified phosphorylation sites. Version 1.0 contains 156 entries and 398 experimentally determined phosphorylation sites. Entries are compiled and revised from the literature and from major protein sequence databases such as SwissProt and PIR. The entries...... displaying the overall conservation of positions around serines phosphorylated by protein kinase A (PKA). PhosphoBase is available on the WWW at http://www.cbs.dtu.dk/databases/PhosphoBase/....

  4. Halofuginone inhibits Smad3 phosphorylation via the PI3K/Akt and MAPK/ERK pathways in muscle cells: Effect on myotube fusion

    Energy Technology Data Exchange (ETDEWEB)

    Roffe, Suzy [Department of Animal Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel); Hagai, Yosey [Department of Animal Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel); Institute of Animal Sciences, Volcani Center, Bet Dagan 50250 (Israel); Pines, Mark [Institute of Animal Sciences, Volcani Center, Bet Dagan 50250 (Israel); Halevy, Orna, E-mail: halevyo@agri.huji.ac.il [Department of Animal Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot 76100 (Israel)

    2010-04-01

    Halofuginone, a novel inhibitor of Smad3 phosphorylation, has been shown to inhibit muscle fibrosis and to improve cardiac and skeletal muscle functions in the mdx mouse model of Duchenne muscular dystrophy. Here, we demonstrate that halofuginone promotes the phosphorylation of Akt and mitogen-activated protein kinase (MAPK) family members in a C2 muscle cell line and in primary myoblasts derived from wild-type and mdx mice diaphragms. Halofuginone enhanced the association of phosphorylated Akt and MAPK/extracellular signal-regulated protein kinase (ERK) with the non-phosphorylated form of Smad3, accompanied by a reduction in Smad3 phosphorylation levels. This reduction was reversed by inhibitors of the phosphoinositide 3'-kinase/Akt (PI3K/Akt) and MAPK/ERK pathways, suggesting their specific role in mediating halofuginone's inhibitory effect on Smad3 phosphorylation. Halofuginone enhanced Akt, MAPK/ERK and p38 MAPK phosphorylation and inhibited Smad3 phosphorylation in myotubes, all of which are crucial for myotube fusion. In addition, halofuginone increased the association Akt and MAPK/ERK with Smad3. As a consequence, halofuginone promoted myotube fusion, as reflected by an increased percentage of C2 and mdx myotubes containing high numbers of nuclei, and this was reversed by specific inhibitors of the PI3K and MAPK/ERK pathways. Together, the data suggest a role, either direct or via inhibition of Smad3 phosphorylation, for Akt or MAPK/ERK in halofuginone-enhanced myotube fusion, a feature which is crucial to improving muscle function in muscular dystrophies.

  5. PKA regulates calcineurin function through the phosphorylation of RCAN1: Identification of a novel phosphorylation site

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seon Sook; Lee, Eun Hye [Department of Molecular Bioscience, College of Biomedical Science, Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 200-701 (Korea, Republic of); Lee, Kooyeon [Department of Bio-Health Technology, College of Biomedical Science, Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 200-701 (Korea, Republic of); Jo, Su-Hyun, E-mail: suhyunjo@kangwon.ac.kr [Department of Physiology, BK21 Plus Graduate Program, Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 200-701 (Korea, Republic of); Seo, Su Ryeon, E-mail: suryeonseo@kangwon.ac.kr [Department of Molecular Bioscience, College of Biomedical Science, Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 200-701 (Korea, Republic of)

    2015-04-17

    Calcineurin is a calcium/calmodulin-dependent phosphatase that has been implicated in T cell activation through the induction of nuclear factors of activated T cells (NFAT). We have previously suggested that endogenous regulator of calcineurin (RCAN1, also known as DSCR1) is targeted by protein kinase A (PKA) for the control of calcineurin activity. In the present study, we characterized the PKA-mediated phosphorylation site in RCAN1 by mass spectrometric analysis and revealed that PKA directly phosphorylated RCAN1 at the Ser 93. PKA-induced phosphorylation and the increase in the half-life of the RCAN1 protein were prevented by the substitution of Ser 93 with Ala (S93A). Furthermore, the PKA-mediated phosphorylation of RCAN1 at Ser 93 potentiated the inhibition of calcineurin-dependent pro-inflammatory cytokine gene expression by RCAN1. Our results suggest the presence of a novel phosphorylation site in RCAN1 and that its phosphorylation influences calcineurin-dependent inflammatory target gene expression. - Highlights: • We identify novel phosphorylation sites in RCAN1 by LC-MS/MS analysis. • PKA-dependent phosphorylation of RCAN1 at Ser 93 inhibits calcineurin-mediated intracellular signaling. • We show the immunosuppressive function of RCAN1 phosphorylation at Ser 93 in suppressing cytokine expression.

  6. Functional Role of mTORC2 versus Integrin-Linked Kinase in Mediating Ser473-Akt Phosphorylation in PTEN-Negative Prostate and Breast Cancer Cell Lines.

    Science.gov (United States)

    Lee, Su-Lin; Chou, Chih-Chien; Chuang, Hsiao-Ching; Hsu, En-Chi; Chiu, Po-Chen; Kulp, Samuel K; Byrd, John C; Chen, Ching-Shih

    2013-01-01

    Although the rictor-mTOR complex (mTORC2) has been shown to act as phosphoinositide-dependent kinase (PDK)2 in many cell types, other kinases have also been implicated in mediating Ser473-Akt phosphorylation. Here, we demonstrated the cell line specificity of integrin-linked kinase (ILK) versus mTORC2 as PDK2 in LNCaP and PC-3 prostate and MDA-MB-468 breast cancer cells, of which the PTEN-negative status allowed the study of Ser473-Akt phosphorylation independent of external stimulation. PC-3 and MDA-MB-468 cells showed upregulated ILK expression relative to LNCaP cells, which expressed a high abundance of mTOR. Exposure to Ku-0063794, a second-generation mTOR inhibitor, decreased Ser473-Akt phosphorylation in LNCaP cells, but not in PC-3 or MDA-MB-468 cells. In contrast, treatment with T315, a novel ILK inhibitor, reduced the phosphorylation of Ser473-Akt in PC-3 and MDA-MB-468 cells without affecting that in LNCaP cells. This cell line specificity was verified by comparing Ser473-Akt phosphorylation status after genetic knockdown of rictor, ILK, and other putative Ser-473-Akt kinases. Genetic knockdown of rictor, but not ILK or the other kinases examined, inhibited Ser473-Akt phosphorylation in LNCaP cells. Conversely, PC-3 and MDA-MB-468 cells were susceptible to the effect of ILK silencing on Ser473-Akt phosphorylation, while knockdown of rictor or any of the other target kinases had no appreciable effect. Co-immunoprecipitation analysis demonstrated the physical interaction between ILK and Akt in PC-3 cells, and T315 blocked ILK-mediated Ser473 phosphorylation of bacterially expressed Akt. ILK also formed complexes with rictor in PC-3 and MDA-MB-468 cells that were disrupted by T315, but such complexes were not observed in LNCaP cells. In the PTEN-functional MDA-MB-231 cell line, both T315 and Ku-0063794 suppressed EGF-induced Ser473-Akt phosphorylation. Inhibition of ILK by T315 or siRNA-mediated knockdown suppressed epithelial-mesenchymal transition in MDA

  7. Functional Role of mTORC2 versus Integrin-Linked Kinase in Mediating Ser473-Akt Phosphorylation in PTEN-Negative Prostate and Breast Cancer Cell Lines.

    Directory of Open Access Journals (Sweden)

    Su-Lin Lee

    Full Text Available Although the rictor-mTOR complex (mTORC2 has been shown to act as phosphoinositide-dependent kinase (PDK2 in many cell types, other kinases have also been implicated in mediating Ser473-Akt phosphorylation. Here, we demonstrated the cell line specificity of integrin-linked kinase (ILK versus mTORC2 as PDK2 in LNCaP and PC-3 prostate and MDA-MB-468 breast cancer cells, of which the PTEN-negative status allowed the study of Ser473-Akt phosphorylation independent of external stimulation. PC-3 and MDA-MB-468 cells showed upregulated ILK expression relative to LNCaP cells, which expressed a high abundance of mTOR. Exposure to Ku-0063794, a second-generation mTOR inhibitor, decreased Ser473-Akt phosphorylation in LNCaP cells, but not in PC-3 or MDA-MB-468 cells. In contrast, treatment with T315, a novel ILK inhibitor, reduced the phosphorylation of Ser473-Akt in PC-3 and MDA-MB-468 cells without affecting that in LNCaP cells. This cell line specificity was verified by comparing Ser473-Akt phosphorylation status after genetic knockdown of rictor, ILK, and other putative Ser-473-Akt kinases. Genetic knockdown of rictor, but not ILK or the other kinases examined, inhibited Ser473-Akt phosphorylation in LNCaP cells. Conversely, PC-3 and MDA-MB-468 cells were susceptible to the effect of ILK silencing on Ser473-Akt phosphorylation, while knockdown of rictor or any of the other target kinases had no appreciable effect. Co-immunoprecipitation analysis demonstrated the physical interaction between ILK and Akt in PC-3 cells, and T315 blocked ILK-mediated Ser473 phosphorylation of bacterially expressed Akt. ILK also formed complexes with rictor in PC-3 and MDA-MB-468 cells that were disrupted by T315, but such complexes were not observed in LNCaP cells. In the PTEN-functional MDA-MB-231 cell line, both T315 and Ku-0063794 suppressed EGF-induced Ser473-Akt phosphorylation. Inhibition of ILK by T315 or siRNA-mediated knockdown suppressed epithelial

  8. Regulation of AKT phosphorylation at Ser473 and Thr308 by endoplasmic reticulum stress modulates substrate specificity in a severity dependent manner.

    Directory of Open Access Journals (Sweden)

    Hong Wa Yung

    Full Text Available Endoplasmic reticulum (ER stress is a common factor in the pathophysiology of diverse human diseases that are characterised by contrasting cellular behaviours, from proliferation in cancer to apoptosis in neurodegenerative disorders. Coincidently, dysregulation of AKT/PKB activity, which is the central regulator of cell growth, proliferation and survival, is often associated with the same diseases. Here, we demonstrate that ER stress modulates AKT substrate specificity in a severity-dependent manner, as shown by phospho-specific antibodies against known AKT targets. ER stress also reduces both total and phosphorylated AKT in a severity-dependent manner, without affecting activity of the upstream kinase PDK1. Normalisation to total AKT revealed that under ER stress phosphorylation of Thr308 is suppressed while that of Ser473 is increased. ER stress induces GRP78, and siRNA-mediated knock-down of GRP78 enhances phosphorylation at Ser473 by 3.6 fold, but not at Thr308. Substrate specificity is again altered. An in-situ proximity ligation assay revealed a physical interaction between GRP78 and AKT at the plasma membrane of cells following induction of ER stress. Staining was weak in cells with normal nuclear morphology but stronger in those displaying rounded, condensed nuclei. Co-immunoprecipitation of GRP78 and P-AKT(Ser473 confirmed the immuno-complex consists of non-phosphorylated AKT (Ser473 and Thr308. The interaction is likely specific as AKT did not bind to all molecular chaperones, and GRP78 did not bind to p70 S6 kinase. These findings provide one mechanistic explanation for how ER stress contributes to human pathologies demonstrating contrasting cell fates via modulation of AKT signalling.

  9. Urocortin 2 stimulates nitric oxide production in ventricular myocytes via Akt- and PKA-mediated phosphorylation of eNOS at serine 1177

    Science.gov (United States)

    Walther, Stefanie; Pluteanu, Florentina; Renz, Susanne; Nikonova, Yulia; Maxwell, Joshua T.; Yang, Li-Zhen; Schmidt, Kurt; Edwards, Joshua N.; Wakula, Paulina; Groschner, Klaus; Maier, Lars S.; Spiess, Joachim; Blatter, Lothar A.; Pieske, Burkert

    2014-01-01

    Urocortin 2 (Ucn2) is a cardioactive peptide exhibiting beneficial effects in normal and failing heart. In cardiomyocytes, it elicits cAMP- and Ca2+-dependent positive inotropic and lusitropic effects. We tested the hypothesis that, in addition, Ucn2 activates cardiac nitric oxide (NO) signaling and elucidated the underlying signaling pathways and mechanisms. In isolated rabbit ventricular myocytes, Ucn2 caused concentration- and time-dependent increases in phosphorylation of Akt (Ser473, Thr308), endothelial NO synthase (eNOS) (Ser1177), and ERK1/2 (Thr202/Tyr204). ERK1/2 phosphorylation, but not Akt and eNOS phosphorylation, was suppressed by inhibition of MEK1/2. Increased Akt phosphorylation resulted in increased Akt kinase activity and was mediated by corticotropin-releasing factor 2 (CRF2) receptors (astressin-2B sensitive). Inhibition of phosphatidylinositol 3-kinase (PI3K) diminished both Akt as well as eNOS phosphorylation mediated by Ucn2. Inhibition of protein kinase A (PKA) reduced Ucn2-induced phosphorylation of eNOS but did not affect the increase in phosphorylation of Akt. Conversely, direct receptor-independent elevation of cAMP via forskolin increased phosphorylation of eNOS but not of Akt. Ucn2 increased intracellular NO concentration ([NO]i), [cGMP], [cAMP], and cell shortening. Inhibition of eNOS suppressed the increases in [NO]i and cell shortening. When both PI3K-Akt and cAMP-PKA signaling were inhibited, the Ucn2-induced increases in [NO]i and cell shortening were attenuated. Thus, in rabbit ventricular myocytes, Ucn2 causes activation of cAMP-PKA, PI3K-Akt, and MEK1/2-ERK1/2 signaling. The MEK1/2-ERK1/2 pathway is not required for stimulation of NO signaling in these cells. The other two pathways, cAMP-PKA and PI3K-Akt, converge on eNOS phosphorylation at Ser1177 and result in pronounced and sustained cellular NO production with subsequent stimulation of cGMP signaling. PMID:25015964

  10. Reduced phosphorylation of brain insulin receptor substrate and Akt proteins in apolipoprotein-E4 targeted replacement mice.

    Science.gov (United States)

    Ong, Qi-Rui; Chan, Elizabeth S; Lim, Mei-Li; Cole, Gregory M; Wong, Boon-Seng

    2014-01-17

    Human ApoE4 accelerates memory decline in ageing and in Alzheimer's disease. Although intranasal insulin can improve cognition, this has little effect in ApoE4 subjects. To understand this ApoE genotype-dependent effect, we examined brain insulin signaling in huApoE3 and huApoE4 targeted replacement (TR) mice. At 32 weeks, lower insulin receptor substrate 1 (IRS1) at S636/639 and Akt phosphorylation at T308 were detected in fasting huApoE4 TR mice as compared to fasting huApoE3 TR mice. These changes in fasting huApoE4 TR mice were linked to lower brain glucose content and have no effect on plasma glucose level. However, at 72 weeks of age, these early changes were accompanied by reduction in IRS2 expression, IRS1 phosphorylation at Y608, Akt phosphorylation at S473, and MAPK (p38 and p44/42) activation in the fasting huApoE4 TR mice. The lower brain glucose was significantly associated with higher brain insulin in the aged huApoE4 TR mice. These results show that ApoE4 reduces brain insulin signaling and glucose level leading to higher insulin content.

  11. Platelet-derived growth factor-induced Akt phosphorylation requires mTOR/Rictor and phospholipase C-γ1, whereas S6 phosphorylation depends on mTOR/Raptor and phospholipase D

    Directory of Open Access Journals (Sweden)

    Razmara Masoud

    2013-01-01

    Full Text Available Abstract Mammalian target of rapamycin (mTOR can be found in two multi-protein complexes, i.e. mTORC1 (containing Raptor and mTORC2 (containing Rictor. Here, we investigated the mechanisms by which mTORC1 and mTORC2 are activated and their downstream targets in response to platelet-derived growth factor (PDGF-BB treatment. Inhibition of phosphatidylinositol 3-kinase (PI3K inhibited PDGF-BB activation of both mTORC1 and mTORC2. We found that in Rictor-null mouse embryonic fibroblasts, or after prolonged rapamycin treatment of NIH3T3 cells, PDGF-BB was not able to promote phosphorylation of Ser473 in the serine/threonine kinase Akt, whereas Thr308 phosphorylation was less affected, suggesting that Ser473 in Akt is phosphorylated in an mTORC2-dependent manner. This reduction in Akt phosphorylation did not influence the phosphorylation of the S6 protein, a well established protein downstream of mTORC1. Consistently, triciribine, an inhibitor of the Akt pathway, suppressed PDGF-BB-induced Akt phosphorylation without having any effect on S6 phosphorylation. Thus, mTORC2 does not appear to be upstream of mTORC1. We could also demonstrate that in Rictor-null cells the phosphorylation of phospholipase Cγ1 (PLCγ1 and protein kinase C (PKC was impaired, and the PKCα protein levels strongly reduced. Furthermore, interfering with the PLCγ/Ca2+/PKC pathway inhibited PDGF-BB-induced Akt phosphorylation. In addition, PDGF-BB-induced activation of mTORC1, as measured by phosphorylation of the downstream S6 protein, was dependent on phospholipase D (PLD. It has been shown that Erk1/2 MAP-kinase directly phosphorylates and activates mTORC1; in partial agreement with this finding, we found that a Mek1/2 inhibitor delayed S6 phosphorylation in response to PDGF-BB, but it did not block it. Thus, whereas both mTORC1 and mTORC2 are activated in a PI3K-dependent manner, different additional signaling pathways are needed. mTORC1 is activated in a PLD-dependent manner

  12. Increased Phosphorylation of PI3K/Akt/mTOR in the Obstructed Kidney of Rats with Unilateral Ureteral Obstruction

    OpenAIRE

    Ma, Seong Kwon; Joo, Soo Yeon; Kim, Chang Seong; Choi, Joon Seok; Bae, Eun Hui; Lee, JongUn; Kim, Soo Wan

    2013-01-01

    The present study aimed to investigate changes in the mammalian target of rapamycin (mTOR) signaling pathway in the obstructed kidney of rats with unilateral ureteral obstruction (UUO). Male Sprague-Dawley rats were unilaterally obstructed by ligation of the left proximal ureter for 7 days. Control rats were treated in the same way except that no ligature was made. The expression levels of phosphorylated phosphatidylinositol 3-kinase (PI3K), Akt, and mTOR were determined in the kidney by semi...

  13. Targeted deletion of Kif18a protects from colitis-associated colorectal (CAC) tumors in mice through impairing Akt phosphorylation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Houbao [State Key Laboratory of Medical Genomics, Research Center for Experimental Medicine, Rui-Jin Hospital and Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai 200025 (China); Xu, Wangyang [Department of Clinical Laboratories, Ninth People’s Hospital, SJTUSM, Shanghai 200011 (China); Zhang, Hongxin [State Key Laboratory of Medical Genomics, Research Center for Experimental Medicine, Rui-Jin Hospital and Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai 200025 (China); Liu, Jianbing [State Key Laboratory of Medical Genomics, Research Center for Experimental Medicine, Rui-Jin Hospital and Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai 200025 (China); Shanghai Research Center for Model Organisms, Shanghai 201203 (China); Xu, Haimin [Department of Pathology, Rui-Jin Hospital, SJTUSM, Shanghai 200025 (China); Lu, Shunyuan; Dang, Suying [State Key Laboratory of Medical Genomics, Research Center for Experimental Medicine, Rui-Jin Hospital and Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai 200025 (China); Kuang, Ying [Shanghai Research Center for Model Organisms, Shanghai 201203 (China); Jin, Xiaolong [Department of Pathology, Rui-Jin Hospital, SJTUSM, Shanghai 200025 (China); Wang, Zhugang, E-mail: zhugangw@shsmu.edu.cn [State Key Laboratory of Medical Genomics, Research Center for Experimental Medicine, Rui-Jin Hospital and Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai 200025 (China); Shanghai Research Center for Model Organisms, Shanghai 201203 (China)

    2013-08-16

    Highlights: •Kif18A is up-regulated in CAC of mouse model. •Kif18a{sup −/−} mice are protected from CAC. •Tumor cells from Kif18a{sup −/−} mice undergo more apoptosis. •Kif18A deficiency induces poor Atk phosphorylation. -- Abstract: Kinesins are a superfamily of molecular motors involved in cell division or intracellular transport. They are becoming important targets for chemotherapeutic intervention of cancer due to their crucial role in mitosis. Here, we demonstrate that the kinesin-8 Kif18a is overexpressed in murine CAC and is a crucial promoter during early CAC carcinogenesis. Kif18a-deficient mice are evidently protected from AOM–DSS-induced colon carcinogenesis. Kif18A is responsible for proliferation of colonic tumor cells, while Kif18a ablation in mice promotes cell apoptosis. Mechanistically, Kif18a is responsible for induction of Akt phosphorylation, which is known to be associated with cell survival regulation. In conclusion, Kif18a is critical for colorectal carcinogenesis in the setting of inflammation by mechanisms of increased PI3K-AKT signaling. Inhibition of Kif18A activity may be useful in the prevention or chemotherapeutic intervention of CAC.

  14. Targeted deletion of Kif18a protects from colitis-associated colorectal (CAC) tumors in mice through impairing Akt phosphorylation

    International Nuclear Information System (INIS)

    Highlights: •Kif18A is up-regulated in CAC of mouse model. •Kif18a−/− mice are protected from CAC. •Tumor cells from Kif18a−/− mice undergo more apoptosis. •Kif18A deficiency induces poor Atk phosphorylation. -- Abstract: Kinesins are a superfamily of molecular motors involved in cell division or intracellular transport. They are becoming important targets for chemotherapeutic intervention of cancer due to their crucial role in mitosis. Here, we demonstrate that the kinesin-8 Kif18a is overexpressed in murine CAC and is a crucial promoter during early CAC carcinogenesis. Kif18a-deficient mice are evidently protected from AOM–DSS-induced colon carcinogenesis. Kif18A is responsible for proliferation of colonic tumor cells, while Kif18a ablation in mice promotes cell apoptosis. Mechanistically, Kif18a is responsible for induction of Akt phosphorylation, which is known to be associated with cell survival regulation. In conclusion, Kif18a is critical for colorectal carcinogenesis in the setting of inflammation by mechanisms of increased PI3K-AKT signaling. Inhibition of Kif18A activity may be useful in the prevention or chemotherapeutic intervention of CAC

  15. Luteolin Inhibits Angiotensin II-Stimulated VSMC Proliferation and Migration through Downregulation of Akt Phosphorylation

    Directory of Open Access Journals (Sweden)

    Tongda Xu

    2015-01-01

    Full Text Available Luteolin is a naturally occurring flavonoid found in many plants that possesses cardioprotective properties. The purpose of this study was to elucidate the effect of luteolin on vascular smooth muscle cells (VSMCs proliferation and migration induced by Angiotensin II (Ang II and to investigate the mechanism(s of action of this compound. Rat VSMCs were cultured in vitro, and the proliferation and migration of these cells following Ang II stimulation were monitored. Different doses of luteolin were added to VSMC cultures, and the proliferation and migration rate were observed by MTT and Transwell chamber assays, respectively. In addition, the expressions of p-Akt (308, p-Akt (473, and proliferative cell nuclear antigen (PCNA in VSMCs were monitored by Western blotting. This study demonstrated that luteolin has an inhibitory effect on Ang II-induced VSMC proliferation and migration. Further, the levels of p-Akt (308, p-Akt (473, and PCNA were reduced in VSMCs treated with both Ang II and luteolin compared to VSMCs treated with only Ang II. These findings strongly suggest that luteolin inhibits Ang II-stimulated proliferation and migration of VSMCs, which is partially due to downregulation of the Akt signaling pathway.

  16. Suppression of Akt1 phosphorylation by adenoviral transfer of the PTEN gene inhibits hypoxia-induced proliferation of rat pulmonary arterial smooth muscle cells

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Chunxia [Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Yi, Bin, E-mail: yibin1974@163.com [Department of Anesthesia, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Institute of Respiratory Disease, Xinqiao Hospital, Third Military Medical University, Chongqing 400037 (China); Bai, Li [Institute of Respiratory Disease, Xinqiao Hospital, Third Military Medical University, Chongqing 400037 (China); Xia, Yongzhi [Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China); Wang, Guansong; Qian, Guisheng [Institute of Respiratory Disease, Xinqiao Hospital, Third Military Medical University, Chongqing 400037 (China); Feng, Hua [Department of Neurosurgery, Southwest Hospital, Third Military Medical University, Chongqing 400038 (China)

    2010-07-02

    Recent findings identify the role of proliferation of pulmonary artery smooth muscle cells (PASMCs) in pulmonary vascular remodeling. Phosphoinositide 3 kinase (PI3K) and serine/threonine kinase (Akt) proteins are expressed in vascular smooth muscle cells. In addition, phosphatase and tensin homolog deleted on chromosome 10 (PTEN) has been identified as a negative regulator of cytokine signaling that inhibits the PI3K-Akt pathway. However, little is known about the role of PTEN/Akt signaling in hypoxia-associated vascular remodeling. In this study, we found that hypoxia-induced the expression of Akt1 mRNA and phosphorylated protein by at least twofold in rat PASMCs. Phospho-PTEN significantly decreased in the nuclei of PASMCs after hypoxic stimulation. After forcing over-expression of PTEN by adenovirus-mediated PTEN (Ad-PTEN) transfection, the expression of phospho-Akt1 was significantly suppressed in PASMCs at all time-points measured. Additionally, we showed here that hypoxia increased proliferation of PASMCs by nearly twofold and over-expression of PTEN significantly inhibited hypoxia-induced PASMCs proliferation. These findings suggest that phospho-PTEN loss in the nuclei of PASMCs under hypoxic conditions may be the major cause of aberrant activation of Akt1 and may, therefore, play an important role in hypoxia-associated pulmonary arterial remodeling. Finally, the fact that transfection with Ad-PTEN inhibits the phosphorylation of Akt1 in PASMCs suggests a potential therapeutic effect on hypoxia-associated pulmonary arterial remodeling.

  17. Neuronal AKAP150 coordinates PKA and Epac-mediated PKB/Akt phosphorylation

    NARCIS (Netherlands)

    Nijholt, Ingrid M.; Dolga, Amalia M.; Ostroveanu, Anghelus; Luiten, Paul G. M.; Schmidt, Martina; Eisel, Ulrich L. M.

    2008-01-01

    In diverse neuronal processes ranging from neuronal survival to synaptic plasticity cyclic adenosine monophosphate (cAMP)-dependent signaling is tightly connected with the protein kinase B (PKB)/Akt pathway but the precise nature of this connection remains unknown. In the current study we investigat

  18. Phosphorylation site on yeast pyruvate dehydrogenase complex

    International Nuclear Information System (INIS)

    The pyruvate dehydrogenase complex was purified to homogeneity from baker's yeast (Saccharomyces cerevisiae). Yeast cells were disrupted in a Manton-Gaulin laboratory homogenizer. The pyruvate dehydrogenase complex was purified by fractionation with polyethylene glycol, isoelectric precipitation, ultracentrifugation and chromatography on hydroxylapatite. Final purification of the yeast pyruvate dehydrogenase complex was achieved by cation-exchange high pressure liquid chromatography (HPLC). No endogenous pyruvate dehydrogenase kinase activity was detected during the purification. However, the yeast pyruvate dehydrogenase complex was phosphorylated and inactivated with purified pyruvate dehydrogenase kinase from bovine kidney. Tryptic digestion of the 32P-labeled complex yielded a single phosphopeptide which was purified to homogeniety. The tryptic digest was subjected to chromatography on a C-18 reverse phase HPLC column with a linear gradient of acetonitrile. Radioactive fractions were pooled, concentrated, and subjected to anion-exchange HPLC. The column was developed with a linear gradient of ammonium acetate. Final purification of the phosphopeptide was achieved by chromatography on a C-18 reverse phase HPLC column developed with a linear gradient of acetonitrile. The amino acid sequence of the homogeneous peptide was determined by manual modified Edman degradation

  19. Identification of Phosphorylation Sites Regulating sst3 Somatostatin Receptor Trafficking.

    Science.gov (United States)

    Lehmann, Andreas; Kliewer, Andrea; Günther, Thomas; Nagel, Falko; Schulz, Stefan

    2016-06-01

    The human somatostatin receptor 3 (sst3) is expressed in about 50% of all neuroendocrine tumors and hence a promising target for multireceptor somatostatin analogs. The sst3 receptor is unique among ssts in that it exhibits a very long intracellular C-terminal tail containing a huge number of potential phosphate acceptor sites. Consequently, our knowledge about the functional role of the C-terminal tail in sst3 receptor regulation is very limited. Here, we have generated a series of phosphorylation-deficient mutants that enabled us to determine crucial sites for its agonist-induced β-arrestin mobilization, internalization, and down-regulation. Based on this information, we generated phosphosite-specific antibodies for C-terminal Ser(337)/Thr(341), Thr(348), and Ser(361) that enabled us to investigate the temporal patterns of sst3 phosphorylation and dephosphorylation. We found that the endogenous ligand somatostatin induced a rapid and robust phosphorylation that was completely blocked by the sst3 antagonist NVP-ACQ090. The stable somatostatin analogs pasireotide and octreotide promoted clearly less phosphorylation compared with somatostatin. We also show that sst3 phosphorylation occurred within seconds to minutes, whereas dephosphorylation of the sst3 receptor occurred at a considerable slower rate. In addition, we also identified G protein-coupled receptor kinases 2 and 3 and protein phosphatase 1α and 1β as key regulators of sst3 phosphorylation and dephosphorylation, respectively. Thus, we here define the C-terminal phosphorylation motif of the human sst3 receptor that regulates its agonist-promoted phosphorylation, β-arrestin recruitment, and internalization of this clinically relevant receptor.

  20. Sustained oxidative stress causes late acute renal failure via duplex regulation on p38 MAPK and Akt phosphorylation in severely burned rats.

    Directory of Open Access Journals (Sweden)

    Yafei Feng

    Full Text Available BACKGROUND: Clinical evidence indicates that late acute renal failure (ARF predicts high mortality in severely burned patients but the pathophysiology of late ARF remains undefined. This study was designed to test the hypothesis that sustained reactive oxygen species (ROS induced late ARF in a severely burned rat model and to investigate the signaling mechanisms involved. MATERIALS AND METHODS: Rats were exposed to 100°C bath for 15 s to induce severe burn injury (40% of total body surface area. Renal function, ROS generation, tubular necrosis and apoptosis, and phosphorylation of MAPK and Akt were measured during 72 hours after burn. RESULTS: Renal function as assessed by serum creatinine and blood urea nitrogen deteriorated significantly at 3 h after burn, alleviated at 6 h but worsened at 48 h and 72 h, indicating a late ARF was induced. Apoptotic cells and cleavage caspase-3 in the kidney went up slowly and turned into significant at 48 h and 72 h. Tubular cell ROS production shot up at 6 h and continuously rose during the 72-h experiment. Scavenging ROS with tempol markedly attenuated tubular apoptosis and renal dysfunction at 72 h after burn. Interestingly, renal p38 MAPK phosphorylation elevated in a time dependent manner whereas Akt phosphorylation increased during the first 24 h but decreased at 48 h after burn. The p38 MAPK specific inhibitor SB203580 alleviated whereas Akt inhibitor exacerbated burn-induced tubular apoptosis and renal dysfunction. Furthermore, tempol treatment exerted a duplex regulation through inhibiting p38 MAPK phosphorylation but further increasing Akt phosphorylation at 72 h postburn. CONCLUSIONS: These results demonstrate that sustained renal ROS overproduction induces continuous tubular cell apoptosis and thus a late ARF at 72 h after burn in severely burned rats, which may result from ROS-mediated activation of p38 MAPK but a late inhibition of Akt phosphorylation.

  1. Vitamin B₂ Sensitizes Cancer Cells to Vitamin-C-Induced Cell Death via Modulation of Akt and Bad Phosphorylation.

    Science.gov (United States)

    Chen, Ni; Yin, Shutao; Song, Xinhua; Fan, Lihong; Hu, Hongbo

    2015-08-01

    Vitamin C is an essential dietary nutrient that has a variety of biological functions. Recent studies have provided promising evidence for its additional health benefits, including anticancer activity. Vitamin B2, another essential dietary nutrient, often coexists with vitamin C in some fruits, vegetables, or dietary supplements. The objective of the present study is to determine whether the combination of vitamin C and B2 can achieve a synergistic anticancer activity. MDA-MB-231, MCF-7, and A549 cells were employed to evaluate the combinatory effects of vitamin C and B2. We found that the combination of vitamin C and B2 resulted in a synergistic cell death induction in all cell lines tested. Further mechanistic investigations revealed that vitamin B2 sensitized cancer cells to vitamin C through inhibition of Akt and Bad phosphorylation. Our findings identified vitamin B2 as a promising sensitizer for improving the efficacy of vitamin-C-based cancer chemoprevention and chemotherapy.

  2. Expression of human apolipoprotein E4 reduces insulin-receptor substrate 1 expression and Akt phosphorylation in the ageing liver

    Directory of Open Access Journals (Sweden)

    Qi-Rui Ong

    2014-01-01

    Full Text Available The diabetic drug rosiglitazone was reported to improve glucose tolerance in insulin-resistant ApoE3 but not ApoE4 knock-in mice. We therefore examined whether apolipoprotein E (ApoE has genotype-specific effects on liver insulin function. At 12 weeks, no difference in liver insulin signaling was detected between fasting ApoE3 and ApoE4 mice. At 72 weeks however, ApoE4 mice had lower IRS-1 and PI3K expression, and reduced Akt phosphorylation. This decline was associated with lower insulin and higher glucose in ApoE4 mouse liver. Liver cholesterol was not affected. These results show that ApoE4 expression reduces liver insulin signaling and insulin levels, leading to higher glucose content.

  3. Sialidase NEU3 dynamically associates to different membrane domains specifically modifying their ganglioside pattern and triggering Akt phosphorylation.

    Directory of Open Access Journals (Sweden)

    Dario Bonardi

    Full Text Available Lipid rafts are known to regulate several membrane functions such as signaling, trafficking and cellular adhesion. The local enrichment in sphingolipids and cholesterol together with the low protein content allows their separation by density gradient flotation after extraction with non-ionic detergent at low temperature. These structures are also referred to as detergent resistant membranes (DRM. Among sphingolipids, gangliosides play important roles in different biological events, including signal transduction and tumorigenesis. Sialidase NEU3 shows high enzymatic specificity toward gangliosides. Moreover, the enzyme is present both at the cell surface and in endosomal structures and cofractionates with caveolin. Although changes in the expression level of NEU3 have been correlated to different tumors, little is known about the precise distribution of the protein and its ability in modifying the ganglioside composition of DRM and non-DRM, thus regulating intracellular events. By means of inducible expression cell system we found that i newly synthesized NEU3 is initially associated to non-DRM; ii at steady state the protein is equally distributed between the two membrane subcompartments, i.e., DRM and non-DRM; iii NEU3 is degraded via the proteasomal pathway; iv the enzyme specifically modifies the ganglioside composition of the membrane areas where it resides; and v NEU3 triggers phosphorylation of Akt, even in absence of exogenously administered EGF. Taken together our data demonstrate that NEU3 regulates the DRM ganglioside content and it can be considered as a modulator of Akt phosphorylation, further supporting the role of this enzyme in cancer and tumorigenesis.

  4. Identification of a novel phosphorylation site on TBC1D4 regulated by AMP-activated protein kinase in skeletal muscle

    DEFF Research Database (Denmark)

    Treebak, Jonas Thue; Taylor, Eric B.; Witczak, Carol A.;

    2010-01-01

    . The majority of known phosphorylation sites on TBC1D4 lie within the Akt consensus motif and are phosphorylated by insulin stimulation. However, the 5 AMP activated protein kinase (AMPK) and other kinases may also phosphorylate TBC1D4, and therefore we hypothesized the presence of additional phosphorylation......TBC1D4 (also known as AS160) regulates GLUT4 translocation and glucose uptake in adipocytes and skeletal muscle. Its mode of action involves phosphorylation of Serine (S)/Threonine (T) residues by upstream kinases resulting in inactivation of Rab-GAP activity leading to GLUT4 mobilization...... that S711 would be recognized by AMPK. Using a phospho-specific antibody against S711, we found that AICAR and contraction increased S711 phosphorylation in mouse skeletal muscle and this increase was abolished in muscle-specific AMPKalpha2 kinase dead transgenic mice. Exercise in human vastus lateralis...

  5. CCN1 acutely increases nitric oxide production via integrin αvβ3-Akt-S6K-phosphorylation of endothelial nitric oxide synthase at the serine 1177 signaling axis.

    Science.gov (United States)

    Hwang, Soojin; Lee, Hyeon-Ju; Kim, Gyungah; Won, Kyung-Jong; Park, Yoon Shin; Jo, Inho

    2015-12-01

    Although CCN1 (also known as cysteine-rich, angiogenic inducer 61, CYR61) has been reported to promote angiogenesis and neovascularization in endothelial cells (ECs), its effects on endothelial nitric oxide (NO) production have never been studied. Using human umbilical vein ECs, we investigated whether and how CCN1 regulates NO production. CCN1 acutely increased NO production in a time- and dose-dependent manner, which was accompanied by increased phosphorylation of endothelial NO synthase (eNOS) at serine 1177 (eNOS-Ser(1177)), but not that of eNOS-Thr(495) or eNOS-Ser(114). The level of total eNOS expression was unaltered. Treatment with either LY294002, a selective inhibitor of phosphoinositide 3-kinase known as an upstream kinase of Akt, or H-89, an inhibitor of protein kinase A, mitogen- and stress-activated protein kinase 1, Rho-associated protein kinase 2, and ribosomal protein S6 kinase (S6K), inhibited CCN1-stimulated eNOS-Ser(1177) phosphorylation and subsequent NO production. Ectopic expression of small interfering RNA against Akt and S6K significantly inhibited the effects of CCN1. Consistently, CCN1 increased the phosphorylation of Akt-Ser(473) and S6K-Thr(389). However, CCN1 did not alter the expression or secretion of VEGF, a known downstream factor of CCN1 and a potential upstream factor of Akt-mediated eNOS-Ser(1177) phosphorylation. Furthermore, neutralization of integrin αvβ3 with corresponding antibody completely reversed all of the observed effects of CCN1. Moreover, CCN1 increased acetylcholine-induced relaxation in the rat aortas. Finally, we also found that CCN1-stimulated eNOS-Ser(1177) phosphorylation and NO production are true for other types of EC tested. In conclusion, CCN1 acutely increases NO production via activation of a signaling axis in integrin αvβ3-Akt-S6K-eNOS-Ser(1177) phosphorylation, suggesting an important role for CCN1 in vasodilation.

  6. Mucin 3 is involved in intestinal epithelial cell apoptosis via N-(3-oxododecanoyl)-L-homoserine lactone-induced suppression of Akt phosphorylation.

    Science.gov (United States)

    Taguchi, Ryoko; Tanaka, Shinya; Joe, Ga-Hyun; Maseda, Hideaki; Nomura, Nobuhiko; Ohnishi, Junji; Ishizuka, Satoshi; Shimizu, Hidehisa; Miyazaki, Hitoshi

    2014-07-15

    N-acyl-homoserine lactones (AHL) are quorum-sensing molecules in bacteria that play important roles in regulating virulence gene expression in pathogens such as Pseudomonas aeruginosa. The present study compared responses between undifferentiated and differentiated Caco-2 cells to N-(3-oxododecanoyl)-L-homoserine lactone (3-oxo-C12-HSL). A low concentration of 3-oxo-C12-HSL (30 μM) is sufficient to reduce viability accompanied by apoptosis via the suppression of phosphorylation by Akt in undifferentiated Caco-2 cells. The suppression of Akt phosphorylation appears specific in 3-oxo-C12-HSL, because other AHLs did not influence the phosphorylation status of Akt. The reduced viability induced by 3-oxo-C12-HSL was partially recovered by constitutively active Akt overexpression in undifferentiated Caco-2 cells. Since mucin is considered a vital component of the gut barrier, we investigated whether mucin protects cellular functions induced by 3-oxo-C12-HSL in undifferentiated Caco-2 cells. The results showed that mucin protected undifferentiated Caco-2 cells from apoptosis induced by 3-oxo-C12-HSL. 3-Oxo-C12-HSL did not induce cell death in differentiated Caco-2 cells that expressed higher levels of mucin 3 (MUC3) than undifferentiated Caco-2 cells. In addition, 3-oxo-C12-HSL promoted cell death in undifferentiated Caco-2 cells transfected with MUC3 siRNA and reduced MUC3 expression in undifferentiated Caco-2 cells. Therefore, MUC3 might be responsible for the survival of undifferentiated intestinal epithelial cells in the presence of 3-oxo-C12-HSL through regulating Akt phosphorylation. In conclusion, 3-oxo-C12-HSL might influence the survival of undifferentiated intestinal epithelial cells as well as interactions between these cells and pathogens.

  7. PhosphoRice: a meta-predictor of rice-specific phosphorylation sites

    OpenAIRE

    Que, Shufu; Li, Kuan; Chen, Min; Wang, Yongfei; Yang, Qiaobin; Zhang, Wenfeng; Zhang, Baoqian; Xiong, Bangshu; He, Huaqin

    2012-01-01

    Background As a result of the growing body of protein phosphorylation sites data, the number of phosphoprotein databases is constantly increasing, and dozens of tools are available for predicting protein phosphorylation sites to achieve fast automatic results. However, none of the existing tools has been developed to predict protein phosphorylation sites in rice. Results In this paper, the phosphorylation site predictors, NetPhos 2.0, NetPhosK, Kinasephos, Scansite, Disphos and Predphosphos, ...

  8. PhosphoRice: a meta-predictor of rice-specific phosphorylation sites

    OpenAIRE

    Que Shufu; Li Kuan; Chen Min; Wang Yongfei; Yang Qiaobin; Zhang Wenfeng; Zhang Baoqian; Xiong Bangshu; He Huaqin

    2012-01-01

    Abstract Background As a result of the growing body of protein phosphorylation sites data, the number of phosphoprotein databases is constantly increasing, and dozens of tools are available for predicting protein phosphorylation sites to achieve fast automatic results. However, none of the existing tools has been developed to predict protein phosphorylation sites in rice. Results In this paper, the phosphorylation site predictors, NetPhos 2.0, NetPhosK, Kinasephos, Scansite, Disphos and Predp...

  9. PFKL/miR-128 axis regulates glycolysis by inhibiting AKT phosphorylation and predicts poor survival in lung cancer.

    Science.gov (United States)

    Yang, Jie; Li, Jingqiu; Le, Yanping; Zhou, Chengwei; Zhang, Shun; Gong, Zhaohui

    2016-01-01

    MicroRNAs (miRNAs) affect cancer cell glucose metabolism by targeting mRNAs of diverse enzymes that have been implicated in oxidative phosphorylation (OXPHOS) and glycolytic pathways. However, the mechanisms that underlie miRNA-mediated regulation of phosphofructokinase (PFK), a key rate-limiting enzyme in glycolysis, remain largely unknown. Here, we show that miR-128 directly targets PFK liver type (PFKL) in lung cancer cells and regulates endogenous expression of PFKL at both the mRNA and protein levels. In line with this, overexpression of miR-128 decreased glucose uptake and lactate production, as well as increased cellular ATP content. Interestingly, knockdown of miR-128 was shown to promote lung cancer cell growth and colony formation. Moreover, we observed that miR-128 expression inversely correlated with PFKL mRNA levels in clinic lung cancer samples and that increased PFKL expression predicted poor overall survival in lung cancer patients. Mechanistically, we showed that miR-128 regulates PFKL via a feedback loop that involves inhibition of the AKT signaling pathway. Together, our results suggest that miR-128 acts as a metabolic regulator in lung cancer cells that may be therapeutically exploited. PMID:27186417

  10. Bioinformatics Study of Cancer-Related Mutations within p53 Phosphorylation Site Motifs

    Directory of Open Access Journals (Sweden)

    Xiaona Ji

    2014-07-01

    Full Text Available p53 protein has about thirty phosphorylation sites located at the N- and C-termini and in the core domain. The phosphorylation sites are relatively less mutated than other residues in p53. To understand why and how p53 phosphorylation sites are rarely mutated in human cancer, using a bioinformatics approaches, we examined the phosphorylation site and its nearby flanking residues, focusing on the consensus phosphorylation motif pattern, amino-acid correlations within the phosphorylation motifs, the propensity of structural disorder of the phosphorylation motifs, and cancer mutations observed within the phosphorylation motifs. Many p53 phosphorylation sites are targets for several kinases. The phosphorylation sites match 17 consensus sequence motifs out of the 29 classified. In addition to proline, which is common in kinase specificity-determining sites, we found high propensity of acidic residues to be adjacent to phosphorylation sites. Analysis of human cancer mutations in the phosphorylation motifs revealed that motifs with adjacent acidic residues generally have fewer mutations, in contrast to phosphorylation sites near proline residues. p53 phosphorylation motifs are mostly disordered. However, human cancer mutations within phosphorylation motifs tend to decrease the disorder propensity. Our results suggest that combination of acidic residues Asp and Glu with phosphorylation sites provide charge redundancy which may safe guard against loss-of-function mutations, and that the natively disordered nature of p53 phosphorylation motifs may help reduce mutational damage. Our results further suggest that engineering acidic amino acids adjacent to potential phosphorylation sites could be a p53 gene therapy strategy.

  11. Increased phosphorylation of skeletal muscle glycogen synthase at NH2-terminal sites during physiological hyperinsulinemia in type 2 diabetes

    DEFF Research Database (Denmark)

    Højlund, Kurt; Staehr, Peter; Hansen, Bo Falck;

    2003-01-01

    In type 2 diabetes, insulin activation of muscle glycogen synthase (GS) is impaired. This defect plays a major role for the development of insulin resistance and hyperglycemia. In animal muscle, insulin activates GS by reducing phosphorylation at both NH(2)- and COOH-terminal sites, but the mecha......In type 2 diabetes, insulin activation of muscle glycogen synthase (GS) is impaired. This defect plays a major role for the development of insulin resistance and hyperglycemia. In animal muscle, insulin activates GS by reducing phosphorylation at both NH(2)- and COOH-terminal sites......, but the mechanism involved in human muscle and the defect in type 2 diabetes remain unclear. We studied the effect of insulin at physiological concentrations on glucose metabolism, insulin signaling and phosphorylation of GS in skeletal muscle from type 2 diabetic and well-matched control subjects during euglycemic......-hyperinsulinemic clamps. Analysis using phospho-specific antibodies revealed that insulin decreases phosphorylation of sites 3a + 3b in human muscle, and this was accompanied by activation of Akt and inhibition of glycogen synthase kinase-3alpha. In type 2 diabetic subjects these effects of insulin were fully intact...

  12. The Transcription Factor Bach2 Is Phosphorylated at Multiple Sites in Murine B Cells but a Single Site Prevents Its Nuclear Localization.

    Science.gov (United States)

    Ando, Ryo; Shima, Hiroki; Tamahara, Toru; Sato, Yoshihiro; Watanabe-Matsui, Miki; Kato, Hiroki; Sax, Nicolas; Motohashi, Hozumi; Taguchi, Keiko; Yamamoto, Masayuki; Nio, Masaki; Maeda, Tatsuya; Ochiai, Kyoko; Muto, Akihiko; Igarashi, Kazuhiko

    2016-01-22

    The transcription factor Bach2 regulates the immune system at multiple points, including class switch recombination (CSR) in activated B cells and the function of T cells in part by restricting their terminal differentiation. However, the regulation of Bach2 expression and its activity in the immune cells are still unclear. Here, we demonstrated that Bach2 mRNA expression decreased in Pten-deficient primary B cells. Bach2 was phosphorylated in primary B cells, which was increased upon the activation of the B cell receptor by an anti-immunoglobulin M (IgM) antibody or CD40 ligand. Using specific inhibitors of kinases, the phosphorylation of Bach2 in activated B cells was shown to depend on the phosphatidylinositol 3-kinase (PI3K)-Akt-mammalian target of rapamycin (mTOR) pathway. The complex of mTOR and Raptor phosphorylated Bach2 in vitro. We identified multiple new phosphorylation sites of Bach2 by mass spectrometry analysis of epitope-tagged Bach2 expressed in the mature B cell line BAL17. Among the sites identified, serine 535 (Ser-535) was critical for the regulation of Bach2 because a single mutation of Ser-535 abolished cytoplasmic accumulation of Bach2, promoting its nuclear accumulation in pre-B cells, whereas Ser-509 played an auxiliary role. Bach2 repressor activity was enhanced by the Ser-535 mutation in B cells. These results suggest that the PI3K-Akt-mTOR pathway inhibits Bach2 by both repressing its expression and inducing its phosphorylation in B cells. PMID:26620562

  13. Constitutive phosphorylation of the mTORC2/Akt/4E-BP1 pathway in newly derived canine hemangiosarcoma cell lines

    Directory of Open Access Journals (Sweden)

    Murai Atsuko

    2012-07-01

    Full Text Available Abstract Background Canine hemangiosarcoma (HSA is a malignant tumor with poor long-term prognosis due to development of metastasis despite aggressive treatment. The phosphatidyl-inositol-3 kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR pathway is involved in its endothelial pathologies; however, it remains unknown how this pathway plays a role in canine HSA. Here, we characterized new canine HSA cell lines derived from nude mice-xenografted canine HSAs and investigated the deregulation of the signaling pathways in these cell lines. Results Seven canine HSA cell lines were established from 3 xenograft canine HSAs and showed characteristics of endothelial cells (ECs, that is, uptake of acetylated low-density lipoprotein and expression of canine-specific CD31 mRNA. They showed varied morphologies and mRNA expression levels for VEGF-A, bFGF, HGF, IGF-I, EGF, PDGF-B, and their receptors. Cell proliferation was stimulated by these growth factors and fetal bovine serum (FBS in 1 cell line and by FBS alone in 3 cell lines. However, cell proliferation was not stimulated by growth factors and FBS in the remaining 3 cell lines. Phosphorylated p44/42 Erk1/2 was increased by FBS stimulation in 4 cell lines. In contrast, phosphorylation of Akt at Ser473, mTOR complex 1 (mTORC1 at Ser2448, and eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1 at Ser65 was high in serum-starved condition and not altered by FBS stimulation in 6 cell lines, despite increased phosphorylation of these residues in normal canine ECs. This suggested that the mTORC2/Akt/4E-BP1 pathway was constitutively activated in these 6 canine HSA cell lines. After cell inoculation into nude mice, canine HSA tumors were formed from 4 cell lines and showed Akt and 4E-BP1 phosphorylation identical to the parental cell lines. Conclusions Our findings suggest that the present cell lines may be useful tools for investigating the role of the mTORC2/Akt/4E-BP1 pathway in

  14. AKT/mTOR substrate P70S6K is frequently phosphorylated in gallbladder cancer tissue and cell lines

    Directory of Open Access Journals (Sweden)

    Leal P

    2013-10-01

    Full Text Available Pamela Leal,1,* Patricia Garcia,2,* Alejandra Sandoval,1 Kurt Buchegger,1 Helga Weber,1 Oscar Tapia,1 Juan C Roa1,2 1Department of Pathology, Universidad de La Frontera, Center of Genetical and Immunological Studies-Scientific and Technological Bioresource Nucleus, Temuco, 2Department of Pathology, Pontificia Universidad Catolica de Chile, Santiago, Chile *These authors contributed equally to this paperBackground: Gallbladder carcinoma is a highly malignant tumor and a public health problem in some parts of the world. It is characterized by a poor prognosis and its resistance to radio and chemotherapy. There is an urgent need to develop novel therapeutic alternatives for the treatment of gallbladder carcinoma. The mammalian target of the rapamycin (mTOR signaling pathway is activated in about 50% of human malignancies, and its role in gallbladder carcinoma has previously been suggested. In the present study, we investigated the phosphorylation status of the mTOR substrate p70S6K in preneoplastic and neoplastic gallbladder tissues and evaluated the effect of three mTOR inhibitors on cell growth and migration in gallbladder carcinoma cell lines.Methods: Immunohistochemical staining of phospho-p70S6K was analyzed in 181 gallbladder carcinoma cases, classified according to lesion type as dysplasia, early carcinoma, or advanced carcinoma. Protein expression of AKT/mTOR members was also evaluated in eight gallbladder carcinoma cell lines by Western blot analysis. We selected two gallbladder carcinoma cell lines (G415 and TGBC-2TKB to evaluate the effect of rapamycin, RAD001, and AZD8055 on cell viability, cell migration, and protein expression.Results: Our results showed that phospho-p70S6K is highly expressed in dysplasia (66.7%, 12/18, early cancer (84.6%, 22/26, and advanced cancer (88.3%, 121/137. No statistical correlation was observed between phospho-p70S6K status and any clinical or pathological features, including age, gender, ethnicity, wall

  15. NetPhosYeast: prediction of protein phosphorylation sites in yeast

    DEFF Research Database (Denmark)

    Ingrell, C.R.; Miller, Martin Lee; Jensen, O.N.;

    2007-01-01

    We here present a neural network-based method for the prediction of protein phosphorylation sites in yeast-an important model organism for basic research. Existing protein phosphorylation site predictors are primarily based on mammalian data and show reduced sensitivity on yeast phosphorylation...... sites compared to those in humans, suggesting the need for an yeast-specific phosphorylation site predictor. NetPhosYeast achieves a correlation coefficient close to 0.75 with a sensitivity of 0.84 and specificity of 0.90 and outperforms existing predictors in the identification of phosphorylation sites...... in yeast....

  16. Targeting the Akt1 allosteric site to identify novel scaffolds through virtual screening.

    Science.gov (United States)

    Yilmaz, Oya Gursoy; Olmez, Elif Ozkirimli; Ulgen, Kutlu O

    2014-02-01

    Preclinical data and tumor specimen studies report that AKT kinases are related to many human cancers. Therefore, identification and development of small molecule inhibitors targeting AKT and its signaling pathway can be therapeutic in treatment of cancer. Numerous studies report inhibitors that target the ATP-binding pocket in the kinase domains, but the similarity of this site, within the kinase family makes selectivity a major problem. The sequence identity amongst PH domains is significantly lower than that in kinase domains and developing more selective inhibitors is possible if PH domain is targeted. This in silico screening study is the first time report toward the identification of potential allosteric inhibitors expected to bind the cavity between kinase and PH domains of Akt1. Structural information of Akt1 was used to develop structure-based pharmacophore models comprising hydrophobic, acceptor, donor and ring features. The 3D structural information of previously identified allosteric Akt inhibitors obtained from literature was employed to develop a ligand-based pharmacophore model. Database was generated with drug like subset of ZINC and screening was performed based on 3D similarity to the selected pharmacophore hypotheses. Binding modes and affinities of the ligands were predicted by Glide software. Top scoring hits were further analyzed considering 2D similarity between the compounds, interactions with Akt1, fitness to pharmacophore models, ADME, druglikeness criteria and Induced-Fit docking. Using virtual screening methodologies, derivatives of 3-methyl-xanthine, quinoline-4-carboxamide and 2-[4-(cyclohexa-1,3-dien-1-yl)-1H-pyrazol-3-yl]phenol were proposed as potential leads for allosteric inhibition of Akt1.

  17. Over-expression of NYGGF4 inhibits glucose transport in 3T3-L1 adipocytes via attenuated phosphorylation of IRS-1 and Akt

    Institute of Scientific and Technical Information of China (English)

    Chun-mei ZHANG; Xiao-hui CHEN; Bin WANG; Feng LIU; Xia CHI; Mei-ling TONG; Yu-hui NI; Rong-hua CHEN; Xi-rong GUO

    2009-01-01

    Aim: NYGGF4 is a novel gene that is abundantly expressed in the adipose tissue of obese patients. The purpose of this study was to investigate the effects of NYGGF4 on basal and insulin-stimulated glucose uptake in mature 3T3-L1 adipocytes and to understand the underlying mechanisms. Methods: 3T3-L1 preadipocytes transfected with either an empty expression vector (pcDNA3.1Myc/His B) or an NYGGF4 expression vector were differentiated into mature adipocytes. Glucose uptake was determined by measuring 2-deoxy-D-[3H]glucose uptake into the adipocytes. Immunoblotting was performed to detect the translocation of insulin-sensitive glu-cose transporter 4 (GLUT4). Immunoblotting also was used to measure the phosphorylation and total protein contents of insulin signaling proteins such as the insulin receptor (IR), insulin receptor substrate (IRS)-I, Akt, ERK1/2, p38, and JNK. Results: NYGGF4 over-expression in 3T3-L1 adipocytes reduced insulin-stimulated glucose uptake and impaired insulin-stimulated GLUT4 translocation. It also diminished insulin-stimulated tyrosine phosphorylation of IRS-1 and serine phos-phorylation of Akt without affecting the phosphorylation of IR, ERK1/2, p38, and JNK. Conclusion: NYGGF4 regulates the functions of IRS-1 and Akt, decreases GLUT4 translocation and reduces glucose uptake in response to insulin. These observations highlight the potential role of NYGGF4 in glucose homeostasis and possibly in the pathogenesis of obesity.

  18. Rho GTPase/Rho Kinase Negatively Regulates Endothelial Nitric Oxide Synthase Phosphorylation through the Inhibition of Protein Kinase B/Akt in Human Endothelial Cells

    Science.gov (United States)

    Ming, Xiu-Fen; Viswambharan, Hema; Barandier, Christine; Ruffieux, Jean; Kaibuchi, Kozo; Rusconi, Sandro; Yang, Zhihong

    2002-01-01

    Endothelial nitric oxide synthase (eNOS) is an important regulator of cardiovascular homeostasis by production of nitric oxide (NO) from vascular endothelial cells. It can be activated by protein kinase B (PKB)/Akt via phosphorylation at Ser-1177. We are interested in the role of Rho GTPase/Rho kinase (ROCK) pathway in regulation of eNOS expression and activation. Using adenovirus-mediated gene transfer in human umbilical vein endothelial cells (HUVECs), we show here that both active RhoA and ROCK not only downregulate eNOS gene expression as reported previously but also inhibit eNOS phosphorylation at Ser-1177 and cellular NO production with concomitant suppression of PKB activation. Moreover, coexpression of a constitutive active form of PKB restores the phosphorylation but not gene expression of eNOS in the presence of active RhoA. Furthermore, we show that thrombin inhibits eNOS phosphorylation, as well as expression via Rho/ROCK pathway. Expression of the active PKB reverses eNOS phosphorylation but has no effect on downregulation of eNOS expression induced by thrombin. Taken together, these data demonstrate that Rho/ROCK pathway negatively regulates eNOS phosphorylation through inhibition of PKB, whereas it downregulates eNOS expression independent of PKB. PMID:12446767

  19. PCNA-interacting peptides reduce Akt phosphorylation and TLR-mediated cytokine secretion suggesting a role of PCNA in cellular signaling.

    Science.gov (United States)

    Olaisen, Camilla; Müller, Rebekka; Nedal, Aina; Otterlei, Marit

    2015-07-01

    Proliferating cell nuclear antigen (PCNA), commonly known as a nuclear protein essential for regulation of DNA replication, DNA repair, and epigenetics, has recently been associated with multiple cytosolic functions. Many proteins containing one of the two known PCNA-interacting motifs, the AlkB homologue 2 PCNA interacting motif (APIM) and the PCNA-interacting peptide (PIP)-box, are considered to be mainly cytosolic. APIM is found in more than 20 kinases and/or associated proteins including several direct or indirect members of the mitogen-activated protein kinase (MAPK) and PI3K/Akt pathways. Mass spectrometry analysis of PCNA-pull downs verified that many cytosolic proteins involved in the MAPK and PI3K/Akt pathways are in complex with PCNA. Furthermore, treatment of cells with a PCNA-interacting APIM-containing peptide (APIM-peptide) reduced Akt phosphorylation in human peripheral blood monocytes and a human keratinocyte cell line (HaCaT). Additionally, the APIM-peptide strongly reduced the cytokine secretion from monocytes stimulated with toll like receptor (TLR) ligands and potentiated the effects of MAPK and PI3K/Akt inhibitors. Interestingly, the protein level of the APIM-containing PKR/RIG-1 activator protein (PACT) was initially strongly reduced in HaCaT cells stimulated with APIM-peptide in combination with the TLR ligand polyinosinic-polycytidylic acid (polyIC). Our results suggest that PCNA has a platform role in cytosol affecting cellular signaling.

  20. Macrophage migration inhibitory factor induces phosphorylation of Mdm2 mediated by phosphatidylinositol 3-kinase/Akt kinase: Role of this pathway in decidual cell survival.

    Science.gov (United States)

    Costa, Adriana Fraga; Gomes, Sara Zago; Lorenzon-Ojea, Aline R; Martucci, Mariane; Faria, Miriam Rubio; Pinto, Décio Dos Santos; Oliveira, Sergio F; Ietta, Francesca; Paulesu, Luana; Bevilacqua, Estela

    2016-05-01

    The phosphatidylinositol 3-kinase (PI3K)/Akt pathway has an anti-apoptotic effect through several downstream targets, which includes activation of the transformed mouse 3T3 cell double-minute 2 (Mdm2) protein, its translocation to the nucleus and degradation of the tumor suppressor p53. We show that Mif, the Macrophage Migration Inhibitory Factor, an important cytokine at the maternal fetal interface in several species, triggers phosphorylation of Mdm2 protein in a PI3K/Akt-dependent manner, thereby preventing apoptosis in cultured mouse decidual cells. Inhibition of Akt and PI3K suppresses the pathway. Mif treatment also changes the nuclear translocation of p53 and interferes with the apoptotic fate of these cells when challenged with reactive oxygen species. In conclusion, an important mechanism has been found underlying decidual cell survival through Akt signaling pathway activated by Mif, suggesting a role for this cytokine in decidual homeostasis and in the integrity of the maternal-fetal barrier that is essential for successful gestation. PMID:27208405

  1. Abelson murine leukemia virus P120: identification and characterization of tyrosine phosphorylation sites.

    OpenAIRE

    Reynolds, F H; Oroszlan, S; Stephenson, J R

    1982-01-01

    Tryptic peptides containing two major in vivo P120gag-abl tyrosine phosphorylation acceptor sites were identified, phosphorylated in vitro, and purified to homogeneity. The tyrosine site in peptide a is localized at a position six residues distal to its trypsin cleavage site, whereas the tyrosine acceptor site in peptide b is at residue seven. A third peptide, c, contains an amino-terminal phosphotyrosine residue: phosphorylation of this latter peptide only occurs to a significant extent in v...

  2. Identification of phosphorylation sites in protein kinase A substrates using artificial neural networks and mass spectrometry

    DEFF Research Database (Denmark)

    Hjerrild, M.; Stensballe, A.; Rasmussen, T.E.;

    2004-01-01

    Protein phosphorylation plays a key role in cell regulation and identification of phosphorylation sites is important for understanding their functional significance. Here, we present an artificial neural network algorithm: NetPhosK (http://www.cbs.dtu.dk/services/NetPhosK/) that predicts protein...... kinase A (PKA) phosphorylation sites. The neural network was trained with a positive set of 258 experimentally verified PKA phosphorylation sites. The predictions by NetPhosK were! validated using four novel PKA substrates: Necdin, RFX5, En-2, and Wee 1. The four proteins were phosphorylated by PKA...

  3. Identification of phosphorylation sites in protein kinase A substrates using artificial neural networks and mass spectrometry

    DEFF Research Database (Denmark)

    Hjerrild, Majbrit; Stensballe, Allan; Rasmussen, Thomas E;

    2011-01-01

    Protein phosphorylation plays a key role in cell regulation and identification of phosphorylation sites is important for understanding their functional significance. Here, we present an artificial neural network algorithm: NetPhosK (http://www.cbs.dtu.dk/services/NetPhosK/) that predicts protein...... kinase A (PKA) phosphorylation sites. The neural network was trained with a positive set of 258 experimentally verified PKA phosphorylation sites. The predictions by NetPhosK were validated using four novel PKA substrates: Necdin, RFX5, En-2, and Wee 1. The four proteins were phosphorylated by PKA...

  4. Kinase-specific prediction of protein phosphorylation sites

    DEFF Research Database (Denmark)

    Miller, Martin Lee; Blom, Nikolaj

    2009-01-01

    As extensive mass spectrometry-based mapping of the phosphoproteome progresses, computational analysis of phosphorylation-dependent signaling becomes increasingly important. The linear sequence motifs that surround phosphorylated residues have successfully been used to characterize kinase...

  5. Dual phosphorylation of Btk by Akt/protein kinase b provides docking for 14-3-3ζ, regulates shuttling, and attenuates both tonic and induced signaling in B cells.

    Science.gov (United States)

    Mohammad, Dara K; Nore, Beston F; Hussain, Alamdar; Gustafsson, Manuela O; Mohamed, Abdalla J; Smith, C I Edvard

    2013-08-01

    Bruton's tyrosine kinase (Btk) is crucial for B-lymphocyte activation and development. Mutations in the Btk gene cause X-linked agammaglobulinemia (XLA) in humans and X-linked immunodeficiency (Xid) in mice. Using tandem mass spectrometry, 14-3-3ζ was identified as a new binding partner and negative regulator of Btk in both B-cell lines and primary B lymphocytes. The activated serine/threonine kinase Akt/protein kinase B (PKB) phosphorylated Btk on two sites prior to 14-3-3ζ binding. The interaction sites were mapped to phosphoserine pS51 in the pleckstrin homology domain and phosphothreonine pT495 in the kinase domain. The double-alanine, S51A/T495A, replacement mutant failed to bind 14-3-3ζ, while phosphomimetic aspartate substitutions, S51D/T495D, caused enhanced interaction. The phosphatidylinositol 3-kinase (PI3-kinase) inhibitor LY294002 abrogated S51/T495 phosphorylation and binding. A newly characterized 14-3-3 inhibitor, BV02, reduced binding, as did the Btk inhibitor PCI-32765 (ibrutinib). Interestingly, in the presence of BV02, phosphorylation of Btk, phospholipase Cγ2, and NF-κB increased strongly, suggesting that 14-3-3 also regulates B-cell receptor (BCR)-mediated tonic signaling. Furthermore, downregulation of 14-3-3ζ elevated nuclear translocation of Btk. The loss-of-function mutant S51A/T495A showed reduced tyrosine phosphorylation and ubiquitination. Conversely, the gain-of-function mutant S51D/T495D exhibited intense tyrosine phosphorylation, associated with Btk ubiquitination and degradation, likely contributing to the termination of BCR signaling. Collectively, this suggests that Btk could become an important new candidate for the general study of 14-3-3-mediated regulation.

  6. Pinpointing Phosphorylation Sites: Quantitative Filtering and a Novel Site-specific x-Ion Fragment

    DEFF Research Database (Denmark)

    Kelstrup, Christian D; Hekmat, Omid; Francavilla, Chiara;

    2011-01-01

    assignments in large-scale phosphoproteomics data sets. To improve methods for site localization, we made use of a synthetic phosphopeptide library and SILAC-labeled peptides from whole cell lysates and analyzed these with high-resolution tandem mass spectrometry on an LTQ Orbitrap Velos. We validated gas......-phase phosphate rearrangement reactions during collision-induced dissociation (CID) and used these spectra to devise a quantitative filter that by comparing signal intensities of putative phosphorylated fragment ions with their nonphosphorylated counterparts allowed us to accurately pinpoint which fragment ions...... contain a phosphorylated residue and which ones do not. We also evaluated higher-energy collisional dissociation (HCD) and found this to be an accurate method for correct phosphorylation site localization with no gas-phase rearrangements observed above noise level. Analyzing a large set of HCD spectra...

  7. Site-specific phosphorylation dynamics of the nuclear proteome during the DNA damage response

    DEFF Research Database (Denmark)

    Bennetzen, Martin; Larsen, Dorthe Helena; Bunkenborg, Jakob;

    2010-01-01

    To investigate the temporal regulation of the DNA damage response, we applied quantitative mass spectrometry-based proteomics to measure site-specific phosphorylation changes of nuclear proteins after ionizing radiation. We profiled 5204 phosphorylation sites at five time points following DNA...... damage of which 594 sites on 209 proteins were observed to be regulated more than 2-fold. Of the 594 sites, 372 are novel phosphorylation sites primarily of nuclear origin. The 594 sites could be classified to distinct temporal profiles. Sites regulated shortly after radiation were enriched in the ataxia...... telangiectasia mutated (ATM) kinase SQ consensus sequence motif and a novel SXXQ motif. Importantly, in addition to induced phosphorylation, we identified a considerable group of sites that undergo DNA damage-induced dephosphorylation. Together, our data extend the number of known phosphorylation sites regulated...

  8. A combination of indol-3-carbinol and genistein synergistically induces apoptosis in human colon cancer HT-29 cells by inhibiting Akt phosphorylation and progression of autophagy

    Directory of Open Access Journals (Sweden)

    Watanabe Hirotsuna

    2009-11-01

    Full Text Available Abstract Background The chemopreventive effects of dietary phytochemicals on malignant tumors have been studied extensively because of a relative lack of toxicity. To achieve desirable effects, however, treatment with a single agent mostly requires high doses. Therefore, studies on effective combinations of phytochemicals at relatively low concentrations might contribute to chemopreventive strategies. Results Here we found for the first time that co-treatment with I3C and genistein, derived from cruciferous vegetables and soy, respectively, synergistically suppressed the viability of human colon cancer HT-29 cells at concentrations at which each agent alone was ineffective. The suppression of cell viability was due to the induction of a caspase-dependent apoptosis. Moreover, the combination effectively inhibited phosphorylation of Akt followed by dephosphorylation of caspase-9 or down-regulation of XIAP and survivin, which contribute to the induction of apoptosis. In addition, the co-treatment also enhanced the induction of autophagy mediated by the dephosphorylation of mTOR, one of the downstream targets of Akt, whereas the maturation of autophagosomes was inhibited. These results give rise to the possibility that co-treatment with I3C and genistein induces apoptosis through the simultaneous inhibition of Akt activity and progression of the autophagic process. This possibility was examined using inhibitors of Akt combined with inhibitors of autophagy. The combination effectively induced apoptosis, whereas the Akt inhibitor alone did not. Conclusion Although in vivo study is further required to evaluate physiological efficacies and toxicity of the combination treatment, our findings might provide a new insight into the development of novel combination therapies/chemoprevention against malignant tumors using dietary phytochemicals.

  9. Hydrogen peroxide inhibits transforming growth factor-β1-induced cell cycle arrest by promoting Smad3 linker phosphorylation through activation of Akt-ERK1/2-linked signaling pathway

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Jiyeon; Park, Seong Ji; Jo, Eun Ji [Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 200-701 (Korea, Republic of); Lee, Hui-Young [Department of Internal Medicine, Kangwon National University, Chuncheon 200-701 (Korea, Republic of); Hong, Suntaek [Laboratory of Cancer Cell Biology, Lee Gil Ya Cancer and Diabetes Institute, Gachon University, Incheon 406-840 (Korea, Republic of); Kim, Seong-Jin [CHA Cancer Institute, CHA University of Medicine and Science, Seoul 135-081 (Korea, Republic of); Kim, Byung-Chul, E-mail: bckim@kangwon.ac.kr [Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon 200-701 (Korea, Republic of)

    2013-06-14

    Highlights: •H{sub 2}O{sub 2} inhibits TGF-β1-induced cell cycle arrest. •H{sub 2}O{sub 2} induces Smad3 linker phosphorylation through Akt-ERK1/2 pathway. •H{sub 2}O{sub 2}-mediated suppression of TGF-β signal requires Smad3 linker phosphorylation. •This is a first report about interplay between H{sub 2}O{sub 2} and growth inhibition pathway. -- Abstract: Hydrogen peroxide (H{sub 2}O{sub 2}) functions as a second messenger in growth factor receptor-mediated intracellular signaling cascade and is tumorigenic by virtue of its ability to promote cell proliferation; however, the mechanisms underlying the growth stimulatory action of H{sub 2}O{sub 2} are less understood. Here we report an important mechanism for antagonistic effects of H{sub 2}O{sub 2} on growth inhibitory response to transforming growth factor-β1 (TGF-β1). In Mv1Lu and HepG2 cells, pretreatment of H{sub 2}O{sub 2} (0.05–0.2 mM) completely blocked TGF-β1-mediated induction of p15{sup INK4B} expression and increase of its promoter activity. Interestingly, H{sub 2}O{sub 2} selectively suppressed the transcriptional activation potential of Smad3, not Smad2, in the absence of effects on TGF-β1-induced phosphorylation of the COOH-tail SSXS motif of Smad3 and its nuclear translocation. Mechanism studies showed that H{sub 2}O{sub 2} increases the phosphorylation of Smad3 at the middle linker region in a concentration- and time-dependent manner and this effect is mediated by activation of extracellular signal-activated kinase 1/2 through Akt. Furthermore, expression of a mutant Smad3 in which linker phosphorylation sites were ablated significantly abrogated the inhibitory effects of H{sub 2}O{sub 2} on TGF-β1-induced increase of p15{sup INK4B}-Luc reporter activity and blockade of cell cycle progression from G1 to S phase. These findings for the first time define H{sub 2}O{sub 2} as a signaling molecule that modulate Smad3 linker phosphorylation and its transcriptional activity, thus providing

  10. PIP3 but not PIP2 increases GLUT4 surface expression and glucose metabolism mediated by AKT/PKCζ/λ phosphorylation in 3T3L1 adipocytes

    OpenAIRE

    Manna, Prasenjit; Jain, Sushil K.

    2013-01-01

    PIP3 (phosphatidylinositol-3,4,5-triphosphate) and PIP2 (phosphatidylinositol-4,5-biphosphate) are two well-known membrane bound polyphosphoinositides. Diabetes is associated with impaired glucose metabolism. Using a 3T3L1 adipocyte cell model, this study investigated the roles of PIP3 and PIP2 on insulin stimulated glucose metabolism in high glucose (HG) treated cells. Exogenous PIP3 supplementation (1, 5, or 10 nM) increased the phosphorylation of AKT and PKCζ/λ, which in turn upregulated G...

  11. Large-scale analysis of phosphorylation site occupancy in eukaryotic proteins

    DEFF Research Database (Denmark)

    Rao, R Shyama Prasad; Møller, Ian Max

    2012-01-01

    in proteins is currently lacking. We have therefore analyzed the occurrence and occupancy of phosphorylated sites (~ 100,281) in a large set of eukaryotic proteins (~ 22,995). Phosphorylation probability was found to be much higher in both the  termini of protein sequences and this is much pronounced...... maximum randomness. An analysis of phosphorylation motifs indicated that just 40 motifs and a much lower number of associated kinases might account for nearly 50% of the known phosphorylations in eukaryotic proteins. Our results provide a broad picture of the phosphorylation sites in eukaryotic proteins....

  12. Haloperidol disrupts Akt signalling to reveal a phosphorylation-dependent regulation of pro-apoptotic Bcl-XS function.

    Science.gov (United States)

    Wei, Zelan; Qi, Ji; Dai, Yunxiu; Bowen, Wayne D; Mousseau, Darrell D

    2009-01-01

    The antipsychotic drug haloperidol is still used to treat psychosis and "agitation", often with devastating consequences, particularly in geriatric and pre-demented patients. Cytotoxicity induced by haloperidol has been associated with induction of Bcl-XS, a pro-apoptotic member of the Bcl-2 family, as well as with modulation of the Akt pro-survival pathway. Using preneuronal PC12 and primary neuronal cultures, we show that haloperidol inactivates Akt. This induces the dephosphorylation of serine residues in Bcl-XS and promotes its association with the mitochondrial voltage-dependent anion channel (VDAC), as well as with cytochrome c- and caspase-3-dependent events. These events are sensitive to expression of constitutively active Akt. Mutation of Serine106 (Ser106), which is flanked by a putative Akt motif, hinders the association of the Bcl-XS protein with Akt, but promotes its association with VDAC. The dephosphorylation mimic, Bcl-XS(Ser106Ala), induces caspase-dependent PC12 and neuronal cell apoptosis. In contrast, Bcl-XS(Ser106Ala) induces a significant loss of VDAC expression, and cytochrome c- and caspase-independent toxicity in the non-neuronal HEK293A cells. We link haloperidol and Akt to Bcl-XS-sensitive toxicity via cell line-dependent mitochondrial events centering on VDAC. This clearly mitigates the chronic use of haloperidol in neuropsychiatric populations, but supports its use as a potential acute therapeutic in cancer, where apoptosis is desirable.

  13. Impaired insulin-stimulated phosphorylation of Akt and AS160 in skeletal muscle of women with polycystic ovary syndrome is reversed by pioglitazone treatment

    DEFF Research Database (Denmark)

    Højlund, Kurt; Glintborg, Dorte; Andersen, Nicoline Resen;

    2008-01-01

    OBJECTIVE: Insulin resistance in skeletal muscle is a major risk factor for type 2 diabetes in women with polycystic ovary syndrome (PCOS). However, the molecular mechanisms underlying skeletal muscle insulin resistance and the insulin-sensitizing effect of thiazolidinediones in PCOS in vivo...... are less well characterized. RESEARCH DESIGN AND METHODS: We determined molecular mediators of insulin signaling to glucose transport in skeletal muscle biopsies of 24 PCOS patients and 14 matched control subjects metabolically characterized by euglycemic-hyperinsulinemic clamps and indirect calorimetry......, and we examined the effect of 16 weeks of treatment with pioglitazone in PCOS patients. RESULTS: Impaired insulin-mediated total (R(d)) oxidative and nonoxidative glucose disposal (NOGD) was paralleled by reduced insulin-stimulated Akt phosphorylation at Ser473 and Thr308 and AS160 phosphorylation...

  14. Absence of the GPR37/PAEL receptor impairs striatal Akt and ERK2 phosphorylation, DeltaFosB expression, and conditioned place preference to amphetamine and cocaine.

    Science.gov (United States)

    Marazziti, Daniela; Di Pietro, Chiara; Mandillo, Silvia; Golini, Elisabetta; Matteoni, Rafaele; Tocchini-Valentini, Glauco P

    2011-06-01

    The orphan G-protein-coupled receptor 37 (GPR37) colocalizes with the dopamine (DA) transporter (DAT) in mouse nigrostriatal presynaptic membranes, and its genetic ablation in homozygous null-mutant (GPR37-KO) mice provokes the marked increase of plasma membrane expression of DAT, alteration of psychostimulant-induced locomotor activity, and reduction of catalepsy induced by DA-receptor antagonists. We report that extracts from GPR37-KO mice displayed biochemical alterations of the nigrostriatal signaling pathways mediated by D1 and D2 dopaminergic receptors. Null-mutant mice showed an increase of the basal phosphorylation level of the D2-regulated Akt kinase. The basal phosphorylation of the D1-activated ERK2 kinase was not altered, but acute treatments with amphetamine or cocaine failed to produce its specific increase, as detected in samples from wild-type littermates. Furthermore, the chronic administration of cocaine to GPR37-KO mice did not increase the expression of the ΔFosB transcription factor isoforms. Consistently, behavioral analysis showed that null-mutant animals did not respond to the incentive properties of amphetamine or cocaine, in conditioned place preference tests. Thus, the lack of GPR37 affects both ERK2- and Akt-mediated striatal signaling pathways, impairing the biochemical and behavioral responses typically induced by acute and chronic administration of psychostimulant drugs. PMID:21372109

  15. Suppressing Akt phosphorylation and activating Fas by safrole oxide inhibited angiogenesis and induced vascular endothelial cell apoptosis in the presence of fibroblast growth factor-2 and serum.

    Science.gov (United States)

    Zhao, Jing; Miao, Junying; Zhao, Baoxiang; Zhang, Shangli; Yin, Deling

    2006-01-01

    At present, vascular endothelial cell (VEC) apoptosis induced by deprivation of fibroblast growth factor-2 (FGF-2) and serum has been well studied. But how to trigger VEC apoptosis in the presence of FGF-2 and serum is not well known. To address this question, in this study, the effects of safrole oxide on angiogenesis and VEC growth stimulated by FGF-2 were investigated. The results showed that safrole oxide inhibited angiogenesis and induced VEC apoptosis in the presence of FGF-2 and serum. To understand the possible mechanism of safrole oxide acting, we first examined the phosphorylation of Akt and the activity of nitric oxide synthase (NOS); secondly, we analyzed the expressions and distributions of Fas and P53; then we measured the activity of phosphatidylcholine specific phospholipase C (PC-PLC) in the VECs treated with and without safrole oxide. The results showed that this small molecule obviously suppressed Akt phosphorylation and the activity of NOS, and promoted the expressions of Fas and P53 markedly. Simultaneously, Fas protein clumped on cell membrane, instead of homogenously distributed. The activity of PC-PLC was not changed obviously. The data suggested that safrole oxide effectively inhibited angiogenesis and triggered VEC apoptosis in the presence of FGF-2 and serum, and it might perform its functions by suppressing Akt/NOS signal pathway, upregulating the expressions of Fas and P53 and modifying the distributing pattern of Fas in VEC. This finding provided a powerful chemical probe for promoting VEC apoptosis during angiogenesis stimulated by FGF-2.

  16. mTORC2-PKBα/Akt1 Serine 473 phosphorylation axis is essential for regulation of FOXP3 Stability by chemokine CCL3 in psoriasis.

    Science.gov (United States)

    Chen, Ling; Wu, Jinjin; Pier, Eric; Zhao, Yun; Shen, Zhu

    2013-02-01

    The connection between infections and acute guttate psoriasis (AGP) outbreaks/chronic plaque psoriasis (CPP) exacerbation has been known for years. Impaired function of FOXP3+Tregs in psoriasis has been identified. However, the mechanisms behind these two observations have not been fully interpreted. In the present study, we provide evidence to support chemokine CCL3 as one of the vital links between infections and FOXP3 stability in the psoriatic microenvironment. We found that serum CCL3, strongly induced by microorganism infections including streptococcus, was closely correlated with FOXP3 levels in CD4+CD25+T cells of patients with psoriasis. CCL3 manipulated FOXP3 stability in a concentration-dependent bidirectional manner. High-concentration CCL3 decreased FOXP3 stability by promoting FOXP3's degradation through K48-linkage ubiquitination. This degradation was mainly dependent on upregulation of Serine 473 phosphorylation of the PKBα/Akt1 isoform, and almost independent of mTORC1 (mammalian target of rapamycin complex 1) activity. On the other hand, low-concentration CCL3 could enhance FOXP3 stability by the maintenance of the PKC pathway and the restriction of the PKB/Akt pathway. We further demonstrated that enhancing FOXP3 stability by low-concentration CCL3 attributed, at least partly, to the prevention of cytoplasmic Sin1, a vital component of mTORC2, nuclear translocation. Our results suggest vital roles for CCL3-mTORC2-isoform PKB/Akt1 S473 phosphorylation axis in FOXP3+Tregs and the development of psoriasis.

  17. Phosphoproteomics Identified an NS5A Phosphorylation Site Involved in Hepatitis C Virus Replication.

    Science.gov (United States)

    Chong, Weng Man; Hsu, Shih-Chin; Kao, Wei-Ting; Lo, Chieh-Wen; Lee, Kuan-Ying; Shao, Jheng-Syuan; Chen, Yi-Hung; Chang, Justin; Chen, Steve S-L; Yu, Ming-Jiun

    2016-02-19

    The non-structural protein 5A (NS5A) is a hepatitis C virus (HCV) protein indispensable for the viral life cycle. Many prior papers have pinpointed several serine residues in the low complexity sequence I region of NS5A responsible for NS5A phosphorylation; however, the functions of specific phosphorylation sites remained obscure. Using phosphoproteomics, we identified three phosphorylation sites (serines 222, 235, and 238) in the NS5A low complexity sequence I region. Reporter virus and replicon assays using phosphorylation-ablated alanine mutants of these sites showed that Ser-235 dominated over Ser-222 and Ser-238 in HCV replication. Immunoblotting using an Ser-235 phosphorylation-specific antibody showed a time-dependent increase in Ser-235 phosphorylation that correlated with the viral replication activity. Ser-235 phosphorylated NS5A co-localized with double-stranded RNA, consistent with its role in HCV replication. Mechanistically, Ser-235 phosphorylation probably promotes the replication complex formation via increasing NS5A interaction with the human homologue of the 33-kDa vesicle-associated membrane protein-associated protein. Casein kinase Iα (CKIα) directly phosphorylated Ser-235 in vitro. Inhibition of CKIα reduced Ser-235 phosphorylation and the HCV RNA levels in the infected cells. We concluded that NS5A Ser-235 phosphorylated by CKIα probably promotes HCV replication via increasing NS5A interaction with the 33-kDa vesicle-associated membrane protein-associated protein. PMID:26702051

  18. Shikonin Inhibits the Migration and Invasion of Human Glioblastoma Cells by Targeting Phosphorylated β-Catenin and Phosphorylated PI3K/Akt: A Potential Mechanism for the Anti-Glioma Efficacy of a Traditional Chinese Herbal Medicine

    Directory of Open Access Journals (Sweden)

    Feng-Ying Zhang

    2015-10-01

    Full Text Available Shikonin is an anthraquinone derivative extracted from the root of lithospermum. Shikonin is traditionally used in the treatment of inflammatory and infectious diseases such as hepatitis. Shikonin also inhibits proliferation and induces apoptosis in various tumors. However, the effect of shikonin on gliomas has not been fully elucidated. In the present study, we aimed to investigate the effects of shikonin on the migration and invasion of human glioblastoma cells as well as the underlying mechanisms. U87 and U251 human glioblastoma cells were treated with shikonin at 2.5, 5, and 7.5 μmol/L and cell viability, migration and invasiveness were assessed with CCK8, scratch wound healing, in vitro Transwell migration, and invasion assays. The expression and activity of matrix metalloproteinase-2 (MMP-2 and matrix metalloproteinase-9 (MMP-9 and the expression of phosphorylated β-catenin (p-β-catenin and phosphorylated PI3K/Akt were also checked. Results showed that shikonin significantly inhibited the cell proliferation, migration, invasion, and expression of MMP-2 and MMP-9 in U87 and U251 cells. The expression of p-β-catenin showed contrary trends in two cell lines. It was significantly inhibited in U87 cells and promoted in U251 cells. Results in this work indicated that shikonin displayed an inhibitory effect on the migration and invasion of glioma cells by inhibiting the expression and activity of MMP-2 and -9. In addition, shikonin also inhibited the expression of p-PI3K and p-Akt to attenuate cell migration and invasion and MMP-2 and MMP-9 expression in both cell lines, which could be reversed by the PI3K/Akt pathway agonist, insulin-like growth factor-1 (IGF-1.

  19. Shikonin Inhibits the Migration and Invasion of Human Glioblastoma Cells by Targeting Phosphorylated β-Catenin and Phosphorylated PI3K/Akt: A Potential Mechanism for the Anti-Glioma Efficacy of a Traditional Chinese Herbal Medicine.

    Science.gov (United States)

    Zhang, Feng-Ying; Hu, Yi; Que, Zhong-You; Wang, Ping; Liu, Yun-Hui; Wang, Zhen-Hua; Xue, Yi-Xue

    2015-10-09

    Shikonin is an anthraquinone derivative extracted from the root of lithospermum. Shikonin is traditionally used in the treatment of inflammatory and infectious diseases such as hepatitis. Shikonin also inhibits proliferation and induces apoptosis in various tumors. However, the effect of shikonin on gliomas has not been fully elucidated. In the present study, we aimed to investigate the effects of shikonin on the migration and invasion of human glioblastoma cells as well as the underlying mechanisms. U87 and U251 human glioblastoma cells were treated with shikonin at 2.5, 5, and 7.5 μmol/L and cell viability, migration and invasiveness were assessed with CCK8, scratch wound healing, in vitro Transwell migration, and invasion assays. The expression and activity of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) and the expression of phosphorylated β-catenin (p-β-catenin) and phosphorylated PI3K/Akt were also checked. Results showed that shikonin significantly inhibited the cell proliferation, migration, invasion, and expression of MMP-2 and MMP-9 in U87 and U251 cells. The expression of p-β-catenin showed contrary trends in two cell lines. It was significantly inhibited in U87 cells and promoted in U251 cells. Results in this work indicated that shikonin displayed an inhibitory effect on the migration and invasion of glioma cells by inhibiting the expression and activity of MMP-2 and -9. In addition, shikonin also inhibited the expression of p-PI3K and p-Akt to attenuate cell migration and invasion and MMP-2 and MMP-9 expression in both cell lines, which could be reversed by the PI3K/Akt pathway agonist, insulin-like growth factor-1 (IGF-1).

  20. Rapid Identification of Protein Kinase Phosphorylation Site Motifs Using Combinatorial Peptide Libraries.

    Science.gov (United States)

    Miller, Chad J; Turk, Benjamin E

    2016-01-01

    Eukaryotic protein kinases phosphorylate substrates at serine, threonine, and tyrosine residues that fall within the context of short sequence motifs. Knowing the phosphorylation site motif for a protein kinase facilitates designing substrates for kinase assays and mapping phosphorylation sites in protein substrates. Here, we describe an arrayed peptide library protocol for rapidly determining kinase phosphorylation consensus sequences. This method uses a set of peptide mixtures in which each of the 20 amino acid residues is systematically substituted at nine positions surrounding a central site of phosphorylation. Peptide mixtures are arrayed in multiwell plates and analyzed by radiolabel assay with the kinase of interest. The preferred sequence is determined from the relative rate of phosphorylation of each peptide in the array. Consensus peptides based on these sequences typically serve as efficient and specific kinase substrates for high-throughput screening or incorporation into biosensors.

  1. Human ATP synthase beta is phosphorylated at multiple sites and shows abnormal phosphorylation at specific sites in insulin-resistant muscle

    DEFF Research Database (Denmark)

    Højlund, K; Yi, Z; Lefort, N;

    2009-01-01

    AIMS/HYPOTHESIS: Insulin resistance in skeletal muscle is linked to mitochondrial dysfunction in obesity and type 2 diabetes. Emerging evidence indicates that reversible phosphorylation regulates oxidative phosphorylation (OxPhos) proteins. The aim of this study was to identify and quantify site......-specific phosphorylation of the catalytic beta subunit of ATP synthase (ATPsyn-beta) and determine protein abundance of ATPsyn-beta and other OxPhos components in skeletal muscle from healthy and insulin-resistant individuals. METHODS: Skeletal muscle biopsies were obtained from lean, healthy, obese, non-diabetic and type...... 2 diabetic volunteers (each group n = 10) for immunoblotting of proteins, and hypothesis-driven identification and quantification of phosphorylation sites on ATPsyn-beta using targeted nanospray tandem mass spectrometry. Volunteers were metabolically characterised by euglycaemic...

  2. Hydrogen peroxide inhibits transforming growth factor-β1-induced cell cycle arrest by promoting Smad3 linker phosphorylation through activation of Akt-ERK1/2-linked signaling pathway.

    Science.gov (United States)

    Choi, Jiyeon; Park, Seong Ji; Jo, Eun Ji; Lee, Hui-Young; Hong, Suntaek; Kim, Seong-Jin; Kim, Byung-Chul

    2013-06-14

    Hydrogen peroxide (H2O2) functions as a second messenger in growth factor receptor-mediated intracellular signaling cascade and is tumorigenic by virtue of its ability to promote cell proliferation; however, the mechanisms underlying the growth stimulatory action of H2O2 are less understood. Here we report an important mechanism for antagonistic effects of H2O2 on growth inhibitory response to transforming growth factor-β1 (TGF-β1). In Mv1Lu and HepG2 cells, pretreatment of H2O2 (0.05-0.2 mM) completely blocked TGF-β1-mediated induction of p15(INK4B) expression and increase of its promoter activity. Interestingly, H2O2 selectively suppressed the transcriptional activation potential of Smad3, not Smad2, in the absence of effects on TGF-β1-induced phosphorylation of the COOH-tail SSXS motif of Smad3 and its nuclear translocation. Mechanism studies showed that H2O2 increases the phosphorylation of Smad3 at the middle linker region in a concentration- and time-dependent manner and this effect is mediated by activation of extracellular signal-activated kinase 1/2 through Akt. Furthermore, expression of a mutant Smad3 in which linker phosphorylation sites were ablated significantly abrogated the inhibitory effects of H2O2 on TGF-β1-induced increase of p15(INK4B)-Luc reporter activity and blockade of cell cycle progression from G1 to S phase. These findings for the first time define H2O2 as a signaling molecule that modulate Smad3 linker phosphorylation and its transcriptional activity, thus providing a potential mechanism whereby H2O2 antagonizes the cytostatic function of TGF-β1.

  3. Prediction of PK-specific phosphorylation site based on information entropy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Phosphorylation is a crucial way to control the activity of proteins in many eukaryotic organisms in vivo. Experimental methods to determine phosphorylation sites in substrates are usually restricted by the in vitro condition of enzymes and very intensive in time and labor. Although some in silico methods and web servers have been introduced for automatic detection of phosphorylation sites, sophisticated methods are still in urgent demand to further improve prediction performances. Protein primary se-quences can help predict phosphorylation sites catalyzed by different protein kinase and most com-putational approaches use a short local peptide to make prediction. However, the useful information may be lost if only the conservative residues that are not close to the phosphorylation site are consid-ered in prediction, which would hamper the prediction results. A novel prediction method named IEPP (Information-Entropy based Phosphorylation Prediction) is presented in this paper for automatic de-tection of potential phosphorylation sites. In prediction, the sites around the phosphorylation sites are selected or excluded by their entropy values. The algorithm was compared with other methods such as GSP and PPSP on the ABL, MAPK and PKA PK families. The superior prediction accuracies were ob-tained in various measurements such as sensitivity (Sn) and specificity (Sp). Furthermore, compared with some online prediction web servers on the new discovered phosphorylation sites, IEPP also yielded the best performance. IEPP is another useful computational resource for identification of PK-specific phosphorylation sites and it also has the advantages of simpleness, efficiency and con-venience.

  4. NetPhosBac - A predictor for Ser/Thr phosphorylation sites in bacterial proteins

    DEFF Research Database (Denmark)

    Miller, Martin Lee; Soufi, Boumediene; Jers, Carsten;

    2009-01-01

    sites in two bacterial model organisms Bacillus subtilis and Escherichia coli. Interestingly, the analysis of these phosphorylation sites revealed that most of them are not characteristic for eukaryotic-type protein kinases, which explains the poor performance of eukaryotic data-trained phosphorylation....... Moreover, NetPhosBac predictions of phosphorylation sites in E. coli proteins were experimentally verified on protein and site-specific levels. In conclusion, NetPhosBac clearly illustrates the advantage of taxa-specific predictors and we hope it will provide a useful asset to the microbiological community....

  5. Differential roles of PDK1- and PDK2-phosphorylation sites in the yeast AGC kinases Ypk1, Pkc1 and Sch9.

    Science.gov (United States)

    Roelants, Françoise M; Torrance, Pamela D; Thorner, Jeremy

    2004-10-01

    Saccharomyces cerevisiae Pkh1 and Pkh2 (orthologues of mammalian protein kinase, PDK1) are functionally redundant. These kinases activate three AGC family kinases involved in the maintenance of cell wall integrity: Ypk1 and Ypk2, two closely related, functionally redundant enzymes (orthologues of mammalian protein kinase SGK), and Pkc1 (orthologue of mammalian protein kinase PRK2). Pkh1 and Pkh2 activate Ypk1, Ypk2 and Pkc1 by phosphorylating a Thr in a conserved sequence motif (PDK1 site) within the activation loop of these proteins. A fourth protein kinase involved in growth control and stress response, Sch9 (orthologue of mammalian protein kinase c-Akt/PKB), also carries the conserved activation loop motif. Like other AGC family kinases, Ypk1, Ypk2, Pkc1 and Sch9 also carry a second conserved sequence motif situated in a region C-terminal to the catalytic domain, called the hydrophobic motif (PDK2 site). Currently, there is still controversy surrounding the identity of the enzyme responsible for phosphorylating this second site and the necessity for phosphorylation at this site for in vivo function. Here, genetic and biochemical methods have been used to investigate the physiological consequences of phosphorylation at the PDK1 and PDK2 sites of Ypk1, Pkc1 and Sch9. It was found that phosphorylation at the PDK1 site in the activation loop is indispensable for the essential functions of all three kinases in vivo, whereas phosphorylation at the PDK2 motif plays a non-essential and much more subtle role in modulating the ability of these kinases to regulate the downstream processes in which they participate. PMID:15470109

  6. Reversal of Multidrug Resistance and Inhibition of Phosphorylation of AKT in Human Ovarian Cancer Cell Line by Wild-type PTEN Gene

    Institute of Scientific and Technical Information of China (English)

    WU Huijuan; WENG Danhui; XING Hui; LU Yunping; MA Ding

    2007-01-01

    The reversing effect of wild-type PTEN gene on resistance of CI3K cells to cisplatin and its inhibitory effect on the phosphorylation of protein kinase B (AKT) were studied. The expression of PTEN mRNA and protein in OV2008 cells and C13K cells were semi-quantitatively detected by using RT-PCR and Western blotting. Recombinant eukaryotic expression plasmid containing human wild-type PTEN gene was transfected into C13K cells by lipofectamine2000. The expression of PTEN mRNA was monitored by RT-PCR and the expression of PTEN, Akt, p-Akt protein were ana- lyzed by Western blotting in PTEN-transfected and non-transfected CI3K cells. Proliferation and chemosensitivity of cells to DDP were measured by MTT, and cell apoptosis was detected by flow cytometry after treatment with cisplatin. The expression of PTEN mRNA and protein in OV2008 cells were significantly higher than those in C13K cells. After transfection with PTEN gene for 48 h, the expression of PTEN mRNA and protein in C13K cells were 2.04±0.10, 0.94±0.04 respectively and the expression of p-Akt protein (0.94±0.07) was lower than those in control groups (1.68±0.14, 1.66±0.10) (P<0.05). The IC50 of DDP to C13K cells transfected with PTEN (7.2±0.3 μmol/L) was obviously lower than those of empty-vector transfected cells and non-transfected cells (12.7±0.4 μmol/l, 13.0±0.3 μmol/L) (P<0.05). The apopototis ratio of wild-type PTEN-transfected, empty vector transfected and non-transfected C13K cells were (41.65±0.87)%, (18.61±0.70)% and (15.28 ±0.80)% respectively, and the difference was statistically significant (P<0.05). PTEN gene plays an important role in ovarian cancer multidrug resistance. Transfection of PTEN could increase the ex- pression of PTEN and restore drug sensitivity to cisplatin in human ovarian cancer cell line C13K with multidrug-resistance by decreasing the expression of p-Akt.

  7. Two putative protein kinase CK2 phosphorylation sites are important for Myf-5 activity

    DEFF Research Database (Denmark)

    Winter, B; Kautzner, I; Issinger, O G;

    1997-01-01

    Myf-5, a member of a family of muscle-specific transcription factors, is important for myogenic cell determination and differentiation. Here, we report that Myf-5 protein constitutes a substrate for phosphorylation in vitro by protein kinase CK2. We identified two potential phosphorylation sites...... localization and/or protein stability. Our data suggest that CK2-mediated phosphorylation of Myf-5 is required for Myf-5 activity....

  8. Phospho.ELM: A database of experimentally verified phosphorylation sites in eukaryotic proteins

    DEFF Research Database (Denmark)

    Diella, F.; Cameron, S.; Gemund, C.;

    2004-01-01

    need for an accurate database dedicated to phosphorylation to provide easily retrievable information on phosphoproteins. Description: Phospho. ELM http://phospho.elm.eu.org is a new resource containing experimentally verified phosphorylation sites manually curated from the literature and is developed...... as part of the ELM ( Eukaryotic Linear Motif) resource. Phospho. ELM constitutes the largest searchable collection of phosphorylation sites available to the research community. The Phospho. ELM entries store information about substrate proteins with the exact positions of residues known...... to be phosphorylated by cellular kinases. Additional annotation includes literature references, subcellular compartment, tissue distribution, and information about the signaling pathways involved as well as links to the molecular interaction database MINT. Phospho. ELM version 2.0 contains 1703 phosphorylation site...

  9. High-accuracy identification and bioinformatic analysis of in vivo protein phosphorylation sites in yeast

    DEFF Research Database (Denmark)

    Gnad, Florian; de Godoy, Lyris M F; Cox, Jürgen;

    2009-01-01

    Protein phosphorylation is a fundamental regulatory mechanism that affects many cell signaling processes. Using high-accuracy MS and stable isotope labeling in cell culture-labeling, we provide a global view of the Saccharomyces cerevisiae phosphoproteome, containing 3620 phosphorylation sites ma...

  10. FV-429 induces apoptosis and inhibits glycolysis by inhibiting Akt-mediated phosphorylation of hexokinase II in MDA-MB-231 cells.

    Science.gov (United States)

    Zhou, Yuxin; Lu, Na; Qiao, Chen; Ni, Ting; Li, Zhiyu; Yu, Boyang; Guo, Qinglong; Wei, Libin

    2016-09-01

    In this study, the anticancer effect of a newly synthesized flavonoid FV-429, against human breast cancer MDA-MB-231 cells, and the underlying mechanisms were investigated. FV-429 triggered the apoptosis and simultaneously inhibited the glycolysis of MDA-MB-231 cells. Both the HK II activity and its level in mitochondria were significantly down regulated by FV-429. Moreover, FV-429 weakened the interaction between HKII and VDAC, stimulated the detachment of HK II from the mitochondria, and resulted in the opening of the mitochondrial permeability transition pores. Thus FV-429 induced the mitochondrial-mediated apoptosis, showing increased Bax/Bcl-2 ratio, loss of mitochondrial membrane potential (MMP) and activation of caspase-3 and -9, cytochrome c (Cyt c) release, and apoptosis inducing factor (AIF) transposition. Further research revealed that the phosphorylation of mitochondrial HKII via Akt was responsible for the dissociation of HKII and the decreased HKII activity induced by FV-429. Taken together, FV-429 inhibited the phosphorylation of HKII, down-regulated its activity, and stimulated the release of HKII from the mitochondria, resulting the inhibited glycolysis and mitochondrial-mediated apoptosis. The studies provide a molecular basis for the development of flavonoid compounds as novel anticancer agents for breast cancer. © 2015 Wiley Periodicals, Inc. PMID:26258875

  11. Augmenter of liver regeneration causes different kinetics of ERK1/2 and Akt/PKB phosphorylation than EGF and induces hepatocyte proliferation in an EGF receptor independent and liver specific manner

    Energy Technology Data Exchange (ETDEWEB)

    Ilowski, Maren; Putz, Christine [Department of Surgery, Ludwig-Maximilians-University of Munich Hospital Grosshadern, Munich (Germany); Weiss, Thomas S. [Department of Surgery, University of Regensburg Hospital, Regensburg (Germany); Brand, Stephan [Department of Internal Medicine II, Ludwig-Maximilians-University of Munich Hospital Grosshadern, Munich (Germany); Jauch, Karl-Walter [Department of Surgery, Ludwig-Maximilians-University of Munich Hospital Grosshadern, Munich (Germany); Hengstler, Jan G. [Leibniz Research Centre for Working Environment and Human Factors, TU Dortmund University, Dortmund (Germany); Thasler, Wolfgang Erwin, E-mail: wolfgang.thasler@med.uni-muenchen.de [Department of Surgery, Ludwig-Maximilians-University of Munich Hospital Grosshadern, Munich (Germany)

    2010-04-16

    Background/Aim: Augmenter of liver regeneration (ALR) is a potent growth factor which supports liver regeneration in experimental animals. The aim of this study was to compare proliferation as well as the kinetics of ERK1/2 and Akt/PKB phosphorylation by recombinant human ALR (rhALR) and EGF in human hepatocytes and extrahepatic cells. Methods: Kinetics of ERK1/2 and Akt/PKB phosphorylation were determined in primary human hepatocytes (phh) after stimulation with rhALR and EGF. Induction of proliferation was analyzed in phh and several cell lines of hepatic and extrahepatic origin by the MTT and [{sup 3}H]-thymidine assay. Results: The kinetics of ERK phosphorylation showed clear differences, whereby rhALR caused a transient and EGF a permanent increase during the observation period of 60 min. For both, Akt and ERK phosphorylation, EGF caused a faster effect with maximal levels observed already after 2 min, whereas rhALR caused maximal phosphorylation between 10 and 15 min. Using the EGF receptor inhibitor AG1478 we provide evidence of an EGF receptor independent induction of proliferation by rhALR. Furthermore, rhALR induced proliferation only in phh and the human liver derived cell lines HepG2 and Chang. In contrast, EGF enhanced proliferation in all analyzed cell types including cell lines of colon, bronchial, pancreatic and gastric origin (SW480, BC1, L36PL and GC1). Conclusion: rhALR and EGF induce different kinetics of ERK and Akt phosphorylation in human hepatocytes. The mitogenic effect of rhALR is liver specific and seems to be at least partially independent from EGF receptor mediated signaling.

  12. IN VITRO ANALYSIS OF τ PHOSPHORYLATION SITES AND ITS BIOLOGICAL ACTIVITY

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Objective.To explore the association between the abnormal phosphorylation sites found in Alzheimer disease (AD) τ and the inhibition of its biological activity. Methods.Ultracentrifugation,chromatography,manual Edman degradation and autosequence techniques were used to prepare and phosphorylate human recombinant τ ,isolate and purify 32P τ peptides and determine phosphorylation sites. Results.Phosphorylation of τ by casein kinase 1 (CK 1),cyclic AMP dependent protein kinase (PKA) and glycogen synthetase kinase 3 (GSK 3) separately inhibited its biological activity and the inhibition of this activity by GSK 3 was significantly increased if τ was prephosphorylated by CK 1 or PKA.The most potent inhibition was seen by a combined phosphorylation of τ with PKA and GSK 3.The treatment of τ by PKA and GSK 3 combination induced phosphorylation of τ at Ser 195,Ser 198,Ser 199,Ser 202,Thr 205,Thr 231,Ser 235,Ser 262,Ser 356,Ser 404,whereas Thr 181,Ser 184,Ser 262,Ser 356 and Ser 400 were phosphorylated by GSK 3 alone under the same condition. Conclusion.Phosphorylation of τ by PKA plus GSK 3 at Thr 205 might play a key role in τ pathology in AD.

  13. Phosphorylation site dynamics of early T-cell receptor signaling

    DEFF Research Database (Denmark)

    Chylek, Lily A; Akimov, Vyacheslav; Dengjel, Jörn;

    2014-01-01

    In adaptive immune responses, T-cell receptor (TCR) signaling impacts multiple cellular processes and results in T-cell differentiation, proliferation, and cytokine production. Although individual protein-protein interactions and phosphorylation events have been studied extensively, we lack...... with central roles in TCR signaling. The model was used to generate predictions suggesting unexpected roles for the phosphatase PTPN6 (SHP-1) and shortcut recruitment of the actin regulator WAS. Predictions were validated experimentally. This integration of proteomics and modeling illustrates a novel...

  14. Distinct and site-specific phosphorylation of the retinoblastoma protein at serine 612 in differentiated cells.

    Directory of Open Access Journals (Sweden)

    Takayuki Hattori

    Full Text Available The retinoblastoma susceptibility protein (pRB is a phosphoprotein that regulates cell cycle progression at the G1/S transition. In quiescent and early G1 cells, pRB predominantly exists in the active hypophosphorylated form. The cyclin/cyclin-dependent protein kinase complexes phosphorylate pRB at the late G1 phase to inactivate pRB. This event leads to the dissociation and activation of E2F family transcriptional factors. At least 12 serine/threonine residues in pRB are phosphorylated in vivo. Although there have been many reports describing bulk phosphorylation of pRB, detail research describing the function of each phosphorylation site remains unknown. Besides its G1/S inhibitory function, pRB is involved in differentiation, prevention of cell death and control of tissue fate. To uncover the function of phosphorylation of pRB in various cellular conditions, we have been investigating phosphorylation of each serine/threonine residue in pRB with site-specific phospho-serine/threonine antibodies. Here we demonstrate that pRB is specifically phosphorylated at Ser612 in differentiated cells in a known kinase-independent manner. We also found that pRB phosphorylated at Ser612 still associates with E2F-1 and tightly binds to nuclear structures including chromatin. Moreover, expression of the Ser612Ala mutant pRB failed to induce differentiation. The findings suggest that phosphorylation of Ser612 provides a distinct function that differs from the function of phosphorylation of other serine/threonine residues in pRB.

  15. Characterization of intracellular regions in the human serotonin transporter for phosphorylation sites

    DEFF Research Database (Denmark)

    Sørensen, Lena; Strømgaard, Kristian; Kristensen, Anders S

    2014-01-01

    /dephosphorylation during transporter regulation by multiple pathways. In particular, activation and/or inhibition of kinases including PKC, PKG, p38MAPK, and CaMKII modulate SERT function and trafficking. The molecular mechanisms by which kinase activity is linked to SERT regulation are poorly understood, including...... the identity of specific phosphorylated residues. To elucidate SERT phosphorylation sites, we have generated peptides corresponding to the entire intracellular region of human SERT and performed in vitro phosphorylation assays with a panel of kinases suggested to be involved in SERT regulation or for which...

  16. Prolonged inorganic arsenite exposure suppresses insulin-stimulated AKT S473 phosphorylation and glucose uptake in 3T3-L1 adipocytes: Involvement of the adaptive antioxidant response

    International Nuclear Information System (INIS)

    Highlights: → In 3T3-L1 adipocytes iAs3+ decreases insulin-stimulated glucose uptake. → iAs3+ attenuates insulin-induced phosphorylation of AKT S473. → iAs3+ activates the cellular adaptive oxidative stress response. → iAs3+ impairs insulin-stimulated ROS signaling. → iAs3+ decreases expression of adipogenic genes and GLUT4. -- Abstract: There is growing evidence that chronic exposure of humans to inorganic arsenic, a potent environmental oxidative stressor, is associated with the incidence of type 2 diabetes (T2D). One critical feature of T2D is insulin resistance in peripheral tissues, especially in mature adipocytes, the hallmark of which is decreased insulin-stimulated glucose uptake (ISGU). Despite the deleterious effects of reactive oxygen species (ROS), they have been recognized as a second messenger serving an intracellular signaling role for insulin action. Nuclear factor erythroid 2-related factor 2 (NRF2) is a central transcription factor regulating cellular adaptive response to oxidative stress. This study proposes that in response to arsenic exposure, the NRF2-mediated adaptive induction of endogenous antioxidant enzymes blunts insulin-stimulated ROS signaling and thus impairs ISGU. Exposure of differentiated 3T3-L1 cells to low-level (up to 2 μM) inorganic arsenite (iAs3+) led to decreased ISGU in a dose- and time-dependent manner. Concomitant to the impairment of ISGU, iAs3+ exposure significantly attenuated insulin-stimulated intracellular ROS accumulation and AKT S473 phosphorylation, which could be attributed to the activation of NRF2 and induction of a battery of endogenous antioxidant enzymes. In addition, prolonged iAs3+ exposure of 3T3-L1 adipocytes resulted in significant induction of inflammatory response genes and decreased expression of adipogenic genes and glucose transporter type 4 (GLUT4), suggesting chronic inflammation and reduction in GLUT4 expression may also be involved in arsenic-induced insulin resistance in adipocytes

  17. Prolonged inorganic arsenite exposure suppresses insulin-stimulated AKT S473 phosphorylation and glucose uptake in 3T3-L1 adipocytes: Involvement of the adaptive antioxidant response

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Peng [The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); School of Public Health, China Medical University, Shenyang 110001 (China); Hou, Yongyong; Zhang, Qiang; Woods, Courtney G.; Yarborough, Kathy; Liu, Huiyu [The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); Sun, Guifan [School of Public Health, China Medical University, Shenyang 110001 (China); Andersen, Melvin E. [The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States); Pi, Jingbo, E-mail: jpi@thehamner.org [The Hamner Institutes for Health Sciences, Research Triangle Park, NC 27709 (United States)

    2011-04-08

    Highlights: {yields} In 3T3-L1 adipocytes iAs{sup 3+} decreases insulin-stimulated glucose uptake. {yields} iAs{sup 3+} attenuates insulin-induced phosphorylation of AKT S473. {yields} iAs{sup 3+} activates the cellular adaptive oxidative stress response. {yields} iAs{sup 3+} impairs insulin-stimulated ROS signaling. {yields} iAs{sup 3+} decreases expression of adipogenic genes and GLUT4. -- Abstract: There is growing evidence that chronic exposure of humans to inorganic arsenic, a potent environmental oxidative stressor, is associated with the incidence of type 2 diabetes (T2D). One critical feature of T2D is insulin resistance in peripheral tissues, especially in mature adipocytes, the hallmark of which is decreased insulin-stimulated glucose uptake (ISGU). Despite the deleterious effects of reactive oxygen species (ROS), they have been recognized as a second messenger serving an intracellular signaling role for insulin action. Nuclear factor erythroid 2-related factor 2 (NRF2) is a central transcription factor regulating cellular adaptive response to oxidative stress. This study proposes that in response to arsenic exposure, the NRF2-mediated adaptive induction of endogenous antioxidant enzymes blunts insulin-stimulated ROS signaling and thus impairs ISGU. Exposure of differentiated 3T3-L1 cells to low-level (up to 2 {mu}M) inorganic arsenite (iAs{sup 3+}) led to decreased ISGU in a dose- and time-dependent manner. Concomitant to the impairment of ISGU, iAs{sup 3+} exposure significantly attenuated insulin-stimulated intracellular ROS accumulation and AKT S473 phosphorylation, which could be attributed to the activation of NRF2 and induction of a battery of endogenous antioxidant enzymes. In addition, prolonged iAs{sup 3+} exposure of 3T3-L1 adipocytes resulted in significant induction of inflammatory response genes and decreased expression of adipogenic genes and glucose transporter type 4 (GLUT4), suggesting chronic inflammation and reduction in GLUT4

  18. Thioredoxin Binding Protein-2 Regulates Autophagy of Human Lens Epithelial Cells under Oxidative Stress via Inhibition of Akt Phosphorylation

    Science.gov (United States)

    Yao, Ke; Zhang, Yidong; Chen, Guangdi; Lai, Kairan; Yin, Houfa

    2016-01-01

    Oxidative stress plays an essential role in the development of age-related cataract. Thioredoxin binding protein-2 (TBP-2) is a negative regulator of thioredoxin (Trx), which deteriorates cellular antioxidant system. Our study focused on the autophagy-regulating effect of TBP-2 under oxidative stress in human lens epithelial cells (LECs). Human lens epithelial cells were used for cell culture and treatment. Lentiviral-based transfection system was used for overexpression of TBP-2. Cytotoxicity assay, western blot analysis, GFP/mCherry-fused LC3 plasmid, immunofluorescence, and transmission electronic microscopy were performed. The results showed that autophagic response of LECs with increased LC3-II, p62, and GFP/mCherry-LC3 puncta (P < 0.01) was induced by oxidative stress. Overexpression of TBP-2 further strengthens this response and worsens the cell viability (P < 0.01). Knockdown of TBP-2 attenuates the autophagic response and cell viability loss induced by oxidative stress. TBP-2 mainly regulates autophagy in the initiation stage, which is mTOR-independent and probably caused by the dephosphorylation of Akt under oxidative stress. These findings suggest a novel role of TBP-2 in human LECs under oxidative stress. Oxidative stress can cause cell injury and autophagy in LECs, and TBP-2 regulates this response. Hence, this study provides evidence regarding the role of TBP-2 in lens and the possible mechanism of cataract development. PMID:27656263

  19. AKT (protein kinase B) is implicated in meiotic maturation of porcine oocytes.

    Science.gov (United States)

    Kalous, Jaroslav; Kubelka, Michal; Solc, Petr; Susor, Andrej; Motlík, Jan

    2009-10-01

    The aim of this study was to investigate the involvement of the serine/threonine protein kinase AKT (also called protein kinase B) in the control of meiosis of porcine denuded oocytes (DOs) matured in vitro. Western blot analysis revealed that the two principal AKT phosphorylation sites, Ser473 and Thr308, are phosphorylated at different stages of meiosis. In freshly isolated germinal vesicle (GV)-stage DOs, Ser473 was already phosphorylated. After the onset of oocyte maturation, the intensity of the Ser473 phosphorylation increased, however, which declined sharply when DOs underwent GV breakdown (GVBD) and remained at low levels in metaphase I- and II-stage (MI- and MII-stage). In contrast, phosphorylation of Thr308 was increased by the time of GVBD and reached maximum at MI-stage. A peak of AKT activity was noticed around GVBD and activity of AKT declined at MI-stage. To assess the role of AKT during meiosis, porcine DOs were cultured in 50 microM SH-6, a specific inhibitor of AKT. In SH-6-treated DOs, GVBD was not inhibited; on the contrary, a significant acceleration of meiosis resumption was observed. The dynamics of the Ser473 phosphorylation was not affected; however, phosphorylation of Thr308 was reduced, AKT activity was diminished at the time of GVBD, and meiotic progression was arrested in early MI-stage. Moreover, the activity of the cyclin-dependent kinase 1 (CDK1) and MAP kinase declined when SH-6-treated DOs underwent GVBD, indicating that AKT activity is involved in the regulation of CDK1 and MAP kinase. These results suggest that activity of AKT is not essential for induction of GVBD in porcine oocytes but plays a substantial role during progression of meiosis to MI/MII-stage.

  20. Ghrelin promotes intestinal epithelial cell proliferation through PI3K/Akt pathway and EGFR trans-activation both converging to ERK 1/2 phosphorylation.

    Science.gov (United States)

    Waseem, Talat; Duxbury, Mark; Ashley, Stanley W; Robinson, Malcolm K

    2014-02-01

    Little is known about ghrelin's effects on intestinal epithelial cells even though it is known to be a mitogen for a variety of other cell types. Because ghrelin is released in close proximity to the proliferative compartment of the intestinal tract, we hypothesized that ghrelin may have potent pro-proliferative effect on intestinal epithelial cells as well. To test this hypothesis, we characterized the effects of ghrelin on FHs74Int and Caco-2 intestinal epithelial cell lines in vitro. We found that ghrelin has potent dose dependent proliferative effects in both cell lines through a yet to be characterized G protein coupled growth hormone secretagogue receptor (GHS-R) subtype. Consistent with above findings, cell cycle flowcytometric analyses demonstrated that ghrelin shifts cells from the G1 to S phase and thereby promotes cell cycle progression. Further characterization of subcellular events, suggested that ghrelin mediates its pro-proliferative effect through Adenylate cyclase (AC)-independent epidermal growth factor receptor (EGFR) trans-activation and PI3K-Akt phosphorylation. Both these pathways converge to stimulate MAPK, ERK 1/2 downstream. The role of ghrelin in states where intestinal mucosal injury and rapid mucosal repair occur warrants further investigation.

  1. In Vivo Phosphorylation Site Mapping and Functional Characterization of Arabidopsis Phototropin 1

    Institute of Scientific and Technical Information of China (English)

    Stuart Sullivan; Catriona E. Thomson; Douglas J.Lamont; Matthew A. Jones; John M.Christie

    2008-01-01

    Phototropins (phot1 and phot2) are blue-light receptor kinases controlling a range of responses that optimize the photosynthetic efficiency of plants. Light sensing is mediated by two flavin-binding motifs, known as LOV1 and LOV2,located within the N-terminal region of the protein. Photoexcitation via LOV2 leads to activation of the C-terminal kinase domain and consequently receptor autophosphorylation. However, knowledge of the in-vivo phosphorylation sites for Arabidopsis phototropins is lacking and has impeded progress in elucidating the functional significance of receptor phosphorylation. We have purified phot1 from Arabidopsis and identified the in-vivo sites of receptor phosphorylation by liquid chromatography tandem mass spectrometry. Arabidopsis-derived phot1 binds flavin mononucleotide as chromophore and is phosphorylated at four major sites located upstream of LOV2 (Ser58, Ser85, Ser350, and Ser410), three of which are induced by blue light. Nevertheless, structure-function analysis indicates that the biological activity of phot1 can be attributed to a modular unit comprising the LOV2-kinase region of the protein. Thus, peptide regions upstream of LOV2, including the sites of receptor phosphorylation identified here, do not appear to be important for receptor signaling. By contrast, these regions may be necessary for maximizing stomatal performance and possibly light-induced relocalization of phot1.

  2. Novel method for the high-throughput production of phosphorylation site-specific monoclonal antibodies

    Science.gov (United States)

    Kurosawa, Nobuyuki; Wakata, Yuka; Inobe, Tomonao; Kitamura, Haruki; Yoshioka, Megumi; Matsuzawa, Shun; Kishi, Yoshihiro; Isobe, Masaharu

    2016-01-01

    Threonine phosphorylation accounts for 10% of all phosphorylation sites compared with 0.05% for tyrosine and 90% for serine. Although monoclonal antibody generation for phospho-serine and -tyrosine proteins is progressing, there has been limited success regarding the production of monoclonal antibodies against phospho-threonine proteins. We developed a novel strategy for generating phosphorylation site-specific monoclonal antibodies by cloning immunoglobulin genes from single plasma cells that were fixed, intracellularly stained with fluorescently labeled peptides and sorted without causing RNA degradation. Our high-throughput fluorescence activated cell sorting-based strategy, which targets abundant intracellular immunoglobulin as a tag for fluorescently labeled antigens, greatly increases the sensitivity and specificity of antigen-specific plasma cell isolation, enabling the high-efficiency production of monoclonal antibodies with desired antigen specificity. This approach yielded yet-undescribed guinea pig monoclonal antibodies against threonine 18-phosphorylated p53 and threonine 68-phosphorylated CHK2 with high affinity and specificity. Our method has the potential to allow the generation of monoclonal antibodies against a variety of phosphorylated proteins. PMID:27125496

  3. Site-specific IGFBP-1 hyper-phosphorylation in fetal growth restriction: clinical and functional relevance.

    Science.gov (United States)

    Abu Shehab, Majida; Khosravi, Javad; Han, Victor K M; Shilton, Brian H; Gupta, Madhulika B

    2010-04-01

    Phosphorylation enhances IGFBP-1 binding to IGF-I, thereby limiting the bioavailability of IGF-I that may be important in fetal growth. Our goal in this study was to determine whether changes in site-specific IGFBP-1 phosphorylation were unique to fetal growth restriction. To establish a link, we compared IGFBP-1 phosphorylation (sites and degree) in amniotic fluid from FGR (N = 10) and controls (N = 12). The concentration of serine phosphorylated IGFBP-1 showed a negative correlation with birth weight in FGR (P = 0.049). LC-MS/MS analysis revealed all four previously identified phosphorylation sites (Ser98, Ser101, Ser119, and Ser169) to be common to FGR and control groups. Relative phosphopeptide intensities (LC-MS) between FGR and controls demonstrated 4-fold higher intensity for Ser101 (P = 0.026), 7-fold for Ser98/Ser101 (P = 0.02), and 23-fold for Ser169 (P = 0.002) in the FGR group. Preliminary BIAcore data revealed 4-fold higher association and 1.7-fold lower dissociation constants for IGFBP-1/IGF-I in FGR. A structural model of IGFBP-1 bound to IGF-I indicates that all the phosphorylation sites are on relatively mobile regions of the IGFBP-1 sequence. Residues Ser98, Ser101, and Ser169 are close to structured regions that are involved in IGF-I binding and, therefore, could potentially make direct contact with IGF-I. On the other hand, residue Ser119 is in the middle of the unstructured linker that connects the N- and C-terminal domains of IGFBP-1. The model is consistent with the assumption that residues Ser98, Ser101, and Ser169 could directly interact with IGF-I, and therefore phosphorylation at these sites could change IGF-I interactions. We suggest that site-specific increase in IGFBP-1 phosphorylation limits IGF-I bioavailability, which directly contributes to the development of FGR. This study delineates the potential role of higher phosphorylation of IGFBP-1 in FGR and provides the basis to substantiate these findings with larger sample size. PMID

  4. Regulation of alternative splice site selection by reversible protein phosphorylation

    OpenAIRE

    Novoyatleva, Tatyana

    2007-01-01

    Splicing is the process that removes introns and joins exons from pre-mesenger RNA (pre-mRNA). It is an essential step in pre-mRNA processing that form the mature RNA. Microarray data indicates that approximately 75% of human genes produce transcripts that are alternatively spliced. Alternative splicing is one of the major mechanisms that ultimately generate high number of protein isoforms from a limited number of genes. The proper catalysis and regulation of alternative splice site selection...

  5. Osteopontin: A uranium phosphorylated binding-site characterization

    International Nuclear Information System (INIS)

    Herein, we describe the structural investigation of one possible uranyl binding site inside a non structured protein. This approach couples spectroscopy, thermodynamics, and theoretical calculations (DFT) and studies the interaction of uranyl ions with a phospho-peptide, thus mimicking a possible osteopontin (OPN) hydroxyapatite growth-inhibition site. Although thermodynamical aspects were investigated by using time-resolved laser fluorescence spectroscopy (TRLFS) and isothermal titration calorimetry (ITC), structural characterization was performed by extended X-ray absorption fine structure (EXAFS) at the U L(III)-edge combined with attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. From the vibrational and fluorescence spectra, several structural models of a UO22+/peptide complex were developed and subsequently refined by using theoretical calculations to fit the experimental EXAFS obtained. The structural effect of the pH value was also considered under acidic to moderately acidic conditions (pH 1.5-5.5). Most importantly, the uranyl/peptide coordination environment was similar to that of the native protein. (authors)

  6. The protein kinase DYRK1A phosphorylates the splicing factor SF3b1/SAP155 at Thr434, a novel in vivo phosphorylation site

    Directory of Open Access Journals (Sweden)

    Lilischkis Richard

    2006-03-01

    Full Text Available Abstract Background The U2 small nuclear ribonucleoprotein particle (snRNP component SF3b1/SAP155 is the only spliceosomal protein known to be phosphorylated concomitant with splicing catalysis. DYRK1A is a nuclear protein kinase that has been localized to the splicing factor compartment. Here we describe the identification of DYRK1A as a protein kinase that phosphorylates SF3b1 in vitro and in cultivated cells. Results Overexpression of DYRK1A caused a markedly increased phosphorylation of SF3b1 in COS-7 cells as assessed by Western blotting with an antibody specific for phosphorylated Thr-Pro dipeptide motifs. Phosphopeptide mapping of metabolically labelled SF3b1 showed that the majority of the in vivo-phosphopeptides corresponded to sites also phosphorylated by DYRK1A in vitro. Phosphorylation with cyclin E/CDK2, a kinase previously reported to phosphorylate SF3b1, generated a completely different pattern of phosphopeptides. By mass spectrometry and mutational analysis of SF3b1, Thr434 was identified as the major phosphorylation site for DYRK1A. Overexpression of DYRK1A or the related kinase, DYRK1B, resulted in an enhanced phosphorylation of Thr434 in endogenous SF3b1 in COS-7 cells. Downregulation of DYRK1A in HEK293 cells or in HepG2 cells by RNA interference reduced the phosphorylation of Thr434 in SF3b1. Conclusion The present data show that the splicing factor SF3b1 is a substrate of the protein kinase DYRK1A and suggest that DYRK1A may be involved in the regulation of pre mRNA-splicing.

  7. PI3K/Akt promotes feedforward mTORC2 activation through IKKα.

    Science.gov (United States)

    Dan, Han C; Antonia, Ricardo J; Baldwin, Albert S

    2016-04-19

    The ser-thr Akt plays a critical role in the regulation of cell survival, cell growth and proliferation, as well as energy metabolism and is dysregulated in many cancers. The regulation of Akt activity depends on the phosphorylation at two sites: (i) Thr308 in the activation loop by phosphoinositide-dependent kinase-1 (PDK1) and (ii) Ser473 hydrophobic motif at the carboxyl terminus by a second activity termed PDK2, which is the mTORC2 complex composed of mTOR, rictor, and Sin1. Previously we demonstrated that IKKα, a component of the IKK complex that controls NF-κB activation, participates in the Akt-dependent regulation of mTORC1. Here we have explored a potential involvement of IKKα in controlling Akt activity and whether this may involve mTORC2. The experiments show that IKKα associates with mTORC2 in several cancer cells in a manner dependent on PI3K/Akt activity and that IKKα positively promotes Akt phosphorylation at Ser473 and at Thr308. Moreover, IKKα enhances mTORC2 kinase activity directed to Akt on Ser473 and Akt-mediated phosphorylation of FOXO3a and GSK3β, but not other Akt-associated targets such as TSC2 and PRAS40, indicating the existence of multiple mechanisms of Akt activation in cells. In addition, loss of IKKα suppresses growth factor-induced Akt activation associated with mTORC1 inhibition. These results indicate that IKKα serves as a feedforward regulator of mTORC2 and that IKKα could serve as a key therapeutic target to block mTORC2 and Akt activation in some cancers. PMID:27027448

  8. PhosTryp: a phosphorylation site predictor specific for parasitic protozoa of the family trypanosomatidae

    Directory of Open Access Journals (Sweden)

    Palmeri Antonio

    2011-12-01

    Full Text Available Abstract Background Protein phosphorylation modulates protein function in organisms at all levels of complexity. Parasites of the Leishmania genus undergo various developmental transitions in their life cycle triggered by changes in the environment. The molecular mechanisms that these organisms use to process and integrate these external cues are largely unknown. However Leishmania lacks transcription factors, therefore most regulatory processes may occur at a post-translational level and phosphorylation has recently been demonstrated to be an important player in this process. Experimental identification of phosphorylation sites is a time-consuming task. Moreover some sites could be missed due to the highly dynamic nature of this process or to difficulties in phospho-peptide enrichment. Results Here we present PhosTryp, a phosphorylation site predictor specific for trypansomatids. This method uses an SVM-based approach and has been trained with recent Leishmania phosphosproteomics data. PhosTryp achieved a 17% improvement in prediction performance compared with Netphos, a non organism-specific predictor. The analysis of the peptides correctly predicted by our method but missed by Netphos demonstrates that PhosTryp captures Leishmania-specific phosphorylation features. More specifically our results show that Leishmania kinases have sequence specificities which are different from their counterparts in higher eukaryotes. Consequently we were able to propose two possible Leishmania-specific phosphorylation motifs. We further demonstrate that this improvement in performance extends to the related trypanosomatids Trypanosoma brucei and Trypanosoma cruzi. Finally, in order to maximize the usefulness of PhosTryp, we trained a predictor combining all the peptides from L. infantum, T. brucei and T. cruzi. Conclusions Our work demonstrates that training on organism-specific data results in an improvement that extends to related species. PhosTryp is freely

  9. Contractions induce phosphorylation of the AMPK site Ser565 in hormone-sensitive lipase in muscle

    DEFF Research Database (Denmark)

    Donsmark, Morten; Langfort, Jozef; Holm, Cecilia;

    2004-01-01

    Intramyocellular triglyceride is an important energy store which is related to insulin resistance. Mobilization of fatty acids from this pool is probably regulated by hormone-sensitive lipase (HSL), which has recently been shown to exist in muscle and to be activated by epinephrine via PKA...... and by contractions via PKC and ERK. 5' AMP-activated protein kinase (AMPK) is an intracellular fuel gauge which regulates metabolism. In this study we incubated rat soleus muscle to investigate if AMPK influences HSL during 5min of repeated tetanic contractions. An eightfold increase in AMPK activity was accompanied...... by a 2.5-fold increase in phosphorylation of the AMPK-site Ser(565) in HSL (pHSL activation while HSL-Ser(565) phosphorylation was not reduced. The study indicates that during contractions AMPK phosphorylates HSL in Ser(565...

  10. Membrane protein assembly: two cytoplasmic phosphorylated serine sites of Vpu from HIV-1 affect oligomerization

    Science.gov (United States)

    Chen, Chin-Pei; Lin, Meng-Han; Chan, Ya-Ting; Chen, Li-Chyong; Ma, Che; Fischer, Wolfgang B.

    2016-01-01

    Viral protein U (Vpu) encoded by human immunodeficiency virus type 1 (HIV-1) is a short integral membrane protein which is known to self-assemble within the lipid membrane and associate with host factors during the HIV-1 infectivity cycle. In this study, full-length Vpu (M group) from clone NL4-3 was over-expressed in human cells and purified in an oligomeric state. Various single and double mutations were constructed on its phosphorylation sites to mimic different degrees of phosphorylation. Size exclusion chromatography of wild-type Vpu and mutants indicated that the smallest assembly unit of Vpu was a dimer and over time Vpu formed higher oligomers. The rate of oligomerization increased when (i) the degree of phosphorylation at serines 52 and 56 was decreased and (ii) when the ionic strength was increased indicating that the cytoplasmic domain of Vpu affects oligomerization. Coarse-grained molecular dynamic simulations with models of wild-type and mutant Vpu in a hydrated lipid bilayer supported the experimental data in demonstrating that, in addition to a previously known role in downregulation of host factors, the phosphorylation sites of Vpu also modulate oligomerization. PMID:27353136

  11. DNA Replication Stress Phosphoproteome Profiles Reveal Novel Functional Phosphorylation Sites on Xrs2 in Saccharomyces cerevisiae.

    Science.gov (United States)

    Huang, Dongqing; Piening, Brian D; Kennedy, Jacob J; Lin, Chenwei; Jones-Weinert, Corey W; Yan, Ping; Paulovich, Amanda G

    2016-05-01

    In response to replication stress, a phospho-signaling cascade is activated and required for coordination of DNA repair and replication of damaged templates (intra-S-phase checkpoint) . How phospho-signaling coordinates the DNA replication stress response is largely unknown. We employed state-of-the-art liquid chromatography tandem-mass spectrometry (LC-MS/MS) approaches to generate high-coverage and quantitative proteomic and phospho-proteomic profiles during replication stress in yeast, induced by continuous exposure to the DNA alkylating agent methyl methanesulfonate (MMS) . We identified 32,057 unique peptides representing the products of 4296 genes and 22,061 unique phosphopeptides representing the products of 3183 genes. A total of 542 phosphopeptides (mapping to 339 genes) demonstrated an abundance change of greater than or equal to twofold in response to MMS. The screen enabled detection of nearly all of the proteins known to be involved in the DNA damage response, as well as many novel MMS-induced phosphorylations. We assessed the functional importance of a subset of key phosphosites by engineering a panel of phosphosite mutants in which an amino acid substitution prevents phosphorylation. In total, we successfully mutated 15 MMS-responsive phosphorylation sites in seven representative genes including APN1 (base excision repair); CTF4 and TOF1 (checkpoint and sister-chromatid cohesion); MPH1 (resolution of homologous recombination intermediates); RAD50 and XRS2 (MRX complex); and RAD18 (PRR). All of these phosphorylation site mutants exhibited MMS sensitivity, indicating an important role in protecting cells from DNA damage. In particular, we identified MMS-induced phosphorylation sites on Xrs2 that are required for MMS resistance in the absence of the MRX activator, Sae2, and that affect telomere maintenance. PMID:27017623

  12. Characterizing Active Site Conformational Heterogeneity along the Trajectory of an Enzymatic Phosphoryl Transfer Reaction.

    Science.gov (United States)

    Zeymer, Cathleen; Werbeck, Nicolas D; Zimmermann, Sabine; Reinstein, Jochen; Hansen, D Flemming

    2016-09-12

    States along the phosphoryl transfer reaction catalyzed by the nucleoside monophosphate kinase UmpK were captured and changes in the conformational heterogeneity of conserved active site arginine side-chains were quantified by NMR spin-relaxation methods. In addition to apo and ligand-bound UmpK, a transition state analog (TSA) complex was utilized to evaluate the extent to which active site conformational entropy contributes to the transition state free energy. The catalytically essential arginine side-chain guanidino groups were found to be remarkably rigid in the TSA complex, indicating that the enzyme has evolved to restrict the conformational freedom along its reaction path over the energy landscape, which in turn allows the phosphoryl transfer to occur selectively by avoiding side reactions. PMID:27534930

  13. Phosphoproteomics of the Arabidopsis plasma membrane and a new phosphorylation site database

    DEFF Research Database (Denmark)

    Nühse, Thomas S; Stensballe, Allan; Jensen, Ole N;

    2004-01-01

    Functional genomic technologies are generating vast amounts of data describing the presence of transcripts or proteins in plant cells. Together with classical genetics, these approaches broaden our understanding of the gene products required for specific responses. Looking to the future, the focus...... database for plant phosphorylation sites maintained by PlantsP (http://plantsp.sdsc.edu) that will be updated as the project expands to encompass additional tissues and organelles....

  14. Insulin stimulation regulates AS160 and TBC1D1 phosphorylation sites in human skeletal muscle

    DEFF Research Database (Denmark)

    Middelbeek, R J W; Chambers, M A; Tantiwong, P;

    2013-01-01

    Individuals with obesity and type 2 diabetes (T2D) are typically insulin resistant, exhibiting impaired skeletal muscle glucose uptake. Animal and cell culture experiments have shown that site-specific phosphorylation of the Rab-GTPase-activating proteins AS160 and TBC1D1 is critical for GLUT4 tr...... translocation facilitating glucose uptake, but their regulation in human skeletal muscle is not well understood....

  15. 骨骼肌收缩模式对p38/Akt磷酸化水平的影响%The influence of contraction modes on the phosphorylation of p38/Akt

    Institute of Scientific and Technical Information of China (English)

    李辉; 焦博; 余志斌; 陈自谦

    2011-01-01

    Objective: Muscle contraction may prompt glucose uptake through non-insulin-dependent ways, and it may be due to the enhanced activation of key proteins known to regulate glucose metabolism, like p38 and Akt. Our experiment focused on the impact of different contraction modes on the phosphorylation of the molecules, thus to explore effective ways to lower blood glucose. Methods: Isolated muscle strips perfusion technique and Western blot analysis were employed to investigate the influence of different modes of contraction on the activation of the molecules. Results: Muscle contraction led to an increase in p38 phosphorylation, with the greatest effect observed after 5 minutes of 10% DC(duty cycle) contraction and 5 minutes of 1 % DC contraction. However, phosphorylation of Akt were not altered by the two contraction modes. Conclusion: The level of phosphorylation of p38 was higher at the optimal contraction modes, but these modes could not increase the level of phosphorlation of Akt.%目的:骨骼肌收缩可能通过非胰岛素依赖的途径促进葡萄糖摄取,而p38与Akt可能是其中起重要作用的分子.本文研究骨骼肌不同收缩模式对上述信号分子磷酸化的影响,从而探讨有效降低血糖的运动方式.方法:采用离体比目鱼肌肌条灌流技术及Western blot检测方法,研究不同模式的收缩对骨骼肌p38、Akt磷酸化水平的影响.结果:5 min 10%DC(duty cycle负荷率)和5min 1% DC的收缩模式可分别使p38的磷酸化较对照组增加30%和34%,是激活p38的适宜刺激.但对Akt的磷酸化水平没有影响.结论:低强度有氧运动可以更好地激活p38,但不能有效激活Akt.

  16. Novel protein phosphorylation site identification in spinach stroma membranes by titanium dioxide microcolumns and tandem mass spectrometry

    DEFF Research Database (Denmark)

    Rinalducci, Sara; Larsen, Martin Røssel; Mohammed, Shabaz;

    2006-01-01

    In this work, spinach stroma membrane, instead of thylakoid, has been investigated for the presence of phosphorylated proteins. We identified seven previously unknown phosphorylation sites by taking advantage of TiO(2) phosphopeptides enrichment coupled to mass spectrometric analysis. Upon illumi...

  17. Coarse-grained molecular simulation of epidermal growth factor receptor protein tyrosine kinase multi-site self-phosphorylation.

    Directory of Open Access Journals (Sweden)

    John G Koland

    2014-01-01

    Full Text Available Upon the ligand-dependent dimerization of the epidermal growth factor receptor (EGFR, the intrinsic protein tyrosine kinase (PTK activity of one receptor monomer is activated, and the dimeric receptor undergoes self-phosphorylation at any of eight candidate phosphorylation sites (P-sites in either of the two C-terminal (CT domains. While the structures of the extracellular ligand binding and intracellular PTK domains are known, that of the ∼225-amino acid CT domain is not, presumably because it is disordered. Receptor phosphorylation on CT domain P-sites is critical in signaling because of the binding of specific signaling effector molecules to individual phosphorylated P-sites. To investigate how the combination of conventional substrate recognition and the unique topological factors involved in the CT domain self-phosphorylation reaction lead to selectivity in P-site phosphorylation, we performed coarse-grained molecular simulations of the P-site/catalytic site binding reactions that precede EGFR self-phosphorylation events. Our results indicate that self-phosphorylation of the dimeric EGFR, although generally believed to occur in trans, may well occur with a similar efficiency in cis, with the P-sites of both receptor monomers being phosphorylated to a similar extent. An exception was the case of the most kinase-proximal P-site-992, the catalytic site binding of which occurred exclusively in cis via an intramolecular reaction. We discovered that the in cis interaction of P-site-992 with the catalytic site was facilitated by a cleft between the N-terminal and C-terminal lobes of the PTK domain that allows the short CT domain sequence tethering P-site-992 to the PTK core to reach the catalytic site. Our work provides several new mechanistic insights into the EGFR self-phosphorylation reaction, and demonstrates the potential of coarse-grained molecular simulation approaches for investigating the complexities of self-phosphorylation in

  18. Assessment of current mass spectrometric workflows for the quantification of low abundant proteins and phosphorylation sites

    Directory of Open Access Journals (Sweden)

    Manuel Bauer

    2015-12-01

    Full Text Available The data described here provide a systematic performance evaluation of popular data-dependent (DDA and independent (DIA mass spectrometric (MS workflows currently used in quantitative proteomics. We assessed the limits of identification, quantification and detection for each method by analyzing a dilution series of 20 unmodified and 10 phosphorylated synthetic heavy labeled reference peptides, respectively, covering six orders of magnitude in peptide concentration with and without a complex human cell digest background. We found that all methods performed very similarly in the absence of background proteins, however, when analyzing whole cell lysates, targeted methods were at least 5–10 times more sensitive than directed or DDA methods. In particular, higher stage fragmentation (MS3 of the neutral loss peak using a linear ion trap increased dynamic quantification range of some phosphopeptides up to 100-fold. We illustrate the power of this targeted MS3 approach for phosphopeptide monitoring by successfully quantifying 9 phosphorylation sites of the kinetochore and spindle assembly checkpoint component Mad1 over different cell cycle states from non-enriched pull-down samples. The data are associated to the research article ‘Evaluation of data-dependent and data-independent mass spectrometric workflows for sensitive quantification of proteins and phosphorylation sites׳ (Bauer et al., 2014 [1]. The mass spectrometry and the analysis dataset have been deposited to the ProteomeXchange Consortium (http://proteomecentral.proteomexchange.org via the PRIDE partner repository with the dataset identifier PXD000964.

  19. Identification of phosphorylation sites in the nucleocapsid protein (N protein) of SARS-coronavirus

    Science.gov (United States)

    Lin, Liang; Shao, Jianmin; Sun, Maomao; Liu, Jinxiu; Xu, Gongjin; Zhang, Xumin; Xu, Ningzhi; Wang, Rong; Liu, Siqi

    2007-12-01

    After decoding the genome of SARS-coronavirus (SARS-CoV), next challenge is to understand how this virus causes the illness at molecular bases. Of the viral structural proteins, the N protein plays a pivot role in assembly process of viral particles as well as viral replication and transcription. The SARS-CoV N proteins expressed in the eukaryotes, such as yeast and HEK293 cells, appeared in the multiple spots on two-dimensional electrophoresis (2DE), whereas the proteins expressed in E. coli showed a single 2DE spotE These 2DE spots were further examined by Western blot and MALDI-TOF/TOF MS, and identified as the N proteins with differently apparent pI values and similar molecular mass of 50 kDa. In the light of the observations and other evidences, a hypothesis was postulated that the SARS-CoV N protein could be phosphorylated in eukaryotes. To locate the plausible regions of phosphorylation in the N protein, two truncated N proteins were generated in E. coli and treated with PKC[alpha]. The two truncated N proteins after incubation of PKC[alpha] exhibited the differently electrophoretic behaviors on 2DE, suggesting that the region of 1-256 aa in the N protein was the possible target for PKC[alpha] phosphorylation. Moreover, the SARS-CoV N protein expressed in yeast were partially digested with trypsin and carefully analyzed by MALDI-TOF/TOF MS. In contrast to the completely tryptic digestion, these partially digested fragments generated two new peptide mass signals with neutral loss, and MS/MS analysis revealed two phosphorylated peptides located at the "dense serine" island in the N protein with amino acid sequences, GFYAEGSRGGSQASSRSSSR and GNSGNSTPGSSRGNSPARMASGGGK. With the PKC[alpha] phosphorylation treatment and the partially tryptic digestion, the N protein expressed in E. coli released the same peptides as observed in yeast cells. Thus, this investigation provided the preliminary data to determine the phosphorylation sites in the SARS-CoV N protein, and

  20. Phospho.ELM: a database of phosphorylation sites--update 2011

    DEFF Research Database (Denmark)

    Dinkel, Holger; Chica, Claudia; Via, Allegra;

    2011-01-01

    The Phospho.ELM resource (http://phospho.elm.eu.org) is a relational database designed to store in vivo and in vitro phosphorylation data extracted from the scientific literature and phosphoproteomic analyses. The resource has been actively developed for more than 7 years and currently comprises 42......,574 serine, threonine and tyrosine non-redundant phosphorylation sites. Several new features have been implemented, such as structural disorder/order and accessibility information and a conservation score. Additionally, the conservation of the phosphosites can now be visualized directly on the multiple...... sequence alignment used for the score calculation. Finally, special emphasis has been put on linking to external resources such as interaction networks and other databases....

  1. Pim kinases phosphorylate multiple sites on Bad and promote 14-3-3 binding and dissociation from Bcl-XL

    Directory of Open Access Journals (Sweden)

    Hastie C James

    2006-01-01

    Full Text Available Abstract Background Pim-1, 2 and 3 are a group of enzymes related to the calcium calmodulin family of protein kinases. Over-expression of Pim-1 and Pim-2 in mice promotes the development of lymphomas, and up-regulation of Pim expression has been observed in several human cancers. Results Here we show that the pim kinases are constitutively active when expressed in HEK-293 cells and are able to phosphorylate the Bcl-2 family member Bad on three residues, Ser112, Ser136 and Ser155 in vitro and in cells. In vitro mapping showed that Pim-2 predominantly phosphorylated Ser112, while Pim-1 phosphorylated Ser112, but also Ser136 and Ser155 at a reduced rate compared to Ser112. Pim-3 was found to be the least specific for Ser112, and the most effective at phosphorylating Ser136 and Ser155. Pim-3 was also able to phosphorylate other sites in Bad in vitro, including Ser170, another potential in vivo site. Mutation of Ser136 to alanine prevented the phosphorylation of Ser112 and Ser155 by Pim kinases in HEK-293 cells, suggesting that this site must be phosphorylated first in order to make the other sites accessible. Pim phosphorylation of Bad was also found to promote the 14-3-3 binding of Bad and block its association with Bcl-XL. Conclusion All three Pim kinase family members predominantly phosphorylate Bad on Ser112 and in addition are capable of phosphorylating Bad on multiple sites associated with the inhibition of the pro-apoptotic function of Bad in HEK-293 cells. This would be consistent with the proposed function of Pim kinases in promoting cell proliferation and preventing cell death.

  2. Identification of phosphorylation sites of proteins by high performance liquid chromatography-electrospray ionization-quadrupole ion trap mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    车发云; 邵晓霞; 夏其昌

    2000-01-01

    The phosphorylation sites of two phosphorylated proteins, bovine β-casein and myelin basic protein (MBP), were identified by high performance liquid chromatography-electrospray ionization-quadrupole ion trap mass spectrometry (HPLC-ESI-QITMS). The tryptic digest of each protein was separated by HPLC, the molecular weight of each peptide was determined by ESI-QITMS on line, and MS/MS spectrum of each peptide was simultaneously obtained by the combination of collision-induced desorption (CID) technique and tandem mass spectrometry (MS/MS) of QITMS. The phosphorylated peptide was identified by looking into whether the difference between the observed and predicted molecular weights of a peptide is 80 u or its integral multiple. Then the phosphorylation site was identified through manual interpretation of the MS/MS spectrum of the phosphorylated peptide or automatic SEQUEST data base-searching.

  3. Identification of phosphorylation sites of proteins by high performance liquid chromatography-electrospray ionization-quadrupole ion trap mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The phosphorylation sites of two phosphorylated proteins, bovine b-casein and myelin basic protein (MBP), were identified by high performance liquid chromatography-electrospray ionization-quadrupole ion trap mass spectrometry (HPLC-ESI-QITMS). The tryptic digest of each protein was separated by HPLC, the molecular weight of each peptide was determined by ESI-QITMS on line, and MS/MS spectrum of each peptide was simultaneously obtained by the combination of collision-induced desorption (CID) technique and tandem mass spectrometry (MS/MS) of QITMS. The phosphorylated peptide was identified by looking into whether the difference between the observed and predicted molecular weights of a peptide is 80 u or its integral multiple. Then the phosphorylation site was identified through manual interpretation of the MS/MS spectrum of the phosphorylated peptide or automatic SEQUEST data base-searching.

  4. Mechanical stimulation of cyclic tensile strain induces reduction of pluripotent related gene expressions via activation of Rho/ROCK and subsequent decreasing of AKT phosphorylation in human induced pluripotent stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Teramura, Takeshi, E-mail: teramura@med.kindai.ac.jp [Institute of Advanced Clinical Medicine, Kinki University, Faculty of Medicine, Osaka (Japan); Takehara, Toshiyuki; Onodera, Yuta [Institute of Advanced Clinical Medicine, Kinki University, Faculty of Medicine, Osaka (Japan); Nakagawa, Koichi; Hamanishi, Chiaki [Department of Orthopaedic Surgery, Kinki University, Faculty of Medicine, Osaka (Japan); Fukuda, Kanji [Institute of Advanced Clinical Medicine, Kinki University, Faculty of Medicine, Osaka (Japan); Department of Orthopaedic Surgery, Kinki University, Faculty of Medicine, Osaka (Japan)

    2012-01-13

    Highlights: Black-Right-Pointing-Pointer Mechanical stimulation is an important factor for regulation of stem cell fate. Black-Right-Pointing-Pointer Cyclic stretch to human induced pluripotent stem cells activated small GTPase Rho. Black-Right-Pointing-Pointer Rho-kinase activation attenuated pluripotency via inhibition of AKT activation. Black-Right-Pointing-Pointer This reaction could be reproduced only by transfection of dominant active Rho. Black-Right-Pointing-Pointer Rho/ROCK are important molecules in mechanotransduction and control of stemness. -- Abstract: Mechanical stimulation has been shown to regulate the proliferation and differentiation of stem cells. However, the effects of the mechanical stress on the stemness or related molecular mechanisms have not been well determined. Pluripotent stem cells such as embryonic stem (ES) cells and induced pluripotent stem (iPS) cells are used as good materials for cell transplantation therapy and research of mammalian development, since they can self-renew infinitely and differentiate into various cell lineages. Here we demonstrated that the mechanical stimulation to human iPS cells altered alignment of actin fibers and expressions of the pluripotent related genes Nanog, POU5f1 and Sox2. In the mechanically stimulated iPS cells, small GTPase Rho was activated and interestingly, AKT phosphorylation was decreased. Inhibition of Rho-associated kinase ROCK recovered the AKT phosphorylation and the gene expressions. These results clearly suggested that the Rho/ROCK is a potent primary effector of mechanical stress in the pluripotent stem cells and it participates to pluripotency-related signaling cascades as an upper stream regulator.

  5. Rice_Phospho 1.0: a new rice-specific SVM predictor for protein phosphorylation sites

    OpenAIRE

    Lin, Shoukai; Song, Qi; Tao, Huan; Wang, Wei; Wan, Weifeng; Huang, Jian; Xu, Chaoqun; Chebii, Vivien; Kitony, Justine; Que, Shufu; Harrison, Andrew; He, Huaqin

    2015-01-01

    Experimentally-determined or computationally-predicted protein phosphorylation sites for distinctive species are becoming increasingly common. In this paper, we compare the predictive performance of a novel classification algorithm with different encoding schemes to develop a rice-specific protein phosphorylation site predictor. Our results imply that the combination of Amino acid occurrence Frequency with Composition of K-Spaced Amino Acid Pairs (AF-CKSAAP) provides the best description of r...

  6. Evolution of nuclear retinoic acid receptor alpha (RARα) phosphorylation sites. Serine gain provides fine-tuned regulation.

    Science.gov (United States)

    Samarut, Eric; Amal, Ismail; Markov, Gabriel V; Stote, Roland; Dejaegere, Annick; Laudet, Vincent; Rochette-Egly, Cécile

    2011-07-01

    The human nuclear retinoic acid (RA) receptor alpha (hRARα) is a ligand-dependent transcriptional regulator, which is controlled by a phosphorylation cascade. The cascade starts with the RA-induced phosphorylation of a serine residue located in the ligand-binding domain, S(LBD), allowing the recruitment of the cdk7/cyclin H/MAT1 subcomplex of TFIIH through the docking of cyclin H. It ends by the subsequent phosphorylation by cdk7 of an other serine located in the N-terminal domain, S(NTD). Here, we show that this cascade relies on an increase in the flexibility of the domain involved in cyclin H binding, subsequently to the phosphorylation of S(LBD). Owing to the functional importance of RARα in several vertebrate species, we investigated whether the phosphorylation cascade was conserved in zebrafish (Danio rerio), which expresses two RARα genes: RARα-A and RARα-B. We found that in zebrafish RARαs, S(LBD) is absent, whereas S(NTD) is conserved and phosphorylated. Therefore, we analyzed the pattern of conservation of the phosphorylation sites and traced back their evolution. We found that S(LBD) is most often absent outside mammalian RARα and appears late during vertebrate evolution. In contrast, S(NTD) is conserved, indicating that the phosphorylation of this functional site has been under ancient high selection constraint. This suggests that, during evolution, different regulatory circuits control RARα activity. PMID:21297158

  7. Arsenite-induced stress signaling: Modulation of the phosphoinositide 3′-kinase/Akt/FoxO signaling cascade

    Directory of Open Access Journals (Sweden)

    Ingrit Hamann

    2013-01-01

    Full Text Available FoxO transcription factors and their regulators in the phosphoinositide 3′-kinase (PI3K/Akt signaling pathway play an important role in the control of cellular processes involved in carcinogenesis, such as proliferation and apoptosis. We have previously demonstrated that physiologically relevant heavy metal ions, such as copper or zinc ions, can stimulate this pathway, triggering phosphorylation and nuclear export of FoxO transcription factors. The present study aims at investigating the effect of arsenite on FoxO transcription factors and the role of PI3K/Akt signaling therein. Exposure of HaCaT human keratinocytes to arsenite resulted in a distinct decrease of glutathione levels only at cytotoxic concentrations. In contrast, a strong phosphorylation of FoxO1a/FoxO3a and Akt was observed at subcytotoxic concentrations of arsenite in HaCaT human keratinocytes. A time- and concentration-dependent increase in phosphorylation of FoxO1a and FoxO3a at sites known to be phosphorylated by Akt as well as phosphorylation of Akt at Ser-473 was detected. These phosphorylations were blunted in the presence of wortmannin, pointing to the involvement of PI3K.

  8. Combining metal oxide affinity chromatography (MOAC and selective mass spectrometry for robust identification of in vivo protein phosphorylation sites

    Directory of Open Access Journals (Sweden)

    Weckwerth Wolfram

    2005-11-01

    Full Text Available Abstract Background Protein phosphorylation is accepted as a major regulatory pathway in plants. More than 1000 protein kinases are predicted in the Arabidopsis proteome, however, only a few studies look systematically for in vivo protein phosphorylation sites. Owing to the low stoichiometry and low abundance of phosphorylated proteins, phosphorylation site identification using mass spectrometry imposes difficulties. Moreover, the often observed poor quality of mass spectra derived from phosphopeptides results frequently in uncertain database hits. Thus, several lines of evidence have to be combined for a precise phosphorylation site identification strategy. Results Here, a strategy is presented that combines enrichment of phosphoproteins using a technique termed metaloxide affinity chromatography (MOAC and selective ion trap mass spectrometry. The complete approach involves (i enrichment of proteins with low phosphorylation stoichiometry out of complex mixtures using MOAC, (ii gel separation and detection of phosphorylation using specific fluorescence staining (confirmation of enrichment, (iii identification of phosphoprotein candidates out of the SDS-PAGE using liquid chromatography coupled to mass spectrometry, and (iv identification of phosphorylation sites of these enriched proteins using automatic detection of H3PO4 neutral loss peaks and data-dependent MS3-fragmentation of the corresponding MS2-fragment. The utility of this approach is demonstrated by the identification of phosphorylation sites in Arabidopsis thaliana seed proteins. Regulatory importance of the identified sites is indicated by conservation of the detected sites in gene families such as ribosomal proteins and sterol dehydrogenases. To demonstrate further the wide applicability of MOAC, phosphoproteins were enriched from Chlamydomonas reinhardtii cell cultures. Conclusion A novel phosphoprotein enrichment procedure MOAC was applied to seed proteins of A. thaliana and to

  9. The hinge region of chicken annexin I contains no site for tyrosine phosphorylation.

    Science.gov (United States)

    Sidis, Y; Horseman, N D

    1993-08-30

    Annexin I (AnxI) is a calcium-dependent membrane binding protein which has been implicated in various physiological activities. The region of the chicken anxI cDNA encoding the first 130 amino terminal residues was cloned by reverse transcription PCR in order to determine the relationship of its variable amino-terminal regulatory region with other known annexins. This nucleotide sequence shows 86% identity with pigeon AnxI isoforms, and 57% with its human homolog. The protein encoded by the chicken anxI cDNA lacks the canonical epidermal growth factor receptor/kinase phosphorylation site, which is present in AnxI of other species. In contrast, the putative protein kinase C phosphorylation site of the amino-terminus is present in the chicken AnxI. Whereas the pigeon genome contains two anxI genes, genomic Southern analysis shows that in the chicken AnxI is encoded by only a single gene. These data suggest that AnxI has undergone significant sequence variation in the avians, and clarifies the relationships of the avian anxI genes with their ancestral homologs.

  10. The Akt switch model: Is location sufficient?

    Science.gov (United States)

    Gray, Catheryn W; Coster, Adelle C F

    2016-06-01

    Akt/PKB is a biochemical regulator that functions as an important cross-talk node between several signalling pathways in the mammalian cell. In particular, Akt is a key mediator of glucose transport in response to insulin. The phosphorylation (activation) of only a small percentage of the Akt pool of insulin-sensitive cells results in maximal translocation of glucose transporter 4 (GLUT4) to the plasma membrane (PM). This enables the diffusion of glucose into the cell. The dysregulation of Akt signalling is associated with the development of diabetes, cancer and cardiovascular disease. Akt is synthesised in the cytoplasm in the inactive state. Under the influence of insulin, it moves to the PM, where it is phosphorylated to form pAkt. Although phosphorylation occurs only at the PM, pAkt is found in many cellular locations, including the PM, the cytoplasm, and the nucleus. Indeed, the spatial distribution of pAkt within the cell appears to be an important determinant of downstream regulation. Here we present a simple, linear, four-compartment ordinary differential equation (ODE) model of Akt activation that tracks both the biochemical state and the physical location of Akt. This model embodies the main features of the activation of this important cross-talk node and is consistent with the experimental data. In particular, it allows different downstream signalling motifs without invoking separate feedback pathways. Moreover, the model is computationally tractable, readily analysed, and elucidates some of the apparent anomalies in insulin signalling via Akt. PMID:26992575

  11. Assigning Quantitative Function to Post-Translational Modifications Reveals Multiple Sites of Phosphorylation That Tune Yeast Pheromone Signaling Output

    Energy Technology Data Exchange (ETDEWEB)

    Pincus, David; Ryan, Christopher J.; Smith, Richard D.; Brent, Roger; Resnekov, Orna; Hakimi, Mohamed Ali

    2013-03-12

    Cell signaling systems transmit information by post-­translationally modifying signaling proteins, often via phosphorylation. While thousands of sites of phosphorylation have been identified in proteomic studies, the vast majority of sites have no known function. Assigning functional roles to the catalog of uncharacterized phosphorylation sites is a key research challenge. Here we present a general approach to address this challenge and apply it to a prototypical signaling pathway, the pheromone response pathway in Saccharomyces cerevisiae. The pheromone pathway includes a mitogen activated protein kinase (MAPK) cascade activated by a G-­protein coupled receptor (GPCR). We used mass spectrometry-based proteomics to identify sites whose phosphorylation changed when the system was active, and evolutionary conservation to assign priority to a list of candidate MAPK regulatory sites. We made targeted alterations in those sites, and measured the effects of the mutations on pheromone pathway output in single cells. Our work identified six new sites that quantitatively tuned system output. We developed simple computational models to find system architectures that recapitulated the quantitative phenotypes of the mutants. Our results identify a number of regulated phosphorylation events that contribute to adjust the input-­output relationship of this model eukaryotic signaling system. We believe this combined approach constitutes a general means not only to reveal modification sites required to turn a pathway on and off, but also those required for more subtle quantitative effects that tune pathway output. Our results further suggest that relatively small quantitative influences from individual regulatory phosphorylation events endow signaling systems with plasticity that evolution may exploit to quantitatively tailor signaling outcomes.

  12. Cellular stress-induced up-regulation of FMRP promotes cell survival by modulating PI3K-Akt phosphorylation cascades

    Directory of Open Access Journals (Sweden)

    Wells David

    2011-02-01

    Full Text Available Abstract Background Fragile X syndrome (FXS, the most commonly inherited mental retardation and single gene cause of autistic spectrum disorder, occurs when the Fmr1 gene is mutated. The product of Fmr1, fragile X linked mental retardation protein (FMRP is widely expressed in HeLa cells, however the roles of FMRP within HeLa cells were not elucidated, yet. Interacting with a diverse range of mRNAs related to cellular survival regulatory signals, understanding the functions of FMRP in cellular context would provide better insights into the role of this interesting protein in FXS. Using HeLa cells treated with etoposide as a model, we tried to determine whether FMRP could play a role in cell survival. Methods Apoptotic cell death was induced by etoposide treatment on Hela cells. After we transiently modulated FMRP expression (silencing or enhancing by using molecular biotechnological methods such as small hairpin RNA virus-induced knock down and overexpression using transfection with FMRP expression vectors, cellular viability was measured using propidium iodide staining, TUNEL staining, and FACS analysis along with the level of activation of PI3K-Akt pathway by Western blot. Expression level of FMRP and apoptotic regulator BcL-xL was analyzed by Western blot, RT-PCR and immunocytochemistry. Results An increased FMRP expression was measured in etoposide-treated HeLa cells, which was induced by PI3K-Akt activation. Without FMRP expression, cellular defence mechanism via PI3K-Akt-Bcl-xL was weakened and resulted in an augmented cell death by etoposide. In addition, FMRP over-expression lead to the activation of PI3K-Akt signalling pathway as well as increased FMRP and BcL-xL expression, which culminates with the increased cell survival in etoposide-treated HeLa cells. Conclusions Taken together, these results suggest that FMRP expression is an essential part of cellular survival mechanisms through the modulation of PI3K, Akt, and Bcl-xL signal

  13. Protein kinase B/Akt1 inhibits autophagy by down-regulating UVRAG expression

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Wonseok; Ju, Ji-hyun; Lee, Kyung-min; Nam, KeeSoo; Oh, Sunhwa [Department of Life Science, College of Natural Science, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Shin, Incheol, E-mail: incheol@hanyang.ac.kr [Department of Life Science, College of Natural Science, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

    2013-02-01

    Autophagy, or autophagocytosis, is a selective intracellular degradative process involving the cell's own lysosomal apparatus. An essential component in cell development, homeostasis, repair and resistance to stress, autophagy may result in either cell death or survival. The targeted region of the cell is sequestered within a membrane structure, the autophagosome, for regulation of the catabolic process. A key factor in both autophagosome formation and autophagosome maturation is a protein encoded by the ultraviolet irradiation resistance-associated gene (UVRAG). Conversely, the serine/threonine-specific protein kinase B (PKB, also known as Akt), which regulates survival in various cancers, inhibits autophagy through mTOR activation. We found that Akt1 may also directly inhibit autophagy by down-regulating UVRAG both in a 293T transient transfection system and breast cancer cells stably expressing Akt1. The UVRAG with mutations at putative Akt1-phosphorylation sites were still inhibited by Akt1, and dominant-negative Akt1 also inhibited UVRAG expression, suggesting that Akt1 down-regulates UVRAG by a kinase activity-independent mechanism. We showed that Akt1 overexpression in MDA-MB-231 breast cancer cells down-regulated UVRAG transcription. Cells over-expressing Akt1 were more resistant than control cells to ultraviolet light-induced autophagy and exhibited the associated reduction in cell viability. Levels of the autophagosome indicator protein LC3B-II and mRFP-GFP-LC3 were reduced in cells that over-expressing Akt1. Inhibiting Akt1 by siRNA or reintroducing UVRAG gene rescued the level of LC3B-II in UV-irradiation. Altogether, these data suggest that Akt1 may inhibit autophagy by decreasing UVRAG expression, which also sensitizes cancer cells to UV irradiation.

  14. β-carboline compounds, including harmine, inhibit DYRK1A and tau phosphorylation at multiple Alzheimer's disease-related sites.

    Directory of Open Access Journals (Sweden)

    Danielle Frost

    Full Text Available Harmine, a β-carboline alkaloid, is a high affinity inhibitor of the dual specificity tyrosine phosphorylation regulated kinase 1A (DYRK1A protein. The DYRK1A gene is located within the Down Syndrome Critical Region (DSCR on chromosome 21. We and others have implicated DYRK1A in the phosphorylation of tau protein on multiple sites associated with tau pathology in Down Syndrome and in Alzheimer's disease (AD. Pharmacological inhibition of this kinase may provide an opportunity to intervene therapeutically to alter the onset or progression of tau pathology in AD. Here we test the ability of harmine, and numerous additional β-carboline compounds, to inhibit the DYRK1A dependent phosphorylation of tau protein on serine 396, serine 262/serine 356 (12E8 epitope, and threonine 231 in cell culture assays and in vitro phosphorylation assays. Results demonstrate that the β-carboline compounds (1 potently reduce the expression of all three phosphorylated forms of tau protein, and (2 inhibit the DYRK1A catalyzed direct phosphorylation of tau protein on serine 396. By assaying several β-carboline compounds, we define certain chemical groups that modulate the affinity of this class of compounds for inhibition of tau phosphorylation.

  15. Phosphoproteomic analysis reveals major default phosphorylation sites outside long intrinsically disordered regions of Arabidopsis plasma membrane proteins

    Directory of Open Access Journals (Sweden)

    Nespoulous Claude

    2012-10-01

    Full Text Available Abstract Background Genome-wide statistics established that long intrinsically disordered regions (over 30 residues are predicted in a large part of proteins in all eukaryotes, with a higher ratio in trans-membrane proteins. At functional level, such unstructured and flexible regions were suggested for years to favour phosphorylation events. In plants, despite increasing evidence of the regulation of transport and signalling processes by phosphorylation events, only few data are available without specific information regarding plasma membrane proteins, especially at proteome scale. Results Using a dedicated phosphoproteomic workflow, 75 novel and unambiguous phosphorylation sites were identified in Arabidopsis plasma membrane. Bioinformatics analysis showed that this new dataset concerned mostly integral proteins involved in key functions of the plasma membrane (such as transport and signal transduction, including protein phosphorylation. It thus expanded by 15% the directory of phosphosites previously characterized in signalling and transport proteins. Unexpectedly, 66% of phosphorylation sites were predicted to be located outside long intrinsically disordered regions. This result was further corroborated by analysis of publicly available data for the plasma membrane. Conclusions The new phosphoproteomics data presented here, with published datasets and functional annotation, suggest a previously unexpected topology of phosphorylation in the plant plasma membrane proteins. The significance of these new insights into the so far overlooked properties of the plant plasma membrane phosphoproteome and the long disordered regions is discussed.

  16. Analysis of tyrosine phosphorylation sites in signaling molecules by a phosphotyrosine-specific immonium ion scanning method

    DEFF Research Database (Denmark)

    Steen, Hanno; Pandey, Akhilesh; Andersen, Jens S;

    2002-01-01

    Signal transduction pathways involve cascades of events, such as formation of second messengers and protein complexes that alter the activities of proteins. This can ultimately lead to changes in gene expression in response to the stimuli. Reversible phosphorylation of proteins is an important me...... mechanism for activating or inhibiting enzymes and for the assembly of multiprotein complexes. Here, we describe a mass spectrometry-based phosphotyrosine-specific immonium ion scanning (PSI scanning) method for selective detection of tyrosine-phosphorylated peptides. Once the tyrosine......-phosphorylated peptides are identified, they can be directly sequenced in the same experiment to localize the phosphorylation site. We provide protocols for isolation and preparation of samples for analysis, and detailed instructions for operation of a quadrupole time-of-flight (TOF) mass spectrometer for this method...

  17. DSePA Antagonizes High Glucose-Induced Neurotoxicity: Evidences for DNA Damage-Mediated p53 Phosphorylation and MAPKs and AKT Pathways.

    Science.gov (United States)

    Wang, Kun; Fu, Xiao-Yan; Fu, Xiao-Ting; Hou, Ya-Jun; Fang, Jie; Zhang, Shuai; Yang, Ming-Feng; Li, Da-Wei; Mao, Lei-Lei; Sun, Jing-Yi; Yuan, Hui; Yang, Xiao-Yi; Fan, Cun-Dong; Zhang, Zong-Yong; Sun, Bao-Liang

    2016-09-01

    Hyperglycemia as the major hallmark of diabetic neuropathy severely limited its therapeutic efficiency. Evidences have revealed that selenium (Se) as an essential trace element could effectively reduce the risk of neurological diseases. In the present study, 3,3'-diselenodipropionic acid (DSePA), a derivative of selenocystine, was employed to investigate its protective effect against high glucose-induced neurotoxicity in PC12 cells and evaluate the underlying mechanism. The results suggested that high glucose showed significant cytotoxicity through launching mitochondria-mediated apoptosis in PC12 cells, accompanied by poly (ADP-ribose) polymerase (PARP) cleavage, caspase activation, and mitochondrial dysfunction. Moreover, high glucose also triggered DNA damage and dysregulation of MAPKs and AKT pathways through reactive oxygen species (ROS) overproduction. p53 RNA interference partially suppressed high glucose-induced cytotoxicity and apoptosis, indicating the role of p53 in high glucose-induced signal. However, DSePA pretreatment effectively attenuated high glucose-induced cytotoxicity, inhibited the mitochondrial dysfunction through regulation of Bcl-2 family, and ultimately reversed high glucose-induced apoptotic cell death in PC12 cells. Attenuation of caspase activation, PARP cleavage, DNA damage, and ROS accumulation all confirmed its protective effects. Moreover, DSePA markedly alleviated the dysregulation of AKT and MAPKs pathways induced by high glucose. Our findings revealed that the strategy of using DSePA to antagonize high glucose-induced neurotoxicity may be a highly effective strategy in combating high glucose-mediated neurological diseases. PMID:26232068

  18. B Cell Receptor Activation Predominantly Regulates AKT-mTORC1/2 Substrates Functionally Related to RNA Processing

    Science.gov (United States)

    Mohammad, Dara K.; Ali, Raja H.; Turunen, Janne J.; Nore, Beston F.; Smith, C. I. Edvard

    2016-01-01

    Protein kinase B (AKT) phosphorylates numerous substrates on the consensus motif RXRXXpS/T, a docking site for 14-3-3 interactions. To identify novel AKT-induced phosphorylation events following B cell receptor (BCR) activation, we performed proteomics, biochemical and bioinformatics analyses. Phosphorylated consensus motif-specific antibody enrichment, followed by tandem mass spectrometry, identified 446 proteins, containing 186 novel phosphorylation events. Moreover, we found 85 proteins with up regulated phosphorylation, while in 277 it was down regulated following stimulation. Up regulation was mainly in proteins involved in ribosomal and translational regulation, DNA binding and transcription regulation. Conversely, down regulation was preferentially in RNA binding, mRNA splicing and mRNP export proteins. Immunoblotting of two identified RNA regulatory proteins, RBM25 and MEF-2D, confirmed the proteomics data. Consistent with these findings, the AKT-inhibitor (MK-2206) dramatically reduced, while the mTORC-inhibitor PP242 totally blocked phosphorylation on the RXRXXpS/T motif. This demonstrates that this motif, previously suggested as an AKT target sequence, also is a substrate for mTORC1/2. Proteins with PDZ, PH and/or SH3 domains contained the consensus motif, whereas in those with an HMG-box, H15 domains and/or NF-X1-zinc-fingers, the motif was absent. Proteins carrying the consensus motif were found in all eukaryotic clades indicating that they regulate a phylogenetically conserved set of proteins. PMID:27487157

  19. The active site of oxidative phosphorylation and the origin of hyperhomocysteinemia in aging and dementia.

    Science.gov (United States)

    McCully, Kilmer S

    2015-01-01

    The active site of oxidative phosphorylation and adenosine triphosphate (ATP) synthesis in mitochondria is proposed to consist of two molecules of thioretinamide bound to cobalamin, forming thioretinaco, complexed with ozone, oxygen, nicotinamide adenine dinucleotide. and inorganic phosphate, TR2CoO3O2NAD(+)H2PO4(-). Reduction of the pyridinium nitrogen of the nicotinamide group by an electron from electron transport complexes initiates polymerization of phosphate with adenosine diphosphate, yielding nicotinamide riboside and ATP bound to thioretinaco ozonide oxygen. A second electron reduces oxygen to hydroperoxyl radical, releasing ATP from the active site. A proton gradient is created within F1F0 ATPase complexes of mitochondria by reaction of protons with reduced nicotinamide riboside and with hydroperoxyl radical, yielding reduced nicotinamide riboside and hydroperoxide. The hyperhomocysteinemia of aging and dementia is attributed to decreased synthesis of adenosyl methionine by thioretinaco ozonide and ATP, causing decreased allosteric activation of cystathionine synthase and decreased allosteric inhibition of methylenetetrahydrofolate reductase and resulting in dysregulation of methionine metabolism. PMID:25887881

  20. Identification and characterization of columbid annexin Icp37. Insights into the evolution of annexin I phosphorylation sites.

    Science.gov (United States)

    Haigler, H T; Mangili, J A; Gao, Y; Jones, J; Horseman, N D

    1992-09-25

    Annexin I (AnxI) contains phosphorylation sites in its "hinge region" that have been implicated in the regulation of cell growth and/or differentiation. A pigeon (Columba livia) isoform of this protein, annexin Icp35 (cp35), has a very similar amino acid sequence overall but an unrelated sequence that lacks phosphorylation sites in the hinge region. We now report the identification and characterization of annexin Icp37 (cp37) from pigeon. Genomic cloning and Southern blot analysis demonstrated that cp37 and cp35 were encoded by separated genes. Prolactin induced the expression of cp35 mRNA but not cp37. The amino acid sequence of cp37 was deduced from a cDNA clone and found to share 93 and 75% sequence identity with cp35 and human AnxI, respectively. The amino acid sequence of cp37 bore similarities to both AnxI and cp35 in the critical hinge region. Like AnxI, cp37 contained consensus phosphorylation sites in its amino acid sequence and was phosphorylated on tyrosine by the EGF receptor/kinase and on serine by protein kinase C in vitro. Despite the functional similarities between cp37 and AnxI, the nucleotide sequence that encoded the hinge region of cp37 was very similar to the analogous region of cp35, but different from that of AnxI. We propose that certain features shared by cp37 and AnxI are the products of convergent evolution. The fact that evolution independently selected for two annexin I-like genes (cp37 and anxI) encoding analogous phosphorylation sites is strong evidence that phosphorylation is important for the regulation of the biological activity of these proteins.

  1. High LET - induced H2AX phosphorylation at sites of DNA double strand breaks

    Science.gov (United States)

    Desai, N.; Cucinotta, F.; Wu, H.

    Within cell nuclei, traversing charged heavy ion particles lead to the accumulation of proteins related to DNA lesions and repair along the ion trajectories. Irradiation using a standard geometric setup with the beam path perpendicular to the cell monolayer generates discrete foci of several proteins known to localize at sites of DNA double strand breaks (DSBs). One such molecule is the histone protein H2AX (gamma-H2AX), which gets rapidly phosphorylated in response to ionizing radiation. Here we present data obtained with a modified irradiation geometry characterized by a beam path parallel to a monolayer of human fibroblast cells. This new irradiation geometry leads to the formation of gamma-H2AX aggregates in the shape of streaks stretching over several micrometers in the x/y plane, thus enabling the analysis of the fluorescence distributions along the particle trajectories. Qualitative analysis of these distributions presented insights into the DNA repair kinetics along the primary track structure and visualization of possible chromatin movement. We also present evidence of colocalization of gamma-H2AX with several other proteins in responses to ionizing radiation exposure. Analysis of gamma-H2AX has the potential to provide useful information on human cell responses to high LET radiation after exposure to space-like radiation.

  2. Scanning mutagenesis of the amino acid sequences flanking phosphorylation site 1 of the mitochondrial pyruvate dehydrogenase complex

    Directory of Open Access Journals (Sweden)

    Nagib eAhsan

    2012-07-01

    Full Text Available The mitochondrial pyruvate dehydrogenase complex is regulated by reversible seryl-phosphorylation of the E1α subunit by a dedicated, intrinsic kinase. The phospho-complex is reactivated when dephosphorylated by an intrinsic PP2C-type protein phosphatase. Both the position of the phosphorylated Ser-residue and the sequences of the flanking amino acids are highly conserved. We have used the synthetic peptide-based kinase client assay plus recombinant pyruvate dehydrogenase E1α and E1α-kinase to perform scanning mutagenesis of the residues flanking the site of phosphorylation. Consistent with the results from phylogenetic analysis of the flanking sequences, the direct peptide-based kinase assays tolerated very few changes. Even conservative changes such as Leu, Ile, or Val for Met, or Glu for Asp, gave very marked reductions in phosphorylation. Overall the results indicate that regulation of the mitochondrial pyruvate dehydrogenase complex by reversible phosphorylation is an extreme example of multiple, interdependent instances of co-evolution.

  3. Reduction of Ambiguity in Phosphorylation-site Localization in Large-scale Phosphopeptide Profiling by Data Filter using Unique Mass Class Information

    International Nuclear Information System (INIS)

    The rapid development of shotgun proteomics is paving the way for extensive proteome profiling, while providing extensive information on various post translational modifications (PTMs) that occur to a proteome of interest. For example, the current phosphoproteomic methods can yield more than 10,000 phosphopeptides identified from a proteome sample. Despite these developments, it remains a challenging issue to pinpoint the true phosphorylation sites, especially when multiple sites are possible for phosphorylation in the peptides. We developed the Phospho-UMC filter, which is a simple method of localizing the site of phosphorylation using unique mass classes (UMCs) information to differentiate phosphopeptides with different phosphorylation sites and increase the confidence in phosphorylation site localization. The method was applied to large scale phosphopeptide profiling data and was demonstrated to be effective in the reducing ambiguity associated with the tandem mass spectrometric data analysis of phosphopeptides

  4. Reduction of Ambiguity in Phosphorylation-site Localization in Large-scale Phosphopeptide Profiling by Data Filter using Unique Mass Class Information

    Energy Technology Data Exchange (ETDEWEB)

    Madar, Inamul Hasan; Back, Seunghoon; Mun, Donggi; Kim, Hokeun; Lee, Sangwon [Korea Univ., Seoul (Korea, Republic of); Jung, Jae Hun; Kim, Kwang Pyo [Kyung Hee Univ., Yongin (Korea, Republic of)

    2014-03-15

    The rapid development of shotgun proteomics is paving the way for extensive proteome profiling, while providing extensive information on various post translational modifications (PTMs) that occur to a proteome of interest. For example, the current phosphoproteomic methods can yield more than 10,000 phosphopeptides identified from a proteome sample. Despite these developments, it remains a challenging issue to pinpoint the true phosphorylation sites, especially when multiple sites are possible for phosphorylation in the peptides. We developed the Phospho-UMC filter, which is a simple method of localizing the site of phosphorylation using unique mass classes (UMCs) information to differentiate phosphopeptides with different phosphorylation sites and increase the confidence in phosphorylation site localization. The method was applied to large scale phosphopeptide profiling data and was demonstrated to be effective in the reducing ambiguity associated with the tandem mass spectrometric data analysis of phosphopeptides.

  5. Identification of a novel phosphorylation site in adipose triglyceride lipase as a regulator of lipid droplet localization.

    Science.gov (United States)

    Xie, Xitao; Langlais, Paul; Zhang, Xiaodong; Heckmann, Bradlee L; Saarinen, Alicia M; Mandarino, Lawrence J; Liu, Jun

    2014-06-15

    Adipose triglyceride lipase (ATGL), the rate-limiting enzyme for triacylglycerol (TG) hydrolysis, has long been known to be a phosphoprotein. However, the potential phosphorylation events that are involved in the regulation of ATGL function remain incompletely defined. Here, using a combinatorial proteomics approach, we obtained evidence that at least eight different sites of ATGL can be phosphorylated in adipocytes. Among them, Thr³⁷² resides within the hydrophobic region known to mediate lipid droplet (LD) targeting. Although it had no impact on the TG hydrolase activity, substitution of phosphorylation-mimic Asp for Thr³⁷² eliminated LD localization and LD-degrading capacity of ATGL expressed in HeLa cells. In contrast, mutation of Thr³⁷² to Ala gave a protein that bound LDs and functioned the same as the wild-type protein. In nonstimulated adipocytes, the Asp mutation led to decreased LD association and basal lipolytic activity of ATGL, whereas the Ala mutation produced opposite effects. Moreover, the LD translocation of ATGL upon β-adrenergic stimulation was also compromised by the Asp mutation. In accord with these findings, the Ala mutation promoted and the Asp mutation attenuated the capacity of ATGL to mediate lipolysis in adipocytes under both basal and stimulated conditions. Collectively, these studies identified Thr³⁷² as a novel phosphorylation site that may play a critical role in determining subcellular distribution as well as lipolytic action of ATGL.

  6. Identification of a novel phosphorylation site in adipose triglyceride lipase as a regulator of lipid droplet localization.

    Science.gov (United States)

    Xie, Xitao; Langlais, Paul; Zhang, Xiaodong; Heckmann, Bradlee L; Saarinen, Alicia M; Mandarino, Lawrence J; Liu, Jun

    2014-06-15

    Adipose triglyceride lipase (ATGL), the rate-limiting enzyme for triacylglycerol (TG) hydrolysis, has long been known to be a phosphoprotein. However, the potential phosphorylation events that are involved in the regulation of ATGL function remain incompletely defined. Here, using a combinatorial proteomics approach, we obtained evidence that at least eight different sites of ATGL can be phosphorylated in adipocytes. Among them, Thr³⁷² resides within the hydrophobic region known to mediate lipid droplet (LD) targeting. Although it had no impact on the TG hydrolase activity, substitution of phosphorylation-mimic Asp for Thr³⁷² eliminated LD localization and LD-degrading capacity of ATGL expressed in HeLa cells. In contrast, mutation of Thr³⁷² to Ala gave a protein that bound LDs and functioned the same as the wild-type protein. In nonstimulated adipocytes, the Asp mutation led to decreased LD association and basal lipolytic activity of ATGL, whereas the Ala mutation produced opposite effects. Moreover, the LD translocation of ATGL upon β-adrenergic stimulation was also compromised by the Asp mutation. In accord with these findings, the Ala mutation promoted and the Asp mutation attenuated the capacity of ATGL to mediate lipolysis in adipocytes under both basal and stimulated conditions. Collectively, these studies identified Thr³⁷² as a novel phosphorylation site that may play a critical role in determining subcellular distribution as well as lipolytic action of ATGL. PMID:24801391

  7. In silico determination of intracellular glycosylation and phosphorylation sites in human selectins: Implications for biological function

    DEFF Research Database (Denmark)

    Ahmad, I.; Hoessli, D.C.; Gupta, Ramneek;

    2007-01-01

    of other interacting proteins. Bioinformatics tools are therefore helpful to predict protein multifunctionality through the identification of serine and threonine residues wherein the hydroxyl group is likely to become modified by phosphorylation or glycosylation. Moreover, serines and threonines...

  8. 磷酸化Akt和ERK在大鼠腹主动脉瘤中的表达*%Expressions of Akt and ERK Phosphorylation in Rat Model of Abdominal Aortic Aneurysm

    Institute of Scientific and Technical Information of China (English)

    郑红波; 周洪莲; 武亚丽; 周丹

    2013-01-01

      目的观察磷酸化Akt(p-Akt)和磷酸化ERK(p-ERK)在大鼠腹主动脉瘤模型中的表达情况,探讨腹主动脉瘤的发病机制。方法构建大鼠腹主动脉瘤模型并测量腹主动脉直径,计算直径扩张度;HE染色观察腹主动脉的病理改变;免疫组织化学技术和Western blot技术检测腹主动脉组织中p-Akt和p-ERK的相对表达量。结果腹主动脉瘤组主动脉扩张度(3.689±0.443)明显高于生理盐水组(1.175±0.159)和正常组(1),差异有统计学意义(P<0.05);HE染色显示,腹主动脉瘤组主动脉结构紊乱并有炎症细胞浸润;免疫组化结果和Western blot结果均显示p-Akt在腹主动脉瘤组中的表达明显高于生理盐水组和正常组(P<0.05);p-ERK表达差异不明显(P>0.05)。在腹主动脉瘤组中,p-Akt表达水平与主动脉扩张度呈正相关,p-ERK表达水平与主动脉扩张度无明显相关性。结论 PI3K/Akt信号通路可能参与腹主动脉瘤的发生与发展。%Objective To observe the expressions of Akt and ERK phosphorylation in abdominal aortic aneurysm of rat model, and explore the pathogenesis of abdominal aortic aneurysm. Methods The rat model of abdominal aortic aneu-rysm was established. The diameter of abdominal aorta was measured and the extended rate of the aorta was calculated. HE staining was used to observe the change of pathology. Immunohistochemistry and Western blot methods were used to detect the expressions of Akt and ERK phosphorylation in the level of protein. Results The dilation of aorta was significantly high-er in abdominal aortic aneurysm group than that of saline group and normal group (P0.05). Conclusion PI3K/Akt signaling pathway may be involved in the development of abdominal aortic aneurysm.

  9. P70S6 Kinase Phosphorylation: A New Site to Assess Pharmacodynamy of Sirolimus

    Directory of Open Access Journals (Sweden)

    Jun-Yu Wang

    2015-01-01

    Full Text Available Background: The phosphorylation of p70S6 kinase (p70S6K represents an important target for sensitive detection on pharmacodynamic effects of sirolimus, but the methods of assessing p70S6K phosphorylation are still unclear. The aim of this study was to investigate p70S6K phosphorylation located down-stream of the mammalian target of rapamycin (mTOR pathway in peripheral blood mononuclear cells (PBMCs of liver transplant patients through different methods. Methods: Seventy-five liver transplant recipients from Beijing Chaoyang Hospital of the Capital Medical University were analyzed in this study. Patients were divided into three groups, patient treated with sirolimus (n = 22, patient treated with tacrolimus (n = 30, patient treated with cyclosporine (n = 23. The p70S6K phosphorylation of PBMCs in patients and healthy control (HC, n = 12 were analyzed by phospho-flow cytometry and Western blotting. A correlation analysis of data from phospho-flow cytometry and Western blotting was performed. Intra-assay variability of p70S6K phosphorylation in HC and different patients were measured. Results: Intra-assay variability of p70S6K phosphorylation in phospho-flow cytometry was from 4.1% to 8.4% and in Western blotting was from 8.2% to 18%. The p70S6K phosphorylation in patients receiving a sirolimus (19.5 ± 7.7 was significantly lower than in HC (50.1 ± 11.3, P < 0.001, tacrolimus (37.7 ± 15.7, P < 0.001 or cyclosporine treated patients (41.7 ± 11.7, P < 0.001. The p70S6K phosphorylation in HC (50.1 ± 11.3 was significantly higher than in tacrolimus (37.7 ± 15.7, P < 0.01 or cyclosporine-treated patients (41.7 ± 11.7, P < 0.01. There was correlation between data from phospho-flow cytometry and data from Western blotting (r = 0.88, P < 0.001. Conclusions: The degree of mTOR inhibition by assessing p70S6K phosphorylation was established by phospho-flow cytometry and Western blotting. Assessment of p70S6K phosphorylation may play an adjunct role to

  10. P70S6 Kinase Phosphorylation: A New Site to Assess Pharmacodynamy of Sirolimus

    Institute of Scientific and Technical Information of China (English)

    Jun-Yu Wang; Hua Fan

    2015-01-01

    Background:The phosphorylation ofp70S6 kinase (p70S6K) represents an important target for sensitive detection on pharmacodynamic effects of sirolimus,but the methods of assessing p70S6K phosphorylation are still unclear.The aim of this study was to investigate p70S6K phosphorylation located down-stream of the mammalian target ofrapamycin (mTOR) pathway in peripheral blood mononuclear cells (PBMCs) of liver transplant patients through different methods.Methods:Seventy-five liver transplant recipients from Beijing Chaoyang Hospital of the Capital Medical University were analyzed in this study.Patients were divided into three groups,patient treated with sirolimus (n =22),patient treated with tacrolimus (n =30),patient treated with cyclosporine (n =23).The p70S6K phosphorylation of PBMCs in patients and healthy control (HC,n =12) were analyzed by phospho-flow cytometry and Western blotting.A correlation analysis of data from phospho-flow cytometry and Western blotting was performed.Intra-assay variability of p70S6K phosphorylation in HC and different patients were measured.Results:Intra-assay variability ofp70S6K phosphorylation in phospho-flow cytometry was from 4.1% to 8.4% and in Western blotting was from 8.2% to 18%.The p70S6K phosphorylation in patients receiving a sirolimus (19.5 ± 7.7) was significantly lower than in HC (50.1 ± 11.3,P < 0.001),tacrolimus (37.7 ± 15.7,P < 0.001) or cyclosporine treated patients (41.7 ± 11.7,P < 0.001).The p70S6K phosphorylation in HC (50.1± 11.3) was significantly higher than in tacrolimus (37.7 ± 15.7,P < 0.01) or cyclosporine-treated patients (41.7 ± 11.7,P < 0.01).There was correlation between data from phospho-flow cytometry and data from Westem blotting (r =0.88,P < 0.001).Conclusions:The degree of mTOR inhibition by assessing p70S6K phosphorylation was established by phospho-flow cytometry and Westem blotting.Assessment of p70S6K phosphorylation may play an adjunct role to on pharmacodynamically

  11. Cyclin-dependent kinase 2 phosphorylates s/t-p sites in the hepadnavirus core protein C-terminal domain and is incorporated into viral capsids.

    Science.gov (United States)

    Ludgate, Laurie; Ning, Xiaojun; Nguyen, David H; Adams, Christina; Mentzer, Laura; Hu, Jianming

    2012-11-01

    Phosphorylation of the hepadnavirus core protein C-terminal domain (CTD) is important for viral RNA packaging, reverse transcription, and subcellular localization. Hepadnavirus capsids also package a cellular kinase. The identity of the host kinase that phosphorylates the core CTD or gets packaged remains to be resolved. In particular, both the human hepatitis B virus (HBV) and duck hepatitis B virus (DHBV) core CTDs harbor several conserved serine/threonine-proline (S/T-P) sites whose phosphorylation state is known to regulate CTD functions. We report here that the endogenous kinase in the HBV capsids was blocked by chemical inhibitors of the cyclin-dependent kinases (CDKs), in particular, CDK2 inhibitors. The kinase phosphorylated the HBV CTD at the serine-proline (S-P) sites. Furthermore, we were able to detect CDK2 in purified HBV capsids by immunoblotting. Purified CDK2 phosphorylated the S/T-P sites of the HBV and DHBV CTD in vitro. Inhibitors of CDKs, of CDK2 in particular, decreased both HBV and DHBV CTD phosphorylation in vivo. Moreover, CDK2 inhibitors blocked DHBV CTD phosphorylation, specifically at the S/T-P sites, in a mammalian cell lysate. These results indicate that cellular CDK2 phosphorylates the functionally critical S/T-P sites of the hepadnavirus core CTD and is incorporated into viral capsids.

  12. PD trafficking of potato leaf roll virus movement protein in Arabidopsis depends on site-specific protein phosphorylation

    Directory of Open Access Journals (Sweden)

    Katrin eLink

    2011-06-01

    Full Text Available Many plant viruses encode for specialised movement proteins (MP to facilitate passage of viral material to and through plasmodesmata (PD. To analyse intracellular trafficking of potato leaf roll virus (PLRV movement protein (MP17 we performed GFP fusion experiments with distinct deletion variants of MP17. These studies revealed that the C-terminus of MP17 is essential but not sufficient for PD targeting. Interestingly, fusion of GFP to three C-terminal MP17 deletion variants resulted in the accumulation of GFP in chloroplasts. This indicates that MP17 harbours hidden plastid targeting sequences. Previous studies showed that posttranslational protein phosphorylation influences PD targeting of MP and virus spread. Analysis of MP17-derived phospho-peptides by mass spectrometry revealed four phosphorylated serine residues (S71, S79, S137 and S140. Site-directed mutagenesis of S71/S79 and S137/S140 showed that the C-terminal serine residues S137/S140 are dispensable for PD targeting. However, exchange of S71/S79 to A71/A79 abolished PD targeting of the mutated MP17 protein. To mimic phosphorylation of S71/S79 both amino acids were substituted by aspartic acid. The resulting D71/D79 variant of MP17 was efficiently targeted to PD. Further deletion analysis showed that PD targeting of MP17 is dependent on the C-terminus, phosphorylation of S71 and/or S79 and a N-terminal domain.

  13. Epidermal Growth Factor Stimulates Extracellular-Signal Regulated Kinase Phosphorylation of a Novel Site on Cytoplasmic Dynein Intermediate Chain 2

    Directory of Open Access Journals (Sweden)

    Andrew D. Catling

    2013-02-01

    Full Text Available Extracellular-signal regulated kinase (ERK signaling is required for a multitude of physiological and patho-physiological processes. However, the identities of the proteins that ERK phosphorylates to elicit these responses are incompletely known. Using an affinity purification methodology of general utility, here we identify cytoplasmic dynein intermediate chain 2 (DYNC1I-2, IC-2 as a novel substrate for ERK following epidermal growth factor receptor stimulation of fibroblasts. IC-2 is a subunit of cytoplasmic dynein, a minus-end directed motor protein necessary for transport of diverse cargos along microtubules. Emerging data support the hypothesis that post-translational modification regulates dynein but the signaling mechanisms used are currently unknown. We find that ERK phosphorylates IC-2 on a novel, highly conserved Serine residue proximal to the binding site for the p150Glued subunit of the cargo adapter dynactin. Surprisingly, neither constitutive phosphorylation nor a phosphomimetic substitution of this Serine influences binding of p150Glued to IC-2. These data suggest that ERK phosphorylation of IC-2 regulates dynein function through mechanisms other than its interaction with dynactin.

  14. Gq-mediated Akt translocation to the membrane: a novel PIP3-independent mechanism in platelets.

    Science.gov (United States)

    Badolia, Rachit; Manne, Bhanu Kanth; Dangelmaier, Carol; Chernoff, Jonathan; Kunapuli, Satya P

    2015-01-01

    Akt is an important signaling molecule regulating platelet aggregation. Akt is phosphorylated after translocation to the membrane through Gi signaling pathways by a phosphatidylinositol-3,4,5-trisphosphate (PIP3)-dependent mechanism. However, Akt is more robustly phosphorylated by thrombin compared with adenosine 5'-diphosphate in platelets. This study investigated the mechanisms of Akt translocation as a possible explanation for this difference. Stimulation of washed human platelets with protease-activated receptor agonists caused translocation of Akt to the membrane rapidly, whereas phosphorylation occurred later. The translocation of Akt was abolished in the presence of a Gq-selective inhibitor or in Gq-deficient murine platelets, indicating that Akt translocation is regulated downstream of Gq pathways. Interestingly, phosphatidylinositol 3-kinase (PI3K) inhibitors or P2Y12 antagonist abolished Akt phosphorylation without affecting Akt translocation to the membrane, suggesting that Akt translocation occurs through a PI3K/PIP3/Gi-independent mechanism. An Akt scaffolding protein, p21-activated kinase (PAK), translocates to the membrane after stimulation with protease-activated receptor agonists in a Gq-dependent manner, with the kinetics of translocation similar to that of Akt. Coimmunoprecipitation studies showed constitutive association of PAK and Akt, suggesting a possible role of PAK in Akt translocation. These results show, for the first time, an important role of the Gq pathway in mediating Akt translocation to the membrane in a novel Gi/PI3K/PIP3-independent mechanism.

  15. Mutation of the SHP-2 binding site in growth hormone (GH) receptor prolongs GH-promoted tyrosyl phosphorylation of GH receptor, JAK2, and STAT5B

    DEFF Research Database (Denmark)

    Stofega, M R; Herrington, J; Billestrup, Nils;

    2000-01-01

    that the SH2 domains of SHP-2 bind directly to tyrosyl phosphorylated GHR from GH-treated cells. Tyrosine-to-phenylalanine mutation of tyrosine 595 of rat GHR greatly diminishes association of the SH2 domains of SHP-2 with GHR, and tyrosine-to-phenylalanine mutation of tyrosine 487 partially reduces...... phosphorylation. Consistent with the effects on STAT5B phosphorylation, tyrosine-to-phenylalanine mutation of tyrosine 595 prolongs the duration of tyrosyl phosphorylation of GHR and JAK2. These data suggest that tyrosine 595 is a major site of interaction of GHR with SHP-2, and that GHR-bound SHP-2 negatively...

  16. Quantitative maps of protein phosphorylation sites across 14 different rat organs and tissues

    DEFF Research Database (Denmark)

    Lundby, Alicia; Secher, Anna; Lage, Kasper;

    2012-01-01

    of individual organs. For skeletal muscle, we find that phosphotyrosines are over-represented, which is mainly due to proteins involved in glycogenolysis and muscle contraction, a finding we validate in human skeletal muscle biopsies. Tyrosine phosphorylation is involved in both skeletal and cardiac muscle...

  17. Novel vasopressin-regulated phosphorylation site of the NaCl co-transporter, NCC

    DEFF Research Database (Denmark)

    Rosenbæk, Lena Lindtoft; Knepper, Mark A; Fenton, Robert A.

    with a novel pS124-NCC antibody demonstrated a band of ~160 kDa in the kidney cortex, but not medulla, which was preabsorbed by a corresponding phosphorylated peptide. Confocal microscopy with segment-specific markers localized pS124-NCC to all DCT cells, with greater abundance in the early DCT. Double...

  18. Identification of the in vitro phosphorylation sites on Gs alpha mediated by pp60c-src.

    Science.gov (United States)

    Moyers, J S; Linder, M E; Shannon, J D; Parsons, S J

    1995-01-15

    Overexpression of pp60c-src in mouse fibroblasts potentiates both agonist-induced signalling through beta-adrenergic receptors and cyclic AMP accumulation in response to cholera toxin [Bushman, Wilson, Luttrell, Moyers and Parsons (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 7462-7466; Moyers, Bouton and Parsons (1993) Mol. Cell. Biol. 13, 2391-2400]. In reconstitution experiments in vitro, phosphorylation of Gs alpha by immune-complexed pp60c-src resulted in enhanced rates of receptor-mediated guanosine 5'-[gamma-thio]triphosphate (GTP[S]) binding and GTP hydrolysis [Hausdorff, Pitcher, Luttrell, Linder, Kurose, Parsons, Caron and Lefkowitz (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 5720-5724]. These results suggest that one mechanism by which pp60c-src affects signalling through the beta-adrenergic receptor is by phosphorylation and functional alteration of the G protein. To elucidate how phosphorylation of Gs alpha might affect its function, we subjected phosphorylated, recombinant Gs alpha to tryptic phosphopeptide analysis. Phosphotryptic peptides were purified by h.p.l.c. and analysed by Edman degradation to determine the cycle numbers at which radiolabelled phosphotyrosine was released. Candidate peptides that contained Tyr residues at the corresponding positions were synthesized, phosphorylated in vitro by pp60c-src, and their migrations in two-dimensional electrophoresis/t.l.c. were compared with those of tryptic phosphopeptides from intact Gs alpha. We report here that Gs alpha is phosphorylated on two residues by pp60c-src, namely, Tyr-37 and Tyr-377. Tyr-37 lies near the site of beta gamma binding in the N-terminus, within a region postulated to modulate GDP dissociation and activation by GTP [Johnson, Dhanasekaran, Gupta, Lowndes, Vaillancourt and Ruoho (1991) J. Cell Biochem. 47, 136-146], while Tyr-377 is located in the extreme C-terminus, within a region of Gs alpha important for receptor interaction [Sullivan, Miller, Masters, Beiderman, Heideman and

  19. LRRK2 Kinase Activity and Biology are Not Uniformly Predicted by its Autophosphorylation and Cellular Phosphorylation Site Status

    Directory of Open Access Journals (Sweden)

    April eReynolds

    2014-06-01

    Full Text Available Missense mutations in the Leucine Rich Repeat protein Kinase 2 (LRRK2 gene are the most common genetic predisposition to develop Parkinson’s disease (PD LRRK2 is a large multi-domain phosphoprotein with a GTPase domain and a serine/threonine protein kinase domain whose activity is implicated in neuronal toxicity; however the precise mechanism is unknown. LRRK2 autophosphorylates on several serine/threonine residues across the enzyme and is found constitutively phosphorylated on Ser910, Ser935, Ser955 and Ser973, which are proposed to be regulated by upstream kinases. Here we investigate the phosphoregulation at these sites by analyzing the effects of disease-associated mutations Arg1441Cys, Arg1441Gly, Ala1442Pro, Tyr1699Cys, Ile2012Thr, Gly2019Ser, and Ile2020Thr. We also studied alanine substitutions of phosphosite serines 910, 935, 955 and 973 and specific LRRK2 inhibition on autophosphorylation of LRRK2 Ser1292, Thr1491, Thr2483 and phosphorylation at the cellular sites. We found that mutants in the Roc-COR domains, including Arg1441Cys, Arg1441His, Ala1442Pro and Tyr1699Cys, can positively enhance LRRK2 kinase activity while concomitantly inducing the dephosphorylation of the cellular sites. Mutation of the cellular sites individually did not affect LRRK2 intrinsic kinase activity; however, Ser910/935/955/973Ala mutations trended toward increased kinase activity of LRRK2. Increased cAMP levels did not lead to increased LRRK2 cellular site phosphorylation, 14-3-3 binding or kinase activity. In cells, inhibition of LRRK2 kinase activity leads to dephosphorylation of Ser1292 by Calyculin A and okadaic acid sensitive phosphatases, while the cellular sites are dephosphorylated by Calyculin A sensitive phosphatases. These findings indicate that comparative analysis of both Ser1292 and Ser910/935/955/973 phosphorylation sites will provide important and distinct measures of LRRK2 kinase and biological activity in vitro and in vivo.

  20. Mutation of androgen receptor N-terminal phosphorylation site Tyr-267 leads to inhibition of nuclear translocation and DNA binding.

    Directory of Open Access Journals (Sweden)

    Mehmet Karaca

    Full Text Available Reactivation of androgen receptor (AR may drive recurrent prostate cancer in castrate patients. Ack1 tyrosine kinase is overexpressed in prostate cancer and promotes castrate resistant xenograft tumor growth and enhances androgen target gene expression and AR recruitment to enhancers. Ack1 phosphorylates AR at Tyr-267 and possibly Tyr-363, both in the N-terminal transactivation domain. In this study, the role of these phosphorylation sites was investigated by characterizing the phosphorylation site mutants in the context of full length and truncated AR lacking the ligand-binding domain. Y267F and Y363F mutants showed decreased transactivation of reporters. Expression of wild type full length and truncated AR in LNCaP cells increased cell proliferation in androgen-depleted conditions and increased colony formation. However, the Y267F mutant of full length and truncated AR was defective in stimulating cell proliferation. The Y363F mutant was less severely affected than the Y267F mutant. The full length AR Y267F mutant was defective in nuclear translocation induced by androgen or Ack1 kinase. The truncated AR was constitutively localized to the nucleus. Chromatin immunoprecipitation analysis showed that it was recruited to the target enhancers without androgen. The truncated Y267F AR mutant did not exhibit constitutive nuclear localization and androgen enhancer binding activity. These results support the concept that phosphorylation of Tyr-267, and to a lesser extent Tyr-363, is required for AR nuclear translocation and recruitment and DNA binding and provide a rationale for development of novel approaches to inhibit AR activity.

  1. Mutation of androgen receptor N-terminal phosphorylation site Tyr-267 leads to inhibition of nuclear translocation and DNA binding.

    Science.gov (United States)

    Karaca, Mehmet; Liu, Yuanbo; Zhang, Zhentao; De Silva, Dinuka; Parker, Joel S; Earp, H Shelton; Whang, Young E

    2015-01-01

    Reactivation of androgen receptor (AR) may drive recurrent prostate cancer in castrate patients. Ack1 tyrosine kinase is overexpressed in prostate cancer and promotes castrate resistant xenograft tumor growth and enhances androgen target gene expression and AR recruitment to enhancers. Ack1 phosphorylates AR at Tyr-267 and possibly Tyr-363, both in the N-terminal transactivation domain. In this study, the role of these phosphorylation sites was investigated by characterizing the phosphorylation site mutants in the context of full length and truncated AR lacking the ligand-binding domain. Y267F and Y363F mutants showed decreased transactivation of reporters. Expression of wild type full length and truncated AR in LNCaP cells increased cell proliferation in androgen-depleted conditions and increased colony formation. However, the Y267F mutant of full length and truncated AR was defective in stimulating cell proliferation. The Y363F mutant was less severely affected than the Y267F mutant. The full length AR Y267F mutant was defective in nuclear translocation induced by androgen or Ack1 kinase. The truncated AR was constitutively localized to the nucleus. Chromatin immunoprecipitation analysis showed that it was recruited to the target enhancers without androgen. The truncated Y267F AR mutant did not exhibit constitutive nuclear localization and androgen enhancer binding activity. These results support the concept that phosphorylation of Tyr-267, and to a lesser extent Tyr-363, is required for AR nuclear translocation and recruitment and DNA binding and provide a rationale for development of novel approaches to inhibit AR activity.

  2. RpoS proteolysis is regulated by a mechanism that does not require the SprE (RssB) response regulator phosphorylation site.

    Science.gov (United States)

    Peterson, Celeste N; Ruiz, Natividad; Silhavy, Thomas J

    2004-11-01

    In Escherichia coli the response regulator SprE (RssB) facilitates degradation of the sigma factor RpoS by delivering it to the ClpXP protease. This process is regulated: RpoS is degraded in logarithmic phase but becomes stable upon carbon starvation, resulting in its accumulation. Because SprE contains a CheY domain with a conserved phosphorylation site (D58), the prevailing model posits that this control is mediated by phosphorylation. To test this model, we mutated the conserved response regulator phosphorylation site (D58A) of the chromosomal allele of sprE and monitored RpoS levels in response to carbon starvation. Though phosphorylation contributed to the SprE basal activity, we found that RpoS proteolysis was still regulated upon carbon starvation. Furthermore, our results indicate that phosphorylation of wild-type SprE occurs by a mechanism that is independent of acetyl phosphate. PMID:15489452

  3. Conserved phosphorylation sites in the activation loop of the Arabidopsis phytosulfokine receptor PSKR1 differentially affect kinase and receptor activity.

    Science.gov (United States)

    Hartmann, Jens; Linke, Dennis; Bönniger, Christine; Tholey, Andreas; Sauter, Margret

    2015-12-15

    PSK (phytosulfokine) is a plant peptide hormone perceived by a leucine-rich repeat receptor kinase. Phosphosite mapping of epitope-tagged PSKR1 (phytosulfokine receptor 1) from Arabidopsis thaliana plants identified Ser(696) and Ser(698) in the JM (juxtamembrane) region and probably Ser(886) and/or Ser(893) in the AL (activation loop) as in planta phosphorylation sites. In vitro-expressed kinase was autophosphorylated at Ser(717) in the JM, and at Ser(733), Thr(752), Ser(783), Ser(864), Ser(911), Ser(958) and Thr(998) in the kinase domain. The LC-ESI-MS/MS spectra provided support that up to three sites (Thr(890), Ser(893) and Thr(894)) in the AL were likely to be phosphorylated in vitro. These sites are evolutionarily highly conserved in PSK receptors, indicative of a conserved function. Site-directed mutagenesis of the four conserved residues in the activation segment, Thr(890), Ser(893), Thr(894) and Thr(899), differentially altered kinase activity in vitro and growth-promoting activity in planta. The T899A and the quadruple-mutated TSTT-A (T890A/S893A/T894A/T899A) mutants were both kinase-inactive, but PSKR1(T899A) retained growth-promoting activity. The T890A and S893A/T894A substitutions diminished kinase activity and growth promotion. We hypothesize that phosphorylation within the AL activates kinase activity and receptor function in a gradual and distinctive manner that may be a means to modulate the PSK response. PMID:26472115

  4. Novel Tyrosine Phosphorylation Sites in Rat Skeletal Muscle Revealed by Phosphopeptide Enrichment and HPLC-ESI-MS/MS

    OpenAIRE

    Zhang, Xiangmin; Højlund, Kurt; Luo, Moulun; Meyer, Christian; Thangiah, Geetha; Yi, Zhengping

    2012-01-01

    Tyrosine phosphorylation plays a fundamental role in many cellular processes including differentiation, growth and insulin signaling. In insulin resistant muscle, aberrant tyrosine phosphorylation of several proteins has been detected. However, due to the low abundance of tyrosine phosphorylation (

  5. Phosphorylation site analysis of the anti-inflammatory and mRNA destabilizing protein tristetraprolin

    OpenAIRE

    Cao, Heping; Deterding, Leesa J.; Blackshear, Perry J.

    2007-01-01

    Tristetraprolin (TTP) is a member of the CCCH zinc finger proteins and is an anti-inflammatory protein. Mice deficient in TTP develop a profound inflammatory syndrome with erosive arthritis, autoimmunity and myeloid hyperplasia. TTP binds to mRNA AU-rich elements with high affinity for UUAUUUAUU nucleotides and causes destabilization of those mRNA molecules. TTP is phosphorylated extensively in vivo and is a substrate for multiple protein kinases in vitro. A number of approaches have been use...

  6. Predikin and PredikinDB: a computational framework for the prediction of protein kinase peptide specificity and an associated database of phosphorylation sites

    OpenAIRE

    Kemp Bruce E; Huber Thomas; Brinkworth Ross I; Saunders Neil FW; Kobe Bostjan

    2008-01-01

    Abstract Background We have previously described an approach to predicting the substrate specificity of serine-threonine protein kinases. The method, named Predikin, identifies key conserved substrate-determining residues in the kinase catalytic domain that contact the substrate in the region of the phosphorylation site and so determine the sequence surrounding the phosphorylation site. Predikin was implemented originally as a web application written in Javascript. Results Here, we describe a...

  7. Conserved phosphorylation sites in the activation loop of the Arabidopsis phytosulfokine receptor PSKR1 differentially affect kinase and receptor activity

    OpenAIRE

    Hartmann, Jens; Linke, Dennis; Bönniger, Christine; Tholey, Andreas; Sauter, Margret

    2015-01-01

    PSK (phytosulfokine) is a plant peptide hormone perceived by a leucine-rich repeat receptor kinase. Phosphosite mapping of epitope-tagged PSKR1 (phytosulfokine receptor 1) from Arabidopsis thaliana plants identified Ser696 and Ser698 in the JM (juxtamembrane) region and probably Ser886 and/or Ser893 in the AL (activation loop) as in planta phosphorylation sites. In vitro-expressed kinase was autophosphorylated at Ser717 in the JM, and at Ser733, Thr752, Ser783, Ser864, Ser911, Ser958 and Thr9...

  8. Vimentin-Ser82 as a memory phosphorylation site in astrocytes

    OpenAIRE

    Oguri, Takashi; Inoko, Akihito; SHIMA, HIROSHI; Izawa, Ichiro; Arimura, Nariko; Yamaguchi, Tomoya; Inagaki, Naoyuki; Kaibuchi, Kozo; Kikuchi, Kunimi; Inagaki, Masaki

    2006-01-01

    In astrocytes, the PGF(2 alpha) or ionomycin treatment induces the phosphorylation at Ser38 and Ser82 of vimentin, a type III intermediate filament, by Ca2+/calmodulin-dependent protein kinase II (CaMKII). We found here that vimentin phospho-Ser82 was dephosphorylated much slower than phospho-Ser38. Vimentin phospho-Ser38 was dephosphorylated quickly by purified PP1 catalytic subunit (PP1c) in vitro, whereas phospho-Ser82 was insensitive to PP1c. Because PP1c directly bound to vimentin throug...

  9. Localisation of the sites of action of cadmium on oxidative phosphorylation in potato tuber mitochondria using top-down elasticity analysis.

    Science.gov (United States)

    Kesseler, A; Brand, M D

    1994-11-01

    The aim of this study was to identify the significant sites of action of cadmium on oxidative phosphorylation in potato tuber mitocondria. We simplified the system to three convenient subsystems linked via the production or consumption of a common intermediate, namely protonmotive force. The three subsystems were substrate oxidation, which produces protonmotive force, and the proton leak reactions and the phosphorylation reactions, which consume protonmotive force. By measuring the effect of cadmium on the kinetic response of each subsystem to protonmotive force (top-down elasticity analysis), we found that cadmium stimulated proton leak reactions and strongly inhibited substrate oxidation, but had no measurable effect on the phosphorylation reactions. Cadmium therefore decreases the amount of ATP produced/oxygen consumed (the effective P/O ratio) not by inhibiting the phosphorylation reactions directly, but by inhibiting the production of protonmotive force and by diverting proton flux from phosphorylation reactions to the proton leak reactions. PMID:7957227

  10. Mapping of p140Cap phosphorylation sites: the EPLYA and EGLYA motifs have a key role in tyrosine phosphorylation and Csk binding, and are substrates of the Abl kinase.

    Directory of Open Access Journals (Sweden)

    Daniele Repetto

    Full Text Available Protein phosphorylation tightly regulates specific binding of effector proteins that control many diverse biological functions of cells (e. g. signaling, migration and proliferation. p140Cap is an adaptor protein, specifically expressed in brain, testis and epithelial cells, that undergoes phosphorylation and tunes its interactions with other regulatory molecules via post-translation modification. In this work, using mass spectrometry, we found that p140Cap is in vivo phosphorylated on tyrosine (Y within the peptide GEGLpYADPYGLLHEGR (from now on referred to as EGLYA as well as on three serine residues. Consistently, EGLYA has the highest score of in silico prediction of p140Cap phosphorylation. To further investigate the p140Cap function, we performed site specific mutagenesis on tyrosines inserted in EGLYA and EPLYA, a second sequence with the same highest score of phosphorylation. The mutant protein, in which both EPLYA/EGLYA tyrosines were converted to phenylalanine, was no longer tyrosine phosphorylated, despite the presence of other tyrosine residues in p140Cap sequence. Moreover, this mutant lost its ability to bind the C-terminal Src kinase (Csk, previously shown to interact with p140Cap by Far Western analysis. In addition, we found that in vitro and in HEK-293 cells, the Abelson kinase is the major kinase involved in p140Cap tyrosine phosphorylation on the EPLYA and EGLYA sequences. Overall, these data represent an original attempt to in vivo characterise phosphorylated residues of p140Cap. Elucidating the function of p140Cap will provide novel insights into its biological activity not only in normal cells, but also in tumors.

  11. A vitellogenin polyserine cleavage site: highly disordered conformation protected from proteolysis by phosphorylation.

    Science.gov (United States)

    Havukainen, Heli; Underhaug, Jarl; Wolschin, Florian; Amdam, Gro; Halskau, Øyvind

    2012-06-01

    Vitellogenin (Vg) is an egg-yolk precursor protein in most oviparous species. In honeybee (Apis mellifera), the protein (AmVg) also affects social behavior and life-span plasticity. Despite its manifold functions, the AmVg molecule remains poorly understood. The subject of our structure-oriented AmVg study is its polyserine tract - a little-investigated repetitive protein segment mostly found in insects. We previously reported that AmVg is tissue specifically cleaved in the vicinity of this tract. Here, we show that, despite its potential for an open, disordered structure, AmVg is unexpectedly resistant to trypsin/chymotrypsin digestion at the tract. Our findings suggest that multiple phosphorylation plays a role in this resilience. Sequence variation is highly pronounced at the polyserine region in insect Vgs. We demonstrate that sequence differences in this region can lead to structural variation, as NMR and circular dichroism (CD) evidence assign different conformational propensities to polyserine peptides from the honeybee and the jewel wasp Nasonia vitripennis; the former is extended and disordered and the latter more compact and helical. CD analysis of the polyserine region of bumblebee Bombus ignitus and wasp Pimpla nipponica supports a random coil structure in these species. The spectroscopic results strengthen our model of the AmVg polyserine tract as a flexible domain linker shielded by phosphorylation. PMID:22573762

  12. Factor XII stimulates ERK1/2 and Akt through uPAR, integrins, and the EGFR to initiate angiogenesis

    Science.gov (United States)

    LaRusch, Gretchen A.; Mahdi, Fakhri; Shariat-Madar, Zia; Adams, Gregory; Sitrin, Robert G.; Zhang, Wan Ming; McCrae, Keith R.

    2010-01-01

    Factor XII (FXII) and high molecular weight kininogen (HK) mutually block each other's binding to the urokinase plasminogen activator receptor (uPAR). We investigated if FXII stimulates cells by interacting with uPAR. FXII (3-62nM) with 0.05mM Zn2+ induces extracellular signal-related kinase 1/2 (ERK1/2; mitogen-activated protein kinase 44 [MAPK44] andMAPK42) and Akt (Ser473) phosphorylation in endothelial cells. FXII-induced phosphorylation of ERK1/2 or Akt is a zymogen activity, not an enzymatic event. ERK1/2 or Akt phosphorylation is blocked upstream by PD98059 or Wortmannin or LY294002, respectively. An uPAR signaling region for FXII is on domain 2 adjacent to uPAR's integrin binding site. Cleaved HK or peptides from HK's domain 5 blocks FXII-induced ERK1/2 and Akt phosphorylation. A β1 integrin peptide that binds uPAR, antibody 6S6 to β1 integrin, or the epidermal growth factor receptor (EGFR) inhibitor AG1478 blocks FXII-induced phosphorylation of ERK1/2 and Akt. FXII induces endothelial cell proliferation and 5-bromo-2′deoxy-uridine incorporation. FXII stimulates aortic sprouting in normal but not uPAR-deficient mouse aorta. FXII produces angiogenesis in matrigel plugs in normal but not uPAR-deficient mice. FXII knockout mice have reduced constitutive and wound-induced blood vessel number. In sum, FXII initiates signaling mediated by uPAR, β1 integrin, and the EGFR to induce human umbilical vein endothelial cell proliferation, growth, and angiogenesis. PMID:20228268

  13. The M3 Phosphorylation Site Is Required for Trafficking and Biological Roles of PIN-FORMED1, 2, and 7 in Arabidopsis

    Science.gov (United States)

    Ki, Daeeun; Sasayama, Daisuke; Cho, Hyung-Taeg

    2016-01-01

    Asymmetrically localized PIN-FORMED (PIN) auxin efflux carriers play key roles in regulating directional intercellular auxin movement, generating local auxin gradients, and diverse auxin-mediated growth and development. The polar localization of PINs is controlled by phosphorylation in the central hydrophilic loop (HL) of PINs. Although the M3 phosphorylation site, including phosphorylatable 5 Ser/Thr residues, is conserved among long HL-PINs, its native role has only been characterized in PIN3. In this study, we examined the role of M3 phosphorylation site of PIN1, PIN2, and PIN7 in intracellular trafficking, phosphorylation, and biological functions of those PINs in their native expressing tissues. Phosphorylation-defective mutations of the phosphorylatable residues in the M3 site of PIN1-HL led to alteration in subcellular polarity of PIN1 and caused defects in PIN1-mediated biological functions such as cotyledon development, phyllotaxy of vegetative leaves, and development of reproductive organs. The M3 mutations of PIN7 interfered with its polar recycling in the root columella cell in response to gravity stimulus and partially disrupted root gravitropism. On the other hand, the M3 site of PIN2 was shown to be necessary for its targeting to the plasma membrane. In vitro phosphorylation assay showed that the M3 phosphorylation residues of PIN1 are the partial targets by PINOID kinase. Our data suggest that the M3 phosphorylation site is functionally conserved among long HL-PINs by playing roles for their subcellular trafficking and auxin-mediated developmental processes.

  14. Current status of the plant phosphorylation site database PhosPhAt and its use as a resource for molecular plant physiology

    OpenAIRE

    Arsova, Borjana; Schulze, Waltraud X.

    2012-01-01

    As the most studied post-translational modification, protein phosphorylation is analyzed in a growing number of proteomic experiments. These high-throughput approaches generate large datasets, from which specific spectrum-based information can be hard to find. In 2007, the PhosPhAt database was launched to collect and present Arabidopsis phosphorylation sites identified by mass spectrometry from and for the scientific community. At present, PhosPhAt 3.0 consolidates phosphoproteomics data fro...

  15. Site-specific phosphorylation of the DNA damage response mediator rad9 by cyclin-dependent kinases regulates activation of checkpoint kinase 1.

    Directory of Open Access Journals (Sweden)

    Carla Manuela Abreu

    2013-04-01

    Full Text Available The mediators of the DNA damage response (DDR are highly phosphorylated by kinases that control cell proliferation, but little is known about the role of this regulation. Here we show that cell cycle phosphorylation of the prototypical DDR mediator Saccharomyces cerevisiae Rad9 depends on cyclin-dependent kinase (CDK complexes. We find that a specific G2/M form of Cdc28 can phosphorylate in vitro the N-terminal region of Rad9 on nine consensus CDK phosphorylation sites. We show that the integrity of CDK consensus sites and the activity of Cdc28 are required for both the activation of the Chk1 checkpoint kinase and its interaction with Rad9. We have identified T125 and T143 as important residues in Rad9 for this Rad9/Chk1 interaction. Phosphorylation of T143 is the most important feature promoting Rad9/Chk1 interaction, while the much more abundant phosphorylation of the neighbouring T125 residue impedes the Rad9/Chk1 interaction. We suggest a novel model for Chk1 activation where Cdc28 regulates the constitutive interaction of Rad9 and Chk1. The Rad9/Chk1 complex is then recruited at sites of DNA damage where activation of Chk1 requires additional DDR-specific protein kinases.

  16. Predikin and PredikinDB: a computational framework for the prediction of protein kinase peptide specificity and an associated database of phosphorylation sites

    Directory of Open Access Journals (Sweden)

    Kemp Bruce E

    2008-05-01

    Full Text Available Abstract Background We have previously described an approach to predicting the substrate specificity of serine-threonine protein kinases. The method, named Predikin, identifies key conserved substrate-determining residues in the kinase catalytic domain that contact the substrate in the region of the phosphorylation site and so determine the sequence surrounding the phosphorylation site. Predikin was implemented originally as a web application written in Javascript. Results Here, we describe a new version of Predikin, completely revised and rewritten as a modular framework that provides multiple enhancements compared with the original. Predikin now consists of two components: (i PredikinDB, a database of phosphorylation sites that links substrates to kinase sequences and (ii a Perl module, which provides methods to classify protein kinases, reliably identify substrate-determining residues, generate scoring matrices and score putative phosphorylation sites in query sequences. The performance of Predikin as measured using receiver operator characteristic (ROC graph analysis equals or surpasses that of existing comparable methods. The Predikin website has been redesigned to incorporate the new features. Conclusion New features in Predikin include the use of SQL queries to PredikinDB to generate predictions, scoring of predictions, more reliable identification of substrate-determining residues and putative phosphorylation sites, extended options to handle protein kinase and substrate data and an improved web interface. The new features significantly enhance the ability of Predikin to analyse protein kinases and their substrates. Predikin is available at http://predikin.biosci.uq.edu.au.

  17. The plastid casein kinase 2 phosphorylates Rubisco activase at the Thr-78 site but is not essential for regulation of Rubisco activation state

    Directory of Open Access Journals (Sweden)

    Sang Yeol eKim

    2016-03-01

    Full Text Available Rubisco activase (RCA is essential for the activation of Rubisco, the carboxylating enzyme of photosynthesis. In Arabidopsis, RCA is composed of a large RCAα and small RCAβ isoform that are formed by alternative splicing of a single gene (At2g39730. The activity of Rubisco is controlled in response to changes in irradiance by regulation of RCA activity, which is known to involve a redox-sensitive disulfide bond located in the carboxy-terminal extension of the RCAα subunit. Additionally, phosphorylation of RCA threonine-78 (Thr-78 has been reported to occur in the dark suggesting that phosphorylation may also be associated with dark-inactivation of RCA and deactivation of Rubisco. In the present study, we developed site-specific antibodies to monitor phosphorylation of RCA at the Thr-78 site and used non-reducing SDS-PAGE to monitor the redox status of the RCAα subunit. By immunoblotting, phosphorylation of both RCA isoforms occurred at low light and in the dark and feeding peroxide or DTT to leaf segments indicated that redox status of the chloroplast stroma was a critical factor controlling RCA phosphorylation. Use of a knockout mutant identified the plastid-targeted casein kinase 2 (cpCK2α as the major protein kinase involved in RCA phosphorylation. Studies with recombinant cpCK2α and synthetic peptide substrates identified acidic residues at the -1, +2 and +3 positions surrounding Thr-78 as strong positive recognition elements. The cpck2 knockout mutant had strongly reduced phosphorylation at the Thr-78 site but was similar to wild type plants in terms of induction kinetics of photosynthesis following transfer from darkness or low light to high light, suggesting that if phosphorylation of RCA Thr-78 plays a direct role it would be redundant to redox regulation for control of Rubisco activation state under normal conditions.

  18. Simultaneous quantification of protein phosphorylation sites using liquid chromatography-tandem mass spectrometry-based targeted proteomics: a linear algebra approach for isobaric phosphopeptides.

    Science.gov (United States)

    Xu, Feifei; Yang, Ting; Sheng, Yuan; Zhong, Ting; Yang, Mi; Chen, Yun

    2014-12-01

    As one of the most studied post-translational modifications (PTM), protein phosphorylation plays an essential role in almost all cellular processes. Current methods are able to predict and determine thousands of phosphorylation sites, whereas stoichiometric quantification of these sites is still challenging. Liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS)-based targeted proteomics is emerging as a promising technique for site-specific quantification of protein phosphorylation using proteolytic peptides as surrogates of proteins. However, several issues may limit its application, one of which relates to the phosphopeptides with different phosphorylation sites and the same mass (i.e., isobaric phosphopeptides). While employment of site-specific product ions allows for these isobaric phosphopeptides to be distinguished and quantified, site-specific product ions are often absent or weak in tandem mass spectra. In this study, linear algebra algorithms were employed as an add-on to targeted proteomics to retrieve information on individual phosphopeptides from their common spectra. To achieve this simultaneous quantification, a LC-MS/MS-based targeted proteomics assay was first developed and validated for each phosphopeptide. Given the slope and intercept of calibration curves of phosphopeptides in each transition, linear algebraic equations were developed. Using a series of mock mixtures prepared with varying concentrations of each phosphopeptide, the reliability of the approach to quantify isobaric phosphopeptides containing multiple phosphorylation sites (≥ 2) was discussed. Finally, we applied this approach to determine the phosphorylation stoichiometry of heat shock protein 27 (HSP27) at Ser78 and Ser82 in breast cancer cells and tissue samples.

  19. Akt is negatively regulated by the MULAN E3 ligase

    Institute of Scientific and Technical Information of China (English)

    Seunghee Bae; Jongdoo Kim; Hong-Duck Um; In-Chul Park; Su-Jae Lee; Seon Young Nam; Young-Woo Jin; Jae Ho Lee; Sungkwan An; Sun-Yong Kim; Jin Hyuk Jung; Yeongmin Yoon; Hwa Jun Cha; Hyunjin Lee; Karam Kim; Jongran Kim; In-Sook An

    2012-01-01

    The serine/threonine kinase Akt functions in multiple cellular processes,including cell survival and tumor development.Studies of the mechanisms that negatively regulate Akt have focused on dephosphorylation-mediated inactivation.In this study,we identified a negative regulator of Akt,MULAN,which possesses both a RING finger domain and E3 ubiquitin ligase activity.Akt was found to directly interact with MULAN and to be ubiquitinated by MULAN in vitro and in vivo.Other molecular assays demonstrated that phosphorylated Akt is a substantive target for both interaction with MULAN and ubiquitination by MULAN.The results of the functional studies suggest that the degradation of Akt by MULAN suppresses cell proliferation and viability.These data provide insight into the Akt ubiquitination signaling network.

  20. Metformin and rapamycin have distinct effects on the AKT pathway and proliferation in breast cancer cells.

    Science.gov (United States)

    Zakikhani, Mahvash; Blouin, Marie-José; Piura, Esther; Pollak, Michael N

    2010-08-01

    Rapamycin and its analogues inhibit mTOR, which leads to decreased protein synthesis and decreased cancer cell proliferation in many experimental systems. Adenosine 5'- monophosphate-activated protein kinase (AMPK) activators such as metformin have similar actions, in keeping with the TSC2/1 pathway linking activation of AMPK to inhibition of mTOR. As mTOR inhibition by rapamycin is associated with attenuation of negative feedback to IRS-1, rapamycin is known to increase activation of AKT, which may reduce its anti-neoplastic activity. We observed that metformin exposure decreases AKT activation, an action opposite to that of rapamycin. We show that metformin (but not rapamycin) exposure leads to increased phosphorylation of IRS-1 at Ser(789), a site previously reported to inhibit downstream signaling and to be an AMPK substrate phosphorylated under conditions of cellular energy depletion. siRNA methods confirmed that reduction of AMPK levels attenuates both the IRS-1 Ser(789) phosphorylation and the inhibition of AKT activation associated with metformin exposure. Although both rapamycin and metformin inhibit mTOR (the former directly and the latter through AMPK signaling), our results demonstrate previously unrecognized differences between these agents. The data are consistent with the observation that maximal induction of apoptosis and inhibition of proliferation are greater for metformin than rapamycin. PMID:20135346

  1. Multiple repeats of Helicobacter pylori CagA EPIYA-C phosphorylation sites predict risk of gastric ulcer in Iran.

    Science.gov (United States)

    Honarmand-Jahromy, Sahar; Siavoshi, Farideh; Malekzadeh, Reza; Sattari, Taher Nejad; Latifi-Navid, Saeid

    2015-12-01

    Biological activity of Helicobacter pylori oncoprotein CagA is determined by a diversity in the tyrosine phosphorylation motif sites. In the present study, the diversity and the type of the H. pylori CagA EPIYA motifs and their association with gastric ulcer (GU) and duodenal ulcer (DU) in Iranian dyspeptic patients were assessed. PCR amplification, sequencing, and bioinformatic analysis were performed to determine the pattern of CagA EPIYA motifs. Of 168 H. pylori cagA(+) strains, the frequency of ABC was 93.50%, ABCCC 5.40%, ABC + ABCCC 0.6% and ABCC 0.6%. There was no EPIYA-D segment. The ABCCC pattern of EPIYA motif was more frequent in the H. pylori isolates from GU (8/50, 16%) than in those from chronic gastritis (CG) (0/81, 0%) (P = 0). In contrast, The ABC pattern of EPIYA motif was less frequent in the H. pylori isolates from GU (41/50, 82%) than in those from CG (80/81, 98.80%) (Age-sex-adjusted odds ratio (OR) = 0.020, 95% CI = 0.002-0.259; P = 0.003). The distribution of the ABC motif was almost the same in H. pylori isolates from CG (98.80%) and DU diseases (97.30%). There was no significant association between the number of CagA EPIYA-C segment and DU (P > 0.05). We have proposed that CagA from Iranian H. pylori strains were Western type and all strains had active phosphorylation sites. The three EPIYA-C motifs of CagA were more frequently observed in the H. pylori strains from GU; thus it might be an important biomarker for predicting the GU risk in Iran.

  2. Cadmium Activates Multiple Signaling Pathways That Coordinately Stimulate Akt Activity to Enhance c-Myc mRNA Stability.

    Directory of Open Access Journals (Sweden)

    Jia-Shiuan Tsai

    Full Text Available Cadmium is a known environmental carcinogen. Exposure of Cd leads to the activation of several proto-oncogenes in cells. We investigated here the mechanism of c-Myc expression in hepatic cells under Cd treatment. The c-Myc protein and mRNA levels increased in dose- and time-dependent manners in HepG2 cells with Cd treatment. This increase was due to an increase in c-Myc mRNA stability. To explore the mechanism involved in enhancing the mRNA stability, several cellular signaling factors that evoked by Cd treatment were analyzed. PI3K, p38, ERK and JNK were activated by Cd. However, ERK did not participate in the Cd-induced c-Myc expression. Further analysis revealed that mTORC2 was a downstream factor of p38. PI3K, JNK and mTORC2 coordinately activated Akt. Akt was phosphorylated at Thr450 in the untreated cells. Cd treatment led to additional phosphorylation at Thr308 and Ser473. Blocking any of the three signaling factors resulted in the reduction of phosphorylation level at all three Akt sites. The activated Akt phosphorylated Foxo1 and allowed the modified protein to translocate into the cytoplasm. We conclude that Cd-induced accumulation of c-Myc requires the activation of several signaling pathways. The signals act coordinately for Akt activation and drive the Foxo1 from the nucleus to the cytoplasm. Reduction of Foxo1 in the nucleus reduces the transcription of its target genes that may affect c-Myc mRNA stability, resulting in a higher accumulation of the c-Myc proteins.

  3. PI-103 and Quercetin Attenuate PI3K-AKT Signaling Pathway in T- Cell Lymphoma Exposed to Hydrogen Peroxide

    Science.gov (United States)

    Maurya, Akhilendra Kumar; Vinayak, Manjula

    2016-01-01

    Phosphatidylinositol 3 kinase—protein kinase B (PI3K-AKT) pathway has been considered as major drug target site due to its frequent activation in cancer. AKT regulates the activity of various targets to promote tumorigenesis and metastasis. Accumulation of reactive oxygen species (ROS) has been linked to oxidative stress and regulation of signaling pathways for metabolic adaptation of tumor microenvironment. Hydrogen peroxide (H2O2) in this context is used as ROS source for oxidative stress preconditioning. Antioxidants are commonly considered to be beneficial to reduce detrimental effects of ROS and are recommended as dietary supplements. Quercetin, a ubiquitous bioactive flavonoid is a dietary component which has attracted much of interest due to its potential health-promoting effects. Present study is aimed to analyze PI3K-AKT signaling pathway in H2O2 exposed Dalton’s lymphoma ascite (DLA) cells. Further, regulation of PI3K-AKT pathway by quercetin as well as PI-103, an inhibitor of PI3K was analyzed. Exposure of H2O2 (1mM H2O2 for 30min) to DLA cells caused ROS accumulation and resulted in increased phosphorylation of PI3K and downstream proteins PDK1 and AKT (Ser-473 and Thr-308), cell survival factors BAD and ERK1/2, as well as TNFR1. However, level of tumor suppressor PTEN was declined. Both PI-103 & quercetin suppressed the enhanced level of ROS and significantly down-regulated phosphorylation of AKT, PDK1, BAD and level of TNFR1 as well as increased the level of PTEN in H2O2 induced lymphoma cells. The overall result suggests that quercetin and PI3K inhibitor PI-103 attenuate PI3K-AKT pathway in a similar mechanism. PMID:27494022

  4. Extracellular signal-regulated kinase 2 (ERK2) phosphorylation sites and docking domain on the nuclear pore complex protein Tpr cooperatively regulate ERK2-Tpr interaction.

    Science.gov (United States)

    Vomastek, Tomás; Iwanicki, Marcin P; Burack, W Richard; Tiwari, Divya; Kumar, Devanand; Parsons, J Thomas; Weber, Michael J; Nandicoori, Vinay Kumar

    2008-11-01

    Identifying direct substrates of mitogen-activated protein kinases (MAPKs) and understanding how those substrates are selected is central to understanding how these ubiquitously activated enzymes generate diverse biological responses. In previous work, we identified several new candidate substrates for the MAPK ERK2 (extracellular signal-regulated kinase 2), including the nuclear pore complex protein Tpr (translocated promoter region). In this report, we identify sites on Tpr for ERK2 phosphorylation and binding and demonstrate their functional interaction. ERK2 phosphorylation and dimerization are necessary for ERK2-Tpr binding, and this occurs through a DEF (docking site for ERK2, FXF) domain on Tpr. Surprisingly, the DEF domain and the phosphorylation sites displayed positive cooperativity to promote ERK2 binding to Tpr, in contrast to substrates where phosphorylation reduces binding. Ectopic expression or depletion of Tpr resulted in decreased movement of activated ERK2 from the cytoplasm to the nucleus, implying a role for Tpr in ERK2 translocation. Collectively, the data provide direct evidence that a component of the nuclear pore complex is a bona fide substrate of ERK2 in vivo and that activated ERK2 stably associates with this substrate after phosphorylation, where it could play a continuing role in nuclear pore function. We propose that Tpr is both a substrate and a scaffold for activated ERKs.

  5. Mutation of light-dependent phosphorylation sites of the Drosophila transient receptor potential-like (TRPL) ion channel affects its subcellular localization and stability.

    Science.gov (United States)

    Cerny, Alexander C; Oberacker, Tina; Pfannstiel, Jens; Weigold, Sebastian; Will, Carina; Huber, Armin

    2013-05-31

    The Drosophila phototransduction cascade terminates in the opening of the ion channel transient receptor potential (TRP) and TRP-like (TRPL). Contrary to TRP, TRPL undergoes light-dependent subcellular trafficking between rhabdomeric photoreceptor membranes and an intracellular storage compartment, resulting in long term light adaptation. Here, we identified in vivo phosphorylation sites of TRPL that affect TRPL stability and localization. Quantitative mass spectrometry revealed a light-dependent change in the TRPL phosphorylation pattern. Mutation of eight C-terminal phosphorylation sites neither affected multimerization of the channels nor the electrophysiological response of flies expressing the mutated channels. However, these mutations resulted in mislocalization and enhanced degradation of TRPL after prolonged dark-adaptation. Mutation of subsets of the eight C-terminal phosphorylation sites also led to a reduction of TRPL content and partial mislocalization in the dark. This suggests that a light-dependent switch in the phosphorylation pattern of the TRPL channel mediates stable expression of TRPL in the rhabdomeres upon prolonged dark-adaptation. PMID:23592784

  6. Mutation of Light-dependent Phosphorylation Sites of the Drosophila Transient Receptor Potential-like (TRPL) Ion Channel Affects Its Subcellular Localization and Stability*

    Science.gov (United States)

    Cerny, Alexander C.; Oberacker, Tina; Pfannstiel, Jens; Weigold, Sebastian; Will, Carina; Huber, Armin

    2013-01-01

    The Drosophila phototransduction cascade terminates in the opening of the ion channel transient receptor potential (TRP) and TRP-like (TRPL). Contrary to TRP, TRPL undergoes light-dependent subcellular trafficking between rhabdomeric photoreceptor membranes and an intracellular storage compartment, resulting in long term light adaptation. Here, we identified in vivo phosphorylation sites of TRPL that affect TRPL stability and localization. Quantitative mass spectrometry revealed a light-dependent change in the TRPL phosphorylation pattern. Mutation of eight C-terminal phosphorylation sites neither affected multimerization of the channels nor the electrophysiological response of flies expressing the mutated channels. However, these mutations resulted in mislocalization and enhanced degradation of TRPL after prolonged dark-adaptation. Mutation of subsets of the eight C-terminal phosphorylation sites also led to a reduction of TRPL content and partial mislocalization in the dark. This suggests that a light-dependent switch in the phosphorylation pattern of the TRPL channel mediates stable expression of TRPL in the rhabdomeres upon prolonged dark-adaptation. PMID:23592784

  7. Current status of the plant phosphorylation site database PhosPhAt and its use as a resource for molecular plant physiology.

    Science.gov (United States)

    Arsova, Borjana; Schulze, Waltraud X

    2012-01-01

    As the most studied post-translational modification, protein phosphorylation is analyzed in a growing number of proteomic experiments. These high-throughput approaches generate large datasets, from which specific spectrum-based information can be hard to find. In 2007, the PhosPhAt database was launched to collect and present Arabidopsis phosphorylation sites identified by mass spectrometry from and for the scientific community. At present, PhosPhAt 3.0 consolidates phosphoproteomics data from 19 published proteomic studies. Out of 5460 listed unique phosphoproteins, about 25% have been identified in at least two independent experimental setups. This is especially important when considering issues of false positive and false negative identification rates and data quality (Durek etal., 2010). This valuable data set encompasses over 13205 unique phosphopeptides, with unambiguous mapping to serine (77%), threonine (17%), and tyrosine (6%). Sorting the functional annotations of experimentally found phosphorylated proteins in PhosPhAt using Gene Ontology terms shows an over-representation of proteins in regulatory pathways and signaling processes. A similar distribution is found when the PhosPhAt predictor, trained on experimentally obtained plant phosphorylation sites, is used to predict phosphorylation sites for the Arabidopsis genome. Finally, the possibility to insert a protein sequence into the PhosPhAt predictor allows species independent use of the prediction resource. In practice, PhosPhAt also allows easy exploitation of proteomic data for design of further targeted experiments. PMID:22723801

  8. Differential Regulation of Kainate Receptor Trafficking by Phosphorylation of Distinct Sites on GluR6*

    OpenAIRE

    Nasu-Nishimura, Yukiko; Jaffe, Howard; Isaac, John T R; Roche, Katherine W.

    2009-01-01

    Kainate receptors are widely expressed in the brain, and are present at pre- and postsynaptic sites where they play a prominent role in synaptic plasticity and the regulation of network activity. Within individual neurons, kainate receptors of different subunit compositions are targeted to various locations where they serve distinct functional roles. Despite this complex targeting, relatively little is known about the molecular mechanisms regulating kainate receptor subunit trafficking. Here ...

  9. Shutoff and agonist-triggered internalization of protease-activated receptor 1 can be separated by mutation of putative phosphorylation sites in the cytoplasmic tail.

    Science.gov (United States)

    Hammes, S R; Shapiro, M J; Coughlin, S R

    1999-07-20

    The thrombin receptor PAR1 becomes rapidly phosphorylated upon activation by either thrombin or exogenous SFLLRN agonist peptide. Substitution of alanine for all serine and threonine residues in the receptor's cytoplasmic carboxyl-terminal tail ablated phosphorylation and yielded a receptor defective in both shutoff and agonist-triggered internalization. These observations suggested that activation-dependent phosphorylation of PAR1's cytoplasmic tail is required for both shutoff and agonist-triggered internalization. To identify the phosphorylation site(s) that are necessary for these functions, we generated three mutant receptors in which alanine was substituted for serine and threonine residues in the amino-terminal, middle, and carboxyl-terminal thirds of PAR1's cytoplasmic tail. When stably expressed in fibroblasts, all three mutated receptors were rapidly phosphorylated in response to agonist, while a mutant in which all serines and threonines in the cytoplasmic tail were converted to alanines was not. This result suggests that phosphorylation can occur at multiple sites in PAR1's cytoplasmic tail. Alanine substitutions in the N-terminal and C-terminal portions of the tail had no effect on either receptor shutoff or agonist-triggered internalization. By contrast, alanine substitutions in the "middle" serine cluster between Ser(391) and Ser(406) yielded a receptor with considerably slower shutoff of signaling after thrombin activation than the wild type. Surprisingly, this same mutant was indistinguishable from the wild type in agonist-triggered internalization and degradation. Overexpression of G protein-coupled receptor kinase 2 (GRK2) and GRK3 "suppressed" the shutoff defect of the S --> A (391-406) mutant, consistent with this defect being due to altered receptor phosphorylation. These results suggest that specific phosphorylation sites are required for rapid receptor shutoff, but phosphorylation at multiple alternative sites is sufficient for agonist

  10. Cardiac myosin binding protein C phosphorylation affects cross-bridge cycle's elementary steps in a site-specific manner.

    Directory of Open Access Journals (Sweden)

    Li Wang

    Full Text Available Based on our recent finding that cardiac myosin binding protein C (cMyBP-C phosphorylation affects muscle contractility in a site-specific manner, we further studied the force per cross-bridge and the kinetic constants of the elementary steps in the six-state cross-bridge model in cMyBP-C mutated transgenic mice for better understanding of the influence of cMyBP-C phosphorylation on contractile functions. Papillary muscle fibres were dissected from cMyBP-C mutated mice of ADA (Ala273-Asp282-Ala302, DAD (Asp273-Ala282-Asp302, SAS (Ser273-Ala282-Ser302, and t/t (cMyBP-C null genotypes, and the results were compared to transgenic mice expressing wide-type (WT cMyBP-C. Sinusoidal analyses were performed with serial concentrations of ATP, phosphate (Pi, and ADP. Both t/t and DAD mutants significantly reduced active tension, force per cross-bridge, apparent rate constant (2πc, and the rate constant of cross-bridge detachment. In contrast to the weakened ATP binding and enhanced Pi and ADP release steps in t/t mice, DAD mice showed a decreased ADP release without affecting the ATP binding and the Pi release. ADA showed decreased ADP release, and slightly increased ATP binding and cross-bridge detachment steps, whereas SAS diminished the ATP binding step and accelerated the ADP release step. t/t has the broadest effects with changes in most elementary steps of the cross-bridge cycle, DAD mimics t/t to a large extent, and ADA and SAS predominantly affect the nucleotide binding steps. We conclude that the reduced tension production in DAD and t/t is the result of reduced force per cross-bridge, instead of the less number of strongly attached cross-bridges. We further conclude that cMyBP-C is an allosteric activator of myosin to increase cross-bridge force, and its phosphorylation status modulates the force, which is regulated by variety of protein kinases.

  11. Cellular Functions Regulated by Phosphorylation of EGFR on Tyr845

    Directory of Open Access Journals (Sweden)

    Ken-ichi Sato

    2013-05-01

    Full Text Available The Src gene product (Src and the epidermal growth factor receptor (EGFR are prototypes of oncogene products and function primarily as a cytoplasmic non-receptor tyrosine kinase and a transmembrane receptor tyrosine kinase, respectively. The identification of Src and EGFR, and the subsequent extensive investigations of these proteins have long provided cutting edge research in cancer and other molecular and cellular biological studies. In 1995, we reported that the human epidermoid carcinoma cells, A431, contain a small fraction of Src and EGFR in which these two kinase were in physical association with each other, and that Src phosphorylates EGFR on tyrosine 845 (Y845 in the Src-EGFR complex. Y845 of EGFR is located in the activation segment of the kinase domain, where many protein kinases contain kinase-activating autophosphorylation sites (e.g., cAMP-dependent protein kinase, Src family kinases, transmembrane receptor type tyrosine kinases or trans-phosphorylation sites (e.g., cyclin-dependent protein kinase, mitogen-activated protein kinase, Akt protein kinase. A number of studies have demonstrated that Y845 phosphorylation serves an important role in cancer as well as normal cells. Here we compile the experimental facts involving Src phosphorylation of EGFR on Y845, by which cell proliferation, cell cycle control, mitochondrial regulation of cell metabolism, gamete activation and other cellular functions are regulated. We also discuss the physiological relevance, as well as structural insights of the Y845 phosphorylation.

  12. Cell confluence induces switching from proliferation to migratory signaling by site-selective phosphorylation of PDGF receptors on lipid raft platforms.

    Science.gov (United States)

    Szöőr, Árpád; Ujlaky-Nagy, László; Tóth, Gábor; Szöllősi, János; Vereb, György

    2016-02-01

    Platelet derived growth factor receptors (PDGFR) play an important role in tumor pathogenesis and are frequently overexpressed in glioblastoma. Earlier we have shown that only confluent glioblastoma cell cultures exhibit a biphasic calcium transient upon PDGF stimulation. Here, we examined how the change in cell density leads to differential cellular responses to the same PDGF stimulus. PDGF beta receptors and their specific phosphotyrosine residues were fluorescently co-labeled on A172 and T98G glioblastoma cells. The distribution in cell membrane microdomains (lipid rafts) and the phosphorylation state of PDGFR was measured by confocal microscopy and quantitated by digital image processing. Corresponding bulk data were obtained by Western blotting. Activation of relevant downstream signaling pathways was assessed by immunofluorescence in confocal microscopy and by Western blot analysis. Functional outcomes were confirmed with bulk and single cell proliferation assays and motility measurements. In non-confluent (sparse) cultures PDGF-BB stimulation significantly increased phosphorylation of Tyr716 specific for the Ras/MAPK pathway and Tyr751 specific for the phosphoinositide 3-kinase/Akt pathway. As cell monolayers reached confluence, Tyr771 and Tyr1021 were the prominently phosphorylated residues. Tyr771 serves as adaptor for Ras-GAP, which inactivates the MAPK pathway, and Tyr1021 feeds into the phospholipase C-gamma/PKC pathway. Coherent with this, MAPK phosphorylation, Ki-67 positivity and proliferation dominated in dispersed cells, and could be abolished with inhibitors of the MAPK pathway. At the same time, RhoA activation, redistribution of cortactin to leading edges, and increased motility were the prominent output features in confluent cultures. Importantly, the stimulus-evoked confluence-specific changes in the phosphorylation of tyrosine residues occurred mainly in GM1-rich lipid microdomains (rafts). These observations suggest that the same stimulus is

  13. Sulfonium Ion Derivatization, Isobaric Stable Isotope Labeling and Data Dependent CID- and ETD-MS/MS for Enhanced Phosphopeptide Quantitation, Identification and Phosphorylation Site Characterization

    OpenAIRE

    Lu, Yali; Zhou, Xiao; Stemmer, Paul M.; Reid, Gavin E.

    2011-01-01

    An amine specific peptide derivatization strategy involving the use of novel isobaric stable isotope encoded ‘fixed charge’ sulfonium ion reagents, coupled with an analysis strategy employing capillary HPLC, ESI-MS, and automated data dependent ion trap CID-MS/MS, -MS3, and/or ETD-MS/MS, has been developed for the improved quantitative analysis of protein phosphorylation, and for identification and characterization of their site(s) of modification. Derivatization of 50 synthetic phosphopeptid...

  14. The autophosphorylation and p34cdc2 phosphorylation sites of casein kinase-2 beta-subunit are not essential for reconstituting the fully-active heterotetrameric holoenzyme

    DEFF Research Database (Denmark)

    Meggio, F; Boldyreff, B; Issinger, O G;

    1993-01-01

    Two mutants of human casein kinase-2 beta-subunit with short deletions at either their amino (delta 1-4) or carboxy (delta 209-215) terminal side have been created that have lost the capability to undergo autophosphorylation and p34cdc2 mediated phosphorylation, respectively. Both mutants give rise...... to reconstituted CK2 holoenzymes displaying basal catalytic activity, thermostability and responsiveness to polylysine, identical to those of wild-type holoenzyme, whose reconstitution, moreover, is not affected by previous phosphorylation of the beta-subunit at either its N-terminal or C-terminal sites. Unlike...

  15. Characterization of phosphorylation sites in the cytoplasmic domain of the 300 kDa mannose-6-phosphate receptor

    DEFF Research Database (Denmark)

    Rosorius, O; Mieskes, G; Issinger, O G;

    1993-01-01

    kinases phosphorylate the cytoplasmic tail exclusively on serine residues. Inhibition studies using synthetic peptides, partial sequencing of isolated tryptic phosphopeptides and co-migration with tryptic phosphopeptides from MPR 300 labelled in vivo showed that (i) PKA phosphorylates the cytoplasmic MPR...... which may play a role in the transport function of MPR 300 and/or interaction with other proteins....

  16. Serine 302 Phosphorylation of Mouse Insulin Receptor Substrate 1 (IRS1) Is Dispensable for Normal Insulin Signaling and Feedback Regulation by Hepatic S6 Kinase.

    Science.gov (United States)

    Copps, Kyle D; Hançer, Nancy J; Qiu, Wei; White, Morris F

    2016-04-15

    Constitutive activation of the mammalian target of rapamycin complex 1 and S6 kinase (mTORC1→ S6K) attenuates insulin-stimulated Akt activity in certain tumors in part through "feedback" phosphorylation of the upstream insulin receptor substrate 1 (IRS1). However, the significance of this mechanism for regulating insulin sensitivity in normal tissue remains unclear. We investigated the function of Ser-302 in mouse IRS1, the major site of its phosphorylation by S6K in vitro, through genetic knock-in of a serine-to-alanine mutation (A302). Although insulin rapidly stimulated feedback phosphorylation of Ser-302 in mouse liver and muscle, homozygous A302 mice (A/A) and their knock-in controls (S/S) exhibited similar glucose homeostasis and muscle insulin signaling. Furthermore, both A302 and control primary hepatocytes from which Irs2 was deleted showed marked inhibition of insulin-stimulated IRS1 tyrosine phosphorylation and PI3K binding after emetine treatment to raise intracellular amino acids and activate mTORC1 → S6K signaling. To specifically activate mTORC1 in mouse tissue, we deleted hepatic Tsc1 using Cre adenovirus. Although it moderately decreased IRS1/PI3K association and Akt phosphorylation in liver, Tsc1 deletion failed to cause glucose intolerance or promote hyperinsulinemia in mixed background A/A or S/S mice. Moreover, Tsc1 deletion failed to stimulate phospho-Ser-302 or other putative S6K sites within IRS1, whereas ribosomal S6 protein was constitutively phosphorylated. Following acute Tsc1 deletion from hepatocytes, Akt phosphorylation, but not IRS1/PI3K association, was rapidly restored by treatment with the mTORC1 inhibitor rapamycin. Thus, within the hepatic compartment, mTORC1 → S6K signaling regulates Akt largely through IRS-independent means with little effect upon physiologic insulin sensitivity.

  17. Analysis of regulatory phosphorylation sites in ZAP-70 by capillary high-performance liquid chromatography coupled to electrospray ionization or matrix-assisted laser desorption ionization time-of-flight mass spectrometry

    NARCIS (Netherlands)

    Miliotis, Tasso; Olof Ericsson, Per; Marko-Varga, Gyorgy; Svensson, Robert; Nilsson, Johan; Laurell, Thomas; Bischoff, Rainer

    2001-01-01

    A methodology for the rapid and quantitative analysis of phosphorylation sites in proteins is presented. The coupling of capillary high-performance liquid chromatography (HPLC) to electrospray ionization mass spectrometry (ESI-MS) allowed one to distinguish phosphorylation sites based on retention t

  18. Current status of the plant phosphorylation site database PhosPhAt and its use as a resource for molecular plant physiology

    Directory of Open Access Journals (Sweden)

    Borjana eArsova

    2012-06-01

    Full Text Available As the most studied post-translational modification protein phosphorylation is part of a growing number of proteomic studies. But these approaches generate large datasets from which, the specific spectrum based data can be hard to find. In 2007 the PhosPhAt database made it its goal to collect and present Arabidopsis phosphorylation data from and for the scientific community. At present, PhosPhAt 3.0 consolidates phosphoproteomics data from 19 published studies. 5460 Unique phosphoproteins are listed, about 25% of which have been identified in at least two independent experimental setups. The valuable data set encompasses over 13205 unique phosphopeptides, with unambiguous mapping to Serine (77% Theronine (17% and Tyrosine (6%. Sorting the functional annotations of experimentally found phosphorylated proteins in PhosPhAt, using Gene Ontology terms, shows an over representation of proteins in regulatory and signaling processes. Similar distribution is found when the PhosPhAt predictor, trained on experimentally obtained plant data, is used to predict phosphorylation sites for the Arabidopsis genome. Finally, the possibility to insert a protein sequence into the PhosPhAt predictor allows species independent use of the resource. In practice, we found that PhosPhAt allows easy exploitation of proteomic data for designing further experiments, and will demonstrate this on the example of targeted analysis of protein phosphorylation.

  19. Regulation of Akt/PKB activity by P21-activated kinase in cardiomyocytes.

    Science.gov (United States)

    Mao, Kai; Kobayashi, Satoru; Jaffer, Zahara M; Huang, Yuan; Volden, Paul; Chernoff, Jonathan; Liang, Qiangrong

    2008-02-01

    Akt/PKB is a critical regulator of cardiac function and morphology, and its activity is governed by dual phosphorylation at active loop (Thr308) by phosphoinositide-dependent protein kinase-1 (PDK1) and at carboxyl-terminal hydrophobic motif (Ser473) by a putative PDK2. P21-activated kinase-1 (Pak1) is a serine/threonine protein kinase implicated in the regulation of cardiac hypertrophy and contractility and was shown previously to activate Akt through an undefined mechanism. Here we report Pak1 as a potential PDK2 that is essential for Akt activity in cardiomyocytes. Both Pak1 and Akt can be activated by multiple hypertrophic stimuli or growth factors in a phosphatidylinositol-3-kinase (PI3K)-dependent manner. Pak1 overexpression induces Akt phosphorylation at both Ser473 and Thr308 in cardiomyocytes. Conversely, silencing or inactivating Pak1 gene diminishes Akt phosphorylation in vitro and in vivo. Purified Pak1 can directly phosphorylate Akt only at Ser473, suggesting that Pak1 may be a relevant PDK2 responsible for AKT Ser473 phosphorylation in cardiomyocytes. In addition, Pak1 protects cardiomyocytes from cell death, which is blocked by Akt inhibition. Our results connect two important regulators of cellular physiological functions and provide a potential mechanism for Pak1 signaling in cardiomyocytes. PMID:18054038

  20. Host-guest complexation. 17. Design, syntheses, and complexation of macrocycles containing phosphoryl, pyridine oxide, and urea binding sites

    International Nuclear Information System (INIS)

    Phosphoryl (P=O), urea (N2C=O), pyridine, and pyridine oxide (N → O) groups have been incorporated into the ring systems of macrocyclic polyethers. The association constants of the resulting eight new ligand systems toward Li+, Na+, K+, Rb+, Cs+, and NH4+ picrates in CHCl3 were surveyed, and the free energies of association were estimated. The P=O complexing sites were covalently bonded through two attached o-tolyl groups as in the unit RP(O)(C6H4CH2-o)2, in which different R groups were attached to phosphorus. The resulting unit, written as RPOD, was attached to two ether oxygens (0), which in turn were connected through CH2CH2 or E units to form macrocycles. Ligand systems C6H5POD(OEOE)2O (9), C6H5POD(OEOEO)2E (10), o-HO2CC6H4POD(OEOE)2O (11), o-CH3O2CC6H4POD(OEOE)2O (12), CH3OPOD(OEOE)2O (13), and C6H5POD(OEO)2PODC6H5 (14 and 15, the syn and anti isomers) were synthesized and examined. The urea complexing site was cyclic, CH2(CH2N)2C = O (abbreviated to UON), and was bonded through its two nitrogens to E units. The cycle prepared and examined was UON(EOEOE)2O (16). The pyridine and pyridine oxide complexing sites were bonded through CH2 groups in their α,α' positions to comprise the units α-CH2(C5H3N)CH2-α and α-CH2(C5H3NO)CH2-α, respectively, the latter of which was abbreviated as POM. The new cycle prepared and examined was POM(OEOE)2O (18). The patterns of ΔG0 values of complexation of these ligand systems were compared to those of 2,3-naphtho 18-crown-6 (19), 2,6-pyrido-18-crown-6 (20), and 1,3-benzo-18-crown-5 (21). The results suggest that those ligand systems whose organization of binding sites before and after complexation are the most similar show the highest structural recognition toward the anions

  1. Mitochondrial Akt Regulation of Hypoxic Tumor Reprogramming.

    Science.gov (United States)

    Chae, Young Chan; Vaira, Valentina; Caino, M Cecilia; Tang, Hsin-Yao; Seo, Jae Ho; Kossenkov, Andrew V; Ottobrini, Luisa; Martelli, Cristina; Lucignani, Giovanni; Bertolini, Irene; Locatelli, Marco; Bryant, Kelly G; Ghosh, Jagadish C; Lisanti, Sofia; Ku, Bonsu; Bosari, Silvano; Languino, Lucia R; Speicher, David W; Altieri, Dario C

    2016-08-01

    Hypoxia is a universal driver of aggressive tumor behavior, but the underlying mechanisms are not completely understood. Using a phosphoproteomics screen, we now show that active Akt accumulates in the mitochondria during hypoxia and phosphorylates pyruvate dehydrogenase kinase 1 (PDK1) on Thr346 to inactivate the pyruvate dehydrogenase complex. In turn, this pathway switches tumor metabolism toward glycolysis, antagonizes apoptosis and autophagy, dampens oxidative stress, and maintains tumor cell proliferation in the face of severe hypoxia. Mitochondrial Akt-PDK1 signaling correlates with unfavorable prognostic markers and shorter survival in glioma patients and may provide an "actionable" therapeutic target in cancer. PMID:27505672

  2. Synthetic sulfoglycolipids targeting the serine-threonine protein kinase Akt.

    Science.gov (United States)

    Costa, Barbara; Dangate, Milind; Vetro, Maria; Donvito, Giulia; Gabrielli, Luca; Amigoni, Loredana; Cassinelli, Giuliana; Lanzi, Cinzia; Ceriani, Michela; De Gioia, Luca; Filippi, Giulia; Cipolla, Laura; Zaffaroni, Nadia; Perego, Paola; Colombo, Diego

    2016-08-15

    The serine-threonine protein kinase Akt, also known as protein kinase B, is a key component of the phosphoinositide 3-kinase (PI3K)-Akt-mTOR axis. Deregulated activation of this pathway is frequent in human tumors and Akt-dependent signaling appears to be critical in cell survival. PI3K activation generates 3-phosphorylated phosphatidylinositols that bind Akt pleckstrin homology (PH) domain. The blockage of Akt PH domain/phosphoinositides interaction represents a promising approach to interfere with the oncogenic potential of over-activated Akt. In the present study, phosphatidyl inositol mimics based on a β-glucoside scaffold have been synthesized as Akt inhibitors. The compounds possessed one or two lipophilic moieties of different length at the anomeric position of glucose, and an acidic or basic group at C-6. Docking studies, ELISA Akt inhibition assays, and cellular assays on different cell models highlighted 1-O-octadecanoyl-2-O-β-d-sulfoquinovopyranosyl-sn-glycerol as the best Akt inhibitor among the synthesized compounds, which could be considered as a lead for further optimization in the design of Akt inhibitors.

  3. A specific p47phox -serine phosphorylated by convergent MAPKs mediates neutrophil NADPH oxidase priming at inflammatory sites

    DEFF Research Database (Denmark)

    Dang, Pham My-Chan; Stensballe, Allan; Boussetta, Tarek;

    2006-01-01

    mass spectrometry to show that GM-CSF and TNF-alpha induce phosphorylation of Ser345 on p47phox, a cytosolic component of NADPH oxidase, in human neutrophils. As Ser345 is located in the MAPK consensus sequence, we tested the effects of MAPK inhibitors. Inhibitors of the ERK1/2 pathway abrogated GM...... containing a TAT-p47phox-Ser345 sequence. Furthermore, ROS generation, p47phox-Ser345 phosphorylation, and ERK1/2 and p38 MAPK phosphorylation were increased in synovial neutrophils from rheumatoid arthritis (RA) patients, and TAT-Ser345 peptide inhibited ROS production by these primed neutrophils...

  4. Akt1 intramitochondrial cycling is a crucial step in the redox modulation of cell cycle progression.

    Directory of Open Access Journals (Sweden)

    Valeria Gabriela Antico Arciuch

    Full Text Available Akt is a serine/threonine kinase involved in cell proliferation, apoptosis, and glucose metabolism. Akt is differentially activated by growth factors and oxidative stress by sequential phosphorylation of Ser(473 by mTORC2 and Thr(308 by PDK1. On these bases, we investigated the mechanistic connection of H(2O(2 yield, mitochondrial activation of Akt1 and cell cycle progression in NIH/3T3 cell line with confocal microscopy, in vivo imaging, and directed mutagenesis. We demonstrate that modulation by H(2O(2 entails the entrance of cytosolic P-Akt1 Ser(473 to mitochondria, where it is further phosphorylated at Thr(308 by constitutive PDK1. Phosphorylation of Thr(308 in mitochondria determines Akt1 passage to nuclei and triggers genomic post-translational mechanisms for cell proliferation. At high H(2O(2, Akt1-PDK1 association is disrupted and P-Akt1 Ser(473 accumulates in mitochondria in detriment to nuclear translocation; accordingly, Akt1 T308A is retained in mitochondria. Low Akt1 activity increases cytochrome c release to cytosol leading to apoptosis. As assessed by mass spectra, differential H(2O(2 effects on Akt1-PDK interaction depend on the selective oxidation of Cys(310 to sulfenic or cysteic acids. These results indicate that Akt1 intramitochondrial-cycling is central for redox modulation of cell fate.

  5. Sustained activation of Akt elicits mitochondrial dysfunction to block Plasmodium falciparum infection in the mosquito host.

    Directory of Open Access Journals (Sweden)

    Shirley Luckhart

    2013-02-01

    Full Text Available The overexpression of activated, myristoylated Akt in the midgut of female transgenic Anopheles stephensi results in resistance to infection with the human malaria parasite Plasmodium falciparum but also decreased lifespan. In the present study, the understanding of mitochondria-dependent midgut homeostasis has been expanded to explain this apparent paradox in an insect of major medical importance. Given that Akt signaling is essential for cell growth and survival, we hypothesized that sustained Akt activation in the mosquito midgut would alter the balance of critical pathways that control mitochondrial dynamics to enhance parasite killing at some cost to survivorship. Toxic reactive oxygen and nitrogen species (RNOS rise to high levels in the midgut after blood feeding, due to a combination of high NO production and a decline in FOXO-dependent antioxidants. Despite an apparent increase in mitochondrial biogenesis in young females (3 d, energy deficiencies were apparent as decreased oxidative phosphorylation and increased [AMP]/[ATP] ratios. In addition, mitochondrial mass was lower and accompanied by the presence of stalled autophagosomes in the posterior midgut, a critical site for blood digestion and stem cell-mediated epithelial maintenance and repair, and by functional degradation of the epithelial barrier. By 18 d, the age at which An. stephensi would transmit P. falciparum to human hosts, mitochondrial dysfunction coupled to Akt-mediated repression of autophagy/mitophagy was more evident and midgut epithelial structure was markedly compromised. Inhibition of RNOS by co-feeding of the nitric-oxide synthase inhibitor L-NAME at infection abrogated Akt-dependent killing of P. falciparum that begins within 18 h of infection in 3-5 d old mosquitoes. Hence, Akt-induced changes in mitochondrial dynamics perturb midgut homeostasis to enhance parasite resistance and decrease mosquito infective lifespan. Further, quality control of mitochondrial

  6. [Relationship between PTEN mutations and protein kinase B phosphorylation caused by insulin or recombinant human epidermal growth factor stimulation].

    Science.gov (United States)

    Zhong, Hailan; Hu, Xianfu; Lin, Jianhua

    2016-08-01

    Objective To study the effect of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) mutations on protein kinase B (Akt) phosphorylation of CNE-1 nasopharyngeal carcinoma cell line. Methods CNE-1 cells were cultured in RPMI1640 medium containing 100 mL/L fetal calf serum, and then transfected with wild-type PTEN (wtPTEN), mutant PTEN C124S and mutant PTEN G129E plasmid separately. After overnight serum starvation, the cells were stimulated with 0.15 IU/mL insulin or 0.3 μg/mL recombinant human epidermal growth factor (rhEGF). At last, Akt phosphorylation was evaluated by Western blotting. Results Insulin or rhEGF stimulation led to Akt activation in CNE-1 cells. The wtPTEN inhibited insulin- or rhEGF-stimulated phosphorylation of Akt. PTEN C124S mutant activated insulin-stimulated phosphorylation of Akt, but not rhEGF-stimulated phosphorylation of Akt. PTEN G129E mutant inhibited insulin-stimulated phosphorylation of Akt. Conclusion The wtPTEN inhibited insulin- or rhEGF-stimulated phosphorylation of Akt, while PTEN C124S and G129E mutants failed to activate the phosphorylation of Akt consistently. This suggested PTEN mutations might not be correlated with activated Akt. PMID:27412938

  7. The conserved dual phosphorylation sites of the Candida albicans Hog1 protein are crucial for white-opaque switching, mating, and pheromone-stimulated cell adhesion.

    Science.gov (United States)

    Chang, Wen-Han; Liang, Shen-Huan; Deng, Fu-Sheng; Lin, Ching-Hsuan

    2016-08-01

    Candida albicans is an opportunistic human pathogen capable of causing life-threatening infections in immunocompromised patients. C. albicans has a unique morphological transition between white and opaque phases. These two cells differ in virulence, mating capability, biofilm formation, and host-cell interaction. Previous studies revealed that deletion of the SSK2, PBS2, or HOG1 gene resulted in 100% opaque cell formation and suppressed the mating response. Thr-174 and Tyr-176 of the Hog1 protein are important phosphoacceptors and can be activated in response to stimuli. In this study, we first demonstrated the importance of two conserved phosphorylation sites in white-opaque switching, mating, and pheromone-stimulated cell adhesion. Six Hog1 point-mutated strains were generated, including nonphosphorylated strains (Hog1(T174A), Hog1(Y176F), and Hog1(T174A,Y176F)) and negatively charged phosphorylated strains (Hog1(T174D), Hog1(Y176D), and Hog1(T174D,Y176D)). Point mutation on Thr-174, Tyr-176 or in combination with the Hog1 protein in C. albicans MTL homozygous strains stimulated opaque cell formation at a frequency of 100%. Furthermore, mating projections of point-mutated strains were significantly shorter and their mating efficiencies and pheromone-stimulated cell adhesive numbers were lower than those of the wild-type. By investigating the effects of Hog1 phosphorylation in ssk1Δ and sln1Δ, we also demonstrate that the phosphorylation intensity of Hog1p is directly involved in the white-opaque switching. Taken together, the results of our study demonstrate that dual phosphorylation sites of C. albicans are crucial for white-opaque transition, sexual mating, and pheromone-induced cell adhesion. PMID:27118797

  8. Nitric oxide synthase and breast cancer: role of TIMP-1 in NO-mediated Akt activation.

    Directory of Open Access Journals (Sweden)

    Lisa A Ridnour

    Full Text Available Prediction of therapeutic response and cancer patient survival can be improved by the identification of molecular markers including tumor Akt status. A direct correlation between NOS2 expression and elevated Akt phosphorylation status has been observed in breast tumors. Tissue inhibitor matrix metalloproteinase-1 (TIMP-1 has been proposed to exert oncogenic properties through CD63 cell surface receptor pathway initiation of pro-survival PI3k/Akt signaling. We employed immunohistochemistry to examine the influence of TIMP-1 on the functional relationship between NOS2 and phosphorylated Akt in breast tumors and found that NOS2-associated Akt phosphorylation was significantly increased in tumors expressing high TIMP-1, indicating that TIMP-1 may further enhance NO-induced Akt pathway activation. Moreover, TIMP-1 silencing by antisense technology blocked NO-induced PI3k/Akt/BAD phosphorylation in cultured MDA-MB-231 human breast cancer cells. TIMP-1 protein nitration and TIMP-1/CD63 co-immunoprecipitation was observed at NO concentrations that induced PI3k/Akt/BAD pro-survival signaling. In the survival analysis, elevated tumor TIMP-1 predicted poor patient survival. This association appears to be mainly restricted to tumors with high NOS2 protein. In contrast, TIMP-1 did not predict poor survival in patient tumors with low NOS2 expression. In summary, our findings suggest that tumors with high TIMP-1 and NOS2 behave more aggressively by mechanisms that favor Akt pathway activation.

  9. 20-Hydroxyeicosatetraenoic acid impairs endothelial insulin signaling by inducing phosphorylation of the insulin receptor substrate-1 at Ser616.

    Directory of Open Access Journals (Sweden)

    Xuguang Li

    Full Text Available 20-Hydroxyeicosatetraenoic acid (20-HETE induces endothelial dysfunction and is correlated with diabetes. This study was designed to investigate the effects of 20-HETE on endothelial insulin signaling.Human umbilical vein endothelial cells (HUVECs or C57BL/6J mice were treated with 20-HETE in the presence or absence of insulin, and p-ERK1/2, p-JNK, IRS-1/PI3K/AKT/eNOS pathway, were examined in endothelial cells and aortas by immunoblotting. eNOS activity and nitric oxide production were measured. 20-HETE increased ERK1/2 phosphorylation and IRS-1 phosphorylation at Ser616; these effects were reversed by ERK1/2 inhibition. We further observed that 20-HETE treatment resulted in impaired insulin-stimulated IRS-1 phosphorylation at Tyr632 and subsequent PI3-kinase/Akt activation. Furthermore, 20-HETE treatment blocked insulin-stimulated phosphorylation of eNOS at the stimulatory Ser1177 site, eNOS activation and NO production; these effects were reversed by inhibiting ERK1/2. Treatment of C57BL/6J mice with 20-HETE resulted in ERK1/2 activation and impaired insulin-dependent activation of the IRS-1/PI3K/Akt/eNOS pathway in the aorta. Our data suggest that the 20-HETE activation of IRS-1 phosphorylation at Ser616 is dependent on ERK1/2 and leads to impaired insulin-stimulated vasodilator effects that are mediated by the IRS-1/PI3K/AKT/eNOS pathway.

  10. Pdx1 is post-translationally modified in vivo and serine 61 is the principal site of phosphorylation

    DEFF Research Database (Denmark)

    Frogne, Thomas; Sylvestersen, Kathrine Beck; Kubicek, Stefan;

    2012-01-01

    signaling. Several studies have shown that post-translational modifications are regulating Pdx1 activity through intracellular localization and binding to co-factors. Understanding the signaling cues converging on Pdx1 and modulating its activity is therefore an attractive approach in diabetes treatment. We...... charged protein species to be examined simultaneously. In all eukaryotic cells tested we find that the Pdx1 protein separates into four distinct peaks whereas Pdx1 protein from bacteria only produces one peak. Of the four peaks in eukaryotic cells we correlate one of them to a phosphorylation Using...... alanine scanning and mass spectrometry we map this phosphorylation to serine 61 in both Min6 cells and in exogenous Pdx1 over-expressed in HEK293 cells. A single phosphorylation is also present in cultured islets but it remains unaffected by changes in glucose levels. It is present during embryogenesis...

  11. Curcumin inhibits Akt/mTOR signaling through protein phosphatase-dependent mechanism*

    OpenAIRE

    Yu, Siwang; Shen, Guoxiang; Khor, Tin Oo; Kim, Jung-Hwan; Kong, Ah-Ng

    2008-01-01

    Akt/mTOR signaling plays an important role in tumorigenesis and is dysregulated in many tumors, especially metastatic prostate cancers. Curcumin has been shown to effectively prevent or inhibit prostate cancer in vivo and inhibit Akt/mTOR signaling in vitro, but the mechanism(s) remains unclear. Here we show that curcumin concentration- and time-dependently inhibited the phosphorylation of Akt, mTOR, and their downstream substrates in human prostate cancer PC-3 cells, and this inhibitory effe...

  12. Detection of phospho-sites generated by protein kinase CK2 in CFTR: mechanistic aspects of Thr1471 phosphorylation.

    Directory of Open Access Journals (Sweden)

    Andrea Venerando

    Full Text Available By mass spectrometry analysis of mouse Cystic Fibrosis Transmembrane-conductance Regulator (mCFTR expressed in yeast we have detected 21 phosphopeptides accounting for 22 potential phospho-residues, 12 of which could be unambiguously assigned. Most are conserved in human CFTR (hCFTR and the majority cluster in the Regulatory Domain, lying within consensus sequences for PKA, as identified in previous mammalian studies. This validates our yeast expression model. A number of phospho-residues were novel and human conserved, notably mouse Ser670, Ser723, Ser737, and Thr1467, that all lie in acidic sequences, compatible with their phosphorylation by protein kinase CK2. Thr1467 is localized in the C-terminal tail, embedded in a functionally important and very acidic sequence (EETEEE which displays an optimal consensus for protein kinase CK2. Herein, we show that Thr1467, homologous to human Thr1471 is readily phosphorylated by CK2. Indeed a 42 amino acid peptide encompassing the C-terminal segment of human CFTR is readily phosphorylated at Thr1471 with favorable kinetics (Km 1.7 µM by CK2 holoenzyme, but neither by its isolated catalytic subunit nor by other acidophilic Ser/Thr kinases (CK1, PLK2/3, GCK/FAM20C. Our finding that by treating CFTR expressing BHK cells with the very specific CK2 inhibitor CX4945, newly synthesized wild type CFTR (and even more its Phe508del mutant accumulates more abundantly than in the absence of CK2 inhibitor, supports the conclusion that phosphorylation of CFTR by CK2 correlates with decreased stability of the protein.

  13. Essential role of PH domain and leucine-rich repeat protein phosphatase 2 in Nrf2 suppression via modulation of Akt/GSK3β/Fyn kinase axis during oxidative hepatocellular toxicity.

    Science.gov (United States)

    Rizvi, F; Shukla, S; Kakkar, P

    2014-01-01

    Instances of sustained oxidative activity have been shown to involve dysregulation of Nrf2-mediated transcriptional induction; however, mechanisms warranting Nrf2-repression remain unclear. In this study, using primary rat hepatocytes, we have attempted to identify factors that may negatively influence Nrf2 survival pathway. Though studies indicate a conspicuous association between Akt and Nrf2, a confirmatory link between the two is unaddressed. On inhibiting PI3K/Akt pathway, we observed compromised activities of antioxidant and detoxification enzymes culminating in oxidative cytotoxicity. This was accompanied by reduced nuclear retention of Nrf2 and its ARE binding affinity, increased Nrf2 ubiquitination and concurrent decline in its downstream targets. Moreover, Akt inhibition enhanced nuclear translocation as well as phosphorylation of Fyn kinase, an enzyme linked to Nrf2 degradation, by relieving GSK3β from phosphorylation-mediated repression. The involvement of Akt and Fyn kinase in influencing Nrf2 signaling was further confirmed in oxidatively stressed hepatocytes by using tert-butyl hydroperoxide (tBHP). tBHP-induced decrease in Nrf2 levels was associated with enhanced Fyn kinase phosphorylation, Fyn kinase nuclear translocation and decreased levels of phosphorylated GSK3β(Ser9) in a time-dependent manner. Interestingly, tBHP induced site-specific deactivation of Akt as only Akt(Ser473) phosphorylation was observed to be affected. Further, protein expression as well as nuclear localization of PHLPP2, a phosphatase specific for Akt(Ser473), was found to be significantly enhanced in tBHP-stressed hepatocytes. Silencing of PHLPP2 not only resulted in considerable restoration of Nrf2 signaling, enhanced Nrf2-ARE binding and reduced Nrf2 ubiquitination but also significantly suppressed tBHP-induced ROS generation and alterations in mitochondrial permeability. We infer that cellular PHLPP2 levels may aggravate oxidative toxicity by suppressing Nrf2/ARE

  14. MOLECULAR CLONING, EXPRESSION AND OVEREXPRESSION ANALYSIS OF AKT3 (PKBγ) IN ZEBRAFISH%斑马鱼akt3基因的克隆及其表达图谱与过表达分析

    Institute of Scientific and Technical Information of China (English)

    谌爽; 周建峰; 卢玲; 刘云章; 李筠

    2011-01-01

    采用RT-PCR和RACE相结合的方法,克隆得到了斑马鱼的akt3/pkbγ基因,其cDNA全长为2874 bp,编码479个氨基酸.斑马鱼Akt3具有Akt家族成员间保守的PH结构域、催化活性结构域和调节结构域以及两个保守的磷酸化位点Thr305和Ser472.与已发表的人、大鼠、小鼠的Akt3氨基酸序列比较,相似性分别为95.8%、94.7%和95.4%.对斑马鱼早期胚胎进行RT-PCR检测显示,akt3在0--4hpf(hours post fertilization)含量水平较高,6hpf到12hpf降低至较低水平,16hpf后表达量开始逐渐上升,60hpf至96hpf则稳定在较高水平.原位杂交结果表明:akt3在2hpf至96hpf的胚胎中整体都有表达,没有组织特异性.在成鱼中,除鳃部外,akt3在所检测的其他各组织器官中均有表达,在脑部和卵巢表达量较高;利用显微注射持续表达myr-akt3 mRNA研究其功能充分性时结果显示,过量表达斑马鱼akt3 mRNA能使斑马鱼胚胎发育滞后且伴随着尾部短粗、体节模糊、尾末端膨大甚至严重缩短等不同程度畸形.而在斑马鱼myr-akt3注射组发育至24hpf时观察(以排除akt3造成的发育延迟的影响),发现注射过akt3的斑马鱼胚胎的脑部厚度较对照组显著增大,表明akt3对斑马鱼胚胎脑部尺寸发育有影响.%In this study, an akt3/pkby cDNA in zebrafish, Danio rerio, were isolated and identified by reverse transcription polymerase chain reaction and rapid amplification of cDNA ends (RACE) methods. The full length cDNA of zebrafish akt3 comprised 2874 base pairs (bp) with an open reading frame (ORF) of 1440 bp, encoding 479 amino acids. Analysis of the deduced amino acid sequences revealed that zebrafish Akt3 contained all three domains and two phos-phorylation sites (Thr305 and Ser472) conserved among Akt family members, and showed high similarity with known sequence from human Akt3 (95.8%), rat Akt3 (94.7%) and mouse Akt3 (95.4%). Analyzing embryos of different development stages by RT-PCR displayed

  15. PI3K / Akt signaling regulates epithelialmesenchymal transition of peritoneal mesothelial cells in peritoneal dialysis

    Institute of Scientific and Technical Information of China (English)

    彭翔

    2014-01-01

    Objective To investigate the role of PI3K/Akt signaling in the regulation of epithelial-mesenchymal transition(EMT)of peritoneal mesothelial cells(PMCs)in peritoneal dialysis in vitro and in vivo.Methods The level of phosphorylated serine/threonine kinase Akt and the expression of EMT associated gene and protein,including ZO-1,Vimentin and FN,were measured in mice EMT model.In vitro study,phosphorylation level and

  16. The Akt1/IL-6/STAT3 pathway regulates growth of lung tumor initiating cells.

    Science.gov (United States)

    Malanga, Donatella; De Marco, Carmela; Guerriero, Ilaria; Colelli, Fabiana; Rinaldo, Nicola; Scrima, Marianna; Mirante, Teresa; De Vitis, Claudia; Zoppoli, Pietro; Ceccarelli, Michele; Riccardi, Miriam; Ravo, Maria; Weisz, Alessandro; Federico, Antonella; Franco, Renato; Rocco, Gaetano; Mancini, Rita; Rizzuto, Antonia; Gulletta, Elio; Ciliberto, Gennaro; Viglietto, Giuseppe

    2015-12-15

    Here we report that the PI3K/Akt1/IL-6/STAT3 signalling pathway regulates generation and stem cell-like properties of Non-Small Cell Lung Cancer (NSCLC) tumor initiating cells (TICs). Mutant Akt1, mutant PIK3CA or PTEN loss enhances formation of lung cancer spheroids (LCS), self-renewal, expression of stemness markers and tumorigenic potential of human immortalized bronchial cells (BEAS-2B) whereas Akt inhibition suppresses these activities in established (NCI-H460) and primary NSCLC cells. Matched microarray analysis of Akt1-interfered cells and LCSs identified IL-6 as a critical target of Akt signalling in NSCLC TICs. Accordingly, suppression of Akt in NSCLC cells decreases IL-6 levels, phosphorylation of IkK and IkB, NF-kB transcriptional activity, phosphorylation and transcriptional activity of STAT3 whereas active Akt1 up-regulates them. Exposure of LCSs isolated from NSCLC cells to blocking anti-IL-6 mAbs, shRNA to IL-6 receptor or to STAT3 markedly reduces the capability to generate LCSs, to self-renew and to form tumors, whereas administration of IL-6 to Akt-interfered cells restores the capability to generate LCSs. Finally, immunohistochemical studies in NSCLC patients demonstrated a positive correlative trend between activated Akt, IL-6 expression and STAT3 phosphorylation (n = 94; p cells in NSCLC.

  17. Clk/STY (cdc2-like kinase 1 and Akt regulate alternative splicing and adipogenesis in 3T3-L1 pre-adipocytes.

    Directory of Open Access Journals (Sweden)

    Pengfei Li

    Full Text Available The development of adipocytes from their progenitor cells requires the action of growth factors signaling to transcription factors to induce the expression of adipogenic proteins leading to the accumulation of lipid droplets, induction of glucose transport, and secretion of adipokines signaling metabolic events throughout the body. Murine 3T3-L1 pre-adipocytes sequentially express all the proteins necessary to become mature adipocytes throughout an 8-10 day process initiated by a cocktail of hormones. We examined the role of Clk/STY or Clk1, a cdc2-like kinase, in adipogenesis since it is known to be regulated by Akt, a pivotal kinase in development. Inhibition of Clk1 by a specific inhibitor, TG003, blocked alternative splicing of PKCβII and expression of PPARγ1 and PPARγ2. SiRNA depletion of Clk1 resulted in early expression of PKCβII and sustained PKCβI expression. Since Clk1 is a preferred Akt substrate, required for phosphorylation of splicing factors, mutation of Clk1 Akt phosphorylation sites was undertaken. Akt sites on Clk1 are in the serine/arginine-rich domain and not the kinase domain. Mutation of single and multiple sites resulted in dysregulation of PKCβII, PKCβI, and PPARγ1&2 expression. Additionally, adipogenesis was blocked as assessed by Oil Red O staining, adiponectin, and Glut1 and 4 expression. Immunofluorescence microscopy revealed that Clk1 triple mutant cDNA, transfected into pre-adipocytes, resulted in excluding SRp40 (SFSR6 from co-localizing to the nucleus with PFS, a perispeckle specific protein. This study demonstrates the role of Akt and Clk1 kinases in the early differentiation of 3T3-L1 cells to adipocytes.

  18. A Site-Specific Phosphorylation of the Focal Adhesion Kinase Controls the Formation of Spheroid Cell Clusters

    DEFF Research Database (Denmark)

    Beck, Hans Christian; Gosau, Martin; Kristensen, Lars Peter;

    2014-01-01

    Human dental follicle cells (DFCs) are ectomesenchymal multipotent stem cells that form spheroid cell clusters (SCCs) under serum free medium cell culture conditions (SFM). Until today, molecular mechanisms for the formation of SCCs are unknown. In this study a quantitative phosphoproteomics...... kinase (FAK) signaling pathway. In addition to the phosphoproteomics approach we showed that a specific phosphorylation of FAK (Y397) was required for the formation of SCCs. In conclusion, this study disclosed the phosphoproteome of SCCs for the first time and showed that the FAK signaling pathway...

  19. PKC{eta} is a negative regulator of AKT inhibiting the IGF-I induced proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Shahaf, Galit; Rotem-Dai, Noa; Koifman, Gabriela; Raveh-Amit, Hadas; Frost, Sigal A.; Livneh, Etta, E-mail: etta@bgu.ac.il

    2012-04-15

    The PI3K-AKT pathway is frequently activated in human cancers, including breast cancer, and its activation appears to be critical for tumor maintenance. Some malignant cells are dependent on activated AKT for their survival; tumors exhibiting elevated AKT activity show sensitivity to its inhibition, providing an Achilles heel for their treatment. Here we show that the PKC{eta} isoform is a negative regulator of the AKT signaling pathway. The IGF-I induced phosphorylation on Ser473 of AKT was inhibited by the PKC{eta}-induced expression in MCF-7 breast adenocarcinoma cancer cells. This was further confirmed in shRNA PKC{eta}-knocked-down MCF-7 cells, demonstrating elevated phosphorylation on AKT Ser473. While PKC{eta} exhibited negative regulation on AKT phosphorylation it did not alter the IGF-I induced ERK phosphorylation. However, it enhanced ERK phosphorylation when stimulated by PDGF. Moreover, its effects on IGF-I/AKT and PDGF/ERK pathways were in correlation with cell proliferation. We further show that both PKC{eta} and IGF-I confer protection against UV-induced apoptosis and cell death having additive effects. Although the protective effect of IGF-I involved activation of AKT, it was not affected by PKC{eta} expression, suggesting that PKC{eta} acts through a different route to increase cell survival. Hence, our studies show that PKC{eta} provides negative control on AKT pathway leading to reduced cell proliferation, and further suggest that its presence/absence in breast cancer cells will affect cell death, which could be of therapeutic value.

  20. PKCη is a negative regulator of AKT inhibiting the IGF-I induced proliferation

    International Nuclear Information System (INIS)

    The PI3K-AKT pathway is frequently activated in human cancers, including breast cancer, and its activation appears to be critical for tumor maintenance. Some malignant cells are dependent on activated AKT for their survival; tumors exhibiting elevated AKT activity show sensitivity to its inhibition, providing an Achilles heel for their treatment. Here we show that the PKCη isoform is a negative regulator of the AKT signaling pathway. The IGF-I induced phosphorylation on Ser473 of AKT was inhibited by the PKCη-induced expression in MCF-7 breast adenocarcinoma cancer cells. This was further confirmed in shRNA PKCη-knocked-down MCF-7 cells, demonstrating elevated phosphorylation on AKT Ser473. While PKCη exhibited negative regulation on AKT phosphorylation it did not alter the IGF-I induced ERK phosphorylation. However, it enhanced ERK phosphorylation when stimulated by PDGF. Moreover, its effects on IGF-I/AKT and PDGF/ERK pathways were in correlation with cell proliferation. We further show that both PKCη and IGF-I confer protection against UV-induced apoptosis and cell death having additive effects. Although the protective effect of IGF-I involved activation of AKT, it was not affected by PKCη expression, suggesting that PKCη acts through a different route to increase cell survival. Hence, our studies show that PKCη provides negative control on AKT pathway leading to reduced cell proliferation, and further suggest that its presence/absence in breast cancer cells will affect cell death, which could be of therapeutic value.

  1. Aging-associated dysfunction of Akt/protein kinase B: S-nitrosylation and acetaminophen intervention.

    Directory of Open Access Journals (Sweden)

    Miaozong Wu

    Full Text Available BACKGROUND: Aged skeletal muscle is characterized by an increased incidence of metabolic and functional disorders, which if allowed to proceed unchecked can lead to increased morbidity and mortality. The mechanism(s underlying the development of these disorders in aging skeletal muscle are not well understood. Protein kinase B (Akt/PKB is an important regulator of cellular metabolism and survival, but it is unclear if aged muscle exhibits alterations in Akt function. Here we report a novel dysfunction of Akt in aging muscle, which may relate to S-nitrosylation and can be prevented by acetaminophen intervention. PRINCIPAL FINDINGS: Compared to 6- and 27-month rats, the phosphorylation of Akt (Ser473 and Thr308 was higher in soleus muscles of very aged rats (33-months. Paradoxically, these increases in Akt phosphorylation were associated with diminished mammalian target of rapamycin (mTOR phosphorylation, along with decreased levels of insulin receptor beta (IR-beta, phosphoinositide 3-kinase (PI3K, phosphatase and tensin homolog deleted on chromosome 10 (PTEN and phosphorylation of phosphoinositide-dependent kinase-1 (PDK1 (Ser241. In vitro Akt kinase measurements and ex vivo muscle incubation experiments demonstrated age-related impairments of Akt kinase activity, which were associated with increases in Akt S-nitrosylation and inducible nitric oxide synthase (iNOS. Impairments in Akt function occurred parallel to increases in myocyte apoptosis and decreases in myocyte size and the expression of myosin and actin. These age-related disorders were attenuated by treating aged (27-month animals with acetaminophen (30 mg/kg body weight/day for 6-months. CONCLUSIONS: These data demonstrate that Akt dysfunction and increased S-nitrosylation of Akt may contribute to age-associated disorders in skeletal muscle and that acetaminophen may be efficacious for the treatment of age-related muscle dysfunction.

  2. Preparation of Na+,K+-ATPase with near maximal specific activity and phosphorylation capacity: evidence that the reaction mechanism involves all of the sites.

    Science.gov (United States)

    Martin, D W; Sachs, J R

    1999-06-01

    The phosphorylation capacity of Na+,K+-ATPase preparations in common use is much less than expected on the basis of the molecular weight of the enzyme deduced from cDNA sequences. This has led to the popularity of half-of-the-sites or flip-flop models for the enzyme reaction mechanism. We have prepared Na+,K+-ATPase from nasal salt glands of salt-adapted ducks which has a phosphorylation capacity and specific activity near the theoretical maxima. Preparations with specific activities of >60 micromol (mg of protein)-1 min-1 at 37 degrees C had phosphorylation capacities of >60 nmol/mg of protein, and the rate of turnover of the enzyme was 9690 min-1, within the range reported for the enzyme from other sources. The fraction of the maximal specific activity of the enzyme compared well with the fraction of the protein on SDS-PAGE which was alpha and beta chains, especially at the highest specific activity which indicates that all of the alphabeta protomers are active. The gels of the most reactive preparations contained only alpha and beta chains, but less active preparations contained a number of extraneous proteins. The major contaminant was actin. The preparation did not contain any protein which migrated in the molecular weight range of the gamma subunit. The subunit composition of the enzyme was alpha1 and beta1 only. This is the first report of a pure, homogeneous, fully active preparation of the protein. Reaction models which incorporate a half-of-the-sites or flip-flop mechanism do not apply to this enzyme.

  3. Double Mutation at the Putative Protein Kinase C Phosphorylation Sites Thr151 Plus Thr323 in the Mouse LeukotrieneD4 Receptor Eliminates Homologous Desensitization

    Directory of Open Access Journals (Sweden)

    Sune T. Jørgensen

    2013-03-01

    Full Text Available Background/Aims: Signalling via CysLT1 is involved in activation of volume sensitive K+ channels and homologous desensitization of the LTD4 receptor impairs regulatory volume decrease (RVD. The aim is to illustrate the effect of mutation of putative PKC consensus phosphorylation sites in the CysLT1R on desensitization and RVD. Methods: mCysLT1 contains 4 putative PKC consensus phosphorylation sites, and four mutants were created: Thr151Gly, Thr323Gly, Thr151Gly plus Thr323Gly, and Thr236Gly plus Ser243Gly. Functional mCysLT1 receptor activity after injection of in vitro transcribed cRNA into Xenopus laevis oocytes was visualized as a LTD4-evoked, Ca2+-activated Cl- currents recorded by two-electrode voltage clamp. Results: Repetitive LTD4 administration (100 nM desensitized the LTD4-evoked currents in oocytes expressing wild type CysLT1. Single mutations as well as the double mutation Thr236Gly plus Ser243Gly had no or a slight effect on the LTD4 induced desensitization. However, double mutation Thr323Gly plus Thr151Gly prevented the desensitization. As a functional consequence we find that inhibition of PKC accelerates RVD and prevents the inhibitory effect of LTD4-pretreatment on RVD in Ehrlich ascites tumour cells. Conclusion: These data indicate that simultaneous PKC-mediated phosphorylation at the 2nd inner loop (Thr151 and at the C-terminal domain (Thr323 leads to mCysLT1 receptor desensitization and abrogates the RVD response following osmotic cell swelling.

  4. Hepatitis B Virus Core Protein Phosphorylation Sites Affect Capsid Stability and Transient Exposure of the C-terminal Domain.

    Science.gov (United States)

    Selzer, Lisa; Kant, Ravi; Wang, Joseph C-Y; Bothner, Brian; Zlotnick, Adam

    2015-11-20

    Hepatitis B virus core protein has 183 amino acids divided into an assembly domain and an arginine-rich C-terminal domain (CTD) that regulates essential functions including genome packaging, reverse transcription, and intracellular trafficking. Here, we investigated the CTD in empty hepatitis B virus (HBV) T=4 capsids. We examined wild-type core protein (Cp183-WT) and a mutant core protein (Cp183-EEE), in which three CTD serines are replaced with glutamate to mimic phosphorylated protein. We found that Cp183-WT capsids were less stable than Cp183-EEE capsids. When we tested CTD sensitivity to trypsin, we detected two different populations of CTDs differentiated by their rate of trypsin cleavage. Interestingly, CTDs from Cp183-EEE capsids exhibited a much slower rate of proteolytic cleavage when compared with CTDs of Cp183-WT capsids. Cryo-electron microscopy studies of trypsin-digested capsids show that CTDs at five-fold symmetry vertices are most protected. We hypothesize that electrostatic interactions between glutamates and arginines in Cp183-EEE, particularly at five-fold, increase capsid stability and reduce CTD exposure. Our studies show that quasi-equivalent CTDs exhibit different rates of exposure and thus might perform distinct functions during the hepatitis B virus lifecycle. Our results demonstrate a structural role for CTD phosphorylation and indicate crosstalk between CTDs within a capsid particle. PMID:26405031

  5. Predicting phosphorylation sites of Poplar protein%杨树蛋白质磷酸化位点预测

    Institute of Scientific and Technical Information of China (English)

    高光芹; 黄家荣; 周俊朝; 谢鹏芳

    2015-01-01

    以小黑杨磷酸化蛋白质组为研究对象,用人工神经网络表达丝氨酸、苏氨酸等残基位点的磷酸化与氨基酸序列的结构特征之间的非线性关系,建立了BP 人工神经网络模型,并用磷酸化数据对所建模型进行训练和分析,得适宜的结构为21×16 : 8 : 4,拟合准确度为90%,Acc、Sn、Sp、MCC分别为78%、89%、67%、0.57,对比分析结果表明,所建模型具有较强的预测能力.%In this paper, the phosphoproteome of Populus simonii × P nigra was used as the research object. The nonlinear relationship between the structure characteristics of amino acid sequence and phosphorylation of serine and threonine was expressed by artificial neural network. A BP artificial neural network model was established and trained by using the real data on phosphorylation. The appropriate structure is 21 x 16 : 8 : 4, the fitting accuracy is 90%, and the Acc, Sn, Sp, MCC are 78%, 89%, 67%, and 0. 57, respectively. The comparative results show that the model has strong prediction ability.

  6. Identification of the amino acids 300-600 of IRS-2 as 14-3-3 binding region with the importance of IGF-1/insulin-regulated phosphorylation of Ser-573.

    Directory of Open Access Journals (Sweden)

    Sabine S Neukamm

    Full Text Available Phosphorylation of insulin receptor substrate (IRS-2 on tyrosine residues is a key event in IGF-1/insulin signaling and leads to activation of the PI 3-kinase and the Ras/MAPK pathway. Furthermore, phosphorylated serine/threonine residues on IRS-2 can induce 14-3-3 binding. In this study we searched IRS-2 for novel phosphorylation sites and investigated the interaction between IRS-2 and 14-3-3. Mass spectrometry identified a total of 24 serine/threonine residues on IRS-2 with 12 sites unique for IRS-2 while the other residues are conserved in IRS-1 and IRS-2. IGF-1 stimulation led to increased binding of 14-3-3 to IRS-2 in transfected HEK293 cells and this binding was prevented by inhibition of the PI 3-kinase pathway and an Akt/PKB inhibitor. Insulin-stimulated interaction between endogenous IRS-2 and 14-3-3 was observed in rat hepatoma cells and in mice liver after an acute insulin stimulus and refeeding. Using different IRS-2 fragments enabled localization of the IGF-1-dependent 14-3-3 binding region spanning amino acids 300-600. The 24 identified residues on IRS-2 included several 14-3-3 binding candidates in the region 300-600. Single alanine mutants of these candidates led to the identification of serine 573 as 14-3-3 binding site. A phospho-site specific antibody was generated to further characterize serine 573. IGF-1-dependent phosphorylation of serine 573 was reduced by inhibition of PI 3-kinase and Akt/PKB. A negative role of this phosphorylation site was implicated by the alanine mutant of serine 573 which led to enhanced phosphorylation of Akt/PKB in an IGF-1 time course experiment. To conclude, our data suggest a physiologically relevant role for IGF-1/insulin-dependent 14-3-3 binding to IRS-2 involving serine 573.

  7. Acute exercise and physiological insulin induce distinct phosphorylation signatures on TBC1D1 and TBC1D4 in human skeletal muscle

    DEFF Research Database (Denmark)

    Treebak, Jonas Thue; Pehmøller, Christian; Kristensen, Jonas Møller;

    2014-01-01

    We investigated the phosphorylation signatures of two Rab GTPase activating proteins TBC1D1 and TBC1D4 in human skeletal muscle in response to physical exercise and physiological insulin levels induced by a carbohydrate rich meal using a paired experimental design. Eight healthy male volunteers...... in response to physiological stimuli in human skeletal muscle and support the idea that Akt and AMPK are upstream kinases. TBC1D1 phosphorylation signatures were comparable between in vitro contracted mouse skeletal muscle and exercised human muscle, and we show that AMPK was regulating phosphorylation...... of these sites in mouse muscle. Contraction and exercise elicited a different phosphorylation pattern of TBC1D4 in mouse compared with human muscle, and although different circumstances in our experimental setup may contribute to this difference, the observation exemplifies that transferring findings between...

  8. Expression and significance of CD44 and p-AKT in pancreatic head cancer

    OpenAIRE

    Xiaoping, Li; Xiaowei, Zhang; Leizhen, Zheng; Weijian, Guo

    2015-01-01

    Background CD44 and phosphorylated AKT (p-AKT) is a potentially interesting prognostic marker and therapeutic target in pancreatic cancer. The expression of CD44 and p-AKT has been reported to correlate with poor prognosis of pancreatic cancer in most literatures. The purpose of this study is to investigate the roles of CD44 and p-AKT in pancreatic head cancer and their correlation with the prognosis of pancreatic head cancer patients. Methods Forty-eight pancreatic head cancer samples were c...

  9. Protein kinase B (PKB/AKT1) formed signaling complexes with mitochondrial proteins and prevented glycolytic energy dysfunction in cultured cardiomyocytes during ischemia-reperfusion injury.

    Science.gov (United States)

    Deng, Wu; Leu, Hsin-Bang; Chen, Yumay; Chen, Yu-Han; Epperson, Christine M; Juang, Charity; Wang, Ping H

    2014-05-01

    Our previous studies showed that insulin stimulated AKT1 translocation into mitochondria and modulated oxidative phosphorylation complex V in cardiac muscle. This raised the possibility that mitochondrial AKT1 may regulate glycolytic oxidative phosphorylation and mitochondrial function in cardiac muscle cells. The aims of this project were to study the effects of mitochondrial AKT1 signaling on cell survival in stressed cardiomyocytes, to define the effect of mitochondrial AKT1 signaling on glycolytic bioenergetics, and to identify mitochondrial targets of AKT1 signaling in cardiomyocytes. Mitochondrial AKT1 signaling played a protective role against apoptosis and necrosis during ischemia-reperfusion stress, suppressed mitochondrial calcium overload, and alleviated mitochondrial membrane depolarization. Activation of AKT1 signaling in mitochondria increased glucose uptake, enhanced respiration efficiency, reduced superoxide generation, and increased ATP production in the cardiomyocytes. Inhibition of mitochondrial AKT attenuated insulin response, indicating that insulin regulation of ATP production required mitochondrial AKT1 signaling. A proteomic approach was used to reveal 15 novel targets of AKT1 signaling in mitochondria, including pyruvate dehydrogenase complex (PDC). We have confirmed and characterized the association of AKT1 and PDC subunits and verified a stimulatory effect of mitochondrial AKT1 on the enzymatic activity of PDC. These findings suggested that AKT1 formed protein complexes with multiple mitochondrial proteins and improved mitochondrial function in stressed cardiomyocytes. The novel AKT1 signaling targets in mitochondria may become a resource for future metabolism research.

  10. Activation of PI3K/Akt pathway limits JNK-mediated apoptosis during EV71 infection.

    Science.gov (United States)

    Zhang, Hua; Li, Fengqi; Pan, Ziye; Wu, Zhijun; Wang, Yanhong; Cui, Yudong

    2014-11-01

    Apoptosis is frequently induced to inhibit virus replication during infection of Enterovirus 71 (EV71). On the contrary, anti-apoptotic pathway, such as PI3K/Akt pathway, is simultaneously exploited by EV71 to accomplish the viral life cycle. The relationship by which EV71-induced apoptosis and PI3K/Akt signaling pathway remains to be elucidated. In this study, we demonstrated that EV71 infection altered Bax conformation and triggered its redistribution from the cytosol to mitochondria in RD cells. Subsequently, cytochrome c was released from mitochondria to cytosol. We also found that c-Jun NH2-terminal kinase (JNK) was activated during EV71 infection. The JNK specific inhibitor significantly inhibited Bax activation and cytochrome c release, suggesting that EV71-induced apoptosis was involved into a JNK-dependent manner. Meanwhile, EV71-induced Akt phosphorylation involved a PI3K-dependent mechanism. Inhibition of the PI3K/Akt pathway enhanced JNK phosphorylation and the JNK-mediated apoptosis upon EV71 infection. Moreover, PI3K/Akt pathway phosphorylated apoptosis signal-regulating kinase 1 (ASK1) and negatively regulated the ASK1 activity. Knockdown of ASK1 significantly decreased JNK phosphorylation, which implied that ASK1 phosphorylation by Akt inhibited ASK1-mediated JNK activation. Collectively, these data reveal that activation of the PI3K/Akt pathway limits JNK-mediated apoptosis by phosphorylating and inactivating ASK1 during EV71 infection.

  11. Sulfonium Ion Derivatization, Isobaric Stable Isotope Labeling and Data Dependent CID- and ETD-MS/MS for Enhanced Phosphopeptide Quantitation, Identification and Phosphorylation Site Characterization

    Science.gov (United States)

    Lu, Yali; Zhou, Xiao; Stemmer, Paul M.; Reid, Gavin E.

    2012-04-01

    An amine specific peptide derivatization strategy involving the use of novel isobaric stable isotope encoded `fixed charge' sulfonium ion reagents, coupled with an analysis strategy employing capillary HPLC, ESI-MS, and automated data dependent ion trap CID-MS/MS, -MS3, and/or ETD-MS/MS, has been developed for the improved quantitative analysis of protein phosphorylation, and for identification and characterization of their site(s) of modification. Derivatization of 50 synthetic phosphopeptides with S, S'-dimethylthiobutanoylhydroxysuccinimide ester iodide (DMBNHS), followed by analysis using capillary HPLC-ESI-MS, yielded an average 2.5-fold increase in ionization efficiencies and a significant increase in the presence and/or abundance of higher charge state precursor ions compared to the non-derivatized phosphopeptides. Notably, 44% of the phosphopeptides (22 of 50) in their underivatized states yielded precursor ions whose maximum charge states corresponded to +2, while only 8% (4 of 50) remained at this maximum charge state following DMBNHS derivatization. Quantitative analysis was achieved by measuring the abundances of the diagnostic product ions corresponding to the neutral losses of `light' (S(CH3)2) and `heavy' (S(CD3)2) dimethylsulfide exclusively formed upon CID-MS/MS of isobaric stable isotope labeled forms of the DMBNHS derivatized phosphopeptides. Under these conditions, the phosphate group stayed intact. Access for a greater number of peptides to provide enhanced phosphopeptide sequence identification and phosphorylation site characterization was achieved via automated data-dependent CID-MS3 or ETD-MS/MS analysis due to the formation of the higher charge state precursor ions. Importantly, improved sequence coverage was observed using ETD-MS/MS following introduction of the sulfonium ion fixed charge, but with no detrimental effects on ETD fragmentation efficiency.

  12. Analysis of protein phosphorylation using mass spectrometry: deciphering the phosphoproteome

    DEFF Research Database (Denmark)

    Mann, Matthias; Ong, Shao En; Grønborg, Mads;

    2002-01-01

    In signal transduction in eukaryotes, protein phosphorylation is a key event. To understand signaling processes, we must first acquire an inventory of phosphoproteins and their phosphorylation sites under different conditions. Because phosphorylation is a dynamic process, elucidation of signaling...

  13. [PKA-regulated phosphorylation status of S149 and S321 sites of CDC25B inhibits mitosis of fertilized mouse eggs].

    Science.gov (United States)

    Xiao, Jian-Ying; Liu, Chao; Sun, Xiao-Han; Yu, Bing-Zhi

    2012-02-25

    To further test whether protein kinase A (PKA) can affect the mitotic cell cycle, one-cell stage mouse embryos at S phase (22 h after hCG injection) were incubated in M16 medium containing various concentrations of H-89, a PKA inhibitor. With increasing concentrations of H-89 (0-50 μmol/L), the G(2) phase of eggs was decreased and the cleavage rate was accelerated. A concentration of 40 μmol/L H-89 led to all of the mouse eggs entering the M phase of mitosis. Furthermore, to study the role of PKA in regulating the phosphorylation status of S149 and S321 sites of cell division cycle 25B (CDC25B) on one-cell stage fertilized mouse eggs, pBSK-CDC25B-WT, pBSK-CDC25B-S149A, pBSK-CDC25B-S321A and pBSK-CDC25B-S149A/S321A were transcribed into mRNAs in vitro, then mRNAs were microinjected into S phase of mouse fertilized eggs and cultured in M16 medium pretreated with H-89. Then, the cleavage of fertilized eggs, maturation promoting factor (MPF) activity and phosphorylation status of CDC2-Tyr15 were observed. In the presence of 40 μmol/L H-89, the cleavage rate of fertilized eggs in CDC25B-S/A-mRNAs and CDC25B-WT-mRNA injected groups was significantly higher than that in the control groups, and the peak of MPF activity appeared in the CDC25B-S/A-mRNAs and CDC25B-WT-mRNA injected groups earlier than that in the control groups. CDC2-Tyr15 phosphorylation state was consistent with MPF activity. In conclusion, the present study suggests that PKA regulates the early development of mouse embryos by phosphorylation of S149 and S321 of CDC25B, which plays an important role in the regulation of G(2)/M transition in the mitotic cell cycle of fertilized mouse eggs. PMID:22348958

  14. Relaxin in paraventricular nucleus contributes to sympathetic overdrive and hypertension via PI3K-Akt pathway.

    Science.gov (United States)

    Sun, Hai-Jian; Chen, Dan; Han, Ying; Zhou, Ye-Bo; Wang, Jue-Jin; Chen, Qi; Li, Yue-Hua; Gao, Xing-Ya; Kang, Yu-Ming; Zhu, Guo-Qing

    2016-04-01

    Relaxin is recognized as an ovarian polypeptide hormone. Abundant relaxin binding sites are observed in hypothalamic paraventricular nucleus (PVN). This study was conducted to determine the roles and underlying mechanisms of relaxin in the PVN in sympathetic activation and hypertension in spontaneously hypertensive rats (SHR). Experiments were performed in normotensive Wistar-Kyoto rats (WKY) and SHR. Relaxin and its RXFP1 receptors in PVN were up-regulated in SHR. Relaxin-positive neurons existed in both parvocellular and magnocellular parts of the PVN. Presympathetic neurons and AVP neurons in the PVN expressed RXFP1, but not relaxin. Bilateral PVN microinjection of human relaxin-2 increased but anti-relaxin IgG reduced renal sympathetic nerve activity (RSNA), mean arterial pressure (MAP), plasma norepinephrine (NE) and arginine vasopressin (AVP) levels in SHR. The effects of relaxin-2 on RSNA and MAP were abolished by intravenous infusion of ganglionic blocker hexamethonium, and attenuated by AVP V1 receptor antagonist AAVP. Akt phosphorylation was enhanced in SHR, and relaxin-2 stimulated Akt phosphorylation and p85α subunit of PI3K expression. PI3K inhibitor LY294002 or Akt inhibitor MK-2206 abolished the effects of relaxin-2 on the RSNA, MAP and plasma NE, and attenuated the relaxin-2-induced AVP secretion. STAT5a and polymerase II (Pol II) binding to relaxin-promoter were significantly increased in SHR. Chronic PVN infusion of relaxin-2 with osmotic pumps in normal rats induced sympathetic activation, AVP secretion and hypertension accompanied with cardiovascular remodeling. Relaxin in the PVN contributes to sympathetic overdrive and hypertension via PI3K-Akt pathway. PMID:26746861

  15. In Vivo Phosphorylation Site Mapping in Mouse Cardiac Troponin I by High Resolution Top-Down Electron Capture Dissociation Mass Spectrometry: Ser22/23 Are the Only Sites Basally Phosphorylated†

    OpenAIRE

    Ayaz-Guner, Serife; Zhang, Jiang; Li, Lin; Walker, Jeffery W.; Ge, Ying

    2009-01-01

    Cardiac troponin I (cTnI) is the inhibitory subunit of cardiac troponin, a key myofilament regulatory protein complex located on the thin filaments of the contractile apparatus. cTnI is uniquely specific for the heart and is widely used in clinics as a serum biomarker for cardiac injury. Phosphorylation of cTnI plays a critical role in modulating cardiac function. cTnI is known to be regulated by protein kinase A and protein kinase C at five sites, Ser22/Ser23, Ser42/44, and Thr143, primarily...

  16. Protein S blocks the extrinsic apoptotic cascade in tissue plasminogen activator/N-methyl D-aspartate-treated neurons via Tyro3-Akt-FKHRL1 signaling pathway

    Directory of Open Access Journals (Sweden)

    Freeman Robert S

    2011-02-01

    Full Text Available Abstract Background Thrombolytic therapy with tissue plasminogen activator (tPA benefits patients with acute ischemic stroke. However, tPA increases the risk for intracerebral bleeding and enhances post-ischemic neuronal injury if administered 3-4 hours after stroke. Therefore, combination therapies with tPA and neuroprotective agents have been considered to increase tPA's therapeutic window and reduce toxicity. The anticoagulant factor protein S (PS protects neurons from hypoxic/ischemic injury. PS also inhibits N-methyl-D-aspartate (NMDA excitotoxicity by phosphorylating Bad and Mdm2 which blocks the downstream steps in the intrinsic apoptotic cascade. To test whether PS can protect neurons from tPA toxicity we studied its effects on tPA/NMDA combined injury which in contrast to NMDA alone kills neurons by activating the extrinsic apoptotic pathway. Neither Bad nor Mdm2 which are PS's targets and control the intrinsic apoptotic pathway can influence the extrinsic cascade. Thus, based on published data one cannot predict whether PS can protect neurons from tPA/NMDA injury by blocking the extrinsic pathway. Neurons express all three TAM (Tyro3, Axl, Mer receptors that can potentially interact with PS. Therefore, we studied whether PS can activate TAM receptors during a tPA/NMDA insult. Results We show that PS protects neurons from tPA/NMDA-induced apoptosis by suppressing Fas-ligand (FasL production and FasL-dependent caspase-8 activation within the extrinsic apoptotic pathway. By transducing neurons with adenoviral vectors expressing the kinase-deficient Akt mutant AktK179A and a triple FKHRL1 Akt phosphorylation site mutant (FKHRL1-TM, we show that Akt activation and Akt-mediated phosphorylation of FKHRL1, a member of the Forkhead family of transcription factors, are critical for FasL down-regulation and caspase-8 inhibition. Using cultured neurons from Tyro3, Axl and Mer mutants, we show that Tyro3, but not Axl and Mer, mediates

  17. VEGF is upregulated by hypoxia-induced mitogenic factor via the PI-3K/Akt-NF-κB signaling pathway

    Directory of Open Access Journals (Sweden)

    Huang Chuanshu

    2006-03-01

    Full Text Available Abstract Background Hypoxia-induced mitogenic factor (HIMF is developmentally regulated and plays an important role in lung pathogenesis. We initially found that HIMF promotes vascular tubule formation in a matrigel plug model. In this study, we investigated the mechanisms which HIMF enhances expression of vascular endothelial growth factor (VEGF in lung tissues and epithelial cells. Methods Recombinant HIMF protein was intratracheally instilled into adult mouse lungs, VEGF expression was examined by immunohistochemical staining and Western blot. The promoter-luciferase reporter assay, RT-PCR, and Western blot were performed to examine the effects of HIMF on VEGF expression in mouse lung epithelial cell line MLE-12. The activation of NF-kappa B (NF-κB and phosphorylation of Akt, IKK and IκBα were examined by luciferase assay and Western blot, respectively. Results Intratracheal instillation of HIMF protein resulted in significant increase of VEGF, mainly localized to airway epithelial and alveolar type II cells. Deletion of NF-κB binding sites within VEGF promoter abolished HIMF-induced VEGF expression in MLE-12 cells, suggesting that activation of NF-κB is essential for VEGF upregulation induced by HIMF. Stimulation of lung epithelial cells by HIMF resulted in phosphorylation of IKK and IκBα, leading to activation of NF-κB. In addition, HIMF strongly induced Akt phosphorylation, and suppression of Akt activation by specific inhibitors and dominant negative mutants for PI-3K, and IKK or IκBα blocked HIMF-induced NF-κB activation and attenuated HIMF-induced VEGF production. Conclusion These results suggest that HIMF enhances VEGF production in mouse lung epithelial cells in a PI-3K/Akt-NF-κB signaling pathway-dependent manner, and may play critical roles in pulmonary angiogenesis.

  18. Polyunsaturated fatty acids affect the localization and signaling of PIP3/AKT in prostate cancer cells.

    Science.gov (United States)

    Gu, Zhennan; Wu, Jiansheng; Wang, Shihua; Suburu, Janel; Chen, Haiqin; Thomas, Michael J; Shi, Lihong; Edwards, Iris J; Berquin, Isabelle M; Chen, Yong Q

    2013-09-01

    AKT is a serine-threonine protein kinase that plays important roles in cell growth, proliferation and apoptosis. It is activated after binding to phosphatidylinositol phosphates (PIPs) with phosphate groups at positions 3,4 and 3,4,5 on the inositol ring. In spite of extensive research on AKT, one aspect has been largely overlooked, namely the role of the fatty acid chains on PIPs. PIPs are phospholipids composed of a glycerol backbone with fatty acids at the sn-1 and sn-2 position and inositol at the sn-3 position. Here, we show that polyunsaturated fatty acids (PUFAs) modify phospholipid content. Docosahexaenoic acid (DHA), an ω3 PUFA, can replace the fatty acid at the sn-2 position of the glycerol backbone, thereby changing the species of phospholipids. DHA also inhibits AKT(T308) but not AKT(S473) phosphorylation, alters PI(3,4,5)P3 (PIP3) and phospho-AKT(S473) protein localization, decreases pPDPK1(S241)-AKT and AKT-BAD interaction and suppresses prostate tumor growth. Our study highlights a potential novel mechanism of cancer inhibition by ω3 PUFA through alteration of PIP3 and AKT localization and affecting the AKT signaling pathway.

  19. Modification in hydrophobic packing of HAMP domain induces a destabilization of the auto-phosphorylation site in the histidine kinase CpxA.

    Science.gov (United States)

    Martinez, Marlet; Duclert-Savatier, Nathalie; Betton, Jean-Michel; Alzari, Pedro M; Nilges, Michael; Malliavin, Thérèse E

    2016-10-01

    The histidine kinases belong to the family of two-component systems, which serves in bacteria to couple environmental stimuli to adaptive responses. Most of the histidine kinases are homodimers, in which the HAMP and DHp domains assemble into an elongated helical region flanked by two CA domains. Recently, X-ray crystallographic structures of the cytoplasmic region of the Escherichia coli histidine kinase CpxA were determined and a phosphotransferase-defective mutant, M228V, located in HAMP, was identified. In the present study, we recorded 1 μs molecular dynamics trajectories to compare the behavior of the WT and M228V protein dimers. The M228V modification locally induces the appearance of larger voids within HAMP as well as a perturbation of the number of voids within DHp, thus destabilizing the HAMP and DHp hydrophobic packing. In addition, a disruption of the stacking interaction between F403 located in the lid of the CA domain involved in the auto-phosphorylation and R296 located in the interacting DHp region, is more often observed in the presence of the M228V modification. Experimental modifications R296A and R296D of CpxA have been observed to reduce also the CpxA activity. These observations agree with the destabilization of the R296/F403 stacking, and could be the sign of the transmission of a conformational event taking place in HAMP to the auto-phosphorylation site of histidine kinase. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 670-682, 2016. PMID:27124288

  20. HDAC inhibition elicits myocardial protective effect through modulation of MKK3/Akt-1.

    Directory of Open Access Journals (Sweden)

    Ting C Zhao

    Full Text Available We and others have demonstrated that HDAC inhibition protects the heart against myocardial injury. It is known that Akt-1 and MAP kinase play an essential role in modulation of myocardial protection and cardiac preconditioning. Our recent observations have shown that Akt-1 was activated in post-myocardial infarction following HDAC inhibition. However, it remains unknown whether MKK3 and Akt-1 are involved in HDAC inhibition-induced myocardial protection in acute myocardial ischemia and reperfusion injury. We sought to investigate whether the genetic disruption of Akt-1 and MKK3 eliminate cardioprotection elicited by HDAC inhibition and whether Akt-1 is associated with MKK3 to ultimately achieve protective effects. Adult wild type and MKK3⁻/⁻, Akt-1⁻/⁻ mice received intraperitoneal injections of trichostatin A (0.1 mg/kg, a potent inhibitor of HDACs. The hearts were subjected to 30 min myocardial ischemia/30 min reperfusion in the Langendorff perfused heart after twenty four hours to elicit pharmacologic preconditioning. Left ventricular function was measured, and infarct size was determined. Acetylation and phosphorylation of MKK3 were detected and disruption of Akt-1 abolished both acetylation and phosphorylation of MKK3. HDAC inhibition produces an improvement in left ventricular functional recovery, but these effects were abrogated by disruption of either Akt-1 or MKK3. Disruption of Akt-1 or MKK3 abolished the effects of HDAC inhibition-induced reduction of infarct size. Trichostatin A treatment resulted in an increase in MKK3 phosphorylation or acetylation in myocardium. Taken together, these results indicate that stimulation of the MKK3 and Akt-1 pathway is a novel approach to HDAC inhibition -induced cardioprotection.

  1. PI3K-Akt pathway: its functions and alterations in human cancer.

    Science.gov (United States)

    Osaki, M; Oshimura, M; Ito, H

    2004-11-01

    Phosphatidylinositol-3-kinase (PI3K) is a lipid kinase and generates phosphatidylinositol-3,4,5-trisphosphate (PI(3, 4, 5)P3). PI(3, 4, 5)P3 is a second messenger essential for the translocation of Akt to the plasma membrane where it is phosphorylated and activated by phosphoinositide-dependent kinase (PDK) 1 and PDK2. Activation of Akt plays a pivotal role in fundamental cellular functions such as cell proliferation and survival by phosphorylating a variety of substrates. In recent years, it has been reported that alterations to the PI3K-Akt signaling pathway are frequent in human cancer. Constitutive activation of the PI3K-Akt pathway occurs due to amplification of the PIK3C gene encoding PI3K or the Akt gene, or as a result of mutations in components of the pathway, for example PTEN (phosphatase and tensin homologue deleted on chromosome 10), which inhibit the activation of Akt. Several small molecules designed to specifically target PI3K-Akt have been developed, and induced cell cycle arrest or apoptosis in human cancer cells in vitro and in vivo . Moreover, the combination of an inhibitor with various cytotoxic agents enhances the anti-tumor efficacy. Therefore, specific inhibition of the activation of Akt may be a valid approach to treating human malignancies and overcoming the resistance of cancer cells to radiation or chemotherapy. PMID:15505410

  2. Preclinical pharmacology, antitumor activity, and development of pharmacodynamic markers for the novel, potent AKT inhibitor CCT128930.

    Science.gov (United States)

    Yap, Timothy A; Walton, Mike I; Hunter, Lisa-Jane K; Valenti, Melanie; de Haven Brandon, Alexis; Eve, Paul D; Ruddle, Ruth; Heaton, Simon P; Henley, Alan; Pickard, Lisa; Vijayaraghavan, Gowri; Caldwell, John J; Thompson, Neil T; Aherne, Wynne; Raynaud, Florence I; Eccles, Suzanne A; Workman, Paul; Collins, Ian; Garrett, Michelle D

    2011-02-01

    AKT is frequently deregulated in cancer, making it an attractive anticancer drug target. CCT128930 is a novel ATP-competitive AKT inhibitor discovered using fragment- and structure-based approaches. It is a potent, advanced lead pyrrolopyrimidine compound exhibiting selectivity for AKT over PKA, achieved by targeting a single amino acid difference. CCT128930 exhibited marked antiproliferative activity and inhibited the phosphorylation of a range of AKT substrates in multiple tumor cell lines in vitro, consistent with AKT inhibition. CCT128930 caused a G(1) arrest in PTEN-null U87MG human glioblastoma cells, consistent with AKT pathway blockade. Pharmacokinetic studies established that potentially active concentrations of CCT128930 could be achieved in human tumor xenografts. Furthermore, CCT128930 also blocked the phosphorylation of several downstream AKT biomarkers in U87MG tumor xenografts, indicating AKT inhibition in vivo. Antitumor activity was observed with CCT128930 in U87MG and HER2-positive, PIK3CA-mutant BT474 human breast cancer xenografts, consistent with its pharmacokinetic and pharmacodynamic properties. A quantitative immunofluorescence assay to measure the phosphorylation and total protein expression of the AKT substrate PRAS40 in hair follicles is presented. Significant decreases in pThr246 PRAS40 occurred in CCT128930-treated mouse whisker follicles in vivo and human hair follicles treated ex vivo, with minimal changes in total PRAS40. In conclusion, CCT128930 is a novel, selective, and potent AKT inhibitor that blocks AKT activity in vitro and in vivo and induces marked antitumor responses. We have also developed a novel biomarker assay for the inhibition of AKT in human hair follicles, which is currently being used in clinical trials. PMID:21191045

  3. PI3K/Akt is involved in brown adipogenesis mediated by growth differentiation factor-5 in association with activation of the Smad pathway

    Energy Technology Data Exchange (ETDEWEB)

    Hinoi, Eiichi; Iezaki, Takashi; Fujita, Hiroyuki; Watanabe, Takumi; Odaka, Yoshiaki; Ozaki, Kakeru; Yoneda, Yukio, E-mail: yyoneda@p.kanazawa-u.ac.jp

    2014-07-18

    Highlights: • Akt is preferentially phosphorylated in BAT and sWAT of aP2-GDF5 mice. • PI3K/Akt signaling is involved in GDF5-induced brown adipogenesis. • PI3K/Akt signaling regulates GDF5-induced Smad5 phosphorylation. - Abstract: We have previously demonstrated promotion by growth differentiation factor-5 (GDF5) of brown adipogenesis for systemic energy expenditure through a mechanism relevant to activating the bone morphological protein (BMP) receptor/mothers against decapentaplegic homolog (Smad)/peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α) pathway. Here, we show the involvement of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in brown adipogenesis mediated by GDF5. Overexpression of GDF5 in cells expressing adipocyte protein-2 markedly accelerated the phosphorylation of Smad1/5/8 and Akt in white and brown adipose tissues. In brown adipose tissue from heterozygous GDF5{sup Rgsc451} mutant mice expressing a dominant-negative (DN) GDF5 under obesogenic conditions, the basal phosphorylation of Smad1/5/8 and Akt was significantly attenuated. Exposure to GDF5 not only promoted the phosphorylation of both Smad1/5/8 and Akt in cultured brown pre-adipocytes, but also up-regulated Pgc1a and uncoupling protein-1 expression in a manner sensitive to the PI3K/Akt inhibitor Ly294002 as well as retroviral infection with DN-Akt. GDF5 drastically promoted BMP-responsive luciferase reporter activity in a Ly294002-sensitive fashion. Both Ly294002 and DN-Akt markedly inhibited phosphorylation of Smad5 in the nuclei of brown pre-adipocytes. These results suggest that PI3K/Akt signals play a role in the GDF5-mediated brown adipogenesis through a mechanism related to activation of the Smad pathway.

  4. PI3K/Akt is involved in brown adipogenesis mediated by growth differentiation factor-5 in association with activation of the Smad pathway

    International Nuclear Information System (INIS)

    Highlights: • Akt is preferentially phosphorylated in BAT and sWAT of aP2-GDF5 mice. • PI3K/Akt signaling is involved in GDF5-induced brown adipogenesis. • PI3K/Akt signaling regulates GDF5-induced Smad5 phosphorylation. - Abstract: We have previously demonstrated promotion by growth differentiation factor-5 (GDF5) of brown adipogenesis for systemic energy expenditure through a mechanism relevant to activating the bone morphological protein (BMP) receptor/mothers against decapentaplegic homolog (Smad)/peroxisome proliferator-activated receptor gamma co-activator 1α (PGC-1α) pathway. Here, we show the involvement of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway in brown adipogenesis mediated by GDF5. Overexpression of GDF5 in cells expressing adipocyte protein-2 markedly accelerated the phosphorylation of Smad1/5/8 and Akt in white and brown adipose tissues. In brown adipose tissue from heterozygous GDF5Rgsc451 mutant mice expressing a dominant-negative (DN) GDF5 under obesogenic conditions, the basal phosphorylation of Smad1/5/8 and Akt was significantly attenuated. Exposure to GDF5 not only promoted the phosphorylation of both Smad1/5/8 and Akt in cultured brown pre-adipocytes, but also up-regulated Pgc1a and uncoupling protein-1 expression in a manner sensitive to the PI3K/Akt inhibitor Ly294002 as well as retroviral infection with DN-Akt. GDF5 drastically promoted BMP-responsive luciferase reporter activity in a Ly294002-sensitive fashion. Both Ly294002 and DN-Akt markedly inhibited phosphorylation of Smad5 in the nuclei of brown pre-adipocytes. These results suggest that PI3K/Akt signals play a role in the GDF5-mediated brown adipogenesis through a mechanism related to activation of the Smad pathway

  5. Mutual inhibition of insulin signaling and PHLPP-1 determines cardioprotective efficiency of Akt in aged heart.

    Science.gov (United States)

    Xing, Yuan; Sun, Wanqing; Wang, Yishi; Gao, Feng; Ma, Heng

    2016-05-01

    Insulin protects cardiomyocytes from myocardial ischemia/reperfusion (MI/R) injury through activating Akt. However, phosphatase PHLPP-1 (PH domain leucine-rich repeat protein phosphatase-1) dephosphorylates and inactivates Akt. The balanced competitive interaction of insulin and PHLPP-1 has not been directly examined. In this study, we have identified the effect of mutual inhibition of insulin signaling and PHLPP-1 on the cardioprotective efficiency of Akt in aged heart. Young (3 months) and aged (20 months) Sprague Dawley (SD) rats were subjected to MI/Rin vivo. The PHLPP-1 level was higher in aged vs. young hearts at base. But, insulin treatment failed to decrease PHLPP-1 level during reperfusion in the aged hearts. Consequently, the cardioprotection of insulin-induced Akt activation was impaired in aged hearts, resulting in more susceptible to MI/R injury. In cultured rat ventricular myocytes, PHLPP-1 knockdown significantly enhanced insulin-induced Akt phosphorylation and reduced simulated hypoxia/reoxygenation-induced apoptosis. Contrary, PHLPP-1 overexpression terminated Akt phosphorylation and deteriorated myocytes apoptosis. Using in vivo aged animal models, we confirmed that cardiac PHLPP-1 knockdown or enhanced insulin sensitivity by exercise training dramatically increased insulin-induced Akt phosphorylation. Specifically, MI/R-induced cardiomyocyte apoptosis and infarct size were decreased and cardiac function was increased. More importantly, we found that insulin regulated the degradation of PHLPP-1 and insulin treatment could enhance the binding between PHLPP-1 and β-transducin repeat-containing protein (β-TrCP) to target for ubiquitin-dependent degradation. Altogether, we have identified a new mechanism by which insulin suppresses PHLPP-1 to enhance Akt activation. But, aged heart possesses lower insulin effectiveness and fails to decrease PHLPP-1 during MI/R, which subsequently limited Akt activity and cardioprotection. PHLPP-1 could be a

  6. Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Zhen [Central Laboratory, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081 (China); Department of Oral & Maxillofacial Surgery, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081 (China); Gan, Ye-Hua, E-mail: kqyehuagan@bjmu.edu.cn [Central Laboratory, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081 (China); Department of Oral & Maxillofacial Surgery, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081 (China)

    2015-05-01

    Radiotherapy is still one of the most effective nonsurgical treatments for many tumors. However, radioresistance remains a major impediment to radiotherapy. Although COX-2 inhibitors can induce radiosensitization, the underlying mechanism is not fully understood. In this study, we showed that COX-2 selective inhibitor celecoxib enhanced the radiation-induced inhibition of cell proliferation and apoptosis in HeLa and SACC-83 cells. Treatment with celecoxib alone dephosphorylated phosphatase and tensin homolog deleted on chromosome ten (PTEN), promoted PTEN membrane translocation or activation, and correspondingly dephosphorylated or inactivated protein kinase B (AKT). By contrast, treatment with radiation alone increased PTEN phosphorylation, inhibited PTEN membrane translocation and correspondingly activated AKT in the two cell lines. However, treatment with celecoxib or another COX-2 selective inhibitor (valdecoxib) completely blocked radiation-induced increase of PTEN phosphorylation, rescued radiation-induced decrease in PTEN membrane translocation, and correspondingly inactivated AKT. Moreover, celecoxib could also upregulate PTEN protein expression by downregulating Sp1 expression, thereby leading to the activation of PTEN transcription. Our results suggested that COX-2 inhibitors could enhance radiosensitization at least partially by activating PTEN to antagonize radiation-induced AKT activation. - Highlights: • COX-2 inhibitor, celecoxib, could enhance radiosensitization. • Radiation induced PTEN inactivation (phosphorylation) and AKT activation. • COX-2 inhibitor induced PTEN expression and activation, and inactivated AKT. • COX-2 inhibitor enhanced radiosensitization through activating PTEN.

  7. Discovery of novel AKT inhibitors with enhanced anti-tumor effects in combination with the MEK inhibitor.

    Directory of Open Access Journals (Sweden)

    Melissa Dumble

    Full Text Available Tumor cells upregulate many cell signaling pathways, with AKT being one of the key kinases to be activated in a variety of malignancies. GSK2110183 and GSK2141795 are orally bioavailable, potent inhibitors of the AKT kinases that have progressed to human clinical studies. Both compounds are selective, ATP-competitive inhibitors of AKT 1, 2 and 3. Cells treated with either compound show decreased phosphorylation of several substrates downstream of AKT. Both compounds have desirable pharmaceutical properties and daily oral dosing results in a sustained inhibition of AKT activity as well as inhibition of tumor growth in several mouse tumor models of various histologic origins. Improved kinase selectivity was associated with reduced effects on glucose homeostasis as compared to previously reported ATP-competitive AKT kinase inhibitors. In a diverse cell line proliferation screen, AKT inhibitors showed increased potency in cell lines with an activated AKT pathway (via PI3K/PTEN mutation or loss while cell lines with activating mutations in the MAPK pathway (KRAS/BRAF were less sensitive to AKT inhibition. Further investigation in mouse models of KRAS driven pancreatic cancer confirmed that combining the AKT inhibitor, GSK2141795 with a MEK inhibitor (GSK2110212; trametinib resulted in an enhanced anti-tumor effect accompanied with greater reduction in phospho-S6 levels. Taken together these results support clinical evaluation of the AKT inhibitors in cancer, especially in combination with MEK inhibitor.

  8. Discovery of novel AKT inhibitors with enhanced anti-tumor effects in combination with the MEK inhibitor.

    Science.gov (United States)

    Dumble, Melissa; Crouthamel, Ming-Chih; Zhang, Shu-Yun; Schaber, Michael; Levy, Dana; Robell, Kimberly; Liu, Qi; Figueroa, David J; Minthorn, Elisabeth A; Seefeld, Mark A; Rouse, Meagan B; Rabindran, Sridhar K; Heerding, Dirk A; Kumar, Rakesh

    2014-01-01

    Tumor cells upregulate many cell signaling pathways, with AKT being one of the key kinases to be activated in a variety of malignancies. GSK2110183 and GSK2141795 are orally bioavailable, potent inhibitors of the AKT kinases that have progressed to human clinical studies. Both compounds are selective, ATP-competitive inhibitors of AKT 1, 2 and 3. Cells treated with either compound show decreased phosphorylation of several substrates downstream of AKT. Both compounds have desirable pharmaceutical properties and daily oral dosing results in a sustained inhibition of AKT activity as well as inhibition of tumor growth in several mouse tumor models of various histologic origins. Improved kinase selectivity was associated with reduced effects on glucose homeostasis as compared to previously reported ATP-competitive AKT kinase inhibitors. In a diverse cell line proliferation screen, AKT inhibitors showed increased potency in cell lines with an activated AKT pathway (via PI3K/PTEN mutation or loss) while cell lines with activating mutations in the MAPK pathway (KRAS/BRAF) were less sensitive to AKT inhibition. Further investigation in mouse models of KRAS driven pancreatic cancer confirmed that combining the AKT inhibitor, GSK2141795 with a MEK inhibitor (GSK2110212; trametinib) resulted in an enhanced anti-tumor effect accompanied with greater reduction in phospho-S6 levels. Taken together these results support clinical evaluation of the AKT inhibitors in cancer, especially in combination with MEK inhibitor.

  9. Blocking the PI3K/AKT pathway enhances mammalian reovirus replication by repressing IFN-stimulated genes

    Science.gov (United States)

    Tian, Jin; Zhang, Xiaozhan; Wu, Hongxia; Liu, Chunguo; Li, Zhijie; Hu, Xiaoliang; Su, Shuo; Wang, Lin-Fa; Qu, Liandong

    2015-01-01

    Many host cellular signaling pathways were activated and exploited by virus infection for more efficient replication. The PI3K/Akt pathway has recently attracted considerable interest due to its role in regulating virus replication. This study demonstrated for the first time that the mammalian reovirus strains Masked Palm Civet/China/2004 (MPC/04) and Bat/China/2003 (B/03) can induce transient activation of the PI3K/Akt pathway early in infection in vitro. When UV-treated, both viruses activated PI3K/Akt signaling, indicating that the virus/receptor interaction was sufficient to activate PI3K/Akt. Reovirus virions can use both clathrin- and caveolae-mediated endocytosis, but only chlorpromazine, a specific inhibitor of clathrin-mediated endocytosis, or siRNA targeting clathrin suppressed Akt phosphorylation. We also identified the upstream molecules of the PI3K pathway. Virus infection induced phosphorylation of focal adhesion kinase (FAK) but not Gab1, and blockage of FAK phosphorylation suppressed Akt phosphorylation. Blockage of PI3K/Akt activation increased virus RNA synthesis and viral yield. We also found that reovirus infection activated the IFN-stimulated response element (ISRE) in an interferon-independent manner and up-regulated IFN-stimulated genes (ISGs) via the PI3K/Akt/EMSY pathway. Suppression of PI3K/Akt activation impaired the induction of ISRE and down-regulated the expression of ISGs. Overexpression of ISG15 and Viperin inhibited virus replication, and knockdown of either enhanced virus replication. Collectively, these results demonstrate that PI3K/Akt activated by mammalian reovirus serves as a pathway for sensing and then inhibiting virus replication/infection. PMID:26388843

  10. Phosphorylation of a specific cdk site in E2F-1 affects its electrophoretic mobility and promotes pRB-binding in vitro

    DEFF Research Database (Denmark)

    Peeper, D S; Keblusek, P; Helin, K;

    1995-01-01

    of the retinoblastoma gene (pRB). We find that E2F-1 proteins are heterogeneously phosphorylated in insect cells, as a result of which they migrate as a doublet on SDS-polyacrylamide gels. This electrophoretic shift is shown to be dependent upon specific phosphorylation of E2F-1 on serine-375 (S375), near the p...... affinity of pRB in vitro. These results suggest a novel way of regulating E2F-1 activity, namely by cell-cycle-dependent phosphorylation of this transcription factor....

  11. DNA-PK mediates AKT activation and apoptosis inhibition in clinically acquired platinum resistance.

    Science.gov (United States)

    Stronach, Euan A; Chen, Michelle; Maginn, Elaina N; Agarwal, Roshan; Mills, Gordon B; Wasan, Harpreet; Gabra, Hani

    2011-11-01

    Clinical resistance to chemotherapy is a frequent event in cancer treatment and is closely linked to poor outcome. High-grade serous (HGS) ovarian cancer is characterized by p53 mutation and high levels of genomic instability. Treatment includes platinum-based chemotherapy and initial response rates are high; however, resistance is frequently acquired, at which point treatment options are largely palliative. Recent data indicate that platinum-resistant clones exist within the sensitive primary tumor at presentation, implying resistant cell selection after treatment with platinum chemotherapy. The AKT pathway is central to cell survival and has been implicated in platinum resistance. Here, we show that platinum exposure induces an AKT-dependent, prosurvival, DNA damage response in clinically platinum-resistant but not platinum-sensitive cells. AKT relocates to the nucleus of resistant cells where it is phosphorylated specifically on S473 by DNA-dependent protein kinase (DNA-PK), and this activation inhibits cisplatin-mediated apoptosis. Inhibition of DNA-PK or AKT, but not mTORC2, restores platinum sensitivity in a panel of clinically resistant HGS ovarian cancer cell lines: we also demonstrate these effects in other tumor types. Resensitization is associated with prevention of AKT-mediated BAD phosphorylation. Strikingly, in patient-matched sensitive cells, we do not see enhanced apoptosis on combining cisplatin with AKT or DNA-PK inhibition. Insulin-mediated activation of AKT is unaffected by DNA-PK inhibitor treatment, suggesting that this effect is restricted to DNA damage-mediated activation of AKT and that, clinically, DNA-PK inhibition might prevent platinum-induced AKT activation without interfering with normal glucose homeostasis, an unwanted toxicity of direct AKT inhibitors. PMID:22131882

  12. DNA-PK Mediates AKT Activation and Apoptosis Inhibition in Clinically Acquired Platinum Resistance12

    Science.gov (United States)

    Stronach, Euan A; Chen, Michelle; Maginn, Elaina N; Agarwal, Roshan; Mills, Gordon B; Wasan, Harpreet; Gabra, Hani

    2011-01-01

    Clinical resistance to chemotherapy is a frequent event in cancer treatment and is closely linked to poor outcome. High-grade serous (HGS) ovarian cancer is characterized by p53 mutation and high levels of genomic instability. Treatment includes platinum-based chemotherapy and initial response rates are high; however, resistance is frequently acquired, at which point treatment options are largely palliative. Recent data indicate that platinum-resistant clones exist within the sensitive primary tumor at presentation, implying resistant cell selection after treatment with platinum chemotherapy. The AKT pathway is central to cell survival and has been implicated in platinum resistance. Here, we show that platinum exposure induces an AKT-dependent, prosurvival, DNA damage response in clinically platinum-resistant but not platinum-sensitive cells. AKT relocates to the nucleus of resistant cells where it is phosphorylated specifically on S473 by DNA-dependent protein kinase (DNA-PK), and this activation inhibits cisplatin-mediated apoptosis. Inhibition of DNA-PK or AKT, but not mTORC2, restores platinum sensitivity in a panel of clinically resistant HGS ovarian cancer cell lines: we also demonstrate these effects in other tumor types. Resensitization is associated with prevention of AKT-mediated BAD phosphorylation. Strikingly, in patient-matched sensitive cells, we do not see enhanced apoptosis on combining cisplatin with AKT or DNA-PK inhibition. Insulin-mediated activation of AKT is unaffected by DNA-PK inhibitor treatment, suggesting that this effect is restricted to DNA damage-mediated activation of AKT and that, clinically, DNA-PK inhibition might prevent platinum-induced AKT activation without interfering with normal glucose homeostasis, an unwanted toxicity of direct AKT inhibitors. PMID:22131882

  13. DNA-PK Mediates AKT Activation and Apoptosis Inhibition in Clinically Acquired Platinum Resistance

    Directory of Open Access Journals (Sweden)

    Euan A. Stronach

    2011-11-01

    Full Text Available Clinical resistance to chemotherapy is a frequent event in cancer treatment and is closely linked to poor outcome. High-grade serous (HGS ovarian cancer is characterized by p53 mutation and high levels of genomic instability. Treatment includes platinum-based chemotherapy and initial response rates are high; however, resistance is frequently acquired, at which point treatment options are largely palliative. Recent data indicate that platinumresistant clones exist within the sensitive primary tumor at presentation, implying resistant cell selection after treatment with platinum chemotherapy. The AKT pathway is central to cell survival and has been implicated in platinum resistance. Here, we show that platinum exposure induces an AKT-dependent, prosurvival, DNA damage response in clinically platinum-resistant but not platinum-sensitive cells. AKT relocates to the nucleus of resistant cells where it is phosphorylated specifically on S473 by DNA-dependent protein kinase (DNA-PK, and this activation inhibits cisplatin-mediated apoptosis. Inhibition of DNA-PK or AKT, but not mTORC2, restores platinum sensitivity in a panel of clinically resistant HGS ovarian cancer cell lines: we also demonstrate these effects in other tumor types. Re-sensitization is associated with prevention of AKT-mediated BAD phosphorylation. Strikingly, in patient-matched sensitive cells, we do not see enhanced apoptosis on combining cisplatin with AKT or DNA-PK inhibition. Insulin-mediated activation of AKT is unaffected by DNA-PK inhibitor treatment, suggesting that this effect is restricted to DNA damage–mediated activation of AKT and that, clinically, DNA-PK inhibition might prevent platinum-induced AKT activation without interfering with normal glucose homeostasis, an unwanted toxicity of direct AKT inhibitors.

  14. Properties of phosphorylated thymidylate synthase.

    Science.gov (United States)

    Frączyk, Tomasz; Ruman, Tomasz; Wilk, Piotr; Palmowski, Paweł; Rogowska-Wrzesinska, Adelina; Cieśla, Joanna; Zieliński, Zbigniew; Nizioł, Joanna; Jarmuła, Adam; Maj, Piotr; Gołos, Barbara; Wińska, Patrycja; Ostafil, Sylwia; Wałajtys-Rode, Elżbieta; Shugar, David; Rode, Wojciech

    2015-12-01

    Thymidylate synthase (TS) may undergo phosphorylation endogenously in mammalian cells, and as a recombinant protein expressed in bacterial cells, as indicated by the reaction of purified enzyme protein with Pro-Q® Diamond Phosphoprotein Gel Stain (PGS). With recombinant human, mouse, rat, Trichinella spiralis and Caenorhabditis elegans TSs, expressed in Escherichia coli, the phosphorylated, compared to non-phosphorylated recombinant enzyme forms, showed a decrease in Vmax(app), bound their cognate mRNA (only rat enzyme studied), and repressed translation of their own and several heterologous mRNAs (human, rat and mouse enzymes studied). However, attempts to determine the modification site(s), whether endogenously expressed in mammalian cells, or recombinant proteins, did not lead to unequivocal results. Comparative ESI-MS/analysis of IEF fractions of TS preparations from parental and FdUrd-resistant mouse leukemia L1210 cells, differing in sensitivity to inactivation by FdUMP, demonstrated phosphorylation of Ser(10) and Ser(16) in the resistant enzyme only, although PGS staining pointed to the modification of both L1210 TS proteins. The TS proteins phosphorylated in bacterial cells were shown by (31)P NMR to be modified only on histidine residues, like potassium phosphoramidate (KPA)-phosphorylated TS proteins. NanoLC-MS/MS, enabling the use of CID and ETD peptide fragmentation methods, identified several phosphohistidine residues, but certain phosphoserine and phosphothreonine residues were also implicated. Molecular dynamics studies, based on the mouse TS crystal structure, allowed one to assess potential of several phosphorylated histidine residues to affect catalytic activity, the effect being phosphorylation site dependent. PMID:26315778

  15. SIMAC - A phosphoproteomic strategy for the rapid separation of mono-phosphorylated from multiply phosphorylated peptides

    DEFF Research Database (Denmark)

    Thingholm, Tine E; Jensen, Ole N; Robinson, Phillip J;

    2008-01-01

    spectrometric analysis, such as immobilized metal affinity chromatography or titanium dioxide the coverage of the phosphoproteome of a given sample is limited. Here we report a simple and rapid strategy - SIMAC - for sequential separation of mono-phosphorylated peptides and multiply phosphorylated peptides from...... and an optimized titanium dioxide chromatographic method. More than double the total number of identified phosphorylation sites was obtained with SIMAC, primarily from a three-fold increase in recovery of multiply phosphorylated peptides....

  16. Role of multiple phosphorylation sites in the COOH-terminal tail of aquaporin-2 for water transport: evidence against channel gating

    DEFF Research Database (Denmark)

    Moeller, Hanne B; Macaulay, Nanna; Knepper, Mark A;

    2009-01-01

    in the COOH-terminal tail of AQP2 on protein function. When expressed in Xenopus laevis oocytes, prevention of AQP2 phosphorylation at S256A (S256A-AQP2) reduced osmotic water permeability threefold compared with wild-type (WT) AQP2-injected oocytes. In contrast, prevention of AQP2 single phosphorylation at S...... demonstrated that lack of phosphorylation at S256, S261, S264, or S269 had no effect on AQP2 unit water transport. Similarly, no effect on AQP2 unit water transport was observed for the 264D and 269D forms, indicating that phosphorylation of the COOH-terminal tail of AQP2 is not involved in gating...

  17. IRS-1 serine phosphorylation and insulin resistance in skeletal muscle from pancreas tranplant recipient

    DEFF Research Database (Denmark)

    Bouzakri, K; Karlsson, HRK; Vestergaard, Henrik;

    2006-01-01

    insulin receptor substrate (IRS)-1 Ser (312) and Ser (616) phosphorylation, IRS-1-associated phosphatidylinositol 3-kinase activity, and extracellular signal-regulated kinase (ERK)-1/2 phosphorylation were elevated in pancreas-kidney transplant recipients, coincident with fasting hyperinsulinemia. Basal...... action on ERK-1/2 and Akt phosphorylation was impaired in pancreas-kidney transplant recipients and was preserved in nondiabetic kidney transplant recipients. Importantly, insulin stimulation of the Akt substrate AS160 was impaired in nondiabetic kidney and pancreas-kidney transplant recipients...

  18. The importance of intrinsic disorder for protein phosphorylation

    OpenAIRE

    Lilia M Iakoucheva; Radivojac, Predrag; Celeste J Brown; O'Connor, Timothy R.; Sikes, Jason G.; Obradovic, Zoran; Dunker, A. Keith

    2004-01-01

    Reversible protein phosphorylation provides a major regulatory mechanism in eukaryotic cells. Due to the high variability of amino acid residues flanking a relatively limited number of experimentally identified phosphorylation sites, reliable prediction of such sites still remains an important issue. Here we report the development of a new web-based tool for the prediction of protein phosphorylation sites, DISPHOS (DISorder-enhanced PHOSphorylation predictor, http://www.ist.temple.edu/DISPHOS...

  19. Free Fatty Acids Inhibit Protein Tyrosine Phosphatase 1B and Activate Akt

    Directory of Open Access Journals (Sweden)

    Eisuke Shibata

    2013-09-01

    Full Text Available Background/Aims: Accumulating evidence has suggested that free fatty acids (FFAs interact with protein kinases and protein phosphatases. The present study examined the effect of FFAs on protein phosphatases and Akt. Methods: Activities of protein phosphatase 1 (PP1, protein phosphatase 2A (PP2A, and protein tyrosine phosphatase 1B (PTP1B were assayed under the cell-free conditions. Phosphorylation of Akt was monitored in MSTO-211H human malignant pleural mesothelioma cells without and with knocking-down phosphatidylinositol 3 kinase (PI3K or 3-phosphoinositide-dependent protein kinase-1 (PDK1. Results: In the cell-free assay, unsaturated FFAs (uFFAs such as oleic, linoleic and linolenic acid and saturated FFAs (sFFAs such as stearic, palmitic, myristic, and behenic acid markedly reduced PTP1B activity, with the potential for uFFAs greater than that for sFFAs. All the investigated sFFAs inhibited PP2A activity, but otherwise no inhibition was obtained with uFFAs. Both uFFAs and sFFAs had no effect on PP1 activity. Oleic acid phosphorylated Akt both on Thr308 and Ser473, while stearic acid phosphorylated Akt on Thr308 alone. The effects of oleic and stearic acid on Akt phosphorylation were abrogated by the PI3K inhibitor wortmannin or the PDK1 inhibitor BX912 and also by knocking-down PI3K or PDK1. Conclusion: The results of the present study indicate that uFFAs and sFFAs could activate Akt through a pathway along a PI3K/PDK1/Akt axis in association with PTP1B inhibition.

  20. Blocking Epidermal Growth Factor Receptor Signaling in HTR-8/SVneo First Trimester Trophoblast Cells Results in Dephosphorylation of PKBα/AKT and Induces Apoptosis

    Directory of Open Access Journals (Sweden)

    J. Bolnick

    2011-01-01

    Full Text Available We identified a major peptide signaling target of EGF/EGFR pathway and explored the consequences of blocking or activating this pathway in the first trimester extravillous trophoblast cells, HTR-8/SVneo. A global analysis of protein phosphorylation was undertaken using novel technology (Kinexus Kinetworks that utilizes SDS-polyacrylamide minigel electrophoresis and multi-lane immunoblotting to permit specific and semiquantitative detection of multiple phosphoproteins. Forty-seven protein phosphorylation sites were queried, and the results reported based on relative phosphorylation at each site. EGF- and Iressa-(gefitinib, ZD1839, an inhibitor of EGFR treated HTR-8/SVneo cells were subjected to immunoblotting and flow cytometry to confirm the phosphoprotein screen and to assess the effects of EGF versus Iressa on cell cycle and apoptosis. EGFR mediates the phosphorylation of important signaling proteins, including PKBα/AKT. This pathway is likely to be central to EGFR-mediated trophoblast survival. Furthermore, EGF treatment induces proliferation and inhibits apoptosis, while Iressa induces apoptosis.

  1. PI3K/Akt signalling pathway and cancer.

    Science.gov (United States)

    Fresno Vara, Juan Angel; Casado, Enrique; de Castro, Javier; Cejas, Paloma; Belda-Iniesta, Cristóbal; González-Barón, Manuel

    2004-04-01

    Phosphatidylinositol-3 kinases, PI3Ks, constitute a lipid kinase family characterized by their ability to phosphorylate inositol ring 3'-OH group in inositol phospholipids to generate the second messenger phosphatidylinositol-3,4,5-trisphosphate (PI-3,4,5-P(3)). RPTK activation results in PI(3,4,5)P(3) and PI(3,4)P(2) production by PI3K at the inner side of the plasma membrane. Akt interacts with these phospholipids, causing its translocation to the inner membrane, where it is phosphorylated and activated by PDK1 and PDK2. Activated Akt modulates the function of numerous substrates involved in the regulation of cell survival, cell cycle progression and cellular growth. In recent years, it has been shown that PI3K/Akt signalling pathway components are frequently altered in human cancers. Cancer treatment by chemotherapy and gamma-irradiation kills target cells primarily by the induction of apoptosis. However, the development of resistance to therapy is an important clinical problem. Failure to activate the apoptotic programme represents an important mode of drug resistance in tumor cells. Survival signals induced by several receptors are mediated mainly by PI3K/Akt, hence this pathway may decisively contribute to the resistant phenotype. Many of the signalling pathways involved in cellular transformation have been elucidated and efforts are underway to develop treatment strategies that target these specific signalling molecules or their downstream effectors. The PI3K/Akt pathway is involved in many of the mechanisms targeted by these new drugs, thus a better understanding of this crossroad can help to fully exploit the potential benefits of these new agents. PMID:15023437

  2. Optimal Classes of Chemotherapeutic Agents Sensitized by Specific Small-Molecule Inhibitors of Akt In Vitro and In Vivo

    Directory of Open Access Journals (Sweden)

    Yan Shi

    2005-11-01

    Full Text Available Akt is a serine/threonine kinase that transduces survival signals from survival/growth factors. Deregulation and signal imbalance in cancer cells make them prone to apoptosis. Upregulation or activation of Akt to aid the survival of cancer cells is a common theme in human malignancies. We have developed small-molecule Akt inhibitors that are potent and specific. These Akt inhibitors can inhibit Akt activity and block phosphorylation by Akt on multiple downstream targets in cells. Synergy in apoptosis induction was observed when Akt inhibitors were combined with doxorubicin or camptothecin. Akt inhibitor-induced enhancement of topoisomerase inhibitor cytotoxicity was also evident in long-term cell survival assay. Synergy with paclitaxel in apoptosis induction was evident in cells pretreated with paclitaxel, and enhancement of tumor delay by paclitaxel was demonstrated through cotreatment with Akt inhibitor Compound A (A-443654. Combination with other classes of chemotherapeutic agents did not yield any enhancement of cytotoxicity. These findings provide important guidance in selecting appropriate classes of chemotherapeutic agents for combination with Akt inhibitors in cancer treatment.

  3. BAY 61-3606, CDKi, and Sodium Butyrate Treatments Modulate p53 Protein Level and Its Site-Specific Phosphorylation in Human Vestibular Schwannomas In Vitro

    Directory of Open Access Journals (Sweden)

    Rohan Mitra

    2014-01-01

    Full Text Available This study is done to evaluate the effect of spleen tyrosine kinase inhibitor (BAY 61-3606, cyclin-dependent kinase inhibitor (CDKi, and sodium butyrate (Na-Bu on the level and phosphorylation of p53 protein and its binding to murine double minute 2 (MDM2 homologue in human vestibular schwannomas (VS. Primary cultures of the tumor tissues were treated individually with optimum concentrations of these small molecules in vitro. The results indicate modulation of p53 protein status and its binding ability to MDM2 in treated samples as compared to the untreated control. The three individual treatments reduced the level of total p53 protein. These treatments also decreased Ser392 and Ser15 phosphorylated p53 in tumor samples of young patients and Ser315 phosphorylated p53 in old patients. Basal level of Thr55 phosphorylated p53 protein was present in all VS samples and it remained unchanged after treatments. The p53 protein from untreated VS samples showed reduced affinity to MDM2 binding in vitro and it increased significantly after treatments. The MDM2/p53 ratio increased approximately 3-fold in the treated VS tumor samples as compared to the control. The differential p53 protein phosphorylation status perhaps could play an important role in VS tumor cell death due to these treatments that we reported previously.

  4. An acidic loop and cognate phosphorylation sites define a molecular switch that modulates ubiquitin charging activity in Cdc34-like enzymes

    DEFF Research Database (Denmark)

    Papaleo, Elena; Ranzani, Valeria; Tripodi, Farida;

    2011-01-01

    elements in one of the larger families of E2 enzymes: an acidic insertion in β4α2 loop in the proximity of the catalytic cysteine and two conserved key serine residues within the catalytic domain, which are phosphorylated by CK2. Our investigations, using yeast Cdc34 as a model, through 2.5 µs molecular......E2 ubiquitin-conjugating enzymes are crucial mediators of protein ubiquitination, which strongly influence the ultimate fate of the target substrates. Recently, it has been shown that the activity of several enzymes of the ubiquitination pathway is finely tuned by phosphorylation, an ubiquitous...... mechanism for cellular regulation, which modulates protein conformation. In this contribution, we provide the first rationale, at the molecular level, of the regulatory mechanism mediated by casein kinase 2 (CK2) phosphorylation of E2 Cdc34-like enzymes. In particular, we identify two co-evolving signature...

  5. Akt1 in osteoblasts and osteoclasts controls bone remodeling.

    Directory of Open Access Journals (Sweden)

    Naohiro Kawamura

    Full Text Available Bone mass and turnover are maintained by the coordinated balance between bone formation by osteoblasts and bone resorption by osteoclasts, under regulation of many systemic and local factors. Phosphoinositide-dependent serine-threonine protein kinase Akt is one of the key players in the signaling of potent bone anabolic factors. This study initially showed that the disruption of Akt1, a major Akt in osteoblasts and osteoclasts, in mice led to low-turnover osteopenia through dysfunctions of both cells. Ex vivo cell culture analyses revealed that the osteoblast dysfunction was traced to the increased susceptibility to the mitochondria-dependent apoptosis and the decreased transcriptional activity of runt-related transcription factor 2 (Runx2, a master regulator of osteoblast differentiation. Notably, our findings revealed a novel role of Akt1/forkhead box class O (FoxO 3a/Bim axis in the apoptosis of osteoblasts: Akt1 phosphorylates the transcription factor FoxO3a to prevent its nuclear localization, leading to impaired transactivation of its target gene Bim which was also shown to be a potent proapoptotic molecule in osteoblasts. The osteoclast dysfunction was attributed to the cell autonomous defects of differentiation and survival in osteoclasts and the decreased expression of receptor activator of nuclear factor-kappaB ligand (RANKL, a major determinant of osteoclastogenesis, in osteoblasts. Akt1 was established as a crucial regulator of osteoblasts and osteoclasts by promoting their differentiation and survival to maintain bone mass and turnover. The molecular network found in this study will provide a basis for rational therapeutic targets for bone disorders.

  6. Reactive oxygen species contribute to arsenic-induced EZH2 phosphorylation in human bronchial epithelial cells and lung cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lingzhi; Qiu, Ping; Chen, Bailing; Lu, Yongju; Wu, Kai; Thakur, Chitra; Chang, Qingshan; Sun, Jiaying; Chen, Fei, E-mail: fchen@wayne.edu

    2014-05-01

    Our previous studies suggested that arsenic is able to induce serine 21 phosphorylation of the EZH2 protein through activation of JNK, STAT3, and Akt signaling pathways in the bronchial epithelial cell line, BEAS-2B. In the present report, we further demonstrated that reactive oxygen species (ROS) were involved in the arsenic-induced protein kinase activation that leads to EZH2 phosphorylation. Several lines of evidence supported this notion. First, the pretreatment of the cells with N-acetyl-L-cysteine (NAC), a potent antioxidant, abolishes arsenic-induced EZH2 phosphorylation along with the inhibition of JNK, STAT3, and Akt. Second, H{sub 2}O{sub 2}, the most important form of ROS in the cells in response to extracellular stress signals, can induce phosphorylation of the EZH2 protein and the activation of JNK, STAT3, and Akt. By ectopic expression of the myc-tagged EZH2, we additionally identified direct interaction and phosphorylation of the EZH2 protein by Akt in response to arsenic and H{sub 2}O{sub 2}. Furthermore, both arsenic and H{sub 2}O{sub 2} were able to induce the translocation of ectopically expressed or endogenous EZH2 from nucleus to cytoplasm. In summary, the data presented in this report indicate that oxidative stress due to ROS generation plays an important role in the arsenic-induced EZH2 phosphorylation. - Highlights:: • Arsenic (As{sup 3+}) induces EZH phosphorylation. • JNK, STAT3, and Akt contribute to EZH2 phosphorylation. • Oxidative stress is involved in As{sup 3+}-induced EZH2 phosphorylation. • As{sup 3+} induces direct interaction of Akt and EZH2. • Phosphorylated EZH2 localized in cytoplasm.

  7. Identification of ischemia-regulated phosphorylation sites in connexin43: A possible target for the antiarrhythmic peptide analogue rotigaptide (ZP123)

    DEFF Research Database (Denmark)

    Axelsen, Lene Nygaard; Stahlhut, Martin; Mohammed, Shabaz;

    2006-01-01

    and presence of the antiarrhythmic peptide analogue rotigaptide (formerly known as ZP123). Phosphorylation analysis was performed on Cx43 purified from isolated perfused rat hearts using matrix-assisted laser desorption/ionization mass spectrometry and liquid chromatography electrospray ionization tandem mass...

  8. Nitric oxide promotes survival of cerebellar granule neurons cultured in vitro through the Akt pathway

    Institute of Scientific and Technical Information of China (English)

    Lin Wang; Mei Li; Lihua Zhou

    2011-01-01

    In this study, cerebellar granule neurons were used to examine the role of nitric oxide on cell survival. The N-methyl-D-aspartic acid receptor antagonist, MK-801, and the soluble guanylate cyclase antagonist, 1H-[1, 2, 4]oxadiazolo-[4, 3-a] quinoxalin-1-one, decreased cell viability, induced caspase-3, and decreased phosphorylated-Akt levels, suggesting that blockade of nitric oxide production promotes apoptosis of differentiating cerebellar granule neurons. After administration of sodium nitroprusside, an endogenous nitric oxide donor, cell viability recovered,caspase-3 expression was decreased, and phosphorylated-Akt levels increased. This study provides direct evidence that nitric oxide can sustain the survival of developing cerebellar granule neurons in vitro through the nitric oxide-Akt pathway. Moreover, endogenous nitric oxide exerts these effects in a cyclic guanosine monophosphate-dependent manner while exogenous nitric oxide does so in a cyclic guanosine monophosphate-independent manner.

  9. Inhibition of Akt activity induces the mesenchymal-to-epithelial reverting transition with restoring E-cadherin expression in KB and KOSCC-25B oral squamous cell carcinoma cells

    Directory of Open Access Journals (Sweden)

    Hong Sam-Pyo

    2009-02-01

    Full Text Available Abstract Background The Akt/PKB family of kinases is frequently activated in human cancers, including oral squamous cell carcinoma (OSCC. Akt-induced epithelial-to-mesenchymal transition (EMT involves downregulation of E-cadherin, which appears to result from upregulation of the transcription repressor Snail. Recently, it was proposed that carcinoma cells, especially in metastatic sites, could acquire the mesenchymal-to-epithelial reverting transition (MErT in order to adapt the microenvironments and re-expression of E-cadherin be a critical indicator of MErT. However, the precise mechanism and biologic or clinical importance of the MErT in cancers have been little known. This study aimed to investigate whether Akt inhibition would restore the expression of E-cadherin and β-catenin, reduce that of Vimentin, and induce the MErT in OSCC cells with low or negative expression of E-cadherin. We also investigate whether inhibition of Akt activity would affect the E-cadherin repressors and signaling molecules like NF-κB, ERK, and p38. Methods We screened several OSCC cell lines in order to select suitable cell line models for inducing MErT, using immunoblotting and methylation specific-PCR. We examined whether Akt inhibitor phosphatidylinositol ether lipid analogues (PIA treatment would restore the expression of E-cadherin and β-catenin, reduce that of Vimentin, and induce the MErT in KB and KOSCC-25B cells using RT-PCR, immunoblotting, immunofluorescence analysis, and in vitro migration assay. We also investigated whether inhibition of Akt activity would affect the E-cadherin repressors, including Snail, Twist, and SIP-1/ZEB-2 and signaling molecules like NF-κB, ERK, JNK, and p38 using RT-PCR, immunoblotting, and immunofluorescence analysis. Results Of the 7 OSCC cell lines, KB and KOSCC-25B showed constitutively activated phosphorylated Akt and low or negative expression of E-cadherin. Inhibition of Akt activity by PIA decreased NF-κB signaling

  10. Phosphatidylinositol 3-Kinase Couples Localised Calcium Influx to Activation of Akt in Central Nerve Terminals.

    Science.gov (United States)

    Nicholson-Fish, Jessica C; Cousin, Michael A; Smillie, Karen J

    2016-03-01

    The efficient retrieval of synaptic vesicle membrane and cargo in central nerve terminals is dependent on the efficient recruitment of a series of endocytosis modes by different patterns of neuronal activity. During intense neuronal activity the dominant endocytosis mode is activity-dependent endocytosis (ADBE). Triggering of ADBE is linked to calcineurin-mediated dynamin I dephosphorylation since the same stimulation intensities trigger both. Dynamin I dephosphorylation is maximised by a simultaneous inhibition of its kinase glycogen synthase kinase 3 (GSK3) by the protein kinase Akt, however it is unknown how increased neuronal activity is transduced into Akt activation. To address this question we determined how the activity-dependent increases in intracellular free calcium ([Ca(2+)]i) control activation of Akt. This was achieved using either trains of high frequency action potentials to evoke localised [Ca(2+)]i increases at active zones, or a calcium ionophore to raise [Ca(2+)]i uniformly across the nerve terminal. Through the use of either non-specific calcium channel antagonists or intracellular calcium chelators we found that Akt phosphorylation (and subsequent GSK3 phosphorylation) was dependent on localised [Ca(2+)]i increases at the active zone. In an attempt to determine mechanism, we antagonised either phosphatidylinositol 3-kinase (PI3K) or calmodulin. Activity-dependent phosphorylation of both Akt and GSK3 was arrested on inhibition of PI3K, but not calmodulin. Thus localised calcium influx in central nerve terminals activates PI3K via an unknown calcium sensor to trigger the activity-dependent phosphorylation of Akt and GSK3.

  11. Short-Chain Fatty Acid Propionate Alleviates Akt2 Knockout-Induced Myocardial Contractile Dysfunction

    Directory of Open Access Journals (Sweden)

    Linlin Li

    2012-01-01

    Full Text Available Background and Aims. Dysregulation of Akt has been implicated in diseases such as cancer and diabetes, although little is known about the role of Akt deficiency on cardiomyocyte contractile function. This study was designed to examine the effect of Akt2 knockout-induced cardiomyocyte contractile response and the effect of dietary supplementation of short-chain fatty acid propionate on Akt2 knockout-induced cardiac dysfunction, if any. Methods and Results. Adult male wild-type (WT and Akt2 knockout mice were treated with propionate (0.3 g/kg, p.o. or vehicle for 7 days. Oral glucose tolerance test (OGTT was performed. Cardiomyocyte contractile function and mitochondrial membrane potential were assessed. Expression of insulin-signaling molecules Akt, PTEN, GSK3β, and eNOS receptors for short-chain fatty acids GPR41, and GPR43 as well as protein phosphatase PP2AA, PP2AB, PP2C were evaluated using Western blot analysis. Our results revealed that Akt2 knockout led to overt glucose intolerance, compromised cardiomyocyte contractile function (reduced peak shortening and maximal velocity of shortening/relengthening as well as prolonged relengthening, loss of mitochondrial membrane potential, decreased GPR41 and elevated GPR43 expression, all of which, with the exception of glucose intolerance and elevated GPR43 level, were significantly attenuated by propionate. Neither Akt2 knockout nor propionate affected the expression of protein phosphatases, eNOS, pan, and phosphorylated PTEN and GSK3β. Conclusions. Taken together, these data depicted that Akt2 knockout may elicit cardiomyocyte contractile and mitochondrial defects and a beneficial role of propionate or short-chain fatty acids against Akt2 deficiency-induced cardiac anomalies.

  12. FBI-1 Is Overexpressed in Gestational Trophoblastic Disease and Promotes Tumor Growth and Cell Aggressiveness of Choriocarcinoma via PI3K/Akt Signaling.

    Science.gov (United States)

    Mak, Victor C Y; Wong, Oscar G W; Siu, Michelle K Y; Wong, Esther S Y; Ng, Wai-Yan; Wong, Richard W C; Chan, Ka-Kui; Ngan, Hextan Y S; Cheung, Annie N Y

    2015-07-01

    Human placental trophoblasts can be considered pseudomalignant, with tightly controlled proliferation, apoptosis, and invasiveness. Gestational trophoblastic disease (GTD) represents a family of heterogeneous trophoblastic lesions with aberrant apoptotic and proliferative activities and dysregulation of cell signaling pathways. We characterize the oncogenic effects of factor that binds to the inducer of short transcripts of HIV-1 [FBI-1, alias POZ and Krüppel erythroid myeloid ontogenic factor (POKEMON)/ZBTB7A] in GTD and its role in promoting cell aggressiveness in vitro and tumor growth in vivo. IHC studies showed increased nuclear expression of FBI-1, including hydatidiform moles, choriocarcinoma (CCA), and placental site trophoblastic tumor, in GTD. In JAR and JEG-3 CCA cells, ectopic FBI-1 expression opposed apoptosis through repression of proapoptotic genes (eg, BAK1, FAS, and CASP8). FBI-1 overexpression also promoted Akt activation, as indicated by Akt-pS473 phosphorylation. FBI-1 overexpression promoted mobility and invasiveness of JEG-3 and JAR, but not in the presence of the phosphoinositide 3-kinase inhibitor LY294002. These findings suggest that FBI-1 could promote cell migration and invasion via phosphoinositide 3-kinase/Akt signaling. In vivo, nude mice injected with CCA cells with stable FBI-1 knockdown demonstrated reduced tumor growth compared with that in control groups. These findings suggest that FBI-1 is clinically associated with the progression of, and may be a therapeutic target in, GTD, owing to its diverse oncogenic effects on dysregulated trophoblasts. PMID:26093985

  13. Protein phosphorylation in chloroplasts - a survey of phosphorylation targets.

    Science.gov (United States)

    Baginsky, Sacha

    2016-06-01

    The development of new software tools, improved mass spectrometry equipment, a suite of optimized scan types, and better-quality phosphopeptide affinity capture have paved the way for an explosion of mass spectrometry data on phosphopeptides. Because phosphoproteomics achieves good sensitivity, most studies use complete cell extracts for phosphopeptide enrichment and identification without prior enrichment of proteins or subcellular compartments. As a consequence, the phosphoproteome of cell organelles often comes as a by-product from large-scale studies and is commonly assembled from these in meta-analyses. This review aims at providing some guidance on the limitations of meta-analyses that combine data from analyses with different scopes, reports on the current status of knowledge on chloroplast phosphorylation targets, provides initial insights into phosphorylation site conservation in different plant species, and highlights emerging information on the integration of gene expression with metabolism and photosynthesis by means of protein phosphorylation. PMID:26969742

  14. AKT regulates NPM dependent ARF localization and p53mut stability in tumors.

    Science.gov (United States)

    Hamilton, Garth; Abraham, Aswin G; Morton, Jennifer; Sampson, Oliver; Pefani, Dafni E; Khoronenkova, Svetlana; Grawenda, Anna; Papaspyropoulos, Angelos; Jamieson, Nigel; McKay, Colin; Sansom, Owen; Dianov, Grigory L; O'Neill, Eric

    2014-08-15

    Nucleophosmin (NPM) is known to regulate ARF subcellular localization and MDM2 activity in response to oncogenic stress, though the precise mechanism has remained elusive. Here we describe how NPM and ARF associate in the nucleoplasm to form a MDM2 inhibitory complex. We find that oligomerization of NPM drives nucleolar accumulation of ARF. Moreover, the formation of NPM and ARF oligomers antagonizes MDM2 association with the inhibitory complex, leading to activation of MDM2 E3-ligase activity and targeting of p53. We find that AKT phosphorylation of NPM-Ser48 prevents oligomerization that results in nucleoplasmic localization of ARF, constitutive MDM2 inhibition and stabilization of p53. We also show that ARF promotes p53 mutant stability in tumors and suppresses p73 mediated p21 expression and senescence. We demonstrate that AKT and PI3K inhibitors may be effective in treatment of therapeutically resistant tumors with elevated AKT and carrying gain of function mutations in p53. Our results show that the clinical candidate AKT inhibitor MK-2206 promotes ARF nucleolar localization, reduced p53(mut) stability and increased sensitivity to ionizing radiation in a xenograft model of pancreatic cancer. Analysis of human tumors indicates that phospho-S48-NPM may be a useful biomarker for monitoring AKT activity and in vivo efficacy of AKT inhibitor treatment. Critically, we propose that combination therapy involving PI3K-AKT inhibitors would benefit from a patient stratification rationale based on ARF and p53(mut) status.

  15. Efficient autophosphorylation and phosphorylation of the beta-subunit by casein kinase-2 require the integrity of an acidic cluster 50 residues downstream from the phosphoacceptor site

    DEFF Research Database (Denmark)

    Boldyreff, B; Meggio, F; Pinna, L A;

    1994-01-01

    -64 are also involved in the process of autophosphorylation, possibly by means of a loop formation. The results obtained with the COOH-terminal-deleted mutants support the view that reconstitution of a functional holoenzyme must occur to allow efficient autophosphorylation. Polylysine prevents...... mutants reconstituting a tetrameric holoenzyme. Only with the three largest COOH-terminal deletion mutants beta delta 150-215, beta delta 171-215, and beta delta 181-215 is no significant alpha-subunit autophosphorylation observed. The phosphorylation of the beta-subunit mutants added in large molar...... excess to CK-2 holoenzyme (either native or recombinant) is also severely impaired by Ala for Glu/Asp substitutions at position 5,6 and in the 55-64 region and by the deletion of the COOH-terminal segments 150-215 and 171-215. Such a phosphorylation is inhibited by polylysine, with the exception...

  16. Phosphorylation of calcium/calmodulin-stimulated protein kinase II at T286 enhances invasion and migration of human breast cancer cells.

    Science.gov (United States)

    Chi, Mengna; Evans, Hamish; Gilchrist, Jackson; Mayhew, Jack; Hoffman, Alexander; Pearsall, Elizabeth Ann; Jankowski, Helen; Brzozowski, Joshua Stephen; Skelding, Kathryn Anne

    2016-01-01

    Calcium/calmodulin-stimulated protein kinase II (CaMKII) is a multi-functional kinase that controls a range of cellular functions, including proliferation, differentiation and apoptosis. The biological properties of CaMKII are regulated by multi-site phosphorylation. However, the role that CaMKII phosphorylation plays in cancer cell metastasis has not been examined. We demonstrate herein that CaMKII expression and phosphorylation at T286 is increased in breast cancer when compared to normal breast tissue, and that increased CAMK2 mRNA is associated with poor breast cancer patient prognosis (worse overall and distant metastasis free survival). Additionally, we show that overexpression of WT, T286D and T286V forms of CaMKII in MDA-MB-231 and MCF-7 breast cancer cells increases invasion, migration and anchorage independent growth, and that overexpression of the T286D phosphomimic leads to a further increase in the invasive, migratory and anchorage independent growth capacity of these cells. Pharmacological inhibition of CaMKII decreases MDA-MB-231 migration and invasion. Furthermore, we demonstrate that overexpression of T286D, but not WT or T286V-CaMKII, leads to phosphorylation of FAK, STAT5a, and Akt. These results demonstrate a novel function for phosphorylation of CaMKII at T286 in the control of breast cancer metastasis, offering a promising target for the development of therapeutics to prevent breast cancer metastasis. PMID:27605043

  17. Phosphorylation of calcium/calmodulin-stimulated protein kinase II at T286 enhances invasion and migration of human breast cancer cells

    Science.gov (United States)

    Chi, Mengna; Evans, Hamish; Gilchrist, Jackson; Mayhew, Jack; Hoffman, Alexander; Pearsall, Elizabeth Ann; Jankowski, Helen; Brzozowski, Joshua Stephen; Skelding, Kathryn Anne

    2016-01-01

    Calcium/calmodulin-stimulated protein kinase II (CaMKII) is a multi-functional kinase that controls a range of cellular functions, including proliferation, differentiation and apoptosis. The biological properties of CaMKII are regulated by multi-site phosphorylation. However, the role that CaMKII phosphorylation plays in cancer cell metastasis has not been examined. We demonstrate herein that CaMKII expression and phosphorylation at T286 is increased in breast cancer when compared to normal breast tissue, and that increased CAMK2 mRNA is associated with poor breast cancer patient prognosis (worse overall and distant metastasis free survival). Additionally, we show that overexpression of WT, T286D and T286V forms of CaMKII in MDA-MB-231 and MCF-7 breast cancer cells increases invasion, migration and anchorage independent growth, and that overexpression of the T286D phosphomimic leads to a further increase in the invasive, migratory and anchorage independent growth capacity of these cells. Pharmacological inhibition of CaMKII decreases MDA-MB-231 migration and invasion. Furthermore, we demonstrate that overexpression of T286D, but not WT or T286V-CaMKII, leads to phosphorylation of FAK, STAT5a, and Akt. These results demonstrate a novel function for phosphorylation of CaMKII at T286 in the control of breast cancer metastasis, offering a promising target for the development of therapeutics to prevent breast cancer metastasis. PMID:27605043

  18. Dual fluorescent molecular substrates selectively report the activation, sustainability and reversibility of cellular PKB/Akt activity

    Science.gov (United States)

    Shen, Duanwen; Bai, Mingfeng; Tang, Rui; Xu, Baogang; Ju, Xiaoming; Pestell, Richard G.; Achilefu, Samuel

    2013-04-01

    Using a newly developed near-infrared (NIR) dye that fluoresces at two different wavelengths (dichromic fluorescence, DCF), we discovered a new fluorescent substrate for Akt, also known as protein kinase B, and a method to quantitatively report this enzyme's activity in real time. Upon insulin activation of cellular Akt, the enzyme multi-phosphorylated a single serine residue of a diserine DCF substrate in a time-dependent manner, culminating in monophospho- to triphospho-serine products. The NIR DCF probe was highly selective for the Akt1 isoform, which was demonstrated using Akt1 knockout cells derived from MMTV-ErbB2 transgenic mice. The DCF mechanism provides unparalleled potential to assess the stimulation, sustainability, and reversibility of Akt activation longitudinally. Importantly, NIR fluorescence provides a pathway to translate findings from cells to living organisms, a condition that could eventually facilitate the use of these probes in humans.

  19. Lutein Inhibits the Migration of Retinal Pigment Epithelial Cells via Cytosolic and Mitochondrial Akt Pathways (Lutein Inhibits RPE Cells Migration

    Directory of Open Access Journals (Sweden)

    Ching-Chieh Su

    2014-08-01

    Full Text Available During the course of proliferative vitreoretinopathy (PVR, the retinal pigment epithelium (RPE cells will de-differentiate, proliferate, and migrate onto the surfaces of the sensory retina. Several studies have shown that platelet-derived growth factor (PDGF can induce migration of RPE cells via an Akt-related pathway. In this study, the effect of lutein on PDGF-BB-induced RPE cells migration was examined using transwell migration assays and Western blot analyses. We found that both phosphorylation of Akt and mitochondrial translocation of Akt in RPE cells induced by PDGF-BB stimulation were suppressed by lutein. Furthermore, the increased migration observed in RPE cells with overexpressed mitochondrial Akt could also be suppressed by lutein. Our results demonstrate that lutein can inhibit PDGF-BB induced RPE cells migration through the inhibition of both cytoplasmic and mitochondrial Akt activation.

  20. Bimatoprost protects retinal neuronal damage via Akt pathway.

    Science.gov (United States)

    Takano, Norihito; Tsuruma, Kazuhiro; Ohno, Yuta; Shimazawa, Masamitsu; Hara, Hideaki

    2013-02-28

    Worldwide, prostaglandin analogs, such as bimatoprost, have become the major therapeutic class for medical treatment of glaucoma because of their efficacy and generally well tolerated systemic safety profile. However, the detailed mechanism of the direct action of bimatoprost on retinal ganglion cells (RGC) has rarely been understood. Thus, in this study, we elucidated the mechanism of the protective effects of bimatoprost on RGC against oxidative stress. To examine the protective effects of bimatoprost, cultured RGC with various concentrations of bimatoprost (in both free acid and amide form) were exposed to l-buthionin-(S,R)-sulfoximine (BSO) plus glutamate or serum depletion in vitro and intravitreal injection of N-methyl-D-aspartate (NMDA) was used to induce retinal damage in vivo. To elucidate the protective mechanism of bimatoprost, we used western blot analysis to investigate the phosphorylation of Akt and extracellular signal-regulated kinase (ERK). Bimatoprost significantly reduced BSO plus glutamate- and serum deprivation-induced death in concentration-dependent manners. Bimatoprost induced activation of Akt and ERK, and a phosphatidylinositol 3-kinase inhibitor, LY294002, attenuated the protective effect of bimatoprost. On the other hand, a mitogen-activated protein kinase kinase inhibitor, U0126, exhibited protective effect unexpectedly. Moreover, ERK was more phosphorylated by attenuation of Akt activity in cultured RGC. In an in vivo study, bimatoprost reduced NMDA-induced RGC death. Taken together, these findings indicate that bimatoprost has protective effects on in vitro and in vivo retinal damage, suggesting that the mechanism underlying may be via the Akt pathway, which may modulate the ERK pathway.

  1. Tamoxifen-induced cytotoxicity in breast cancer cells is mediated by glucose-regulated protein 78 (GRP78) via AKT (Thr308) regulation.

    Science.gov (United States)

    Pujari, Radha; Jose, Jemy; Bhavnani, Varsha; Kumar, Natesh; Shastry, Padma; Pal, Jayanta K

    2016-08-01

    Glucose regulated protein 78 (GRP78) has recently been suggested to be associated with drug resistance in breast cancer patients. However, the precise role of GRP78 in drug resistance and the involved signaling pathways are not clearly understood. In the present study, we show that among a panel of drugs, namely Paclitaxel (TAX), Doxorubicin (DOX), 5-fluorouracil (5-FU), UCN-01 and Tamoxifen (TAM) used, TAM alone up-regulated the expression of GRP78 significantly and induced apoptosis in MCF-7 and MDA-MB-231 cells. Interestingly, inhibition of GRP78 by a specific pharmacological inhibitor, VER-155008 augmented TAM-induced apoptosis, and overexpression of GRP78 rendered the cells resistant to TAM-induced cell death suggesting a role for GRP78 in TAM-induced cytotoxicity. Mechanistically, the expression of phosphorylated AKT as determined by Western blot analyses revealed that TAM selectively upregulated phosphorylation of AKT at Thr308 but not at Ser473, and siRNA silencing of GRP78 resulted in inhibition of AKT phosphorylation at Thr308 but not at Ser473. Further, a GRP78 inhibitor, VER155008 inhibited TAM-induced phosphorylation of GSK3β, a downstream substrate of AKT. These results, thus suggests a role for GRP78 in TAM-induced AKT activation. Additionally, co-localization studies by immunofluorescence, and immunoprecipitation experiments demonstrated a complex formation of AKT and GRP78. Furthermore, in glucose-free medium, the cells were sensitized to TAM-induced cell death that was associated with reduced AKT phosphorylation at Thr308, thus strengthening the association of AKT regulation with drug response. Collectively, our findings identify a role of GRP78 in AKT regulation in response to TAM in breast cancer cells. PMID:27262235

  2. Lithium protects against methamphetamine-induced neurotoxicity in PC12 cells via Akt/GSK3β/mTOR pathway

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jintao; Zhu, Dexiao; Zhang, Jing; Li, Guibao [Department of Anatomy, School of Medicine, Shandong University, Jinan, Shandong, 250012 (China); Liu, Zengxun [Department of Psychiatry, School of Medicine, Shandong University, Jinan, Shandong, 250012 China (China); Sun, Jinhao, E-mail: sunjinhao@gmail.com [Department of Anatomy, School of Medicine, Shandong University, Jinan, Shandong, 250012 (China)

    2015-09-25

    Methamphetamine (MA) is neurotoxic, especially in dopaminergic neurons. Long-lasting exposure to MA causes psychosis and increases the risk of Parkinson's disease. Lithium (Li) is a known mood stabilizer and has neuroprotective effects. Previous studies suggest that MA exposure decreases the phosphorylation of Akt/GSK3β pathway in vivo, whereas Li facilitates the phosphorylation of Akt/GSK3β pathway. Moreover, GSK3β and mTOR are implicated in the locomotor sensitization induced by psychostimulants and mTOR plays a critical role in MA induced toxicity. However, the effect of MA on Akt/GSK3β/mTOR pathway has not been fully investigated in vitro. Here, we found that MA exposure significantly dephosphorylated Akt/GSK3β/mTOR pathway in PC12 cells. In addition, Li remarkably attenuated the dephosphorylation effect of MA exposure on Akt/GSK3β/mTOR pathway. Furthermore, Li showed obvious protective effects against MA toxicity and LY294002 (Akt inhibitor) suppressed the protective effects of Li. Together, MA exposure dephosphorylates Akt/GSK3β/mTOR pathway in vitro, while lithium protects against MA-induced neurotoxicity via phosphorylation of Akt/GSK3β/mTOR pathway. - Highlights: • Lithium protects against methamphetamine-induced neurotoxicity in vitro. • Methamphetamine exposure dephosphorylates Akt/GSK3β/mTOR pathway. • Lithium attenuates methamphetamine-induced toxicity via phosphorylating Akt/GSK3β/mTOR pathway.

  3. mTOR-rictor is the Ser473 kinase for AKT1 in mouse one-cell stage embryos.

    Science.gov (United States)

    Zhang, Zhe; Zhang, Guojun; Xu, Xiaoyan; Su, Wenhui; Yu, Bingzhi

    2012-02-01

    Mammalian target of rapamycin (mTOR) controls cell growth and proliferation via the raptor-mTOR (TORC1) and rictor-mTOR (TORC2) protein complexes. The mTORC2 containing mTOR and rictor is thought to be rapamycin insensitive and it is recently shown that both rictor and mTORC2 are essential for the development of both embryonic and extra embryonic tissues. To explore rictor function in the early development of mouse embryos, we disrupted the expression of rictor, a specific component of mTORC2, in mouse fertilized eggs by using rictor shRNA. Our results showed that one-cell stage eggs that were lack of rictor could not enter into the two-cell stage normally. Recent biochemical studies suggests that TORC2 is the elusive PDK2 (3'-phosphoinositide-dependent kinase 2) for AKT/PKB Ser473 phosphorylation, which is deemed necessary for AKT function, so we microinjected AKT-S473A into mouse fertilized eggs to investigate whether AKT-S473A is downstream effector of mTOR.rictor to regulate the mitotic division. Our findings revealed that the rictor induced phosphorylation of AKT in Ser473 is required for TORC2 function in early development of mouse embryos. PMID:22057724

  4. Vasopressin activates Akt/mTOR pathway in smooth muscle cells cultured in high glucose concentration

    Energy Technology Data Exchange (ETDEWEB)

    Montes, Daniela K.; Brenet, Marianne; Muñoz, Vanessa C.; Burgos, Patricia V.; Villanueva, Carolina I. [Department of Physiology, Universidad Austral de Chile, Valdivia 509-9200 (Chile); Figueroa, Carlos D. [Department of Anatomy, Histology and Pathology, Universidad Austral de Chile, Valdivia 509-9200 (Chile); González, Carlos B., E-mail: cbgonzal@uach.cl [Department of Physiology, Universidad Austral de Chile, Valdivia 509-9200 (Chile); Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX 77555 (United States)

    2013-11-29

    Highlights: •AVP induces mTOR phosphorylation in A-10 cells cultured in high glucose concentration. •The mTOR phosphorylation is mediated by the PI3K/Akt pathway activation. •The AVP-induced mTOR phosphorylation inhibited autophagy and stimulated cell proliferation. -- Abstract: Mammalian target of rapamycin (mTOR) complex is a key regulator of autophagy, cell growth and proliferation. Here, we studied the effects of arginine vasopressin (AVP) on mTOR activation in vascular smooth muscle cells cultured in high glucose concentration. AVP induced the mTOR phosphorylation in A-10 cells grown in high glucose, in contrast to cells cultured in normal glucose; wherein, only basal phosphorylation was observed. The AVP-induced mTOR phosphorylation was inhibited by a PI3K inhibitor. Moreover, the AVP-induced mTOR activation inhibited autophagy and increased thymidine incorporation in cells grown in high glucose. This increase was abolished by rapamycin which inhibits the mTORC1 complex formation. Our results suggest that AVP stimulates mTOR phosphorylation by activating the PI3K/Akt signaling pathway and, subsequently, inhibits autophagy and raises cell proliferation in A-10 cells maintained in high glucose concentration.

  5. Wnt5a promotes migration of human osteosarcoma cells by triggering a phosphatidylinositol-3 kinase/Akt signals

    OpenAIRE

    Zhang, Ailiang; He, Shuanghua; Sun, Xiaoliang; Ding, Lianghua; Bao, Xinnan; Wang, Neng

    2014-01-01

    Wnt5a is classified as a non-transforming Wnt family member and plays complicated roles in oncogenesis and cancer metastasis. However, Wnt5a signaling in osteosarcoma progression remains poorly defined. In this study, we found that Wnt5a stimulated the migration of human osteosarcoma cells (MG-63), with the maximal effect at 100 ng/ml, via enhancing phosphorylation of phosphatidylinositol-3 kinase (PI3K)/Akt. PI3K and Akt showed visible signs of basal phosphorylation and elevated phosphorylat...

  6. Tert-butylhydroquinone lowers blood pressure in AngII-induced hypertension in mice via proteasome-PTEN-Akt-eNOS pathway

    Science.gov (United States)

    Xu, Bing-Can; Long, Hui-Bao; Luo, Ke-Qin

    2016-01-01

    Tert-butylhydroquinone (tBHQ), as an antioxidant, has been widely used for many years to prevent oxidization of food products. The aim of this study was to investigate whether tBHQ activates endothelial nitric oxide synthase (eNOS) to prevent endothelial dysfunction and lower blood pressure. The role of Akt in tBHQ-induced eNOS phosphorylation was examined in human umbilical vein endothelial cells (HUVEC) or in mice. tBHQ treatment of HUVEC increased both Akt-Ser473 phosphorylation, accompanied with increased eNOS-Ser1177 phosphorylation and NO release. Mechanically, pharmacologic or genetic inhibition of Akt abolished tBHQ-enhanced NO release and eNOS phosphorylation in HUVEC. Gain-function of PTEN or inhibition of 26S proteasome abolished tBHQ-enhanced Akt phosphorylation in HUVEC. Ex vivo analysis indicated that tBHQ improved Ach-induced endothelium-dependent relaxation in LPC-treated mice aortic arteries, which were abolished by inhibition of Akt or eNOS. In animal study, administration of tBHQ significantly increased eNOS-Ser1177 phosphorylation and acetylcholine-induced vasorelaxation, and lowered AngII-induced hypertension in wildtype mice, but not in mice deficient of Akt or eNOS. In conclusion, tBHQ via proteasome-dependent degradation of PTEN increases Akt phosphorylation, resulting in upregulation of eNOS-derived NO production and consequent improvement of endothelial function in vivo. In this way, tBHQ lowers blood pressure in hypertensive mice. PMID:27435826

  7. 肌醇5'磷酸酶基因突变对K562细胞周期蛋白和Akt磷酸化的影响%Effects of SHIP gene mutation on cell cycle related proteins and phosphorylated Akt in K562 cells

    Institute of Scientific and Technical Information of China (English)

    杨琳; 罗建民; 刘小军; 温树鹏; 杨敬慈; 张敬宇

    2009-01-01

    Objective To investigate the effect of SHIP gene mutation on the cell cycle and its related gene expression in K562 cells.Methods The recombinated green fluorescent protein (GFP) containing F1V-SHIP gene was transfected into K562 cells.The transfection efficiency and cell cycle of K562/SHIP were assessed by flow cytometry (FCM).The proliferation of K562 ceils was detected by MTT assay,the mRNA levels of SHIP by real-time fluorescent relative-quantification reverse transcriptional PCR(FQ-PCR),and the protein levels of SHIP,CyclinDl,p21WAF1/CIPI and p27KIP1 by Western blot.Results Wild type SHIP inhibited K562 cell proliferation and caused a G0/G1 arrest [(34.2 ± 7.8) % vs (0.7 ± 8.3) % (P0.05).Conclusion ①wtSHIP gene can downregulate Akt phosphorylation and result in inhibition of cyclin D1 expression,up-regulating p27KIP1 and p21WIF1/CIPI expression,finally leading to the reduction of K562 cell proliferation,and inducing G0/G1 phase arrest.②SHIP gene suppresses the proliferation of K562,being dependent on its intact structure and function.%目的 从分子水平探讨肌醇5'磷酸酶(SHIP)基因突变对人白血病细胞系K562细胞周期及其相关基因表达的影响.方法 应用携带野生型和突变型SHIP及绿色荧光蛋白的慢病毒及空载体慢病毒质粒转染K562细胞,通过流式细胞术检测K562/SHIP细胞转染效率、细胞增殖指数及细胞周期变化;MTT法检测细胞增殖活性改变,实时荧光定量PCR(FQ-PCR)检测SHIP mRNA水平变化,Western blot检测各组K562细胞SHIP、细胞周期蛋白(cyclin)D1、p21WAF1/CIPI、P27KIP1蛋白表达水平及Akt磷酸化变化.结果 野生型SHIP基因能明显抑制K562细胞增殖,并产生明显的G0/G1期阻滞[G0/G1期细胞分别为(34.2±7.8)%和(0.7±8.3)%,P0.05].Western blot结果发现转染野生型SHIP基因后K562细胞Akt磷酸化和cyclin D1表达水平明显下降(P0.05).结论 ①野生型SHIP基因通过下调K562细胞Akt磷酸化

  8. Linear motif atlas for phosphorylation-dependent signaling

    DEFF Research Database (Denmark)

    Miller, Martin Lee; Jensen, LJ; Diella, F;

    2008-01-01

    Systematic and quantitative analysis of protein phosphorylation is revealing dynamic regulatory networks underlying cellular responses to environmental cues. However, matching these sites to the kinases that phosphorylate them and the phosphorylation-dependent binding domains that may subsequently...... sequence models of linear motifs. The atlas is available as a community resource (http://netphorest.info)....

  9. Silencing p110{beta} prevents rapid depletion of nuclear pAkt

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Zhi-wei; Ghalali, Aram; Hoegberg, Johan [Institute of Environmental Medicine, Karolinska Institutet, S-17177 Stockholm (Sweden); Stenius, Ulla, E-mail: ulla.stenius@ki.se [Institute of Environmental Medicine, Karolinska Institutet, S-17177 Stockholm (Sweden)

    2011-12-02

    Highlights: Black-Right-Pointing-Pointer p110{beta} was essential for the statin- and ATP-induced depletion of nuclear pAkt and an associated inhibition of growth. Black-Right-Pointing-Pointer p110{beta} knock-out inhibited statin-induced changes in binding between FKBP51, pAkt and PTEN. Black-Right-Pointing-Pointer Data supports the hypothesis that nuclear pAkt is important for anti-cancer effects of statins. -- Abstract: The p110{beta} subunit in the class IA PI3K family may act as an oncogene and is critical for prostate tumor development in PTEN knockout mice. We tested the possible involvement of p110{beta} in a recently described rapid depletion of phosphorylated Akt (pAkt) in the nucleus. Previous work showed that this down-regulation is induced by extracellular ATP or by statins and is mediated by the purinergic receptor P2X7. Here, we used p110{beta} knock out mouse embryonic fibroblasts (MEFs) and siRNA-treated cancer cells. We found that p110{beta} is essential for ATP- or statin-induced nuclear pAkt depletion in MEFs and in several cancer cell lines including prostate cancer cells. ATP, statin or the selective P2X7 agonist BzATP also inhibited cell growth, and this inhibition was not seen in p110{beta} knock out cells. We also found that p110{beta} was necessary for statin-induced changes in binding between FKBP51, pAkt and PTEN. Our data show that p110{beta} is essential for the ATP- and statin-induced effects and support a role of nuclear pAkt in cancer development. They also provide support for a chemopreventive effect of statins mediated by depletion of nuclear pAkt.

  10. Akt1-mediated fast/glycolytic skeletal muscle growth attenuates renal damage in experimental kidney disease.

    Science.gov (United States)

    Hanatani, Shinsuke; Izumiya, Yasuhiro; Araki, Satoshi; Rokutanda, Taku; Kimura, Yuichi; Walsh, Kenneth; Ogawa, Hisao

    2014-12-01

    Muscle wasting is frequently observed in patients with kidney disease, and low muscle strength is associated with poor outcomes in these patients. However, little is known about the effects of skeletal muscle growth per se on kidney diseases. In this study, we utilized a skeletal muscle-specific, inducible Akt1 transgenic (Akt1 TG) mouse model that promotes the growth of functional skeletal muscle independent of exercise to investigate the effects of muscle growth on kidney diseases. Seven days after Akt1 activation in skeletal muscle, renal injury was induced by unilateral ureteral obstruction (UUO) in Akt1 TG and wild-type (WT) control mice. The expression of atrogin-1, an atrophy-inducing gene in skeletal muscle, was upregulated 7 days after UUO in WT mice but not in Akt1 TG mice. UUO-induced renal interstitial fibrosis, tubular injury, apoptosis, and increased expression of inflammatory, fibrosis-related, and adhesion molecule genes were significantly diminished in Akt1 TG mice compared with WT mice. An increase in the activating phosphorylation of eNOS in the kidney accompanied the attenuation of renal damage by myogenic Akt1 activation. Treatment with the NOS inhibitor L-NAME abolished the protective effect of skeletal muscle Akt activation on obstructive kidney disease. In conclusion, Akt1-mediated muscle growth reduces renal damage in a model of obstructive kidney disease. This improvement appears to be mediated by an increase in eNOS signaling in the kidney. Our data support the concept that loss of muscle mass during kidney disease can contribute to renal failure, and maintaining muscle mass may improve clinical outcome.

  11. AKT3 controls mitochondrial biogenesis and autophagy via regulation of the major nuclear export protein CRM-1.

    Science.gov (United States)

    Corum, Daniel G; Tsichlis, Philip N; Muise-Helmericks, Robin C

    2014-01-01

    Our previous work has shown that Akt3 is required for mitochondrial biogenesis in primary human endothelial cells (ECs) and in Akt3-null mice; Akt3 affects subcellular localization of peroxisome proliferator-activated receptor γ coactivator-1 (PGC-1α), the master regulator of mitochondrial biogenesis. The purpose of this study is to determine the mechanism by which Akt3 controls the subcellular distribution of PGC-1α and to explore the effect on mitochondrial biogenesis and turnover during angiogenesis. Here we use standard biochemical analyses and Akt3-knockdown strategies to show that Akt3 controls the stabilization of chromosome maintenance region-1 (CRM-1), the major nuclear export receptor. Site-directed mutagenesis and association analyses show that PGC-1α nuclear export is CRM-1 dependent. Akt3 knockdown and CRM-1 overexpression cause 3-fold reductions in PGC-1α target gene expression, compared to control levels. Akt3 inhibition causes autophagy, as measured by autophagosome formation, in a CRM-1-dependent, Akt1/mTOR-independent pathway. In vivo, Akt3-null and heterozygous mice show dose-dependent decreases in angiogenesis compared to wild-type littermates (~5- and 2.5-fold decreases, respectively), as assessed by Matrigel plug assays. This correlates with an ~1.5-fold decrease in mitochondrial Cox IV expression. Our studies suggest that Akt3 is a regulator of mitochondrial dynamics in the vasculature via regulation of CRM-1-dependent nuclear export.

  12. Molecular characterization of the encoding regions and tissue expression analyses for 3 novel buffalo AKT genes, AKT1, AKT2, and AKT3

    OpenAIRE

    Wu, Chunfeng; LIU, Lixian; HUO, Jinlong; Li, Dalin; YUAN, Yueyun; Yuan,Feng; Miao, Yongwang

    2014-01-01

    The objective of this study was to obtain the complete coding sequences (CDSs) of 3 buffalo genes (AKT1, AKT2, and AKT3) using reverse-transcriptase polymerase chain reaction and to depict their molecular characterizations and tissue expression patterns in buffalo. The buffalo AKT1, AKT2, and AKT3 CDSs were 1443 bp, 1446 bp, and 1440 bp in length and encoded 480, 481, and 479 amino acids, respectively. Nine, 13, and 3 nucleotide differences were found in the CDSs between buffalo and other bov...

  13. Propofol directly increases tau phosphorylation.

    Directory of Open Access Journals (Sweden)

    Robert A Whittington

    Full Text Available In Alzheimer's disease (AD and other tauopathies, the microtubule-associated protein tau can undergo aberrant hyperphosphorylation potentially leading to the development of neurofibrillary pathology. Anesthetics have been previously shown to induce tau hyperphosphorylation through a mechanism involving hypothermia-induced inhibition of protein phosphatase 2A (PP2A activity. However, the effects of propofol, a common clinically used intravenous anesthetic, on tau phosphorylation under normothermic conditions are unknown. We investigated the effects of a general anesthetic dose of propofol on levels of phosphorylated tau in the mouse hippocampus and cortex under normothermic conditions. Thirty min following the administration of propofol 250 mg/kg i.p., significant increases in tau phosphorylation were observed at the AT8, CP13, and PHF-1 phosphoepitopes in the hippocampus, as well as at AT8, PHF-1, MC6, pS262, and pS422 epitopes in the cortex. However, we did not detect somatodendritic relocalization of tau. In both brain regions, tau hyperphosphorylation persisted at the AT8 epitope 2 h following propofol, although the sedative effects of the drug were no longer evident at this time point. By 6 h following propofol, levels of phosphorylated tau at AT8 returned to control levels. An initial decrease in the activity and expression of PP2A were observed, suggesting that PP2A inhibition is at least partly responsible for the hyperphosphorylation of tau at multiple sites following 30 min of propofol exposure. We also examined tau phosphorylation in SH-SY5Y cells transfected to overexpress human tau. A 1 h exposure to a clinically relevant concentration of propofol in vitro was also associated with tau hyperphosphorylation. These findings suggest that propofol increases tau phosphorylation both in vivo and in vitro under normothermic conditions, and further studies are warranted to determine the impact of this anesthetic on the acceleration of

  14. Directional and quantitative phosphorylation networks

    DEFF Research Database (Denmark)

    Jørgensen, Claus; Linding, Rune

    2008-01-01

    for unravelling phosphorylation-mediated cellular interaction networks. In particular, we will discuss how the combination of new quantitative mass-spectrometric technologies and computational algorithms together are enhancing mapping of these largely uncharted dynamic networks. By combining quantitative......Directionality in protein signalling networks is due to modulated protein-protein interactions and is fundamental for proper signal progression and response to external and internal cues. This property is in part enabled by linear motifs embedding post-translational modification sites. These serve...... as recognition sites, guiding phosphorylation by kinases and subsequent binding of modular domains (e.g. SH2 and BRCT). Characterization of such modification-modulated interactions on a proteome-wide scale requires extensive computational and experimental analysis. Here, we review the latest advances in methods...

  15. Regulation of Akt/PKB activity by P21-activated Kinase in Cardiomyocytes

    OpenAIRE

    Mao, Kai; Kobayashi, Satoru; Jaffer, Zahara M.; Huang, Yuan; Volden, Paul; Chernoff, Jonathan; Liang, Qiangrong

    2007-01-01

    Akt/PKB is a critical regulator of cardiac function and morphology, and its activity is governed by dual phosphorylation at active loop (Thr308) by phosphoinositide-dependent protein kinase-1 (PDK1) and at carboxyl-terminal hydrophobic motif (Ser473) by a putative PDK2. P21-activated kinase-1 (Pak1) is a serine/threonine protein kinase implicated in the regulation of cardiac hypertrophy and contractility, and was shown previously to activate Akt through an undefined mechanism. Here we report ...

  16. AKT activation drives the nuclear localization of CSE1L and a pro-oncogenic transcriptional activation in ovarian cancer cells

    International Nuclear Information System (INIS)

    The human homolog of the yeast cse1 gene (CSE1L) is over-expressed in ovarian cancer. CSE1L forms complex with Ran and importin-α and has roles in nucleocytoplasmic traffic and gene expression. CSE1L accumulated in the nucleus of ovarian cancer cell lines, while it was localized also in the cytoplasm of other cancer cell lines. Nuclear localization depended on AKT, which was constitutively active in ovarian cancer cells, as the CSE1L protein translocated to the cytoplasm when AKT was inactivated. Moreover, the expression of a constitutively active AKT forced the translocation of CSE1L from the cytoplasm to the nucleus in other cancer cells. Nuclear accrual of CSE1L was associated to the nuclear accumulation of the phosphorylated Ran Binding protein 3 (RanBP3), which depended on AKT as well. Also in samples of human ovarian cancer, AKT activation was associated to nuclear accumulation of CSE1L and phosphorylation of RanBP3. Expression profiling of ovarian cancer cells after CSE1L silencing showed that CSE1L was required for the expression of genes promoting invasion and metastasis. In agreement, CSE1L silencing impaired motility and invasiveness of ovarian cancer cells. Altogether these data show that in ovarian cancer cells activated AKT by affecting RanBP3 phosphorylation determines the nuclear accumulation of CSE1L and likely the nuclear concentration of transcription factors conveying pro-oncogenic signals. - highlights: • CSE1L is a key player in nucleocytoplasmic traffic by forming complex with Ran. • AKT phosphorylates RanBP3 that regulates the nucleocytoplasmic gradient of Ran. • The activated oncogenic AKT drives the nuclear accumulation of CSE1L. • CSE1L in the nucleus up-regulates genes conveying pro-oncogenic signals. • CSE1L might contribute to tumor progression driven by the activated oncogenic AKT

  17. AKT activation drives the nuclear localization of CSE1L and a pro-oncogenic transcriptional activation in ovarian cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Lorenzato, Annalisa; Biolatti, Marta [Department of Oncology, University of Torino School of Medicine, Torino (Italy); Institute for Cancer Research at Candiolo, Candiolo, Torino (Italy); Delogu, Giuseppe [Department of Biomedical Sciences-Histology, University of Sassari, Sassari (Italy); Capobianco, Giampiero [Department of Surgical, Microsurgical and Medical Sciences, University of Sassari, Sassari (Italy); Farace, Cristiano [Department of Biomedical Sciences-Histology, University of Sassari, Sassari (Italy); Dessole, Salvatore; Cossu, Antonio; Tanda, Francesco [Department of Surgical, Microsurgical and Medical Sciences, University of Sassari, Sassari (Italy); Madeddu, Roberto [Department of Biomedical Sciences-Histology, University of Sassari, Sassari (Italy); National Institute of Biostructures and Biosystems, Rome (Italy); Olivero, Martina [Department of Oncology, University of Torino School of Medicine, Torino (Italy); Institute for Cancer Research at Candiolo, Candiolo, Torino (Italy); Di Renzo, Maria Flavia, E-mail: mariaflavia.direnzo@unito.it [Department of Oncology, University of Torino School of Medicine, Torino (Italy); Institute for Cancer Research at Candiolo, Candiolo, Torino (Italy)

    2013-10-15

    The human homolog of the yeast cse1 gene (CSE1L) is over-expressed in ovarian cancer. CSE1L forms complex with Ran and importin-α and has roles in nucleocytoplasmic traffic and gene expression. CSE1L accumulated in the nucleus of ovarian cancer cell lines, while it was localized also in the cytoplasm of other cancer cell lines. Nuclear localization depended on AKT, which was constitutively active in ovarian cancer cells, as the CSE1L protein translocated to the cytoplasm when AKT was inactivated. Moreover, the expression of a constitutively active AKT forced the translocation of CSE1L from the cytoplasm to the nucleus in other cancer cells. Nuclear accrual of CSE1L was associated to the nuclear accumulation of the phosphorylated Ran Binding protein 3 (RanBP3), which depended on AKT as well. Also in samples of human ovarian cancer, AKT activation was associated to nuclear accumulation of CSE1L and phosphorylation of RanBP3. Expression profiling of ovarian cancer cells after CSE1L silencing showed that CSE1L was required for the expression of genes promoting invasion and metastasis. In agreement, CSE1L silencing impaired motility and invasiveness of ovarian cancer cells. Altogether these data show that in ovarian cancer cells activated AKT by affecting RanBP3 phosphorylation determines the nuclear accumulation of CSE1L and likely the nuclear concentration of transcription factors conveying pro-oncogenic signals. - highlights: • CSE1L is a key player in nucleocytoplasmic traffic by forming complex with Ran. • AKT phosphorylates RanBP3 that regulates the nucleocytoplasmic gradient of Ran. • The activated oncogenic AKT drives the nuclear accumulation of CSE1L. • CSE1L in the nucleus up-regulates genes conveying pro-oncogenic signals. • CSE1L might contribute to tumor progression driven by the activated oncogenic AKT.

  18. Constitutively Active Akt1 Cooperates with KRasG12D to Accelerate In Vivo Pancreatic Tumor Onset and Progression

    Directory of Open Access Journals (Sweden)

    Toya M. Albury

    2015-02-01

    Full Text Available BACKGROUND AND AIMS: Pancreatic adenocarcinoma is a deadly disease characterized by metastatic progression and resistance to conventional therapeutics. Mutation of KRAS is the most frequent early event in pancreatic tumor progression. AKT isoforms are frequently activated in pancreatic cancer, and reports have implicated hyperactivation of AKT1, as well as AKT2, in pancreatic tumor formation. The objective here is to delineate the role of AKT in facilitating in vivo pancreatic tumor progression in the context of KRAS mutation and predisposition to pancreatic cancer. METHODS: Mice with Akt1 and KRas mutant alleles expressed using the pancreas Pdx promoter were mated to characterize the incidence and frequency of histologic and genetic alterations known to occur commonly in human pancreatic ductal adenocarcinoma. RESULTS: Active Akt1 (Akt1Myr, containing a myristoylation sequence cooperated with active mutant KRasG12D to accelerate pancreatic carcinoma onset and progression and increase phosphorylation of downstream effectors in the Akt pathway. Mucin and smooth muscle actin expression was found in and around pancreatic intraepithelial neoplasms (PanINs, and accelerated time to metastasis was found in Akt1Myr/KRasG12D mice. CONCLUSIONS: In contrast to prior reports of pancreatic KRas mutant mice mated with mice deficient for various tumor suppressor genes, which resulted in aggressive disease within a few months of age, Akt1Myr/KRasG12D mice enabled the study of PanINs and spontaneous pancreatic transformation more characteristic of human pancreatic progression in elderly individuals. The Akt1Myr/KRasG12D model holds promise for delineating the tumor biology and biomarkers critical for understanding their cooperation in cancer oncogenesis and future targeting in therapeutic strategies.

  19. Activation of Akt by advanced glycation end products (AGEs: involvement of IGF-1 receptor and caveolin-1.

    Directory of Open Access Journals (Sweden)

    Su-Jung Yang

    Full Text Available Diabetes is characterized by chronic hyperglycemia, which in turn facilitates the formation of advanced glycation end products (AGEs. AGEs activate signaling proteins such as Src, Akt and ERK1/2. However, the mechanisms by which AGEs activate these kinases remain unclear. We examined the effect of AGEs on Akt activation in 3T3-L1 preadipocytes. Addition of AGEs to 3T3-L1 cells activated Akt in a dose- and time-dependent manner. The AGEs-stimulated Akt activation was blocked by a PI3-kinase inhibitor LY 294002, Src inhibitor PP2, an antioxidant NAC, superoxide scavenger Tiron, or nicotinamide adenine dinucleotide phosphate (NAD(PH oxidase inhibitor DPI, suggesting the involvement of Src and NAD(PH oxidase in the activation of PI3-kinase-Akt pathway by AGEs. AGEs-stimulated Src tyrosine phosphorylation was inhibited by NAC, suggesting that Src is downstream of NAD(PH oxidase. The AGEs-stimulated Akt activity was sensitive to Insulin-like growth factor 1 receptor (IGF-1R kinase inhibitor AG1024. Furthermore, AGEs induced phosphorylation of IGF-1 receptorβsubunit (IGF-1Rβ on Tyr1135/1136, which was sensitive to PP2, indicating that AGEs stimulate Akt activity by transactivating IGF-1 receptor. In addition, the AGEs-stimulated Akt activation was attenuated by β-methylcyclodextrin that abolishes the structure of caveolae, and by lowering caveolin-1 (Cav-1 levels with siRNAs. Furthermore, addition of AGEs enhanced the interaction of phospho-Cav-1 with IGF-1Rβ and transfection of 3T3-L1 cells with Cav-1 Y14F mutants inhibited the activation of Akt by AGEs. These results suggest that AGEs activate NAD(PH oxidase and Src which in turn phosphorylates IGF-1 receptor and Cav-1 leading to activation of IGF-1 receptor and the downstream Akt in 3T3-L1 cells. AGEs treatment promoted the differentiation of 3T3-L1 preadipocytes and addition of AG1024, LY 294002 or Akt inhibitor attenuated the promoting effect of AGEs on adipogenesis, suggesting that IGF-1

  20. Apigenin inhibits HGF-promoted invasive growth and metastasis involving blocking PI3K/Akt pathway and β4 integrin function in MDA-MB-231 breast cancer cells

    International Nuclear Information System (INIS)

    Hepatocyte growth factor (HGF) and its receptor, Met, known to control invasive growth program have recently been shown to play crucial roles in the survival of breast cancer patients. The diet-derived flavonoids have been reported to possess anti-invasion properties; however, knowledge on the pharmacological and molecular mechanisms in suppressing HGF/Met-mediated tumor invasion and metastasis is poorly understood. In our preliminary study, we use HGF as an invasive inducer to investigate the effect of flavonoids including apigenin, naringenin, genistein and kaempferol on HGF-dependent invasive growth of MDA-MB-231 human breast cancer cells. Results show that apigenin presents the most potent anti-migration and anti-invasion properties by Boyden chamber assay. Furthermore, apigenin represses the HGF-induced cell motility and scattering and inhibits the HGF-promoted cell migration and invasion in a dose-dependent manner. The effect of apigenin on HGF-induced signaling activation involving invasive growth was evaluated by immunoblotting analysis, it shows that apigenin blocks the HGF-induced Akt phosphorylation but not Met, ERK, and JNK phosphorylation. In addition to MDA-MB-231 cells, apigenin exhibits inhibitory effect on HGF-induced Akt phosphorylation in hepatoma SK-Hep1 cells and lung carcinoma A549 cells. By indirect immunofluorescence microscopy assay, apigenin inhibits the HGF-induced clustering of β4 integrin at actin-rich adhesive site and lamellipodia through PI3K-dependent manner. Treatment of apigenin inhibited HGF-stimulated integrin β4 function including cell-matrix adhesion and cell-endothelial cells adhesion in MDA-MB-231 cells. By Akt-siRNA transfection analysis, it confirmed that apigenin inhibited HGF-promoted invasive growth involving blocking PI3K/Akt pathway. Finally, we evaluated the effect of apigenin on HGF-promoted metastasis by lung colonization of tumor cells in nude mice and organ metastasis of tumor cells in chick embryo. By

  1. Variability of protein level and phosphorylation status caused by biopsy protocol design in human skeletal muscle analyses

    Directory of Open Access Journals (Sweden)

    Caron Marc-André

    2011-11-01

    Full Text Available Abstract Background Bergström needle biopsy is widely used to sample skeletal muscle in order to study cell signaling directly in human tissue. Consequences of the biopsy protocol design on muscle protein quantity and quality remain unclear. The aim of the present study was to assess the impact of different events surrounding biopsy protocol on the stability of the Western blot signal of eukaryotic translation initiation factor 4E binding protein 1 (4E-BP1, Akt, glycogen synthase kinase-3β (GSK-3β, muscle RING finger protein 1 (MuRF1 and p70 S6 kinase (p70 S6K. Six healthy subjects underwent four biopsies of the vastus lateralis, distributed into two distinct visits spaced by 48 hrs. At visit 1, a basal biopsy in the right leg was performed in the morning (R1 followed by a second in the left leg in the afternoon (AF. At visit 2, a second basal biopsy (R2 was collected from the right leg. Low intensity mobilization (3 × 20 right leg extensions was performed and a final biopsy (Mob was collected using the same incision site as R2. Results Akt and p70 S6K phosphorylation levels were increased by 83% when AF biopsy was compared to R1. Mob condition induced important phosphorylation of p70 S6K when compared to R2. Comparison of R1 and R2 biopsies revealed a relative stability of the signal for both total and phosphorylated proteins. Conclusions This study highlights the importance to standardize muscle biopsy protocols in order to minimize the method-induced variation when analyzing Western blot signals.

  2. TG-interacting factor transcriptionally induced by AKT/FOXO3A is a negative regulator that antagonizes arsenic trioxide-induced cancer cell apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Zi-Miao; Tseng, Hong-Yu; Cheng, Ya-Ling [Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan (China); Yeh, Bi-Wen [Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan (China); Department of Urology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (China); Wu, Wen-Jeng [Department of Urology, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan (China); Department of Urology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan (China); Huang, Huei-Sheng, E-mail: huanghs@mail.ncku.edu.tw [Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 701, Taiwan (China)

    2015-05-15

    Arsenic trioxide (ATO) is a multi-target drug approved by the Food and Drug Administration as the first-line chemotherapeutic agent for the treatment of acute promyelocytic leukemia. In addition, several clinical trials are being conducted with arsenic-based drugs for the treatment of other hematological malignancies and solid tumors. However, ATO's modest clinical efficacy on some cancers, and potential toxic effects on humans have been reported. Determining how best to reduce these adverse effects while increasing its therapeutic efficacy is obviously a critical issue. Previously, we demonstrated that the JNK-induced complex formation of phosphorylated c-Jun and TG-interacting factor (TGIF) antagonizes ERK-induced cyclin-dependent kinase inhibitor CDKN1A (p21{sup WAF1/CIP1}) expression and resultant apoptosis in response to ATO in A431 cells. Surprisingly, at low-concentrations (0.1–0.2 μM), ATO increased cellular proliferation, migration and invasion, involving TGIF expression, however, at high-concentrations (5–20 μM), ATO induced cell apoptosis. Using a promoter analysis, TGIF was transcriptionally regulated by ATO at the FOXO3A binding site (− 1486 to − 1479 bp) via the c-Src/EGFR/AKT pathway. Stable overexpression of TGIF promoted advancing the cell cycle into the S phase, and attenuated 20 μM ATO-induced apoptosis. Furthermore, blockage of the AKT pathway enhanced ATO-induced CDKN1A expression and resultant apoptosis in cancer cells, but overexpression of AKT1 inhibited CDKN1A expression. Therefore, we suggest that TGIF is transcriptionally regulated by the c-Src/EGFR/AKT pathway, which plays a role as a negative regulator in antagonizing ATO-induced CDKN1A expression and resultant apoptosis. Suppression of these antagonistic effects might be a promising therapeutic strategy toward improving clinical efficacy of ATO. - Highlights: • ATO-induced biphasic survival responses of cancer cells depend on low- or high-concentrations. • TGIF

  3. Identification and quantification of the phosphorylated ovalbumin by high resolution mass spectrometry under dry-heating treatment.

    Science.gov (United States)

    Wang, Hui; Tu, Zong-Cai; Liu, Guang-Xian; Zhang, Lu; Chen, Yuan

    2016-11-01

    The specific phosphorylation sites and degree of phosphorylation (DP) at each site are directly related to protein's structure and functional properties. Thus, characterizing the introduced phosphate groups is of great importance. This study was to monitor the phosphorylation sites, DP and the number of phosphorylation sites in P-Oval achieved by dry heating in the presence of pyrophosphate for 1, 2 and 5days by using Fourier transform ion cyclotron mass spectrometry (FTICR MS). Two phosphorylation sites were found in natural ovalbumin, but the number of phosphorylation sites increased to 8, 8 and 10 after dry-heating phosphorylation for 1, 2 and 5days, respectively. In addition, dual-phosphorylated peptides were detected for samples without extensive heating. The phosphorylation sites were found to be mainly on Ser residues, which could be the preferred phosphorylation site for dry heating in the presence of pyrophosphate. PMID:27211632

  4. Ghrelin Protects against the Detrimental Consequences of Porphyromonas gingivalis-Induced Akt Inactivation through S-Nitrosylation on Salivary Mucin Synthesis

    Directory of Open Access Journals (Sweden)

    Bronislaw L. Slomiany

    2011-01-01

    Full Text Available Disturbances in nitric oxide synthase isozyme system and the impairment in salivary mucin synthesis are well-recognized features associated with oral mucosal inflammatory responses to periodontopathic bacterium, P. gingivalis. In this study, using rat sublingual gland acinar cells, we report that P. gingivalis LPS-induced impairment in mucin synthesis and associated suppression in Akt kinase activity were accompanied by a decrease in constitutive nitric oxide synthase (cNOS activity and an induction in inducible nitric oxide synthase (iNOS expression. The LPS effect on Akt inactivation was manifested in the kinase S-nitrosylation and a decrease in its phosphorylation at Ser473. Further, we demonstrate that a peptide hormone, ghrelin, countered the LPS-induced impairment in mucin synthesis. This effect of ghrelin was reflected in the suppression of iNOS and the increase in Akt activation, associated with the loss in S-nitrosylation and the increase in phosphorylation, as well as cNOS activation through phosphorylation. Our findings suggest that induction in iNOS expression by P. gingivalis-LPS leads to Akt kinase inactivation through S-nitrosylation that detrimentally impacts cNOS activation through phosphorylation as well as mucin synthesis. We also show that the countering effect of ghrelin on P. gingivalis-induced impairment in mucin synthesis is associated with Akt activation through phosphorylation.

  5. Full activation of PKB/Akt in response to insulin or ionizing radiation is mediated through ATM.

    Science.gov (United States)

    Viniegra, Juan Guinea; Martínez, Natalia; Modirassari, Pegah; Hernández Losa, Javier; Parada Cobo, Carlos; Sánchez-Arévalo Lobo, Víctor Javier; Aceves Luquero, Clara Isabel; Alvarez-Vallina, Luis; Ramón y Cajal, Santiago; Rojas, José María; Sánchez-Prieto, Ricardo

    2005-02-11

    The gene mutated in ataxia telangiectasia, ATM, has been implicated in several cell functions such as cell cycle control and response to DNA damage and insulin. PKB/Akt has also been implicated in the cellular response to insulin, gamma-radiation, and cell cycle control. Interestingly, lack of PKB/Akt function in vivo is able to mimic some phenotypic abnormalities associated with ataxia telangiectasia (AT). Here we show that ATM is a major determinant of full PKB/Akt activation in response to insulin or gamma-radiation. This effect is mediated through the phosphatidylinositol 3-kinase domain of ATM that specifically affects Akt serine 473 phosphorylation. This conclusion was inferred from the results obtained in transient transfection assays using exogenous PKB/Akt and ATM in Cos cells. Moreover, the use of ATM inhibitors or small interfering RNA confirmed our observation. Further supporting these results, we also observed that biological responses tightly regulated by Akt, such as transcription factor of the forkhead family activity after insulin treatment or gamma-radiation response, were altered in cell lines derived from AT patients and knockout mice for ATM in which phosphorylation in serine 473 was almost abolished. This study proposes new clues in the search of the unknown PDK2 and new explanations for the radiosensitivity or insulin intolerance described more than 30 years ago in AT patients. PMID:15546863

  6. Frequent alterations of the PI3K/AKT/mTOR pathways in hereditary nonpolyposis colorectal cancer

    DEFF Research Database (Denmark)

    Ekstrand, Anna Isinger; Jönsson, Mats; Lindblom, Annika;

    2010-01-01

    The phosphatidylinositol 3-kinases-AKT-mammalian target of rapamycin pathway (PI3K/AKT/mTOR) is central in colorectal tumors. Data on its role in hereditary cancers are, however, scarce and we therefore characterized mutations in PIK3CA and KRAS, and expression of PIK3CA, phosphorylated AKT...... and PTEN in 58 HNPCC-associated colorectal cancers. Derangements of at least one of the PI3K/AKT/mTOR components analyzed were found in 51/58 (88%) tumors. Mutations in PIK3CA and KRAS were identified in 14 and 31% of the tumors respectively. Overexpression of PIK3CA and phosphorylated AKT occurred in 59...... and 75% and were strongly associated (P = 0.005). Reduced/lost PTEN expression was found in 63% of the tumors. Though HNPCC-associated colorectal cancers show simple genetic profiles with few chromosomal alterations, we demonstrate frequent and repeated targeting of the PI3K/AKT/mTOR pathway, which...

  7. Mechanical stretch increases MMP-2 production in vascular smooth muscle cells via activation of PDGFR-β/Akt signaling pathway.

    Directory of Open Access Journals (Sweden)

    Kyo Won Seo

    Full Text Available Increased blood pressure, leading to mechanical stress on vascular smooth muscle cells (VSMC, is a known risk factor for vascular remodeling via increased activity of matrix metalloproteinase (MMP within the vascular wall. This study aimed to identify cell surface mechanoreceptors and intracellular signaling pathways that influence VSMC to produce MMP in response to mechanical stretch (MS. When VSMC was stimulated with MS (0-10% strain, 60 cycles/min, both production and gelatinolytic activity of MMP-2, but not MMP-9, were increased in a force-dependent manner. MS-enhanced MMP-2 expression and activity were inhibited by molecular inhibition of Akt using Akt siRNA as well as by PI3K/Akt inhibitors, LY293002 and AI, but not by MAPK inhibitors such as PD98059, SP600125 and SB203580. MS also increased Akt phosphorylation in VSMC, which was attenuated by AG1295, a PDGF receptor (PDGFR inhibitor, but not by inhibitors for other receptor tyrosine kinase including EGF, IGF, and FGF receptors. Although MS activated PDGFR-α as well as PDGFR-β in VSMC, MS-induced Akt phosphorylation was inhibited by molecular deletion of PDGFR-β using siRNA, but not by inhibition of PDGFR-α. Collectively, our data indicate that MS induces MMP-2 production in VSMC via activation of Akt pathway, that is mediated by activation of PDGFR-β signaling pathways.

  8. Phosphatidylinositol 3-kinase/Akt pathway regulates hepatic stellate cell apoptosis

    Institute of Scientific and Technical Information of China (English)

    Yan Wang; Xiao-Yu Jiang; Li Liu; Hui-Qing Jiang

    2008-01-01

    AIM:To investigate the role of phosphatidylinositol 3-kinase(PI 3-K)/Akt signaling pathway in the balance of HSC activation and apoptosis in rat hepatic stellate cells(HSC).METHODS:An activated HSC cell line was used in this study.LY 294002,the PI 3-K/Akt signal pathway blocker was used to investigate the molecular events on apoptosis in HSC and to interpret the role of this pathway in HSC apoptosis.Immunocytochemistry,Western blot and reverse transcription polymerase chain reaction(RT-PCR)analysis were applied to detect the expression of PI 3-K,and simultaneously phosphorylated-Akt(p-Akt)and total-Akt were determined by Western blot.The HSC apoptosis was examined by annexin-V/propidium iodide double-labelled flow cytometry and transmission electron microscopy.RESULTS:The apoptosis rates in LY 294002(30.82% ±2.90%)and LY 294002+PDGF-BB(28.16%±2.58%)groups were significantly increased compared with those of control(9.02%±1.81%)and PDGF-BB(4.35%±1.18%).PDGF-BB augmented PI 3-K and p-Akt expression.LY 294002 significantly reduced the contents of PI 3-K and p-Akt.mRNA transcription evaluated by RT-PCR showed similar tendencies as protein expression.CONCLUSION:Inhibition of PI 3-K/Akt signaling pathway Induces apoptosis in HSC.(C)2008 The WJG Press.All rights reserved.

  9. Phosphorylation of Recombinant Tristetraprolin in Vitro

    OpenAIRE

    Cao, Heping; Lin, Rui

    2008-01-01

    Tristetraprolin/zinc finger protein 36 (TTP/ZFP36) binds and destabilizes some proinflammatory cytokine mRNAs. TTP-deficient mice develop a profound inflammatory syndrome due to excessive production of proinflammatory cytokines. TTP gene expression is induced by various factors including insulin, cinnamon, and green tea extracts. Previous studies have shown that TTP is highly phosphorylated in vivo and multiple phosphorylation sites are identified in human TTP. This study evaluated the potent...

  10. Phosphorylation-independent dual-site binding of the FHA domain of KIF13 mediates phosphoinositide transport via centaurin [alpha]1

    Energy Technology Data Exchange (ETDEWEB)

    Tong, Yufeng; Tempel, Wolfram; Wang, Hui; Yamada, Kaori; Shen, Limin; Senisterra, Guillermo A.; MacKenzie, Farrell; Chishti, Athar H.; Park, Hee-Won (Toronto); (UICM)

    2011-11-07

    Phosphatidylinositol 3,4,5-triphosphate (PIP3) plays a key role in neuronal polarization and axon formation. PIP3-containing vesicles are transported to axon tips by the kinesin KIF13B via an adaptor protein, centaurin {alpha}1 (CENTA1). KIF13B interacts with CENTA1 through its forkhead-associated (FHA) domain. We solved the crystal structures of CENTA1 in ligand-free, KIF13B-FHA domain-bound, and PIP3 head group (IP4)-bound conformations, and the CENTA1/KIF13B-FHA/IP4 ternary complex. The first pleckstrin homology (PH) domain of CENTA1 specifically binds to PIP3, while the second binds to both PIP3 and phosphatidylinositol 3,4-biphosphate (PI(3,4)P2). The FHA domain of KIF13B interacts with the PH1 domain of one CENTA1 molecule and the ArfGAP domain of a second CENTA1 molecule in a threonine phosphorylation-independent fashion. We propose that full-length KIF13B and CENTA1 form heterotetramers that can bind four phosphoinositide molecules in the vesicle and transport it along the microtubule.

  11. Unraveling a phosphorylation event in a folded protein by NMR spectroscopy: phosphorylation of the Pin1 WW domain by PKA

    Energy Technology Data Exchange (ETDEWEB)

    Smet-Nocca, Caroline, E-mail: caroline.smet@univ-lille1.fr; Launay, Helene; Wieruszeski, Jean-Michel; Lippens, Guy; Landrieu, Isabelle, E-mail: isabelle.landrieu@univ-lille1.fr [Universite de Lille-Nord de France, Institut Federatif de Recherches 147, CNRS UMR 8576 (France)

    2013-04-15

    The Pin1 protein plays a critical role in the functional regulation of the hyperphosphorylated neuronal Tau protein in Alzheimer's disease and is by itself regulated by phosphorylation. We have used Nuclear Magnetic Resonance (NMR) spectroscopy to both identify the PKA phosphorylation site in the Pin1 WW domain and investigate the functional consequences of this phosphorylation. Detection and identification of phosphorylation on serine/threonine residues in a globular protein, while mostly occurring in solvent-exposed flexible loops, does not lead to chemical shift changes as obvious as in disordered proteins and hence does not necessarily shift the resonances outside the spectrum of the folded protein. Other complications were encountered to characterize the extent of the phosphorylation, as part of the {sup 1}H,{sup 15}N amide resonances around the phosphorylation site are specifically broadened in the unphosphorylated state. Despite these obstacles, NMR spectroscopy was an efficient tool to confirm phosphorylation on S16 of the WW domain and to quantify the level of phosphorylation. Based on this analytical characterization, we show that WW phosphorylation on S16 abolishes its binding capacity to a phosphorylated Tau peptide. A reduced conformational heterogeneity and flexibility of the phospho-binding loop upon S16 phosphorylation could account for part of the decreased affinity for its phosphorylated partner. Additionally, a structural model of the phospho-WW obtained by molecular dynamics simulation and energy minimization suggests that the phosphate moiety of phospho-S16 could compete with the phospho-substrate.

  12. Unraveling a phosphorylation event in a folded protein by NMR spectroscopy: phosphorylation of the Pin1 WW domain by PKA

    International Nuclear Information System (INIS)

    The Pin1 protein plays a critical role in the functional regulation of the hyperphosphorylated neuronal Tau protein in Alzheimer’s disease and is by itself regulated by phosphorylation. We have used Nuclear Magnetic Resonance (NMR) spectroscopy to both identify the PKA phosphorylation site in the Pin1 WW domain and investigate the functional consequences of this phosphorylation. Detection and identification of phosphorylation on serine/threonine residues in a globular protein, while mostly occurring in solvent-exposed flexible loops, does not lead to chemical shift changes as obvious as in disordered proteins and hence does not necessarily shift the resonances outside the spectrum of the folded protein. Other complications were encountered to characterize the extent of the phosphorylation, as part of the 1H,15N amide resonances around the phosphorylation site are specifically broadened in the unphosphorylated state. Despite these obstacles, NMR spectroscopy was an efficient tool to confirm phosphorylation on S16 of the WW domain and to quantify the level of phosphorylation. Based on this analytical characterization, we show that WW phosphorylation on S16 abolishes its binding capacity to a phosphorylated Tau peptide. A reduced conformational heterogeneity and flexibility of the phospho-binding loop upon S16 phosphorylation could account for part of the decreased affinity for its phosphorylated partner. Additionally, a structural model of the phospho-WW obtained by molecular dynamics simulation and energy minimization suggests that the phosphate moiety of phospho-S16 could compete with the phospho-substrate.

  13. AGC kinases regulate phosphorylation and activation of eukaryotic translation initiation factor 4B

    NARCIS (Netherlands)

    van Gorp, A. G. M.; van der Vos, K. E.; Brenkman, A. B.; Bremer, A.; van den Broek, N.; Zwartkruis, F.; Hershey, J. W.; Burgering, B. M. T.; Calkhoven, C. F.; Coffer, P. J.

    2009-01-01

    Eukaryotic translation initiation factor 4B (eIF4B) plays a critical role during the initiation of protein synthesis and its activity can be regulated by multiple phosphorylation events. In a search for novel protein kinase B (PKB/c-akt) substrates, we identified eIF4B as a potential target. Using a

  14. Neurofilament subunit (NFL) head domain phosphorylation regulates axonal transport of neurofilaments.

    LENUS (Irish Health Repository)

    Yates, Darran M

    2009-04-01

    Neurofilaments are the intermediate filaments of neurons and are synthesised in neuronal cell bodies and then transported through axons. Neurofilament light chain (NFL) is a principal component of neurofilaments, and phosphorylation of NFL head domain is believed to regulate the assembly of neurofilaments. However, the role that NFL phosphorylation has on transport of neurofilaments is poorly understood. To address this issue, we monitored axonal transport of phosphorylation mutants of NFL. We mutated four known phosphorylation sites in NFL head domain to either preclude phosphorylation, or mimic permanent phosphorylation. Mutation to preclude phosphorylation had no effect on transport but mutation of three sites to mimic permanent phosphorylation inhibited transport. Mutation of all four sites together to mimic permanent phosphorylation proved especially potent at inhibiting transport and also disrupted neurofilament assembly. Our results suggest that NFL head domain phosphorylation is a regulator of neurofilament axonal transport.

  15. Bypassing AMPK Phosphorylation

    OpenAIRE

    Viollet, Benoit; Foretz, Marc; Schlattner, Uwe

    2014-01-01

    AMP-activated protein kinase (AMPK) functions as a signaling hub to balance energy supply with demand. Phosphorylation of activation loop Thr172 has been considered as an essential step in AMPK activation. In this issue of Chemistry & Biology, Scott and colleagues show that the small molecule direct AMPK activator, A-769662, bypasses this phosphorylation event, and acts synergistically with AMP on naive AMPK.

  16. Inhibition of PKB/Akt activity involved in apigenin-induced apoptosis in human gastric carcinoma cells

    Institute of Scientific and Technical Information of China (English)

    YUAN LinHong; XIA Wei; ZHAO XiuJuan; ZHANG XiaoHua; ZHANG Ling; WU Kun

    2007-01-01

    Apigenin is a flavonoid widely distributed in fruits and vegetables.It possesses growth inhibitory properties against numerous cancer cell lines.However, the molecular mechanism(s) by which apigenin elicits its effects have not been fully elucidated.Here we studied whether apigenin inhibits growth and induces apoptosis in human gastric carcinoma cells.We showed that the flavonoid inhibited growth of the cells and caused apoptosis, as evidenced by DNA Ladder, cleavage of pro-caspase-3 in a time-dependent manner.Induction of apoptosis was dependent on inhibition of the PKB/Akt activity.We found that while apigenin had no effect on the expression of Akt and Bad, it inhibited specific phosphorylation of the two proteins that are associated with pro-survival mechanisms.We propose that this important flavonoid induces apoptosis in gastric cancer cells by inhibiting Akt activity.Since Akt is often activated in cancers, our findings may have clinical implications.

  17. Effect of Phosphorylation on Hydrogen-Bonding Interactions of the Active Site Histidine of the Phosphocarrier Protein HPr of the Phosphoenolpyruvate-Dependent Phosphotransferase System Determined by 15N NMR Spectroscopy

    NARCIS (Netherlands)

    Dijk, Alard A. van; Lange, Liesbeth C.M. de; Bachovchin, William W.; Robillard, George T.

    1990-01-01

    The phosphocarrier protein HPr of the phosphoenolpyruvate-dependent sugar transport system of Escherichia coli can exist in a phosphorylated and a nonphosphorylated form. During phosphorylation, the phosphoryl group is carried on a histidine residue, His15. The hydrogen-bonding state of this histidi

  18. The relationships among bovine αS-casein phosphorylation isoforms suggest different phosphorylation pathways.

    Science.gov (United States)

    Fang, Z H; Visker, M H P W; Miranda, G; Delacroix-Buchet, A; Bovenhuis, H; Martin, P

    2016-10-01

    Casein (CN) phosphorylation is an important posttranslational modification and is one of the key factors responsible for constructing and stabilizing casein micelles. Variation in phosphorylation degree of αS-CN is of great interest because it is suggested to affect milk technological properties. This study aimed to investigate the variation in phosphorylation degree of αS-CN among milk of individual cows and to explore relationships among different phosphorylation isoforms of αS-CN. For this purpose, we analyzed morning milk samples from 529 French Montbéliarde cows using liquid chromatography coupled with electrospray ionization mass spectrometry. We detected 3 new phosphorylation isoforms: αS2-CN-9P, αS2-CN-14P, and αS2-CN-15P in bovine milk, in addition to the known isoforms αS1-CN-8P, αS1-CN-9P, αS2-CN-10P, αS2-CN-11P, αS2-CN-12P, and αS2-CN-13P. The relative concentrations of each αS-CN phosphorylation isoform varied considerably among individual cows. Furthermore, the phenotypic correlations and hierarchical clustering suggest at least 2 regulatory systems for phosphorylation of αS-CN: one responsible for isoforms with lower levels of phosphorylation (αS1-CN-8P, αS2-CN-10P, and αS2-CN-11P), and another responsible for isoforms with higher levels of phosphorylation (αS1-CN-9P, αS2-CN-12P, αS2-CN-13P, and αS2-CN-14P). Identifying all phosphorylation sites of αS2-CN and investigating the genetic background of different αS2-CN phosphorylation isoforms may provide further insight into the phosphorylation mechanism of caseins. PMID:27522420

  19. Spatial proximity statistics suggest a regulatory role of protein phosphorylation on compound binding.

    Science.gov (United States)

    Korkuć, Paula; Walther, Dirk

    2016-05-01

    Phosphorylation is an important post-translational modification that regulates protein function by the attachment of negatively charged phosphate groups to phosphorylatable amino acid residues. As a mode of action, an influence of phosphorylation on the binding of compounds to proteins has been discussed and described for a number of proteins in the literature. However, a systematic statistical survey probing for enriched phosphorylation sites close to compound binding sites in support of this notion and with properly chosen random reference distributions has not been presented yet. Using high-resolution protein structures from the Protein Data Bank including their co-crystallized non-covalently bound compounds and experimentally determined phosphorylation sites, we analyzed the pairwise distance distributions of phosphorylation and compound binding sites on protein surfaces. We found that phosphorylation sites are indeed located at significantly closer distances to compounds than expected by chance holding true specifically also for the subset of compound binding sites serving as catalytic sites of metabolic reactions. This tendency was particularly evident when treating phosphorylation sites as collective sets supporting the relevance of phosphorylation hotspots. Interestingly, phosphorylation sites were found to be closer to negatively charged than to positively charged compounds suggesting a stronger modulation of the binding of negatively charged compounds in dependence on phosphorylation status than on positively charged compounds. The enrichment of phosphorylation sites near compound binding sites confirms a regulatory role of phosphorylation in compound binding and provides a solid statistical basis for the literature-reported selected events.

  20. AKT induces erythroid-cell maturation of JAK2-deficient fetal liver progenitor cells and is required for Epo regulation of erythroid-cell differentiation.

    Science.gov (United States)

    Ghaffari, Saghi; Kitidis, Claire; Zhao, Wei; Marinkovic, Dragan; Fleming, Mark D; Luo, Biao; Marszalek, Joseph; Lodish, Harvey F

    2006-03-01

    AKT serine threonine kinase of the protein kinase B (PKB) family plays essential roles in cell survival, growth, metabolism, and differentiation. In the erythroid system, AKT is known to be rapidly phosphorylated and activated in response to erythropoietin (Epo) engagement of Epo receptor (EpoR) and to sustain survival signals in cultured erythroid cells. Here we demonstrate that activated AKT complements EpoR signaling and supports erythroid-cell differentiation in wild-type and JAK2-deficient fetal liver cells. We show that erythroid maturation of AKT-transduced cells is not solely dependent on AKT-induced cell survival or proliferation signals, suggesting that AKT transduces also a differentiation-specific signal downstream of EpoR in erythroid cells. Down-regulation of expression of AKT kinase by RNA interference, or AKT activity by expression of dominant negative forms, inhibits significantly fetal liver-derived erythroid-cell colony formation and gene expression, demonstrating that AKT is required for Epo regulation of erythroid-cell maturation.

  1. Targeting FAK Radiosensitizes 3-Dimensional Grown Human HNSCC Cells Through Reduced Akt1 and MEK1/2 Signaling

    Energy Technology Data Exchange (ETDEWEB)

    Hehlgans, Stephanie [OncoRay-National Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, Dresden University of Technology, Dresden (Germany); Department of Radiotherapy and Oncology, University of Frankfurt, Frankfurt am Main (Germany); Institute of Radiopharmacy, Helmholtz Center Dresden-Rossendorf, Dresden (Germany); Eke, Iris [OncoRay-National Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, Dresden University of Technology, Dresden (Germany); Cordes, Nils, E-mail: Nils.Cordes@OncoRay.de [OncoRay-National Center for Radiation Research in Oncology, Medical Faculty Carl Gustav Carus, Dresden University of Technology, Dresden (Germany); Institute of Radiopharmacy, Helmholtz Center Dresden-Rossendorf, Dresden (Germany); Department of Radiation Oncology, University Hospital and Medical Faculty Carl Gustav Carus, Dresden University of Technology, Dresden (Germany)

    2012-08-01

    Purpose: Focal adhesion kinase (FAK), a main regulator of integrin signaling and cell migration, is frequently overexpressed and hyperphosphorylated in human head-and-neck squamous cell carcinoma (HNSCC). We have previously shown that pharmacologic FAK inhibition leads to radiosensitization of 3-dimensionally grown HNSCC cell lines. To further evaluate the role of FAK in radioresistance and as a potential cancer target, we examined FAK and FAK downstream signaling in HNSCC cell lines grown in more physiologic extracellular matrix-based 3-dimensional cell cultures. Methods and Materials: Seven HNSCC cell lines were grown in 3-dimensional extracellular matrix and the clonogenic radiation survival, expression, and phosphorylation of FAK, paxillin, Akt1, extracellular signal-regulated kinase (ERK)1/2, and MEK1/2 were analyzed after siRNA-mediated knockdown of FAK, Akt1, MEK1, FAK+Akt1, or FAK+MEK1 compared with controls or stable overexpression of FAK. The role of MEK1/2 for clonogenic survival and signaling was investigated using the MEK inhibitor U0126 with or without irradiation. Results: FAK knockdown moderately or significantly enhanced the cellular radiosensitivity of 3-dimensionally grown HNSCC cells. The FAK downstream targets paxillin, Akt1, and ERK1/2 were substantially dephosphorylated under FAK depletion. FAK overexpression, in contrast, increased radiation survival and paxillin, Akt1, and ERK1/2 phosphorylation. The degree of radiosensitization upon Akt1, ERK1/2, or MEK1 depletion or U0126 was superimposable to FAK knockdown. Combination knockdown conditions (ie, Akt1/FAK, MEK1/FAK, or U0126/FAK) failed to provide additional radiosensitization. Conclusions: Our data provide further evidence for FAK as important determinant of radiation survival, which acts in the same signaling axis as Akt1 and ERK1/2. These data strongly support our hypothesis that FAK is a relevant molecular target for HNSCC radiotherapy.

  2. Pancreas-specific Pten deficiency causes partial resistance to diabetes and elevated hepatic AKT signaling

    Institute of Scientific and Technical Information of China (English)

    Zan Tong; Yan Fan; Weiqi Zhang; Jun Xu; Jing Cheng; Mingxiao Ding; Hongkui Deng

    2009-01-01

    PTEN, a negative regulator of the phosphatidylinositol-3-kinase/AKT pathway, is an important modulator of insu-lin signaling. To determine the metabolic function of pancreatic Pten, we generated pancreas-specific Pten knockout (PPKO) mice. PPKO mice had enlarged pancreas and elevated proliferation of acinar cells. They also exhibited hy-poglycemia, hypoinsulinemia, and altered amino metabolism. Notably, PPKO mice showed delayed onset of strepto-zotocin (STZ)-induced diabetes and sex-biased resistance to high-fat-diet (HFD)-induced diabetes. To investigate the mechanism for the resistance to HFD-induced hyperglycemia in PPKO mice, we evaluated AKT phosphorylation in major insulin-responsive tissues: the liver, muscle, and fat. We found that Pten loss in the pancreas causes the eleva-tion of AKT signaling in the liver. The phosphorylation of AKT and its downstream substrate GSK3β was increased in the liver of PPKO mice, while PTEN level was decreased without detectable excision of Pten allele in the liver of PPKO mice. Proteomics analysis revealed dramatically decreased level of 78-kDa glucose-regulated protein (GRP78) in the liver of PPKO mice, which may also contribute to the lower blood glucose level of PPKO mice fed with HFD. Together, our findings reveal a novel response in the liver to pancreatic defect in metabolic regulation, adding a new dimension to understanding diabetes resistance.

  3. Protein kinase A (PKA) phosphorylation of Na+/K+-ATPase opens intracellular C-terminal water pathway leading to third Na+-binding site in molecular dynamics simulations

    DEFF Research Database (Denmark)

    Poulsen, Hanne; Nissen, Poul; Mouritsen, Ole G.;

    2012-01-01

    a C-terminal hydrated pathway leading to D926, a transmembrane residue proposed to form part of the third sodium ion-binding site (4). Simulations of a S936E mutant form, for which only subtle effects are observed when expressed in Xenopus oocytes and studied with electrophysiology, does not mimic...

  4. Raf activation by Ras and promotion of cellular metastasis require phosphorylation of prohibitin in the raft domain of the plasma membrane.

    Science.gov (United States)

    Chiu, C-F; Ho, M-Y; Peng, J-M; Hung, S-W; Lee, W-H; Liang, C-M; Liang, S-M

    2013-02-01

    Prohibitin (PHB) is indispensable for Ras-induced Raf-1 activation, cell migration and growth; however, the exact role of PHB in the molecular pathogenesis of cancer metastasis remains largely unexamined. Here, we found a positive correlation between plasma membrane-associated PHB and the clinical stages of cancer. The level of PHB phosphorylated at threonine 258 (T258) and tyrosine 259 (Y259) in human cancer-cell membranes correlated with the invasiveness of cancer cells. Overexpression of phosphorylated PHB (phospho-PHB) in the lipid-raft domain of the cell membrane enhanced cell migration/invasion through PI3K/Akt and Raf-1/ERK activation. It also enhanced epithelial-mesenchymal transition, matrix metalloproteinase-2 activity and invasiveness of cancer cells in vitro. Immunoprecipitation analysis demonstrated that phospho-PHB associated with Raf-1, Akt and Ras in the membrane and was essential for the activation of Raf-1 signaling by Ras. Mice implanted with cancer cells stably overexpressing PHB in the plasma membrane showed enlarged cervical tumors, enhanced metastasis and shorter survival time compared with mice implanted with cancer cells without PHB overexpression. Dephosphorylation of PHB at T258 by site-directed mutagenesis diminished the in vitro and in vivo effects of PHB. These results suggest that increase in phospho-PHB T258 in the raft domain of the plasma membrane has a role in the Ras-driven activation of PI3K/Akt and Raf-1/ERK-signaling cascades and results in the promotion of cancer metastasis.

  5. Caffeic acid phenethyl ester causes p21 induction, Akt signaling reduction, and growth inhibition in PC-3 human prostate cancer cells.

    Directory of Open Access Journals (Sweden)

    Hui-Ping Lin

    Full Text Available Caffeic acid phenethyl ester (CAPE treatment suppressed proliferation, colony formation, and cell cycle progression in PC-3 human prostate cancer cells. CAPE decreased protein expression of cyclin D1, cyclin E, SKP2, c-Myc, Akt1, Akt2, Akt3, total Akt, mTOR, Bcl-2, Rb, as well as phosphorylation of Rb, ERK1/2, Akt, mTOR, GSK3α, GSK3β, PDK1; but increased protein expression of KLF6 and p21(Cip1. Microarray analysis indicated that pathways involved in cellular movement, cell death, proliferation, and cell cycle were affected by CAPE. Co-treatment of CAPE with chemotherapeutic drugs vinblastine, paclitaxol, and estramustine indicated synergistic suppression effect. CAPE administration may serve as a potential adjuvant therapy for prostate cancer.

  6. AKT activation drives the nuclear localization of CSE1L and a pro-oncogenic transcriptional activation in ovarian cancer cells.

    Science.gov (United States)

    Lorenzato, Annalisa; Biolatti, Marta; Delogu, Giuseppe; Capobianco, Giampiero; Farace, Cristiano; Dessole, Salvatore; Cossu, Antonio; Tanda, Francesco; Madeddu, Roberto; Olivero, Martina; Di Renzo, Maria Flavia

    2013-10-15

    The human homolog of the yeast cse1 gene (CSE1L) is over-expressed in ovarian cancer. CSE1L forms complex with Ran and importin-α and has roles in nucleocytoplasmic traffic and gene expression. CSE1L accumulated in the nucleus of ovarian cancer cell lines, while it was localized also in the cytoplasm of other cancer cell lines. Nuclear localization depended on AKT, which was constitutively active in ovarian cancer cells, as the CSE1L protein translocated to the cytoplasm when AKT was inactivated. Moreover, the expression of a constitutively active AKT forced the translocation of CSE1L from the cytoplasm to the nucleus in other cancer cells. Nuclear accrual of CSE1L was associated to the nuclear accumulation of the phosphorylated Ran Binding protein 3 (RanBP3), which depended on AKT as well. Also in samples of human ovarian cancer, AKT activation was associated to nuclear accumulation of CSE1L and phosphorylation of RanBP3. Expression profiling of ovarian cancer cells after CSE1L silencing showed that CSE1L was required for the expression of genes promoting invasion and metastasis. In agreement, CSE1L silencing impaired motility and invasiveness of ovarian cancer cells. Altogether these data show that in ovarian cancer cells activated AKT by affecting RanBP3 phosphorylation determines the nuclear accumulation of CSE1L and likely the nuclear concentration of transcription factors conveying pro-oncogenic signals. PMID:23948303

  7. Leucine minimizes denervation-induced skeletal muscle atrophy of rats through akt/mtor signaling pathways

    Directory of Open Access Journals (Sweden)

    Carolina Barbosa Ribeiro

    2015-03-01

    Full Text Available The aim of the present study was to evaluate the effect of leucine treatment (0.30 mM on muscle weight and signaling of myoproteins related to synthesis and degradation pathways of soleus muscle following seven days of complete sciatic nerve lesion.Wistar rats (n=24 of 3 to 4 months of age (192 ± 23 g were used. The animals were randomly distributed into four experimental groups (n=6/group: control, treated with leucine (L, denervated (D and denervated treated with leucine (DL.Dependent measures were proteins levels of AKT, AMPK, mTOR, and ACC performed by Western blot. Leucine induced a reduction in the phosphorylation of AMPK (p<0.05 by 16% in the L and by 68% in the DL groups as compared with control group. Denervation increased AMPK by 24% in the D group as compared with the control group (p<0.05. AKT was also modulated by denervation and leucine treatment, highlighted by the elevation of AKT phosphorylation in the D (65%, L (98% and DL (146% groups as compared with the control group (p<0.05. AKT phosphorylation was 49% higher in the D group as compared with the DL group.Furthermore, denervation decreased mTOR phosphorylation by 29% in the D group as compared with the control group. However, leucine treatment induced an increase of 49% in the phosphorylation of mTOR in the L group as compared with the control group, and an increase of 154% in the DL as compared with the D group ( p<0.05. ACC phosphorylation was 20% greater in the D group than the control group. Furthermore, ACC in the soleus was 22% lower in the in the L group and 50% lower in the DL group than the respective control group (p<0.05.In conclusion, leucine treatment minimized the deleterious effects of denervation on rat soleus muscle by increasing anabolic (AKT and mTOR and decreasing catabolic (AMPK pathways. These results may be interesting for muscle recovery following acute denervation, which may contribute to musculoskeletal rehabilitation after denervation.

  8. Fibronectin phosphorylation by ecto-protein kinase

    Energy Technology Data Exchange (ETDEWEB)

    Imada, Sumi; Sugiyama, Yayoi; Imada, Masaru (Meiji Institute of Health Science, Odawara (Japan))

    1988-12-01

    The presence of membrane-associated, extracellular protein kinase (ecto-protein kinase) and its substrate proteins was examined with serum-free cultures of Swiss 3T3 fibroblast. When cells were incubated with ({gamma}-{sup 32})ATP for 10 min at 37{degree}C, four proteins with apparent molecular weights between 150 and 220 kDa were prominently phosphorylated. These proteins were also radiolabeled by lactoperoxidase catalyzed iodination and were sensitive to mild tryptic digestion, suggesting that they localized on the cell surface or in the extracellular matrix. Phosphorylation of extracellular proteins with ({gamma}-{sup 32}P)ATP in intact cell culture is consistent with the existence of ecto-protein kinase. Anti-fibronectin antibody immunoprecipitated one of the phosphoproteins which comigrated with a monomer and a dimer form of fibronectin under reducing and nonreducing conditions of electrophoresis, respectively. The protein had affinity for gelatin as demonstrated by retention with gelatin-conjugated agarose. This protein substrate of ecto-protein kinase was thus concluded to be fibronectin. The sites of phosphorylation by ecto-protein kinase were compared with those of intracellularly phosphorylated fibronectin by the analysis of radiolabeled amino acids and peptides. Ecto-protein kinase phosphorylated fibronectin at serine and threonine residues which were distinct from the sites of intracellular fibronectin phosphorylation.

  9. Marine Cyclotripeptide X-13 Promotes Angiogenesis in Zebrafish and Human Endothelial Cells via PI3K/Akt/eNOS Signaling Pathways

    Directory of Open Access Journals (Sweden)

    Zhong Pei

    2012-06-01

    Full Text Available Cyclotripeptide X-13 is a core of novel marine compound xyloallenoide A isolated from mangrove fungus Xylaria sp. (no. 2508. We found that X-13 dose-dependently induced angiogenesis in zebrafish embryos and in human endothelial cells, which was accompanied by increased phosphorylation of eNOS and Akt and NO release. Inhibition of PI3K/Akt/eNOS by LY294002 or l-NAME suppressed X-13-induced angiogenesis. The present work demonstrates that X-13 promotes angiogenesis via PI3K/Akt/eNOS pathways.

  10. Breviscapine attenuatted contrast medium-induced nephropathy via PKC/Akt/MAPK signalling in diabetic mice.

    Science.gov (United States)

    Jiang, Wenbin; Li, Zhengwei; Zhao, Wei; Chen, Hao; Wu, Youyang; Wang, Yi; Shen, Zhida; He, Jialin; Chen, Shengyu; Zhang, Jiefang; Fu, Guosheng

    2016-01-01

    Contrast medium-induced nephropathy (CIN) remains a major cause of iatrogenic, drug-induced renal injury. Recent studies reveal that Breviscapine can ameliorate diabetic nephropathy in mice. Yet it remains unknown if Breviscapine could reduce CIN in diabetic mice. In this study, male C57/BL6J mice were randomly divided into 7 groups: control, diabetes mellitus, CIN, diabetes mellitus+CIN, diabetes mellitus+Breviscapine, CIN+Breviscapine and diabetes mellitus+CIN+Breviscapine. Model of CIN was induced by tail intravenous administration of iopromide and model of diabetes mellitus was induced by Streptozotocin intraperitoneally. Breviscapine was administered intragastrically for 4 weeks. Renal function parameters, kidney histology, markers of renal fibrosis, phosphorylation of protein kinase C/Akt/mitogen activated protein kinases were measured by western blot. We found out that diabetes mellitus aggravated CIN damage. Renal histological analysis showed Breviscapine reduced of renal fibrosis and tubular damage. Breviscapine was also shown markedly to ameliorate CIN fibrotic markers expression, reduced proteinuria and serum creatinine. Furthermore, Breviscapine decreased phosphorylation of PKCβII, Akt, JNK1/2 and p38. Therefore, Breviscapine treatment could ameliorate the development of CIN in diabetic mice, which was partly attributed to its suppression of renal fibrosis via phosphorylation of PKCβII/Akt/JNK1/2/p38 signalling.

  11. Dopamine D2 receptor-mediated Akt/PKB signalling: initiation by the D2S receptor and role in quinpirole-induced behavioural activation.

    Science.gov (United States)

    Chen, Han-Ting; Ruan, Nan-Yu; Chen, Jin-Chung; Lin, Tzu-Yung

    2012-09-24

    The short and long isoforms of the dopamine D2 receptor (D2S and D2L respectively) are highly expressed in the striatum. Functional D2 receptors activate an intracellular signalling pathway that includes a cAMP-independent route involving Akt/GSK3 (glycogen synthase kinase 3). To investigate the Akt/GSK3 response to the seldom-studied D2S receptor, we established a rat D2S receptor-expressing cell line [HEK (human embryonic kidney)-293/rD2S]. We found that in HEK-293/rD2S cells, the D2/D3 agonists bromocriptine and quinpirole significantly induced Akt and GSK3 phosphorylation, as well as ERK1/2 (extracellular-signal-regulated kinase 1/2) activation. The D2S receptor-induced Akt signals were profoundly inhibited by the internalization blockers monodansyl cadaverine and concanavalin A. Activation of the D2S receptor in HEK-293/rD2S cells appeared to trigger Akt/phospho-Akt translocation to the cell membrane. In addition to our cell culture experiments, we studied D2 receptor-dependent Akt in vivo by systemic administration of the D2/D3 agonist quinpirole. The results show that quinpirole evoked Akt-Ser473 phosphorylation in the ventral striatum. Furthermore, intra-accumbens administration of wortmannin, a PI3K (phosphoinositide 3-kinase) inhibitor, significantly suppressed the quinpirole-evoked behavioural activation. Overall, we demonstrate that activation of the dopamine D2S receptor stimulates Akt/GSK3 signalling. In addition, in vivo Akt activity in the ventral striatum appears to play an important role in systemic D2/D3 agonist-induced behavioural activation.

  12. Dopamine D2 receptor-mediated Akt/PKB signalling: initiation by the D2S receptor and role in quinpirole-induced behavioural activation

    Directory of Open Access Journals (Sweden)

    Jin‑Chung Chen

    2012-09-01

    Full Text Available The short and long isoforms of the dopamine D2 receptor (D2S and D2L respectively are highly expressed in the striatum. Functional D2 receptors activate an intracellular signalling pathway that includes a cAMP-independent route involving Akt/GSK3 (glycogen synthase kinase 3. To investigate the Akt/GSK3 response to the seldom-studied D2S receptor, we established a rat D2S receptor-expressing cell line [HEK (human embryonic kidney-293/rD2S]. We found that in HEK-293/rD2S cells, the D2/D3 agonists bromocriptine and quinpirole significantly induced Akt and GSK3 phosphorylation, as well as ERK1/2 (extracellular-signal-regulated kinase 1/2 activation. The D2S receptor-induced Akt signals were profoundly inhibited by the internalization blockers monodansyl cadaverine and concanavalin A. Activation of the D2S receptor in HEK-293/rD2S cells appeared to trigger Akt/phospho-Akt translocation to the cell membrane. In addition to our cell culture experiments, we studied D2 receptor-dependent Akt in vivo by systemic administration of the D2/D3 agonist quinpirole. The results show that quinpirole evoked Akt-Ser473 phosphorylation in the ventral striatum. Furthermore, intra-accumbens administration of wortmannin, a PI3K (phosphoinositide 3-kinase inhibitor, significantly suppressed the quinpirole-evoked behavioural activation. Overall, we demonstrate that activation of the dopamine D2S receptor stimulates Akt/GSK3 signalling. In addition, in vivo Akt activity in the ventral striatum appears to play an important role in systemic D2/D3 agonist-induced behavioural activation.

  13. Mechanism of Akt1 inhibition of breast cancer cell invasionreveals a protumorigenic role for TSC2

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hong; Radisky, Derek C.; Nelson, Celeste M.; Zhang, Hui; Fata, Jimmie; Roth, Richard A.; Bissell, Mina J.

    2006-02-07

    Akt1 is frequently upregulated in human tumors, and has been shown to accelerate cell proliferation and to suppress programmed cell death; consequently, inhibiting the activity of Akt1 has been seen as an attractive target for therapeutic intervention. Paradoxically, hyperactivation of the Akt1 oncogene can also prevent the invasive behavior that underlies progression to metastasis. Here we show that overexpression of activated myr-Akt1 in human breast cancer cells phosphorylates and thereby targets the tumor suppressor tuberous sclerosis complex 2 (TSC2) for degradation, leading to reduced Rho-GTPase activity, decreased actin stress fibers and focal adhesions, and reduced motility and invasion. Overexpression of TSC2 rescues the migration phenotype of myr-Akt1-expressing tumor cells, and high levels of TSC2 in breast cancer patients correlate with increased metastasis and reduced survival. These data indicate that the functional properties of genes designated as oncogenes or tumor suppressor genes depends on the context of the cell type and the tissues studied, and suggest the need for caution in designing therapies targeting the function of individual genes in epithelial tissues.

  14. The role of Akt on Arsenic trioxide suppression of 3T3-L1 preadipocyte differentiation

    Institute of Scientific and Technical Information of China (English)

    Zhi Xin WANG; Chun Sun JIANG; Lei LIU; Xiao Hui WANG; Hai Jing JIN; Qiao WU; Quan CHEN

    2005-01-01

    The present study investigates the molecular details of how arsenic trioxide inhibits preadipocyte differentiation and examines the role of Akt/PKB in regulation of differentiation and apoptosis. Continual exposure of arsenic trioxide, at the clinic achievable dosage that does not induce apoptosis, suppressed 3T3-L1 cell differentiation into fat cells by inhibiting the expression of PPARγ and C/EBPα and disrupting the interaction between PPARγ and RXRα, which determines the programming of the adipogenic genes. Interestingly, if we treated the cells for 12 or 24 h and then withdrew arsenic trioxide, the cells were able to differentiate to the comparable levels of untreated cells as assayed by the activity of GAPDH, the biochemical marker of preadipocyte differentiation. Long term treatment blocked the differentiation and the activity of GAPDH could not recover to the comparable levels of untreated cells. Continual exposure of arsenic trioxide caused accumulation in G2/M phase and the accumulation of p21. We found that arsenic trioxide induced the expression and the phosphorylation of Akt/PKB and it inhibited the interaction between Akt/PKB and PPARγ. Akt/PKB inhibitor appears to block the arsenic trioxide suppression of differentiation. Our results suggested that Akt/PKB may play a role in suppression of apoptosis and negatively regulate preadipocyte differentiation.

  15. Mechanistic Analysis of AKT1 Regulation by the CBL-CIPK-PP2CA Interactions

    Institute of Scientific and Technical Information of China (English)

    Wen-Zhi Lan; Sung-Chul Lee; Yu-Fen Che; Yuan-Qing Jiang; Sheng Luan

    2011-01-01

    T Arabidopsis K+ transporter 1 (AKT1) participates in K+ uptake in roots, especially under low-K conditions. We recently identified a Ca2+ signaling pathway consisting of multiple calcineurin B-like calcium sensors (CBLs) and multiple target kinases (CBL-interacting protein kinases or CIPKs) that phosphorylate and activate AKT1, whereas a specific PP2C-type phosphatase inactivates CIPK-dependent AKT1 activity. In this study, we analyzed the interactions between PP2Cs and the CBL-CIPK pathway and found previously unsuspected mechanisms underlying the CBL-CIPK-PP2C signaling processes. The interaction between the CIPKs and PP2Cs involves the kinase domain of the CIPK component, in addition to the protein phosphatase interacting motif (PPI) in the regulatory domain. Furthermore, specific CBLs physically interact with and inactivate PP2C phosphatases to recover the CIPK-dependent AKT1 channel activity. These findings provide further insights into the signaling network consisting of CBL-CIPK-PP2C interactions in the activation of the AKT1 channel.

  16. Roles of Akt and SGK1 in the Regulation of Renal Tubular Transport

    Directory of Open Access Journals (Sweden)

    Nobuhiko Satoh

    2015-01-01

    Full Text Available A serine/threonine kinase Akt is a key mediator in various signaling pathways including regulation of renal tubular transport. In proximal tubules, Akt mediates insulin signaling via insulin receptor substrate 2 (IRS2 and stimulates sodium-bicarbonate cotransporter (NBCe1, resulting in increased sodium reabsorption. In insulin resistance, the IRS2 in kidney cortex is exceptionally preserved and may mediate the stimulatory effect of insulin on NBCe1 to cause hypertension in diabetes via sodium retention. Likewise, in distal convoluted tubules and cortical collecting ducts, insulin-induced Akt phosphorylation mediates several hormonal signals to enhance sodium-chloride cotransporter (NCC and epithelial sodium channel (ENaC activities, resulting in increased sodium reabsorption. Serum- and glucocorticoid-inducible kinase 1 (SGK1 mediates aldosterone signaling. Insulin can stimulate SGK1 to exert various effects on renal transporters. In renal cortical collecting ducts, SGK1 regulates the expression level of ENaC through inhibition of its degradation. In addition, SGK1 and Akt cooperatively regulate potassium secretion by renal outer medullary potassium channel (ROMK. Moreover, sodium-proton exchanger 3 (NHE3 in proximal tubules is possibly activated by SGK1. This review focuses on recent advances in understanding of the roles of Akt and SGK1 in the regulation of renal tubular transport.

  17. TNF-alpha stimulates Akt by a distinct aPKC-dependent pathway in premalignant keratinocytes

    DEFF Research Database (Denmark)

    Faurschou, A.; Gniadecki, R.

    2008-01-01

    , ERK1/2 and p38. The specific peptide blocking the activity of the atypical protein kinase C (aPKC) species zeta and iota/lambda abrogated the effects of TNF-alpha on Akt and ERK1/2 but increased the activation of p38. The TNF-alpha-dependent phosphorylation of Akt-ERK1/2 was slightly decreased by NF......B- and OH-dependent pathway resulting in the activation of survival and mitogenic pathways mediated by Akt and ERK1/2, and a signalling pathway conveyed by p38 that contributes to Akt activation but is suppressed by aPKC. Our data may be utilized in the development of more selective anti...... kappaB inhibition and in the presence of p38 blockers. Akt/ERK signalling but not p38 activation was abolished in the presence of the iron chelator desferroxamine that blocks formation of hydroxyl ( OH) radicals. Thus, the TNF-alpha signalling in keratinocytes seems to bifurcate into an aPKC-, NFk...

  18. VAMP-associated protein B (VAPB) promotes breast tumor growth by modulation of Akt activity.

    Science.gov (United States)

    Rao, Meghana; Song, Wenqiang; Jiang, Aixiang; Shyr, Yu; Lev, Sima; Greenstein, David; Brantley-Sieders, Dana; Chen, Jin

    2012-01-01

    VAPB (VAMP- associated protein B) is an ER protein that regulates multiple biological functions. Although aberrant expression of VAPB is associated with breast cancer, its function in tumor cells is poorly understood. In this report, we provide evidence that VAPB regulates breast tumor cell proliferation and AKT activation. VAPB protein expression is elevated in primary and metastatic tumor specimens, and VAPB mRNA expression levels correlated negatively with patient survival in two large breast tumor datasets. Overexpression of VAPB in mammary epithelial cells increased cell growth, whereas VAPB knockdown in tumor cells inhibited cell proliferation in vitro and suppressed tumor growth in orthotopic mammary gland allografts. The growth regulation of mammary tumor cells controlled by VAPB appears to be mediated, at least in part, by modulation of AKT activity. Overexpression of VAPB in MCF10A-HER2 cells enhances phosphorylation of AKT. In contrast, knockdown of VAPB in MMTV-Neu tumor cells inhibited pAKT levels. Pharmacological inhibition of AKT significantly reduced three-dimensional spheroid growth induced by VAPB. Collectively, the genetic, functional and mechanistic analyses suggest a role of VAPB in tumor promotion in human breast cancer.

  19. VAMP-associated protein B (VAPB promotes breast tumor growth by modulation of Akt activity.

    Directory of Open Access Journals (Sweden)

    Meghana Rao

    Full Text Available VAPB (VAMP- associated protein B is an ER protein that regulates multiple biological functions. Although aberrant expression of VAPB is associated with breast cancer, its function in tumor cells is poorly understood. In this report, we provide evidence that VAPB regulates breast tumor cell proliferation and AKT activation. VAPB protein expression is elevated in primary and metastatic tumor specimens, and VAPB mRNA expression levels correlated negatively with patient survival in two large breast tumor datasets. Overexpression of VAPB in mammary epithelial cells increased cell growth, whereas VAPB knockdown in tumor cells inhibited cell proliferation in vitro and suppressed tumor growth in orthotopic mammary gland allografts. The growth regulation of mammary tumor cells controlled by VAPB appears to be mediated, at least in part, by modulation of AKT activity. Overexpression of VAPB in MCF10A-HER2 cells enhances phosphorylation of AKT. In contrast, knockdown of VAPB in MMTV-Neu tumor cells inhibited pAKT levels. Pharmacological inhibition of AKT significantly reduced three-dimensional spheroid growth induced by VAPB. Collectively, the genetic, functional and mechanistic analyses suggest a role of VAPB in tumor promotion in human breast cancer.

  20. P3DB: An Integrated Database for Plant Protein Phosphorylation

    Directory of Open Access Journals (Sweden)

    Qiuming eYao

    2012-09-01

    Full Text Available Protein phosphorylation is widely recognized as the most pervasive, enzyme-catalyzed post-translational modification in eukaryotes. In particular, plants have purloined this signaling mechanism as evidenced by the two-fold higher frequency of protein kinases within the genome compared to other eukaryotes. While all aspects of plant protein phosphorylation research have grown in the past ten years; phosphorylation site mapping using high-resolution mass spectrometry has grown exponentially. In Arabidopsis alone there are thousands of experimentally-determined phosphorylation sites. To archive these events in a user-intuitive format we have developed P3DB, The Plant Protein Phosphorylation Database (p3db.org. This database is a repository for plant protein phosphorylation site data, currently hosting information on 32,963 non-redundant sites collated from 23 experimental studies from seven plant species. These data can be queried for a protein-of-interest using an integrated BLAST function to query similar sequences with known phosphorylation sites among the multiple plants currently investigated. Thus, this resource can help identify functionally-conserved phosphorylation sites in plants using a multi-system approach.

  1. A Crystallographic Snapshot of Tyrosine Trans-phosphorylation in Action

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.; Xu, C; Ma, J; Eliseenkova, A; Li, W; Pollock, P; Pitteloud, N; Miller, W; Neubert, T; Mohammadi, M

    2008-01-01

    Tyrosine trans-phosphorylation is a key event in receptor tyrosine kinase signaling, yet, the structural basis for this process has eluded definition. Here, we present the crystal structure of the FGF receptor 2 kinases caught in the act of trans-phosphorylation of Y769, the major C-terminal phosphorylation site. The structure reveals that enzyme- and substrate-acting kinases engage each other through elaborate and specific interactions not only in the immediate vicinity of Y769 and the enzyme active site, but also in regions that are as much of 18 {angstrom} away from D626, the catalytic base in the enzyme active site. These interactions lead to an unprecedented level of specificity and precision during the trans-phosphorylation on Y769. Time-resolved mass spectrometry analysis supports the observed mechanism of trans-phosphorylation. Our data provide a molecular framework for understanding the mechanism of action of Kallmann syndrome mutations and the order of trans-phosphorylation reactions in FGFRs. We propose that the salient mechanistic features of Y769 trans-phosphorylation are applicable to trans-phosphorylation of the equivalent major phosphorylation sites in many other RTKs.

  2. Oxidative phosphorylation revisited

    DEFF Research Database (Denmark)

    Nath, Sunil; Villadsen, John

    2015-01-01

    The fundamentals of oxidative phosphorylation and photophosphorylation are revisited. New experimental data on the involvement of succinate and malate anions respectively in oxidative phosphorylation and photophosphorylation are presented. These new data offer a novel molecular mechanistic...... are proton‐dicarboxylic acid anion cotransporters and not simply electrogenic proton translocators. These results necessitate revision of previous theories of biological energy transduction, coupling, and ATP synthesis. The novel molecular mechanism is extended to cover ATP synthesis in prokaryotes...

  3. Phosphorylation of Cdc5 regulates its accumulation

    Directory of Open Access Journals (Sweden)

    Simpson-Lavy Kobi J

    2011-12-01

    Full Text Available Abstract Background Cdc5 (polo kinase/Plk1 is a highly conserved key regulator of the S. cerevisiae cell cycle from S-phase until cytokinesis. However, much of the regulatory mechanisms that govern Cdc5 remain to be determined. Cdc5 is phosphorylated on up to 10 sites during mitosis. In this study, we investigated the function of phosphorylation site T23, the only full consensus Cdk1 (Cdc28 phosphorylation site present. Findings Cdc5T23A introduces a degron that reduces its cellular amount to undetectable levels, which are nevertheless sufficient for normal cell proliferation. The degron acts in cis and is reversed by N-terminal GFP-tagging. Cdk1 kinase activity is required to maintain Cdc5 levels during G2. This, Cdk1 inhibited, Cdc5 degradation is APC/CCdh1 independent and requires new protein synthesis. Cdc5T23E is hyperactive, and reduces the levels of Cdc5 (in trans and drastically reduces Clb2 levels. Conclusions Phosphorylation of Cdc5 by Cdk1 is required to maintain Cdc5 levels during G2. However, phosphorylation of T23 (probably by Cdk1 caps Cdc5 and other CLB2 cluster protein accumulation, preventing potential protein toxicity, which may arise from their overexpression or from APC/CCdh1 inactivation.

  4. PSEA: Kinase-specific prediction and analysis of human phosphorylation substrates

    OpenAIRE

    Sheng-Bao Suo; Jian-Ding Qiu; Shao-Ping Shi; Xiang Chen; Ru-Ping Liang

    2014-01-01

    Protein phosphorylation catalysed by kinases plays crucial regulatory roles in intracellular signal transduction. With the increasing number of kinase-specific phosphorylation sites and disease-related phosphorylation substrates that have been identified, the desire to explore the regulatory relationship between protein kinases and disease-related phosphorylation substrates is motivated. In this work, we analysed the kinases' characteristic of all disease-related phosphorylation substrates by...

  5. Impaired striatal Akt signaling disrupts dopamine homeostasis and increases feeding.

    Directory of Open Access Journals (Sweden)

    Nicole Speed

    Full Text Available BACKGROUND: The prevalence of obesity has increased dramatically worldwide. The obesity epidemic begs for novel concepts and therapeutic targets that cohesively address "food-abuse" disorders. We demonstrate a molecular link between impairment of a central kinase (Akt involved in insulin signaling induced by exposure to a high-fat (HF diet and dysregulation of higher order circuitry involved in feeding. Dopamine (DA rich brain structures, such as striatum, provide motivation stimuli for feeding. In these central circuitries, DA dysfunction is posited to contribute to obesity pathogenesis. We identified a mechanistic link between metabolic dysregulation and the maladaptive behaviors that potentiate weight gain. Insulin, a hormone in the periphery, also acts centrally to regulate both homeostatic and reward-based HF feeding. It regulates DA homeostasis, in part, by controlling a key element in DA clearance, the DA transporter (DAT. Upon HF feeding, nigro-striatal neurons rapidly develop insulin signaling deficiencies, causing increased HF calorie intake. METHODOLOGY/PRINCIPAL FINDINGS: We show that consumption of fat-rich food impairs striatal activation of the insulin-activated signaling kinase, Akt. HF-induced Akt impairment, in turn, reduces DAT cell surface expression and function, thereby decreasing DA homeostasis and amphetamine (AMPH-induced DA efflux. In addition, HF-mediated dysregulation of Akt signaling impairs DA-related behaviors such as (AMPH-induced locomotion and increased caloric intake. We restored nigro-striatal Akt phosphorylation using recombinant viral vector expression technology. We observed a rescue of DAT expression in HF fed rats, which was associated with a return of locomotor responses to AMPH and normalization of HF diet-induced hyperphagia. CONCLUSIONS/SIGNIFICANCE: Acquired disruption of brain insulin action may confer risk for and/or underlie "food-abuse" disorders and the recalcitrance of obesity. This molecular

  6. Stimulation of Wnt/β-Catenin Signaling to Improve Bone Development by Naringin via Interacting with AMPK and Akt

    Directory of Open Access Journals (Sweden)

    Dawei Wang

    2015-07-01

    Full Text Available Background/Aims: Naringin is a naturally existing compound in citrus fruits and has been elucidated to promote bone development and maintenance. Methods: The biological roles of naringin were investigated in vitro using osteoblast-like UMR-106 cells, and in vivo through performing ovariectomy to mimic osteoporosis in female mice. Since Wnt/β-catenin signaling is involved in osteoblastogenesis, the effect of naringin on Wnt/β-catenin signaling was studied. Results: Naringin promoted the mRNA and protein expressions of β-catenin, and improved Ser552 phosphorylation on β-catenin in UMR-106 cells, which leads to the activation of lymphoid enhancer factor (LEF/ T-cell factor (TCF transcription factors. The recruitments of protein kinase B (Akt inhibitor (Akti-1/2 and AMP-activated protein kinase (AMPK inhibitor (Dorsomorphin reduced the influence of naringin on β-catenin phosphorylation, suggesting naringin activates β-catenin via regulating Akt and AMPK. In ovariectomized (OVX mice naringin treatment improved the bone strength while AMPK and Akt inhibitors partly reversed the effect, which further proved the involvements of Akt and AMPK in the action of naringin in vivo. Conclusion: Our study points to a novel finding on the mechanism of naringin in facilitating bone formation via Akt and AMPK signaling.

  7. SP600125 Induces Src and Type I IGF Receptor Phosphorylation Independent of JNK

    Directory of Open Access Journals (Sweden)

    Qingbin Kong

    2014-09-01

    Full Text Available c-Jun N-terminal kinases (JNK are members of the mitogen-activated protein kinase (MAPK family that have important roles in signal transduction. The small molecule SP600125 is widely used in biochemical studies as a JNK inhibitor. However, recent studies indicate that SP600125 may also act independent of JNK. Here, we report that SP600125 can induce Src, type I insulin-like growth factor receptor (IGF-IR, Akt and Erk1/2 phosphorylation. Notably, these effects are independent of its inhibition of JNK. Inhibition of Src abrogates the stimulation of IGF-IR, Akt and Erk1/2 phosphorylation. IGF-IR knockdown blunts the induction of both Akt and Erk1/2 phosphorylation by SP600125. Moreover, combination of SP600125 and the Src inhibitor saracatinib synergistically inhibits cell proliferation. We conclude that SP600125 can activate Src-IGF-IR-Akt/Erk1/2 signaling pathways independent of JNK.

  8. Compartment-Specific Phosphorylation of Squid Neurofilaments.

    Science.gov (United States)

    Grant, Philip; Pant, Harish C

    2016-01-01

    Studies of the giant axon and synapse of third-order neurons in the squid stellate ganglion have provided a vast literature on neuronal physiology and axon transport. Large neuronal size also lends itself to comparative biochemical studies of cell body versus axon. These have focused on the regulation of synthesis, assembly, posttranslational modification and function of neuronal cytoskeletal proteins (microtubules (MTs) and neurofilaments (NFs)), the predominant proteins in axoplasm. These contribute to axonal organization, stability, transport, and impulse transmission responsible for rapid contractions of mantle muscles underlying jet propulsion. Studies of vertebrate NFs have established an extensive literature on NF structure, organization, and function; studies of squid NFs, however, have made it possible to compare compartment-specific regulation of NF synthesis, assembly, and function in soma versus axoplasm. Since NFs contain over 100 eligible sites for phosphorylation by protein kinases, the compartment-specific patterns of phosphorylation have been a primary focus of biochemical studies. We have learned that NF phosphorylation is tightly compartmentalized; extensive phosphorylation occurs only in the axonal compartment in squid and in vertebrate neurons. This extensive phosphorylation plays a key role in organizing NFs, in association with microtubules (MTs), into a stable, dynamic functional lattice that supports axon growth, diameter, impulse transmission, and synaptic activity. To understand how cytoskeletal phosphorylation is topographically regulated, the kinases and phosphatases, bound to NFs isolated from cell bodies and axoplasm, have also been studied.

  9. Protein phosphorylation during coconut zygotic embryo development

    International Nuclear Information System (INIS)

    Evidence was obtained on the occurrence of protein threonine, serine, and tyrosine (Tyr) kinases in developing coconut (Cocos nucifera L.) zygotic embryos, based on in vitro phosphorylation of proteins in the presence of [gamma-32P]ATP, alkaline treatment, and thin-layer chromatography analysis, which showed the presence of [32P]phosphoserine, [32P]phosphothreonine, and [32P]phosphotyrosine in [32P]-labeled protein hydrolyzates. Tyr kinase activity was further confirmed in extracts of embryos at different stages of development using antiphosphotyrosine monoclonal antibodies and the synthetic peptide derived from the amino acid sequence surrounding the phosphorylation site in pp60src (RR-SRC), which is specific for Tyr kinases. Anti-phosphotyrosine western blotting revealed a changing profile of Tyr-phosphorylated proteins during embryo development. Tyr kinase activity, as assayed using RR-SRC, also changed during embryo development, showing two peaks of activity, one during early and another during late embryo development. In addition, the use of genistein, a Tyr kinase inhibitor, diminished the ability of extracts to phosphorylate RR-SRC. Results presented here show the occurrence of threonine, serine, and Tyr kinases in developing coconut zygotic embryos, and suggest that protein phosphorylation, and the possible inference of Tyr phosphorylation in particular, may play a role in the coordination of the development of embryos in this species

  10. The Novel Small Molecule Inhibitor, OSU-T315, Suppresses Vestibular Schwannoma and Meningioma Growth by Inhibiting PDK2 Function in the AKT Pathway Activation

    Science.gov (United States)

    Mercado-Pimentel, ME; Igarashi, S; Dunn, AM; Behbahani, M; Miller, C; Read, CM; Jacob, A

    2016-01-01

    Activation of PKB/AKT signaling, which requires PDK1 and PDK2 function, drives Vestibular Schwannoma (VS) and meningioma growth. PDK2 function is defined as a molecule that phosphorylates AKT-Ser473. Integrin-Linked Kinase (ILK) functions as PDK2 in PKB/AKT activation in many cancers; therefore, we hypothesized that OSU-T315, a small molecule ILK inhibitor, will inhibit the ILK-PDK2 function in PKB/AKT signaling activation in VS and meningioma cell growth. OSU-T315 decreased cell viability at IC50 < 2μM in VS (HEI193) and meningioma (Ben-Men-1) cell lines, in primary cells at < 3.5μM, while in normal primary Schwann cells at 7.1μM. OSU-T315 inhibits AKT signaling by decreasing phosphorylation at AKT-Ser473, AKT-Thr308, ILK-Ser246 and ILK-Thr173. In addition, OSU-T315 affected the phosphorylation or expression levels of AKT downstream proliferation effectors as well as autophagy markers. Flow cytometry shows that OSU-T315 increased the percentage of cells arrested at G2/M for both, HEI193 (39.99%) and Ben-Men-1 (26.96%) cells, compared to controls (21.54%, 8.47%). Two hours of OSU-T315 treatment increased cell death in both cell lines (34.3%, 9.1%) versus untreated (12.1%, 8.1%). Though longer exposure increased cell death in Ben-Men-1, TUNEL assays showed that OSU-T315 does not induce apoptosis. OSU-T315 was primarily cytotoxic for HEI193 and Ben-Men-1 inducing a dysregulated autophagy. Our studies suggest that OSU-T315 has translational potential as a chemotherapeutic agent against VS and meningioma.

  11. Upregulation of AKT3 Confers Resistance to the AKT Inhibitor MK2206 in Breast Cancer.

    Science.gov (United States)

    Stottrup, Casey; Tsang, Tiffany; Chin, Y Rebecca

    2016-08-01

    Acquired resistance to molecular targeted therapy represents a major challenge for the effective treatment of cancer. Hyperactivation of the PI3K/AKT pathway is frequently observed in virtually all human malignancies, and numerous PI3K and AKT inhibitors are currently under clinical evaluation. However, mechanisms of acquired resistance to AKT inhibitors have yet to be described. Here, we use a breast cancer preclinical model to identify resistance mechanisms to a small molecule allosteric AKT inhibitor, MK2206. Using a step-wise and chronic high-dose exposure, breast cancer cell lines harboring oncogenic PI3K resistant to MK2206 were established. Using this model, we reveal that AKT3 expression is markedly upregulated in AKT inhibitor-resistant cells. Induction of AKT3 is regulated epigenetically by the bromodomain and extra terminal domain proteins. Importantly, knockdown of AKT3, but not AKT1 or AKT2, in resistant cells restores sensitivity to MK2206. AKT inhibitor-resistant cells also display an epithelial to mesenchymal transition phenotype as assessed by alterations in the levels of E-Cadherin, N-Cadherin, and vimentin, as well as enhanced invasiveness of tumor spheroids. Notably, the invasive morphology of resistant spheroids is diminished upon AKT3 depletion. We also show that resistance to MK2206 is reversible because upon drug removal resistant cells regain sensitivity to AKT inhibition, accompanied by reexpression of epithelial markers and reduction of AKT3 expression, implying that epigenetic reprogramming contributes to acquisition of resistance. These findings provide a rationale for developing therapeutics targeting AKT3 to circumvent acquired resistance in breast cancer. Mol Cancer Ther; 15(8); 1964-74. ©2016 AACR. PMID:27297869

  12. Sericin can reduce hippocampal neuronal apoptosis by activating the Akt signal transduction pathway in a rat model of diabetes mellitus

    Institute of Scientific and Technical Information of China (English)

    Zhihong Chen; Yaqiang He; Chengjun Song; Zhijun Dong; Zhejun Su; Jingfeng Xue

    2012-01-01

    In the present study, a rat model of type 2 diabetes mellitus was established by continuous peritoneal injection of streptozotocin. Following intragastric perfusion of sericin for 35 days, blood glucose levels significantly reduced, neuronal apoptosis in the hippocampal CA1 region decreased, hippocampal phosphorylated Akt and nuclear factor kappa B expression were enhanced, but Bcl-xL/Bcl-2 associated death promoter expression decreased. Results demonstrated that sericin can reduce hippocampal neuronal apoptosis in a rat model of diabetes mellitus by regulating abnormal changes in the Akt signal transduction pathway.

  13. Pyrrolidinium fullerene induces apoptosis by activation of procaspase-9 via suppression of Akt in primary effusion lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Tadashi [Department of Cell Biology, Kyoto Pharmaceutical University, Misasagi-Shichonocho 1, Yamashinaku, Kyoto 607-8412 (Japan); Nakamura, Shigeo [Department of Chemistry, Nippon Medical School, 1-7-1 Kyonan-cho, Musashino, Tokyo 180-0023 (Japan); Ono, Toshiya; Ui, Sadaharu [Department of Biotechnology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Kofu 400-8511 (Japan); Yagi, Syota; Kagawa, Hiroki [Department of Cell Biology, Kyoto Pharmaceutical University, Misasagi-Shichonocho 1, Yamashinaku, Kyoto 607-8412 (Japan); Watanabe, Hisami [Center of Molecular Biosciences, Tropical Biosphere Research Center, University of the Ryukyus, 1 Senbaru, Nishihara-cho, Okinawa 903-0213 (Japan); Ohe, Tomoyuki; Mashino, Tadahiko [Department of Pharmaceutical Sciences, Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato-ku, Tokyo 105-8512 (Japan); Fujimuro, Masahiro, E-mail: fuji2@mb.kyoto-phu.ac.jp [Department of Cell Biology, Kyoto Pharmaceutical University, Misasagi-Shichonocho 1, Yamashinaku, Kyoto 607-8412 (Japan)

    2014-08-15

    Highlights: • Seven fullerenes were evaluated in terms of their cytotoxic effects on B-lymphomas. • Pyrrolidinium fullerene induced apoptosis of KSHV-infected B-lymphoma PEL cells. • The activation of Akt is essential for PEL cell survival. • Pyrrolidinium fullerene activated caspase-9 by inactivating Akt in PEL cells. • Pyrrolidinium fullerene have potential as novel drugs for the treatment of PEL. - Abstract: Primary effusion lymphoma (PEL) is a subtype of non-Hodgkin’s B-cell lymphoma and is an aggressive neoplasm caused by Kaposi’s sarcoma-associated herpesvirus (KSHV) in immunosuppressed patients. In general, PEL cells are derived from post-germinal center B-cells and are infected with KSHV. To evaluate potential novel anti-tumor compounds against KSHV-associated PEL, seven water-soluble fullerene derivatives were evaluated as potential drug candidates for the treatment of PEL. Herein, we discovered a pyrrolidinium fullerene derivative, 1,1,1′,1′-tetramethyl [60]fullerenodipyrrolidinium diiodide, which induced apoptosis of PEL cells via a novel mechanism, the caspase-9 activation by suppressing the caspase-9 phosphorylation, causing caspase-9 inactivation. Pyrrolidinium fullerene treatment reduced significantly the viability of PEL cells compared with KSHV-uninfected lymphoma cells, and induced the apoptosis of PEL cells by activating caspase-9 via procaspase-9 cleavage. Pyrrolidinium fullerene additionally reduced the Ser473 phosphorylation of Akt and Ser196 of procaspase-9. Ser473-phosphorylated Akt (i.e., activated Akt) phosphorylates Ser196 in procaspase-9, causing inactivation of procaspase-9. We also demonstrated that Akt inhibitors suppressed the proliferation of PEL cells compared with KSHV-uninfected cells. Our data therefore suggest that Akt activation is essential for cell survival in PEL and a pyrrolidinium fullerene derivative induced apoptosis by activating caspase-9 via suppression of Akt in PEL cells. In addition, we evaluated

  14. B7-H4 Treatment of T Cells Inhibits ERK, JNK, p38, and AKT Activation

    Science.gov (United States)

    Wang, Xiaojie; Hao, Jianqiang; Metzger, Daniel L.; Ao, Ziliang; Chen, Lieping; Ou, Dawei; Verchere, C. Bruce; Mui, Alice; Warnock, Garth L.

    2012-01-01

    B7-H4 is a newly identified B7 homolog that plays an important role in maintaining T-cell homeostasis by inhibiting T-cell proliferation and lymphokine-secretion. In this study, we investigated the signal transduction pathways inhibited by B7-H4 engagement in mouse T cells. We found that treatment of CD3+ T cells with a B7-H4.Ig fusion protein inhibits anti-CD3 elicited T-cell receptor (TCR)/CD28 signaling events, including phosphorylation of the MAP kinases, ERK, p38, and JNK. B7-H4.Ig treatment also inhibited the phosphorylation of AKT kinase and impaired its kinase activity as assessed by the phosphorylation of its endogenous substrate GSK-3. Expression of IL-2 is also reduced by B7-H4. In contrast, the phosphorylation state of the TCR proximal tyrosine kinases ZAP70 and lymphocyte-specific protein tyrosine kinase (LCK) are not affected by B7-H4 ligation. These results indicate that B7-H4 inhibits T-cell proliferation and IL-2 production through interfering with activation of ERK, JNK, and AKT, but not of ZAP70 or LCK. PMID:22238573

  15. B7-H4 Treatment of T Cells Inhibits ERK, JNK, p38, and AKT Activation.

    Directory of Open Access Journals (Sweden)

    Xiaojie Wang

    Full Text Available B7-H4 is a newly identified B7 homolog that plays an important role in maintaining T-cell homeostasis by inhibiting T-cell proliferation and lymphokine-secretion. In this study, we investigated the signal transduction pathways inhibited by B7-H4 engagement in mouse T cells. We found that treatment of CD3(+ T cells with a B7-H4.Ig fusion protein inhibits anti-CD3 elicited T-cell receptor (TCR/CD28 signaling events, including phosphorylation of the MAP kinases, ERK, p38, and JNK. B7-H4.Ig treatment also inhibited the phosphorylation of AKT kinase and impaired its kinase activity as assessed by the phosphorylation of its endogenous substrate GSK-3. Expression of IL-2 is also reduced by B7-H4. In contrast, the phosphorylation state of the TCR proximal tyrosine kinases ZAP70 and lymphocyte-specific protein tyrosine kinase (LCK are not affected by B7-H4 ligation. These results indicate that B7-H4 inhibits T-cell proliferation and IL-2 production through interfering with activation of ERK, JNK, and AKT, but not of ZAP70 or LCK.

  16. Stem cell factor protects against neuronal apoptosis by activating AKT/ERK in diabetic mice

    Directory of Open Access Journals (Sweden)

    J.-W. Li

    2009-11-01

    Full Text Available Neuronal apoptosis occurs in the diabetic brain due to insulin deficiency or insulin resistance, both of which reduce the expression of stem cell factor (SCF. We investigated the possible involvement of the activation of the MAPK/ERK and/or AKT pathways in neuroprotection by SCF in diabetes. Male C57/B6 mice (20-25 g were randomly divided into four groups of 10 animals each. The morphology of the diabetic brain in mice treated or not with insulin or SCF was evaluated by H&E staining and TUNEL. SCF, ERK1/2 and AKT were measured by Western blotting. In diabetic mice treated with insulin or SCF, there was fewer structural change and apoptosis in the cortex compared to untreated mice. The apoptosis rate of the normal group, the diabetic group receiving vehicle, the diabetic group treated with insulin, and the diabetic group treated with SCF was 0.54 ± 0.077%, 2.83 ± 0.156%, 1.86 ± 0.094%, and 1.78 ± 0.095% (mean ± SEM, respectively. SCF expression was lower in the diabetic cortex than in the normal cortex; however, insulin increased the expression of SCF in the diabetic cortex. Furthermore, expression of phosphorylated ERK1/2 and AKT was decreased in the diabetic cortex compared to the normal cortex. However, insulin or SCF could activate the phosphorylation of ERK1/2 and AKT in the diabetic cortex. The results suggest that SCF may protect the brain from apoptosis in diabetes and that the mechanism of this protection may, at least in part, involve activation of the ERK1/2 and AKT pathways. These results provide insight into the mechanisms by which SCF and insulin exert their neuroprotective effects in the diabetic brain.

  17. Protein kinase B/Akt activates c-Jun NH(2)-terminal kinase by increasing NO production in response to shear stress

    Science.gov (United States)

    Go, Y. M.; Boo, Y. C.; Park, H.; Maland, M. C.; Patel, R.; Pritchard, K. A. Jr; Fujio, Y.; Walsh, K.; Darley-Usmar, V.; Jo, H.

    2001-01-01

    Laminar shear stress activates c-Jun NH(2)-terminal kinase (JNK) by the mechanisms involving both nitric oxide (NO) and phosphatidylinositide 3-kinase (PI3K). Because protein kinase B (Akt), a downstream effector of PI3K, has been shown to phosphorylate and activate endothelial NO synthase, we hypothesized that Akt regulates shear-dependent activation of JNK by stimulating NO production. Here, we examined the role of Akt in shear-dependent NO production and JNK activation by expressing a dominant negative Akt mutant (Akt(AA)) and a constitutively active mutant (Akt(Myr)) in bovine aortic endothelial cells (BAEC). As expected, pretreatment of BAEC with the PI3K inhibitor (wortmannin) prevented shear-dependent stimulation of Akt and NO production. Transient expression of Akt(AA) in BAEC by using a recombinant adenoviral construct inhibited the shear-dependent stimulation of NO production and JNK activation. However, transient expression of Akt(Myr) by using a recombinant adenoviral construct did not induce JNK activation. This is consistent with our previous finding that NO is required, but not sufficient on its own, to activate JNK in response to shear stress. These results and our previous findings strongly suggest that shear stress triggers activation of PI3K, Akt, and endothelial NO synthase, leading to production of NO, which (along with O(2-), which is also produced by shear) activates Ras-JNK pathway. The regulation of Akt, NO, and JNK by shear stress is likely to play a critical role in its antiatherogenic effects.

  18. Phosphorylation of the Epstein-Barr virus nuclear antigen 2

    DEFF Research Database (Denmark)

    Grässer, F A; Göttel, S; Haiss, P;

    1992-01-01

    A major in vivo phosphorylation site of the Epstein-Barr virus nuclear antigen 2 (EBNA-2) was found to be localized at the C-terminus of the protein. In vitro phosphorylation studies using casein kinase 1 (CK-1) and casein kinase 2 (CK-2) revealed that EBNA-2 is a substrate for CK-2, but not for CK...

  19. Interplay between FOXO, TOR, and Akt

    OpenAIRE

    Hay, Nissim

    2011-01-01

    FOXO transcription factors have emerged as rheostats that coordinate the activities of Akt and target of rapamycin complexes (TORCs). This review summarizes the regulatory circuits mediated by the activation of FOXO, which in turn modulate Akt and TORCs activities. The biological significance of these regulatory circuits is discussed in this article.

  20. Fucoidan/FGF-2 induces angiogenesis through JNK- and p38-mediated activation of AKT/MMP-2 signalling

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Beom Su [Wonkwang Bone Regeneration Research Institute, Wonkwang University, Iksan, Jeonbuk 570-749 (Korea, Republic of); Bonecell Biotech Inc., 77, Dunsan-dong, Seo-gu, Daejeon 302-830 (Korea, Republic of); Park, Ji-Yun [Bonecell Biotech Inc., 77, Dunsan-dong, Seo-gu, Daejeon 302-830 (Korea, Republic of); Kang, Hyo-Jin [Wonkwang Bone Regeneration Research Institute, Wonkwang University, Iksan, Jeonbuk 570-749 (Korea, Republic of); Kim, Hyung-Jin [Department of Microbiology, School of Medicine, Wonkwang University, Iksan, Jeonbuk 570-749 (Korea, Republic of); Lee, Jun, E-mail: omslee@wku.ac.kr [Wonkwang Bone Regeneration Research Institute, Wonkwang University, Iksan, Jeonbuk 570-749 (Korea, Republic of); Bonecell Biotech Inc., 77, Dunsan-dong, Seo-gu, Daejeon 302-830 (Korea, Republic of)

    2014-08-08

    Graphical abstract: Schematic diagram of the angiogenic activity mechanism by FGF-2/fucoidan treatment in HUVECs. Fucoidan enhances the FGF-2-induced phosphorylation of p38, JNK, and ERK MAPKs. However, p38 and JNK were involved in AKT phosphorylation and MMP-2 activation and resulted in enhanced angiogenic activity, such as tube formation and migration, in HUVECs. - Highlights: • The angiogenic activity of fucoidan in HUVECs was explored. • Fucoidan enhanced HUVEC proliferation, migration, and tube formation. • Fucoidan enhanced angiogenesis through p38 and JNK but not ERK in HUVECs. • Fucoidan targeted angiogenesis-mediated AKT/MMP-2 signalling in HUVECs. - Abstract: Angiogenesis is an important biological process in tissue development and repair. Fucoidan has previously been shown to potentiate in vitro tube formation in the presence of basic fibroblast growth factor (FGF-2). However, the underlying molecular mechanism remains largely unknown. This study was designed to investigate the action of fucoidan in angiogenesis in human umbilical vein endothelial cells (HUVECs) and to explore fucoidan-signalling pathways. First, we evaluated the effect of fucoidan on cell proliferation. Matrigel-based tube formation and wound healing assays were performed to investigate angiogenesis. Matrix metalloproteinase-2 (MMP-2) mRNA expression and activity levels were analysed by reverse transcription polymerase chain reaction (RT-PCR) and zymography, respectively. Additionally, phosphorylation of mitogen-activated protein kinases (MAPKs) and protein kinase B (AKT) was detected by Western blot. The results indicate that fucoidan treatment significantly increased cell proliferation in the presence of FGF-2. Moreover, compared to the effect of FGF-2 alone, fucoidan and FGF-2 had a greater effect on tube formation and cell migration, and this effect was found to be synergistic. Furthermore, fucoidan enhanced the phosphorylation of extracellular signal-regulated kinase (ERK

  1. Multistep Phosphorylation by Oncogenic Kinases Enhances the Degradation of the NF2 Tumor Suppressor Merlin

    Directory of Open Access Journals (Sweden)

    Minja Laulajainen

    2011-07-01

    Full Text Available Mutations in the Neurofibromatosis 2 gene (NF2 predispose to tumors of the nervous system, mainly schwannomas and meningiomas. The NF2 gene encodes for the tumor suppressor protein merlin (moesin-ezrin-radixin-like protein, which functions as a linker between the plasma membrane and the cytoskeleton. Carboxyterminal phosphorylation affects merlin activity, but many open questions on the regulation of merlin function still remain. The phosphoinositide 3-kinase/Akt pathway is activated in human vestibular schwannoma, suggesting a role for Akt-dependent merlin regulation in the formation of these tumors. In this study, we identify merlin serine 10 as a novel substrate for Akt phosphorylation. We demonstrate that this N-terminal phosphorylation directs merlin for proteasome-mediated degradation and affects merlin binding to the E3 ligase component DCAF1. Our data indicate that sequential phosphorylation of merlin C- and N-terminus by different oncogenic kinases targets merlin for degradation and thus downregulates its activity. On the basis of these findings, we propose a model for a posttranslational mechanism of merlin inactivation.

  2. Hybrid cells derived from breast epithelial cell/breast cancer cell fusion events show a differential RAF-AKT crosstalk

    Directory of Open Access Journals (Sweden)

    Özel Cem

    2012-04-01

    Full Text Available Abstract Background The biological phenomenon of cell fusion has been linked to several characteristics of tumour progression, including an enhanced metastatogenic capacity and an enhanced drug resistance of hybrid cells. We demonstrated recently that M13SV1-EGFP-Neo breast epithelial cells exhibiting stem cell characteristics spontaneously fused with MDA-MB-435-Hyg breast cancer cells, thereby giving rise to stable M13MDA435 hybrid cells, which are characterised by a unique gene expression profile and migratory behaviour. Here we investigated the involvement of the PLC-β/γ1, PI3K/AKT and RAS-RAF-ERK signal transduction cascades in the EGF and SDF-1α induced migration of two M13MDA435 hybrid cell clones in comparison to their parental cells. Results Analysis of the migratory behaviour by using the three-dimensional collagen matrix migration assay showed that M13SV1-EGFP-Neo cells as well as M13MDA435 hybrid cells, but not the breast cancer cell line, responded to EGF stimulation with an increased locomotory activity. By contrast, SDF-1α solely stimulated the migration of M13SV1-EGFP-Neo cells, whereas the migratory activity of the other cell lines was blocked. Analysis of signal transduction cascades revealed a putative differential RAF-AKT crosstalk in M13MDA435-1 and -3 hybrid cell clones. The PI3K inhibitor Ly294002 effectively blocked the EGF induced migration of M13MDA435-3 hybrid cells, whereas the EGF induced locomotion of M13MDA435-1 hybrid cells was markedly increased. Analysis of RAF-1 S259 phosphorylation, being a major mediator of the negative regulation of RAF-1 by AKT, showed decreased pRAF-1 S259 levels in LY294002 treated M13MDA435-1 hybrid cells. By contrast, pRAF-1 S259 levels remained unaltered in the other cell lines. Inhibition of PI3K/AKT signalling by Ly294002 relieves the AKT mediated phosphorylation of RAF-1, thereby restoring MAPK signalling. Conclusions Here we show that hybrid cells could evolve exhibiting a

  3. ROLE OF PI3K-AKT-mTOR AND Wnt SIGNALING PATHWAYS IN G1-S TRANSITION OF CELL CYCLE IN CANCER CELLS

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    LAKSHMIPATHI eVADLAKONDA

    2013-04-01

    Full Text Available The PI3K–Akt pathway together with one of its downstream targets, the mechanistic target of rapamycin (mTOR is a highly deregulated pathway in cancers. There is a reciprocal relation between the Akt phosphorylation and mTOR complexes. Akt phosphorylated at T308 activates mTORC1 by inhibition of the tuberous sclerosis complex (TSC1/2, where as mTORC2 is recognized as the kinase that phosphorylates Akt at S473. Recent developments in the research on regulatory mechanisms of autophagy places mTORC1 mediated inhibition of autophagy at the central position in activation of proliferation and survival pathways in cells. Autophagy is a negative regulator of Wnt signaling pathway and the downstream effectors of Wnt signaling pathway, cyclin D1 and the c-Myc, are the key players in initiation of cell cycle and regulation of the G1-S transition in cancer cells. Production of reaction oxygen species (ROS, a common feature of a cancer cell metabolism, activates several downstream targets like the transcription factors FoxO, which play key roles in promoting the progression of cell cycle. A model is presented on the role of PI3K -Akt - mTOR and Wnt pathways in regulation of the progression of cell cycle through Go-G1-and S phases.

  4. Activating PER repressor through a DBT-directed phosphorylation switch.

    Directory of Open Access Journals (Sweden)

    Saul Kivimäe

    2008-07-01

    Full Text Available Protein phosphorylation plays an essential role in the generation of circadian rhythms, regulating the stability, activity, and subcellular localization of certain proteins that constitute the biological clock. This study examines the role of the protein kinase Doubletime (DBT, a Drosophila ortholog of human casein kinase I (CKIepsilon/delta. An enzymatically active DBT protein is shown to directly phosphorylate the Drosophila clock protein Period (PER. DBT-dependent phosphorylation sites are identified within PER, and their functional significance is assessed in a cultured cell system and in vivo. The per(S mutation, which is associated with short-period (19-h circadian rhythms, alters a key phosphorylation target within PER. Inspection of this and neighboring sequence variants indicates that several DBT-directed phosphorylations regulate PER activity in an integrated fashion: Alternative phosphorylations of two adjoining sequence motifs appear to be associated with switch-like changes in PER stability and repressor function.

  5. Akt Links Insulin Signaling to Albumin Endocytosis in Proximal Tubule Epithelial Cells.

    Science.gov (United States)

    Coffey, Sam; Costacou, Tina; Orchard, Trevor; Erkan, Elif

    2015-01-01

    Diabetes mellitus (DM) has become an epidemic, causing a significant decline in quality of life of individuals due to its multisystem involvement. Kidney is an important target organ in DM accounting for the majority of patients requiring renal replacement therapy at dialysis units. Microalbuminuria (MA) has been a valuable tool to predict end-organ damage in DM but its low sensitivity has driven research efforts to seek other alternatives. Albumin is taken up by albumin receptors, megalin and cubilin in the proximal tubule epithelial cells. We demonstrated that insulin at physiological concentrations induce albumin endocytosis through activation of protein kinase B (Akt) in proximal tubule epithelial cells. Inhibition of Akt by a phosphorylation deficient construct abrogated insulin induced albumin endocytosis suggesting a role for Akt in insulin-induced albumin endocytosis. Furthermore we demonstrated a novel interaction between Akt substrate 160kDa (AS160) and cytoplasmic tail of megalin. Mice with type 1 DM (T1D) displayed decreased Akt, megalin, cubilin and AS160 expression in their kidneys in association with urinary cubilin shedding preceding significant MA. Patients with T1D who have developed MA in the EDC (The Pittsburgh Epidemiology of Diabetes Complications) study demonstrated urinary cubilin shedding prior to development of MA. We hypothesize that perturbed insulin-Akt cascade in DM leads to alterations in trafficking of megalin and cubilin, which results in urinary cubilin shedding as a prelude to MA in early diabetic nephropathy. We propose that utilization of urinary cubilin shedding, as a urinary biomarker, will allow us to detect and intervene in diabetic nephropathy (DN) at an earlier stage. PMID:26465605

  6. Akt Links Insulin Signaling to Albumin Endocytosis in Proximal Tubule Epithelial Cells.

    Directory of Open Access Journals (Sweden)

    Sam Coffey

    Full Text Available Diabetes mellitus (DM has become an epidemic, causing a significant decline in quality of life of individuals due to its multisystem involvement. Kidney is an important target organ in DM accounting for the majority of patients requiring renal replacement therapy at dialysis units. Microalbuminuria (MA has been a valuable tool to predict end-organ damage in DM but its low sensitivity has driven research efforts to seek other alternatives. Albumin is taken up by albumin receptors, megalin and cubilin in the proximal tubule epithelial cells. We demonstrated that insulin at physiological concentrations induce albumin endocytosis through activation of protein kinase B (Akt in proximal tubule epithelial cells. Inhibition of Akt by a phosphorylation deficient construct abrogated insulin induced albumin endocytosis suggesting a role for Akt in insulin-induced albumin endocytosis. Furthermore we demonstrated a novel interaction between Akt substrate 160kDa (AS160 and cytoplasmic tail of megalin. Mice with type 1 DM (T1D displayed decreased Akt, megalin, cubilin and AS160 expression in their kidneys in association with urinary cubilin shedding preceding significant MA. Patients with T1D who have developed MA in the EDC (The Pittsburgh Epidemiology of Diabetes Complications study demonstrated urinary cubilin shedding prior to development of MA. We hypothesize that perturbed insulin-Akt cascade in DM leads to alterations in trafficking of megalin and cubilin, which results in urinary cubilin shedding as a prelude to MA in early diabetic nephropathy. We propose that utilization of urinary cubilin shedding, as a urinary biomarker, will allow us to detect and intervene in diabetic nephropathy (DN at an earlier stage.

  7. Akt mediated ROS-dependent selective targeting of mutant KRAS tumors.

    Science.gov (United States)

    Iskandar, Kartini; Rezlan, Majidah; Pervaiz, Shazib

    2014-10-01

    Reactive oxygen species (ROS) play a critical role in a variety of cellular processes, ranging from cell survival and proliferation to cell death. Previously, we reported the ability of a small molecule compound, C1, to induce ROS dependent autophagy associated apoptosis in human cancer cell lines and primary tumor cells (Wong C. et al. 2010). Our ongoing investigations have unraveled a hitherto undefined novel signaling network involving hyper-phosphorylation of Akt and Akt-mediated ROS production in cancer cell lines. Interestingly, drug-induced Akt activation is selectively seen in cell lines that carry mutant KRAS; HCT116 cells that carry the V13D KRAS mutation respond favorably to C1 while HT29 cells expressing wild type KRAS are relatively resistant. Of note, not only does the compound target mutant KRAS expressing cells but also induces RAS activation as evidenced by the PAK pull down assay. Corroborating this, pharmacological inhibition as well as siRNA mediated silencing of KRAS or Akt, blocked C1-induced ROS production and rescued tumor colony forming ability in HCT116 cells. To further confirm the involvement of KRAS, we made use of mutant KRAS transformed RWPE-1 prostate epithelial cells. Notably, drug-induced ROS generation and death sensitivity was significantly higher in RWPE-1-KRAS cells than the RWPE-1-vector cells, thus confirming the results obtained with mutant KRAS colorectal carcinoma cell line. Lastly, we made use of HCT116 mutant KRAS knockout cells (KO) where the mutant KRAS allele had been deleted, thus expressing a single wild-type KRAS allele. Exposure of the KO cells to C1 failed to induce Akt activation and mitochondrial ROS production. Taken together, results show the involvement of activated Akt in ROS-mediated selective targeting of mutant KRAS expressing tumors, which could have therapeutic implications given the paucity of chemotherapeutic strategies specifically targeting KRAS mutant cancers. PMID:26461287

  8. The Akt inhibitor MK-2206 enhances the cytotoxicity of paclitaxel (Taxol) and cisplatin in ovarian cancer cells.

    Science.gov (United States)

    Lin, Ying-Hsi; Chen, Bert Yu-Hung; Lai, Wei-Ting; Wu, Shao-Fu; Guh, Jih-Hwa; Cheng, Ann-Lii; Hsu, Lih-Ching

    2015-01-01

    Abnormalities in the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway are commonly observed in human cancers and contribute to chemotherapy resistance. Combination therapy, involving the use of molecular targeted agents and traditional cytotoxic drugs, may represent a promising strategy to lower resistance and enhance cytotoxicity. Here, we demonstrate the efficacy of an Akt inhibitor, MK-2206, in increasing the cytotoxic effect of either paclitaxel (Taxol) or cisplatin against the ovarian cancer cell lines SKOV3 (with constitutively active Akt) and ES2 (with inactive Akt). Sequential treatment of Taxol or cisplatin, followed by MK-2206, induced a synergistic inhibition of cell proliferation and effectively promoted cell death, either by inhibiting the phosphorylation of Akt and its downstream effectors 4E-BP1 and p70S6K in SKOV3 cells or by restoring p53 levels, which were downregulated after Taxol or cisplatin treatment, in ES2 cells. Combination treatment also downregulated the pro-survival protein Bcl-2 in both SKOV3 and ES2 cells, which may have contributed to cell death. In addition, we discovered that Taxol/MK-2206 or cisplatin/MK-2206 combination treatment resulted in significant enhancement of intracellular reactive oxygen species (ROS) induced by MK-2206, in both SKOV3 and ES2 cells; however, MK-2206-induced growth inhibition was reversed by a ROS scavenger only in ES2 cells. MK-2206 also suppressed DNA repair, particularly in SKOV3 cells. Taken together, our results demonstrate that the Akt inhibitor MK-2206 enhances the efficacy of cytotoxic agents in both Akt-active and Akt-inactive ovarian cancer cells but through different mechanisms.

  9. Novel PI3K/Akt inhibitors screened by the cytoprotective function of human immunodeficiency virus type 1 Tat.

    Directory of Open Access Journals (Sweden)

    Yuri Kim

    Full Text Available The PI3K/Akt pathway regulates various stress-related cellular responses such as cell survival, cell proliferation, metabolism and protein synthesis. Many cancer cell types display the activation of this pathway, and compounds inhibiting this cell survival pathway have been extensively evaluated as anti-cancer agents. In addition to cancers, several human viruses, such as HTLV, HPV, HCV and HIV-1, also modulate this pathway, presumably in order to extend the life span of the infected target cells for productive viral replication. The expression of HIV-1 Tat protein exhibited the cytoprotective effect in macrophages and a human microglial cell line by inhibiting the negative regulator of this pathway, PTEN. This cytoprotective effect of HIV-1 appears to contribute to the long-term survival and persistent HIV-1 production in human macrophage reservoirs. In this study we exploited the PI3K/Akt dependent cytoprotective effect of Tat-expressing CHME5 cells. We screened a collection of compounds known to modulate inflammation, and identified three novel compounds: Lancemaside A, Compound K and Arctigenin that abolished the cytoprotective phenotype of Tat-expressing CHME5 cells. All three compounds antagonized the kinase activity of Akt. Further detailed signaling studies revealed that each of these three compounds targeted different steps of the PI3K/Akt pathway. Arctigenin regulates the upstream PI3K enzyme from converting PIP2 to PIP3. Lancemaside A1 inhibited the movement of Akt to the plasma membrane, a critical step for Akt activation. Compound K inhibited Akt phosphorylation. This study supports that Tat-expressing CHME5 cells are an effective model system for screening novel PI3K/Akt inhibitors.

  10. Phosphorylation of plastoglobular proteins in Arabidopsis thaliana.

    Science.gov (United States)

    Lohscheider, Jens N; Friso, Giulia; van Wijk, Klaas J

    2016-06-01

    Plastoglobules (PGs) are plastid lipid-protein particles with a small specialized proteome and metabolome. Among the 30 core PG proteins are six proteins of the ancient ABC1 atypical kinase (ABC1K) family and their locations in an Arabidopsis mRNA-based co-expression network suggested central regulatory roles. To identify candidate ABC1K targets and a possible ABC1K hierarchical phosphorylation network within the chloroplast PG proteome, we searched Arabidopsis phosphoproteomics data from publicly available sources. Evaluation of underlying spectra and/or associated information was challenging for a variety of reasons, but supported pSer sites and a few pThr sites in nine PG proteins, including five FIBRILLINS. PG phosphorylation motifs are discussed in the context of possible responsible kinases. The challenges of collection and evaluation of published Arabidopsis phosphorylation data are discussed, illustrating the importance of deposition of all mass spectrometry data in well-organized repositories such as PRIDE and ProteomeXchange. This study provides a starting point for experimental testing of phosho-sites in PG proteins and also suggests that phosphoproteomics studies specifically designed toward the PG proteome and its ABC1K are needed to understand phosphorylation networks in these specialized particles. PMID:26962209

  11. EBP50 inhibits EGF-induced breast cancer cell proliferation by blocking EGFR phosphorylation.

    Science.gov (United States)

    Yao, Wenfang; Feng, Duiping; Bian, Weihua; Yang, Longyan; Li, Yang; Yang, Zhiyu; Xiong, Ying; Zheng, Junfang; Zhai, Renyou; He, Junqi

    2012-11-01

    Ezrin-radixin-moesin-binding phosphoprotein-50 (EBP50) suppresses breast cancer cell proliferation, potentially through its regulatory effect on epidermal growth factor receptor (EGFR) signaling, although the mechanism by which this occurs remains unknown. Thus in our studies, we aimed to determine the effect of EBP50 expression on EGF-induced cell proliferation and activation of EGFR signaling in the breast cancer cell lines, MDA-MB-231 and MCF-7. In MDA-MB-231 cells, which express low levels of EBP50, EBP50 overexpression inhibited EGF-induced cell proliferation, ERK1/2 and AKT phosphorylation. In MCF-7 cells, which express high levels of EBP50, EBP50 knockdown promoted EGF-induced cell proliferation, ERK1/2 and AKT phosphorylation. Knockdown of EBP50 in EBP50-overexpressed MDA-MB-231 cells abrogated the inhibitory effect of EBP50 on EGF-stimulated ERK1/2 phosphorylation and restoration of EBP50 expression in EBP50-knockdown MCF-7 cells rescued the inhibition of EBP50 on EGF-stimulated ERK1/2 phosphorylation, further confirming that the activation of EGF-induced downstream molecules could be specifically inhibited by EBP50 expression. Since EGFR signaling was triggered by EGF ligands via EGFR phosphorylation, we further detected the phosphorylation status of EGFR in the presence or absence of EBP50 expression. Overexpression of EBP50 in MDA-MB-231 cells inhibited EGF-stimulated EGFR phosphorylation, whereas knockdown of EBP50 in MCF-7 cells enhanced EGF-stimulated EGFR phosphorylation. Meanwhile, total expression levels of EGFR were unaffected during EGF stimulation. Taken together, our data shows that EBP50 can suppress EGF-induced proliferation of breast cancer cells by inhibiting EGFR phosphorylation and blocking EGFR downstream signaling in breast cancer cells. These results provide further insight into the molecular mechanism by which EBP50 regulates the development and progression of breast cancer.

  12. Akt- and CREB-Mediated Prostate Cancer Cell Proliferation Inhibition by Nexrutine, a Phellodendron amurense Extract

    Directory of Open Access Journals (Sweden)

    Gretchen E. Garcia

    2006-06-01

    Full Text Available Evidence from epidemiological studies suggests that plant-based diets can reduce the risk of prostate cancer. However, very little information is available concerning the use of botanicals in preventing prostate cancer. As a first step toward developing botanicals as prostate cancer preventives, we examined the effect of Nexrutine on human prostate cancer cells. Nexrutine is a herbal extract developed from Phellodendron amurense. Phellodendron extracts have been used traditionally in Chinese medicine for hundreds of years as an antidiarrheal, astringent, and anti-inflammatory agent. The present study investigated its potential antitumor effect on human prostate cancer cells. Our results suggest that it inhibits tumor cell proliferation through apoptosis induction and inhibition of cell survival signaling. The results of the present study indicate that Nexrutine treatment 1 inhibits the proliferation of both androgenresponsive and androgen-independent human prostate cancer cells through induction of apoptosis; 2 reduces levels of pAkt, phosphorylated cAMP response-binding protein (pCREB, and CREB DNA-binding activity; and 3 induces apoptosis in prostate cancer cells stably overexpressing Bcl-2. Further Akt kinase activity was reduced in cells treated with Nexrutine, and ectopic expression of myristoylated Akt protected from Nexrutine induced inhibition of proliferation, implicating a role for Akt signaling.

  13. PERK Utilizes Intrinsic Lipid Kinase Activity To Generate Phosphatidic Acid, Mediate Akt Activation, and Promote Adipocyte Differentiation

    Science.gov (United States)

    Bobrovnikova-Marjon, Ekaterina; Pytel, Dariusz; Riese, Matthew J.; Vaites, Laura Pontano; Singh, Nickpreet; Koretzky, Gary A.; Witze, Eric S.

    2012-01-01

    The endoplasmic reticulum (ER) resident PKR-like kinase (PERK) is necessary for Akt activation in response to ER stress. We demonstrate that PERK harbors intrinsic lipid kinase, favoring diacylglycerol (DAG) as a substrate and generating phosphatidic acid (PA). This activity of PERK correlates with activation of mTOR and phosphorylation of Akt on Ser473. PERK lipid kinase activity is regulated in a phosphatidylinositol 3-kinase (PI3K) p85α-dependent manner. Moreover, PERK activity is essential during adipocyte differentiation. Because PA and Akt regulate many cellular functions, including cellular survival, proliferation, migratory responses, and metabolic adaptation, our findings suggest that PERK has a more extensive role in insulin signaling, insulin resistance, obesity, and tumorigenesis than previously thought. PMID:22493067

  14. PERK utilizes intrinsic lipid kinase activity to generate phosphatidic acid, mediate Akt activation, and promote adipocyte differentiation.

    Science.gov (United States)

    Bobrovnikova-Marjon, Ekaterina; Pytel, Dariusz; Riese, Matthew J; Vaites, Laura Pontano; Singh, Nickpreet; Koretzky, Gary A; Witze, Eric S; Diehl, J Alan

    2012-06-01

    The endoplasmic reticulum (ER) resident PKR-like kinase (PERK) is necessary for Akt activation in response to ER stress. We demonstrate that PERK harbors intrinsic lipid kinase, favoring diacylglycerol (DAG) as a substrate and generating phosphatidic acid (PA). This activity of PERK correlates with activation of mTOR and phosphorylation of Akt on Ser473. PERK lipid kinase activity is regulated in a phosphatidylinositol 3-kinase (PI3K) p85α-dependent manner. Moreover, PERK activity is essential during adipocyte differentiation. Because PA and Akt regulate many cellular functions, including cellular survival, proliferation, migratory responses, and metabolic adaptation, our findings suggest that PERK has a more extensive role in insulin signaling, insulin resistance, obesity, and tumorigenesis than previously thought.

  15. Sequential phosphorylation of GRASP65 during mitotic Golgi disassembly

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    Danming Tang

    2012-09-01

    GRASP65 phosphorylation during mitosis and dephosphorylation after mitosis are required for Golgi disassembly and reassembly during the cell cycle. At least eight phosphorylation sites on GRASP65 have been identified, but whether they are modified in a coordinated fashion during mitosis is so far unknown. In this study, we raised phospho-specific antibodies that recognize phosphorylated T220/T224, S277 and S376 residues of GRASP65, respectively. Biochemical analysis showed that cdc2 phosphorylates all three sites, while plk1 enhances the phosphorylation. Microscopic studies using these antibodies for double and triple labeling demonstrate sequential phosphorylation and dephosphorylation during the cell cycle. S277 and S376 are phosphorylated from late G2 phase through metaphase until telophase when the new Golgi is reassembled. T220/224 is not modified until prophase, but is highly modified from prometaphase to anaphase. In metaphase, phospho-T220/224 signal localizes on both Golgi haze and mitotic Golgi clusters that represent dispersed Golgi vesicles and Golgi remnants, respectively, while phospho-S277 and S376 labeling is more concentrated on mitotic Golgi clusters. Expression of a phosphorylation-resistant GRASP65 mutant T220A/T224A inhibited mitotic Golgi fragmentation to a much larger extent than the expression of the S277A and S376A mutants. In cytokinesis, T220/224 dephosphorylation occurs prior to that of S277, but after S376. This study provides evidence that GRASP65 is sequentially phosphorylated and dephosphorylated during mitosis at different sites to orchestrate Golgi disassembly and reassembly during cell division, with phosphorylation of the T220/224 site being most critical in the process.

  16. Helicobacter pylori CagA induces tumor suppressor gene hypermethylation by upregulating DNMT1 via AKT-NFκB pathway in gastric cancer development.

    Science.gov (United States)

    Zhang, Bao-Gui; Hu, Lei; Zang, Ming De; Wang, He-Xiao; Zhao, Wei; Li, Jian-Fang; Su, Li-Ping; Shao, Zhifeng; Zhao, Xiaodong; Zhu, Zheng-Gang; Yan, Min; Liu, Bingya

    2016-03-01

    Methylation of CpG islands in tumor suppressor gene prompter is one of the most characteristic abnormalities in Helicobacter pylori (HP)-associated gastric carcinoma (GC). Here, we investigated the pathogenic and molecular mechanisms underlying hypermethylation of tumor suppressor genes in HP induced GC development. We found that tumor suppressor genes hypermethylation, represented by MGMT, positively correlated with CagA in clinical specimens, gastric tissues from HP infected C57 mice and GC cell lines transfected by CagA or treated by HP infection. CagA enhanced PDK1 and AKT interaction and increased AKT phosphorylation. The P-AKT subsequent activated NFκB, which then bound to DNMT1 promoter and increased its expression. Finally, the upregulated DNMT1 promoted tumor suppressor genes hypermethylation with MGMT as a representative. In conclusion, CagA increased tumor suppressor genes hypermethylation via stimulating DNMT1 expression through the AKT-NFκB pathway. PMID:26848521

  17. Characterization of AKT independent effects of the synthetic AKT inhibitors SH-5 and SH-6 using an integrated approach combining transcriptomic profiling and signaling pathway perturbations

    International Nuclear Information System (INIS)

    Signal transduction processes mediated by phosphatidyl inositol phosphates affect a broad range of cellular processes such as cell cycle progression, migration and cell survival. The protein kinase AKT is one of the major effectors in this signaling network. Chronic AKT activation contributes to oncogenic transformation and tumor development. Therefore, analogs of phosphatidyl inositol phosphates (PIAs) were designed as new small drugs to block AKT activity for cancer treatment. Here we characterize the biological effects of the PIAs SH-5 and SH-6 in colorectal cancer cell lines. Serum-starved or serum-supplemented human colorectal cancer cell lines SW480, HT29 and HCT116 were exposed to SH-5 and SH-6. AKT activation was determined by western blotting. Cell viability was assessed using a colorimetric XTT-based assay, apoptosis and cell cycle changes were monitored by FACS analysis. The dynamics of cell morphology alterations was evaluated by confocal and time-lapse microscopy. Transcriptional changes due to inhibitor treatment were analyzed using Affymetrix HG-U133A microarrays and RT-PCR. While the PIAs clearly reduce AKT phosphorylation in serum starved cells, we did not observe a significant reduction under serum supplemented conditions, giving us the opportunity to analyze AKT independent effects of these compounds. Both inhibitors induce broadly the same morphological alterations, in particular changes in cell shape and formation of intracellular vesicles. Moreover, we observed the induction of binucleated cells specifically in the SW480 cell line. Gene expression analysis revealed transcriptional alterations, which are mostly cell line specific. In accordance to the phenotype we found a gene group associated with mitosis and spindle organization down regulated in SW480 cells, but not in the other cell lines. A bioinformatics analysis using the Connectivity Map linked the gene expression pattern of the inhibitor treated SW480 cells to PKC signaling. Using

  18. Cyclic mechanical strain maintains Nanog expression through PI3K/Akt signaling in mouse embryonic stem cells

    Energy Technology Data Exchange (ETDEWEB)

    Horiuchi, Rie [Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Akimoto, Takayuki, E-mail: akimoto@m.u-tokyo.ac.jp [Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Institute for Biomedical Engineering, Consolidated Research Institute for Advanced Science and Medical Care, Waseda University, 513 Waseda-tsurumaki, Shinjuku, Tokyo 162-0041 (Japan); Hong, Zhang [Institute for Biomedical Engineering, Consolidated Research Institute for Advanced Science and Medical Care, Waseda University, 513 Waseda-tsurumaki, Shinjuku, Tokyo 162-0041 (Japan); Ushida, Takashi [Division of Regenerative Medical Engineering, Center for Disease Biology and Integrative Medicine, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan)

    2012-08-15

    Mechanical strain has been reported to affect the proliferation/differentiation of many cell types; however, the effects of mechanotransduction on self-renewal as well as pluripotency of embryonic stem (ES) cells remains unknown. To investigate the effects of mechanical strain on mouse ES cell fate, we examined the expression of Nanog, which is an essential regulator of self-renewal and pluripotency as well as Nanog-associated intracellular signaling during uniaxial cyclic mechanical strain. The mouse ES cell line, CCE was plated onto elastic membranes, and we applied 10% strain at 0.17 Hz. The expression of Nanog was reduced during ES cell differentiation in response to the withdrawal of leukemia inhibitory factor (LIF); however, two days of cyclic mechanical strain attenuated this reduction of Nanog expression. On the other hand, the cyclic mechanical strain promoted PI3K-Akt signaling, which is reported as an upstream of Nanog transcription. The cyclic mechanical strain-induced Akt phosphorylation was blunted by the PI3K inhibitor wortmannin. Furthermore, cytochalasin D, an inhibitor of actin polymerization, also inhibited the mechanical strain-induced increase in phospho-Akt. These findings imply that mechanical force plays a role in regulating Nanog expression in ES cells through the actin cytoskeleton-PI3K-Akt signaling. -- Highlights: Black-Right-Pointing-Pointer The expression of Nanog, which is an essential regulator of 'stemness' was reduced during embryonic stem (ES) cell differentiation. Black-Right-Pointing-Pointer Cyclic mechanical strain attenuated the reduction of Nanog expression. Black-Right-Pointing-Pointer Cyclic mechanical strain promoted PI3K-Akt signaling and mechanical strain-induced Akt phosphorylation was blunted by the PI3K inhibitor and an inhibitor of actin polymerization.

  19. Anti-malarial drug artesunate attenuates experimental allergic asthma via inhibition of the phosphoinositide 3-kinase/Akt pathway.

    Directory of Open Access Journals (Sweden)

    Chang Cheng

    Full Text Available BACKGROUND: Phosphoinositide 3-kinase (PI3K/Akt pathway is linked to the development of asthma. Anti-malarial drug artesunate is a semi-synthetic derivative of artemisinin, the principal active component of a medicinal plant Artemisia annua, and has been shown to inhibit PI3K/Akt activity. We hypothesized that artesunate may attenuate allergic asthma via inhibition of the PI3K/Akt signaling pathway. METHODOLOGY/PRINCIPAL FINDINGS: Female BALB/c mice sensitized and challenged with ovalbumin (OVA developed airway inflammation. Bronchoalveolar lavage fluid was assessed for total and differential cell counts, and cytokine and chemokine levels. Lung tissues were examined for cell infiltration and mucus hypersecretion, and the expression of inflammatory biomarkers. Airway hyperresponsiveness was monitored by direct airway resistance analysis. Artesunate dose-dependently inhibited OVA-induced increases in total and eosinophil counts, IL-4, IL-5, IL-13 and eotaxin levels in bronchoalveolar lavage fluid. It attenuated OVA-induced lung tissue eosinophilia and airway mucus production, mRNA expression of E-selectin, IL-17, IL-33 and Muc5ac in lung tissues, and airway hyperresponsiveness to methacholine. In normal human bronchial epithelial cells, artesunate blocked epidermal growth factor-induced phosphorylation of Akt and its downstream substrates tuberin, p70S6 kinase and 4E-binding protein 1, and transactivation of NF-κB. Similarly, artesunate blocked the phosphorylation of Akt and its downstream substrates in lung tissues from OVA-challenged mice. Anti-inflammatory effect of artesunate was further confirmed in a house dust mite mouse asthma model. CONCLUSION/SIGNIFICANCE: Artesunate ameliorates experimental allergic airway inflammation probably via negative regulation of PI3K/Akt pathway and the downstream NF-κB activity. These findings provide a novel therapeutic value for artesunate in the treatment of allergic asthma.

  20. Cyclic mechanical strain maintains Nanog expression through PI3K/Akt signaling in mouse embryonic stem cells

    International Nuclear Information System (INIS)

    Mechanical strain has been reported to affect the proliferation/differentiation of many cell types; however, the effects of mechanotransduction on self-renewal as well as pluripotency of embryonic stem (ES) cells remains unknown. To investigate the effects of mechanical strain on mouse ES cell fate, we examined the expression of Nanog, which is an essential regulator of self-renewal and pluripotency as well as Nanog-associated intracellular signaling during uniaxial cyclic mechanical strain. The mouse ES cell line, CCE was plated onto elastic membranes, and we applied 10% strain at 0.17 Hz. The expression of Nanog was reduced during ES cell differentiation in response to the withdrawal of leukemia inhibitory factor (LIF); however, two days of cyclic mechanical strain attenuated this reduction of Nanog expression. On the other hand, the cyclic mechanical strain promoted PI3K-Akt signaling, which is reported as an upstream of Nanog transcription. The cyclic mechanical strain-induced Akt phosphorylation was blunted by the PI3K inhibitor wortmannin. Furthermore, cytochalasin D, an inhibitor of actin polymerization, also inhibited the mechanical strain-induced increase in phospho-Akt. These findings imply that mechanical force plays a role in regulating Nanog expression in ES cells through the actin cytoskeleton-PI3K-Akt signaling. -- Highlights: ► The expression of Nanog, which is an essential regulator of “stemness” was reduced during embryonic stem (ES) cell differentiation. ► Cyclic mechanical strain attenuated the reduction of Nanog expression. ► Cyclic mechanical strain promoted PI3K-Akt signaling and mechanical strain-induced Akt phosphorylation was blunted by the PI3K inhibitor and an inhibitor of actin polymerization.

  1. Activation of Akt is essential for the propagation of mitochondrial respiratory stress signaling and activation of the transcriptional coactivator heterogeneous ribonucleoprotein A2.

    Science.gov (United States)

    Guha, Manti; Fang, Ji-Kang; Monks, Robert; Birnbaum, Morris J; Avadhani, Narayan G

    2010-10-15

    Mitochondrial respiratory stress (also called mitochondrial retrograde signaling) activates a Ca(2+)/calcineurin-mediated signal that culminates in transcription activation/repression of a large number of nuclear genes. This signal is propagated through activation of the regulatory proteins NFκB c-Rel/p50, C/EBPδ, CREB, and NFAT. Additionally, the heterogeneous ribonucleoprotein A2 (hnRNPA2) functions as a coactivator in up-regulating the transcription of Cathepsin L, RyR1, and Glut-4, the target genes of stress signaling. Activation of IGF1R, which causes a metabolic switch to glycolysis, cell invasiveness, and resistance to apoptosis, is a phenotypic hallmark of C2C12 myoblasts subjected to mitochondrial stress. In this study, we report that mitochondrial stress leads to increased expression, activation, and nuclear localization of Akt1. Mitochondrial respiratory stress also activates Akt1-gene expression, which involves hnRNPA2 as a coactivator, indicating a complex interdependency of these two factors. Using Akt1(-/-) mouse embryonic fibroblasts and Akt1 mRNA-silenced C2C12 cells, we show that Akt1-mediated phosphorylation is crucial for the activation and recruitment of hnRNPA2 to the enhanceosome complex. Akt1 mRNA silencing in mtDNA-depleted cells resulted in reversal of the invasive phenotype, accompanied by sensitivity to apoptotic stimuli. These results show that Akt1 is an important regulator of the nuclear transcriptional response to mitochondrial stress.

  2. Metabolomic analysis of akt1-mediated muscle hypertrophy in models of diet-induced obesity and age-related fat accumulation.

    Science.gov (United States)

    Cheng, Kian-Kai; Akasaki, Yuichi; Lecommandeur, Emmanuelle; Lindsay, Ross T; Murfitt, Steven; Walsh, Kenneth; Griffin, Julian L

    2015-01-01

    Akt1 is a serine/threonine kinase that promotes cell growth and survival. Previously, Akt1 activation in a double transgenic (DTG) mouse model fed a high-fat/high-sucrose (HF/HS) diet was found to promote type IIb muscle growth and to lead to a significant reduction in obesity. Here, we have used metabolomics to examine the metabolic perturbations in blood serum and liver and gastrocnemius tissues of the DTG mice. Multivariate statistics highlighted consistent metabolic changes in gastrocnemius muscle following Akt1 activation, which included significant reductions of serine and histidine-containing dipeptides (anserine and carnosine), in addition to increased concentrations of phosphorylated sugars. In addition, Akt1-mediated regression in obesity could be associated with increased glycolysis in gastrocnemius muscle as well as increased gluconeogenesis, glycogenolysis, and ketogenesis in the liver. In old DTG animals, Akt1 activation was found to improve glucose metabolism and confer a beneficial effect in the regression of age-related fat accumulation. This study identifies metabolic changes induced by Akt1-mediated muscle growth and demonstrates a cross-talk between distant organs that leads to a regression of fat mass. The current findings indicate that agents that promote Akt1 induction in muscle have utility in the regression of obesity. PMID:25231380

  3. Quercetin postconditioning attenuates myocardial ischemia/reperfusion injury in rats through the PI3K/Akt pathway

    Directory of Open Access Journals (Sweden)

    Y. Wang

    2013-09-01

    Full Text Available Quercetin (Que, a plant-derived flavonoid, has multiple benefical actions on the cardiovascular system. The current study investigated whether Que postconditioning has any protective effects on myocardial ischemia/reperfusion (I/R injury in vivo and its potential cardioprotective mechanisms. Male Sprague-Dawley rats were randomly allocated to 5 groups (20 animals/group: sham, I/R, Que postconditioning, Que+LY294002 [a phosphatidylinositol 3-kinase (PI3K/Akt signaling pathway inhibitor], and LY294002+I/R. I/R was produced by 30-min coronary occlusion followed by 2-h reperfusion. At the end of reperfusion, myocardial infarct size and biochemical changes were compared. Apoptosis was evaluated by both TUNEL staining and measurement of activated caspase-3 immunoreactivity. The phosphorylation of Akt and protein expression of Bcl-2 and Bax were determined by Western blotting. Que postconditioning significantly reduced infarct size and serum levels of creatine kinase and lactate dehydrogenase compared with the I/R group (all P<0.05. Apoptotic cardiomyocytes and caspase-3 immunoreactivity were also suppressed in the Que postconditioning group compared with the I/R group (both P<0.05. Akt phosphorylation and Bcl-2 expression increased after Que postconditioning, but Bax expression decreased. These effects were inhibited by LY294002. The data indicate that Que postconditioning can induce cardioprotection by activating the PI3K/Akt signaling pathway and modulating the expression of Bcl-2 and Bax proteins.

  4. Quercetin postconditioning attenuates myocardial ischemia/reperfusion injury in rats through the PI3K/Akt pathway

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y.; Zhang, Z.Z.; Wu, Y.; Ke, J.J.; He, X.H.; Wang, Y.L. [Department of Anesthesiology, Zhongnan Hospital, Wuhan University, Wuhan (China)

    2013-09-24

    Quercetin (Que), a plant-derived flavonoid, has multiple benefical actions on the cardiovascular system. The current study investigated whether Que postconditioning has any protective effects on myocardial ischemia/reperfusion (I/R) injury in vivo and its potential cardioprotective mechanisms. Male Sprague-Dawley rats were randomly allocated to 5 groups (20 animals/group): sham, I/R, Que postconditioning, Que+LY294002 [a phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway inhibitor], and LY294002+I/R. I/R was produced by 30-min coronary occlusion followed by 2-h reperfusion. At the end of reperfusion, myocardial infarct size and biochemical changes were compared. Apoptosis was evaluated by both TUNEL staining and measurement of activated caspase-3 immunoreactivity. The phosphorylation of Akt and protein expression of Bcl-2 and Bax were determined by Western blotting. Que postconditioning significantly reduced infarct size and serum levels of creatine kinase and lactate dehydrogenase compared with the I/R group (all P<0.05). Apoptotic cardiomyocytes and caspase-3 immunoreactivity were also suppressed in the Que postconditioning group compared with the I/R group (both P<0.05). Akt phosphorylation and Bcl-2 expression increased after Que postconditioning, but Bax expression decreased. These effects were inhibited by LY294002. The data indicate that Que postconditioning can induce cardioprotection by activating the PI3K/Akt signaling pathway and modulating the expression of Bcl-2 and Bax proteins.

  5. Quercetin postconditioning attenuates myocardial ischemia/reperfusion injury in rats through the PI3K/Akt pathway

    International Nuclear Information System (INIS)

    Quercetin (Que), a plant-derived flavonoid, has multiple benefical actions on the cardiovascular system. The current study investigated whether Que postconditioning has any protective effects on myocardial ischemia/reperfusion (I/R) injury in vivo and its potential cardioprotective mechanisms. Male Sprague-Dawley rats were randomly allocated to 5 groups (20 animals/group): sham, I/R, Que postconditioning, Que+LY294002 [a phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway inhibitor], and LY294002+I/R. I/R was produced by 30-min coronary occlusion followed by 2-h reperfusion. At the end of reperfusion, myocardial infarct size and biochemical changes were compared. Apoptosis was evaluated by both TUNEL staining and measurement of activated caspase-3 immunoreactivity. The phosphorylation of Akt and protein expression of Bcl-2 and Bax were determined by Western blotting. Que postconditioning significantly reduced infarct size and serum levels of creatine kinase and lactate dehydrogenase compared with the I/R group (all P<0.05). Apoptotic cardiomyocytes and caspase-3 immunoreactivity were also suppressed in the Que postconditioning group compared with the I/R group (both P<0.05). Akt phosphorylation and Bcl-2 expression increased after Que postconditioning, but Bax expression decreased. These effects were inhibited by LY294002. The data indicate that Que postconditioning can induce cardioprotection by activating the PI3K/Akt signaling pathway and modulating the expression of Bcl-2 and Bax proteins

  6. Morphine Suppresses T helper Lymphocyte Differentiation to Th1 Type Through PI3K/AKT Pathway.

    Science.gov (United States)

    Mao, Mao; Qian, Yanning; Sun, Jie

    2016-04-01

    To investigate the effect of morphine on T helper lymphocyte differentiation and PI3K/AKT pathway mechanism, CD4+ lymphocytes were treated by phorbol-myristate-acetate (25 ng/ml) (PMA) plus ionomycin (1 μg/ml) in the presence of various concentrations of morphine (25, 50, 100, 200 ng/ml) for 4 h. Th1 and Th2 subsets, supernatant cytokines, and PI3K, AKT, and protein kinase C-theta (PKC-θ) levels were detected. The Th1 cell percentage, Th1-derived cytokines, and ratio of Th1/Th2 decreased in the presence of morphine in a concentration-dependent manner. However, Th2 cell percentage kept stable after morphine treatment. The phosphorylation of PI3K and AKT decreased, but the phosphorylation of PKC-θ did not change in the presence of morphine. The decreased percentage of Th1 cells and ratio of Th1/Th2 was recovered by naloxone concentration-dependently. Morphine can inhibit the differentiation of Th1 lymphocytes and decrease the ratio of Th1/Th2 via the pathway of PI3K/AKT. The effect can be inhibited by naloxone. PMID:26883517

  7. Crosstalk between p38, Hsp25 and Akt in spinal motor neurons after sciatic nerve injury

    Science.gov (United States)

    Murashov, A. K.; Ul Haq, I.; Hill, C.; Park, E.; Smith, M.; Wang, X.; Wang, X.; Goldberg, D. J.; Wolgemuth, D. J.

    2001-01-01

    The p38 stress-activated protein kinase pathway is involved in regulation of phosphorylation of Hsp25, which in turn regulates actin filament dynamic in non-neuronal cells. We report that p38, Hsp25 and Akt signaling pathways were specifically activated in spinal motor neurons after sciatic nerve axotomy. The activation of the p38 kinase was required for induction of Hsp25 expression. Furthermore, Hsp25 formed a complex with Akt, a member of PI-3 kinase pathway that prevents neuronal cell death. Together, our observations implicate Hsp25 as a central player in a complex system of signaling that may both promote regeneration of nerve fibers and prevent neuronal cell death in the injured spinal cord.

  8. Icaritin requires Phosphatidylinositol 3 kinase (PI3K)/Akt signaling to counteract skeletal muscle atrophy following mechanical unloading

    OpenAIRE

    ZHANG, Zong-Kang; Li, Jie; Liu, Jin; Baosheng GUO; Leung, Albert; Zhang, Ge; Zhang, Bao-Ting

    2016-01-01

    Counteracting muscle atrophy induced by mechanical unloading/inactivity is of great clinical need and challenge. A therapeutic agent that could counteract muscle atrophy following mechanical unloading in safety is desired. This study showed that natural product Icaritin (ICT) could increase the phosphorylation level of Phosphatidylinositol 3 kinase (PI3K) at p110 catalytic subunit and promote PI3K/Akt signaling markers in C2C12 cells. This study further showed that the high dose ICT treatment...

  9. Sericin can reduce hippocampal neuronal apoptosis by activating the Akt signal transduction pathway in a rat model of diabetes mellitus☆

    OpenAIRE

    Chen, Zhihong; He, Yaqiang; Song, Chengjun; Dong, Zhijun; Su, Zhejun; Xue, Jingfeng

    2012-01-01

    In the present study, a rat model of type 2 diabetes mellitus was established by continuous peritoneal injection of streptozotocin. Following intragastric perfusion of sericin for 35 days, blood glucose levels significantly reduced, neuronal apoptosis in the hippocampal CA1 region decreased, hippocampal phosphorylated Akt and nuclear factor kappa B expression were enhanced, but Bcl-xL/Bcl-2 associated death promoter expression decreased. Results demonstrated that sericin can reduce hippocampa...

  10. Adiponectin Stimulates Angiogenesis by Promoting Cross-talk between AMP-activated Protein Kinase and Akt Signaling in Endothelial Cells*

    OpenAIRE

    Ouchi, Noriyuki; Kobayashi, Hideki; Kihara, Shinji; Kumada, Masahiro; Sato, Kaori; Inoue, Tatsuya; Funahashi, Tohru; Walsh, Kenneth

    2003-01-01

    Adiponectin is an adipocyte-specific adipocytokine with anti-atherogenic and anti-diabetic properties. Here, we investigated whether adiponectin regulates angiogenic processes in vitro and in vivo. Adiponectin stimulated the differentiation of human umbilical vein endothelium cells (HUVECs) into capillary-like structures in vitro and functioned as a chemoattractant in migration assays. Adiponectin promoted the phosphorylation of AMP-activated protein kinase (AMPK), protein kinase Akt/protein ...

  11. Phosphorylation Regulates Functions of ZEB1 Transcription Factor.

    Science.gov (United States)

    Llorens, M Candelaria; Lorenzatti, Guadalupe; Cavallo, Natalia L; Vaglienti, Maria V; Perrone, Ana P; Carenbauer, Anne L; Darling, Douglas S; Cabanillas, Ana M

    2016-10-01

    ZEB1 transcription factor is important in both development and disease, including many TGFβ-induced responses, and the epithelial-to-mesenchymal transition (EMT) by which many tumors undergo metastasis. ZEB1 is differentially phosphorylated in different cell types; however the role of phosphorylation in ZEB1 activity is unknown. Luciferase reporter studies and electrophoresis mobility shift assays (EMSA) show that a decrease in phosphorylation of ZEB1 increases both DNA-binding and transcriptional repression of ZEB1 target genes. Functional analysis of ZEB1 phosphorylation site mutants near the second zinc finger domain (termed ZD2) show that increased phosphorylation (due to either PMA plus ionomycin, or IGF-1) can inhibit transcriptional repression by either a ZEB1-ZD2 domain clone, or full-length ZEB1. This approach identifies phosphosites that have a substantial effect regulating the transcriptional and DNA-binding activity of ZEB1. Immunoprecipitation with anti-ZEB1 antibodies followed by western analysis with a phospho-Threonine-Proline-specific antibody indicates that the ERK consensus site at Thr-867 is phosphorylated in ZEB1. In addition to disrupting in vitro DNA-binding measured by EMSA, IGF-1-induced MEK/ERK phosphorylation is sufficient to disrupt nuclear localization of GFP-ZEB1 fusion clones. These data suggest that phosphorylation of ZEB1 integrates TGFβ signaling with other signaling pathways such as IGF-1. J. Cell. Physiol. 231: 2205-2217, 2016. © 2016 Wiley Periodicals, Inc. PMID:26868487

  12. L-3-n-butylphthalide protects against vascular dementia via activation of the Akt kinase pathway**

    Institute of Scientific and Technical Information of China (English)

    Yaping Huai; Yanhong Dong; Jing Xu; Nan Meng; Chunfeng Song; Wenbin Li; Peiyuan Lv

    2013-01-01

    As a neuroprotective drug for the treatment of ischemic stroke, 3-n-butylphthalide, a celery seed ex-tract, has been approved by the State Food and Drug Administration of China as a clinical therapeutic drug for ischemic stroke patients. L-3-n-butylphthalide possesses significant efficacy in the treatment of acute ischemic stroke. The activated Akt kinase pathway can prevent the death of nerve cel s and exhibit neuroprotective effects in the brain after stroke. This study provides the hypothesis that l-3-n-butylphthalide has a certain therapeutic effect on vascular dementia, and its mechanism depends on the activation of the Akt kinase pathway. A vascular dementia mouse model was established by cere-bral repetitive ischemia/reperfusion, and intragastrical y administered l-3-n-butylphthalide daily for 28 consecutive days after ischemia/reperfusion, or 7 consecutive days before ischemia/reperfusion. The Morris water maze test showed significant impairment of spatial learning and memory at 4 weeks after operation, but intragastric administration of l-3-n-butylphthalide, especial y pretreatment with l-3-n-butylphthalide, significantly reversed these changes. Thionine staining and western blot analylsis showed that preventive and therapeutic application of l-3-n-butylphthalide can reduce loss of pyrami-dal neurons in the hippocampal CA1 region and al eviate nerve damage in mice with vascular demen-tia. In addition, phosphorylated Akt expression in hippocampal tissue increased significantly after l-3-n-butylphthalide treatment. Experimental findings demonstrate that l-3-n-butylphthalide has preventive and therapeutic effects on vascular dementia, and its mechanism may be mediated by upregulation of phosphorylated Akt in the hippocampus.

  13. Interleukin-6 upregulates paraoxonase 1 gene expression via an AKT/NF-κB-dependent pathway

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chi-Chih [Department of Research, Taichung Veterans General Hospital, Taichung, Taiwan (China); Hsueh, Chi-Mei [Department of Life Sciences, National Chung Hsing University, Taichung, Taiwan (China); Chen, Chiu-Yuan [Graduate Institute of Natural Healing Sciences, Nanhua University, Chiayi, Taiwan (China); Chen, Tzu-Hsiu, E-mail: hsiu@mail.chna.edu.tw [Department of Health and Nutrition, Chia Nan University of Pharmacy and Science, Tainan, Taiwan (China); Hsu, Shih-Lan, E-mail: h2326@vghtc.gov.tw [Department of Research, Taichung Veterans General Hospital, Taichung, Taiwan (China); Department of Applied Chemistry, National Chi Nan University, Puli, Nantou, Taiwan (China)

    2013-07-19

    Highlights: •IL-6 could induce PON1 gene expression. •IL-6 increased NF-κB protein expression and NF-κB-p50 and -p65 subunits nuclear translocation. •IL-6-induced PON1 up-regulation was through an AKT/NF-κB pathway. -- Abstract: The aim of this study is to investigate the relationship between paraoxonase 1 (PON1) and atherosclerosis-related inflammation. In this study, human hepatoma HepG2 cell line was used as a hepatocyte model to examine the effects of the pro-inflammatory cytokines on PON1 expression. The results showed that IL-6, but not TNF-α and IL-1β, significantly increased both the function and protein level of PON1; data from real-time RT-PCR analysis revealed that the IL-6-induced PON1 expression occurred at the transcriptional level. Increase of IκB kinase activity and IκB phosphorylation, and reduction of IκB protein level were also observed in IL-6-treated HepG2 cells compared with untreated culture. This event was accompanied by increase of NF-κB-p50 and -p65 nuclear translocation. Moreover, treatment with IL-6 augmented the DNA binding activity of NF-κB. Furthermore, pharmacological inhibition of NF-κB activation by PDTC and BAY 11-7082, markedly suppressed the IL-6-mediated PON1 expression. In addition, IL-6 increased the levels of phosphorylated protein kinase B (PKB, AKT). An AKT inhibitor LY294002 effectively suppressed IKK/IκB/NF-κB signaling and PON1 gene expression induced by IL-6. Our findings demonstrate that IL-6 upregulates PON1 gene expression through an AKT/NF-κB signaling axis in human hepatocyte-derived HepG2 cell line.

  14. Insulin improves cardiac myocytes contractile function recovery in simulated ischemia-reperfusion: Key role of Akt

    Institute of Scientific and Technical Information of China (English)

    ZHANG Bo; ZHANG Haifeng; FAN Qian; MA Xinliang; GAO Feng

    2003-01-01

    The present study examined cardiac myocyte contractile and Ca2+ transient responses to insulin during simulated ischemia/reperfusion (I/R) and furtherinvestigated the role of protein kinase B (Akt) in the insulin- induced inotropic effect. Ventricular myocytes were enzymatically isolated from adult Sprague-Dawley rats and perfused with Tyrode solution while electrically field-stimulated. Simulated I/R was induced by perfusing the cells with chemical anoxic solution including sodium cyanide-sodium lactate for 15 min followed by reperfusion with normal oxygenated Tyrode solution with or without insulin. It is found that insulin only at concentration as high as 10 IU/L could increase cell shortening (16±5%, P < 0.05) in normal myocytes, whereas it concentration-dependently (0.01-10 IU/L) increased the contraction,the velocity of shortening/releng- theningand Ca2+ transient in I/R myocytes. In addition, insulin treatment (1 IU/L) increased Akt phosphorylation of I/R cardiomyocytes by 2.4-fold compared with that of the control (P < 0.01). Most importantly, pretreatment with LY 294002, a specific inhibitor of phosphatidylinositol 3′-kinase (PI3-kinase), significantly inhibited both Akt phosphorylation and the positive inotropic response to insulin in the I/R cardiomyocytes. These results suggest that insulin exerts direct positive inotropic effect by increasing Ca2+ transient of cardiomyocytes, which is enhanced in the pathological condition of I/R. Akt activation plays an important role in the insulin-induced improvement of myocyte contractile function following I/R.

  15. Combination of PKCε Activation and PTP1B Inhibition Effectively Suppresses Aβ-Induced GSK-3β Activation and Tau Phosphorylation.

    Science.gov (United States)

    Kanno, Takeshi; Tsuchiya, Ayako; Tanaka, Akito; Nishizaki, Tomoyuki

    2016-09-01

    Glycogen synthase kinase-3β (GSK-3β) is a key element to phosphorylate tau and form neurofibrillary tangles (NFTs) found in tauopathies including Alzheimer's disease (AD). A current topic for AD therapy is focused upon how to prevent tau phosphorylation. In the present study, PKCε activated Akt and inactivated GSK-3β by directly interacting with each protein. Inhibition of protein tyrosine phosphatase 1B (PTP1B), alternatively, caused an enhancement in the tyrosine phosphorylation of insulin receptor substrate 1 (IRS-1), allowing activation of Akt through a pathway along an IRS-1/phosphatidylinositol 3 kinase (PI3K)/3-phosphoinositide-dependent protein kinase-1 (PDK1)/Akt axis, to phosphorylate and inactivate GSK-3β. Combination of PKCε activation and PTP1B inhibition more sufficiently activated Akt and inactivated GSK-3β than each independent treatment, to suppress amyloid β (Aβ)-induced tau phosphorylation and ameliorate spatial learning and memory impairment in 5xFAD transgenic mice, an animal model of AD. This may represent an innovative strategy for AD therapy. PMID:26328540

  16. Angiotensin II-induced Akt activation through the epidermal growth factor receptor in vascular smooth muscle cells is mediated by phospholipid metabolites derived by activation of phospholipase D.

    Science.gov (United States)

    Li, Fang; Malik, Kafait U

    2005-03-01

    Angiotensin II (Ang II) activates cytosolic Ca(2+)-dependent phospholipase A(2) (cPLA(2)), phospholipase D (PLD), p38 mitogen-activated protein kinase (MAPK), epidermal growth factor receptor (EGFR) and Akt in vascular smooth muscle cells (VSMC). This study was conducted to investigate the relationship between Akt activation by Ang II and other signaling molecules in rat VSMC. Ang II-induced Akt phosphorylation was significantly reduced by the PLD inhibitor 1-butanol, but not by its inactive analog 2-butanol, and by brefeldin A, an inhibitor of the PLD cofactor ADP-ribosylation factor, and in cells infected with retrovirus containing PLD(2) siRNA or transfected with PLD(2) antisense but not control LacZ or sense oligonucleotide. Diacylglycerol kinase inhibitor II diminished Ang II-induced and diC8-phosphatidic acid (PA)-increased Akt phosphorylation, suggesting that PLD-dependent Akt activation is mediated by PA. Ang II-induced EGFR phosphorylation was inhibited by 1-butanol and PLD(2) siRNA and also by cPLA(2) siRNA. In addition, the inhibitor of arachidonic acid (AA) metabolism 5,8,11,14-eicosatetraynoic acid (ETYA) reduced both Ang II- and AA-induced EGFR transactivation. Furthermore, ETYA, cPLA(2) antisense, and cPLA(2) siRNA attenuated Ang II-elicited PLD activation. p38 MAPK inhibitor SB202190 [4-(4-flurophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole] reduced PLD activity and EGFR and Akt phosphorylation elicited by Ang II. Pyrrolidine-1, a cPLA(2) inhibitor, and cPLA(2) siRNA decreased p38 MAPK activity. These data indicate that Ang II-stimulated Akt activity is mediated by cPLA(2)-dependent, p38 MAPK regulated PLD(2) activation and EGFR transactivation. We propose the following scheme of the sequence of events leading to activation of Akt in VSMC by Ang II: Ang II-->cPLA(2)-->AA-->p38 MAPK-->PLD(2)-->PA-->EGFR-->Akt. PMID:15525798

  17. Angiotensin II-induced Akt activation through the epidermal growth factor receptor in vascular smooth muscle cells is mediated by phospholipid metabolites derived by activation of phospholipase D.

    Science.gov (United States)

    Li, Fang; Malik, Kafait U

    2005-03-01

    Angiotensin II (Ang II) activates cytosolic Ca(2+)-dependent phospholipase A(2) (cPLA(2)), phospholipase D (PLD), p38 mitogen-activated protein kinase (MAPK), epidermal growth factor receptor (EGFR) and Akt in vascular smooth muscle cells (VSMC). This study was conducted to investigate the relationship between Akt activation by Ang II and other signaling molecules in rat VSMC. Ang II-induced Akt phosphorylation was significantly reduced by the PLD inhibitor 1-butanol, but not by its inactive analog 2-butanol, and by brefeldin A, an inhibitor of the PLD cofactor ADP-ribosylation factor, and in cells infected with retrovirus containing PLD(2) siRNA or transfected with PLD(2) antisense but not control LacZ or sense oligonucleotide. Diacylglycerol kinase inhibitor II diminished Ang II-induced and diC8-phosphatidic acid (PA)-increased Akt phosphorylation, suggesting that PLD-dependent Akt activation is mediated by PA. Ang II-induced EGFR phosphorylation was inhibited by 1-butanol and PLD(2) siRNA and also by cPLA(2) siRNA. In addition, the inhibitor of arachidonic acid (AA) metabolism 5,8,11,14-eicosatetraynoic acid (ETYA) reduced both Ang II- and AA-induced EGFR transactivation. Furthermore, ETYA, cPLA(2) antisense, and cPLA(2) siRNA attenuated Ang II-elicited PLD activation. p38 MAPK inhibitor SB202190 [4-(4-flurophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)1H-imidazole] reduced PLD activity and EGFR and Akt phosphorylation elicited by Ang II. Pyrrolidine-1, a cPLA(2) inhibitor, and cPLA(2) siRNA decreased p38 MAPK activity. These data indicate that Ang II-stimulated Akt activity is mediated by cPLA(2)-dependent, p38 MAPK regulated PLD(2) activation and EGFR transactivation. We propose the following scheme of the sequence of events leading to activation of Akt in VSMC by Ang II: Ang II-->cPLA(2)-->AA-->p38 MAPK-->PLD(2)-->PA-->EGFR-->Akt.

  18. DNA–PKcs–SIN1 complexation mediates low-dose X-ray irradiation (LDI)-induced Akt activation and osteoblast differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Yong; Fang, Shi-ji [The Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou 215000 (China); Zhu, Li-juan [Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases and Institute of Neuroscience, Soochow University, Suzhou, Jiangsu 215021 (China); Zhu, Lun-qing, E-mail: xiaodongwangsz@163.com [The Center of Diagnosis and Treatment for Children’s Bone Diseases, The Children’s Hospital Affiliated to Soochow University, Suzhou, Jiangsu 215000 (China); Zhou, Xiao-zhong, E-mail: zhouxz@suda.edu.cn [The Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou 215000 (China)

    2014-10-24

    Highlights: • LDI increases ALP activity, promotes type I collagen (Col I)/Runx2 mRNA expression. • LDI induces DNA–PKcs activation, which is required for osteoblast differentiation. • Akt activation mediates LDI-induced ALP activity and Col I/Runx2 mRNA increase. • DNA–PKcs–SIN1 complexation mediates LDI-induced Akt Ser-473 phosphorylation. • DNA–PKcs–SIN1 complexation is important for osteoblast differentiation. - Abstract: Low-dose irradiation (LDI) induces osteoblast differentiation, however the underlying mechanisms are not fully understood. In this study, we explored the potential role of DNA-dependent protein kinase catalytic subunit (DNA–PKcs)–Akt signaling in LDI-induced osteoblast differentiation. We confirmed that LDI promoted mouse calvarial osteoblast differentiation, which was detected by increased alkaline phosphatase (ALP) activity as well as mRNA expression of type I collagen (Col I) and runt-related transcription factor 2 (Runx2). In mouse osteoblasts, LDI (1 Gy) induced phosphorylation of DNA–PKcs and Akt (mainly at Ser-473). The kinase inhibitors against DNA–PKcs (NU-7026 and NU-7441) or Akt (LY294002, perifosine and MK-2206), as well as partial depletion of DNA–PKcs or Akt1 by targeted-shRNA, dramatically inhibited LDI-induced Akt activation and mouse osteoblast differentiation. Further, siRNA-knockdown of SIN1, a key component of mTOR complex 2 (mTORC2), also inhibited LDI-induced Akt Ser-473 phosphorylation as well as ALP activity increase and Col I/Runx2 expression in mouse osteoblasts. Co-immunoprecipitation (Co-IP) assay results demonstrated that LDI-induced DNA–PKcs–SIN1 complexation, which was inhibited by NU-7441 or SIN1 siRNA-knockdown in mouse osteoblasts. In summary, our data suggest that DNA–PKcs–SIN1 complexation-mediated Akt activation (Ser-473 phosphorylation) is required for mouse osteoblast differentiation.

  19. PPAR-γ ligands repress TGFβ-induced myofibroblast differentiation by targeting the PI3K/Akt pathway: implications for therapy of fibrosis.

    Directory of Open Access Journals (Sweden)

    Ajit A Kulkarni

    Full Text Available Transforming growth factor beta (TGFβ induced differentiation of human lung fibroblasts to myofibroblasts is a key event in the pathogenesis of pulmonary fibrosis. Although the typical TGFβ signaling pathway involves the Smad family of transcription factors, we have previously reported that peroxisome proliferator-activated receptor-γ (PPAR-γ ligands inhibit TGFβ-mediated differentiation of human lung fibroblasts to myofibroblasts via a Smad-independent pathway. TGFβ also activates the phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt pathway leading to phosphorylation of Akt(S473. Here, we report that PPAR-γ ligands, 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO and 15-deoxy-(12,14-15d-prostaglandin J(2 (15d-PGJ(2, inhibit human myofibroblast differentiation of normal and idiopathic pulmonary fibrotic (IPF fibroblasts, by blocking Akt phosphorylation at Ser473 by a PPAR-γ-independent mechanism. The PI3K inhibitor LY294002 and a dominant-negative inactive kinase-domain mutant of Akt both inhibited TGFβ-stimulated myofibroblast differentiation, as determined by Western blotting for α-smooth muscle actin and calponin. Prostaglandin A(1 (PGA(1, a structural analogue of 15d-PGJ(2 with an electrophilic center, also reduced TGFβ-driven phosphorylation of Akt, while CAY10410, another analogue that lacks an electrophilic center, did not; implying that the activity of 15d-PGJ(2 and CDDO is dependent on their electrophilic properties. PPAR-γ ligands inhibited TGFβ-induced Akt phosphorylation via both post-translational and post-transcriptional mechanisms. This inhibition is independent of MAPK-p38 and PTEN but is dependent on TGFβ-induced phosphorylation of FAK, a kinase that acts upstream of Akt. Thus, PPAR-γ ligands inhibit TGFβ signaling by affecting two pro-survival pathways that culminate in myofibroblast differentiation. Further studies of PPAR-γ ligands and small electrophilic molecules may lead to a new generation of

  20. Proteome-wide survey of phosphorylation patterns affected by nuclear DNA polymorphisms in Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Engelsberger Wolfgang R

    2010-07-01

    Full Text Available Abstract Background Protein phosphorylation is an important post-translational modification influencing many aspects of dynamic cellular behavior. Site-specific phosphorylation of amino acid residues serine, threonine, and tyrosine can have profound effects on protein structure, activity, stability, and interaction with other biomolecules. Phosphorylation sites can be affected in diverse ways in members of any species, one such way is through single nucleotide polymorphisms (SNPs. The availability of large numbers of experimentally identified phosphorylation sites, and of natural variation datasets in Arabidopsis thaliana prompted us to analyze the effect of non-synonymous SNPs (nsSNPs onto phosphorylation sites. Results From the analyses of 7,178 experimentally identified phosphorylation sites we found that: (i Proteins with multiple phosphorylation sites occur more often than expected by chance. (ii Phosphorylation hotspots show a preference to be located outside conserved domains. (iii nsSNPs affected experimental phosphorylation sites as much as the corresponding non-phosphorylated amino acid residues. (iv Losses of experimental phosphorylation sites by nsSNPs were identified in 86 A. thaliana proteins, among them receptor proteins were overrepresented. These results were confirmed by similar analyses of predicted phosphorylation sites in A. thaliana. In addition, predicted threonine phosphorylation sites showed a significant enrichment of nsSNPs towards asparagines and a significant depletion of the synonymous substitution. Proteins in which predicted phosphorylation sites were affected by nsSNPs (loss and gain, were determined to be mainly receptor proteins, stress response proteins and proteins involved in nucleotide and protein binding. Proteins involved in metabolism, catalytic activity and biosynthesis were less affected. Conclusions We analyzed more than 7,100 experimentally identified phosphorylation sites in almost 4,300 protein

  1. PDGF stimulation of Mueller cell proliferation: Contributions of c-JNK and the PI3K/Akt pathway

    Energy Technology Data Exchange (ETDEWEB)

    Moon, Sang Woong [Department of Ophthalmology, Seoul Paik Hospital, Inje University College of Medicine, Busan (Korea, Republic of); Chung, Eun Jee [Department of Ophthalmology, National Health Insurance Corporation, Ilsan Hospital, Gyounggi-do (Korea, Republic of); Jung, Sun-Ah [Myunggok Eye Research Institute, Kim' s Eye Hospital, Konyang University College of Medicine, Seoul (Korea, Republic of); Lee, Joon H., E-mail: joonhlee@konyang.ac.kr [Myunggok Eye Research Institute, Kim' s Eye Hospital, Konyang University College of Medicine, Seoul (Korea, Republic of)

    2009-10-09

    Platelet-derived growth factor (PDGF) has a critical role in proliferative vitreoretinopathy (PVR) as a chemoattractant and mitogen for retinal pigment epithelial cells and retinal glial cells. Here, we investigated the potential effects of PDGF on the proliferation of Mueller cells and the intracellular signaling pathway mediating these changes. PDGF induced Mueller cell proliferation and increased phosphorylation of the PDGF receptor (PDGFR), as shown by an MTT assay and immunoprecipitation analyses. Both effects were blocked by JNJ, a PDGFR-selective tyrosine kinase inhibitor. PDGF also stimulated phosphorylation of c-JNK and Akt. PDGF-induced Mueller cell proliferation was significantly reduced by pre-treatment with SP600125 and LY294002, inhibitors of c-JNK and Akt phosphorylation, respectively. Our findings collectively indicate that PDGF-stimulated Mueller cell proliferation occurs via activation of the c-JNK and PI3K/Akt signaling pathways. These data provide useful information in establishing the role of Mueller cells in the development of proliferative vitreoretinopathy.

  2. Extracellular Ser/Thr/Tyr phosphorylated proteins of Pseudomonas aeruginosa PA14 strain.

    Science.gov (United States)

    Ouidir, Tassadit; Jarnier, Frédérique; Cosette, Pascal; Jouenne, Thierry; Hardouin, Julie

    2014-09-01

    Protein phosphorylation on serine, threonine, and tyrosine is known to be involved in a wide variety of cellular processes, signal transduction, and bacterial virulence. We characterized, for the first time, the extracellular phosphoproteins of the Pseudomonas aeruginosa PA14 strain. We identified 28 phosphoproteins (59 phosphosites) including enzymes, with various phosphorylation sites, known as potent secreted virulence factors in P. aeruginosa. The high phosphorylation level of these virulence factors might reflect a relationship between Ser/Thr/Tyr phosphorylation and virulence. PMID:24965220

  3. Phosphorylation of insulin receptor substrate 1 by glycogen synthase kinase 3 impairs insulin action

    OpenAIRE

    Eldar-Finkelman, Hagit; Krebs, Edwin G.

    1997-01-01

    The phosphorylation of insulin receptor substrate 1 (IRS-1) on tyrosine residues by the insulin receptor (IR) tyrosine kinase is involved in most of the biological responses of insulin. IRS-1 mediates insulin signaling by recruiting SH2 proteins through its multiple tyrosine phosphorylation sites. The phosphorylation of IRS-1 on serine/threonine residues also occurs in cells; however, the particular protein kinase(s) promoting this type of phosphorylation are unknown. Here we report that glyc...

  4. Curcumin Attenuated Bupivacaine-Induced Neurotoxicity in SH-SY5Y Cells Via Activation of the Akt Signaling Pathway.

    Science.gov (United States)

    Fan, You-Ling; Li, Heng-Chang; Zhao, Wei; Peng, Hui-Hua; Huang, Fang; Jiang, Wei-Hang; Xu, Shi-Yuan

    2016-09-01

    Bupivacaine is widely used for regional anesthesia, spinal anesthesia, and pain management. However, bupivacaine could cause neuronal injury. Curcumin, a low molecular weight polyphenol, has a variety of bioactivities and may exert neuroprotective effects against damage induced by some stimuli. In the present study, we tested whether curcumin could attenuate bupivacaine-induced neurotoxicity in SH-SY5Y cells. Cell injury was evaluated by examining cell viability, mitochondrial damage and apoptosis. We also investigated the levels of activation of the Akt signaling pathway and the effect of Akt inhibition by triciribine on cell injury following bupivacaine and curcumin treatment. Our findings showed that the bupivacaine treatment could induce neurotoxicity. Pretreatment of the SH-SY5Y cells with curcumin significantly attenuated bupivacaine-induced neurotoxicity. Interestingly, the curcumin treatment increased the levels of Akt phosphorylation. More significantly, the pharmacological inhibition of Akt abolished the cytoprotective effect of curcumin against bupivacaine-induced cell injury. Our data suggest that pretreating SH-SY5Y cells with curcumin provides a protective effect on bupivacaine-induced neuronal injury via activation of the Akt signaling pathway. PMID:27233246

  5. Juglanthraquinone C Induces Intracellular ROS Increase and Apoptosis by Activating the Akt/Foxo Signal Pathway in HCC Cells

    Directory of Open Access Journals (Sweden)

    Ya-Qin Hou

    2016-01-01

    Full Text Available Juglanthraquinone C (JC, a naturally occurring anthraquinone extracted from Juglans mandshurica, could induce apoptosis of cancer cells. This study aims to investigate the detailed cytotoxicity mechanism of JC in HepG2 and BEL-7402 cells. The Affymetrix HG-U133 Plus 2.0 arrays were first used to analyze the mRNA expression exposed to JC or DMSO in HepG2 cells. Consistent with the previous results, the data indicated that JC could induce apoptosis and hyperactivated Akt. The Western blot analysis further revealed that Akt, a well-known survival protein, was strongly activated in HepG2 and BEL-7402 cells. Furthermore, an obvious inhibitory effect on JC-induced apoptosis was observed when the Akt levels were decreased, while the overexpression of constitutively active mutant Akt greatly accelerated JC-induced apoptosis. The subsequent results suggested that JC treatment suppressed nuclear localization and increased phosphorylated levels of Foxo3a, and the overexpression of Foxo3a abrogated JC-induced apoptosis. Most importantly, the inactivation of Foxo3a induced by JC further led to an increase of intracellular ROS levels by suppressing ROS scavenging enzymes, and the antioxidant N-acetyl-L-cysteine and catalase successfully decreased JC-induced apoptosis. Collectively, this study demonstrated that JC induced the apoptosis of hepatocellular carcinoma (HCC cells by activating Akt/Foxo signaling pathway and increasing intracellular ROS levels.

  6. Juglanthraquinone C Induces Intracellular ROS Increase and Apoptosis by Activating the Akt/Foxo Signal Pathway in HCC Cells

    Science.gov (United States)

    2016-01-01

    Juglanthraquinone C (JC), a naturally occurring anthraquinone extracted from Juglans mandshurica, could induce apoptosis of cancer cells. This study aims to investigate the detailed cytotoxicity mechanism of JC in HepG2 and BEL-7402 cells. The Affymetrix HG-U133 Plus 2.0 arrays were first used to analyze the mRNA expression exposed to JC or DMSO in HepG2 cells. Consistent with the previous results, the data indicated that JC could induce apoptosis and hyperactivated Akt. The Western blot analysis further revealed that Akt, a well-known survival protein, was strongly activated in HepG2 and BEL-7402 cells. Furthermore, an obvious inhibitory effect on JC-induced apoptosis was observed when the Akt levels were decreased, while the overexpression of constitutively active mutant Akt greatly accelerated JC-induced apoptosis. The subsequent results suggested that JC treatment suppressed nuclear localization and increased phosphorylated levels of Foxo3a, and the overexpression of Foxo3a abrogated JC-induced apoptosis. Most importantly, the inactivation of Foxo3a induced by JC further led to an increase of intracellular ROS levels by suppressing ROS scavenging enzymes, and the antioxidant N-acetyl-L-cysteine and catalase successfully decreased JC-induced apoptosis. Collectively, this study demonstrated that JC induced the apoptosis of hepatocellular carcinoma (HCC) cells by activating Akt/Foxo signaling pathway and increasing intracellular ROS levels. PMID:26682007

  7. Filamin A Expression Negatively Regulates Sphingosine-1-Phosphate-Induced NF-κB Activation in Melanoma Cells by Inhibition of Akt Signaling

    Science.gov (United States)

    Campos, Ludmila S.; Rodriguez, Yamila I.; Leopoldino, Andreia M.; Hait, Nitai C.; Lopez Bergami, Pablo; Castro, Melina G.; Sanchez, Emilse S.; Maceyka, Michael

    2015-01-01

    Sphingosine-1-phosphate (S1P) is a bioactive lipid mediator that regulates many processes in inflammation and cancer. S1P is a ligand for five G-protein-coupled receptors, S1PR1 to -5, and also has important intracellular actions. Previously, we showed that intracellular S1P is involved in tumor necrosis factor alpha (TNF)-induced NF-κB activation in melanoma cell lines that express filamin A (FLNA). Here, we show that extracellular S1P activates NF-κB only in melanoma cells that lack FLNA. In these cells, S1P, but not TNF, promotes IκB kinase (IKK) and p65 phosphorylation, IκBα degradation, p65 nuclear translocation, and NF-κB reporter activity. NF-κB activation induced by S1P was mediated via S1PR1 and S1PR2. Exogenous S1P enhanced the phosphorylation of protein kinase Cδ (PKCδ), and its downregulation reduced S1P-induced the phosphorylation of IKK and p65. In addition, silencing of Bcl10 also inhibited S1P-induced IKK phosphorylation. Surprisingly, S1P reduced Akt activation in melanoma cells that express FLNA, whereas in the absence of FLNA, high phosphorylation levels of Akt were maintained, enabling S1P-mediated NF-κB signaling. In accord, inhibition of Akt suppressed S1P-mediated IKK and p65 phosphorylation and degradation of IκBα. Hence, these results support a negative role of FLNA in S1P-mediated NF-κB activation in melanoma cells through modulation of Akt. PMID:26552704

  8. Sequence- and structure-based prediction of eukaryotic proteinphosphorylation sites

    DEFF Research Database (Denmark)

    Blom, Nikolaj; Gammeltoft, Steen; Brunak, Søren

    1999-01-01

    Protein phosphorylation at serine, threonine or tyrosine residues affects a multitude of cellular signaling processes. Howis specificity in substrate recognition and phosphorylation by protein kinases achieved? Here, we present an artificialneural network method that predicts phosphorylation site...

  9. Protective Effect of Tempol on Acute Kidney Injury Through PI3K/Akt/Nrf2 Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Gensheng Zhang

    2016-02-01

    Full Text Available Background/Aims: Tempol is a protective antioxidant against ischemic injury in many animal models. The molecular mechanisms are not well understood. Nuclear factor erythroid 2-related factor (Nrf2 is a master transcription factor during oxidative stress, which is enhanced by activation of protein kinase C (PKC pathway. Another factor, tubular epithelial apoptosis, is mediated by activation of phosphoinositide 3-kinase (PI3K/protein kinase B (PKB, Akt signaling pathway during renal ischemic injury. We tested the hypothesis that tempol activates PKC or PI3K/Akt/Nrf2 pathways to transcribe many genes that coordinate endogenous antioxidant defense. Methods: The right renal pedicle was clamped for 45 minutes and the left kidney was removed to study renal ischemia/reperfusion (I/R injury in C57BL/6 mice. The response was assessed from serum parameters, renal morphology and renal expression of PKC, phosphorylated-PKC (p-PKC, Nrf2, heme oxygenase-1 (HO-1, Akt, phosphorylated-Akt (p-Akt, pro-caspase-3 and cleaved caspase-3 in groups of sham and I/R mice given vehicle, or tempol (50 or 100 mg/kg, intraperitoneal injection. Results: The serum malondialdehyde (MDA, marker of reactive oxygen species doubled and the BUN and creatinine increased 5- to 10-fold after I/R injury. Tempol (50 or 100 mg/kg prevented the increases in MDA but only tempol (50 mg/kg lessened the increases in BUN and creatinine and moderated the acute tubular necrosis. I/R did not change expression of PKC or p-PKC but reduced renal expression of Nrf2, p-Akt, HO-1 and pro-caspase-3 and increased cleaved caspase-3. Tempol (50 mg/kg prevented these changes produced by I/R whereas tempol (100 mg/kg had lesser or inconsistent effects. Conclusion: Tempol (50 mg/kg prevents lipid peroxidation and attenuates renal damage after I/R injury. The beneficial pathway apparently is not dependent on upregulation or phosphorylation of PKC, at lower tempol doses, does implicate upregulation of Akt with

  10. Heat Stress-Induced PI3K/mTORC2-Dependent AKT Signaling Is a Central Mediator of Hepatocellular Carcinoma Survival to Thermal Ablation Induced Heat Stress.

    Science.gov (United States)

    Thompson, Scott M; Callstrom, Matthew R; Jondal, Danielle E; Butters, Kim A; Knudsen, Bruce E; Anderson, Jill L; Lien, Karen R; Sutor, Shari L; Lee, Ju-Seog; Thorgeirsson, Snorri S; Grande, Joseph P; Roberts, Lewis R; Woodrum, David A

    2016-01-01

    Thermal ablative therapies are important treatment options in the multidisciplinary care of patients with hepatocellular carcinoma (HCC), but lesions larger than 2-3 cm are plagued with high local recurrence rates and overall survival of these patients remains poor. Currently no adjuvant therapies exist to prevent local HCC recurrence in patients undergoing thermal ablation. The molecular mechanisms mediating HCC resistance to thermal ablation induced heat stress and local recurrence remain unclear. Here we demonstrate that the HCC cells with a poor prognostic hepatic stem cell subtype (Subtype HS) are more resistant to heat stress than HCC cells with a better prognostic hepatocyte subtype (Subtype HC). Moreover, sublethal heat stress rapidly induces phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) dependent-protein kinase B (AKT) survival signaling in HCC cells in vitro and at the tumor ablation margin in vivo. Conversely, inhibition of PI3K/mTOR complex 2 (mTORC2)-dependent AKT phosphorylation or direct inhibition of AKT function both enhance HCC cell killing and decrease HCC cell survival to sublethal heat stress in both poor and better prognostic HCC subtypes while mTOR complex 1 (mTORC1)-inhibition has no impact. Finally, we showed that AKT isoforms 1, 2 and 3 are differentially upregulated in primary human HCCs and that overexpression of AKT correlates with worse tumor biology and pathologic features (AKT3) and prognosis (AKT1). Together these findings define a novel molecular mechanism whereby heat stress induces PI3K/mTORC2-dependent AKT survival signaling in HCC cells and provide a mechanistic rationale for adjuvant AKT inhibition in combination with thermal ablation as a strategy to enhance HCC cell killing and prevent local recurrence, particularly at the ablation margin. PMID:27611696

  11. The transplantation of Akt-overexpressing amniotic fluid-derived mesenchymal stem cells protects the heart against ischemia-reperfusion injury in rabbits

    Science.gov (United States)

    WANG, YAN; LI, YIGANG; SONG, LEI; LI, YANYAN; JIANG, SHAN; ZHANG, SONG

    2016-01-01

    Amniotic fluid-derived mesenchymal stem cells (AFMSCs) are an attractive cell source for applications in regenerative medicine, due to characteristics such as proliferative capacity and multipotency. In addition, Akt, a serine-threonine kinase, maintains stem cells by promoting viability and proliferation. Whether the transplantation of Akt-overexpressing AFMSCs protects the heart against ischemia-reperfusion (I/R) injury has yet to be elucidated. Accordingly, the Akt gene was overexpressed in AFMSCs using lentiviral transduction, and Akt-AFMSCs were transplanted into the ischemic myocardium of rabbits prior to reperfusion. Any protective effects resulting from this procedure were subsequently sought after three weeks later. A histological examination revealed that there was a decrease in intramyocardial inflammation and ultrastructural damage, and an increase in capillary density and in the levels of GATA binding protein 4, connexin 43 and cardiac troponin T in the Akt-AFMSC group compared with the control group. A significant decrease in cardiomyocyte apoptosis, accompanying an increase in phosphorylated Akt and B-cell lymphoma 2 (Bcl-2) and a decrease in caspase-3, was also observed. Furthermore, the left ventricular function was markedly augmented in the Akt-AFMSC group compared with the control group. These observations suggested that the protective effect of AFMSCs may be due to the delivery of secreted cytokines, promotion of neoangiogenesis, prevention of cardiomyocyte apoptosis, transdifferentiation into cardiomyocytes and promotion of the viability of AFMSCs, which are assisted by Akt gene modification. Taken together, the results of the present study have indicated that transplantation of Akt-AFMSCs is able to alleviate myocardial I/R injury and improve cardiac function. PMID:27151366

  12. Identification of extracellularly phosphorylated membrane proteins.

    Science.gov (United States)

    Burghoff, Sandra; Willberg, Wibke; Schrader, Jürgen

    2015-10-01

    Ecto-protein kinases phosphorylate extracellular membrane proteins and exhibit similarities to casein kinases and protein kinases A and C. However, the identification of their protein substrates still remains a challenge because a clear separation from intracellular phosphoproteins is difficult. Here, we describe a straightforward method for the identification of extracellularly phosphorylated membrane proteins in human umbilical vein endothelial cells (HUVECs) and K562 cells which used the protease bromelain to selectively remove ectoproteins from intact cells and combined this with the subsequent analysis using IMAC and LC-MS/MS. A "false-positive" strategy in which cells without protease treatment served as controls was applied. Using this approach we identified novel phosphorylation sites on five ectophosphoproteins (NOTCH1, otopetrin 1, regulator of G-protein signalling 13 (RGS13), protein tyrosine phosphatase receptor type D isoform 3 (PTPRD), usherin isoform B (USH2A)). Use of bromelain appears to be a reliable technique for the further identification of phosphorylated surface-exposed peptides when extracellular adenosine-5'-triphosphate is elevated during purinergic signalling. PMID:26152529

  13. Weight Loss Upregulates the Small GTPase DIRAS3 in Human White Adipose Progenitor Cells, Which Negatively Regulates Adipogenesis and Activates Autophagy via Akt-mTOR Inhibition.

    Science.gov (United States)

    Ejaz, Asim; Mitterberger, Maria C; Lu, Zhen; Mattesich, Monika; Zwierzina, Marit E; Hörl, Susanne; Kaiser, Andreas; Viertler, Hans-Peter; Rostek, Ursula; Meryk, Andreas; Khalid, Sana; Pierer, Gerhard; Bast, Robert C; Zwerschke, Werner

    2016-04-01

    Long-term weight-loss (WL) interventions reduce insulin serum levels, protect from obesity, and postpone age-associated diseases. The impact of long-term WL on adipose-derived stromal/progenitor cells (ASCs) is unknown. We identified DIRAS3 and IGF-1 as long-term WL target genes up-regulated in ASCs in subcutaneous white adipose tissue of formerly obese donors (WLDs). We show that DIRAS3 negatively regulates Akt, mTOR and ERK1/2 signaling in ASCs undergoing adipogenesis and acts as a negative regulator of this pathway and an activator of autophagy. Studying the IGF-1-DIRAS3 interaction in ASCs of WLDs, we demonstrate that IGF-1, although strongly up-regulated in these cells, hardly activates Akt, while ERK1/2 and S6K1 phosphorylation is activated by IGF-1. Overexpression of DIRAS3 in WLD ASCs completely inhibits Akt phosphorylation also in the presence of IGF-1. Phosphorylation of ERK1/2 and S6K1 is lesser reduced under these conditions. In conclusion, our key findings are that DIRAS3 down-regulates Akt-mTOR signaling in ASCs of WLDs. Moreover, DIRAS3 inhibits adipogenesis and activates autophagy in these cells. PMID:27211557

  14. Involvement of PI3K/AKT and MAPK Pathways for TNF-α Production in SiHa Cervical Mucosal Epithelial Cells Infected with Trichomonas vaginalis.

    Science.gov (United States)

    Yang, Jung-Bo; Quan, Juan-Hua; Kim, Ye-Eun; Rhee, Yun-Ee; Kang, Byung-Hyun; Choi, In-Wook; Cha, Guang-Ho; Yuk, Jae-Min; Lee, Young-Ha

    2015-08-01

    Trichomonas vaginalis; induces proinflammation in cervicovaginal mucosal epithelium. To investigate the signaling pathways in TNF-α production in cervical mucosal epithelium after T. vaginalis infection, the phosphorylation of PI3K/AKT and MAPK pathways were evaluated in T. vaginalis-infected SiHa cells in the presence and absence of specific inhibitors. T. vaginalis increased TNF-α production in SiHa cells, in a parasite burden-dependent and incubation time-dependent manner. In T. vaginalis-infected SiHa cells, AKT, ERK1/2, p38 MAPK, and JNK were phosphorylated from 1 hr after infection; however, the phosphorylation patterns were different from each other. After pretreatment with inhibitors of the PI3K/AKT and MAPK pathways, TNF-α production was significantly decreased compared to the control; however, TNF-α reduction patterns were different depending on the type of PI3K/MAPK inhibitors. TNF-α production was reduced in a dose-dependent manner by treatment with wortmannin and PD98059, whereas it was increased by SP600125. These data suggested that PI3K/AKT and MAPK signaling pathways are important in regulation of TNF-α production in cervical mucosal epithelial SiHa cells. However, activation patterns of each pathway were different from the types of PI3K/MAPK pathways.

  15. Silencing miR-21 Sensitizes Non-Small Cell Lung Cancer A549 Cells to Ionizing Radiation through Inhibition of PI3K/Akt

    Directory of Open Access Journals (Sweden)

    Yongfu Ma

    2014-01-01

    Full Text Available We investigated the role of microRNA-21 (miR-21 in radiotherapy resistance of non-small cell lung cancers (NSCLC and the underlying molecular mechanism. A549 cells were transfected with anti-miR-21 or the negative control oligonucleotides and real-time PCR was applied to detect miR-21 expression level. After ionizing radiation (IR, the survival fractions, proliferation, apoptosis, and expression of phosphorylated-Akt of A549 cells were determined by clonogenic survival analysis, MTT assay, flow cytometry, and Western blotting. Downregulation of miR-21 in radioresistant NSCLC A549 cells inhibited the colony-forming ability and proliferation of A549 cells after IR. Moreover, silencing miR-21 enhanced apoptosis of A549 cells induced by IR accompanied by decreased phosphorylated-Akt protein level. However, PI3K activator IGF-1 reversed suppression of phosphorylated-Akt protein level and promotion of apoptosis of A549 cells after IR caused by miR-21 knockdown. Silencing miR-21 in radioresistant NSCLC A549 cells sensitized them to IR by inhibiting cell proliferation and enhancing cell apoptosis through inhibition of PI3K/Akt signaling pathway. This might help in sensitization of NSCLC to radiotherapy.

  16. SchA-p85-FAK complex dictates isoform-specific activation of Akt2 and subsequent PCBP1-mediated post-transcriptional regulation of TGFβ-mediated epithelial to mesenchymal transition in human lung cancer cell line A549.

    Science.gov (United States)

    Xue, Xinying; Wang, Xin; Liu, Yuxia; Teng, Guigen; Wang, Yong; Zang, Xuefeng; Wang, Kaifei; Zhang, Jinghui; Xu, Yali; Wang, Jianxin; Pan, Lei

    2014-08-01

    A post-transcriptional pathway by which TGF-β modulates expression of specific proteins, Disabled-2 (Dab2) and Interleukin-like EMT Inducer (ILEI), inherent to epithelial to mesenchymal transition (EMT) in murine epithelial cells through Akt2-mediated phosphorylation of poly r(C) binding protein (PCBP1), has been previously elucidated. The aims of the current study were to determine if the same mechanism is operative in the non-small cell lung cancer (NSCLC) cell line, A549, and to delineate the underlying mechanism. Steady-state transcript and protein expression levels of Dab2 and ILEI were examined in A549 cells treated with TGF-β for up to 48 h. Induction of translational de-repression in this model was quantified by polysomal fractionation followed by qRT-PCR. The underlying mechanism of isoform-specific activation of Akt2 was elucidated through a combination of co-immunoprecipitation studies. TGF-β induced EMT in A549 cells concomitant with translational upregulation of Dab2 and ILEI proteins through isoform-specific activation of Akt2 followed by phosphorylation of PCBP1 at serine-43. Our experiments further elucidated that the adaptor protein SchA is phosphorylated at tyrosine residues following TGF-β treatment, which initiated a signaling cascade resulting in the sequential recruitment of p85 subunit of PI3K and focal adhesion kinase (FAK). The SchA-FAK-p85 complex subsequently selectively recruited and activated Akt2, not Akt1. Inhibition of the p85 subunit through phosphorylated 1257 peptide completely attenuated EMT in these cells. We have defined the underlying mechanism responsible for isoform-specific recruitment and activation of Akt2, not Akt1, during TGF-β-mediated EMT in A549 cells. Inhibition of the formation of this complex thus represents an important and novel therapeutic target in metastatic lung carcinoma. PMID:24819169

  17. In vivo phosphorylation of 2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP): CNP in brain myelin is phosphorylated by forskolin- and phorbol ester-sensitive protein kinases.

    Science.gov (United States)

    Agrawal, H C; Sprinkle, T J; Agrawal, D

    1994-06-01

    2',3'-cyclic nucleotide 3'-phosphohydrolase (CNP) was phosphorylated in vivo, in brain slices and in a cell free system. Phosphoamino acid analysis of immunoprecipitated CNP labeled in vivo and in brain slices revealed phosphorylation of phosphoserine (94%) and phosphothreonine (5%) residues. Phosphorylation of CNP increased by 3-fold after brain slices were incubated with forskolin. Similarly, incubation of isolated myelin with [gamma-32]ATP with cAMP (5 microM) and cAMP (5 microM)+catalytic unit of cAMP dependent protein kinase dramatically increased CNP2 phosphorylation by 4- and 6-fold, respectively. It is feasible that CNP2 was predominantly phosphorylated on serine and/or threonine residues of the amino terminal peptide of CNP2, and this phosphorylation was catalyzed by protein kinase A. Phosphorylation of CNP1 and CNP2 increased 2-fold by incubating brain slices with phorbol ester. Forskolin and phorbol ester increased the phosphorylation of single, but distinct, CNP peptides. We present the first biochemical evidence that CNP2, on a protein mass basis, is far more heavily phosphorylated than CNP1, suggesting there are more phosphorylation sites on CNP2 than CNP1 and that at least one site is located on the 20-amino acid terminus of CNP2 and that it is likely a PKA site. PMID:8065530

  18. Impaired insulin-induced site-specific phosphorylation of TBC1 domain family, member 4 (TBC1D4) in skeletal muscle of type 2 diabetes patients is restored by endurance exercise-training

    DEFF Research Database (Denmark)

    Vind, B. F.; Pehmøller, Christian; Treebak, Jonas Thue;

    2011-01-01

    AIMS/HYPOTHESIS: Insulin-mediated glucose disposal rates (R (d)) are reduced in type 2 diabetic patients, a process in which intrinsic signalling defects are thought to be involved. Phosphorylation of TBC1 domain family, member 4 (TBC1D4) is at present the most distal insulin receptor signalling ...

  19. Synthesis of Isomeric Phosphoubiquitin Chains Reveals that Phosphorylation Controls Deubiquitinase Activity and Specificity.

    Science.gov (United States)

    Huguenin-Dezot, Nicolas; De Cesare, Virginia; Peltier, Julien; Knebel, Axel; Kristaryianto, Yosua Adi; Rogerson, Daniel T; Kulathu, Yogesh; Trost, Matthias; Chin, Jason W

    2016-07-26

    Ubiquitin is post-translationally modified by phosphorylation at several sites, but the consequences of these modifications are largely unknown. Here, we synthesize multi-milligram quantities of ubiquitin phosphorylated at serine 20, serine 57, and serine 65 via genetic code expansion. We use these phosphoubiquitins for the enzymatic assembly of 20 isomeric phosphoubiquitin dimers, with different sites of isopeptide linkage and/or phosphorylation. We discover that phosphorylation of serine 20 on ubiquitin converts UBE3C from a dual-specificity E3 ligase into a ligase that primarily synthesizes K48 chains. We profile the activity of 31 deubiquitinases on the isomeric phosphoubiquitin dimers in 837 reactions, and we discover that phosphorylation at distinct sites in ubiquitin can activate or repress cleavage of a particular linkage by deubiquitinases and that phosphorylation at a single site in ubiquitin can control the specificity of deubiquitinases for distinct ubiquitin linkages. PMID:27425610

  20. Krüppel-like factor 14 increases insulin sensitivity through activation of PI3K/Akt signal pathway.

    Science.gov (United States)

    Yang, Min; Ren, Yan; Lin, Zhimin; Tang, Chenchen; Jia, Yanjun; Lai, Yerui; Zhou, Tingting; Wu, Shaobo; Liu, Hua; Yang, Gangyi; Li, Ling

    2015-11-01

    Genome-wide association studies (GWAS) have shown that Krüppel-like factor 14 (KLF14) is associated with type 2 diabetes mellitus (T2DM). However, no report has demonstrated a relationship between KLF14 and glucose metabolism. The aim of this study was to determine whether KLF14 is associated with glucose metabolism and insulin signaling in vitro. The mRNA and protein expressions of KLF14 were determined by Real-time PCR and Western blotting. Glucose uptake was assessed by 2-[(3)H]-deoxyglucose (2-DG) uptake. Western blotting was used to identify the activation of insulin signaling proteins. KLF14 mRNA and protein in fat and muscle were significantly decreased in HFD-fed mice, db/db mice and T2DM patients. Overexpression of KLF14 enhanced insulin-stimulated glucose uptake and the activation of Akt kinase in Hepa1-6 cells. The phosphorylation of insulin receptor (InsR), insulin receptor substrate-1(IRS-1), glycogen synthase kinase-3β (GSK-3β) and Akt also elevated significantly by up-regulation of KLF14. KLF14 overexpression in Hepa1-6 cells prevented the inhibition of glucose uptake and Akt phosphorylation induced by high glucose and/or high insulin, or T2DM serum. However, KLF14's ability to increase glucose uptake and Akt activation was significantly attenuated by LY294002, a PI3-kinase inhibitor. These data suggested that KLF14 could increase insulin sensitivity probably through the PI3K/Akt pathway. PMID:26226221

  1. Identification of Mitosis-Specific Phosphorylation in Mitotic Chromosome-Associated Proteins.

    Science.gov (United States)

    Ohta, Shinya; Kimura, Michiko; Takagi, Shunsuke; Toramoto, Iyo; Ishihama, Yasushi

    2016-09-01

    During mitosis, phosphorylation of chromosome-associated proteins is a key regulatory mechanism. Mass spectrometry has been successfully applied to determine the complete protein composition of mitotic chromosomes, but not to identify post-translational modifications. Here, we quantitatively compared the phosphoproteome of isolated mitotic chromosomes with that of chromosomes in nonsynchronized cells. We identified 4274 total phosphorylation sites and 350 mitosis-specific phosphorylation sites in mitotic chromosome-associated proteins. Significant mitosis-specific phosphorylation in centromere/kinetochore proteins was detected, although the chromosomal association of these proteins did not change throughout the cell cycle. This mitosis-specific phosphorylation might play a key role in regulation of mitosis. Further analysis revealed strong dependency of phosphorylation dynamics on kinase consensus patterns, thus linking the identified phosphorylation sites to known key mitotic kinases. Remarkably, chromosomal axial proteins such as non-SMC subunits of condensin, TopoIIα, and Kif4A, together with the chromosomal periphery protein Ki67 involved in the establishment of the mitotic chromosomal structure, demonstrated high phosphorylation during mitosis. These findings suggest a novel mechanism for regulation of chromosome restructuring in mitosis via protein phosphorylation. Our study generated a large quantitative database on protein phosphorylation in mitotic and nonmitotic chromosomes, thus providing insights into the dynamics of chromatin protein phosphorylation at mitosis onset.

  2. Research in anti oligodendrocytes apoptosis by activating PI3K/Akt signal pathway in preterm rat%激活 PI3K/Akt 信号通路抗少突胶质细胞凋亡的研究

    Institute of Scientific and Technical Information of China (English)

    帅春; 汪灏

    2014-01-01

    目的探讨在脑室周围白质软化的早产大鼠中,脑组织 PI3K/Akt 通路的磷酸化激活情况,以及神经生长因子是否有抗少突胶质细胞凋亡的作用。方法本实验研究在早产大鼠脑室周围白质软化后,脑组织中少突胶质细胞的凋亡情况。给予神经生长因子,比较脑组织中 Akt 磷酸化激活情况及相应少突胶质细胞凋亡改变。结果早产大鼠脑损伤后,脑组织中少突胶质细胞凋亡急剧增加,给予神经生长因子后,脑组织中 Akt 磷酸化激活明显增加,相应少突胶质细胞凋亡明显减少。结论神经生长因子对脑损伤的保护机制与其增强 PI3K/Akt 信号转导通路的激活有关,激活 PI3K/Akt 信号转导通路可防治脑损伤刺激后的少突胶质细胞的凋亡。%Objective To explore activating phosphorylation of PI3K/Akt pathway in brain tissue and whether nerve growth factor has the effect of anti oligodendrocytes apoptosis in preterm rat with periventricular leukomalacia. Methods We studied apoptotic oligodendrocytes in brain tissue of preterm rats with periventricular leukomalacia and compared the situation of Akt phosphorylation activation and oligodendrocytes apoptosis change accordingly after nerve growth factor administered. Re-sults Oligodendrocytes apoptosis increased sharply in brain tissue after premature rats suffering periventricular leukomalacia.Akt phosphorylation activation increased significantly in brain tissue and the corresponding oligodendrocytes apoptosis decreased significantly after nerve growth factor administerd. Conclusion The effects of nerve growth factor on brain injury protection mechanism were related with enhancing the activation of PI3K/Akt signal transduction pathway.The activation of PI3K/Akt sig-nal transduction pathway may prevent and treat apoptotic oligodendrocytes after brain injury.

  3. Protein Synthesis Initiation Factors: Phosphorylation and Regulation

    Energy Technology Data Exchange (ETDEWEB)

    Karen S. Browning

    2009-06-15

    The initiation of the synthesis of proteins is a fundamental process shared by all living organisms. Each organism has both shared and unique mechanisms for regulation of this vital process. Higher plants provide for a major amount of fixation of carbon from the environment and turn this carbon into food and fuel sources for our use. However, we have very little understanding of how plants regulate the synthesis of the proteins necessary for these metabolic processes. The research carried out during the grant period sought to address some of these unknowns in the regulation of protein synthesis initiation. Our first goal was to determine if phosphorylation plays a significant role in plant initiation of protein synthesis. The role of phosphorylation, although well documented in mammalian protein synthesis regulation, is not well studied in plants. We showed that several of the factors necessary for the initiation of protein synthesis were targets of plant casein kinase and showed differential phosphorylation by the plant specific isoforms of this kinase. In addition, we identified and confirmed the phosphorylation sites in five of the plant initiation factors. Further, we showed that phosphorylation of one of these factors, eIF5, affected the ability of the factor to participate in the initiation process. Our second goal was to develop a method to make initiation factor 3 (eIF3) using recombinant methods. To date, we successfully cloned and expressed 13/13 subunits of wheat eIF3 in E. coli using de novo gene construction methods. The final step in this process is to place the subunits into three different plasmid operons for co-expression. Successful completion of expression of eIF3 will be an invaluable tool to the plant translation community.

  4. Adenosine triphosphate-sensitive potassium channel opener protects PC12 cells against hypoxia-induced apoptosis through PI3K/Akt and Bcl-2 signaling pathways

    Institute of Scientific and Technical Information of China (English)

    Hong Zhang; Chunhong Jia; Danyang Zhao; Yang Lu; Runling Wang; Jia Li

    2010-01-01

    Although previous studies have shown the neuroprotective effects of the adenosine triphosphate (ATP)-sensitive potassium (KATP) channel opener against ischemic neuronal damage, little is known about the mechanisms involved. Phosphatidylinositol-3 kinase (PI3K)/v-akt murine thy-moma viral oncogene homolog (Akt) and Bcl-2 are thought to be important factors that mediate neuroprotection. The present study investigated the effects of KATP openers on hypoxia-induced PC12 cell apoptosis, as well as mRNA and protein expression of Akt and Bcl-2. Results demon-strated that pretreatment of PC12 cells with pinacidil, a KATP opener, resulted in decreased PC12 cell apoptosis following hypoxia, as detected by Annexin-V fluorescein isothiocyanate/ propidium iodide double staining flow cytometry. In addition, mRNA and protein expression of phosphorylated Akt (p-Akt) and Bcl-2 increased, as detected by immunofluorescence, Western blot analysis, and reverse-transcription polymerase chain reaction. The protective effect of this preconditioning was attenuated by glipizide, a selective KATP blocker. These results demonstrate for the first time that the protective mechanisms of KATP openers on PC12 cell apoptosis following hypoxia could result from activation of the PI3K/Akt signaling pathway, which further activates expression of the downstream Bcl-2 gene.

  5. Methylmercury, an environmental electrophile capable of activation and disruption of the Akt/CREB/Bcl-2 signal transduction pathway in SH-SY5Y cells

    Science.gov (United States)

    Unoki, Takamitsu; Abiko, Yumi; Toyama, Takashi; Uehara, Takashi; Tsuboi, Koji; Nishida, Motohiro; Kaji, Toshiyuki; Kumagai, Yoshito

    2016-01-01

    Methylmercury (MeHg) modifies cellular proteins via their thiol groups in a process referred to as “S-mercuration”, potentially resulting in modulation of the cellular signal transduction pathway. We examined whether low-dose MeHg could affect Akt signaling involved in cell survival. Exposure of human neuroblastoma SH-SY5Y cells of up to 2 μM MeHg phosphorylated Akt and its downstream signal molecule CREB, presumably due to inactivation of PTEN through S-mercuration. As a result, the anti-apoptotic protein Bcl-2 was up-regulated by MeHg. The activation of Akt/CREB/Bcl-2 signaling mediated by MeHg was, at least in part, linked to cellular defence because either pretreatment with wortmannin to block PI3K/Akt signaling or knockdown of Bcl-2 enhanced MeHg-mediated cytotoxicity. In contrast, increasing concentrations of MeHg disrupted Akt/CREB/Bcl-2 signaling. This phenomenon was attributed to S-mercuration of CREB through Cys286 rather than Akt. These results suggest that although MeHg is an apoptosis-inducing toxicant, this environmental electrophile is able to activate the cell survival signal transduction pathway at lower concentrations prior to apoptotic cell death. PMID:27357941

  6. EGF‑stimulated AKT activation is mediated by EGFR recycling via an early endocytic pathway in a gefitinib‑resistant human lung cancer cell line.

    Science.gov (United States)

    Nishimura, Yukio; Takiguchi, Soichi; Ito, Shigeru; Itoh, Kazuyuki

    2015-04-01

    The receptor tyrosine kinase epidermal growth factor receptor (EGFR) and its ligand epidermal growth factor (EGF) are known to play important roles in malignant tumor cells, and the EGFR signaling pathway is one of the most important targets in various tumors, including non-small cell lung cancer (NSCLC). We reported recently that an aberration in certain steps of EGF-stimulated phosphorylated epidermal growth factor receptor (pEGFR) endocytic trafficking from the early endosomes to the late endosomes occurs in the gefitinib-resistant NSCLC cells, in which large amounts of sorting nexin 1 (SNX1) are colocalized with EGFR in the aggregated early endosomes where the internalized pEGFR is also accumulated of these cells. To further investigate the role of SNX1 in EGF‑stimulated pEGFR endocytosis, followed by downstream signaling leading to the activation of phosphatidylinositol 3-kinase (PI3K)--the serine/threonine kinase AKT pathway, we examined the effect of depletion of SNX1 knock-down expression by siRNA and an inhibition of targeting membrane recycling using monensin. Using immunofluorescence, we observed an efficient endocytic transport of pEGFR from early endosomes to late endosomes/lysosomes after EGF-stimulation in the cells transfected with siRNA‑SNX1, whereas the delayed endocytic delivery of pEGFR was evident in the siRNA-control-transfected cells. Furthermore, a large amount of endocytosed pEGFR was accumulated in the presence of monensin in the early endosomes of the SNX1 knock-down cells. In western blot analysis, EGF stimulation of both control and cells transfected with siRNA-SNX1 resulted in rapid phosphorylation of EGFR and enhanced AKT phosphorylation. Monensin-dependent inhibition of AKT phosphorylation was stronger in SNX1 knock-down cells than in controls. In contrast, however, monensin had no effect on AKT phosphorylation triggered by activation of the MET receptor tyrosine kinase. Collectively, we suggest that EGF-stimulated recycling of

  7. Properties of phosphorylated thymidylate synthase

    DEFF Research Database (Denmark)

    Frączyk, Tomasz; Ruman, Tomasz; Wilk, Piotr;

    2015-01-01

    , Trichinella spiralis and Caenorhabditis elegans TSs, expressed in Escherichia coli, the phosphorylated, compared to non-phosphorylated recombinant enzyme forms, showed a decrease in Vmax(app), bound their cognate mRNA (only rat enzyme studied), and repressed translation of their own and several heterologous m...

  8. Andrographolide Inhibits Nuclear Factor-κB Activation through JNK-Akt-p65 Signaling Cascade in Tumor Necrosis Factor-α-Stimulated Vascular Smooth Muscle Cells

    Directory of Open Access Journals (Sweden)

    Yu-Ying Chen

    2014-01-01

    Full Text Available Critical vascular inflammation leads to vascular dysfunction and cardiovascular diseases, including abdominal aortic aneurysms, hypertension, and atherosclerosis. Andrographolide is the most active and critical constituent isolated from the leaves of Andrographis paniculata, a herbal medicine widely used for treating anti-inflammation in Asia. In this study, we investigated the mechanisms of the inhibitory effects of andrographolide in vascular smooth muscle cells (VSMCs exposed to a proinflammatory stimulus, tumor necrosis factor-α (TNF-α. Treating TNF-α-stimulated VSMCs with andrographolide suppressed the expression of inducible nitric oxide synthase in a concentration-dependent manner. A reduction in TNF-α-induced c-Jun N-terminal kinase (JNK, Akt, and p65 phosphorylation was observed in andrographolide-treated VSMCs. However, andrographolide affected neither IκBα degradation nor p38 mitogen-activated protein kinase or extracellular signal-regulated kinase 1/2 phosphorylation under these conditions. Both treatment with LY294002, a phosphatidylinositol 3-kinase/Akt inhibitor, and treatment with SP600125, a JNK inhibitor, markedly reversed the andrographolide-mediated inhibition of p65 phosphorylation. In addition, LY294002 and SP600125 both diminished Akt phosphorylation, whereas LY294002 had no effects on JNK phosphorylation. These results collectively suggest that therapeutic interventions using andrographolide can benefit the treatment of vascular inflammatory diseases, and andrographolide-mediated inhibition of NF-κB activity in TNF-α-stimulated VSMCs occurs through the JNK-Akt-p65 signaling cascade, an IκBα-independent mechanism.

  9. COMP-angiopoietin 1 increases proliferation, differentiation, and migration of stem-like cells through Tie-2-mediated activation of p38 MAPK and PI3K/Akt signal transduction pathways

    International Nuclear Information System (INIS)

    Highlights: • COMP-Ang1 induces Tie-2 activation in BMMSCs, but not in primary osteoblasts. • Tie-2 knockdown inhibits COMP-Ang1-stimulated proliferation and osteoblastogenesis. • Tie-2 knockdown prevents COMP-Ang1-induced activation of PI3K/Akt and p38 MAPK. • COMP-Ang1 induces migration of cells via activation of PI3K/Akt and CXCR4 pathways. • COMP-Ang1 stimulates in vivo migration of PDLSCs into a calvarial defect site of rats. - Abstract: Recombinant COMP-Ang1, a chimera of angiopoietin-1 (Ang1) and a short coiled-coil domain of cartilage oligomeric matrix protein (COMP), is under consideration as a therapeutic agent capable of inducing the homing of cells with increased angiogenesis. However, the potentials of COMP-Ang1 to stimulate migration of mesenchymal stem cells (MSCs) and the associated mechanisms are not completely understood. We examined the potential of COMP-Ang1 on bone marrow (BM)-MSCs, human periodontal ligament stem cells (PDLSCs), and calvarial osteoblasts. COMP-Ang1 augmented Tie-2 induction at protein and mRNA levels and increased proliferation and expression of runt-related transcription factor 2 (Runx2), osterix, and CXCR4 in BMMSCs, but not in osteoblasts. The COMP-Ang1-mediated increases were inhibited by Tie-2 knockdown and by treating inhibitors of phosphoinositide 3-kinase (PI3K), LY294002, or p38 mitogen-activated protein kinase (MAPK), SB203580. Phosphorylation of p38 MAPK and Akt was prevented by siRNA-mediated silencing of Tie-2. COMP-Ang1 also induced in vitro migration of BMMSCs and PDLSCs. The induced migration was suppressed by Tie-2 knockdown and by CXCR4-specific peptide antagonist or LY294002, but not by SB203580. Furthermore, COMP-Ang1 stimulated the migration of PDLSCs into calvarial defect site of rats. Collectively, our results demonstrate that COMP-Ang1-stimulated proliferation, differentiation, and migration of progenitor cells may involve the Tie-2-mediated activation of p38 MAPK and PI3K/Akt pathways

  10. COMP-angiopoietin 1 increases proliferation, differentiation, and migration of stem-like cells through Tie-2-mediated activation of p38 MAPK and PI3K/Akt signal transduction pathways

    Energy Technology Data Exchange (ETDEWEB)

    Kook, Sung-Ho [Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences and School of Dentistry, Chonbuk National University, Jeonju (Korea, Republic of); Lim, Shin-Saeng [School of Dentistry and Dental Research Institute, Seoul National University, Seoul (Korea, Republic of); Cho, Eui-Sic; Lee, Young-Hoon; Han, Seong-Kyu; Lee, Kyung-Yeol [Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences and School of Dentistry, Chonbuk National University, Jeonju (Korea, Republic of); Kwon, Jungkee [College of Veterinary Medicine, Chonbuk National University, Jeonju (Korea, Republic of); Hwang, Jae-Won; Bae, Cheol-Hyeon [Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences and School of Dentistry, Chonbuk National University, Jeonju (Korea, Republic of); Seo, Young-Kwon [Research Institute of Biotechnology, Dongguk University, Seoul (Korea, Republic of); Lee, Jeong-Chae, E-mail: leejc88@jbnu.ac.kr [Cluster for Craniofacial Development and Regeneration Research, Institute of Oral Biosciences and School of Dentistry, Chonbuk National University, Jeonju (Korea, Republic of)

    2014-12-12

    Highlights: • COMP-Ang1 induces Tie-2 activation in BMMSCs, but not in primary osteoblasts. • Tie-2 knockdown inhibits COMP-Ang1-stimulated proliferation and osteoblastogenesis. • Tie-2 knockdown prevents COMP-Ang1-induced activation of PI3K/Akt and p38 MAPK. • COMP-Ang1 induces migration of cells via activation of PI3K/Akt and CXCR4 pathways. • COMP-Ang1 stimulates in vivo migration of PDLSCs into a calvarial defect site of rats. - Abstract: Recombinant COMP-Ang1, a chimera of angiopoietin-1 (Ang1) and a short coiled-coil domain of cartilage oligomeric matrix protein (COMP), is under consideration as a therapeutic agent capable of inducing the homing of cells with increased angiogenesis. However, the potentials of COMP-Ang1 to stimulate migration of mesenchymal stem cells (MSCs) and the associated mechanisms are not completely understood. We examined the potential of COMP-Ang1 on bone marrow (BM)-MSCs, human periodontal ligament stem cells (PDLSCs), and calvarial osteoblasts. COMP-Ang1 augmented Tie-2 induction at protein and mRNA levels and increased proliferation and expression of runt-related transcription factor 2 (Runx2), osterix, and CXCR4 in BMMSCs, but not in osteoblasts. The COMP-Ang1-mediated increases were inhibited by Tie-2 knockdown and by treating inhibitors of phosphoinositide 3-kinase (PI3K), LY294002, or p38 mitogen-activated protein kinase (MAPK), SB203580. Phosphorylation of p38 MAPK and Akt was prevented by siRNA-mediated silencing of Tie-2. COMP-Ang1 also induced in vitro migration of BMMSCs and PDLSCs. The induced migration was suppressed by Tie-2 knockdown and by CXCR4-specific peptide antagonist or LY294002, but not by SB203580. Furthermore, COMP-Ang1 stimulated the migration of PDLSCs into calvarial defect site of rats. Collectively, our results demonstrate that COMP-Ang1-stimulated proliferation, differentiation, and migration of progenitor cells may involve the Tie-2-mediated activation of p38 MAPK and PI3K/Akt pathways.

  11. Dioscin inhibits osteoclast differentiation and bone resorption though down-regulating the Akt signaling cascades

    International Nuclear Information System (INIS)

    Highlights: •A natural-derived compound, dioscin, suppresses osteoclast formation and bone resorption. •Dioscin inhibits osteolytic bone loss in vivo. •Dioscin impairs the Akt signaling cascades pathways during osteoclastogenesis. •Dioscin have therapeutic value in treating osteoclast-related diseases. -- Abstract: Bone resorption is the unique function of osteoclasts (OCs) and is critical for both bone homeostasis and pathologic bone diseases including osteoporosis, rheumatoid arthritis and tumor bone metastasis. Thus, searching for natural compounds that may suppress osteoclast formation and/or function is promising for the treatment of osteoclast-related diseases. In this study, we for the first time demonstrated that dioscin suppressed RANKL-mediated osteoclast differentiation and bone resorption in vitro in a dose-dependent manner. The suppressive effect of dioscin is supported by the reduced expression of osteoclast-specific markers. Further molecular analysis revealed that dioscin abrogated AKT phosphorylation, which subsequently impaired RANKL-induced nuclear factor-kappaB (NF-κB) signaling pathway and inhibited NFATc1 transcriptional activity. Moreover, in vivo studies further verified the bone protection activity of dioscin in osteolytic animal model. Together our data demonstrate that dioscin suppressed RANKL-induced osteoclast formation and function through Akt signaling cascades. Therefore, dioscin is a potential natural agent for the treatment of osteoclast-related diseases

  12. Dormancy of cancer cells with suppression of AKT activity contributes to survival in chronic hypoxia.

    Directory of Open Access Journals (Sweden)

    Hiroko Endo

    Full Text Available A hypoxic microenvironment in tumors has been recognized as a cause of malignancy or resistance to various cancer therapies. In contrast to recent progress in understanding the acute response of cancer cells to hypoxia, the characteristics of tumor cells in chronic hypoxia remain elusive. We have identified a pancreatic cancer cell line, AsPC-1, that is exceptionally able to survive for weeks under 1% oxygen conditions while most tested cancer cell lines die after only some days under these conditions. In chronic hypoxia, AsPC-1 cells entered a state of dormancy characterized by no proliferation, no death, and metabolic suppression. They reversibly switched to active status after being placed again in optimal culture conditions. ATP turnover, an indicator of energy demand, was markedly decreased and accompanied by reduced AKT phosphorylation. Forced activation of AKT resulted in increased ATP turnover and massive cell death in vitro and a decreased number of dormant cells in vivo. In contrast to most cancer cell lines, primary-cultured colorectal cancer cells easily entered the dormant status with AKT suppression under hypoxia combined with growth factor-depleted conditions. Primary colorectal cancer cells in dormancy were resistant to chemotherapy. Thus, the ability to survive in a deteriorated microenvironment by entering into dormancy under chronic hypoxia might be a common property among cancer cells. Targeting the regulatory mechanism inducing this dormant status could provide a new strategy for treating cancer.

  13. Dioscin inhibits osteoclast differentiation and bone resorption though down-regulating the Akt signaling cascades

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Xinhua; Zhai, Zanjing; Liu, Xuqiang; Li, Haowei [Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai (China); Ouyang, Zhengxiao [Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai (China); Department of Orthopaedics, Hunan Provincial Tumor Hospital and Tumor Hospital of Xiangya School of Medicine, Central South University, Changsha (China); Wu, Chuanlong [Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai (China); Liu, Guangwang [Department of Orthopaedic Surgery, The Central Hospital of Xuzhou, Affiliated Hospital of Medical Collage of Southeast University, Xuzhou (China); Fan, Qiming; Tang, Tingting [Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai (China); Qin, An, E-mail: dr.qinan@gmail.com [Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai (China); Dai, Kerong, E-mail: krdai@163.com [Shanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedics, Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai (China)

    2014-01-10

    Highlights: •A natural-derived compound, dioscin, suppresses osteoclast formation and bone resorption. •Dioscin inhibits osteolytic bone loss in vivo. •Dioscin impairs the Akt signaling cascades pathways during osteoclastogenesis. •Dioscin have therapeutic value in treating osteoclast-related diseases. -- Abstract: Bone resorption is the unique function of osteoclasts (OCs) and is critical for both bone homeostasis and pathologic bone diseases including osteoporosis, rheumatoid arthritis and tumor bone metastasis. Thus, searching for natural compounds that may suppress osteoclast formation and/or function is promising for the treatment of osteoclast-related diseases. In this study, we for the first time demonstrated that dioscin suppressed RANKL-mediated osteoclast differentiation and bone resorption in vitro in a dose-dependent manner. The suppressive effect of dioscin is supported by the reduced expression of osteoclast-specific markers. Further molecular analysis revealed that dioscin abrogated AKT phosphorylation, which subsequently impaired RANKL-induced nuclear factor-kappaB (NF-κB) signaling pathway and inhibited NFATc1 transcriptional activity. Moreover, in vivo studies further verified the b