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Dugan MP, Maiya R, Fleischer C, Bajo M, Snyder AE, Koduri A, Srinivasan S, Roberto M, Messing RO. Brain-specific serine/threonine-protein kinase 1 is a substrate of protein kinase C epsilon involved in sex-specific ethanol and anxiety phenotypes. Addict Biol 2024; 29:e13388. [PMID: 38497285 PMCID: PMC10950061 DOI: 10.1111/adb.13388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Revised: 02/08/2024] [Accepted: 02/13/2024] [Indexed: 03/19/2024]
Abstract
Protein kinase C epsilon (PKCε) regulates behavioural responses to ethanol and plays a role in anxiety-like behaviour, but knowledge is limited on downstream substrates of PKCε that contribute to these behaviours. We recently identified brain-specific serine/threonine-protein kinase 1 (BRSK1) as a substrate of PKCε. Here, we test the hypothesis that BRSK1 mediates responses to ethanol and anxiety-like behaviours that are also PKCε dependent. We used in vitro kinase assays to further validate BRSK1 as a substrate of PKCε and used Brsk1-/- mice to assess the role of BRSK1 in ethanol- and anxiety-related behaviours and in physiological responses to ethanol. We found that BRSK1 is phosphorylated by PKCε at a residue identified in a chemical genetic screen of PKCε substrates in mouse brain. Like Prkce-/- mice, male and female Brsk1-/- mice were more sensitive than wild-type to the acute sedative-hypnotic effect of alcohol. Unlike Prkce-/- mice, Brsk1-/- mice responded like wild-type to ataxic doses of ethanol. Although in Prkce-/- mice ethanol consumption and reward are reduced in both sexes, they were reduced only in female Brsk1-/- mice. Ex vivo slice electrophysiology revealed that ethanol-induced facilitation of GABA release in the central amygdala was absent in male Brsk1-/- mice similar to findings in male Prkce-/- mice. Collectively, these results indicate that BRSK1 is a target of PKCε that mediates some PKCε-dependent responses to ethanol in a sex-specific manner and plays a role distinct from PKCε in anxiety-like behaviour.
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Affiliation(s)
- Michael P. Dugan
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
| | - Rajani Maiya
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
- Department of PhysiologyLouisiana State University Health Sciences CenterNew OrleansLouisianaUSA
| | - Caleb Fleischer
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
| | - Michal Bajo
- Department of Molecular MedicineThe Scripps Research InstituteLa JollaCaliforniaUSA
| | - Angela E. Snyder
- Department of Molecular MedicineThe Scripps Research InstituteLa JollaCaliforniaUSA
| | - Ashwin Koduri
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
| | - Sathvik Srinivasan
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
| | - Marisa Roberto
- Department of Molecular MedicineThe Scripps Research InstituteLa JollaCaliforniaUSA
| | - Robert O. Messing
- Waggoner Center for Alcohol and Addiction ResearchDepartment of NeuroscienceThe University of Texas at AustinAustinTexasUSA
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Dugan MP, Ferguson LB, Hertz NT, Chalkley RJ, Burlingame AL, Shokat KM, Parker PJ, Messing RO. Chemical Genetic Identification of PKC Epsilon Substrates in Mouse Brain. Mol Cell Proteomics 2023; 22:100522. [PMID: 36863607 PMCID: PMC10105488 DOI: 10.1016/j.mcpro.2023.100522] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 01/25/2023] [Accepted: 02/27/2023] [Indexed: 03/04/2023] Open
Abstract
PKC epsilon (PKCε) plays important roles in behavioral responses to alcohol and in anxiety-like behavior in rodents, making it a potential drug target for reducing alcohol consumption and anxiety. Identifying signals downstream of PKCε could reveal additional targets and strategies for interfering with PKCε signaling. We used a chemical genetic screen combined with mass spectrometry to identify direct substrates of PKCε in mouse brain and validated findings for 39 of them using peptide arrays and in vitro kinase assays. Prioritizing substrates with several public databases such as LINCS-L1000, STRING, GeneFriends, and GeneMAINA predicted interactions between these putative substrates and PKCε and identified substrates associated with alcohol-related behaviors, actions of benzodiazepines, and chronic stress. The 39 substrates could be broadly classified in three functional categories: cytoskeletal regulation, morphogenesis, and synaptic function. These results provide a list of brain PKCε substrates, many of which are novel, for future investigation to determine the role of PKCε signaling in alcohol responses, anxiety, responses to stress, and other related behaviors.
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Affiliation(s)
- Michael P Dugan
- Department of Neuroscience, The University of Texas at Austin, Austin, Texas, USA
| | - Laura B Ferguson
- Department of Neuroscience, The University of Texas at Austin, Austin, Texas, USA
| | - Nicholas T Hertz
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute at the University of California San Francisco, San Francisco, California, USA; Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, USA
| | - Robert J Chalkley
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, USA
| | - Alma L Burlingame
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, USA
| | - Kevan M Shokat
- Department of Cellular and Molecular Pharmacology and Howard Hughes Medical Institute at the University of California San Francisco, San Francisco, California, USA
| | - Peter J Parker
- The Francis Crick Institute, London, United Kingdom; School of Cancer and Pharmaceutical Sciences, King's College London, London, United Kingdom
| | - Robert O Messing
- Department of Neuroscience, The University of Texas at Austin, Austin, Texas, USA.
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3
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Min X, Wang S, Zhang X, Sun N, Kim KM. PKCβII activation requires nuclear trafficking for phosphorylation and Mdm2-mediated ubiquitination. Life Sci Alliance 2023; 6:e202201748. [PMID: 36717249 PMCID: PMC9887771 DOI: 10.26508/lsa.202201748] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 01/11/2023] [Accepted: 01/11/2023] [Indexed: 01/31/2023] Open
Abstract
PKCβII, a conventional PKC family member, plays critical roles in the regulation of a variety of cellular functions. Here, we employed loss-of-function approaches and mutants of PKCβII with altered phosphorylation and protein interaction behaviors to identify the cellular mechanisms underlying the activation of PKCβII. Our results show that 3-phosphoinositide-dependent protein kinase-1 (PDK1)-mediated constitutive phosphorylation of PKCβII at the activation loop (T500) is required for phorbol ester-induced nuclear entry and subsequent Mdm2-mediated ubiquitination of PKCβII, whereas ubiquitination of PKCβII is required for the PDK1-mediated inducible phosphorylation of PKCβII at T500 in the nucleus. After moving out of the nucleus, PKCβII interacts with actin, undergoes inducible mTORC2-mediated phosphorylation at the turn motif (T641), interacts with clathrin, and then translocates to the plasma membrane. This overall cascade of cellular events intertwined with the phosphorylation at critical residues and Mdm2-mediated ubiquitination in the nucleus and along with interactions with actin and clathrin plays roles that encompass the core processes of PKC activation.
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Affiliation(s)
- Xiao Min
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Shujie Wang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Xiaohan Zhang
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Ningning Sun
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
| | - Kyeong-Man Kim
- Department of Pharmacology, College of Pharmacy, Chonnam National University, Gwang-Ju, Republic of Korea
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4
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Meng Z, Li Z, Xie M, Yu H, Jiang L, Yao X. TM9SF4 is an F-actin disassembly factor that promotes tumor progression and metastasis. Nat Commun 2022; 13:5728. [PMID: 36175399 PMCID: PMC9522921 DOI: 10.1038/s41467-022-33276-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/09/2022] [Indexed: 11/29/2022] Open
Abstract
F-actin dynamics is crucial for many fundamental properties of cancer cells, from cell-substrate adhesion to migration, invasion and metastasis. However, the regulatory mechanisms of actin dynamics are still incompletely understood. In this study, we demonstrate the function of a protein named TM9SF4 in regulating actin dynamics and controlling cancer cell motility and metastasis. We show that an N-terminal fragment (NTF) cleaved from TM9SF4 can directly bind to F-actin to induce actin oxidation at Cys374, consequently enhancing cofilin-mediated F-actin disassembly. Knockdown of TM9SF4 reduces cell migration and invasion in ovarian cancer cells A2780, SKOV3 and several high grade serous ovarian cancer lines (HGSOCs). In vivo, knockdown of TM9SF4 completely abolishes the tumor growth and metastasis in athymic nude mice. These data provide mechanistic insights into TM9SF4-mediated regulation of actin dynamics in ovarian cancer cells. F-actin dynamics influence cancer cell motility. Here the authors show that TM9SF4 facilitates the cofilin-induced disassembly of F-actin to promote cancer cell migration and metastasis.
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Affiliation(s)
- Zhaoyue Meng
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.,Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Zhichao Li
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China.,Key Laboratory of Medical Reprogramming Technology, Shenzhen Second People's Hospital, The First Affiliated Hospital of Shenzhen University, Shenzhen, China
| | - Mingxu Xie
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Hongyan Yu
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China
| | - Liwen Jiang
- Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China.
| | - Xiaoqiang Yao
- School of Biomedical Sciences and Li Ka Shing Institute of Health Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, China. .,Centre for Cell & Developmental Biology and State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Hong Kong, China.
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Watson L, Soliman TN, Davis K, Kelly J, Lockwood N, Yang X, Lynham S, Scott JD, Crossland V, McDonald NQ, Mann DJ, Armstrong A, Eggert U, Parker PJ. Co-ordinated control of the Aurora B abscission checkpoint by PKCε complex assembly, midbody recruitment and retention. Biochem J 2021; 478:2247-2263. [PMID: 34143863 PMCID: PMC8238520 DOI: 10.1042/bcj20210283] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 05/24/2021] [Accepted: 05/26/2021] [Indexed: 11/17/2022]
Abstract
A requirement for PKCε in exiting from the Aurora B dependent abscission checkpoint is associated with events at the midbody, however, the recruitment, retention and action of PKCε in this compartment are poorly understood. Here, the prerequisite for 14-3-3 complex assembly in this pathway is directly linked to the phosphorylation of Aurora B S227 at the midbody. However, while essential for PKCε control of Aurora B, 14-3-3 association is shown to be unnecessary for the activity-dependent enrichment of PKCε at the midbody. This localisation is demonstrated to be an autonomous property of the inactive PKCε D532N mutant, consistent with activity-dependent dissociation. The C1A and C1B domains are necessary for this localisation, while the C2 domain and inter-C1 domain (IC1D) are necessary for retention at the midbody. Furthermore, it is shown that while the IC1D mutant retains 14-3-3 complex proficiency, it does not support Aurora B phosphorylation, nor rescues division failure observed with knockdown of endogenous PKCε. It is concluded that the concerted action of multiple independent events facilitates PKCε phosphorylation of Aurora B at the midbody to control exit from the abscission checkpoint.
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Affiliation(s)
- Lisa Watson
- Protein Phosphorylation Laboratory, Francis Crick Institute, Midland Road, London NE1 1AT, U.K
| | - Tanya N. Soliman
- Protein Phosphorylation Laboratory, Francis Crick Institute, Midland Road, London NE1 1AT, U.K
| | - Khalil Davis
- Protein Phosphorylation Laboratory, Francis Crick Institute, Midland Road, London NE1 1AT, U.K
| | - Joanna Kelly
- Protein Phosphorylation Laboratory, Francis Crick Institute, Midland Road, London NE1 1AT, U.K
| | - Nicola Lockwood
- Protein Phosphorylation Laboratory, Francis Crick Institute, Midland Road, London NE1 1AT, U.K
| | - Xiaoping Yang
- Proteomics Facility, King's College London, Denmark Hill Campus, London SE5 9NU, U.K
| | - Steven Lynham
- Proteomics Facility, King's College London, Denmark Hill Campus, London SE5 9NU, U.K
| | - John D. Scott
- Department of Pharmacology, University of Washington, Seattle, WA 98195, U.S.A
| | - Victoria Crossland
- Protein Phosphorylation Laboratory, Francis Crick Institute, Midland Road, London NE1 1AT, U.K
| | - Neil Q. McDonald
- Signalling and Structural Biology Laboratory, Francis Crick Institute, Midland Road, London NE1 1AT, U.K
- Institute of Structural and Molecular Biology, Department of Biological Sciences, Birkbeck College, London WC1E 7HX, U.K
| | - David J. Mann
- Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K
| | - Alan Armstrong
- Department of Chemistry, Imperial College London White City Campus, London W12 0BZ, U.K
| | - Ulrike Eggert
- Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London SE1 1UL, U.K
- Department of Chemistry, King's College London, London SE1 1UL, U.K
| | - Peter J. Parker
- Protein Phosphorylation Laboratory, Francis Crick Institute, Midland Road, London NE1 1AT, U.K
- CRUK KHP Centre, School of Cancer and Pharmaceutical Sciences, King's College London, London SE1 1UL, U.K
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6
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Distinctive requirement of PKCε in the control of Rho GTPases in epithelial and mesenchymally transformed lung cancer cells. Oncogene 2019; 38:5396-5412. [PMID: 30923343 PMCID: PMC6609469 DOI: 10.1038/s41388-019-0796-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 03/07/2019] [Accepted: 03/08/2019] [Indexed: 12/17/2022]
Abstract
Diacylglycerol (DAG)/phorbol ester-regulated protein kinase C (PKC) isozymes have been widely linked to tumor promotion and the development of a metastatic phenotype. PKCε, an oncogenic member of the PKC family, is abnormally overexpressed in lung cancer and other cancer types. This kinase plays significant roles in proliferation, survival and migration; however its role in epithelial-to-mesenchymal transition (EMT) has been scarcely studied. Silencing experiments in non-small lung cancer (NSCLC) cells revealed that PKCε or other DAG-regulated PKCs (PKCα and PKCδ) were dispensable for the acquisition of a mesenchymal phenotype induced by transforming growth factor beta (TGF-β). Unexpectedly, we found a nearly complete down-regulation of PKCε expression in TGF-β-mesenchymally transformed NSCLC cells. PMA and AJH-836 (a DAG-mimetic that preferentially activates PKCε) promote ruffle formation in NSCLC cells via Rac1, however they fail to induce these morphological changes in TGF-β-mesenchymally transformed cells despite their elevated Rac1 activity. Several Rac Guanine nucleotide Exchange-Factors (Rac-GEFs) were also up-regulated in TGF-β-treated NSCLC cells, including Trio and Tiam2, which were required for cell motility. Lastly, we found that silencing or inhibiting PKCε enhances RhoA activity and stress fiber formation, a phenotype also observed in TGF-β-transformed cells. Our studies established a distinctive involvement of PKCε in epithelial and mesenchymal NSCLC cells, and identified a complex interplay between PKCε and small GTPases that contributes to regulation of NSCLC cell morphology and motile activity.
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7
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Liu Z, Khalil RA. Evolving mechanisms of vascular smooth muscle contraction highlight key targets in vascular disease. Biochem Pharmacol 2018; 153:91-122. [PMID: 29452094 PMCID: PMC5959760 DOI: 10.1016/j.bcp.2018.02.012] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 02/12/2018] [Indexed: 12/11/2022]
Abstract
Vascular smooth muscle (VSM) plays an important role in the regulation of vascular function. Identifying the mechanisms of VSM contraction has been a major research goal in order to determine the causes of vascular dysfunction and exaggerated vasoconstriction in vascular disease. Major discoveries over several decades have helped to better understand the mechanisms of VSM contraction. Ca2+ has been established as a major regulator of VSM contraction, and its sources, cytosolic levels, homeostatic mechanisms and subcellular distribution have been defined. Biochemical studies have also suggested that stimulation of Gq protein-coupled membrane receptors activates phospholipase C and promotes the hydrolysis of membrane phospholipids into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 stimulates initial Ca2+ release from the sarcoplasmic reticulum, and is buttressed by Ca2+ influx through voltage-dependent, receptor-operated, transient receptor potential and store-operated channels. In order to prevent large increases in cytosolic Ca2+ concentration ([Ca2+]c), Ca2+ removal mechanisms promote Ca2+ extrusion via the plasmalemmal Ca2+ pump and Na+/Ca2+ exchanger, and Ca2+ uptake by the sarcoplasmic reticulum and mitochondria, and the coordinated activities of these Ca2+ handling mechanisms help to create subplasmalemmal Ca2+ domains. Threshold increases in [Ca2+]c form a Ca2+-calmodulin complex, which activates myosin light chain (MLC) kinase, and causes MLC phosphorylation, actin-myosin interaction, and VSM contraction. Dissociations in the relationships between [Ca2+]c, MLC phosphorylation, and force have suggested additional Ca2+ sensitization mechanisms. DAG activates protein kinase C (PKC) isoforms, which directly or indirectly via mitogen-activated protein kinase phosphorylate the actin-binding proteins calponin and caldesmon and thereby enhance the myofilaments force sensitivity to Ca2+. PKC-mediated phosphorylation of PKC-potentiated phosphatase inhibitor protein-17 (CPI-17), and RhoA-mediated activation of Rho-kinase (ROCK) inhibit MLC phosphatase and in turn increase MLC phosphorylation and VSM contraction. Abnormalities in the Ca2+ handling mechanisms and PKC and ROCK activity have been associated with vascular dysfunction in multiple vascular disorders. Modulators of [Ca2+]c, PKC and ROCK activity could be useful in mitigating the increased vasoconstriction associated with vascular disease.
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Affiliation(s)
- Zhongwei Liu
- Vascular Surgery Research Laboratories, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA
| | - Raouf A Khalil
- Vascular Surgery Research Laboratories, Division of Vascular and Endovascular Surgery, Brigham and Women's Hospital, and Harvard Medical School, Boston, MA 02115, USA.
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8
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Isakov N. Protein kinase C (PKC) isoforms in cancer, tumor promotion and tumor suppression. Semin Cancer Biol 2017; 48:36-52. [PMID: 28571764 DOI: 10.1016/j.semcancer.2017.04.012] [Citation(s) in RCA: 168] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 03/22/2017] [Accepted: 04/25/2017] [Indexed: 12/27/2022]
Abstract
The AGC family of serine/threonine kinases (PKA, PKG, PKC) includes more than 60 members that are critical regulators of numerous cellular functions, including cell cycle and differentiation, morphogenesis, and cell survival and death. Mutation and/or dysregulation of AGC kinases can lead to malignant cell transformation and contribute to the pathogenesis of many human diseases. Members of one subgroup of AGC kinases, the protein kinase C (PKC), have been singled out as critical players in carcinogenesis, following their identification as the intracellular receptors of phorbol esters, which exhibit tumor-promoting activities. This observation attracted the attention of researchers worldwide and led to intense investigations on the role of PKC in cell transformation and the potential use of PKC as therapeutic drug targets in cancer diseases. Studies demonstrated that many cancers had altered expression and/or mutation of specific PKC genes. However, the causal relationships between the changes in PKC gene expression and/or mutation and the direct cause of cancer remain elusive. Independent studies in normal cells demonstrated that activation of PKC is essential for the induction of cell activation and proliferation, differentiation, motility, and survival. Based on these observations and the general assumption that PKC isoforms play a positive role in cell transformation and/or cancer progression, many PKC inhibitors have entered clinical trials but the numerous attempts to target PKC in cancer has so far yielded only very limited success. More recent studies demonstrated that PKC function as tumor suppressors, and suggested that future clinical efforts should focus on restoring, rather than inhibiting, PKC activity. The present manuscript provides some historical perspectives on the tumor promoting function of PKC, reviewing some of the observations linking PKC to cancer progression, and discusses the role of PKC in the pathogenesis of cancer diseases and its potential usage as a therapeutic target.
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Affiliation(s)
- Noah Isakov
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences and the Cancer Research Center, Ben Gurion University of the Negev, P.O.B. 653, Beer Sheva 84105, Israel.
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9
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Duong M, Yu X, Teng B, Schroder P, Haller H, Eschenburg S, Schiffer M. Protein kinase C ϵ stabilizes β-catenin and regulates its subcellular localization in podocytes. J Biol Chem 2017; 292:12100-12110. [PMID: 28539358 DOI: 10.1074/jbc.m117.775700] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2017] [Revised: 05/23/2017] [Indexed: 01/18/2023] Open
Abstract
Kidney disease has been linked to dysregulated signaling via PKC in kidney cells such as podocytes. PKCα is a conventional isoform of PKC and a well-known binding partner of β-catenin, which promotes its degradation. β-Catenin is the main effector of the canonical Wnt pathway and is critical in cell adhesion. However, whether other PKC isoforms interact with β-catenin has not been studied systematically. Here we demonstrate that PKCϵ-deficient mice, which develop proteinuria and glomerulosclerosis, display lower β-catenin expression compared with PKC wild-type mice, consistent with an altered phenotype of podocytes in culture. Remarkably, β-catenin showed a reversed subcellular localization pattern: Although β-catenin exhibited a perinuclear pattern in undifferentiated wild-type cells, it predominantly localized to the nucleus in PKCϵ knockout cells. Phorbol 12-myristate 13-acetate stimulation of both cell types revealed that PKCϵ positively regulates β-catenin expression and stabilization in a glycogen synthase kinase 3β-independent manner. Further, β-catenin overexpression in PKCϵ-deficient podocytes could restore the wild-type phenotype, similar to rescue with a PKCϵ construct. This effect was mediated by up-regulation of P-cadherin and the β-catenin downstream target fascin1. Zebrafish studies indicated three PKCϵ-specific phosphorylation sites in β-catenin that are required for full β-catenin function. Co-immunoprecipitation and pulldown assays confirmed PKCϵ and β-catenin as binding partners and revealed that ablation of the three PKCϵ phosphorylation sites weakens their interaction. In summary, we identified a novel pathway for regulation of β-catenin levels and define PKCϵ as an important β-catenin interaction partner and signaling opponent of other PKC isoforms in podocytes.
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Affiliation(s)
- Michelle Duong
- Department of Hypertension and Nephrology, Hanover Medical School, 30625 Hanover, Germany
| | - Xuejiao Yu
- Department of Hypertension and Nephrology, Hanover Medical School, 30625 Hanover, Germany
| | - Beina Teng
- Department of Hypertension and Nephrology, Hanover Medical School, 30625 Hanover, Germany
| | - Patricia Schroder
- Mount Desert Island Biological Laboratory, Salisbury Cove, Maine 04672
| | - Hermann Haller
- Department of Hypertension and Nephrology, Hanover Medical School, 30625 Hanover, Germany
| | - Susanne Eschenburg
- Institute for Biophysical Chemistry, Hanover Medical School, 30625 Hanover, Germany
| | - Mario Schiffer
- Department of Hypertension and Nephrology, Hanover Medical School, 30625 Hanover, Germany.
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Molecular dynamics simulations reveal ligand-controlled positioning of a peripheral protein complex in membranes. Nat Commun 2017; 8:6. [PMID: 28232750 PMCID: PMC5431895 DOI: 10.1038/s41467-016-0015-8] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 11/17/2016] [Indexed: 01/13/2023] Open
Abstract
Bryostatin is in clinical trials for Alzheimer’s disease, cancer, and HIV/AIDS eradication. It binds to protein kinase C competitively with diacylglycerol, the endogenous protein kinase C regulator, and plant-derived phorbol esters, but each ligand induces different activities. Determination of the structural origin for these differing activities by X-ray analysis has not succeeded due to difficulties in co-crystallizing protein kinase C with relevant ligands. More importantly, static, crystal-lattice bound complexes do not address the influence of the membrane on the structure and dynamics of membrane-associated proteins. To address this general problem, we performed long-timescale (400–500 µs aggregate) all-atom molecular dynamics simulations of protein kinase C–ligand–membrane complexes and observed that different protein kinase C activators differentially position the complex in the membrane due in part to their differing interactions with waters at the membrane inner leaf. These new findings enable new strategies for the design of simpler, more effective protein kinase C analogs and could also prove relevant to other peripheral protein complexes. Natural supplies of bryostatin, a compound in clinical trials for Alzheimer’s disease, cancer, and HIV, are scarce. Here, the authors perform molecular dynamics simulations to understand how bryostatin interacts with membrane-bound protein kinase C, offering insights for the design of bryostatin analogs.
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11
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Ringvold HC, Khalil RA. Protein Kinase C as Regulator of Vascular Smooth Muscle Function and Potential Target in Vascular Disorders. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 78:203-301. [PMID: 28212798 PMCID: PMC5319769 DOI: 10.1016/bs.apha.2016.06.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Vascular smooth muscle (VSM) plays an important role in maintaining vascular tone. In addition to Ca2+-dependent myosin light chain (MLC) phosphorylation, protein kinase C (PKC) is a major regulator of VSM function. PKC is a family of conventional Ca2+-dependent α, β, and γ, novel Ca2+-independent δ, ɛ, θ, and η, and atypical ξ, and ι/λ isoforms. Inactive PKC is mainly cytosolic, and upon activation it undergoes phosphorylation, maturation, and translocation to the surface membrane, the nucleus, endoplasmic reticulum, and other cell organelles; a process facilitated by scaffold proteins such as RACKs. Activated PKC phosphorylates different substrates including ion channels, pumps, and nuclear proteins. PKC also phosphorylates CPI-17 leading to inhibition of MLC phosphatase, increased MLC phosphorylation, and enhanced VSM contraction. PKC could also initiate a cascade of protein kinases leading to phosphorylation of the actin-binding proteins calponin and caldesmon, increased actin-myosin interaction, and VSM contraction. Increased PKC activity has been associated with vascular disorders including ischemia-reperfusion injury, coronary artery disease, hypertension, and diabetic vasculopathy. PKC inhibitors could test the role of PKC in different systems and could reduce PKC hyperactivity in vascular disorders. First-generation PKC inhibitors such as staurosporine and chelerythrine are not very specific. Isoform-specific PKC inhibitors such as ruboxistaurin have been tested in clinical trials. Target delivery of PKC pseudosubstrate inhibitory peptides and PKC siRNA may be useful in localized vascular disease. Further studies of PKC and its role in VSM should help design isoform-specific PKC modulators that are experimentally potent and clinically safe to target PKC in vascular disease.
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Affiliation(s)
- H C Ringvold
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States
| | - R A Khalil
- Brigham and Women's Hospital, Harvard Medical School, Boston, MA, United States.
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12
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Sen A, Hongpaisan J, Wang D, Nelson TJ, Alkon DL. Protein Kinase Cϵ (PKCϵ) Promotes Synaptogenesis through Membrane Accumulation of the Postsynaptic Density Protein PSD-95. J Biol Chem 2016; 291:16462-76. [PMID: 27330081 DOI: 10.1074/jbc.m116.730440] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Indexed: 11/06/2022] Open
Abstract
Protein kinase Cϵ (PKCϵ) promotes synaptic maturation and synaptogenesis via activation of synaptic growth factors such as BDNF, NGF, and IGF. However, many of the detailed mechanisms by which PKCϵ induces synaptogenesis are not fully understood. Accumulation of PSD-95 to the postsynaptic density (PSD) is known to lead to synaptic maturation and strengthening of excitatory synapses. Here we investigated the relationship between PKCϵ and PSD-95. We show that the PKCϵ activators dicyclopropanated linoleic acid methyl ester and bryostatin 1 induce phosphorylation of PSD-95 at the serine 295 residue, increase the levels of PSD-95, and enhance its membrane localization. Elimination of the serine 295 residue in PSD-95 abolished PKCϵ-induced membrane accumulation. Knockdown of either PKCϵ or JNK1 prevented PKCϵ activator-mediated membrane accumulation of PSD-95. PKCϵ directly phosphorylated PSD-95 and JNK1 in vitro Inhibiting PKCϵ, JNK, or calcium/calmodulin-dependent kinase II activity prevented the effects of PKCϵ activators on PSD-95 phosphorylation. Increase in membrane accumulation of PKCϵ and phosphorylated PSD-95 (p-PSD-95(S295)) coincided with an increased number of synapses and increased amplitudes of excitatory post-synaptic potentials (EPSPs) in adult rat hippocampal slices. Knockdown of PKCϵ also reduced the synthesis of PSD-95 and the presynaptic protein synaptophysin by 30 and 44%, respectively. Prolonged activation of PKCϵ increased synapse number by 2-fold, increased presynaptic vesicle density, and greatly increased PSD-95 clustering. These results indicate that PKCϵ promotes synaptogenesis by activating PSD-95 phosphorylation directly through JNK1 and calcium/calmodulin-dependent kinase II and also by inducing expression of PSD-95 and synaptophysin.
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Affiliation(s)
- Abhik Sen
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
| | - Jarin Hongpaisan
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
| | - Desheng Wang
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
| | - Thomas J Nelson
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
| | - Daniel L Alkon
- From the Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia 26505
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13
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Scruggs SB, Wang D, Ping P. PRKCE gene encoding protein kinase C-epsilon-Dual roles at sarcomeres and mitochondria in cardiomyocytes. Gene 2016; 590:90-6. [PMID: 27312950 DOI: 10.1016/j.gene.2016.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Revised: 05/23/2016] [Accepted: 06/05/2016] [Indexed: 12/26/2022]
Abstract
Protein kinase C-epsilon (PKCε) is an isoform of a large PKC family of enzymes that has a variety of functions in different cell types. Here we discuss two major roles of PKCε in cardiac muscle cells; specifically, its role in regulating cardiac muscle contraction via targeting the sarcomeric proteins, as well as modulating cardiac cell energy production and metabolism by targeting cardiac mitochondria. The importance of PKCε action is described within the context of intracellular localization, as substrate selectivity and specificity is achieved through spatiotemporal targeting of PKCε. Accordingly, the role of PKCε in regulating myocardial function in physiological and pathological states has been documented in both cardioprotection and cardiac hypertrophy.
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Affiliation(s)
- Sarah B Scruggs
- Departments of Physiology, Medicine (Cardiology) and Bioinformatics, NIH BD2K Center of Excellence for Biomedical Computing, University of California Los Angeles, Los Angeles, CA 90095, USA.
| | - Ding Wang
- Departments of Physiology, Medicine (Cardiology) and Bioinformatics, NIH BD2K Center of Excellence for Biomedical Computing, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Peipei Ping
- Departments of Physiology, Medicine (Cardiology) and Bioinformatics, NIH BD2K Center of Excellence for Biomedical Computing, University of California Los Angeles, Los Angeles, CA 90095, USA.
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14
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Sun MK, Hongpaisan J, Alkon DL. Rescue of Synaptic Phenotypes and Spatial Memory in Young Fragile X Mice. ACTA ACUST UNITED AC 2016; 357:300-10. [PMID: 26941170 DOI: 10.1124/jpet.115.231100] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/02/2016] [Indexed: 01/01/2023]
Abstract
Fragile X syndrome (FXS) is characterized by synaptic immaturity, cognitive impairment, and behavioral changes. The disorder is caused by transcriptional shutdown in neurons of thefragile X mental retardation 1gene product, fragile X mental retardation protein. Fragile X mental retardation protein is a repressor of dendritic mRNA translation and its silencing leads to dysregulation of synaptically driven protein synthesis and impairments of intellect, cognition, and behavior, and FXS is a disorder that currently has no effective therapeutics. Here, young fragile X mice were treated with chronic bryostatin-1, a relatively selective protein kinase Cεactivator, which induces synaptogenesis and synaptic maturation/repair. Chronic treatment with bryostatin-1 rescues young fragile X mice from the disorder phenotypes, including normalization of most FXS abnormalities in 1) hippocampal brain-derived neurotrophic factor expression, 2) postsynaptic density-95 levels, 3) transformation of immature dendritic spines to mature synapses, 4) densities of the presynaptic and postsynaptic membranes, and 5) spatial learning and memory. The therapeutic effects were achieved without downregulation of metabotropic glutamate receptor (mGluR) 5 in the hippocampus and are more dramatic than those of a late-onset treatment in adult fragile X mice. mGluR5 expression was in fact lower in fragile X mice and its expression was restored with the bryostatin-1 treatment. Our results show that synaptic and cognitive function of young FXS mice can be normalized through pharmacological treatment without downregulation of mGluR5 and that bryostatin-1-like agents may represent a novel class of drugs to treat fragile X mental retardation at a young age and in adults.
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Affiliation(s)
- Miao-Kun Sun
- Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia
| | - Jarin Hongpaisan
- Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia
| | - Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia
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15
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Mukherjee A, Roy S, Saha B, Mukherjee D. Spatio-Temporal Regulation of PKC Isoforms Imparts Signaling Specificity. Front Immunol 2016; 7:45. [PMID: 26925059 PMCID: PMC4756072 DOI: 10.3389/fimmu.2016.00045] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 01/29/2016] [Indexed: 12/18/2022] Open
Affiliation(s)
| | - Sayoni Roy
- National Centre for Cell Science , Pune , India
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16
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Activation of Brain L-glutamate Decarboxylase 65 Isoform (GAD65) by Phosphorylation at Threonine 95 (T95). Mol Neurobiol 2016; 54:866-873. [DOI: 10.1007/s12035-015-9633-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2015] [Accepted: 12/15/2015] [Indexed: 11/26/2022]
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17
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Brownlow N, Pike T, Crossland V, Claus J, Parker P. Regulation of the cytokinesis cleavage furrow by PKCε. Biochem Soc Trans 2014; 42:1534-7. [PMID: 25399566 DOI: 10.1042/bst20140240] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cytokinesis is the final act of the cell cycle where the replicated DNA and cellular contents are finally split into two daughter cells. This process is very tightly controlled as DNA segregation errors and cytokinesis failure is commonly associated with aneuploidy and aggressive tumours. Protein kinase Cε (PKCε) is a lipid-activated serine/threonine kinase that is part of the PKC superfamily. PKCε plays a complex role in the regulation of migration, adhesion and cytokinesis and in the present article we discuss the interplay between these processes. Integrin-mediated interaction with the actin cytoskeleton is a known regulator of cell adhesion and migration and there is emerging evidence that this pathway may also be essential for cytokinesis. We discuss evidence that a known actin-binding region in PKCε is involved in PKCε-mediated regulation of cytokinesis, providing a link between integrin-mediated stabilization of the cytokinesis furrow and PKCε recruitment.
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Affiliation(s)
- Nicola Brownlow
- *Protein Phosphorylation Laboratory, Cancer Research UK London Research Institute, London WC2A 3LY, U.K
| | - Tanya Pike
- *Protein Phosphorylation Laboratory, Cancer Research UK London Research Institute, London WC2A 3LY, U.K
| | - Victoria Crossland
- *Protein Phosphorylation Laboratory, Cancer Research UK London Research Institute, London WC2A 3LY, U.K
| | - Jeroen Claus
- *Protein Phosphorylation Laboratory, Cancer Research UK London Research Institute, London WC2A 3LY, U.K
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18
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Ann J, Yoon S, Baek J, Kim DH, Lewin NE, Hill CS, Blumberg PM, Lee J. Design and synthesis of protein kinase C epsilon selective diacylglycerol lactones (DAG-lactones). Eur J Med Chem 2014; 90:332-41. [PMID: 25437619 DOI: 10.1016/j.ejmech.2014.11.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 10/29/2014] [Accepted: 11/11/2014] [Indexed: 10/24/2022]
Abstract
DAG-lactones afford a synthetically accessible, high affinity platform for probing structure activity relationships at the C1 regulatory domain of protein kinase C (PKC). Given the central role of PKC isoforms in cellular signaling, along with their differential biological activities, a critical objective is the design of isoform selective ligands. Here, we report the synthesis of a series of DAG-lactones varying in their side chains, with a particular focus on linoleic acid derivatives. We evaluated their selectivity for PKC epsilon versus PKC alpha both under standard lipid conditions (100% phosphatidylserine, PS) as well as in the presence of a nuclear membrane mimetic lipid mixture (NML). We find that selectivity for PKC epsilon versus PKC alpha tended to be enhanced in the presence of the nuclear membrane mimetic lipid mixture and, for our lead compound, report a selectivity of 32-fold.
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Affiliation(s)
- Jihyae Ann
- Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea
| | - Suyoung Yoon
- Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea
| | - Jisoo Baek
- Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea
| | - Da Hye Kim
- Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea
| | - Nancy E Lewin
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Colin S Hill
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Peter M Blumberg
- Laboratory of Cancer Biology and Genetics, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892, USA
| | - Jeewoo Lee
- Laboratory of Medicinal Chemistry, Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Republic of Korea.
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19
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Garg R, Benedetti LG, Abera MB, Wang H, Abba M, Kazanietz MG. Protein kinase C and cancer: what we know and what we do not. Oncogene 2014; 33:5225-37. [PMID: 24336328 DOI: 10.1038/onc.2013.524] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 10/20/2013] [Accepted: 10/20/2013] [Indexed: 02/08/2023]
Abstract
Since their discovery in the late 1970s, protein kinase C (PKC) isozymes represent one of the most extensively studied signaling kinases. PKCs signal through multiple pathways and control the expression of genes relevant for cell cycle progression, tumorigenesis and metastatic dissemination. Despite the vast amount of information concerning the mechanisms that control PKC activation and function in cellular models, the relevance of individual PKC isozymes in the progression of human cancer is still a matter of controversy. Although the expression of PKC isozymes is altered in multiple cancer types, the causal relationship between such changes and the initiation and progression of the disease remains poorly defined. Animal models developed in the last years helped to better understand the involvement of individual PKCs in various cancer types and in the context of specific oncogenic alterations. Unraveling the enormous complexity in the mechanisms by which PKC isozymes have an impact on tumorigenesis and metastasis is key for reassessing their potential as pharmacological targets for cancer treatment.
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Affiliation(s)
- R Garg
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - L G Benedetti
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M B Abera
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - H Wang
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - M Abba
- Centro de Investigaciones Inmunológicas Básicas y Aplicadas (CINIBA), Facultad de Ciencias Médicas, Universidad Nacional de La Plata, La Plata, Argentina
| | - M G Kazanietz
- Department of Pharmacology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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20
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Stiles BG, Pradhan K, Fleming JM, Samy RP, Barth H, Popoff MR. Clostridium and bacillus binary enterotoxins: bad for the bowels, and eukaryotic being. Toxins (Basel) 2014; 6:2626-56. [PMID: 25198129 PMCID: PMC4179152 DOI: 10.3390/toxins6092626] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 08/22/2014] [Accepted: 08/27/2014] [Indexed: 12/18/2022] Open
Abstract
Some pathogenic spore-forming bacilli employ a binary protein mechanism for intoxicating the intestinal tracts of insects, animals, and humans. These Gram-positive bacteria and their toxins include Clostridium botulinum (C2 toxin), Clostridium difficile (C. difficile toxin or CDT), Clostridium perfringens (ι-toxin and binary enterotoxin, or BEC), Clostridium spiroforme (C. spiroforme toxin or CST), as well as Bacillus cereus (vegetative insecticidal protein or VIP). These gut-acting proteins form an AB complex composed of ADP-ribosyl transferase (A) and cell-binding (B) components that intoxicate cells via receptor-mediated endocytosis and endosomal trafficking. Once inside the cytosol, the A components inhibit normal cell functions by mono-ADP-ribosylation of globular actin, which induces cytoskeletal disarray and death. Important aspects of each bacterium and binary enterotoxin will be highlighted in this review, with particular focus upon the disease process involving the biochemistry and modes of action for each toxin.
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Affiliation(s)
- Bradley G Stiles
- Biology Department, Wilson College, 1015 Philadelphia Avenue, Chambersburg, PA 17201, USA.
| | - Kisha Pradhan
- Environmental Science Department, Wilson College, 1015 Philadelphia Avenue, Chambersburg, PA 17201, USA.
| | - Jodie M Fleming
- Department of Biology, North Carolina Central University, 1801 Fayetteville Street, Durham, NC 27707, USA.
| | - Ramar Perumal Samy
- Venom and Toxin Research Programme, Department of Anatomy, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Kent Ridge 117597, Singapore.
| | - Holger Barth
- Institute of Pharmacology and Toxicology, University of Ulm Medical Center, Albert-Einstein-Allee 11, Ulm D-89081, Germany.
| | - Michel R Popoff
- Bacteries Anaerobies et Toxines, Institut Pasteur, 28 Rue du Docteur Roux, Paris 75724, France.
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21
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Hoque M, Rentero C, Cairns R, Tebar F, Enrich C, Grewal T. Annexins — Scaffolds modulating PKC localization and signaling. Cell Signal 2014; 26:1213-25. [DOI: 10.1016/j.cellsig.2014.02.012] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 02/22/2014] [Indexed: 12/15/2022]
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22
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Ong ST, Freeley M, Skubis-Zegadło J, Fazil MHUT, Kelleher D, Fresser F, Baier G, Verma NK, Long A. Phosphorylation of Rab5a protein by protein kinase Cϵ is crucial for T-cell migration. J Biol Chem 2014; 289:19420-34. [PMID: 24872409 DOI: 10.1074/jbc.m113.545863] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Rab GTPases control membrane traffic and receptor-mediated endocytosis. Within this context, Rab5a plays an important role in the spatial regulation of intracellular transport and signal transduction processes. Here, we report a previously uncharacterized role for Rab5a in the regulation of T-cell motility. We show that Rab5a physically associates with protein kinase Cϵ (PKCϵ) in migrating T-cells. After stimulation of T-cells through the integrin LFA-1 or the chemokine receptor CXCR4, Rab5a is phosphorylated on an N-terminal Thr-7 site by PKCϵ. Both Rab5a and PKCϵ dynamically interact at the centrosomal region of migrating cells, and PKCϵ-mediated phosphorylation on Thr-7 regulates Rab5a trafficking to the cell leading edge. Furthermore, we demonstrate that Rab5a Thr-7 phosphorylation is functionally necessary for Rac1 activation, actin rearrangement, and T-cell motility. We present a novel mechanism by which a PKCϵ-Rab5a-Rac1 axis regulates cytoskeleton remodeling and T-cell migration, both of which are central for the adaptive immune response.
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Affiliation(s)
- Seow Theng Ong
- From the From the Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Dublin 8, Ireland
| | - Michael Freeley
- From the From the Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Dublin 8, Ireland
| | - Joanna Skubis-Zegadło
- From the From the Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Dublin 8, Ireland, Department of Applied Pharmacy and Bioengineering, Medical University of Warsaw, 02-091 Warsaw, Poland
| | | | - Dermot Kelleher
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 637553, Faculty of Medicine, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom, and
| | - Friedrich Fresser
- the Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, A-6020 Innsbruck, Austria
| | - Gottfried Baier
- the Department of Medical Genetics, Molecular and Clinical Pharmacology, Innsbruck Medical University, A-6020 Innsbruck, Austria
| | - Navin Kumar Verma
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore 637553,
| | - Aideen Long
- From the From the Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin, Dublin 8, Ireland,
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23
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Jain K, Basu A. The Multifunctional Protein Kinase C-ε in Cancer Development and Progression. Cancers (Basel) 2014; 6:860-78. [PMID: 24727247 PMCID: PMC4074807 DOI: 10.3390/cancers6020860] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 03/27/2014] [Accepted: 04/01/2014] [Indexed: 12/31/2022] Open
Abstract
The protein kinase C (PKC) family proteins are important signal transducers and have long been the focus of cancer research. PKCɛ, a member of this family, is overexpressed in most solid tumors and plays critical roles in different processes that lead to cancer development. Studies using cell lines and animal models demonstrated the transforming potential of PKCɛ. While earlier research established the survival functions of PKCɛ, recent studies revealed its role in cell migration, invasion and cancer metastasis. PKCɛ has also been implicated in epithelial to mesenchymal transition (EMT), which may be the underlying mechanism by which it contributes to cell motility. In addition, PKCɛ affects cell-extracellular matrix (ECM) interactions by direct regulation of the cytoskeletal elements. Recent studies have also linked PKCɛ signaling to cancer stem cell functioning. This review focuses on the role of PKCɛ in different processes that lead to cancer development and progression. We also discussed current literatures on the pursuit of PKCɛ as a target for cancer therapy.
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Affiliation(s)
- Kirti Jain
- Department of Molecular and Medical Genetics, University of North Texas Health Science Center, Institute for Cancer Research, and Focused on Resources for her Health Education and Research, Fort Worth, TX 76107, USA.
| | - Alakananda Basu
- Department of Molecular and Medical Genetics, University of North Texas Health Science Center, Institute for Cancer Research, and Focused on Resources for her Health Education and Research, Fort Worth, TX 76107, USA.
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24
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Kano T, Kouzuki T, Mizuno S, Ueda S, Yamanoue M, Sakane F, Saito N, Shirai Y. Both the C1 domain and a basic amino acid cluster at the C-terminus are important for the neurite and branch induction ability of DGKβ. Biochem Biophys Res Commun 2014; 447:89-94. [DOI: 10.1016/j.bbrc.2014.03.113] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Accepted: 03/22/2014] [Indexed: 01/14/2023]
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25
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Morphine mediates a proinflammatory phenotype via μ-opioid receptor–PKCɛ–Akt–ERK1/2 signaling pathway in activated microglial cells. Biochem Pharmacol 2013; 86:487-96. [DOI: 10.1016/j.bcp.2013.05.027] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 05/28/2013] [Accepted: 05/31/2013] [Indexed: 11/18/2022]
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26
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PKC-epsilon activation is required for recognition memory in the rat. Behav Brain Res 2013; 253:280-9. [PMID: 23911427 DOI: 10.1016/j.bbr.2013.07.036] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2013] [Revised: 07/18/2013] [Accepted: 07/22/2013] [Indexed: 11/20/2022]
Abstract
Activation of PKCɛ, an abundant and developmentally regulated PKC isoform in the brain, has been implicated in memory throughout life and across species. Yet, direct evidence for a mechanistic role for PKCɛ in memory is still lacking. Hence, we sought to evaluate this in rats, using short-term treatments with two PKCɛ-selective peptides, the inhibitory ɛV1-2 and the activating ψɛRACK, and the novel object recognition task (NORT). Our results show that the PKCɛ-selective activator ψɛRACK, did not have a significant effect on recognition memory. In the short time frames used, however, inhibition of PKCɛ activation with the peptide inhibitor ɛV1-2 significantly impaired recognition memory. Moreover, when we addressed at the molecular level the immediate proximal signalling events of PKCɛ activation in acutely dissected rat hippocampi, we found that ψɛRACK increased in a time-dependent manner phosphorylation of MARCKS and activation of Src, Raf, and finally ERK1/2, whereas ɛV1-2 inhibited all basal activity of this pathway. Taken together, these findings present the first direct evidence that PKCɛ activation is an essential molecular component of recognition memory and point toward the use of systemically administered PKCɛ-regulating peptides as memory study tools and putative therapeutic agents.
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27
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Hongpaisan J, Xu C, Sen A, Nelson TJ, Alkon DL. PKC activation during training restores mushroom spine synapses and memory in the aged rat. Neurobiol Dis 2013; 55:44-62. [DOI: 10.1016/j.nbd.2013.03.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Revised: 03/14/2013] [Accepted: 03/19/2013] [Indexed: 01/24/2023] Open
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Carracedo S, Braun U, Leitges M. Expression pattern of protein kinase C ϵ during mouse embryogenesis. BMC DEVELOPMENTAL BIOLOGY 2013; 13:16. [PMID: 23639204 PMCID: PMC3668281 DOI: 10.1186/1471-213x-13-16] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 04/24/2013] [Indexed: 12/29/2022]
Abstract
BACKGROUND Protein kinase C epsilon (PKCϵ) belongs to the novel PKC subfamily, which consists of diacylglycerol dependent- and calcium independent-PKCs. Previous studies have shown that PKCϵ is important in different contexts, such as wound healing or cancer. In this study, we contribute to expand the knowledge on PKCϵ by reporting its expression pattern during murine midgestation using the LacZ reporter gene and immunostaining procedures. RESULTS Sites showing highest PKCϵ expression were heart at ealier stages, and ganglia in older embryos. Other stained domains included somites, bone, stomach, kidney, and blood vessels. CONCLUSIONS The seemingly strong expression of PKCϵ in heart and ganglia shown in this study suggests a important role of this isoform in the vascular and nervous systems during mouse development. However, functional redundancy with other PKCs during midgestation within these domains and others reported here possibly exists since PKCϵ deficient mice do not display obvious embryonic developmental defects.
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Affiliation(s)
- Sergio Carracedo
- Biotechnology Centre of Oslo, University of Oslo, Gaustadalleen 21, Oslo, N-0349, Norway.
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29
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Abstract
Protein kinase C (PKC) has been a tantalizing target for drug discovery ever since it was first identified as the receptor for the tumour promoter phorbol ester in 1982. Although initial therapeutic efforts focused on cancer, additional indications--including diabetic complications, heart failure, myocardial infarction, pain and bipolar disorder--were targeted as researchers developed a better understanding of the roles of eight conventional and novel PKC isozymes in health and disease. Unfortunately, both academic and pharmaceutical efforts have yet to result in the approval of a single new drug that specifically targets PKC. Why does PKC remain an elusive drug target? This Review provides a short account of some of the efforts, challenges and opportunities in developing PKC modulators to address unmet clinical needs.
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30
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Biophysical Forces Modulate the Costamere and Z-Disc for Sarcomere Remodeling in Heart Failure. BIOPHYSICS OF THE FAILING HEART 2013. [DOI: 10.1007/978-1-4614-7678-8_7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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31
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Peterson TA, Stamnes M. ARF1-regulated coatomer directs the steady-state localization of protein kinase C epsilon at the Golgi apparatus. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012. [PMID: 23195223 DOI: 10.1016/j.bbamcr.2012.11.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Protein kinase C epsilon (PKCε) contributes to multiple signaling pathways affecting human disease. The function of PKCε requires it to undergo changes in subcellular distribution in response to signaling events. While the mechanisms underlying this translocation are incompletely understood, it involves the receptor for activated C kinase protein (RACK2/β'-COP). This receptor also functions as a vesicle coat protein in the secretory pathway where it is regulated by the small GTP-binding protein ADP-ribosylation factor, ARF1. We inhibited ARF1 activation to test the requirement for RACK2/β'-COP in PKCε localization in NIH3T3 fibroblasts. We found that steady-state localization of PKCε at the Golgi complex requires ARF1-regulated RACK2/β'-COP function. By contrast, we did not observe any defects in phorbol ester-induced translocation when ARF1 was inhibited. We also found that PKCε bound to isolated membranes through two distinct mechanisms. One mechanism was dependent upon RACK2/β'-COP while a second was RACK2/β'-COP-independent and stimulated by phorbol esters. Finally, we show that RACK2/β'-COP affects the subcellular distribution of a constitutively active form of PKCε, in a manner similar to what we observed for wild-type PKCε. Together, our data support a role for RACK2/β'-COP in the steady-state localization of PKCε at the Golgi apparatus, which may be independent of its role during PKCε translocation to the cell surface.
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Affiliation(s)
- Tabitha A Peterson
- Department of Molecular Physiology & Biophysics, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, Iowa City, IA 52242, USA
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Protein kinase C-theta in platelet activation. FEBS Lett 2011; 585:3208-15. [DOI: 10.1016/j.febslet.2011.09.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 08/20/2011] [Accepted: 09/12/2011] [Indexed: 02/05/2023]
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Duquesnes N, Lezoualc'h F, Crozatier B. PKC-delta and PKC-epsilon: foes of the same family or strangers? J Mol Cell Cardiol 2011; 51:665-73. [PMID: 21810427 DOI: 10.1016/j.yjmcc.2011.07.013] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 06/24/2011] [Accepted: 07/15/2011] [Indexed: 11/30/2022]
Abstract
Protein kinase C (PKC) is a family of 10 serine/threonine kinases divided into 3 subfamilies, classical, novel and atypical classes. Two PKC isozymes of the novel group, PKCε and PKCδ, have different and sometimes opposite effects. PKCε stimulates cell growth and differentiation while PKCδ is apoptotic. In the heart, they are among the most expressed PKC isozymes and they are opposed in the preconditioning process with a positive role of PKCε and an inhibiting role of PKCδ. The goal of this review is to analyze the structural differences of these 2 enzymes that may explain their different behaviors and properties.
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Epac2-dependent rap1 activation and the control of islet insulin secretion by glucagon-like peptide-1. VITAMINS AND HORMONES 2011; 84:279-302. [PMID: 21094904 DOI: 10.1016/b978-0-12-381517-0.00010-2] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Glucagon-like peptide-1 (GLP-1) binds its Class II G protein-coupled receptor to stimulate cyclic adenosine monophosphate (cAMP) production and to potentiate the glucose metabolism-dependent secretion of insulin from pancreatic β cells located within the islets of Langerhans. Prior clinical studies demonstrate that this cAMP-mediated action of GLP-1 to potentiate glucose-stimulated insulin secretion (GSIS) is of major therapeutic importance when evaluating the abilities of GLP-1 receptor (GLP-1R) agonists to lower levels of blood glucose in type 2 diabetic subjects. Surprisingly, recent in vitro studies of human or rodent islets of Langerhans provide evidence for the existence of a noncanonical mechanism of β cell cAMP signal transduction, one that may explain how GLP-1R agonists potentiate GSIS. What these studies demonstrate is that a cAMP-regulated guanine nucleotide exchange factor designated as Epac2 couples β cell cAMP production to the protein kinase A-independent stimulation of insulin exocytosis. Provided here is an overview of the Epac2 signal transduction system in β cells, with special emphasis on Rap1, a Ras-related GTPase that is an established target of Epac2.
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Chen Y, Tian Q. The role of protein kinase C epsilon in neural signal transduction and neurogenic diseases. Front Med 2011; 5:70-6. [PMID: 21681677 DOI: 10.1007/s11684-011-0119-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Accepted: 01/11/2011] [Indexed: 01/02/2023]
Abstract
Protein kinase C epsilon (PKC ɛ) is one of major isoforms in novel PKC family. Although it has been extensively characterized in the past decade, the role of PKC ɛ in neuron is still not well understood. Advances in molecular biology have now removed significant barriers to the direct investigation of PKC ɛ functions in vivo, and PKC ɛ has been increasingly implicated in the neural biological functions and associated neurogenic diseases. Recent studies have provided important insights into the influence of PKC ɛ on cortical processing at both the single cell level and network level. These studies provide compelling evidence that PKC ɛ could regulate distinct aspects of neural signal transduction and suggest that the coordinated actions of a number of molecular signals contribute to the specification and differentiation of PKC ɛ signal pathway in the developing brain.
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Affiliation(s)
- Yuan Chen
- Neurobiology Research Center, Zhongshan Medical School, Sun Yat-sen University, Guangzhou, 510080, China.
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Yang SH, Jeng CJ, Chen CH, Chen Y, Chen YC, Wang SM. Schisandrin enhances dendrite outgrowth and synaptogenesis in primary cultured hippocampal neurons. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2011; 91:694-702. [PMID: 21302324 DOI: 10.1002/jsfa.4238] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
BACKGROUND Schisandra chinensis, commonly used in Asia for tea material and traditional Chinese medicine, is presumed to enhance mental and intellectual functions. In this study, the effects and signalling mechanisms of a purified compound schisandrin, one of the lignan of Schisandra chinensis, on primary cultured hippocampal neurons were investigated. RESULTS Schisandrin treatment enhanced total dendritic length and branching complexity, both of which were significantly suppressed in the presence of specific blockers for calmodulin-dependent kinase II (CaMKII), protein kinase C epsilon (PKCε), and mitogen activated protein kinase kinase (MEK). Moreover, schisandrin induced calcium influx, and phosphorylation of CaMKII, PKCε, and MEK. Inhibition of CAMKII and PKCε attenuated the schisandrin-induced phosphorylation of PKCε and MEK, and the phosphorylation of MEK, respectively. Moreover, schisandrin also stimulated the phosphorylation of cyclic AMP responsive-element binding protein (CREB) at Ser-133, an effect that was blocked by KN93. In addition to its neuritogenic effects, schisandrin increased the numbers of postsynaptic density-95-positive and FM1-43-positive puncta in dendrites and synaptic boutons, respectively. CONCLUSION In hippocampal neurons, schisandrin exhibits neurotrophic properties that are mediated by the CaMKII-PKCε-MEK pathway.
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Affiliation(s)
- Shih-Hung Yang
- Department of Anatomy and Cell Biology, College of Medicine, National Taiwan University, No. 1, Section 1, Jen-Ai Road, Taipei 10051, Taiwan
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Frequency-dependent modes of synaptic vesicle endocytosis and exocytosis at adult mouse neuromuscular junctions. J Neurosci 2011; 31:1093-105. [PMID: 21248134 DOI: 10.1523/jneurosci.2800-10.2011] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
During locomotion, adult rodent lumbar motoneurons fire in high-frequency (80-100 Hz) 1-2 s bursts every several seconds, releasing between 10,000 and 20,000 vesicles per burst. The estimated total vesicle pool size indicates that all vesicles would be used within 30 s; thus, a mechanism for rapid endocytosis and vesicle recycling is necessary to maintain effective transmission and motor behavior. However, whether such rapid recycling exists at mouse neuromuscular junctions (NMJs) or how it is regulated has been unclear. Here, we show that much less FM1-43 dye is lost per stimulus with 100 Hz stimulation than with 10 Hz stimulation even when the same number of vesicles undergo exocytosis. Electrophysiological data using folimycin show this lesser amount of dye loss is caused in part by the rapid reuse of vesicles. We showed previously that a myosin light chain kinase (MLCK)-myosin II pathway was required for effective transmission at 100 Hz. Here, we confirm the activation of MLCK, based on increased nerve terminal phospho-MLC immunostaining, with 100 Hz but not with 10 Hz stimulation. We further demonstrate that activation of MLCK, by increased extracellular Ca(2+), by PKC (protein kinase C) activation, or by a MLCK agonist peptide, reduces the amount of dye lost even with 10 Hz stimulation. MLCK activation at 10 Hz also resulted in more vesicles being rapidly reused. Thus, MLCK activation by 100 Hz stimulation switches the mechanism of vesicle cycling to a rapid-reuse mode and is required to sustain effective transmission in adult mouse NMJs.
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Asimaki O, Mangoura D. Cannabinoid receptor 1 induces a biphasic ERK activation via multiprotein signaling complex formation of proximal kinases PKCε, Src, and Fyn in primary neurons. Neurochem Int 2010; 58:135-44. [PMID: 21074588 DOI: 10.1016/j.neuint.2010.11.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 11/02/2010] [Accepted: 11/03/2010] [Indexed: 11/17/2022]
Abstract
Cannabinoid receptors 1 (CB1Rs) play important roles in the regulation of dendritic branching, synapse density, and synaptic transmission through multiple G-protein-coupled signaling systems, including the activation of the extracellular signal-regulated kinases ERK1/2. The proximal signaling interactions leading to ERK1/2 activation by CB1R in CNS remain, however, unclear. Here, we present evidence that the CB1R agonist methanandamide induced a biphasic and sustained activation of ERK1/2 in primary neurons derived from E7 telencephalon. We show that E7 neurons natively express high levels of CB1R message and protein, the majority of which associates with PKCɛ at basal conditions. We now demonstrate that the first peak of ERK activation by CB1R was mediated by the sequential activation of G(q), PLC, and PKCɛ, selectively, and that the CB1R-activated PKCɛ acutely formed transient signaling modules containing activated Src and Fyn. A second pool of CB1Rs, coupled to PTX-sensitive activation of G(i/o), utilized as effectors additional Src and Fyn molecules to generate a second, additional wave of ERK activation at 15 min. Concurrently to these intermolecular signaling interactions, cytoskeleton-associated proteins MARCKS and p120catenin were drastically modified by phosphorylation of PKC and Src, respectively. These receptor-proximal signaling events correlated well with induction of neuritic outgrowth in the long term. Our data provide evidence for multiprotein signaling complex formation in the coupling of CB1R to activation of ERK in CNS neurons, and may elucidate several of the less understood acute effects of cannabinoid drugs.
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Affiliation(s)
- Olga Asimaki
- Developmental Neurobiology and Neurochemistry Group, Basic Neurosciences, Center for Preventive Medicine, Neurosciences and Social Psychiatry, Biomedical Research Foundation of the Academy of Athens, 4, Soranou Ephessiou Street, 11527 Athens, Greece
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Guo J, Cong L, Rybin VO, Gertsberg Z, Steinberg SF. Protein kinase C-{delta} regulates the subcellular localization of Shc in H2O2-treated cardiomyocytes. Am J Physiol Cell Physiol 2010; 299:C770-8. [PMID: 20686066 DOI: 10.1152/ajpcell.00170.2010] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Protein kinase C-δ (PKCδ) exerts important cardiac actions as a lipid-regulated kinase. There is limited evidence that PKCδ also might exert an additional kinase-independent action as a regulator of the subcellular compartmentalization of binding partners such as Shc (Src homologous and collagen), a family of adapter proteins that play key roles in growth regulation and oxidative stress responses. This study shows that native PKCδ forms complexes with endogenous Shc proteins in H(2)O(2)-treated cardiomyocytes; H(2)O(2) treatment also leads to the accumulation of PKCδ and Shc in a detergent-insoluble cytoskeletal fraction and in mitochondria. H(2)O(2)-dependent recruitment of Shc isoforms to cytoskeletal and mitochondrial fractions is amplified by wild-type-PKCδ overexpression, consistent with the notion that PKCδ acts as a signal-regulated scaffold to anchor Shc in specific subcellular compartments. However, overexpression studies with kinase-dead (KD)-PKCδ-K376R (an ATP-binding mutant of PKCδ that lacks catalytic activity) are less informative, since KD-PKCδ-K376R aberrantly localizes as a constitutively tyrosine-phosphorylated enzyme to detergent-insoluble and mitochondrial fractions of resting cardiomyocytes; relatively little KD-PKCδ-K376R remains in the cytosolic fraction. The aberrant localization and tyrosine phosphorylation patterns for KD-PKCδ-K376R do not phenocopy the properties of native PKCδ, even in cells chronically treated with GF109203X to inhibit PKCδ activity. Hence, while KD-PKCδ-K376R overexpression increases Shc localization to the detergent-insoluble and mitochondrial fractions, the significance of these results is uncertain. Our studies suggest that experiments using KD-PKCδ-K376R overexpression as a strategy to competitively inhibit the kinase-dependent actions of native PKCδ or to expose the kinase-independent scaffolding functions of PKCδ should be interpreted with caution.
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Affiliation(s)
- Jianfen Guo
- Department of Pharmacology, College of Physicians and Surgeons, Columbia Univ., 630 West 168 St., New York, NY 10032, USA
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Abstract
The epsilon isoform of protein kinase C (PKCepsilon) has important roles in the function of the cardiac, immune and nervous systems. As a result of its diverse actions, PKCepsilon is the target of active drug-discovery programmes. A major research focus is to identify signalling cascades that include PKCepsilon and the substrates that PKCepsilon regulates. In the present review, we identify and discuss those proteins that have been conclusively shown to be direct substrates of PKCepsilon by the best currently available means. We will also describe binding partners that anchor PKCepsilon near its substrates. We review the consequences of substrate phosphorylation and discuss cellular mechanisms by which target specificity is achieved. We begin with a brief overview of the biology of PKCepsilon and methods for substrate identification, and proceed with a discussion of substrate categories to identify common themes that emerge and how these may be used to guide future studies.
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Aromolaran KA, Benzow KA, Cribbs LL, Koob MD, Piedras-Rentería ES. T-type current modulation by the actin-binding protein Kelch-like 1. Am J Physiol Cell Physiol 2010; 298:C1353-62. [PMID: 20147652 DOI: 10.1152/ajpcell.00235.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report a novel form of modulation of T-type calcium currents carried out by the neuronal actin-binding protein (ABP) Kelch-like 1 (KLHL1). KLHL1 is a constitutive neuronal ABP localized to the soma and dendritic arbors; its genetic elimination in Purkinje neurons leads to dendritic atrophy and motor insufficiency. KLHL1 participates in neurite outgrowth and upregulates voltage-gated P/Q-type calcium channel function; here we investigated KLHL1's role as a modulator of low-voltage-gated calcium channels and determined the molecular mechanism of this modulation with electrophysiology and biochemistry. Coexpression of KLHL1 with Ca(V)3.1 or Ca(V)3.2 (alpha(1G) or alpha(1H) subunits) caused increases in T-type current density (35%) and calcium influx (75-83%) when carried out by alpha(1H) but not by alpha(1G). The association between KLHL1 and alpha(1H) was determined by immunoprecipitation and immunolocalization in brain membrane fractions and in vitro in HEK-293 cells. Noise analysis showed that neither alpha(1H) single-channel conductance nor open probability was altered by KLHL1, yet a significant increase in channel number was detected and further corroborated by Western blot analysis. KLHL1 also induced an increase in alpha(1H) current deactivation time (tau(deactivation)). Interestingly, the majority of KLHL1's effects were eliminated when the actin-binding motif (kelch) was removed, with the exception of the calcium influx increase during action potentials, indicating that KLHL1 interacts with alpha(1H) and actin and selectively regulates alpha(1H) function by increasing the number of alpha(1H) channels. This constitutes a novel regulatory mechanism of T-type calcium currents and supports the role of KLHL1 in the modulation of cellular excitability.
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Jani K, Schöck F. Molecular mechanisms of mechanosensing in muscle development. Dev Dyn 2009; 238:1526-34. [DOI: 10.1002/dvdy.21972] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Sivaramakrishnan S, Schneider JL, Sitikov A, Goldman RD, Ridge KM. Shear stress induced reorganization of the keratin intermediate filament network requires phosphorylation by protein kinase C zeta. Mol Biol Cell 2009; 20:2755-65. [PMID: 19357195 DOI: 10.1091/mbc.e08-10-1028] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Keratin intermediate filaments (KIFs) form a fibrous polymer network that helps epithelial cells withstand external mechanical forces. Recently, we established a correlation between the structure of the KIF network and its local mechanical properties in alveolar epithelial cells. Shear stress applied across the cell surface resulted in the structural remodeling of KIF and a substantial increase in the elastic modulus of the network. This study examines the mechanosignaling that regulates the structural remodeling of the KIF network. We report that the shear stress-mediated remodeling of the KIF network is facilitated by a twofold increase in the dynamic exchange rate of KIF subunits, which is regulated in a PKC zeta and 14-3-3-dependent manner. PKC zeta phosphorylates K18pSer33, and this is required for the structural reorganization because the KIF network in A549 cells transfected with a dominant negative PKC zeta, or expressing the K18Ser33Ala mutation, is unchanged. Blocking the shear stress-mediated reorganization results in reduced cellular viability and increased apoptotic levels. These data suggest that shear stress mediates the phosphorylation of K18pSer33, which is required for the reorganization of the KIF network, resulting in changes in mechanical properties of the cell that help maintain the integrity of alveolar epithelial cells.
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Moh MC, Tian Q, Zhang T, Lee LH, Shen S. The immunoglobulin-like cell adhesion molecule hepaCAM modulates cell adhesion and motility through direct interaction with the actin cytoskeleton. J Cell Physiol 2009; 219:382-91. [PMID: 19142852 DOI: 10.1002/jcp.21685] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Previously, we reported the identification of a novel immunoglobulin-like cell adhesion molecule hepaCAM that promotes cell-extracellular matrix (ECM) interactions including cell adhesion and motility. Cell-ECM interactions are known to be directed by the actin cytoskeleton. In this study, we examined the association of hepaCAM with the actin cytoskeleton. We found that hepaCAM was partially insoluble in Triton X-100 and colocalized with the actin cytoskeleton on the plasma membrane. Disruption of F-actin decreased the detergent insolubility and disturbed the subcellular localization of hepaCAM. Coimmunoprecipitation and F-actin cosedimentation assays revealed that hepaCAM directly bound to F-actin. In addition, we constructed three N- and C-terminal domain-deleted mutants of hepaCAM to determine the actin-binding region as well as to evaluate the effect of the domains on the biological function of hepaCAM. Detergent solubility assays showed that the cytoplasmic domain of hepaCAM might be required for actin association. However, deletion of either the extracellular or the cytoplasmic domain of hepaCAM abolished actin coprecipitation as well as delayed cell-ECM adhesion and cell motility. The data suggest that an intact hepaCAM protein is critical for establishing a stable physical association with the actin cytoskeleton; and such association is important for modulating hepaCAM-mediated cell adhesion and motility.
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Affiliation(s)
- Mei Chung Moh
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
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Churchill EN, Qvit N, Mochly-Rosen D. Rationally designed peptide regulators of protein kinase C. Trends Endocrinol Metab 2009; 20:25-33. [PMID: 19056296 PMCID: PMC2714361 DOI: 10.1016/j.tem.2008.10.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Revised: 09/30/2008] [Accepted: 10/01/2008] [Indexed: 11/23/2022]
Abstract
Protein-protein interactions sequester enzymes close to their substrates. Protein kinase C (PKC) is one example of a ubiquitous signaling molecule with effects that are dependent upon localization. Short peptides derived from interaction sites between each PKC isozyme and its receptor for activated C kinase act as highly specific inhibitors and have become available as selective drugs in basic research and animal models of human diseases, such as myocardial infarction and hyperglycemia. Whereas the earlier inhibitory peptides are highly specific, we believe that peptides targeting additional interactions between PKC and selective substrates will generate even more selective tools that regulate different functions of individual isozymes. Here, we discuss the methodologies and applications for identifying selective regulators of PKC.
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Affiliation(s)
- Eric N Churchill
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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Abstract
Protein kinase C (PKC) isoforms comprise a family of lipid-activated enzymes that have been implicated in a wide range of cellular functions. PKCs are modular enzymes comprised of a regulatory domain (that contains the membrane-targeting motifs that respond to lipid cofactors, and in the case of some PKCs calcium) and a relatively conserved catalytic domain that binds ATP and substrates. These enzymes are coexpressed and respond to similar stimulatory agonists in many cell types. However, there is growing evidence that individual PKC isoforms subserve unique (and in some cases opposing) functions in cells, at least in part as a result of isoform-specific subcellular compartmentalization patterns, protein-protein interactions, and posttranslational modifications that influence catalytic function. This review focuses on the structural basis for differences in lipid cofactor responsiveness for individual PKC isoforms, the regulatory phosphorylations that control the normal maturation, activation, signaling function, and downregulation of these enzymes, and the intra-/intermolecular interactions that control PKC isoform activation and subcellular targeting in cells. A detailed understanding of the unique molecular features that underlie isoform-specific posttranslational modification patterns, protein-protein interactions, and subcellular targeting (i.e., that impart functional specificity) should provide the basis for the design of novel PKC isoform-specific activator or inhibitor compounds that can achieve therapeutically useful changes in PKC signaling in cells.
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Affiliation(s)
- Susan F Steinberg
- Department of Pharmacology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA.
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Liu JX, Tang YC, Liu Y, Tang FR. mGluR5-PLCbeta4-PKCbeta2/PKCgamma pathways in hippocampal CA1 pyramidal neurons in pilocarpine model of status epilepticus in mGluR5+/+ mice. Epilepsy Res 2008; 82:111-23. [PMID: 18774262 DOI: 10.1016/j.eplepsyres.2008.07.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2008] [Revised: 06/27/2008] [Accepted: 07/18/2008] [Indexed: 10/21/2022]
Abstract
While it is generally accepted that phospholipase C (PLC) and protein kinase C (PKC) are down-stream proteins involved in metabotropic glutamate receptor 5 (mGluR5)-related signal transduction, we still do not know which subtype of PLC or PKC is specifically regulated after mGluR5 activation. In the present study in mGluR5 wild-type (mGluR5+/+) mice, we showed induced PKCbeta2 or PKCgamma expression at the border between the stratum oriens and alveus (O/A border) at 2h during pilocarpine induced status epilepticus (SE), and in the stratum pyramidale in CA1 area at 1 day after pilocarpine induced SE; at 1 day, induced expression of PLCbeta4 in the stratum pyramidale of CA1 area was observed. Furthermore, double labeling revealed the co-localization of induced PKCbeta2 or PKCgamma with mGluR5 or with induced PLCbeta4 in the stratum pyramidale of CA1 area. These induced expression, however, were not found in mGluR5 mutant (mGluR5-/-) mice. It suggests that induced PLCbeta4-PKCbeta2/PKCgamma at 1 day after pilocarpine induced SE in pyramidal neurons or PKCbeta2 or PKCgamma in interneurons at O/A border at 2h during pilocarpine induced SE may be specifically linked to the activation of mGluR5. When compared to mGluR5+/+ mice, significant shorter latency (from pilocarpine injection to the occurrence of status epilepticus) and maintenance period (from beginning to the end of status epilepticus) for status epilepticus in mGluR5-/- mice were also demonstrated. It is possible that mGluR5 may play a negative role in initiation of status epilepticus by interacting with muscarinic acetylcholine receptor in mGluR5+/+ mice.
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Affiliation(s)
- Jian Xin Liu
- Epilepsy Research Laboratory, National Neuroscience Institute, Singapore, Singapore
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Regulation of epithelial electrolyte transporters through protein-protein interactions. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008. [PMID: 18727254 DOI: 10.1007/0-387-23752-6_32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Akita Y. Protein kinase Cε: multiple roles in the function of, and signaling mediated by, the cytoskeleton. FEBS J 2008; 275:3995-4004. [DOI: 10.1111/j.1742-4658.2008.06557.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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