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Pilo CA, Baffi TR, Kornev AP, Kunkel MT, Malfavon M, Chen DH, Rossitto LA, Chen DX, Huang LC, Longman C, Kannan N, Raskind WH, Gonzalez DJ, Taylor SS, Gorrie G, Newton AC. Mutations in protein kinase Cγ promote spinocerebellar ataxia type 14 by impairing kinase autoinhibition. Sci Signal 2022; 15:eabk1147. [PMID: 36166510 PMCID: PMC9810342 DOI: 10.1126/scisignal.abk1147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Spinocerebellar ataxia type 14 (SCA14) is a neurodegenerative disease caused by germline variants in the diacylglycerol (DAG)/Ca2+-regulated protein kinase Cγ (PKCγ), leading to Purkinje cell degeneration and progressive cerebellar dysfunction. Most of the identified mutations cluster in the DAG-sensing C1 domains. Here, we found with a FRET-based activity reporter that SCA14-associated PKCγ mutations, including a previously undescribed variant, D115Y, enhanced the basal activity of the kinase by compromising its autoinhibition. Unlike other mutations in PKC that impair its autoinhibition but lead to its degradation, the C1 domain mutations protected PKCγ from such down-regulation. This enhanced basal signaling rewired the brain phosphoproteome, as revealed by phosphoproteomic analysis of cerebella from mice expressing a human SCA14-associated H101Y mutant PKCγ transgene. Mutations that induced a high basal activity in vitro were associated with earlier average age of onset in patients. Furthermore, the extent of disrupted autoinhibition, but not agonist-stimulated activity, correlated with disease severity. Molecular modeling indicated that almost all SCA14 variants not within the C1 domain were located at interfaces with the C1B domain, suggesting that mutations in and proximal to the C1B domain are a susceptibility for SCA14 because they uniquely enhance PKCγ basal activity while protecting the enzyme from down-regulation. These results provide insight into how PKCγ activation is modulated and how deregulation of the cerebellar phosphoproteome by SCA14-associated mutations affects disease progression.
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Affiliation(s)
- Caila A. Pilo
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
- Biomedical Sciences Graduate Program, University of California, La Jolla, CA 92037, USA
| | - Timothy R. Baffi
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Alexandr P. Kornev
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Maya T. Kunkel
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Mario Malfavon
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Dong-Hui Chen
- Department of Neurology, University of Washington Seattle, WA 98195, USA
| | - Leigh-Ana Rossitto
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
- Biomedical Sciences Graduate Program, University of California, La Jolla, CA 92037, USA
| | - Daniel X. Chen
- Department of Neurology, University of Washington Seattle, WA 98195, USA
| | - Liang-Chin Huang
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
| | - Cheryl Longman
- Queen Elizabeth University Hospital, Glasgow, Scotland G51 4TF, United Kingdom
| | - Natarajan Kannan
- Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Wendy H. Raskind
- Department of Medicine/Medical Genetics, University of Washington Seattle, WA 98195, USA
- Department of Psychiatry and Behavioral Sciences, University of Washington Seattle, WA 98195, USA
- Mental Illness Research, Education and Clinical Center, Department of Veterans Affairs, Seattle, WA 98108, USA
| | - David J. Gonzalez
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - Susan S. Taylor
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
| | - George Gorrie
- Queen Elizabeth University Hospital, Glasgow, Scotland G51 4TF, United Kingdom
| | - Alexandra C. Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, USA
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Pilo CA, Newton AC. Two Sides of the Same Coin: Protein Kinase C γ in Cancer and Neurodegeneration. Front Cell Dev Biol 2022; 10:929510. [PMID: 35800893 PMCID: PMC9253466 DOI: 10.3389/fcell.2022.929510] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 05/23/2022] [Indexed: 12/23/2022] Open
Abstract
Protein kinase C (PKC) isozymes transduce myriad signals within the cell in response to the generation of second messengers from membrane phospholipids. The conventional isozyme PKCγ reversibly binds Ca2+ and diacylglycerol, which leads to an open, active conformation. PKCγ expression is typically restricted to neurons, but evidence for its expression in certain cancers has emerged. PKC isozymes have been labeled as oncogenes since the discovery that they bind tumor-promoting phorbol esters, however, studies of cancer-associated PKC mutations and clinical trial data showing that PKC inhibitors have worsened patient survival have reframed PKC as a tumor suppressor. Aberrant expression of PKCγ in certain cancers suggests a role outside the brain, although whether PKCγ also acts as a tumor suppressor remains to be established. On the other hand, PKCγ variants associated with spinocerebellar ataxia type 14 (SCA14), a neurodegenerative disorder characterized by Purkinje cell degeneration, enhance basal activity while preventing phorbol ester-mediated degradation. Although the basis for SCA14 Purkinje cell degeneration remains unknown, studies have revealed how altered PKCγ activity rewires cerebellar signaling to drive SCA14. Importantly, enhanced basal activity of SCA14-associated mutants inversely correlates with age of onset, supporting that enhanced PKCγ activity drives SCA14. Thus, PKCγ activity should likely be inhibited in SCA14, whereas restoring PKC activity should be the goal in cancer therapies. This review describes how PKCγ activity can be lost or gained in disease and the overarching need for a PKC structure as a powerful tool to predict the effect of PKCγ mutations in disease.
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Affiliation(s)
- Caila A. Pilo
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States
- Biomedical Sciences Graduate Program, University of California, San Diego, San Diego, CA, United States
| | - Alexandra C. Newton
- Department of Pharmacology, University of California, San Diego, San Diego, CA, United States
- *Correspondence: Alexandra C. Newton,
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Pilo CA, Kunkel MT, Van AAN, Kobori EK, Longman C, Gorrie G, Taylor SS, Newton AC. Impaired Autoinhibition of Protein Kinase Cγ in Spinocerebellar Ataxia Type 14. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.04177] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Kajimoto T, Caliman AD, Tobias IS, Okada T, Pilo CA, Van AAN, McCammon JA, Nakamura SI, Newton AC. A new molecular mechanism of evasion of apoptosis revealed by novel C‐kinase activity reporter. FASEB J 2020. [DOI: 10.1096/fasebj.2020.34.s1.03250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Pilo CA, Kunkel MT, Van AAN, Kobori EK, Kornev AP, Longman C, Gorrie G, Taylor SS, Newton AC. Impaired Autoinhibition of Protein Kinase Cγ in Spinocerebellar Ataxia Type 14. Biophys J 2020. [DOI: 10.1016/j.bpj.2019.11.2936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Kajimoto T, Caliman AD, Tobias IS, Okada T, Pilo CA, Van AAN, Andrew McCammon J, Nakamura SI, Newton AC. Activation of atypical protein kinase C by sphingosine 1-phosphate revealed by an aPKC-specific activity reporter. Sci Signal 2019; 12:eaat6662. [PMID: 30600259 PMCID: PMC6657501 DOI: 10.1126/scisignal.aat6662] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Atypical protein kinase C (aPKC) isozymes are unique in the PKC superfamily in that they are not regulated by the lipid second messenger diacylglycerol, which has led to speculation about whether a different second messenger acutely controls their function. Here, using a genetically encoded reporter that we designed, aPKC-specific C kinase activity reporter (aCKAR), we found that the lipid mediator sphingosine 1-phosphate (S1P) promoted the cellular activity of aPKC. Intracellular S1P directly bound to the purified kinase domain of aPKC and relieved autoinhibitory constraints, thereby activating the kinase. In silico studies identified potential binding sites on the kinase domain, one of which was validated biochemically. In HeLa cells, S1P-dependent activation of aPKC suppressed apoptosis. Together, our findings identify a previously undescribed molecular mechanism of aPKC regulation, a molecular target for S1P in cell survival regulation, and a tool to further explore the biochemical and biological functions of aPKC.
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Affiliation(s)
- Taketoshi Kajimoto
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92037, USA.
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Kobe University, Kobe 650-0017, Japan
| | - Alisha D Caliman
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92037, USA
| | - Irene S Tobias
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92037, USA
| | - Taro Okada
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Kobe University, Kobe 650-0017, Japan
| | - Caila A Pilo
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92037, USA
| | - An-Angela N Van
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92037, USA
| | - J Andrew McCammon
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92037, USA
| | - Shun-Ichi Nakamura
- Division of Biochemistry, Department of Biochemistry and Molecular Biology, Graduate School of Medicine, Kobe University, Kobe 650-0017, Japan
| | - Alexandra C Newton
- Department of Pharmacology, University of California at San Diego, La Jolla, CA 92037, USA.
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Stanford SM, Svensson MND, Sacchetti C, Pilo CA, Wu DJ, Kiosses WB, Hellvard A, Bergum B, Muench GRA, Elly C, Liu YC, den Hertog J, Elson A, Sap J, Mydel P, Boyle DL, Corr M, Firestein GS, Bottini N. Receptor Protein Tyrosine Phosphatase α-Mediated Enhancement of Rheumatoid Synovial Fibroblast Signaling and Promotion of Arthritis in Mice. Arthritis Rheumatol 2016; 68:359-69. [PMID: 26414708 DOI: 10.1002/art.39442] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 09/15/2015] [Indexed: 01/03/2023]
Abstract
OBJECTIVE During rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) critically promote disease pathogenesis by aggressively invading the extracellular matrix of the joint. The focal adhesion kinase (FAK) signaling pathway is emerging as a contributor to the anomalous behavior of RA FLS. The receptor protein tyrosine phosphatase α (RPTPα), which is encoded by the PTPRA gene, is a key promoter of FAK signaling. The aim of this study was to investigate whether RPTPα mediates FLS aggressiveness and RA pathogenesis. METHODS Through RPTPα knockdown, we assessed FLS gene expression by quantitative polymerase chain reaction analysis and enzyme-linked immunosorbent assay, invasion and migration by Transwell assays, survival by annexin V and propidium iodide staining, adhesion and spreading by immunofluorescence microscopy, and activation of signaling pathways by Western blotting of FLS lysates. Arthritis development was examined in RPTPα-knockout (KO) mice using the K/BxN serum-transfer model. The contribution of radiosensitive and radioresistant cells to disease was evaluated by reciprocal bone marrow transplantation. RESULTS RPTPα was enriched in the RA synovial lining. RPTPα knockdown impaired RA FLS survival, spreading, migration, invasiveness, and responsiveness to platelet-derived growth factor, tumor necrosis factor, and interleukin-1 stimulation. These phenotypes correlated with increased phosphorylation of Src on inhibitory Y(527) and decreased phosphorylation of FAK on stimulatory Y(397) . Treatment of RA FLS with an inhibitor of FAK phenocopied the knockdown of RPTPα. RPTPα-KO mice were protected from arthritis development, which was due to radioresistant cells. CONCLUSION By regulating the phosphorylation of Src and FAK, RPTPα mediates proinflammatory and proinvasive signaling in RA FLS, correlating with the promotion of disease in an FLS-dependent model of RA.
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Affiliation(s)
| | | | | | - Caila A Pilo
- La Jolla Institute for Allergy and Immunology, La Jolla, California
| | - Dennis J Wu
- La Jolla Institute for Allergy and Immunology, La Jolla, California
| | | | - Annelie Hellvard
- Broegelmann Research Laboratory and University of Bergen, Bergen, Norway
| | - Brith Bergum
- Broegelmann Research Laboratory and University of Bergen, Bergen, Norway
| | | | - Christian Elly
- La Jolla Institute for Allergy and Immunology, La Jolla, California
| | - Yun-Cai Liu
- La Jolla Institute for Allergy and Immunology, La Jolla, California
| | - Jeroen den Hertog
- Hubrecht Institute-Koninklijke Nederlands Akademie van Wetenschappen and University Medical Center Utrecht, Utrecht, The Netherlands, and Institute of Biology, Leiden, The Netherlands
| | - Ari Elson
- Weizmann Institute of Science, Rehovot, Israel
| | - Jan Sap
- Université Paris Diderot, Sorbonne Paris Cité, Paris, France
| | - Piotr Mydel
- Broegelmann Research Laboratory and University of Bergen, Bergen, Norway
| | - David L Boyle
- University of California at San Diego School of Medicine, La Jolla
| | - Maripat Corr
- University of California at San Diego School of Medicine, La Jolla
| | - Gary S Firestein
- University of California at San Diego School of Medicine, La Jolla
| | - Nunzio Bottini
- La Jolla Institute for Allergy and Immunology, La Jolla, California
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