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Nashi S, Singh R, Menon D, Arshad F, Alladi S, Mahale RR. Sensory Neuropathy in Spinocerebellar Ataxia Type 14: A Novel Phenotype. Ann Indian Acad Neurol 2023; 26:591-593. [PMID: 37970274 PMCID: PMC10645198 DOI: 10.4103/aian.aian_324_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 04/21/2023] [Accepted: 05/02/2023] [Indexed: 11/17/2023] Open
Affiliation(s)
- Saraswati Nashi
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
| | - Raviprakash Singh
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
| | - Deepak Menon
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
| | - Faheem Arshad
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
| | - Suvarna Alladi
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
| | - Rohan R. Mahale
- Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, Karnataka, India
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2
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Kapfhammer JP, Shimobayashi E. Viewpoint: spinocerebellar ataxias as diseases of Purkinje cell dysfunction rather than Purkinje cell loss. Front Mol Neurosci 2023; 16:1182431. [PMID: 37426070 PMCID: PMC10323145 DOI: 10.3389/fnmol.2023.1182431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Accepted: 05/22/2023] [Indexed: 07/11/2023] Open
Abstract
Spinocerebellar ataxias (SCAs) are a group of hereditary neurodegenerative diseases mostly affecting cerebellar Purkinje cells caused by a wide variety of different mutations. One subtype, SCA14, is caused by mutations of Protein Kinase C gamma (PKCγ), the dominant PKC isoform present in Purkinje cells. Mutations in the pathway in which PKCγ is active, i.e., in the regulation of calcium levels and calcium signaling in Purkinje cells, are the cause of several other variants of SCA. In SCA14, many of the observed mutations in the PKCγ gene were shown to increase the basal activity of PKCγ, raising the possibility that increased activity of PKCγ might be the cause of most forms of SCA14 and might also be involved in the pathogenesis of SCA in related subtypes. In this viewpoint and review article we will discuss the evidence for and against such a major role of PKCγ basal activity and will suggest a hypothesis of how PKCγ activity and the calcium signaling pathway may be involved in the pathogenesis of SCAs despite the different and sometimes opposing effects of mutations affecting these pathways. We will then widen the scope and propose a concept of SCA pathogenesis which is not primarily driven by cell death and loss of Purkinje cells but rather by dysfunction of Purkinje cells which are still present and alive in the cerebellum.
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3
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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] [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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4
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Wu QW, Kapfhammer JP. The Emerging Key Role of the mGluR1-PKCγ Signaling Pathway in the Pathogenesis of Spinocerebellar Ataxias: A Neurodevelopmental Viewpoint. Int J Mol Sci 2022; 23:ijms23169169. [PMID: 36012439 PMCID: PMC9409119 DOI: 10.3390/ijms23169169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 08/11/2022] [Accepted: 08/12/2022] [Indexed: 12/19/2022] Open
Abstract
Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal dominantly inherited progressive disorders with degeneration and dysfunction of the cerebellum. Although different subtypes of SCAs are classified according to the disease-associated causative genes, the clinical syndrome of the ataxia is shared, pointing towards a possible convergent pathogenic pathway among SCAs. In this review, we summarize the role of SCA-associated gene function during cerebellar Purkinje cell development and discuss the relationship between SCA pathogenesis and neurodevelopment. We will summarize recent studies on molecules involved in SCA pathogenesis and will focus on the mGluR1-PKCγ signaling pathway evaluating the possibility that this might be a common pathway which contributes to these diseases.
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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] [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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Lordén G, Newton A. Conventional protein kinase C in the brain: repurposing cancer drugs for neurodegenerative treatment? Neuronal Signal 2021; 5:NS20210036. [PMID: 34737895 PMCID: PMC8536831 DOI: 10.1042/ns20210036] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 09/16/2021] [Accepted: 09/17/2021] [Indexed: 12/23/2022] Open
Abstract
Protein Kinase C (PKC) isozymes are tightly regulated kinases that transduce a myriad of signals from receptor-mediated hydrolysis of membrane phospholipids. They play an important role in brain physiology, and dysregulation of PKC activity is associated with neurodegeneration. Gain-of-function mutations in PKCα are associated with Alzheimer's disease (AD) and mutations in PKCγ cause spinocerebellar ataxia (SCA) type 14 (SCA14). This article presents an overview of the role of the conventional PKCα and PKCγ in neurodegeneration and proposes repurposing PKC inhibitors, which failed in clinical trials for cancer, for the treatment of neurodegenerative diseases.
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Affiliation(s)
- Gema Lordén
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, U.S.A
| | - Alexandra C. Newton
- Department of Pharmacology, University of California, San Diego, La Jolla, CA 92037, U.S.A
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7
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De Michele G, Galatolo D, Galosi S, Mignarri A, Silvestri G, Casali C, Leuzzi V, Ricca I, Barghigiani M, Tessa A, Cioffi E, Caputi C, Riso V, Dotti MT, Saccà F, De Michele G, Cocozza S, Filla A, Santorelli FM. Episodic ataxia and severe infantile phenotype in spinocerebellar ataxia type 14: expansion of the phenotype and novel mutations. J Neurol 2021; 269:1476-1484. [PMID: 34292398 PMCID: PMC8857164 DOI: 10.1007/s00415-021-10712-5] [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: 04/03/2021] [Revised: 07/08/2021] [Accepted: 07/10/2021] [Indexed: 12/30/2022]
Abstract
Introduction Spinocerebellar ataxia type 14 (SCA14) is a dominantly inherited neurological disorder characterized by slowly progressive cerebellar ataxia. SCA14 is caused by mutations in PRKCG, a gene encoding protein kinase C gamma (PKCγ), a master regulator of Purkinje cells development. Methods We performed next-generation sequencing targeted resequencing panel encompassing 273 ataxia genes in 358 patients with genetically undiagnosed ataxia. Results We identified fourteen patients in ten families harboring nine pathogenic heterozygous variants in PRKCG, seven of which were novel. We encountered four patients with not previously described phenotypes: one with episodic ataxia, one with a spastic paraparesis dominating her clinical manifestations, and two children with an unusually severe phenotype. Conclusions Our study broadens the genetic and clinical spectrum of SCA14. Supplementary Information The online version contains supplementary material available at 10.1007/s00415-021-10712-5.
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Affiliation(s)
- Giovanna De Michele
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, Federico II University, Via Sergio Pansini 5, 80131, Naples, Italy
| | - Daniele Galatolo
- Istituto Di Ricovero E Cura a Carattere Scientifico (IRCCS), Fondazione Stella Maris, Pisa, Italy
| | - Serena Galosi
- Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
| | - Andrea Mignarri
- Department of Medicine, Surgery and Neuroscience, Neurology and Neurometabolic Unit, University of Siena, Siena, Italy
| | - Gabriella Silvestri
- Department of Neurosciences, Faculty of Medicine and Surgery, Catholic University of Sacred Heart, Rome, Italy
- Neurology Unit, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Carlo Casali
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Rome, Italy
| | - Vincenzo Leuzzi
- Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
| | - Ivana Ricca
- Istituto Di Ricovero E Cura a Carattere Scientifico (IRCCS), Fondazione Stella Maris, Pisa, Italy
| | - Melissa Barghigiani
- Istituto Di Ricovero E Cura a Carattere Scientifico (IRCCS), Fondazione Stella Maris, Pisa, Italy
| | - Alessandra Tessa
- Istituto Di Ricovero E Cura a Carattere Scientifico (IRCCS), Fondazione Stella Maris, Pisa, Italy
| | - Ettore Cioffi
- Department of Medical and Surgical Sciences and Biotechnologies, Sapienza University of Rome, Rome, Italy
| | - Caterina Caputi
- Department of Human Neuroscience, Sapienza University of Rome, Rome, Italy
| | - Vittorio Riso
- Department of Neurosciences, Faculty of Medicine and Surgery, Catholic University of Sacred Heart, Rome, Italy
- Neurology Unit, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Maria Teresa Dotti
- Department of Medicine, Surgery and Neuroscience, Neurology and Neurometabolic Unit, University of Siena, Siena, Italy
| | - Francesco Saccà
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, Federico II University, Via Sergio Pansini 5, 80131, Naples, Italy
| | - Giuseppe De Michele
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, Federico II University, Via Sergio Pansini 5, 80131, Naples, Italy
| | - Sirio Cocozza
- Department of Advanced Biomedical Sciences, Federico II University, Naples, Italy
| | - Alessandro Filla
- Department of Neurosciences, Reproductive and Odontostomatological Sciences, Federico II University, Via Sergio Pansini 5, 80131, Naples, Italy.
| | - Filippo M Santorelli
- Istituto Di Ricovero E Cura a Carattere Scientifico (IRCCS), Fondazione Stella Maris, Pisa, Italy
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8
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Sun H, Shen XR, Fang ZB, Jiang ZZ, Wei XJ, Wang ZY, Yu XF. Next-Generation Sequencing Technologies and Neurogenetic Diseases. Life (Basel) 2021; 11:life11040361. [PMID: 33921670 PMCID: PMC8072598 DOI: 10.3390/life11040361] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/05/2021] [Accepted: 04/16/2021] [Indexed: 12/18/2022] Open
Abstract
Next-generation sequencing (NGS) technology has led to great advances in understanding the causes of Mendelian and complex neurological diseases. Owing to the complexity of genetic diseases, the genetic factors contributing to many rare and common neurological diseases remain poorly understood. Selecting the correct genetic test based on cost-effectiveness, coverage area, and sequencing range can improve diagnosis, treatments, and prevention. Whole-exome sequencing and whole-genome sequencing are suitable methods for finding new mutations, and gene panels are suitable for exploring the roles of specific genes in neurogenetic diseases. Here, we provide an overview of the classifications, applications, advantages, and limitations of NGS in research on neurological diseases. We further provide examples of NGS-based explorations and insights of the genetic causes of neurogenetic diseases, including Charcot-Marie-Tooth disease, spinocerebellar ataxias, epilepsy, and multiple sclerosis. In addition, we focus on issues related to NGS-based analyses, including interpretations of variants of uncertain significance, de novo mutations, congenital genetic diseases with complex phenotypes, and single-molecule real-time approaches.
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Affiliation(s)
| | | | | | | | | | | | - Xue-Fan Yu
- Correspondence: ; Tel.: +86-157-5430-1836
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9
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Schmitz-Hübsch T, Lux S, Bauer P, Brandt AU, Schlapakow E, Greschus S, Scheel M, Gärtner H, Kirlangic ME, Gras V, Timmann D, Synofzik M, Giorgetti A, Carloni P, Shah JN, Schöls L, Kopp U, Bußenius L, Oberwahrenbrock T, Zimmermann H, Pfueller C, Kadas EM, Rönnefarth M, Grosch AS, Endres M, Amunts K, Paul F, Doss S, Minnerop M. Spinocerebellar ataxia type 14: refining clinicogenetic diagnosis in a rare adult-onset disorder. Ann Clin Transl Neurol 2021; 8:774-789. [PMID: 33739604 PMCID: PMC8045942 DOI: 10.1002/acn3.51315] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 12/29/2020] [Accepted: 01/13/2021] [Indexed: 12/29/2022] Open
Abstract
Objectives Genetic variant classification is a challenge in rare adult‐onset disorders as in SCA‐PRKCG (prior spinocerebellar ataxia type 14) with mostly private conventional mutations and nonspecific phenotype. We here propose a refined approach for clinicogenetic diagnosis by including protein modeling and provide for confirmed SCA‐PRKCG a comprehensive phenotype description from a German multi‐center cohort, including standardized 3D MR imaging. Methods This cross‐sectional study prospectively obtained neurological, neuropsychological, and brain imaging data in 33 PRKCG variant carriers. Protein modeling was added as a classification criterion in variants of uncertain significance (VUS). Results Our sample included 25 cases confirmed as SCA‐PRKCG (14 variants, thereof seven novel variants) and eight carriers of variants assigned as VUS (four variants) or benign/likely benign (two variants). Phenotype in SCA‐PRKCG included slowly progressive ataxia (onset at 4–50 years), preceded in some by early‐onset nonprogressive symptoms. Ataxia was often combined with action myoclonus, dystonia, or mild cognitive‐affective disturbance. Inspection of brain MRI revealed nonprogressive cerebellar atrophy. As a novel finding, a previously not described T2 hyperintense dentate nucleus was seen in all SCA‐PRKCG cases but in none of the controls. Interpretation In this largest cohort to date, SCA‐PRKCG was characterized as a slowly progressive cerebellar syndrome with some clinical and imaging features suggestive of a developmental disorder. The observed non‐ataxia movement disorders and cognitive‐affective disturbance may well be attributed to cerebellar pathology. Protein modeling emerged as a valuable diagnostic tool for variant classification and the newly described T2 hyperintense dentate sign could serve as a supportive diagnostic marker of SCA‐PRKCG.
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Affiliation(s)
- Tanja Schmitz-Hübsch
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health Berlin, Berlin, Germany.,Experimental and Clinical Research Center, Max Delbrueck Center for Molecular Medicine and Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Silke Lux
- Department of Psychiatry and Psychotherapy, University Hospital Bonn, Bonn, Germany
| | - Peter Bauer
- Institute of Medical Genetics and Applied Genomics, University of Tübingen, Tübingen, Germany.,CENTOGENE AG, Rostock, Germany
| | - Alexander U Brandt
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health Berlin, Berlin, Germany.,Department of Neurology, University of California, Irvine, CA, USA
| | - Elena Schlapakow
- Department of Neurology, University Hospital Bonn, Bonn, Germany.,Center for Rare Diseases, University of Bonn, Bonn, Germany
| | - Susanne Greschus
- Department of Radiology, University Hospital Bonn, Bonn, Germany
| | - Michael Scheel
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health Berlin, Berlin, Germany.,Department of Neuroradiology, Charité -Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Hanna Gärtner
- Institute of Neuroscience and Medicine (INM-1), Research Centre Juelich, Juelich, Germany
| | - Mehmet E Kirlangic
- Institute of Neuroscience and Medicine (INM-1), Research Centre Juelich, Juelich, Germany.,Institute for Biomedical Engineering and Computer Science, Technische Universität Ilmenau, Ilmenau, Germany
| | - Vincent Gras
- Institute of Neuroscience and Medicine (INM-4), Research Centre Juelich, Juelich, Germany
| | - Dagmar Timmann
- Department of Neurology, Essen University Hospital, University of Duisburg-Essen, Essen, Germany
| | - Matthis Synofzik
- Department of Neurodegenerative Diseases, Center for Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Alejandro Giorgetti
- Computational Biophysics, German Research School for Simulation Sciences, and Computational Biomedicine, Institute for Advanced Simulation (IAS-5) and Institute of Neuroscience and Medicine (INM-9), Research Centre Juelich, Juelich, Germany.,Department of Biotechnology, University of Verona, Verona, 37134, Italy
| | - Paolo Carloni
- Computational Biophysics, German Research School for Simulation Sciences, and Computational Biomedicine, Institute for Advanced Simulation (IAS-5) and Institute of Neuroscience and Medicine (INM-9), Research Centre Juelich, Juelich, Germany
| | - Jon N Shah
- Institute of Neuroscience and Medicine (INM-4), Research Centre Juelich, Juelich, Germany.,Department of Neurology, Faculty of Medicine, JARA, RWTH Aachen University, Aachen, Germany
| | - Ludger Schöls
- Department of Neurodegenerative Diseases, Center for Neurology, Hertie-Institute for Clinical Brain Research, University of Tübingen, Tübingen, Germany.,German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany
| | - Ute Kopp
- Klinik und Hochschulambulanz für Neurologie, Charité -Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Lisa Bußenius
- Institute of Neuroscience and Medicine (INM-1), Research Centre Juelich, Juelich, Germany.,Institute for Biochemistry and Molecular Cell Biology, Center for Experimental Medicine, University Clinic Hamburg Eppendorf, Hamburg, Germany
| | - Timm Oberwahrenbrock
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health Berlin, Berlin, Germany
| | - Hanna Zimmermann
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health Berlin, Berlin, Germany
| | - Caspar Pfueller
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health Berlin, Berlin, Germany
| | - Ella-Maria Kadas
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health Berlin, Berlin, Germany
| | - Maria Rönnefarth
- Klinik und Hochschulambulanz für Neurologie, Charité -Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Anne-Sophie Grosch
- Klinik und Hochschulambulanz für Neurologie, Charité -Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Matthias Endres
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health Berlin, Berlin, Germany.,Klinik und Hochschulambulanz für Neurologie, Charité -Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany.,Center for Stroke Research Berlin (CSB), Charité - Universitätsmedizin Berlin, Berlin, Germany.,German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,German Centre for Cardiovascular Research (DZHK), Berlin, Germany
| | - Katrin Amunts
- Institute of Neuroscience and Medicine (INM-1), Research Centre Juelich, Juelich, Germany.,C. and O. Vogt Institute for Brain Research, Medical Faculty, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Friedemann Paul
- NeuroCure Clinical Research Center, Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health Berlin, Berlin, Germany.,Experimental and Clinical Research Center, Max Delbrueck Center for Molecular Medicine and Charité - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany.,Klinik und Hochschulambulanz für Neurologie, Charité -Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany
| | - Sarah Doss
- Klinik und Hochschulambulanz für Neurologie, Charité -Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, Berlin Institute of Health, Berlin, Germany.,Movement Disorders Section, Department of Neurological Sciences, University of Nebraska Medical Center, Omaha, NE, USA
| | - Martina Minnerop
- Institute of Neuroscience and Medicine (INM-1), Research Centre Juelich, Juelich, Germany.,Department of Neurology, Center for Movement Disorders and Neuromodulation, Medical Faculty, Heinrich Heine University, Düsseldorf, Germany.,Institute of Clinical Neuroscience and Medical Psychology, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
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A New Mouse Model Related to SCA14 Carrying a Pseudosubstrate Domain Mutation in PKCγ Shows Perturbed Purkinje Cell Maturation and Ataxic Motor Behavior. J Neurosci 2021; 41:2053-2068. [PMID: 33478986 PMCID: PMC7939089 DOI: 10.1523/jneurosci.1946-20.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 01/12/2021] [Accepted: 01/12/2021] [Indexed: 01/15/2023] Open
Abstract
Spinocerebellar ataxias (SCAs) are diseases characterized by cerebellar atrophy and loss of Purkinje neurons caused by mutations in diverse genes. In SCA14, the disease is caused by point mutations or small deletions in protein kinase C γ (PKCγ), a crucial signaling protein in Purkinje cells. It is still unclear whether increased or decreased PKCγ activity may be involved in the SCA14 pathogenesis. In this study, we present a new knock-in mouse model related to SCA14 with a point mutation in the pseudosubstrate domain, PKCγ-A24E, known to induce a constitutive PKCγ activation. In this protein conformation, the kinase domain of PKCγ is activated, but at the same time the protein is subject to dephosphorylation and protein degradation. As a result, we find a dramatic reduction of PKCγ protein expression in PKCγ-A24E mice of either sex. Despite this reduction, there is clear evidence for an increased PKC activity in Purkinje cells from PKCγ-A24E mice. Purkinje cells derived from PKCγ-A24E have short thickened dendrites typical for PKC activation. These mice also develop a marked ataxia and signs of Purkinje cell dysfunction making them an interesting new mouse model related to SCA. Recently, a similar mutation in a human patient was discovered and found to be associated with overt SCA14. RNA profiling of PKCγ-A24E mice showed a dysregulation of related signaling pathways, such as mGluR1 or mTOR. Our results show that the induction of PKCγ activation in Purkinje cells results in the SCA-like phenotype indicating PKC activation as one pathogenetic avenue leading to a SCA.SIGNIFICANCE STATEMENT Spinocerebellar ataxias (SCAs) are hereditary diseases affecting cerebellar Purkinje cells and are a one of neurodegenerative diseases. While mutation in several genes have been identified as causing SCAs, it is unclear how these mutations cause the disease phenotype. Mutations in PKCγ cause one subtype of SCAs, SCA14. In this study, we have generated a knock-in mouse with a mutation in the pseudosubstrate domain of PKCγ, which keeps PKCγ in the constitutive active open conformation. We show that this mutation leading to a constant activation of PKCγ results in a SCA-like phenotype in these mice. Our findings establish the constant activation of PKC signaling as one pathogenetic avenue leading to an SCA phenotype and a mechanism causing a neurodegenerative disease.
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Li T, Hu J, Wang S, Zhang H. Super-variants identification for brain connectivity. Hum Brain Mapp 2020; 42:1304-1312. [PMID: 33236465 PMCID: PMC7927294 DOI: 10.1002/hbm.25294] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 10/25/2020] [Accepted: 11/12/2020] [Indexed: 12/17/2022] Open
Abstract
Identifying genetic biomarkers for brain connectivity helps us understand genetic effects on brain function. The unique and important challenge in detecting associations between brain connectivity and genetic variants is that the phenotype is a matrix rather than a scalar. We study a new concept of super‐variant for genetic association detection. Similar to but different from the classic concept of gene, a super‐variant is a combination of alleles in multiple loci but contributing loci can be anywhere in the genome. We hypothesize that the super‐variants are easier to detect and more reliable to reproduce in their associations with brain connectivity. By applying a novel ranking and aggregation method to the UK Biobank databases, we discovered and verified several replicable super‐variants. Specifically, we investigate a discovery set with 16,421 subjects and a verification set with 2,882 subjects, where they are formed according to release date, and the verification set is used to validate the genetic associations from the discovery phase. We identified 12 replicable super‐variants on Chromosomes 1, 3, 7, 8, 9, 10, 12, 15, 16, 18, and 19. These verified super‐variants contain single nucleotide polymorphisms that locate in 14 genes which have been reported to have association with brain structure and function, and/or neurodevelopmental and neurodegenerative disorders in the literature. We also identified novel loci in genes RSPO2 and TMEM74 which may be upregulated in brain issues. These findings demonstrate the validity of the super‐variants and its capability of unifying existing results as well as discovering novel and replicable results.
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Affiliation(s)
- Ting Li
- Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut, USA
| | - Jianchang Hu
- Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut, USA
| | - Shiying Wang
- Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut, USA
| | - Heping Zhang
- Department of Biostatistics, Yale University School of Public Health, New Haven, Connecticut, USA
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Winkler SC, Shimobayashi E, Kapfhammer JP. PKCγ-Mediated Phosphorylation of CRMP2 Regulates Dendritic Outgrowth in Cerebellar Purkinje Cells. Mol Neurobiol 2020; 57:5150-5166. [PMID: 32860158 PMCID: PMC7541385 DOI: 10.1007/s12035-020-02038-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/22/2020] [Indexed: 11/02/2022]
Abstract
The signalling protein PKCγ is a major regulator of Purkinje cell development and synaptic function. We have shown previously that increased PKCγ activity impairs dendritic development of cerebellar Purkinje cells. Mutations in the protein kinase Cγ gene (PRKCG) cause spinocerebellar ataxia type 14 (SCA14). In a transgenic mouse model of SCA14 expressing the human S361G mutation, Purkinje cell dendritic development is impaired in cerebellar slice cultures similar to pharmacological activation of PKC. The mechanisms of PKCγ-driven inhibition of dendritic growth are still unclear. Using immunoprecipitation-coupled mass spectrometry analysis, we have identified collapsin response mediator protein 2 (CRMP2) as a protein interacting with constitutive active PKCγ(S361G) and confirmed the interaction with the Duolink™ proximity ligation assay. We show that in cerebellar slice cultures from PKCγ(S361G)-mice, phosphorylation of CRMP2 at the known PKC target site Thr555 is increased in Purkinje cells confirming phosphorylation of CRMP2 by PKCγ. miRNA-mediated CRMP2 knockdown decreased Purkinje cell dendritic outgrowth in dissociated cerebellar cultures as did the transfection of CRMP2 mutants with a modified Thr555 site. In contrast, dendritic development was normal after wild-type CRMP2 overexpression. In a novel knock-in mouse expressing only the phospho-defective T555A-mutant CRMP2, Purkinje cell dendritic development was reduced in dissociated cultures. This reduction could be rescued by transfecting wild-type CRMP2 but only partially by the phospho-mimetic T555D-mutant. Our findings establish CRMP2 as an important target of PKCγ phosphorylation in Purkinje cells mediating its control of dendritic development. Dynamic regulation of CRMP2 phosphorylation via PKCγ is required for its correct function.
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Affiliation(s)
- Sabine C Winkler
- Anatomical Institute, Department of Biomedicine, University of Basel, Pestalozzistrasse 20, CH - 4056, Basel, Switzerland
| | - Etsuko Shimobayashi
- Anatomical Institute, Department of Biomedicine, University of Basel, Pestalozzistrasse 20, CH - 4056, Basel, Switzerland
| | - Josef P Kapfhammer
- Anatomical Institute, Department of Biomedicine, University of Basel, Pestalozzistrasse 20, CH - 4056, Basel, Switzerland.
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