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Mair D, Biskup S, Kress W, Abicht A, Brück W, Zechel S, Knop KC, Koenig FB, Tey S, Nikolin S, Eggermann K, Kurth I, Ferbert A, Weis J. Differential diagnosis of vacuolar myopathies in the NGS era. Brain Pathol 2020; 30:877-896. [PMID: 32419263 PMCID: PMC8017999 DOI: 10.1111/bpa.12864] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Revised: 04/10/2020] [Accepted: 05/07/2020] [Indexed: 12/12/2022] Open
Abstract
Altered autophagy accompanied by abnormal autophagic (rimmed) vacuoles detectable by light and electron microscopy is a common denominator of many familial and sporadic non-inflammatory muscle diseases. Even in the era of next generation sequencing (NGS), late-onset vacuolar myopathies remain a diagnostic challenge. We identified 32 adult vacuolar myopathy patients from 30 unrelated families, studied their clinical, histopathological and ultrastructural characteristics and performed genetic testing in index patients and relatives using Sanger sequencing and NGS including whole exome sequencing (WES). We established a molecular genetic diagnosis in 17 patients. Pathogenic mutations were found in genes typically linked to vacuolar myopathy (GNE, LDB3/ZASP, MYOT, DES and GAA), but also in genes not regularly associated with severely altered autophagy (FKRP, DYSF, CAV3, COL6A2, GYG1 and TRIM32) and in the digenic facioscapulohumeral muscular dystrophy 2. Characteristic histopathological features including distinct patterns of myofibrillar disarray and evidence of exocytosis proved to be helpful to distinguish causes of vacuolar myopathies. Biopsy validated the pathogenicity of the novel mutations p.(Phe55*) and p.(Arg216*) in GYG1 and of the p.(Leu156Pro) TRIM32 mutation combined with compound heterozygous deletion of exon 2 of TRIM32 and expanded the phenotype of Ala93Thr-caveolinopathy and of limb-girdle muscular dystrophy 2i caused by FKRP mutation. In 15 patients no causal variants were detected by Sanger sequencing and NGS panel analysis. In 12 of these cases, WES was performed, but did not yield any definite mutation or likely candidate gene. In one of these patients with a family history of muscle weakness, the vacuolar myopathy was eventually linked to chloroquine therapy. Our study illustrates the wide phenotypic and genotypic heterogeneity of vacuolar myopathies and validates the role of histopathology in assessing the pathogenicity of novel mutations detected by NGS. In a sizable portion of vacuolar myopathy cases, it remains to be shown whether the cause is hereditary or degenerative.
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Affiliation(s)
- Dorothea Mair
- Institute of Neuropathology, RWTH Aachen University, Aachen, Germany.,Department of Neurology, Kassel School of Medicine, Klinikum Kassel, Kassel, Germany.,University of Southampton, Southampton, UK
| | - Saskia Biskup
- Centre for Genomics and Transcriptomics CeGaT, Tübingen, Germany
| | - Wolfram Kress
- Institute of Human Genetics, University Würzburg, Würzburg, Germany
| | | | - Wolfgang Brück
- Institute of Neuropathology, Göttingen University, Göttingen, Germany
| | - Sabrina Zechel
- Institute of Neuropathology, Göttingen University, Göttingen, Germany
| | | | | | - Shelisa Tey
- Institute of Neuropathology, RWTH Aachen University, Aachen, Germany
| | - Stefan Nikolin
- Institute of Neuropathology, RWTH Aachen University, Aachen, Germany
| | - Katja Eggermann
- Institute of Human Genetics, RWTH Aachen University, Aachen, Germany
| | - Ingo Kurth
- Institute of Human Genetics, RWTH Aachen University, Aachen, Germany
| | - Andreas Ferbert
- Department of Neurology, Kassel School of Medicine, Klinikum Kassel, Kassel, Germany
| | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University, Aachen, Germany
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Roos A, Hathazi D, Schara U. Immunofluorescence-Based Analysis of Caveolin-3 in the Diagnostic Management of Neuromuscular Diseases. Methods Mol Biol 2020; 2169:197-216. [PMID: 32548831 DOI: 10.1007/978-1-0716-0732-9_18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Immunohistochemistry- and/or immunofluorescence-based analysis of muscular proteins represents a standard procedure in the diagnostic management of patients suffering from neuromuscular diseases such as "Caveolinopathies" which are caused by mutations in the CAV3 gene encoding for caveolin-3. Human caveolin-3 is a 151 amino acid sized transmembrane protein localized within caveolae, predominantly expressed in cardiac and skeletal muscle cells and involved in a diversity of cellular functions crucial for muscle cell homeostasis. Loss of caveolin-3 protein abundance is indicative for the presence of pathogenic mutations within the corresponding gene and thus for the diagnosis of "Caveolinopathies." Moreover, description of abnormal immunoreactivity findings for the caveolin-3 protein is increasing in the context of other neuromuscular diseases suggesting that profound knowledge of abnormal caveolin-3-expression and/or distribution findings can be decisive also for the diagnosis of other neurological diseases as well as for a better understanding of the biology of the protein. Here, we summarize the current knowledge about the caveolin-3, report on a protocol for immunofluorescence-based analysis of the protein in the diagnostic workup of neuromuscular patients-also considering problems encountered-and confirm as well as summarize already published abnormal histological findings in muscular pathologies beyond "Caveolinopathies."
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Affiliation(s)
- Andreas Roos
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, Centre for Neuromuscular Disorders in Children, University Hospital Essen, University of Duisburg-Essen, Essen, Germany.
| | - Denisa Hathazi
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK
| | - Ulrike Schara
- Department of Neuropediatrics, Developmental Neurology and Social Pediatrics, Centre for Neuromuscular Disorders in Children, University Hospital Essen, University of Duisburg-Essen, Essen, Germany
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3
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Dystrophy-associated caveolin-3 mutations reveal that caveolae couple IL6/STAT3 signaling with mechanosensing in human muscle cells. Nat Commun 2019; 10:1974. [PMID: 31036801 PMCID: PMC6488599 DOI: 10.1038/s41467-019-09405-5] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 02/27/2019] [Indexed: 12/14/2022] Open
Abstract
Caveolin-3 is the major structural protein of caveolae in muscle. Mutations in the CAV3 gene cause different types of myopathies with altered membrane integrity and repair, expression of muscle proteins, and regulation of signaling pathways. We show here that myotubes from patients bearing the CAV3 P28L and R26Q mutations present a dramatic decrease of caveolae at the plasma membrane, resulting in abnormal response to mechanical stress. Mutant myotubes are unable to buffer the increase in membrane tension induced by mechanical stress. This results in impaired regulation of the IL6/STAT3 signaling pathway leading to its constitutive hyperactivation and increased expression of muscle genes. These defects are fully reversed by reassembling functional caveolae through expression of caveolin-3. Our study reveals that under mechanical stress the regulation of mechanoprotection by caveolae is directly coupled with the regulation of IL6/STAT3 signaling in muscle cells and that this regulation is absent in Cav3-associated dystrophic patients. Caveolae are mechanosensors and mutations of their coat proteins are implicated in muscle disorders, but molecular mechanisms are unclear. Here, the authors show that caveolae can regulate IL6/STAT3 signaling in muscle cells under stress, and that dystrophy related Cav3 mutant myotubes have reduced caveolae and upregulated IL6 signaling.
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González Coraspe JA, Weis J, Anderson ME, Münchberg U, Lorenz K, Buchkremer S, Carr S, Zahedi RP, Brauers E, Michels H, Sunada Y, Lochmüller H, Campbell KP, Freier E, Hathazi D, Roos A. Biochemical and pathological changes result from mutated Caveolin-3 in muscle. Skelet Muscle 2018; 8:28. [PMID: 30153853 PMCID: PMC6114045 DOI: 10.1186/s13395-018-0173-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2018] [Accepted: 07/24/2018] [Indexed: 12/16/2022] Open
Abstract
Background Caveolin-3 (CAV3) is a muscle-specific protein localized to the sarcolemma. It was suggested that CAV3 is involved in the connection between the extracellular matrix (ECM) and the cytoskeleton. Caveolinopathies often go along with increased CK levels indicative of sarcolemmal damage. So far, more than 40 dominant pathogenic mutations have been described leading to several phenotypes many of which are associated with a mis-localization of the mutant protein to the Golgi. Golgi retention and endoplasmic reticulum (ER) stress has been demonstrated for the CAV3 p.P104L mutation, but further downstream pathophysiological consequences remained elusive so far. Methods We utilized a transgenic (p.P104L mutant) mouse model and performed proteomic profiling along with immunoprecipitation, immunofluorescence and immunoblot examinations (including examination of α-dystroglycan glycosylation), and morphological studies (electron and coherent anti-Stokes Raman scattering (CARS) microscopy) in a systematic investigation of molecular and subcellular events in p.P104L caveolinopathy. Results Our electron and CARS microscopic as well as immunological studies revealed Golgi and ER proliferations along with a build-up of protein aggregates further characterized by immunoprecipitation and subsequent mass spectrometry. Molecular characterization these aggregates showed affection of mitochondrial and cytoskeletal proteins which accords with our ultra-structural findings. Additional global proteomic profiling revealed vulnerability of 120 proteins in diseased quadriceps muscle supporting our previous findings and providing more general insights into the underlying pathophysiology. Moreover, our data suggested that further DGC components are altered by the perturbed protein processing machinery but are not prone to form aggregates whereas other sarcolemmal proteins are ubiquitinated or bind to p62. Although the architecture of the ER and Golgi as organelles of protein glycosylation are altered, the glycosylation of α-dystroglycan presented unchanged. Conclusions Our combined data classify the p.P104 caveolinopathy as an ER-Golgi disorder impairing proper protein processing and leading to aggregate formation pertaining proteins important for mitochondrial function, cytoskeleton, ECM remodeling and sarcolemmal integrity. Glycosylation of sarcolemmal proteins seems to be normal. The new pathophysiological insights might be of relevance for the development of therapeutic strategies for caveolinopathy patients targeting improved protein folding capacity. Electronic supplementary material The online version of this article (10.1186/s13395-018-0173-y) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University Hospital, Pauwelsstr. 30, 52074, Aachen, Germany
| | - Mary E Anderson
- Howard Hughes Medical Institute, Departments of Molecular Physiology and Biophysics, of Neurology, University of Iowa, Iowa City, IA, 52242, USA
| | - Ute Münchberg
- Biomedical Research Department, Tissue Omics group, Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Otto-Hahn-Str. 6b, 44227, Dortmund, Germany
| | - Kristina Lorenz
- Biomedical Research Department, Tissue Omics group, Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Otto-Hahn-Str. 6b, 44227, Dortmund, Germany
| | - Stephan Buchkremer
- Institute of Neuropathology, RWTH Aachen University Hospital, Pauwelsstr. 30, 52074, Aachen, Germany
| | - Stephanie Carr
- Institute of Genetic Medicine, International Centre for Life, Central Parkway, Newcastle upon Tyne, England, UK
| | - René Peiman Zahedi
- Biomedical Research Department, Tissue Omics group, Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Otto-Hahn-Str. 6b, 44227, Dortmund, Germany.,Gerald Bronfman Department of Oncology, Jewish General Hospital, McGill University, Montreal, Quebec, H4A 3T2, Canada.,Segal Cancer Proteomics Centre, Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Quebec, H3T 1E2, Canada
| | - Eva Brauers
- Institute of Neuropathology, RWTH Aachen University Hospital, Pauwelsstr. 30, 52074, Aachen, Germany
| | - Hannah Michels
- Institute of Genetic Medicine, International Centre for Life, Central Parkway, Newcastle upon Tyne, England, UK
| | - Yoshihide Sunada
- Department of Neurology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan
| | - Hanns Lochmüller
- Institute of Genetic Medicine, International Centre for Life, Central Parkway, Newcastle upon Tyne, England, UK.,Department of Neuropediatrics and Muscle Disorders, Medical Center - University of Freiburg, Faculty of Medicine, Freiburg, Germany.,Centro Nacional de Análisis Genómico (CNAG-CRG), Center for Genomic Regulation, Barcelona Institute of Science and Technology (BIST), Barcelona, Catalonia, Spain.,Children's Hospital of Eastern Ontario Research Institute, University of Ottawa, Ottawa, Canada and Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, Canada
| | - Kevin P Campbell
- Howard Hughes Medical Institute, Departments of Molecular Physiology and Biophysics, of Neurology, University of Iowa, Iowa City, IA, 52242, USA
| | - Erik Freier
- Biomedical Research Department, Tissue Omics group, Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Otto-Hahn-Str. 6b, 44227, Dortmund, Germany
| | - Denisa Hathazi
- Biomedical Research Department, Tissue Omics group, Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Otto-Hahn-Str. 6b, 44227, Dortmund, Germany
| | - Andreas Roos
- Biomedical Research Department, Tissue Omics group, Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V, Otto-Hahn-Str. 6b, 44227, Dortmund, Germany.
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5
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Tracking Effects of SIL1 Increase: Taking a Closer Look Beyond the Consequences of Elevated Expression Level. Mol Neurobiol 2017; 55:2524-2546. [PMID: 28401474 DOI: 10.1007/s12035-017-0494-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 03/14/2017] [Indexed: 12/31/2022]
Abstract
SIL1 acts as a co-chaperone for the major ER-resident chaperone BiP and thus plays a role in many BiP-dependent cellular functions such as protein-folding control and unfolded protein response. Whereas the increase of BiP upon cellular stress conditions is a well-known phenomenon, elevation of SIL1 under stress conditions was thus far solely studied in yeast, and different studies indicated an adverse effect of SIL1 increase. This is seemingly in contrast with the beneficial effect of SIL1 increase in surviving neurons in neurodegenerative disorders such as amyotrophic lateral sclerosis and Alzheimer's disease. Here, we addressed these controversial findings. Applying cell biological, morphological and biochemical methods, we demonstrated that SIL1 increases in various mammalian cells and neuronal tissues upon cellular stress. Investigation of heterozygous SIL1 mutant cells and tissues supported this finding. Moreover, SIL1 protein was found to be stabilized during ER stress. Increased SIL1 initiates ER stress in a concentration-dependent manner which agrees with the described adverse SIL1 effect. However, our results also suggest that protective levels are achieved by the secretion of excessive SIL1 and GRP170 and that moderately increased SIL1 also ameliorates cellular fitness under stress conditions. Our immunoprecipitation results indicate that SIL1 might act in a BiP-independent manner. Proteomic studies showed that SIL1 elevation alters the expression of proteins including crucial players in neurodegeneration, especially in Alzheimer's disease. This finding agrees with our observation of increased SIL1 immunoreactivity in surviving neurons of Alzheimer's disease autopsy cases and supports the assumption that SIL1 plays a protective role in neurodegenerative disorders.
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6
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Transactivation of the epidermal growth factor receptor in responses to myocardial stress and cardioprotection. Int J Biochem Cell Biol 2017; 83:97-110. [DOI: 10.1016/j.biocel.2016.12.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 12/25/2016] [Accepted: 12/26/2016] [Indexed: 12/20/2022]
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7
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Brauers E, Roos A, Kollipara L, Zahedi RP, Beckmann A, Mohanadas N, Bauer H, Häusler M, Thoma S, Kress W, Senderek J, Weis J. The Caveolin-3 G56S sequence variant of unknown significance: Muscle biopsy findings and functional cell biological analysis. Proteomics Clin Appl 2016; 11. [PMID: 27739254 PMCID: PMC5248598 DOI: 10.1002/prca.201600007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 08/09/2016] [Accepted: 10/11/2016] [Indexed: 12/31/2022]
Abstract
Purpose In the era of next‐generation sequencing, we are increasingly confronted with sequence variants of unknown significance. This phenomenon is also known for variations in Caveolin‐3 and can complicate the molecular diagnosis of the disease. Here, we aimed to study the ambiguous character of the G56S Caveolin‐3 variant. Experimental design A comprehensive approach combining genetic and morphological studies of muscle derived from carriers of the G56S Caveolin‐3 variant were carried out and linked to biochemical assays (including phosphoblot studies and proteome profiling) and morphological investigations of cultured myoblasts. Results Muscles showed moderate chronic myopathic changes in all carriers of the variant. Myogenic RCMH cells expressing the G56S Caveolin‐3 protein presented irregular Caveolin‐3 deposits within the Golgi in addition to a regular localization of the protein to the plasma membrane. This result was associated with abnormal findings on the ultra‐structural level. Phosphoblot studies revealed that G56S affects EGFR‐signaling. Proteomic profiling demonstrated alterations in levels of physiologically relevant proteins which are indicative for antagonization of G56S Caveolin‐3 expression. Remarkably, some proteomic alterations were enhanced by osmotic/mechanical stress. Conclusions and clinical relevance Our studies suggest that G56S might influence the manifestation of myopathic changes upon the presence of additional cellular stress burden. Results of our studies moreover improve the current understanding of (genetic) causes of myopathic disorders classified as caveolinopathies.
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Affiliation(s)
- Eva Brauers
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany
| | - Andreas Roos
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany.,Leibniz-Institut für Analytische Wissenschaften - ISAS e.V, Dortmund, Germany
| | | | - René P Zahedi
- Leibniz-Institut für Analytische Wissenschaften - ISAS e.V, Dortmund, Germany
| | - Alf Beckmann
- Medizinisches Versorgungszentrum Dr. Eberhard und Partner, Dortmund, Germany
| | - Nilane Mohanadas
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany
| | - Hartmut Bauer
- Department of Neurology, Marien-Hospital, Euskirchen, Germany
| | - Martin Häusler
- Department of Pediatrics, RWTH Aachen University Hospital, Aachen, Germany
| | | | - Wolfram Kress
- Institute of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Jan Senderek
- Friedrich-Baur-Institut, Neurologische Klinik und Poliklinik, Ludwig-Maximilians-University, München, Germany
| | - Joachim Weis
- Institute of Neuropathology, RWTH Aachen University Hospital, Aachen, Germany
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Stavusis J, Inashkina I, Jankevics E, Radovica I, Micule I, Strautmanis J, Naudina MS, Utkus A, Burnyte B, Lace B. CAV3 gene sequence variations: National Genome Database and clinics. Acta Neurol Scand 2015; 132:185-90. [PMID: 25630502 DOI: 10.1111/ane.12369] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/25/2014] [Indexed: 02/05/2023]
Abstract
INTRODUCTION Caveolinopathies are a group of untreatable, degenerative muscle diseases associated with caveolin 3 (CAV3) gene mutations. OBJECTIVES The goal of this study was to characterize the role of the CAV3 gene in patients with limb-girdle muscular dystrophy, hyperCKemia, cardiomyopathies, as well as utilization of the National Genome Database in clinical applications. MATERIALS AND METHODS We sequenced the coding region and exon/intron boundaries of CAV3 gene in 81 neuromuscular disorder patients, a sample group from the National Genome Database, consisting of 97 individuals with cardiomyopathies, and also random selection of 100 persons. Immunohistochemical staining of muscle biopsy was performed to verify findings in one case, as the setup for the project was to use less invasive molecular biology methods. RESULTS We identified three novel sequence variations (c.183C>G, p.S61R; c.220C>A, p.R74S; c.220C>T, p.R74C) and found evidence that one was associated with hypercreatine kinase-emia. Two previously reported mutations in families with limb-girdle muscular dystrophy were found. No mutations were identified in the cohort of patients with cardiomyopathies. DISCUSSION CAV3 gene encodes muscle-specific protein with dominant negative type of missense mutations in it causing various phenotypes. Our study confirmed CAV3 gene involvement in neuromuscular disorders, but found no evidence in the group of patients with cardiomyopathies. Persons included in the National Genome Database could be screened for late onset Mendelian diseases.
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Affiliation(s)
- J. Stavusis
- Latvian Biomedical Research and Study Center; Riga Latvia
| | - I. Inashkina
- Latvian Biomedical Research and Study Center; Riga Latvia
| | - E. Jankevics
- Latvian Biomedical Research and Study Center; Riga Latvia
| | - I. Radovica
- Latvian Biomedical Research and Study Center; Riga Latvia
| | - I. Micule
- Latvian Biomedical Research and Study Center; Riga Latvia
| | - J. Strautmanis
- Latvian Biomedical Research and Study Center; Riga Latvia
| | - M. S. Naudina
- Latvian Biomedical Research and Study Center; Riga Latvia
| | - A. Utkus
- Department of Human and Medical Genetics; Faculty of Medicine; Vilnius University; Vilnius Lithuania
- Centre for Medical Genetics; Vilnius University Hospital Santariškių Klinikos; Vilnius Lithuania
| | - B. Burnyte
- Department of Human and Medical Genetics; Faculty of Medicine; Vilnius University; Vilnius Lithuania
- Centre for Medical Genetics; Vilnius University Hospital Santariškių Klinikos; Vilnius Lithuania
| | - B. Lace
- Latvian Biomedical Research and Study Center; Riga Latvia
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Vollrath JT, Sechi A, Dreser A, Katona I, Wiemuth D, Vervoorts J, Dohmen M, Chandrasekar A, Prause J, Brauers E, Jesse CM, Weis J, Goswami A. Loss of function of the ALS protein SigR1 leads to ER pathology associated with defective autophagy and lipid raft disturbances. Cell Death Dis 2014; 5:e1290. [PMID: 24922074 PMCID: PMC4611717 DOI: 10.1038/cddis.2014.243] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2014] [Revised: 04/01/2014] [Accepted: 04/17/2014] [Indexed: 12/12/2022]
Abstract
Intracellular accumulations of altered, misfolded proteins in neuronal and other cells are pathological hallmarks shared by many neurodegenerative diseases including amyotrophic lateral sclerosis (ALS). Mutations in several genes give rise to familial forms of ALS. Mutations in Sigma receptor 1 have been found to cause a juvenile form of ALS and frontotemporal lobar degeneration (FTLD). We recently described altered localization, abnormal modification and loss of function of SigR1 in sporadic ALS. In order to further elucidate the molecular mechanisms underlying SigR1-mediated alterations in sporadic and familial ALS, we extended our previous studies using neuronal SigR1 knockdown cell lines. We found that loss of SigR1 leads to abnormal ER morphology, mitochondrial abnormalities and impaired autophagic degradation. Consistent with these results, we found that endosomal trafficking of EGFR is impaired upon SigR1 knockdown. Furthermore, in SigR1-deficient cells the transport of vesicular stomatitis virus glycoprotein is inhibited, leading to the accumulation of this cargo protein in the Golgi apparatus. Moreover, depletion of SigR1 destabilized lipid rafts and associated calcium mobilization, confirming the crucial role of SigR1 in lipid raft and intracellular calcium homeostasis. Taken together, our results support the notion that loss of SigR1 function contributes to ALS pathology by causing abnormal ER morphology, lipid raft destabilization and defective endolysosomal pathways.
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Affiliation(s)
- J T Vollrath
- Institute of Neuropathology, Uniklinik RWTH Aachen and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
| | - A Sechi
- Institute of Biomedical Engineering and Cell Biology, RWTH Aachen University and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
| | - A Dreser
- Institute of Neuropathology, Uniklinik RWTH Aachen and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
| | - I Katona
- Institute of Neuropathology, Uniklinik RWTH Aachen and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
| | - D Wiemuth
- Institute of Physiology, RWTH Aachen University, Pauwelsstraße 30, Aachen 52074, Germany
| | - J Vervoorts
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, Pauwelsstraße 30, Aachen 52074, Germany
| | - M Dohmen
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, Pauwelsstraße 30, Aachen 52074, Germany
| | - A Chandrasekar
- Institute of Neuropathology, Uniklinik RWTH Aachen and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
| | - J Prause
- Institute of Neuropathology, Uniklinik RWTH Aachen and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
| | - E Brauers
- Institute of Neuropathology, Uniklinik RWTH Aachen and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
| | - C M Jesse
- Institute of Neuropathology, Uniklinik RWTH Aachen and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
| | - J Weis
- Institute of Neuropathology, Uniklinik RWTH Aachen and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
| | - A Goswami
- Institute of Neuropathology, Uniklinik RWTH Aachen and JARA Brain Translational Medicine, Pauwelsstraße 30, Aachen 52074, Germany
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Schreckenbach T, Henn W, Kress W, Roos A, Maschke M, Feiden W, Dillmann U, Schulz JB, Weis J, Claeys KG. NovelFHL1mutation in a family with reducing body myopathy. Muscle Nerve 2012; 47:127-34. [DOI: 10.1002/mus.23500] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2012] [Indexed: 11/06/2022]
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11
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Liu YW, Lukiyanchuk V, Schmid SL. Common membrane trafficking defects of disease-associated dynamin 2 mutations. Traffic 2011; 12:1620-33. [PMID: 21762456 DOI: 10.1111/j.1600-0854.2011.01250.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Dynamin (Dyn) is a multidomain and multifunctional GTPase best known for its essential role in clathrin-mediated endocytosis (CME). Dyn2 mutations have been linked to two human diseases, centronuclear myopathy (CNM) and Charcot-Marie-Tooth (CMT) disease. Paradoxically, although Dyn2 is ubiquitously expressed and essential for embryonic development, the disease-associated Dyn2 mutants are autosomal dominant, but result in slowly progressing and tissue-specific diseases. Thus, although the cellular defects that cause disease remain unclear, they are expected to be mild. To gain new insight into potential pathogenic mechanisms, we utilized mouse Dyn2 conditional knockout cells combined with retroviral-mediated reconstitution to mimic both heterozygous and homozygous states and characterized cellular phenotypes using quantitative assays for several membrane trafficking events. Surprisingly, none of the four mutants studied exhibited a defect in CME, but all were impaired in their ability to support p75/neurotrophin receptor export from the Golgi, the raft-dependent endocytosis of cholera toxin and the clathrin-independent endocytosis of epidermal growth factor receptor (EGFR). While it will be important to study these mutants in disease-relevant muscle and neuronal cells, given the importance of neurotrophic factors and lipid rafts in muscle physiology, we speculate that these common cellular defects might contribute to the tissue-specific diseases caused by a ubiquitously expressed protein.
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Affiliation(s)
- Ya-Wen Liu
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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