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Lalonde R, Strazielle C. The DST gene in neurobiology. J Neurogenet 2023; 37:131-138. [PMID: 38465459 DOI: 10.1080/01677063.2024.2319880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 02/13/2024] [Indexed: 03/12/2024]
Abstract
DST is a gene whose alternative splicing yields epithelial, neuronal, and muscular isoforms. The autosomal recessive Dstdt (dystonia musculorum) spontaneous mouse mutation causes degeneration of spinocerebellar tracts as well as peripheral sensory nerves, dorsal root ganglia, and cranial nerve ganglia. In addition to Dstdt mutants, axonopathy and neurofilament accumulation in perikarya are features of two other murine lines with spontaneous Dst mutations, targeted Dst knockout mice, DstTg4 transgenic mice carrying two deleted Dst exons, DstGt mice with trapped actin-binding domain-containing isoforms, and conditional Schwann cell-specific Dst knockout mice. As a result of nerve damage, Dstdt mutants display dystonia and ataxia, as seen in several genetically modified models and their motor coordination deficits have been quantified along with the spontaneous Dst nonsense mutant, the conditional Schwann cell-specific Dst knockout, the conditional DstGt mutant, and the Dst-b isoform specific Dst mutant. Recent findings in humans have associated DST mutations of the Dst-b isoform with hereditary sensory and autonomic neuropathies type 6 (HSAN-VI). These data should further encourage the development of genetic techniques to treat or prevent ataxic and dystonic symptoms.
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Affiliation(s)
- Robert Lalonde
- Université de Lorraine, Laboratoire Stress, Immunité, Pathogènes (EA7300), Faculté de Médecine, Vandœuvre-les-Nancy, France
| | - Catherine Strazielle
- Université de Lorraine, Laboratoire Stress, Immunité, Pathogènes (EA7300), Faculté de Médecine, Vandœuvre-les-Nancy, France
- CHRU Nancy, Vandœuvre-les-Nancy, France
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2
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Lucas L, Cooper TA. Insights into Cell-Specific Functions of Microtubules in Skeletal Muscle Development and Homeostasis. Int J Mol Sci 2023; 24:ijms24032903. [PMID: 36769228 PMCID: PMC9917663 DOI: 10.3390/ijms24032903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/17/2023] [Accepted: 01/31/2023] [Indexed: 02/05/2023] Open
Abstract
The contractile cells of skeletal muscles, called myofibers, are elongated multinucleated syncytia formed and maintained by the fusion of proliferative myoblasts. Human myofibers can be hundreds of microns in diameter and millimeters in length. Myofibers are non-mitotic, obviating the need for microtubules in cell division. However, microtubules have been adapted to the unique needs of these cells and are critical for myofiber development and function. Microtubules in mature myofibers are highly dynamic, and studies in several experimental systems have demonstrated the requirements for microtubules in the unique features of muscle biology including myoblast fusion, peripheral localization of nuclei, assembly of the sarcomere, transport and signaling. Microtubule-binding proteins have also been adapted to the needs of the skeletal muscle including the expression of skeletal muscle-specific protein isoforms generated by alternative splicing. Here, we will outline the different roles microtubules play in skeletal muscle cells, describe how microtubule abnormalities can lead to muscle disease and discuss the broader implications for microtubule function.
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Affiliation(s)
- Lathan Lucas
- Chemical, Physical, Structural Biology Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Thomas A. Cooper
- Chemical, Physical, Structural Biology Graduate Program, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Pathology & Immunology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Molecular & Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA
- Department of Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
- Correspondence:
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Hochberg Z, Albertsson-Wikland K, Privé F, German A, Holmgren A, Rubin L, Shmoish M. Energy Trade-Off and Four Extreme Human Body Types. J Clin Endocrinol Metab 2022; 108:e89-e97. [PMID: 36413496 DOI: 10.1210/clinem/dgac665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/24/2022] [Accepted: 11/14/2022] [Indexed: 11/23/2022]
Abstract
BACKGROUND Resource trade-off theory suggests that increased performance on a given trait comes at the cost of decreased performance on other traits. METHODS Growth data from 1889 subjects (996 girls) were used from the GrowUp1974 Gothenburg study. Energy Trade-Off (ETO) between height and weight for individuals with extreme body types was characterized using a novel ETO-Score (ETOS). Four extreme body types were defined based on height and ETOI at early adulthood: tall-slender, short-stout, short-slender, and tall-stout; their growth trajectories assessed from ages 0.5-17.5 years.A GWAS using UK BioBank data was conducted to identify gene variants associated with height, BMI, and for the first time with ETOS. RESULTS Height and ETOS trajectories show a two-hit pattern with profound changes during early infancy and at puberty for tall-slender and short-stout body types.Several loci (including FTO, ADCY3, GDF5, ) and pathways were identified by GWAS as being highly associated with ETOS. The most strongly associated pathways were related to 'extracellular matrix', 'signal transduction', 'chromatin organization', and 'energy metabolism'. CONCLUSIONS ETOS represents a novel anthropometric trait with utility in describing body types. We discovered the multiple genomic loci and pathways probably involved in energy trade-off.
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Affiliation(s)
- Ze'ev Hochberg
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
| | - Kerstin Albertsson-Wikland
- Physiology/Endocrinology, Institute of Neuroscience & Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Florian Privé
- National Centre for Register-Based Research, Aarhus University, Aarhus, Denmark
| | - Alina German
- The Ruth and Bruce Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Haifa, Israel
- Pediatric Endocrinology, Haemek Medical Center, Afula, Israel
| | - Anton Holmgren
- Göteborg Pediatric Growth Research Center, Department of Pediatrics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Lisa Rubin
- School of Public Health, University of Haifa, Haifa, Israel
| | - Michael Shmoish
- Bioinformatics Knowledge Unit, The Lokey Center, Technion -Israel Institute of Technology, Haifa, Israel
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4
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Yoshioka N, Kurose M, Yano M, Tran DM, Okuda S, Mori-Ochiai Y, Horie M, Nagai T, Nishino I, Shibata S, Takebayashi H. Isoform-specific mutation in Dystonin-b gene causes late-onset protein aggregate myopathy and cardiomyopathy. eLife 2022; 11:78419. [PMID: 35942699 PMCID: PMC9365387 DOI: 10.7554/elife.78419] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 07/18/2022] [Indexed: 12/03/2022] Open
Abstract
Dystonin (DST), which encodes cytoskeletal linker proteins, expresses three tissue-selective isoforms: neural DST-a, muscular DST-b, and epithelial DST-e. DST mutations cause different disorders, including hereditary sensory and autonomic neuropathy 6 (HSAN-VI) and epidermolysis bullosa simplex; however, etiology of the muscle phenotype in DST-related diseases has been unclear. Because DST-b contains all of the DST-a-encoding exons, known HSAN-VI mutations could affect both DST-a and DST-b isoforms. To investigate the specific function of DST-b in striated muscles, we generated a Dst-b-specific mutant mouse model harboring a nonsense mutation. Dst-b mutant mice exhibited late-onset protein aggregate myopathy and cardiomyopathy without neuropathy. We observed desmin aggregation, focal myofibrillar dissolution, and mitochondrial accumulation in striated muscles, which are common characteristics of myofibrillar myopathy. We also found nuclear inclusions containing p62, ubiquitin, and SUMO proteins with nuclear envelope invaginations as a unique pathological hallmark in Dst-b mutation-induced cardiomyopathy. RNA-sequencing analysis revealed changes in expression of genes responsible for cardiovascular functions. In silico analysis identified DST-b alleles with nonsense mutations in populations worldwide, suggesting that some unidentified hereditary myopathy and cardiomyopathy are caused by DST-b mutations. Here, we demonstrate that the Dst-b isoform is essential for long-term maintenance of striated muscles.
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Affiliation(s)
- Nozomu Yoshioka
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.,Transdisciplinary Research Programs, Niigata University, Niigata, Japan
| | - Masayuki Kurose
- Department of Physiology, School of Dentistry, Iwate Medical University, Iwate, Japan
| | - Masato Yano
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Dang Minh Tran
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Shujiro Okuda
- Medical AI Center, School of Medicine, Niigata University, Niigata, Japan
| | - Yukiko Mori-Ochiai
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Masao Horie
- Department of Nursing, Niigata College of Nursing, Jōetsu, Japan
| | - Toshihiro Nagai
- Electron Microscope Laboratory, Keio University, Tokyo, Japan
| | - Ichizo Nishino
- Department of Neuromuscular Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan
| | - Shinsuke Shibata
- Electron Microscope Laboratory, Keio University, Tokyo, Japan.,Division of Microscopic Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.,Center for Coordination of Research Facilities, Niigata University, Niigata, Japan
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Drp1 overexpression induces desmin disassembling and drives kinesin-1 activation promoting mitochondrial trafficking in skeletal muscle. Cell Death Differ 2020; 27:2383-2401. [PMID: 32042098 PMCID: PMC7370230 DOI: 10.1038/s41418-020-0510-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 12/13/2019] [Accepted: 01/23/2020] [Indexed: 12/15/2022] Open
Abstract
Mitochondria change distribution across cells following a variety of pathophysiological stimuli. The mechanisms presiding over this redistribution are yet undefined. In a murine model overexpressing Drp1 specifically in skeletal muscle, we find marked mitochondria repositioning in muscle fibres and we demonstrate that Drp1 is involved in this process. Drp1 binds KLC1 and enhances microtubule-dependent transport of mitochondria. Drp1-KLC1 coupling triggers the displacement of KIF5B from kinesin-1 complex increasing its binding to microtubule tracks and mitochondrial transport. High levels of Drp1 exacerbate this mechanism leading to the repositioning of mitochondria closer to nuclei. The reduction of Drp1 levels decreases kinesin-1 activation and induces the partial recovery of mitochondrial distribution. Drp1 overexpression is also associated with higher cyclin-dependent kinase-1 (Cdk-1) activation that promotes the persistent phosphorylation of desmin at Ser-31 and its disassembling. Fission inhibition has a positive effect on desmin Ser-31 phosphorylation, regardless of Cdk-1 activation, suggesting that induction of both fission and Cdk-1 are required for desmin collapse. This altered desmin architecture impairs mechanotransduction and compromises mitochondrial network stability priming mitochondria transport through microtubule-dependent trafficking with a mechanism that involves the Drp1-dependent regulation of kinesin-1 complex.
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GWAS for Meat and Carcass Traits Using Imputed Sequence Level Genotypes in Pooled F2-Designs in Pigs. G3-GENES GENOMES GENETICS 2019; 9:2823-2834. [PMID: 31296617 PMCID: PMC6723123 DOI: 10.1534/g3.119.400452] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In order to gain insight into the genetic architecture of economically important traits in pigs and to derive suitable genetic markers to improve these traits in breeding programs, many studies have been conducted to map quantitative trait loci. Shortcomings of these studies were low mapping resolution, large confidence intervals for quantitative trait loci-positions and large linkage disequilibrium blocks. Here, we overcome these shortcomings by pooling four large F2 designs to produce smaller linkage disequilibrium blocks and by resequencing the founder generation at high coverage and the F1 generation at low coverage for subsequent imputation of the F2 generation to whole genome sequencing marker density. This lead to the discovery of more than 32 million variants, 8 million of which have not been previously reported. The pooling of the four F2 designs enabled us to perform a joint genome-wide association study, which lead to the identification of numerous significantly associated variant clusters on chromosomes 1, 2, 4, 7, 17 and 18 for the growth and carcass traits average daily gain, back fat thickness, meat fat ratio, and carcass length. We could not only confirm previously reported, but also discovered new quantitative trait loci. As a result, several new candidate genes are discussed, among them BMP2 (bone morphogenetic protein 2), which we recently discovered in a related study. Variant effect prediction revealed that 15 high impact variants for the traits back fat thickness, meat fat ratio and carcass length were among the statistically significantly associated variants.
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Lindo J, Haas R, Hofman C, Apata M, Moraga M, Verdugo RA, Watson JT, Viviano Llave C, Witonsky D, Beall C, Warinner C, Novembre J, Aldenderfer M, Di Rienzo A. The genetic prehistory of the Andean highlands 7000 years BP though European contact. SCIENCE ADVANCES 2018; 4:eaau4921. [PMID: 30417096 PMCID: PMC6224175 DOI: 10.1126/sciadv.aau4921] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/12/2018] [Indexed: 05/02/2023]
Abstract
The peopling of the Andean highlands above 2500 m in elevation was a complex process that included cultural, biological, and genetic adaptations. Here, we present a time series of ancient whole genomes from the Andes of Peru, dating back to 7000 calendar years before the present (BP), and compare them to 42 new genome-wide genetic variation datasets from both highland and lowland populations. We infer three significant features: a split between low- and high-elevation populations that occurred between 9200 and 8200 BP; a population collapse after European contact that is significantly more severe in South American lowlanders than in highland populations; and evidence for positive selection at genetic loci related to starch digestion and plausibly pathogen resistance after European contact. We do not find selective sweep signals related to known components of the human hypoxia response, which may suggest more complex modes of genetic adaptation to high altitude.
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Affiliation(s)
- John Lindo
- Department of Anthropology, Emory University, Atlanta, GA 30322, USA
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Randall Haas
- Department of Anthropology, University of California, Davis, CA 95616, USA
| | - Courtney Hofman
- Department of Anthropology, University of Oklahoma, Norman, OK 73019, USA
- Laboratories of Molecular Anthropology and Microbiome Research, University of Oklahoma, Norman, OK 73019, USA
| | - Mario Apata
- Programa de Genética Humana, ICBM, Universidad de Chile, Santiago, Chile
| | - Mauricio Moraga
- Programa de Genética Humana, ICBM, Universidad de Chile, Santiago, Chile
- Departamento de Antropología, Universidad de Chile, Santiago, Chile
| | - Ricardo A. Verdugo
- Programa de Genética Humana, ICBM, Universidad de Chile, Santiago, Chile
- Departamento de Oncología Básico-Clínica, Universidad de Chile, Santiago, Chile
| | - James T. Watson
- Arizona State Museum and School of Anthropology, University of Arizona, Tucson, AZ 85721, USA
| | | | - David Witonsky
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Cynthia Beall
- Department of Anthropology, Case Western University, Cleveland, OH 44106, USA
| | - Christina Warinner
- Department of Anthropology, University of Oklahoma, Norman, OK 73019, USA
- Laboratories of Molecular Anthropology and Microbiome Research, University of Oklahoma, Norman, OK 73019, USA
- Department of Archaeogenetics, Max Planck Institute for the Science of Human History, Jena 07745, Germany
| | - John Novembre
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
| | - Mark Aldenderfer
- School of Social Sciences, Humanities, and Arts, University of California, Merced, Merced, CA 95343, USA
| | - Anna Di Rienzo
- Department of Human Genetics, University of Chicago, Chicago, IL 60637, USA
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8
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Voelzmann A, Liew YT, Qu Y, Hahn I, Melero C, Sánchez-Soriano N, Prokop A. Drosophila Short stop as a paradigm for the role and regulation of spectraplakins. Semin Cell Dev Biol 2017; 69:40-57. [DOI: 10.1016/j.semcdb.2017.05.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 05/22/2017] [Accepted: 05/29/2017] [Indexed: 02/07/2023]
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9
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Horie M, Yoshioka N, Takebayashi H. BPAG1 in muscles: Structure and function in skeletal, cardiac and smooth muscle. Semin Cell Dev Biol 2017; 69:26-33. [PMID: 28736206 DOI: 10.1016/j.semcdb.2017.07.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 07/12/2017] [Accepted: 07/14/2017] [Indexed: 01/19/2023]
Abstract
BPAG1, also known as Dystonin or BP230, belongs to the plakin family of proteins, which has multiple cytoskeleton-binding domains. Several BPAG1 isoforms are produced by a single BPAG1 genomic locus using different promoters and exons. For example, BPAG1a, BPAG1b, and BPAG1e are predominantly expressed in the nervous system, muscle, and skin, respectively. Among BPAG1 isoforms, BPAG1e is well studied because it was first identified as an autoantigen in patients with bullous pemphigoid, an autoimmune skin disease. BPAG1e is a component of hemidesmosomes, the adhesion complexes that promote dermal-epidermal cohesion. In the nervous system, the role of BPAG1a is also well studied because disruption of BPAG1a results in a phenotype identical to that of Dystonia musculorum (dt) mutants, which show progressive motor disorder. However, the expression and function of BPAG1 in muscles is not well studied. The aim of this review is to provide an overview of and highlight some recent findings on the expression and function of BPAG1 in muscles, which can assist future studies designed to delineate the role and regulation of BPAG1 in the dt mouse phenotype and in human hereditary sensory and autonomic neuropathy type 6 (HSAN6).
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Affiliation(s)
- Masao Horie
- Division of Neurobiology and Anatomy, Niigata University, Niigata 951-8510, Japan
| | - Nozomu Yoshioka
- Division of Neurobiology and Anatomy, Niigata University, Niigata 951-8510, Japan
| | - Hirohide Takebayashi
- Division of Neurobiology and Anatomy, Niigata University, Niigata 951-8510, Japan.
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Ali A, Hu L, Zhao F, Qiu W, Wang P, Ma X, Zhang Y, Chen L, Qian A. BPAG1, a distinctive role in skin and neurological diseases. Semin Cell Dev Biol 2017. [PMID: 28627382 DOI: 10.1016/j.semcdb.2017.06.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Spectraplakins are multifunctional cytoskeletal linker proteins that act as important communicators, connecting cytoskeletal components with each other and to cellular junctions. Bullous pemphigoid antigen 1 (BPAG1)/dystonin is a member of spectraplakin family and expressed in various tissues. Alternative splicing of BPAG1 gene produces various isoforms with unique structure and domains. BPAG1 plays crucial roles in numerous biological processes, such as cytoskeleton organization, cell polarization, cell adhesion, and cell migration as well as signaling transduction. Genetic mutation of BPAG1 isoforms is the miscreant of epidermolysis bullosa and multifarious, destructive neurological diseases. In this review, we summarize the recent advances of BPAG1's role in various biological processes and in skin and neurological diseases.
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Affiliation(s)
- Arshad Ali
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China; Shenzhen Research Institution of Northwestern Polytechnical University, Shenzhen, 518057, PR China; Northwestern Polytechnical University-Hong Kong Baptist University Joint Research Centre for Translational Medicine on Musculoskeletal Health in Space, Xi'an, 710072, PR China
| | - Lifang Hu
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China; Shenzhen Research Institution of Northwestern Polytechnical University, Shenzhen, 518057, PR China; Northwestern Polytechnical University-Hong Kong Baptist University Joint Research Centre for Translational Medicine on Musculoskeletal Health in Space, Xi'an, 710072, PR China
| | - Fan Zhao
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China; Shenzhen Research Institution of Northwestern Polytechnical University, Shenzhen, 518057, PR China; Northwestern Polytechnical University-Hong Kong Baptist University Joint Research Centre for Translational Medicine on Musculoskeletal Health in Space, Xi'an, 710072, PR China
| | - Wuxia Qiu
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China; Shenzhen Research Institution of Northwestern Polytechnical University, Shenzhen, 518057, PR China; Northwestern Polytechnical University-Hong Kong Baptist University Joint Research Centre for Translational Medicine on Musculoskeletal Health in Space, Xi'an, 710072, PR China
| | - Pai Wang
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China; Shenzhen Research Institution of Northwestern Polytechnical University, Shenzhen, 518057, PR China; Northwestern Polytechnical University-Hong Kong Baptist University Joint Research Centre for Translational Medicine on Musculoskeletal Health in Space, Xi'an, 710072, PR China
| | - Xiaoli Ma
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China; Shenzhen Research Institution of Northwestern Polytechnical University, Shenzhen, 518057, PR China; Northwestern Polytechnical University-Hong Kong Baptist University Joint Research Centre for Translational Medicine on Musculoskeletal Health in Space, Xi'an, 710072, PR China
| | - Yan Zhang
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China; Shenzhen Research Institution of Northwestern Polytechnical University, Shenzhen, 518057, PR China; Northwestern Polytechnical University-Hong Kong Baptist University Joint Research Centre for Translational Medicine on Musculoskeletal Health in Space, Xi'an, 710072, PR China
| | - Lei Chen
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China; Shenzhen Research Institution of Northwestern Polytechnical University, Shenzhen, 518057, PR China; Northwestern Polytechnical University-Hong Kong Baptist University Joint Research Centre for Translational Medicine on Musculoskeletal Health in Space, Xi'an, 710072, PR China
| | - Airong Qian
- Laboratory for Bone Metabolism, Key Laboratory for Space Bioscience and Biotechnology, School of Life Sciences, Northwestern Polytechnical University, Xi'an, Shaanxi 710072, PR China; Shenzhen Research Institution of Northwestern Polytechnical University, Shenzhen, 518057, PR China; Northwestern Polytechnical University-Hong Kong Baptist University Joint Research Centre for Translational Medicine on Musculoskeletal Health in Space, Xi'an, 710072, PR China.
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Seehusen F, Kiel K, Jottini S, Wohlsein P, Habierski A, Seibel K, Vogel T, Urlaub H, Kollmar M, Baumgärtner W, Teichmann U. Axonopathy in the Central Nervous System Is the Hallmark of Mice with a Novel Intragenic Null Mutation of Dystonin. Genetics 2016; 204:191-203. [PMID: 27401753 PMCID: PMC5012385 DOI: 10.1534/genetics.116.186932] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 07/03/2016] [Indexed: 01/13/2023] Open
Abstract
Dystonia musculorum is a neurodegenerative disorder caused by a mutation in the dystonin gene. It has been described in mice and humans where it is called hereditary sensory autonomic neuropathy. Mutated mice show severe movement disorders and die at the age of 3-4 weeks. This study describes the discovery and molecular, clinical, as well as pathological characterization of a new spontaneously occurring mutation in the dystonin gene in C57BL/6N mice. The mutation represents a 40-kb intragenic deletion allele of the dystonin gene on chromosome 1 with exactly defined deletion borders. It was demonstrated by Western blot, mass spectrometry, and immunohistology that mice with a homozygous mutation were entirely devoid of the dystonin protein. Pathomorphological lesions were restricted to the brain stem and spinal cord and consisted of swollen, argyrophilic axons and dilated myelin sheaths in the white matter and, less frequently, total chromatolysis of neurons in the gray matter. Axonal damage was detected by amyloid precursor protein and nonphosphorylated neurofilament immunohistology. Axonopathy in the central nervous system (CNS) represents the hallmark of this disease. Mice with the dystonin mutation also showed suppurative inflammation in the respiratory tract, presumably due to brain stem lesion-associated food aspiration, whereas skeletal muscles showed no pathomorphological changes. This study describes a novel mutation in the dystonin gene in mice leading to axonopathy in the CNS. In further studies, this model may provide new insights into the pathogenesis of neurodegenerative diseases and may elucidate the complex interactions of dystonin with various other cellular proteins especially in the CNS.
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Affiliation(s)
- Frauke Seehusen
- Department of Pathology, University of Veterinary Medicine, D-30559 Hannover, Germany
| | - Kirsten Kiel
- Animal Facility, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Stefano Jottini
- Department of Pathology, University of Veterinary Medicine, D-30559 Hannover, Germany Department of Animal Health, Pathology Unit, Faculty of Veterinary Medicine, University of Parma, I-43100, Italy
| | - Peter Wohlsein
- Department of Pathology, University of Veterinary Medicine, D-30559 Hannover, Germany
| | - Andre Habierski
- Department of Pathology, University of Veterinary Medicine, D-30559 Hannover, Germany
| | - Katharina Seibel
- Department of Cellular Logistics, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Tanja Vogel
- Institute of Anatomy and Cell Biology, University of Freiburg, D-79104, Germany
| | - Henning Urlaub
- Bioanalytical Mass Spectrometry, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany Bioanalytics, Department of Clinical Chemistry, University Medical Center Göttingen, D-37075, Germany
| | - Martin Kollmar
- Department of NMR-Based Structural Biology, Research Group Systems Biology of Motor Proteins, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
| | - Wolfgang Baumgärtner
- Department of Pathology, University of Veterinary Medicine, D-30559 Hannover, Germany Center for Systems Neuroscience, University of Veterinary Medicine, D-30559 Hannover, Germany
| | - Ulrike Teichmann
- Animal Facility, Max Planck Institute for Biophysical Chemistry, D-37077 Göttingen, Germany
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12
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Grando SA. The mitochondrion is a common target of disease pathophysiology in pemphigus and pemphigoid. Exp Dermatol 2016; 24:655-6. [PMID: 26014338 DOI: 10.1111/exd.12772] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/20/2015] [Indexed: 01/01/2023]
Affiliation(s)
- Sergei A Grando
- Department of Dermatology, University of California, Irvine, CA, USA
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Ozuemba B, Masilamani TJ, Loiselle JJ, Koenderink B, Vanderbeck KA, Knee J, Larivière C, Sutherland LC. Co- and post-transcriptional regulation of Rbm5 and Rbm10 in mouse cells as evidenced by tissue-specific, developmental and disease-associated variation of splice variant and protein expression levels. Gene 2016; 580:26-36. [PMID: 26784654 DOI: 10.1016/j.gene.2015.12.070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/31/2015] [Indexed: 01/09/2023]
Abstract
BACKGROUND Expression and function of the two RNA binding proteins and regulators of alternative splicing, RBM5 and RBM10, have largely been studied in human tissue and cell lines. The objective of the study described herein was to examine their expression in mouse tissue, in order to lay the framework for comprehensive functional studies using mouse models. METHODS All RNA variants of Rbm5 and Rbm10 were examined in a range of normal primary mouse tissues. RNA and protein were examined in differentiating C2C12 myoblasts and in denervated and dystonin-deficient mouse skeletal muscle. RESULTS All Rbm5 and Rbm10 variants examined were expressed in all mouse tissues and cell lines. In general, Rbm5 and Rbm10 RNA expression was higher in brain than in skin. RNA expression levels were more varied between cardiac and skeletal muscle, depending on the splice variant: for instance, Rbm10v1 RNA was higher in skeletal than cardiac muscle, whereas Rbm10v3 RNA was higher in cardiac than skeletal muscle. In mouse brain, cardiac and skeletal muscle, RNA encoding an approximately 17kDa potential paralogue of a small human RBM10 isoform was detected, and the protein observed in myoblasts and myotubes. Expression of Rbm5 and Rbm10 RNA remained constant during C2C12 myogenesis, but protein levels significantly decreased. In two muscle disease models, neither Rbm10 nor Rbm5 showed significant transcriptional changes, although significant specific alternative splicing changes of Rbm5 pre-mRNA were observed. Increased RBM10 protein levels were observed following denervation. CONCLUSIONS The varied co-transcriptional and post-transcriptional regulation aspects of Rbm5 and Rbm10 expression associated with mouse tissues, myogenesis and muscle disease states suggest that a mouse model would be an interesting and useful model in which to study comprehensive functional aspects of RBM5 and RBM10.
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Affiliation(s)
| | - Twinkle J Masilamani
- Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E 2C6, Canada
| | - Julie J Loiselle
- Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E 2C6, Canada
| | - Benjamin Koenderink
- AMRIC, Health Sciences North, 41 Ramsey Lake Road, Sudbury, ON, P3E 5J1, Canada
| | - Kaitlin A Vanderbeck
- School of Human Kinetics, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E 2C6, Canada
| | - Jose Knee
- AMRIC, Health Sciences North, 41 Ramsey Lake Road, Sudbury, ON, P3E 5J1, Canada
| | - Céline Larivière
- Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E 2C6, Canada; School of Human Kinetics, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E 2C6, Canada
| | - Leslie C Sutherland
- Biomolecular Sciences Program, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E 2C6, Canada; AMRIC, Health Sciences North, 41 Ramsey Lake Road, Sudbury, ON, P3E 5J1, Canada; Division of Medical Sciences, Northern Ontario School of Medicine, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E 2C6, Canada; Department of Chemistry and Biochemistry, Laurentian University, 935 Ramsey Lake Road, Sudbury, ON, P3E 2C6, Canada; Department of Medicine, Division of Medical Oncology, University of Ottawa, Ottawa, ON, Canada.
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14
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Abstract
The cytoskeleton is a dynamic network of filamentous protein polymers required for virtually all cellular processes. It consists of three major classes, filamentous actin (F-actin), intermediate filaments, and microtubules, all displaying characteristic structural properties, functions, cellular distributions, and sets of interacting regulatory proteins. One unique class of proteins, the spectraplakins, bind, regulate, and integrate the functions of all three classes of cytoskeleton proteins. Spectraplakins are giant, evolutionary conserved multidomain proteins (spanning up to 9000 aa) that are true members of the plakin, spectrin, and Gas2-like protein families. They have OMIM-listed disease links to epidermolysis bullosa and hereditary sensory and autonomic neuropathy. Their role in disease is likely underrepresented since studies in model animal systems have revealed critical roles in polarity, morphogenesis, differentiation and maintenance, migration, signaling, and intracellular trafficking in a variety of tissues. This enormous diversity of spectraplakin function is consistent with the numerous isoforms produced from single genomic loci that combine different sets of functional domains in distinct cellular contexts. To study the broad range of functions and complexity of these proteins, Drosophila is a powerful model. Thus, the fly spectraplakin Short stop (Shot) acts as an actin-microtubule linker and plays important roles in many developmental processes, which provide experimentally amenable and relevant contexts in which to study spectraplakin functions. For these studies, a versatile range of relevant experimental resources that facilitate genetics and transgenic approaches, highly refined genomics tools, and an impressive set of spectraplakin-specific genetic and molecular tools are readily available. Here, we use the example of Shot to illustrate how the various tools and strategies available for Drosophila can be employed to decipher and dissect cellular roles and molecular mechanisms of spectraplakins.
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Poliakova K, Adebola A, Leung CL, Favre B, Liem RKH, Schepens I, Borradori L. BPAG1a and b associate with EB1 and EB3 and modulate vesicular transport, Golgi apparatus structure, and cell migration in C2.7 myoblasts. PLoS One 2014; 9:e107535. [PMID: 25244344 PMCID: PMC4171495 DOI: 10.1371/journal.pone.0107535] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 08/18/2014] [Indexed: 11/19/2022] Open
Abstract
BPAG1a and BPAG1b (BPAG1a/b) constitute two major isoforms encoded by the dystonin (Dst) gene and show homology with MACF1a and MACF1b. These proteins are members of the plakin family, giant multi-modular proteins able to connect the intermediate filament, microtubule and microfilament cytoskeletal networks with each other and to distinct cell membrane sites. They also serve as scaffolds for signaling proteins that modulate cytoskeletal dynamics. To gain better insights into the functions of BPAG1a/b, we further characterized their C-terminal region important for their interaction with microtubules and assessed the role of these isoforms in the cytoskeletal organization of C2.7 myoblast cells. Our results show that alternative splicing does not only occur at the 5′ end of Dst and Macf1 pre-mRNAs, as previously reported, but also at their 3′ end, resulting in expression of additional four mRNA variants of BPAG1 and MACF1. These isoform-specific C-tails were able to bundle microtubules and bound to both EB1 and EB3, two microtubule plus end proteins. In the C2.7 cell line, knockdown of BPAG1a/b had no major effect on the organization of the microtubule and microfilament networks, but negatively affected endocytosis and maintenance of the Golgi apparatus structure, which became dispersed. Finally, knockdown of BPAG1a/b caused a specific decrease in the directness of cell migration, but did not impair initial cell adhesion. These data provide novel insights into the complexity of alternative splicing of Dst pre-mRNAs and into the role of BPAG1a/b in vesicular transport, Golgi apparatus structure as well as in migration in C2.7 myoblasts.
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Affiliation(s)
- Kseniia Poliakova
- Department of Clinical Research, University of Bern, Bern, Switzerland
- Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
- Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland
- * E-mail:
| | - Adijat Adebola
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
| | - Conrad L. Leung
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
| | - Bertrand Favre
- Department of Clinical Research, University of Bern, Bern, Switzerland
- Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland
| | - Ronald K. H. Liem
- Department of Pathology and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, United States of America
| | - Isabelle Schepens
- Department of Clinical Research, University of Bern, Bern, Switzerland
| | - Luca Borradori
- Department of Clinical Research, University of Bern, Bern, Switzerland
- Department of Dermatology, Inselspital, Bern University Hospital, Bern, Switzerland
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Duplication in the microtubule-actin cross-linking factor 1 gene causes a novel neuromuscular condition. Sci Rep 2014; 4:5180. [PMID: 24899269 PMCID: PMC4046130 DOI: 10.1038/srep05180] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 05/12/2014] [Indexed: 12/12/2022] Open
Abstract
Spectrins and plakins are important communicators linking cytoskeletal components to each other and to cellular junctions. Microtubule-actin cross-linking factor 1 (MACF1) belongs to the spectraplakin family and is involved in control of microtubule dynamics. Complete knock out of MACF1 in mice is associated with developmental retardation and embryonic lethality. Here we present a family with a novel neuromuscular condition. Genetic analyses show a heterozygous duplication resulting in reduced MACF1 gene product. The functional consequence is affected motility observed as periodic hypotonia, lax muscles and diminished motor skills, with heterogeneous presentation among the affected family members. To corroborate these findings we used RNA interference to knock down the VAB-10 locus containing the MACF1 homologue in C. elegans, and we could show that this also causes movement disturbances. These findings suggest that changes in the MACF1 gene is implicated in this neuromuscular condition, which is an important observation since MACF1 has not previously been associated with any human disease and thus presents a key to understanding the essential nature of this gene.
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17
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Bouameur JE, Favre B, Borradori L. Plakins, a versatile family of cytolinkers: roles in skin integrity and in human diseases. J Invest Dermatol 2013; 134:885-894. [PMID: 24352042 DOI: 10.1038/jid.2013.498] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Revised: 10/16/2013] [Accepted: 10/25/2013] [Indexed: 11/09/2022]
Abstract
The plakin family consists of giant proteins involved in the cross-linking and organization of the cytoskeleton and adhesion complexes. They further modulate several fundamental biological processes, such as cell adhesion, migration, and polarization or signaling pathways. Inherited and acquired defects of plakins in humans and in animal models potentially lead to dramatic manifestations in the skin, striated muscles, and/or nervous system. These observations unequivocally demonstrate the key role of plakins in the maintenance of tissue integrity. Here we review the characteristics of the mammalian plakin members BPAG1 (bullous pemphigoid antigen 1), desmoplakin, plectin, envoplakin, epiplakin, MACF1 (microtubule-actin cross-linking factor 1), and periplakin, highlighting their role in skin homeostasis and diseases.
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Affiliation(s)
- Jamal-Eddine Bouameur
- Departments of Dermatology and Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland; Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland
| | - Bertrand Favre
- Departments of Dermatology and Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland.
| | - Luca Borradori
- Departments of Dermatology and Clinical Research, Inselspital, Bern University Hospital, and University of Bern, Bern, Switzerland
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18
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Cellular and Molecular Biology of Neuronal Dystonin. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 300:85-120. [DOI: 10.1016/b978-0-12-405210-9.00003-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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19
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Untethering the nuclear envelope and cytoskeleton: biologically distinct dystonias arising from a common cellular dysfunction. Int J Cell Biol 2012; 2012:634214. [PMID: 22611399 PMCID: PMC3352338 DOI: 10.1155/2012/634214] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 12/12/2011] [Accepted: 01/08/2012] [Indexed: 12/31/2022] Open
Abstract
Most cases of early onset DYT1 dystonia in humans are caused by a GAG deletion in the TOR1A gene leading to loss of a glutamic acid (ΔE) in the torsinA protein, which underlies a movement disorder associated with neuronal dysfunction without apparent neurodegeneration. Mutation/deletion of the gene (Dst) encoding dystonin in mice results in a dystonic movement disorder termed dystonia musculorum, which resembles aspects of dystonia in humans. While torsinA and dystonin proteins do not share modular domain architecture, they participate in a similar function by modulating a structural link between the nuclear envelope and the cytoskeleton in neuronal cells. We suggest that through a shared interaction with the nuclear envelope protein nesprin-3α, torsinA and the neuronal dystonin-a2 isoform comprise a bridge complex between the outer nuclear membrane and the cytoskeleton, which is critical for some aspects of neuronal development and function. Elucidation of the overlapping roles of torsinA and dystonin-a2 in nuclear/endoplasmic reticulum dynamics should provide insights into the cellular mechanisms underlying the dystonic phenotype.
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20
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Damon M, Wyszynska-Koko J, Vincent A, Hérault F, Lebret B. Comparison of muscle transcriptome between pigs with divergent meat quality phenotypes identifies genes related to muscle metabolism and structure. PLoS One 2012; 7:e33763. [PMID: 22470472 PMCID: PMC3312351 DOI: 10.1371/journal.pone.0033763] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2011] [Accepted: 02/17/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Meat quality depends on physiological processes taking place in muscle tissue, which could involve a large pattern of genes associated with both muscle structural and metabolic features. Understanding the biological phenomena underlying muscle phenotype at slaughter is necessary to uncover meat quality development. Therefore, a muscle transcriptome analysis was undertaken to compare gene expression profiles between two highly contrasted pig breeds, Large White (LW) and Basque (B), reared in two different housing systems themselves influencing meat quality. LW is the most predominant breed used in pig industry, which exhibits standard meat quality attributes. B is an indigenous breed with low lean meat and high fat contents, high meat quality characteristics, and is genetically distant from other European pig breeds. METHODOLOGY/PRINCIPAL FINDINGS Transcriptome analysis undertaken using a custom 15 K microarray, highlighted 1233 genes differentially expressed between breeds (multiple-test adjusted P-value<0.05), out of which 635 were highly expressed in the B and 598 highly expressed in the LW pigs. No difference in gene expression was found between housing systems. Besides, expression level of 12 differentially expressed genes quantified by real-time RT-PCR validated microarray data. Functional annotation clustering emphasized four main clusters associated to transcriptome breed differences: metabolic processes, skeletal muscle structure and organization, extracellular matrix, lysosome, and proteolysis, thereby highlighting many genes involved in muscle physiology and meat quality development. CONCLUSIONS/SIGNIFICANCE Altogether, these results will contribute to a better understanding of muscle physiology and of the biological and molecular processes underlying meat quality. Besides, this study is a first step towards the identification of molecular markers of pork quality and the subsequent development of control tools.
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Affiliation(s)
- Marie Damon
- INRA, UMR1348 Physiologie, Environnement et Génétique pour l'Animal et les Systèmes d'Elevage (PEGASE), Saint Gilles, France.
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21
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Ryan SD, Bhanot K, Ferrier A, De Repentigny Y, Chu A, Blais A, Kothary R. Microtubule stability, Golgi organization, and transport flux require dystonin-a2-MAP1B interaction. ACTA ACUST UNITED AC 2012; 196:727-42. [PMID: 22412020 PMCID: PMC3308695 DOI: 10.1083/jcb.201107096] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Loss of interaction between the dystonin-a2 isoform and the microtubule-associated protein MAP1B induces microtubule instability and trafficking defects that may underlie certain neuropathies. Loss of function of dystonin cytoskeletal linker proteins causes neurodegeneration in dystonia musculorum (dt) mutant mice. Although much investigation has focused on understanding dt pathology, the diverse cellular functions of dystonin isoforms remain poorly characterized. In this paper, we highlight novel functions of the dystonin-a2 isoform in mediating microtubule (MT) stability, Golgi organization, and flux through the secretory pathway. Using dystonin mutant mice combined with isoform-specific loss-of-function analysis, we found dystonin-a2 bound to MT-associated protein 1B (MAP1B) in the centrosomal region, where it maintained MT acetylation. In dt neurons, absence of the MAP1B–dystonin-a2 interaction resulted in altered MAP1B perikaryal localization, leading to MT deacetylation and instability. Deacetylated MT accumulation resulted in Golgi fragmentation and prevented anterograde trafficking via motor proteins. Maintenance of MT acetylation through trichostatin A administration or MAP1B overexpression mitigated the observed defect. These cellular aberrations are apparent in prephenotype dorsal root ganglia and primary sensory neurons from dt mice, suggesting they are causal in the disorder.
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Affiliation(s)
- Scott D Ryan
- Ottawa Hospital Research Institute, Ottawa, Ontario K1H 8L6, Canada
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22
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Ryan SD, Ferrier A, Sato T, O'Meara RW, De Repentigny Y, Jiang SX, Hou ST, Kothary R. Neuronal dystonin isoform 2 is a mediator of endoplasmic reticulum structure and function. Mol Biol Cell 2012; 23:553-66. [PMID: 22190742 PMCID: PMC3279385 DOI: 10.1091/mbc.e11-06-0573] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Revised: 10/26/2011] [Accepted: 12/12/2011] [Indexed: 12/16/2022] Open
Abstract
Dystonin/Bpag1 is a cytoskeletal linker protein whose loss of function in dystonia musculorum (dt) mice results in hereditary sensory neuropathy. Although loss of expression of neuronal dystonin isoforms (dystonin-a1/dystonin-a2) is sufficient to cause dt pathogenesis, the diverging function of each isoform and what pathological mechanisms are activated upon their loss remains unclear. Here we show that dt(27) mice manifest ultrastructural defects at the endoplasmic reticulum (ER) in sensory neurons corresponding to in vivo induction of ER stress proteins. ER stress subsequently leads to sensory neurodegeneration through induction of a proapoptotic caspase cascade. dt sensory neurons display neurodegenerative pathologies, including Ca(2+) dyshomeostasis, unfolded protein response (UPR) induction, caspase activation, and apoptosis. Isoform-specific loss-of-function analysis attributes these neurodegenerative pathologies to specific loss of dystonin-a2. Inhibition of either UPR or caspase signaling promotes the viability of cells deficient in dystonin. This study provides insight into the mechanism of dt neuropathology and proposes a role for dystonin-a2 as a mediator of normal ER structure and function.
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Affiliation(s)
- Scott D. Ryan
- Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
| | - Andrew Ferrier
- Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Tadasu Sato
- Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Division of Periodontology and Endodontology, Graduate School of Dentistry, Tohoku University, Sendai 980-8575, Japan
| | - Ryan W. O'Meara
- Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | | | - Susan X. Jiang
- Institute for Biological Sciences, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
| | - Sheng T. Hou
- Institute for Biological Sciences, National Research Council Canada, Ottawa, ON K1A 0R6, Canada
| | - Rashmi Kothary
- Ottawa Hospital Research Institute, Ottawa, ON K1H 8L6, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Department of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
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23
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De Repentigny Y, Ferrier A, Ryan SD, Sato T, Kothary R. Motor unit abnormalities in Dystonia musculorum mice. PLoS One 2011; 6:e21093. [PMID: 21698255 PMCID: PMC3115977 DOI: 10.1371/journal.pone.0021093] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 05/18/2011] [Indexed: 12/21/2022] Open
Abstract
Dystonia musculorum (dt) is a mouse inherited sensory neuropathy caused by mutations in the dystonin gene. While the primary pathology lies in the sensory neurons of dt mice, the overt movement disorder suggests motor neurons may also be affected. Here, we report on the contribution of motor neurons to the pathology in dt(27J) mice. Phenotypic dt(27J) mice display reduced alpha motor neuron cell number and eccentric alpha motor nuclei in the ventral horn of the lumbar L1 spinal cord region. A dramatic reduction in the total number of motor axons in the ventral root of postnatal day 15 dt(27J) mice was also evident. Moreover, analysis of the trigeminal nerve of the brainstem showed a 2.4 fold increase in number of degenerating neurons coupled with a decrease in motor neuron number relative to wild type. Aberrant phosphorylation of neurofilaments in the perikaryon region and axonal swellings within the pre-synaptic terminal region of motor neurons were observed. Furthermore, neuromuscular junction staining of dt(27J) mouse extensor digitorum longus and tibialis anterior muscle fibers showed immature endplates and a significant decrease in axon branching compared to wild type littermates. Muscle atrophy was also observed in dt(27J) muscle. Ultrastructure analysis revealed amyelinated motor axons in the ventral root of the spinal nerve, suggesting a possible defect in Schwann cells. Finally, behavioral analysis identified defective motor function in dt(27J) mice. This study reveals neuromuscular defects that likely contribute to the dt(27J) pathology and identifies a critical role for dystonin outside of sensory neurons.
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Affiliation(s)
| | - Andrew Ferrier
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine and the Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Scott D. Ryan
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Tadasu Sato
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
| | - Rashmi Kothary
- Ottawa Hospital Research Institute, Ottawa, Ontario, Canada
- Department of Cellular and Molecular Medicine and the Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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Boyer JG, Bernstein MA, Boudreau-Larivière C. Plakins in striated muscle. Muscle Nerve 2010; 41:299-308. [DOI: 10.1002/mus.21472] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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25
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Hearts of dystonia musculorum mice display normal morphological and histological features but show signs of cardiac stress. PLoS One 2010; 5:e9465. [PMID: 20209123 PMCID: PMC2830884 DOI: 10.1371/journal.pone.0009465] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2009] [Accepted: 02/08/2010] [Indexed: 12/31/2022] Open
Abstract
Dystonin is a giant cytoskeletal protein belonging to the plakin protein family and is believed to crosslink the major filament systems in contractile cells. Previous work has demonstrated skeletal muscle defects in dystonin-deficient dystonia musculorum (dt) mice. In this study, we show that the dystonin muscle isoform is localized at the Z-disc, the H zone, the sarcolemma and intercalated discs in cardiac tissue. Based on this localization pattern, we tested whether dystonin-deficiency leads to structural defects in cardiac muscle. Desmin intermediate filament, microfilament, and microtubule subcellular organization appeared normal in dt hearts. Nevertheless, increased transcript levels of atrial natriuretic factor (ANF, 66%) β-myosin heavy chain (beta-MHC, 95%) and decreased levels of sarcoplasmic reticulum calcium pump isoform 2A (SERCA2a, 26%), all signs of cardiac muscle stress, were noted in dt hearts. Hearts from two-week old dt mice were assessed for the presence of morphological and histological alterations. Heart to body weight ratios as well as left ventricular wall thickness and left chamber volume measurements were similar between dt and wild-type control mice. Hearts from dt mice also displayed no signs of fibrosis or calcification. Taken together, our data provide new insights into the intricate structure of the sarcomere by situating dystonin in cardiac muscle fibers and suggest that dystonin does not significantly influence the structural organization of cardiac muscle fibers during early postnatal development.
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26
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Steiner-Champliaud MF, Schneider Y, Favre B, Paulhe F, Praetzel-Wunder S, Faulkner G, Konieczny P, Raith M, Wiche G, Adebola A, Liem RK, Langbein L, Sonnenberg A, Fontao L, Borradori L. BPAG1 isoform-b: Complex distribution pattern in striated and heart muscle and association with plectin and α-actinin. Exp Cell Res 2010; 316:297-313. [DOI: 10.1016/j.yexcr.2009.11.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Revised: 11/13/2009] [Accepted: 11/16/2009] [Indexed: 10/20/2022]
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27
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Bereiter-Hahn J, Jendrach M. Mitochondrial dynamics. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2010; 284:1-65. [PMID: 20875628 DOI: 10.1016/s1937-6448(10)84001-8] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mitochondrial dynamics is a key feature for the interaction of mitochondria with other organelles within a cell and also for the maintenance of their own integrity. Four types of mitochondrial dynamics are discussed: Movement within a cell and interactions with the cytoskeleton, fusion and fission events which establish coherence within the chondriome, the dynamic behavior of cristae and their components, and finally, formation and disintegration of mitochondria (mitophagy). Due to these essential functions, disturbed mitochondrial dynamics are inevitably connected to a variety of diseases. Localized ATP gradients, local control of calcium-based messaging, production of reactive oxygen species, and involvement of other metabolic chains, that is, lipid and steroid synthesis, underline that physiology not only results from biochemical reactions but, in addition, resides on the appropriate morphology and topography. These events and their molecular basis have been established recently and are the topic of this review.
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Affiliation(s)
- Jürgen Bereiter-Hahn
- Center of Excellence Macromolecular Complexes, Institute for Cell Biology and Neurosciences, Goethe University, Frankfurt am Main, Germany
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28
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Abstract
The dystonin/Bpag1 cytoskeletal interacting proteins play important roles in maintaining cytoarchitecture integrity in skin and in the neuromuscular system. The most profound phenotype observed in the dystonin mutant dystonia musculorum (dt) mice is a severe movement disorder, attributed in large part to sensory neuron degeneration. The molecular basis for this phenotype is currently not clear, despite several studies indicating possible causes for the pathology in dt mice. Complicating the picture of what essential dystonin functions are lost in dt mice is the fact that our understanding of the very nature of what dystonin is has evolved greatly over the past decade. Elucidating the roles of dystonin most relevant to neuronal function and survival should help to shed light on some of the common mechanisms underlying neurodegeneration.
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Affiliation(s)
- Kevin G Young
- Ottawa Health Research Institute, Ottawa, Ontario, K1H 8L6 Canada
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Muscular Integrity—A Matter of Interlinking Distinct Structures via Plectin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 642:165-75. [DOI: 10.1007/978-0-387-84847-1_12] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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30
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Sonnenberg A, Liem RKH. Plakins in development and disease. Exp Cell Res 2007; 313:2189-203. [PMID: 17499243 DOI: 10.1016/j.yexcr.2007.03.039] [Citation(s) in RCA: 228] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2007] [Revised: 03/01/2007] [Accepted: 03/06/2007] [Indexed: 11/22/2022]
Abstract
Plakins are large multi-domain molecules that have various functions to link cytoskeletal elements together and to connect them to junctional complexes. Plakins were first identified in epithelial cells where they were found to connect the intermediate filaments to desmosomes and hemidesmosomes [Ruhrberg, C., and Watt, F.M. (1997). The plakin family: versatile organizers of cytoskeletal architecture. Curr Opin Genet Dev 7, 392-397.]. They were subsequently found to be important for the integrity of muscle cells. Most recently, they have been found in the nervous system, where their functions appear to be more complex, including cross-linking of microtubules (MTs) and actin filaments [Leung, C.L., Zheng, M., Prater, S.M., and Liem, R.K. (2001). The BPAG1 locus: Alternative splicing produces multiple isoforms with distinct cytoskeletal linker domains, including predominant isoforms in neurons and muscles. J Cell Biol 154, 691-697., Leung, C.L., Sun, D., Zheng, M., Knowles, D.R., and Liem, R.K. (1999). Microtubule actin cross-linking factor (MACF): a hybrid of dystonin and dystrophin that can interact with the actin and microtubule cytoskeletons. J Cell Biol 147, 1275-1286.]. These plakins have also indicated their relationship to the spectrin superfamily of proteins and the plakins appear to be evolutionarily related to the spectrins, but have diverged to perform different specialized functions. In invertebrates, a single plakin is present in both Drosophila melanogaster and Caenorhabditis elegans, which resemble the more complex plakins found in mammals [Roper, K., Gregory, S.L., and Brown, N.H. (2002). The 'spectraplakins': cytoskeletal giants with characteristics of both spectrin and plakin families. J Cell Sci 115, 4215-4225.]. In contrast, there are seven plakins found in mammals and most of them have alternatively spliced forms leading to a very complex group of proteins with potential tissue specific functions [Jefferson, J.J., Leung, C.L., and Liem, R.K. (2004). Plakins: goliaths that link cell junctions and the cytoskeleton. Nat Rev Mol Cell Biol 5, 542-553.]. In this review, we will first describe the plakins, desmoplakin, plectin, envoplakin and periplakin and then describe two other mammalian plakins, Bullous pemphigoid antigen 1 (BPAG1) and microtubule actin cross-linking factor 1 (MACF1), that are expressed in multiple isoforms in different tissues. We will also describe the relationship of these two proteins to the invertebrate plakins, shortstop (shot) in Drosophila and VAB-10 in C. elegans. Finally, we will describe an unusual mammalian plakin, called epiplakin.
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Affiliation(s)
- Arnoud Sonnenberg
- Division of Cell Biology, The Netherlands Cancer Inst., Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands.
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Goryunov D, Adebola A, Jefferson JJ, Leung CL, Messer A, Liem RKH. Molecular characterization of the genetic lesion in Dystonia musculorum (dt-Alb) mice. Brain Res 2007; 1140:179-87. [PMID: 16725123 DOI: 10.1016/j.brainres.2006.04.068] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Revised: 04/17/2006] [Accepted: 04/18/2006] [Indexed: 10/24/2022]
Abstract
Dystonia musculorum (dt) is an inherited autosomal recessive neuropathy in mice. Homozygous animals display primarily sensory neurodegeneration resulting in a severe loss of coordination. Several dt strains exist, including spontaneous mutants dt-Alb (Albany), dt-J (Jackson Labs), and dt-Frk (Frankel), and a transgene insertion mutant, Tg4. They contain mutations in the gene encoding Bullous Pemphigoid Antigen 1 (BPAG1), or dystonin. BPAG1 is a member of the plakin family of cytolinker proteins. BPAG1 is alternatively spliced to produce several isoforms, including the major brain-specific isoform, BPAG1a. The neurological phenotype observed in dt-Alb mice is thought to result from the absence of BPAG1a protein in the developing nervous system. The goal of this study was to determine the precise molecular nature of the dt-Alb mutation and examine residual BPAG1 expression in homozygous dt-Alb mice. A combination of molecular biological strategies revealed that the dt-Alb lesion is a deletion-insertion eliminating a large part of the coding region of BPAG1a. The molecular lesion in the dt-Alb BPAG1 allele is expected to render it completely non-functional. Although transcripts corresponding to BPAG1 segments still remaining in homozygous dt-Alb mice could be detected by RT-PCR, there was no positive signal for BPAG1 in the brain of dt-Alb mice by Northern blotting. Western blotting with polyclonal anti-BPAG1 antibodies confirmed the absence of functional BPAG1 protein (full-length or truncated) in the dt-Alb brain. Our identification of the 5' junction of the dt-Alb insertion makes it possible to genotype dt-Alb animals by standard PCR.
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Affiliation(s)
- Dmitry Goryunov
- Department of Pathology, Columbia University College of Physicians and Surgeons, P&S 15-421, New York, NY 10032, USA
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Anesti V, Scorrano L. The relationship between mitochondrial shape and function and the cytoskeleton. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2006; 1757:692-9. [PMID: 16729962 DOI: 10.1016/j.bbabio.2006.04.013] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2006] [Revised: 03/13/2006] [Accepted: 04/07/2006] [Indexed: 12/12/2022]
Abstract
Mitochondria are crucial organelles for life and death of the cell. They are prominent players in energy conversion and integrated signaling pathways including regulation of Ca2+ signals and apoptosis. Their functional versatility is matched by their morphological plasticity and by their high mobility, allowing their transport at specialized cellular sites. This transport occurs by interactions with a variety of cytoskeletal proteins that also have the ability to influence shape and function of the organelle. A growing body of evidence suggests that mitochondria use cytoskeletal proteins as tracks for their movement; in turn, mitochondrial morphology and function is regulated via mostly uncharacterized pathways, by the cytoskeleton.
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Affiliation(s)
- Vasiliki Anesti
- Dulbecco-Telethon Institute, Venetian Institute of Molecular Medicine, Via Orus 2, I-35129, Padova, Italy
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33
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Lalonde R, Strazielle C. Spontaneous and induced mouse mutations with cerebellar dysfunctions: behavior and neurochemistry. Brain Res 2006; 1140:51-74. [PMID: 16499884 DOI: 10.1016/j.brainres.2006.01.031] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Accepted: 01/12/2006] [Indexed: 11/20/2022]
Abstract
Grid2(Lc) (Lurcher), Grid2(ho) (hot-foot), Rora(sg) (staggerer), nr (nervous), Agtpbp1(pcd) (Purkinje cell degeneration), Reln(rl) (reeler), and Girk2(Wv) (Weaver) are spontaneous mutations with cerebellar atrophy, ataxia, and deficits in motor coordination tasks requiring balance and equilibrium. In addition to these signs, the Dst(dt) (dystonia musculorum) spinocerebellar mutant displays dystonic postures and crawling. More recently, transgenic models with human spinocerebellar ataxia mutations and alterations in calcium homeostasis have been shown to exhibit cerebellar anomalies and motor coordination deficits. We describe neurochemical characteristics of these mutants with respect to regional brain metabolism as well as amino acid and biogenic amine concentrations, uptake sites, and receptors.
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Affiliation(s)
- R Lalonde
- Université de Rouen, Faculté de Médecine et de Pharmacie, INSERM U614, 76183 Rouen Cedex, France.
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34
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Pool M, Boudreau Larivière C, Bernier G, Young KG, Kothary R. Genetic alterations at the Bpag1 locus in dt mice and their impact on transcript expression. Mamm Genome 2005; 16:909-17. [PMID: 16341670 DOI: 10.1007/s00335-005-0073-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Accepted: 08/23/2005] [Indexed: 10/25/2022]
Abstract
The dystonin/Bpag1 gene encodes several tissue-specific alternatively spliced transcripts that encode cytoskeletal binding proteins. These various isoforms are necessary for maintaining the structural integrity of epithelial, neural, and muscle tissues. Mutations in the dystonin/Bpag1 gene cause dystonia musculorum (dt), a hereditary neuropathy of the mouse characterized by the progressive degeneration of sensory neurons. Several dt mutant alleles exist, most of which have arisen through spontaneous mutations. In this article we demonstrate that the dt locus encodes 107 exons spanning 400 kb. The high frequency of occurrence of spontaneous dt mutants may therefore be a result of the large size of the gene. Analysis of genomic DNA from several dt spontaneous mutant alleles, dt(24J), dt(27J), dt(Alb), and dt(Frk), shows a deletion of the central portion of the gene in dt(Alb) but no large rearrangements or deletions in the other alleles. These other alleles likely have small deletions or rearrangements, or point mutations. To determine the impact of the known and unknown mutations on transcript levels, RT-PCR was performed to detect various coding regions of the dystonin/Bpag1 transcripts in brain and muscle from multiple dt alleles: dt(Tg4), dt(Alb), dt(24J), dt(27J), and dt(Frk). With the exception of dt(Frk), reduced transcript levels were observed for all alleles tested. Such alterations likely result in reduced or absent dystonin/Bpag1 protein levels. Thus, distinct genetic defects lead to a common outcome of reduced transcript expression causing the same phenotype in multiple dt alleles.
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Affiliation(s)
- Madeline Pool
- Molecular Medicine Program, Ottawa Health Research Institute, Ottawa, Ontario, K1H 8L6, Canada
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35
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Lalonde R, Marchetti N, Strazielle C. Primary neurologic screening and motor coordination of Dstdt-J mutant mice (dystonia musculorum) with spinocerebellar atrophy. Physiol Behav 2005; 86:46-51. [PMID: 16087202 DOI: 10.1016/j.physbeh.2005.06.028] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2005] [Revised: 05/30/2005] [Accepted: 06/20/2005] [Indexed: 11/27/2022]
Abstract
The autosomal recessive dystonia musculorum (Dst(dt-J)) mutation causes degenerative lesions of peripheral and central sensory pathways. A test battery of motor, sensory, postural, and autonomic functions was used to compare young control and homozygous Dst(dt-J) mice. The Dst(dt-J) mutants were severely impaired for muscle strength, limb coordination, and postural reflexes. As a result of a loss in motor control, the mutants were hypoactive in the open-field and fell quickly from the stationary beam. In sensory tests, the acoustic startle response was impaired, but not tactile reflexes and contact righting, attesting to preserved labyrinthine function and non-lemniscal pathways. Dst(dt-J) mutants were also distinguishable from controls on the basis of tremor, a paler skin, piloerection, and half-open eyes, as well as low body weight and fecal boli. Grooming episodes were less frequent in the mutants but without any reduction in grooming time. The neurologic screening battery delineated the functional integrity of some sensorimotor pathways in a spinocerebellar mutant whose severe phenotype prevents a more elaborate evaluation.
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Affiliation(s)
- R Lalonde
- Université de Rouen, Faculté de Médecine et de Pharmacie, INSERM U614, Bâtiment de Recherche, Salle 1D18, France.
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36
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Abstract
Spectrin repeat sequences are among the more common repeat elements identified in proteins, typically occurring in large structural proteins. Examples of spectrin repeat-containing proteins include dystrophin, alpha-actinin and spectrin itself--all proteins with well-demonstrated roles of establishing and maintaining cell structure. Over the past decade, it has become clear that, although these proteins display a cytoplasmic and plasma membrane distribution, several are also found both at the nuclear envelope, and within the intranuclear space. In this review, we provide an overview of recent work regarding various spectrin repeat-containing structural proteins in the nucleus. As well, we hypothesize about the regulation of their nuclear localization and possible nuclear functions based on domain architecture, known interacting proteins and evolutionary relationships. Given their large size, and their potential for interacting with multiple proteins and with chromatin, spectrin repeat-containing proteins represent strong candidates for important organizational proteins within the nucleus. Supplementary material for this article can be found on the BioEssays website (http://www.interscience.wiley.com/jpages/0265-9247/suppmat/index.html).
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Affiliation(s)
- Kevin G Young
- Ottawa Health Research Institute, Ontario K1H 8L6, Canada
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37
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Goryunov D, Leung CL, Liem RKH. Studying cytolinker proteins. Methods Cell Biol 2005; 78:787-816. [PMID: 15646639 DOI: 10.1016/s0091-679x(04)78027-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/01/2023]
Affiliation(s)
- Dmitry Goryunov
- Columbia University College of Physicians and Surgeons, New York, New York 10032, USA
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38
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Green KJ, Böhringer M, Gocken T, Jones JCR. Intermediate filament associated proteins. ADVANCES IN PROTEIN CHEMISTRY 2005; 70:143-202. [PMID: 15837516 DOI: 10.1016/s0065-3233(05)70006-1] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Intermediate filament associated proteins (IFAPs) coordinate interactions between intermediate filaments (IFs) and other cytoskeletal elements and organelles, including membrane-associated junctions such as desmosomes and hemidesmosomes in epithelial cells, costameres in striated muscle, and intercalated discs in cardiac muscle. IFAPs thus serve as critical connecting links in the IF scaffolding that organizes the cytoplasm and confers mechanical stability to cells and tissues. However, in recent years it has become apparent that IFAPs are not limited to structural crosslinkers and bundlers but also include chaperones, enzymes, adapters, and receptors. IF networks can therefore be considered scaffolding upon which associated proteins are organized and regulated to control metabolic activities and maintain cell homeostasis.
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Affiliation(s)
- Kathleen J Green
- Departments of Pathology and Dermatology and R.H. Lurie Cancer Center, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA
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39
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Yung CK, Halperin VL, Tomaselli GF, Winslow RL. Gene expression profiles in end-stage human idiopathic dilated cardiomyopathy: altered expression of apoptotic and cytoskeletal genes. Genomics 2004; 83:281-97. [PMID: 14706457 DOI: 10.1016/j.ygeno.2003.08.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dilated cardiomyopathy is now the leading cause of cardiovascular morbidity and mortality. While the molecular basis of this disease remains uncertain, evidence is emerging that gene expression profiles of left ventricular myocardium isolated from failing versus nonfailing patients differ dramatically. In this study, we use high-density oligonucleotide microarrays with approximately 22000 probes to characterize differences in the expression profiles further. To facilitate interpretation of experimental data, we evaluate algorithms for normalization of hybridization data and for computation of gene expression indices using a control spike-in data set. We then use these methods to identify statistically significant changes in the expression levels of genes not previously implicated in the molecular phenotype of heart failure. These regulated genes take part in diverse cellular processes, including transcription, apoptosis, sarcomeric and cytoskeletal function, remodeling of the extracellular matrix, membrane transport, and metabolism.
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Affiliation(s)
- Christina K Yung
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine & Whiting School of Engineering, Baltimore, MD 21218, USA.
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40
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Young KG, Pool M, Kothary R. Bpag1 localization to actin filaments and to the nucleus is regulated by its N-terminus. J Cell Sci 2003; 116:4543-55. [PMID: 14576348 DOI: 10.1242/jcs.00764] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Plakins are a family of giant cytoskeleton binding proteins. One member of this group is bullous pemphigoid antigen 1 (Bpag1)/dystonin, which has neuronal and muscle isoforms that consist of actin-binding and microtubule-binding domains at either end separated by a plakin domain and several spectrin repeats. The better-characterized epithelial isoform has only the plakin domain in common with the neuronal and muscle isoforms. Here, we have analyzed the localization of muscle/neuronal (Bpag1a/b) isoforms and the epithelial (Bpag1e) isoform within C2C12 myoblast cells. Although an antibody specific to Bpag1a/b isoform 2 detected protein co-aligning actin stress fibers, this same antibody and two Bpag1e antibodies predominantly detected protein in the nuclei. A Bpag1a/b isoform 2 N-terminal fusion protein containing the plakin domain also localized to actin stress fibers and to nuclei. Within the plakin domain, we characterized a functional nuclear localization signal, which was responsible for localization of the fusion protein to the nucleus. Bpag1a/b isoform 1 N-terminal fusion proteins differed in their interaction with the actin cytoskeleton and with their ability to localize to the nucleus, suggesting that Bpag1 isoforms with different N-termini have differing roles. These results show the importance of N-terminal domains in dictating the localization and function of Bpag1 isoforms. We provide the first indication that Bpag1 is not strictly a cytoplasmic/membrane protein but that it can also localize to the nucleus.
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Affiliation(s)
- Kevin G Young
- Ottawa Health Research Institute, 501 Smyth Road, Ottawa, Ontario, Canada K1H 8L6, and Center for Neuromuscular Disease, and Departments of Cellular and Molecular Medicine, and Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
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41
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Herrmann H, Hesse M, Reichenzeller M, Aebi U, Magin TM. Functional complexity of intermediate filament cytoskeletons: from structure to assembly to gene ablation. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 223:83-175. [PMID: 12641211 DOI: 10.1016/s0074-7696(05)23003-6] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The cell biology of intermediate filament (IF) proteins and their filaments is complicated by the fact that the members of the gene family, which in humans amount to at least 65, are differentially expressed in very complex patterns during embryonic development. Thus, different tissues and cells express entirely different sets and amounts of IF proteins, the only exception being the nuclear B-type lamins, which are found in every cell. Moreover, in the course of evolution the individual members of this family have, within one species, diverged so much from each other with regard to sequence and thus molecular properties that it is hard to envision a unifying kind of function for them. The known epidermolytic diseases, caused by single point mutations in keratins, have been used as an argument for a role of IFs in mechanical "stress resistance," something one would not have easily ascribed to the beaded chain filaments, a special type of IF in the eye lens, or to nuclear lamins. Therefore, the power of plastic dish cell biology may be limited in revealing functional clues for these structural elements, and it may therefore be of interest to go to the extreme ends of the life sciences, i.e., from the molecular properties of individual molecules including their structure at the atomic level to targeted inactivation of their genes in living animals, mouse, and worm to define their role more precisely in metazoan cell physiology.
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Affiliation(s)
- Harald Herrmann
- Division of Cell Biology, German Cancer Research Center, D-69120 Heidelberg, Germany
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42
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Jazwinska A, Ehler E, Hughes SM. Intermediate filament-co-localized molecules with myosin heavy chain epitopes define distinct cellular domains in hair follicles and epidermis. BMC Cell Biol 2003; 4:10. [PMID: 12899730 PMCID: PMC194435 DOI: 10.1186/1471-2121-4-10] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2003] [Accepted: 08/04/2003] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Proteins linking intermediate filaments to other cytoskeletal components have important functions in maintaining tissue integrity and cell shape. RESULTS We found a set of monoclonal antibodies raised against specific human sarcomeric myosin heavy chain (MyHC) isoforms labels cells in distinct regions of the mammalian epidermis. The antigens co-localize with intermediate filament-containing structures. A slow MyHC-related antigen is punctate on the cell surface and co-localizes with desmoplakin at desmosomal junctions of all suprabasal epidermal layers from rat foetal day 16 onwards, in the root sheath of the hair follicle and in intercalated disks of cardiomyocytes. A fast MyHC-related antigen occurs in cytoplasmic filaments in a subset of basal cells of skin epidermis and bulb, but not neck, of hair follicles. A fast IIA MyHC-related antigen labels filaments of a single layer of cells in hair bulb. This 230,000 Mr antigen co-purifies with keratin. No obvious candidate for any of the antigens appears in the literature. CONCLUSIONS We describe a set of molecules that co-localize with intermediate filament in specific cell subsets in epithelial tissues. These antigens presumably influence intermediate filament structure or function.
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Affiliation(s)
- Ania Jazwinska
- current address: Dept. of Cell Biology, Biozentrum, Klingelbergstr. 70, CH-4056 Basel, Switzerland
| | - Elisabeth Ehler
- Randall Centre, 4th floor south, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
| | - Simon M Hughes
- Randall Centre, 4th floor south, New Hunt's House, Guy's Campus, King's College London, London SE1 1UL, UK
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43
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De Repentigny Y, Deschênes-Furry J, Jasmin BJ, Kothary R. Impaired fast axonal transport in neurons of the sciatic nerves from dystonia musculorum mice. J Neurochem 2003; 86:564-71. [PMID: 12859670 DOI: 10.1046/j.1471-4159.2003.01861.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Dystonia musculorum (dt) mice suffer from a severe sensory neuropathy caused by mutations in the gene encoding the cytoskeletal cross-linker protein dystonin/bullous pemphigoid antigen 1 (Bpag1). Loss of function of dystonin/Bpag1 within neurons leads to a loss in the maintenance of cytoskeletal organization and to the development of focal axonal swellings prior to death of the neuron. In the present study, we demonstrate that neurons within the sciatic nerves of dt27J mice undergo axonal degeneration as has been previously reported for the dorsal roots. Furthermore, ultrastructural studies reveal a perturbed organization of the neurofilament and microtubule networks within the axons of sciatic nerves in dt27J mice. The disrupted cytoskeletal organization suggested that axonal transport is affected in dt mice. To address this, we assessed fast axonal transport by measuring the rate of accumulation of acetylcholinesterase (AChE) proximal and distal to a surgically introduced ligature on the sciatic nerves of normal and dt27J mice. Our findings demonstrate that axonal transport of AChE in both orthograde and retrograde directions is markedly affected, and allow us to conclude that axonal transport defects do exist in the sciatic nerves of dt27J mice.
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44
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Röper K, Gregory SL, Brown NH. The 'spectraplakins': cytoskeletal giants with characteristics of both spectrin and plakin families. J Cell Sci 2002; 115:4215-25. [PMID: 12376554 DOI: 10.1242/jcs.00157] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recent studies have characterised a family of giant cytoskeletal crosslinkers encoded by the short stop gene in Drosophila and the dystonin/BPAG1 and MACF1 genes in mammals. We refer to the products of these genes as spectraplakins to highlight the fact that they share features with both the spectrin and plakin superfamilies. These genes produce a variety of large proteins, up to almost 9000 residues long, which can potentially extend 0.4 micro m across a cell. Spectraplakins can interact with all three elements of the cytoskeleton: actin, microtubules and intermediate filaments. The analysis of mutant phenotypes in BPAG1 in mouse and short stop in Drosophila demonstrates that spectraplakins have diverse roles. These include linking the plasma membrane and the cytoskeleton, linking together different elements of the cytoskeleton and organising membrane domains.
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Affiliation(s)
- Katja Röper
- Wellcome Trust/Cancer Research UK Institute and Dept of Anatomy, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QR, UK
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45
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Boudreau-Larivière C, Kothary R. Differentiation potential of primary myogenic cells derived from skeletal muscle of dystonia musculorum mice. Differentiation 2002; 70:247-56. [PMID: 12190986 DOI: 10.1046/j.1432-0436.2002.700603.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The dystonia musculorum (dt) mouse has a mutation in the gene encoding the cytoskeletal crosslinker protein bullous pemphigoid antigen 1 (Bpag1). These mice have perturbations in the cytoarchitecture of skeletal muscle. Bpag1 has been hypothesized to be involved in the maintenance rather than the establishment of the muscle cell architecture given that cytoskeletal disruptions are observed in the muscle tissue of post-natal dt mice. Not known is whether Bpag1-deficiency affects the proliferative and differentiation potential of myogenic cells. In the present investigation, we show that the growth rate of cultured primary myogenic cells derived from dt mice, as assessed by BrdU incorporation, is similar to that of myogenic cells derived from wild-type littermates. The myogenic differentiation potential of dt versus wild-type cells was monitored by examining the expression of myosin heavy chain by immunofluorescence, and by analyzing the expression profiles of myogenic regulatory factors and myogenic differentiation markers by RT-PCR. In all instances, both dt and wild-type myogenic cells displayed a similar differentiation profile. Furthermore, the absence of any observable differences in the proliferation and differentiation rates of dt and wild-type cells was not due to an overexpression of plectin, another crosslinker protein, in dt cells. Together, these findings demonstrate that the early phases of myogenic differentiation occur independently of Bpag1.
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46
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Saulnier R, De Repentigny Y, Yong VW, Kothary R. Alterations in myelination in the central nervous system of dystonia musculorum mice. J Neurosci Res 2002; 69:233-42. [PMID: 12111805 DOI: 10.1002/jnr.10289] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Dystonia musculorum (dt) is an autosomal recessive sensory neuropathy in mice resulting from a mutation in the gene encoding the cytoskeletal linker protein Bpag1. In addition to neurodegeneration, dt mice display myelination abnormalities in the peripheral nervous system. In this report we investigated whether myelination abnormalities are also present in the central nervous system of dt(Tg4) mice. Transcripts for both neural isoforms of Bpag1 (a1 and a2) were detected in optic nerves and spinal cords of wild-type mice. Light microscopy of resin-embedded thin sections revealed a reduction in myelinated axons in both optic nerves and spinal cords in dt(Tg4) mice. As well, hypermyelinated axons were detected in these tissues. Ultrastructural analysis of optic nerves and spinal cords from dt(Tg4) mice revealed an increase in the number of amyelinated axons, the presence of hypo- and hypermyelinated axons, and redundant myelin that course away from axons. Changes in the level of myelin proteins accompanied the morphological alterations. Myelin-associated glycoprotein levels were reduced in optic nerves of dt(Tg4) mice, and myelin basic protein levels were altered in optic nerves, sciatic nerves, and spinal cords of affected mice. Short-term cultures of oligodendrocytes derived from dt(Tg4) mice did not show morphological alterations.
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Affiliation(s)
- Ron Saulnier
- Ottawa Health Research Institute and The University of Ottawa Center for Neuromuscular Disease, Ottawa, Ontario, Canada
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47
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Strazielle C, Ase AR, Lalonde R, Reader TA. Biochemical and autoradiographic studies of the central noradrenergic system in dystonia musculorum mutant mice. J Chem Neuroanat 2002; 23:143-55. [PMID: 11841918 DOI: 10.1016/s0891-0618(01)00154-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The autosomal recessive mutation dystonia musculorum (dt(J)/dt(J)) causes degenerative alterations of peripheral and central sensory pathways leading to ataxia. To determine the consequences of this pathology on the central noradrenergic (NA) system, NA contents were measured by high-performance liquid chromatography (HPLC) in 22 brain regions and spinal cord, while NA transporters, or uptake sites, were evaluated by quantitative ligand binding autoradiography, using [3H]nisoxetine, in wild-type and dt(J)/dt(J) mutant mice. The only significant differences in NA contents between the two genotypes were increased levels in hypothalamus and mesencephalic dopaminergic regions A9/A10 of dt(J)/dt(J) mutants. The dt(J)/dt(J) spinal cord showed a similar result, but its NA content remained unchanged when taking into account its reduced volume. Binding to NA transporters revealed increased densities in sensory nuclei of cranial nerves, granular layer of the cerebellar cortex, as well as in cerebellar-related and basal ganglia structures, such as the lateral cuneate nucleus, pontine nuclei, substantia nigra, pontine reticular formation, median raphe nucleus and superior colliculus. Forebrain regions were relatively unaffected in the dt(J)/dt(J) mutants, although NA transporter densities were higher in piriform cortex, hippocampal subdivisions and ventro-anterior thalamic nucleus. In contrast, densities of NA transporters were decreased in hypothalamic subregions and in two ventrobasal thalamic nuclei. The results are discussed in relation to expression of the dystonin gene in normal brain, cellular defects resulting from the loss of gene transcription in the dt(J)/dt(J) mutation, functional circuits of the central nervous system and some of the phenotypical characteristics of dystonia musculorum mutants.
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Affiliation(s)
- C Strazielle
- Département de Physiologie, Centre de Recherche en Sciences Neurologiques, Faculté de Médecine, Université de Montréal, Quebec, H3C 3J7, Montréal, Canada
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Abstract
By connecting cytoskeletal elements to each other and to junctional complexes, the plakin family of cytolinkers plays a crucial role in orchestrating cellular development and maintaining tissue integrity. Plakins are built from combinations of interacting domains that bind to microfilaments, microtubules, intermediate filaments, cell-adhesion molecules and members of the armadillo family. Plakins are involved in both inherited and autoimmune diseases that affect the skin, neuronal tissue, and cardiac and skeletal muscle. Here, we describe the members of the plakin family and their interaction partners, and give examples of the cellular defects that result from their dysfunction.
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Affiliation(s)
- Conrad L Leung
- Dept of Pathology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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Leung CL, Zheng M, Prater SM, Liem RK. The BPAG1 locus: Alternative splicing produces multiple isoforms with distinct cytoskeletal linker domains, including predominant isoforms in neurons and muscles. J Cell Biol 2001; 154:691-7. [PMID: 11514586 PMCID: PMC2196450 DOI: 10.1083/jcb.200012098] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2000] [Revised: 07/06/2001] [Accepted: 07/13/2001] [Indexed: 12/04/2022] Open
Abstract
Bullous pemphigoid antigen 1 (BPAG1) is a member of the plakin family with cytoskeletal linker properties. Mutations in BPAG1 cause sensory neuron degeneration and skin fragility in mice. We have analyzed the BPAG1 locus in detail and found that it encodes different interaction domains that are combined in tissue-specific manners. These domains include an actin-binding domain (ABD), a plakin domain, a coiled coil (CC) rod domain, two different potential intermediate filament-binding domains (IFBDs), a spectrin repeat (SR)-containing rod domain, and a microtubule-binding domain (MTBD). There are at least three major forms of BPAG1: BPAG1-e (302 kD), BPAG1-a (615 kD), and BPAG1-b (834 kD). BPAG1-e has been described previously and consists of the plakin domain, the CC rod domain, and the first IFBD. It is the primary epidermal BPAG1 isoform, and its absence that is the likely cause of skin fragility in mutant mice. BPAG1-a is the major isoform in the nervous system and a homologue of the microtubule actin cross-linking factor, MACF. BPAG1-a is composed of the ABD, the plakin domain, the SR-containing rod domain, and the MTBD. The absence of BPAG1-a is the likely cause of sensory neurodegeneration in mutant mice. BPAG1-b is highly expressed in muscles, and has extra exons encoding a second IFBD between the plakin and SR-containing rod domains of BPAG1-a.
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Affiliation(s)
- C L Leung
- Department of Pathology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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Milner DJ, Mavroidis M, Weisleder N, Capetanaki Y. Desmin cytoskeleton linked to muscle mitochondrial distribution and respiratory function. J Cell Biol 2000; 150:1283-98. [PMID: 10995435 PMCID: PMC2150713 DOI: 10.1083/jcb.150.6.1283] [Citation(s) in RCA: 273] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2000] [Accepted: 08/02/2000] [Indexed: 12/28/2022] Open
Abstract
Ultrastructural studies have previously suggested potential association of intermediate filaments (IFs) with mitochondria. Thus, we have investigated mitochondrial distribution and function in muscle lacking the IF protein desmin. Immunostaining of skeletal muscle tissue sections, as well as histochemical staining for the mitochondrial marker enzymes cytochrome C oxidase and succinate dehydrogenase, demonstrate abnormal accumulation of subsarcolemmal clumps of mitochondria in predominantly slow twitch skeletal muscle of desmin-null mice. Ultrastructural observation of desmin-null cardiac muscle demonstrates in addition to clumping, extensive mitochondrial proliferation in a significant fraction of the myocytes, particularly after work overload. These alterations are frequently associated with swelling and degeneration of the mitochondrial matrix. Mitochondrial abnormalities can be detected very early, before other structural defects become obvious. To investigate related changes in mitochondrial function, we have analyzed ADP-stimulated respiration of isolated muscle mitochondria, and ADP-stimulated mitochondrial respiration in situ using saponin skinned muscle fibers. The in vitro maximal rates of respiration in isolated cardiac mitochondria from desmin-null and wild-type mice were similar. However, mitochondrial respiration in situ is significantly altered in desmin-null muscle. Both the maximal rate of ADP-stimulated oxygen consumption and the dissociation constant (K(m)) for ADP are significantly reduced in desmin-null cardiac and soleus muscle compared with controls. Respiratory parameters for desmin-null fast twitch gastrocnemius muscle were unaffected. Additionally, respiratory measurements in the presence of creatine indicate that coupling of creatine kinase and the adenine translocator is lost in desmin-null soleus muscle. This coupling is unaffected in cardiac muscle from desmin-null animals. All of these studies indicate that desmin IFs play a significant role in mitochondrial positioning and respiratory function in cardiac and skeletal muscle.
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Affiliation(s)
- D J Milner
- Department of Molecular and Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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