1
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Lloyd EM, Pinniger GJ, Murphy RM, Grounds MD. Slow or fast: Implications of myofibre type and associated differences for manifestation of neuromuscular disorders. Acta Physiol (Oxf) 2023; 238:e14012. [PMID: 37306196 DOI: 10.1111/apha.14012] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 05/30/2023] [Accepted: 06/06/2023] [Indexed: 06/13/2023]
Abstract
Many neuromuscular disorders can have a differential impact on a specific myofibre type, forming the central premise of this review. The many different skeletal muscles in mammals contain a spectrum of slow- to fast-twitch myofibres with varying levels of protein isoforms that determine their distinctive contractile, metabolic, and other properties. The variations in functional properties across the range of classic 'slow' to 'fast' myofibres are outlined, combined with exemplars of the predominantly slow-twitch soleus and fast-twitch extensor digitorum longus muscles, species comparisons, and techniques used to study these properties. Other intrinsic and extrinsic differences are discussed in the context of slow and fast myofibres. These include inherent susceptibility to damage, myonecrosis, and regeneration, plus extrinsic nerves, extracellular matrix, and vasculature, examined in the context of growth, ageing, metabolic syndrome, and sexual dimorphism. These many differences emphasise the importance of carefully considering the influence of myofibre-type composition on manifestation of various neuromuscular disorders across the lifespan for both sexes. Equally, understanding the different responses of slow and fast myofibres due to intrinsic and extrinsic factors can provide deep insight into the precise molecular mechanisms that initiate and exacerbate various neuromuscular disorders. This focus on the influence of different myofibre types is of fundamental importance to enhance translation for clinical management and therapies for many skeletal muscle disorders.
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Affiliation(s)
- Erin M Lloyd
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
- Curtin Health Innovation Research Institute, Curtin Medical School, Curtin University, Bentley, Western Australia, Australia
| | - Gavin J Pinniger
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Robyn M Murphy
- Department of Biochemistry and Chemistry, School of Agriculture, Biomedicine and Environment, La Trobe University, Melbourne, Victoria, Australia
| | - Miranda D Grounds
- Department of Anatomy, Physiology and Human Biology, School of Human Sciences, The University of Western Australia, Perth, Western Australia, Australia
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2
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Gleneadie HJ, Fernandez-Ruiz B, Sardini A, Van de Pette M, Dimond A, Prinjha RK, McGinty J, French PMW, Bagci H, Merkenschlager M, Fisher AG. Endogenous bioluminescent reporters reveal a sustained increase in utrophin gene expression upon EZH2 and ERK1/2 inhibition. Commun Biol 2023; 6:318. [PMID: 36966198 PMCID: PMC10039851 DOI: 10.1038/s42003-023-04666-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 03/06/2023] [Indexed: 03/27/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked disorder caused by loss of function mutations in the dystrophin gene (Dmd), resulting in progressive muscle weakening. Here we modelled the longitudinal expression of endogenous Dmd, and its paralogue Utrn, in mice and in myoblasts by generating bespoke bioluminescent gene reporters. As utrophin can partially compensate for Dmd-deficiency, these reporters were used as tools to ask whether chromatin-modifying drugs can enhance Utrn expression in developing muscle. Myoblasts treated with different PRC2 inhibitors showed significant increases in Utrn transcripts and bioluminescent signals, and these responses were independently verified by conditional Ezh2 deletion. Inhibition of ERK1/2 signalling provoked an additional increase in Utrn expression that was also seen in Dmd-mutant cells, and maintained as myoblasts differentiate. These data reveal PRC2 and ERK1/2 to be negative regulators of Utrn expression and provide specialised molecular imaging tools to monitor utrophin expression as a therapeutic strategy for DMD.
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Affiliation(s)
- Hannah J Gleneadie
- Epigenetic Memory Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Beatriz Fernandez-Ruiz
- Epigenetic Memory Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Alessandro Sardini
- Whole Animal Physiology and Imaging Facility, MRC LMS, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Mathew Van de Pette
- Epigenetic Memory Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, Du Cane Road, London, W12 0NN, UK
- MRC Toxicology Unit, Gleeson Building, Tennis Court Road, Cambridge, CB2 1QR, UK
| | - Andrew Dimond
- Epigenetic Memory Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Rab K Prinjha
- Immunology and Epigenetics Research Unit, Research, GlaxoSmithKline, Gunnels Wood Road, Stevenage, Herts, SG1 2NY, UK
| | - James McGinty
- Photonics Group, Department of Physics, Blackett Laboratory, Imperial College London, London, SW7 2AZ, UK
| | - Paul M W French
- Photonics Group, Department of Physics, Blackett Laboratory, Imperial College London, London, SW7 2AZ, UK
| | - Hakan Bagci
- Lymphocyte Development Group, MRC LMS, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Matthias Merkenschlager
- Lymphocyte Development Group, MRC LMS, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Amanda G Fisher
- Epigenetic Memory Group, MRC London Institute of Medical Sciences (LMS), Imperial College London, Du Cane Road, London, W12 0NN, UK.
- Department of Biochemistry, University of Oxford, South Parks Road, OX1 3QU, Oxford, UK.
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3
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Mitochondrial Permeability Transition Causes Mitochondrial Reactive Oxygen Species- and Caspase 3-Dependent Atrophy of Single Adult Mouse Skeletal Muscle Fibers. Cells 2021; 10:cells10102586. [PMID: 34685566 PMCID: PMC8534155 DOI: 10.3390/cells10102586] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/16/2021] [Accepted: 09/25/2021] [Indexed: 02/03/2023] Open
Abstract
Elevated mitochondrial reactive oxygen species (mROS) and an increase in caspase-3 activity are established mechanisms that lead to skeletal muscle atrophy via the upregulation of protein degradation pathways. However, the mechanisms upstream of an increase in mROS and caspase-3 activity in conditions of muscle atrophy have not been identified. Based upon knowledge that an event known as mitochondrial permeability transition (MPT) causes an increase in mROS emission and the activation of caspase-3 via mitochondrial release of cytochrome c, as well as the circumstantial evidence for MPT in some muscle atrophy conditions, we tested MPT as a mechanism of atrophy. Briefly, treating cultured single mouse flexor digitorum brevis (FDB) fibers from adult mice with a chemical inducer of MPT (Bz423) for 24 h caused an increase in mROS and caspase-3 activity that was accompanied by a reduction in muscle fiber diameter that was able to be prevented by inhibitors of MPT, mROS, or caspase-3 (p < 0.05). Similarly, a four-day single fiber culture as a model of disuse caused atrophy that could be prevented by inhibitors of MPT, mROS, or activated caspase-3. As such, our results identify MPT as a novel mechanism of skeletal muscle atrophy that operates through mROS emission and caspase-3 activation.
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Smith LR, Meyer GA. Skeletal muscle explants: ex-vivo models to study cellular behavior in a complex tissue environment. Connect Tissue Res 2020; 61:248-261. [PMID: 31492079 PMCID: PMC8837600 DOI: 10.1080/03008207.2019.1662409] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 08/22/2019] [Indexed: 02/03/2023]
Abstract
Purpose/Aim: Skeletal muscle tissue explants have been cultured and studied for nearly 100 years. These cultures, which retain complex tissue structure in an environment suited to precision manipulation and measurement, have led to seminal discoveries of the extrinsic and intrinsic mechanisms regulating contractility, metabolism and regeneration. This review discusses the two primary models of muscle explant: isolated myofiber and intact muscle.Materials and Methods: Relevant literature was reviewed and synthesized with a focus on the unique challenges and capabilities of each explant model.Results: Impactful past, current and future novel applications are discussed.Conclusions: Experiments using skeletal muscle explants have been integral to our understanding of the fundamentals of muscle physiology. As they are refined and adapted, they are poised to continue to inform the field for years to come.
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Affiliation(s)
- Lucas R Smith
- Departments of Neurobiology, Physiology and Behavior and Physical Medicine and Rehabilitation, University of California, Davis, CA, USA
| | - Gretchen A Meyer
- Program in Physical Therapy and Departments of Neurology, Biomedical Engineering and Orthopaedic Surgery, Washington University in St. Louis, St. Louis, MO, USA
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5
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Cabrera-Serrano M, Coote DJ, Azmanov D, Goullee H, Andersen E, McLean C, Davis M, Ishimura R, Stark Z, Vallat JM, Komatsu M, Kornberg A, Ryan M, Laing NG, Ravenscroft G. A homozygous UBA5 pathogenic variant causes a fatal congenital neuropathy. J Med Genet 2020; 57:835-842. [PMID: 32179706 DOI: 10.1136/jmedgenet-2019-106496] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 02/19/2020] [Accepted: 02/22/2020] [Indexed: 12/17/2022]
Abstract
BACKGROUND UBA5 is the activating enzyme of UFM1 in the ufmylation post-translational modification system. Different neurological phenotypes have been associated with UBA5 pathogenic variants including epilepsy, intellectual disability, movement disorders and ataxia. METHODS AND RESULTS We describe a large multigenerational consanguineous family presenting with a severe congenital neuropathy causing early death in infancy. Whole exome sequencing and linkage analysis identified a novel homozygous UBA5 NM_024818.3 c.31C>T (p.Arg11Trp) mutation. Protein expression assays in mouse tissue showed similar levels of UBA5 in peripheral nerves to the central nervous system. CRISPR-Cas9 edited HEK (human embrionic kidney) cells homozygous for the UBA5 p.Arg11Trp mutation showed reduced levels of UBA5 protein compared with the wild-type. The mutant p.Arg11Trp UBA5 protein shows reduced ability to activate UFM1. CONCLUSION This report expands the phenotypical spectrum of UBA5 mutations to include fatal peripheral neuropathy.
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Affiliation(s)
- Macarena Cabrera-Serrano
- Department of Neurology, Neuromuscular Unit and Instituto de Biomedicina de Sevilla/CSIC, Hospital Universitario Virgen del Rocío, Sevilla, Spain.,Centre of Medical Research, The University of Western Australia and the Harry Perkins Institute for Medical Research, Perth, Western Australia, Australia.,Centro Investigación Biomédica en Red Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - David Joseph Coote
- Centre of Medical Research, The University of Western Australia and the Harry Perkins Institute for Medical Research, Perth, Western Australia, Australia
| | - Dimitar Azmanov
- Centre of Medical Research, The University of Western Australia and the Harry Perkins Institute for Medical Research, Perth, Western Australia, Australia.,Department of Diagnostic Genomics, PathWest, QEII Medical Centre, Perth, Western Australia, Australia
| | - Hayley Goullee
- Centre of Medical Research, The University of Western Australia and the Harry Perkins Institute for Medical Research, Perth, Western Australia, Australia
| | - Erik Andersen
- Pediatrics, University of Otago Wellington, Wellington, New Zealand.,Department of Neurology and Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Catriona McLean
- Anatomical Pathology, Alfred Health, Melbourne, Victoria, Australia
| | - Mark Davis
- Department of Diagnostic Genomics, PathWest, QEII Medical Centre, Perth, Western Australia, Australia
| | - Ryosuke Ishimura
- Department of Physiology, Juntendo University School of Medicine Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Zornitza Stark
- Victorian Clinical Genetics Services, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Jean-Michel Vallat
- Reference center for peripheral neuropathies, University Hospital, Limoges, France
| | - Masaaki Komatsu
- Department of Physiology, Juntendo University School of Medicine Graduate School of Medicine, Bunkyo-ku, Tokyo, Japan
| | - Andrew Kornberg
- Department of Neurology and Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Monique Ryan
- Department of Neurology and Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Nigel G Laing
- Centre of Medical Research, The University of Western Australia and the Harry Perkins Institute for Medical Research, Perth, Western Australia, Australia
| | - Gina Ravenscroft
- Centre of Medical Research, The University of Western Australia and the Harry Perkins Institute for Medical Research, Perth, Western Australia, Australia
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6
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Hoppstädter J, Valbuena Perez JV, Linnenberger R, Dahlem C, Legroux TM, Hecksteden A, Tse WKF, Flamini S, Andreas A, Herrmann J, Herr C, Müller R, Meyer T, Bals R, Riccardi C, Bruscoli S, Kiemer AK. The glucocorticoid-induced leucine zipper mediates statin-induced muscle damage. FASEB J 2020; 34:4684-4701. [PMID: 32030813 DOI: 10.1096/fj.201902557rrr] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 01/21/2020] [Accepted: 01/21/2020] [Indexed: 12/31/2022]
Abstract
Statins, the most prescribed class of drugs for the treatment of hypercholesterolemia, can cause muscle-related adverse effects. It has been shown that the glucocorticoid-induced leucine zipper (GILZ) plays a key role in the anti-myogenic action of dexamethasone. In the present study, we aimed to evaluate the role of GILZ in statin-induced myopathy. Statins induced GILZ expression in C2C12 cells, primary murine myoblasts/myotubes, primary human myoblasts, and in vivo in zebrafish embryos and human quadriceps femoris muscle. Gilz induction was mediated by FOXO3 activation and binding to the Gilz promoter, and could be reversed by the addition of geranylgeranyl, but not farnesyl, pyrophosphate. Atorvastatin decreased Akt phosphorylation and increased cleaved caspase-3 levels in myoblasts. This effect was reversed in myoblasts from GILZ knockout mice. Similarly, myofibers isolated from knockout animals were more resistant toward statin-induced cell death than their wild-type counterparts. Statins also impaired myoblast differentiation, and this effect was accompanied by GILZ induction. The in vivo relevance of our findings was supported by the observation that gilz overexpression in zebrafish embryos led to impaired embryonic muscle development. Taken together, our data point toward GILZ as an essential mediator of the molecular mechanisms leading to statin-induced muscle damage.
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Affiliation(s)
- Jessica Hoppstädter
- Department of Pharmacy, Pharmaceutical Biology, Saarland University, Saarbrücken, Germany.,Department of Medicine, Section of Pharmacology, University of Perugia, Perugia, Italy
| | | | - Rebecca Linnenberger
- Department of Pharmacy, Pharmaceutical Biology, Saarland University, Saarbrücken, Germany
| | - Charlotte Dahlem
- Department of Pharmacy, Pharmaceutical Biology, Saarland University, Saarbrücken, Germany
| | - Thierry M Legroux
- Department of Pharmacy, Pharmaceutical Biology, Saarland University, Saarbrücken, Germany
| | - Anne Hecksteden
- Institute of Sports and Preventive Medicine, Saarland University, Saarbrücken, Germany
| | - William K F Tse
- Center for Promotion of International Education and Research, Faculty of Agriculture, Kyushu University, Fukuoka, Japan
| | - Sara Flamini
- Department of Medicine, Section of Pharmacology, University of Perugia, Perugia, Italy
| | - Anastasia Andreas
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarbrücken, Germany
| | - Jennifer Herrmann
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarbrücken, Germany
| | - Christian Herr
- Department of Internal Medicine V-Pulmonology, Allergology and Critical Care Medicine, Saarland University, Homburg, Germany
| | - Rolf Müller
- Department of Microbial Natural Products, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Saarbrücken, Germany
| | - Tim Meyer
- Institute of Sports and Preventive Medicine, Saarland University, Saarbrücken, Germany
| | - Robert Bals
- Department of Internal Medicine V-Pulmonology, Allergology and Critical Care Medicine, Saarland University, Homburg, Germany
| | - Carlo Riccardi
- Department of Medicine, Section of Pharmacology, University of Perugia, Perugia, Italy
| | - Stefano Bruscoli
- Department of Medicine, Section of Pharmacology, University of Perugia, Perugia, Italy
| | - Alexandra K Kiemer
- Department of Pharmacy, Pharmaceutical Biology, Saarland University, Saarbrücken, Germany
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7
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Stierwalt HD, Ehrlicher SE, Bergman BC, Robinson MM, Newsom SA. Insulin-stimulated Rac1-GTP binding is not impaired by palmitate treatment in L6 myotubes. Physiol Rep 2018; 6:e13956. [PMID: 30592185 PMCID: PMC6308110 DOI: 10.14814/phy2.13956] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 11/28/2018] [Indexed: 01/01/2023] Open
Abstract
Ras-related C3 botulinum toxin substrate 1 (Rac1) is required for normal insulin-stimulated glucose transport in skeletal muscle and evidence indicates Rac1 may be negatively regulated by lipids. We investigated if insulin-stimulated activation of Rac1 (i.e., Rac1-GTP binding) is impaired by accumulation of diacylglycerols (DAG) and ceramides in cultured muscle cells. Treating L6 myotubes with 100 nmol/L insulin resulted in increased Rac1-GTP binding that was rapid (occurring within 2 min), relatively modest (+38 ± 19% vs. basal, P < 0.001), and short-lived, returning to near-basal levels within 15 min of continuous treatment. Incubating L6 myotubes overnight in 500 μmol/L palmitate increased the accumulation of DAG and ceramides (P < 0.05 vs. no fatty acid control). Despite significant accumulation of lipids, insulin-stimulated Rac1-GTP binding was not impaired during palmitate treatment (P = 0.39 vs. no fatty acid control). Nevertheless, phosphorylation of Rac1 effector protein p21-activated kinase (PAK) was attenuated in response to palmitate treatment (P = 0.02 vs. no fatty acid control). Palmitate treatment also increased inhibitory phosphorylation of insulin receptor substrate-1 and attenuated insulin-stimulated phosphorylation of Akt at both Thr308 and Ser473 (all P < 0.05 vs. no fatty acid control). Such signaling impairments resulted in near complete inhibition of insulin-stimulated translocation of glucose transporter protein 4 (GLUT4; P = 0.10 vs. basal during palmitate treatment). In summary, our finding suggests that Rac1 may not undergo negative regulation by DAG or ceramides. We instead provide evidence that attenuated PAK phosphorylation and impaired GLUT4 translocation during palmitate-induced insulin resistance can occur independent of defects in insulin-stimulated Rac1-GTP binding.
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Affiliation(s)
- Harrison D. Stierwalt
- School of Biological and Population Health SciencesCollege of Public Health and Human SciencesOregon State UniversityCorvallisOregon
| | - Sarah E. Ehrlicher
- School of Biological and Population Health SciencesCollege of Public Health and Human SciencesOregon State UniversityCorvallisOregon
| | - Bryan C. Bergman
- Division of Endocrinology, Metabolism and DiabetesSchool of MedicineUniversity of Colorado DenverDenverColorado
| | - Matthew M. Robinson
- School of Biological and Population Health SciencesCollege of Public Health and Human SciencesOregon State UniversityCorvallisOregon
| | - Sean A. Newsom
- School of Biological and Population Health SciencesCollege of Public Health and Human SciencesOregon State UniversityCorvallisOregon
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8
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Acclimation of C2C12 myoblasts to physiological glucose concentrations for in vitro diabetes research. Life Sci 2018; 211:238-244. [DOI: 10.1016/j.lfs.2018.09.041] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 09/19/2018] [Accepted: 09/21/2018] [Indexed: 12/17/2022]
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9
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Hsu CP, Moghadaszadeh B, Hartwig JH, Beggs AH. Sarcomeric and nonmuscle α-actinin isoforms exhibit differential dynamics at skeletal muscle Z-lines. Cytoskeleton (Hoboken) 2018; 75:213-228. [PMID: 29518289 PMCID: PMC5943145 DOI: 10.1002/cm.21442] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 03/02/2018] [Accepted: 03/05/2018] [Indexed: 01/12/2023]
Abstract
The α-actinin proteins are a highly conserved family of actin crosslinkers that mediate interactions between several cytoskeletal and sarcomeric proteins. Nonsarcomeric α-actinin-1 and α-actinin-4 crosslink actin filaments in the cytoskeleton, while sarcomeric α-actinin-2 and α-actinin-3 serve a crucial role in anchoring actin filaments to the muscle Z-line. To assess the difference in turnover dynamics and structure/function properties between the α-actinin isoforms at the sarcomeric Z-line, we used Fluorescence Recovery After Photobleaching (FRAP) in primary myofiber cultures. We found that the recovery kinetics of these proteins followed three distinct patterns: α-actinin-2/α-actinin-3 had the slowest turn over, α-actinin-1 recovered to an intermediate degree, and α-actinin-4 had the fastest recovery. Interestingly, the isoforms' patterns of recovery were reversed at adhesion plaques in fibroblasts. This disparity suggests that the different α-actinin isoforms have unique association kinetics in myofibers and that nonmuscle isoform interactions are more dynamic at the sarcomeric Z-line. Protein domain-specific investigations using α-actinin-2/4 chimeric proteins showed that differential dynamics between sarcomeric and nonmuscle isoforms are regulated by cooperative interactions between the N-terminal actin-binding domain, the spectrin-like linker region and the C-terminal calmodulin-like EF hand domain. Together, these findings demonstrate that α-actinin isoforms are unique in binding dynamics at the Z-line and suggest differentially evolved interactive and Z-line association capabilities of each functional domain.
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Affiliation(s)
- Cynthia P Hsu
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Behzad Moghadaszadeh
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - John H Hartwig
- Translational Medicine Division, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Alan H Beggs
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children’s Hospital, Harvard Medical School, Boston, MA 02115, USA
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10
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Liu Y, Russell SJ, Schneider MF. Foxo1 nucleo-cytoplasmic distribution and unidirectional nuclear influx are the same in nuclei in a single skeletal muscle fiber but vary between fibers. Am J Physiol Cell Physiol 2017; 314:C334-C348. [PMID: 29187365 DOI: 10.1152/ajpcell.00168.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Foxo transcription factors promote protein breakdown and atrophy of skeletal muscle fibers. Foxo transcriptional effectiveness is largely determined by phosphorylation-dependent nucleo-cytoplasmic shuttling. Imaging Foxo1-green fluorescent protein (GFP) over time in 124 nuclei in 68 multinucleated adult skeletal muscle fibers under control culture conditions reveals large variability between fibers in Foxo1-GFP nucleo-cytoplasmic concentration ratio (N/C) and in the apparent rate coefficient ( kI') for Foxo1-GFP unidirectional nuclear influx (measured with efflux blocked by leptomycin B). Pairs of values of N/C or of kI' from different nuclei in the same fiber were essentially the same, but only weakly correlated in nuclei from different fibers in the same culture well. Thus, fiber to fiber variability of cellular factors, but not extracellular factors, determines Foxo1 distribution. Over all nuclei, N/C and kI' were closely proportional, indicating that kI' is the major determinant of Foxo1 distribution. IGF-I activation of Foxo kinase Akt reduces variability by decreasing kI' and N/C in all fibers. However, inhibiting Akt did not drive kI' uniformly high, indicating other pathways in Foxo1 regulation.
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Affiliation(s)
- Yewei Liu
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine , Baltimore, Maryland
| | - Sarah J Russell
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine , Baltimore, Maryland
| | - Martin F Schneider
- Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine , Baltimore, Maryland
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11
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Fernández-Verdejo R, Vanwynsberghe AM, Hai T, Deldicque L, Francaux M. Activating transcription factor 3 regulates chemokine expression in contracting C 2C 12 myotubes and in mouse skeletal muscle after eccentric exercise. Biochem Biophys Res Commun 2017; 492:249-254. [PMID: 28822763 DOI: 10.1016/j.bbrc.2017.08.059] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 08/15/2017] [Indexed: 01/05/2023]
Abstract
Activating transcription factor (ATF) 3 regulates chemokine expression in various cell types and tissues. Herein, we studied this regulation in contracting muscle cells in vitro, and in skeletal muscle after muscle-damaging exercise in vivo. C2C12 myotubes with normal or low ATF3 levels (atf3_siRNA) were electrically stimulated (EPS). Also, ATF3-knockout (ATF3-KO) and control mice ran downhill until exhaustion, and muscles were analyzed post-exercise. EPS increased ATF3 levels in myotubes (P < 0.01). Chemokine C-C motif ligand (ccl) 2 mRNA increased post-EPS, but atf3_siRNA attenuated the response (P < 0.05). Atf3_siRNA up-regulated ccl6 basal mRNA, and down-regulated ccl9 and chemokine C-X-C motif ligand (cxcl) 1 basal mRNAs. Post-exercise, ATF3-KO mice showed exacerbated mRNA levels of ccl6 and ccl9 in soleus (P < 0.05), and similar trends were observed for ccl2 and interleukin (il) 1β (P < 0.09). In quadriceps, il6 mRNA level increased only in ATF3-KO (P < 0.05), and cxcl1 mRNA showed a similar trend (P = 0.082). Cluster of differentiation-68 (cd68) mRNA, a macrophage marker, increased in quadriceps and soleus independently of genotype (P < 0.001). Our data demonstrate that ATF3 regulates chemokine expression in muscle cells in vitro and skeletal muscle in vivo, but the regulation differs in each model. Cells other than myofibers may thus participate in the response observed in skeletal muscle. Our results also indicate that ATF3-independent mechanisms would regulate macrophage infiltration upon muscle-damaging exercise. The implications of chemokine regulation in skeletal muscle remain to be determined.
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Affiliation(s)
- R Fernández-Verdejo
- Institute of Neuroscience, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - A M Vanwynsberghe
- Institute of Neuroscience, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - T Hai
- Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA
| | - L Deldicque
- Institute of Neuroscience, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
| | - M Francaux
- Institute of Neuroscience, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.
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12
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Ohtsubo H, Sato Y, Suzuki T, Mizunoya W, Nakamura M, Tatsumi R, Ikeuchi Y. Data supporting possible implication of APOBEC2 in self-renewal functions of myogenic stem satellite cells: Toward understanding the negative regulation of myoblast differentiation. Data Brief 2017; 12:269-273. [PMID: 28462365 PMCID: PMC5403764 DOI: 10.1016/j.dib.2017.03.051] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2017] [Revised: 03/21/2017] [Accepted: 03/31/2017] [Indexed: 11/19/2022] Open
Abstract
This paper provides in vitro phenotypical data to show that APOBEC2, a member of apoB mRNA editing enzyme, catalytic polypeptide-like family, may implicate in self-renewal functions of myogenic stem satellite cells, namely in the re-establishment of quiescent status after activation and proliferation of myoblasts in single-myofiber culture.
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Affiliation(s)
- Hideaki Ohtsubo
- Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
| | - Yusuke Sato
- Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
- Department of Bio-Productive Science, Utsunomiya University, Utsunomiya, Tochigi 321-8505, Japan
| | - Takahiro Suzuki
- Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
- Department of Molecular and Developmental Biology, Kawasaki Medical School, Kurashiki, Okayama 701-0192, Japan
| | - Wataru Mizunoya
- Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
| | - Mako Nakamura
- Graduate School of Agriculture, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
| | - Ryuichi Tatsumi
- Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
- Correspondence to: Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan. Fax: +81 92 642 2951.
| | - Yoshihide Ikeuchi
- Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
- Correspondence to: Department of Animal and Marine Bioresource Sciences, Graduate School of Agriculture, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan. Fax: +81 92 642 2951.
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13
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Hernández-Ochoa EO, Vanegas C, Iyer SR, Lovering RM, Schneider MF. Alternating bipolar field stimulation identifies muscle fibers with defective excitability but maintained local Ca(2+) signals and contraction. Skelet Muscle 2016; 6:6. [PMID: 26855765 PMCID: PMC4743112 DOI: 10.1186/s13395-016-0076-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 01/05/2016] [Indexed: 11/25/2022] Open
Abstract
Background Most cultured enzymatically dissociated adult myofibers exhibit spatially uniform (UNI) contractile responses and Ca2+ transients over the entire myofiber in response to electric field stimuli of either polarity applied via bipolar electrodes. However, some myofibers only exhibit contraction and Ca2+ transients at alternating (ALT) ends in response to alternating polarity field stimulation. Here, we present for the first time the methodology for identification of ALT myofibers in primary cultures and isolated muscles, as well as a study of their electrophysiological properties. Results We used high-speed confocal microscopic Ca2+ imaging, electric field stimulation, microelectrode recordings, immunostaining, and confocal microscopy to characterize the properties of action potential-induced Ca2+ transients, contractility, resting membrane potential, and staining of T-tubule voltage-gated Na+ channel distribution applied to cultured adult myofibers. Here, we show for the first time, with high temporal and spatial resolution, that normal control myofibers with UNI responses can be converted to ALT response myofibers by TTX addition or by removal of Na+ from the bathing medium, with reappearance of the UNI response on return of Na+. Our results suggest disrupted excitability as the cause of ALT behavior and indicate that the ALT response is due to local depolarization-induced Ca2+ release, whereas the UNI response is triggered by action potential propagation over the entire myofiber. Consistent with this interpretation, local depolarizing monopolar stimuli give uniform (propagated) responses in UNI myofibers, but only local responses at the electrode in ALT myofibers. The ALT responses in electrically inexcitable myofibers are consistent with expectations of current spread between bipolar stimulating electrodes, entering (hyperpolarizing) one end of a myofiber and leaving (depolarizing) the other end of the myofiber. ALT responses were also detected in some myofibers within intact isolated whole muscles from wild-type and MDX mice, demonstrating that ALT responses can be present before enzymatic dissociation. Conclusions We suggest that checking for ALT myofiber responsiveness by looking at the end of a myofiber during alternating polarity stimuli provides a test for compromised excitability of myofibers, and could be used to identify inexcitable, damaged or diseased myofibers by ALT behavior in healthy and diseased muscle. Electronic supplementary material The online version of this article (doi:10.1186/s13395-016-0076-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Erick O Hernández-Ochoa
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, 108 N. Greene Street, Baltimore, MD 21201 USA
| | - Camilo Vanegas
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, 108 N. Greene Street, Baltimore, MD 21201 USA
| | - Shama R Iyer
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Richard M Lovering
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, MD 21201 USA
| | - Martin F Schneider
- Department of Biochemistry and Molecular Biology, School of Medicine, University of Maryland, Baltimore, 108 N. Greene Street, Baltimore, MD 21201 USA
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14
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Lo HP, Nixon SJ, Hall TE, Cowling BS, Ferguson C, Morgan GP, Schieber NL, Fernandez-Rojo MA, Bastiani M, Floetenmeyer M, Martel N, Laporte J, Pilch PF, Parton RG. The caveolin-cavin system plays a conserved and critical role in mechanoprotection of skeletal muscle. J Cell Biol 2015; 210:833-49. [PMID: 26323694 PMCID: PMC4555827 DOI: 10.1083/jcb.201501046] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The caveolar membrane microdomain plays an integral role in stabilizing the muscle fiber surface in mice and zebrafish. Dysfunction of caveolae is involved in human muscle disease, although the underlying molecular mechanisms remain unclear. In this paper, we have functionally characterized mouse and zebrafish models of caveolae-associated muscle disease. Using electron tomography, we quantitatively defined the unique three-dimensional membrane architecture of the mature muscle surface. Caveolae occupied around 50% of the sarcolemmal area predominantly assembled into multilobed rosettes. These rosettes were preferentially disassembled in response to increased membrane tension. Caveola-deficient cavin-1−/− muscle fibers showed a striking loss of sarcolemmal organization, aberrant T-tubule structures, and increased sensitivity to membrane tension, which was rescued by muscle-specific Cavin-1 reexpression. In vivo imaging of live zebrafish embryos revealed that loss of muscle-specific Cavin-1 or expression of a dystrophy-associated Caveolin-3 mutant both led to sarcolemmal damage but only in response to vigorous muscle activity. Our findings define a conserved and critical role in mechanoprotection for the unique membrane architecture generated by the caveolin–cavin system.
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Affiliation(s)
- Harriet P Lo
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Susan J Nixon
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Thomas E Hall
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Belinda S Cowling
- Department of Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Institut National de la Santé et de la Recherche Médicale U964, Centre National de la Recherche Scientifique UMR7104, Strasbourg University, Illkirch 67404, France
| | - Charles Ferguson
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia Center for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Garry P Morgan
- Center for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nicole L Schieber
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Manuel A Fernandez-Rojo
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Michele Bastiani
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Matthias Floetenmeyer
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia Center for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Nick Martel
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Jocelyn Laporte
- Department of Translational Medicine and Neurogenetics, Institut de Génétique et de Biologie Moléculaire et Cellulaire, Institut National de la Santé et de la Recherche Médicale U964, Centre National de la Recherche Scientifique UMR7104, Strasbourg University, Illkirch 67404, France
| | - Paul F Pilch
- Department of Biochemistry, Boston University School of Medicine, Boston, MA 02118
| | - Robert G Parton
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Queensland 4072, Australia Center for Microscopy and Microanalysis, The University of Queensland, Brisbane, Queensland 4072, Australia
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15
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Primary Murine Myotubes as a Model for Investigating Muscular Dystrophy. BIOMED RESEARCH INTERNATIONAL 2015; 2015:594751. [PMID: 26380282 PMCID: PMC4561302 DOI: 10.1155/2015/594751] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Accepted: 03/11/2015] [Indexed: 11/18/2022]
Abstract
Muscular dystrophies caused by defects in various genes are often associated with impairment of calcium homeostasis. Studies of calcium currents are hampered because of the lack of a robust cellular model. Primary murine myotubes, formed upon satellite cell fusion, were examined for their utilization as a model of adult skeletal muscle. We enzymatically isolated satellite cells and induced them to differentiation to myotubes. Myotubes displayed morphological and physiological properties resembling adult muscle fibers. Desmin and myosin heavy chain immunoreactivity in the differentiated myotubes were similar to the mature muscle cross-striated pattern. The myotubes responded to electrical and chemical stimulations with sarcoplasmic reticulum calcium release. Presence of L-type calcium channels in the myotubes sarcolemma was confirmed via whole-cell patch-clamp technique. To assess the use of myotubes for studying functional mutation effects lentiviral transduction was applied. Satellite cells easily underwent transduction and were able to retain a positive expression of lentivirally encoded GFP up to and after the formation of myotubes, without changes in their physiological and morphological properties. Thus, we conclude that murine myotubes may serve as a fruitful cell model for investigating calcium homeostasis in muscular dystrophy and the effects of gene modifications can be assessed due to lentiviral transduction.
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16
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Hernández-Ochoa EO, Pratt SJP, Garcia-Pelagio KP, Schneider MF, Lovering RM. Disruption of action potential and calcium signaling properties in malformed myofibers from dystrophin-deficient mice. Physiol Rep 2015; 3:3/4/e12366. [PMID: 25907787 PMCID: PMC4425971 DOI: 10.14814/phy2.12366] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Duchenne muscular dystrophy (DMD), the most common and severe muscular dystrophy, is caused by the absence of dystrophin. Muscle weakness and fragility (i.e., increased susceptibility to damage) are presumably due to structural instability of the myofiber cytoskeleton, but recent studies suggest that the increased presence of malformed/branched myofibers in dystrophic muscle may also play a role. We have previously studied myofiber morphology in healthy wild-type (WT) and dystrophic (MDX) skeletal muscle. Here, we examined myofiber excitability using high-speed confocal microscopy and the voltage-sensitive indicator di-8-butyl-amino-naphthyl-ethylene-pyridinium-propyl-sulfonate (di-8-ANEPPS) to assess the action potential (AP) properties. We also examined AP-induced Ca2+ transients using high-speed confocal microscopy with rhod-2, and assessed sarcolemma fragility using elastimetry. AP recordings showed an increased width and time to peak in malformed MDX myofibers compared to normal myofibers from both WT and MDX, but no significant change in AP amplitude. Malformed MDX myofibers also exhibited reduced AP-induced Ca2+ transients, with a further Ca2+ transient reduction in the branches of malformed MDX myofibers. Mechanical studies indicated an increased sarcolemma deformability and instability in malformed MDX myofibers. The data suggest that malformed myofibers are functionally different from myofibers with normal morphology. The differences seen in AP properties and Ca2+ signals suggest changes in excitability and remodeling of the global Ca2+ signal, both of which could underlie reported weakness in dystrophic muscle. The biomechanical changes in the sarcolemma support the notion that malformed myofibers are more susceptible to damage. The high prevalence of malformed myofibers in dystrophic muscle may contribute to the progressive strength loss and fragility seen in dystrophic muscles.
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Affiliation(s)
- Erick O Hernández-Ochoa
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Stephen J P Pratt
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
| | - Karla P Garcia-Pelagio
- Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Martin F Schneider
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Baltimore, Maryland
| | - Richard M Lovering
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, Maryland
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17
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Komiya Y, Anderson JE, Akahoshi M, Nakamura M, Tatsumi R, Ikeuchi Y, Mizunoya W. Protocol for rat single muscle fiber isolation and culture. Anal Biochem 2015; 482:22-4. [PMID: 25912416 DOI: 10.1016/j.ab.2015.03.034] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Revised: 03/20/2015] [Accepted: 03/24/2015] [Indexed: 11/19/2022]
Abstract
To attain a superior in vitro model of mature muscle fibers, we modified the established protocol for isolating single muscle fibers from rat skeletal muscle. Muscle fiber cultures with high viability were obtained using flexor digitorum brevis muscle and lasted for at least 7 days. We compared the expression levels of adult myosin heavy chain (MyHC) isoforms in these single muscle fibers with myotubes formed from myoblasts; isolated fibers contained markedly more abundant adult MyHC isoforms than myotubes. This muscle fiber model, therefore, will be useful for studying the various functions and cellular processes of mature muscles in vitro.
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Affiliation(s)
- Yusuke Komiya
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan
| | - Judy E Anderson
- Department of Biological Sciences, University of Manitoba, Winnipeg, Manitoba R3T 2N2, Canada
| | - Mariko Akahoshi
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan
| | - Mako Nakamura
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan
| | - Ryuichi Tatsumi
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan
| | - Yoshihide Ikeuchi
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan
| | - Wataru Mizunoya
- Department of Bioresource Sciences, Faculty of Agriculture, Kyushu University, Higashi-ku, Fukuoka 812-8581, Japan.
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18
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Cabrera-Serrano M, Ghaoui R, Ravenscroft G, Johnsen RD, Davis MR, Corbett A, Reddel S, Sue CM, Liang C, Waddell LB, Kaur S, Lek M, North KN, MacArthur DG, Lamont PJ, Clarke NF, Laing NG. Expanding the phenotype of GMPPB mutations. ACTA ACUST UNITED AC 2015; 138:836-44. [PMID: 25681410 DOI: 10.1093/brain/awv013] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Dystroglycanopathies are a heterogeneous group of diseases with a broad phenotypic spectrum ranging from severe disorders with congenital muscle weakness, eye and brain structural abnormalities and intellectual delay to adult-onset limb-girdle muscular dystrophies without mental retardation. Most frequently the disease onset is congenital or during childhood. The exception is FKRP mutations, in which adult onset is a common presentation. Here we report eight patients from five non-consanguineous families where next generation sequencing identified mutations in the GMPPB gene. Six patients presented as an adult or adolescent-onset limb-girdle muscular dystrophy, one presented with isolated episodes of rhabdomyolysis, and one as a congenital muscular dystrophy. This report expands the phenotypic spectrum of GMPPB mutations to include limb-girdle muscular dystrophies with adult onset with or without intellectual disability, or isolated rhabdomyolysis.
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Affiliation(s)
- Macarena Cabrera-Serrano
- 1 Centre for Medical Research, University of Western Australia, Harry Perkins Institute of Medical Research, Perth, WA, Australia 2 Instituto de Biomedicina de Sevilla, Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, Seville, Spain
| | - Roula Ghaoui
- 3 Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia 4 Discipline of Paediatrics and Child Health, University of Sydney, Sydney, NSW 2006, Australia 5 Department of Neurology, Royal North Shore Hospital, Sydney, Australia
| | - Gianina Ravenscroft
- 1 Centre for Medical Research, University of Western Australia, Harry Perkins Institute of Medical Research, Perth, WA, Australia
| | - Russell D Johnsen
- 6 Centre for Comparative Genomics, Murdoch University, Perth, Australia
| | - Mark R Davis
- 7 Department of Diagnostic Genomics, Pathwest Laboratory Medicine WA. Perth, WA, Australia
| | - Alastair Corbett
- 8 Department of Neurology, Concord Repatriation Hospital, and Sydney Medical School, Sydney, Australia
| | - Stephen Reddel
- 8 Department of Neurology, Concord Repatriation Hospital, and Sydney Medical School, Sydney, Australia
| | - Carolyn M Sue
- 5 Department of Neurology, Royal North Shore Hospital, Sydney, Australia
| | - Christina Liang
- 5 Department of Neurology, Royal North Shore Hospital, Sydney, Australia
| | - Leigh B Waddell
- 3 Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia 4 Discipline of Paediatrics and Child Health, University of Sydney, Sydney, NSW 2006, Australia
| | - Simranpreet Kaur
- 3 Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Monkol Lek
- 3 Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia 4 Discipline of Paediatrics and Child Health, University of Sydney, Sydney, NSW 2006, Australia 9 Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA 02114, USA 10 Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Kathryn N North
- 3 Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia 11 Murdoch Children's Research Institute, The Royal Children's Hospital, Parkville, Victoria, Australia 12 Department of Paediatrics, University of Melbourne, Victoria, Australia
| | - Daniel G MacArthur
- 9 Analytic and Translational Genetics Unit, Massachusetts General Hospital, Boston, MA 02114, USA 10 Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Phillipa J Lamont
- 13 Neurogenetic Unit, Department of Neurology, Royal Perth Hospital, Perth, WA, Australia
| | - Nigel F Clarke
- 3 Institute for Neuroscience and Muscle Research, The Children's Hospital at Westmead, Sydney, NSW 2145, Australia 4 Discipline of Paediatrics and Child Health, University of Sydney, Sydney, NSW 2006, Australia
| | - Nigel G Laing
- 1 Centre for Medical Research, University of Western Australia, Harry Perkins Institute of Medical Research, Perth, WA, Australia
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19
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Analysis of beat fluctuations and oxygen consumption in cardiomyocytes by scanning electrochemical microscopy. Anal Biochem 2014; 447:39-42. [DOI: 10.1016/j.ab.2013.11.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 10/18/2013] [Accepted: 11/07/2013] [Indexed: 11/19/2022]
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20
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Establishment of a human skeletal muscle-derived cell line: biochemical, cellular and electrophysiological characterization. Biochem J 2013; 455:169-77. [PMID: 23905709 DOI: 10.1042/bj20130698] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Excitation-contraction coupling is the physiological mechanism occurring in muscle cells whereby an electrical signal sensed by the dihydropyridine receptor located on the transverse tubules is transformed into a chemical gradient (Ca2+ increase) by activation of the ryanodine receptor located on the sarcoplasmic reticulum membrane. In the present study, we characterized for the first time the excitation-contraction coupling machinery of an immortalized human skeletal muscle cell line. Intracellular Ca2+ measurements showed a normal response to pharmacological activation of the ryanodine receptor, whereas 3D-SIM (super-resolution structured illumination microscopy) revealed a low level of structural organization of ryanodine receptors and dihydropyridine receptors. Interestingly, the expression levels of several transcripts of proteins involved in Ca2+ homoeostasis and differentiation indicate that the cell line has a phenotype closer to that of slow-twitch than fast-twitch muscles. These results point to the potential application of such human muscle-derived cell lines to the study of neuromuscular disorders; in addition, they may serve as a platform for the development of therapeutic strategies aimed at correcting defects in Ca2+ homoeostasis due to mutations in genes involved in Ca2+ regulation.
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21
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Mutations in KLHL40 are a frequent cause of severe autosomal-recessive nemaline myopathy. Am J Hum Genet 2013; 93:6-18. [PMID: 23746549 DOI: 10.1016/j.ajhg.2013.05.004] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 04/25/2013] [Accepted: 05/03/2013] [Indexed: 11/22/2022] Open
Abstract
Nemaline myopathy (NEM) is a common congenital myopathy. At the very severe end of the NEM clinical spectrum are genetically unresolved cases of autosomal-recessive fetal akinesia sequence. We studied a multinational cohort of 143 severe-NEM-affected families lacking genetic diagnosis. We performed whole-exome sequencing of six families and targeted gene sequencing of additional families. We identified 19 mutations in KLHL40 (kelch-like family member 40) in 28 apparently unrelated NEM kindreds of various ethnicities. Accounting for up to 28% of the tested individuals in the Japanese cohort, KLHL40 mutations were found to be the most common cause of this severe form of NEM. Clinical features of affected individuals were severe and distinctive and included fetal akinesia or hypokinesia and contractures, fractures, respiratory failure, and swallowing difficulties at birth. Molecular modeling suggested that the missense substitutions would destabilize the protein. Protein studies showed that KLHL40 is a striated-muscle-specific protein that is absent in KLHL40-associated NEM skeletal muscle. In zebrafish, klhl40a and klhl40b expression is largely confined to the myotome and skeletal muscle, and knockdown of these isoforms results in disruption of muscle structure and loss of movement. We identified KLHL40 mutations as a frequent cause of severe autosomal-recessive NEM and showed that it plays a key role in muscle development and function. Screening of KLHL40 should be a priority in individuals who are affected by autosomal-recessive NEM and who present with prenatal symptoms and/or contractures and in all Japanese individuals with severe NEM.
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22
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Sylow L, Jensen TE, Kleinert M, Højlund K, Kiens B, Wojtaszewski J, Prats C, Schjerling P, Richter EA. Rac1 signaling is required for insulin-stimulated glucose uptake and is dysregulated in insulin-resistant murine and human skeletal muscle. Diabetes 2013; 62:1865-75. [PMID: 23423567 PMCID: PMC3661612 DOI: 10.2337/db12-1148] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The actin cytoskeleton-regulating GTPase Rac1 is required for insulin-stimulated GLUT4 translocation in cultured muscle cells. However, involvement of Rac1 and its downstream signaling in glucose transport in insulin-sensitive and insulin-resistant mature skeletal muscle has not previously been investigated. We hypothesized that Rac1 and its downstream target, p21-activated kinase (PAK), are regulators of insulin-stimulated glucose uptake in mouse and human skeletal muscle and are dysregulated in insulin-resistant states. Muscle-specific inducible Rac1 knockout (KO) mice and pharmacological inhibition of Rac1 were used to determine whether Rac1 regulates insulin-stimulated glucose transport in mature skeletal muscle. Furthermore, Rac1 and PAK1 expression and signaling were investigated in muscle of insulin-resistant mice and humans. Inhibition and KO of Rac1 decreased insulin-stimulated glucose transport in mouse soleus and extensor digitorum longus muscles ex vivo. Rac1 KO mice showed decreased insulin and glucose tolerance and trended toward higher plasma insulin concentrations after intraperitoneal glucose injection. Rac1 protein expression and insulin-stimulated PAK(Thr423) phosphorylation were decreased in muscles of high fat-fed mice. In humans, insulin-stimulated PAK activation was decreased in both acute insulin-resistant (intralipid infusion) and chronic insulin-resistant states (obesity and diabetes). These findings show that Rac1 is a regulator of insulin-stimulated glucose uptake and a novel candidate involved in skeletal muscle insulin resistance.
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Affiliation(s)
- Lykke Sylow
- Molecular Physiology Group, Department of Nutrition, Exercise, and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E. Jensen
- Molecular Physiology Group, Department of Nutrition, Exercise, and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Maximilian Kleinert
- Molecular Physiology Group, Department of Nutrition, Exercise, and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Kurt Højlund
- Diabetes Research Center, Department of Endocrinology, Odense University Hospital, Odense, Denmark
| | - Bente Kiens
- Molecular Physiology Group, Department of Nutrition, Exercise, and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Jørgen Wojtaszewski
- Molecular Physiology Group, Department of Nutrition, Exercise, and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
| | - Clara Prats
- Department of Biomedical Sciences, Center of Healthy Aging, University of Copenhagen, Copenhagen, Denmark
| | - Peter Schjerling
- Institute of Sports Medicine, Department of Orthopedic Surgery, Bispebjerg Hospital and Center for Healthy Aging, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Erik A. Richter
- Molecular Physiology Group, Department of Nutrition, Exercise, and Sports, August Krogh Centre, University of Copenhagen, Copenhagen, Denmark
- Corresponding author: Erik A. Richter,
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23
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Moghadaszadeh B, Rider BE, Lawlor MW, Childers MK, Grange RW, Gupta K, Boukedes SS, Owen CA, Beggs AH. Selenoprotein N deficiency in mice is associated with abnormal lung development. FASEB J 2013; 27:1585-99. [PMID: 23325319 DOI: 10.1096/fj.12-212688] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Mutations in the human SEPN1 gene, encoding selenoprotein N (SepN), cause SEPN1-related myopathy (SEPN1-RM) characterized by muscle weakness, spinal rigidity, and respiratory insufficiency. As with other members of the selenoprotein family, selenoprotein N incorporates selenium in the form of selenocysteine (Sec). Most selenoproteins that have been functionally characterized are involved in oxidation-reduction (redox) reactions, with the Sec residue located at their catalytic site. To model SEPN1-RM, we generated a Sepn1-knockout (Sepn1(-/-)) mouse line. Homozygous Sepn1(-/-) mice are fertile, and their weight and lifespan are comparable to wild-type (WT) animals. Under baseline conditions, the muscle histology of Sepn1(-/-) mice remains normal, but subtle core lesions could be detected in skeletal muscle after inducing oxidative stress. Ryanodine receptor (RyR) calcium release channels showed lower sensitivity to caffeine in SepN deficient myofibers, suggesting a possible role of SepN in RyR regulation. SepN deficiency also leads to abnormal lung development characterized by enlarged alveoli, which is associated with decreased tissue elastance and increased quasi-static compliance of Sepn1(-/-) lungs. This finding raises the possibility that the respiratory syndrome observed in patients with SEPN1 mutations may have a primary pulmonary component in addition to the weakness of respiratory muscles.
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Affiliation(s)
- Behzad Moghadaszadeh
- Division of Genetics, The Manton Center for Orphan Disease Research, Boston Children's Hospital, Boston, MA 02115, USA
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24
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Goodall MH, Ward CW, Pratt SJP, Bloch RJ, Lovering RM. Structural and functional evaluation of branched myofibers lacking intermediate filaments. Am J Physiol Cell Physiol 2012; 303:C224-32. [PMID: 22592402 DOI: 10.1152/ajpcell.00136.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Intermediate filaments (IFs), composed of desmin and keratins, link myofibrils to each other and to the sarcolemma in skeletal muscle. Fast-twitch muscle of mice lacking the IF proteins, desmin and keratin 19 (K19), showed reduced specific force and increased susceptibility to injury in earlier studies. Here we tested the hypothesis that the number of malformed myofibers in mice lacking desmin (Des(-/-)), keratin 19 (K19(-/-)), or both IF proteins (double knockout, DKO) is increased and is coincident with altered excitation-contraction (EC) coupling Ca(2+) kinetics, as reported for mdx mice. We quantified the number of branched myofibers, characterized their organization with confocal and electron microscopy (EM), and compared the Ca(2+) kinetics of EC coupling in flexor digitorum brevis myofibers from adult Des(-/-), K19(-/-), or DKO mice and compared them to age-matched wild type (WT) and mdx myofibers. Consistent with our previous findings, 9.9% of mdx myofibers had visible malformations. Des(-/-) myofibers had more malformations (4.7%) than K19(-/-) (0.9%) or DKO (1.3%) myofibers. Confocal and EM imaging revealed no obvious changes in sarcomere misalignment at the branch points, and the neuromuscular junctions in the mutant mice, while more variably located, were limited to one per myofiber. Global, electrically evoked Ca(2+) signals showed a decrease in the rate of Ca(2+) uptake (decay rate) into the sarcoplasmic reticulum after Ca(2+) release, with the most profound effect in branched DKO myofibers (44% increase in uptake relative to WT). Although branched DKO myofibers showed significantly faster rates of Ca(2+) clearance, the milder branching phenotype observed in DKO muscle suggests that the absence of K19 corrects the defect created by the absence of desmin alone. Thus, there are complex roles for desmin-based and K19-based IFs in skeletal muscle, with the null and DKO mutations having different effects on Ca(2+) reuptake and myofiber branching.
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Affiliation(s)
- Mariah H Goodall
- Department of Orthopaedics, University of Maryland School of Medicine, Baltimore, 21201, USA
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25
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Anderson JE, Wozniak AC, Mizunoya W. Single muscle-fiber isolation and culture for cellular, molecular, pharmacological, and evolutionary studies. Methods Mol Biol 2012; 798:85-102. [PMID: 22130833 DOI: 10.1007/978-1-61779-343-1_6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
The technique of single muscle-fiber cultures has already proven valuable in extending knowledge of myogenesis, stem cell heterogeneity, the stem cell niche in skeletal muscle, and satellite cell activation. This report reviews the background of the model and applications, and details the procedures of muscle dissection, fiber digestion and isolation, cleaning the fiber preparation, plating fibers, and extensions of the technique for studying activation from stable quiescence of satellite cells, mRNA expression by in situ hybridization and regulation of satellite cell activation in zebrafish muscle by nitric oxide, hepatocyte growth factor.
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Affiliation(s)
- Judy E Anderson
- Department of Biological Sciences, Department of Human Anatomy and Cell Science, University of Manitoba, Winnipeg, MB, Canada.
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26
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Tomasi M, Canato M, Paolini C, Dainese M, Reggiani C, Volpe P, Protasi F, Nori A. Calsequestrin (CASQ1) rescues function and structure of calcium release units in skeletal muscles of CASQ1-null mice. Am J Physiol Cell Physiol 2011; 302:C575-86. [PMID: 22049211 DOI: 10.1152/ajpcell.00119.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amplitude of Ca(2+) transients, ultrastructure of Ca(2+) release units, and molecular composition of sarcoplasmic reticulum (SR) are altered in fast-twitch skeletal muscles of calsequestrin-1 (CASQ1)-null mice. To determine whether such changes are directly caused by CASQ1 ablation or are instead the result of adaptive mechanisms, here we assessed ability of CASQ1 in rescuing the null phenotype. In vivo reintroduction of CASQ1 was carried out by cDNA electro transfer in flexor digitorum brevis muscle of the mouse. Exogenous CASQ1 was found to be correctly targeted to the junctional SR (jSR), as judged by immunofluorescence and confocal microscopy; terminal cisternae (TC) lumen was filled with electron dense material and its width was significantly increased, as judged by electron microscopy; peak amplitude of Ca(2+) transients was significantly increased compared with null muscle fibers transfected only with green fluorescent protein (control); and finally, transfected fibers were able to sustain cytosolic Ca(2+) concentration during prolonged tetanic stimulation. Only the expression of TC proteins, such as calsequestrin 2, sarcalumenin, and triadin, was not rescued as judged by Western blot. Thus our results support the view that CASQ1 plays a key role in both Ca(2+) homeostasis and TC structure.
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Affiliation(s)
- Mirta Tomasi
- Dept. of Experimental Biomedical Sciences, Univ. of Padova, Italy
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27
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Baltgalvis KA, Jaeger MA, Fitzsimons DP, Thayer SA, Lowe DA, Ervasti JM. Transgenic overexpression of γ-cytoplasmic actin protects against eccentric contraction-induced force loss in mdx mice. Skelet Muscle 2011; 1:32. [PMID: 21995957 PMCID: PMC3214766 DOI: 10.1186/2044-5040-1-32] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2011] [Accepted: 10/13/2011] [Indexed: 11/22/2022] Open
Abstract
Background γ-cytoplasmic (γ-cyto) actin levels are elevated in dystrophin-deficient mdx mouse skeletal muscle. The purpose of this study was to determine whether further elevation of γ-cyto actin levels improve or exacerbate the dystrophic phenotype of mdx mice. Methods We transgenically overexpressed γ-cyto actin, specifically in skeletal muscle of mdx mice (mdx-TG), and compared skeletal muscle pathology and force-generating capacity between mdx and mdx-TG mice at different ages. We investigated the mechanism by which γ-cyto actin provides protection from force loss by studying the role of calcium channels and stretch-activated channels in isolated skeletal muscles and muscle fibers. Analysis of variance or independent t-tests were used to detect statistical differences between groups. Results Levels of γ-cyto actin in mdx-TG skeletal muscle were elevated 200-fold compared to mdx skeletal muscle and incorporated into thin filaments. Overexpression of γ-cyto actin had little effect on most parameters of mdx muscle pathology. However, γ-cyto actin provided statistically significant protection against force loss during eccentric contractions. Store-operated calcium entry across the sarcolemma did not differ between mdx fibers compared to wild-type fibers. Additionally, the omission of extracellular calcium or the addition of streptomycin to block stretch-activated channels did not improve the force-generating capacity of isolated extensor digitorum longus muscles from mdx mice during eccentric contractions. Conclusions The data presented in this study indicate that upregulation of γ-cyto actin in dystrophic skeletal muscle can attenuate force loss during eccentric contractions and that the mechanism is independent of activation of stretch-activated channels and the accumulation of extracellular calcium.
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Affiliation(s)
- Kristen A Baltgalvis
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 6-155 Jackson Hall, 321 Church Street SE, Minneapolis, MN 55455, USA.
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A new extensively characterised conditionally immortal muscle cell-line for investigating therapeutic strategies in muscular dystrophies. PLoS One 2011; 6:e24826. [PMID: 21935475 PMCID: PMC3173493 DOI: 10.1371/journal.pone.0024826] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2011] [Accepted: 08/18/2011] [Indexed: 01/13/2023] Open
Abstract
A new conditionally immortal satellite cell-derived cell-line, H2K 2B4, was generated from the H2Kb-tsA58 immortomouse. Under permissive conditions H2K 2B4 cells terminally differentiate in vitro to form uniform myotubes with a myogenic protein profile comparable with freshly isolated satellite cells. Following engraftment into immunodeficient dystrophin-deficient mice, H2K 2B4 cells regenerated host muscle with donor derived myofibres that persisted for at least 24 weeks, without forming tumours. These cells were readily transfectable using both retrovirus and the non-viral transfection methods and importantly upon transplantation, were able to reconstitute the satellite cell niche with functional donor derived satellite cells. Finally using the Class II DNA transposon, Sleeping Beauty, we successfully integrated a reporter plasmid into the genome of H2K 2B4 cells without hindering the myogenic differentiation. Overall, these data suggest that H2K 2B4 cells represent a readily transfectable stable cell-line in which to investigate future stem cell based therapies for muscle disease.
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29
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Chemello F, Bean C, Cancellara P, Laveder P, Reggiani C, Lanfranchi G. Microgenomic analysis in skeletal muscle: expression signatures of individual fast and slow myofibers. PLoS One 2011; 6:e16807. [PMID: 21364935 PMCID: PMC3043066 DOI: 10.1371/journal.pone.0016807] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 12/30/2010] [Indexed: 11/18/2022] Open
Abstract
Background Skeletal muscle is a complex, versatile tissue composed of a variety of functionally diverse fiber types. Although the biochemical, structural and functional properties of myofibers have been the subject of intense investigation for the last decades, understanding molecular processes regulating fiber type diversity is still complicated by the heterogeneity of cell types present in the whole muscle organ. Methodology/Principal Findings We have produced a first catalogue of genes expressed in mouse slow-oxidative (type 1) and fast-glycolytic (type 2B) fibers through transcriptome analysis at the single fiber level (microgenomics). Individual fibers were obtained from murine soleus and EDL muscles and initially classified by myosin heavy chain isoform content. Gene expression profiling on high density DNA oligonucleotide microarrays showed that both qualitative and quantitative improvements were achieved, compared to results with standard muscle homogenate. First, myofiber profiles were virtually free from non-muscle transcriptional activity. Second, thousands of muscle-specific genes were identified, leading to a better definition of gene signatures in the two fiber types as well as the detection of metabolic and signaling pathways that are differentially activated in specific fiber types. Several regulatory proteins showed preferential expression in slow myofibers. Discriminant analysis revealed novel genes that could be useful for fiber type functional classification. Conclusions/Significance As gene expression analyses at the single fiber level significantly increased the resolution power, this innovative approach would allow a better understanding of the adaptive transcriptomic transitions occurring in myofibers under physiological and pathological conditions.
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Affiliation(s)
- Francesco Chemello
- Department of Biology and CRIBI Biotechnology Center, University of Padova, Padova, Italy
| | - Camilla Bean
- Department of Biology and CRIBI Biotechnology Center, University of Padova, Padova, Italy
| | - Pasqua Cancellara
- Department of Anatomy and Physiology, University of Padova, Padova, Italy
| | - Paolo Laveder
- Department of Biology and CRIBI Biotechnology Center, University of Padova, Padova, Italy
| | - Carlo Reggiani
- Department of Anatomy and Physiology, University of Padova, Padova, Italy
| | - Gerolamo Lanfranchi
- Department of Biology and CRIBI Biotechnology Center, University of Padova, Padova, Italy
- * E-mail:
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Whitehead NP, Yeung EW, Froehner SC, Allen DG. Skeletal muscle NADPH oxidase is increased and triggers stretch-induced damage in the mdx mouse. PLoS One 2010; 5:e15354. [PMID: 21187957 PMCID: PMC3004864 DOI: 10.1371/journal.pone.0015354] [Citation(s) in RCA: 138] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 11/11/2010] [Indexed: 11/19/2022] Open
Abstract
Recent studies have shown that oxidative stress contributes to the pathogenesis of muscle damage in dystrophic (mdx) mice. In this study we have investigated the role of NADPH oxidase as a source of the oxidative stress in these mice. The NADPH oxidase subunits gp91phox, p67phox and rac 1 were increased 2–3 fold in tibilais anterior muscles from mdx mice compared to wild type. Importantly, this increase occurred in 19 day old mice, before the onset of muscle necrosis and inflammation, suggesting that NADPH oxidase is an important source of oxidative stress in mdx muscle. In muscles from 9 week old mdx mice, gp91phox and p67phox were increased 3–4 fold and NADPH oxidase superoxide production was 2 times greater than wild type. In single fibers from mdx muscle NADPH oxidase subunits were all located on or near the sarcolemma, except for p67phox,which was expressed in the cytosol. Pharmacological inhibition of NADPH oxidase significantly reduced the intracellular Ca2+ rise following stretched contractions in mdx single fibers, and also attenuated the loss of muscle force. These results suggest that NADPH oxidase is a major source of reactive oxygen species in dystrophic muscle and its enhanced activity has a stimulatory effect on stretch-induced Ca2+ entry, a key mechanism for muscle damage and functional impairment.
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Affiliation(s)
- Nicholas P Whitehead
- Discipline of Physiology, Bosch Institute, The University of Sydney, Sydney, New South Wales, Australia.
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31
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Langhammer CG, Zahn JD, Firestein BL. Identification and quantification of skeletal myotube contraction and association in vitro by video microscopy. Cytoskeleton (Hoboken) 2010; 67:413-24. [PMID: 20506519 DOI: 10.1002/cm.20457] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Skeletal muscle is the largest tissue in the body by weight and plays many roles in maintaining homeostasis and health. Ex vivo cell-based experimental systems used to study muscle cell contraction, and others based on incorporation of cells into sensitive force transducers or electrophysiology equipment, are time-consuming, invasive, and not universally available, slowing the pace of research. Video microscopy provides a noninvasive way to record the contractile behavior of skeletal muscle cells in vitro. We have developed a numerical procedure using image processing and pattern recognition algorithms, that makes it possible to quantify contractile behavior of multiple myotubes simultaneously, based on video data. We examined the ability of the program to identify movement using a simplified graphical model of myotube contraction and found that the program's success is dependent on the morphology and movement characteristics of the objects. However, the program performs optimally over the types of motions approximating those observed in culture and identifies contracting myotubes in sample videomicrographs of muscle cells in vitro. This program quantifies contractility on a population level, can be adapted for use in laboratories capable of digital video capture from a microscope, and may be coupled with other experimental techniques to supplement existing research tools.
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Affiliation(s)
- Christopher G Langhammer
- Department of Biomedical Engineering, Rutgers University, Busch Campus, Piscataway, New Jersey 08854, USA
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32
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Sodium channel Na(V)1.5 expression is enhanced in cultured adult rat skeletal muscle fibers. J Membr Biol 2010; 235:109-19. [PMID: 20517693 DOI: 10.1007/s00232-010-9262-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Accepted: 05/10/2010] [Indexed: 12/19/2022]
Abstract
This study analyzes changes in the distribution, electrophysiological properties, and proteic composition of voltage-gated sodium channels (Na(V)) in cultured adult rat skeletal muscle fibers. Patch clamp and molecular biology techniques were carried out in flexor digitorum brevis (FDB) adult rat skeletal muscle fibers maintained in vitro after cell dissociation with collagenase. After 4 days of culture, an increase of the Na(V)1.5 channel type was observed. This was confirmed by an increase in TTX-resistant channels and by Western blot test. These channels exhibited increased activation time constant (tau(m)) and reduced conductance, similar to what has been observed in denervated muscles in vivo, where the density of Na(V)1.5 was increasing progressively after denervation. By real-time polymerase chain reaction, we found that the expression of beta subunits was also modified, but only after 7 days of culture: increase in beta(1) without beta(4) modifications. beta(1) subunit is known to induce a negative shift of the inactivation curve, thus reducing current amplitude and duration. At day 7, tau(h) was back to normal and tau(m) still increased, in agreement with a decrease in sodium current and conductance at day 4 and normalization at day 7. Our model is a useful tool to study the effects of denervation in adult muscle fibers in vitro and the expression of sodium channels. Our data evidenced an increase in Na(V)1.5 channels and the involvement of beta subunits in the regulation of sodium current and fiber excitability.
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Abstract
In the past decade, high-content screening has become a highly developed approach to obtaining richly descriptive quantitative phenotypic data using automated microscopy. From early use in drug screening, the technique has evolved to embrace a diverse range of applications in both academic and industrial sectors and is now widely recognized as providing an efficient and effective approach to large-scale programs investigating cell biology in situ and in context.
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Affiliation(s)
- Nick Thomas
- GE Healthcare, Whitchurch, Cardiff, United Kingdom,
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Lovering RM, Michaelson L, Ward CW. Malformed mdx myofibers have normal cytoskeletal architecture yet altered EC coupling and stress-induced Ca2+ signaling. Am J Physiol Cell Physiol 2009; 297:C571-80. [PMID: 19605736 DOI: 10.1152/ajpcell.00087.2009] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Skeletal muscle function is dependent on its highly regular structure. In studies of dystrophic (dy/dy) mice, the proportion of malformed myofibers decreases after prolonged whole muscle stimulation, suggesting that the malformed myofibers are more prone to injury. The aim of this study was to assess morphology and to measure excitation-contraction (EC) coupling (Ca(2+) transients) and susceptibility to osmotic stress (Ca(2+) sparks) of enzymatically isolated muscle fibers of the extensor digitorum longus (EDL) and flexor digitorum brevis (FDB) muscles from young (2-3 mo) and old (8-9 mo) mdx and age-matched control mice (C57BL10). In young mdx EDL, 6% of the myofibers had visible malformations (i.e., interfiber splitting, branched ends, midfiber appendages). In contrast, 65% of myofibers in old mdx EDL contained visible malformations. In the mdx FDB, malformation occurred in only 5% of young myofibers and 11% of old myofibers. Age-matched control mice did not display the altered morphology of mdx muscles. The membrane-associated and cytoplasmic cytoskeletal structures appeared normal in the malformed mdx myofibers. In mdx FDBs with significantly branched ends, an assessment of global, electrically evoked Ca(2+) signals (indo-1PE-AM) revealed an EC coupling deficit in myofibers with significant branching. Interestingly, peak amplitude of electrically evoked Ca(2+) release in the branch of the bifurcated mdx myofiber was significantly decreased compared with the trunk of the same myofiber. No alteration in the basal myoplasmic Ca(2+) concentration (i.e., indo ratio) was seen in malformed vs. normal mdx myofibers. Finally, osmotic stress induced the occurrence of Ca(2+) sparks to a greater extent in the malformed portions of myofibers, which is consistent with deficits in EC coupling control. In summary, our data show that aging mdx myofibers develop morphological malformations. These malformations are not associated with gross disruptions in cytoskeletal or t-tubule structure; however, alterations in myofiber Ca(2+) signaling are evident.
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Affiliation(s)
- Richard M Lovering
- Univ. of Maryland School of Medicine, Dept. of Physiology, 685 W. Baltimore St., HSF-1, Rm, 580, Baltimore, MD 21201, USA.
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Ravenscroft G, Colley SM, Walker KR, Clement S, Bringans S, Lipscombe R, Fabian VA, Laing NG, Nowak KJ. Expression of cardiac α-actin spares extraocular muscles in skeletal muscle α-actin diseases – Quantification of striated α-actins by MRM-mass spectrometry. Neuromuscul Disord 2008; 18:953-8. [DOI: 10.1016/j.nmd.2008.09.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 07/09/2008] [Accepted: 09/16/2008] [Indexed: 10/21/2022]
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