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Mokhonova EI, Malik R, Mamsa H, Walker J, Gibbs EM, Crosbie RH. The Development of Robust Antibodies to Sarcospan, a Dystrophin- and Integrin-Associated Protein, for Basic and Translational Research. Int J Mol Sci 2024; 25:6121. [PMID: 38892308 PMCID: PMC11173052 DOI: 10.3390/ijms25116121] [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: 04/13/2024] [Revised: 05/25/2024] [Accepted: 05/27/2024] [Indexed: 06/21/2024] Open
Abstract
Sarcospan (SSPN) is a 25-kDa transmembrane protein that is broadly expressed at the cell surface of many tissues, including, but not limited to, the myofibers from skeletal and smooth muscles, cardiomyocytes, adipocytes, kidney epithelial cells, and neurons. SSPN is a core component of the dystrophin-glycoprotein complex (DGC) that links the intracellular actin cytoskeleton with the extracellular matrix. It is also associated with integrin α7β1, the predominant integrin expressed in skeletal muscle. As a tetraspanin-like protein with four transmembrane spanning domains, SSPN functions as a scaffold to facilitate protein-protein interactions at the cell membrane. Duchenne muscular dystrophy, Becker muscular dystrophy, and X-linked dilated cardiomyopathy are caused by the loss of dystrophin at the muscle cell surface and a concomitant loss of the entire DGC, including SSPN. SSPN overexpression ameliorates Duchenne muscular dystrophy in the mdx murine model, which supports SSPN being a viable therapeutic target. Other rescue studies support SSPN as a biomarker for the proper assembly and membrane expression of the DGC. Highly specific and robust antibodies to SSPN are needed for basic research on the molecular mechanisms of SSPN rescue, pre-clinical studies, and biomarker evaluations in human samples. The development of SSPN antibodies is challenged by the presence of its four transmembrane domains and limited antigenic epitopes. To address the significant barrier presented by limited commercially available antibodies, we aimed to generate a panel of robust SSPN-specific antibodies that can serve as a resource for the research community. We created antibodies to three SSPN protein epitopes, including the intracellular N- and C-termini as well as the large extracellular loop (LEL) between transmembrane domains 3 and 4. We developed a panel of rabbit antibodies (poly- and monoclonal) against an N-terminal peptide fragment of SSPN. We used several assays to show that the rabbit antibodies recognize mouse SSPN with a high functional affinity and specificity. We developed mouse monoclonal antibodies against the C-terminal peptide and the large extracellular loop of human SSPN. These antibodies are superior to commercially available antibodies and outperform them in various applications, including immunoblotting, indirect immunofluorescence analysis, immunoprecipitation, and an ELISA. These newly developed antibodies will significantly improve the quality and ease of SSPN detection for basic and translational research.
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Affiliation(s)
- Ekaterina I. Mokhonova
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Ravinder Malik
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Hafsa Mamsa
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Jackson Walker
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Elizabeth M. Gibbs
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
| | - Rachelle H. Crosbie
- Department of Integrative Biology and Physiology, University of California Los Angeles, Los Angeles, CA 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California Los Angeles, Los Angeles, CA 90095, USA
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA 90095, USA
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA
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Hwang HS, Kahmini AR, Prascak J, Cejas-Carbonell A, Valera IC, Champion S, Corrigan M, Mumbi F, Parvatiyar MS. Sarcospan Deficiency Increases Oxidative Stress and Arrhythmias in Hearts after Acute Ischemia-Reperfusion Injury. Int J Mol Sci 2023; 24:11868. [PMID: 37511627 PMCID: PMC10380899 DOI: 10.3390/ijms241411868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2023] [Revised: 07/14/2023] [Accepted: 07/20/2023] [Indexed: 07/30/2023] Open
Abstract
The protein sarcospan (SSPN) is an integral member of the dystrophin-glycoprotein complex (DGC) and has been shown to be important in the heart during the development and the response to acute stress. In this study, we investigated the role of SSPN in the cardiac response to acute ischemia-reperfusion (IR) injury in SSPN-deficient (SSPN-/-) mice. First, the hemodynamic response of SSPN-/- mice was tested and was similar to SSPN+/+ (wild-type) mice after isoproterenol injection. Using the in situ Langendorff perfusion method, SSPN-/- hearts were subjected to IR injury and found to have increased infarct size and arrhythmia susceptibility compared to SSPN+/+. Ca2+ handling was assessed in single cardiomyocytes and diastolic Ca2+ levels were increased after acute β-AR stimulation in SSPN+/+ but not SSPN-/-. It was also found that SSPN-/- cardiomyocytes had reduced Ca2+ SR content compared to SSPN+/+ but similar SR Ca2+ release. Next, we used qRT-PCR to examine gene expression of Ca2+ handling proteins after acute IR injury. SSPN-/- hearts showed a significant decrease in L-type Ca2+ channels and a significant increase in Ca2+ release channel (RyR2) expression. Interestingly, under oxidizing conditions reminiscent of IR, SSPN-/- cardiomyocytes, had increased H2O2-induced reactive oxygen species production compared to SSPN+/+. Examination of oxidative stress proteins indicated that NADPH oxidase 4 and oxidized CAMKII were increased in SSPN-/- hearts after acute IR injury. These results suggest that increased arrhythmia susceptibility in SSPN-/- hearts post-IR injury may arise from alterations in Ca2+ handling and a reduced capacity to regulate oxidative stress pathways.
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Affiliation(s)
- Hyun Seok Hwang
- Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA
| | - Aida Rahimi Kahmini
- Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA
| | - Julia Prascak
- Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA
| | - Alexis Cejas-Carbonell
- Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA
| | - Isela C Valera
- Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA
| | - Samantha Champion
- Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA
| | - Mikayla Corrigan
- Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA
| | - Florence Mumbi
- Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA
| | - Michelle S Parvatiyar
- Department of Nutrition and Integrative Physiology, Florida State University, 107 Chieftan Way, Biomedical Research Facility, Tallahassee, FL 32306-1490, USA
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Stearns-Reider KM, Hicks MR, Hammond KG, Reynolds JC, Maity A, Kurmangaliyev YZ, Chin J, Stieg AZ, Geisse NA, Hohlbauch S, Kaemmer S, Schmitt LR, Pham TT, Yamauchi K, Novitch BG, Wollman R, Hansen KC, Pyle AD, Crosbie RH. Myoscaffolds reveal laminin scarring is detrimental for stem cell function while sarcospan induces compensatory fibrosis. NPJ Regen Med 2023; 8:16. [PMID: 36922514 PMCID: PMC10017766 DOI: 10.1038/s41536-023-00287-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 02/22/2023] [Indexed: 03/18/2023] Open
Abstract
We developed an on-slide decellularization approach to generate acellular extracellular matrix (ECM) myoscaffolds that can be repopulated with various cell types to interrogate cell-ECM interactions. Using this platform, we investigated whether fibrotic ECM scarring affected human skeletal muscle progenitor cell (SMPC) functions that are essential for myoregeneration. SMPCs exhibited robust adhesion, motility, and differentiation on healthy muscle-derived myoscaffolds. All SPMC interactions with fibrotic myoscaffolds from dystrophic muscle were severely blunted including reduced motility rate and migration. Furthermore, SMPCs were unable to remodel laminin dense fibrotic scars within diseased myoscaffolds. Proteomics and structural analysis revealed that excessive collagen deposition alone is not pathological, and can be compensatory, as revealed by overexpression of sarcospan and its associated ECM receptors in dystrophic muscle. Our in vivo data also supported that ECM remodeling is important for SMPC engraftment and that fibrotic scars may represent one barrier to efficient cell therapy.
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Affiliation(s)
- Kristen M Stearns-Reider
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Department of Orthopaedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Michael R Hicks
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Department of Physiology and Biophysics, University of California, Irvine, Irvine, CA, 92697, USA
| | - Katherine G Hammond
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Joseph C Reynolds
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Alok Maity
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Institute for Quantitative and Computational Biology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Yerbol Z Kurmangaliyev
- Institute for Quantitative and Computational Biology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Department of Biological Chemistry, HHMI, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Jesse Chin
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Adam Z Stieg
- California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | | | - Sophia Hohlbauch
- Asylum Research, An Oxford Instruments Company, Santa Barbara, CA, 93117, USA
| | - Stefan Kaemmer
- Park Systems, 3040 Olcott St, Santa Clara, CA, 95054, USA
| | - Lauren R Schmitt
- Department of Biochemistry and Molecular Genetics, University of Colorado, Denver, Aurora, CO, 80045, USA
| | - Thanh T Pham
- Department of Biochemistry and Molecular Genetics, University of Colorado, Denver, Aurora, CO, 80045, USA
| | - Ken Yamauchi
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Bennett G Novitch
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Intellectual and Developmental Disabilities Research Center, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, 90095, USA
| | - Roy Wollman
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Institute for Quantitative and Computational Biology, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, University of Colorado, Denver, Aurora, CO, 80045, USA
| | - April D Pyle
- Department of Microbiology, Immunology, and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA, 90095, USA
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA
| | - Rachelle H Crosbie
- Department of Integrative Biology and Physiology, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
- Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
- Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
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McCourt JL, Stearns-Reider KM, Mamsa H, Kannan P, Afsharinia MH, Shu C, Gibbs EM, Shin KM, Kurmangaliyev YZ, Schmitt LR, Hansen KC, Crosbie RH. Multi-omics analysis of sarcospan overexpression in mdx skeletal muscle reveals compensatory remodeling of cytoskeleton-matrix interactions that promote mechanotransduction pathways. Skelet Muscle 2023; 13:1. [PMID: 36609344 PMCID: PMC9817407 DOI: 10.1186/s13395-022-00311-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Accepted: 12/06/2022] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The dystrophin-glycoprotein complex (DGC) is a critical adhesion complex of the muscle cell membrane, providing a mechanical link between the extracellular matrix (ECM) and the cortical cytoskeleton that stabilizes the sarcolemma during repeated muscle contractions. One integral component of the DGC is the transmembrane protein, sarcospan (SSPN). Overexpression of SSPN in the skeletal muscle of mdx mice (murine model of DMD) restores muscle fiber attachment to the ECM in part through an associated increase in utrophin and integrin adhesion complexes at the cell membrane, protecting the muscle from contraction-induced injury. In this study, we utilized transcriptomic and ECM protein-optimized proteomics data sets from wild-type, mdx, and mdx transgenic (mdxTG) skeletal muscle tissues to identify pathways and proteins driving the compensatory action of SSPN overexpression. METHODS The tibialis anterior and quadriceps muscles were isolated from wild-type, mdx, and mdxTG mice and subjected to bulk RNA-Seq and global proteomics analysis using methods to enhance capture of ECM proteins. Data sets were further analyzed through the ingenuity pathway analysis (QIAGEN) and integrative gene set enrichment to identify candidate networks, signaling pathways, and upstream regulators. RESULTS Through our multi-omics approach, we identified 3 classes of differentially expressed genes and proteins in mdxTG muscle, including those that were (1) unrestored (significantly different from wild type, but not from mdx), (2) restored (significantly different from mdx, but not from wild type), and (3) compensatory (significantly different from both wild type and mdx). We identified signaling pathways that may contribute to the rescue phenotype, most notably cytoskeleton and ECM organization pathways. ECM-optimized proteomics revealed an increased abundance of collagens II, V, and XI, along with β-spectrin in mdxTG samples. Using ingenuity pathway analysis, we identified upstream regulators that are computationally predicted to drive compensatory changes, revealing a possible mechanism of SSPN rescue through a rewiring of cell-ECM bidirectional communication. We found that SSPN overexpression results in upregulation of key signaling molecules associated with regulation of cytoskeleton organization and mechanotransduction, including Yap1, Sox9, Rho, RAC, and Wnt. CONCLUSIONS Our findings indicate that SSPN overexpression rescues dystrophin deficiency partially through mechanotransduction signaling cascades mediated through components of the ECM and the cortical cytoskeleton.
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Affiliation(s)
- Jackie L. McCourt
- grid.19006.3e0000 0000 9632 6718Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Kristen M. Stearns-Reider
- grid.19006.3e0000 0000 9632 6718Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA ,grid.19006.3e0000 0000 9632 6718Department of Orthopedic Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA USA
| | - Hafsa Mamsa
- grid.19006.3e0000 0000 9632 6718Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Pranav Kannan
- grid.19006.3e0000 0000 9632 6718Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Mohammad Hossein Afsharinia
- grid.19006.3e0000 0000 9632 6718Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Cynthia Shu
- grid.19006.3e0000 0000 9632 6718Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Elizabeth M. Gibbs
- grid.19006.3e0000 0000 9632 6718Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Kara M. Shin
- grid.19006.3e0000 0000 9632 6718Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA
| | - Yerbol Z. Kurmangaliyev
- grid.19006.3e0000 0000 9632 6718Department of Biological Chemistry, Howard Hughes Medical Institute, David Geffen School of Medicine, University of California, Los Angeles, CA USA
| | - Lauren R. Schmitt
- grid.241116.10000000107903411Department of Biochemistry and Molecular Genetics, University of Colorado, Denver, CO USA
| | - Kirk C. Hansen
- grid.241116.10000000107903411Department of Biochemistry and Molecular Genetics, University of Colorado, Denver, CO USA
| | - Rachelle H. Crosbie
- grid.19006.3e0000 0000 9632 6718Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095 USA ,grid.19006.3e0000 0000 9632 6718Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA USA ,grid.19006.3e0000 0000 9632 6718Molecular Biology Institute, University of California, Los Angeles, CA USA ,grid.19006.3e0000 0000 9632 6718Broad Stem Cell Research Center, University of California, Los Angeles, CA USA
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High-Throughput Screening to Identify Modulators of Sarcospan. Methods Mol Biol 2022; 2587:479-493. [PMID: 36401045 DOI: 10.1007/978-1-0716-2772-3_25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
High-throughput screening enables the discovery of disease-modifying small molecules. Here, we describe the development of a scalable, cell-based assay to screen for small molecules that modulate sarcospan for the treatment of Duchenne muscular dystrophy. We detail the hit validation pipeline, which includes secondary screening, gene/protein quantification, and an in vitro membrane stability assay.
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Hayes AJ, Farrugia BL, Biose IJ, Bix GJ, Melrose J. Perlecan, A Multi-Functional, Cell-Instructive, Matrix-Stabilizing Proteoglycan With Roles in Tissue Development Has Relevance to Connective Tissue Repair and Regeneration. Front Cell Dev Biol 2022; 10:856261. [PMID: 35433700 PMCID: PMC9010944 DOI: 10.3389/fcell.2022.856261] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Accepted: 02/28/2022] [Indexed: 12/19/2022] Open
Abstract
This review highlights the multifunctional properties of perlecan (HSPG2) and its potential roles in repair biology. Perlecan is ubiquitous, occurring in vascular, cartilaginous, adipose, lymphoreticular, bone and bone marrow stroma and in neural tissues. Perlecan has roles in angiogenesis, tissue development and extracellular matrix stabilization in mature weight bearing and tensional tissues. Perlecan contributes to mechanosensory properties in cartilage through pericellular interactions with fibrillin-1, type IV, V, VI and XI collagen and elastin. Perlecan domain I - FGF, PDGF, VEGF and BMP interactions promote embryonic cellular proliferation, differentiation, and tissue development. Perlecan domain II, an LDLR-like domain interacts with lipids, Wnt and Hedgehog morphogens. Perlecan domain III binds FGF-7 and 18 and has roles in the secretion of perlecan. Perlecan domain IV, an immunoglobulin repeat domain, has cell attachment and matrix stabilizing properties. Perlecan domain V promotes tissue repair through interactions with VEGF, VEGF-R2 and α2β1 integrin. Perlecan domain-V LG1-LG2 and LG3 fragments antagonize these interactions. Perlecan domain V promotes reconstitution of the blood brain barrier damaged by ischemic stroke and is neurogenic and neuroprotective. Perlecan-VEGF-VEGFR2, perlecan-FGF-2 and perlecan-PDGF interactions promote angiogenesis and wound healing. Perlecan domain I, III and V interactions with platelet factor-4 and megakaryocyte and platelet inhibitory receptor promote adhesion of cells to implants and scaffolds in vascular repair. Perlecan localizes acetylcholinesterase in the neuromuscular junction and is of functional significance in neuromuscular control. Perlecan mutation leads to Schwartz-Jampel Syndrome, functional impairment of the biomechanical properties of the intervertebral disc, variable levels of chondroplasia and myotonia. A greater understanding of the functional working of the neuromuscular junction may be insightful in therapeutic approaches in the treatment of neuromuscular disorders. Tissue engineering of salivary glands has been undertaken using bioactive peptides (TWSKV) derived from perlecan domain IV. Perlecan TWSKV peptide induces differentiation of salivary gland cells into self-assembling acini-like structures that express salivary gland biomarkers and secrete α-amylase. Perlecan also promotes chondroprogenitor stem cell maturation and development of pluripotent migratory stem cell lineages, which participate in diarthrodial joint formation, and early cartilage development. Recent studies have also shown that perlecan is prominently expressed during repair of adult human articular cartilage. Perlecan also has roles in endochondral ossification and bone development. Perlecan domain I hydrogels been used in tissue engineering to establish heparin binding growth factor gradients that promote cell migration and cartilage repair. Perlecan domain I collagen I fibril scaffolds have also been used as an FGF-2 delivery system for tissue repair. With the availability of recombinant perlecan domains, the development of other tissue repair strategies should emerge in the near future. Perlecan co-localization with vascular elastin in the intima, acts as a blood shear-flow endothelial sensor that regulates blood volume and pressure and has a similar role to perlecan in canalicular fluid, regulating bone development and remodeling. This complements perlecan’s roles in growth plate cartilage and in endochondral ossification to form the appendicular and axial skeleton. Perlecan is thus a ubiquitous, multifunctional, and pleomorphic molecule of considerable biological importance. A greater understanding of its diverse biological roles and functional repertoires during tissue development, growth and disease will yield valuable insights into how this impressive proteoglycan could be utilized successfully in repair biology.
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Affiliation(s)
- Anthony J. Hayes
- Bioimaging Research Hub, Cardiff School of Biosciences, Cardiff University, Wales, United Kingdom
| | - Brooke L. Farrugia
- Department of Biomedical Engineering, Melbourne School of Engineering, The University of Melbourne, Melbourne, VIC, Australia
| | - Ifechukwude J. Biose
- Departments of Neurosurgery and Neurology, Clinical Neuroscience Research Center, Tulane University School of Medicine, New Orleans, LA, United States
| | - Gregory J. Bix
- Departments of Neurosurgery and Neurology, Clinical Neuroscience Research Center, Tulane University School of Medicine, New Orleans, LA, United States
| | - James Melrose
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW, Australia
- Raymond Purves Bone and Joint Research Laboratories, Kolling Institute of Medical Research, Royal North Shore Hospital, The Faculty of Medicine and Health, The University of Sydney, St. Leonard’s, NSW, Australia
- *Correspondence: James Melrose,
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7
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Mamsa H, Stark RL, Shin KM, Beedle AM, Crosbie RH. Sarcospan increases laminin-binding capacity of α-dystroglycan to ameliorate DMD independent of Galgt2. Hum Mol Genet 2022; 31:718-732. [PMID: 34581784 PMCID: PMC8895749 DOI: 10.1093/hmg/ddab276] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 08/27/2021] [Accepted: 09/13/2021] [Indexed: 11/14/2022] Open
Abstract
In Duchenne muscular dystrophy (DMD), mutations in dystrophin result in a loss of the dystrophin-glycoprotein complex (DGC) at the myofiber membrane, which functions to connect the extracellular matrix with the intracellular actin cytoskeleton. The dystroglycan subcomplex interacts with dystrophin and spans the sarcolemma where its extensive carbohydrates (matriglycan and CT2 glycan) directly interact with the extracellular matrix. In the current manuscript, we show that sarcospan overexpression enhances the laminin-binding capacity of dystroglycan in DMD muscle by increasing matriglycan glycosylation of α-dystroglycan. Furthermore, we find that this modification is not affected by loss of Galgt2, a glycotransferase, which catalyzes the CT2 glycan. Our findings reveal that the matriglycan carbohydrates, and not the CT2 glycan, are necessary for sarcospan-mediated amelioration of DMD. Overexpression of Galgt2 in the DMD mdx murine model prevents muscle pathology by increasing CT2 modified α-dystroglycan. Galgt2 also increases expression of utrophin, which compensates for the loss of dystrophin in DMD muscle. We found that combined loss of Galgt2 and dystrophin reduced utrophin expression; however, it did not interfere with sarcospan rescue of disease. These data reveal a partial dependence of sarcospan on Galgt2 for utrophin upregulation. In addition, sarcospan alters the cross-talk between the adhesion complexes by decreasing the association of integrin β1D with dystroglycan complexes. In conclusion, sarcospan functions to re-wire the cell to matrix connections by strengthening the cellular adhesion and signaling, which, in turn, increases the resilience of the myofiber membrane.
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Affiliation(s)
- Hafsa Mamsa
- Department of Integrative Biology & Physiology, University of California, Los Angeles 90095, USA
| | - Rachelle L Stark
- Department of Integrative Biology & Physiology, University of California, Los Angeles 90095, USA
| | - Kara M Shin
- Department of Integrative Biology & Physiology, University of California, Los Angeles 90095, USA
| | - Aaron M Beedle
- Department of Pharmaceutical Sciences, Binghamton University State University of New York, New York 13902, USA
| | - Rachelle H Crosbie
- Department of Integrative Biology & Physiology, University of California, Los Angeles 90095, USA
- Broad Stem Cell Institute, University of California, Los Angeles 90095, USA
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles 90095, USA
- Molecular Biology Institute, University of California, Los Angeles 90095, USA
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8
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Molecular and cellular basis of genetically inherited skeletal muscle disorders. Nat Rev Mol Cell Biol 2021; 22:713-732. [PMID: 34257452 PMCID: PMC9686310 DOI: 10.1038/s41580-021-00389-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2021] [Indexed: 02/06/2023]
Abstract
Neuromuscular disorders comprise a diverse group of human inborn diseases that arise from defects in the structure and/or function of the muscle tissue - encompassing the muscle cells (myofibres) themselves and their extracellular matrix - or muscle fibre innervation. Since the identification in 1987 of the first genetic lesion associated with a neuromuscular disorder - mutations in dystrophin as an underlying cause of Duchenne muscular dystrophy - the field has made tremendous progress in understanding the genetic basis of these diseases, with pathogenic variants in more than 500 genes now identified as underlying causes of neuromuscular disorders. The subset of neuromuscular disorders that affect skeletal muscle are referred to as myopathies or muscular dystrophies, and are due to variants in genes encoding muscle proteins. Many of these proteins provide structural stability to the myofibres or function in regulating sarcolemmal integrity, whereas others are involved in protein turnover, intracellular trafficking, calcium handling and electrical excitability - processes that ensure myofibre resistance to stress and their primary activity in muscle contraction. In this Review, we discuss how defects in muscle proteins give rise to muscle dysfunction, and ultimately to disease, with a focus on pathologies that are most common, best understood and that provide the most insight into muscle biology.
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9
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Lü Z, Gong L, Ren Y, Chen Y, Wang Z, Liu L, Li H, Chen X, Li Z, Luo H, Jiang H, Zeng Y, Wang Y, Wang K, Zhang C, Jiang H, Wan W, Qin Y, Zhang J, Zhu L, Shi W, He S, Mao B, Wang W, Kong X, Li Y. Large-scale sequencing of flatfish genomes provides insights into the polyphyletic origin of their specialized body plan. Nat Genet 2021; 53:742-751. [PMID: 33875864 PMCID: PMC8110480 DOI: 10.1038/s41588-021-00836-9] [Citation(s) in RCA: 19] [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: 06/24/2020] [Accepted: 03/05/2021] [Indexed: 11/09/2022]
Abstract
The evolutionary and genetic origins of the specialized body plan of flatfish are largely unclear. We analyzed the genomes of 11 flatfish species representing 9 of the 14 Pleuronectiforme families and conclude that Pleuronectoidei and Psettodoidei do not form a monophyletic group, suggesting independent origins from different percoid ancestors. Genomic and transcriptomic data indicate that genes related to WNT and retinoic acid pathways, hampered musculature and reduced lipids might have functioned in the evolution of the specialized body plan of Pleuronectoidei. Evolution of Psettodoidei involved similar but not identical genes. Our work provides valuable resources and insights for understanding the genetic origins of the unusual body plan of flatfishes.
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Affiliation(s)
- Zhenming Lü
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Zhejiang Ocean University, Zhoushan, China
| | - Li Gong
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Zhejiang Ocean University, Zhoushan, China
| | - Yandong Ren
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Yongjiu Chen
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Zhejiang Ocean University, Zhoushan, China
| | - Zhongkai Wang
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Liqin Liu
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Zhejiang Ocean University, Zhoushan, China
| | - Haorong Li
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Xianqing Chen
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Zhenzhu Li
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Hairong Luo
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Hui Jiang
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Zhejiang Ocean University, Zhoushan, China
| | - Yan Zeng
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Yifan Wang
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Zhejiang Ocean University, Zhoushan, China
| | - Kun Wang
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Chen Zhang
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Haifeng Jiang
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Wenting Wan
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Yanli Qin
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China
| | - Jianshe Zhang
- National Engineering Laboratory of Marine Germplasm Resources Exploration and Utilization, Zhejiang Ocean University, Zhoushan, China
| | - Liang Zhu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Wei Shi
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
| | - Shunping He
- Key Laboratory of Aquatic Biodiversity and Conservation, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Bingyu Mao
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China
| | - Wen Wang
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China.
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, China.
| | - Xiaoyu Kong
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China.
| | - Yongxin Li
- School of Ecology and Environment, Northwestern Polytechnical University, Xi'an, China.
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, China.
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10
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Valera IC, Wacker AL, Hwang HS, Holmes C, Laitano O, Landstrom AP, Parvatiyar MS. Essential roles of the dystrophin-glycoprotein complex in different cardiac pathologies. Adv Med Sci 2021; 66:52-71. [PMID: 33387942 DOI: 10.1016/j.advms.2020.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 12/12/2020] [Accepted: 12/17/2020] [Indexed: 12/20/2022]
Abstract
The dystrophin-glycoprotein complex (DGC), situated at the sarcolemma dynamically remodels during cardiac disease. This review examines DGC remodeling as a common denominator in diseases affecting heart function and health. Dystrophin and the DGC serve as broad cytoskeletal integrators that are critical for maintaining stability of muscle membranes. The presence of pathogenic variants in genes encoding proteins of the DGC can cause absence of the protein and/or alterations in other complex members leading to muscular dystrophies. Targeted studies have allowed the individual functions of affected proteins to be defined. The DGC has demonstrated its dynamic function, remodeling under a number of conditions that stress the heart. Beyond genetic causes, pathogenic processes also impinge on the DGC, causing alterations in the abundance of dystrophin and associated proteins during cardiac insult such as ischemia-reperfusion injury, mechanical unloading, and myocarditis. When considering new therapeutic strategies, it is important to assess DGC remodeling as a common factor in various heart diseases. The DGC connects the internal F-actin-based cytoskeleton to laminin-211 of the extracellular space, playing an important role in the transmission of mechanical force to the extracellular matrix. The essential functions of dystrophin and the DGC have been long recognized. DGC based therapeutic approaches have been primarily focused on muscular dystrophies, however it may be a beneficial target in a number of disorders that affect the heart. This review provides an account of what we now know, and discusses how this knowledge can benefit persistent health conditions in the clinic.
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Affiliation(s)
- Isela C Valera
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Amanda L Wacker
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Hyun Seok Hwang
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Christina Holmes
- Department of Chemical and Biomedical Engineering, Florida A&M University-Florida State University College of Engineering, Tallahassee, FL, USA
| | - Orlando Laitano
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA
| | - Andrew P Landstrom
- Department of Pediatrics, Division of Cardiology, Duke University School of Medicine, Durham, NC, USA; Department of Cell Biology, Duke University School of Medicine, Durham, NC, USA
| | - Michelle S Parvatiyar
- Department of Nutrition, Food and Exercise Sciences, Florida State University, Tallahassee, FL, USA.
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11
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Gibbs EM, McCourt JL, Shin KM, Hammond KG, Marshall JL, Crosbie RH. Loss of sarcospan exacerbates pathology in mdx mice, but does not affect utrophin amelioration of disease. Hum Mol Genet 2021; 30:149-159. [PMID: 33432327 PMCID: PMC8091037 DOI: 10.1093/hmg/ddaa264] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Revised: 10/26/2020] [Accepted: 11/30/2020] [Indexed: 01/02/2023] Open
Abstract
The dystrophin-glycoprotein complex (DGC) is a membrane adhesion complex that provides structural stability at the sarcolemma by linking the myocyte's internal cytoskeleton and external extracellular matrix. In Duchenne muscular dystrophy (DMD), the absence of dystrophin leads to the loss of the DGC at the sarcolemma, resulting in sarcolemmal instability and progressive muscle damage. Utrophin (UTRN), an autosomal homolog of dystrophin, is upregulated in dystrophic muscle and partially compensates for the loss of dystrophin in muscle from patients with DMD. Here, we examine the interaction between Utr and sarcospan (SSPN), a small transmembrane protein that is a core component of both UTRN-glycoprotein complex (UGC) and DGC. We show that additional loss of SSPN causes an earlier onset of disease in dystrophin-deficient mdx mice by reducing the expression of the UGC at the sarcolemma. In order to further evaluate the role of SSPN in maintaining therapeutic levels of Utr at the sarcolemma, we tested the effect of Utr transgenic overexpression in mdx mice lacking SSPN (mdx:SSPN -/-:Utr-Tg). We found that overexpression of Utr restored SSPN to the sarcolemma in mdx muscle but that the ablation of SSPN in mdx muscle reduced Utr at the membrane. Nevertheless, Utr overexpression reduced central nucleation and improved grip strength in both lines. These findings demonstrate that high levels of Utr transgenic overexpression ameliorate the mdx phenotype independently of SSPN expression but that loss of SSPN may impair Utr-based mechanisms that rely on lower levels of Utr protein.
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Affiliation(s)
- Elizabeth M Gibbs
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA
| | - Jackie L McCourt
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA
| | - Kara M Shin
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA
| | - Katherine G Hammond
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA
| | - Jamie L Marshall
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA
| | - Rachelle H Crosbie
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA.,Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.,Molecular Biology Institute, University of California, Los Angeles, CA, USA
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12
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Bawa S, Gameros S, Baumann K, Brooks DS, Kollhoff JA, Zolkiewski M, Re Cecconi AD, Panini N, Russo M, Piccirillo R, Johnson DK, Kashipathy MM, Battaile KP, Lovell S, Bouyain SEA, Kawakami J, Geisbrecht ER. Costameric integrin and sarcoglycan protein levels are altered in a Drosophila model for Limb-girdle muscular dystrophy type 2H. Mol Biol Cell 2020; 32:260-273. [PMID: 33296226 PMCID: PMC8098830 DOI: 10.1091/mbc.e20-07-0453] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mutations in two different domains of the ubiquitously expressed TRIM32 protein give rise to two clinically separate diseases, one of which is Limb-girdle muscular dystrophy type 2H (LGMD2H). Uncovering the muscle-specific role of TRIM32 in LGMD2H pathogenesis has proven difficult, as neurogenic phenotypes, independent of LGMD2H pathology, are present in TRIM32 KO mice. We previously established a platform to study LGMD2H pathogenesis using Drosophila melanogaster as a model. Here we show that LGMD2H disease-causing mutations in the NHL domain are molecularly and structurally conserved between fly and human TRIM32. Furthermore, transgenic expression of a subset of myopathic alleles (R394H, D487N, and 520fs) induce myofibril abnormalities, altered nuclear morphology, and reduced TRIM32 protein levels, mimicking phenotypes in patients afflicted with LGMD2H. Intriguingly, we also report for the first time that the protein levels of βPS integrin and sarcoglycan δ, both core components of costameres, are elevated in TRIM32 disease-causing alleles. Similarly, murine myoblasts overexpressing a catalytically inactive TRIM32 mutant aberrantly accumulate α- and β-dystroglycan and α-sarcoglycan. We speculate that the stoichiometric loss of costamere components disrupts costamere complexes to promote muscle degeneration.
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Affiliation(s)
- Simranjot Bawa
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
| | - Samantha Gameros
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
| | - Kenny Baumann
- School of Biological Sciences, University of Missouri-Kansas City, MO 64110
| | - David S Brooks
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
| | - Joseph A Kollhoff
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
| | - Michal Zolkiewski
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506
| | | | - Nicolò Panini
- Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, 20156 Milan, Italy
| | - Massimo Russo
- Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, 20156 Milan, Italy
| | | | - David K Johnson
- Molecular Graphics and Modeling Laboratory, Computational Chemical Biology Core, University of Kansas, Lawrence, KS 66047
| | | | | | - Scott Lovell
- Protein Structure Laboratory, University of Kansas, Lawrence, KS 66047
| | - Samuel E A Bouyain
- School of Biological Sciences, University of Missouri-Kansas City, MO 64110
| | - Jessica Kawakami
- School of Biological Sciences, University of Missouri-Kansas City, MO 64110
| | - Erika R Geisbrecht
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506.,School of Biological Sciences, University of Missouri-Kansas City, MO 64110
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13
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The sockeye salmon genome, transcriptome, and analyses identifying population defining regions of the genome. PLoS One 2020; 15:e0240935. [PMID: 33119641 PMCID: PMC7595290 DOI: 10.1371/journal.pone.0240935] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 10/06/2020] [Indexed: 12/12/2022] Open
Abstract
Sockeye salmon (Oncorhynchus nerka) is a commercially and culturally important species to the people that live along the northern Pacific Ocean coast. There are two main sockeye salmon ecotypes—the ocean-going (anadromous) ecotype and the fresh-water ecotype known as kokanee. The goal of this study was to better understand the population structure of sockeye salmon and identify possible genomic differences among populations and between the two ecotypes. In pursuit of this goal, we generated the first reference sockeye salmon genome assembly and an RNA-seq transcriptome data set to better annotate features of the assembly. Resequenced whole-genomes of 140 sockeye salmon and kokanee were analyzed to understand population structure and identify genomic differences between ecotypes. Three distinct geographic and genetic groups were identified from analyses of the resequencing data. Nucleotide variants in an immunoglobulin heavy chain variable gene cluster on chromosome 26 were found to differentiate the northwestern group from the southern and upper Columbia River groups. Several candidate genes were found to be associated with the kokanee ecotype. Many of these genes were related to ammonia tolerance or vision. Finally, the sex chromosomes of this species were better characterized, and an alternative sex-determination mechanism was identified in a subset of upper Columbia River kokanee.
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14
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Shu C, Parfenova L, Mokhonova E, Collado JR, Damoiseaux R, Campagna J, John V, Crosbie RH. High-throughput screening identifies modulators of sarcospan that stabilize muscle cells and exhibit activity in the mouse model of Duchenne muscular dystrophy. Skelet Muscle 2020; 10:26. [PMID: 32948250 PMCID: PMC7499884 DOI: 10.1186/s13395-020-00244-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/01/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Duchenne muscular dystrophy (DMD) is a degenerative muscle disease caused by mutations in the dystrophin gene. Loss of dystrophin prevents the formation of a critical connection between the muscle cell membrane and the extracellular matrix. Overexpression of sarcospan (SSPN) in the mouse model of DMD restores the membrane connection and reduces disease severity, making SSPN a promising therapeutic target for pharmacological upregulation. METHODS Using a previously described cell-based promoter reporter assay of SSPN gene expression (hSSPN-EGFP), we conducted high-throughput screening on libraries of over 200,000 curated small molecules to identify SSPN modulators. The hits were validated in both hSSPN-EGFP and hSSPN-luciferase reporter cells. Hit selection was conducted on dystrophin-deficient mouse and human myotubes with assessments of (1) SSPN gene expression using quantitative PCR and (2) SSPN protein expression using immunoblotting and an ELISA. A membrane stability assay using osmotic shock was used to validate the functional effects of treatment followed by cell surface biotinylation to label cell surface proteins. Dystrophin-deficient mdx mice were treated with compound, and muscle was subjected to quantitative PCR to assess SSPN gene expression. RESULTS We identified and validated lead compounds that increased SSPN gene and protein expression in dystrophin-deficient mouse and human muscle cells. The lead compound OT-9 increased cell membrane localization of compensatory laminin-binding adhesion complexes and improved membrane stability in DMD myotubes. We demonstrated that the membrane stabilizing benefit is dependent on SSPN. Intramuscular injection of OT-9 in the mouse model of DMD increased SSPN gene expression. CONCLUSIONS This study identifies a pharmacological approach to treat DMD and sets the path for the development of SSPN-based therapies.
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Affiliation(s)
- Cynthia Shu
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA, USA
- Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA
- Center for Duchenne Muscular Dystrophy, University of California Los Angeles, Los Angeles, CA, USA
| | - Liubov Parfenova
- Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA
| | - Ekaterina Mokhonova
- Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA
- Center for Duchenne Muscular Dystrophy, University of California Los Angeles, Los Angeles, CA, USA
| | - Judd R Collado
- Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA
| | - Robert Damoiseaux
- Department of Molecular and Medicinal Pharmacology, University of California Los Angeles, Los Angeles, CA, USA
- California NanoSystems Institute, University of California Los Angeles, Los Angeles, CA, USA
| | - Jesus Campagna
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA
- Drug Discovery Lab, University of California Los Angeles, Los Angeles, CA, USA
| | - Varghese John
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA
- Drug Discovery Lab, University of California Los Angeles, Los Angeles, CA, USA
| | - Rachelle H Crosbie
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA.
- Center for Duchenne Muscular Dystrophy, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Neurology, David Geffen School of Medicine, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA.
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15
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Shu C, Kaxon-Rupp AN, Collado JR, Damoiseaux R, Crosbie RH. Development of a high-throughput screen to identify small molecule enhancers of sarcospan for the treatment of Duchenne muscular dystrophy. Skelet Muscle 2019; 9:32. [PMID: 31831063 PMCID: PMC6907331 DOI: 10.1186/s13395-019-0218-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 12/04/2019] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Duchenne muscular dystrophy (DMD) is caused by loss of sarcolemma connection to the extracellular matrix. Transgenic overexpression of the transmembrane protein sarcospan (SSPN) in the DMD mdx mouse model significantly reduces disease pathology by restoring membrane adhesion. Identifying SSPN-based therapies has the potential to benefit patients with DMD and other forms of muscular dystrophies caused by deficits in muscle cell adhesion. METHODS Standard cloning methods were used to generate C2C12 myoblasts stably transfected with a fluorescence reporter for human SSPN promoter activity. Assay development and screening were performed in a core facility using liquid handlers and imaging systems specialized for use with a 384-well microplate format. Drug-treated cells were analyzed for target gene expression using quantitative PCR and target protein expression using immunoblotting. RESULTS We investigated the gene expression profiles of SSPN and its associated proteins during myoblast differentiation into myotubes, revealing an increase in expression after 3 days of differentiation. We created C2C12 muscle cells expressing an EGFP reporter for SSPN promoter activity and observed a comparable increase in reporter levels during differentiation. Assay conditions for high-throughput screening were optimized for a 384-well microplate format and a high-content imager for the visualization of reporter levels. We conducted a screen of 3200 compounds and identified seven hits, which include an overrepresentation of L-type calcium channel antagonists, suggesting that SSPN gene activity is sensitive to calcium. Further validation of a select hit revealed that the calcium channel inhibitor felodipine increased SSPN transcript and protein levels in both wild-type and dystrophin-deficient myotubes, without increasing differentiation. CONCLUSIONS We developed a stable muscle cell line containing the promoter region of the human SSPN protein fused to a fluorescent reporter. Using the reporter cells, we created and validated a scalable, cell-based assay that is able to identify compounds that increase SSPN promoter reporter, transcript, and protein levels in wild-type and dystrophin-deficient muscle cells.
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Affiliation(s)
- Cynthia Shu
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, USA.,Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA.,Center for Duchenne Muscular Dystrophy, University of California Los Angeles, Los Angeles, USA
| | - Ariana N Kaxon-Rupp
- Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA
| | - Judd R Collado
- Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA
| | - Robert Damoiseaux
- Department of Molecular and Medicinal Pharmacology, University of California Los Angeles, Los Angeles, USA.,California NanoSystems Institute, University of California Los Angeles, Los Angeles, CA, USA
| | - Rachelle H Crosbie
- Molecular Biology Institute, University of California Los Angeles, Los Angeles, USA. .,Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA. .,Center for Duchenne Muscular Dystrophy, University of California Los Angeles, Los Angeles, USA. .,Department of Neurology David Geffen School of Medicine, University of California Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA.
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16
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Nielsen MH, Sabaratnam R, Pedersen AJT, Højlund K, Handberg A. Acute Exercise Increases Plasma Levels of Muscle-Derived Microvesicles Carrying Fatty Acid Transport Proteins. J Clin Endocrinol Metab 2019; 104:4804-4814. [PMID: 30933285 DOI: 10.1210/jc.2018-02547] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 03/26/2019] [Indexed: 02/03/2023]
Abstract
CONTEXT Microvesicles (MVs) are a class of membrane particles shed by any cell in the body in physiological and pathological conditions. They are considered to be key players in intercellular communication, and with a molecular content reflecting the composition of the cell of origin, they have recently emerged as a promising source of biomarkers in a number of diseases. OBJECTIVE The effects of acute exercise on the plasma concentration of skeletal muscle-derived MVs (SkMVs) carrying metabolically important membrane proteins were examined. PARTICIPANTS Thirteen men with obesity and type 2 diabetes mellitus (T2DM) and 14 healthy male controls with obesity exercised on a cycle ergometer for 60 minutes. INTERVENTIONS Muscle biopsies and blood samples-obtained before exercise, immediately after exercise, and 3 hours into recovery-were collected for the analysis of long-chain fatty acid (LCFA) transport proteins CD36 (a scavenger receptor class B protein) and fatty acid transport protein 4 (FATP4) mRNA content in muscle and for flow cytometric studies on circulating SkMVs carrying either LCFA transport protein. RESULTS Besides establishing a flow cytometric approach for the detection of circulating SkMVs and subpopulations carrying either CD36 or FATP4 and thereby adding proof to their existence, we demonstrated an overall exercise-induced change of SkMVs carrying these LCFA transport proteins. A positive correlation between exercise-induced changes in skeletal muscle CD36 mRNA expression and concentrations of SkMVs carrying CD36 was found in T2DM only. CONCLUSIONS This approach could add important real-time information about the abundance of LCFA transport proteins present on activated muscle cells in subjects with impaired glucose metabolism.
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Affiliation(s)
| | - Rugivan Sabaratnam
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
- Section of Molecular Diabetes and Metabolism, Institute of Molecular Medicine and Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Andreas James Thestrup Pedersen
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
- Section of Molecular Diabetes and Metabolism, Institute of Molecular Medicine and Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Kurt Højlund
- Steno Diabetes Center Odense, Odense University Hospital, Odense, Denmark
- Section of Molecular Diabetes and Metabolism, Institute of Molecular Medicine and Institute of Clinical Research, University of Southern Denmark, Odense, Denmark
| | - Aase Handberg
- Department of Clinical Biochemistry, Aalborg University Hospital, Aalborg, Denmark
- Department of Clinical Medicine, Faculty of Medicine, Aalborg University, Aalborg, Denmark
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17
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Parvatiyar MS, Brownstein AJ, Kanashiro-Takeuchi RM, Collado JR, Dieseldorff Jones KM, Gopal J, Hammond KG, Marshall JL, Ferrel A, Beedle AM, Chamberlain JS, Renato Pinto J, Crosbie RH. Stabilization of the cardiac sarcolemma by sarcospan rescues DMD-associated cardiomyopathy. JCI Insight 2019; 5:123855. [PMID: 31039133 PMCID: PMC6629091 DOI: 10.1172/jci.insight.123855] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Accepted: 04/23/2019] [Indexed: 02/02/2023] Open
Abstract
In the current preclinical study, we demonstrate the therapeutic potential of sarcospan (SSPN) overexpression to alleviate cardiomyopathy associated with Duchenne muscular dystrophy (DMD) utilizing dystrophin-deficient mdx mice with utrophin haploinsufficiency that more accurately represent the severe disease course of human DMD. SSPN interacts with dystrophin, the DMD disease gene product, and its autosomal paralog utrophin, which is upregulated in DMD as a partial compensatory mechanism. SSPN transgenic mice have enhanced abundance of fully glycosylated α-dystroglycan, which may further protect dystrophin-deficient cardiac membranes. Baseline echocardiography reveals SSPN improves systolic function and hypertrophic indices in mdx and mdx:utr-heterozygous mice. Assessment of SSPN transgenic mdx mice by hemodynamic pressure-volume methods highlights enhanced systolic performance compared to mdx controls. SSPN restores cardiac sarcolemma stability, the primary defect in DMD disease, reduces fibrotic response and improves contractile function. We demonstrate that SSPN ameliorates more advanced cardiac disease in the context of diminished sarcolemma expression of utrophin and β1D integrin that mitigate disease severity and partially restores responsiveness to β-adrenergic stimulation. Overall, our current and previous findings suggest SSPN overexpression in DMD mouse models positively impacts skeletal, pulmonary and cardiac performance by addressing the stability of proteins at the sarcolemma that protect the heart from injury, supporting SSPN and membrane stabilization as a therapeutic target for DMD.
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Affiliation(s)
- Michelle S. Parvatiyar
- Department of Integrative Biology & Physiology and
- Center for Duchenne Muscular Dystrophy, UCLA, Los Angeles, California, USA
| | - Alexandra J. Brownstein
- Department of Integrative Biology & Physiology and
- Center for Duchenne Muscular Dystrophy, UCLA, Los Angeles, California, USA
| | - Rosemeire M. Kanashiro-Takeuchi
- Interdisciplinary Stem Cell Institute, University of Miami, Florida, USA
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, USA
| | | | | | - Jay Gopal
- Department of Integrative Biology & Physiology and
| | - Katherine G. Hammond
- Department of Integrative Biology & Physiology and
- Center for Duchenne Muscular Dystrophy, UCLA, Los Angeles, California, USA
| | - Jamie L. Marshall
- Department of Integrative Biology & Physiology and
- Center for Duchenne Muscular Dystrophy, UCLA, Los Angeles, California, USA
| | - Abel Ferrel
- Department of Integrative Biology & Physiology and
| | - Aaron M. Beedle
- Department of Pharmaceutical Sciences, Binghamton University State University of New York, Binghamton, New York, USA
| | | | - Jose Renato Pinto
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, USA
| | - Rachelle H. Crosbie
- Department of Integrative Biology & Physiology and
- Center for Duchenne Muscular Dystrophy, UCLA, Los Angeles, California, USA
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, California, USA
- Molecular Biology Institute, UCLA, Los Angeles, California, USA
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18
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Larsson L, Degens H, Li M, Salviati L, Lee YI, Thompson W, Kirkland JL, Sandri M. Sarcopenia: Aging-Related Loss of Muscle Mass and Function. Physiol Rev 2019; 99:427-511. [PMID: 30427277 DOI: 10.1152/physrev.00061.2017] [Citation(s) in RCA: 734] [Impact Index Per Article: 146.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Sarcopenia is a loss of muscle mass and function in the elderly that reduces mobility, diminishes quality of life, and can lead to fall-related injuries, which require costly hospitalization and extended rehabilitation. This review focuses on the aging-related structural changes and mechanisms at cellular and subcellular levels underlying changes in the individual motor unit: specifically, the perikaryon of the α-motoneuron, its neuromuscular junction(s), and the muscle fibers that it innervates. Loss of muscle mass with aging, which is largely due to the progressive loss of motoneurons, is associated with reduced muscle fiber number and size. Muscle function progressively declines because motoneuron loss is not adequately compensated by reinnervation of muscle fibers by the remaining motoneurons. At the intracellular level, key factors are qualitative changes in posttranslational modifications of muscle proteins and the loss of coordinated control between contractile, mitochondrial, and sarcoplasmic reticulum protein expression. Quantitative and qualitative changes in skeletal muscle during the process of aging also have been implicated in the pathogenesis of acquired and hereditary neuromuscular disorders. In experimental models, specific intervention strategies have shown encouraging results on limiting deterioration of motor unit structure and function under conditions of impaired innervation. Translated to the clinic, if these or similar interventions, by saving muscle and improving mobility, could help alleviate sarcopenia in the elderly, there would be both great humanitarian benefits and large cost savings for health care systems.
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Affiliation(s)
- Lars Larsson
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Hans Degens
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Meishan Li
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Leonardo Salviati
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Young Il Lee
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Wesley Thompson
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - James L Kirkland
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
| | - Marco Sandri
- Department of Physiology and Pharmacology, Basic and Clinical Muscle Biology Group, Karolinska Institutet , Stockholm , Sweden ; Section of Clinical Neurophysiology, Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden ; Department of Biobehavioral Health, The Pennsylvania State University , University Park, Pennsylvania ; School of Healthcare Science, Metropolitan University , Manchester , United Kingdom ; Institute of Sport Science and Innovations, Lithuanian Sports University , Kaunas , Lithuania ; Clinical Genetics Unit, Department of Woman and Child Health, University of Padova , Padova , Italy ; IRP Città della Speranza, Padova , Italy ; Department of Biology, Texas A&M University , College Station, Texas ; Robert and Arlene Kogod Center on Aging, Mayo Clinic , Rochester, Minnesota ; Department of Biomedical Science, Venetian Institute of Molecular Medicine, University of Padova , Padova , Italy
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19
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Sarcoglycan Alpha Mitigates Neuromuscular Junction Decline in Aged Mice by Stabilizing LRP4. J Neurosci 2018; 38:8860-8873. [PMID: 30171091 DOI: 10.1523/jneurosci.0860-18.2018] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 08/07/2018] [Accepted: 08/22/2018] [Indexed: 01/08/2023] Open
Abstract
During aging, acetylcholine receptor (AChR) clusters become fragmented and denervated at the neuromuscular junction (NMJ). Underpinning molecular mechanisms are not well understood. We showed that LRP4, a receptor for agrin and critical for NMJ formation and maintenance, was reduced at protein level in aged mice, which was associated with decreased MuSK tyrosine phosphorylation, suggesting compromised agrin-LRP4-MuSK signaling in aged muscles. Transgenic expression of LRP4 in muscles alleviated AChR fragmentation and denervation and improved neuromuscular transmission in aged mice. LRP4 ubiquitination was augmented in aged muscles, suggesting increased LRP4 degradation as a mechanism for reduced LRP4. We found that sarcoglycan α (SGα) interacted with LRP4 and delayed LRP4 degradation in cotransfected cells. AAV9-mediated expression of SGα in muscles mitigated AChR fragmentation and denervation and improved neuromuscular transmission in aged mice. These observations support a model where compromised agrin-LRP4-MuSK signaling serves as a pathological mechanism of age-related NMJ decline and identify a novel function of SGα in stabilizing LRP4 for NMJ stability in aged mice.SIGNIFICANCE STATEMENT This study provides evidence that LRP4, a receptor of agrin that is critical for NMJ formation and maintenance, is reduced at protein level in aged muscles. Transgenic expression of LRP4 in muscles ameliorates AChR fragmentation and denervation and improves neuromuscular transmission in aged mice, demonstrating a critical role of the agrin-LRP4-MuSK signaling. Our study also reveals a novel function of SGα to prevent LRP4 degradation in aged muscles. Finally, we show that NMJ decline in aged mice can be mitigated by AAV9-mediated expression of SGα in muscles. These observations provide insight into pathological mechanisms of age-related NMJ decline and suggest that improved agrin-LRP4-MuSK signaling may be a target for potential therapeutic intervention.
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20
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Leyva-Leyva M, Sandoval A, Felix R, González-Ramírez R. Biochemical and Functional Interplay Between Ion Channels and the Components of the Dystrophin-Associated Glycoprotein Complex. J Membr Biol 2018; 251:535-550. [PMID: 29779049 DOI: 10.1007/s00232-018-0036-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 05/09/2018] [Indexed: 12/19/2022]
Abstract
Dystrophin is a cytoskeleton-linked membrane protein that binds to a larger multiprotein assembly called the dystrophin-associated glycoprotein complex (DGC). The deficiency of dystrophin or the components of the DGC results in the loss of connection between the cytoskeleton and the extracellular matrix with significant pathophysiological implications in skeletal and cardiac muscle as well as in the nervous system. Although the DGC plays an important role in maintaining membrane stability, it can also be considered as a versatile and flexible molecular complex that contribute to the cellular organization and dynamics of a variety of proteins at specific locations in the plasma membrane. This review deals with the role of the DGC in transmembrane signaling by forming supramolecular assemblies for regulating ion channel localization and activity. These interactions are relevant for cell homeostasis, and its alterations may play a significant role in the etiology and pathogenesis of various disorders affecting muscle and nerve function.
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Affiliation(s)
- Margarita Leyva-Leyva
- Department of Molecular Biology and Histocompatibility, "Dr. Manuel Gea González" General Hospital, Mexico City, Mexico
| | - Alejandro Sandoval
- Faculty of Superior Studies Iztacala, National Autonomous University of Mexico (UNAM), Tlalnepantla, Mexico
| | - Ricardo Felix
- Department of Cell Biology, Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico.
| | - Ricardo González-Ramírez
- Department of Molecular Biology and Histocompatibility, "Dr. Manuel Gea González" General Hospital, Mexico City, Mexico.
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21
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Gawor M, Prószyński TJ. The molecular cross talk of the dystrophin-glycoprotein complex. Ann N Y Acad Sci 2017; 1412:62-72. [DOI: 10.1111/nyas.13500] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/29/2017] [Accepted: 09/04/2017] [Indexed: 12/25/2022]
Affiliation(s)
- Marta Gawor
- Laboratory of Synaptogenesis; Nencki Institute of Experimental Biology; Polish Academy of Sciences Warsaw Poland
| | - Tomasz J. Prószyński
- Laboratory of Synaptogenesis; Nencki Institute of Experimental Biology; Polish Academy of Sciences Warsaw Poland
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22
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Van Ry PM, Fontelonga TM, Barraza-Flores P, Sarathy A, Nunes AM, Burkin DJ. ECM-Related Myopathies and Muscular Dystrophies: Pros and Cons of Protein Therapies. Compr Physiol 2017; 7:1519-1536. [PMID: 28915335 DOI: 10.1002/cphy.c150033] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Extracellular matrix (ECM) myopathies and muscular dystrophies are a group of genetic diseases caused by mutations in genes encoding proteins that provide critical links between muscle cells and the extracellular matrix. These include structural proteins of the ECM, muscle cell receptors, enzymes, and intracellular proteins. Loss of adhesion within the myomatrix results in progressive muscle weakness. For many ECM muscular dystrophies, symptoms can occur any time after birth and often result in reduced life expectancy. There are no cures for the ECM-related muscular dystrophies and treatment options are limited to palliative care. Several therapeutic approaches have been explored to treat muscular dystrophies including gene therapy, gene editing, exon skipping, embryonic, and adult stem cell therapy, targeting genetic modifiers, modulating inflammatory responses, or preventing muscle degeneration. Recently, protein therapies that replace components of the defective myomatrix or enhance muscle and/or extracellular matrix integrity and function have been explored. Preclinical studies for many of these biologics have been promising in animal models of these muscle diseases. This review aims to summarize the ECM muscular dystrophies for which protein therapies are being developed and discuss the exciting potential and possible limitations of this approach for treating this family of devastating genetic muscle diseases. © 2017 American Physiological Society. Compr Physiol 7:1519-1536, 2017.
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Affiliation(s)
- Pam M Van Ry
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Tatiana M Fontelonga
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Pamela Barraza-Flores
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Apurva Sarathy
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
| | - Andreia M Nunes
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA.,Departamento de Biologia Animal, Centro de Ecologia, Evolucao e Alteracoes Ambientais, Faculdade de Ciencias, Universidade de Lisboa, Lisbon, Portugal
| | - Dean J Burkin
- Department of Pharmacology, University of Nevada School of Medicine, Reno, Nevada, USA
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23
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Cox ML, Evans JM, Davis AG, Guo LT, Levy JR, Starr-Moss AN, Salmela E, Hytönen MK, Lohi H, Campbell KP, Clark LA, Shelton GD. Exome sequencing reveals independent SGCD deletions causing limb girdle muscular dystrophy in Boston terriers. Skelet Muscle 2017; 7:15. [PMID: 28697784 PMCID: PMC5506588 DOI: 10.1186/s13395-017-0131-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 06/23/2017] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Limb-girdle muscular dystrophies (LGMDs) are a heterogeneous group of inherited autosomal myopathies that preferentially affect voluntary muscles of the shoulders and hips. LGMD has been clinically described in several breeds of dogs, but the responsible mutations are unknown. The clinical presentation in dogs is characterized by marked muscle weakness and atrophy in the shoulder and hips during puppyhood. METHODS Following clinical evaluation, the identification of the dystrophic histological phenotype on muscle histology, and demonstration of the absence of sarcoglycan-sarcospan complex by immunostaining, whole exome sequencing was performed on five Boston terriers: one affected dog and its three family members and one unrelated affected dog. RESULTS Within sarcoglycan-δ (SGCD), a two base pair deletion segregating with LGMD in the family was discovered, and a deletion encompassing exons 7 and 8 was found in the unrelated dog. Both mutations are predicted to cause an absence of SGCD protein, confirmed by immunohistochemistry. The mutations are private to each family. CONCLUSIONS Here, we describe the first cases of canine LGMD characterized at the molecular level with the classification of LGMD2F.
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Affiliation(s)
- Melissa L. Cox
- CAG GmbH - Center for Animal Genetics, Paul-Ehrlich-Str. 23, 72076 Tubingen, Germany
| | - Jacquelyn M. Evans
- Department of Genetics and Biochemistry, Clemson University, 130 McGinty Ct., Clemson, SC 29634 USA
| | - Alexander G. Davis
- Department of Genetics and Biochemistry, Clemson University, 130 McGinty Ct., Clemson, SC 29634 USA
| | - Ling T. Guo
- Department of Pathology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 USA
| | - Jennifer R. Levy
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology, The University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, Iowa 52242-1101 USA
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, Iowa 52242 USA
| | - Alison N. Starr-Moss
- Department of Genetics and Biochemistry, Clemson University, 130 McGinty Ct., Clemson, SC 29634 USA
| | - Elina Salmela
- Department of Veterinary Biosciences and Research Programs Unit, University of Helsinki, Haartmaninkatu 8, FI-00290 Helsinki, Finland
- Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Marjo K. Hytönen
- Department of Veterinary Biosciences and Research Programs Unit, University of Helsinki, Haartmaninkatu 8, FI-00290 Helsinki, Finland
- Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Hannes Lohi
- Department of Veterinary Biosciences and Research Programs Unit, University of Helsinki, Haartmaninkatu 8, FI-00290 Helsinki, Finland
- Folkhälsan Institute of Genetics, Helsinki, Finland
| | - Kevin P. Campbell
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology, The University of Iowa Roy J. and Lucille A. Carver College of Medicine, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, Iowa 52242-1101 USA
- Department of Neurology, Roy J. and Lucille A. Carver College of Medicine, The University of Iowa, 4283 Carver Biomedical Research Building, 285 Newton Road, Iowa City, Iowa 52242 USA
| | - Leigh Anne Clark
- Department of Genetics and Biochemistry, Clemson University, 130 McGinty Ct., Clemson, SC 29634 USA
| | - G. Diane Shelton
- Department of Pathology, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 USA
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24
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Bhat HF, Mir SS, Dar KB, Bhat ZF, Shah RA, Ganai NA. ABC of multifaceted dystrophin glycoprotein complex (DGC). J Cell Physiol 2017; 233:5142-5159. [DOI: 10.1002/jcp.25982] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 05/01/2017] [Indexed: 01/16/2023]
Affiliation(s)
- Hina F. Bhat
- Division of BiotechnologySher‐e‐Kashmir University of Agricultural Sciences and Technology of Kashmir SKUAST‐KShuhama, SrinagarJammu and KashmirIndia
| | - Saima S. Mir
- Department of BiotechnologyUniversity of KashmirHazratbal, SrinagarJammu and KashmirIndia
| | - Khalid B. Dar
- Department of BiochemistryUniversity of KashmirHazratbal, SrinagarJammu and KashmirIndia
| | - Zuhaib F. Bhat
- Division of Livestock Products and TechnologySher‐e‐Kashmir University of Agricultural Sciences and Technology of Jammu (SKUAST‐J), R.S. PoraJammuJammu and KashmirIndia
| | - Riaz A. Shah
- Division of BiotechnologySher‐e‐Kashmir University of Agricultural Sciences and Technology of Kashmir SKUAST‐KShuhama, SrinagarJammu and KashmirIndia
| | - Nazir A. Ganai
- Division of BiotechnologySher‐e‐Kashmir University of Agricultural Sciences and Technology of Kashmir SKUAST‐KShuhama, SrinagarJammu and KashmirIndia
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25
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Abstract
Cardiac and skeletal striated muscles are intricately designed machines responsible for muscle contraction. Coordination of the basic contractile unit, the sarcomere, and the complex cytoskeletal networks are critical for contractile activity. The sarcomere is comprised of precisely organized individual filament systems that include thin (actin), thick (myosin), titin, and nebulin. Connecting the sarcomere to other organelles (e.g., mitochondria and nucleus) and serving as the scaffold to maintain cellular integrity are the intermediate filaments. The costamere, on the other hand, tethers the sarcomere to the cell membrane. Unique structures like the intercalated disc in cardiac muscle and the myotendinous junction in skeletal muscle help synchronize and transmit force. Intense investigation has been done on many of the proteins that make up these cytoskeletal assemblies. Yet the details of their function and how they interconnect have just started to be elucidated. A vast number of human myopathies are contributed to mutations in muscle proteins; thus understanding their basic function provides a mechanistic understanding of muscle disorders. In this review, we highlight the components of striated muscle with respect to their interactions, signaling pathways, functions, and connections to disease. © 2017 American Physiological Society. Compr Physiol 7:891-944, 2017.
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Affiliation(s)
- Christine A Henderson
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Christopher G Gomez
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Stefanie M Novak
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Lei Mi-Mi
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
| | - Carol C Gregorio
- Department of Cellular and Molecular Medicine, The University of Arizona, Tucson, Arizona, USA.,Sarver Molecular Cardiovascular Research Program, The University of Arizona, Tucson, Arizona, USA
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26
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Gibbs EM, Marshall JL, Ma E, Nguyen TM, Hong G, Lam JS, Spencer MJ, Crosbie-Watson RH. High levels of sarcospan are well tolerated and act as a sarcolemmal stabilizer to address skeletal muscle and pulmonary dysfunction in DMD. Hum Mol Genet 2017; 25:5395-5406. [PMID: 27798107 PMCID: PMC5418831 DOI: 10.1093/hmg/ddw356] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 10/13/2016] [Indexed: 12/27/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a genetic disorder that causes progressive muscle weakness, ultimately leading to early mortality in affected teenagers and young adults. Previous work from our lab has shown that a small transmembrane protein called sarcospan (SSPN) can enhance the recruitment of adhesion complex proteins to the cell surface. When human SSPN is expressed at three-fold levels in mdx mice, this increase in adhesion complex abundance improves muscle membrane stability, preventing many of the histopathological changes associated with DMD. However, expressing higher levels of human SSPN (ten-fold transgenic expression) causes a severe degenerative muscle phenotype in wild-type mice. Since SSPN-mediated stabilization of the sarcolemma represents a promising therapeutic strategy in DMD, it is important to determine whether SSPN can be introduced at high levels without toxicity. Here, we show that mouse SSPN (mSSPN) can be overexpressed at 30-fold levels in wild-type mice with no deleterious effects. In mdx mice, mSSPN overexpression improves dystrophic pathology and sarcolemmal stability. We show that these mice exhibit increased resistance to eccentric contraction-induced damage and reduced fatigue following exercise. mSSPN overexpression improved pulmonary function and reduced dystrophic histopathology in the diaphragm. Together, these results demonstrate that SSPN overexpression is well tolerated in mdx mice and improves sarcolemma defects that underlie skeletal muscle and pulmonary dysfunction in DMD.
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Affiliation(s)
- Elizabeth M Gibbs
- Department of Integrative Biology and Physiology.,Center for Duchenne Muscular Dystrophy
| | - Jamie L Marshall
- Department of Integrative Biology and Physiology.,Center for Duchenne Muscular Dystrophy
| | - Eva Ma
- Department of Integrative Biology and Physiology.,Center for Duchenne Muscular Dystrophy
| | - Thien M Nguyen
- Department of Integrative Biology and Physiology.,Center for Duchenne Muscular Dystrophy
| | - Grace Hong
- Department of Integrative Biology and Physiology.,Center for Duchenne Muscular Dystrophy
| | - Jessica S Lam
- Department of Integrative Biology and Physiology.,Center for Duchenne Muscular Dystrophy
| | - Melissa J Spencer
- Center for Duchenne Muscular Dystrophy.,Molecular Biology Institute, University of California Los Angeles CA 90095, USA
| | - Rachelle H Crosbie-Watson
- Department of Integrative Biology and Physiology.,Center for Duchenne Muscular Dystrophy.,Department of Neurology David Geffen School of Medicine.,Molecular Biology Institute, University of California Los Angeles CA 90095, USA
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27
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Peter AK, Miller G, Capote J, DiFranco M, Solares-Pérez A, Wang EL, Heighway J, Coral-Vázquez RM, Vergara J, Crosbie-Watson RH. Nanospan, an alternatively spliced isoform of sarcospan, localizes to the sarcoplasmic reticulum in skeletal muscle and is absent in limb girdle muscular dystrophy 2F. Skelet Muscle 2017; 7:11. [PMID: 28587652 PMCID: PMC5461684 DOI: 10.1186/s13395-017-0127-9] [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: 02/27/2017] [Accepted: 05/12/2017] [Indexed: 12/26/2022] Open
Abstract
Background Sarcospan (SSPN) is a transmembrane protein that interacts with the sarcoglycans (SGs) to form a tight subcomplex within the dystrophin-glycoprotein complex that spans the sarcolemma and interacts with laminin in the extracellular matrix. Overexpression of SSPN ameliorates Duchenne muscular dystrophy in murine models. Methods Standard cloning approaches were used to identify nanospan, and nanospan-specific polyclonal antibodies were generated and validated. Biochemical isolation of skeletal muscle membranes and two-photon laser scanning microscopy were used to analyze nanospan localization in muscle from multiple murine models. Duchenne muscular dystrophy biopsies were analyzed by immunoblot analysis of protein lysates as well as indirect immunofluorescence analysis of muscle cryosections. Results Nanospan is an alternatively spliced isoform of sarcospan. While SSPN has four transmembrane domains and is a core component of the sarcolemmal dystrophin-glycoprotein complex, nanospan is a type II transmembrane protein that does not associate with the dystrophin-glycoprotein complex. We demonstrate that nanospan is enriched in the sarcoplasmic reticulum (SR) fractions and is not present in the T-tubules. SR fractions contain membranes from three distinct structural regions: a region flanking the T-tubules (triadic SR), a SR region across the Z-line (ZSR), and a longitudinal SR region across the M-line (LSR). Analysis of isolated murine muscles reveals that nanospan is mostly associated with the ZSR and triadic SR, and only minimally with the LSR. Furthermore, nanospan is absent from the SR of δ-SG-null (Sgcd−/−) skeletal muscle, a murine model for limb girdle muscular dystrophy 2F. Analysis of skeletal muscle biopsies from Duchenne muscular dystrophy patients reveals that nanospan is preferentially expressed in type I (slow) fibers in both control and Duchenne samples. Furthermore, nanospan is significantly reduced in Duchenne biopsies. Conclusions Alternative splicing of proteins from the SG-SSPN complex produces δ-SG3, microspan, and nanospan that localize to the ZSR and the triadic SR, where they may play a role in regulating resting calcium levels as supported by previous studies (Estrada et al., Biochem Biophys Res Commun 340:865–71, 2006). Thus, alternative splicing of SSPN mRNA generates three protein isoforms (SSPN, microspan, and nanospan) that differ in the number of transmembrane domains affecting subcellular membrane association into distinct protein complexes. Electronic supplementary material The online version of this article (doi:10.1186/s13395-017-0127-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Angela K Peter
- Department of Integrative Biology and Physiology, University of California, Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA.,Present Address: Biofrontiers Institute, Department of Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO, USA
| | - Gaynor Miller
- Department of Integrative Biology and Physiology, University of California, Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA.,Present Address: Department of Oncology and Metabolism, University of Sheffield, Sheffield, UK
| | - Joana Capote
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA.,Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, Los Angeles, CA, USA
| | - Marino DiFranco
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, Los Angeles, CA, USA.,Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Alhondra Solares-Pérez
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Emily L Wang
- Department of Integrative Biology and Physiology, University of California, Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA
| | - Jim Heighway
- Cancer Communications and Consultancy Ltd, Knutsford, Cheshire, UK
| | - Ramón M Coral-Vázquez
- Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Julio Vergara
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, Los Angeles, CA, USA.,Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, USA
| | - Rachelle H Crosbie-Watson
- Department of Integrative Biology and Physiology, University of California, Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA. .,Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, 610 Charles E. Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA. .,Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, Los Angeles, CA, USA. .,Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA, USA.
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Arena S, Iacona R, Impellizzeri P, Russo T, Marseglia L, Gitto E, Romeo C. Physiopathology of vesico-ureteral reflux. Ital J Pediatr 2016; 42:103. [PMID: 27899160 PMCID: PMC5129198 DOI: 10.1186/s13052-016-0316-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 11/26/2016] [Indexed: 01/13/2023] Open
Abstract
Vescico-Ureteral Reflux (VUR) is a common condition in childhood, caused by a congenital anomaly at the Vescico-Ureteral Junction (VUJ) level. It seems that the main cause could be an abnormal embryological development occurred during the early stage of fetal life. Refluxing ureteral endings show structural and functional anomalies: previous studies have shown a significant decrease in alfa actin, miosin and desmin contents as well as an high rate of atrophy and muscular degeneration with disorganized muscular fibres. The roles played by Cajal cells and Connexin 43 in generating peristaltic waves appears to be fundamental for the physiological VUJ function and activity. Attention was focused also on the congenital muscular deficiency of the RUs, on regard to general morphology, smooth muscle cells architecture, inflammatory markers and the distribution of collagen composition. This review will discuss and investigate the importance of the modified configuration of Sarcoglycan (SG) sub complex (particularly the deficiency of the ε-SG and the increased expression of the α-SG), the role played by Cajal Cells, the intravescical tunnel length to ureteral diameter ratio as possible causes of the functional alterations in the refluxing ureteral ends leading towards the VUJ incompetence.
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Affiliation(s)
- Salvatore Arena
- Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi" - Unit of Paediatric Surgery, University of Messina, 98125, Messina, Italy.
| | - Roberta Iacona
- Unit of pediatric Surgery, Oxford University Hospital, Oxford, UK
| | - Pietro Impellizzeri
- Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi" - Unit of Paediatric Surgery, University of Messina, 98125, Messina, Italy
| | - Tiziana Russo
- Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi" - Unit of Paediatric Surgery, University of Messina, 98125, Messina, Italy
| | - Lucia Marseglia
- Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi" - Unit of Paediatrics, University of Messina, Messina, 98125, Italy
| | - Eloisa Gitto
- Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi" - Unit of Paediatrics, University of Messina, Messina, 98125, Italy
| | - Carmelo Romeo
- Department of Human Pathology in Adult and Developmental Age "Gaetano Barresi" - Unit of Paediatric Surgery, University of Messina, 98125, Messina, Italy
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Abstract
The dystrophin complex stabilizes the plasma membrane of striated muscle cells. Loss of function mutations in the genes encoding dystrophin, or the associated proteins, trigger instability of the plasma membrane, and myofiber loss. Mutations in dystrophin have been extensively cataloged, providing remarkable structure-function correlation between predicted protein structure and clinical outcomes. These data have highlighted dystrophin regions necessary for in vivo function and fueled the design of viral vectors and now, exon skipping approaches for use in dystrophin restoration therapies. However, dystrophin restoration is likely more complex, owing to the role of the dystrophin complex as a broad cytoskeletal integrator. This review will focus on dystrophin restoration, with emphasis on the regions of dystrophin essential for interacting with its associated proteins and discuss the structural implications of these approaches.
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Affiliation(s)
- Quan Q Gao
- Committee on Development, Regeneration and Stem Cell Biology, The University of Chicago, Chicago, Illinois, USA
| | - Elizabeth M McNally
- Center for Genetic Medicine, Northwestern University, Chicago, Chicago, Illinois, USA
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31
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Allen DG, Whitehead NP, Froehner SC. Absence of Dystrophin Disrupts Skeletal Muscle Signaling: Roles of Ca2+, Reactive Oxygen Species, and Nitric Oxide in the Development of Muscular Dystrophy. Physiol Rev 2016; 96:253-305. [PMID: 26676145 DOI: 10.1152/physrev.00007.2015] [Citation(s) in RCA: 272] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Dystrophin is a long rod-shaped protein that connects the subsarcolemmal cytoskeleton to a complex of proteins in the surface membrane (dystrophin protein complex, DPC), with further connections via laminin to other extracellular matrix proteins. Initially considered a structural complex that protected the sarcolemma from mechanical damage, the DPC is now known to serve as a scaffold for numerous signaling proteins. Absence or reduced expression of dystrophin or many of the DPC components cause the muscular dystrophies, a group of inherited diseases in which repeated bouts of muscle damage lead to atrophy and fibrosis, and eventually muscle degeneration. The normal function of dystrophin is poorly defined. In its absence a complex series of changes occur with multiple muscle proteins showing reduced or increased expression or being modified in various ways. In this review, we will consider the various proteins whose expression and function is changed in muscular dystrophies, focusing on Ca(2+)-permeable channels, nitric oxide synthase, NADPH oxidase, and caveolins. Excessive Ca(2+) entry, increased membrane permeability, disordered caveolar function, and increased levels of reactive oxygen species are early changes in the disease, and the hypotheses for these phenomena will be critically considered. The aim of the review is to define the early damage pathways in muscular dystrophy which might be appropriate targets for therapy designed to minimize the muscle degeneration and slow the progression of the disease.
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Affiliation(s)
- David G Allen
- Sydney Medical School & Bosch Institute, University of Sydney, New South Wales, Australia; and Department of Physiology & Biophysics, University of Washington, Seattle, Washington
| | - Nicholas P Whitehead
- Sydney Medical School & Bosch Institute, University of Sydney, New South Wales, Australia; and Department of Physiology & Biophysics, University of Washington, Seattle, Washington
| | - Stanley C Froehner
- Sydney Medical School & Bosch Institute, University of Sydney, New South Wales, Australia; and Department of Physiology & Biophysics, University of Washington, Seattle, Washington
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de Greef JC, Hamlyn R, Jensen BS, O'Campo Landa R, Levy JR, Kobuke K, Campbell KP. Collagen VI deficiency reduces muscle pathology, but does not improve muscle function, in the γ-sarcoglycan-null mouse. Hum Mol Genet 2016; 25:1357-69. [PMID: 26908621 PMCID: PMC4787905 DOI: 10.1093/hmg/ddw018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 01/18/2016] [Indexed: 01/19/2023] Open
Abstract
Muscular dystrophy is characterized by progressive skeletal muscle weakness and dystrophic muscle exhibits degeneration and regeneration of muscle cells, inflammation and fibrosis. Skeletal muscle fibrosis is an excessive deposition of components of the extracellular matrix including an accumulation of Collagen VI. We hypothesized that a reduction of Collagen VI in a muscular dystrophy model that presents with fibrosis would result in reduced muscle pathology and improved muscle function. To test this hypothesis, we crossed γ-sarcoglycan-null mice, a model of limb-girdle muscular dystrophy type 2C, with a Col6a2-deficient mouse model. We found that the resulting γ-sarcoglycan-null/Col6a2Δex5 mice indeed exhibit reduced muscle pathology compared with γ-sarcoglycan-null mice. Specifically, fewer muscle fibers are degenerating, fiber size varies less, Evans blue dye uptake is reduced and serum creatine kinase levels are lower. Surprisingly, in spite of this reduction in muscle pathology, muscle function is not significantly improved. In fact, grip strength and maximum isometric tetanic force are even lower in γ-sarcoglycan-null/Col6a2Δex5 mice than in γ-sarcoglycan-null mice. In conclusion, our results reveal that Collagen VI-mediated fibrosis contributes to skeletal muscle pathology in γ-sarcoglycan-null mice. Importantly, however, our data also demonstrate that a reduction in skeletal muscle pathology does not necessarily lead to an improvement of skeletal muscle function, and this should be considered in future translational studies.
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Affiliation(s)
- Jessica C de Greef
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology and Department of Internal Medicine, The University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Rebecca Hamlyn
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology and Department of Internal Medicine, The University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Braden S Jensen
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology and Department of Internal Medicine, The University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Raul O'Campo Landa
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology and Department of Internal Medicine, The University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Jennifer R Levy
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology and Department of Internal Medicine, The University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Kazuhiro Kobuke
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology and Department of Internal Medicine, The University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
| | - Kevin P Campbell
- Howard Hughes Medical Institute, Department of Molecular Physiology and Biophysics, Department of Neurology and Department of Internal Medicine, The University of Iowa Roy J. and Lucille A. Carver College of Medicine, Iowa City, IA 52242, USA
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Parvatiyar MS, Marshall JL, Nguyen RT, Jordan MC, Richardson VA, Roos KP, Crosbie-Watson RH. Sarcospan Regulates Cardiac Isoproterenol Response and Prevents Duchenne Muscular Dystrophy-Associated Cardiomyopathy. J Am Heart Assoc 2015; 4:JAHA.115.002481. [PMID: 26702077 PMCID: PMC4845268 DOI: 10.1161/jaha.115.002481] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Background Duchenne muscular dystrophy is a fatal cardiac and skeletal muscle disease resulting from mutations in the dystrophin gene. We have previously demonstrated that a dystrophin‐associated protein, sarcospan (SSPN), ameliorated Duchenne muscular dystrophy skeletal muscle degeneration by activating compensatory pathways that regulate muscle cell adhesion (laminin‐binding) to the extracellular matrix. Conversely, loss of SSPN destabilized skeletal muscle adhesion, hampered muscle regeneration, and reduced force properties. Given the importance of SSPN to skeletal muscle, we investigated the consequences of SSPN ablation in cardiac muscle and determined whether overexpression of SSPN into mdx mice ameliorates cardiac disease symptoms associated with Duchenne muscular dystrophy cardiomyopathy. Methods and Results SSPN‐null mice exhibited cardiac enlargement, exacerbated cardiomyocyte hypertrophy, and increased fibrosis in response to β‐adrenergic challenge (isoproterenol; 0.8 mg/day per 2 weeks). Biochemical analysis of SSPN‐null cardiac muscle revealed reduced sarcolemma localization of many proteins with a known role in cardiomyopathy pathogenesis: dystrophin, the sarcoglycans (α‐, δ‐, and γ‐subunits), and β1D integrin. Transgenic overexpression of SSPN in Duchenne muscular dystrophy mice (mdxTG) improved cardiomyofiber cell adhesion, sarcolemma integrity, cardiac functional parameters, as well as increased expression of compensatory transmembrane proteins that mediate attachment to the extracellular matrix. Conclusions SSPN regulates sarcolemmal expression of laminin‐binding complexes that are critical to cardiac muscle function and protects against transient and chronic injury, including inherited cardiomyopathy.
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Affiliation(s)
- Michelle S Parvatiyar
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA (M.S.P., J.L.M., R.T.N., V.A.R., R.H.C.W.) Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA (M.S.P., J.L.M., M.C.J., V.A.R., K.P.R., R.H.C.W.)
| | - Jamie L Marshall
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA (M.S.P., J.L.M., R.T.N., V.A.R., R.H.C.W.) Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA (M.S.P., J.L.M., M.C.J., V.A.R., K.P.R., R.H.C.W.)
| | - Reginald T Nguyen
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA (M.S.P., J.L.M., R.T.N., V.A.R., R.H.C.W.)
| | - Maria C Jordan
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA (M.S.P., J.L.M., M.C.J., V.A.R., K.P.R., R.H.C.W.) Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA (M.C.J., K.P.R.)
| | - Vanitra A Richardson
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA (M.S.P., J.L.M., R.T.N., V.A.R., R.H.C.W.) Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA (M.S.P., J.L.M., M.C.J., V.A.R., K.P.R., R.H.C.W.)
| | - Kenneth P Roos
- Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA (M.S.P., J.L.M., M.C.J., V.A.R., K.P.R., R.H.C.W.) Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, CA (M.C.J., K.P.R.)
| | - Rachelle H Crosbie-Watson
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA (M.S.P., J.L.M., R.T.N., V.A.R., R.H.C.W.) Center for Duchenne Muscular Dystrophy, University of California, Los Angeles, CA (M.S.P., J.L.M., M.C.J., V.A.R., K.P.R., R.H.C.W.) Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA (R.H.C.W.)
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Al-Zaidy SA, Malik V, Kneile K, Rosales XQ, Gomez AM, Lewis S, Hashimoto S, Gastier-Foster J, Kang P, Darras B, Kunkel L, Carlo J, Sahenk Z, Moore SA, Pyatt R, Mendell JR. A slowly progressive form of limb-girdle muscular dystrophy type 2C associated with founder mutation in the SGCG gene in Puerto Rican Hispanics. Mol Genet Genomic Med 2015; 3:92-8. [PMID: 25802879 PMCID: PMC4367081 DOI: 10.1002/mgg3.125] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 11/10/2014] [Accepted: 11/13/2014] [Indexed: 01/02/2023] Open
Abstract
Limb-girdle muscular dystrophy type 2C (LGMD2C) is considered one of the severe forms of childhood-onset muscular dystrophy. The geographical distribution of founder mutations in the SGCG gene has a prominent effect on the prevalence of LGMD2C in certain populations. The aim of this study was to confirm the hypothesis that the c.787G>A (p.E263K) mutation in the SGCG gene is a founder mutation among Puerto Rican Hispanics and to characterize the associated clinical and immunohistochemical phenotype. Genotyping of six polymorphic microsatellite markers internal to (D13S232) and flanking (D13S175, D13S292, D13S787, D13S1243, D13S283) the SGCG gene was performed on four unrelated Puerto Rican patients with LGMD2C. Preserved ambulation to the second decade of life was observed in at least two subjects. Immunostaining of skeletal muscle demonstrated absence of γ-sarcoglycan in all affected subjects. Two markers, D13S232 and D13S292, were highly informative and confirmed that all four families share the haplotype of the mutant allele. Our findings confirm that the E263K missense mutation in the SGCG gene is a founder mutation in Puerto Rican Hispanics. A slowly progressive disease course with prolonged preservation of ambulation can be seen in association with this mutation, providing evidence for phenotypic variability.
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Affiliation(s)
- Samiah A Al-Zaidy
- Center for Gene Therapy and Paul D. Wellstone Muscular Dystrophy Research Center, Nationwide Children's Hospital Columbus, Ohio ; Department of Pediatrics and Neurology, The Ohio State University Columbus, Ohio
| | - Vinod Malik
- Center for Gene Therapy and Paul D. Wellstone Muscular Dystrophy Research Center, Nationwide Children's Hospital Columbus, Ohio
| | - Kelley Kneile
- Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital Columbus, Ohio
| | - Xiomara Q Rosales
- Center for Gene Therapy and Paul D. Wellstone Muscular Dystrophy Research Center, Nationwide Children's Hospital Columbus, Ohio ; Department of Pediatrics and Neurology, The Ohio State University Columbus, Ohio
| | - Ana Maria Gomez
- Center for Gene Therapy and Paul D. Wellstone Muscular Dystrophy Research Center, Nationwide Children's Hospital Columbus, Ohio
| | - Sarah Lewis
- Center for Gene Therapy and Paul D. Wellstone Muscular Dystrophy Research Center, Nationwide Children's Hospital Columbus, Ohio ; Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital Columbus, Ohio
| | - Sayaka Hashimoto
- Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital Columbus, Ohio
| | - Julie Gastier-Foster
- Department of Pathology, Ohio State University and Nationwide Children's Hospital Columbus, Ohio ; Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital Columbus, Ohio
| | - Peter Kang
- Department of Neurology, Boston Children's Hospital and Harvard Medical School Boston, Massachusetts
| | - Basil Darras
- Department of Neurology, Boston Children's Hospital and Harvard Medical School Boston, Massachusetts
| | - Louis Kunkel
- Division of Genetics and Genomics, The Manton Center for Orphan Disease Research, Boston Children's Hospital Boston, Massachusetts
| | - Jose Carlo
- Department of Neurology, School of Medicine, University of Puerto Rico San Juan, Puerto Rico
| | - Zarife Sahenk
- Center for Gene Therapy and Paul D. Wellstone Muscular Dystrophy Research Center, Nationwide Children's Hospital Columbus, Ohio ; Department of Pediatrics and Neurology, The Ohio State University Columbus, Ohio
| | - Steven A Moore
- Department of Pathology, The University of Iowa Carver College of Medicine Iowa City, Iowa
| | - Robert Pyatt
- Department of Pathology, Ohio State University and Nationwide Children's Hospital Columbus, Ohio ; Department of Pathology and Laboratory Medicine, Nationwide Children's Hospital Columbus, Ohio
| | - Jerry R Mendell
- Center for Gene Therapy and Paul D. Wellstone Muscular Dystrophy Research Center, Nationwide Children's Hospital Columbus, Ohio ; Department of Pediatrics and Neurology, The Ohio State University Columbus, Ohio ; Department of Pathology, Ohio State University and Nationwide Children's Hospital Columbus, Ohio
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Durbeej M. Laminin-α2 Chain-Deficient Congenital Muscular Dystrophy: Pathophysiology and Development of Treatment. CURRENT TOPICS IN MEMBRANES 2015; 76:31-60. [PMID: 26610911 DOI: 10.1016/bs.ctm.2015.05.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Laminin-211 is a major constituent of the skeletal muscle basement membrane. It stabilizes skeletal muscle and influences signal transduction events from the myomatrix to the muscle cell. Mutations in the gene encoding the α2 chain of laminin-211 lead to congenital muscular dystrophy type 1A (MDC1A), a life-threatening disease characterized by severe hypotonia, progressive muscle weakness, and joint contractures. Common complications include severely impaired motor ability, respiratory failure, and feeding difficulties. Several adequate animal models for laminin-α2 chain deficiency exist and analyses of different MDC1A mouse models have led to a significant improvement in our understanding of MDC1A pathogenesis. Importantly, the animal models have been indispensable tools for the preclinical development of new therapeutic approaches for laminin-α2 chain deficiency, highlighting a number of important disease driving mechanisms that can be targeted by pharmacological approaches. In this chapter, I will describe laminin-211 and discuss the cellular and molecular pathophysiology of MDC1A as well as progression toward development of treatment.
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Affiliation(s)
- Madeleine Durbeej
- Department of Experimental Medical Science, Lund University, Lund, Sweden.
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Marshall JL, Oh J, Chou E, Lee JA, Holmberg J, Burkin DJ, Crosbie-Watson RH. Sarcospan integration into laminin-binding adhesion complexes that ameliorate muscular dystrophy requires utrophin and α7 integrin. Hum Mol Genet 2014; 24:2011-22. [PMID: 25504048 DOI: 10.1093/hmg/ddu615] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is caused by mutations in the dystrophin gene that result in loss of the dystrophin-glycoprotein complex, a laminin receptor that connects the myofiber to its surrounding extracellular matrix. Utrophin, a dystrophin ortholog that is normally localized to the neuromuscular junction, is naturally upregulated in DMD muscle, which partially compensates for the loss of dystrophin. Transgenic overexpression of utrophin causes broad sarcolemma localization of utrophin, restoration of laminin binding and amelioration of disease in the mdx mouse model of DMD. We previously demonstrated that overexpression of sarcospan, a dystrophin- and utrophin-binding protein, ameliorates mdx muscular dystrophy. Sarcospan boosts levels of utrophin to therapeutic levels at the sarcolemma, where attachment to laminin is restored. However, understanding the compensatory mechanism is complicated by concomitant upregulation of α7β1 integrin, which also binds laminin. Similar to the effects of utrophin, transgenic overexpression of α7 integrin prevents DMD disease in mice and is accompanied by increased abundance of utrophin around the extra-synaptic sarcolemma. In order to investigate the mechanisms underlying sarcospan 'rescue' of muscular dystrophy, we created double-knockout mice to test the contributions of utrophin or α7 integrin. We show that sarcospan-mediated amelioration of muscular dystrophy in DMD mice is dependent on the presence of both utrophin and α7β1 integrin, even when they are individually expressed at therapeutic levels. Furthermore, we found that association of sarcospan into laminin-binding complexes is dependent on utrophin and α7β1 integrin.
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Affiliation(s)
- Jamie L Marshall
- Department of Integrative Biology and Physiology, Center for Duchenne Muscular Dystrophy
| | - Jennifer Oh
- Department of Integrative Biology and Physiology, Center for Duchenne Muscular Dystrophy
| | - Eric Chou
- Department of Integrative Biology and Physiology, Center for Duchenne Muscular Dystrophy
| | - Joy A Lee
- Department of Integrative Biology and Physiology, Center for Duchenne Muscular Dystrophy
| | - Johan Holmberg
- Department of Integrative Biology and Physiology, Center for Duchenne Muscular Dystrophy
| | - Dean J Burkin
- Department of Pharmacology, Center for Molecular Medicine, University of Nevada School of Medicine, Reno, NV 89557, USA
| | - Rachelle H Crosbie-Watson
- Department of Integrative Biology and Physiology, Center for Duchenne Muscular Dystrophy, Molecular Biology Institute, Department of Neurology, University of California, Los Angeles, CA 90095, USA and
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37
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Townsend D. Finding the sweet spot: assembly and glycosylation of the dystrophin-associated glycoprotein complex. Anat Rec (Hoboken) 2014; 297:1694-705. [PMID: 25125182 PMCID: PMC4135523 DOI: 10.1002/ar.22974] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 03/27/2014] [Indexed: 01/12/2023]
Abstract
The dystrophin-associated glycoprotein complex (DGC) is a collection of glycoproteins that are essential for the normal function of striated muscle and many other tissues. Recent genetic studies have implicated the components of this complex in over a dozen forms of muscular dystrophy. Furthermore, disruption of the DGC has been implicated in many forms of acquired disease. This review aims to summarize the current state of knowledge regarding the processing and assembly of dystrophin-associated proteins with a focus primarily on the dystroglycan heterodimer and the sarcoglycan complex. These proteins form the transmembrane portion of the DGC and undergo a complex multi-step processing with proteolytic cleavage, differential assembly, and both N- and O-glycosylation. The enzymes responsible for this processing and a model describing the sequence and subcellular localization of these events are discussed.
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Affiliation(s)
- Dewayne Townsend
- Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota
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Dystrophin complex functions as a scaffold for signalling proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:635-42. [DOI: 10.1016/j.bbamem.2013.08.023] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Revised: 08/22/2013] [Accepted: 08/28/2013] [Indexed: 11/23/2022]
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Johnson EK, Li B, Yoon JH, Flanigan KM, Martin PT, Ervasti J, Montanaro F. Identification of new dystroglycan complexes in skeletal muscle. PLoS One 2013; 8:e73224. [PMID: 23951345 PMCID: PMC3738564 DOI: 10.1371/journal.pone.0073224] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/18/2013] [Indexed: 01/16/2023] Open
Abstract
The dystroglycan complex contains the transmembrane protein β-dystroglycan and its interacting extracellular mucin-like protein α-dystroglycan. In skeletal muscle fibers, the dystroglycan complex plays an important structural role by linking the cytoskeletal protein dystrophin to laminin in the extracellular matrix. Mutations that affect any of the proteins involved in this structural axis lead to myofiber degeneration and are associated with muscular dystrophies and congenital myopathies. Because loss of dystrophin in Duchenne muscular dystrophy (DMD) leads to an almost complete loss of dystroglycan complexes at the myofiber membrane, it is generally assumed that the vast majority of dystroglycan complexes within skeletal muscle fibers interact with dystrophin. The residual dystroglycan present in dystrophin-deficient muscle is thought to be preserved by utrophin, a structural homolog of dystrophin that is up-regulated in dystrophic muscles. However, we found that dystroglycan complexes are still present at the myofiber membrane in the absence of both dystrophin and utrophin. Our data show that only a minority of dystroglycan complexes associate with dystrophin in wild type muscle. Furthermore, we provide evidence for at least three separate pools of dystroglycan complexes within myofibers that differ in composition and are differentially affected by loss of dystrophin. Our findings indicate a more complex role of dystroglycan in muscle than currently recognized and may help explain differences in disease pathology and severity among myopathies linked to mutations in DAPC members.
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Affiliation(s)
- Eric K. Johnson
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
- Ohio State Biochemistry Program, the Ohio State University, Columbus, Ohio, United States of America
| | - Bin Li
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Jung Hae Yoon
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
| | - Kevin M. Flanigan
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
- Department of Pediatrics, the Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - Paul T. Martin
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
- Department of Pediatrics, the Ohio State University College of Medicine, Columbus, Ohio, United States of America
| | - James Ervasti
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Federica Montanaro
- Center for Gene Therapy, the Research Institute at Nationwide Children’s Hospital, and The Ohio State University Biochemistry Program, Columbus, Ohio, United States of America
- Ohio State Biochemistry Program, the Ohio State University, Columbus, Ohio, United States of America
- Department of Pediatrics, the Ohio State University College of Medicine, Columbus, Ohio, United States of America
- * E-mail:
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Marshall JL, Kwok Y, McMorran BJ, Baum LG, Crosbie-Watson RH. The potential of sarcospan in adhesion complex replacement therapeutics for the treatment of muscular dystrophy. FEBS J 2013; 280:4210-29. [PMID: 23601082 DOI: 10.1111/febs.12295] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 04/12/2013] [Indexed: 12/23/2022]
Abstract
Three adhesion complexes span the sarcolemma and facilitate critical connections between the extracellular matrix and the actin cytoskeleton: the dystrophin- and utrophin-glycoprotein complexes and α7β1 integrin. Loss of individual protein components results in a loss of the entire protein complex and muscular dystrophy. Muscular dystrophy is a progressive, lethal wasting disease characterized by repetitive cycles of myofiber degeneration and regeneration. Protein-replacement therapy offers a promising approach for the treatment of muscular dystrophy. Recently, we demonstrated that sarcospan facilitates protein-protein interactions amongst the adhesion complexes and is an important potential therapeutic target. Here, we review current protein-replacement strategies, discuss the potential benefits of sarcospan expression, and identify important experiments that must be addressed for sarcospan to move to the clinic.
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Affiliation(s)
- Jamie L Marshall
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA
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Feng HZ, Wang Q, Reiter RS, Lin JLC, Lin JJC, Jin JP. Localization and function of Xinα in mouse skeletal muscle. Am J Physiol Cell Physiol 2013; 304:C1002-12. [PMID: 23485711 DOI: 10.1152/ajpcell.00005.2013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The Xin repeat-containing proteins were originally found in the intercalated discs of cardiac muscle with implicated roles in cardiac development and function. A pair of paralogous genes, Xinα (Xirp1) and Xinβ (Xirp2), is present in mammals. Ablation of the mouse Xinα (mXinα) did not affect heart development but caused late-onset adulthood cardiac hypertrophy and cardiomyopathy with conductive defects. Both mXinα and mXinβ are also found in the myotendinous junction (MTJ) of skeletal muscle. Here we investigated the structural and functional significance of mXinα in skeletal muscle. In addition to MTJ and the contact sites between muscle and perimysium, mXinα but not mXinβ was found in the blood vessel walls, whereas both proteins were absent in neuromuscular junctions and nerve fascicles. Coimmunoprecipitation suggested association of mXinα with talin, vinculin, and filamin, but not β-catenin, in adult skeletal muscle, consistent with our previous report of colocalization of mXinα with vinculin. Loss of mXinα in mXinα-null mice had subtle effects on the MTJ structure and the levels of several MTJ components. Diaphragm muscle of mXinα-null mice showed hypertrophy. Compared with wild-type controls, mouse extensor digitorum longus (EDL) muscle lacking mXinα exhibited no overt change in contractile and relaxation velocities or maximum force development but better tolerance to fatigue. Loaded fatigue contractions generated stretch injury in wild-type EDL muscle as indicated by a fragmentation of troponin T. This effect was blunted in mXinα-null EDL muscle. The results suggest that mXinα play a role in MTJ conductance of contractile and stretching forces.
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Affiliation(s)
- Han-Zhong Feng
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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Marshall JL, Crosbie-Watson RH. Sarcospan: a small protein with large potential for Duchenne muscular dystrophy. Skelet Muscle 2013; 3:1. [PMID: 23282144 PMCID: PMC3599653 DOI: 10.1186/2044-5040-3-1] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2012] [Accepted: 11/27/2012] [Indexed: 01/09/2023] Open
Abstract
Purification of the proteins associated with dystrophin, the gene product responsible for Duchenne muscular dystrophy, led to the discovery of the dystrophin-glycoprotein complex. Sarcospan, a 25-kDa transmembrane protein, was the last component to be identified and its function in skeletal muscle has been elusive. This review will focus on progress over the last decade revealing that sarcospan is an important regulator of muscle cell adhesion, strength, and regeneration. Investigations using several transgenic mouse models demonstrate that overexpression of sarcospan in the mouse model for Duchenne muscular dystrophy ameliorates pathology and restores muscle cell binding to laminin. Sarcospan improves cell surface expression of the dystrophin- and utrophin-glycoprotein complexes as well as α7β1 integrin, which are the three major laminin-binding complexes in muscle. Utrophin and α7β1 integrin compensate for the loss of dystrophin and the finding that sarcospan increases their abundance at the extra-synaptic sarcolemma supports the use of sarcospan as a therapeutic target. Newly discovered phenotypes in sarcospan-deficient mice, including a reduction in specific force output and increased drop in force in the diaphragm muscle, result from decreased utrophin and dystrophin expression and further reveal sarcospan’s role in determining abundance of these complexes. Dystrophin protein levels and the specific force output of the diaphragm muscle are further reduced upon genetic removal of α7 integrin (Itga7) in SSPN-deficient mice, demonstrating that interactions between integrin and sarcospan are critical for maintenance of the dystrophin-glycoprotein complex and force production of the diaphragm muscle. Sarcospan is a major regulator of Akt signaling pathways and sarcospan-deficiency significantly impairs muscle regeneration, a process that is dependent on Akt activation. Intriguingly, sarcospan regulates glycosylation of a specific subpopulation of α-dystroglycan, the laminin-binding receptor associated with dystrophin and utrophin, localized to the neuromuscular junction. Understanding the basic mechanisms responsible for assembly and trafficking of the dystrophin- and utrophin-glycoprotein complexes to the cell surface is lacking and recent studies suggest that sarcospan plays a role in these essential processes.
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Affiliation(s)
- Jamie L Marshall
- Department of Integrative Biology and Physiology, University of California Los Angeles, 610 Charles E, Young Drive East, Terasaki Life Sciences Building, Los Angeles, CA, 90095, USA.
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Abstract
A chain is no stronger than its weakest link is an old idiom that holds true for muscle biology. As the name implies, skeletal muscle's main function is to move the bones. However, for a muscle to transmit force and withstand the stress that contractions give rise to, it relies on a chain of proteins attaching the cytoskeleton of the muscle fiber to the surrounding extracellular matrix. The importance of this attachment is illustrated by a large number of muscular dystrophies caused by interruption of the cytoskeletal-extracellular matrix interaction. One of the major components of the extracellular matrix is laminin, a heterotrimeric glycoprotein and a major constituent of the basement membrane. It has become increasingly apparent that laminins are involved in a multitude of biological functions, including cell adhesion, differentiation, proliferation, migration and survival. This review will focus on the importance of laminin-211 for normal skeletal muscle function.
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Affiliation(s)
- Johan Holmberg
- Muscle Biology Unit, Department of Experimental Medical Science, Lund University, Lund, Sweden.
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Marshall JL, Holmberg J, Chou E, Ocampo AC, Oh J, Lee J, Peter AK, Martin PT, Crosbie-Watson RH. Sarcospan-dependent Akt activation is required for utrophin expression and muscle regeneration. ACTA ACUST UNITED AC 2012; 197:1009-27. [PMID: 22734004 PMCID: PMC3384411 DOI: 10.1083/jcb.201110032] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Utrophin is normally confined to the neuromuscular junction (NMJ) in adult muscle and partially compensates for the loss of dystrophin in mdx mice. We show that Akt signaling and utrophin levels were diminished in sarcospan (SSPN)-deficient muscle. By creating several transgenic and knockout mice, we demonstrate that SSPN regulates Akt signaling to control utrophin expression. SSPN determined α-dystroglycan (α-DG) glycosylation by affecting levels of the NMJ-specific glycosyltransferase Galgt2. After cardiotoxin (CTX) injury, regenerating myofibers express utrophin and Galgt2-modified α-DG around the sarcolemma. SSPN-null mice displayed delayed differentiation after CTX injury caused by loss of utrophin and Akt signaling. Treatment of SSPN-null mice with viral Akt increased utrophin and restored muscle repair after injury, revealing an important role for the SSPN-Akt-utrophin signaling axis in regeneration. SSPN improved cell surface expression of utrophin by increasing transportation of utrophin and DG from endoplasmic reticulum/Golgi membranes. Our experiments reveal functions of utrophin in regeneration and new pathways that regulate utrophin expression at the cell surface.
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Affiliation(s)
- Jamie L Marshall
- Department of Integrative Biology and Physiology and 2 Molecular Biology Institute, University of California-Los Angeles, Los Angeles, CA 90095, USA
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Marshall JL, Chou E, Oh J, Kwok A, Burkin DJ, Crosbie-Watson RH. Dystrophin and utrophin expression require sarcospan: loss of α7 integrin exacerbates a newly discovered muscle phenotype in sarcospan-null mice. Hum Mol Genet 2012; 21:4378-93. [PMID: 22798625 DOI: 10.1093/hmg/dds271] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Sarcospan (SSPN) is a core component of the major adhesion complexes in skeletal muscle, the dystrophin- and utrophin (Utr)-glycoprotein complexes (DGC and UGC). We performed a rigorous analysis of SSPN-null mice and discovered that loss of SSPN decreased DGC and UGC abundance, leading to impaired laminin-binding activity and susceptibility to eccentric contraction-induced injury in skeletal muscle. We show that loss of SSPN increased levels of α7β1 integrin. To genetically test whether integrin compensates for the loss of DGC and UGC function in SSPN-nulls, we generated mice lacking both SSPN and α7 integrin (DKO, double knockout). Muscle regeneration, sarcolemma integrity and fibrosis were exacerbated in DKO mice and were remarkably similar to muscle from Duchenne muscular dystrophy (DMD) patients, suggesting that secondary loss of integrin contributes significantly to pathogenesis. Expression of the DGC and UGC, laminin binding and Akt signaling were negatively impacted in DKO muscle, resulting in severely diminished specific force properties. We demonstrate that SSPN is a necessary component of dystrophin and Utr function and that SSPN modulation of integrin signaling is required for extracellular matrix attachment and muscle force development.
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Affiliation(s)
- Jamie L Marshall
- Department of Integrative Biology and Physiology, University of California, Los Angeles, CA 90095, USA
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Abstract
Costameres are sub-membranous, Z-line associated structures found in striated muscle. They have been shown to have important roles in transmission of force from the sarcomere to the sarcolemma and extracellular matrix, maintaining mechanical integrity of the sarcolemma, and orchestrating mechanically related signaling. The costamere is akin to the more well-known focal adhesion complex present in most cells. The Z-line is a critical structural anchor for the sarcomere, but it is also a hot-spot for muscle cell signaling. Therefore functionally, the costamere represents a two-way signaling highway tethered between the Z-line and the extracellular matrix, relaying mechanical stress signals from outside the cell to intracellular signaling networks. In this role it can modulate myofibril growth and contraction. The major force generated by sarcomeres is transduced in the lateral direction from the sarcomere to the extracellular matrix through the costamere. Two major protein complexes have been described at the costamere: the dystrophin-glycoprotein complex and the integrin-vinculin-talin complex. The importance of these two protein complexes in striated muscle function has between demonstrated both in human disease and mouse models. Members of the dystrophin glycoprotein complex and integrins have both been reported to interact directly with filamin-C, thus linking costameric complexes with those present at the Z-line. Moreover, studies from our labs and others have shown that the Z-line proteins belonging to the PDZ-LIM domain protein family, enigma homolog (ENH) and cypher, may directly or indirectly be involved in this linkage. The following review will focus on the protein components of this linkage, their function in force transmission, and how the dysfunction or loss of proteins within these complexes contributes to muscular disease.
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Solares-Pérez A, Alvarez R, Crosbie RH, Vega-Moreno J, Medina-Monares J, Estrada FJ, Ortega A, Coral-Vazquez R. Altered calcium pump and secondary deficiency of gamma-sarcoglycan and microspan in sarcoplasmic reticulum membranes isolated from delta-sarcoglycan knockout mice. Cell Calcium 2010; 48:28-36. [PMID: 20638123 DOI: 10.1016/j.ceca.2010.06.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2010] [Revised: 06/17/2010] [Accepted: 06/21/2010] [Indexed: 11/25/2022]
Abstract
Sarcoglycans (SGs) and sarcospan (SSPN) are transmembrane proteins of the dystrophin-glycoprotein complex. Mutations in the genes encoding SGs cause many inherited forms of muscular dystrophy. In this study, using purified membranes of wild-type (WT) and delta-SG knockout (KO) mice, we found the specific localization of the SG-SSPN isoforms in transverse tubules (TT) and sarcoplasmic reticulum (SR) membranes. Immunoblotting revealed that the absence of delta-SG isoforms in TT and SR results in a secondary deficiency of gamma-SG and microSPN. Our results showed augmented ATP hydrolytic activity, ATP-dependent calcium uptake and passive calcium efflux, probably through SERCA1 in KO compared to WT mice. Furthermore, we found a conformational change in SERCA1 isolated from KO muscle as demonstrated by calorimetric analysis. Following these alterations with mechanical properties, we found an increase in force in KO muscle with the same rate of fatigue but with a decreased fatigue recovery compared to WT. Together our observations suggest, for the first time, that the delta-SG isoforms may stabilize the expression of gamma-SG and microSPN in the TT and SR membranes and that this possible complex may play a role in the maintenance of a stable level of resting cytosolic calcium concentration in skeletal muscle.
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Affiliation(s)
- Alhondra Solares-Pérez
- Sección de Posgrado, Escuela Superior de Medicina, Instituto Politécnico Nacional, México, DF., México
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Several dystrophin-glycoprotein complex members are present in crude surface membranes but they are sodium dodecyl sulphate invisible in KCl-washed microsomes from mdx mouse muscle. Cell Mol Biol Lett 2009; 15:134-52. [PMID: 19997781 PMCID: PMC6276006 DOI: 10.2478/s11658-009-0039-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 11/27/2009] [Indexed: 11/20/2022] Open
Abstract
The dystrophin-glycoprotein complex (DGC) is a large trans-sarcolemmal complex that provides a linkage between the subsarcolemmal cytoskeleton and the extracellular matrix. In skeletal muscle, it consists of the dystroglycan, sarcoglycan and cytoplasmic complexes, with dystrophin forming the core protein. The DGC has been described as being absent or greatly reduced in dystrophin-deficient muscles, and this lack is considered to be involved in the dystrophic phenotype. Such a decrease in the DGC content was observed in dystrophin-deficient muscle from humans with muscular dystrophy and in mice with X-linked muscular dystrophy (mdx mice). These deficits were observed in total muscle homogenates and in partially membrane-purified muscle fractions, the so-called KCl-washed microsomes. Here, we report that most of the proteins of the DGC are actually present at normal levels in the mdx mouse muscle plasma membrane. The proteins are detected in dystrophic animal muscles when the immunoblot assay is performed with crude surface membrane fractions instead of the usually employed KCl-washed microsomes. We propose that these proteins form SDS-insoluble membrane complexes when dystrophin is absent.
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Xu R, DeVries S, Camboni M, Martin PT. Overexpression of Galgt2 reduces dystrophic pathology in the skeletal muscles of alpha sarcoglycan-deficient mice. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 175:235-47. [PMID: 19498002 DOI: 10.2353/ajpath.2009.080967] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Recent studies have shown that a number of genes that are not mutated in various forms of muscular dystrophy may serve as surrogates to protect skeletal myofibers from injury. One such gene is Galgt2, which is also called cytotoxic T cell GalNAc transferase in mice. In this study, we show that Galgt2 overexpression reduces the development of dystrophic pathology in the skeletal muscles of mice lacking alpha sarcoglycan (Sgca), a mouse model for limb girdle muscular dystrophy 2D. Galgt2 transgenic Sgca(-/-) mice showed reduced levels of myofiber damage, as evidenced by i) normal levels of serum creatine kinase activity, ii) a lack of Evans blue dye uptake into myofibers, iii) normal levels of mouse locomotor activity, and iv) near normal percentages of myofibers with centrally located nuclei. In addition, the overexpression of Galgt2 in the early postnatal period using an adeno-associated virus gene therapy vector protected Sgca(-/-) myofibers from damage, as observed using histopathology measurements. Galgt2 transgenic Sgca(-/-) mice also had increased levels of glycosylation of alpha dystroglycan with the CT carbohydrate, but showed no up-regulation of beta, gamma, delta, or epsilon sarcoglycan. These data, coupled with results from our previous studies, show that Galgt2 has therapeutic effects in three distinct forms of muscular dystrophy and may, therefore, have a broad spectrum of therapeutic potential for the treatment of various myopathies.
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Affiliation(s)
- Rui Xu
- the Departments of Pediatrics, Center for Gene Therapy, Physiology and Cell Biology, Ohio State University College of Medicine, Columbus, Ohio 43205, USA
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