DOCSLIB.ORG

Dystrobrevin Alpha Gene Is a Direct Target of the Vitamin D Receptor in Muscle

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dystrobrevin Alpha Gene Is a Direct Target of the Vitamin D Receptor in Muscle 64 3 Journal of Molecular M K Tsoumpra et al. Upregulation of dystrobrevin by 64:3 195–208 Endocrinology calcitriol RESEARCH Dystrobrevin alpha gene is a direct target of the vitamin D receptor in muscle Maria K Tsoumpra1, Shun Sawatsubashi2, Michihiro Imamura1, Seiji Fukumoto2, Shin’ichi Takeda1, Toshio Matsumoto2 and Yoshitsugu Aoki1 1Department of Molecular Therapy, National Institute of Neuroscience, National Centre of Neurology and Psychiatry, Tokyo, Japan 2Fujii Memorial Institute of Medical Sciences, Tokushima University, Tokushima, Japan Correspondence should be addressed to S Fukumoto: [email protected] Abstract The biologically active metabolite of vitamin D, 1,25-dihydroxyvitamin D3 (VD3), exerts its Key Words tissue-specific actions through binding to its intracellular vitamin D receptor (VDR) which f vitamin D functions as a heterodimer with retinoid X receptor (RXR) to recognize vitamin D response f muscle elements (VDRE) and activate target genes. Upregulation of VDR in murine skeletal muscle f gene regulation cells occurs concomitantly with transcriptional regulation of key myogenic factors upon f receptor binding VD3 administration, reinforcing the notion that VD3 exerts beneficial effects on muscle. Herein we elucidated the regulatory role of VD3/VDR axis on the expression of dystrobrevin alpha (DTNA), a member of dystrophin-associated protein complex (DAPC). In C2C12 cells, Dtna and VDR gene and protein expression were upregulated by 1–50 nM of VD3 during all stages of myogenic differentiation. In the dystrophic-derived H2K-mdx52 cells, upregulation of DTNA by VD3 occurred upon co-transfection of VDR and RXR expression vectors. Silencing of MyoD1, an E-box binding myogenic transcription factor, did not alter the VD3-mediated Dtna induction, but Vdr silencing abolished this effect. We also demonstrated that VD3 administration enhanced the muscle-specific Dtna promoter activity in presence of VDR/RXR only. Through site-directed mutagenesis and chromatin immunoprecipitation assays, we have validated a VDRE site in Dtna promoter in myogenic cells. We have thus proved that the positive regulation of Dtna by VD3 observed during in vitro murine myogenic differentiation is VDR mediated and specific. The current study reveals a novel mechanism of VDR-mediated regulation for Dtna, which may be positively explored in Journal of Molecular treatments aiming to stabilize the DAPC in musculoskeletal diseases. Endocrinology (2020) 64, 195–208 Introduction The biologically active metabolite of vitamin D, genomic sequences called vitamin D response elements 1,25-dihydroxyvitamin D3 (VD3), is a calcium regulating (VDREs) to influence gene transcription (Umesono et al. hormone that exerts its tissue-specific biological actions 1991, Kliewer et al. 1992). through binding to its intracellular vitamin D receptor A link of murine VDR implication in transcriptional (VDR) (Kato 2000). Once VD3 binds to VDR, dimerization downregulation of myogenic factors during skeletal with one of the three retinoid X receptors (RXRα, muscle development has been initially reported by RXRβ, and RXRγ) occurs, and the VDR-RXR dimer can our team (Endo et al. 2003), suggesting that VDR can translocate to the nucleus where it recognizes specific partially mediate the course of myogenic differentiation. https://jme.bioscientifica.com © 2020 Society for Endocrinology https://doi.org/10.1530/JME-19-0229 Published by Bioscientifica Ltd. Printed in Great Britain Downloaded from Bioscientifica.com at 09/27/2021 07:41:33PM via free access -19-0229 Journal of Molecular M K Tsoumpra et al. Upregulation of dystrobrevin by 64:3 196 Endocrinology calcitriol In vitro studies using murine C2C12 muscle cells backed motif interaction (Sadoulet-Puccio et al. 1997), whereas its up the existence of a dose-dependent anti-proliferative N-terminal domain directly interacts with sarcoglycan and effect of VD3 that increased myotube size, which was sarcospan subcomplex (Yoshida et al. 2000). Absence of C accompanied by downregulation of myostatin, a negative terminal dystrophin binding motif does not prevent DTNA regulator of muscle mass (Garcia et al. 2011, Girgis et al. binding to the DAPC, indicating that an unidentified 2014a). The same group demonstrated the presence of an anchoring site is present in the N-terminal region of Dtna autoregulatory vitamin D-endocrine system in skeletal (Crawford et al. 2000). In addition, DTNA colocalizes at muscle (Girgis et al. 2014a), although the VDR muscle- the sarcolemma with dysbindin (Benson et al. 2001), at the specific expression was reported to be much lower than neuromuscular junction with syncoilin (Newey et al. 2001), that measured in other specific tissues such as intestine and binds desmuslin (Mizuno et al. 2001) and syntrophins (Bouillon et al. 2014). VDR expression was found elevated (Ahn et al. 1996). in tibialis anterior muscle obtained from mice treated daily The murine Dtna gene is located on chromosome 18 with VD3 via i.m. injection on days 4–7 post-mechanical consists of 24 coding exons and is subjected to extensive injury, which suggests the presence of local synthesis and alternative splicing that produces tissue-specific isoforms regulation of VD3 metabolism during muscle regeneration (Blake et al. 1996, Ambrose et al. 1997). Overall, three (Srikuea & Hirunsai 2016). Furthermore, Vdr ablation main isoforms have been described in mouse (Dtna1, resulted in reduced grip strength and dysregulation of Dtna2, and Dtna3); however, slight rearrangements myogenic factors in mice mimicking atrophic phenotype within the internal exon usage in individual isoforms changes mainly attributed to reduced expression of genes generate multiple transcript variants encoding for the associated with calcium handling channels (Girgis et al. same isoform, further adding to the complexity of Dtna 2015). However, in the global VDRKO model, it is hard genomic region (Böhm et al. 2009). The largest isoform, to discriminate effects of direct VDR deletion in muscle DTNA1, is an 87 kDa protein (77–84 kDa in mouse) and those caused by mineral metabolism changes such originally discovered in postsynaptic membranes of as hypocalcaemia. Modifications in intracellular calcium Torpedo electric organ (Wagner et al. 1993), is enriched at levels by VD3 can be unavoidable even in conditional the neuromuscular junction, and possesses two syntrophin VDR null mice such as the myocyte-specific VDR knockout binding domains, a dystrophin/utrophin binding site mice described recently (Girgis et al. 2019) and interfere as well as a unique COOH-terminal containing three with muscle relaxation (Berchtold et al. 2000) or tamper potential tyrosine phosphorylation sites (Peters et al. with myoblast nature due to the disrupted regulation of 1998, Pawlikowski & Maimone 2009, Gingras et al. 2016). phosphate metabolism (Bellido & Boland 1987). It is thus DTNA2 exists in two alternative isoforms (DTNA2A and highly probable that the so-called VDR-muscle generated DTNA2B), possesses a unique C terminal domain, localizes effects observed previously are mediated by tissues other in the sarcolemma and the neuromuscular synapse, and than muscle or even by non-genomic mechanisms related binds only dystrophin (Enigk & Maimone 1999). The to the disrupted calcium uptake and thus are not a direct smallest DTNA3 isoform (42 kDa) contains two structural effect of muscle Vdr ablation per se. motifs belonging to the dystrophin-family proteins, lacks Dystrobrevin alpha (DTNA) is an essential structural the syntrophin binding domain (Ponting et al. 1996), component of the dystrophin associated protein complex and it is exclusively found in cardiac and skeletal muscle (DAPC). The DAPC maintains sarcolemmal stability during (Nawrotzki et al. 1998). The exact function of DTNA is muscle contraction and through its binding domains and unknown, but it has been speculated that, apart from its associated channel proteins aids signal transduction toward supportive role, it may aid in the transmission of DAPC muscle fibers to mainly protect them against damage from signaling (Newey et al. 2000). stress (Blake et al. 2002, Ehmsen et al. 2002). The core The identification of VDR in muscle tissue hints at the member of DAPC, dystrophin, serves as an anchor between presence of a direct pathway for VD3 to impact on skeletal the actin cytoskeleton and the connective tissue (Ervasti muscle function that is yet to be discovered. Herein, we & Campbell 1991, Petrof et al. 1993, Ohlendieck 1996). have shown that VD3 administration positively regulates Mutation on dystrophin gene leads to the X chromosome- Dtna gene and protein expression in C2C12 myogenic linked, progressive, fatal degenerative muscle disorder cells as well as in H2K-mdx52 that are immortalized cells called Duchenne muscular dystrophy (Hoffman et al. derived from the humanized mdx52 mouse model (Araki 1987). The C terminus of DTNA is strongly associated with et al. 1997). DTNA upregulation was strictly associated the C terminus of dystrophin through a specific coiled-coil with VDR expression levels in both healthy and https://jme.bioscientifica.com © 2020 Society for Endocrinology https://doi.org/10.1530/JME-19-0229 Published by Bioscientifica Ltd. Printed in Great Britain Downloaded from Bioscientifica.com at 09/27/2021 07:41:33PM via free access Journal of Molecular M K Tsoumpra et al. Upregulation of dystrobrevin by 64:3 197 Endocrinology calcitriol dystrophic myotubes. We have also identified a functional template for RT using
Load more

Recommended publications
  • Development of a High-Throughput Screen to Identify Small Molecule Enhancers of Sarcospan for the Treatment of Duchenne Muscular Dystrophy
    UCLA UCLA Previously Published Works Title Development of a high-throughput screen to identify small molecule enhancers of sarcospan for the treatment of Duchenne muscular dystrophy. Permalink https://escholarship.org/uc/item/85z6k8t7 Journal Skeletal muscle, 9(1) ISSN 2044-5040 Authors Shu, Cynthia Kaxon-Rupp, Ariana N Collado, Judd R et al. Publication Date 2019-12-12 DOI 10.1186/s13395-019-0218-x Peer reviewed eScholarship.org Powered by the California Digital Library University of California Shu et al. Skeletal Muscle (2019) 9:32 https://doi.org/10.1186/s13395-019-0218-x RESEARCH Open Access Development of a high-throughput screen to identify small molecule enhancers of sarcospan for the treatment of Duchenne muscular dystrophy Cynthia Shu1,2,3, Ariana N. Kaxon-Rupp2, Judd R. Collado2, Robert Damoiseaux4,5 and Rachelle H. Crosbie1,2,3,6* 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.
    [Show full text]
  • Dystrophin Complex Functions As a Scaffold for Signalling Proteins☆
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Elsevier - Publisher Connector Biochimica et Biophysica Acta 1838 (2014) 635–642 Contents lists available at ScienceDirect Biochimica et Biophysica Acta journal homepage: www.elsevier.com/locate/bbamem Review Dystrophin complex functions as a scaffold for signalling proteins☆ Bruno Constantin IPBC, CNRS/Université de Poitiers, FRE 3511, 1 rue Georges Bonnet, PBS, 86022 Poitiers, France article info abstract Article history: Dystrophin is a 427 kDa sub-membrane cytoskeletal protein, associated with the inner surface membrane and Received 27 May 2013 incorporated in a large macromolecular complex of proteins, the dystrophin-associated protein complex Received in revised form 22 August 2013 (DAPC). In addition to dystrophin the DAPC is composed of dystroglycans, sarcoglycans, sarcospan, dystrobrevins Accepted 28 August 2013 and syntrophin. This complex is thought to play a structural role in ensuring membrane stability and force trans- Available online 7 September 2013 duction during muscle contraction. The multiple binding sites and domains present in the DAPC confer the scaf- fold of various signalling and channel proteins, which may implicate the DAPC in regulation of signalling Keywords: Dystrophin-associated protein complex (DAPC) processes. The DAPC is thought for instance to anchor a variety of signalling molecules near their sites of action. syntrophin The dystroglycan complex may participate in the transduction of extracellular-mediated signals to the muscle Sodium channel cytoskeleton, and β-dystroglycan was shown to be involved in MAPK and Rac1 small GTPase signalling. More TRPC channel generally, dystroglycan is view as a cell surface receptor for extracellular matrix proteins.
    [Show full text]
  • Reviewreview Duchenne Muscular Dystrophy and Dystrophin: Pathogenesis and Opportunities for Treatment Third in Molecular Medicine Review Series Kristen J
    reviewreview Duchenne muscular dystrophy and dystrophin: pathogenesis and opportunities for treatment Third in Molecular Medicine Review Series Kristen J. Nowak† & Kay E. Davies+ MRC Functional Genetics Unit, University of Oxford, UK Duchenne muscular dystrophy (DMD) is caused by mutations in protein. Becker muscular dystrophy (BMD; OMIM 300376)—a the gene that encodes the 427-kDa cytoskeletal protein dys- much milder form of the disease—is caused by a reduction in the trophin. Increased knowledge of the function of dystrophin and amount, or alteration in the size, of the dystrophin protein. The its role in muscle has led to a greater understanding of the high incidence of sporadic cases of DMD (1 in 10,000 sperm or pathogenesis of DMD. This, together with advances in the eggs) means that genetic screening will never eliminate this dis- genetic toolkit of the molecular biologist, are leading to many ease, so an effective therapy is highly desirable. This review sum- different approaches to treatment. Gene therapy can be marizes our understanding of the disease and the strategies that are achieved using plasmids or viruses, mutations can be corrected being developed for an effective treatment (Fig 1). using chimaeraplasts and short DNA fragments, exon skipping of mutations can be induced using oligonucleotides and Pathogenesis readthrough of nonsense mutations can be achieved using Dystrophin has a major structural role in muscle as it links the aminoglycoside antibiotics. Blocking the proteasome degrada- internal cytoskeleton to the extracellular matrix. The amino-terminus tion pathway can stabilize any truncated dystrophin protein, of dystrophin binds to F-actin and the carboxyl terminus to the and upregulation of other proteins can also prevent the dys- dystrophin-associated protein complex (DAPC) at the sarcolemma trophic process.
    [Show full text]
  • Governs the Making of Photocopies Or Other Reproductions of Copyrighted Materials
    Warning Concerning Copyright Restrictions The Copyright Law of the United States (Title 17, United States Code) governs the making of photocopies or other reproductions of copyrighted materials. Under certain conditions specified in the law, libraries and archives are authorized to furnish a photocopy or other reproduction. One of these specified conditions is that the photocopy or reproduction is not to be used for any purpose other than private study, scholarship, or research. If electronic transmission of reserve material is used for purposes in excess of what constitutes "fair use," that user may be liable for copyright infringement. University of Nevada, Reno The Role of Utrophin, Sarcospan, and Glycosyltransferase Activity in the Pathogenesis of Duchenne Muscular Dystrophy and a Representative Case Study A thesis submitted in partial fulfillment of the requirements for the degree of Bachelor of Science in Biochemistry & Molecular Biology by Susan T. Alaei Josh Baker, Ph.D., Thesis Advisor May, 2013 UNIVERSITY OF NEVADA THE HONORS PROGRAM RENO We recommend that the thesis prepared under our supervision by Susan T. Alaei entitled The Role of Utrophin, Sarcospan, and Glycosyltransferase Activity in the Pathogenesis of Duchenne Muscular Dystrophy and a Representative Case Study be accepted in partial fulfillment of the requirements for the degree of Bachelor of Science in Biochemistry & Molecular Biology ______________________________________________ Josh Baker, Ph.D., Thesis Advisor ______________________________________________ Tamara Valentine, Ph.D., Director, Honors Program May 2013 i Abstract Duchenne Muscular Dystrophy is a degenerative muscle disease that is characterized by the breakdown of skeletal muscle as a result of membrane instability. A mutation in the dystrophin gene, one of the largest gene in the human genome, results in a complete lack of dystrophin in the membrane of skeletal muscle cells.
    [Show full text]
  • Sarcospan-Dependent Akt Activation Is Required for Utrophin Expression and Muscle Regeneration
    JCB: Article Sarcospan-dependent Akt activation is required for utrophin expression and muscle regeneration Jamie L. Marshall,1 Johan Holmberg,1 Eric Chou,1 Amber C. Ocampo,1 Jennifer Oh,1 Joy Lee,1 Angela K. Peter,1 Paul T. Martin,3,4 and Rachelle H. Crosbie-Watson1,2 1Department of Integrative Biology and Physiology and 2Molecular Biology Institute, University of California, Los Angeles, Los Angeles, CA 90095 3Center for Gene Therapy, The Research Institute, Nationwide Children’s Hospital, and 4Department of Pediatrics, Ohio State University College of Medicine and College of Public Health, Columbus, OH 43205 trophin is normally confined to the neuromus- sarcolemma. SSPN-null mice displayed delayed differen- cular junction (NMJ) in adult muscle and par- tiation after CTX injury caused by loss of utrophin and Akt U tially compensates for the loss of dystrophin in signaling. Treatment of SSPN-null mice with viral Akt mdx mice. We show that Akt signaling and utrophin increased utrophin and restored muscle repair after in- levels were diminished in sarcospan (SSPN)-deficient jury, revealing an important role for the SSPN-Akt-utro- muscle. By creating several transgenic and knockout phin signaling axis in regeneration. SSPN improved cell mice, we demonstrate that SSPN regulates Akt signal- surface expression of utrophin by increasing transportation ing to control utrophin expression. SSPN determined of utrophin and DG from endoplasmic reticulum/Golgi -dystroglycan (-DG) glycosylation by affecting levels membranes. Our experiments reveal functions of utro- of the NMJ-specific glycosyltransferase Galgt2. After phin in regeneration and new pathways that regulate cardiotoxin (CTX) injury, regenerating myofibers ex- utrophin expression at the cell surface.
    [Show full text]
  • Muscle Diseases: the Muscular Dystrophies
    ANRV295-PM02-04 ARI 13 December 2006 2:57 Muscle Diseases: The Muscular Dystrophies Elizabeth M. McNally and Peter Pytel Department of Medicine, Section of Cardiology, University of Chicago, Chicago, Illinois 60637; email: [email protected] Department of Pathology, University of Chicago, Chicago, Illinois 60637; email: [email protected] Annu. Rev. Pathol. Mech. Dis. 2007. Key Words 2:87–109 myotonia, sarcopenia, muscle regeneration, dystrophin, lamin A/C, The Annual Review of Pathology: Mechanisms of Disease is online at nucleotide repeat expansion pathmechdis.annualreviews.org Abstract by Drexel University on 01/13/13. For personal use only. This article’s doi: 10.1146/annurev.pathol.2.010506.091936 Dystrophic muscle disease can occur at any age. Early- or childhood- onset muscular dystrophies may be associated with profound loss Copyright c 2007 by Annual Reviews. All rights reserved of muscle function, affecting ambulation, posture, and cardiac and respiratory function. Late-onset muscular dystrophies or myopathies 1553-4006/07/0228-0087$20.00 Annu. Rev. Pathol. Mech. Dis. 2007.2:87-109. Downloaded from www.annualreviews.org may be mild and associated with slight weakness and an inability to increase muscle mass. The phenotype of muscular dystrophy is an endpoint that arises from a diverse set of genetic pathways. Genes associated with muscular dystrophies encode proteins of the plasma membrane and extracellular matrix, and the sarcomere and Z band, as well as nuclear membrane components. Because muscle has such distinctive structural and regenerative properties, many of the genes implicated in these disorders target pathways unique to muscle or more highly expressed in muscle.
    [Show full text]
  • The Congenital and Limb-Girdle Muscular Dystrophies Sharpening the Focus, Blurring the Boundaries
    NEUROLOGICAL REVIEW SECTION EDITOR: DAVID E. PLEASURE, MD The Congenital and Limb-Girdle Muscular Dystrophies Sharpening the Focus, Blurring the Boundaries Janbernd Kirschner, MD; Carsten G. Bo¨nnemann, MD uring the past decade, outstanding progress in the areas of congenital and limb- girdle muscular dystrophies has led to staggering clinical and genetic complexity. With the identification of an increasing number of genetic defects, individual enti- ties have come into sharper focus and new pathogenic mechanisms for muscular dys- Dtrophies, like defects of posttranslational O-linked glycosylation, have been discovered. At the same time, this progress blurs the traditional boundaries between the categories of congenital and limb- girdle muscular dystrophies, as well as between limb-girdle muscular dystrophies and other clini- cal entities, as mutations in genes such as fukutin-related protein, dysferlin, caveolin-3 and lamin A/C can cause a striking variety of phenotypes. We reviewed the different groups of proteins cur- rently recognized as being involved in congenital and limb-girdle muscular dystrophies, associ- ated them with the clinical phenotypes, and determined some clinical and molecular clues that are helpful in the diagnostic approach to these patients. Arch Neurol. 2004;61:189-199 Muscular dystrophies were first recog- phy. The age at onset may range from early nized as a disease entity with the detailed childhood to late adulthood.5 description of the clinical presentation of During the past decade, exciting Duchenne muscular dystrophy in 1852 and progress has been made in the field of CMD thereafter.1,2 About 50 years later, Batten3 and LGMD, emphasizing differences as published the first case reports of a con- well as commonalities between them.
    [Show full text]
  • Muscular Dystrophies Involving the Dystrophin–Glycoprotein Complex: an Overview of Current Mouse Models Madeleine Durbeej and Kevin P Campbell*
    349 Muscular dystrophies involving the dystrophin–glycoprotein complex: an overview of current mouse models Madeleine Durbeej and Kevin P Campbell* The dystrophin–glycoprotein complex (DGC) is a multisubunit dystrophies are a heterogeneous group of disorders. complex that connects the cytoskeleton of a muscle fiber to its Patients with DMD have a childhood onset phenotype and surrounding extracellular matrix. Mutations in the DGC disrupt die by their early twenties as a result of either respiratory the complex and lead to muscular dystrophy. There are a few or cardiac failure, whereas patients with BMD have naturally occurring animal models of DGC-associated moderate weakness in adulthood and may have normal life muscular dystrophy (e.g. the dystrophin-deficient mdx mouse, spans. The limb–girdle muscular dystrophies have a dystrophic golden retriever dog, HFMD cat and the highly variable onset and progression, but the unifying δ-sarcoglycan-deficient BIO 14.6 cardiomyopathic hamster) theme among the limb–girdle muscular dystrophies is the that share common genetic protein abnormalities similar to initial involvement of the shoulder and pelvic girdle those of the human disease. However, the naturally occurring muscles. Moreover, muscular dystrophies may or may not animal models only partially resemble human disease. In be associated with cardiomyopathy [1–4]. addition, no naturally occurring mouse models associated with loss of other DGC components are available. This has Combined positional cloning and candidate gene encouraged the generation of genetically engineered mouse approaches have been used to identify an increasing number models for DGC-linked muscular dystrophy. Not only have of genes that are mutated in various forms of muscular analyses of these mice led to a significant improvement in our dystrophy.
    [Show full text]
  • Disrupted Mechanical Stability of the Dystrophin- Glycoprotein Complex Causes Severe Muscular Dystrophy in Sarcospan Transgenic Mice
    996 Research Article Disrupted mechanical stability of the dystrophin- glycoprotein complex causes severe muscular dystrophy in sarcospan transgenic mice Angela K. Peter1,*, Gaynor Miller1,* and Rachelle H. Crosbie1,2,‡ 1Department of Physiological Science and 2Molecular Biology Institute, University of California, Los Angeles, CA 90095, USA *These authors contributed equally to this work ‡Author for correspondence (e-mail: [email protected]) Accepted 23 November 2006 Journal of Cell Science 120, 996-1008 Published by The Company of Biologists 2007 doi:10.1242/jcs.03360 Summary The dystrophin-glycoprotein complex spans the muscle pathology marked by increased muscle fiber degeneration plasma membrane and provides a mechanical linkage and/or regeneration. Sarcospan transgenic muscle does not between laminin in the extracellular matrix and actin in the display sarcolemma damage, which is distinct from intracellular cytoskeleton. Within the dystrophin- dystrophin- and sarcoglycan-deficient muscular glycoprotein complex, the sarcoglycans and sarcospan dystrophies. We show that sarcospan clusters the constitute a subcomplex of transmembrane proteins that sarcoglycans into insoluble protein aggregates and causes stabilize ␣-dystroglycan, a receptor for laminin and other destabilization of ␣-dystroglycan. Evidence is provided to components of the extracellular matrix. In order to demonstrate abnormal extracellular matrix assembly, elucidate the function of sarcospan, we generated which represents a probable pathological mechanism for transgenic mice that overexpress sarcospan in skeletal the severe and lethal dystrophic phenotype. Taken together, muscle. Sarcospan transgenic mice with moderate (tenfold) these data suggest that sarcospan plays an important levels of sarcospan overexpression exhibit a severe mechanical role in stabilizing the dystrophin-glycoprotein phenotype that is similar to mouse models of laminin- complex.
    [Show full text]
  • A Structural Fix For
    TARGETS & MECHANISMS JCB paper is important because it identifies another potential target for treating muscular dystrophy. “The paper provides a nice demonstration of a protein that could replace or partially replace dystrophin in order to stabilize the sarcolemma,” he said. The company’s PTC124 is in Phase IIb testing to treat DMD due to a A structural fix nonsense mutation. PTC expects to complete enrollment in the trial by next February. The small molecule that facilitates complete translation of proteins containing nonsense mutations is partnered with Genzyme for DMD Corp. PTC124 has Fast Track designation in the U.S. and Orphan Drug By Brian Moy, Staff Writer designations for nonsense mutation–related DMD and cystic fibrosis in the U.S. and EU. Researchers at the University of California, Los Angeles have found that increasing expression of the structural protein sarcospan improves Utrophin utility dystrophic pathology in mice with Duchenne muscular dystrophy. Although the JCB paper identifies a new approach for treating DMD, Although the finding identifies a new way to treat the disease, one con- increasing the level of sarcospan is likely to only temporarily relieve cern is that increasing levels of sarcospan will only slow muscle degen- the disease pathology. eration and simply delay the inevitable progression of the disease. Jon Tinsley, senior director of therapeutic programs at Summit plc, Sarcospan (Kras oncogene-associated gene) (SSPN) is a component told SciBX that recombinant sarcospan injected systemically could pro- of the dystrophin-glycoprotein complex in muscle cells. During muscle vide some therapeutic benefit, but sooner or later the natural utrophin contraction, the complex provides mechanical protein will become degraded and lost.
    [Show full text]
  • Generation and Characterization of a Dmdegfp Reporter Mouse As a Tool to Investigate Dystrophin Expression Mina Petkova
    Generation and characterization of a dmdegfp reporter mouse as a tool to investigate dystrophin expression Mina Petkova To cite this version: Mina Petkova. Generation and characterization of a dmdegfp reporter mouse as a tool to investigate dystrophin expression. Cellular Biology. Université Pierre et Marie Curie - Paris VI; Freie Universität (Berlin). Fachbereich Biologie, 2016. English. NNT : 2016PA066090. tel-01458772 HAL Id: tel-01458772 https://tel.archives-ouvertes.fr/tel-01458772 Submitted on 7 Feb 2017 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Generation and Characterization of a DmdEGFP Reporter Mouse as a Tool to Investigate Dystrophin Expression Inaugural-Dissertation to obtain the academic degree Doctor rerum naturalium (Dr. rer. nat.) Submitted to the Department of Biology, Chemistry and Pharmacy of the Freie Universität Berlin and in cotutelle to the Ecole Doctorale 515 "Complexité du vivant" of Université Pierre et Marie Curie Paris by Mina Petkova from Sofia, Bulgaria 2016 The research presented in this thesis was conducted from October 2011 until December 2015 in the followng laboratories: Department of neuropediatrics and NeuroCure, Charité Cross Over, Charité Universitätmedizin, Berlin, Germany. Biothérapies des maladies neuromusculaires, UFR des sciences de la santé Simone Veil, Université de Versailles Saint-Quentin-en-Yvelines, France.
    [Show full text]
  • Fukutin-Related Protein Associates with the Sarcolemmal Dystrophin
    Supplemental Material can be found at: http://www.jbc.org/cgi/content/full/C700061200/DC1 ACCELERATED PUBLICATION This paper is available online at www.jbc.org THE JOURNAL OF BIOLOGICAL CHEMISTRY VOL. 282, NO. 23, pp. 16713–16717, June 8, 2007 © 2007 by The American Society for Biochemistry and Molecular Biology, Inc. Printed in the U.S.A. Fukutin-related Protein with variable heart, respiratory, and brain involvement (1–3). Although the specific function of FKRP is unclear, FKRP and its Associates with the closest known homolog fukutin share sequence homology with Sarcolemmal Dystrophin- phosphoryl ligand transferases and contain DXD domains common to some glycosyltransferases (4, 5). In addition, FKRP- *□S Glycoprotein Complex associated muscular dystrophies fall into a growing family of Received for publication, March 30, 2007, and in revised form, April 17, 2007 “dystroglycanopathies,” which exhibit reduced glycosylation of Published, JBC Papers in Press, April 23, 2007, DOI 10.1074/jbc.C700061200 membrane-associated ␣DG (6). Extracellular ␣DG and the 1 2 Aaron M. Beedle , Patricia M. Nienaber, and Kevin P. Campbell transmembrane-spanning ␤DG bind to dystrophin, sarcogly- From the Howard Hughes Medical Institute (HHMI) and the Departments cans, and other proteins to form the dystrophin-glycoprotein of Molecular Physiology and Biophysics, Internal Medicine, and Neurology, University of Iowa Carver College of Medicine, Iowa City, Iowa 52242 complex (DGC), which serves as a critical structural link between the cell cytoskeleton, the sarcolemma, and the extra- Mutations in fukutin-related protein (FKRP) give rise to mild cellular basement membrane. ␣DG glycans, detected by anti- Downloaded from and more severe forms of muscular dystrophy.
    [Show full text]