title: Antisense inhibition of syndecan-3 expression during skeletal muscle differentiation accelerates myogenesis through a basic fibroblast growth factor-dependent mechanism.
abstract: Syndecan-3 is a member of a family of transmembrane proteoglycans that posses highly homologous cytoplasmic and transmembrane domains and function as extracellular matrix receptors and low-affinity receptors for signaling molecules such as basic fibroblasts growth factor (FGF-2). Syndecan-3 is transiently expressed in developing limb bud and absent in adult skeletal muscle. In this study we investigated the expression of syndecan-3 and its role on FGF-2-dependent inhibition of myogenesis. Syndecan-3 expression was down-regulated during skeletal muscle differentiation of C(2)C(12) myoblasts, as determined by Northern blot analyses and immunoprecipitation. To probe the function of syndecan-3 during myogenesis, C(2)C(12) myoblasts were stably transfected with a plasmid coding for antisense syndecan-3 mRNA. The resulting inhibition of syndecan-3 expression caused accelerated skeletal muscle differentiation, as determined by expression of creatine kinase and myosin and myoblast fusion. Expression of a master transcription factor for muscle differentiation, myogenin, was also accelerated in antisense syndecan-3-transfected myoblasts compared with control transfected and wild type cells. Reduced expression of syndecan-3 resulted in a 13-fold decrease in sensitivity to FGF-2-dependent inhibition of myogenin expression. Addition of heparin partially reversed this effect. These results demonstrate that syndecan-3 expression is down-regulated during differentiation and the level of expression of membrane-bound heparan sulfate on myoblast surface is critical for fine modulation of responsiveness to FGF-2. These findings strongly suggest a role for syndecan-3 in regulation of skeletal muscle terminal differentiation.
authors.affiliation: Department of Cell Biology, Faculty of Biological Sciences, Catholic University of Chile, Santiago, Chile.
authors.forename: L
authors.initials: L
authors.lastname: Fuentealba
authors.forename: D J
authors.initials: DJ
authors.lastname: Carey
authors.forename: E
authors.initials: E
authors.lastname: Brandan
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D016222:Fibroblast Growth Factor 2 / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D011509:Proteoglycans / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D053670:Syndecan-3; D014162:Transfection
chemical_list: D008562:Membrane Glycoproteins; D016376:Oligonucleotides, Antisense; D011509:Proteoglycans; C508302:Sdc3 protein, mouse; D053670:Syndecan-3; D016222:Fibroblast Growth Factor 2