Syndecan-1 expression is down-regulated during myoblast terminal differentiation. Modulation by growth factors and retinoic acid.
Syndecan-1 is an integral membrane proteoglycan involved in the interaction of cells with extracellular matrix proteins and growth factors. It is transiently expressed in several condensing mesenchymal tissues after epithelial induction. In this study we evaluated the expression of syndecan-1 during skeletal muscle differentiation. The expression of syndecan-1 as determined by Northern blot analyses and immunofluorescence microscopy is down-regulated during differentiation. The transcriptional activity of a syndecan-1 promoter construct is also down-regulated in differentiating muscle cells. The decrease in syndecan-1 gene expression is not dependent on the presence of E-boxes, binding sites for the MyoD family of transcription factors in the promoter region, or myogenin expression. Deletion of the region containing the E-boxes or treatment of differentiating cells with sodium butyrate, an inhibitor of myogenin expression, had no effect on syndecan-1 expression. Basic fibroblast growth factor and transforming growth factor type beta, which are inhibitors of myogenesis, had little effect on syndecan-1 expression. When added together, however, they induced syndecan-1 expression. Retinoic acid, an inducer of myogenesis, inhibited syndecan-1 expression and abolished the effect of the growth factors. These results indicate that syndecan-1 expression is down-regulated during myogenesis and that growth factors and retinoic acid modulate syndecan-1 expression by a mechanism that is independent of myogenin.
Larraín
J
J
Department of Cell and Molecular Biology, Faculty of Biological Sciences, Catholic University of Chile, Casilla 114-D, Santiago, Chile.
Cizmeci-Smith
G
G
Troncoso
V
V
Stahl
R C
RC
Carey
D J
DJ
Brandan
E
E
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002460:Cell Line; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006133:Growth Substances / Q000494:pharmacology*; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D051379:Mice; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018008:Myogenin / Q000096:biosynthesis; D011509:Proteoglycans / Q000096:biosynthesis*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D053668:Syndecan-1; D053667:Syndecans; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014212:Tretinoin / Q000494:pharmacology*
D006133:Growth Substances; D008562:Membrane Glycoproteins; C503801:Myog protein, mouse; D018008:Myogenin; D011509:Proteoglycans; D011993:Recombinant Fusion Proteins; C508242:Sdc1 protein, mouse; D053668:Syndecan-1; D053667:Syndecans; D016212:Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; D014212:Tretinoin; D015500:Chloramphenicol O-Acetyltransferase