ECM is required for skeletal muscle differentiation independently of muscle regulatory factor expression.
Transcription of specific skeletal muscle genes requires the expression of the muscle regulatory factor myogenin. To assess the role of the extracellular matrix (ECM) in skeletal muscle differentiation, the specific inhibitors of proteoglycan synthesis, sodium chlorate and beta-D-xyloside, were used. Treatment of cultured skeletal muscle cells with each inhibitor substantially abolished the expression of creatine kinase and alpha-dystroglycan. This inhibition was totally reversed by the addition of exogenous ECM. Myoblast treatment with each inhibitor affected the deposition and assembly of the ECM constituents glypican, fibronectin, and laminin. These treatments did not affect MyoD, MEF2A, and myogenin expression and nuclear localization. Differentiated myoblast treatment with RGDS peptides completely inhibited myogenesis without affecting the expression or nuclear localization of myogenin. Integrin-mediated signaling of focal adhesion kinase was partially inhibited by chlorate and beta-D-xyloside, an effect reversed by the addition of exogenous ECM gel. These results suggested that the expression of myogenin is not sufficient to successfully drive skeletal muscle formation and that ECM is required to complete the skeletal muscle differentiation process.
Osses
Nelson
N
Centro de Regulación Celular y Patología, Departamento de Biología Celular y Molecular, Facultad de Ciencias Biológicas, Millennium Institute for Fundamental and Applied Biology, Pontificia Universidad Católica de Chile, Santiago, Chile.
Brandan
Enrique
E
D000818:Animals; D015415:Biomarkers; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D005109:Extracellular Matrix / Q000187:drug effects / Q000502:physiology*; D006027:Glycosides / Q000494:pharmacology; D051379:Mice; D018482:Muscle, Skeletal / Q000166:cytology* / Q000502:physiology; D018008:Myogenin / Q000502:physiology*; D011509:Proteoglycans / Q000502:physiology; D014157:Transcription Factors / Q000378:metabolism
D015415:Biomarkers; D006027:Glycosides; C503801:Myog protein, mouse; D018008:Myogenin; D011509:Proteoglycans; D014157:Transcription Factors; C010807:xylosides