SM-20 is a novel growth factor-responsive gene regulated during skeletal muscle development and differentiation.
SM-20 is a novel, evolutionarily conserved "early response" gene originally cloned from a rat aortic smooth muscle cell (SMC) cDNA library. SM-20 encodes a cytoplasmic protein, which is induced by platelet-derived growth factor and angiotensin II in cultured SMC and is upregulated in intimal SMC of atherosclerotic plaques and injured arteries. We have now examined SM-20 expression during differentiation of cultured skeletal myoblasts and during skeletal myogenesis in vivo. Low levels of SM-20 mRNA and protein were expressed in proliferating mouse C2C12 myoblasts. Differentiation by serum withdrawal was associated with a marked induction of SM-20 mRNA and the expression of high levels of SM-20 antigen in myotubes. The induction was partially inhibited by blocking differentiation with bFGF or TGFbeta. Similar results were obtained with the nonfusing mouse C25 myoblast line, suggesting that SM-20 upregulation is a consequence of biochemical differentiation and is fusion independent. During mouse embryogenesis, SM-20 was first observed at 8.5E in the dermomyotomal cells of the rostral somites. SM-20 expression progressed in a rostral to caudal pattern, with highest levels seen in the muscle primordia and mature muscles. SM-20 thus represents a novel intracellular protein that is regulated during skeletal muscle differentiation and development.
Moschella
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MC
The Michael A. and Zena Wiener Cardiovascular Institute, Department of Medicine, The Mount Sinai School of Medicine, New York, NY 10029, USA.
Menzies
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K
Tsao
L
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Lieb
M A
MA
Kohtz
J D
JD
Kohtz
D S
DS
Taubman
M B
MB
D000818:Animals; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D018507:Gene Expression Regulation, Developmental; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D008815:Mice, Inbred Strains; D018482:Muscle, Skeletal / Q000166:cytology / Q000196:embryology* / Q000378:metabolism*; D011393:Procollagen-Proline Dioxygenase; D015854:Up-Regulation
D004268:DNA-Binding Proteins; D017874:Immediate-Early Proteins; D011393:Procollagen-Proline Dioxygenase; C490189:Egln1 protein, mouse; D064799:Hypoxia-Inducible Factor-Proline Dioxygenases