Regulation of c-jun/AP-1 expression in rat L6 myoblasts.
Myogenic differentiation of skeletal myoblasts in culture is triggered by withdrawal of serum mitogens. Expression of one of the serum-inducible, immediate early genes, the protooncogene c-jun, is maintained under low-serum conditions during myogenic differentiation of L6 myoblasts. In this report we have used agents that modulate protein kinases and Ca2+ levels to investigate how the expression of c-jun and myogenin mRNA and also the activator protein 1 (AP-1) DNA-binding activity are regulated in differentiating L6 cells. Our results show that expression of c-jun and myogenin are regulated independent of each other. Furthermore, down regulation of c-jun expression does not cause an increase in myogenin expression, suggesting that c-jun does not suppress myogenin expression in these cells. Electrophoretic mobility shift and ultraviolet cross-linking analyses revealed that the AP-1 complexes of proliferating myoblasts and differentiating myotubes are formed of similar set of polypeptides, and the AP-1 binding activity is probably modulated by posttranslational modifications in differentiating L6 cells.
Thinakaran
G
G
Department of Molecular Biology and Genetics, University of Guelph, Ont., Canada.
Bag
J
J
D000818:Animals; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D002999:Clone Cells; D016895:Culture Media, Serum-Free; D000242:Cyclic AMP / Q000378:metabolism; D015536:Down-Regulation; D004533:Egtazic Acid / Q000494:pharmacology; D005786:Gene Expression Regulation; D009132:Muscles / Q000166:cytology; D018008:Myogenin / Q000235:genetics; D011487:Protein Conformation; D011494:Protein Kinases / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics* / Q000528:radiation effects; D012333:RNA, Messenger / Q000096:biosynthesis*; D051381:Rats; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology; D015534:Trans-Activators / Q000235:genetics; D014466:Ultraviolet Rays
D016895:Culture Media, Serum-Free; C503803:Myog protein, rat; D018008:Myogenin; D016755:Proto-Oncogene Proteins c-jun; D012333:RNA, Messenger; D015534:Trans-Activators; D004533:Egtazic Acid; D000242:Cyclic AMP; D011494:Protein Kinases; D002118:Calcium