Mitogenic repression of myogenin autoregulation.
The muscle-specific helix-loop-helix proteins MyoD and myogenin have been shown to positively autoregulate their own expression and to cross-activate one another's expression following transfection into a variety of nonmyogenic cell lines. We show that the ability of an exogenous myogenin expression vector to activate the endogenous myogenin allele in 10T1/2 fibroblasts is dependent on serum withdrawal. Repression of myogenin autoregulation by serum can be observed with a reporter gene linked to myogenin upstream sequences, indicating that repression occurs at the level of transcription. Like MyoD, myogenin exhibits a short half-life (approximately 20 min), which may serve to maintain the autoregulatory loop without allowing excess accumulation of the protein.
Edmondson
D G
DG
Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston 77030.
Brennan
T J
TJ
Olson
E N
EN
D000818:Animals; D015152:Blotting, Northern; D002460:Cell Line; D006706:Homeostasis; D007700:Kinetics; D008715:Methionine / Q000378:metabolism; D051379:Mice; D009124:Muscle Proteins / Q000096:biosynthesis / Q000235:genetics*; D009132:Muscles / Q000378:metabolism*; D018008:Myogenin; D010957:Plasmids; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D013462:Sulfur Radioisotopes; D015534:Trans-Activators / Q000235:genetics; D014162:Transfection
D009124:Muscle Proteins; C503801:Myog protein, mouse; D018008:Myogenin; D013462:Sulfur Radioisotopes; D015534:Trans-Activators; D012313:RNA; D008715:Methionine