PMID: 2104845Jan 25, 1990Paper

Different members of the jun proto-oncogene family exhibit distinct patterns of expression in response to type beta transforming growth factor.

The Journal of Biological Chemistry
L LiE N Olson

Abstract

Type beta transforming growth factor (TGF-beta) is a multifunctional regulator of cell growth and differentiation. In the BC3H1 muscle cell line, TGF-beta blocks the onset of differentiation when added to undifferentiated myoblasts and causes dedifferentiation when added to fully differentiated myocytes. The goal of the present study was to determine whether TGF-beta-dependent repression of muscle-specific genes was preceded by modulation in expression of members of the jun proto-oncogene family, which function as growth factor-inducible transcription factors. junB mRNA was expressed at a basal level in differentiated BC3H1 myocytes. Within 15 min following exposure of myocytes to TGF-beta, junB mRNA began to accumulate; a peak of expression 20-fold above basal levels was observed after 2 h with a gradual decline thereafter. Nuclear run-on transcription assays showed that induction of junB by TGF-beta occurred at the level of transcription through a mechanism independent of protein synthesis. junB was also induced by 20% fetal bovine serum, platelet-derived growth factor, and insulin, but the maximal level of expression in response to these growth factors was lower and less sustained than in the presence of TGF-beta. In contras...Continue Reading

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