Adipocyte differentiation selectively represses the serum inducibility of c-jun and junB by reversible transcription-dependent mechanisms.
Nonterminally differentiated 3T3 T adipocytes are resistant to growth stimulation by 10% (vol/vol) fetal bovine serum even though they can be induced to proliferate with extremely high serum concentrations. We now report that in adipocytes 10% fetal bovine serum also fails to typically induce c-jun or junB. Rather, after 10% fetal bovine serum treatment, c-jun and junB expression is markedly repressed after a brief initial slight induction. Gel mobility shift studies confirm that AP-1 DNA binding activity is inhibited in adipocytes. Repression in c-jun and junB inducibility in adipocytes results from transcriptional mechanisms, can be reversed by treatment with protein synthesis inhibitors or higher serum concentrations, and does not affect c-fos or c-myc expression. These data suggest that adipocyte differentiation selectively and transcriptionally represses the inducibility of c-jun and junB so as to decrease the cell's ability to proliferate in response to 10% fetal bovine serum.
Wang
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Department of Pathology, University of Tennessee College of Medicine, Memphis 38163.
Scott
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D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology* / Q000378:metabolism; D000818:Animals; D001769:Blood; D002454:Cell Differentiation; D003470:Culture Media; D003513:Cycloheximide / Q000494:pharmacology; D005786:Gene Expression Regulation; D007700:Kinetics; D051379:Mice; D016755:Proto-Oncogene Proteins c-jun / Q000235:genetics*; D014158:Transcription, Genetic
D003470:Culture Media; D016755:Proto-Oncogene Proteins c-jun; D003513:Cycloheximide