The effect of platelet-derived growth factor and adipogenic hormones on the expression of CCAAT/enhancer-binding proteins in 3T3-L1 cells in serum-free conditions.
In the absence of serum and serum substitutes, insulin at high doses together with platelet-derived growth factor BB (PDGF BB), corticosterone, and 3-isobutyl-1-methyl-xanthine is required to stimulate differentiation of 3T3-L1 preadipocytes. Under these conditions the differentiating cells express the CCAAT/enhancer-binding proteins (C/EBP) C/EBPdelta, C/EBPbeta, and C/EBP alpha with a similar sequence as described for differentiating cells in the presence of serum. The major differences detected under serum-free conditions are as follows: (a) PDGF BB is the major stimulator of the expression of the C/EBPbeta isoform liver activator protein (LAP). (b) The expression of LAP is also increased in preconfluent, proliferating cells due to the treatment with PDGF BB. (c) A small protein of 20 kDa (p20C/EBPbeta is detected with the anti-C/EBPbeta antibody. It is synthesized at high levels in such cells, which subsequently express high levels of the differentiation markers C/EBP alpha and glycerol-3-phosphate dehydrogenase. (d) Treatment of cells with fibroblast growth factor-2 (bFGF) in addition to adipogenic hormones results in differentiation and C/EBP alpha expression only to a very moderate extent as compared to treatment with PDGF BB but leads to a strong expression of both C/EBPbeta and C/EBPdelta.
Bachmeier
M
M
Institute for Biochemistry, Genetics and Microbiology, University of Regensburg, Germany.
Löffler
G
G
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology*; D000818:Animals; D022762:CCAAT-Enhancer-Binding Proteins; D002454:Cell Differentiation / Q000187:drug effects; D003345:Corticosterone / Q000494:pharmacology; D003470:Culture Media; D004268:DNA-Binding Proteins / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*
D022762:CCAAT-Enhancer-Binding Proteins; D003470:Culture Media; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D010982:Platelet-Derived Growth Factor; D014157:Transcription Factors; D016222:Fibroblast Growth Factor 2; D015056:1-Methyl-3-isobutylxanthine; D003345:Corticosterone