C/EBPbeta reprograms white 3T3-L1 preadipocytes to a Brown adipocyte pattern of gene expression.
cAMP-dependent protein kinase induction of PPARgamma coactivator-1alpha (PGC-1alpha) and uncoupling protein 1 (UCP1) expression is an essential step in the commitment of preadipocytes to the brown adipose tissue (BAT) lineage. We studied the molecular mechanisms responsible for differential expression of PGC-1alpha in HIB1B (BAT) and 3T3-L1 white adipose tissue (WAT) precursor cell lines. In HIB1B cells PGC-1alpha and UCP1 expression is cAMP-inducible, but in 3T3-L1 cells, expression is reduced and is cAMP-insensitive. A proximal 264-bp PGC-1alpha reporter construct was cAMP-inducible only in HIB1B cells and was suppressed by site-directed mutagenesis of the proximal cAMP response element (CRE). In electrophoretic mobility shift assays, the transcription factors CREB and C/EBPbeta, but not C/EBPalpha and C/EBPdelta, bound to the CRE on the PGC-1alpha promoter region in HIB1B and 3T3-L1 cells. Chromatin immunoprecipitation studies demonstrated that C/EBPbeta and CREB bound to the CRE region in HIB1B and 3T3-L1 cell lysates. C/EBPbeta expression was induced by cAMP only in HIB1B cells, and overexpression of C/EBPbeta rescued cAMP-inducible PGC-1alpha and UCP1 expression in 3T3-L1 cells. These data demonstrate that differentiation of preadipocytes toward the BAT rather than the WAT phenotype is controlled in part by the action of C/EBPbeta on the CRE in PGC-1alpha proximal promoter.
Karamanlidis
Georgios
G
School of Biological Sciences, University of Aberdeen, Aberdeen, AB24 5UH, United Kingdom.
Karamitri
Angeliki
A
Docherty
Kevin
K
Hazlerigg
David G
DG
Lomax
Michael A
MA
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology* / Q000378:metabolism; D000273:Adipose Tissue / Q000378:metabolism; D002001:Adipose Tissue, Brown / Q000378:metabolism; D000818:Animals; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism*; D002454:Cell Differentiation; D000242:Cyclic AMP / Q000378:metabolism; D005786:Gene Expression Regulation; D051379:Mice; D008954:Models, Biological; D016297:Mutagenesis, Site-Directed; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors
D022782:CCAAT-Enhancer-Binding Protein-beta; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D015534:Trans-Activators; D014157:Transcription Factors; D000242:Cyclic AMP