title: Combinatorial transcription factor regulation of the cyclic AMP-response element on the Pgc-1alpha promoter in white 3T3-L1 and brown HIB-1B preadipocytes.
abstract: Cold stress in rodents increases the expression of UCP1 and PGC-1alpha in brown and white adipose tissue. We have previously reported that C/EBPbeta specifically binds to the CRE on the proximal Pgc-1alpha promoter and increases forskolin-sensitive Pgc-1alpha and Ucp1 expression in white 3T3-L1 preadipocytes. Here we show that in mice exposed to a cold environment for 24 h, Pgc-1alpha, Ucp1, and C/ebpbeta but not C/ebpalpha or C/ebpdelta expression were increased in BAT. Conversely, expression of the C/EBP dominant negative Chop10 was increased in WAT but not BAT during cold exposure. Reacclimatization of cold-exposed mice to a warm environment for 24 h completely reversed these changes in gene expression. In HIB-1B, brown preadipocytes, forskolin increased expression of Pgc-1alpha, Ucp1, and C/ebpbeta early in differentiation and inhibited Chop10 expression. Employing chromatin immunoprecipitation, we demonstrate that C/EBPbeta, CREB, ATF-2, and CHOP10 are bound to the Pgc-1alpha proximal CRE, but CHOP10 does not bind in HIB-1B cell lysates. Forskolin stimulation and C/EBPbeta overexpression in 3T3-L1 cells increased C/EBPbeta and CREB but displaced ATF-2 and CHOP10 binding to the Pgc-1alpha proximal CRE. Overexpression of ATF-2 and CHOP10 in 3T3-L1 cells decreased Pgc-1alpha transcription. Knockdown of Chop10 in 3T3-L1 cells using siRNA increased Pgc-1alpha transcription, whereas siRNA against C/ebpbeta in HIB-1B cells decreased Pgc-1alpha and Ucp1 expression. We conclude that the increased cAMP stimulation of Pgc-1alpha expression is regulated by the combinatorial effect of transcription factors acting at the CRE on the proximal Pgc-1alpha promoter.
authors.affiliation: School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD.
authors.forename: Angeliki
authors.initials: A
authors.lastname: Karamitri
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Shore
authors.forename: Kevin
authors.initials: K
authors.lastname: Docherty
authors.forename: John R
authors.initials: JR
authors.lastname: Speakman
authors.forename: Michael A
authors.initials: MA
authors.lastname: Lomax
mesh_terms: D051698:Activating Transcription Factor 2 / Q000378:metabolism; D017667:Adipocytes / Q000187:drug effects / Q000378:metabolism*; D002001:Adipose Tissue, Brown / Q000166:cytology*; D052436:Adipose Tissue, White / Q000166:cytology*; D000375:Aging / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism; D003080:Cold Temperature; D000242:Cyclic AMP / Q000494:pharmacology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D007473:Ion Channels / Q000378:metabolism; D051379:Mice; D024101:Mitochondrial Proteins / Q000378:metabolism; D009928:Organ Specificity / Q000187:drug effects; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D011485:Protein Binding / Q000187:drug effects; D020033:Protein Isoforms / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D020218:Response Elements / Q000235:genetics*; D015534:Trans-Activators / Q000235:genetics*; D051742:Transcription Factor CHOP / Q000378:metabolism*; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000187:drug effects; D000071256:Uncoupling Protein 1
chemical_list: D051698:Activating Transcription Factor 2; C497106:Atf2 protein, mouse; D022782:CCAAT-Enhancer-Binding Protein-beta; D017362:Cyclic AMP Response Element-Binding Protein; C497250:Ddit3 protein, mouse; D007473:Ion Channels; D024101:Mitochondrial Proteins; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C485290:Ppargc1a protein, mouse; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D015534:Trans-Activators; D014157:Transcription Factors; C000604371:UCP1 protein, human; C000604372:Ucp1 protein, mouse; C000604373:Ucp1 protein, rat; D000071256:Uncoupling Protein 1; D051742:Transcription Factor CHOP; D000242:Cyclic AMP