PPARgamma and C/EBP factors orchestrate adipocyte biology via adjacent binding on a genome-wide scale.
Peroxisome proliferator-activated receptor gamma(PPARgamma), a nuclear receptor and the target of anti-diabetic thiazolinedione drugs, is known as the master regulator of adipocyte biology. Although it regulates hundreds of adipocyte genes, PPARgamma binding to endogenous genes has rarely been demonstrated. Here, utilizing chromatin immunoprecipitation (ChIP) coupled with whole genome tiling arrays, we identified 5299 genomic regions of PPARgamma binding in mouse 3T3-L1 adipocytes. The consensus PPARgamma/RXRalpha "DR-1"-binding motif was found at most of the sites, and ChIP for RXRalpha showed colocalization at nearly all locations tested. Bioinformatics analysis also revealed CCAAT/enhancer-binding protein (C/EBP)-binding motifs in the vicinity of most PPARgamma-binding sites, and genome-wide analysis of C/EBPalpha binding demonstrated that it localized to 3350 of the locations bound by PPARgamma. Importantly, most genes induced in adipogenesis were bound by both PPARgamma and C/EBPalpha, while very few were PPARgamma-specific. C/EBPbeta also plays a role at many of these genes, such that both C/EBPalpha and beta are required along with PPARgamma for robust adipocyte-specific gene expression. Thus, PPARgamma and C/EBP factors cooperatively orchestrate adipocyte biology by adjacent binding on an unanticipated scale.
Lefterova
Martina I
MI
Institute for Diabetes, Obesity, and Metabolism, and Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA.
Zhang
Yong
Y
Steger
David J
DJ
Schupp
Michael
M
Schug
Jonathan
J
Cristancho
Ana
A
Feng
Dan
D
Zhuo
David
D
Stoeckert
Christian J
CJ
Liu
X Shirley
XS
Lazar
Mitchell A
MA
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology / Q000502:physiology*; D000818:Animals; D022763:CCAAT-Enhancer-Binding Protein-alpha / Q000378:metabolism*; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology; D047369:Chromatin Immunoprecipitation; D016678:Genome; D051379:Mice; D047495:PPAR gamma / Q000378:metabolism*; D011485:Protein Binding; D014158:Transcription, Genetic
D022763:CCAAT-Enhancer-Binding Protein-alpha; D022782:CCAAT-Enhancer-Binding Protein-beta; D047495:PPAR gamma