OBESITY AND THE ADIPOCYTE PPARã and the molecular control of adipogenesis

Major insights into the understanding of the molecular regulation of adipocyte diVerentiation have stemmed from the characterization of important transcription factor bind-ing sites in the regulatory regions of genes expressed specifically in mature adipocytes. These studies resulted in the identification of two families of transcription factors which play critical roles in the regulation of adipogenesis, the CCAAT/enhancer-binding protein (C/EBP) family members and the peroxisome proliferator-activated recep-tors (PPARs) (for review see Brun et al. 1996a). C/EBPâ and C/EBPä are induced early and transiently in adipocyte diVerentiation while C/EBPá expression is induced late (Cao et al. 1991, Yeh et al. 1995). C/EBPá has been shown to activate the promoters of several genes expressed in the mature adipocyte, overexpression o