PPARγ2 is expressed almost exclusively in adipose tissue and plays a central role in adipogenesis. Despite intensive studies over the last 2 decades, the mechanism regulating the expression of the Pparg2 gene, especially the role of cis-regulatory elements, is still not completely understood. Here, we report a comprehensive investigation of the enhancer elements within the murine Pparg2 gene. Utilizing the combined techniques of sequence conservation analysis and chromatin marker examination, we identified a potent enhancer element that augmented the expression of a reporter gene under the control of the Pparg2 promoter by 20-fold. This enhancer element was first identified as highly conserved non-coding sequence 10 (CNS10) and was later shown to be enriched with the enhancer marker H3 K27 acetylation. Further studies identified a binding site for p300 as the essential enhancer element in CNS10. Moreover, p300 physically binds to CNS10 and is required for the enhancer activity of CNS10. The depletion of p300 by siRNA resulted in significantly impaired activation of Pparg2 at the early stages of 3T3-L1 adipogenesis. In summary, our study identified a novel enhancer element on the murine Pparg2 gene and suggested a novel mechanism for the regulation of Pparg2 expression by p300 in 3T3-L1 adipogenesis.
Keywords: 3-isobutyl-1-methylxanthine; Rosi; CNS; H3 K27 acetylation; PPAR-Response Elements; TSS; PPARg2; adipogenesis; chromatin immunoprecipitation; GR; conserved non-coding sequence; TZDs; dexamethasone; IBMX; enhancer; glucocorticoid receptor; PPRE; lysine acetyl-transferase; DEX; p300; rosiglitazone; ChIP; thiazolidinediones; KAT; transcription start site.