The Gene Encoding the Acyl-CoA-binding Protein Is Activated by Peroxisome Proliferator-activated Receptor γ through an Intronic Response Element Functionally Conserved between Humans and Rodents

The acyl-CoA-binding protein (ACBP) is a 10-kDa intracellular protein that specifically binds acyl-CoA esters with high affinity and is structurally and functionally conserved from yeast to mammals. In vitro studies indicate that ACBP may regulate the availability of acyl-CoA esters for various metabolic and regulatory purposes. The protein is particularly abundant in cells with a high level of lipogenesis and de novo fatty acid synthesis and is significantly induced during adipocyte differentiation. However, the molecular mechanisms underlying the regulation of ACBP expression in mammalian cells have remained largely unknown. Here we report that ACBP is a novel peroxisome proliferator-activated receptor (PPAR)γ target gene. The rat ACBP gene is directly activated by PPARγ/retinoid X receptor α (RXRα) and PPARα/RXRα, but not by PPARδ/RXRα, through a PPAR-response element in intron 1, which is functionally conserved in the human ACBP gene. The intronic PPAR-response element (PPRE) mediates induction by endogenous PPARγ in murine adipocytes and confers responsiveness to the PPARγ-selective ligand BRL49653. Finally, we have used chromatin immunoprecipitation to demonstrate that the intronic PPRE efficiently binds PPARγ/RXR in its natural chromatin context in adipocytes. Thus, the PPRE in intron 1 of the ACBP gene is a bona fidePPARγ-response element.