Hormone-sensitive lipase (HSL) catalyzes the rate-limiting step of lipolysis in adipose tissue. Several studies suggest that protein phosphorylation regulates the HSL enzymatic activity. On the other hand, the precise mechanism of the transcriptional regulation of the HSL gene remains to be elucidated. Here, we identified a functional peroxisome-proliferator responsive element (PPRE) in the mouse HSL promoter by reporter assay in CV-1 cells using serial deletion and point mutants of the 5'-flanking region. Chromatin immunoprecipitation (ChIP) analysis revealed that both peroxisome-proliferator activated receptor (PPAR gamma) and retinoid X receptor (RXR alpha) interacted with the region. Binding of the PPAR gamma/RXR alpha heterodimer to the PPRE sequence was also confirmed by electrophoretic mobility shift assay. These results indicate that the HSL gene is transcriptionally regulated by PPAR gamma/RXR alpha heterodimer, and suggest that a cis-acting element regulates the HSL gene expression. (c) 2006 Elsevier Inc. All rights reserved.