Farnesoid X receptor represses hepatic lipase gene expression

Audrey Sirvent, Adrie J. M. Verhoeven, Hans Jansen, Vladimir Kosykh, Raphaël J. Darteil, Dean W. Hum, Jean-Charles Fruchart, Bart Staels
2004 Journal of Lipid Research  
The farnesoid X receptor (FXR) is a nuclear receptor that regulates gene expression in response to bile acids (BAs). FXR plays a central role in BA, cholesterol, and lipoprotein metabolism. Here, we identify HL, an enzyme involved in the metabolism of remnant and high density lipoproteins, as a novel FXR-regulated gene. The natural FXR ligand, chenodeoxycholic acid (CDCA), downregulates HL gene expression in a dose-and time-dependent manner in human hepatoma HepG2 cells. The nonsteroidal
more » ... nonsteroidal synthetic FXR agonist GW4064 also decreases HL mRNA levels in HepG2 cells and in primary human hepatocytes. Moreover, the decrease of HL mRNA levels after treatment with FXR agonists was associated with a significant decrease in secreted enzymatic activity. In addition, FXR-specific gene silencing using small interfering RNAs demonstrated that CDCA-and GW4064-mediated downregulation of HL transcript levels occurs via an FXR-dependent mechanism. Finally, using transient transfection experiments, it is shown that FXR represses transcriptional activity of a reporter driven by the ؊ 698/ ؉ 13 bp human HL promoter. Taken together, these results identify HL as a new FXR-regulated gene in human liver cells. In view of the role of HL in plasma lipoprotein metabolism, our results further emphasize the central role of FXR in lipid homeostasis. -Sirvent, A., A. J. M. Verhoeven, H. Jansen, V. Kosykh, R. J. Darteil, D. W. Hum, J-C. Fruchart, and B. Staels. Farnesoid X receptor represses hepatic lipase gene expression. J. Lipid Res. 2004. 45: 2110-2115. Supplementary key words hepatocytes • small interfering ribonucleic acids • lipid metabolism Abbreviations: apoA-I, apolipoprotein A-I; BA, bile acid; BSEP, bile salt export pump; CDCA, chenodeoxycholic acid; FXR, farnesoid X receptor; FXRE, FXR response element; IR1, inverted repeat spaced by one nucleotide; SHP, small heterodimer partner; siRNA, small interfering RNA.
doi:10.1194/jlr.m400221-jlr200 pmid:15342685 fatcat:vlmne75zrjcrrogzg7ukj4vrjq