Nuclear receptors and microRNA-144 coordinately regulate cholesterol efflux.

Abstract

The ATP-binding cassette transporter A1 (ABCA1) is a key mediator of cellular cholesterol efflux and HDL maturation. <i>ABCA1</i> mRNA has an unusually long 3’ untranslated region, which makes it highly susceptible to microRNA (miRNA) targeting and repression. As such, multiple miRNAs have been reported to directly target ABCA1, including miR-33a/b, miR-26, miR-106b, and miR-758. Many of these miRNAs participate in feed-forward or feedback networks in controlling cholesterol and lipid homeostasis. Antisense oligonucleotide-based inhibition of miR-33 was found to increase HDL-C levels and regress atherosclerosis in mice and non-human primates. In this edition of <i>Circulation Research</i>, two separate studies identified novel miRNA networks driven by nuclear receptor induced miR-144 targeting of ABCA1 and cholesterol efflux. The first study reports that miR-144 serves to buffer uncontrolled ABCA1 activation in response to high cholesterol states and liver X receptor (LXR) activation in macrophages and liver. The second study highlights the role of miR-144 and ABCA1 in promotion of bile acid secretion in response to farensoid X receptor (FXR) activation in the liver. These studies suggest that anti-miR-144, like anti-miR-33, could be a novel approach to targeting HDL and reverse cholesterol transport.