title: Retinoid regulated macrophage cholesterol efflux involves the steroidogenic acute regulatory protein.
abstract: Elimination of excess cholesteryl esters from macrophage-derived foam cells is known to be a key process in limiting plaque stability and progression of atherosclerotic lesions. We have recently demonstrated that regulation of retinoid mediated cholesterol efflux is influenced by liver X receptor (LXR) signaling in mouse macrophages (Manna, P.R. et al., 2015, Biochem. Biophys. Res. Commun., 464:312-317). The data presented in this article evaluate the importance of the steroidogenic acute regulatory protein (StAR) in retinoid mediated macrophage cholesterol efflux. Overexpression of StAR in mouse RAW 264.7 macrophages increased the effects of both all-trans retinoic acid (atRA) and 9-cis RA on cholesterol efflux, suggesting StAR enhances the efficacy of retinoic acid receptor (RAR) and/or retinoid X receptor (RXR) ligands. Additional data revealed that atRA enhances (Bu)2cAMP induced StAR and ATP-binding cassette transporter A1 protein levels. Treatment of macrophages transfected with an LXRE reporter plasmid (pLXREx3-Luc) was found to induce the effects of RAR and RXR analogs on LXR activity.
authors.affiliation: Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, School of Medicine, Lubbock, TX 79430, USA.
authors.forename: Pulak R
authors.initials: PR
authors.lastname: Manna
keywords: (Bu)2cAMP, dibutyryl cAMP, RAR, retinoic acid receptor; ABCA1; ABCA1, ATP-binding cassette transporter A1; Apo-A1, apolipoprotein A1; Cholesterol efflux; LXR, liver X receptor; Macrophages; RAR; RXR; RXR, retinoid X receptor; Retinoids; SREBP-1c, sterol regulatory element-binding protein 1c; StAR; StAR, steroidogenic acute regulatory protein; atRA, all-trans RA; retinoids, retinoic acid (RA) and its derivatives