The liver X receptors (LXRα and LXRβ) are nuclear hormone receptors whose native ligands are oxysterols. LXRs regulate the oxysterol-induced expression of cholesterol 7α-hydroxylase, the rate limiting enzyme of classic bile acid synthesis. 22(R)-hydroxy Cholesterol is an endogenous agonist for LXRs that activates LXRα with an EC50 value of 325 nM. 22(R)-hydroxy Cholesterol, acting through LXR heterodimerized with the retinoid X receptor, induces the expression of the ABCA1 reverse cholesterol transporter. This activity increases the efflux of cholesterol from enterocytes and thus inhibits the overall absorption of cholesterol. 22(R)-hydroxy Cholesterol can be used as a substrate to monitor cholesterol transport or as an endogenous positive control for testing LXR agonists which have potential as therapeutic agents for the treatment of atherosclerosis.
