Liver X receptors, lipids and their reproductive secrets in the male

Liver X receptor (LXR) alpha and LXR beta belong to the nuclear receptor superfamily. For many years, they have been called orphan receptors, as no natural ligand was identified. In the last decade, the LXR natural ligands have been shown to be oxysterols, molecules derived from cholesterol. While these nuclear receptors have been abundantly studied for their roles in the regulation of lipid metabolism, it appears that they also present crucial activities in reproductive organs such as testis and epididymis, as well as prostate. Phenotypic analyses of mice lacking LXRs (lxr-/-) pointed out their physiological activities in the various cells and organs regulating reproductive functions. This review summarizes the impact of LXR-deficiency in male reproduction, highlighting the novel information coming from the phenotypic analyses of lxr alpha-/-, lxr beta-/- and lxr alpha;lxr beta-/- mice. This article is part of a Special Issue entitled: Translating nuclear receptor from health to disease. (C) 2011 Elsevier B.V. All rights reserved.