title: Intestinal pregnane X receptor links xenobiotic exposure and hypercholesterolemia.
abstract: Recent studies have associated endocrine-disrupting chemical (EDC) exposure with the increased risk of cardiovascular disease in humans, but the underlying mechanisms responsible for these associations remain elusive. Many EDCs have been implicated in activation of the nuclear receptor pregnane X receptor (PXR), which acts as a xenobiotic sensor to regulate xenobiotic metabolism in the liver and intestine. Here we report an important role of intestinal PXR in linking xenobiotic exposure and hyperlipidemia. We identified tributyl citrate (TBC), one of a large group of Food and Drug Administration-approved plasticizers for pharmaceutical or food applications, as a potent and selective PXR agonist. TBC efficiently activated PXR and induced PXR target gene expression in vitro and in vivo. Interestingly, TBC activated intestinal PXR but did not affect hepatic PXR activity. Exposure to TBC increased plasma total cholesterol and atherogenic low-density lipoprotein cholesterol levels in wild-type mice, but not in PXR-deficient mice. TBC-mediated PXR activation stimulated the expression of an essential cholesterol transporter, Niemann-Pick C1-like 1 (NPC1L1), in the intestine. Promoter analysis revealed a DR-4 type of PXR response element in the human NPC1L1 promoter, and TBC promoted PXR recruitment onto the NPC1L1 promoter. Consistently, TBC treatment significantly increased lipid uptake by human and murine intestinal cells and deficiency of PXR inhibited TBC-elicited lipid uptake. These findings provide critical mechanistic insight for understanding the impact of EDC-mediated PXR activation on lipid homeostasis and demonstrate a potential role of PXR in mediating the adverse effects of EDCs on cardiovascular disease risk in humans.
authors: Department of Pharmacology and Nutritional Sciences (Y.S., R.N.H., S.-H.P., X.S., Z.L., C.Z.) and Saha Cardiovascular Research Center (C.Z.), University of Kentucky, Lexington, Kentucky 40506.
authors: Yipeng
authors: Y
authors: Sui
authors: Robert N
authors: RN
authors: Helsley
authors: Se-Hyung
authors: SH
authors: Park
authors: Xiulong
authors: X
authors: Song
authors: Zun
authors: Z
authors: Liu
authors: Changcheng
authors: C
authors: Zhou
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000378:metabolism; D002951:Citrates / Q000633:toxicity*; D052244:Endocrine Disruptors / Q000633:toxicity*; D056945:Hep G2 Cells; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000139:chemically induced; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects; D008297:Male; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D010795:Phthalic Acids / Q000633:toxicity*; D010968:Plasticizers / Q000633:toxicity*; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D015262:Xenobiotics
chemical_list: D002951:Citrates; D052244:Endocrine Disruptors; D026901:Membrane Transport Proteins; C482445:Npc1l1 protein, mouse; D010795:Phthalic Acids; D010968:Plasticizers; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid; D015262:Xenobiotics; C039783:tributyl citrate; D002784:Cholesterol