Here we show that an unusual phosphatidyl-choline species with two saturated 12 carbon fatty acid acyl side chains (dilauroyl phosphatidylcholine

(DLPC)) is an LRH-1 agonist ligand in vitro. DLPC treatment induces bile acid biosynthetic enzymes in mouse liver, increases bile acid levels, and lowers hepatic triglycerides and serum glucose. DLPC treatment also decreases hepatic steatosis and improves glucose homeostasis in two mouse models of insulin resistance. Both the antidiabetic and lipotropic effects are lost in liver-specific Lrh-1 knockouts. These findings identify an LRH-1 dependent phosphatidylcholine signalling pathway that regulates bile acid metabolism and glucose Selleck DMXAA homeostasis. The orphan nuclear receptor liver receptor homolog-1 (LRH-1, NR5A2) is regarded as a central regulator of bile salt biosynthesis and bile salts are increasingly recognized as modulators

of glucose and lipid metabolism in mice and men. In their remarkable study, Lee et al.1 identified a ligand for LRH-1, dilauroyl phosphatidylcholine (DLPC), a C12:0/C12:0 phospholipid, which had potent effects on glucose, BIBW2992 lipid, and bile salt homeostasis in vivo. In a cell-free system, Lee et al. demonstrated by mass spectrometry that DLPC specifically binds to a recombinant LRH-1 ligand-binding domain. Agonism for LRH-1 could be confirmed in an elegant mammalian two-hybrid assay for DLPC and its sister-molecule diundecanoyl phosphatidylcholine (DUPC; C11:0/C11:0). On functional level, DLPC and even more DUPC were strong activators of both human and mouse LRH-1, whereas other nuclear receptors including FXR, CAR, PXR, PPARα and PPARγ were all unaffected in cell culture. DLPC and

DUPC induced transactivation of the native mouse Shp and Oct4 promoters, in line with previous studies on Lrh-1.2, 3 In the human hepatoma cell line HepG2, DLPC induced the expression of CYP8B1. When orally applied to wildtype mice, DLPC and DUPC induced the expression of hepatic Cyp7a1, Cyp8b1, and Sr-b1 but repressed Shp, leading to a modest increase in serum bile salts and total bile salt pool. These findings were consistent with previous observations in 上海皓元医药股份有限公司 liver-specific Lrh-1 knockouts.4 More strikingly, DUPC- and DLPC-treated mice showed significantly decreased serum glucose, serum nonesterified fatty acids (NEFAs), and hepatic triglycerides. The effects of DLPC were lost in LRH-1 floxed (Lrh-1f/f) mice after administration of adenoviral Cre (Ad-Cre) vector, deleting LRH-1. Comparative oral administration of cholate (100 mg/kg body weight twice daily) improved serum NEFAs and hepatic triglycerides to a similar degree, but did not affect serum glucose. The surprising effects of DLPC on glucose metabolism were further investigated in a diabetic model, utilizing insulin-resistant leptin receptor deficient db/db mice. DLPC improved glucose homeostasis, as assessed by serum insulin, glucose tolerance test (GTT), and insulin tolerance test (ITT).