Nuclear hormone receptors regulate diverse metabolic pathways and the orphan nuclear receptor LRH-1 (NR5A2) regulates bile acid biosynthesis1,2. Structural studies have identified phospholipids as potential LRH-1 ligands3–5, but their functional relevance is unclear. Here we show that an unusual phosphatidylcholine 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 signaling pathway that regulates bile acid metabolism and glucose homeostasis.

Mutations in several genes encoding transcription factors of the hepatocyte nuclear factor (HNF) cascade are associated with maturity-onset diabetes of the young (MODY), a monogenic form of early-onset diabetes mellitus. The ability of the orphan nuclear receptor small heterodimer partner (SHP, NR0B2) to modulate the transcriptional activity of MODY1 protein, the nuclear receptor HNF-4␣, suggested SHP as a candidate MODY gene. We screened 173 unrelated Japanese subjects with earlyonset diabetes for mutations in this gene and found five different mutations (H53fsdel10, L98fsdel9insAC, R34X, A195S, and R213C) in 6 subjects as well as one apparent polymorphism (R216H), all present in the heterozygous state. Interestingly, all of the subjects with the mutations were mildly or moderately obese at onset of diabetes, and analysis of the lineages of these individuals indicated that the SHP mutations were associated with obesity rather than with diabetes. Therefore, an additional group of 101 unrelated nondiabetic subjects with early-onset obesity was screened for mutations in the SHP gene. Two of the previously observed mutations (R34X and A195S) and two additional mutations (R57W and G189E) were identified in 6 subjects, whereas no mutations were identified in 116 young nondiabetic lean controls (P ‫؍‬ 0.0094). Functional studies of the mutant proteins show that the mutations result in the loss of SHP activity. These results suggest that genetic variation in the SHP gene contributes to increased body weight and reveal a pathway leading to this common metabolic disorder in Japanese.nuclear receptor ͉ maturity-onset diabetes of the young ͉ insulin secretion ͉ body weight ͉ hepatocyte nuclear factor H eterozygous mutations in genes encoding transcription factors in the hepatocyte nuclear factor (HNF) regulatory cascade (1) are associated with an early-onset autosomal dominant form of diabetes mellitus, maturity-onset diabetes of the young (MODY) (2). To date, diabetes-associated mutations have been found in three members of this regulatory network, HNF-1␣, -1␤, and -4␣ (MODY3, 5, and 1, respectively) (3-6). These forms of MODY are characterized primarily by defective insulin secretion with normal body weight (7-9). In contrast, forms of early-onset autosomal-dominant type 2 diabetes that are not linked to known MODY genes are often characterized by insulin resistance with high body weight, rather than by pure pancreatic ␤-cell defects (10). It is not known whether obesity-associated MODY genes or other common modifying factors are responsible for these phenotypic features.The protein small heterodimer partner (SHP; also called NROB2 for nuclear receptor subfamily 0, group B, member 2), an atypical orphan nuclear receptor that lacks a conventional DNA-binding domain, interacts with a number of other nuclear receptors, including HNF-4␣, and inhibits their transcriptional activity (11)(12)(13)(14)(15)(16)(17). SHP is expressed in the liver and has recently been suggested to regulate cholesterol homeostasis by an inhibitory e...