Edited by Norma AllewellLiver receptor homolog 1 (NR5A2, LRH-1) is an orphan nuclear hormone receptor that regulates diverse biological processes, including metabolism, proliferation, and the resolution of endoplasmic reticulum stress. Although preclinical and cellular studies demonstrate that LRH-1 has great potential as a therapeutic target for metabolic diseases and cancer, development of LRH-1 modulators has been difficult. Recently, systematic modifications to one of the few known chemical scaffolds capable of activating LRH-1 failed to improve efficacy substantially. Moreover, mechanisms through which LRH-1 is activated by synthetic ligands are entirely unknown. Here, we use x-ray crystallography and other structural methods to explore conformational changes and receptor-ligand interactions associated with LRH-1 activation by a set of related agonists. Unlike phospholipid LRH-1 ligands, these agonists bind deep in the pocket and do not interact with residues near the mouth nor do they expand the pocket like phospholipids. Unexpectedly, two closely related agonists with similar efficacies (GSK8470 and RJW100) exhibit completely different binding modes. The dramatic repositioning is influenced by a differential ability to establish stable face-to-face --stacking with the LRH-1 residue His-390, as well as by a novel polar interaction mediated by the RJW100 hydroxyl group. The differing binding modes result in distinct mechanisms of action for the two agonists. Finally, we identify a network of conserved water molecules near the ligand-binding site that are important for activation by both agonists. This work reveals a previously unappreciated complexity associated with LRH-1 agonist development and offers insights into rational design strategies.Liver receptor homolog 1 (LRH-1; NR5A2) is a nuclear hormone receptor (NR) 3 that controls expression of a diverse set of genes important both in normal physiology and disease. In addition to a vital role during development (1, 2), LRH-1 regulates many genes related to metabolism, proliferation, and cell survival. In the liver, LRH-1 regulates bile acid biosynthesis (3) and reverse cholesterol transport (4, 5), affecting hepatic and circulating cholesterol levels. Glucose metabolism is also regulated by LRH-1 at several points, including GLUT-4-mediated transport (6) and glucose phosphorylation, the latter of which is essential for proper postprandial glucose sensing, flux through glycolysis and glycogenesis pathways, and de novo lipogenesis (7). LRH-1 is a key mediator of the cell stress response through control of genes involved in the hepatic acute phase response (8) and in the cytoprotective resolution of endoplasmic reticulum stress (9). Additionally, LRH-1 can be aberrantly overexpressed in certain cancers and can promote tumor growth through estrogen receptor and ␤-catenin signaling (10 -16).Considering the breadth and significance of these physiological effects, LRH-1 modulators are highly desired as potential therapeutic agents. Chemical modulators would al...

As a key regulator of metabolism and inflammation, the orphan nuclear hormone receptor, Liver Receptor Homolog-1 (LRH-1), has potential as a therapeutic target for diabetes, nonalcoholic fatty liver disease, and inflammatory bowel diseases. Discovery of LRH-1 modulators has been difficult, in part due to the tendency for synthetic compounds to bind unpredictably within the lipophilic binding pocket. Using a structure-guided approach, we exploited a newly-discovered polar interaction to lock agonists in a consistent orientation. This enabled the discovery of the first low nanomolar LRH-1 agonist, one hundred times more potent than the best previous modulator. We elucidate a novel mechanism of action that relies upon specific polar interactions deep in the LRH-1 binding pocket. In an organoid model of inflammatory bowel disease, the new agonist increases expression of LRH-1-conrolled steroidogenic genes and promotes anti-inflammatory gene expression changes. These studies constitute major progress in developing LRH-1 modulators with potential clinical utility. glucose metabolism suggests therapeutic potential for LRH-1 agonists in metabolic diseases such as nonalcoholic fatty liver disease, type II diabetes, and cardiovascular disease. Indeed, the phospholipid LRH-1 agonist dilauroylphosphatidylcholine (DLPC; PC 12:0/12:0) improves glucose tolerance, insulin sensitivity, and triglyceride levels in obese mice 6 . These anti-diabetic effects occur in an LRH-1-dependent manner and have been primarily attributed to a reduction of de novo lipogenesis 6 . In addition, targeting LRH-1 in the gut has therapeutic potential for inflammatory bowel disease, where LRH-1 overexpression ameliorates disease-associated inflammation and cell death 10 .While small molecule LRH-1 modulators are highly sought, the large and lipophilic LRH-1 binding pocket has been extremely challenging to target. A promising class of agonists developed by Whitby and colleagues features a bicyclic hexahydropentalene core scaffold [11][12] . The beststudied of this class, named RJW100, was discovered as a part of an extensive synthetic effort to improve acid stability and efficacy of a related compound, GSK8470 12 (Figure 1A). We recently determined the crystal structure of LRH-1 bound to RJW100 and made a surprising discovery: it exhibits a completely different binding mode than GSK8470, such that the bicyclic cores of the two agonists are perpendicular to each other (Figure 1A) 13 . As a result, the two compounds use different mechanisms to activate LRH-1 but exhibit similar activation profiles in luciferase reporter assays 13 . A tendency for ligands in this class to bind unpredictably in the hydrophobic pocket has likely been a confounding factor in agonist design; however, insights from the LRH-1-RJW100 structure have provided new strategies to improve activity.In the LRH-1-RJW100 crystal structure, the ligand hydroxyl group contacts a network of water molecules deep in the ligand binding pocket (Figure 1B). This water network coordinates a

A photocatalytic system for the dearomative hydroarylation of benzene derivatives has been developed. Using a combination of an organic photoredox catalyst and an amine reductant, this process operates through a reductive radical-polar crossover mechanism where aryl halide reduction triggers a regioselective radical cyclization event, followed by anion formation and quenching to produce a range of complex spirocyclic cyclohexadienes. This light-driven protocol functions at room temperature in a green solvent system (aq. MeCN) without the need for precious metal-based catalysts or reagents or the generation of stoichiometric metal byproducts.

The orphan nuclear receptor Liver Receptor Homologue-1 (LRH-1) is an emerging drug target for metabolic disorders. The most effective known LRH-1 modulators are phospholipids or synthetic hexahydropentalene compounds. While both classes have micromolar efficacy, they target different portions of the ligand binding pocket and activate LRH-1 through different mechanisms. Guided by crystallographic data, we combined aspects of both ligand classes into a single scaffold, resulting in the most potent and efficacious LRH-1 agonists to date.

As a key regulator of metabolism and inflammation, the orphan nuclear hormone receptor, Liver Receptor Homolog-1 (LRH-1), has potential as a therapeutic target for diabetes, nonalcoholic fatty liver disease, and inflammatory bowel diseases. Discovery of LRH-1 modulators has been difficult, in part due to the tendency for synthetic compounds to bind unpredictably within the lipophilic binding pocket. Using a structure-guided approach, we exploited a newly-discovered polar interaction to lock agonists in a consistent orientation. This enabled the discovery of the first low nanomolar LRH-1 agonist, one hundred times more potent than the best previous modulator. We elucidate a novel mechanism of action that relies upon specific polar interactions deep in the LRH-1 binding pocket. In an organoid model of inflammatory bowel disease, the new agonist increases expression of LRH-1-conrolled steroidogenic genes and promotes anti-inflammatory gene expression changes. These studies constitute major progress in developing LRH-1 modulators with potential clinical utility.de novo lipogenesis 6 . In addition, targeting LRH-1 in the gut has therapeutic potential for inflammatory bowel disease, where LRH-1 overexpression ameliorates disease-associated inflammation and cell death 10 .While small molecule LRH-1 modulators are highly sought, the large and lipophilic LRH-1 binding pocket has been extremely challenging to target. A promising class of agonists developed by Whitby and colleagues features a bicyclic hexahydropentalene core scaffold 11-12 . The beststudied of this class, named RJW100, was discovered as a part of an extensive synthetic effort to improve acid stability and efficacy of a related compound, GSK8470 12 ( Figure 1A). We recently determined the crystal structure of LRH-1 bound to RJW100 and made a surprising discovery: it exhibits a completely different binding mode than GSK8470, such that the bicyclic cores of the two agonists are perpendicular to each other ( Figure 1A) 13 . As a result, the two compounds use different mechanisms to activate LRH-1 but exhibit similar activation profiles in luciferase reporter assays 13 . A tendency for ligands in this class to bind unpredictably in the hydrophobic pocket has likely been a confounding factor in agonist design; however, insights from the LRH-1-RJW100 structure have provided new strategies to improve activity.In the LRH-1-RJW100 crystal structure, the ligand hydroxyl group contacts a network of water molecules deep in the ligand binding pocket ( Figure 1B). This water network coordinates a small group of polar residues (e.g. Thr352, His390, and Arg393) in an otherwise predominantly hydrophobic pocket. The endo RJW100 diastereomer adopts a nearly identical pose and makes the same water-mediated contact with Thr352, supporting the idea that this interaction is a primary driver of ligand orientation 13 . Using both a RJW100 analog lacking a hydroxyl group and a LRH-1 Thr352Val mutation, we demonstrated that this interaction is required for RJW100-mediated activation o...