Uniting features from strongly activating small molecules to develop chimeric LRH‐1 agonist

Nuclear receptors are transcription factors that respond to external lipophilic signaling molecules to alter target gene expression. Liver receptor homolog‐1 (LRH‐1) is a nuclear receptor that operates as a master metabolic regulator in the liver, making it an attractive target for treating a variety of diseases characterized by dysregulated glucose and lipid homeostasis. Phospholipids (PLs) represent the putative endogenous ligands for LRH‐1, but their insolubility, rapid turnover, and poor potency have made synthetic agonists more attractive tools for targeting this receptor. With structural data that defined the binding pose of the first class of synthetic LRH‐1 agonists, we designed and characterized small molecules with enhanced solubility, potency, and efficacy. This work led to a compound (“6N”) that binds hydrophilic residues deep within the binding pocket, exhibiting nanomolar potency. We have also targeted residues contacted by the headgroups of activating PLs as a complementary strategy for activation. These modifications resulted in our most efficacious small molecule (“10CA”). To capture the characteristics of both compounds, we have synthesized a chimeric small molecule that includes the key moieties of 6N and 10CA responsible for high affinity and efficacy, respectively. Excitingly, this new hybrid compound exhibits the highest affinity, potency, and effect on receptor thermal stability. While the hybrid activates LRH‐1 to an equivalent level as 10CA in reporter assays, it elicits LRH‐1 target gene expression to a greater degree than either 6N or 10CA alone. Interestingly, RNA‐seq studies have revealed that the hybrid compound captures a PL‐mediated gene expression response more effectively that either 6N or 10CA alone. Further crystallography and molecular dynamics studies reveal that these characteristics are the result of the hybrid compound engaging with, and communicating from, both sites of agonist binding. Altogether, our studies demonstrate the differences between our leading agonists and suggest that the hybrid molecule is our most effective agonist to date, providing a critical tool for both studying LRH‐1 biology and treating a range of metabolic disorders.