Disulfide-Trapping Identifies a New, Effective Chemical Probe for Activating the Nuclear Receptor Human LRH-1 (NR5A2)

Area of Science:

• Biochemistry
• Molecular Biology
• Drug Discovery

Background:

• Conventional screening methods struggle to find effective chemical probes for human nuclear receptors.
• Human liver receptor homolog 1 (hLRH-1, NR5A2) has a large ligand-binding pocket but existing ligands have limitations like poor solubility and off-target effects.

Purpose of the Study:

• To explore disulfide-trapping as a novel approach for identifying lead compounds targeting hLRH-1.
• To develop potent and specific activators of hLRH-1.

Main Methods:

• Disulfide-trapping identified a lead compound that conjugated to hLRH-1's Cys346.
• Computational modeling and cellular assays guided lead optimization into PME8 and PME9.
• hLRH-1 activity was assessed by measuring CYP24A1 gene induction in HepG2 cells.

Main Results:

• A lead compound was identified via disulfide-trapping, forming a conjugate with hLRH-1.
• Optimized ligands PME8 and PME9 bind hLRH-1 reversibly and activate its function.
• PME8 and PME9 demonstrated comparable induction of the hLRH-1 target gene CYP24A1 as existing agonist RJW100.
• Specificity was confirmed by siRNA-mediated knockdown of hLRH-1, which abolished PME8 and PME9 efficacy.

Conclusions:

• PME8 and PME9 are potent, specific activators of hLRH-1.
• Disulfide-trapping is a viable strategy for discovering nuclear receptor modulators.
• This lead series holds promise for developing in vivo chemical probes for hLRH-1 manipulation.