HDX-MS reveals structural determinants for RORγ hyperactivation by synthetic agonists.

Area of Science:

• Molecular Biology
• Biochemistry
• Structural Biology

Background:

• Nuclear receptors (NRs) are crucial regulators of physiological and pathophysiological processes.
• Many NRs are
• orphan NRs
• lacking known ligands, hindering the understanding of their functions.
• Targeting NRs with small molecules is a key therapeutic strategy.

Purpose of the Study:

• To investigate the ligand-dependent activity of the orphan nuclear receptor RORγ (Retinoid-related Orphan Receptor gamma).
• To elucidate the structural determinants of RORγ activation for potential therapeutic applications in cancer immunotherapy.

Main Methods:

• Selective disruption of putative endogenous ligand binding to RORγ.
• Characterization of RORγ modulators using a library of compounds.
• Assessment of receptor structural dynamics via Hydrogen-Deuterium Exchange Mass Spectrometry (HDX-MS).
• X-ray co-crystallography and site-directed mutagenesis.

Main Results:

• Demonstrated ligand-dependent action of orphan RORγ by disrupting endogenous ligand binding.
• Correlated structural dynamics (HDX-MS) with RORγ activity in biochemical and cell-based assays.
• Identified structural determinants of RORγ activation through integrated structural biology techniques.

Conclusions:

• The orphan RORγ exhibits ligand-dependent activity, which can be modulated.
• Understanding RORγ structural dynamics is key to its functional modulation.
• These findings provide a foundation for designing RORγ agonists for cancer immunotherapy.