Structure-based screening and a conformational biosensor identify a GPR183 inverse agonist and an activation switch

Area of Science:

• Pharmacology
• Immunology
• Biochemistry

Background:

• G protein-coupled receptor 183 (GPR183) is a key regulator of immune cell migration.
• Dysregulation of GPR183 signaling is implicated in inflammatory, autoimmune, and oncological diseases.

Purpose of the Study:

• To identify novel inverse agonists targeting GPR183.
• To elucidate the molecular mechanisms of GPR183 activation and signaling.
• To evaluate the therapeutic potential of identified inhibitors in immune cell migration.

Main Methods:

• AI-driven virtual screening and biophysical assays for compound identification.
• Biochemical assays to assess Gi signaling and β-arrestin2 recruitment.
• Molecular dynamics simulations, mutagenesis, and conformational biosensors for structural analysis.
• Ex vivo assays using peripheral blood mononuclear cells to evaluate cell migration inhibition.

Main Results:

• Compound 78 identified as a potent inverse agonist, inhibiting constitutive and agonist-induced Gi signaling and β-arrestin2 recruitment.
• Structural studies confirmed compound 78 binds within the GPR183 receptor core.
• Compound 78 effectively blocked agonist-driven migration of peripheral blood mononuclear cells ex vivo.
• Tyrosine 260 (Y260^6.51) in transmembrane helix 6 identified as critical for GPR183 activation and compound 78 efficacy, revealing a switch mechanism.

Conclusions:

• Compound 78 represents a potent chemical scaffold for GPR183 inhibition.
• Understanding GPR183 activation mechanisms provides insights into receptor function.
• This study offers novel tools and therapeutic strategies for targeting GPR183 in various diseases.