Covalent drug discovery targeting G protein-coupled receptors

Abstract

G protein-coupled receptors (GPCRs) play pivotal roles in converting physicochemical stimuli due to environmental changes to intracellular responses. After ligand stimulation, many GPCRs are desensitized and then recycled or degraded through phosphorylation and β-arrestin-dependent internalization, an important process to maintain protein quality control of GPCRs. However, it is unknown how GPCRs with low β-arrestin sensitivity are controlled. Here we unmasked a β-arrestin-independent GPCR internalization, named Redox-dependent Alternative Internalization (REDAI), focusing on β-arrestin-resistant purinergic P2Y₆ receptor (P2Y₆R). P2Y₆R is highly expressed in macrophage and pathologically contributes to the development of colitis in mice. Natural electrophiles including in functional foods induce REDAI-mediated P2Y₆R degradation leading to anti-inflammation in macrophages. Prevention of Cys220 modification on P2Y₆R resulted in aggravation of the colitis. These results strongly suggest that targeting REDAI on GPCRs will be a breakthrough strategy for the prevention and treatment of inflammatory diseases.