A Tyrosine Switch on NEDD4-2 E3 Ligase Transmits GPCR Inflammatory Signaling

Abstract

Summary: Ubiquitination is essential for protein degradation and signaling and pivotal to many physiological processes. Ubiquitination of a subset of G-protein-coupled receptors (GPCRs) by the E3 ligase NEDD4-2 is required for p38 activation, but how GPCRs activate NEDD4-2 to promote ubiquitin-mediated signaling is not known. Here, we report that the GPCR protease-activated receptor-1 (PAR1) stimulates c-Src-mediated tyrosine phosphorylation and activation of NEDD4-2 to promote p38 signaling and endothelial barrier disruption. Using mass spectrometry, we identified a unique phosphorylated tyrosine (Y)-485 within the 2,3-linker peptide between WW domain 2 and 3 of NEDD4-2 in agonist-stimulated cells. Mutation of NEDD4-2 Y485 impaired E3 ligase activity and failed to rescue PAR1-stimulated p38 activation and endothelial barrier permeability. The purinergic P2Y1 receptor also required c-Src and NEDD4-2 tyrosine phosphorylation for p38 activation. These studies reveal a novel role for c-Src in GPCR-induced NEDD4-2 activation, which is critical for driving ubiquitin-mediated p38 inflammatory signaling. : Grimsey et al. report that GPCRs stimulate activation of NEDD4-2 E3 ubiquitin ligase via c-Src to induce endothelial p38 inflammatory signaling. c-Src phosphorylates NEDD4-2 at tyrosine-485, releasing the auto-inhibitory linker peptide that is critical for enhancing E3 ligase activity, and provides mechanistic insight of how GPCRs activate E3 ubiquitin ligases. Keywords: HECT, NEDD4, GPCR, c-Src, thrombin, protease-activated receptor, ubiquitin, endothelial barrier permeability, p38 MAPK