Abstract 112: The 20-HETE Receptor: a New Player in Hypertension

Abstract

Here, we report that GPR75, a G protein-coupled receptor of the Gq rhodopsin subfamily, selectively binds 20-hydroxyeicosatetraenoic acid (20-HETE), a cytochrome P450-derived bioactive arachidonic acid metabolite implicated in the pathogenesis of hypertension and cardiovascular diseases. In endothelial cells, 20-HETE binding to GPR75 stimulates β-arrestin recruitment and GIT1-GPR75 association, which further facilitates a c-Src-mediated transactivation of EGFR. This results in downstream signaling pathways which induce ACE expression and decrease NO bioavailability. Knockdown of GPR75 prevents 20-HETE-mediated downstream effects in endothelial cells including EGFR activation and ACE induction. In vascular smooth muscle cells, GPR75-20-HETE pairing is associated with Gα q/11 -and GIT1-mediated PKC-stimulated phosphorylation of MaxiKβ, linking GPR75 activation to 20-HETE-mediated vasoconstriction. We used the conditional Cyp4a12tg mice, which display doxycycline (DOX)-mediated hypertension along with vascular dysfunction and remodeling in a 20-HETE-dependent manner, to assess whether GPR75 is a necessary component of 20-HETE pro-hypertensive actions. Administration of GPR75-targeted shRNA lentiviral particles to DOX-treated Cyp4a12tg mice, which resulted in 80% knockdown of GPR75 knockdown, prevented blood pressure elevation (100±3 vs 135±2 mmHg) and 20-HETE-mediated increases in ACE expression, endothelial dysfunction, smooth muscle contractility and vascular remodeling when compared to DOX-treated Cyp4a12tg mice receiving non-targeted shRNA. The discovery of 20-HETE-GPR75 pairing provides the molecular basis for the signaling and pathophysiological bioactions mediated by 20-HETE in hypertension. These results clearly place GPR75 as a novel target in the control of blood pressure and vascular function.