Abstract 19249: Redox Regulation of Soluble Epoxide Hydrolase by 15-Deoxy-Prostaglandin J2 Controls Coronary Hypoxic Vasodilation
A fundamental mechanism of redox signalling is the post-translational oxidative modification of proteins, which allows alterations in cellular redox to be integrated into coordinated homeostatic responses. Here we show the important cardiovascular drug target soluble epoxide hydrolase (sEH), is covalently modified and inhibited by the lipid signalling molecule 15-deoxy-Δ 12,14-prostaglandin J2 (15d-PGJ2). Using proteomics we found 15d-PGJ2 adducted specifically to a highly conserved thiol (Cys521), which is directly proximal to the catalytic centre of the hydrolase, providing a rational structural basis for inhibition. A Cys521Ser sEH ‘redox-dead’ mutant transfected into HEK or HUVEC cells was not inhibited by 15d-PGJ2 corroborating its importance in the redox control of hydrolase activity. 15d-PGJ2 dilated coronary vessels and this was not blocked by the PPAR gamma inhibitor GW9662. A role for hydrolase inhibition was supported by sEH antagonists (AUDA or t-AUCB) independently inducing vasorelaxation and a EET receptor antagonist (14,15-EEZE) blocked the vasodilation induced by 15d-PGJ2. Furthermore, 15d-PGJ2 and sEH antagonists also increased coronary effluent epoxyeicosatrienoic acids (EETs, measured by LC-MS) consistent with their vasodilatory actions. Indeed 14,15 EET alone induced relaxation and 15d-PGJ2-mediated vasodilation was blocked by the EET receptor antagonist 14,15-EEZE. Additionally the coronary vasculature of sEH null mice was basally dilated compared to wild-type controls and failed to vasodilate in response to 15d-PGJ2. Coronary vasodilation in response to hypoxia was markedly attenuated in sEH null mice, consistent with increased 15d-PGJ2 adduct formation and sEH inhibition at this time. This represents a new paradigm for the regulation of sEH by an endogenous lipid, which is integral to the fundamental physiological response of coronary hypoxic vasodilation. sEH inhibitors are also known to provide integrated cardiovascular protection against hypertension, ischemia and reperfusion, hypertrophy, and heart failure. 15d-PGJ2 is also broadly protective and this is likely significantly mediated by it being an endogenous inhibitory ligand of sEH as we have shown here.
- © 2010 by American Heart Association, Inc.