Integrative Physiology Redox Regulation of Soluble Epoxide Hydrolase by 15-Deoxy- -Prostaglandin J2 Controls Coronary Hypoxic Vasodilation

Rationale: 15-Deoxy-prostaglandin (15d-PG)J2 is an electrophilic oxidant that dilates the coronary vasculature. This lipid can adduct to redox active protein thiols to induce oxidative posttranslational modifications that modulate protein and tissue function. Objective: To investigate the role of oxidative protein modifications in 15d-PGJ2–mediated coronary vasodilation and define the distal signaling pathways leading to enhanced perfusion. Methods and Results: Proteomic screening with biotinylated 15d-PGJ2 identified novel vascular targets to which it adducts, most notably soluble epoxide hydrolase (sEH). 15d-PGJ2 inhibited sEH by specifically adducting to a highly conserved thiol (Cys521) adjacent to the catalytic center of the hydrolase. Indeed a Cys521Ser sEH “redox-dead” mutant was resistant to 15d-PGJ2–induced hydrolase inhibition. 15d-PGJ2 dilated coronary vessels and a role for hydrolase inhibition was supported by 2 structurally different sEH antagonists each independently inducing vasorelaxation. Furthermore, 15d-PGJ2 and sEH antagonists also increased coronary effluent epoxyeicosatrienoic acids consistent with their vasodilatory actions. Indeed 14,15-EET alone induced relaxation and 15d-PGJ2–mediated vasodilation was blocked by the EET receptor antagonist 14,15epoxyeicosa-5(Z)-enoic acid (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 to hypoxia in wild-types was accompanied by 15d-PGJ2 adduction to and inhibition of sEH. Consistent with the importance of hydrolase inhibition, sEH-null mice failed to vasodilate during hypoxia. Conclusion: 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. (Circ Res. 2011;108:324-334.)