Role of 20-HETE in Endothelial Dysfunction

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This is a proposal to investigate the function and regulation of 20-hydroxyeicosatetraenoic acid (20- HETE) synthesis in the vasculature, more specifically, its participation in endothelium dysfunction in models of increased vascular expression of cytochrome P450 (CYP) 4A. 20-HETE is a primary eicosanoid in the microcirculation where it participates in the regulation of vascular tone. In rat renal arteries, CYP4A expression and 20-HETE production increased with decreased arterial diameter. CYP4A overexpression in small arteries and arterioles increased vascular reactivity and myogenic tone. Recent studies and preliminary results suggest that the endothelium is a target for 20-HETE bioactions. Smooth muscle-specific CYP4A1 expression via Ad-SM22-4A1 induces a marked CYP4A-dependent and 20-HETE-mediated endothelial sprouting in renal arterial microvessels. In vitro, 20-HETE is a potent angiogenic factor stimulating capillary-like tube formation of endothelial cells by a mechanism that may include MAPK activation and induction of inflammatory and angiogenic proteins (IL-8 and VEGF). In vivo, intravenous injection of Adv-CYP4A2 causes hypertension and renal arteries from these rats display endothelial dysfunction, which can be reversed by inhibition of CYP4A activity. Arteries from Adv-CYP4A2-transduced rats produce more 20-HETE and less NO; they also express higher levels of inflammatory proteins (ICAM and VCAM). These findings raise the possibility that vascular 20-HETE is an important determinant of endothelial dysfunction, a condition that is characterized by decreased NO bioavailability and enhanced endothelial activation, and are the basis for the proposal's hypothesis: Vascular overexpression of CYP4A fosters prohypertensive mechanisms via increased production of 20-HETE in a manner that may include endothelial dysfunction and activation. This hypothesis will be tested by 1) determining the relationship between hypertension, endothelial dysfunction and activation, CYP4A expression and 20-HETE synthesis; 2) determining whether the functional consequences of increased vascular expression of CYP4A is associated with endothelial expression and synthesis of CYP4A and 20-HETE, respectively; and 3) exploring mechanisms underlying 20-HETE mediated endothelial dysfunction and activation.