Role of Icosaniods in Renal Function

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The kidney plays a key role in the control of body fluid volume and composition, and tubular and/or hemodymic dysfunction are common features of diseases such as stroke, hypertension, and diabetes. The CYP P450 (P450) arachidonic acid (AA) monooxygenase, a member of the AA cascade, biosynthesizes several regioisomeric hydroxyand epoxy-AA derivatives capable of modulating renal hemodynamics, tubular transport, and renovascular reactivity in vitro. Cell and animal models of P450 gene-isoform specific phenotypes, including P450 knockout mice strains, have confirmed the functional importance of these enzymes, facilitated studies of their physiological roles, and provided insights into the mechanism of action of their metabolites. By building upon these and previous studies, this application proposes: a) an integrated molecular, biochemical, and functional approach to further characterize the physiological significance of the renal AA monooxygenase, and b) to initiate the analysis of its role in the pathophysiology of human disease. For these purposes, we will continue to utilize synthetic metabolites, isoform specific inhibitors, cloned cDNAs and/or genes, and recombinant DNA and molecular genetics approaches for the study of P450isoform specific phenotypes at the cellular, organ and whole animal levels. Functional studies will include: a) biochemical documentation of P450 isoform specific changes in cell, organ, or whole animal AA metabolism b) characterization of cellular phenotypes including hormonal responses, signaling mechanisms, and ion flux and channel effects, c) the identification and characterization of hemodynamic and/or tubular effects, and d) the use of mice strains carrying disrupted P450 genes for the integration of gene specific cell and/or organ phenotypes into whole animal physiology and/or pathophysiology. The human homologues of functionally relevant murine and/or rat P450s will be identified, cloned, expressed, and characterized. High throughput sequencing will be used to define potential associations between alterations in P450 gene structure/expression and the pathophysiology of diseases such as hypertension. Our long term goals are to provide a molecular understanding of role(s) of P450 eicosanoids in renal physi ological, their mechanism and site of action, and relevance to human disease. These are needed for the development of meaningful approaches for: a) the unequivocal definition of pathophysiological significance, and b) future pharmacological targeting, and clinical diagnosis and intervention.