P450 enzymes metabolize not only exogenous chemicals but also participate in the disposition of key endogenous compounds, including fatty acids, prostaglandins, and leukotrienes. P450- mediated oxidation of these lipid-derived endobiotics gives rise, at least in animals, to products with potent biological effects, including vasoactivity and ion transport inhibition, or can result in their inactivation, as noted with prostanoids and proinflammatory leukotrienes. To that end, we will continue our characterization of two hepatic CYP4 gene family enzymes, namely CYP4A11 and CYP4F2, that we have isolated from human liver, and have thus far shown to be the principle catalysts of arachidonate metabolism to 20-HETE, a potent vasoconstrictor and Na+K+-ATPase inhibitor. Initially, we will examine the capacity of these P450s to omega-hydroxylate other long-chain fatty acids such as palmitate and stearate to products with potential physiological impact, and to oxidize prostaglandins A1 and E1 as well as leukotrienes B4 and E4, thereby inactivating these potent mediators of signal transduction processes. Immunochemical studies will be utilized to: a) reveal if CYP4A11 and/or CYP4F2 catalyze these same reactions in intact liver and kidney tissue; b) assess the distribution of these P450s within the hepatic acinus and kidney nephron and; c) to determine if the interindividual variations noted in fatty acid and eicosanoid metabolism by these tissues stem from differences in CYP4 enzyme levels. Cultures of human hepatocytes will then be employed to assess if therapeutic hypolipidemic agents that are capable of altering fatty acid homeostasis, such as clofibrate and gemfibrozil, are also capable of increasing CYP4A11 and/or CYP4F2 expression, and if ethanol, which increases lipid deposition in liver, induces these CYP4 proteins as it does CYP2E1.
Our aims are to define the role of human CYP4A11 and CYP4F2 in metabolism of important endogeous fatty acids and signal transduction agents in both liver and kidney, and to reveal if variations in endobiotic metabolism by the CYP4 enzymes can indeed perturb normal physiological processes, including the regulation of renal function, the control of inflammation, and cellular lipid flux.
|Savas, Uzen; Machemer, Daniel E W; Hsu, Mei-Hui et al. (2009) Opposing roles of peroxisome proliferator-activated receptor alpha and growth hormone in the regulation of CYP4A11 expression in a transgenic mouse model. J Biol Chem 284:16541-52|
|Hirani, Vandana; Yarovoy, Anton; Kozeska, Anita et al. (2008) Expression of CYP4F2 in human liver and kidney: assessment using targeted peptide antibodies. Arch Biochem Biophys 478:59-68|
|Dhar, Madhurima; Sepkovic, Daniel W; Hirani, Vandana et al. (2008) Omega oxidation of 3-hydroxy fatty acids by the human CYP4F gene subfamily enzyme CYP4F11. J Lipid Res 49:612-24|
|Raucy, Judy L; Lasker, Jerome; Ozaki, Kazuaki et al. (2004) Regulation of CYP2E1 by ethanol and palmitic acid and CYP4A11 by clofibrate in primary cultures of human hepatocytes. Toxicol Sci 79:233-41|
|Hirani, Vandana N; Raucy, Judy L; Lasker, Jerome M (2004) Conversion of the HIV protease inhibitor nelfinavir to a bioactive metabolite by human liver CYP2C19. Drug Metab Dispos 32:1462-7|
|Raucy, Judy L; Mueller, Lisa; Duan, Kui et al. (2002) Expression and induction of CYP2C P450 enzymes in primary cultures of human hepatocytes. J Pharmacol Exp Ther 302:475-82|
|Lasker, J M; Chen, W B; Wolf, I et al. (2000) Formation of 20-hydroxyeicosatetraenoic acid, a vasoactive and natriuretic eicosanoid, in human kidney. Role of Cyp4F2 and Cyp4A11. J Biol Chem 275:4118-26|
|Cummings, B S; Lasker, J M; Lash, L H (2000) Expression of glutathione-dependent enzymes and cytochrome P450s in freshly isolated and primary cultures of proximal tubular cells from human kidney. J Pharmacol Exp Ther 293:677-85|
|Wester, M R; Lasker, J M; Johnson, E F et al. (2000) CYP2C19 participates in tolbutamide hydroxylation by human liver microsomes. Drug Metab Dispos 28:354-9|
|Pan-Zhou, X R; Cretton-Scott, E; Zhou, X J et al. (1998) Role of human liver P450s and cytochrome b5 in the reductive metabolism of 3'-azido-3'-deoxythymidine (AZT) to 3'-amino-3'-deoxythymidine. Biochem Pharmacol 55:757-66|
Showing the most recent 10 out of 26 publications