Human CYP4F3s are the main catalysts in the oxidation of fatty acid epoxides

• Published in: Journal of lipid research Vol. 45; no. 8; pp. 1446 - 1458
• Main Authors: Le Quéré, Valérie, Plée-Gautier, Emmanuelle, Potin, Philippe, Madec, Stéphanie, Salaün, Jean-Pierre
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2004; Elsevier
• Subjects: Adult; Arachidonic Acid - metabolism; Cytochrome P-450 Enzyme System - genetics; Cytochrome P-450 Enzyme System - metabolism; cytochrome P450; Cytochrome P450 Family 4; Epoxy Compounds - metabolism; epoxyeicosatrienoic acid; Exotoxins - metabolism; Fatty Acids - metabolism; Female; Humans; hydroxylation; leukotoxin; liver; Male; microsomes; Microsomes, Liver - enzymology; Microsomes, Liver - metabolism; oxylipin; recombinant cytochrome P450; Stearic Acids - metabolism; leukotoxin; oxylipin; epoxyeicosatrienoic acid; liver; hydroxylation; recombinant cytochrome P450; cytochrome P450; microsomes
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1194/jlr.M300463-JLR200

CYP4F isoforms are involved in the oxidation of important cellular mediators such as leukotriene B4 (LTB4) and prostaglandins. The proinflammatory agent LTB4 and cytotoxic leukotoxins have been associated with several inflammatory diseases. We present evidence that the hydroxylation of Z 9(10)-epoxyoctadecanoic, Z 9(10)-epoxyoctadec-Z 12-enoic, and Z 12(13)-epoxyoctadec-Z 9-enoic acids and that of monoepoxides from arachidonic acid [epoxyeicosatrienoic acid (EET)] is important in the regulation of leukotoxin and EET activity. These three epoxidized derivatives from the C18 family (C18-epoxides) were converted to 18-hydroxy-C18-epoxides by human hepatic microsomes with apparent Km values of between 27.6 and 175 μM. Among recombinant P450 enzymes, CYP4F2 and CYP4F3B catalyzed mainly the ω-hydroxylation of C18-epoxides with an apparent Vmax of between 0.84 and 15.0 min−1, whereas the apparent Vmax displayed by CYP4F3A, the isoform found in leukocytes, ranged from 3.0 to 21.2 min−1. The rate of ω-hydroxylation by CYP4A11 was experimentally found to be between 0.3 and 2.7 min−1. CYP4F2 and CYP4F3 exhibited preferences for ω-hydroxylation of Z 8(9)-EET, whereas human liver microsomes preferred Z 11(12)-EET and, to a lesser extent, Z 8(9)-EET. Moreover, vicinal diol from both C18-epoxides and EETs were ω-hydroxylated by liver microsomes and by CYP4F2 and CYP4F3. These data support the hypothesis that the human CYP4F subfamily is involved in the ω-hydroxylation of fatty acid epoxides. These findings demonstrate that another pathway besides conversion to vicinal diol or chain shortening by β-oxidation exists for fatty acid epoxide inactivation.