Abstract
5-Oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-oxo-ETE) is a metabolite of the 5-lipoxygenase (5-LO) product 5S-hydroxy-6E,8Z,11Z,14Z-eicosatetraenoic acid (5-HETE), formed by the microsomal enzyme 5-hydroxyeicosanoid dehydrogenase (5-HEDH). 5-oxo-ETE is a chemoattractant for neutrophils and eosinophils, both in vitro and in vivo. To examine the substrate selectivity of 5-HEDH and to search for potential inhibitors, we prepared a series of 5S-hydroxy fatty acids (C12 to C20 containing zero to four double bonds) by total chemical synthesis and examined their metabolism by microsomes from monocytic U937 cells. Although most of these fatty acids were oxidized to their 5-oxo metabolites by 5-HEDH, 5-HETE seemed to be the best substrate. However, substrates containing less than 16 carbons, a methylated α-carboxyl group, or a hydroxyl group at the ω-end of the molecule were not substantially metabolized. Some of the fatty acids tested were fairly potent inhibitors of the formation of 5-oxo-ETE by 5-HEDH, in particular 5-hydroxy-6-octadecenoic acid and 5-hydroxy-6-eicosenoic acid. Both substances selectively inhibited 5-oxo-ETE formation by human peripheral blood mononuclear cells incubated with arachidonic acid and calcium ionophore without affecting the formation of leukotriene B4, 12-HETE, or 12-hydroxy-5,8,10-heptadecatrienoic acid. We conclude that the requirements for appreciable metabolism by 5-HEDH include a chain length of at least 16 carbons, a free α-carboxyl group, and a hydrophobic group at the ω-end of the molecule. 5-Hydroxy-Δ6 C18 and C20 fatty acids selectively inhibit 5-HEDH without inhibiting 5-LO, leukotriene A4 hydrolase, 12-lipoxygenase, or cyclooxygenase. Such compounds may be useful in defining the role of 5-oxo-ETE and its mechanism of synthesis.
Footnotes
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This work was supported in part by the National Institutes of Health National Heart, Lung, and Blood Institute [Grant HL81873]; the Canadian Institutes of Health Research [Grant MOP-6254]; and the Quebec Heart and Stroke Foundation.
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The Meakins-Christie Laboratories-MUHC-RI are supported in part by the Le Fonds de la Recherche en Santé du Québec [center grant] and the J.T. Costello Memorial Research Fund.
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Article, publication date, and citation information can be found at http://jpet.aspetjournals.org.
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doi:10.1124/jpet.108.143453.
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ABBREVIATIONS: 5-LO, 5-lipoxygenase; LT, leukotriene; 5-oxo-ETE, 5-oxo-6E,8Z,11Z,14Z-eicosatetraenoic acid; AA, arachidonic acid; 5-HpETE, 5S-hydroperoxy-6,8,11,14-eicosatetraenoic acid; 5-HETE, 5S-hydroxy-6E,8Z,11Z,14Z-eicosatetraenoic acid; 5-HEDH, 5-hydroxyeicosanoid dehydrogenase; 5,18-diOH-18:2, 5S,18-dihydroxy-6E,8Z-octadecadienoic acid; RP-HPLC, reversed-phase high-performance liquid chromatography; 13-HODE, 13S-hydroxy-9Z,11E-octadecadienoic acid; 5h-20:5 (5-HEPE), 5-hydroxy-6E,8Z,11Z,14Z,17Z-eicosapentaenoic acid; PMA, phorbol 12-myristate 13-acetate; tBuOOH, t-butyl hydroperoxide; PBS, phosphate-buffered saline; PBMC, peripheral blood mononuclear cell; 5h-12:2, 5S-hydroxy-6E,8Z-dodecadienoic acid; 5h-14:2, 5S-hydroxy-6E,8Z-tetradecadienoic acid; tR, retention time; 5-oxo-18:1, 5-oxo-6E-octadecenoic acid; 5-oxo-20:1, 5-oxo-6E-eicosenoic acid; 5h-18:1, 5S-hydroxy-6E-octadecenoic acid; 5h-18:2, 5S-hydroxy-6E,8Z-octadecadienoic acid; 5h-20:1, 5S-hydroxy-6E-eicosenoic acid; Δ6,8,11-5h-20:3, 5S-hydroxy-6E,8Z,11Z-eicosatrienoic acid; 5h-16:2, 5S-hydroxy-6E,8Z-hexadecadienoic acid; 5h-20:2, 5S-hydroxy-6E,8Z-eicosadienoic acid; 5h-20:0, 5-hydroxyeicosanoic acid; 12-HHT, 12-hydroxy-5,8,10-heptadecatrienoic acid; Δ6,18,14-5h-20:3, 5-hydroxy-6E,8Z,14Z-eicosatrienoic acid; 5-HETE-Me, 5-HETE methyl ester; 5-oxo-ETE-Me, 5-oxo-ETE methyl ester.
- Received July 18, 2008.
- Accepted January 21, 2009.
- The American Society for Pharmacology and Experimental Therapeutics
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