Localization of 12-hydroxyeicosatetraenoic acid in endothelial cells.
Bovine aortic endothelial cells take up 12-hydroxyeicosatetraenoic acid (12-HETE), a lipoxygenase product formed from arachidonic acid. The uptake of [3H]12-HETE reached a maximum in 2 to 4 h. At this time, from 75 to 80% of the incorporated radioactivity was contained in phospholipids, about 85% of the esterified radioactivity remained in the form of 12-HETE, and at least 90% of the phospholipid radioactivity was present in the sn-2-position. Subcellular fractionation on Percoll and sucrose gradients demonstrated that 65 to 74% of the radioactivity was present in membranes enriched in NADPH-cytochrome c reductase and UDP-galactosyl transferase. The specific radioactivity relative to protein of these intracellular membranes was 2.9-times higher than in a plasma membrane fraction enriched in 5'-nucleotidase. A similar intracellular localization was observed when [3H]5-HETE or [3H]arachidonic acid were taken up. The 12-HETE was contained primarily in the choline glycerophospholipids of the microsomal membranes. After incorporation, [3H]12-HETE was removed from the cell lipids much more rapidly than [3H]arachidonic acid, and 80% of the radioactivity released into the medium during the first hour remained as 12-HETE. Because it accumulates in microsomal membranes, 12-HETE uptake may perturb certain intracellular processes and thereby lead to endothelial dysfunction. The relatively rapid removal of the newly incorporated 12-HETE may be an important protective mechanism that prevents excessive accumulation and more extensive endothelial damage.
Wang
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Department of Biochemistry, University of Iowa, Iowa City 52242.
Kaduce
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Spector
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D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D000818:Animals; D002417:Cattle; D002458:Cell Fractionation; D002478:Cells, Cultured; D002499:Centrifugation, Density Gradient; D004730:Endothelium, Vascular / Q000378:metabolism*; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism*; D007700:Kinetics; D008563:Membrane Lipids / Q000378:metabolism
D006893:Hydroxyeicosatetraenoic Acids; D008563:Membrane Lipids; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid