MK886, a potent and specific leukotriene biosynthesis inhibitor blocks and reverses the membrane association of 5-lipoxygenase in ionophore-challenged leukocytes

• Published in: The Journal of biological chemistry 1990-01, Vol.265 (3), p.1436-1442
• Main Authors: Rouzer, C A, Ford-Hutchinson, A W, Morton, H E, Gillard, J W
• Format: Article
• Language: English
• Subjects: Arachidonate 5-Lipoxygenase - metabolism; Arachidonate Lipoxygenases - metabolism; Arachidonic Acid; Arachidonic Acids - pharmacology; Calcimycin - pharmacology; Calcium - pharmacology; Cell Compartmentation - drug effects; Cell Membrane - enzymology; cell membranes; Dose-Response Relationship, Drug; Humans; In Vitro Techniques; Indoles - pharmacology; Leukocytes - enzymology; leukotrienes; Leukotrienes - biosynthesis; lipoxygenase; Structure-Activity Relationship
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/s0021-9258(19)40034-3

Recently, we have shown that ionophore activation of human leukocytes results in leukotriene synthesis and a translocation of 5-lipoxygenase from the cytosol to cellular membrane. This membrane translocation was postulated to be an important early activation step for the enzyme. 3-[1-(p-Chlorobenzyl)-5-(isopropyl)-3-tert-butylthioindol-2-yl]-2, 2- dimethylpropanoic acid (MK886) is a potent and specific inhibitor of leukotriene biosynthesis in vivo and in intact cells, but has no direct effect on 5-lipoxygenase activity in cell-free systems. In this report, we show that MK886 can both prevent and reverse the membrane translocation of 5-lipoxygenase, in conjunction with the inhibition of leukotriene synthesis. Similar compounds of the indole class could also inhibit the membrane translocation of 5-lipoxygenase in a rank order of potency that correlated with their potencies for leukotriene synthesis inhibition. In contrast L-656,224, a direct 5-lipoxygenase inhibitor, had no effect on the translocation of the enzyme. Attempts to demonstrate the effects of MK886 on the association of 5-lipoxygenase with membrane in cell-free preparations failed due to a nonspecific Ca2+-dependent sedimentation of the enzyme. The mechanism of action of MK-886 is therefore to block translocation, prevent subsequent activation of 5-lipoxygenase, and hence block cellular leukotriene biosynthesis.