Induction of 5-lipoxygenase activation in polymorphonuclear leukocytes by 1-oleoyl-2-acetylglycerol.
1,2-Diacylglycerols (DAGs) can prime polymorphonuclear leukocytes (PMNL) for enhanced release of arachidonic acid (AA) and generation of 5-lipoxygenase (5-LO) products upon subsequent agonist stimulation. Here, we demonstrate that in isolated human PMNL, 1-oleoyl-2-acetylglycerol (OAG) functions as a direct agonist stimulating 5-LO product formation (up to 42-fold). OAG caused no release of endogenous AA, but in the presence of exogenous AA, the magnitude of 5-LO product synthesis induced by OAG was comparable to that obtained with the Ca(2+)-ionophore A23187. Interestingly, OAG-induced 5-LO product synthesis was not connected with increased 5-LO nuclear membrane association. Examination of diverse glycerides revealed that the sn-2-acetyl-group is important, thus, also 1-O-hexadecyl-2-acetylglycerol (EAG) stimulated 5-LO product formation (up to 8-fold). Treatment of PMNL with OAG did not alter the mobilization of Ca(2+) but removal of intracellular Ca(2+) abolished the upregulatory OAG effects. Notably, the PKC activator phorbol-myristate-acetate hardly increased 5-LO product synthesis and PKC inhibitors failed to suppress the effects of OAG. Although OAG rapidly activated p38 MAPK and p42/44(MAPK), which can stimulate 5-LO for product synthesis, specific inhibitors of these kinases could not prevent 5-LO activation by OAG. Together, OAG acts as a direct agonist for 5-LO product synthesis in PMNL stimulating 5-LO by novel undefined mechanisms.
Albert
Dana
D
Institute of Pharmaceutical Chemistry, University of Frankfurt, Marie-Curie-Str 9, D-60439, Frankfurt, Germany.
Buerkert
Eva
E
Steinhilber
Dieter
D
Werz
Oliver
O
D001094:Arachidonate 5-Lipoxygenase / Q000096:biosynthesis*; D016718:Arachidonic Acid / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D004075:Diglycerides / Q000737:chemistry / Q000494:pharmacology*; D004789:Enzyme Activation; D006801:Humans; D007476:Ionophores / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology*; D011493:Protein Kinase C / Q000378:metabolism; D015854:Up-Regulation
D004075:Diglycerides; D007476:Ionophores; D016718:Arachidonic Acid; D000001:Calcimycin; C038237:1-oleoyl-2-acetylglycerol; D001094:Arachidonate 5-Lipoxygenase; D011493:Protein Kinase C; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium