Interactions of 12-lipoxygenase with phospholipase A2 isoforms following platelet activation through the glycoprotein VI collagen receptor.

Recent studies implicate the collagen receptor, glycoprotein VI (GPVI) in activation of platelet 12-lipoxygenase (p12-LOX). Herein, we show that GPVI-stimulated 12-hydro(peroxy)eicosatetraenoic acid (H(P)ETE) synthesis is inhibited by palmityl trifluromethyl ketone or oleyloxyethylphosphocholine , but not bromoenol lactone, implicating secretory and cytosolic, but not calcium-independent phospholipase A2 (PLA2) isoforms. Also, following GPVI activation, 12-LOX co-immunoprecipitates with both cytosolic and secretory PLA2 (sPLA2). Finally, venoms containing sPLA2 acutely activate p12-LOX in a dose-dependent manner. This study shows that platelet 12-H(P)ETE generation utilizes arachidonate substrate from both c- and sPLA2 and that 12-LOX functionally associates with both PLA2 isoforms. Copyright 2004 Federation of European Biochemical Societies