1,2-Diacylglycerol Hydroperoxide Induces the Generation and Release of Superoxide Anion from Human Polymorphonuclear Leukocytes

Abstract

Protein kinase C (PKC) plays a crucial role in receptor-mediated signal transduction affecting a diverse range of cellular responses such as cell proliferation, differentiation, and tumor promotion. PKC is known to be activated by calcium ion and lipids such as phosphatidylserine and 1,2-diacylglycerol, and directly by phorbol 12-myristate 13-acetate (PMA). We have recently reported that 1,2-dilinoleoylglycerol hydroperoxide (1,2-LLG-OOH) and hydroxide (1,2-LLG-OH) activate PKC isolated from rat brain almost as efficiently as does PMA.¹ 1,2-LLG-OOH and 1,2-LLG-OH can activate PKC even in the absence of calcium ion and phosphatidylserine.¹ It is therefore suggested that 1,2-diacylglycerol hydroperoxide (1,2-DAG-OOH) and hydroxide (1,2-DAG-OH) may activate the PKC-dependent signal transduction system if these components are released from oxidized biomembranes by the action of phospholipase C.¹ Recently, we have demonstrated that oxidized 1,2-diacylglycerol can act as a biochemical messenger in cellular systems by showing that 1,2-DAG-OOH activates human polymorphonuclear leukocytes (PMNs).² The activation of PMNs was assessed by measuring the Superoxide anion released from PMNs. The production of Superoxide anion was measured by a chemiluminescence method using a sea-firefly cypridina luciferin analogue, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazo [1, 2-a] pyrazin-3-one (MCLA), as a luminescence reagent. 3