ACTIVATION OF PROTEIN-KINASE-C BY LIPOXIN-A AND OTHER EICOSANOIDS - INTRACELLULAR ACTION OF OXYGENATION PRODUCTS OF ARACHIDONIC-ACID

Arachidonic acid, linolenic acid and 14 different oxygenated fatty acid derivatives were tested as activators of human protein kinase C in vitro using histone as substrate. Lipoxin A (5,6,15L-trihydroxy-7,9,11,13-eicosatetraenoic acid) activated the kinase in the presence of calcium at 30 fold lower concentration (1 .mu.M) than did arachidonic acid or 1,3-dioleoylglycerol. The methyl ester of lipoxin A and the free acids of leukotriene B4 as well as two lipoxin B isomers were without effect. In contrast, linolenic acid, leukotriene C4, certain mono- and dihydroxylated eicosanoids and one lipoxin B isomer had stimulatory effects, albeit at higher concentrations. The substrate specificity of protein kinase C activated by lipoxin A proved to be different from that of the phosphatidylserine or phorbol ester activated kinase. Results of the present study suggest that arachidonic acid derived oxygenation products, in particular lipoxin A, may serve as intracellular activators of protein kinase C.