ACTIVATION OF PROTEIN-KINASE-C BY OXIDIZED DIACYLGLYCEROLS

The effects of 1,2-diacylglycerol hydroperoxide (DAG-OOH), its alcohol (DAG-OH), ''unoxidized'' 1,2-diacylglycerol (DAG), 1,2-dioleoylglycer ol (DOG), and phorbol 12-myristate acetate (PMA) on the activity of pr otein kinase C (PKC) isolated from rat brain were examined in the pres ence and absence of phosphatidylserine (PS) and calcium ion. Both DAG- OOH and DAG-OH stimulated the activity of PKC dose- and time-dependent ly, The ability of additives for PKC activation increased in the order of DOG, DAG << DAG-OOH, DAG-OH < PMA. DAG-OOH and DAG-OH activated PK C even in the absence of PS and calcium ion as PMA does. If DAG-OOH an d DAG-OH are released from the oxidized biomembranes by the action of phospholipase C, these components may act like PMA and serve to activa te the PKC-dependent signal transduction system. (C) 1995 Academic Pre ss, Inc.