Proteinkinase C beta-isoform triggers the formation of prostanoids and superoxide in liver macrophages.

The zymosan- and phorbolester-induced formation of prostanoids in cultured rat liver macrophages has been shown recently to be controlled by proteinkinase C (1). Using specific antibodies raised against the alpha-, beta-, gamma- and epsilon-isoforms of proteinkinase C, we show that proteinkinase-beta is the predominant isoform in rat liver macrophages. Northern blot analysis with a beta-isoform-specific c-DNA probe revealed the expression of m-RNA for proteinkinase-beta. In resting cells the beta-isoform of proteinkinase C is nearly equally distributed between the cytosolic and membrane fractions. Zymosan and phorbolester led to a translocation of proteinkinase-beta from the cytosol to the membranes, whereas exogenously added arachidonic acid and the calcium ionophore A23187 had no effect. These data indicate that the beta-isoform of proteinkinase C takes part in the prostaglandin and superoxide formation following PMA and zymosan treatment of rat liver macrophages.