SUBCELLULAR-LOCALIZATION AND TRANSLOCATION OF PROTEIN-KINASE-C ISOFORM-ZETA AND ISOFORM-EPSILON IN HUMAN PERIPHERAL-BLOOD LYMPHOCYTES

The calcium-independent members of the protein kinase C (PKC) family m ay play a significant role in T cell function, We have characterized t he subcellular localization and redistribution of calcium-independent kinase C activity and of two specific members of this family (zeta and epsilon) in response to activation of human peripheral blood lymphocy tes with phorbol myristate acetate (PMA) or through the TCR-CD3 comple x. Both PMA and OKT3, an antibody against the TCR-associated CD3 compl ex, induce an increase in membrane and cytoskeletal activity with a co ncomitant decrease in cytosolic activity, By Western blot analysis, PK C epsilon is present in resting cytosol and membrane fractions, and is detected in the membrane following activation with PMA and in both th e membrane and cytoskeleton following OKT3 activation, By contrast, PK C zeta is progressively lost from the cytoskeleton following activatio n with anti-CD3. Immunocytochemistry reveals distinct redistribution p atterns for these enzymes in response to activation through anti-CD3 a nd by PMA, These findings demonstrate that signaling through the CD3 c omplex induces significant changes in calcium-independent PKC activity and in the intracellular distribution of specific isoenzymes, and sup port a role for specific functions for individual isoenzymes in T cell activation, Lastly, changes in the cytoskeletal distribution of these isoenzymes suggest a potential role in the modulation of cell structu re in response to activation.