A study on the role of protein kinase C and intracellular calcium in the activation of superoxide generation.

Accumulating evidence indicates that protein kinase C plays an essential role in the activation of NADPH oxidase. In the present study, the correlation between superoxide generation, intracellular calcium, activation of purified protein kinase C and stabilized membrane-bound protein kinase C was studied. Phorbol 12-myristate 13-acetate (PMA) and 1-deacyl-2-acetyl-rac-glycerol (OAG) were found to induce equal activation of purified protein kinase C and translocation of protein kinase C to the membrane fraction, but differed significantly in their ability to induce superoxide generation.

Modulation of high-affinity interleukin 2 receptors on activated human T lymphocytes by activators of protein kinase C.

Phorbol myristate acetate (PMA) and 1-oleoyl-2-acetyl-rac-glycerol (OAG) are shown to induce a rapid (within 30 min) down-regulation of the capacity of activated human T lymphocytes to bind interleukin 2. This was associated with a manifold increase in membrane-associated protein kinase C, whereas no change in free cytoplasmic calcium was observed. In contrast, a 10-fold increase in free cytoplasmic calcium by ionomycin had no effect on interleukin 2 binding or subcellular distribution of protein kinase C.

Membrane-associated protein kinase C activity in superoxide-producing human polymorphonuclear leukocytes.

Protein kinase C activity was studied in superoxide-producing human polymorphonuclear leukocytes. Using equivalent cell concentrations, superoxide production and particulate fraction-associated protein kinase C activity increased in parallel in phorbol 12-myristate 13-acetate (PMA), oleoyl-acetyl-glycerol (OAG), opsonized zymosan, and A23187-activated leukocytes. Also, an increase in particulate fraction-associated phospholipid-independent kinase activity was observed upon stimulation with these activators.

Protein kinase C activity in activated human T-lymphocytes stimulated by interleukin-2.

Interleukin-2 and phorbol 12-myristate 13-acetate (PMA) are shown to induce DNA-synthesis in human T-lymphocytes activated with phytohaemagglutinin. However, whereas PMA induced a rapid and persistent translocation of protein kinase C from cytosol to particulate fraction, no translocation was observed upon stimulation with interleukin-2. Treatment with PMA for 72 h caused a slow down-regulation of protein kinase C activity to less than 10% of unstimulated T-lymphocytes and was mainly located in the particulate fraction.