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. Intracellular calcium was varied using calcium ionophores and increasing the intracellular calcium concentration to more than 1 microM was found to induce increased superoxide generation in maximally OAG-stimulated cells; this contrasted to maximally PMA-stimulated leukocytes. Ionomycin and A23187 were both found to induce a translocation of protein kinase C to the membrane fraction. This translocation was highly dependent upon extracellular calcium. In contrast, PMA- and OAG-induced translocation of protein kinase C was not dependent upon extracellular calcium. In conclusion, our results indicate that although PMA, OAG and calcium ionophores seem to activate protein kinase C in human polymorphonuclear leukocytes these activators differ in their ability to induce superoxide generation.
Christiansen
N O
NO
Department of Medicine and Infectious Diseases, Marselisborg Hospital, Aarhus C, Denmark.
Larsen
C S
CS
Esmann
V
V
D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000097:blood* / Q000502:physiology; D002462:Cell Membrane / Q000201:enzymology; D004075:Diglycerides / Q000494:pharmacology; D004789:Enzyme Activation; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism*; D011493:Protein Kinase C / Q000097:blood* / Q000502:physiology; D013481:Superoxides / Q000097:blood*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004075:Diglycerides; D013481:Superoxides; D000001:Calcimycin; D009240:N-Formylmethionine Leucyl-Phenylalanine; C038237:1-oleoyl-2-acetylglycerol; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium