Effects of calyculin A and FK506 on the O2- generation of rat peritoneal macrophages.
To investigate the role of phosphatase in O2- generation, the effects of the potent phosphoprotein phosphatase inhibitors, Calyculin A and FK506, were analyzed during phagocytosis using rat peritoneal macrophages. O2- generation was continuously measured after addition of opsonized zymosan (op. ZY) or IgG-coated zymosan (IgG-ZY). The rate of O2- generation was directly proportional to the number of macrophages, up to 1-2 x 10(6) cells/ml. It was found that the rate and duration of O2- generation were markedly inhibited by Calyculin A. The addition of 100 nM of Calyculin A reduced O2- generation to about one-tenth of the control value. In contrast, FK506 did not inhibit O2- generation, suggesting that calcium calmodulin phosphatase is not involved in the activation of NADPH oxidase. This result indicates that the process of dephosphorylation might involve activation of NADPH oxidase as a control mechanism in phagocytosis by rat peritoneal macrophages. Furthermore, since Calyculin A is an inhibitor of phosphatase 1 and 2A, it is suggested that dephosphorylation may be evoked by these phosphatases.
Kogi
M
M
National Institute of Health Sciences, School of Medicine, Tokai University, Tokyo, Japan.
Yamaguchi
T
T
Oshizawa
T
T
Hayakawa
T
T
D000818:Animals; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism*; D008387:Marine Toxins; D010080:Oxazoles / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D054645:Protein Phosphatase 1; D051381:Rats; D013481:Superoxides / Q000378:metabolism*; D016559:Tacrolimus / Q000494:pharmacology*
D008387:Marine Toxins; D010080:Oxazoles; D013481:Superoxides; C059041:calyculin A; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1; D016559:Tacrolimus