Taurine chloramine inhibits superoxide anion production by regulating translocation and phosphorylation of NADPH oxidase components

초록

NADPH oxidase is a membrane-associated enzyme complex that generates superoxide anion (O2-). Upon stimulation, the cytosolic components of NADPH oxidase, p47phox, p40phox, p67phox and small GTPase, Rac move to plasma membrane and become associated with the membrane components, p22phox and gp91phox of NADPH oxidase. We previously showed that taurine and taurine chloramine (Tau-Cl), formed by a reaction of taurine with HOCl/OCl-, inhibits O2- production in mouse peritoneal polymorphonuclear (PMN) cells (Kim C., Immunopharmacology 34, 1996). Here we investigated the mechanisms underlying the effect of Tau-Cl on O2- production using a human myeloid leukemia cell line, PLB 985 cells. Tau-Cl inhibited the PMA-elicited O2- production which was measured by cytochrome c reduction and nitroblue tetrazolium (NBT) assay. Tau-Cl also inhibited PMA-stimulated translocation of p47phox and p67phox to plasma membrane, but not Rac. In addition, Tau-Cl reduced phosphorylation of p47phox. These results suggest that the deceased PMA-elicited O2- production by Tau-Cl in PLB 985 cells is caused by inhibition of the NADPH oxidase assembly rather than interaction with assembled NADPH oxidase complex.