H. Masaki et al., DIFFERENTIAL ROLE OF CATALASE AND GLUTATHIONE-PEROXIDASE IN CULTURED HUMAN FIBROBLASTS UNDER EXPOSURE OF H2O2 OR ULTRAVIOLET-B LIGHT, Archives of dermatological research, 290(3), 1998, pp. 113-118
The purpose of this study was to elucidate the differential contributi
on of catalase and glutathione peroxidase (GSH-Px) to H2O2 scavenging
in cultured human dermal fibroblasts. Responses of the cells in terms
of both enzyme activities were examined by using two sorts of inhibito
rs, 3-amino-1H-1,2,4-triazole (AT) for catalase and DL-buthionine-[S,
R]-sulfoximine (BSO) for GSH-Px, under exposure to H2O2 or ultraviolet
(UV) B radiation. AT treatment resulted in a decrease in H2O2 scaveng
ing activity, while BSO treatment did not affect H2O2 scavenging. When
fibroblasts were exposed to a low concentration of H2O2 (100 mu M). A
T treatment resulted in a significant decrease in cell survival, but B
SO treatment did not affect survival. At higher concentrations of H2O2
ranging from 500 mu M to 1 mM, BSO-treated fibroblasts showed reduced
survival. In addition, AT treatment was much more cytotoxic in the pr
esence of UVB than BSO treatment. The intracellular levels of H2O2 in
fibroblasts treated with AT or BSO were also determined. BSO-treated c
ells showed similar H2O2 levels to control cells, but the intracellula
r H2O2 levels of AT-treated fibroblasts were 1.4-fold higher than foun
d in control cells. These results with human dermal fibroblasts indica
te that catalase acts as a primary defence against oxidative stress fr
om exogenous or endogenous H2O2 at low concentrations. In contrast, GS
H-Px helps protect the cell from damage during exposure to high concen
trations of H2O2.