Differences in basal and hyperoxia-associated HO expression in oxidant-resistant hamster fibroblasts

摘要: Heme oxygenase (HO) is the rate-limiting enzyme in production of bilirubin from heme, and HO-1 its inducible isoenzyme. In metabolic pathway HO a potential oxidant, degraded, antioxidant, bilirubin, generated, potent sequestering agent redox active iron, ferritin, thought to be coinduced. Therefore, sum reactions may useful antioxidant defense. To explore role protection against oxidative stress, we examined expression Chinese hamster fibroblasts (HA-1) as well stable hydrogen peroxide (H2O2)-resistant (OC-14) 95% O2-resistant (O2R95) variant cell lines derived HA-1, after exposure 72 h hyperoxia (95% O2-5% CO2). Total activity, protein, mRNA steady-state levels were assessed before daily during hyperoxia. Controls exposed air-5% CO2. Confluent monolayers O2R95 OC-14 cells had increased basal immunoreactive protein relative HA-1 when grown normoxia, higher total activity. When for up 3 days, cells, which resistant oxygen-induced killing, did not show induction or whereas relatively more sensitive than oxygen-related cytotoxicity, demonstrated significant increases Basal ferritin highest intermediate OC-14, lowest but increase further, with hyperoxic exposure, any lines. We conclude that constitutive associated resistance hyperoxia, an index injury, since it only occurs have sustained cytotoxic injury. also does necessarily accompany oxidant stress. speculate plays damage.