Figure 5

Role of thioredoxin in the oxidant- or gamma irradiation-induced stress response and apoptosis. A. Induction of thioredoxin gene expression by oxidants and gamma irradiation. THP1 monocytic cells were treated with media alone or with varying doses of hydrogen peroxide for 24 h (Panel a). Cells were exposed to varying doses of gamma irradiation (γ-IR) and further cultured for 16 h (Panel b). Cells were treated with media alone, IFN-γ (10 ng/ml), γ-IR (5 Gy), and IFN-γ plus γ-IR for 16 h (Panel c). Total RNA was prepared and analyzed by Northern blot to determine the thioredoxin mRNA levels. B. Protective function of thioredoxin against gamma irradiation-induced apoptosis. U937 monocytic cells were either mock-transfected with empty vector (-) or transfected with thioredoxin expression construct (+) and then cultured for 40 h. The cells were then exposed to 50 Gy of γ-IR, after which they were analyzed for ROS generation at 30 min (upper box) and apoptosis at 16 h (lower box) as described in the text.