Abstract
Reactive oxygen species (ROS) are generated in cells exposed to ionizing radiation. ROS oxidize DNA, proteins and lipids, and act as mediators of ionizing radiation-induced cellular damage. ROS have been shown to participate in various biological consequences of ionizing radiation.
In this study, we examined whether and how cellular sensitivity to ionizing radiation and oxidative stress are modulated by the overexpression of superoxide dismutase (SOD) and glutaredoxine (Grx) in cultured human cells. SOD is a scavenging enzyme of superoxide anion and Grx repairs the oxidized macromolecules.
In this study we examined whether the overexpression of SOD1 and SOD2 protects cells against cellular effect of gamma-rays. Overexpression of SOD2 in mitochondria enhanced the survival following gamma irradiation compared with control HeLa cells, while overexpression of SOD1 in the cytosol did not affect the cell survival. As the results of overexpression of SOD2, the levels of DNA double-stranded breaks and oxidized cellular proteins, the expression level of OXR1 protein, and morphologic change of mitochondria were suppressed in HeLa cells.
These results indicated that mitochondrial antioxidant enzymes plays important roles in various cellular responses to the ionizing radiation and cellular homeostasis. We are currently looking at the effect of overexpression of Grx(Grx) in mitochondria.
