Abstract
Oxidative stress plays a critical role in the modulation of several important physiological functions. On the other hand, oxidative stress is accountable for development of many unphysiological changes, which could be deleterious for cells. Oxidative stress is a cellular or physiological condition due to elevated concentrations of reactive oxygen species (ROS) that cause molecular damage to vital structures and
functions. Several factors influence the susceptibility to oxidative stress by affecting the antioxidant status and/or oxygen free radical generation. These factors can be divided into those of endogenous, e.g. exercise and psychological stress or of exogenous origin, e.g. food, alcohol, cigarette smoke, environmental pollutants, UV and radiation. ROS have been shown to participate in the pathogenesis of many human diseases. However, the biochemical mechanisms by which ROS cause cell damage and ultimately organ dysfunction are not fully understood. One of the major cellular targets of ROS is protein. ROS can oxidize both aliphatic and aromatic amino acid residues of proteins, leading to irreversible structural changes. Redox environment is controlled by a variety of redox regulating systems that include superoxide dismutase, glutathione peroxidase, thioredoxin, thioredoxin reductase, glutaredoxin and peroxiredoxin. In this study, we examined whether and how cellular sensitivities to radiation and oxidative stress are modulated by overexpression of these antioxidant enzymes in cultured human cells.
