The effect of sirt3 mediated SOD2 in radiation responses

Objective: To study the effects of the silent information regulator 3 (sirt3) and its relative anti-oxidation factors on ionizing radiation (IR)-induced damage in 293T cells. Methods: 293T cells irradiated with 2, 4, 8, 16 Gy of γ-rays, after 6, 12, 24 and 48 h of exposure, the expressions of sirt3 mRNA and SOD2 protein were examined by Real-Time PCR and immunoblotting assay, respectively. sirt3 siRNA was applied to knock down sirt3 in the cells. SOD2 activities were measured by a WST kit and the cellular ROS level was detected by a flow cytometry. Results: The mRNA levels of sirt3 and SOD2 in each group campared with the 0 Gy group were reached the maximum at 12 h(t = 6.75, 13.59, 6.59, 10.13, P < 0.05) and 24 h(t = 6.80, 8.73, 11.09, P < 0.05), and protein levels also increased. It was found that sirt3 was a upstream regulatory factor of SOD2. The activity of SOD2 were much higher at 24 h(t = 46.04, 23.19, 26.28, 14.70, P < 0.05) than that in the 0 Gy group as well as the level of ROS. Conclusion: Sirt3 may strengthen antioxidant protection system through regulation of the SOD2 expression and activity, and possibly plays an important role in IR-induced damage response and clinic treatment. (authors)