The effect of DNA polymerase beta on repair of the γ-rays irradiated hepatoma (H22) cell nuclei

The effects of DNA polymerase alpha and beta on DNA repair of the 40 Gy γ-rays irradiated H22 cell nuclei, using specific inhibitor NEM or ddTTP to DNA polymerase alpha or beta respectively, were observed. The results showed that the rate of DNA repair synthesis of the 40 Gy γ-rays irradiated H22 cell nuclei was much higher than that of the non-irradiated ones after 60, 120 min incubation at 37 deg C (P < 0.05, P < 0.01) when DNA polymerase alpha was inhibited completely. There was no difference in the rate of DNA repair synthesis between the irradiated and the non-irradiated cell nuclei (P > 0.05) when DNA polymerase beta was inhibited completely. And also, there was no difference between them (P > 0.05) when both DNA polymerase alpha and beta were inhibited completely. These results indicate that under our experimental conditions, DNA polymerase beta, not alpha, is responsible for DNA repair of the γ-rays irradiated H22 cell nuclei. The above results are discussd by the author considerably