G_1和G_2期细胞对X射线引起双链DNA断裂修复的影响

Effects of G_1 and G_2 Cells on DNA Double Stand Breaks Repair Kinetics Induced by X-ray Irradiation

目的:探讨X射线对G_1和G_2期细胞双链DNA断裂损伤修复的动力学影响。方法:采用3%多聚甲醛或70%乙醇固定受X射线放射细胞的M059J、M059K和Hela,用流式细胞仪分选G_1和G_2期Hela细胞,以脉冲场电泳分析双链DNA断裂修复动力学。结果:乙醇固定不影响X射线放射引起的双链DNA断裂修复动力学,可用于固定Hela细胞G_1和G_2期的分选,且G_2期细胞双链DNA断裂修复速率显著慢于G_1期细胞。结论:G_1和G_2期细胞中的双链DNA断裂可能采用不同的修复方式。G_1期细胞主要采用快速的末端连接修复方式,而G_2期细胞主要采用相对较慢的同源性重组修复方式。

Objective：To study DNA Double Stand Breaks（DSB） repair kinetics in X-ray irradiated G1 and G2 cells. Methods：X-ray irradiated M059J, M059K and Hela cells were fixed with 70% ethanol or 3% paraformaldehyde, and G1 and G2 Hela ceils were sorted by flow cytometry. DSB repair kinetics was analyzed by pulsed field gel electrophoresis. Results： No significant effects of DSB repair kinetics were found in ethanol fixed cells compared to their non-fixed counterpart, and ethanol fixed Hela cells were suitable for sorting G1 and G2 cells. Furthermore, a slower repair kinetics in G2 cells were found than in G1 cells. Conclusion：G1 and G2 phase cells might recruit distinct repair pathways to deal with X ray induced DSBs. DSBs in G1 cells might prefer to be repaired by nonhomologous end-joining（NHEJ） while DSBs in G2 cells might prefer to be repaired by homjol ogous recombination（HRR）.