POLK和POLH在N-甲基-N′-硝基-N-亚硝基胍引起的非定标突变中的作用

Role of POLK and POLH in N-methyl-N′-nitro-N-nitrosoguanidine induced nontargeted mutagenesis

目的 研究DNA聚合酶kappa(POLK)和DNA聚合酶eta(POLH)的功能。方法 采用穿梭质粒pZ189介导的突变试验,对建立的阻断细胞系FL POLK- 和FL POLH- 进行非定标突变研究。结果穿梭质粒pZ189在FL POLK- 和FL POLH- 细胞中复制后,其supFtRNA基因的自发突变频率分别为11.2×10 - 4和13 .5×10 - 4,而对照细胞FL和FL M分别为4 .9×10 - 4和3 .7×10 - 4。质粒在接触过N 甲基 N′硝基 N 亚硝基胍的FL POLK- 和FL POLH- 细胞中复制,其supFtRNA基因的非定标突变频率下降。结论 POLK和POLH在维持哺乳类细胞的基因组稳定性中起重要作用,同时它们还参与了哺乳动物细胞非定标突变的形成,如同其同源基因编码的PolⅣ和PolⅤ在E .

AIM To study the function of polymerase kappa(POLK) and polymerase eta(POLH) in N-methyl-N′-nitro-N-nitrosoguanidine(MNNG) induced nontargeted mutagenesis. METHODS(Based on the) shuttle-plasmid pZ189, the mutation assay was made in the FL-POLK^- and FL-POLH^- cells. RESULTS The spontaneous mutation frequency of SupF tRNA gene in the plasmid replicated in the FL-POLK^- and FL-POLH^- cells was 11.2×10^(-4) and 13.5×10^(-4), respectively, while it was 4.9×10^(-4) and 3.7×10^(-4) in the control cells FL and FL-M, respectively. The nontargeted mutation frequency of SupF tRNA gene decreased in the plasmid replicated in these cell lines pretreated with MNNG. CONCLUSION POLK and POLH take an important role in maintenance of genetic stability. POLK and POLH also take part in the genesis of nontargeted mutation, just as the role played by their homologous polymerases, Pol Ⅳ and Pol Ⅴ of umuC (superfamily) in the nontargeted mutagenesis in (Escherichia) coli.