Kohzaki Masaoki, Nishihara Kana, Hirota Kouji, Sonoda Eiichiro, Yoshimura Michio, Ekino Shigeo, Butler John E, Watanabe Masami, Halazonetis Thanos D, Takeda Shunichi
Department of Radiation Genetics, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
J Cell Biol. 2010 Jun 28;189(7):1117-27. doi: 10.1083/jcb.200912012.
The chicken DT40 B lymphocyte line diversifies its immunoglobulin (Ig) V genes through translesion DNA synthesis-dependent point mutations (Ig hypermutation) and homologous recombination (HR)-dependent Ig gene conversion. The error-prone biochemical characteristic of the A family DNA polymerases Polnu and Pol led us to explore the role of these polymerases in Ig gene diversification in DT40 cells. Disruption of both polymerases causes a significant decrease in Ig gene conversion events, although POLN(-/-)/POLQ(-/-) cells exhibit no prominent defect in HR-mediated DNA repair, as indicated by no increase in sensitivity to camptothecin. Poleta has also been previously implicated in Ig gene conversion. We show that a POLH(-/-)/POLN(-/-)/POLQ(-/-) triple mutant displays no Ig gene conversion and reduced Ig hypermutation. Together, these data define a role for Polnu and Pol in recombination and suggest that the DNA synthesis associated with Ig gene conversion is accounted for by three specialized DNA polymerases.
鸡DT40 B淋巴细胞系通过跨损伤DNA合成依赖性点突变（Ig超突变）和同源重组（HR）依赖性Ig基因转换来使免疫球蛋白（Ig）V基因多样化。A家族DNA聚合酶Polν和Pol的易错生化特性促使我们探究这些聚合酶在DT40细胞Ig基因多样化中的作用。两种聚合酶的缺失均导致Ig基因转换事件显著减少，尽管POLN(-/-)/POLQ(-/-)细胞在HR介导的DNA修复中未表现出明显缺陷，如对喜树碱的敏感性未增加所示。之前也有研究表明Polθ参与了Ig基因转换。我们发现POLH(-/-)/POLN(-/-)/POLQ(-/-)三突变体不发生Ig基因转换且Ig超突变减少。总之，这些数据确定了Polν和Pol在重组中的作用，并表明与Ig基因转换相关的DNA合成由三种特殊的DNA聚合酶负责。
Zotero 插件
