Homologous recombination and non-homologous end-joining pathways of DNA double-strand break repair have overlapping roles in the maintenance of chromosomal integrity in vertebrate cells
Homologous recombination and non-homologous end-joining pathways of DNA double-strand break repair have overlapping roles in the maintenance of chromosomal integrity in vertebrate cells
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DOI：
10.1093/emboj/17.18.5497
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发表时间：
1998-09-15
期刊：
影响因子：
11.4
通讯作者：
Takeda, S
中科院分区：
文献类型：
--
作者：
Takata, M;Sasaki, MS;Takeda, S
真核细胞修复DNA双链断裂至少有两条途径，同源重组(HR)和非同源末端连接(NHEJ)。RAD54参与第一条重组修复途径，而Ku蛋白参与NHEJ。为了研究这两个修复途径的差异和冗余作用，我们分析了从鸡B细胞系DT40产生的突变体RAD54(-/-)、KU70(-/-)和RAD54(-/-)/KU70(-/-)。我们发现，在G(1)-S早期，NHEJ通路在伽玛辐射诱导的DSB修复中起主导作用，而在S-G(2)晚期，重组修复优先使用。RAD54(-/-)/KU70(-/-)细胞对伽马射线的敏感度比任何一个突变体都高得多，这表明这两条修复途径是互补的。在RAD54(-/-)和RAD54(-/-)/KU70(-/-)细胞中均观察到自发的染色体异常和细胞死亡，其中RAD54(-/-)/KU70(-/-)细胞的染色体畸变率明显高于RAD54-/-细胞。这些观察提供了第一个遗传学证据，证明这两条修复途径在细胞周期中都在维持染色体DNA方面发挥了作用。
Eukaryotic cells repair DNA double-strand breaks (DSBs) by at least two pathways, homologous recombination (HR) and non-homologous end-joining (NHEJ). Rad54 participates in the first recombinational repair pathway while Ku proteins are involved in NHEJ. To investigate the distinctive as well as redundant roles of these two repair pathways, we analyzed the mutants RAD54(-/-), KU70(-/-) and RAD54(-/-)/KU70(-/-), generated from the chicken B-cell line DT40. We found that the NHEJ pathway plays a dominant role in repairing gamma-radiation-induced DSBs during G(1)-early S phase while recombinational repair is preferentially used in late S-G(2) phase. RAD54(-/-)/KU70(-/-) cells were profoundly more sensitive to gamma-rays than either single mutant, indicating that the two repair pathways are complementary. Spontaneous chromosomal aberrations and cell death were observed in both RAD54(-/-) and RAD54(-/-)/KU70(-/-) cells, with RAD54(-/-)/KU70(-/-) cells exhibiting significantly higher levels of chromosomal aberrations than RAD54-/- cells. These observations provide the first genetic evidence that both repair pathways play a role in maintaining chromosomal DNA during the cell cycle.