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Complex genetic interactions between DNA polymerase β and the NHEJ ligase.
The FEBS Journal ( IF 5.5 ) Pub Date : 2019-07-29 , DOI: 10.1111/febs.15012
Aya Kurosawa 1 , Hiroyuki Kuboshima 1 , Noritaka Adachi 1
Affiliation  

Mammalian cells possess multiple pathways for repairing various types of DNA damage. Although the molecular mechanisms of each DNA repair pathway have been analyzed by biochemical analysis and cell biological analysis, interplay between different pathways has not been fully elucidated. In this study, using human Nalm-6-mutant cell lines, we analyzed the relationship between the base excision repair factor DNA polymerase β (POLβ) and DNA ligase IV (LIG4), which is essential for DNA double-strand break (DSB) repair by non-homologous end-joining (NHEJ). We found that cells lacking both POLβ and LIG4 grew significantly more slowly than either single mutant, indicating cooperative functions of the two proteins in normal cell growth. To further investigate the genetic interaction between POLβ and LIG4, we examined DNA damage sensitivity of the mutant cell lines. Our results suggested that NHEJ acts as a backup pathway for repairing alkylation damage (when converted into DSBs) in the absence of POLβ. Surprisingly, despite the critical role of POLβ in alkylation damage repair, cells lacking POLβ exhibited increased resistance to camptothecin (a topoisomerase I inhibitor that induces DNA single-strand breaks), irrespective of the presence or absence of LIG4. A LIG4-independent increased resistance associated with POLβ loss was also observed with ionizing radiation; however, cells lacking both POLβ and LIG4 were more radiosensitive than either single mutant. Taken together, our findings provide novel insight into the complex interplay between different DNA repair pathways.

中文翻译:

DNA聚合酶β和NHEJ连接酶之间复杂的遗传相互作用。

哺乳动物细胞具有修复各种类型的DNA损伤的多种途径。尽管已通过生化分析和细胞生物学分析分析了每个DNA修复途径的分子机制,但尚未完全阐明不同途径之间的相互作用。在这项研究中,我们使用人类Nalm-6突变细胞系分析了碱基切除修复因子DNA聚合酶β(POLβ)和DNA连接酶IV(LIG4)之间的关系,这对于DNA双链断裂(DSB)是必不可少的通过非同源末端连接(NHEJ)进行修复。我们发现,缺少POLβ和LIG4的细胞比任何一个突变体的生长都明显慢得多,这表明这两种蛋白在正常细胞生长中具有协同作用。为了进一步研究POLβ和LIG4之间的遗传相互作用,我们检查了突变细胞系的DNA损伤敏感性。我们的结果表明,在没有POLβ的情况下,NHEJ可以作为修复烷基化损伤(当转化为DSB时)的备用途径。出人意料的是,尽管POLβ在烷基化损伤修复中起着关键作用,但缺乏POLβ的细胞对喜树碱(诱导DNA单链断裂的拓扑异构酶I抑制剂)的抵抗力增加,而与LIG4的存在与否无关。电离辐射也观察到与POLβ丧失相关的LIG4依赖性增加的耐药性;然而,同时缺乏POLβ和LIG4的细胞比任何一个突变体都具有更高的放射敏感性。综上所述,我们的发现为不同DNA修复途径之间的复杂相互作用提供了新颖的见解。我们的结果表明,在没有POLβ的情况下,NHEJ可以作为修复烷基化损伤(当转化为DSB时)的备用途径。出人意料的是,尽管POLβ在烷基化损伤修复中起着关键作用,但缺乏POLβ的细胞对喜树碱(诱导DNA单链断裂的拓扑异构酶I抑制剂)的抵抗力增加,而与LIG4的存在与否无关。电离辐射也观察到与POLβ丧失相关的LIG4依赖性增加的耐药性;然而,同时缺乏POLβ和LIG4的细胞比任何一个突变体都具有更高的放射敏感性。综上所述,我们的发现为不同DNA修复途径之间的复杂相互作用提供了新颖的见解。我们的结果表明,在没有POLβ的情况下,NHEJ可以作为修复烷基化损伤(当转化为DSB时)的备用途径。出人意料的是,尽管POLβ在烷基化损伤修复中起着关键作用,但缺乏POLβ的细胞对喜树碱(诱导DNA单链断裂的拓扑异构酶I抑制剂)的抵抗力增加,而与LIG4的存在与否无关。电离辐射也观察到与POLβ丧失相关的LIG4依赖性增加的耐药性;然而,缺乏POLβ和LIG4的细胞比任何一个突变体都对放射线敏感。综上所述,我们的发现为不同DNA修复途径之间的复杂相互作用提供了新颖的见解。尽管POLβ在烷基化损伤修复中起着关键作用,但是缺乏POLβ的细胞对喜树碱(诱导DNA单链断裂的拓扑异构酶I抑制剂)的抵抗力增加,而与LIG4的存在与否无关。电离辐射也观察到与POLβ丧失相关的LIG4依赖性增加的耐药性;然而,同时缺乏POLβ和LIG4的细胞比任何一个突变体都具有更高的放射敏感性。综上所述,我们的发现为不同DNA修复途径之间的复杂相互作用提供了新颖的见解。尽管POLβ在烷基化损伤修复中起着关键作用,但是缺乏POLβ的细胞对喜树碱(诱导DNA单链断裂的拓扑异构酶I抑制剂)的抵抗力增加,而与LIG4的存在与否无关。电离辐射也观察到与POLβ丧失相关的LIG4依赖性增加的耐药性;然而,缺乏POLβ和LIG4的细胞比任何一个突变体都对放射线敏感。综上所述,我们的发现为不同DNA修复途径之间的复杂相互作用提供了新颖的见解。电离辐射也观察到与POLβ丧失相关的LIG4依赖性增加的耐药性;然而,同时缺乏POLβ和LIG4的细胞比任何一个突变体都具有更高的放射敏感性。综上所述,我们的发现为不同DNA修复途径之间的复杂相互作用提供了新颖的见解。电离辐射也观察到与POLβ丧失相关的LIG4依赖性增加的耐药性;然而,缺乏POLβ和LIG4的细胞比任何一个突变体都对放射线敏感。综上所述,我们的发现为不同DNA修复途径之间的复杂相互作用提供了新颖的见解。
更新日期:2020-01-21
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