Genetic evidence for involvement of two distinct nonhomologous end-joining pathways in repair of topoisomerase II-mediated DNA damage
Genetic evidence for involvement of two distinct nonhomologous end-joining pathways in repair of topoisomerase II-mediated DNA damage
复制标题
DOI：
10.1016/j.bbrc.2004.04.099
复制
发表时间：
2004-06-11
影响因子：
3.1
通讯作者：
Koyama, H
中科院分区：
文献类型：
--
作者：
Adachi, N;Iiizumi, S;Koyama, H
在脊椎动物细胞中，DNA双链断裂可以通过同源重组或非同源末端连接(NHEJ)有效修复。后者依赖于Ku(Ku70/Ku86异源二聚体)、DNA-PKcs、Artemis、Xrcc4和DNA连接酶IV(Lig4)。在这里，我们显示了Lig4缺失的人前B细胞系对拓扑异构酶II(TOP2)抑制剂表现出超敏反应，表明NHEJ通路在修复TOP2诱导的脊椎动物DNA损伤中起着至关重要的作用。我们还发现，在鸡DT40细胞系中，所有NHEJ突变体(即Ku70-、Lig4-和DNA-PKcs-空细胞)对TOP2抑制剂ICRF-193同样敏感，表明涉及DNA-PKcs的NHEJ修复了药物诱导的损伤。然而，有趣的是，DNA-PKcs-空细胞在对VP-16(一种稳定可切割复合体的TOP2毒药)的超敏反应方面表现出比其他NHEJ突变体要轻得多的严重表型。结果表明，涉及或不涉及DNA-PKcs的两条不同的NHEJ通路对于VP-16诱导的DNA损伤的修复是重要的，这为DNA-PKcs非依赖的NHEJ的生物学相关性提供了额外的证据。我们的结果为TOP2介导的DNA损伤的修复机制提供了重要的见解，并对使用TOP2抑制剂的化疗具有指导意义。(C)2004 Elsevier Inc.保留所有权利。
In vertebrate cells, DNA double-strand breaks are efficiently repaired by homologous recombination or nonhomologous end-joining (NHEJ). The latter pathway relies on Ku (the Ku70/Ku86 heterodimer), DNA-PKcs, Artemis, Xrcc4, and DNA ligase IV (Lig4). Here, we show that a human pre-B cell line nullizygous for Lig4 exhibits hypersensitivity to topoisomerase II (Top2) inhibitors, demonstrating a crucial role for the NHEJ pathway in repair of Top2-induced DNA damage in vertebrates. We also show that in the chicken DT40 cell line, all NHEJ mutants (i.e., Ku70-, Lig4-, and DNA-PKcs-null cells) are equally hypersensitive to the Top2 inhibitor ICRF-193, indicating that the drug-induced damage is repaired by NHEJ involving DNA-PKcs. Intriguingly, however, DNA-PKcs-null cells display considerably less severe phenotype than other NHEJ mutants in terms of hypersensitivity to VP-16, a Top2 poison that stabilizes cleavable complexes. The results indicate that two distinct NHEJ pathways, involving or not involving DNA-PKcs, are important for the repair of VP-16-induced DNA damage, providing additional evidence for the biological relevance of DNA-PKcs-independent NHEJ. Our results provide significant insights into the mechanisms of repair of Top2-mediated DNA damage, with implications for chemotherapy involving Top2 inhibitors. (C) 2004 Elsevier Inc. All rights reserved.