Different roles for nonhomologous end joining and homologous recombination following replication arrest in mammalian cells
Different roles for nonhomologous end joining and homologous recombination following replication arrest in mammalian cells
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DOI：
10.1128/mcb.22.16.5869-5878.2002
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发表时间：
2002-08-01
影响因子：
5.3
通讯作者：
Helleday, T
中科院分区：
文献类型：
--
作者：
Lundin, C;Erixon, K;Helleday, T
同源重组（HR）和非同源末端连接（NHEJ）在细胞周期S期产生的DNA双链断裂（DSBs）修复中起重叠作用。在这里，我们描述了HR和NHEJ参与拯救被羟基脲或胸腺嘧啶处理的仓鼠细胞阻滞或减慢的DNA复制叉。我们发现，羟基脲阻止复制会在新复制的DNA上形成dsb，从而产生DNA碎片。HR和NHEJ均能保护细胞免受羟基脲的致死作用，并增加了同源和非同源交换介导的重组频率。胸腺嘧啶诱导较不严格的复制阻滞，并没有产生可检测的dsb。单靠HR就能将细胞从胸苷嘧啶的致命作用中拯救出来。此外，胸苷嘧啶增加了在没有检测到dsb的情况下仅由HR介导的DNA交换频率。我们的数据表明，NHEJ和HR都参与了包括DSB的停滞复制分叉的修复，而在没有可检测到的DSB的情况下，HR单独用于修复减慢的复制分叉。
Homologous recombination (HR) and nonhomologous end joining (NHEJ) play overlapping roles in repair of DNA double-strand breaks (DSBs) generated during the S phase of the cell cycle. Here, we characterized the involvement of HR and NHEJ in the rescue of DNA replication forks arrested or slowed by treatment of hamster cells with hydroxyurea or thymidine. We show that the arrest of replication with hydroxyurea generates DNA fragmentation as a consequence of the formation of DSBs at newly replicated DNA. Both HR and NHEJ protected cells from the lethal effects of hydroxyurea, and this agent also increased the frequency of recombination mediated by both homologous and nonhomologous exchanges. Thymidine induced a less stringent arrest of replication and did not generate detectable DSBs. HR alone rescued cells from the lethal effects of thymidine. Furthermore, thymidine increased the frequency of DNA exchange mediated solely by HR in the absence of detectable DSBs. Our data suggest that both NHEJ and HR are involved in repair of arrested replication forks that include a DSB, while HR alone is required for the repair of slowed replication forks in the absence of detectable DSBs.