Acute inactivation of the replicative helicase in human cells triggers MCM8-9-dependent DNA synthesis.
Acute inactivation of the replicative helicase in human cells triggers MCM8-9-dependent DNA synthesis.
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DOI：
10.1101/gad.297663.117
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发表时间：
2017-04-15
影响因子：
10.5
通讯作者：
Kanemaki MT
中科院分区：
文献类型：
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作者：
Natsume T;Nishimura K;Minocherhomji S;Bhowmick R;Hickson ID;Kanemaki MT
Natalie等人表明，MCM 2耗尽的细胞激活DNA损伤反应途径并产生复制相关的DNA双链断裂（DSB）。这些细胞在没有MCM 2的情况下维持一定的DNA合成，这需要MCM 8 -9复合物，MCM 2 -7复制解旋酶的一部分。DNA复制叉进程可以在人类基因组中难以复制的位点被破坏，这有可能挑战染色体的完整性。这种复制叉破坏可导致复制体的解离和DNA损伤的形成。为了模拟DNA复制扰动过程中复制体解离的事件，我们使用了一个基于degron的系统来诱导复制解旋酶亚基的蛋白水解。我们发现，MCM 2缺失的细胞激活DNA损伤反应途径，并产生复制相关的DNA双链断裂（DSB）。值得注意的是，这些细胞在没有MCM 2的情况下保持一定的DNA合成，这需要MCM 8 -9复合物，MCM 2 -7复制解旋酶的一部分。我们表明，MCM 8 -9的功能在一个同源重组为基础的途径下游的RAD 51，这是促进DSB诱导。这个RAD 51/MCM 8 -9轴与最近描述的RAD 52依赖性DNA合成途径不同，后者在常见的脆性位点的早期有丝分裂中起作用。我们提出，停滞的复制叉可以重新启动，在S期通过同源重组使用MCM 8 -9作为一个替代的复制解旋酶。
Natsume et al. show that MCM2-depleted cells activate a DNA damage response pathway and generate replication-associated DNA double-strand breaks (DSBs). These cells maintain some DNA synthesis in the absence of MCM2, and this requires the MCM8–9 complex, a paralog of the MCM2–7 replicative helicase. DNA replication fork progression can be disrupted at difficult to replicate loci in the human genome, which has the potential to challenge chromosome integrity. This replication fork disruption can lead to the dissociation of the replisome and the formation of DNA damage. To model the events stemming from replisome dissociation during DNA replication perturbation, we used a degron-based system for inducible proteolysis of a subunit of the replicative helicase. We show that MCM2-depleted cells activate a DNA damage response pathway and generate replication-associated DNA double-strand breaks (DSBs). Remarkably, these cells maintain some DNA synthesis in the absence of MCM2, and this requires the MCM8–9 complex, a paralog of the MCM2–7 replicative helicase. We show that MCM8–9 functions in a homologous recombination-based pathway downstream from RAD51, which is promoted by DSB induction. This RAD51/MCM8–9 axis is distinct from the recently described RAD52-dependent DNA synthesis pathway that operates in early mitosis at common fragile sites. We propose that stalled replication forks can be restarted in S phase via homologous recombination using MCM8–9 as an alternative replicative helicase.