CTCF prevents genomic instability by promoting homologous recombination-directed DNA double-strand break repair
CTCF prevents genomic instability by promoting homologous recombination-directed DNA double-strand break repair
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CTCF 通过促进同源重组引导的 DNA 双链断裂修复来防止基因组不稳定
DOI：
10.1073/pnas.1704076114
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发表时间：
2017-10-10
影响因子：
11.1
通讯作者：
Zhou, Jumin
中科院分区：
文献类型：
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作者：
Lang, Fengchao;Li, Xin;Zhou, Jumin
CTCF通过数千个位点与基因组相互作用，并将基因组组织成拓扑结构域，但CTCF是否在维持基因组稳定性方面具有直接功能尚不清楚。在这里，我们报道CTCF耗竭增加染色体不稳定性并激活DNA损伤反应。我们发现，CTCF通过DNA损伤信号传导和CTCF的DNA结合域被招募到DNA损伤位点，CTCF通过与Rad51相互作用，促进Rad51修复病灶的形成，参与DNA双链断裂的同源重组修复。因此，CTCF通过参与DNA修复来维持基因组稳定性，突出了基因组组织与基因组稳定性之间的潜在联系。CTCF是一种重要的表观遗传调控因子，介导染色质绝缘、远程调控相互作用和细胞核中大拓扑结构域的组织。人类CTCF单倍体不足突变、小鼠CTCF基因敲除和细胞耗竭的表型通常与基因组稳定性受损一致，但CTCF在基因组维持中的作用尚未得到充分研究。在这里，我们报道CTCF维持基因组稳定性，被招募到DNA损伤位点，并促进DNA双链断裂（DSBs）的同源重组修复。CTCF缺失增加了染色体不稳定性，表现为染色体断裂和末端融合，基因毒性应激诱导的基因组DNA断裂升高，并激活了共济失调毛细血管扩张突变（ATM）激酶。我们发现CTCF可以被招募到药物诱导的53BP1病灶和已知的脆弱位点，以及I-SceI内切酶诱导的dsb。激光照射分析表明，这种招募依赖于ATM、奈梅根断裂综合征（NBS）和CTCF的锌指dna结合结构域。我们证明CTCF敲低会损害dsb的同源重组（HR）修复。与此一致的是，CTCF敲除减少了γ辐射诱导的Rad51病灶的形成，以及Rad51在DNA损伤激光照射部位和i - scii诱导的dsb中的募集。我们进一步发现CTCF与DNA HR修复因子MDC1和AGO2相关，并通过其C端直接与Rad51相互作用。这些分析建立了CTCF在DNA修复中的直接功能作用，并提供了基因组组织和基因组稳定性之间的潜在联系。
Significance CTCF interacts with the genome through thousands of sites and organizes the genome into topological domains, but whether CTCF has direct functions in the maintenance of genome stability is not known. Here, we report that CTCF depletion increases chromosomal instability and activates the DNA damage response. We show that CTCF is recruited to sites of DNA lesions in a process that depends on DNA damage signaling and the DNA-binding domain of CTCF, and that CTCF participates in homologous recombination repair of DNA double-strand breaks by interacting with Rad51 and promoting Rad51 repair foci formation. Thus, CTCF maintains genome stability by participating in DNA repair, highlighting a potential link between genome organization and genome stability. CTCF is an essential epigenetic regulator mediating chromatin insulation, long-range regulatory interactions, and the organization of large topological domains in the nucleus. Phenotypes of CTCF haploinsufficient mutations in humans, knockout in mice, and depletion in cells are often consistent with impaired genome stability, but a role of CTCF in genome maintenance has not been fully investigated. Here, we report that CTCF maintains genome stability, is recruited to sites of DNA damage, and promotes homologous recombination repair of DNA double-strand breaks (DSBs). CTCF depletion increased chromosomal instability, marked by chromosome breakage and end fusions, elevated genotoxic stress-induced genomic DNA fragmentation, and activated the ataxia telangiectasia mutated (ATM) kinase. We show that CTCF could be recruited to drug-induced 53BP1 foci and known fragile sites, as well as to I-SceI endonuclease-induced DSBs. Laser irradiation analysis revealed that this recruitment depends on ATM, Nijmegen breakage syndrome (NBS), and the zinc finger DNA-binding domain of CTCF. We demonstrate that CTCF knockdown impaired homologous recombination (HR) repair of DSBs. Consistent with this, CTCF knockdown reduced the formation of γ-radiation–induced Rad51 foci, as well as the recruitment of Rad51 to laser-irradiated sites of DNA lesions and to I-SceI–induced DSBs. We further show that CTCF is associated with DNA HR repair factors MDC1 and AGO2, and directly interacts with Rad51 via its C terminus. These analyses establish a direct, functional role of CTCF in DNA repair and provide a potential link between genome organization and genome stability.