Coordinated nuclease activities counteract Ku at single-ended DNA double-strand breaks.
Coordinated nuclease activities counteract Ku at single-ended DNA double-strand breaks.
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DOI：
10.1038/ncomms12889
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发表时间：
2016-09-19
影响因子：
16.6
通讯作者：
Calsou, Patrick
中科院分区：
文献类型：
--
作者：
Chanut, Pauline;Britton, Sebastien;Coates, Julia;Jackson, Stephen P.;Calsou, Patrick
通过同源重组（HR）修复单端DNA双链断裂（seDSBs）需要在DNA切除过程中通过外切酶活性产生3 '单链DNA悬垂。然而，预计高度丰富的DNA末端结合蛋白Ku将sedsb隔离并保护它们免受外切酶活性的影响。尽管在酵母中进行了开创性的研究，但尚不清楚哺乳动物细胞如何在sedsb中和Ku以使HR继续进行。本研究表明，在人类细胞中，atm依赖的CtIP磷酸化、MRE11和CtIP核酸酶活性的上位性和协同作用是限制Ku在sedsb上稳定加载的必要条件。我们还提供了迄今为止未被怀疑的额外机制的证据，该机制有助于阻止Ku在sedsb上的积累，该机制作用于MRE11内切酶活性的下游，并与MRE11外切酶活性平行。最后，我们发现Ku在seDSBs上的持久性会影响Rad51焦点的组装，但不会影响DNA的切除。同源重组需要在断裂位点末端切除DNA，而Ku二聚体可以隔离单端双链断裂。在这里，作者表明，atm依赖的CtIP磷酸化，以及Mre11的作用，损害了Ku在DNA上的稳定加载。
Repair of single-ended DNA double-strand breaks (seDSBs) by homologous recombination (HR) requires the generation of a 3′ single-strand DNA overhang by exonuclease activities in a process called DNA resection. However, it is anticipated that the highly abundant DNA end-binding protein Ku sequesters seDSBs and shields them from exonuclease activities. Despite pioneering works in yeast, it is unclear how mammalian cells counteract Ku at seDSBs to allow HR to proceed. Here we show that in human cells, ATM-dependent phosphorylation of CtIP and the epistatic and coordinated actions of MRE11 and CtIP nuclease activities are required to limit the stable loading of Ku on seDSBs. We also provide evidence for a hitherto unsuspected additional mechanism that contributes to prevent Ku accumulation at seDSBs, acting downstream of MRE11 endonuclease activity and in parallel with MRE11 exonuclease activity. Finally, we show that Ku persistence at seDSBs compromises Rad51 focus assembly but not DNA resection. Homologous recombination requires end resection of the DNA at the site of the break, however the Ku dimer can sequester single-ended double-strand breaks. Here the authors show that ATM-dependent phosphorylation of CtIP, along with the actions of Mre11, impair the stable loading of Ku onto DNA.
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影响因子：
4.8
作者：
Furuta, T;Takemura, H;Pommier, Y
通讯作者：
Pommier, Y
影响因子：
14.9
作者：
Jensen KL;Russell P
通讯作者：
Russell P
影响因子：
64.5
作者：
Buis J;Wu Y;Deng Y;Leddon J;Westfield G;Eckersdorff M;Sekiguchi JM;Chang S;Ferguson DO
通讯作者：
Ferguson DO
DOI：
10.1083/jcb.201204035
发表时间：
2012-08-06
期刊：
The Journal of cell biology
影响因子：
--
作者：
Daniel JA;Pellegrini M;Lee BS;Guo Z;Filsuf D;Belkina NV;You Z;Paull TT;Sleckman BP;Feigenbaum L;Nussenzweig A
通讯作者：
Nussenzweig A
影响因子：
8.8
作者：
Balestrini, Alessia;Ristic, Dejan;Petrini, John H. J.
通讯作者：
Petrini, John H. J.