ATM release at resected double-strand breaks provides heterochromatin reconstitution to facilitate homologous recombination.
ATM release at resected double-strand breaks provides heterochromatin reconstitution to facilitate homologous recombination.
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DOI：
10.1371/journal.pgen.1003667
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发表时间：
2013
期刊：
影响因子：
4.5
通讯作者：
Löbrich M
中科院分区：
文献类型：
--
作者：
Geuting V;Reul C;Löbrich M
非同源末端连接(NHEJ)和同源重组(HR)是修复DNA双链断裂的两条主要途径。在哺乳动物细胞周期的G2期，两个过程都可以进行，染色质结构是决定DSB修复途径选择的重要因素之一。ATM通过磷酸化和失活异染色质构建因子KAP-1来促进异染色质DSB的修复，导致局部染色质松弛。在这里，我们显示在HR期间接受末端切除的DSB中ATM的积聚和活性显著减少。在缺乏HR因子BRCA2、XRCC3或RAD51的细胞中，这种DSB仍然没有修复。值得注意的是，KAP-1的缺失或磷酸化模拟KAP-1的表达允许在缺乏BRCA2、XRCC3或RAD51的情况下通过错误的依赖PARP的ALT-NHEJ过程修复被切除的DSB。我们认为，异染色质中的DSB引起最初的局部异染色质松弛，而在HR期间，由于ATM从切除断端释放，这种松弛作用被逆转。恢复的异色结构有助于HR并防止使用容易出错的替代工艺。双链断裂(DSB)是关键的DNA损伤，因为它们可以导致细胞死亡，或者更具破坏性的是，形成基因组重排。细胞有两条修复损伤的主要途径，同源重组(HR)和非同源末端连接(NHEJ)。HR是一个没有错误的过程，可以完全恢复遗传信息，而NHEJ有可能形成基因组重排。我们先前已经证明，染色质的结构是决定这两条途径之间选择的一个重要因素，这样定位于高浓缩异染色区的DSB主要由HR修复，而更开放的常染DNA断裂则由NHEJ修复。在这里，我们研究DSB修复途径选择的这一方面。我们发现，DSB末端切除将DSB修复引导到HR的过程中，抵消了最初发生在断裂位置的深刻的局部松弛，并重新构建了异色结构。经过基因改造的细胞不能在切除的DSB处重建异染结构，它们不能利用HR，而是通过替代的NHEJ机制修复异色DSB。因此，在末端切除过程中发生的染色质修饰防止了容易出错的修复途径产生基因组重排。
Non-homologous end-joining (NHEJ) and homologous recombination (HR) represent the two main pathways for repairing DNA double-strand breaks (DSBs). During the G2 phase of the mammalian cell cycle, both processes can operate and chromatin structure is one important factor which determines DSB repair pathway choice. ATM facilitates the repair of heterochromatic DSBs by phosphorylating and inactivating the heterochromatin building factor KAP-1, leading to local chromatin relaxation. Here, we show that ATM accumulation and activity is strongly diminished at DSBs undergoing end-resection during HR. Such DSBs remain unrepaired in cells devoid of the HR factors BRCA2, XRCC3 or RAD51. Strikingly, depletion of KAP-1 or expression of phospho-mimic KAP-1 allows repair of resected DSBs in the absence of BRCA2, XRCC3 or RAD51 by an erroneous PARP-dependent alt-NHEJ process. We suggest that DSBs in heterochromatin elicit initial local heterochromatin relaxation which is reversed during HR due to the release of ATM from resection break ends. The restored heterochromatic structure facilitates HR and prevents usage of error-prone alternative processes. Double-strand breaks (DSBs) are critical DNA lesions because they can lead to cell death or, which is even more devastating, the formation of genomic rearrangements. Cells are equipped with two main pathways to repair such lesions, homologous recombination (HR) and non-homologous end-joining (NHEJ). HR is an error-free process and completely restores the genetic information, whereas NHEJ has the potential to form genomic rearrangements. We have previously shown that the structure of the chromatin is one important factor which determines the choice between these two pathways, such that DSBs localizing to highly condensed heterochromatic regions are mainly repaired by HR and breaks in more open euchromatic DNA undergo repair by NHEJ. Here, we investigate this aspect of DSB repair pathway choice. We show that DSB end-resection, which channels DSB repair into the process of HR, counteracts the profound local relaxation which initially takes place at the break site and reconstitutes the heterochromatic structure. Cells which are genetically modified, such that they cannot reconstitute the heterochromatic structure at resected DSBs, fail to employ HR and instead repair heterochromatic DSBs by alternative NHEJ mechanisms. Thus, chromatin modifications which occur during the process of end-resection prevent error-prone repair pathways from generating genomic rearrangements.
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影响因子：
5.7
作者：
Jeggo, Penny A.;Geuting, Verena;Loebrich, Markus
通讯作者：
Loebrich, Markus
DOI：
10.1073/pnas.0915067107
发表时间：
2010-02-16
影响因子：
11.1
作者：
Boboila, Cristian;Jankovic, Mila;Alt, Frederick W.
通讯作者：
Alt, Frederick W.
影响因子：
21.3
作者：
Jazayeri, A;Falck, J;Jackson, SP
通讯作者：
Jackson, SP
影响因子：
4
作者：
Chapman, J. Ross;Sossick, Alex J.;Jackson, Stephen P.
通讯作者：
Jackson, Stephen P.
影响因子：
64.8
作者：
Ayoub, Nabieh;Jeyasekharan, Anand D.;Venkitaraman, Ashok R.
通讯作者：
Venkitaraman, Ashok R.