Regulation of pairing between broken DNA-containing chromatin regions by Ku80, DNA-PKcs, ATM, and 53BP1.
Regulation of pairing between broken DNA-containing chromatin regions by Ku80, DNA-PKcs, ATM, and 53BP1.
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DOI：
10.1038/srep41812
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发表时间：
2017-02-03
影响因子：
4.6
通讯作者：
Matsuda N
中科院分区：
文献类型：
--
作者：
Yamauchi M;Shibata A;Suzuki K;Suzuki M;Niimi A;Kondo H;Miura M;Hirakawa M;Tsujita K;Yamashita S;Matsuda N
由于染色体重排可产生致癌融合基因，因此具有重要的临床和生理意义。染色体重排需要在两个基因组位置处的DNA双链断裂（DSB）和DSB之间的错接。在DSB重新连接之前，两个含有DSB的染色质区域移动并彼此配对;然而，这一过程的分子机制在很大程度上是未知的。我们进行了电离辐射诱导的p53结合蛋白1（53 BP 1），含DSB染色质的标志物的病灶的时空分析。我们发现一些53 BP 1灶是成对的，表明两个受损的染色质区域彼此相邻。我们寻找调节病灶配对的因素，发现当Ku 80、DNA-PKcs或ATM不存在时，配对病灶的数量增加。相反，53 BP 1耗竭减少了成对病灶和双着丝粒染色体的数量-染色体间重排。在对照细胞中，异染色质中的病灶比常染色质中的病灶更频繁地配对。此外，53 BP 1耗尽细胞中减少的病灶配对被异染色质构建因子如Krüppel相关盒相关蛋白1或染色体结构域解旋酶DNA结合蛋白3的伴随耗尽所拯救。这些发现表明，含有DSB的染色质区域之间的配对被Ku 80、DNA-PKcs和ATM抑制，并且这种配对被53 BP 1通过染色质松弛促进。
Chromosome rearrangement is clinically and physiologically important because it can produce oncogenic fusion genes. Chromosome rearrangement requires DNA double-strand breaks (DSBs) at two genomic locations and misrejoining between the DSBs. Before DSB misrejoining, two DSB-containing chromatin regions move and pair with each other; however, the molecular mechanism underlying this process is largely unknown. We performed a spatiotemporal analysis of ionizing radiation-induced foci of p53-binding protein 1 (53BP1), a marker for DSB-containing chromatin. We found that some 53BP1 foci were paired, indicating that the two damaged chromatin regions neighboured one another. We searched for factors regulating the foci pairing and found that the number of paired foci increased when Ku80, DNA-PKcs, or ATM was absent. In contrast, 53BP1 depletion reduced the number of paired foci and dicentric chromosomes—an interchromosomal rearrangement. Foci were paired more frequently in heterochromatin than in euchromatin in control cells. Additionally, the reduced foci pairing in 53BP1-depleted cells was rescued by concomitant depletion of a heterochromatin building factor such as Krüppel-associated box-associated protein 1 or chromodomain helicase DNA-binding protein 3. These findings indicate that pairing between DSB-containing chromatin regions was suppressed by Ku80, DNA-PKcs, and ATM, and this pairing was promoted by 53BP1 through chromatin relaxation.