Depletion of CHK1, but not CHK2, induces chromosomal instability and breaks at common fragile sites
Depletion of CHK1, but not CHK2, induces chromosomal instability and breaks at common fragile sites
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DOI：
10.1038/sj.onc.1209466
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发表时间：
2006-07-01
期刊：
影响因子：
8
通讯作者：
Glover, T. W.
中科院分区：
文献类型：
--
作者：
Durkin, S. G.;Arlt, M. F.;Glover, T. W.
常见的脆弱位点是基因组的特定区域，当DNA合成部分受到抑制时，在中期染色体上形成间隙和断裂。脆弱位点及其相关基因在癌细胞中表现出频繁的缺失和其他重排，可能是肿瘤发生早期DNA复制应激的指标。我们之前已经证明DNA损伤反应蛋白ATR、BRCA1和FANCD2在维持脆弱位点区域的稳定性中起着关键作用。为了进一步阐明调节脆弱位点稳定性的途径，我们研究了细胞周期检查点激酶CHK1和CHK2的耗尽对人类细胞中常见脆弱位点稳定性的影响。我们证明，CHK1和CHK2在用低剂量阿希霉素处理细胞后都被激活，从而诱导脆弱部位断裂。此外，我们表明，使用短干扰RNA （siRNA）耗尽CHK1，而不是CHK2，会导致染色体高度不稳定和特定的常见脆性位点断裂。在许多细胞中，CHK1缺失导致广泛的染色体断裂，这与通常与细胞凋亡相关的核内溶解分裂不同。这些发现证明了CHK1激酶在调节染色体稳定性，特别是普通脆性位点稳定性中的关键作用。
Common fragile sites are specific regions of the genome that form gaps and breaks on metaphase chromosomes when DNA synthesis is partially inhibited. Fragile sites and their associated genes show frequent deletions and other rearrangements in cancer cells, and may be indicators of DNA replication stress early in tumorigenesis. We have previously shown that the DNA damage response proteins ATR, BRCA1 and FANCD2 play critical roles in maintaining the stability of fragile site regions. To further elucidate the pathways regulating fragile site stability, we have investigated the effects of depletion of the cell cycle checkpoint kinases, CHK1 and CHK2 on common fragile site stability in human cells. We demonstrate that both CHK1 and CHK2 are activated following treatment of cells with low doses of aphidicolin that induce fragile site breakage. Furthermore, we show that depletion of CHK1, but not CHK2, using short-interfering RNA (siRNA) leads to highly destabilized chromosomes and specific common fragile site breakage. In many cells, CHK1 depletion resulted in extensive chromosome fragmentation, which was distinct from endonucleolytic cleavage commonly associated with apoptosis. These findings demonstrate a critical role for the CHK1 kinase in regulating chromosome stability, and in particular, common fragile site stability.