Mode of ATM-dependent suppression of chromosome translocation.
Mode of ATM-dependent suppression of chromosome translocation.
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ATM 依赖性染色体易位抑制模式。
DOI：
10.1016/j.bbrc.2011.11.006
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Yamashita S
中科院分区：
文献类型：
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作者：
Yamauchi M;Suzuki K;Oka Y;Suzuki M;Kondo H;Yamashita S
共济失调毛细血管扩张突变蛋白（ATM）的缺乏导致染色体易位频率的升高，这是有据可查的，然而，ATM如何抑制易位频率仍然知之甚少。在本研究中，我们探讨了ATM依赖性抑制易位频率的机制。为了立即了解整个基因组中易位事件的频率，我们进行了着丝粒/端粒FISH并对双着丝粒染色体进行评分，因为双着丝粒和易位以相同的频率和相同的机制发生。通过着丝粒/端粒FISH分析，我们证实了化学抑制或RNAi介导的ATM敲低导致G 0/G1期2Gy γ射线照射后第一次有丝分裂时双着丝粒频率增加2至2.5倍。FISH分析显示ATM/p53依赖的G1检查点抑制双着丝粒频率，因为RNAi介导的p53敲低使双着丝粒频率升高1.5倍。我们发现ATM也抑制双着丝粒发生独立的检查点的作用，ATM抑制剂显示额外的影响双着丝粒频率的背景下，p53耗竭和Chk 1/2失活。使用化学抑制剂的上位性分析表明，ATM激酶的功能在相同的途径，需要DNA依赖性蛋白激酶催化亚基（DNA-PKcs）的激酶活性，以抑制双着丝粒频率。从本研究的结果，我们得出结论，ATM通过其承诺G1检查点和DNA双链断裂修复途径，需要激酶活性的DNA-PKcs的易位频率最小化。
It is well documented that deficiency in ataxia telangiectasia mutated (ATM) protein leads to elevated frequency of chromosome translocation, however, it remains poorly understood how ATM suppresses translocation frequency. In the present study, we addressed the mechanism of ATM-dependent suppression of translocation frequency. To know frequency of translocation events in a whole genome at once, we performed centromere/telomere FISH and scored dicentric chromosomes, because dicentric and translocation occur with equal frequency and by identical mechanism. By centromere/telomere FISH analysis, we confirmed that chemical inhibition or RNAi-mediated knockdown of ATM causes 2 to 2.5-fold increase in dicentric frequency at first mitosis after 2Gy of gamma-irradiation in G0/G1. The FISH analysis revealed that ATM/p53-dependent G1 checkpoint suppresses dicentric frequency, since RNAi-mediated knockdown of p53 elevated dicentric frequency by 1.5-fold. We found ATM also suppresses dicentric occurrence independently of its checkpoint role, as ATM inhibitor showed additional effect on dicentric frequency in the context of p53 depletion and Chk1/2 inactivation. Epistasis analysis using chemical inhibitors revealed that ATM kinase functions in the same pathway that requires kinase activity of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) to suppress dicentric frequency. From the results in the present study, we conclude that ATM minimizes translocation frequency through its commitment to G1 checkpoint and DNA double-strand break repair pathway that requires kinase activity of DNA-PKcs.