Homologous recombination repair is regulated by domains at the N- and C-terminus of NBS1 and is dissociated with ATM functions
Homologous recombination repair is regulated by domains at the N- and C-terminus of NBS1 and is dissociated with ATM functions
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DOI：
10.1038/sj.onc.1210428
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发表时间：
2007-09-01
期刊：
影响因子：
8
通讯作者：
Komatsu, K.
中科院分区：
文献类型：
--
作者：
Sakamoto, S.;Iijima, K.;Komatsu, K.
负责辐射敏感性疾病的蛋白质，NBS 1，激酶共济失调-毛细血管扩张-（A-T）-突变（ATM）和MRE 11，通过NBS 1的C-末端相互作用以响应DNA双链断裂（DSB）的产生，并且都涉及检查点调节和DSB修复，例如同源重组（HR）.我们使用DR-GFP或SCneo系统测量了几种NBS 1突变克隆和A-T细胞调节HR修复的能力。ATM缺陷没有降低诱导的DSB的HR修复频率，并且通过以下发现证实了HR频率仅受到NBS 1的最末端C末端处的ATM结合位点的缺失的轻微影响。相反，通过在NBS 1的C-末端缺失MRE 11-结合结构域，HR调节能力显著降低，并且通过在N-末端的FHA/ BRCT结构域中的突变显著抑制。HR的这种受损能力与未能观察到MRE 11病灶形成一致。此外，使用姐妹染色单体的正常HR被FHA/ BRCT结构域的缺失完全抑制。这些结果表明，NBS 1的N-和C-末端结构域是HR途径的主要调节结构域，很可能通过以ATM-非依赖性方式将MRE 11核酸酶募集和保留到DSB位点。
The proteins responsible for radiation sensitive disorders, NBS1, kinase ataxia- telangiectasia-( A- T)- mutated ( ATM) and MRE11, interact through the C- terminus of NBS1 in response to the generation of DNA double- strand breaks ( DSBs) and are all implicated in checkpoint regulation and DSB repair, such as homologous recombination ( HR). We measured the ability of several NBS1 mutant clones and A- T cells to regulate HR repair using the DR- GFP or SCneo systems. ATM deficiency did not reduce the HR repair frequency of an induced DSB, and it was confirmed by findings that HR frequencies are only slightly affected by deletion of ATM- binding site at the extreme C-terminus of NBS1. In contrast, The HR- regulating ability is dramatically reduced by deletion of the MRE11- binding domain at the C- terminus of NBS1 and markedly inhibited by mutations in the FHA/ BRCT domains at the N- terminus. This impaired capability in HR is consistent with a failure to observe MRE11 foci formation. Furthermore, normal HR using sister chromatid was completely inhibited by the absence of FHA/ BRCT domains. These results suggested that the N- and C- terminal domains of NBS1 are the major regulatory domains for HR pathways, very likely through the recruitment and retention of the MRE11 nuclease to DSB sites in an ATM-independent fashion.