Kim Jun Hyun, Grosbart Malgorzata, Anand Roopesh, Wyman Claire, Cejka Petr, Petrini John H J
Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10021, USA.
Department of Molecular Genetics, Erasmus University Medical Center, 3000 Rotterdam, the Netherlands; Department of Radiation Oncology, Erasmus University Medical Center, 3000 Rotterdam, the Netherlands.
Cell Rep. 2017 Jan 10;18(2):496-507. doi: 10.1016/j.celrep.2016.12.035.
The Mre11 complex (Mre11, Rad50, and Nbs1) is integral to both DNA repair and ataxia telangiectasia mutated (ATM)-dependent DNA damage signaling. All three Mre11 complex components are essential for viability at the cellular and organismal levels. To delineate essential and non-essential Mre11 complex functions that are mediated by Nbs1, we used TALEN-based genome editing to derive Nbs1 mutant mice (Nbs1 mice), which harbor mutations in the Mre11 interaction domain of Nbs1. Nbs1 alleles that abolished interaction were incompatible with viability. Conversely, a 108-amino-acid Nbs1 fragment comprising the Mre11 interface was sufficient to rescue viability and ATM activation in cultured cells and support differentiation of hematopoietic cells in vivo. These data indicate that the essential role of Nbs1 is via its interaction with Mre11 and that most of the Nbs1 protein is dispensable for Mre11 complex functions and suggest that Mre11 and Rad50 directly activate ATM.
Mre11复合物（Mre11、Rad50和Nbs1）对于DNA修复以及共济失调毛细血管扩张症突变（ATM）依赖的DNA损伤信号传导而言不可或缺。Mre11复合物的所有三个组分对于细胞和机体水平的生存能力都是必不可少的。为了阐明由Nbs1介导的Mre11复合物的必需和非必需功能，我们使用基于转录激活样效应因子核酸酶（TALEN）的基因组编辑技术来培育Nbs1突变小鼠（Nbs1小鼠），这些小鼠在Nbs1的Mre11相互作用结构域中存在突变。消除相互作用的Nbs1等位基因与生存能力不兼容。相反，包含Mre11界面的一个108个氨基酸的Nbs1片段足以挽救培养细胞中的生存能力和ATM激活，并支持体内造血细胞的分化。这些数据表明，Nbs1的重要作用是通过其与Mre11的相互作用实现的，并且Nbs1蛋白的大部分对于Mre11复合物的功能而言是可有可无的，这表明Mre11和Rad50直接激活ATM。
