Costanzo V, Robertson K, Bibikova M, Kim E, Grieco D, Gottesman M, Carroll D, Gautier J
Department of Genetics and Development, Columbia University, New York, NY 10032, USA.
Mol Cell. 2001 Jul;8(1):137-47. doi: 10.1016/s1097-2765(01)00294-5.
Mre11 complex promotes repair of DNA double-strand breaks (DSBs). Xenopus Mre11 (X-Mre11) has been cloned, and its role in DNA replication and DNA damage checkpoint studied in cell-free extracts. DSBs stimulate the phosphorylation and 3'-5' exonuclease activity of X-Mre11 complex. This induced phosphorylation is ATM independent. Phosphorylated X-Mre11 is found associated with replicating nuclei. X-Mre11 complex is required to yield normal DNA replication products. Genomic DNA replicated in extracts immunodepleted of X-Mre11 complex accumulates DSBs as demonstrated by TUNEL assay and reactivity to phosphorylated histone H2AX antibodies. In contrast, the ATM-dependent DNA damage checkpoint that blocks DNA replication initiation is X-Mre11 independent. These results strongly suggest that the function of X-Mre11 complex is to repair DSBs that arise during normal DNA replication, thus unraveling a critical link between recombination-dependent repair and DNA replication.
Mre11复合物促进DNA双链断裂（DSB）的修复。非洲爪蟾的Mre11（X-Mre11）已被克隆，并在无细胞提取物中研究了其在DNA复制和DNA损伤检查点中的作用。DSB刺激X-Mre11复合物的磷酸化和3'-5'核酸外切酶活性。这种诱导的磷酸化不依赖于ATM。磷酸化的X-Mre11被发现与复制细胞核相关。产生正常的DNA复制产物需要X-Mre11复合物。如TUNEL检测和对磷酸化组蛋白H2AX抗体的反应性所示，在免疫去除X-Mre11复合物的提取物中复制的基因组DNA积累了DSB。相反，阻断DNA复制起始的ATM依赖性DNA损伤检查点不依赖于X-Mre11。这些结果强烈表明，X-Mre11复合物的功能是修复正常DNA复制过程中出现的DSB，从而揭示了重组依赖性修复与DNA复制之间的关键联系。
