ERCC1-XPF endonuclease facilitates DNA double-strand break repair
ERCC1-XPF endonuclease facilitates DNA double-strand break repair
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DOI：
10.1128/mcb.00293-08
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发表时间：
2008-08-01
影响因子：
5.3
通讯作者：
Niedernhofer, Laura J.
中科院分区：
文献类型：
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作者：
Ahmad, Anwaar;Robinson, Andria Rasile;Niedernhofer, Laura J.
ERCC 1-XPF核酸内切酶是螺旋扭曲DNA损伤的核苷酸切除修复（NER）所必需的。然而，ERCC 1或XPF在人类或小鼠中的突变导致比NER缺失更严重的表型，促使人们寻找核酸酶的新修复活性。在酿酒酵母中，ERCC 1-XPF（Rad 10-Rad 1）的直系同源物参与双链断裂（DSB）的修复。Rad 10-Rad 1参与了两种易错的DSB修复途径：微同源介导的末端连接（Ku 86独立机制）和单链退火。为了确定ERCC 1-XPF是否参与哺乳动物的DSB修复，筛选突变细胞和小鼠对γ辐射的敏感性。ERCC 1-XPF缺陷型成纤维细胞对γ射线超敏感，γ H2 AX病灶（DSB的标志物）在辐照的突变细胞中持续存在，与DSB修复缺陷一致。突变小鼠也对辐射过敏，建立了ERCC 1-XPF在体内保护免受DSB的重要作用。ERCC 1-XPF和Ku 86缺陷的小鼠不能存活。然而，Ercc 1（-/-）Ku 86（-/-）成纤维细胞是超敏感的γ射线相比，单突变体和积累显着更大的染色体畸变。最后，具有3'突出端的DSB的体外修复在不存在ERCC 1-XPF的情况下导致大的缺失。这些数据支持的结论是，在酵母中，ERCC 1-XPF通过末端连接机制，这是Ku 86独立的促进DSB修复。
ERCC1-XPF endonuclease is required for nucleotide excision repair (NER) of helix-distorting DNA lesions. However, mutations in ERCC1 or XPF in humans or mice cause a more severe phenotype than absence of NER, prompting a search for novel repair activities of the nuclease. In Saccharomyces cerevisiae, orthologs of ERCC1-XPF (Rad10-Rad1) participate in the repair of double-strand breaks (DSBs). Rad10-Rad1 contributes to two error-prone DSB repair pathways: microhomology-mediated end joining (a Ku86-independent mechanism) and single-strand annealing. To determine if ERCC1-XPF participates in DSB repair in mammals, mutant cells and mice were screened for sensitivity to gamma irradiation. ERCC1-XPF-deficient fibroblasts were hypersensitive to gamma irRadiation, and gamma H2AX foci, a marker of DSBs, persisted in irradiated mutant cells, consistent with a defect in DSB repair. Mutant mice were also hypersensitive to irradiation, establishing an essential role for ERCC1-XPF in protecting against DSBs in vivo. Mice defective in both ERCC1-XPF and Ku86 were not viable. However, Ercc1(-/-) Ku86(-/-) fibroblasts were hypersensitive to gamma irradiation compared to single mutants and accumulated significantly greater chromosomal aberrations. Finally, in vitro repair of DSBs with 3' overhangs led to large deletions in the absence of ERCC1-XPF. These data support the conclusion that, as in yeast, ERCC1-XPF facilitates DSB repair via an end-joining mechanism that is Ku86 independent.