Human fanconi anemia monoubiquitination pathway promotes homologous DNA repair
Human fanconi anemia monoubiquitination pathway promotes homologous DNA repair
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DOI：
10.1073/pnas.0407796102
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发表时间：
2005-01-25
影响因子：
11.1
通讯作者：
Jasin, M
中科院分区：
文献类型：
--
作者：
Nakanishi, K;Yang, YG;Jasin, M
范可尼贫血（FA）是一种隐性疾病，其特征是先天性异常，进行性骨髓衰竭和癌症易感性。来自FA患者的细胞对产生DNA交联的试剂过敏，并且在用这些试剂治疗后，具有明显的染色体断裂和其他细胞遗传学异常。已经克隆了八个FANC基因，并且编码的蛋白质在共同的细胞途径中相互作用。DNA损伤剂激活FANCD 2的单泛素化，导致其靶向也包含BRCA 1和BRCA 2/FANCD 1的核灶，这些蛋白质参与同源定向的DNA修复。考虑到FANC蛋白与BRCA 1和BRCA 2的相互作用，我们测试了来自FA患者（A组，G组和D2组）的细胞和具有靶向突变的小鼠Fanca（-/-）细胞是否受损。我们发现，上游（FANCA和FANCG）和下游（FANCD 2）FA通路组件促进同源性定向修复染色体双链断裂（DSB）。FANCD 2单泛素化位点对于正常修复水平至关重要，而ATM磷酸化位点则不是。然而，这些细胞中的缺陷是轻微的，将它们与BRCA 1和BRCA 2突变细胞区分开来。令人惊讶的是，我们提供的证据表明，这些蛋白质，像BRCA 1，但不像BRCA 2，促进第二个DSB修复途径涉及同源性，即，单链退火。这些结果表明FANC蛋白在同源DSB修复途径选择中的早期作用。
Fanconi anemia (FA) is a recessive disorder characterized by congenital abnormalities, progressive bone-marrow failure, and cancer susceptibility. Cells from FA patients are hypersensitive to agents that produce DNA crosslinks and, after treatment with these agents, have pronounced chromosome breakage and other cytogenetic abnormalities. Eight FANC genes have been cloned, and the encoded proteins interact in a common cellular pathway. DNA-damaging agents activate the monoubiquitination of FANCD2, resulting in its targeting to nuclear foci that also contain BRCA1 and BRCA2/FANCD1, proteins involved in homology-directed DNA repair. Given the interaction of the FANC proteins with BRCA1 and BRCA2, we tested whether cells from FA patients (groups A, G, and D2) and mouse Fanca(-/-) cells with a targeted mutation are impaired for this repair pathway. We find that both the upstream (FANCA and FANCG) and downstream (FANCD2) FA pathway components promote homology-directed repair of chromosomal double-strand breaks (DSBs). The FANCD2 monoubiquitination site is critical for normal levels of repair, whereas the ATM phosphorylation site is not. The defect in these cells, however, is mild, differentiating them from BRCA1 and BRCA2 mutant cells. Surprisingly, we provide evidence that these proteins, like BRCA1 but unlike BRCA2, promote a second DSB repair pathway involving homology, i.e., single-strand annealing. These results suggest an early role for the FANC proteins in homologous DSB repair pathway choice.