Cooperative roles of vertebrate Fbh1 and Blm DNA helicases in avoidance of crossovers during recombination initiated by replication fork collapse
Cooperative roles of vertebrate Fbh1 and Blm DNA helicases in avoidance of crossovers during recombination initiated by replication fork collapse
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DOI：
10.1128/mcb.02043-06
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发表时间：
2007-04-01
影响因子：
5.3
通讯作者：
Takeda, Shunichi
中科院分区：
文献类型：
--
作者：
Kohzaki, Masaoki;Hatanaka, Atsushi;Takeda, Shunichi
FBH1(F-box DNA Helicase 1)同源基因从裂殖酵母到鸡和人都是保守的。在这里，我们报告了在DT40细胞中FBH1基因的破坏。虽然酵母FBH1突变体对DNA损伤剂的敏感性增加，但FBH1(-/-)DT40克隆没有表现出显著的敏感性，这表明FBH1的丢失可能被其他基因补偿。然而，FBH1(-/-)细胞在姐妹染色单体交换和同源染色体之间的放射状结构的形成方面都有所增加，但没有表现出同源重组的缺陷。这种表型使人联想到BLM-/-细胞，并表明FBH1可能参与阻止同源重组过程中广泛的链交换。此外，FBH1(-/-)细胞中的主要同源重组因子RAD54的破坏会导致复制叉停后染色体类型断裂(两个姐妹染色单体在同一位置上的断裂)显著增加。此外，FBH1BLM细胞在姐妹染色单体交换和放射状染色体的形成方面均表现出相加的增加。这些数据表明，FBH1与Bloom解旋酶平行作用，控制重组介导的复制区块的双链断裂修复，并减少交叉频率。
Fbh1 (F-box DNA helicase 1) orthologues are conserved from Schizosaccharomyces pombe to chickens and humans. Here, we report the disruption of the FBH1 gene in DT40 cells. Although the yeast fbh1 mutant shows an increase in sensitivity to DNA damaging agents, FBH1(-/-) DT40 clones show no prominent sensitivity, suggesting that the loss of FBH1 might be compensated by other genes. However, FBH1(-/-) cells exhibit increases in both sister chromatid exchange and the formation of radial structures between homologous chromosomes without showing a defect in homologous recombination. This phenotype is reminiscent of BLM-/- cells and suggests that Fbh1 may be involved in preventing extensive strand exchange during homologous recombination. In addition, disruption of RAD54, a major homologous recombination factor in FBH1(-/-) cells, results in a marked increase in chromosome-type breaks (breaks on both sister chromatids at the same place) following replication fork arrest. Further, FBH1BLM cells showed additive increases in both sister chromatid exchange and the formation of radial chromosomes. These data suggest that Fbh1 acts in parallel with Bloom helicase to control recombination-mediated double-strand-break repair at replication blocks and to reduce the frequency of crossover.