XLF interacts with the XRCC4-DNA ligase IV complex to promote DNA nonhomologous end-joining
XLF interacts with the XRCC4-DNA ligase IV complex to promote DNA nonhomologous end-joining
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DOI：
10.1016/j.cell.2005.12.031
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发表时间：
2006-01-27
期刊：
影响因子：
64.5
通讯作者：
Jackson, SP
中科院分区：
文献类型：
--
作者：
Ahnesorg, P;Smith, P;Jackson, SP
DNA非同源末端连接（NHEJ）是哺乳动物细胞中DNA双链断裂修复的主要途径，其缺陷会导致细胞和生物体水平的辐射敏感性。NHEJ的核心是含有DNA连接酶IV和XRCC4的蛋白质复合物。通过寻找其他XRCC4相互作用因子，我们发现了一个以前未被鉴定的33 kDa蛋白，XRCC4样因子（XLF，也称为Cernunnos），与XRCC4具有弱序列同源性，预计与XRCC4具有结构相似性。在体外和体内实验中，我们发现XLF直接与xrcc4 -连接酶IV复合物相互作用，并且在人细胞系中，sirna介导的XLF下调会导致放射敏感性和NHEJ受损。此外，我们证实来自放射敏感和免疫缺陷患者的NHEJ缺陷20亿细胞由于其基因的移位突变失活而缺乏XLF，并且将野生型XLF重新引入这些细胞中可以纠正其放射敏感性和NHEJ缺陷。因此，XLF构成了哺乳动物NHEJ装置的新型核心组件。
DNA nonhomologous end-joining (NHEJ) is a predominant pathway of DNA double-strand break repair in mammalian cells, and defects in it cause radiosensitivity at the cellular and whole-organism levels. Central to NHEJ is the protein complex containing DNA Ligase IV and XRCC4. By searching for additional XRCC4-interacting factors, we identified a previously uncharacterized 33 kDa protein, XRCC4-like factor (XLF, also named Cernunnos), that has weak sequence homology with XRCC4 and is predicted to display structural similarity to XRCC4. We show that XLF directly interacts with the XRCC4-Ligase IV complex in vitro and in vivo and that siRNA-mediated downregulation of XLF in human cell lines leads to radiosensitivity and impaired NHEJ. Furthermore, we establish that NHEJ-deficient 2BN cells derived from a radiosensitive and immune-deficient patient lack XLF due to an inactivating frameshift mutation in its gene, and that reintroduction of wild-type XLF into such cells corrects their radiosensitivity and NHEJ defects. XLF thus constitutes a novel core component of the mammalian NHEJ apparatus.