The SNF2 family ATPase LSH promotes phosphorylation of H2AX and efficient repair of DNA double-strand breaks in mammalian cells
The SNF2 family ATPase LSH promotes phosphorylation of H2AX and efficient repair of DNA double-strand breaks in mammalian cells
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DOI：
10.1242/jcs.111252
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发表时间：
2012-11-15
影响因子：
4
通讯作者：
Stancheva, Irina
中科院分区：
文献类型：
--
作者：
Burrage, Joe;Termanis, Ausma;Stancheva, Irina
LSH是一种与染色质重塑ATPase SNF2家族相关的蛋白质，对于植物和哺乳动物细胞中DNA甲基化水平和模式的正确建立是必不可少的。然而，由于LSH缺乏导致的一些表型不能很容易地用DNA甲基化缺陷来解释。在这里，我们显示缺乏LSH的小鼠和人类成纤维细胞暴露在电离辐射后活性降低，修复DNA双链断裂的效率低于野生型细胞。对这一表型的更详细的特征表明，在没有LSH的情况下，组蛋白变体H2AX不能有效地磷酸化来响应DNA损伤。这导致MDC1和53BP1蛋白在DNA双链断裂中的募集受损，并损害了检查点激酶Chk2的磷酸化。此外，我们还证明了LSH水解三磷酸腺苷的能力是DNA双链断裂时H_2AX有效磷酸化和成功修复DNA损伤所必需的。综上所述，我们的数据揭示了LSH ATPase在哺乳动物体细胞中维持基因组稳定性的先前未知的作用，这与其在发育过程中从头开始DNA甲基化的功能无关。
LSH, a protein related to the SNF2 family of chromatin-remodelling ATPases, is essential for the correct establishment of DNA methylation levels and patterns in plants and mammalian cells. However, some of the phenotypes resulting from LSH deficiency cannot be explained easily by defects in DNA methylation. Here we show that LSH-deficient mouse and human fibroblasts show reduced viability after exposure to ionizing radiation and repair DNA double-strand breaks less efficiently than wild-type cells. A more detailed characterisation of this phenotype revealed that, in the absence of LSH, the histone variant H2AX is not efficiently phosphorylated in response to DNA damage. This results in impaired recruitment of MDC1 and 53BP1 proteins to DNA double-strand breaks and compromises phosphorylation of checkpoint kinase CHK2. Furthermore, we demonstrate that the ability of LSH to hydrolyse ATP is necessary for efficient phosphorylation of H2AX at DNA double-strand breaks and successful repair of DNA damage. Taken together, our data reveal a previously unsuspected role of LSH ATPase in the maintenance of genome stability in mammalian somatic cells, which is independent of its function in de novo DNA methylation during development.