Regulation of homologous recombinational repair by lamin B1 in radiation-induced DNA damage
Regulation of homologous recombinational repair by lamin B1 in radiation-induced DNA damage
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DOI：
10.1096/fj.14-265546
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发表时间：
2015-06-01
期刊：
影响因子：
4.8
通讯作者：
Tashiro, Satoshi
中科院分区：
文献类型：
--
作者：
Liu, Ning-Ang;Sun, Jiying;Tashiro, Satoshi
DNA双链断裂(DSB)是电离辐射(IR)引起的主要致命性损伤。RAD51依赖的同源重组(HR)是DSB修复和基因组完整性维持的重要途径之一。然而，RAD51对HR的调节机制尚不清楚。为了了解RAD51依赖的HR的机制，我们通过蛋白质组学分析寻找RAD51的相互作用伙伴，并在人类细胞中鉴定了lamin B1。层粘连蛋白是一种核层蛋白，在细胞核的结构组织和染色体功能的调节中发挥重要作用。免疫印迹分析表明，siRNA介导的lamin B1缺失抑制了IR后RAD51的DNA损伤依赖性增加。这种抑制被蛋白酶体抑制剂MG132取消，这表明Lamin B1通过防止蛋白酶体介导的降解在IR诱导的DNA损伤细胞中稳定RAD51。我们还发现，层蛋白B1的缺失抑制了RAD51病灶的形成，并降低了IR后的存活率。在这些结果的基础上，我们认为Lamin B1通过在IR后DSB诱导时维持HR的RAD51蛋白水平来促进DSB修复和细胞存活。
DNA double-strand breaks (DSBs) are the major lethal lesion induced by ionizing radiation (IR). RAD51-dependent homologous recombination (HR) is one of the most important pathways in DSB repair and genome integrity maintenance. However, the mechanism of HR regulation by RAD51 remains unclear. To understand the mechanism of RAD51-dependent HR, we searched for interacting partners of RAD51 by a proteomics analysis and identified lamin B1 in human cells. Lamins are nuclear lamina proteins that play important roles in the structural organization of the nucleus and the regulation of chromosome functions. Immunoblotting analyses revealed that siRNA-mediated lamin B1 depletion repressed the DNA damage-dependent increase of RAD51 after IR. The repression was abolished by the proteasome inhibitor MG132, suggesting that lamin B1 stabilizes RAD51 by preventing proteasome-mediated degradation in cells with IR-induced DNA damage. We also showed that lamin B1 depletion repressed RAD51 focus formation and decreased the survival rates after IR. On the basis of these results, we propose that lamin B1 promotes DSB repair and cell survival by maintaining the RAD51 protein levels for HR upon DSB induction after IR.