TIS21/BTG2/PC3 accelerates the repair of DNA double strand breaks by enhancing Mre11 methylation and blocking damage signal transfer to the Chk2T68-p53S20 pathway
TIS21/BTG2/PC3 accelerates the repair of DNA double strand breaks by enhancing Mre11 methylation and blocking damage signal transfer to the Chk2T68-p53S20 pathway
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DOI：
10.1016/j.dnarep.2012.09.009
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发表时间：
2012-12-01
期刊：
影响因子：
3.8
通讯作者：
Lim, In Young
中科院分区：
文献类型：
--
作者：
Choi, Kyu-Sung;Kim, Ji Yeon;Lim, In Young
DNA双链断裂（DSB）在TIS 21（-/-）小鼠胚胎成纤维细胞中的发生率高于野生型MEFs（wt-MEFs）。因此，研究了TIS 21在DNA损伤应答中的作用。用TIS 21基因腺病毒转导Huh 7肿瘤细胞加速了依托泊苷治疗诱导的DSB的修复，如通过γ H2 AX病灶的清除和彗星试验所评估的。通过免疫沉淀和放射性标记分析确定，TIS 21增加了Mre 11的甲基化和蛋白质精氨酸甲基转移酶1（PRMT 1）活性，导致Mre 11在体外和体内活化。当在各种人类癌细胞系中评价下游DNA损伤应答介体时，发现TIS 21强烈抑制Chk 2（T68）和p53（S20）被p-ATM（S1981）磷酸化，但不抑制p53（S15）磷酸化。依托泊苷处理后Chk 2活化的丧失通过下调E2 F1和Bax的表达来减少细胞凋亡。这些数据表明TIS 21调节DSB修复和凋亡。TIS 21的表达通过Mre 11和PRMT 1的激活阻断p-ATM（S1981）到Chk 2（T68）-p53（S20）的损伤信号，促进DSB的修复，减少凋亡。(C)2012爱思唯尔有限公司版权所有。
DNA double strand breaks (DSBs) occur more frequently in TIS21(-/-) mouse embryo fibroblasts than that in wild type MEFs (wt-MEFs). Therefore, the role TIS21 plays in the DNA damage response was investigated. Adenoviral transduction of Huh7 tumor cells with the TIS21 gene accelerated the repair of DSBs induced by etoposide treatment as evaluated by clearance of gamma H2AX foci and the Comet assay. TIS21 increased methylation of Mre11 and protein arginine methyltransferase 1 (PRMT1) activity, leading to Mre11 activation in vitro and in vivo, as determined by immunoprecipitation and radiolabeling analyses. When downstream DNA damage response mediators were evaluated in various human cancer cells lines, TIS21 was found to strongly inhibit Chk2(T68) and p53(S20) phosphorylation by p-ATM(S1981) but not p53(S15). The loss of Chk2 activation after etoposide treatment reduced apoptosis in the cells by downregulating the expression of E2F1 and Bax. These data suggest that TIS21 regulates DSB repair and apoptosis. Expression of TIS21 promoted the repair of DSBs and reduced apoptosis by blocking the damage signal from p-ATM(S1981) to Chk2(T68)-p53(S20) via the activation of Mre11 and PRMT1. (C) 2012 Elsevier B.V. All rights reserved.