Accumulation of p21 proteins at DNA damage sites independent of p53 and core NHEJ factors following irradiation
Accumulation of p21 proteins at DNA damage sites independent of p53 and core NHEJ factors following irradiation
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DOI：
10.1016/j.bbrc.2011.07.032
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发表时间：
2011-08-19
影响因子：
3.1
通讯作者：
Koike, Aki
中科院分区：
文献类型：
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作者：
Koike, Manabu;Yutoku, Yasutomo;Koike, Aki
细胞周期蛋白依赖性激酶（CDK）抑制剂p21在p53依赖性DNA损伤反应中起关键作用，即，细胞周期检查点、衰老或凋亡。p21也可能在DNA修复中发挥作用。p21灶出现在重离子照射的DNA双链断裂（DSB）位点，其主要通过非同源DNA末端连接（NHEJ）修复。然而，没有p21积累在双链断裂（DSB）网站的机制已被详细阐明。最近的研究表明，Ku 70和Ku 80对于其他NHEJ核心因子的积累是必不可少的，例如，DNA-PKcs、XRCC 4和XLF，以及其他DNA损伤反应因子，例如，BRCA1。在这里，我们表明，p21焦点出现在激光照射的网站在细胞从各种组织从各种物种。EGFP-p21的积累不仅在正常细胞中检测到，而且在转化细胞或癌细胞中也检测到。我们的研究结果还表明，EGFP-p21在照射部位迅速积累，并与DSB标记γ-H2 AX和DSB传感器蛋白Ku 80共定位。另一方面，在Ku 70-、Ku 80-或DNA-PKcs-缺陷细胞系和人乳头瘤病毒18阳性细胞中发生蓄积，而没有PCNA结合区的p21突变体（EGFP-p21（1-146））未能在照射部位蓄积。这些发现表明，p21的积累，而不是功能性p53和NHEJ核心因子，是依赖于PCNA。这些发现还表明，p21在DNA损伤位点的积累活性在人和动物细胞中是保守的，并且p21是作为DNA损伤位点的检测标记物的有用工具。(C)2011 Elsevier Inc. All rights reserved.
The cyclin-dependent kinase (CDK) inhibitor p21 plays key roles in p53-dependent DNA-damage responses, i.e., cell cycle checkpoints, senescence, or apoptosis. p21 might also play a role in DNA repair. p21 foci arise at heavy-ion-irradiated DNA-double-strand break (DSB) sites, which are mainly repaired by nonhomologous DNA-end-joining (NHEJ). However, no mechanisms of p21 accumulation at double-strand break (DSB) sites have been clarified in detail. Recent works indicate that Ku70 and Ku80 are essential for the accumulation of other NHEJ core factors, e.g., DNA-PKcs, XRCC4 and XLF, and other DNA damage response factors, e.g., BRCA1. Here, we show that p21 foci arise at laser-irradiated sites in cells from various tissues from various species. The accumulation of EGFP-p21 was detected in not only normal cells, but also transformed or cancer cells. Our results also showed that EGFP-p21 accumulated rapidly at irradiated sites, and colocalized with the DSB marker gamma-H2AX and with the DSB sensor protein Ku80. On the other hand, the accumulation occurred in Ku70-, Ku80-, or DNA-PKcs-deficient cell lines and in human papillomavirus 18-positive cells, whereas the p21 mutant without the PCNA-binding region (EGFP-p21(1-146)) failed to accumulate at the irradiated sites. These findings suggest that the accumulation of p21, but not functional p53 and the NHEJ core factors, is dependent on PCNA. These findings also suggest that the accumulation activity of p21 at DNA damaged sites is conserved among human and animal cells, and p21 is a useful tool as a detection marker of DNA damaged sites. (C) 2011 Elsevier Inc. All rights reserved.