Shi Wenting, Tang Mei Kuen, Yao Yao, Tang Chengcheng, Chui Yiu Loon, Lee Kenneth Ka Ho
Stem Cell and Regeneration Thematic Research Programme, School of Biomedical Sciences, Chinese University of Hong Kong, Hong Kong, People's Republic of China.
Department of Chemical Pathology, Chinese University of Hong Kong, Hong Kong, People's Republic of China.
Sci Rep. 2016 Mar 22;6:23506. doi: 10.1038/srep23506.
The BRE gene, alias BRCC45, produces a 44 kDa protein that is normally distributed in both cytoplasm and nucleus. In this study, we used adult fibroblasts isolated from wild-type (WT) and BRE knockout (BRE(-/-)) mice to investigate the functional role of BRE in DNA repair and cellular senescence. We compared WT with BRE(-/-) fibroblasts at different cell passages and observed that the mutant fibroblasts entered replicative senescence earlier than the WT fibroblasts. With the use of gamma irradiation to induce DNA damage in fibroblasts, the percentage of SA-β-Gal(+) cells was significantly higher in BRE(-/-) fibroblasts compared with WT cells, suggesting that BRE is also associated with DNA damage-induced premature senescence. We also demonstrated that the gamma irradiation induced γ-H2AX foci, a DNA damage marker, persisted significantly longer in BRE(-/-) fibroblasts than in WT fibroblasts, confirming that the DNA repair process is impaired in the absence of BRE. In addition, the BRCA1-A complex recruitment and homologous recombination (HR)-dependent DNA repair process upon DNA damage were impaired in BRE(-/-) fibroblasts. Taken together, our results demonstrate a role for BRE in both replicative senescence and DNA damage-induced premature senescence. This can be attributed to BRE being required for BRCA1-A complex-driven HR DNA repair.
BRE基因，别名BRCC45，产生一种44 kDa的蛋白质，该蛋白质通常分布于细胞质和细胞核中。在本研究中，我们使用从野生型（WT）和BRE基因敲除（BRE(-/-)）小鼠分离的成年成纤维细胞，来研究BRE在DNA修复和细胞衰老中的功能作用。我们比较了不同细胞传代次数下的WT和成纤维细胞与BRE(-/-)成纤维细胞，观察到突变的成纤维细胞比WT成纤维细胞更早进入复制性衰老。通过使用γ射线照射诱导成纤维细胞中的DNA损伤，与WT细胞相比，BRE(-/-)成纤维细胞中SA-β-Gal(+)细胞的百分比显著更高，这表明BRE也与DNA损伤诱导的早衰有关。我们还证明，γ射线照射诱导的DNA损伤标记物γ-H2AX焦点在BRE(-/-)成纤维细胞中持续的时间明显长于WT成纤维细胞，证实了在没有BRE的情况下DNA修复过程受损。此外，BRE(-/-)成纤维细胞中DNA损伤时BRCA1-A复合物的募集和同源重组（HR）依赖性DNA修复过程受损。综上所述，我们的结果证明了BRE在复制性衰老和DNA损伤诱导的早衰中均发挥作用。这可归因于BRE是BRCA1-A复合物驱动的HR DNA修复所必需的。
