雷达51
生物
同源重组
DNA修复
细胞生物学
DNA损伤
有丝分裂
细胞分裂
细胞周期检查点
细胞生长
基因
细胞周期
癌症研究
细胞
遗传学
DNA
作者
Takuya Abe,Dana Branzei
出处
期刊:DNA Repair
[Elsevier]
日期:2014-10-01
卷期号:22: 153-164
被引量:17
标识
DOI:10.1016/j.dnarep.2014.08.003
摘要
Transient induction or suppression of target genes is useful to study the function of toxic or essential genes in cells. Here we apply a Tet-On 3G system to DT40 lymphoma B cell lines, validating it for three different genes. Using this tool, we then show that overexpression of the chicken BRC4 repeat of the tumor suppressor BRCA2 impairs cell proliferation and induces chromosomal breaks. Mechanistically, high levels of BRC4 suppress double strand break-induced homologous recombination, inhibit the formation of RAD51 recombination repair foci, reduce cellular resistance to DNA damaging agents and induce a G2 damage checkpoint-mediated cell-cycle arrest. The above phenotypes are mediated by BRC4 capability to bind and inhibit RAD51. The toxicity associated with BRC4 overexpression is exacerbated by chemotherapeutic agents and reversed by RAD51 overexpression, but it is neither aggravated nor suppressed by a deficit in the non-homologous end-joining pathway of double strand break repair. We further find that the endogenous BRCA2 mediates the cytotoxicity associated with BRC4 induction, thus underscoring the possibility that BRC4 or other domains of BRCA2 cooperate with ectopic BRC4 in regulating repair activities or mitotic cell division. In all, the results demonstrate the utility of the Tet-On 3G system in DT40 research and underpin a model in which BRC4 role on cell proliferation and chromosome repair arises primarily from its suppressive role on RAD51 functions.
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