Loss of BRCA1-A complex function in RAP80 null tumor cells.
Loss of BRCA1-A complex function in RAP80 null tumor cells.
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DOI：
10.1371/journal.pone.0040406
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Yu X
中科院分区：
文献类型：
--
作者：
Bian C;Wu R;Cho K;Yu X
受体相关蛋白80(RAP80)是BRCA1-A复合体的一个亚基，在DNA双链断裂时针对BRCA1的DNA损伤部位。由于BRCA1突变与家族性卵巢癌相关，我们对26个卵巢癌来源的细胞株进行了RAP80突变筛查，发现TOV-21G细胞含有RAP80突变(c.1107G>；A)。该突变在Trp369处产生一个终止密码子，该终止密码子缺失RAP80的部分Air区域和C-末端的锌指。有趣的是，由于启动子的高甲基化，RAP80的突变型和野生型等位基因都失去了表达，这表明tov-21G是一个RAP80缺失的细胞系。在这些细胞中，不仅BRCA1-A复合体被破坏，BRCA1-A复合体中包括BRCA1、CCDC98、NBA1、BRCC36和BRE在内的其余亚基的重新定位也受到显著抑制。此外，TOV-21G细胞对电离辐射高度敏感，这是由于这些细胞的DNA损伤修复能力受损所致。用野生型RAP80重组tov-21G细胞可以挽救这些细胞在应对DNA损伤时的缺陷。因此，我们的结果表明RAP80是BRCA1-A复合体中的一种支架蛋白。将TOV-21G鉴定为RAP80缺失的肿瘤细胞系，将为研究DNA损伤反应的分子机制奠定基础。
Receptor Associated Protein 80 (RAP80) is a subunit of the BRCA1-A complex and targets BRCA1 to DNA damage sites in response to DNA double strand breaks. Since mutations of BRCA1 are associated with familial ovarian cancers, we screened 26 ovarian cancer-derived cell lines for RAP80 mutations and found that TOV-21G cells harbor a RAP80 mutation (c.1107G >A). This mutation generates a stop codon at Trp369, which deletes the partial AIR region and the C-terminal zinc fingers of RAP80. Interestingly, both the mutant and wild type alleles of RAP80 lose their expression due to promoter hypermethylation, suggesting that TOV-21G is a RAP80-null cell line. In these cells, not only is the BRCA1-A complex disrupted, but the relocation of the remaining subunits in the BRCA1-A complex including BRCA1, CCDC98, NBA1, BRCC36 and BRE is significantly suppressed. Moreover, TOV-21G cells are hypersensitive to ionizing radiation, which is due to the compromised DNA damage repair capacity in these cells. Reconstitution of TOV-21G cells with wild type RAP80 rescues these cellular defects in response to DNA damage. Thus, our results demonstrate that RAP80 is a scaffold protein in the BRCA1-A complex. Identification of TOV-21G as a RAP80 null tumor cell line will be very useful for the study of the molecular mechanism in DNA damage response.
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