Impact of RING and BRCT domain mutations on BRCA1 protein stability, localization and recruitment to DNA damage.
Impact of RING and BRCT domain mutations on BRCA1 protein stability, localization and recruitment to DNA damage.
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DOI：
10.1667/rr1290.1
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发表时间：
2010-07
影响因子：
3.4
通讯作者：
Holt JT
中科院分区：
文献类型：
--
作者：
Nelson AC;Holt JT
肿瘤抑制因子BRCA 1内的突变导致大多数遗传性乳腺癌和卵巢癌病例。BRCA 1蛋白是DNA双链断裂修复的重要调节因子，BRCA 1缺陷细胞对电离辐射高度敏感。此外，BRCA 1功能可能有助于G2细胞周期检查点的执行。E3-泛素连接酶活性是BRCA 1唯一已知的酶活性，其由N-末端RING指结构域介导。介导蛋白质-蛋白质相互作用的C-末端BRCT重复结构域是唯一的其他鉴定的结构域。通过研究每个结构域内的癌症相关突变，我们证明BRCT结构域的截短极大地损害了BRCA 1蛋白的稳定性和核定位。RING结构域内的错义突变不影响这些生化特性。然而，BRCA 1的两种突变形式都不能与已知的BRCA 1相互作用蛋白BARD 1和BACH 1共定位在核灶中，这两种蛋白对DNA修复很重要。尽管RING突变体蛋白与BACH 1相互作用的持续能力以及BRCT突变体与BARD 1相互作用的能力，这种失败还是发生了。此外，BRCA 1的两种突变形式都不会被募集到由γ H2 AX标记的DNA损伤相关病灶中。因此，我们的数据表明，BRCA 1的RING和BRCT结构域都是BRCA 1在DNA修复过程中发挥功能的早期步骤所必需的：招募到DNA损伤部位。
Mutations within the tumor suppressor BRCA1 cause the majority of hereditary breast and ovarian cancer cases. The BRCA1 protein is an important regulator of DNA double strand break repair and BRCA1 deficient cells are highly sensitive to ionizing radiation. Furthermore, BRCA1 function may contribute to G2 cell cycle checkpoint enforcement. E3-ubiquitin ligase activity is the only known enzymatic activity of BRCA1, which is mediated by the N-terminal RING finger domain. The C-terminal BRCT repeat domain, which mediates protein-protein interactions, is the only other identified structural domain. By investigating cancer-linked mutations within each domain, we demonstrate that truncation of the BRCT domain greatly impairs the stability and nuclear localization of BRCA1 protein. A missense mutation within the RING domain does not affect these biochemical properties. However, both mutant forms of BRCA1 fail to co-localize in nuclear foci with the known BRCA1-interacting proteins BARD1 and BACH1, which are important for DNA repair. This failure occurs despite the continued ability of the RING mutant protein to interact with BACH1 and the ability of the BRCT mutant to interact with BARD1. Furthermore, neither mutant form of BRCA1 is recruited into DNA-damage-associated foci marked by γH2AX. Therefore, our data suggests that both the RING and BRCT domains of BRCA1 are required for an early step in the function of BRCA1 during DNA repair: recruitment to the sites of DNA damage.