DNA Mismatch and Double-Strand Break Repair

描述（由申请人提供）：同源重组是一种机制，它对于细胞耐受各种DNA损伤剂产生的DNA损伤至关重要。长期目标是确定顺铂、一氧化氮和甲基化剂等药物诱导DNA双链断裂形成及其修复的机制。我们已经证明，第一次，使用单细胞微凝胶电泳，顺铂诱导形成这样的断裂，并建议在第一个目的是检查其他代理商的能力，这样做，并检查在这个过程中的作用的DNA复制。在第二个目标中，将寻找一类新的依赖于同源重组存活的突变细胞，并特别针对它们对DNA损伤剂的响应进行表征。肿瘤细胞中DNA错配修复的缺失导致耐药性，而相反，错配修复能力导致药物致敏。第三个目标是基于发现的C-末端的一个关键的错配修复蛋白，MutS，是需要药物致敏和实验提出，以确定是否MutS的多聚体状态负责。我们最近表明，顺铂诱导的重组和双链断裂修复需要DNA聚合酶I，在第四个目标，我们将确定其在这些过程中的作用，通过灭活其核酸外切酶或聚合酶的活动。我们只能使用E。这是因为我们对DNA复制、修复和重组的了解比其他任何生物都多，而且它有能力在基因组中构建多个突变。这项基础研究影响了几个临床相关领域，包括抗肿瘤药物杀死细胞的机制以及耐药肿瘤如何在癌症化疗中出现。它还影响致病菌对抗生素产生耐药性的机制以及这种耐药性如何传播。

DESCRIPTION (provided by applicant): Homologous recombination is a mechanism that is essential to allow cells to tolerate DNA damage produced by various DNA damaging agents. The long term goals are to define the mechanisms by which agents such as cisplatin, nitric oxide and methylators induce the formation of DNA double-strand breaks and their repair. We have demonstrated, for the first time, using single cell microgel electrophoresis that cisplatin induces the formation of such breaks and it is proposed in the first aim to examine the other agents for their ability to do so and to examine the role of DNA replication in the process. In the second aim, a new class of mutant cells which are dependent on homologous recombination for survival will be sought and characterized especially for their response to DNA damaging agents. Loss of DNA mismatch repair in tumor cells results in drug resistance while, conversely, mismatch repair proficiency leads to drug sensitization. The third aim is based on the finding that the C-terminal end of a key mismatch repair protein, MutS, is needed for drug sensitization and experiments are proposed to determine if the multimeric state of MutS is responsible. We recently showed that cisplatin-induced recombination and double-strand break repair require DNA polymerase I and in the fourth aim, we will determine its role in these processes by inactivating either its exonuclease or polymerase activities. We can use only E. coli for these studies because more is known about DNA replication, repair and recombination than in any other organism and because of the ability to construct multiple mutations in its genome. This basic research impacts several areas of clinical relevance, including mechanisms by which antitumor agents kill cells and how drug-resistant tumors emerge in cancer chemotherapy. It also impacts the mechanism by which pathogenic bacteria become resistant to antibiotics and how this resistance is disseminated.