Recognition and processing of complex lesions by components from multiple DNA

DNA链间交联（ICLs）是DNA代谢过程的一个强大障碍，必须修复才能使细胞存活。虽然已经做了很多工作来定义细菌和酵母中ICL修复的机制，但它们在哺乳动物细胞中的加工过程尚未明确定义。在上一个资助期，我们证明了哺乳动物细胞中三链体定向的peptide ICL的核苷酸切除修复（NER）依赖性，易错修复。我们还发现，错配修复（MMR）蛋白参与的响应和修复peptide ICLs在一个错误的过程。我们在此更新应用程序中的工作假设是 NER和错配修复（MMR）蛋白在ICL的识别和初始加工中相互作用，而MMR蛋白独立于NER因子，参与ICL诱导的细胞周期调节和凋亡。拟议研究的长期目标是阐明从哺乳动物基因组中去除DNA ICL的分子机制，确定HR，MMR和NER途径中蛋白质之间的相互作用，并确定这些蛋白质在其他细胞对这些病变的反应中的作用。具体来说，我们建议：1）测试的假设，蛋白质从NER和 MMR通路在ICL的识别和初始加工过程中相互作用; 2）测试MLH 1在细胞检查点和对DNA ICL的凋亡反应中发挥作用的提议; 3）将DNA ICL靶向突变哺乳动物细胞系中的特定基因组位点，以确定DNA修复和重组基因产物在ICL加工中的作用; 4）评估靶向ICL作为抗增殖治疗剂的潜力。从这些研究中获得的结果将提供有价值的信息，以开发改进的靶向策略，以控制人类癌症使用ICL诱导剂。

DNA interstrand crosslinks (ICLs) present a formidable block to DNA metabolic processes and must be repaired for cell survival. While much work has been done to define the mechanisms of ICL repair in bacteria and yeast, their processing in mammalian cells is not clearly defined. In the previous funding period, we demonstrated an nucleotide excision repair (NER)-dependent, error-prone repair of triplex-directed psoralen ICLs in mammalian cells. We also found that mismatch repair (MMR) proteins are involved in the response to and repair of psoralen ICLs in an error-free process. Our working hypothesis in this renewal application is that NER and mismatch repair (MMR) proteins interact in the recognition and initial processing of ICLs, while MMR proteins, independently of NER factors, are involved in ICL-induced cell-cycle regulation and apoptosis. The long-term objectives of the proposed research are to elucidate molecular mechanisms involved in the removal of DNA ICLs from the mammalian genome, to identify interactions among proteins from HR, MMR, and NER pathways in doing so, and to determine the roles of these proteins in other cellular responses to these lesions. Specifically we propose to: 1) test the hypothesis that proteins from the NER and MMR pathways interact during recognition and initial processing of ICLs; 2) test the proposal that MLH1 functions in cellular checkpoint and apoptosis responses to DNA ICLs; 3) target DNA ICLs to specific genomic sites in mutant mammalian cell lines to determine roles for DNA repair and recombination gene products in processing ICLs; and 4) assess the potential of targeted ICLs as antiproliferative therapeutic agents. The results obtained from these studies will provide valuable information to develop improved targeted strategies to control human cancers using ICL-inducing agents.