STUDIES OF DNA MISMATCH REPAIR

工作总结：本项目的目标是了解流程 真核细胞复制后错配修复，选择性地移除 来自新合成的链的DNA复制错误。我们是 检测正常和突变的人类细胞提取物的校正能力 含有错配或未配对核苷酸的DNA底物。不匹配 连接突变的癌细胞系修复活性有缺陷 五种不同的基因，MSH2、MSH3、MSH6、MLH1和PMS2中的任何一种。每一个 这些系已通过将野生型染色体转移到 正在对细胞系和由此产生的表型进行检查。这些 表型包括微卫星不稳定性、HPRT突变率、 细胞周期对碱基类似物和烷化剂的敏感性 检查点控制和错配修复，在DNA之前的一步 重新合成。我们已经证明了错配需要MLH1 通过研究人成纤维细胞的修复能力来研究 MLH1基因为(+/+)、(+/-)和(-/-)的小鼠。我们有 证明成纤维细胞来源于沃纳综合征，一种 早衰综合征，是错配修复的缺陷。这些 研究对于理解黄褐斑病毒的遗传学和生物化学很重要。 失配修复系统，功能繁多 错配修复基因--启动的分子遗传学基础 癌症及其后续治疗中的事件和对 暴露于DNA损伤剂的人群中的个人。

Summary of Work: The goal of this project is to understand the process of eukaryotic post-replication mismatch repair, which selectively removes DNA replication errors from the newly synthesized strand. We are examining the ability of normal and mutant human cell extracts to correct DNA substrates containing mispaired or unpaired nucleotides. Mismatch repair activity is defective in cancer cell lines contaning mutations in any of five different genes, MSH2, MSH3, MSH6, MLH1, and PMS2. Each of these lines has been corrected by transfer of a wild-type chromosome to the cell line and the resulting phenotypes are being examined. These phenotypes include microsatellite instability, HPRT mutation rate, sensitivity to base analogues and alkylating agents, cell cycle checkpoint control, and mismatch repair, at a step preceding DNA resynthesis. We have demonstrated that MLH1 is required for mismatch repoari by studying the repair capacity of fibroblast cells derived from mice that are (+/+), (+/-) and (-/-) for the MLH1 gene. We have demonstrated that fibroblast cells derived from Werner Syndrome, a premature aging syndrome, are defective in mismatch repair. These studies are important for understanding the genetics and biochemistry of the mismatch repair system, the multiple functions of the numerous mismatch repair genes, the molecular genetic basis for the initiating events in cancer and its subsequent treatment and the risk posed to individuals in the population by exposure to DNA damaging agents.