TRANSCRIPTION DEPENDENT DNA REPAIR OF N-ETHYLPURINES

这项拨款提案的长期目标是阐明细胞 参与这种称为转录现象的成分- 依赖的DNA修复，其特征是优先 偏置清除转录链上的DNA损伤 积极表达遗传基因座。这导致了显著的调制 化学诱导的、经修饰的碱基的生物后果 DNA，包括致突变性、毒性和致癌性。乙基化 试剂是一类与环境相关的化合物 破坏DNA，产生以优先方式清除的加合物 从转录的基因组结构域中。此应用程序的假设 N-乙基嘌呤的转录依赖清除存在于 精通DNA修复的哺乳动物细胞，但在缺乏DNA修复的细胞中缺失 功能核苷酸切除修复或错配修复。具体的 测试的目的是：(1)N-乙基嘌呤的修复将是 在哺乳动物细胞中评估活跃的遗传位点，这些细胞精通 DNA修复；(2)基因特异性去除N-乙基嘌呤 在来自具有核苷酸的患者的细胞系中进行评估 切除修复缺陷性色素性干皮病； 从患者来源的细胞中清除这些加合物 将确定Cockayne综合征；(4)N-乙基嘌呤清除 将在功能不匹配缺陷的人类细胞中进行测量 修复；以及(5)这些加合物的基因特异性移除将是 在缺乏碱基切除修复途径的小鼠细胞中进行评估。这个 从这些研究中获得的结果将开始定义精确的基因 转录依赖清除病变所需的产物 在DNA中形成，数据将与 依赖转录的加合物清除。这些发现将增加 对我们理解这一机制的重要贡献 潜在的转录依赖的DNA修复和DNA修复 将军。

The long range goals of this grant proposal are to elucidate the cellular components involved in the phenomenon known as transcription- dependent DNA repair, which is characterized by the preferentially biased clearance of DNA damage from the transcribed strand of actively expressed genetic loci. This results in significant modulation of the biological consequences of chemical-induced, modified bases in DNA, including mutagenicity, toxicity, and carcinogenicity. Ethylating agents are one class of environmentally relevant compounds that damage DNA, yielding adducts that are cleared in a preferential fashion from transcribed genomic domains. The hypothesis of this application is that transcription-dependent clearance of N-ethylpurines exists in DNA repair proficient mammalian cells but is absent in cells lacking functional nucleotide excision repair or mismatch repair. The specific aims designed to test this are: (1) The repair of N-ethylpurines will be assessed in active genetic loci in mammalian cells that are proficient in DNA repair; (2) the gene-specific removal of N-ethylpurines will be evaluated in cell lines derived from patients with the nucleotide excision repair deficiency disease xeroderma pigmentosum; (3) the clearance of these adducts from cells originating from patients having Cockayne's syndrome will be determined; (4) N-ethylpurine clearance will be measured in human cells deficient in functional mismatch repair; and (5) the gene-specific removal of these adducts will be assessed in murine cells lacking the base excision repair pathway. The results obtained from these studies will begin to define the precise gene products necessary for the transcription-dependent clearance of lesions formed in DNA, and the data will be compared to results for the transcription-dependent clearance of adducts. These findings will add an important contribution to our understanding of the mechanism underlying transcription-dependent DNA repair and DNA repair in general.