TRANSCRIPTION DEPENDENT DNA REPAIR OF N-ETHYLPURINES

这项拨款提案的长期目标是阐明细胞 参与转录现象的成分 依赖性DNA修复，其特征在于优先 从转录链中有偏向地清除DNA损伤， 活跃表达的基因位点。 这导致显著的调制 化学诱导的生物学后果，修饰的碱基， DNA，包括致突变性、毒性和致癌性。 乙基化 药剂是一类与环境相关的化合物， 损伤DNA，产生以优先方式清除的加合物 从转录的基因组区域。 本申请的假设 N-乙基嘌呤的转录依赖性清除存在于 DNA修复精通哺乳动物细胞，但缺乏细胞缺乏 功能性核苷酸切除修复或错配修复。 具体 目的旨在测试这是：（1）N-乙基嘌呤的修复将是 在哺乳动物细胞中的活跃遗传基因座中进行评估， DNA修复;（2）N-乙基嘌呤的基因特异性去除将是 在来自具有核苷酸的患者的细胞系中进行评价 切除修复缺陷性疾病着色性干皮病;（3） 这些加合物从来自患有 将测定Cockayne综合征;（4）N-乙基嘌呤清除率 将在功能不匹配缺陷的人类细胞中进行测量 修复;和（5）这些加合物的基因特异性去除将是 在缺乏碱基切除修复途径的鼠细胞中评估。 的 从这些研究中获得的结果将开始确定精确的基因 转录依赖性清除病变所必需的产品 在DNA中形成，数据将与 加合物的转录依赖性清除。 这些发现将增加 这对我们理解 潜在的转录依赖性DNA修复和 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.