IONIZING RADIATION INDUCED DNA DAMAGE AND REPAIR

这个项目的目标是增加我们对如何 电离辐射通过以下途径导致癌症、突变和细胞死亡 哺乳动物X-射线的酶学和遗传学研究 诱导DNA修复。开发……的直接途径 X射线诱导的DNA修复酶的人类遗传学 对修复进行了描述。 这个项目将定义初级结构和遗传学 电离修复所需的人和牛酶 辐射引起的DNA损伤。牛组织(小牛胸腺)将 可用作制备均一酶的来源 氨基酸测序和抗体产生。CDNA3 编码修复酶的序列将选自lambda 兔抗酶免疫筛选gt11文库 抗体或来自lambda gt10文库的混合筛选 寡核苷酸。一旦牛酶的cdna被 获得的人cdna将选自lambda gt10或 Lambda gt11文库通过其核酸同源性或 免疫交叉反应。 脱氧核糖核酸内切酶已被选为 在本程序中进行克隆的原因如下：1)无嘌呤位点 在DNA中已知具有致突变性(并且可能致癌)2) 无嘌呤位点在许多类型的DNA损伤和 包括X光在内的修复3)单个基因或 AP内切酶的多个哺乳动物基因编码是 未解决的4)这种方法的要求是 完成a)均一酶b)氨基酸序列数据c) 来源组织的抗体探针和d)cdna文库 全部可用。 对X射线酶一级结构的认识 诱导的DNA修复将有助于理解这种 酶识别受损的DNA，过程中的一系列事件 修复以及修复失败可能如何导致生物性 X射线的影响。这些分子探针的可用性 基因将允许研究它们在遗传缺陷中的作用。 DNA修复如共济失调、毛细血管扩张症和易感性 个体和肿瘤对X射线的影响。

The goal of this project is to increase our understanding of how ionizing radiation causes cancer, mutation and cell death by elucidating the enzymology and genetics of mammalian X-ray- induced DNA repair. A direct approach for the development of human genetics for the enzymes of repair of X-ray-induced DNA repair is described. This project will define the primary structure and genetics of human and bovine enzymes required for repair of ionizing radiation-induced DNA damage. Bovine tissue (calf thymus) will be used as a source of preparation of homogeneous enzymes for amino acid sequencing and antibody production. The cDNA sequences coding for repair enzymes will be selected from lambda gt11 libraries by immunoscreening with rabbit anti-enzyme antibodies or from lambda gt10 libraries by screening with mixed oligonucleotides. Once the cDNA for the bovine enzyme is obtained the human cDNA will be selected from lambda gt10 or lambda gt11 libraries through its nucleic acid homology or immunologic cross reactivity, respectively. Apurinic endonuclease has been chosen as the initial target for cloning in this program for the following reasons; 1) Apurinic sites in DNA are known to mutagenic (and possibly carcinogenic) 2) apurinic sites are common to many types of DNA damage and repair including X-rays 3) the issue of whether a single gene or multiple mammalian genes code for AP endonuclease is unresolved 4) the requirements for this approach have been fulfilled a) homogeneous enzyme b) amino-acid sequence data c) antibody probes and d) cDNA libraries for the tissue of origin are all available. Knowledge of the primary structure of the enzymes of X-ray induced DNA repair will be useful in understanding how such enzymes recognize damaged DNA, the sequence of events during repair and how failures of repair might lead to the biological effects of X-rays. The availability of molecular probes for these genes will allow studies of their role in the inherited defects of DNA repair such as ataxia telangiectasia and in the susceptibility of individuals and tumors to X-rays effects.