XRCC5 MUTANT MICE AND CELL LINES

本课题的目的是研究Ku 80在组织中的功能 培养细胞和小鼠，以便我们更好地了解这些途径， 修复DNA双链断裂（DSB）并监测DNA损伤。酷80 - Ku 70异二聚体形成DNA依赖性的DNA结合组分 蛋白激酶（DNA-PK）和第三种蛋白质DNA-PKcs是催化 亚单位这三种蛋白质中的任何一种缺乏都会损害 在V（D）J（可变[多样性]连接）重组期间发生的DSB 或在暴露于电离辐射之后。严重联合免疫缺陷病（Scid） 缺乏）缺陷的小鼠最近被证明是由于减少 DNA-PKcs水平。然而，没有产生无效突变，或者 在小鼠中观察到编码这些蛋白质的任何基因， 包括SCID。编码Ku 80的基因XRCC 5在小鼠中发生突变 通过胚胎干细胞/基因靶向技术。老鼠是理想的 研究DNA修复的系统，因为它与人类非常相似， 因为他们有复杂的基因初步结果表明， xrcc 5突变与scid突变相似;两者都导致免疫缺陷。 缺陷小鼠和G-辐射超敏细胞系。但不同于 scid，xrcc 5突变小鼠严重生长迟缓，突变细胞 线增殖缓慢并且老化迅速。这份提案将回答：什么 是xrcc 5突变细胞系和小鼠的表型？具体目标 1）分析xrcc 5突变小鼠的表型。2)分析细胞 XRCC 5突变细胞系的增殖、衰老和辐射敏感性。 3)描述xrcc 5突变对淋巴细胞发育的影响 和V（D）J重组。4)分析突变细胞中DSB的修复 通过端对端连接以及非同源和同源连接 重组这些目标的实现将极大地影响 我们思考DNA的动态本质，并可能影响癌症的治疗 和免疫缺陷

The goal of this project is to investigate the function of Ku80 in tissue culture cells and in mice so that we may better understand those pathways that repair DNA double-strand breaks (DSBs) and monitor DNA damage. A Ku80 - Ku70 heterodimer forms the DNA binding component of DNA-dependent protein kinase (DNA-PK) and a third protein, DNA-PKcs, is the catalytic subunit. A deficiency in any one of thee proteins impairs the repair of DSBs that occur during V(D)J (variable [Diversity] Joining) recombination or after exposure to ionizing radiation. The scid (severe combined immune deficient) defect in mice was recently shown to be caused by a decrease in the level of DNA-PKcs. However, a null mutation has not been generated or observed for any of the genes that code for these proteins in mice, including scid. The gene that codes for Ku80, XRCC5, was mutated in mice by the embryonic stem cell/gene targeting technology. Mice are an ideal system to study DNA repair due to the remarkable similarity to humans and due to the sophisticated genetics. Preliminary results demonstrate the xrcc5 mutation is similar to the scid mutation; both result in immune deficient mice and g-radiation hypersensitive cell lines. However, unlike scid, the xrcc5 mutant mice are severely growth retarded and mutant cell lines proliferate slowly and age rapidly. This proposal will answer: What is the phenotype of xrcc5 mutant cell lines and mice? The specific aims are: 1) Analyze the phenotype of xrcc5 mutant mice. 2) Analyze cell proliferation, aging and radiation sensitivity in xrcc5 mutant cell lines. 3) Characterize the effects of an xrcc5 mutation on lymphocyte development and V(D)J recombination. 4) Analyze the repair of DSBs in mutant cell lines by end-to-end joining and nonhomologous and homologous recombination. Completion of these aims will significantly impact the way we think about the dynamic nature of DNA and may impact therapy for cancer and immune deficiency.