XRCC5 MUTANT MICE AND CELL LINES

该项目的目标是研究Ku80在组织中的功能 培养细胞和小鼠，这样我们就可以更好地了解这些途径 修复DNA双链断裂(DSB)并监测DNA损伤。一辆酷80 -Ku70异源二聚体形成DNA依赖的DNA结合成分 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的缺乏都会损害 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。SCID(严重联合免疫) 有缺陷的)小鼠的缺陷最近被证明是由于 DNA-PKcs水平。但是，尚未生成空突变，或者 在小鼠身上观察到编码这些蛋白质的任何基因， 包括SCID。编码Ku80的基因XRCC5在小鼠身上发生了突变 通过胚胎干细胞/基因打靶技术。老鼠是一个理想的选择 研究DNA修复的系统，因为它与人类和 由于复杂的遗传学。初步结果表明， XRCC5突变类似于SCID突变；两者都会导致免疫 缺陷小鼠和g辐射过敏性细胞系。然而，不同于 SCID，XRCC5突变小鼠是严重生长迟缓和突变的细胞 细胞系增殖缓慢，老化迅速。这份提案将回答：什么 XRCC5的表型是突变的细胞系和小鼠吗？具体目标 1)XRCC5突变小鼠的表型分析。2)分析单元格 XRCC5突变细胞系的增殖、老化和辐射敏感性。 3)表征XRCC5突变对淋巴细胞发育的影响 和V(D)J复合。4)分析DSB在突变细胞中的修复情况 通过端到端连接的线和非同源和同源的线 重组。这些目标的实现将显著影响 我们思考DNA的动态性质，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.