Expression of ATM in ataxia telangiectasia fibroblasts rescues defects in DNA double-strand break repair in nuclear extracts
Expression of ATM in ataxia telangiectasia fibroblasts rescues defects in DNA double-strand break repair in nuclear extracts
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DOI：
10.1002/em.1020
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发表时间：
2001-01-01
影响因子：
2.8
通讯作者：
Dixon, K
中科院分区：
文献类型：
--
作者：
Li, YL;Carty, MP;Dixon, K
毛细血管扩张共济失调 (A-T) 是一种 cc 人类遗传性疾病，其特征是进行性小脑变性、对电离辐射 (IR) 过敏、免疫缺陷和高癌症风险。在细胞水平上，IR 敏感性以及自发性和 IR 诱导的染色体断裂和重排频率增加是 A-T 的标志。在这种综合征中突变的 ATM 基因已被克隆并编码与 DNA-PKcs 具有同源性的蛋白质，DNA-PKcs 是一种参与 DNA 双链断裂 (DSB) 修复和 DNA 损伤反应的蛋白激酶。 A-T细胞表型和ATM基因的特征表明，ATM可能在DSB修复中发挥类似于DNA-PKcs的作用，并且A-T细胞中存在原发性DNA修复缺陷。在当前的研究中，使用两个质粒在体外系统中评估了 ATM 在 DNA DSB 修复中的功能，这两个质粒在 lacZ α 基因内携带 EcoRI 诱导的 DSB，或在 SupF 抑制 tRNA 基因内携带各种核酸内切酶诱导的 DSB。我们发现 A-T 核提取物中的 DSB 修复效率与正常核提取物中的 DSB 修复效率相当，甚至更高。然而，当修复具有短 5' 和 3' 突出端的 DSB 时，A-T 核提取物的修复保真度会降低（
Ataxia telangiectasia (A-T) is cc human genetic disorder characterized by progressive cerebellar degeneration, hypersensitivity to ionizing radiation (IR), immunodeficiency, and high cancer risk. At the cellular level, IR sensitivity and increased frequency of spontaneous and IR-induced chromosomal breakage and rearrangements are the hallmarks of A-T. The ATM gene, mutated in this syndrome, has been cloned and codes for a protein sharing homology with DNA-PKcs, a protein kinase involved in DNA double-strand break (DSB) repair and DNA damage responses. The characteristics of the A-T cellular phenotypes and ATM gene suggest that ATM may play a role similar to that of DNA-PKcs in DSB repair and that there is a primary DNA repair defect in A-T cells. In the current study, the Function of ATM in DNA DSB repair was evaluated in an in vitro system using two plasmids, carrying either an EcoRI-induced DSB within the lacZ alpha gene or various endonuclease-induced DSB in the SupF suppressor tRNA gene. We Found that the DSB repair efficiency in A-T nuclear extracts was comparable to, if not higher than, that in normal nuclear extracts. However, the repair fidelity in A-T nuclear extracts was decreased when repairing DSB with short 5 ' and 3 ' overhangs (