TELOMERASE ACTIVITY AND RADIATION SENSITIVITY

端粒酶活性和辐射敏感性

• 批准号: 2190565
• 负责人: JEFFREY L. SCHWARTZ
• 金额: --
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-10 至 1995-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2190565
• 关键词: CHO cells; DNA directed DNA polymerase; chromosomes; enzyme activity; gene deletion mutation; genetic recombination; genome; hypoxanthine phosphoribosyltransferase; in situ hybridization; mutant; nucleic acid probes; nucleic acid repetitive sequence; nucleic acid sequence; polymerase chain reaction; pulsed field gel electrophoresis; radiation genetics; radiation sensitivity; southern blotting; telomere; transfection /expression vector

It has been proposed that telomere repeat sequences and telomere terminal transferase (telomerase) may influence mutation induction by ionizing radiation. Interstitial telomere repeat sequences are thought to be radiation-sensitive fragile sites, and telomerase has been reported to cap the ends of broken chromosomes, preventing their repair and promoting chromosome terminalization or recombination. We have been characterizing a Chinese hamster ovary cell line into which a gpt containing retroviral shuttle vector has been stably integrated. This normally stable locus in T5 cells is very sensitive to deletion mutation following ionizing radiation exposure. The gene also shows an LET response with an RBE of 3 for a particles. Analysis of the integration site has identified regions of T2AG3 telomere repeats both 3-prime and 5-prime to the gpt gene. The goal of these studies is to establish the role of telomere repeat sequences and telomerase in radiation sensitivity and genomic stability using this gpt locus as a model system. We plan to test the following hypotheses: (l) the telomere repeat sequences found at the gpt integration site were added to the vector or to the vector integration site by telomerase prior to or during integration, (2) these telomeric sequences have made the vector integration site a radiation-sensitive site, and (3) telomeres act as radiation-sensitive fragile sites by either serving as a site for further telomerase action and chromosome terminalization or by providing repeat structures to facilitate radiation-induced recombination. These studies should further our understanding of the roles that telomerase and interstitial telomere sequences play in genetic disease and help to better define the potential risks associated with environmental exposures to both low- and high-LET radiations.

有人提出端粒重复序列和端粒末端 转移酶（端粒酶）可能通过电离影响突变诱导 辐射。间质端粒重复序列被认为是 据报道，端粒酶可以限制对辐射敏感的脆弱部位 断裂染色体的末端，阻止其修复并促进 染色体末端化或重组。我们一直在描述一个 中国仓鼠卵巢细胞系，其中含有逆转录病毒的gpt 穿梭载体已稳定整合。这个通常稳定的位点 T5细胞对电离后的缺失突变非常敏感 辐射暴露。该基因还显示出 RBE 为 3 的 LET 反应 对于一个粒子。对整合站点的分析已确定区域 T2AG3 端粒与 gpt 基因重复 3 引物和 5 引物。这 这些研究的目标是确定端粒重复的作用 序列和端粒酶在辐射敏感性和基因组稳定性中的作用 使用这个 gpt 基因座作为模型系统。我们计划测试以下内容 假设：(l) 在 gpt 整合中发现的端粒重复序列 位点被添加到载体或载体整合位点 端粒酶在整合之前或期间，（2）这些端粒序列 使矢量整合位点成为辐射敏感位点，并且（3） 端粒通过充当辐射敏感的脆弱位点 进一步端粒酶作用和染色体末端化的位点或通过 提供重复结构以促进辐射诱导的重组。 这些研究应该进一步加深我们对以下角色的理解： 端粒酶和间质端粒序列在遗传性疾病和 帮助更好地定义与环境相关的潜在风险 暴露于低和高 LET 辐射。