MECHANISMS OF HIGH LET INDUCED GENOMIC INSTABILITY

描述：(申请人描述) 这个应用程序的目标是分析分子、遗传、 启动和保持基因组的细胞遗传学和细胞机制 细胞暴露于辐射后的不稳定性通常在 太空。这一目标将通过五个具体目标来实现。 特殊目标1将测试基因组不稳定性的假设，因为 通过延迟性染色体不稳定来衡量，可以由高能诱导 质子，高Z和高能(HZE)铁离子，以及高LETα 对数期和汇合期的颗粒均可使细胞停滞。具体目标2 将检验一种假设，即高密度脂蛋白的关键细胞靶点 LET诱导的基因组不稳定性位于细胞核和 核外细胞室。这将通过有选择地实现 以细胞核和/或质膜和细胞质为靶点 大于1阿尔法粒子，或由于125碘的衰变而加入到 DNA作为~(125)IUdR或以~(125)I-偶联形式结合到质膜上 刀豆蛋白A.特定目标3将检验细胞显示出 基因组不稳定的一点，例如染色体不稳定，表明 一种“突变子”表型，并表现出其他不稳定的终点， 具体地说，hprt和aprt基因座突变增加 DHFR和CAD基因座的扩增，姐妹染色单体交换水平升高，并延迟 生殖细胞死亡。《特定目标4》将检验假设 让辐射诱导的基因组不稳定性在等基因中增加 修复缺陷细胞系与已知DNA突变的关系 双链断裂修复。具体目标5将检验以下假设 导致基因组不稳定的分子基础可能是 从细胞遗传学上观察到。申请者将监测 (TTAGGG)n间质类端粒重复序列及其比较 基因组杂交，以确定一致的染色体区域 不稳定克隆和稳定克隆之间的区别。

DESCRIPTION: (Applicant's Description) The goal of this application is to analyze the molecular, genetic, cytogenetic and cellular mechanisms that initiate and perpetuate genomic instability after cellular exposure to radiations commonly encountered in space. This goal will be addressed by means of five specific aims. Specific aim 1 will test the hypothesis that genomic instability, as measured by delayed chromosomal instability, can be induced by high-energy protons, high-Z and high-energy (HZE) iron ions, and high LET alpha particles in both log-phase and confluence arrested cells. Specific aim 2 will test the hypothesis that the critical cellular target for high LET-induced genomic instability is located in both the nuclear and extranuclear cellular compartments. This will be achieved by selectively targeting the cell nucleus and/or the plasma membrane and cytoplasm to more than 1 alpha particle, or to the decay of 125iodine incorporated into the DNA as 125IUdR or bound to the plasma membrane as 125I-conjugated concanavalin A. Specific aim 3 will test the hypothesis that cells showing one point of genomic instability, e.g., chromosomal instability, demonstrate a "mutator" phenotype and display other endpoints of instability, specifically, increased mutation at the HPRT and APRT loci, gene amplification at the DHFR and CAD loci, increased SCE levels, and delayed reproductive cell death. Specific aim 4 will test the hypothesis that high LET radiation-induced genomic instability is increased in isogenic repair-deficient cell lines as a function of known mutations in DNA doublestrand-break repair. Specific aim 5 will test the hypothesis that there is a molecular basis for induced genomic instability that can be observed cytogenetically. The applicant will monitor instability of the (TTAGGG)n interstitial telomere-like repeat sequence and use comparative genomic hybridization to identify chromosomal regions that are consistently different between unstable and stable clones.