MECHANISMS OF HIGH LET INDUCED GENOMIC INSTABILITY

描述：（申请人的描述） 这个应用程序的目标是分析分子，遗传， 启动和延续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， 空间 将通过五个具体目标来实现这一目标。 具体目标1将检验基因组不稳定性的假设， 通过延迟的染色体不稳定性来衡量，高能量可以诱导 质子，高Z和高能（HZE）铁离子，以及高LET α 在对数期和汇合期的颗粒都阻滞了细胞。 具体目标2 将测试这一假设，即关键的细胞靶高 LET诱导的基因组不稳定性位于细胞核和 胞核细胞区室。 这将通过有选择地 靶向细胞核和/或质膜和细胞质， 比1 α粒子，或衰变的125碘纳入 DNA以125 IUdR形式结合或以125 I结合形式结合于质膜 伴刀豆球蛋白A具体目标3将检验细胞显示 基因组不稳定性的一个点，例如，染色体不稳定性，显示 一种“突变体”表型并显示其它不稳定性终点， 特别是HPRT和APRT基因座突变增加， DHFR和CAD基因座扩增，增加SCE水平，并延迟 生殖细胞死亡 具体目标4将检验假设， LET辐射诱导的基因组不稳定性增加， 作为DNA中已知突变的函数的修复缺陷细胞系 双股断裂修复 具体目标5将检验以下假设： 存在诱导基因组不稳定性的分子基础， 细胞遗传学观察 申请人将监测 （TTAGGG）n间质端粒样重复序列和使用比较 基因组杂交来鉴定染色体区域， 不稳定克隆和稳定克隆的区别。

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.