CHROMATIN REPLICATION AND HEAT-INDUCED CELL DEATH

这项提案的总体目标是确定 高热(40-48度)与温热的综合作用(S) 辐射(0~100Gy射线)对小鼠胸腺DNA复制的影响 哺乳动物细胞，以及损伤在DNA复制中的作用 热或热与辐射联合诱导的S相电池 细胞毒性。加热和/或辐照S相的电容 细胞：重新分配在核内聚合的DNA 将这些初生的DNA加工成更高级的- 订购(螺线管)染色质结构，并最终将其连接起来 DNA完全进入染色体大小的DNA将被确定。这个 我们将在加热的牢房中测试的模型是，对 核基质，或其相关的结构或大分子， 导致DNA中的残留损伤在 高温暴露。一个类似的模型将被测试以 确定S相细胞是否对辐射敏感 敏感的共济失调毛细血管扩张症人类细胞，XRS-CHO双 链断裂修复突变体或暴露于咖啡因的“野生型”细胞 在X射线照射期间由于这些细胞不能 将复制的DNA完全连接到染色体中。核电 在加热的牢房中正在检查的变化是热的 核基质蛋白变性(S)，沉淀 核蛋白和核糖核酸转移到核基质上 拓扑异构酶的潜在不可逆关联 转移到核基质附近的DNA上。我们将决定 这些损伤是否在DNA复制过程中受热 细胞导致DNA链断裂的长期存在 DNA在细胞加热过程中复制，从而最终 染色体畸变率和细胞毒性。

The overall objective of this proposal is to determine the combined effect(s) of hyperthermia (40 to 48 degree) and radiation (0 to 100 Gy) exposure on DNA replication in mammalian cells, and the role of lesions in DNA replication in heat-, or combined heat and radiation-induced S phase cell cytotoxicity. The capacity of heated and/or irradiated S phase cells: to redistribute DNA being polymerized at the nuclear matrix into bulk DNA, to process this nascent DNA into higher- order (solenoid) chromatin structure, and ultimately to ligate this DNA fully into chromosome-sized DNA will be determined. The model we will test in heated cells is that long-term damage to the nuclear matrix, or its associated structures or macromolecules, results in residual lesions in DNA being replicated during hyperthermic exposure. A similar model will be tested to determine whether S phase cell sensitivity in the radiation sensitive ataxia telangiectasia human cells, the xrs CHO double strand break repair mutants or "wild-type" cells exposed caffeine during X irradiation results from the failure of these cells to ligate replicating DNA fully into chromosomes. The nuclear alterations being examined in heated cells are the thermal denaturation of nuclear matrix protein(s), the precipitation of nuclear protein and RNA onto the nuclear matrix and the potentially irreversible association of the topoisomerase enzymes onto DNA adjacent to the nuclear matrix. We will determine whether these lesions in the DNA replicative process in heated cells result in the long-term presence of DNA strand breaks in DNA replicated during cell heating and thus ultimately to chromosome aberration formation and cytotoxicity.