Radioprotection of acute and persistent DNA deletions

项目1的主要目标是找到能够抵消辐射引起的DNA缺失的药物，这些缺失会导致细胞死亡和遗传不稳定，从而产生诸如出生缺陷和癌症等长期后果。我们之前已经证明，在酵母和人类细胞以及小鼠中，电离辐射可以诱导DNA缺失。我们将在酵母和小鼠中使用报告基因测定来确定能够抵消辐射引起的DNA缺失频率的试剂。我们已经开发了一种生物发光版本的酵母缺失试验，适用于自动化到高通量筛选（HTS）格式。在目标1中，我们建议表征不同化合物库集的化学物质在电离辐射处理之前或之后添加时对细胞毒性的活性以及DNA缺失的频率的影响（核心D）。酵母试验的力量在于它可以用作HTS

The primary goal of Project 1 is to find agents that counteract radiation-induced DNA deletions leading to cell death and genetic instability that can have long-term consequences such as birth defects and cancer. We have previously shown that DNA deletions are inducible by ionizing radiation in yeast and human cells, as well as in mice. We will use reporter assays in yeast and mice to identify agents that counteract the radiation-induced frequency of DNA deletions. We have developed a bioluminescent version of the yeast deletion assay that is suitable for automation to a high throughput screening (HTS) format. In aim 1 we propose to characterize the effect of the chemicals of different compound library sets for their activity to counteract the cytotoxicity as well as the frequency of DNA deletions when added before or after treatment with ionizing radiation (Core D). The power of the yeast assay is that it can be used as an HTS assay to prioritize chemicals for further assays in mice and in human cells in aims 3 and 4 and in other Research Projects. Ionizing radiation induces these deletions also in a delayed fashion causing a persistent hyperrecombination phenotype, which is a major contributor to the progressive, multistage development of malignant disease. For aim 2 we will reformat the HTS yeast assay of aim 1 and use a subset of agents selected from Aim 1 to specifically score their potential to counteract radiation-induced hyperrecombination. In aim 3 we will use a subset of those chemicals that were most potent in aim 1 to determine whether they reduce the frequency of radiation-induced DNA deletions in vivo in mice (Core C). Finally, in aim 4 we will determine whether any of the three most potent radioprotectors from all three projects combined would reduce the frequency of radiation-induced tumors in mice. We will also determine effects of the agents selected from Aim 1 on levels of radiation-induced oxidative 8-oxoguanine DNA damage and strand breaks. Furthermore, lymphocytes of the mice treated with those chemicals that show an in vivo effect will be used in the Proteomics Core to determine the signaling pathways that they activate.