Transposition and DNA Repair in Drosophila

描述(由申请人提供)： 目的：将在果蝇体内研究双链DNA断裂的修复。这项工作的目的是确定什么因素影响细胞在几条修复途径中选择哪一条修复途径会导致修复DNA的不同最终产物。要检测的因素包括： Break的基因组位置 存在DNA修复突变 生物体的年龄和DNA断裂的时间 细胞内存在大量的裂隙 影响基因表达的基因“主开关” 方法：建立了一种在果蝇胚系中制造双链断裂的系统，并可以确定四种可选途径的相对使用情况。DNA断裂发生在一个特殊构建的转座遗传元件RRepeterl中的特定位置。该元件的设计方式是，不同的修复途径导致遗传上可区分的产物，以确定基因组位置的影响，将RReport I元件移动到果蝇基因组中的不同位置，并确定每一位置四种修复途径的相对使用情况。对于其他变量，报告基因1的位置是固定的，而遗传背景、个体年龄或环境变量的变化被测试其对途径使用的影响 医学意义：DNA修复被认为是维持基因组稳定性的关键，特别是在具有复杂基因组的物种中人类许多DNA修复基因的突变，包括本研究中几个基因座的人类同源物，导致癌症易感性一些修复途径产生主要的忠实修复产物，但另一些非常容易出错，因此，途径的选择对于癌症保护至关重要

DESCRIPTION (provided by applicant): Goals: The repair of double-strand DNA breaks will be studied in Drosophila This work is aimed at determining what factors influence the cell's "choice" of which of several repair pathways to utilize These pathways lead to different final products of repaired DNA The factors to be examined are: Genomic position of break Presence of DNA repair mutations Age of the organism and timing of the DNA break The existence of a large number of breaks m the cell Genetic "master switches" that affect gene expression Methods: A system has been developed whereby double-strand breaks are made in the Drosophila germline, and the relative usage of four alternative pathways can be ascertained DNA breakage occurs at a particular site within a specially constructed transposable genetic element named Rreporterl The element is designed in such a way that the different repair pathways lead to genetically distinguishable products To determine the effect of genomic position, the Rreporter I element is moved to a variety of sites within the Drosophila genome, and the relative usage of the four repair pathways is ascertained for each position. For the other variables, the positions of Rreporter 1 are fixed, while changes in the genetic background, age of the individual, or environmental variables are tested for their effects on pathway usage Medical Significance: DNA repair is recognized as crucial to maintaining the stability of the genome, especially in species with complex genomes Human mutations in many DNA repair genes, including the human homologs of several of the loci in the present study, cause predisposition to cancer Some of the repair pathways produce primarily faithful repair products, but others are highly error-prone Thus, the choice of pathway can be critical for cancer protection