RADIATION INDUCTION OF GENOMIC REARRANGEMENTS IN YEAST

酵母基因组重排的辐射诱导

• 批准号: 6522366
• 负责人: MICHAEL Thomas FASULLO
• 金额: $ 20.93万
• 依托单位: ALBANY MEDICAL COLLEGE
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-08-01 至 2003-03-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6522366
• 关键词: DNA damage; DNA repair; DNA replication; Saccharomyces cerevisiae; artificial chromosomes; cell cycle; chromosome translocation; fungal genetics; gene deletion mutation; gene frequency; gene induction /repression; gene rearrangement; genetic crossing over; genetic polymorphism; genetic regulation; genetic strain; helicase; ionizing radiation; mutant; nucleic acid repetitive sequence; protein kinase; radiation genetics; recombinase; transposon /insertion element; ultraviolet radiation

DNA damage-induced cell cycle checkpoints have been postulated to be important in maintaining genetic stability by arresting or delaying the cell cycle to allow time for repair of recombinogenic DNA damage. Loss-of-function mutations that abolish checkpoints and increase genetic instability have been observed in cancer cells and may contribute to rapid proliferation and/or resistance to chemotherapeutic drugs and radiation therapy. Cell cycle checkpoint genes may function in a signal transduction pathway in which the presence of DNA damage is relayed to both the cell cycle machinery and the transcription apparatus to upregulate DNA repair genes. The purpose of this proposal is to elucidate the genetic pathway by which the Saccharomyces cerevisiae RAD9 checkpoint reduces genetic instability that results from homologous recombination between repeated sequences (ectopic recombination). We have previously described a chromosomal translocation assay that can measure genetic instability in yeast rad9 mutants. The first aim is to identify specific genes or combinations of genes in the RAD9- mediated signal transduction pathway which reduce the radiation- associated stimulation of translocations. The second aim is to examine the contribution of other cell cycle checkpoints in maintaining genetic stability. The third aim is to understand whether checkpoints also reduce the radiation-associated recombination between yeast Ty elements. The results obtained in this study may also elucidate current ideas concerning genomic stability in eukaryotic organisms: 1) that elevated levels of recombinases may be important in DNA repair of double-strand breaks (DSBs) generated by DNA replication, 2) that signal transduction pathways that trigger the G2-M checkpoint and control genetic stability are redundant, 3) that the non-random accumulation of genetic changes observed in checkpoint mutants may partially result from recombination between retrotransposons.

DNA损伤诱导的细胞周期检查点被认为是重要的，通过阻止或延迟细胞周期来维持遗传稳定性，以便有时间修复重组DNA损伤。已经在癌细胞中观察到功能丧失突变，这些突变会取消检查点并增加遗传不稳定性，并可能导致癌细胞快速增殖和/或对化疗药物和放射治疗产生耐药性。细胞周期检查点基因可能在信号转导途径中起作用，其中DNA损伤的存在被传递给细胞周期机制和转录装置，以上调DNA修复基因。本研究旨在阐明酿酒酵母RAD9检查点减少重复序列之间同源重组（异位重组）导致的遗传不稳定性的遗传途径。我们以前已经描述了一种染色体易位测定，可以测量酵母rad9突变体的遗传不稳定性。第一个目的是确定RAD9介导的信号转导途径中减少辐射相关易位刺激的特定基因或基因组合。第二个目的是检查其他细胞周期检查点在维持遗传稳定性方面的贡献。第三个目的是了解检查点是否也减少了与辐射相关的酵母Ty元素之间的重组。本研究的结果也可能阐明目前关于真核生物基因组稳定性的观点：1)重组酶水平的升高可能在DNA复制产生的双链断裂（DSBs）的DNA修复中起重要作用；2)触发G2-M检查点和控制遗传稳定性的信号转导途径是冗余的；3)在检查点突变体中观察到的遗传变化的非随机积累可能部分是由反转录转座子之间的重组引起的。