Genetic regulation of genome stability in yeast

描述(申请人提供)：基因组可以以各种方式改变，包括单碱基对改变、序列的删除和复制，以及染色体重排(易位和倒置)。这些事件发生的频率影响着两个截然不同的过程。基因变化是进化所必需的，因此，这些变化的速度原则上可以影响进化的速度。其次，许多癌症与染色体重组率升高有关，而这种类型的不稳定性似乎与转移性肿瘤密切相关。当哺乳动物细胞被DNA聚合酶抑制剂aphidiclin(一种DNA聚合酶抑制剂)处理时，染色体在与肿瘤细胞中观察到的易位断裂点相关的特定位置(脆弱位置)处断裂。在ATM和ATR基因突变的哺乳动物细胞中也观察到高水平的染色体断裂和其他异常。我们的总体目标是在酿酒酵母中模拟这种类型的遗传不稳定性，并表征导致这种不稳定性的机制。我们的具体目标是：1)确定表征酵母脆弱部位的DNA序列属性，并表征与脆弱部位DNA断裂相关的染色体重排；2)表征具有影响DNA损伤检查点、端粒长度调节、重组和/或染色质组装基因突变的酵母菌株的染色体异常；例如，将检测具有Mec1和/或tel1基因的菌株(分别与哺乳动物ATR和ATM基因的酵母同源物)，以及3)了解电离辐射诱导的遗传不稳定性。这些研究将强调允许检查整个酵母基因组的技术，包括DNA微阵列分析(检测基因剂量的变化并绘制易位断点图)，以及允许分离完整染色体DNA分子的凝胶技术。

DESCRIPTION (provided by applicant): Genomes can be altered in a variety of ways including single base pair changes, deletions and duplications of sequences, and chromosome rearrangements (translocations and inversions). The rates at which these events occur affect 2 quite different processes. Genetic changes are required for evolution and the rate of these changes, therefore, can in principle affect the rate of evolution. Second, many cancers are associated with elevated rates of chromosome rearrangements, and this type of instability appears to be strongly associated with metastatic tumors. When mammalian cells are treated with aphidicolin (a DNA polymerase inhibitor), the chromosomes are broken at specific sites (fragile sites) that are related to translocation breakpoints observed in tumor cells. High levels of chromosome breaks and other aberrations are also observed in mammalian cells with mutations in the ATM and ATR genes. Our general goal is to mimic this type of genetic instability in the yeast Saccharomyces cerevisae, and to characterize the mechanisms responsible for this instability. Our specific aims are: 1) to determine the DNA sequence properties that characterize yeast fragile sites and to characterize the chromosome rearrangements that are associated with DNA breaks at fragile sites, 2) to characterize chromosome aberrations in yeast strains with mutations in genes affecting DNA damage checkpoints, telomere length regulation, recombination, and/or chromatin assembly; for example, strains with mec1 and/or tel1 genes (yeast homologues of the mammalian ATR and ATM genes, respectively) will be examined, and 3) to understand the genetic instability induced by ionizing radiation. These studies will emphasize techniques that allow examination of the entire yeast genome, including DNA microarray analysis (to detect changes in gene dosage and to map translocation breakpoints), and gel technologies that allow separation of intact chromosomal DNA molecules.