Stability & Fragility of Trinucleotide Repeats in Yeast

描述（来自申请人摘要的逐字记录）： 三核苷酸重复（TNR）序列是许多人的致病突变。 遗传性疾病，包括强直性肌营养不良，最常见的营养不良， 脆性X综合征，最常见的遗传性精神疾病， 发育迟缓和神经退行性疾病，如亨廷顿舞蹈症和 脊髓小脑性共济失调TNR不稳定的机制是有趣的， 为了了解三联体重复疾病的病因和遗传， 以及对人类基因组稳定性的基本了解。此外，本发明还提供了一种方法， 扩展的CGG/CCG和CTGICAG序列是染色体脆性位点， 在体内易于断裂。染色体断裂与 在许多类型的癌症中发现的易位和缺失。的目的 该提案旨在阐明TNR不稳定性的机制， 脆弱性，并确定这两个不寻常的特征是如何相互关联的 使用酿酒酵母。已经开发了一种新的遗传测定法， 当TNR道扩张或断裂时产生可选择的表型。该测定 将用于筛选过表达影响TNR的蛋白质 膨胀或脆弱。发现的影响TNR的蛋白质将是 其特征在于确定它们的正常细胞功能和它们的 影响重复维护。此外，TNR的假设， 通过异常滞后链复制发生的扩增将通过 分析道的稳定性（通过PCR）和脆弱性（通过遗传和物理 分析）在特定的酵母复制突变体中。G2IM的作用 检测TNR道损伤和防止染色体断裂的检查点 将通过比较野生型和 检查点缺陷细胞。最后，这些分析将扩展到其他 在人类细胞中充当脆弱位点的小卫星序列类型。的 提出的实验旨在阐明不仅是简单的重复 扩大到引起人类疾病，但也造成的后果和细胞 对扩大的大片的反应，目的是了解基因组如何 不稳定会影响人类健康。

DESCRIPTION (Verbatim from the applicant's abstract): Expansion of trinucleotide repeat (TNR) sequences is the causative mutation for a number of hereditary diseases, including myotonic dystrophy, the most common dystrophy in adults, Fragile X syndrome, the most common form of inherited mental retardation, and neurodegenerative diseases such as Huntington's and the spinocerebellar ataxias. The mechanism of TNR instability is interesting both for understanding the etiology and inheritance of the triplet repeat diseases, and for a basic understanding of genome stability in humans. In addition, expanded CGG/CCG and CTGICAG sequences are sites of chromosome fragility, areas prone to breakage in vivo. Chromosome breakage is implicated in the generation of translocations and deletions found in many types of cancer. The aim of this proposal is to elucidate the mechanisms involved in TNR instability and fragility, and determine how these two unusual characteristics are interrelated using Saccharomyces cerevisiae. A novel genetic assay has been developed that produces a selectable phenotype when a TNR tract expands or breaks. This assay will be used to screen for proteins whose over-expression influences TNR expansion or fragility. The proteins found to influence TNRs will be characterized to determine both their normal cellular functions and their influence on repeat maintenance. In addition, the hypothesis that TNR expansions occur by aberrant lagging strand replication will be tested by analyzing tract stability (by PCR) and fragility (by genetic and physical analysis) in specific yeast replication mutants. The role of the G2IM checkpoint in detecting TNR tract damage and preventing chromosome breakage will be investigated by comparing rates of TNR tract breakage in wild-type and cheokpoint-defective cells. Lastly, these analyses will be extended to other types of minisatellite sequences that act as fragile sites in human cells. The proposed experiments are designed to elucidate not only how simple repeats expand to cause human disease, but also the consequences of and cellular response to expanded tracts, with the goal of understanding how genomic instability can affect human health.