Suppression of translocations by RecQ-like DNA helicases

RecQ 样 DNA 解旋酶抑制易位

• 批准号: 7468137
• 负责人: Kristina Schmidt
• 金额: $ 26.46万
• 依托单位: UNIVERSITY OF SOUTH FLORIDA
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7468137
• 关键词: Affect; Aging; Alleles; BLM gene; Bacteria; Biological Models; Bloom Syndrome; Cells; Chromatin Modeling; Chromosomal Breaks; Chromosomal Rearrangement; Chromosome Breakage; Chromosome Structures; Chromosomes; Chromosomes, Human, Pair 14; Chromosomes, Human, Pair 5; Collection; Complementary DNA; Complex; Controlled Environment; DNA; DNA Repair; DNA Sequence; DNA Sequence Rearrangement; DNA damage checkpoint; DNA repair protein; Disease; Dominant-Negative Mutation; Environment; Family; Frequencies; Gene Structure; Genes; Genetic; Genetic Polymorphism; Genetic Recombination; Genome; Genomic Instability; Goals; Growth; Hereditary Disease; Homologous Gene; Human; Individual; Inherited; Investigation; Light; Location; Maintenance; Malignant Neoplasms; Mass Spectrum Analysis; Measures; Metabolic Pathway; Mismatch Repair; Mutate; Mutation; N-terminal; Numbers; PTPN22 gene; Pathway interactions; Phenotype; Phosphorylation; Phosphorylation Site; Phosphotransferases; Polymerase Chain Reaction; Population; Proteins; Public Health; RECQL gene; Rad52 protein; Range; Rate; Reporting; Role; Rothmund-Thomson syndrome; Saccharomyces cerevisiae; Site-Directed Mutagenesis; Structure; Syndrome; Testing; Thinking; Time; Topoisomerase; Translocation Breakpoint; Upper arm; WRN gene; Werner Syndrome; Western Blotting; Yeasts; base; cancer risk; helicase; homologous recombination; in vivo; inhibitor/antagonist; insight; man; mutant; novel; promoter; sensor; tool; yeast genetics; yeast two hybrid system

DESCRIPTION (provided by applicant): Certain human genetic disorders with extreme cancer risk, such as Bloom's syndrome and Werner syndrome, are associated with mutations in DNA helicases of the RecQ family. Mutants of the yeast Saccharomyces cerevisiae that lack Sgs1, the only RecQ- related DNA helicase in this yeast, have proven to be excellent model systems for some cellular phenotypes of the Bloom's and Werner syndromes, especially with respect to their hyperrecombination phenotype. Although rates of accumulating gross- chromosomal rearrangements are only moderately elevated in sgs1 mutants, it was recently shown that cells lacking Sgs1 are uniquely susceptible to undergoing complex, recurring translocations driven by small regions of homology in highly diverged genes (60-65 % identity). Although Sgs1 and mismatch repair proteins are inhibitors of recombination between similar but nonidentical (homeologous) sequences, only Sgs1 is required for the suppression of these complexes and recurring translocations. The objective of this proposal is to study the intra- and interchromosomal recombination mechanisms that cause homeology-driven translocations in the absence of Sgs1. The specific aims of this study are to: (1) Determine the extent to which gene structure and chromosome environment control the rate and structure of homeology-driven translocations in sgs1 mutants lacking DNA damage checkpoint sensors or chromatin assembly factors. This will be achieved by modifying location, orientation and copy number of translocation targets as well as homology block distance and DNA sequence identity. (2) Elucidate the differential requirement of DNA-damage checkpoint components for the suppression and formation of recurring translocations in sgs1 mutants. (3) Examine the role of functional domains and known physical interactions of Sgs1 in the inhibition of homeology-driven translocations. (4) Determine the ability of the five human RecQ-like DNA helicases to substitute for Sgs1 in the suppression of homeology-driven translocations. SGS1 will be replaced with cDNAs of human RecQ homologs, some of which have been successfully expressed in yeast and suppress some aspects of the sgs1 mutant phenotype. These studies will provide mechanistic insights into the role of RecQ helicases in the maintenance of genome integrity and will shed light on the general mechanisms leading to gross-chromosomal rearrangements, especially gene translocations, which are often associated with human cancers. PUBLIC HEALTH RELEVANCE: The causes of genome instability, which is a hallmark of most cancers, are still unclear. The proposed studies will provide mechanistic insights into the role of DNA unwinding enzymes in the maintenance of genome integrity and will shed light on the general mechanisms leading to chromosomal rearrangements, especially gene translocations, which are often associated with human cancers and chromosome breakage syndromes.

描述（由申请人提供）：某些具有极高癌症风险的人类遗传性疾病，如Bloom综合征和Werner综合征，与RecQ家族DNA解旋酶突变相关。缺乏Sgs 1（该酵母中唯一的RecQ相关DNA解旋酶）的酵母酿酒酵母的突变体已被证明是Bloom和Werner综合征的一些细胞表型的极好模型系统，特别是关于它们的超重组表型。尽管累积的总染色体重排率在sgs 1突变体中仅适度升高，但最近显示缺乏sgs 1的细胞独特地易受高度分化基因（60- 65%同一性）中同源性小区域驱动的复杂、重复易位的影响.虽然Sgs 1和错配修复蛋白是相似但不相同（同源异型）序列之间重组的抑制剂，但只有Sgs 1才能抑制这些复合物和重复易位。这项建议的目的是研究内和染色体间的重组机制，导致同源驱动的易位在Sgs 1的情况下。本研究的具体目的是：（1）确定基因结构和染色体环境在多大程度上控制缺乏DNA损伤检查点传感器或染色质组装因子的sgs 1突变体中同源驱动易位的速率和结构。这将通过改变易位靶标的位置、方向和拷贝数以及同源性阻断距离和DNA序列同一性来实现。(2)阐明sgs 1突变体中DNA损伤检查点组分对抑制和形成重复易位的不同要求。(3)检查功能域的作用和已知的物理相互作用的Sgs 1抑制同源驱动的易位。(4)确定五种人类RecQ样DNA解旋酶在抑制同源驱动的易位中取代Sgs 1的能力。SGS 1将被人RecQ同源物的cDNA取代，其中一些已在酵母中成功表达并抑制了sgs 1突变表型的某些方面。这些研究将为RecQ解旋酶在维持基因组完整性中的作用提供机制见解，并将阐明导致染色体重排的一般机制，特别是基因易位，这通常与人类癌症有关。 公共卫生相关性：基因组不稳定性是大多数癌症的标志，其原因仍不清楚。拟议的研究将为DNA解旋酶在维持基因组完整性方面的作用提供机制见解，并将阐明导致染色体重排的一般机制，特别是基因易位，这通常与人类癌症和染色体断裂综合征有关。