Suppression of translocations by RecQ-like DNA helicases

RecQ 样 DNA 解旋酶抑制易位

• 批准号: 8144579
• 负责人: Kristina Schmidt
• 金额: $ 3.71万
• 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/8144579
• 关键词: Affect; Age; 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; Human Genetics; Individual; Inherited; Investigation; Light; Location; Maintenance; Malignant Neoplasms; Mass Spectrum Analysis; Measures; Metabolic Pathway; Mismatch Repair; Mutate; Mutation; N-terminal; PTPN22 gene; Pathway interactions; Phenotype; Phosphorylation; Phosphorylation Site; Phosphotransferases; Population; Proteins; RECQL gene; Rad52 protein; Reporting; Role; Rothmund-Thomson syndrome; Saccharomyces cerevisiae; Site-Directed Mutagenesis; Structure; Syndrome; Testing; Time; Topoisomerase; Translocation Breakpoint; Werner Syndrome; Western Blotting; Yeasts; arm; base; cancer risk; helicase; homologous recombination; human DNA; in vivo; inhibitor/antagonist; insight; man; mutant; novel; promoter; public health relevance; 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)：某些具有极端癌症风险的人类遗传疾病，如布卢姆综合征和沃纳综合征，与RecQ家族DNA解旋酶的突变有关。酿酒酵母中唯一与RecQ相关的DNA解旋酶Sgs1缺失的突变株已被证明是Bloom‘s综合征和Werner综合征某些细胞表型的优秀模式系统，特别是关于它们的超重组表型。尽管在sgs1突变体中累积的总染色体重排的速率仅适度增加，但最近的研究表明，缺乏sgs1的细胞特别容易经历复杂的、反复发生的易位，这些易位是由高度分散的基因中的小同源区域驱动的(60-65%的同源性)。虽然SGS1和错配修复蛋白是相似但不相同(同源)序列之间重组的抑制剂，但只需要SGS1来抑制这些复合体和反复发生的易位。这项建议的目的是研究在缺少SGS1的情况下导致同源易位的染色体内和染色体间重组机制。本研究的具体目的是：(1)确定在缺乏DNA损伤检查点传感器或染色质组装因子的sgs1突变体中，基因结构和染色体环境在多大程度上控制同源基因驱动的易位的速率和结构。这将通过修改易位靶标的位置、方向和拷贝数以及同源区块距离和DNA序列同一性来实现。(2)阐明sgs1突变体中DNA损伤检查点成分对抑制和形成复发性易位的不同要求。(3)研究SGS1的功能结构域和已知的物理相互作用在抑制同源易位中的作用。(4)确定5种人类RecQ样DNA解旋酶在抑制同源易位中替代SGS1的能力。SGS1将被人RecQ同源物的cDNA取代，其中一些已经在酵母中成功表达，并抑制了sgs1突变表型的某些方面。这些研究将提供对RecQ解旋酶在维持基因组完整性中的作用的机械性见解，并将阐明导致大染色体重排的一般机制，特别是经常与人类癌症相关的基因易位。与公共卫生相关：基因组不稳定的原因仍不清楚，基因组不稳定是大多数癌症的标志。拟议的研究将提供对DNA解旋酶在维持基因组完整性中的作用的机械性见解，并将揭示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。