Mechanism of transcription-associated genome instability

转录相关基因组不稳定的机制

• 批准号: 10207038
• 负责人: Nayun Kim
• 金额: $ 38.71万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2026-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10207038
• 关键词: Address; Adverse event; Animal Model; Binding; Cell Cycle; Cell physiology; Cells; Chromosomal Rearrangement; Chromosomes; Complex; DNA; DNA Damage; DNA Repair; DNA Structure; DNA biosynthesis; DNA-Binding Proteins; DNA-Directed DNA Polymerase; DNA-Directed RNA Polymerase; Development; Disease; Event; Frequencies; G-Quartets; G1 Phase; G2 Phase; Genes; Genetic Recombination; Genetic Transcription; Genome; Genomic Instability; Goals; In Vitro; Investigation; Knowledge; Link; Malignant Neoplasms; Mission; Modeling; Mutagenesis; Mutation; Nucleosides; Process; Proteins; Public Health; Research; Ribonucleotides; Saccharomyces cerevisiae; Stress; Structure; System; Testing; Topoisomerase; Torsion; Transcription Process; Transcriptional Activation; United States National Institutes of Health; Uracil; Work; cancer therapy; density; genetic approach; genome integrity; grasp; in vivo; innovation; metaplastic cell transformation; novel; programs; protein complex; response; tumorigenesis

PROJECT SUMMARY: Changes in the genome such as mutagenesis, duplication, deletions, and recombination bring about somatic diseases like cancer and drive evolutionary processes. My lab has been focused on understanding how such genome instability events occur at incongruently higher frequencies at certain “hotspots.” Quite different from the familiar depiction of chromosomes as stationary strings made up of DNA, genome is more like a busy highway, where many proteins, including topoisomerases in surveillance for irregular helical torsion, bind and/or actively modify DNA. Moreover, mega-complexes of proteins like RNA polymerase and DNA polymerase complexes are dynamically moving along, unwinding, and forcibly distorting DNA while carrying out transcription and replication, sometimes physically colliding with each other. In order to explain why mutation/recombination hotspots are often located within actively transcribed regions, we viewed the multiple DNA-involving processes as an interactive system rather than as each independent activity and identified transcription-associated causes of genome instability. My work was instrumental in showing that mutations resulting from the non-canonical residues, uracil and ribonucleotide, are highly elevated upon transcription activation. Subsequently, novel discoveries in my lab led to the model that non-replicative DNA synthesis occurring in G1- and G2-phases of the cell cycles results in higher uracil density in actively transcribed genes. We also made key findings linking the transcription-generated negative torsional stress with the elevated recombination associated with the DNA secondary structure G-quadruplex or G4 DNA. We further identified G4 DNA-binding proteins that either suppress or exacerbate such G4 DNA-induced genome instability. The central goal of my research program is to uncover fundamental and conserved mechanism underlying mutagenesis and genome rearrangements, which will be important for both the cellular transformation into cancers and responses to chemotherapeutics. Building upon our previous findings, we will continue to address important remaining questions by (1) using tractable genetic approaches to study transcription-associated genome instability in the simple eukaryotic model organism Saccharomyces cerevisiae, (2) developing innovative approaches to test the model of uracil/ribonucleotide incorporation into DNA during G1 and G2, and (3) defining the functional and structural interaction between key G4 DNA-binding proteins and G4 DNA both in vitro and in vivo. Our ongoing investigation should further the understanding of how transcription, replication, and DNA repair work in conjunction either for the benefit or the detriment of genome integrity. Having a comprehensive picture of these interconnected and dynamic processes occurring on the genome will help in predicting how to suppress and correct genome instability events adverse to normal cellular functions.

项目摘要：基因组的变化，例如诱变，重复，缺失和 重组会导致癌症等体疾病和进化过程。我的实验室已经 专注于理解这种基因组不稳定性事件是如何在不一致的较高频率处发生的 某些“热点”。与对染色体的熟悉描述完全不同，因为固定字符串由 DNA，基因组更像是一条繁忙的高速公路，许多蛋白质，包括监视的拓扑异构酶 不规则的螺旋扭转，结合和/或主动修饰DNA。此外，蛋白质的大型复合物等RNA 聚合酶和DNA聚合酶复合物正在动态移动，放松和强行扭曲 DNA进行转录和复制时，有时会相互碰撞。为了 解释为什么突变/重组热点通常位于主动转录区域内，我们看到 多个涉及DNA的过程是一种交互式系统，而不是每个独立活动， 鉴定出与转录相关的基因组不稳定性原因。我的工作有助于表明 由非经典残留物，尿嘧啶和核糖核苷酸产生的突变在高度升高 转录激活。随后，我实验室中的新发现导致了非复制性DNA的模型 在细胞周期的G1和G2强度中发生的合成导致较高的尿嘧啶密度在积极的 转录基因。我们还做出了关键发现，将转录产生的负扭转应​​力与 与DNA二级结构G-四链体或G4 DNA相关的升高重组。我们进一步 鉴定出抑制或加剧这种G4 DNA诱导基因组的G4 DNA结合蛋白 不稳定。我的研究计划的核心目标是发现基本和构成机制 潜在的诱变和基因组重排，这对于两个细胞都很重要 转化为癌症和对化学治疗剂的反应。在我们以前的发现的基础上，我们将 继续使用（1）使用可进行的遗传方法来解决重要的剩余问题 简单的真核模型生物有机体中与转录相关的基因组不稳定性 酿酒酵母，（2）开发创新方法来测试尿嘧啶/核糖核苷酸的模型 G1和G2期间的DNA，以及（3）定义关键G4 DNA结合之间的功能和结构相互作用 蛋白质和G4 DNA在体外和体内都有。 我们正在进行的调查应进一步了解转录，复制和DNA如何 为了获得基因组完整性的利益或确定，维修工作是结合使用的。拥有全面 基因组上发生的这些相互联系和动态过程的图片将有助于预测如何 抑制和纠正基因组不稳定性事件不利于正常的细胞功能。