Trinucleotide Repeat Instability via DNA Damage and Repair

DNA 损伤和修复导致的三核苷酸重复不稳定性

• 批准号: 9182889
• 负责人: Yuan Liu
• 金额: $ 32.11万
• 依托单位: FLORIDA INTERNATIONAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-12-09 至 2018-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9182889
• 关键词: 8-hydroxyguanosine; Address; Adverse effects; Affect; Alkylating Agents; Base Excision Repairs; Base Pairing; CAG repeat; Chromates; Cleaved cell; Coenzymes; Collaborations; Complement; Country; DNA; DNA Damage; DNA Polymerase beta; DNA Repair; DNA Repair Gene; DNA Single Strand Break; DNA Structure; DNA biosynthesis; DNA glycosylase; DNA-(apurinic or apyrimidinic site) lyase; DNA-Directed DNA Polymerase; Data; Development; Diagnosis; Disease; Etiology; Excision; Exodeoxyribonuclease I; Exposure to; Foundations; GC Rich Sequence; General Population; Genes; Goals; Human; In Vitro; Inherited; Knowledge; Lead; Length; Lesion; Link; Malignant Neoplasms; Mediating; Molecular; Nerve Degeneration; Neurodegenerative Disorders; Nucleotides; OGG1 gene; Oxides; Pathway interactions; Pattern; Polymerase; Positioning Attribute; Prevention; Proteins; RTH-1 Nuclease; Research; Research Project Grants; Risk Assessment; Roentgen Rays; Role; Site; Somatic Cell; Stress; Structure; Surgical Flaps; Surgical incisions; Testing; Tissues; Toxic Environmental Substances; Translational Research; Trinucleotide Repeat Expansion; Trinucleotide Repeats; United States; Variant; Vinyl Chloride; Vitronectin; WRN gene; adduct; base; chemotherapeutic agent; effective therapy; endonuclease; experience; genetic variant; genotoxicity; human disease; in vivo; innovation; insight; new therapeutic target; novel; prevent; protein protein interaction; public health relevance; repair enzyme; repaired; targeted agent; temozolomide; therapeutic DNA

DESCRIPTION (provided by applicant): Inherited trinucleotide repeat (TNR) instability, (i.e. expansions and deletions/contractions) is associated with more than 40 human familial neurodegenerative diseases and cancer. Non-inherited somatic TNR instability may be involved in the development of these diseases in the general public. No effective treatment for TNR- related diseases is yet available, partially because of a poor understanding of the underlying mechanisms. We have recently discovered that DNA base damage and base excision repair (BER) initiate and modulate somatic CAG repeat expansion and deletion by inducing single-strand DNA (ssDNA) breaks and promoting the formation of GC self-base-pairing hairpins. This indicates a new role of DNA base lesions, ssDNA breaks and BER in modulating TNR instability. To explore the potential of DNA damage and BER as new targets for the prevention and treatment of TNR-related diseases, in this project we seek to understand how environmentally and chemotherapeutically induced ssDNA breaks and their inefficient repair are involved in somatic TNR instability during BER. This goal will be achieved by pursuing three Specific Aims. Aim 1 is to determine if the accumulation of environmentally and chemotherapeutically induced DNA base lesions and ssDNA breaks can preferentially lead to CAG repeat instability in a site-specific manner. Site-specific accumulation of the ssDNA breaks in CAG/CTG repeat tracts induced by environmental toxicants and chemotherapeutic agents such as vinyl chloride and temozolomide will be determined. The unique patterns of ssDNA break accumulation induced by DNA-damaging agents will be correlated with repeat expansion and deletion to identify damage- specific "position effects" on CAG repeat instability. The effects will be further examined under imbalanced levels of BER enzymes and cofactors to determine if TNR instability can be modulated by compromised BER efficiency. Aim 2 is to test the hypothesis that inefficient BER facilitates CAG repeat deletion by promoting the formation of multiple non-B-form DNA structures. This will be done by determining if inefficient DNA synthesis by DNA polymerases (Pol ß genetic variants, Pol κ) can facilitate the accumulation of a template hairpin and promote TNR deletion. Aim 3 is to determine if TNR expansion and deletion can be prevented by efficiently disrupting non-B-form DNA structures through BER protein-protein interactions and functional coordination. This project addresses the fundamental mechanisms underlying DNA damage-induced somatic TNR instability by dissecting the interplay among environmental and chemotherapeutic DNA damage, BER, and TNR instability. The results will provide important new insights into how exposure to environmental and chemotherapeutic stresses may influence the development and progression of TNR-related human diseases in the general population, and how these adverse effects can be prevented by DNA damage repair. This will help to identify novel targets for prevention, diagnosis, and treatment of TNR-related diseases, and provide new information for risk assessment of environmentally and chemotherapeutically induced genotoxic effects.

描述（由申请人提供）：遗传性三核苷酸重复 (TNR) 不稳定性（即扩展和缺失/收缩）与 40 多种人类家族性神经退行性疾病和癌症相关，非遗传性体细胞 TNR 不稳定性可能与这些疾病的发生有关。目前尚无针对 TNR 相关疾病的有效治疗方法，部分原因是我们最近发现 DNA 碱基损伤和相关疾病的潜在机制尚不清楚。碱基切除修复（BER）通过诱导单链DNA（ssDNA）断裂并促进GC自碱基配对发夹的形成来启动和调节体细胞CAG重复扩增和缺失，这表明DNA碱基损伤，ssDNA断裂的新作用。为了探索 DNA 损伤和 BER 作为预防和治疗 TNR 相关疾病的新靶点的潜力，在这个项目中，我们试图了解环境和化疗是如何诱导的。 ssDNA 断裂及其低效修复与 BER 期间的体细胞 TNR 不稳定有关。这一目标将通过追求三个具体目标来实现，目标 1 是确定环境和化疗诱导的 DNA 碱基损伤和 ssDNA 断裂的积累是否会优先导致 CAG。由环境毒物和化疗剂（如乙烯基）引起的 CAG/CTG 重复序列中 ssDNA 断裂的位点特异性积累。将确定由 DNA 损伤剂诱导的 ssDNA 断裂积累的独特模式与重复扩增和缺失，以确定对 CAG 重复不稳定性的损伤特异性“位置效应”。目的 2 是测试低效 BER 通过促进多个重复序列的形成而促进 CAG 重复删除的假设。这将通过确定 DNA 聚合酶（Pol ß 遗传变体，Pol κ）的低效 DNA 合成是否会促进模板发夹的积累并促进 TNR 删除来完成。通过 BER 蛋白-蛋白相互作用和功能协调有效破坏非 B 型 DNA 结构，可以防止扩增和缺失。该项目通过剖析环境和 TNR 之间的相互作用，解决了 DNA 损伤引起的体细胞 TNR 不稳定的基本机制。化疗 DNA 损伤、BER 和 TNR 不稳定性这些结果将为了解环境和化疗应激如何影响普通人群中 TNR 相关人类疾病的发生和进展，以及如何预防这些不利影响提供重要的新见解。这将有助于确定预防、诊断和治疗 TNR 相关疾病的新靶标，并为环境和化疗引起的基因毒性效应的风险评估提供新信息。