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（由适用提供）：遗传的三核苷酸重复（TNR）不稳定性（即扩张和缺失/收缩）与40多种人类家庭神经退行性疾病和癌症有关。非系列的体细胞TNR不稳定性可能参与了公众的这些疾病的发展。尚无对TNR相关疾病的有效治疗方法，部分原因是对基本机制的了解不足。我们最近发现，DNA碱基损伤和基本惊喜修复（BER）启动并通过诱导的单链DNA（ssDNA）破裂并促进GC自生态发夹的形成，从而启动并调节体细胞CAG重复膨胀和删除。这表明DNA碱病变，ssDNA断裂和BER在调节TNR不稳定性中的新作用。为了探索DNA损伤和BER作为预防和治疗TNR相关疾病的新目标，在该项目中，我们试图了解环境和化学疗法诱导的ssDNA断裂及其无效修复如何涉及BER期间的体细胞TNR不稳定。通过追求三个具体目标来实现此目标。 AIM 1是确定环境和化学诱导的DNA碱病变和ssDNA断裂的准确性是否可以以特异性方式导致CAG重复不稳定。环境有毒物质和化学治疗剂（如乙烯基氯化物和替莫唑胺）诱导的CAG/CTG重复区中ssDNA断裂的位点特异性积累。由DNA破坏剂引起的ssDNA断裂积累的独特模式将与重复膨胀和缺失相关，以识别损伤 - 特定的“位置效应”对CAG重复不稳定性的损害。将在BER酶和辅助因子的不平衡水平下进一步检查这些效果，以确定是否可以通过受损的BER效率来调节TNR不稳定。目的2是检验以下假设：效率低下的BER设施CAG重复缺失通过促进多个非B形DNA结构的形成。这将通过确定DNA聚合酶（polß遗传变异，POLκ）是否效率低下的DNA合成来完成，可以促进模板发夹的积累并促进TNR缺失。 AIM 3是通过通过BER蛋白 - 蛋白质相互作用和功能协调有效破坏非B形式的DNA结构来确定TNR扩展和缺失。该项目通过剖析环境和化学治疗DNA损伤，BER和TNR不稳定性之间的相互作用来解决DNA损伤诱导的体细胞不稳定的基本机制。该结果将提供重要的新见解，了解如何影响一般人群中与TNR相关的人类疾病的发展和进展，以及如何通过DNA损伤修复来预防这些不良反应。这将有助于确定针对TNR相关疾病的预防，诊断和治疗的新颖目标，并为环境和化学疗法诱导的遗传毒性作用提供新的信息，以评估风险评估。