Inflammation as a Mediator of Dynamic DNA Mutations

炎症作为动态 DNA 突变的中介

基本信息

批准号：
8146923
负责人：
Sarah Delaney
金额：
$ 51.44万
依托单位：
BROWN UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2010
资助国家：
美国
起止时间：
2010-09-22 至 2015-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8146923
关键词：
7,8-dihydro-8-oxoguanine 8-hydroxyguanosine Adopted Aflatoxin B Aflatoxin B1 Area Binding Biological Biological Assay Cells Chemicals Chromatin Chronic Complex DNA DNA Damage DNA Packaging DNA Repair Enzymes DNA Sequence Data Diet Modification Disease Disease Progression Environmental Carcinogens Environmental Exposure Epidemiology Event Excision Family Gene Mutation Generations Genes Genetic Anticipation Goals Hepatitis B Hepatitis B Virus Hot Spot Human Huntington Disease In Vitro Individual Infectious Agent Inflammation Inflammatory Inflammatory Response Intervention Knowledge Laboratories Lead Length Link Location Malignant Neoplasms Malignant neoplasm of liver Mediating Mediator of activation protein Methods Modeling Modification Molecular Molecular Conformation Mutation Neurodegenerative Disorders Nitrates Nitric Oxide Nucleosome Core Particle OGG1 gene Oligonucleotides Pathway interactions Patients Pattern Peroxonitrite Play Polymerase Primer Extension Process Proteins Reaction Relative (related person)Relative Risks Research Risk Role Source Structure Superoxides Testing Tissues Trauma Trinucleotide Repeats Work base cytokine design environmental agent experience human Huntingtin protein human disease macrophage mouse model nucleobase oxidation oxidative DNA damage oxidative damage prevent public health relevance repaired research study synergism therapy design

项目摘要

DESCRIPTION (provided by applicant): The goal of this work is to define the mechanism by which DNA damage resulting from an inflammatory response or other environmental sources of damage contribute to dynamic DNA mutations. Dynamic mutations are characterized by the expansion of a triplet repeat sequence such as (CAG)n/(CTG)n and are known to be the primary pathogenic signature of several neurodegenerative disorders. As one example, 5-35 repeats are present in the huntingtin gene of normal individuals but there are more than 40 repeats in Huntington's disease (HD) patients. Using a mouse model of HD, recent work from other laboratories has implicated the oxidative DNA damage product 7,8-dihydro-8-oxoguanine (8-oxoG) in dynamic mutations. Furthermore, the DNA repair enzyme OGG1, which is known to remove 8-oxoG from DNA duplexes, has also been linked to dynamic mutations. Our central hypothesis is based on our preliminary data that (CAG)n and (CTG)n sequences adopt non-B conformations that are hyper-susceptible to DNA damage relative to duplex, including the formation of 8-oxoG. In addition to containing hot spots for DNA damage we have also found that these non-B conformations are not efficiently repaired by OGG1. We postulate that formation of an OGG1- DNA misrepair complex stabilizes the non-B conformation and the DNA is then misreplicated and polymerase incorporates excess triplet repeats. This proposal outlines four specific aims to test our hypothesis. First, studies are proposed to identify the conformation of a family of repetitive CAG/CTG sequences that are prone to dynamic mutations. These experiments will be performed both with oligonucleotide substrates and also DNA in nucleosome core particles (NCP) which model the packaging of DNA in chromatin. Second, the patterns of damage in the triplet repeat DNA will be established using peroxynitrite as the damaging agent. Peroxynitrite is the reactive species produced during inflammation and is known to convert G to 8-oxoG. Third, the OGG1-mediated repair of 8-oxoG-containing DNA substrates, both oligonucleotide and NCP, will be characterized. The final aim of this proposal is to define the processing of damage-containing CAG/CTG sequences by the replication machinery and elucidate the role of OGG1 in modulating replication fidelity. PUBLIC HEALTH RELEVANCE: The goal of this research is to define how the DNA damage derived from an inflammatory response or other environmental sources contribute to dynamic DNA mutations. In particular, this work will describe how the DNA damage product 7,8-dihydro-8-oxoguanine contributes to disease-initiating dynamic mutations. This knowledge is expected to provide the information needed to rationally design interventions to prevent or delay the onset of multiple diseases that are caused by dynamic mutations.

描述（由申请人提供）：这项工作的目标是确定由炎症反应或其他环境损伤源引起的 DNA 损伤导致动态 DNA 突变的机制。动态突变的特征是三联体重复序列的扩展，例如 (CAG)n/(CTG)n，并且已知是几种神经退行性疾病的主要致病特征。例如，正常个体的亨廷顿基因中存在 5-35 个重复，但亨廷顿病 (HD) 患者的亨廷顿基因中存在超过 40 个重复。其他实验室最近的工作使用 HD 小鼠模型，表明氧化 DNA 损伤产物 7,8-二氢-8-氧代鸟嘌呤 (8-oxoG) 与动态突变有关。此外，DNA 修复酶 OGG1（已知可从 DNA 双链体中去除 8-oxoG）也与动态突变有关。我们的中心假设基于我们的初步数据，即 (CAG)n 和 (CTG)n 序列采用非 B 构象，相对于双链体，这些构象极易受到 DNA 损伤，包括 8-oxoG 的形成。除了含有 DNA 损伤热点之外，我们还发现 OGG1 无法有效修复这些非 B 构象。我们假设 OGG1-DNA 错误修复复合物的形成稳定了非 B 构象，然后 DNA 被错误复制，聚合酶掺入了过量的三联体重复序列。该提案概述了检验我们假设的四个具体目标。首先，建议进行研究以确定易于发生动态突变的重复 CAG/CTG 序列家族的构象。这些实验将使用寡核苷酸底物和核小体核心颗粒 (NCP) 中的 DNA 进行，该颗粒模拟染色质中 DNA 的包装。其次，将使用过氧亚硝酸盐作为损伤剂来建立三联体重复 DNA 中的损伤模式。过氧亚硝酸盐是炎症过程中产生的活性物质，已知可将 G 转化为 8-oxoG。第三，将表征OGG1介导的含有8-oxoG的DNA底物（寡核苷酸和NCP）的修复。该提案的最终目的是定义复制机制对含有损伤的 CAG/CTG 序列的处理，并阐明 OGG1 在调节复制保真度中的作用。公共健康相关性：本研究的目的是确定炎症反应或其他环境来源产生的 DNA 损伤如何导致动态 DNA 突变。特别是，这项工作将描述 DNA 损伤产物 7,8-二氢-8-氧代鸟嘌呤如何导致疾病引发的动态突变。这些知识有望提供合理设计干预措施所需的信息，以预防或延缓由动态突变引起的多种疾病的发生。