Repair in Nucleosomes

核小体修复

• 批准号: 8725061
• 负责人: DAVID S PEDERSON
• 金额: $ 15.88万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-03 至 2016-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8725061
• 关键词: Accounting; Address; Affect; Base Excision Repairs; Binding; Cells; Chromatin; Chromosome Segregation; Complex; DNA; DNA Binding; DNA Damage; DNA Packaging; DNA Repair Enzymes; DNA glycosylase; DNA ligase III; DNA-Directed DNA Polymerase; Enzymes; Foundations; Future; Genes; Genome; Goals; Hand; Histones; Human; Individual; Instruction; Left; Lesion; Linker DNA; Metabolism; Molecular; Molecular Chaperones; Nucleosomes; Oligonucleotides; Oncogenic; Polymerase; Positioning Attribute; Process; Proteins; Radiation; Radiation therapy; Reaction; Reagent; Recruitment Activity; Refractory; Relative (related person); Sodium Chloride; Structure; Testing; Therapeutic; Variant; base; cancer therapy; chromatin remodeling; cytotoxic; dimer; enhancing factor; human DNA; in vivo; oxidative DNA damage; oxidative damage; promoter; repair enzyme; repaired; thymine glycol; tumor

PROJECT SUMMARY (See Instructions): Every day, normal cellular metabolism produces 30,000 or more oxidative lesions In the DNA of each human cell. Most of these lesions are removed by the base excision repair (BER) machinery. Certain defective BER enzymes have been shown to be oncogenic, Nucleosomes that package DNA into chromafin provide little if any protection from oxidative damage. Project 4 was added to the original POI in September, 2007, to identify rate-limiting steps in the BER of lesions in nucleosomes, and to investigate mechanisms that cells use to circumvent these limits. Studies to date indicate that the human bifunctional DNA glycosylase hNTHI can excise oxidative lesions from nucleosomal DNA without irreversibly disrupting the nucleosome, and that spontaneous, transient partial unwrapping of DNA from the histone octamer facilitates access to sterically occluded lesions. With these results as a foundation, the goals for this new proposal are to test HYPOTHESIS 1, that during BER of lesions in nucleosomes, there is a stepwise hand-off of substrates from one enzyme to the next, facilitated by BER accessory factors. In the course of testing this hypothesis, we will investigate changes in nucleosome structure that accompany individual steps in BER, These structural analyses will help guide future studies of histone chaperones and chromatin remodeling agents that facilitate BER in vivo. We also will test HYPOTHESIS 2, that histone primary sequence variants associated with either transcriptionally active or inactive chromatin influence the capacity of selected human DNA glycosylases to repair oxidative damages in nucleosomes. Information from Project 2 will help elucidate the molecular basis for interactions between hNTHI and lesion-containing nucleosomes. Information and reagents provided by Core A and Projects 1 and 3 will enable us to test HYPOTHESIS 3, that DNA polymerase p (Pol P) variants with demonstrated oncogenic potential differ from wild type Pol p in BER of lesions in nucleosomes. We also will determine If, in the context of nucleosomal templates, Pol p (or oncogenic variants of Pol P) can bind or recruit hRadSI. Core B will provide critical reagents for all of the studies in Project 4.

项目摘要（参见说明）： 每天，正常的细胞代谢会在每个人的 DNA 中产生 30,000 个或更多的氧化损伤 细胞。大多数这些病变可以通过碱基切除修复（BER）机器去除。某些有缺陷的 BER 酶已被证明具有致癌性，将 DNA 包装成嗜铬蛋白的核小体几乎没有提供任何致癌作用。 任何防止氧化损伤的保护措施。项目 4 于 2007 年 9 月添加到原始 POI 中，以 确定核小体病变 BER 的限速步骤，并研究细胞的机制 用于规避这些限制。迄今为止的研究表明，人类双功能 DNA 糖基化酶 hNTHI 可以在不不可逆地破坏核小体的情况下从核小体 DNA 中切除氧化损伤，并且 DNA 从组蛋白八聚体中自发、短暂地部分解开，有利于空间接触 闭塞的病灶。以这些结果为基础，这个新提案的目标是测试 假设 1，在核小体损伤的 BER 过程中，底物从 在 BER 辅助因素的推动下，一种酶转移到另一种酶。在检验这一假设的过程中，我们将 研究伴随 BER 各个步骤的核小体结构的变化，这些结构 分析将有助于指导组蛋白伴侣和染色质重塑剂的未来研究，从而促进 体内 BER。我们还将测试假设 2，组蛋白一级序列变体与以下任一相关： 转录活性或非活性染色质影响选定的人类 DNA 糖基化酶的能力 修复核小体的氧化损伤。项目 2 的信息将有助于阐明分子基础 用于 hNTHI 和含有病变的核小体之间的相互作用。信息和试剂提供者 核心 A 以及项目 1 和 3 将使我们能够测试假设 3，即 DNA 聚合酶 p (Pol P) 变体 已证实具有致癌潜力的 Pol p 在核小体病变的 BER 方面与野生型 Pol p 不同。我们也 将确定在核小体模板的背景下，Pol p（或 Pol P 的致癌变体）是否可以结合或 招募 hRadSI。核心 B 将为项目 4 中的所有研究提供关键试剂。