Repair in Nucleosomes

核小体修复

• 批准号: 8381907
• 负责人: DAVID S PEDERSON
• 金额: $ 16.38万
• 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
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8381907
• 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（请参阅说明）： 每天，正常的细胞代谢在每个人的DNA中产生30,000或更多的氧化病变 细胞。这些病变中的大多数都是通过基础切除修复（BER）机械去除的。某些有缺陷的BER 酶已被证明是致癌的，将DNA包装到Chromafin中的核小体几乎没有提供 任何免受氧化损伤的保护。项目4于2007年9月添加到原始POI中 识别核小体病变BER中的限速步骤，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，人双功能DNA糖基酶HNTHI 可以从核小体DNA上切除氧化病变，而不会不可逆地破坏核小体，并且 从组蛋白八聚体从组蛋白的自发，短暂的部分解开DNA可有助于进入空间 阻塞病变。以这些结果为基础，该新建议的目标是测试 假设1，即在核小体病变中，从 下一个酶是由Ber附件因子促进的。在检验该假设的过程中，我们将 研究这些结构的核体结构的变化 分析将有助于指导对促进的组蛋白伴侣和染色质重塑剂的未来研究 Ber in Vivo。我们还将检验假设2，是组蛋白的主要序列变体与任何一个 转录活性或非活性染色质影响选定的人DNA糖基化酶对 修复核小体中的氧化损伤。项目2的信息将有助于阐明分子基础 用于HNTHI和含病变的核小体之间的相互作用。提供的信息和试剂 核心A和项目1和3将使我们能够检验假设3，即DNA聚合酶P（POL P）变体 在核小体病变中，有证明的致癌潜力与野生型POL P不同。我们也是 将确定在核小体模板的背景下，POL P（或POL P的致癌变体）可以结合还是 招募Hradsi。核心B将为项目4中的所有研究提供关键试剂。