Excision of Carcinogen-DNA Adducts in Nucleosomes

核小体中致癌物-DNA 加合物的切除

基本信息

批准号：
8520270
负责人：
Nicholas E Geacintov
金额：
$ 30.24万
依托单位：
NEW YORK UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-08-01 至 2017-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8520270
关键词：
Accounting Adenine Advanced Malignant Neoplasm Affect Air Animal Model Area Aromatic Polycyclic Hydrocarbons Attention Bay Region Benzo(a)pyrene Binding Sites Biological Biological Assay Biological Markers Biological Models Cancer Etiology Carcinogens Cell Extracts Cells Chromatin Communities DNA DNA Adducts DNA Packaging DNA Repair DNA lesion Development Environment Environmental Carcinogens Environmental Exposure Epoxy Compounds Etiology Excision Fluorescence Resonance Energy Transfer Food Fossil Fuels Future Glycols Guanine Health Hela Cells Histone H2B Histone H3 Histones Human Hybrids Individual Investigation Laboratory Research Lesion Libraries Liquid substance Lung Malignant Neoplasms Mammalian Cell Methods Modeling Modification Molecular Mutagens NURF Nucleosomes Nucleotide Excision Repair Outcome Study Population Positioning Attribute Predisposition Prevention approach Process Property Proteins Recombinants Relative (related person)Resistance Role Site Smoker Structure System Therapeutic Agents Thermodynamics Time Tissues Tobacco smoke Variant Water adduct aqueous base cancer prevention chemical carcinogen chemical carcinogenesis chromatin remodeling design environmental chemical exhaust hazard histone modification human tissue in vivo insight interest molecular dynamics next generation non-smoker novel prototype reconstitution repaired research study tumorigenic

项目摘要

DESCRIPTION (provided by applicant): Polycyclic aromatic hydrocarbons (PAH) are byproducts of fossil fuel combustion and are present in our air, food and water; the presence of these genotoxic environmental carcinogens in our environment continues to be a hazard to human health. The structural features and biological impact of PAH that distinguish highly active mutagens and tumorigens from structurally related less active, or inactive compounds, have long been of interest for understanding the etiology of human cancers in exposed populations. There are two important sub-classes of PAH that are distinguished by different topological features: (i) the sterically hindered 'fjord' region that causes significant non-planarity in the aromatic ring system of fjord PAH, and (ii) 'bay' region PAH that are sterically unhindered and planar (e.g., the well known environmental carcinogen benzo[a]pyrene). Both types of PAH are metabolically activated to reactive diol epoxide intermediates that react predominantly with guanine and adenine in cellular DNA to form pre-mutagenic covalent adducts in mammalian cells and tissues that can, if not repaired, ultimately contribute to the etiology of human cancers The fjord PAH have attracted significant attention by the chemical carcinogenesis community because they are up to ~ 100-fold more tumorigenic than the bay region prototype benzo[a]pyrene. Previous research from this laboratory has shown that there are remarkable differences in the relative excision efficiencies of different, stereochemically well defined PAH-DNA adducts by the human nucleotide excision repair (NER) system in whole cell extracts. Of particular interest are the observations that PAH- adenine DNA adducts derived from highly tumorigenic fjord PAH are strongly resistant to NER. However, these conclusions are built on NER experiments that were conducted with free DNA in aqueous environments; it is not known whether in biologically more relevant protein environments of nucleosomes, the fundamental sub-units of DNA packaging in the cell, similar hierarchies of NER will be observed with DNA substrates containing the same single bay and fjord PAH-DNA adducts. The objectives of this project are to evaluate NER efficiencies in nucleosomal DNA. The specific aims are: (1) to investigate the role of DNA positioning sequence, thermodynamic stability, nucleosome dynamics, and accessibility of DNA adducts at different sites of the nucleosomal superhelix on NER efficiencies; (2) Evaluate the effects of covalent modification of H3, H4, H2A and H2B histones on the same nucleosome properties and NER; (3) Determine how structurally distinct fjord and bay region PAH-DNA adducts in nucleosomes are differentially excised by the NER system with human cell extracts in nucleosomes, and elucidate how the excision efficiencies are impacted by the histone environment compared with uncomplexed DNA The outcome of this study is expected to provide a molecular basis for future investigations of how bulky carcinogen-DNA lesions are processed in vivo and how nucleosome remodeling factors enhance and facilitate the NER of bulky DNA lesions in cellular environments.

描述（由申请人提供）：多环芳烃（PAH）是化石燃料燃烧的副产品，存在于我们的空气、食物和水中；我们环境中存在的这些遗传毒性环境致癌物继续危害人类健康。 PAH 的结构特征和生物学影响将高活性诱变剂和致瘤剂与结构相关的低活性或无活性化合物区分开来，长期以来一直是了解暴露人群中人类癌症病因学的兴趣所在。 PAH 有两个重要的子类，它们具有不同的拓扑特征：(i) 空间位阻“峡湾”区域，导致峡湾 PAH 芳环系统显着的非平面性，以及 (ii)“海湾”区域PAH 是空间无阻碍且平面的（例如，众所周知的环境致癌物苯并[a]芘）。两种类型的 PAH 均被代谢激活为反应性二醇环氧化物中间体，这些中间体主要与细胞 DNA 中的鸟嘌呤和腺嘌呤反应，在哺乳动物细胞和组织中形成诱变前共价加合物，如果不进行修复，最终可能导致人类癌症的病因学。峡湾多环芳烃引起了化学致癌学界的极大关注，因为它们的致瘤性比海湾地区原型苯并[a]芘高约 100 倍。该实验室之前的研究表明，全细胞提取物中人核苷酸切除修复（NER）系统对不同立体化学明确的 PAH-DNA 加合物的相对切除效率存在显着差异。特别令人感兴趣的是，来自高致瘤性峡湾 PAH 的 PAH-腺嘌呤 DNA 加合物对 NER 具有很强的抵抗力。然而，这些结论是建立在 NER 实验的基础上的，这些实验是在水环境中使用游离 DNA 进行的；目前尚不清楚，在核小体（细胞中 DNA 包装的基本亚单位）的生物学上更相关的蛋白质环境中，是否会使用含有相同单湾和峡湾 PAH-DNA 加合物的 DNA 底物观察到类似的 NER 层次结构。该项目的目标是评估核小体 DNA 的 NER 效率。具体目标是：（1）研究DNA定位序列、热力学稳定性、核小体动力学以及核小体超螺旋不同位点DNA加合物的可及性对NER效率的作用；（2）评估H3、H4、H2A和H2B组蛋白共价修饰对相同核小体性质和NER的影响； (3) 确定核小体中结构不同的峡湾和海湾区域 PAH-DNA 加合物如何被 NER 系统与核小体中的人类细胞提取物进行差异性切除，并阐明与未复合的 DNA 相比，组蛋白环境如何影响切除效率。这项研究有望为未来研究大体积致癌物-DNA损伤如何在体内处理以及核小体重塑因子如何提供分子基础增强和促进细胞环境中大量 DNA 损伤的 NER。