Excision of Carcinogen-DNA Adducts in Nucleosomes

核小体中致癌物-DNA 加合物的切除

• 批准号: 8677822
• 负责人: Nicholas E Geacintov
• 金额: $ 31.37万
• 依托单位: NEW YORK UNIVERSITY
• 依托单位国家: 美国
• 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/8677822
• 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

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，并且存在于我们的空气，食物和水中；这些遗传毒性环境致癌物在我们的环境中的存在仍然是对人类健康的危害。 PAH的结构特征和生物学影响将高度活跃的诱变剂和肿瘤与结构相关的较小或非活性化合物区分开来，长期以来一直感兴趣地了解暴露群体中人类癌的病因。 PAH有两个重要的pah层，这些拓扑特征具有不同的拓扑特征：（i）在峡湾PAH的芳香环系统中引起大量非平面性的空间受阻的“峡湾”区域，以及（ii）'Bay'PAH，它们在空间上不受欢迎和平面（E.G.两种类型的PAH都被代谢激活为反应性二醇环氧中间体，这些中间体主要与细胞DNA中的鸟嘌呤和腺嘌呤反应，以形成哺乳动物的细胞和组织中的毛氨酸和腺嘌呤，从而在哺乳动物的细胞和组织中可以（如果无法修复，最终都会促成fosen carcogen），因为它们会促成fojord cancogen，因为它们的fogjod carcogen carcogen cansogen的效果很大，因为它们是fogen carcogen的重大关注〜比海湾区域原型苯并[a] pyrene的肿瘤性更大。 该实验室的先前研究表明，在整个细胞提取物中，人核苷酸切除修复（NER）系统的不同，立体化学上定义明确的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观察到，源自高度肿瘤峡湾PAH的Pah-腺嘌呤DNA加合物对NER具有强烈的抵抗力。但是，这些结论是基于在水性环境中自由DNA进行的NER实验。在核小体的生物学上更相关的蛋白质环境中，是否尚不清楚细胞中DNA包装的基本子单元，与含有同一单个单湾和峡湾PAH-DNA加合物的DNA底物观察到NER的类似层次结构。该项目的目标是评估核小体DNA中的NER效率。具体目的是：（1）研究DNA定位序列，热力学稳定性，核小体动力学以及DNA加合物在NER效率上不同位点的DNA加合物的可及性； （2）评估H3，H4，H2A和H2B组蛋白对相同核小体性能和NER的共价修饰的影响； （3）确定在核小体中结构不同的峡湾和海湾区域PAH-DNA如何通过NER系统与核小体中的人类细胞提取物差异化，并阐明了切除效率如何受组蛋白环境的影响，与未来的研究相比，组蛋白环境如何为未来的研究提供了研究的结果。体内和核小体重塑因子如何增强和促进细胞环境中笨重的DNA病变的NER。