Analysis and Effect of Persistent Ah Receptor Activation

Ah受体持续激活的分析及效果

• 批准号: 6867595
• 负责人: MICHAEL STEVEN DENISON
• 金额: $ 24.54万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-12-01 至 2008-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6867595
• 关键词: DNA; DNA footprinting; acetylcholine; carbopolycyclic compound; chemical binding; cholinergic receptors; chromatin; chromatin immunoprecipitation; gene expression; gene induction /repression; genetically modified animals; heterocyclic polycyclic compound; laboratory mouse; microarray technology; molecular cloning; polymerase chain reaction; protein structure; receptor expression; tissue /cell culture; toxicant interaction

The overall goal of our research is to understand the molecular mechanism by which halogenated aromatic hydrocarbons (HAHs), polycyclic aromatic hydrocarbons (PAHs) and related chemicals interact with the Ah receptor (AhR) to alter gene expression and responses of cells and animals to these inducers. The AhR is a ligand-dependent transcription factor that mediates the majority of the biological and toxicological actions of HAHs and PAHs. Significant species, tissue- and ligand-specific differences have been reported in the spectrum of toxic and biological responses observed following exposure to HAHs and PAHs but also in the concentration of chemicals needed to produce these responses, with HAHs being significantly more potent than PAHs. Although differential responsiveness to HAHs and PAHs can result from a variety of biochemical and physiological characteristics in target cells, it is generally accepted that the greater toxicological and biological potency of HAHs results from their significantly higher AhR binding affinity and resistance to metabolism. Recent evidence has demonstrated that differences exist in the potency and efficacy of HAHs and PAHs as activators of AhR-dependent gene expression that are separate from those directly related to their persistence and metabolic stability in the cell. We hypothesize that some of the differences in the potency and biological responses produced by PAHs and HAHs are directly related to ligand-specific differences in the structure of the AhR protein and/or AhR protein complex that alters the functionality of the AhR and its relative affinity/specificity for DNA/chromatin. Accordingly, here we propose to conduct detailed comparative studies to characterize the similarities and differences in the activation and persistence of ligand and DNA/chromatin binding of mouse AhR occupied by selected HAHs and PAHs in vitro and in cells in culture and to identify and characterize ligand-dependent changes in AhR structure. The DREnucleotide specificity for transcriptional activation of gene expression by AhR complexes bound by HAHs and PAHs and similarities and differences in HAH- and PAH-induction of gene expression assessed in cells culture and CYP null mice using microarrays. Finally, transgenic animals expressing a consitutively active (e.g., ligand-independent) AhR complex will be generated to examine contributions of the AhR and the ligand to the adverse effects associated with this persistent AhR activation. Overall, these studies will provide insights into the species- and ligand-specific differences in the ability of HAHs and PAHs to activate the AhR, the mechanisms responsible for the persistence of this activation and the role that it plays in the toxic and biological effects of HAHs and PAHs.

我们研究的总体目的是了解卤化芳基烃（HAHS），多环芳族烃（PAHS）和相关化学物质与AH受体（AHR）相互作用以改变基因表达以及细胞和动物对这些诱导剂的基因表达以及反应。 AHR是一个依赖配体的转录因子，它介导了HAHS和PAH的大多数生物学和毒理学作用。在暴露于HAHS和PAHS之后观察到的有毒和生物学反应的范围中，已经报道了重要的物种，组织和配体特异性差异，还报告了产生这些反应所需的化学物质浓度，而HAHS比PAHS明显更有效。尽管对HAH和PAH的差异反应性可能是由于靶细胞中各种生化和生理特征所致，但人们普遍认为，HAH的较高毒理学和生物学效力是由于它们明显更高的AHR结合亲和力以及对代谢的耐药性的明显更高。最近的证据表明，HAH和PAHS作为AHR依赖性基因表达的激活因子的效力和功效存在差异，这些基因表达与与细胞中其持久性和代谢稳定性直接相关的基因表达存在。我们假设PAHS和HAH产生的效力和生物学反应的某些差异与AHR蛋白和/或AHR蛋白复合物的结构的配体特异性差异直接相关，从而改变了AHR及其对DNA/Chromatin的相对亲和力/特异性的功能。因此，在这里，我们建议进行详细的比较研究，以表征在培养和培养中所选的HAHS和PAHS所占据的小鼠AHR的配体和DNA/染色质结合的激活和持续性的相似性和差异，以识别和识别和识别和识别和表征AHR结构中的配体变化。 Drenucleotide 通过HAHS结合的AHR复合物对基因表达的转录激活的特异性 PAHS以及使用微阵列评估在细胞培养和CYP无效小鼠中评估的基因表达的HAH和PAH诱导的相似性以及差异。最后，将生成表达共识活性（例如，独立于配体的）AHR复合物的转基因动物，以检查AHR和配体对与这种持续AHR激活相关的不良反应的贡献。总体而言，这些研究将提供有关HAH和PAH激活AHR的能力的物种和配体特异性差异的见解，造成这种激活持续性的机制及其在HAHS和PAHS的有毒和生物学作用中所起的作用。