Role of two AHRs in dioxin sensitivity & resistance

两个 AHR 在二恶英敏感性中的作用

• 批准号: 6578800
• 负责人: MARK HAHN
• 金额: $ 13.44万
• 依托单位: BOSTON UNIVERSITY MEDICAL CAMPUS
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6578800
• 关键词: aromatic hydrocarbon receptor; biomarker; dioxins; environmental exposure; environmental toxicology; fish; gene environment interaction; genetic susceptibility; hazardous substances; receptor expression; water pollution; zebrafish

The overall objective of the basic research proposed here is to understand mechanisms underlying differential sensitivity to the developmental toxicity of dioxins. We will address this objective by elucidating the differences in expression and functional characteristics of two distinct aryl hydrocarbon receptor (AHR1 and AHR2) and an AHR repressor during development using a fish models of dioxin sensitivity and resistance. In the previous grant period, we characterized a PHAH-resistant population of the estuarine teleost Fundulus heteroclitus and New Bedford Harbor, a Superfund site. We showed that these fish were approximately 15-fold less sensitive to TCDD and that this diminished sensitivity was heritable We also identified two distinct AHRs in this species, including a novel AHR form (AHR2) that has been identified in several other species of fish. The proposed research seeks to understand the role of these two AHRs, and related proteins, in differential PHAH sensitivity in this model of dioxin resistance Elucidating the molecular mechanisms underlying such innate or acquired resistance is important for understanding the response of animals to chronic PHAH exposure and identifying molecular markers of susceptibility associated with increased risk in populations and subpopulations of animals, including humans. The central hypothesis to be tested is that alterations in the expression and/or function of AHR1, AHR2, and/or AHRR underlie differential dioxin sensitivity. This hypothesis will be tested primarily in Fundulus, with parallel studies in zebrafish The studies will focus on developmental toxicity of TCDD, which is among the most sensitive effects of this compound in vertebrates. The specific aims of the project are: 1. To measure the developmental expression of AHR1 and AHR2 in embryos and larvae of dioxin sensitive and dioxin resistant fundulus and zebrafish. 2. To determine the effect of TCDD treatment of AHR1 and AHR2 expression in Fundulus and zebrafish embryos. 3. To determine the ligand-binding specificity of Fundulus AHR1 and AHR2. 4. To determine if Fundulus and zebrafish express a homolog (ortholog) of the AHR repressor (AHRR) recently cloned from mice. 5. To determine the DNA- binding specificity of Fundulus AHR1 and AHR2. 6. To assess functional interactions among AHR1, AHR2, and AhRR.

这里提出的基础研究的总体目标是了解二恶英发育毒性差异敏感性的机制。我们将通过使用二恶英敏感性和抗性鱼类模型阐明开发过程中两种不同芳基烃受体（AHR1 和 AHR2）和 AHR 抑制子的表达和功能特征的差异来实现这一目标。在上一个资助期间，我们对河口硬骨鱼 Fundulus heteroclitus 和超级基金地点新贝德福德港的 PHAH 抗性种群进行了表征。我们发现这些鱼对 TCDD 的敏感性降低了大约 15 倍，并且这种敏感性的降低是可遗传的。我们还在该物种中发现了两种不同的 AHR，包括已在其他几种鱼类中发现的一种新的 AHR 形式 (AHR2)。拟议的研究旨在了解这两种 AHR 和相关蛋白质在二恶英抗性模型中不同 PHAH 敏感性中的作用。阐明这种先天性或获得性抗性背后的分子机制对于了解动物对慢性 PHAH 暴露的反应和识别与包括人类在内的动物种群和亚种群风险增加相关的易感性分子标记。要测试的中心假设是 AHR1、AHR2 和/或 AHRR 的表达和/或功能的改变是二恶英敏感性差异的基础。这一假设将主要在眼底进行测试，并在斑马鱼中进行平行研究。研究将集中于 TCDD 的发育毒性，这是该化合物对脊椎动物最敏感的影响之一。该项目的具体目标是： 1. 测量二恶英敏感和二恶英抗性眼底和斑马鱼胚胎和幼虫中AHR1和AHR2的发育表达。 2.确定TCDD处理对眼底和斑马鱼胚胎中AHR1和AHR2表达的影响。 3.确定眼底AHR1和AHR2的配体结合特异性。 4. 确定眼底和斑马鱼是否表达最近从小鼠克隆的 AHR 阻遏蛋白 (AHRR) 的同源物 (直系同源物)。 5.确定眼底AHR1和AHR2的DNA结合特异性。 6. 评估 AHR1、AHR2 和 AhRR 之间的功能相互作用。