Molecular Mechanisms of Dioxin Action

二恶英作用的分子机制

• 批准号: 6951895
• 负责人: Alvaro Puga
• 金额: $ 35.63万
• 依托单位: UNIVERSITY OF CINCINNATI
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-09-30 至 2009-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6951895
• 关键词: aromatic hydrocarbon receptor; cell cycle; cell growth regulation; chromatin immunoprecipitation; cyclin dependent kinase; dioxins; environmental toxicology; enzyme activity; enzyme inhibitors; gene expression; genetic regulation; molecular pathology; polymerase chain reaction; protein protein interaction; tissue /cell culture; western blottings

DESCRIPTION (provided by applicant): The long-term objective of this proposal is to understand the molecular mechanisms underlying the biological responses to dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD) exposure. TCDD, the prototypic dioxin and a model for many other organochlorinated compounds, produces many apparently unrelated biological effects, ranging from chloracne in humans to developmental teratogenesis, tumor promotion, thymic atrophy, wasting syndrome and death in laboratory animals. In addition, TCDD, a rodent carcinogen, is strongly suspected of being carcinogenic also in humans. The molecular basis of the biological effects of TCDD is largely unknown. Dioxin is a ligand for the aromatic hydrocarbon (Ah) receptor (AHR), which, as a dimer with the Ah receptor nuclear translocator protein ARNT, mediates the transcriptional activation of genes in the CYP 1 family of cytochrome P450 monooxygenases. However, activation of the CYP1A1, CYP1A2 and CYP1 B1 genes, although one of the best characterized effects of Ah receptor activation by TCDD, does not adequately explain the diversity of TCDD effects. Our recent global expression profiling analyses of human hepatoma cells shows that exposure to dioxin induces or represses a total of more than 300 genes, with repression being the more frequent. Induction may readily be explained by the transactivating potential of the AHR, but gene repression is a novel effect of the activated AHR that is uncharacterized at the molecular level. The goal of the experiments proposed here is to define and characterize the regulatory interactions between the activated AHR and other transcription factors, co-regulators and chromatin remodeling factors responsible for the effects of dioxin on gene expression. The major objectives of this work are, (1) to define the role of discrete domains of the AHR in gene regulation; (2) to use proteomic analyses to identify AHR coregulatory partners in gene induction and repression; and (3) to clone the promoters of AHR regulated genes and characterize their response to dioxin exposure. Results from these experiments will be crucial for our understanding of the long-range biological consequences of exposure to dioxin and to other organochlorinated compounds and will help formulate an adequate rationale to deal with health problems arising from an ever-increasing exposure to these environmental agents.

描述（由申请人提供）：该提案的长期目标是了解对二恶英（2,3,7,8-甲基氯迪本佐-P-二恶英； TCDD）的生物学反应的基础机制。 TCDD是许多其他有机氯化合物的原型二恶英和模型，从人类的氯酸氯氯氯此产生了许多显然无关的生物学作用，到发育发生，肿瘤促进，胸腺萎缩，胸腺萎缩，浪费综合征和实验室动物的死亡。此外，强烈怀疑啮齿动物致癌的TCDD在人类中也具有致癌性。 TCDD生物学作用的分子基础在很大程度上未知。二恶英是一种芳族烃（AH）受体（AHR）的配体，该配体作为二聚体，用AH受体核转运蛋白ARNT介导CYP 1的CYTOCHROME P450单一助剂酶的CYP 1家族中基因的转录激活。然而，尽管CYP1A1，CYP1A2和CYP1 B1基因的激活虽然TCDD对AH受体激活的最佳特征作用之一，但并不能充分解释TCDD效应的多样性。我们最近对人肝癌细胞进行的全球表达分析分析表明，暴露于二恶英会诱导或抑制总共300多个基因，抑制更为频繁。诱导很容易通过AHR的反式激活潜力来解释，但是基因抑制是激活的AHR的新作用，在分子水平上未表征。这里提出的实验的目的是定义和表征活化的AHR与其他转录因子，共同调节剂和染色质重塑因子之间的调节相互作用，导致二恶英对基因表达的影响。这项工作的主要目标是（1）定义AHR离散域在基因调节中的作用； （2）使用蛋白质组学分析来识别基因诱导和抑制中的AHR核心调节伙伴； （3）克隆AHR调节基因的启动子并表征其对二恶英暴露的反应。这些实验的结果对于我们理解暴露于二恶英和其他有机氯的化合物的远程生物学后果至关重要，并将有助于提出足够的理由来解决因对这些环境药物的不断增长而引起的健康问题。