Aryl Hydrocarbon Receptor-Mediated Epigenetic Processes

芳基烃受体介导的表观遗传过程

• 批准号: 9124375
• 负责人: Cornelis Johan Elferink
• 金额: $ 44.28万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9124375
• 关键词: ARNT gene; ARNT protein; Affect; Amino Acids; Arginine; Aryl Hydrocarbon Receptor; Binding; Binding Sites; Biological; Biological Assay; Biology; Carbamyl Phosphate; ChIP-seq; Chromatin; Co-Immunoprecipitations; Complex; DNA; DNA Binding; Data; Dioxins; EMSA; Environmental Pollutants; Environmental Pollution; Enzymes; Epigenetic Process; Event; Exposure to; Fluorescence Recovery After Photobleaching; Functional disorder; Gene Expression; Gene Targeting; General Population; Genes; Genetic Transcription; Genome; Genomics; Health; Heterodimerization; Histone H1; Histone H1(s); Histone H3; Histones; Human; Immune System Diseases; Immunoprecipitation; Ligands; Link; Lysine; Malignant Neoplasms; Mass Spectrum Analysis; Mediating; Mediator of activation protein; Modification; Molecular; Molecular Conformation; Monitor; Outcome; Post-Translational Protein Processing; Process; Protein-arginine deiminase; Proteins; Proteomics; Reaction; Recombinant Proteins; Recombinants; Recruitment Activity; Research; Response Elements; Risk; Role; Shotgun Sequencing; Signal Transduction; Site; Tars; Tertiary Protein Structure; Testing; Tetrachlorodibenzodioxin; Toxic effect; Transcriptional Activation; Transcriptional Regulation; Tumor Suppressor Proteins; Xenobiotics; activating transcription factor; base; chromatin remodeling; design; genetic signature; homocitrulline; innovation; insight; mutant; novel; pollutant; protein protein interaction; signal processing; transcriptome

DESCRIPTION (provided by applicant): The Aryl hydrocarbon Receptor (AhR) is a mediator of xenobiotic toxicity, best recognized for conveying the deleterious human health effects following exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, dioxin) and related environmental contaminants. Mechanistically, the AhR is known to function as a ligand-activated transcription factor that binds to a canonical xenobiotic response element (XRE) in association with its heterodimerization partner, the AhR nuclear translocator (Arnt) protein. However, within the repertoire of AhR target genes identified in recent years, many lack a clearly defined XRE, highlighting the growing realization that AhR-mediated gene expression appears to involve additional mechanisms distinct from the well- characterized process involving the XRE. We recently identified a non-consensus XRE (NC-XRE) that recruits a novel AhR-containing protein-DNA complex. DNA binding and functional studies confirmed that NC-XRE binding by the AhR is independent of the Arnt protein, and instead occurs in partnership with the Kruppel-like factor 6 (KLF6) tumor suppressor. Mass spectrometry-based proteomics identified Carbamoyl-Phosphate Synthase 1 (CPS1) as an additional component of the TCDD induced AhR-KLF6 NC-XRE-bound complex. Preliminary evidence indicates that TCDD treatment promotes reversible site-specific homocitrullination (carbamoylation of lysine residues) of lysine 34 on histone H1, supporting the hypothesis that CPS1 recruitment to the NC-XRE complex catalyzes a hitherto unknown epigenetic modification responsible for chromatin remodeling and transcriptional regulation. Our evidence also reveals that AhR-dependent transcriptional activation of the peptidylarginine deiminase type-2 (PADI2) gene requires CPS1 recruitment. Since the PADI2 protein modifies arginine 26 on histone H3 to facilitate transcriptional activation, the data are consistent with the AhR catalyzing a distinct epigenetic signature through the direct and indirect action of specific chromatin modifying enzymes. In keeping with our long-term objective to understand the pathophysiology of AhR activity, this proposal will examine three specific aims designed to characterize the epigenetic modifications initiated by the recruitment of CPS1 to chromatin. Specific aim 1 describes a detailed characterization of the CPS1 interaction with the novel AhR-KLF6 complex. Specific Aim 2 will test the hypothesis that AhR-mediated recruitment of CPS1 introduces epigenetic modifications that alter chromatin into an open, transcriptionally permissive conformation. Specific Aim 3 will use ChIP-sequencing and whole transcriptome shotgun sequencing to provide a global genomic assessment of the functional CPS1-dependent AhR-KLF6 binding sites. Identification of this novel AhR complex represents a paradigm shift in our understanding of AhR biology, with discovery of the homocitrulline post-translational modification embodying a significant and innovative insight into epigenetic transcriptional control.

描述（由申请人提供）：芳基碳氢化合物受体 (AhR) 是一种异生物质毒性介质，最被认可的是在暴露于 2,3,7,8-四氯二苯并-对二恶英（TCDD，二恶英）和相关环境污染物后对人类健康产生有害影响。从机制上讲，AhR 被认为是一种配体激活转录因子，与典型的异生素反应元件 (XRE) 结合，并与其异二聚化伙伴，AhR 核易位蛋白 (Arnt) 蛋白结合。然而，在近年来确定的 AhR 靶基因库中，许多缺乏明确定义的 XRE，这凸显了人们日益认识到 AhR 介导的基因表达似乎涉及与涉及 XRE 的充分表征过程不同的其他机制。我们最近发现了一种非共识 XRE (NC-XRE)，它可以招募一种新型的含有 AhR 的蛋白质-DNA 复合物。 DNA 结合和功能研究证实，AhR 的 NC-XRE 结合独立于 Arnt 蛋白，而是与 Kruppel 样因子 6 (KLF6) 肿瘤抑制因子合作发生。基于质谱的蛋白质组学鉴定氨基甲酰磷酸合酶 1 (CPS1) 是 TCDD 诱导的 AhR-KLF6 NC-XRE 结合复合物的附加成分。初步证据表明，TCDD 处理促进组蛋白 H1 上赖氨酸 34 的可逆位点特异性同瓜氨酸化（赖氨酸残基的氨甲酰化），支持 CPS1 招募到 NC-XRE 复合物催化迄今未知的表观遗传修饰（负责染色质重塑和转录调控）的假设。我们的证据还表明，肽基精氨酸脱亚胺酶 2 型 (PADI2) 基因的 AhR 依赖性转录激活需要 CPS1 募集。由于 PADI2 蛋白修饰组蛋白 H3 上的精氨酸 26 以促进转录激活，因此数据与 AhR 通过特定染色质修饰酶的直接和间接作用催化独特的表观遗传特征一致。为了与我们了解 AhR 活性的病理生理学的长期目标保持一致，该提案将研究三个具体目标，旨在表征由 CPS1 招募至染色质而引发的表观遗传修饰。具体目标 1 描述了 CPS1 与新型 AhR-KLF6 复合物相互作用的详细表征。具体目标 2 将检验以下假设：AhR 介导的 CPS1 募集引入了表观遗传修饰，将染色质改变为开放的、转录允许的构象。 Specific Aim 3 将使用 ChIP 测序和全转录组鸟枪测序来提供功能性 CPS1 依赖性 AhR-KLF6 结合位点的全局基因组评估。这种新型 AhR 复合物的鉴定代表了我们对 AhR 生物学理解的范式转变，同型瓜氨酸翻译后修饰的发现体现了对表观遗传转录控制的重要和创新见解。