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）：芳烃受体（AhR）是一种外源毒性介质，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，最被认可的是传递有害的人体健康影响。从机制上讲，已知AhR是一种配体激活的转录因子，它与典型的异种反应元件（XRE）结合，并与其异源二聚化伙伴AhR核转运蛋白（Arnt）结合。然而，在近年来鉴定的AhR靶基因中，许多缺乏明确定义的XRE，这突出了越来越多的人认识到AhR介导的基因表达似乎涉及与XRE相关的明确表征过程不同的其他机制。我们最近发现了一种非共识的XRE (NC-XRE)，它招募了一种新的含有ahr的蛋白质- dna复合物。DNA结合和功能研究证实，NC-XRE与AhR的结合不依赖于Arnt蛋白，而是与kruppel样因子6 （KLF6）肿瘤抑制因子一起发生。基于质谱的蛋白质组学鉴定出氨甲酰磷酸合成酶1 （CPS1）是TCDD诱导的AhR-KLF6 nc - xre结合复合物的附加组分。初步证据表明，TCDD治疗促进组蛋白H1上赖氨酸34的可逆位点特异性同甲基化（赖氨酸残基氨基化），支持CPS1募集到NC-XRE复合体催化一种迄今未知的表观遗传修饰，负责染色质重塑和转录调节。我们的证据还表明，ahr依赖的肽精氨酸脱亚胺酶2型（PADI2）基因的转录激活需要CPS1的募集。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相一致。为了与我们了解AhR活性的病理生理的长期目标保持一致，本提案将研究三个特定的目标，旨在表征CPS1向染色质募集所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特征。特异性目标2将验证ahr介导的CPS1募集引入表观遗传修饰的假设，这些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测序和全转录组霰弹枪测序对cps1依赖性AhR-KLF6结合位点的功能进行全球基因组评估。这种新型AhR复合体的鉴定代表了我们对AhR生物学理解的范式转变，同源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的见解。