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）是异生物质毒性的介体，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传递有害的人类健康影响。从机制上讲，AhR已知作为配体激活的转录因子发挥作用，其结合与其异源二聚化伴侣AhR核转运蛋白（Arnt）蛋白相关的典型异源反应元件（XRE）。然而，在近年来鉴定的AhR靶基因库中，许多缺乏明确定义的XRE，这凸显了人们越来越认识到AhR介导的基因表达似乎涉及与涉及XRE的已充分表征的过程不同的其他机制。我们最近发现了一种非共识XRE（NC-XRE），它招募了一种新的含AhR的蛋白质-DNA复合物。DNA结合和功能研究证实，AhR与NC-XRE的结合不依赖于Arnt蛋白，而是与Kruppel样因子6（KLF 6）肿瘤抑制因子合作发生。基于质谱的蛋白质组学鉴定了氨甲酰磷酸合酶1（CPS 1）作为TCDD诱导的AhR-KLF 6 NC-XRE结合复合物的额外组分。初步证据表明，TCDD治疗促进可逆的位点特异性高瓜氨酸（赖氨酸残基的氨甲酰化）的组蛋白H1上的赖氨酸34，支持的假设，CPS 1招聘NC-XRE复合物催化一个迄今未知的表观遗传修饰负责染色质重塑和转录调控。我们的证据还表明，AhR依赖的肽基精氨酸脱亚胺酶2型（PADI 2）基因的转录激活需要CPS 1的招聘。由于PADI 2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通过特异性染色质修饰酶的直接和间接作用催化不同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，本提案将研究旨在表征由CPS 1向染色质的募集引发的表观遗传修饰的三个具体目标。具体目标1描述了CPS 1与新型AhR-KLF 6复合物相互作用的详细表征。具体目标2将测试的假设，AhR介导的招聘的CPS 1引入表观遗传修饰，改变染色质到一个开放的，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，对功能性CPS 1依赖性AhR-KLF 6结合位点进行全面基因组评估。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，高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。