Hepatic Aryl Hydrocarbon Receptor Regulation of Obesity: Mechanisms of Action

肝芳基烃受体对肥胖的调节：作用机制

• 批准号: 10701901
• 负责人: Cornelis Johan Elferink
• 金额: $ 35.62万
• 依托单位: UNIVERSITY OF TEXAS MED BR GALVESTON
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-09 至 2027-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10701901
• 关键词: ARNT gene; ARNTL gene; Affect; Architecture; Aromatic Polycyclic Hydrocarbons; Aryl Hydrocarbon Receptor; Binding Sites; Biological; Brain; Brown Fat; Cell Line; Cell Separation; Cells; Chemicals; Chromatin; Circadian Rhythms; Cues; Deposition; Development; Dioxins; Disparate; Electron Transport; Environmental Pollutants; Estrogens; Event; Exhibits; Exposure to; FGF21 gene; Female; Gene Expression; General Population; Genes; Genomics; Glucagon; Glucocorticoids; Gonadal Steroid Hormones; Health; Hepatic; Hepatocyte; High Fat Diet; Homeostasis; Human; Insulin; Intervention; Knockout Mice; Ligands; Liver; Mediating; Metabolic; Metabolic Diseases; Metabolic hormone; Mitochondria; Molecular; Mus; Muscle; Mutate; Obesity; Outcome; Pathway interactions; Periodicity; Phase; Phenotype; Physiological; Physiological Processes; Process; Property; Protein Family; Proteins; Receptor Signaling; Regulation; Reporting; Research; Respiration; Response Elements; Risk; Signal Transduction; Somatotropin; Stat5 protein; Suggestion; Tertiary Protein Structure; Testing; Tetrachlorodibenzodioxin; Therapeutic; Thermogenesis; Thyroid Hormones; Transcriptional Regulation; Transfection; Variant; Xenobiotics; carbohydrate metabolism; circadian; clinical development; combat; conditional knockout; diet-induced obesity; estrogenic; fibroblast growth factor 21; hepatoma cell; improved; in vivo; lipid metabolism; member; novel strategies; pollutant; preservation; prime editing; promoter; receptor expression; reconstitution; response; sexual dimorphism; single-cell RNA sequencing; single-minded protein; success; transcription factor; transcriptome; transcriptome sequencing; transcriptomics

PROJECT SUMMARY/ABSTRACT The Aryl Hydrocarbon Receptor (AhR) is a member of the eukaryotic Per-ARNT-Sim (PAS) domain protein family that regulates adaptive and toxic responses to a variety of chemical pollutants, including polycyclic aromatic hydrocarbons and polychlorinated dioxins, most notably 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). We recently showed that female, but not male liver-specific AhR conditional knockout mice are protected from high fat diet-induced obesity and exhibited improved metabolic homeostasis. The sexually dimorphic phenotype was attributed to increased hepatic expression of fibroblast growth factor 21 (FGF21) in females. FGF21 is a circulating hepatokine that affects carbohydrate and lipid metabolism, and induces thermogenesis in white and brown fat deposits by uncoupling mitochondrial respiration from the electron transport chain. These properties have motivated research into the development of FGF21-based therapeutics to combat metabolic disorders and obesity, but with little success to date. Hence, understanding how AhR activity controls Fgf21 expression may point to novel strategies or targets for the development of clinical interventions. Hepatic Fgf21 expression is also under the control of sex steroids and is subject to circadian rhythms. The latter observation is of note because both the AhR and its partner protein, the AhR Nuclear Translocator (ARNT), belong to the same PAS protein family as several of the circadian rhythm (clock) proteins, including brain and muscle ARNT-like 1 (BMAL1). Hepatic AhR expression exhibits a 24 h periodicity in phase with BMAL1 oscillations, suggestive of co-regulation of these proteins. Moreover, ARNT shares considerable sequence similarity to BMAL1, and an AhR-BMAL1 interaction has been reported, implying that interactions between circadian rhythmicity and AhR signaling are reciprocal and significant. The central premise of this application is, that hepatic Fgf21 expression represents a nexus where AhR signaling and the molecular events underlying sexual dimorphism and circadian rhythmicity, coalesce. We hypothesize that a comprehensive assessment of how these physiologically disparate signaling processes are integrated is required to fully understand AhR regulated Fgf21 expression, and its impact on diet-induced obesity. To test the hypothesis, we propose experimental strategies that preserve the physiological context and genomic milieu. Specific Aim 1 will examine Fgf21 promoter functionality from the standpoint of AhR, ARNT, and BMAL1 activity as a function of circadian rhythmicity. Specific Aim 2 will use single-cell transcriptomics to identify diurnal changes in liver gene expression due to AhR, ARNT, and BMAL1 activity. Specific Aim 3 will interrogate sexually dimorphic Fgf21 expression as a function of estrogenicity. The Specific Aims constitute distinct yet integrated endeavors to mechanistically understand how the AhR regulates Fgf21 expression in the liver, under experimental conditions that preserve the physiological processes responsible for the sexual dimorphism and circadian rhythmicity in the context of a native genomic milieu that retains normal chromatin architecture.

项目摘要/摘要 芳烃受体(AhR)是真核细胞Per-Arnt-Sim(PAS)结构域蛋白的一员 调节对包括多环在内的各种化学污染物的适应性和毒性反应的家族 芳香烃和多氯二恶英，最著名的是2，3，7，8-四氯二苯并-对二恶英(TCDD)。 我们最近表明，雌性而不是雄性肝脏特异性AhR条件性基因敲除小鼠受到保护，不受 高脂饮食导致肥胖，并表现出改善的代谢稳态。性两面性 表型归因于女性肝脏成纤维细胞生长因子21(FGF21)表达增加。 FGF21是一种循环中的肝细胞因子，影响碳水化合物和脂肪代谢，并诱导产热 在白色和棕色脂肪中，通过将线粒体呼吸从电子传输链中分离出来而沉积。 这些特性推动了基于FGF21的疗法的研究，以对抗 代谢紊乱和肥胖，但迄今为止收效甚微。因此，理解AhR活动是如何 对照FGF21的表达可能为临床干预的发展提供新的策略或靶点。 肝脏FGF21的表达也受性类固醇的控制，并受昼夜节律的影响。这个 后一种观察结果值得注意，因为AhR及其伙伴蛋白AhR核转运体 (ARNT)与一些昼夜节律(时钟)蛋白属于相同的PAS蛋白家族，包括 脑和肌肉ARNT样蛋白1(BMAL1)。肝脏AhR的表达具有24小时的周期性，与 BMal1振荡，暗示这些蛋白质的共同调节。此外，Arnt还分享了相当大的份额 序列与BMAL1相似，并且已经报道了AhR-BMAL1相互作用，这意味着相互作用 昼夜节律性和AhR信号之间是相互作用和显著的。这一点的中心前提是 应用是，肝脏FGF21的表达代表了AhR信号和分子事件的联系 潜在的性二型性和昼夜节律性，结合在一起。我们假设一个全面的 需要评估这些生理上不同的信号过程是如何整合的，以充分 了解AhR调节FGF21的表达，以及它对饮食诱导的肥胖的影响。为了检验这一假设， 我们提出了保护生理环境和基因组环境的实验策略。具体目标1 我将从AhR、Arnt和BMAL1活性的角度来研究FGF21启动子的功能 昼夜节律性的。《特定目标2》将使用单细胞转录组学技术来识别肝脏的昼夜变化 AhR、Arnt和BMAL1活性导致的基因表达。《特定目标3》将审讯性二相者 FGF21的表达与雌激素活性有关。具体的目标构成了不同但又综合的努力 为了从机制上了解AhR如何调节肝脏FGF21的表达，在实验 维持导致性二型性和昼夜节律的生理过程的条件 在保持正常染色质结构的天然基因组环境中的节律性。