Mechanisms and biological consequences of the nuclear receptor CAR activation

核受体 CAR 激活的机制和生物学后果

• 批准号: 10004464
• 负责人: MASAHIKO NEGISHI
• 金额: $ 262.09万
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10004464
• 关键词: Affect; Alanine; Androstanes; Animal Model; Anti-inflammatory; Antibodies; Apoptosis; Apoptotic; Binding; Biological; Brain; Cell Death Signaling Process; Cells; Cholestasis; Communication; Cytochromes; Defense Mechanisms; Development; Diabetes Mellitus; Disease; Disease susceptibility; Drug Interactions; Energy Metabolism; Environmental Exposure; Enzymes; Epidermal Growth Factor Receptor; Estrogen Nuclear Receptor; Estrogen Receptors; Excretory function; Exposure to; Fatty Acids; GADD45A gene; Genes; Genetic Transcription; Gluconeogenesis; Glucose; Growth; Health; Hepatic; Hepatocyte; Hepatotoxicity; Human; Immune; Inflammation; Insulin Receptor; Investigation; Knock-in Mouse; Kupffer Cells; Laboratories; Ligands; Lipids; Liver; Liver diseases; Liver neoplasms; MAPK3 gene; MAPK8 gene; Mediating; Microglia; Molecular; Mus; Mutation; Neurodegenerative Disorders; Nuclear; Nuclear Hormone Receptors; Nuclear Receptors; Obesity; Organism; Orphan; Osteomalacia; Pharmaceutical Preparations; Pharmacotherapy; Phenobarbital; Phosphorylation; Physiological; Primary carcinoma of the liver cells; Protein phosphatase; Proto-Oncogene Proteins c-akt; Receptor Activation; Regulation; Retinoids; Role; Serine; Signal Transduction; System; Threonine; Transcriptional Activation; Transducers; Vitamin D3 Receptor; Work; Xenobiotic Metabolism; Xenobiotics; cell growth; cell growth regulation; constitutive active receptor; drug disposition; drug metabolism; environmental chemical; ketogenesis; lipid biosynthesis; liver metabolism; macrophage; member; neutrophil; novel; pregnane X receptor; receptor; receptor function; response; sulfotransferase; transcription factor; tumor

CAR and PXR are members of the NR1I subfamily within the nuclear receptor superfamily. My laboratory was the first to characterize CAR as a drug-activated nuclear receptor, leading world-wide investigations to characterize CAR and PXR and establish their biological roles. Both CAR and PXR regulate not only hepatic drug metabolism and disposition but also energy metabolism such as gluconeogenesis and lipogenesis and ketogenesis. In addition, they regulate cell growth and death signals as well, which includes JNK1, p38MAPK, AKT and GADD45 signals. Consequently, CAR and PXR have now been implicated in various hepatic toxicities and diseases such as liver tumors. It is now known that these receptors act as transcription factors as well as signal transducers in these regulations. However, their molecular mechanisms are not fully understood now. Our work found that CAR is phosphorylated at threonine 38 within the DBD and is inactivated. This phosphorylation is the underlying principle through which CAR functions diverge. For example, phenobarbital stimulates dephosphorization of threonine 38 by protein phosphatase 2A, by binding EGF receptor and/or insulin receptor and repressing their down-stream ERK1/2 signal for CAR activation. In PXR, phosphorylation of serine 350 within the LBD regulates its functions. These phosphorylation motifs within the DBD or LBD are conserved in the majority of nuclear receptors, suggesting that findings with CAR and PXR can be implicated in the investigations of numerous other nuclear receptors Estrogen receptor (ER) conserves threonine 38 of CAR at serine 216 within its DBD. With a phospho-Ser216peptide antibody, it was found that ER is specifically phosphorylated at serine 216 in immune cells such as neutrophils and macrophages in mice. ER KI (Esr1S216A) mice bearing a non-phosphomimetic alanine mutation were generated to investigate the biological roles of this phosphorylation. ER KI mice are fertile but develop obesity. Analysis of brains and microglia and Kupffer cells (resident macrophages in the brain or liver) showed that this phosphorylation confers anti-inflammatory and anti-apoptotic capabilities to ER Phosphorylated ER can be a novel target to investigate various diseases such as obesity and inflammation-related neurodegenerative diseases and their mechanisms. ER KI mice can be an excellent animal model for these investigations. Retinoid related orphan receptor (ROR) conserves this phosphorylation at serine 100 within the DBD. This serine residue becomes phosphorylated in mouse livers in response to phenobarbital treatment, regulating CAR-targeted genes. These nuclear receptors appears to communicate through the conserved phosphorylation, regulating genes and disease developments in response to environmental chemicals and providing an excellent experimental system to investigate the molecular mechanism of this communication. in response to drug treatments and/or physiological/pathophysiological conditions. There are 40 nuclear receptors which conserve this motif with the DBD, enabling us to extend the same line of communication study far beyond these three nuclear receptors.

CAR和PXR是核受体超家族中NR 1 I亚家族的成员。我的实验室是第一个将CAR描述为药物激活的核受体的实验室，领导了世界范围内的研究，以表征CAR和PXR并确定其生物学作用。CAR和PXR不仅调节肝脏药物代谢和处置，而且还调节能量代谢，如脂肪生成、脂肪生成和酮生成。此外，它们还调节细胞生长和死亡信号，包括JNK 1、p38 MAPK、AKT和GADD 45信号。因此，CAR和PXR现在已经涉及各种肝毒性和疾病，如肝肿瘤。现在已知这些受体在这些调节中充当转录因子以及信号转导子。然而，它们的分子机制现在还不完全清楚。 我们的工作发现CAR在DBD内的苏氨酸38处被磷酸化并且被失活。这种磷酸化是CAR功能分化的基本原理。例如，苯巴比妥通过结合EGF受体和/或胰岛素受体并抑制其下游ERK 1/2信号以激活CAR，刺激蛋白磷酸酶2A对苏氨酸38的脱磷酸化。 在PXR中，LBD内丝氨酸350的磷酸化调节其功能。DBD或LBD中的这些磷酸化基序在大多数核受体中是保守的，这表明CAR和PXR的发现可能涉及许多其他核受体的研究 雌激素受体（ER）将CAR的苏氨酸38保留在其DBD内的丝氨酸216处。使用磷酸化-Ser 216肽抗体，发现ER在免疫细胞如小鼠的中性粒细胞和巨噬细胞中的丝氨酸216处特异性磷酸化。ER KI（Esr 1 S216 A）小鼠携带非磷酸模拟丙氨酸突变，以研究这种磷酸化的生物学作用。ER KI小鼠是可生育的，但发展为肥胖。对脑和小胶质细胞和枯否细胞（脑或肝中的常驻巨噬细胞）的分析表明，这种磷酸化赋予ER抗炎和抗凋亡能力。磷酸化的ER可以成为研究各种疾病如肥胖和炎症相关的神经退行性疾病及其机制的新靶点。ER KI小鼠可以成为这些研究的极好动物模型。维甲酸相关孤儿受体（ROR）在DBD内的丝氨酸100处保存这种磷酸化。这种丝氨酸残基在小鼠肝脏中响应于苯巴比妥治疗而磷酸化，调节CAR靶向基因。这些核受体似乎通过保守的磷酸化作用进行通讯，调节基因和疾病的发展，以响应环境化学物质，并提供了一个很好的实验系统，以研究这种通讯的分子机制。响应于药物治疗和/或生理/病理生理条件。有40个核受体与DBD一起保存了这个基序，使我们能够将相同的通信研究范围扩展到远远超出这三个核受体。