Regulation of Bile Acid Synthesis by Nuclear receptors

核受体对胆汁酸合成的调节

• 批准号: 7802989
• 负责人: JOHN Y. L. CHIANG
• 金额: $ 30.2万
• 依托单位: NORTHEAST OHIO MEDICAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7802989
• 关键词: ADD-1 protein; Abbreviations; Acute-Phase Reaction; Animal Model; Atherosclerosis; Bile Acid Biosynthesis Pathway; Bile Acids; Binding; Biological Assay; CYP7A1 gene; CYP8B1 gene; Cardiovascular Diseases; Catabolism; Cholelithiasis; Cholesterol; Cholic Acids; Chromatin; Chromatin Structure; Complex; Diabetes Mellitus; Dyslipidemias; Energy Metabolism; Enzymes; Gene Expression Regulation; Genes; Genetic; Genetic Transcription; Glucagon; Hepatocyte; Hepatocyte Growth Factor; Histone Deacetylase; Histones; Homeostasis; Human; Inflammation; Injury; Insulin; Insulin Signaling Pathway; Lipids; Liver; Liver diseases; MAP Kinase Signaling Pathways; MAPK Signaling Pathway Pathway; Metabolic Diseases; Metabolism; Mitogen-Activated Protein Kinases; Mixed Function Oxygenases; Modeling; Molecular; Mus; Non-Insulin-Dependent Diabetes Mellitus; Nuclear Orphan Receptor; Nuclear Receptors; Nutrient; Obesity; Orthologous Gene; PI3K/AKT; Pathogenesis; Pathway interactions; Physiological; Proteins; Rattus; Receptor Signaling; Regulation; Repression; Research; Research Personnel; Research Project Grants; Response Elements; Rodent; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Small Interfering RNA; Steroids; Sterols; Stimulus; Therapeutic Agents; Time; Two-Hybrid System Techniques; Vitamins; Xenobiotics; absorption; blood glucose regulation; chromatin immunoprecipitation; cytokine; forkhead protein; formycin triphosphate; glucose metabolism; human HDAC1 protein; insulin signaling; mouse model; protein protein interaction; species difference

DESCRIPTION (provided by applicant): Bile acids are physiological agents that facilitate absorption, transport and disposal of steroids, nutrients, metabolites and xenobiotics. Bile acids also are signaling molecules that activate nuclear receptors to regulate lipid and glucose homeostasis. Dysregulation of bile acid metabolism causes dyslipidemia, gallstone, liver, and cardiovascular diseases, and diabetes. Bile acids, insulin and cytokines inhibit CYP7A1, the first and rate-limiting enzyme of the bile acid synthesis pathway in the liver. The expression of CYP7A1 is mainly regulated at gene transcriptional level. Bile acid activates the FXR/SHP pathway, and several cell signaling pathways to inhibit CYP7A1 gene transcription. The mechanism of nuclear receptors and signaling pathways regulating CYP7A1 gene transcription remain to be elucidated. Most studies on CYP7A1 gene regulation have been performed in animal models. We have observed marked differences in regulation of the human and rodent CYP7A1 genes. Our central hypothesis is that as an acute phase response to inflammation and liver injury, bile acids and other stimuli activate the PI3K/AKT and MAP kinase signaling pathways, and signal crosstalk regulates nuclear receptors and co-regulators to remodel CYP7A1 and CYP8B1 chromatins. The specific aim 1 will study nuclear receptor and co-regulator modulation of CYP7A1 and CYP8B1 chromatin. The roles of HNF4? and FTP, and their co-regulators Prox1, PGC-1?, histone deacetylase (HDAC) and silencing information regulator (SIRT1) will be studied. HepG2 and primary human hepatocytes will be used for chromatin immunoprecipitation (ChIP), co-IP and mammalian two-hybrid assays to study DNA-protein and protein-protein interaction. Aim 2 will study the crosstalk of bile acid, cytokine, insulin, glucagon and PMA signaling pathways in regulating CYP7A1/CYP8B1 gene transcription. Real time PCR, siRNA, and microarrays will be used to identify genes involved in signaling crosstalk. Am 3 will study hepatocyte growth factor (HGF) regulation of CYP7A1 gene transcription to identify signaling pathway and crosstalk with insulin signaling. The objective of this research is to elucidate the molecular mechanism of nuclear receptor and signaling pathway regulation of bile acid synthesis. This study could contribute to understanding the mechanisms of metabolic diseases caused by dysregulation of bile acid synthesis and develop therapeutic agents to treat dyslipidemia, liver diseases, obesity and type II diabetes.

描述（由申请人提供）：胆汁酸是促进类固醇、营养物、代谢物和异种生物的吸收、运输和处置的生理制剂。胆汁酸也是激活核受体调节脂质和葡萄糖稳态的信号分子。胆汁酸代谢失调导致血脂异常、胆结石、肝脏、心血管疾病和糖尿病。胆汁酸、胰岛素和细胞因子抑制肝脏中胆汁酸合成途径的第一酶和限速酶CYP7A1。CYP7A1的表达主要在基因转录水平受到调控。胆汁酸激活FXR/SHP通路和多种细胞信号通路，抑制CYP7A1基因转录。核受体调控CYP7A1基因转录的机制和信号通路尚不清楚。大多数关于CYP7A1基因调控的研究都是在动物模型中进行的。我们已经观察到人类和啮齿动物CYP7A1基因的调控有显著差异。我们的中心假设是，作为炎症和肝损伤的急性期反应，胆胆酸和其他刺激激活PI3K/AKT和MAP激酶信号通路，信号串音调节核受体和共调节因子重塑CYP7A1和CYP8B1染色质。具体目的1将研究CYP7A1和CYP8B1染色质的核受体和共调节调节。HNF4的作用？和FTP，以及它们的共同调节因子Prox1， PGC-1？将研究组蛋白去乙酰化酶（HDAC）和沉默信息调节因子（SIRT1）。HepG2和原代人肝细胞将用于染色质免疫沉淀（ChIP）、co-IP和哺乳动物双杂交实验，以研究dna -蛋白和蛋白-蛋白相互作用。Aim 2将研究胆酸、细胞因子、胰岛素、胰高血糖素和PMA信号通路在调节CYP7A1/CYP8B1基因转录中的串扰。实时PCR、siRNA和微阵列将用于识别参与信号串扰的基因。am3将研究肝细胞生长因子（HGF）调控CYP7A1基因转录，识别信号通路并与胰岛素信号串扰。本研究旨在阐明胆汁酸合成过程中核受体的分子机制及信号通路调控。该研究有助于了解胆汁酸合成失调引起的代谢性疾病的机制，并有助于开发治疗血脂异常、肝脏疾病、肥胖和II型糖尿病的药物。