Metabolic Reprogramming by Protease-activated Receptor 2

蛋白酶激活受体 2 的代谢重编程

• 批准号: 10569593
• 负责人: ATHAN KULIOPULOS
• 金额: $ 59.13万
• 依托单位: TUFTS MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-15 至 2024-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10569593
• 关键词: ADD-1 protein; Adipose tissue; Affect; American; Applications Grants; Biochemical; Body Weight decreased; Carbon; Cell membrane; Cholesterol; Cholesterol Homeostasis; Cirrhosis; Clinical Data; Coagulation Process; Consumption; Coupled; Cross-Sectional Studies; Data; Dyslipidemias; Etiology; Extracellular Domain; Fatty Liver; Fatty acid glycerol esters; Fibrosis; G-Protein-Coupled Receptors; GLUT-2 protein; GTP-Binding Proteins; Glucose; Glucose Transporter; Glycogen; Goals; Hepatic; Hepatocyte; Homeostasis; Human; Hypertriglyceridemia; In Vitro; Inflammation; Insulin; Insulin Resistance; Intestines; Knock-out; Knockout Mice; Kupffer Cells; LDL Cholesterol Lipoproteins; Ligands; Link; Liver; Liver Fibrosis; Liver diseases; MAP Kinase Gene; Macrophage; Mediating; Membrane; Metabolic; Metabolic Pathway; Metabolism; Modeling; Mus; N-terminal; Names; Non-Insulin-Dependent Diabetes Mellitus; Obese Mice; Obesity; Obesity Epidemic; PAR-1 Receptor; PAR-2 Receptor; Pathogenesis; Pathology; Pathway interactions; Patients; Peptide Hydrolases; Phenotype; Pilot Projects; Plasma; Primary carcinoma of the liver cells; Proteinase-Activated Receptors; Proto-Oncogene Proteins c-akt; Ramp; Role; SRE-2 binding protein; Signal Pathway; Signal Transduction; Site; Specimen; Surface; Technology; Testing; Therapeutic Intervention; Thinness; Tissues; Trypsin; United States National Institutes of Health; Validation; Visceral; antagonist; beta-arrestin; blood glucose regulation; cell type; cohort; diabetic; diet-induced obesity; effective therapy; fatty liver disease; glycogenesis; hypercholesterolemia; in vivo; lipid metabolism; liver biopsy; liver metabolism; liver transplantation; mortality; mouse model; non-alcoholic fatty liver disease; nonalcoholic steatohepatitis; novel; protein expression; receptor; release of sequestered calcium ion into cytoplasm; resistance mechanism; reverse cholesterol transport; sugar

Excessive sugar and fat consumption can lead to a range of metabolic abnormalities including non-alcoholic fatty liver disease (NAFLD), hypercholesterolemia, dyslipidemia, obesity, and insulin resistance. Emerging evidence points to a new mechanism linking carbon metabolism and fatty liver disease to the G protein-coupled Protease Activated Receptor-2 (PAR2), a receptor previously known to be involved in inflammation. To provide key support for the potential importance of hepatic PAR2 in humans, in a cross-sectional study of liver specimens and clinical data from 108 NAFLD patients and controls, we found that PAR2 protein expression in hepatocytes was low in control livers and progressively increased in patients with mild NAFLD fibrosis and in NAFLD with higher stages of fibrosis. The high PAR2-expressing NAFLD patient cohort had significantly elevated plasma LDL cholesterol as compared to the low PAR2-expressing cohort. However, a definitive role for PAR2 in metabolism, cholesterol homeostasis, and liver pathology remains unknown. The overarching goal of this grant proposal is to examine the role of PAR2 signaling in the etiology and pathogenesis of fatty liver disease to test our central hypothesis that hepatic PAR2 is a novel contributor of hypertriglyceridemia, obesity, and insulin resistance. PAR2 is expressed by many tissues and cell types and a conventional mouse whole-body knockout (KO) has been used to date. Therefore, it is unclear how much of the KO phenotype or effects of PAR2 inhibition on steatosis, lipid metabolism, and weight loss is mediated only at the level of the hepatocyte and how much is due to loss of PAR2 at other sites of expression. We will use our new hepatocyte-specific PAR2-KO, PAR2∆Hep mice to define and validate the specific involvement of liver PAR2 in these profound metabolic effects in aims 1-3. It is unclear how PAR2 promotes insulin resistance in diet-induced obesity models. Aim 2 will explore a novel mechanism whereby PAR2 activates a Gq-PLC pathway to stimulate calcium flux and CaMKK2 to interfere in insulin activation of AKT-glucose signaling. To explain our preliminary data that global PAR2-deficiency lowers basal plasma glucose, but increases liver glucose and glycogen in both lean and obese mouse models, Aim 3 will test the hypothesis that hepatocyte PAR2 suppresses the major liver glucose transporter GLUT2 through a mechanism potentially involving Gq-MAPK-FoxA3. Aims 1-3 will utilize our pepducin technology developed to allosterically target G-protein coupled receptors on the inside surface of the plasma membrane to help delineate specific PAR2-effector signaling pathways in aberrant liver metabolism and insulin resistance in vitro and in vivo.

过多的糖和脂肪摄入会导致一系列代谢异常，包括非酒精性脂肪肝病（NAFLD）、高胆固醇血症、血脂异常、肥胖和胰岛素抵抗。新出现的证据表明，碳代谢和脂肪肝疾病与 G 蛋白偶联蛋白酶激活受体 2 (PAR2) 之间存在联系，而 PAR2 是一种先前已知与炎症有关的受体。为了为肝 PAR2 对人类的潜在重要性提供关键支持，在对 108 名 NAFLD 患者和对照者的肝脏标本和临床数据进行的横断面研究中，我们发现对照肝脏中肝细胞中 PAR2 蛋白的表达较低，而在轻度 NAFLD 纤维化患者和纤维化较高阶段的 NAFLD 中逐渐增加。与低 PAR2 表达队列相比，高 PAR2 表达 NAFLD 患者队列的血浆 LDL 胆固醇显着升高。然而，PAR2 在代谢、胆固醇稳态和肝脏病理学中的明确作用仍然未知。这项拨款提案的总体目标是研究 PAR2 信号传导在脂肪肝疾病的病因和发病机制中的作用，以检验我们的中心假设，即肝脏 PAR2 是高甘油三酯血症、肥胖和胰岛素抵抗的新贡献者。 PAR2 在许多组织和细胞类型中表达，迄今为止已使用传统的小鼠全身敲除 (KO) 方法。因此，尚不清楚 PAR2 的 KO 表型或抑制对脂肪变性、脂质代谢和体重减轻的影响有多少仅在肝细胞水平介导，有多少是由于其他表达位点 PAR2 的缺失所致。我们将使用新的肝细胞特异性 PAR2-KO、PAR2ΔHep 小鼠来定义和验证肝脏 PAR2 在目标 1-3 中这些深远代谢效应中的具体参与。目前尚不清楚 PAR2 如何在饮食诱发的肥胖模型中促进胰岛素抵抗。目标 2 将探索一种新机制，通过 PAR2 激活 Gq-PLC 通路来刺激钙流，并通过 CaMKK2 来干扰 AKT-葡萄糖信号传导的胰岛素激活。为了解释我们的初步数据，即在瘦小鼠和肥胖小鼠模型中，整体 PAR2 缺乏会降低基础血浆葡萄糖，但会增加肝脏葡萄糖和糖原，Aim 3 将测试肝细胞 PAR2 通过可能涉及 Gq-MAPK-FoxA3 的机制抑制主要肝脏葡萄糖转运蛋白 GLUT2 的假设。目标 1-3 将利用我们开发的 pepducin 技术来变构靶向质膜内表面上的 G 蛋白偶联受体，以帮助描绘异常肝脏代谢和体外和体内胰岛素抵抗中的特定 PAR2 效应器信号传导途径。