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.

过量的糖和脂肪摄入会导致一系列代谢异常，包括非酒精性脂肪性肝病(NAFLD)、高胆固醇血症、血脂异常、肥胖和胰岛素抵抗。新的证据指出了一种新的机制，将碳代谢和脂肪肝与G蛋白偶联蛋白酶激活的受体-2(PAR2)联系起来，这是一种先前已知参与炎症的受体。为了对人类肝脏PAR2的潜在重要性提供关键支持，我们对108例NAFLD患者和对照组的肝脏标本和临床数据进行了横断面研究，发现在对照肝脏中PAR2蛋白的表达水平较低，而在轻度NAFLD纤维化患者和纤维化分期较高的NAFLD患者中，PAR2蛋白的表达逐渐增加。与PAR2低表达组相比，高PAR2表达的NAFLD患者队列显著升高了血浆低密度脂蛋白胆固醇。然而，PAR2在新陈代谢、胆固醇稳态和肝脏病理中的确切作用仍不清楚。这项拨款提案的主要目标是研究PAR2信号在脂肪肝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都有表达，到目前为止，已经使用了传统的小鼠全身基因敲除(KO)。因此，目前尚不清楚有多少KO表型或抑制PAR2对脂肪变性、脂代谢和体重减轻的影响仅在肝细胞水平上介导，以及有多少是由于其他表达部位的PAR2丢失所致。我们将使用我们的新的肝细胞特异性PAR2-KO，PAR2HEP小鼠来定义和验证肝脏PAR2在AIMS 1-3的这些深刻的代谢效应中的特定参与。目前尚不清楚PAR2是如何在饮食诱导的肥胖模型中促进胰岛素抵抗的。目的2探索一种新的机制，即PAR2激活GQ-PLC通路刺激钙离子通量，而CAMKK2干扰胰岛素激活AKT-葡萄糖信号通路。为了解释我们的初步数据，在瘦小鼠和肥胖小鼠模型中，全球PAR2缺乏降低基础血糖，但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体GLUT2的假设。AIMS 1-3将利用我们开发的针对质膜内表面G蛋白偶联受体的变构蛋白技术，在体外和体内帮助描绘肝脏异常代谢和胰岛素抵抗中特定的PAR2效应信号通路。