Cell Surface Plasminogen Activation and Hypertension

细胞表面纤溶酶原激活与高血压

• 批准号: 8669725
• 负责人: ROBERT J PARMER
• 金额: --
• 依托单位: VA SAN DIEGO HEALTHCARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2017-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8669725
• 关键词: Ablation; Adult; Affect; Aldosterone; Binding Sites; Blood Pressure; Cause of Death; Cell surface; Cells; Chronic Kidney Failure; Cirrhosis; Congestive Heart Failure; Coronary Arteriosclerosis; Data; Development; Disease; Distal; Edema; Employee Strikes; Environmental Risk Factor; Enzyme Precursors; Epigenetic Process; Epithelial; Epithelial Cells; Equilibrium; Essential Hypertension; Extracellular Fluid; Frequencies; Functional disorder; Genetic; Healthcare Systems; Homeostasis; Hormonal; Hormones; Hypertension; Image; In Vitro; Kidney; Lead; Mediating; Mediator of activation protein; Metabolic syndrome; Mineralocorticoids; Modeling; Mus; Nephrons; Nephrotic Syndrome; Obesity; Pathway interactions; Peptide Hydrolases; Physiology; Plasmin; Plasminogen; Play; Population; Process; Proteins; Proteolytic Processing; Proteomics; Reagent; Regulation; Risk Factors; Role; Serine Protease; Site; Sodium; Sodium Channel; Stroke; Syndrome; System; Testing; Transcriptional Activation; Urokinase; Urokinase Plasminogen Activator Receptor; Vasopressins; Work; base; blood pressure regulation; disability; epithelial Na+ channel; improved; in vivo; mouse model; new therapeutic target; novel; plasminogen receptor; protein expression; public health relevance; response; salt sensitive hypertension; trafficking

DESCRIPTION (provided by applicant): Hypertension affects more than 25% of the adult population and is a major risk factor for coronary artery disease, stroke, and chronic kidney disease. Previous studies have revealed that interactions between genetic and environmental factors play a critical role in the development of elevated blood pressure, and a large body of evidence implicates the inappropriate retention of sodium by the kidney in the pathophysiology of hypertension. However, the regulatory steps that govern and modulate sodium reabsorption by the kidney are not fully understood. Within the kidney, the epithelial sodium channel (ENaC) is expressed in the aldosterone- responsive distal portions of the nephron, where it serves as the rate-limiting step in the reabsorption of filtered sodium, hence playing a crucial role in the regulation of sodium balance, extracellular fluid volume, and blood pressure. Results have emerged that document a critical role for serine protease-mediated cleavage of ENaC subunits in ENaC activation, and recent studies suggest that plasmin is a key protease in this process. This proposal is based on our proteomics-based discovery of a new protein, the plasminogen receptor, Plg-RKT, which markedly enhances the activation of the zymogen plasminogen to plasmin, as well as concentrates and localizes the proteolytic activity of plasmin at specific site on the cell surface. We have observed prominent (indeed striking) expression of Plg-RKT in renal epithelial cells, particularly in the distal portions of the nephron, and in confocal imaging studies have noted prominent co-localization of Plg-RKT with ENaC, and with the urokinase receptor (uPAR), another key component of the plasminogen activation pathway. Our preliminary data suggest the presence of a local, renal distal nephron plasminogen activation system, which includes all major components of the plasminogen activation pathway, including plasminogen activator [urokinase (uPA)], the urokinase receptor (uPAR), the zymogen plasminogen, and of high importance, the specific plasminogen receptor Plg-RKT, for local amplication and concentration of cell surface plasminogen activation. In other recent results, we have demonstrated a key role for Plg-RKT and the local plasminogen activation system in ENaC proteolytic processing, and have shown that genetic ablation of various components of the plasminogen activation system (including plasminogen, urokinase, and Plg-RKT) results in substantial alterations in sodium homeostasis in vivo. The overall objective of this proposal is to test the hypothesis that Plg-RKT plays a crucial role in ENaC activation and sodium retention in salt-sensitive hypertension. We have generated a novel Plg- RKT deficient mouse model and will use this to comprehensively investigate the role of Plg-RKT in sodium retention in vivo in models of salt-sensitive hypertension, including models of mineralocorticoid excess, obesity/metabolic syndrome, and Liddle's syndrome. In addition, we will examine the regulation of Plg-RKT expression (including transcriptional activation and protein expression) and trafficking in renal epithelial cells, and determine the extent to which Plg-RKT expression is regulated by hormonal agents that are active in the distal nephron and that function to regulate sodium balance, including aldosterone and vasopressin. Thus, we will evaluate the role of Plg-RKT as a key mediator of hormone-stimulated sodium reabsorption in the distal nephron. This project seeks to provide new information on sodium reabsorption by the kidney in hypertension, which will lead to improved management and novel therapeutic targets for this highly prevalent disorder, as well as for other diseases characterized by increased sodium reabsorption.

描述（由申请人提供）： 高血压影响了成年人口的25％以上，是冠状动脉疾病，中风和慢性肾脏疾病的主要危险因素。先前的研究表明，遗传因素与环境因素之间的相互作用在升高血压的发展中起着至关重要的作用，大量证据表明，肾脏在高血压病理生理学中对钠的保留不当。但是，尚未完全理解肾脏的控制和调节钠重吸收的调节步骤。在肾脏中，上皮钠通道（ENAC）在静脉的醛固酮反应性远端中表达，在该醛固酮反应性的远端，它是过滤钠的重吸收的限速步骤，因此在调节钠平衡，外细胞液体和血压的调节中起着至关重要的作用。结果表明，记录了丝氨酸蛋白酶介导的ENAC亚基在ENAC激活中的裂解至关重要的作用，而最近的研究表明，在此过程中，纤溶酶是关键蛋白酶。该提案基于我们基于蛋白质组学的发现，对新蛋白质纤溶酶原受体PLG-RKT的发现显着增强了酶原纤溶酶原成纤溶酶的激活，并浓缩并定位在细胞表面特定部位的纤溶酶的蛋白水解活性。我们已经观察到PLG-RKT在肾上皮细胞中的显着（确实是引人注目的）表达 研究已经注意到，PLG-RKT与ENAC以及尿激酶受体（UPAR）的显着共定位，这是纤溶酶原活化途径的另一个关键组成部分。 Our preliminary data suggest the presence of a local, renal distal nephron plasminogen activation system, which includes all major components of the plasminogen activation pathway, including plasminogen activator [urokinase (uPA)], the urokinase receptor (uPAR), the zymogen plasminogen, and of high importance, the specific plasminogen receptor Plg-RKT, for local amplication and concentration of cell surface纤溶酶原活化。在最近的其他结果中，我们在ENAC蛋白水解加工中证明了PLG-RKT和局部纤溶酶原激活系统的关键作用，并表明纤溶酶原激活系统各种成分的遗传消融（包括纤溶酶原，尿激酶和PLG-RKT）在Sodium sodium Bissostasis sodium Bissostasis Invivo中的实质性层次危害的结果。该提议的总体目的是 测试PLG-RKT在盐敏感性高血压中的ENAC激活和钠保留率中起着至关重要的作用的假设。我们已经产生了一种新型的PLG-RKT缺陷小鼠模型，并将使用它来全面研究PLG-RKT在体内钠在体内的作用，包括盐敏感的高血压模型，包括矿物皮质激素过量，肥胖/代谢综合征和Liddle综合征的模型。此外，我们将检查PLG-RKT表达（包括转录激活和蛋白质表达）和肾上皮细胞中的运输调节，并确定PLG-RKT表达在多大程度上受激素的调节的程度，这些激素剂受到远端肾脏的活性和该功能的活性，该功能调节了钠平衡，包括雌激素和vasopressins。因此，我们将评估PLG-RKT作为激素刺激的钠在远端肾单位中重吸收的关键介体的作用。该项目旨在提供有关肾脏在高血压中的钠重吸收的新信息，这将导致这种高度普遍的疾病的管理和新颖的治疗靶标，以及其他以钠升高的特征的其他疾病。