Dopamine and Angiotensin Receptor Interactions in Genetic Hypertension

遗传性高血压中多巴胺和血管紧张素受体的相互作用

• 批准号: 7938789
• 负责人: Robin A Felder
• 金额: $ 215.02万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7938789
• 关键词: Dopamine; Angiotensin; Receptor; Interactions; Genetic

Hypertension and salt sensitivity are major contributors to human morbidity and mortality. However, there has been slow progress in the understanding of the etiology or the link between personal genetics, biochemical regulation, and environmental influences. Our work has shown that two renal regulatory pathways that counter-regulate sodium reabsorption in the renal tubule, namely, dopamine (inhibitory) and angiotensin (stimulatory), are central in the etiology of hypertension and salt sensitivity. We have reported that increased activity of G protein-coupled receptor kinase type 4 (GRK4), because of activating variants, directly causes the dysregulation of dopamine receptors, as well as the angiotensin receptors, in renal proximal tubule cells (RPTCs) from humans with essential hypertension. In animal models, transgenic mice over expressing GRK4y wild-type gene are normotensive, while GRK4Y 142V transgenic mice are hypertensive and salt-sensitive, while GRK4y486V transgenic mice are salt-sensitive. The overall objective of this program project is the study of novel mechanisms of trans-regulation, including protein degradation, between the dopamine and angiotensin receptors in renal tubule cells. These novel mechanisms will be examined in novel mouse models, and in humans in whom in vivo renal functional studies will be correlated with studies in freshly voided renal tubule cells obtained from the same individual. Supported by administrative, analytical, and animal core laboratories, Project 1 will test the hypothesis that novel spatiotemporal interactions between and among dopaminergic and angiotensin receptors and several key regulatory proteins (DiR, D5R, ATiR, and GRK4) occur in lipid rafts and are regulated by the interaction between caveolin-1 and GRK4 in human RPTCs. We also hypothesize that the facilitatory effect of caveolin-1 on DiR function is impaired by GRK4 gene variants. Project 2 will test the hypothesis that ATiR-mediated antinatriuresis is opposed by DiRs and D3RS, acting in concert in normal human subjects, and that this protective mechanism is deficient in patients with essential hypertension. The physiologic responses to selective dopaminergic and angiotensin system stimulation from a specific subject will be correlated with single renal cell physiological responses from the urine-derived cells obtained from the same subject. This will enable us to correlate renal functional responses with renal cellular studies in the same subject. Project 3 will test the hypothesis that the hypertension that occurs with decreased D3R expression or function (caused by GRK4 gene variants) is due to increased activity and expression of NHE3, NCC, and ENaC; their increased expression is caused by decreased degradation due to their deubiquitination (a.k.a. deubiquitinylation) by USP48. This basic and translational grant application will delineate new insights into the interactions between the dopaminergic and renin-angiotensin systems and provide new insight that will lead to new therapeutic approaches.

高血压和盐敏感性是人类发病率和死亡率的主要因素。但是，对病因的理解或个人遗传学，生化调节和环境影响之间的联系取得了缓慢的进步。我们的工作表明，在肾小管中反调节钠的重吸收的两种肾脏调节途径，即多巴胺（抑制性）和血管紧张素（刺激性）在高血压和盐敏感性的病因中是核心。我们已经报道说，G蛋白偶联受体激酶4型（GRK4）的活性增加，由于激活变异，直接引起肾邻近小管细胞（RPTC）在人类中的肾邻近小管细胞（RPTC）中的血管紧张素受体的失调以及血管紧张素受体。在动物模型中，以表达GRK4Y野生型基因的转基因小鼠是正常的，而GRK4Y 142V转基因小鼠是高血压和盐敏感的，而GRK4Y486V转基因小鼠对盐敏感。该计划项目的总体目的是研究肾小管细胞中多巴胺和血管紧张素受体之间反式调节的新机制，包括蛋白质降解。这些新型机制将在新型的小鼠模型中进行检查，在人类中，体内肾功能研究将与从同一个体获得的新鲜无效的肾小管细胞中的研究相关。在行政，分析和动物核心实验室的支持下，项目1将检验以下假设：多巴胺能和血管紧张素受体之间和血管紧张素受体之间的新型时空相互作用以及几种关键的调节蛋白（DIR，D5R，ATIR和GRK4）在脂质柱中发生在脂肪中，并在cavewors-raft中发生在人类和Grkk4之间的相互作用。我们还假设Caveolin-1对DIR功能的促进作用受到GRK4基因变体的损害。项目2将检验以下假设：ATIR介导的抗钠尿液与DIRS和D3RS相反，在正常的人类受试者中起作用，并且这种保护机制在基本高血压患者中不足。对特定受试者的选择性多巴胺能和血管紧张素系统刺激的生理反应将与从同一受试者获得的尿液衍生细胞的单个肾细胞生理反应相关。这将使我们能够将肾功能反应与同一受试者的肾细胞研究相关联。项目3将检验以下假设：D3R表达或功能降低（由GRK4基因变体引起）发生的高血压是由于NHE3，NCC和ENAC的活性和表达增加所致。它们的表达增加是由于它们的去泛素化（又称去泛素化）引起的降解引起的。这个基本和转化的赠款应用程序将描述对多巴胺能和肾素 - 血管紧张素系统之间相互作用的新见解，并提供新的见解，从而导致新的治疗方法。