Dopamine and Angiotensin Receptor Interactions in Genetic Hypertension

高血压和盐敏感性是人类发病率和死亡率的主要因素。然而，对病因学或个人遗传学，生化调节和环境影响之间的联系的理解进展缓慢。我们的工作表明，两个肾脏调节途径，反调节钠在肾小管重吸收，即多巴胺（抑制）和血管紧张素（刺激），是高血压和盐敏感性的病因学的中心。我们已经报道，增加G蛋白偶联受体激酶4型（GRK 4）的活性，因为激活的变体，直接导致多巴胺受体的失调，以及血管紧张素受体，在肾近端小管细胞（RPTC）从人类原发性高血压。在动物模型中，过表达GRK 4 y野生型基因的转基因小鼠血压正常，而GRK 4 Y142 V转基因小鼠血压高且盐敏感，而GRK 4 y 486 V转基因小鼠盐敏感。该项目的总体目标是研究肾小管细胞中多巴胺和血管紧张素受体之间的反式调节的新机制，包括蛋白质降解。这些新机制将在新的小鼠模型和人体中进行检查，其中体内肾功能研究将与从同一个体获得的新鲜排泄的肾小管细胞中的研究相关。在管理、分析和动物核心实验室的支持下，项目1将检验以下假设：多巴胺能受体和血管紧张素受体与几种关键调控蛋白（DiR、D5 R、ATiR和GRK 4）之间的新型时空相互作用发生在脂筏中，并受人RPTC中小窝蛋白-1和GRK 4之间相互作用的调控。我们还推测，小窝蛋白-1对DiR功能的促进作用受到GRK 4基因变异的损害。项目2将检验以下假设：ATiR介导的抗白尿作用受到DiR和D3 RS的反对，在正常人类受试者中协同作用，并且这种保护机制在原发性高血压患者中缺乏。对来自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来自获自同一受试者的尿衍生细胞的单个肾细胞生理反应相关。这将使我们能够将同一受试者的肾功能反应与肾细胞研究相关联。项目3将检验以下假设：伴随D3 R表达或功能降低（由GRK 4基因变体引起）而发生的高血压是由于NHE 3、NCC和ENaC的活性和表达增加;它们的表达增加是由于它们的去泛素化（也称为去泛素化）导致的降解减少引起的。去泛素化）。这个基本的和翻译补助金申请将描绘多巴胺能和肾素-血管紧张素系统之间的相互作用的新见解，并提供新的见解，将导致新的治疗方法。

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.