Regulation of ENaC in salt-sensitive hypertension via inflammation-induced ROS pr

描述(申请人提供)：上皮钠通道(ENaC)是醛固酮敏感型远端肾单位(ASDN)钠稳态的关键调节器，控制身体液体容量和血压。ENaC的功能障碍和异常调节导致一系列与钠处理异常相关的疾病，从低血压到高血压伴钠滞留和消耗，再到呼吸综合征。这些研究集中在ENaC在正常和病理生理中的作用，可以转化为临床实践，实现NHLBI改善患者健康的使命。钠负荷与血压正常和高血压患者的血压升高有关。本研究中使用的Dahl盐敏感型(SS)大鼠在高盐饮食下会出现严重的高血压。我们的初步数据表明，ENaC介导的ASDN中的Na+重吸收有助于SS大鼠品系的盐敏感型高血压，我在此假设过多的H_2O_2产生介导了这一效应。与饲喂低盐饲料的SS大鼠和饲喂高盐饲料的配偶SS-130亿只大鼠相比，饲喂高盐饲料的SS大鼠ENAC亚单位的表达不适当地上调。ENaC抑制剂苯扎米可减轻SS大鼠的血压升高。肾脏T淋巴细胞的浸润增加了氧化应激，参与了SS大鼠盐敏感型高血压的发生发展。此外，我们的初步结果表明，过氧化氢的产生上调了ENaC的活性。我推测ENaC介导的ASDN中的Na+重吸收在盐敏感型高血压的发生中起作用，免疫细胞的激活增加了H_2O_2的产生，而H_2O_2相应地激活了ENaC，参与了盐敏感型高血压的发展。进一步推测，H_2O_2的产生增加会导致肌动蛋白细胞骨架的改变，而皮质蛋白和MIM蛋白参与了这一机制。基于我们的初步数据和以前发表的研究结果，这项提议的具体目标是确定渗透是否增加了肾皮质中H_2O_2的产生，从而上调了ENaC介导的ASDN中的钠重吸收，并确定了H_2O_2介导的ENaC活性变化的确切机制。在这项提案中，将使用多种方法的组合来提供关于ENaC如何被过氧化氢调节以及这一途径的变化如何导致盐诱导的高血压的机械性见解。这些研究将针对两个特定的目标：1)确定SS大鼠T细胞的渗透和连续的H_2O_2产生是否增加ENaC活性；2)确定H_2O_2调节ENaC活性的细胞和分子机制。我的长期职业目标是继续我在生物医学研究领域的学术生涯，在细胞、器官和系统水平上研究参与调节盐分和水平衡的离子通道。K99/R00资助金符合我的职业目标，提供了帮助我过渡到 拥有美国国立卫生研究院或其他独立研究基金的稳定独立研究职位。

DESCRIPTION (provided by applicant): Epithelial sodium channel (ENaC) is a key regulator of sodium homeostasis in aldosterone-sensitive distal nephron (ASDN) controlling body liquid volume and blood pressure. Dysfunction and aberrant regulation of ENaC lead to a spectrum of diseases associated with abnormal sodium handling, ranging from hypo- to hypertension with sodium retention and wasting, respectively, to respiratory syndromes. The studies focused on the role of ENaC in normal and pathological physiology can be translated into clinical practice and fulfill the mission of NHLBI to improve health of the patients. Sodium loading is associated with an increase in blood pressure in normotensive and hypertensive individuals. Dahl salt-sensitive (SS) rats used in this proposal develop severe hypertension on high-salt diet. Our preliminary data indicate that ENaC-mediated Na+ reabsorption in the ASDN contributes to salt-sensitive hypertension in SS rat strain and I hypothesize here that excessive H2O2 production mediates this effect. ENaC subunits expression is inappropriately upregulated in SS rats fed a high salt diet compared to SS rats fed a low salt diet and consomic SS-13BN rats fed a high salt diet. Treatment with ENaC inhibitor benzamil attenuates increase in blood pressure in SS rats. Infiltrating T lymphocytes in the kidney increase oxidative stress and participate in the development of salt-sensitive hypertension in SS rats. Moreover, our preliminary results demonstrate that ENaC activity is upregulated by H2O2 production. I hypothesize that ENaC-mediated Na+ reabsorption in the ASDN plays a role in the development of salt-sensitive hypertension and that activation of immune cells increases generation of H2O2, which correspondingly activates ENaC and participates in the development of salt-sensitive hypertension. It is further hypothesized that increased H2O2 production results in changes of the actin cytoskeleton and that cortactin and MIM proteins are involved in this mechanism. Built upon our preliminary data and previously published findings, the specific objectives of this proposal are to determine whether infiltration increases H2O2 production in the kidney cortex and consequently upregulates ENaC-mediated sodium reabsorption in the ASDN and define the precise mechanisms of H2O2-mediated changes in ENaC activity. A combination of variety approaches will be used in this proposal to provide mechanistic insights on how ENaC is regulated by H2O2 and how changes in this pathway contribute to salt-induced hypertension. These studies will address two Specific Aims: 1) To determine if infiltration of T cells and consecutive H2O2 production in SS rats increases ENaC activity; 2) To define the cellular and molecular mechanism by which H2O2 modulates ENaC activity. My long-term professional goal is to continue my academic career in the field of biomedical research to study ion channels involved in regulation of salt and water balance at the cellular, organ and systemic levels. The K99/R00 grant fits to my career goals providing excellent opportunity to assist in transitioning to a stable independent research position with NIH or other independent research funding.