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

描述（由申请人提供）：上皮钠通道（ENaC）是醛固酮敏感远端肾元（ASDN）控制体液容量和血压中钠稳态的关键调节剂。ENaC的功能障碍和异常调节导致一系列与异常钠处理相关的疾病，从低钠到高血压，分别伴有钠潴存和钠消耗，再到呼吸综合征。关注ENaC在正常生理和病理生理中的作用的研究可以转化为临床实践，实现NHLBI改善患者健康的使命。在正常血压和高血压患者中，钠负荷与血压升高有关。本研究中使用的达尔盐敏感（SS）大鼠在高盐饮食中发生严重高血压。我们的初步数据表明，enact介导的ASDN Na+重吸收有助于SS大鼠品系的盐敏感性高血压，我在这里假设过量的H2O2产生介导了这一作用。与低盐喂养的SS大鼠和高盐喂养的经济型SS- 13bn大鼠相比，高盐喂养的SS大鼠ENaC亚基表达不适当上调。用ENaC抑制剂苯氨苄治疗可减轻SS大鼠血压升高。肾内浸润T淋巴细胞增加氧化应激，参与SS大鼠盐敏感性高血压的发生。此外，我们的初步结果表明，ENaC活性受到H2O2产生的上调。我推测ENaC介导的ASDN Na+重吸收参与了盐敏感性高血压的发生，免疫细胞的激活增加了H2O2的生成，H2O2相应激活ENaC，参与了盐敏感性高血压的发生。进一步假设H2O2生成的增加导致肌动蛋白细胞骨架的改变，而这一机制可能与接触蛋白和MIM蛋白有关。基于我们的初步数据和先前发表的研究结果，本提案的具体目标是确定浸润是否增加肾皮质中H2O2的产生，从而上调ENaC介导的ASDN中钠的重吸收，并确定H2O2介导的ENaC活性变化的确切机制。本研究将使用多种方法的组合来提供ENaC如何被H2O2调节的机制见解，以及该途径的变化如何促进盐诱导的高血压。这些研究将解决两个特定的目的：1)确定浸润T细胞和连续产生H2O2是否会增加SS大鼠ENaC活性；2)明确H2O2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，研究参与细胞、器官和全身水平盐和水平衡调节的离子通道。K99/R00奖助金符合我的职业目标，提供极好的机会协助我过渡到

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.