Nedd4-dependent regulation of EnaC in hypertension

上皮性钠通道(ENaC)是肾素-血管紧张素-醛固酮途径的远端靶点，在血压控制中发挥重要作用。ENaC功能获得突变会导致利德尔综合征，这是一种遗传性高血压。相反，功能丧失突变会导致盐耗和低血压(假性低醛固酮增多症1型)的遗传紊乱。因此，了解这一通道的功能和调节机制将为人类血压变化和高血压的发病机制提供重要的见解。在这个项目中，我们响应了RFA的目标2：“遗传变异后果的机械论研究”。在初步研究中，我们发现ENaC与泛素蛋白连接酶Nedd4的相互作用在控制Na+吸收中起着重要作用。一些发现表明泛素蛋白连接酶在控制Na+吸收中起着重要作用。一些发现表明Nedd4可能在控制血压中发挥关键作用。首先，在初步研究中，我们发现Nedd4通过靶向降解通道来降低ENaC Na+电流。首先，在初步研究中，我们发现Nedd4通过靶向降解通道来降低ENaC Na+电流。其次，在利德尔综合征中，ENaC中与Ndd4(PY基序)结合的序列被删除或突变。第三，我们发现，利德尔综合征的BetaENaC亚基突变阻止了Nedd4抑制该通道。因此，本提案的总体目标是了解Nedd4抑制该通道的分子机制。因此，这项提案的总体目标是了解Nedd4抑制ENaC的分子机制，并开始确定这一途径在利德尔综合征和更常见的高血压形式中的作用。因此，这项提案的总体目标是了解Nedd4抑制ENaC的分子机制，并开始确定这一途径在利德尔综合征和更常见的高血压形式中的作用。在前两个特定目标中，我们将研究Nedd4抑制ENaC的分子决定因素。具体目标1将集中在Nedd4的C2结构域在ENaC的钙依赖抑制中的作用，以及Nedd4的WW结构域与ENaC的PY基序之间的物理相互作用。特异性目标2将补充目标1，确定ENaC中参与Nedd4相互作用和抑制的序列。具体地说，我们将研究在利德尔综合征中靶向的PY基序的作用，并测试Nedd4介导的抑制需要ENaC泛素化的假设。在具体目标3中，我们将研究在高血压人群中发现的ENaC自然遗传变异的功能后果。这可能为了解ENaC和Nedd4在人类血压变化和高血压发病机制中的作用提供重要的新见解。

The epithelial Na+ channel (ENaC) is a distal target of the renin- angiotensin-aldosterone pathway, where it is critically positioned to play an important role in blood pressure control. Gain-of-function mutations in ENaC cause Liddle's syndrome, an inherited form of hypertension. Conversely, loss-of-function mutations cause a genetic disorder of salt wasting and hypotension (pseudohypoaldosteronism type 1). Thus, an understanding of the function and regulation of this channel will provide important insights into human blood pressure variations and the pathogenesis of hypertension. In this project, we are responsive to Goal 2 of the RFA; "mechanistic studies on the consequence of genetic variation." In preliminary studies, we found that the interaction of ENaC with Nedd4, a ubiquitin protein-ligase, plays an important role in controlling Na+ absorption. Several findings suggest that a ubiquitin protein-ligase plays an important role in controlling Na+ absorption Several findings suggest that Nedd4 might play a critical role in the control of blood pressure. First, in preliminary studies we found that Nedd4 decreases ENaC Na+ current by targeting the channel for degradation. First, in preliminary studies we found that Nedd4 decreases ENaC Na+ current by targeting the channel for degradation. Second, the sequences in ENaC that bind to Ndd4 (PY motifs) are deleted or mutated in Liddle's syndromes. Third, we found that Liddle's syndrome mutations in the betaENaC subunit prevention Nedd4 from inhibiting the channel. Thus, the overall goal of this proposal is to understand the molecular mechanisms by which Nedd4 from inhibiting the channel. Thus, the overall goal of this proposal is to understand the molecular mechanisms by which Nedd4 inhibits ENaC, and to begin to define the role of this pathway in Liddle's syndrome and more common forms of hypertension. Thus, the overall goal of this proposal is to understand the molecular mechanisms by which Nedd4 inhibits ENaC, and to begin to define the role of this pathway in Liddle's syndrome and more common forms of hypertension. In the first two specific aims, we will investigate the molecular determinants for the inhibition of ENaC by Nedd4. Specific Aim 1 will focus on the role of a C2 domain in Nedd4 in the Ca2+- dependent inhibition of ENaC, and on the physical interaction between WW domains in Nedd4 and the PY motifs of ENaC. Specific Aim 2 will complement Aim 1, determining the sequences in ENaC that are involved in the interaction and inhibition by Nedd4. Specifically, we will examine the role of the PY motifs that are targeted in Liddle's syndrome, and test the hypothesis that ubiquitination of ENaC is required for Nedd4- mediated inhibition. In Specific Aim 3, we will examine the functional consequences of natural genetic variation in ENaC found in hypertensive populations. This may provide important new insight into the role of ENaC and Nedd4 in human blood pressure variation and the pathogenesis of hypertension.