ENaC Regulation by Nedd4-2 and SGK

Nedd4-2 和 SGK 的 ENaC 法规

• 批准号: 6797888
• 负责人: Peter M Snyder
• 金额: $ 25.73万
• 依托单位: UNIVERSITY OF IOWA
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6797888
• 关键词: Xenopus oocyte; aldosterone; calcium binding protein; corticosteroid receptors; cyclic AMP; electrolyte balance; epithelium; gene mutation; hypertension; protein binding; protein kinase; protein protein interaction; protein structure function; receptor binding; receptor expression; renal tubular transport; saluresis; site directed mutagenesis; sodium channel; tissue /cell culture; Xenopus oocyte; aldosterone; calcium binding protein; corticosteroid receptors; cyclic AMP; electrolyte balance; epithelium; gene mutation; hypertension; protein binding; protein kinase; protein protein interaction; protein structure function; receptor binding; receptor expression; renal tubular transport; saluresis; site directed mutagenesis; sodium channel; tissue /cell culture

DESCRIPTION (provided by applicant): The epithelial Na+ channel, ENaC, forms the pathway for Na+ absorption in the kidney collecting duct and other epithelia (1, 2). Specific ENaC mutations lead to excessive channel expression at the cell surface, resulting in a genetic form of hypertension (Liddle's syndrome). Aldosterone and other steroid hormones regulate Na+ absorption by altering the expression of ENaC at the cell surface. Thus, understanding the mechanisms that control ENaC surface expression wifi provide critical new insights into the molecular mechanisms of Na+ homeostasis, and the pathogenesis of hypertension. Previous work found that Nedd4 and Nedd4-2 reduce ENaC surface expression by targeting the channel for degradation. A defect in this pathway is responsible for Liddle's syndrome. Conversely, serum and glucocorticoid-regulated kinase (SGK), a down-stream mediator of aldosterone, increases ENaC surface expression. Our preliminary studies suggest the novel hypothesis that these two pathways are not independent, but that they converge in a common pathway to regulate Na+ absorption. The goal of this project is to test the hypothesis that SGK modulates ENaC surface expression in part through Nedd4-2 binding and phosphorylation, and to understand the mechanisms involved. In the first specific aim, we will test the hypothesis that SGK phosphorylates Nedd4-2. We will identify the specific residues that are phosphorylated, and will test whether phoshorylation alters Nedd4-2 function. In specific aim two, we will test the hypothesis that SGK binds to Nedd4-2. We will identify the sequences that mediate this interaction, and test the functional role of binding. Specific forms of hypertension are caused by defects in ENaC regulation by Nedd4 family members (Liddle's syndrome) and defects in mineralocorticoid and glucocorticoid signaling signalling (e.g. glucocorticoid-remediable aldosteronism). Thus, our work will provide a new understanding of these forms of hypertension. In addition, by elucidating the pathways and proteins responsible for blood pressure control, this work may provide important new insights into the molecular causes of essential hypertension.

描述（由申请人提供）：上皮Na+通道ENAC构成了肾脏收集管和其他上皮的Na+吸收的途径（1，2）。特定的ENAC突变导致细胞表面过度的通道表达，从而导致高血压的遗传形式（Liddle综合征）。醛固酮和其他类固醇激素通过改变细胞表面的ENAC表达来调节Na+吸收。因此，了解控制ENAC表面表达WiFi的机制为NA+稳态的分子机制和高血压发病机理提供了关键的新见解。先前的工作发现NEDD4和NEDD4-2通过靶向降解通道来减少ENAC表面表达。该途径中的缺陷是Liddle综合征的原因。相反，血清和糖皮质激素调节的激酶（SGK）是醛固酮的下游介质，增加了ENAC表面表达。我们的初步研究表明，这两种途径不是独立的，但它们在调节Na+吸收的共同途径中收敛。该项目的目的是测试SGK通过NEDD4-2结合和磷酸化部分调节ENAC表面表达的假设，并了解所涉及的机制。在第一个特定目的中，我们将测试SGK磷酸化NEDD4-2的假设。我们将确定磷酸化的特定残基，并将测试phoshoration是否会改变NEDD4-2的功能。在特定目标二中，我们将测试SGK与NEDD4-2结合的假设。我们将确定介导这种相互作用的序列，并测试结合的功能作用。特定形式的高血压是由NEDD4家族成员（Liddle's综合征）的ENAC调节中的缺陷以及矿物皮质激素和糖皮质激素信号信号传导（例如糖皮质激素可抑制的醛固酮）引起的。因此，我们的工作将为这些高血压形式提供新的理解。此外，通过阐明负责血压控制的途径和蛋白质，这项工作可以为基本高血压的分子原因提供重要的新见解。