Mechanisms of Hormonal Regulation of the Sodium Chloride Cotransporter

描述（由申请人提供）：噻嗪类药物敏感的氯化钠共转运体（NCC）是盐平衡和全身血压的关键决定因素之一。然而，与盐平衡的其他重要效应物相比，我们对激素和生理信号如何改变这种共转运体的活性知之甚少。初步数据表明，ERK1/2 MAPK（细胞外信号调节激酶1和2丝裂原活化蛋白激酶）通路在NCC的泛素化和内吞作用中起作用。与- no - lysine Kinase 1和4 (WNK1和WNK4)， ste20相关的脯氨酸-丙氨酸-富激酶（SPAK）和氧化应激反应-1 （OSR1）也是NCC的重要调节因子，并且有数据表明一些激素调节NCC。然而，激素与介导激素对NCC影响的细胞内通路之间的联系尚未建立。提出的研究的广泛假设是，NCC受激素调节，通过调节激酶ERK1/2、SPAK/OSR和WNKs进行调节。Aim 1将通过激活ERK1/2 MAPK来定义NCC的激素调节。ERK1/2 MAPK将作为表皮生长因子（EGF）和钙敏感受体（CaSR）在NCC中激素/生理作用的中心介质进行研究。我们将深入研究ERK1/2的激活机制以及泛素化和内吞作用在这一过程中的作用，追踪从激素刺激到功能作用的途径。目的2将确定醛固酮通过ERK1/2 MAPK和SPAK/OSR对NCC的激素调节及其作用机制。醛固酮抑制ERK1/2和激活SPAK/OSR可能导致NCC活性增加。WNKs在这些通路中的作用将被彻底研究。目的3将确定血管紧张素II介导NCC激素调节的潜在分子机制。每个这些激酶途径的作用将被检查，特别强调WNKs。哺乳动物细胞培养，分离小管微灌注和全动物实验将用于检查细胞/分子，小管和组织水平的影响。激素调节血压的知识在开发治疗高血压的新疗法中发挥了关键作用，高血压是导致全球死亡最多的单一危险因素。这些研究将提供关于调节这一重要的血压稳态效应的重要信息。

DESCRIPTION (provided by applicant): The thiazide-sensitive sodium chloride cotransporter (NCC) is one of the key determinants of salt balance and thus systemic blood pressure. However, in contrast to other important effectors of salt balance we know little about how hormonal and physiological signals alter activity of this cotransporter. Preliminary data demonstrates the role of the ERK1/2 MAPK (Extra-cellular signal-Regulated Kinases 1 and 2 Mitogen-Activated Protein Kinases) pathway in the ubiquitination and endocytosis of NCC. With-No-Lysine Kinase 1 and 4 (WNK1 and WNK4), Ste20-related proline alanine-rich kinase (SPAK) and Oxidative Stress Response-1 (OSR1) are also important regulators of NCC, and there is data that some hormones regulate NCC. However, a link between hormones and the intracellular pathways that mediate the effects of hormones on NCC has not been established. The broad hypothesis of the proposed investigation is that NCC is subject to hormonal regulation that proceeds through modulation of the kinases ERK1/2, SPAK/OSR and WNKs. Aim 1 will define the hormonal regulation of NCC through activation of ERK1/2 MAPK. ERK1/2 MAPK will be examined as a central mediator of the hormonal/physiological effects of Epidermal Growth Factor (EGF) and the Calcium-sensing Receptor (CaSR) on NCC. The mechanism of ERK1/2 activation and the roles of ubiquitination and endocytosis in this process will be thoroughly examined for each hormone, tracing a pathway from hormonal stimulus to functional effect. Aim 2 will determine the hormonal regulation of NCC by Aldosterone through ERK1/2 MAPK and SPAK/OSR and the mechanisms underlying these effects. ERK1/2 inhibition and SPAK/OSR activation by Aldosterone may lead to increased NCC activity. The role of WNKs in these pathways will be thoroughly examined. Aim 3 will determine the underlying molecular mechanisms mediating hormonal regulation of NCC by Angiotensin II. The roles of each of these kinase pathways will be examined with a particular emphasis on WNKs. Mammalian cell culture, isolated tubule microperfusion and whole animal experimentation will be utilized to examine effects at the cellular/molecular, tubular and organismal level. Knowledge of hormonal regulation of blood pressure has played a critical role in the development of new therapies to treat hypertension, the single risk factor that contributes the most to worldwide mortality. These studies will provide vital information on the regulation of this important effector of blood pressure homeostasis.