Collecting duct endothelin and sodium homeostasis

集合管内皮素和钠稳态

• 批准号: 8002593
• 负责人: Donald E Kohan
• 金额: $ 51.5万
• 依托单位: AUGUSTA UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-06 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8002593
• 关键词: Address; Antihypertensive Agents; Apical; Binding; Biology; Blood Pressure; Cell Culture Techniques; Cells; Coupled; Coupling; Data; Defect; Duct (organ) structure; Electrophysiology (science); Endothelin; Endothelin A Receptor; Endothelin B Receptor; Endothelin-1; Excretory function; Extracellular Fluid; Gene Targeting; Genes; Genetic Transcription; Genetically Engineered Mouse; Homeostasis; Hypertension; Kidney; Lead; Liquid substance; Mediating; Molecular; Mus; Pathway interactions; Physiological; Preparation; Probability; Production; Regulation; SRC gene; Signal Pathway; Signal Transduction; Sodium; System; Testing; Transcriptional Activation; Tubular formation; autocrine; base; cis acting element; epithelial Na+ channel; extracellular; polycystic kidney disease 1 protein; promoter; receptor; receptor coupling; response; saluretic; tool

The collecting duct (CD) endothelin system has emerged as an important regulator of renal Na excretion and systemic blood pressure (BP). CD-derived endothelin-1 (ET-1) exerts a hypotensive effect that is likely due, at least partly, to inhibition of the CD epithelial Na channel (ENaC). CD-derived ET-1 is important in mediating the natriuretic response to extracellular fluid volume (ECFV) expansion and controlling arterial BP; defects in the CD ET-1 system may contribute to hypertension. While the general biology of the CD ET system has been established, there remains much unknown about how this system functions. In particular, key components in critical need of study are: 1) determination if and how ET-1 inhibits CD Na transport; and 2) determination how ECFV status is coupled to CD ET-1 production. Based on preliminary data, the proposed studies will address the following hypotheses; ECFV expansion increases tubule fluid fiow rate through the CD. Increased fiow increases intracellular Ca concentration [Ca2+] through polycystins-1 and -2. Increased CD [Ca2+] induces signaling pathways causing transcriptional activation of the ET-1 gene. This increases CD ET-1 production and secretion resulting in autocrine activation of most likely the ETB receptor (ETRB), but also possibly the ETA receptor (ETRA). ET-1 binding leads to inhibition of the ENaC through reduction of channel open probability (Po) and possibly apical channel number (N). The effect on Po is due, at least partly, to activation of the c-src/MAPK pathway. The specific aims for this project include: Aim 1. Test the hypothesis that fiow stimulates CD ET-1 production, and that this effect is exerted by activation of specific cellular signaling pathways, cis-acting elements and trans-activating factors. Accordingly, we will: a) determine the effects of flow on CD ET-1 production; and b) determine the cellular signaling pathways, cis-acting elements and trans-activating factors coupling flow and intracellular Ca to ET-1 gene transcription. Aim 2. Test the hypothesis that ET-1 regulates ENaC in the CD, and that specific cellular and molecular mechanisms underpin this regulation. Accordingly, we will: a) determine if ET-1 regulates ENaC Po in native isolated CD cells; b) identify the specific ET receptor involved in regulating ENaC in native CD cells and elucidate the cellular signaling pathway coupling this receptor to the channel; c) define the importance of ET-1 regulation of CD ENaC in physiologic control of renal Na handling, and probe pathophysiological consequences of disrupting this regulation using gene targeted mice; and d) define the molecular mechanisms by which ET-1 modulates ENaC function, including identifying the specific residues/regions of ENaC that enable the channel to respond to ET-1.

集合管（CD）内皮素系统已成为肾Na排泄的重要调节因子 和全身血压（BP）。 CD 衍生内皮素-1 (ET-1) 可能具有降压作用 至少部分是由于 CD 上皮 Na 通道 (ENaC) 的抑制。 CD 衍生的 ET-1 在以下方面很重要 介导对细胞外液容量 (ECFV) 扩张的利尿钠反应并控制动脉血压； CD ET-1 系统的缺陷可能导致高血压。虽然 CD ET 的一般生物学 系统已经建立，但该系统如何运作仍存在很多未知。尤其， 迫切需要研究的关键部分是：1）确定 ET-1 是否以及如何抑制 CD Na 转运；和 2) 确定ECFV状态如何与CD ET-1生产耦合。根据初步数据， 拟议的研究将解决以下假设； ECFV 扩张增加肾小管液流量 通过CD。流量增加通过多囊蛋白-1 和-2 增加细胞内 Ca 浓度 [Ca2+]。 CD [Ca2+] 增加会诱导信号通路导致 ET-1 基因转录激活。这 增加 CD ET-1 的产生和分泌，导致最有可能的 ETB 受体的自分泌激活 (ETRB)，也可能是 ETA 受体 (ETRA)。 ET-1 结合通过减少通道开放概率 (Po) 和可能的顶端通道数 (N) 来抑制 ENaC。对 Po 的影响至少部分归因于 c-src/MAPK 途径的激活。该项目的具体目标包括： 目标 1. 检验以下假设：流动刺激 CD ET-1 的产生，并且这种效应是通过 激活特定的细胞信号传导途径、顺式作用元件和反式激活因子。 因此，我们将： a) 确定流动对 CD ET-1 生产的影响； b) 确定细胞信号通路、顺式作用元件和反式激活因子耦合流和细胞内 Ca 与 ET-1 基因转录。 目标 2. 检验以下假设：ET-1 调节 CD 中的 ENaC，以及特定的细胞和分子机制支撑这种调节。因此，我们将： a) 确定 ET-1 是否调节天然分离 CD 细胞中的 ENaC Po； b) 鉴定参与调节天然 CD 细胞中 ENaC 的特定 ET 受体，并阐明将该受体与通道耦合的细胞信号传导途径； c) 定义 ET-1 对 CD ENaC 的调节在肾脏 Na 处理的生理控制中的重要性，并利用基因靶向小鼠探讨破坏这种调节的病理生理学后果； d) 定义 ET-1 调节 ENaC 功能的分子机制，包括识别 ENaC 的特定残基/区域，使通道能够响应 ET-1。