Angiotensin II uncoupling of eNOS in hypertension

高血压中血管紧张素 II 与 eNOS 的解偶联

基本信息

批准号：
6985063
负责人：
Hua Linda Cai
金额：
$ 38.13万
依托单位：
UNIVERSITY OF CHICAGO
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-07-13 至 2010-06-30
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Accumulating evidence suggests that oxidant stress contributes to the pathogenesis of hypertension and atherosclerosis. Vascular NAD(P)H oxidases are activated in hypertension, predominantly contribute to vascular production of reactive oxygen species (ROS). Indeed, scavenging of ROS with either antioxidant enzymes or inhibitors of vascular NAD(P)H oxidases significantly restores endothelial function to reduce blood pressure. Nevertheless, these treatments failed to completely normalize endothelial function or blood pressure, implicating involvement of other mechanisms that are not readily reversible by scavenging ROS. Recent studies demonstrated that in atherosclerotic or hypertensive blood vessels, endothelial nitric oxide synthase (eNOS) transformed from an antioxidant enzyme into a pro-oxidant enzyme producing ROS rather than nitric oxide. 1 of the causes for this uncoupling of eNOS seems to be a deficiency in eNOS cofactor tetrahydrobiopterin (H4B). It is interesting to speculate that unsatisfactory outcomes of some antioxidant therapies are partially due to their ineffectiveness in recoupling eNOS. The precise mechanisms as to how H4B becomes persistently deficient under disease conditions remain unclear. We and others have recently shown that angiotensin II uncouples eNOS in vitro and in vivo (Figures 1-3, Mollnau et al Cir Res 90: E58-65). In this project we will fully characterize this phenomenon and determine whether it is mediated by vascular NAD(P)H oxidase-derived hydrogen peroxide and an endothelial H4B deficiency (aim 1). In aim 2 we will determine whether angiotensin II modulation of endothelial H4B salvage enzymes contributes to endothelial H4B deficiency. Effects on eNOS recoupling, endothelial function and blood pressure of H4B precursors/analogues, inhibition of vascular NAD(P)H oxidases, overexpression of H4B salvage enzymes or combination of 2 or more will be studied in angiotensin II infused mice. In aim 3 we will examine potential roles of eNOS monomerization, threonine phosphorylation and dissociation from heat shock protein 90 (HSP90) in angiotensin II uncoupling of eNOS and their interdependence with H4B deficiency. Effects on eNOS recoupling of agents promoting eNOS dimerization and its association with HSP90 will be studied. These proposed experiments could ultimately lead to novel therapeutics restoring nitric oxide production from uncoupled eNOS, which are anticipated to reduce blood pressure and impede atherosclerosis. We will also determine whether eNOS uncoupling augments hypertension (aim 4, H4B-deficient hph-1 mice will be studied). This will address the question: is eNOS uncoupling a mere consequence/marker of hypertension or 1 of the causes?

描述（由申请人提供）：积累证据表明氧化应激有助于高血压和动脉粥样硬化的发病机理。血管NAD（P）H氧化酶在高血压中被激活，主要有助于活性氧（ROS）的血管产生。实际上，用抗氧化剂酶或血管NAD（P）H氧化酶的抑制剂清除ROS可显着恢复内皮功能以降低血压。然而，这些治疗方法未能完全使内皮功能或血压完全归一化，这暗示了其他机制的参与，而其他机制则无法通过清除ROS而容易逆转。最近的研究表明，在动脉粥样硬化或高血压血管中，从抗氧化剂转化为产生抗氧化酶的内皮一氧化氮合酶（ENOS），从而转化为产生ROS而不是一氧化氮的促氧化酶。 eNOS解耦合的1个原因似乎是eNOS辅助因子四氢无生蛋白（H4B）的缺陷。有趣的是，推测某些抗氧化剂疗法的结果不令人满意，部分原因是它们在恢复eNOS中的效率低下。关于H4B如何在疾病条件下持续缺乏的确切机制尚不清楚。我们和其他人最近表明，血管紧张素II的体外和体内eNOS eNOS（图1-3，Mollnau等人CIR Res 90：e58-65）。在这个项目中，我们将充分表征这种现象，并确定它是否是由血管NAD（P）H氧化酶衍生的过氧化氢和内皮H4B缺乏症介导的（AIM 1）。在AIM 2中，我们将确定血管紧张素II的内皮H4B打捞酶是否有助于内皮H4B缺乏症。对H4B前体/类似物的eNOS再耦，内皮功能和血压的影响，抑制血管NAD（P）H氧化酶，H4B拯救酶的过表达或在Angiotensin II注入小鼠中的影响。在AIM 3中，我们将检查eNOS单体化，苏氨酸磷酸化和热休克蛋白90（HSP90）的潜在作用，在血管紧张素II的ENOS偶联及其与H4B缺乏的相互依赖性中。将研究促进eNOS二聚化及其与HSP90关联的eNOS重耦的影响。这些提出的实验最终可能导致新型的治疗剂恢复未偶联的eNOS产生一氧化氮，这预计会降低血压并阻碍动脉粥样硬化。我们还将确定是否会研究ENOS解偶联增强高血压（AIM 4，缺陷HPH-1小鼠）。这将解决以下问题：eNOS是否将高血压的后果/标记或1个原因取消？