NADPH oxidase signaling, blood pressure sensing and the development of myogenic tone

NADPH 氧化酶信号传导、血压传感和肌源性张力的发展

• 批准号: RGPIN-2017-04659
• 负责人: Welsh, Donald
• 金额: $ 2.33万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=711100
• 关键词: NADPH; oxidase; signaling; blood; pressure

Under dynamic conditions, arterial tone is regulated by multiple stimuli including neuronal activity, tissue metabolism and intravascular pressure. A century ago, Bayliss first observed that arteries could respond to changes in blood pressure. The “myogenic response” has been documented in various vascular beds and is dependent upon a rise in smooth muscle [Ca2+]. Elevated pressure augments smooth muscle [Ca2+] by activating signal transduction pathways that: 1) depolarize smooth muscle and elevate Ca2+ channel activity; and 2) mobilize internal Ca2+ stores. While some of the ion channels driving myogenic tone development have have been identified, the signaling cascades which enable pressure modulation have not. Present day work typically focuses on standard G-protein coupled mechanisms and few venture “outside this signaling box” to consider novel molecules. This includes reactive oxygen species whose production could be facilitated by NADPH oxidases (NOX), enzymes known to associate with mechanosensitive proteins. Consistent with our long term interests in the myogenic response, this NSERC proposal will explore the linkage between intravascular pressure, NOX signaling and myogenic tone in the cerebral circulation. The three aims will: 1) Determine whether NOX facilitates myogenic tone. 2) Determine whether NOX facilitates myogenic tone via electromechanical coupling. 3) Determine whether NOX modulates ion channels sensitive to mechanical stimuli. Our overarching hypothesis states that NOX (in particular NOX1) augments TRPC6 and/or TRPM4 activity in vascular smooth muscle by generating H2O2 and activating PKC. This increase in depolarizing current will facilitate pressure-induced depolarization, an event that will elevate cytosolic [Ca2+] and myogenic tone. Our experimental approach will synergistically employ: 1) vessel myography to assess tone, membrane potential, and cytosolic [Ca2+], 2) Q-PCR and immunohistochemistry to determine NOX expression and localization; and 3) electrophysiology to ascertain ion channel activity. Experiments will be performed in cerebral arteries isolated from rat, NOX1-/- mice and humans. Our focus on pressure-sensing and NOX signaling will foster a deeper mechanistic appreciation of the myogenic response and its biological significance to blood pressure and blood flow regulation.

在动态条件下，动脉张力受多种刺激调节，包括神经元活动、组织代谢和血管内压力。 一个世纪前，贝利斯首次观察到动脉可以对血压的变化做出反应。 “肌源性反应”已在各种血管床中记录，并依赖于平滑肌[Ca 2 +]的升高。 升高的压力通过激活信号转导途径增加平滑肌[Ca 2 +]，所述信号转导途径：1）使平滑肌脱钙并提高Ca 2+通道活性;和2）动员内部Ca 2+储存。 虽然已经鉴定了一些驱动肌源性张力发展的离子通道，但是使得压力调节成为可能的信号级联还没有。目前的工作通常集中在标准的G-蛋白偶联机制，很少冒险“在这个信号框之外”考虑新的分子。这包括活性氧物质，其产生可以通过NADPH氧化酶（NOX）促进，所述酶已知与机械敏感蛋白质相关。 与我们对肌源性反应的长期兴趣一致，本NSERC提案将探索脑循环中血管内压力、NOX信号传导和肌源性张力之间的联系。 这三个目标将： 1)确定NOX是否促进肌源性张力。 2)确定NOX是否通过机电耦合促进肌源性张力。 3)确定NOX是否调节对机械刺激敏感的离子通道。 我们的总体假设表明，NOX（特别是NOX 1）通过产生H2 O2和激活PKC来增强血管平滑肌中TRPC 6和/或TRPM 4的活性。这种去极化电流的增加将促进压力诱导的去极化，这是一种将升高细胞溶质[Ca 2 +]和肌源性张力的事件。 我们的实验方法将协同采用：1）血管肌造影术，以评估张力，膜电位和胞质[Ca 2 +]，2）Q-PCR和免疫组织化学，以确定NOX的表达和定位;和3）电生理学，以确定离子通道活性。实验将在从大鼠、NOX 1-/-小鼠和人类分离的脑动脉中进行。 我们对压力传感和NOX信号的关注将促进对肌源性反应及其对血压和血流调节的生物学意义的更深层次的机械评价。