Regulatory mechanisms of fluid clearance and lung function by alveolar ion channels

肺泡离子通道对液体清除和肺功能的调节机制

• 批准号: RGPIN-2016-04378
• 负责人: Brochiero, Emmanuelle
• 金额: $ 2.26万
• 依托单位: Université de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=684046
• 关键词: Regulatory; mechanisms; fluid; clearance; lung

Lung function is dependent on alveolar epithelial cells that are responsible for surfactant production and transepithelial ion/liquid transport. Indeed, fluid clearance is required to maintain alveolar spaces virtually free of liquid, which is necessary for gas exchange. It has been established that liquid absorption is mainly driven by active ion transport through the Na+ channel ENaC. However, the complex regulatory mechanisms of ENaC and Na+/fluid transport remain incompletely understood.***Over the terms of our previous NSERC grants, we have made significant progress in the understanding of the mechanisms regulating ENaC channels and Na+/liquid transport through primary alveolar type II (ATII) cells. Our work also unveiled another class of channels, i.e. K+ channels (KCh, namely KATP and KvQT1 channels) that regulates ENaC expression via changes in promoter activity and participate in the control of Na+/liquid absorption. Finally, we have implemented an integrative murine model to study the clearance of fluids and lung function parameters. Our preliminary in vivo data indicated a relationship between ENaC and KCh and a control of alveolar fluid clearance, surfactant expression and lung compliance by KCh. We now propose to pursue our research program to dissect the complementary roles of ENaC and KCh in the control of fluid absorption and lung function using both cellular and animal models.****Our first goal will be to investigate, at the cellular level: 1) the signals controlling ENaC expression and the region of the ENaC promoter involved in ENaC regulation by KCh and 2) the complementary function, and relative contribution, of ENaC and KCh, on liquid absorption through ATII cells under basal conditions as well as following stimulation with -adrenergic agonists or corticosteroids. Expression of surfactant proteins will also be evaluated. Our second aim will be to pursue our in vivo studies in mice after ion channel silencing, or conversely after instillation of pharmacological compounds stimulating Na+ and K+ transport. Based on our in vitro observation showing a relationship between KCh function and ENaC expression, we will measure the level of expression of ion channels and transporters involved in alveolar clearance in situ. Finally, we will define the physiological effects of ENaC and KCh modulation on liquid clearance, surfactant production, lung function parameters as well as blood gases; in basal conditions and after stimulation with -adrenergic agonists or corticosteroids.***Our research program will allow a better understanding of the regulatory mechanisms responsible for the control of major functions of alveolar cells in lung epithelial physiology, in non-pathological conditions. Combining molecular and cellular aspects as well as an integrative model to study lung physiology in mice, our NSERC program also provides high level, multidisciplinary training to HQP in our lab.**

肺功能依赖于负责表面活性剂产生和跨上皮离子/液体运输的肺泡上皮细胞。事实上，需要液体间隙来保持肺泡空间几乎没有液体，这是气体交换所必需的。已经确定液体吸收主要由通过 Na+ 通道 ENaC 的活性离子传输驱动。然而，ENaC 和 Na+/液体转运的复杂调节机制仍未完全了解。***根据我们之前的 NSERC 拨款条款，我们在了解通过初级通道调节 ENaC 通道和 Na+/液体转运的机制方面取得了重大进展。肺泡 II 型 (ATII) 细胞。我们的工作还揭示了另一类通道，即 K+ 通道（KCh，即 KATP 和 KvQT1 通道），它通过启动子活性的变化调节 ENaC 表达并参与 Na+/液体吸收的控制。最后，我们建立了一个综合小鼠模型来研究液体的清除率和肺功能参数。我们的初步体内数据表明 ENaC 和 KCh 之间的关系以及 KCh 对肺泡液清除、表面活性剂表达和肺顺应性的控制。我们现在建议继续我们的研究计划，利用细胞和动物模型来剖析 ENaC 和 KCh 在控制液体吸收和肺功能中的互补作用。****我们的首要目标是在细胞水平上进行研究： 1) 控制 ENaC 表达的信号和参与 KCh 调节 ENaC 的 ENaC 启动子区域；2) ENaC 和 KCh 在基础条件下以及刺激后对 ATII 细胞液体吸收的互补功能和相对贡献与β-肾上腺素能激动剂或皮质类固醇合用。还将评估表面活性蛋白的表达。我们的第二个目标是在离子通道沉默后或相反地在滴注刺激Na+和K+转运的药理学化合物后在小鼠体内进行体内研究。根据我们显示 KCh 功能和 ENaC 表达之间关系的体外观察，我们将测量参与肺泡清除的离子通道和转运蛋白的表达水平。最后，我们将定义 ENaC 和 KCh 调节对液体清除、表面活性剂产生、肺功能参数以及血气的生理影响；在基础条件下以及用β-肾上腺素能激动剂或皮质类固醇刺激后。***我们的研究计划将有助于更好地了解在非病理条件下负责控制肺上皮生理学中肺泡细胞主要功能的调节机制。我们的 NSERC 项目结合分子和细胞方面以及综合模型来研究小鼠肺生理学，还为我们实验室的 HQP 提供高水平、多学科培训。 **