Regulation of Lung Sodium Channels

肺钠通道的调节

• 批准号: 6327062
• 负责人: LUCKY JAIN
• 金额: $ 30.47万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-05-01 至 2005-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6327062
• 关键词: hormone regulation /control mechanism; laboratory rat; lung; oxygen tension; phosphorylation; protein isoforms; protein structure function; respiratory epithelium; sodium channel; steroid hormone; voltage /patch clamp

Alveolar fluid clearance in the developing and mature lungs is believed to be mediated, in part, by amiloride-recorded from distal lung epithelia were different from channels reported from other Na+ transporting epithelia expressing ENaC. Preliminary experiments from this laboratory show that, when grown under appropriate culture conditions, rat alveolar type II (ATII) cells express three distinct types of cation channels that are capable of transporting Na+. The highly selective and non selective cation channels appear to belong to the ENaC family of Na+ channels, but bear striking differences in their biophysical properties, and in their regulation by signal transduction pathways, including those working through protein kinases A, G, and C. It is hypothesized that lung alveolar environment, including steroids and oxygen, is responsible for selective expression of highly selective and non selective cation channels in ATII cells, and this is achieved through different arrangements of ENaC subunits. Further, it is proposed that signal transduction pathways mediated by protein kinases A, G, and C regulate the expression and activity of both the highly selective, and non selective cation channels. These questions will be addressed by combining the use of patch clamp techniques and molecular biological approaches to characterize Na+ permeant channels in ATII cells. There are three specific aims to this proposal. The first aim is to contrast the biophysical properties of Na+ channels in ATII ells at the single channel level, and to establish their relationship to the cloned ENaC subunits. The second aim is to investigate conditions, including exposure to steroid hormones and differing oxygen tension, that lead to differences in the density of non selective channels and highly selective channels in ATII cells. The third aim is to contrast the regulation of highly selective and non-selective cation channels in ATII cells by phosphorylation and dephosphorylation. These experiments will improve our understanding of how lungs modulate alveolar fluid absorption, and help it devising therapeutic strategies to improve the process.

据信，发育中和成熟肺中的肺泡液清除部分是由远端肺上皮记录的阿米洛利介导的，这与表达 ENaC 的其他 Na+ 转运上皮报告的通道不同。该实验室的初步实验表明，在适当的培养条件下生长时，大鼠 II 型肺泡 (ATII) 细胞表达三种不同类型的能够运输 Na+ 的阳离子通道。高选择性和非选择性阳离子通道似乎属于 Na+ 通道的 ENaC 家族，但在生物物理特性以及信号转导途径（包括通过蛋白激酶 A、G 和 C 发挥作用的途径）的调节方面具有显着差异。据推测，包括类固醇和氧气在内的肺泡环境负责 ATII 细胞中高选择性和非选择性阳离子通道的选择性表达，这是通过 ENaC 亚基的不同排列来实现的。此外，有人提出，由蛋白激酶A、G和C介导的信号转导途径调节高选择性和非选择性阳离子通道的表达和活性。这些问题将通过结合使用膜片钳技术和分子生物学方法来表征 ATII 细胞中的 Na+ 渗透通道来解决。该提案有三个具体目标。第一个目的是在单通道水平上对比 ATII 细胞中 Na+ 通道的生物物理特性，并建立它们与克隆的 ENaC 亚基的关系。第二个目标是研究导致 ATII 细胞中非选择性通道和高选择性通道密度差异的条件，包括暴露于类固醇激素和不同的氧张力。第三个目的是对比 ATII 细胞中磷酸化和去磷酸化对高选择性和非选择性阳离子通道的调节。这些实验将提高我们对肺部如何调节肺泡液吸收的理解，并帮助其制定治疗策略来改善这一过程。