Li Yue, Chang Jianjun, Cui Yong, Zhao Runzhen, Ding Yan, Hou Yapeng, Zhou Zhiyu, Ji Hong-Long, Nie Hongguang
Institute of Metabolic Disease Research and Drug Development, China Medical University, Shenyang 110122, Liaoning, China.
Department of Anesthesiology, First Affiliated Hospital of China Medical University, Shenyang 110001, Liaoning, China.
Oncotarget. 2017 May 12;8(48):83509-83522. doi: 10.18632/oncotarget.17840. eCollection 2017 Oct 13.
Crotonaldehyde is a highly noxious α,β-unsaturated aldehyde in cigarette smoke that causes edematous acute lung injury.
To understand how crotonaldehyde impairs lung function, we examined its effects on human epithelial sodium channels (ENaC), which are major contributors to alveolar fluid clearance.
We studied alveolar fluid clearance in C57 mice and ENaC activity was examined in H441 cells. Expression of α- and γ-ENaC was measured at protein and mRNA levels by western blot and real-time PCR, respectively. Intracellular ROS levels were detected by the dichlorofluorescein assay. Heterologous αβγ-ENaC activity was observed in an oocyte model.
Our results showed that crotonaldehyde reduced transalveolar fluid clearance in mice. Furthermore, ENaC activity in H441 cells was inhibited by crotonaldehyde dose-dependently. Expression of α- and γ-subunits of ENaC was decreased at the protein and mRNA level in H441 cells exposed to crotonaldehyde, which was probably mediated by the increase in phosphorylated extracellular signal-regulated protein kinases 1 and 2. ROS levels increased time-dependently in cells exposed to crotonaldehyde. Heterologous αβγ-ENaC activity was rapidly eliminated by crotonaldehyde.
Our findings suggest that crotonaldehyde causes edematous acute lung injury by eliminating ENaC activity at least partly via facilitating the phosphorylation of extracellular signal-regulated protein kinases 1 and 2 signal molecules. Long-term exposure may decrease the expression of ENaC subunits and damage the cell membrane integrity, as well as increase the levels of cellular ROS products.
巴豆醛是香烟烟雾中一种剧毒的α,β-不饱和醛，可导致水肿性急性肺损伤。
为了解巴豆醛如何损害肺功能，我们研究了其对人上皮钠通道（ENaC）的影响，ENaC是肺泡液体清除的主要贡献者。
我们研究了C57小鼠的肺泡液体清除情况，并检测了H441细胞中的ENaC活性。分别通过蛋白质印迹法和实时PCR在蛋白质和mRNA水平上测量α-和γ-ENaC的表达。通过二氯荧光素测定法检测细胞内活性氧水平。在卵母细胞模型中观察异源αβγ-ENaC活性。
我们的结果表明，巴豆醛降低了小鼠的经肺泡液体清除率。此外，巴豆醛剂量依赖性地抑制了H441细胞中的ENaC活性。在暴露于巴豆醛的H441细胞中，ENaC的α-和γ-亚基的表达在蛋白质和mRNA水平上均降低，这可能是由磷酸化的细胞外信号调节蛋白激酶1和2的增加介导的。在暴露于巴豆醛的细胞中，活性氧水平随时间依赖性增加。巴豆醛迅速消除了异源αβγ-ENaC活性。
我们的研究结果表明，巴豆醛至少部分通过促进细胞外信号调节蛋白激酶1和2信号分子的磷酸化来消除ENaC活性，从而导致水肿性急性肺损伤。长期暴露可能会降低ENaC亚基的表达，损害细胞膜完整性，并增加细胞内活性氧产物的水平。
