Li Jie, Ren Xiaohu, Wang Lingwei, Yu Xiu, Khan Khalid, Feng Mengjie, He Qi, Luo Huanmin, Qiu Chen
Department of Respiratory Diseases, Second Clinical Medical College (Shenzhen People's Hospital), Jinan University, Shenzhen, China.
Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou, China.
Cell Physiol Biochem. 2018;48(1):237-250. doi: 10.1159/000491723. Epub 2018 Jul 13.
BACKGROUND/AIMS: Thermal injury causes pulmonary edema and can lead to death. Intercellular junctions are composed of adhesive (p120ctn, E-cadherin, α-catenin and β-catenin) and compact (occludin and ZO-1) junctions. Heat deteriorates intercellular junctions and increases cell gaps to ultimately induce pulmonary edema, but the underlying mechanism remains elusive.
Mouse lung epithelial (MLE-12) cells pre-treated with the c-Src inhibitor PP2, p120ctn catenin (p120ctn) small interfering RNA and p120ctn catenin (p120ctn) complementary DNA were subjected to heat treatment. Western blotting and real-time polymerase chain reaction assays were used to evaluate junction protein expression changes after heat treatment, and co-immunoprecipitation was used to test the binding state of junction proteins. In addition, hematoxylin and eosin staining and immunohistochemistry were used to evaluate changes in junction protein expression and lung injury in a Wistar rat model of thermal inhalation injury.
Heat increased cell permeability; induced ZO-1, occludin, α-catenin and β-catenin degradation; and decreased E-cadherin distribution in cell membranes. Heat also activated c-Src and decreased both p120ctn expression levels and occludin and ZO-1 association. c-Src inhibitor (PP2) treatment and p120ctn overexpression reversed these effects and attenuated lung injury in vivo.
Heat induces junction protein degradation and dissociation to increase membrane permeability and cause lung edema via c-Src kinase activation and p120ctn expression downregulation.
背景/目的：热损伤可导致肺水肿并可能致死。细胞间连接由黏附连接（p120连环蛋白、E-钙黏蛋白、α-连环蛋白和β-连环蛋白）和紧密连接（闭合蛋白和紧密连接蛋白1）组成。热会破坏细胞间连接并增加细胞间隙，最终诱发肺水肿，但其潜在机制仍不清楚。
用c-Src抑制剂PP2、p120连环蛋白（p120ctn）小干扰RNA和p120连环蛋白（p120ctn）互补DNA预处理小鼠肺上皮（MLE-12）细胞，然后进行热处理。采用蛋白质免疫印迹法和实时聚合酶链反应分析评估热处理后连接蛋白表达的变化，并用免疫共沉淀法检测连接蛋白的结合状态。此外，采用苏木精-伊红染色和免疫组织化学法评估热吸入损伤Wistar大鼠模型中连接蛋白表达的变化和肺损伤情况。
热增加了细胞通透性；诱导紧密连接蛋白1、闭合蛋白、α-连环蛋白和β-连环蛋白降解；并减少了E-钙黏蛋白在细胞膜上的分布。热还激活了c-Src，降低了p120ctn的表达水平以及闭合蛋白与紧密连接蛋白1的结合。c-Src抑制剂（PP2）处理和p120ctn过表达可逆转这些效应，并减轻体内肺损伤。
热通过激活c-Src激酶和下调p120ctn表达，诱导连接蛋白降解和解离，增加膜通透性并导致肺水肿。
