细胞外调节蛋白激酶信号通路参与机械牵张诱导肺泡上皮细胞高迁移率族蛋白B1的表达调控

目的 探讨细胞外调节蛋白激酶（ERK）信号通路在机械牵张诱导肺泡上皮细胞（A549）表达高迁移率族蛋白B1（HMGB1）中的作用。 方法 肺泡上皮细胞A549分为A、B、C 3组，A组为对照组；B组A549细胞施加14%牵张应变，牵张时间为4 h；C组细胞的牵张模式与B组相同，只是于施加牵张前用ERK的特异性抑制剂PD98059预处理A549细胞2h。分别用免疫细胞化学染色和RT-PCR检测细胞HMGB1蛋白和mRNA的表达，用Western blotting检测ERK激酶的活性。 结果 A549细胞施加14 %牵张应变后，HMGB1蛋白和mRNA表达明显增加，ERK激酶活性明显增高（P＜0.05）；该诱导激活作用可被PD98059阻断。 结论 机械牵张通过ERK信号通路，调节A549细胞的HMGB1基因和蛋白表达。

ERK signal is pathway involved in mechanical stretch induced HMGB1 expression in alveolar epithelial cells

Objective To investigate the role of extracellular regulated protein kinase (ERK) signal pathway in mechanical stretch induced high mobility group box 1 protein (HMGB1) expression on alveolar epithelial cells (A549). MethodsA549 cells were cultured and seeded at 1×10⁵ cells/ml in 6-well Bioflex cell culture plates. Subsequently, the cells were exposed to cyclic mechanical stretch at 14% (group B) elongation for 4 hours using Flexercell 4000T cell stretching unit. In group C, cells were pretreated with PD98059 for 2 hours before mechanical stretch. Cells in group A without stretch were served as control. The expression of HMGB1 protein and mRNA in A549 cells were detected by immunocytochemisty staining and RT-PCR, respectively. ERK activity was measured by Western blotting method. Results Immunocytochemisty staining indicated that the expression of HMGB1 protein in A549 cells was increased obviously in group B (P<0.05) and decreased in group C (P<0.05). Polymerase chain reaction (RT-PCR) showed that the expression of HMGB1 mRNA was also significantly increased in group B (P<0.05) and decreased in group C (P<0.05). Western blotting analysis confirmed the activation of ERK in A549 cells by mechanical stretch (P<0.05). PD98059, an inhibitor of ERK, might significantly inhibit mechanical stretch induced HMGB1 protein and mRNA expression in A549 cells (P<0.05). Conclusion Mechanical stretch could regulate the expression of HMGB1 gene and protein in A549 cells through ERK signal pathway.