Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Florida, Gainesville, Florida; and North Florida/South Georgia Veterans Health Care System, Malcom Randall Veterans Affairs Medical Center, University of Florida, Gainesville, Florida.
Division of Pulmonary, Critical Care and Sleep Medicine, Department of Medicine, University of Florida, Gainesville, Florida; and North Florida/South Georgia Veterans Health Care System, Malcom Randall Veterans Affairs Medical Center, University of Florida, Gainesville, Florida
Am J Physiol Cell Physiol. 2014 Jun 15;306(12):C1154-66. doi: 10.1152/ajpcell.00415.2012. Epub 2014 Apr 9.
Erythropoietin-producing human hepatocellular carcinoma (Eph) receptors are the largest family of receptor tyrosine kinases (RTKs) that mediate various cellular and developmental processes. The degrees of expression of these key molecules control the cell-cell interactions. Although the role of Eph receptors and their ligand Ephrins is well studied in developmental processes, their function in tobacco smoke (TS)-induced epithelial barrier dysfunction is unknown. We hypothesized that TS may induce permeability in bronchial airway epithelial cell (BAEpC) monolayer by modulating receptor EphA2 expression, actin cytoskeleton, adherens junction, and focal adhesion proteins. Here we report that in BAEpCs, acute TS exposure significantly upregulated EphA2 and EphrinA1 expression, disrupted the actin filaments, decreased E-cadherin expression, and increased protein permeability, whereas the focal adhesion protein paxillin was unaffected. Silencing the receptor EphA2 expression with silencing interference RNA (siRNA) significantly attenuated TS-induced hyperpermeability in BAEpCs. In addition, when BAEpC monolayer was transfected with EphA2-expressing plasmid and treated with recombinant EphrinA1, the transepithelial electrical resistance decreased significantly. Furthermore, TS downregulated E-cadherin expression and induced hyperpermeability across BAEpC monolayer in a Erk1/Erk2, p38, and JNK MAPK-dependent manner. TS induced hyperpermeability in BAEpC monolayer by targeting cell-cell adhesions, and interestingly cell-matrix adhesions were unaffected. The present data suggest that TS causes significant damage to the BAEpCs via induction of EphA2 and downregulation of E-cadherin. Induction of EphA2 in the BAEpCs exposed to TS may be an important signaling event in the pathogenesis of TS-induced epithelial injury.
促红细胞生成素产生的人肝细胞癌 (Eph) 受体是最大的受体酪氨酸激酶 (RTKs) 家族，可介导各种细胞和发育过程。这些关键分子的表达程度控制着细胞间的相互作用。虽然 Eph 受体及其配体 Ephrins 在发育过程中的作用得到了很好的研究，但它们在烟草烟雾 (TS) 诱导的上皮屏障功能障碍中的作用尚不清楚。我们假设，TS 可能通过调节受体 EphA2 表达、肌动蛋白细胞骨架、黏着连接和黏着斑蛋白，诱导支气管气道上皮细胞 (BAEpC) 单层通透性。在这里，我们报告在 BAEpCs 中，急性 TS 暴露显著上调 EphA2 和 EphrinA1 的表达，破坏肌动蛋白丝，降低 E-钙黏蛋白的表达，增加蛋白通透性，而黏着斑蛋白 paxillin 不受影响。用沉默干扰 RNA (siRNA) 沉默受体 EphA2 表达显著减弱了 TS 诱导的 BAEpCs 高通透性。此外，当 BAEpC 单层转染 EphA2 表达质粒并给予重组 EphrinA1 处理时，跨上皮电阻显著降低。此外，TS 通过 Erk1/Erk2、p38 和 JNK MAPK 依赖性方式下调 E-钙黏蛋白的表达并诱导 BAEpC 单层的高通透性。TS 通过靶向细胞-细胞黏附引起 BAEpC 单层的高通透性，有趣的是细胞-基质黏附不受影响。本研究数据表明，TS 通过诱导 EphA2 和下调 E-钙黏蛋白对 BAEpCs 造成显著损伤。暴露于 TS 的 BAEpCs 中 EphA2 的诱导可能是 TS 诱导的上皮损伤发病机制中的一个重要信号事件。
