Department of Developmental Biology, Key Laboratory of Cell Biology, Ministry of Public Health and Key Laboratory of Medical Cell Biology, Ministry of Education, China Medical University,92 Bei Er Road, Heping District, Shenyang 110001, China.
Microvasc Res. 2011 Sep;82(2):113-21. doi: 10.1016/j.mvr.2011.06.005. Epub 2011 Jun 25.
Eph receptor tyrosine kinases and ephrin ligands participate in the regulation of a wide variety of biological processes, such as axon guidance, synaptic plasticity, angiogenesis, and tumorigenesis. The role of Eph receptors and ephrin ligands in brain endothelial cells remains unknown. Here, we examined the expression profile of EphA receptors and ephrin-A ligands in human brain microvascular endothelial cell line (HBMEC). Our results showed that multiple EphA receptors and ephrin-A ligands are expressed in HBMEC. We found that the phosphorylation of EphA2, but not other EphA receptors, was significantly increased in HBMEC treated with recombinant ephrin-A1/Fc. Meanwhile, elevated EphA2 phosphorylation was accompanied by disassembly of tight junctions in HBMEC. Furthermore, EphA2 RNAi in HBMEC could promote tight junction formation and prevent the ephrin-A1-induced tight junction disruption. Also, when a kinase-inactive mutant of EphA2 (EphA2-K646M) was expressed in HBMEC, the tight junction was enhanced and the ephrin-A1-induced tight junction disruption was blocked. In addition, EphA2 RNAi and expression of EphA2-K646M in HBMEC inhibited in vitro cell migration and angiogenesis of HBMEC. These data indicated an important role of EphA2 in regulating both tight junction formation and angiogenesis in brain endothelial cells.
Eph 受体酪氨酸激酶和 Ephrin 配体参与调节多种生物学过程，如轴突导向、突触可塑性、血管生成和肿瘤发生。Eph 受体和 Ephrin 配体在脑内皮细胞中的作用尚不清楚。在这里，我们检查了 EphA 受体和 Ephrin-A 配体在人脑微血管内皮细胞系 (HBMEC) 中的表达谱。我们的结果表明，多种 EphA 受体和 Ephrin-A 配体在 HBMEC 中表达。我们发现 Ephrin-A1/Fc 处理 HBMEC 可显著增加 EphA2 的磷酸化，但其他 EphA 受体则不然。同时，EphA2 磷酸化的升高伴随着 HBMEC 中紧密连接的解体。此外，EphA2 RNAi 在 HBMEC 中可促进紧密连接的形成，并防止 Ephrin-A1 诱导的紧密连接破坏。此外，当 EphA2 的激酶失活突变体 (EphA2-K646M) 在 HBMEC 中表达时，紧密连接增强，Ephrin-A1 诱导的紧密连接破坏被阻断。此外，EphA2 RNAi 和 EphA2-K646M 在 HBMEC 中的表达抑制了 HBMEC 的体外细胞迁移和血管生成。这些数据表明 EphA2 在调节脑内皮细胞中紧密连接形成和血管生成方面具有重要作用。
