Department of Neurobiology, College of Basic Medicine, China Medical University, Shenyang, Liaoning Province, People's Republic of China, 110001.
J Mol Neurosci. 2012 Mar;46(3):666-76. doi: 10.1007/s12031-011-9564-9. Epub 2011 Jun 7.
The purpose of the present study was to determine the potential for RhoA/ROCK signaling to play a role in endothelial-monocyte-activating polypeptide (EMAP) II-induced increase in blood-tumor barrier (BTB) permeability in rat brain microvascular endothelial cells (RBMECs). In the present study, we used an in vitro BTB model, a RhoA inhibitor (C3 exoenzyme) and a ROCK inhibitor (Y27632) to determine whether RhoA/ROCK pathway play a role in the process of TJ disassembly, stress fiber formation, MLC and cofilin phosphorylation, as well as increase of BTB permeability induced by EMAP II. The results revealed that BTB permeability was increased by EMAP II induction, and C3 exoenzyme or Y27632 could partially inhibit the EMAP II-induced increase of BTB permeability. The significant down-regulations in tight junction (TJ)-associated proteins occludin, claudin-5 and ZO-1 and stress fiber formation by EMAP II administration were observed, which were partly prevented by C3 exoenzyme or Y27632 pretreatment. Moreover, the significant increases in RhoA activity, myosin light chain (MLC) and cofilin phosphorylation by EMAP II administration were observed, MLC and cofilin phosphorylation were partly inhibited by C3 exoenzyme or Y27632 pretreatment. The present study demonstrates that the activation of RhoA/ROCK signaling in RBMECs was required for the increase of BTB permeability and these effects are related with the ability for RhoA/ROCK to mediate TJ disassembly and stress fiber formation by phosphorylating cofilin and MLC.
本研究旨在探讨 RhoA/ROCK 信号通路在内皮细胞激活肽 II（EMAP II）诱导血脑屏障（BTB）通透性增加中的作用。本研究采用体外 BTB 模型、RhoA 抑制剂（C3 外毒素）和 ROCK 抑制剂（Y27632），观察 RhoA/ROCK 通路在 TJ 解聚、应力纤维形成、MLC 和丝切蛋白磷酸化以及 EMAP II 诱导的 BTB 通透性增加中的作用。结果表明，EMAP II 诱导增加了 BTB 通透性，C3 外毒素或 Y27632 可部分抑制 EMAP II 诱导的 BTB 通透性增加。EMAP II 处理导致紧密连接（TJ）相关蛋白 occludin、claudin-5 和 ZO-1 表达下调和应力纤维形成，C3 外毒素或 Y27632 预处理可部分预防这些变化。此外，EMAP II 处理导致 RhoA 活性、肌球蛋白轻链（MLC）和丝切蛋白磷酸化显著增加，C3 外毒素或 Y27632 预处理可部分抑制 MLC 和丝切蛋白磷酸化。本研究表明，RBMECs 中 RhoA/ROCK 信号的激活是增加 BTB 通透性所必需的，这些作用与 RhoA/ROCK 通过磷酸化丝切蛋白和 MLC 介导 TJ 解聚和应力纤维形成的能力有关。
