Lohmann Christina, Krischke Miriam, Wegener Joachim, Galla Hans Joachim
Institut fuer Biochemie, Westfaelische Wilhelms-Universitaet Muenster, Wilhelm-Klemm-Str. 2, 48149, Münster, Germany.
Brain Res. 2004 Jan 9;995(2):184-96. doi: 10.1016/j.brainres.2003.10.002.
Tight junctions between endothelial cells of brain capillaries form the structural basis of the blood-brain barrier (BBB), which controls the exchange of molecules between blood and CNS. Regulation of cellular barrier permeability is a vital and complex process involving intracellular signalling and rearrangement of tight junction proteins. We have analysed the impact of tyrosine phosphatase inhibition on tight junction proteins and endothelial barrier integrity in a primary cell culture model based on porcine brain capillary endothelial cells (PBCEC) that closely mimics the BBB in vitro. The tyrosine phosphatase inhibitor phenylarsine oxide (PAO) induced increased matrix metalloproteinase (MMP) activity, which was paralleled by severe disruption of cell-cell contacts and proteolysis of the tight junction protein occludin. ZO-1 and claudin-5 were not affected. Under these conditions, the transendothelial electrical resistance (TEER) was markedly reduced. PAO-induced occludin proteolysis could be prevented by different MMP inhibitors. Pervanadate (PV) reduced the TEER similar to PAO, but did not increase MMP activity. Cell-cell contacts of PV-treated cells appeared unaffected, and occludin proteolysis did not occur. Our results suggest that tyrosine phosphatase inhibition can influence barrier properties independent of, but also correlated to MMPs. Evidence is given for a role of MMPs in endothelial tight junction regulation at the BBB in particular and probably at tight junctions (TJs) in general.
脑毛细血管内皮细胞之间的紧密连接构成了血脑屏障（BBB）的结构基础，血脑屏障控制着血液与中枢神经系统之间分子的交换。细胞屏障通透性的调节是一个至关重要且复杂的过程，涉及细胞内信号传导和紧密连接蛋白的重排。我们在一个基于猪脑毛细血管内皮细胞（PBCEC）的原代细胞培养模型中分析了酪氨酸磷酸酶抑制对紧密连接蛋白和内皮屏障完整性的影响，该模型在体外紧密模拟血脑屏障。酪氨酸磷酸酶抑制剂氧化苯胂（PAO）诱导基质金属蛋白酶（MMP）活性增加，同时伴有细胞间接触的严重破坏和紧密连接蛋白occludin的蛋白水解。ZO-1和claudin-5不受影响。在这些条件下，跨内皮电阻（TEER）显著降低。不同的MMP抑制剂可预防PAO诱导的occludin蛋白水解。过氧钒酸盐（PV）降低TEER的作用与PAO相似，但不会增加MMP活性。PV处理细胞的细胞间接触似乎未受影响，且未发生occludin蛋白水解。我们的结果表明，酪氨酸磷酸酶抑制可独立于MMPs但又与之相关地影响屏障特性。有证据表明MMPs在血脑屏障的内皮紧密连接调节中起作用，特别是在一般的紧密连接（TJ）中可能也起作用。
