Fischer S, Wobben M, Marti H H, Renz D, Schaper W
Kerckhoff-Clinic, 61231 Bad Nauheim, Germany.
Microvasc Res. 2002 Jan;63(1):70-80. doi: 10.1006/mvre.2001.2367.
In vivo, hypoxia is known to damage the blood-brain barrier (BBB) leading to the development of vasogenic brain edema. Primary cultures of porcine brain derived microvascular endothelial cells were used as an in vitro BBB model to evaluate the mechanisms by which hypoxia regulates paracellular permeability. Paracellular passage across endothelial cell monolayers is regulated by specialized intercellular structures like the tight junctions (TJ). Zonula occludens-1 (ZO-1), a protein of the TJ, lines the cytoplasmic face of intact TJ. The continuity of the ZO-1 expression was disrupted during 24 h of hypoxia which correlated with a decrease of the protein level to 32 +/- 8% and with a twofold increase in the phosphorylation of ZO-1 in comparison to values determined at the start of the experiment. The localization and expression level of ZO-1 were maintained during hypoxia in the presence of a polyclonal antibody to vascular endothelial growth factor (VEGF) demonstrating that hypoxia-induced changes of the ZO-1 expression are mediated by VEGF. The effect of hypoxia on the ZO-1 distribution probably is not tissue- or cell-specific because similar changes of ZO-1 distribution were observed when the rat brain endothelial cell line RBE4 or the murine epithelial cell line CSG was used. Furthermore, ZO-1 changes correlated with small changes in actin distribution. These results suggest that hypoxia increases the paracellular flux across the cell monolayer via the release of VEGF, which in turn leads to the dislocalization, decreased expression, and enhanced phosphorylation of ZO-1. Science.
在体内,已知缺氧会损害血脑屏障(BBB),导致血管源性脑水肿的发展。猪脑微血管内皮细胞的原代培养物被用作体外血脑屏障模型,以评估缺氧调节细胞旁通透性的机制。跨内皮细胞单层的细胞旁通道由紧密连接(TJ)等特殊的细胞间结构调节。紧密连接蛋白1(ZO-1)是TJ的一种蛋白质,排列在完整TJ的细胞质面上。在缺氧24小时期间,ZO-1表达的连续性被破坏,这与蛋白质水平降至32±8%相关,并且与实验开始时测定的值相比,ZO-1的磷酸化增加了两倍。在存在血管内皮生长因子(VEGF)多克隆抗体的情况下,缺氧期间ZO-1的定位和表达水平得以维持,这表明缺氧诱导的ZO-1表达变化是由VEGF介导的。缺氧对ZO-1分布的影响可能不是组织或细胞特异性的,因为当使用大鼠脑内皮细胞系RBE4或小鼠上皮细胞系CSG时,观察到了类似的ZO-1分布变化。此外,ZO-1的变化与肌动蛋白分布的微小变化相关。这些结果表明,缺氧通过释放VEGF增加了跨细胞单层的细胞旁通量,这反过来又导致ZO-1的错位、表达降低和磷酸化增强。《科学》