Guo Mingzhang, Breslin Jerome W, Wu Mack H, Gottardi Cara J, Yuan Sarah Y
Department of Surgery, University of California-Davis School of Medicine, Sacramento, CA 95817, USA.
Am J Physiol Cell Physiol. 2008 Apr;294(4):C977-84. doi: 10.1152/ajpcell.90607.2007. Epub 2008 Feb 20.
Beta-catenin plays an important role in the regulation of vascular endothelial cell-cell adhesions and barrier function by linking the VE-cadherin junction complex to the cytoskeleton. The purpose of this study was to evaluate the effect of beta-catenin and VE-cadherin interactions on endothelial permeability during inflammatory stimulation by histamine. We first assessed the ability of a beta-catenin binding polypeptide known as inhibitor of beta-catenin and T cell factor (ICAT) to compete beta-catenin binding to VE-cadherin in vitro. We then overexpressed recombinant FLAG-ICAT in human umbilical vein endothelial cells (HUVECs) to study its impact on endothelial barrier function controlled by cell-cell adhesions. The binding of beta-catenin to VE-cadherin was quantified before and after stimulation with histamine along with measurements of transendothelial electrical resistance (TER) and apparent permeability to albumin (P(a)) under the same conditions. The results showed that ICAT bound to beta-catenin and competitively inhibited binding of the VE-cadherin cytoplasmic domain to beta-catenin in a concentration-dependent manner. Overexpression of FLAG-ICAT in endothelial cell monolayers did not affect their basal permeability properties, as indicated by unaltered TER and P(a); however, the magnitude and duration of histamine-induced decreases in TER were significantly augmented. Likewise, the increase in P(a) in the presence of histamine was exacerbated. Overexpression of FLAG-ICAT also significantly decreased the level of beta-catenin-associated VE-cadherin following histamine stimulation. Taken together, these data suggest that inflammatory agents like histamine cause a transient and reversible disruption of binding between beta-catenin and VE-cadherin, during which endothelial permeability is elevated.
β-连环蛋白通过将血管内皮钙黏蛋白连接复合体与细胞骨架相连，在调节血管内皮细胞间黏附及屏障功能中发挥重要作用。本研究旨在评估β-连环蛋白与血管内皮钙黏蛋白的相互作用对组胺炎症刺激下内皮通透性的影响。我们首先评估了一种名为β-连环蛋白和T细胞因子抑制剂（ICAT）的β-连环蛋白结合多肽在体外竞争β-连环蛋白与血管内皮钙黏蛋白结合的能力。然后我们在人脐静脉内皮细胞（HUVECs）中过表达重组FLAG-ICAT，以研究其对由细胞间黏附控制的内皮屏障功能的影响。在组胺刺激前后，对β-连环蛋白与血管内皮钙黏蛋白的结合进行定量，并在相同条件下测量跨内皮电阻（TER）和白蛋白表观通透性（P(a)）。结果表明，ICAT与β-连环蛋白结合，并以浓度依赖的方式竞争性抑制血管内皮钙黏蛋白胞质结构域与β-连环蛋白的结合。内皮细胞单层中FLAG-ICAT的过表达并未影响其基础通透性特性，TER和P(a)未改变；然而组胺诱导的TER降低的幅度和持续时间显著增加。同样，组胺存在时P(a)的增加也加剧。FLAG-ICAT的过表达还显著降低了组胺刺激后与β-连环蛋白相关的血管内皮钙黏蛋白水平。综上所述，这些数据表明，组胺等炎症介质会导致β-连环蛋白与血管内皮钙黏蛋白之间的结合发生短暂且可逆的破坏，在此期间内皮通透性升高。
