Steinberg's differential adhesion hypothesis suggests that adhesive mechanisms are important for sorting of cells and tissues during morphogenesis (Steinberg, 2007). During zebrafish vasculogenesis, endothelial cells sort into arterial and venous vessel beds but it is unknown whether this involves adhesive mechanisms. Claudins are tight junction proteins regulating the permeability of epithelial and endothelial tissue barriers. Previously, the roles of claudins during organ development have exclusively been related to their canonical functions in determining paracellular permeability. Here, we use atomic force microscopy to quantify claudin-5-dependent adhesion and find that this strongly contributes to the adhesive forces between arterial endothelial cells. Based on genetic manipulations, we reveal a non-canonical role of Claudin-5a during zebrafish vasculogenesis, which involves the regulation of adhesive forces between adjacent dorsal aortic endothelial cells. In vitro and in vivo studies demonstrate that loss of claudin-5 results in increased motility of dorsal aorta endothelial cells and in a failure of the dorsal aorta to lumenize. Our findings uncover a novel role of claudin-5 in limiting arterial endothelial cell motility, which goes beyond its traditional sealing function during embryonic development.

斯坦伯格的差异粘附假说表明，粘附机制对于形态发生过程中细胞和组织的分类非常重要。斯坦伯格，2007）。在斑马鱼血管发生过程中，内皮细胞分类成动脉和静脉血管床，但尚不清楚这是否涉及粘附机制。紧密连接蛋白是调节上皮和内皮组织屏障通透性的紧密连接蛋白。此前，紧密蛋白在器官发育过程中的作用完全与其在确定细胞旁通透性方面的典型功能有关。在这里，我们使用原子力显微镜来量化claudin-5依赖性粘附，并发现这对动脉内皮细胞之间的粘附力有很大贡献。基于基因操作，我们揭示了 Claudin-5a 在斑马鱼血管发生过程中的非典型作用，其中涉及相邻背主动脉内皮细胞之间粘附力的调节。体外和体内研究表明，claudin-5 的缺失会导致背主动脉内皮细胞的运动性增加以及背主动脉无法内腔化。我们的研究结果揭示了claudin-5在限制动脉内皮细胞运动方面的新作用，这超出了其在胚胎发育过程中的传统密封功能。