Kiener Tanja K, Selptsova-Friedrich Inna, Hunziker Walter
Epithelial Cell Biology Laboratory, Institute of Molecular and Cell Biology, A*STAR (Agency for Science Technology and Research), Singapore 138673, Singapore.
Dev Biol. 2008 Apr 1;316(1):36-49. doi: 10.1016/j.ydbio.2007.12.047. Epub 2008 Jan 26.
TJP3/ZO-3 is a scaffolding protein that tethers tight junction integral membrane proteins to the actin cytoskeleton and links the conserved Crumbs polarity complex to tight junctions. The physiological function of TJP3/ZO-3 is not known and mice lacking TJP3/ZO-3 show no apparent phenotype. Here we show that Tjp3/Zo-3 is a component of tight junctions present in the enveloping cell layer of zebrafish embryos. Silencing tjp3/zo-3 using morpholinos leads to edema, loss of blood circulation and tail fin malformations in the embryos. The ultrastructure of tight junctions of the enveloping cell layer is disrupted, without affecting the asymmetric distribution of plasma membrane proteins. Morphants show a loss of the epidermal barrier, as assessed by an increased permeability of the enveloping cell layer to low molecular weight tracers and a higher sensitivity of the embryos to osmotic stress. Subjecting wild-type embryos to osmotic stress mimicks the morphant phenotype, consistent with the phenotype being a direct consequence of failed osmoregulation. Thus, Tjp3/Zo-3 is critical for barrier function of the enveloping cell layer and osmoregulation in early stages of zebrafish development.
TJP3/ZO - 3是一种支架蛋白，它将紧密连接整合膜蛋白与肌动蛋白细胞骨架相连，并将保守的Crumbspolarity复合体与紧密连接相连接。TJP3/ZO - 3的生理功能尚不清楚，缺乏TJP3/ZO - 3的小鼠没有明显的表型。在这里，我们表明Tjp3/Zo - 3是斑马鱼胚胎包被细胞层中紧密连接的一个组成部分。使用吗啉代寡核苷酸沉默tjp3/zo - 3会导致胚胎出现水肿、血液循环丧失和尾鳍畸形。包被细胞层紧密连接的超微结构被破坏，但不影响质膜蛋白的不对称分布。通过包被细胞层对低分子量示踪剂的通透性增加以及胚胎对渗透应激的更高敏感性评估，突变体显示出表皮屏障的丧失。使野生型胚胎遭受渗透应激会模拟突变体表型，这与该表型是渗透调节失败的直接后果一致。因此，Tjp3/Zo - 3对于斑马鱼发育早期包被细胞层的屏障功能和渗透调节至关重要。
