Ikeda W, Nakanishi H, Miyoshi J, Mandai K, Ishizaki H, Tanaka M, Togawa A, Takahashi K, Nishioka H, Yoshida H, Mizoguchi A, Nishikawa S, Takai Y
Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Osaka 565-0871, Japan.
J Cell Biol. 1999 Sep 6;146(5):1117-32. doi: 10.1083/jcb.146.5.1117.
Afadin is an actin filament-binding protein that binds to nectin, an immunoglobulin-like cell adhesion molecule, and is colocalized with nectin at cadherin-based cell-cell adherens junctions (AJs). To explore the function of afadin in cell-cell adhesion during embryogenesis, we generated afadin(-/-) mice and embryonic stem cells. In wild-type mice at embryonic days 6.5-8.5, afadin was highly expressed in the embryonic ectoderm and the mesoderm, but hardly detected in the extraembryonic regions such as the visceral endoderm. Afadin(-/-) mice showed developmental defects at stages during and after gastrulation, including disorganization of the ectoderm, impaired migration of the mesoderm, and loss of somites and other structures derived from both the ectoderm and the mesoderm. Cystic embryoid bodies derived from afadin(-/-) embryonic stem cells showed normal organization of the endoderm but disorganization of the ectoderm. Cell-cell AJs and tight junctions were improperly organized in the ectoderm of afadin(-/-) mice and embryoid bodies. These results indicate that afadin is highly expressed in the ectoderm- derived cells during embryogenesis and plays a key role in proper organization of AJs and tight junctions of the highly expressing cells, which is essential for proper tissue morphogenesis.
Afadin是一种肌动蛋白丝结合蛋白，它与免疫球蛋白样细胞粘附分子nectin结合，并与nectin共定位于基于钙粘蛋白的细胞间粘附连接（AJs）处。为了探究afadin在胚胎发育过程中细胞间粘附的功能，我们构建了afadin基因敲除（-/-）小鼠和胚胎干细胞。在胚胎期6.5 - 8.5天的野生型小鼠中，afadin在胚胎外胚层和中胚层中高表达，但在内脏内胚层等胚外区域几乎检测不到。Afadin基因敲除小鼠在原肠胚形成期间及之后的阶段出现发育缺陷，包括外胚层紊乱、中胚层迁移受损以及体节和其他源自外胚层和中胚层的结构缺失。源自afadin基因敲除胚胎干细胞的囊性胚状体显示内胚层组织正常，但外胚层紊乱。在afadin基因敲除小鼠和胚状体的外胚层中，细胞间AJs和紧密连接组织不当。这些结果表明，afadin在胚胎发育过程中在外胚层来源的细胞中高表达，并且在高表达细胞的AJs和紧密连接的正确组织中起关键作用，这对于正确的组织形态发生至关重要。
