Itoh Masahiko
Department of Biochemistry; Dokkyo Medical University; Tochigi, Japan.
Tissue Barriers. 2013 Apr 1;1(2):e24221. doi: 10.4161/tisb.24221.
Epithelial cells form organized sheets to protect underlying tissues and maintain the physiological environment by the assembly of tight junctions (TJs) and adherens junctions (AJs), which mainly regulate paracellular molecular passage and selective cell-cell adhesion, respectively. At the cytoplasmic surface, TJs and AJs associate with a specific actomyosin cytoskeletal structure called the perijunctional actomyosin ring (PJAR), which encircles cells in a belt-like manner. ZO family proteins play important roles in regulating TJ and PJAR organization. We recently found that ARHGEF11, a member of the RGS-RhoGEF family of proteins, associates with TJs by binding to ZO-1. ARHGEF11 mediates ZO-1-dependent junction assembly and barrier formation in mammary epithelial cells. Another recent study demonstrated that ARHGEF11-dependent apical actomyosin contraction is coupled to planar cell polarity signaling in neuroepithelial cells for the control of neural tube formation. These findings suggest that ARHGEF11 generally regulates apical junctions and junction-associated actomyosin in various epithelial tissues.
上皮细胞通过紧密连接（TJs）和黏附连接（AJs）的组装形成有组织的薄片，以保护下层组织并维持生理环境，紧密连接和黏附连接分别主要调节细胞旁分子通道和选择性细胞间黏附。在细胞质表面，紧密连接和黏附连接与一种称为连接周肌动球蛋白环（PJAR）的特定肌动球蛋白细胞骨架结构相关联，该结构以带状方式环绕细胞。ZO家族蛋白在调节紧密连接和连接周肌动球蛋白环的组织中起重要作用。我们最近发现，RGS-RhoGEF家族蛋白成员ARHGEF11通过与ZO-1结合而与紧密连接相关联。ARHGEF11介导乳腺上皮细胞中依赖于ZO-1的连接组装和屏障形成。另一项最近的研究表明，在神经上皮细胞中，依赖于ARHGEF11的顶端肌动球蛋白收缩与平面细胞极性信号传导相关联，以控制神经管形成。这些发现表明，ARHGEF11通常调节各种上皮组织中的顶端连接和与连接相关的肌动球蛋白。
