Yano Tomoki, Kanoh Hatsuho, Tamura Atsushi, Tsukita Sachiko
Laboratory of Biological Science, Graduate School of Frontier Biosciences and Graduate School of Medicine, Osaka University, Osaka, Japan.
Graduate School of Biostudies, Kyoto University, Kyoto, Japan.
Ann N Y Acad Sci. 2017 Oct;1405(1):32-43. doi: 10.1111/nyas.13432. Epub 2017 Aug 1.
Epithelial cell sheet formation is central to many aspects of vertebrate development and function. For example, it is a major principle of differentiation in embryogenesis and regeneration, enables the compartmentalization of tissues, and is the basis for the maintenance of homeostasis throughout the body. A key characteristic of biologically functional epithelial cell sheets is a clear difference between the top and bottom sides owing to the apicobasal polarity of the cells in the sheet, as seen in the simple polar epithelia. Epithelial cell sheets are formed by cell-cell adhesion conferred by junctional complexes, in particular via tight junctions (TJs), which thus create a paracellular barrier. This review focuses on the apical side of the sheet, which serves as the front line. The apical membranes and TJs of the various tissues have specific characteristics that enable them to function and adapt to their biological context: each system must be robust, but also dynamic and flexible to maintain homeostasis. Here, we describe various apical cytoskeletal structures that are critical to the integrity of epithelial cell sheets. We also discuss the association of apical cytoskeletal networks with TJs, which thus forms a combined system, tentatively termed the TJ-apical complex.
上皮细胞片层的形成是脊椎动物发育和功能诸多方面的核心。例如，它是胚胎发生和再生过程中分化的主要原则，使组织能够进行分隔，并且是维持全身内环境稳态的基础。具有生物学功能的上皮细胞片层的一个关键特征是，由于片层中细胞的顶-基极性，其顶面和底面存在明显差异，这在简单极性上皮中可见。上皮细胞片层由连接复合体赋予的细胞-细胞黏附形成，特别是通过紧密连接（TJ），从而形成细胞旁屏障。本综述聚焦于片层的顶面，它起着前沿防线的作用。各种组织的顶膜和紧密连接具有特定特征，使其能够发挥功能并适应其生物学环境：每个系统都必须稳健，但也需要动态灵活以维持内环境稳态。在这里，我们描述了对上皮细胞片层完整性至关重要的各种顶端细胞骨架结构。我们还讨论了顶端细胞骨架网络与紧密连接的关联，由此形成了一个组合系统，暂称为紧密连接-顶端复合体。
