Tepass U
Department of Molecular Cell Developmental Biology, University of California at Los Angeles, 405 Hilgard Avenue, Los Angeles, California, 90095-1606, USA.
Dev Biol. 1996 Jul 10;177(1):217-25. doi: 10.1006/dbio.1996.0157.
The zonula adherens (ZA) is a cell-cell adherens junction that forms a belt in the apical most region of the lateral cell surface of many epithelia. It is composed of the cadherin-catenin complex and many associated proteins and is connected to a prominent belt of microfilaments. The ZA is believed to play an important role in the differentiation and behavior of epithelial tissues and thus contributes substantially to embryonic morphogenesis. In Drosophila embryos the ZA is formed during and shortly after gastrulation from adherens junction material that appears on the cell surface during cellularization. A ZA is present in a subset of epithelia in the Drosophila embryo called primary epithelia. A second specific marker for primary epithelia is the Crumbs protein, which in concert with the gene product of stardust is required to maintain epithelial polarity. This report shows that both genes are required for the reorganization of adherens junction material into the ZA. Using immunoelectron microscopy it is shown that Crumbs is not a component of the ZA but is distributed over the entire apical cell surface and concentrated in the immediate vicinity of the ZA. These results indicate a rather direct requirement of an apical activity for the organization of the lateral membrane domain in Drosophila primary epithelia. It is proposed that the marginal zone of the apical cell surface contains a crumbs- and stardust-dependent retention mechanism for adherens junction material that aids in the formation of the ZA.
黏着连接带（ZA）是一种细胞间黏着连接，在许多上皮细胞侧面顶端区域形成一条带。它由钙黏蛋白 - 连环蛋白复合体和许多相关蛋白组成，并与一条显著的微丝带相连。ZA被认为在上皮组织的分化和行为中起重要作用，因此对胚胎形态发生有重大贡献。在果蝇胚胎中，ZA在原肠胚形成期间及之后不久，由细胞化过程中出现在细胞表面的黏着连接物质形成。果蝇胚胎中一部分上皮细胞（称为初级上皮细胞）存在ZA。初级上皮细胞的另一个特异性标记是Crb蛋白，它与星尘基因产物协同作用以维持上皮极性。本报告表明，这两个基因对于将黏着连接物质重组为ZA都是必需的。利用免疫电子显微镜显示，Crb不是ZA的组成成分，而是分布在整个顶端细胞表面，并集中在ZA紧邻区域。这些结果表明，果蝇初级上皮细胞中侧面膜结构域的组织对顶端活性有相当直接的需求。有人提出，顶端细胞表面的边缘区域含有一种依赖Crb和星尘的黏着连接物质保留机制，有助于ZA的形成。
