Tepass U, Gruszynski-DeFeo E, Haag T A, Omatyar L, Török T, Hartenstein V
Department of Molecular Cellular Developmental Biology, University of California at Los Angeles, 90024-1606, USA.
Genes Dev. 1996 Mar 15;10(6):672-85. doi: 10.1101/gad.10.6.672.
Adhesion molecules of the cadherin superfamily have an important role during vertebrate development. The DE-cadherin homolog DE-cadherin is the first classic cadherin isolated from invertebrates. We report here that DE-cadherin is encoded by the shotgun (shg) gene. shg is expressed in most embryonic epithelia and decreases in cells that undergo epithelial-mesenchymal transitions like the mesoderm or neural precursors. Removal of both maternal and zygotic shg function leads to severe defects in all epithelia expressing shg, suggesting that DE-cadherin, similar to vertebrate classic cadherins, has a crucial role for the formation and/or maintenance of epithelial tissues. Interestingly, the analysis of different shg alleles indicates that the requirement for shg in a given epithelium depends on the degree of its morphogenetic activity. Only epithelia involved in extensive morphogenetic movements require zygotic shg function in addition to maternal expression. In support of this view we find that suppression of morphogenetic movements rescues the zygotic shg phenotype. We find that in zygotic shg nulls the level of Dalpha-catenin and Armadillo at adherens junctions is dramatically reduced, surprisingly also in epithelia that differentiate normally and possess a zonula adherens.
钙黏蛋白超家族的黏附分子在脊椎动物发育过程中发挥着重要作用。DE-钙黏蛋白同源物DE-钙黏蛋白是首个从无脊椎动物中分离出的经典钙黏蛋白。我们在此报告，DE-钙黏蛋白由散弹枪（shg）基因编码。shg在大多数胚胎上皮中表达，并在经历上皮-间充质转化的细胞（如中胚层或神经前体）中减少。去除母源和合子源的shg功能会导致所有表达shg的上皮出现严重缺陷，这表明DE-钙黏蛋白与脊椎动物经典钙黏蛋白类似，对上皮组织的形成和/或维持具有关键作用。有趣的是，对不同shg等位基因的分析表明，给定上皮中对shg的需求取决于其形态发生活性的程度。只有参与广泛形态发生运动的上皮除了母源表达外还需要合子源的shg功能。支持这一观点的是，我们发现抑制形态发生运动会挽救合子源shg的表型。我们发现，在合子源shg缺失的情况下，黏着连接处的Dα-连环蛋白和犰狳蛋白水平显著降低，令人惊讶的是，在正常分化且具有黏着小带的上皮中也是如此。
