Chen W T, Chen J M, Mueller S C
J Cell Biol. 1986 Sep;103(3):1073-90. doi: 10.1083/jcb.103.3.1073.
We have analyzed the expression and distribution of fibronectin, laminin, and the 140K cell adhesion molecules (140K complex) in embryonic chick lung cells by a combination of biochemical and immunofluorescent approaches. The 140K complex was identified by monoclonal antibody JG22E as a complex of glycoproteins averaging 140,000 Mr and has been implicated in vitro as a receptor for fibronectin and laminin. Our studies provide the first description that the 140K complex is developmentally regulated, and that the 140K complex appears to be involved in adhesion of epithelial and endothelial cells during morphogenesis. We have shown that the 140K complex is expressed in high quantity in embryonic lung cell types, but is markedly reduced in all of the differentiated cell types except smooth muscle. Embryonic lung cells are enriched in 140K complex on portions of cells in close proximity to areas rich in fibronectin. For example, during the formation of airways and alveolar tissues, 140K complex is concentrated at the basal surfaces of epithelial cells adjacent to fibronectin. Likewise, during the angiogenic invasion of capillaries into lung mesenchyme, the 140K complex becomes localized at sites on the basal surfaces of endothelial cells in close contact with fibronectin. Finally, cytodifferentiating lung smooth muscle cells show unusually high levels of 140K complex, fibronectin, and laminin that persist into the adult. In contrast to fibronectin, laminin is found to be uniformly distributed in the basement membranes of differentiating epithelial cells. It becomes prominent in adult alveolar epithelium and airway epithelium concomitant with a reduction or loss of 140K complex and fibronectin at cell-basement membrane attachment sites. Surprisingly, laminin is also present in a punctate pattern in the mesenchyme of early lung buds, however, laminin, fibronectin, and 140K complex are greatly reduced or lost during mesenchymal maturation. Our results are consistent with the active participation of the 140K complex in cell-to-matrix adhesion during morphogenesis of alveolar walls and cytodifferentiation of mesenchymal and smooth muscle cells.
我们通过生化和免疫荧光相结合的方法，分析了胚胎鸡肺细胞中纤连蛋白、层粘连蛋白和140K细胞黏附分子（140K复合物）的表达及分布情况。单克隆抗体JG22E将140K复合物鉴定为一种平均分子量为140,000的糖蛋白复合物，在体外被认为是纤连蛋白和层粘连蛋白的受体。我们的研究首次描述了140K复合物受发育调控，并且在形态发生过程中，140K复合物似乎参与上皮细胞和内皮细胞的黏附。我们发现，140K复合物在胚胎肺细胞类型中大量表达，但在除平滑肌外的所有分化细胞类型中显著减少。胚胎肺细胞在靠近富含纤连蛋白区域的细胞部分富含140K复合物。例如，在气道和肺泡组织形成过程中，140K复合物集中在上皮细胞与纤连蛋白相邻的基底表面。同样，在毛细血管向肺间充质的血管生成性侵入过程中，140K复合物定位于内皮细胞基底表面与纤连蛋白紧密接触的部位。最后，正在进行细胞分化的肺平滑肌细胞显示出异常高水平的140K复合物、纤连蛋白和层粘连蛋白，这些物质一直持续到成年期。与纤连蛋白不同，层粘连蛋白在分化的上皮细胞基底膜中均匀分布。在成年肺泡上皮和气道上皮中，随着140K复合物和纤连蛋白在细胞 - 基底膜附着位点的减少或丧失，层粘连蛋白变得突出。令人惊讶的是，层粘连蛋白在早期肺芽的间充质中也呈点状分布，然而，在间充质成熟过程中，层粘连蛋白、纤连蛋白和140K复合物大量减少或消失。我们的结果与140K复合物在肺泡壁形态发生以及间充质和平滑肌细胞的细胞分化过程中积极参与细胞与基质黏附的情况一致。
