The cytoskeleton and substratum adhesion in chick embryonic corneal epithelial cells.
The cytoskeleton and substratum adhesion in chick embryonic corneal epithelial cells.
复制标题
鸡胚角膜上皮细胞的细胞骨架和基质粘附。
作者：
D. Billig;A. Nicol;R. McGinty;P. Cowin;J. Morgan;D. Garrod
用干涉反射显微镜(IRM)、电子显微镜和抗肌动蛋白、微管蛋白、角蛋白前、纤维连接蛋白和层粘连蛋白的特异性抗体对15日龄鸡胚角膜上皮细胞的黏附和细胞骨架进行了研究。细胞间连接以桥粒为主，半桥粒在与基底膜接触的上皮基面突出。完整的上皮细胞表达肌动蛋白、微管蛋白、前角蛋白和层粘连蛋白，但不表达纤维连接蛋白，基底膜表达纤维连接蛋白和层粘连蛋白。在单层培养中，经胰酶解离后，细胞间桥粒重新形成。然而，我们主要集中在细胞-基质黏附，因为对于上皮细胞，基质黏附和细胞骨架之间的关系还没有得到彻底的研究。我们的大多数结果适用于与明胶基质的接触，但在玻璃或组织培养塑料上的情况类似。IRM显示与成纤维细胞相似的局灶性接触，主要位于单层岛外周细胞的前导板下方。荧光抗体染色显示，每个焦点接触位于肌动蛋白微丝束的末端。然而，焦性接触与前角蛋白细丝或微管之间没有对应关系。纤维连接蛋白纤维主要分布在外周细胞下，但有证据表明纤维连接蛋白并不直接参与这些细胞的细胞-基质黏附。我们认为纤维连接蛋白模式的产生是因为细胞物理上重组了纤维连接蛋白，纤维连接蛋白从培养液中吸附或结合到基质上。电子显微镜显示，这些细胞与底物形成两种类型的接触：除了局灶性接触外，还存在小而致密的斑块状结构，可能是半嵌合体。前者与张力细丝有关，与体内发现的桥粒和半桥粒大小相同(直径约为O-I纤维)。它们比焦距接触器小得多，后者的长度从一微米到几微米。这些结构没有体内发现的半桥粒形成得那么好，可能是因为底物不完全合适。讨论了这两种细胞-基质粘连的意义。
The adhesions and cytoskeleton of 15-day chick embryonic comeal epithelial cells have been studied using interference reflection microscopy (IRM), electron microscopy and fluorescent staining with specific antibodies against actin, tubulin, prekeratin, fibronectin and laminin In vivo, desmosomes were the most frequent intercellular junctions and hemidesmosomes were prominent at the basal surface of the epithelium in contact with the basement membrane. The intact epithelium stained for actin, tubulin, and prekeratin and laminin, but not fibronectin, and the basement membrane for fibronectin and laminin. In monolayer culture intercellular desmosomes were reformed after dissociation with trypsin. However, we have concentrated on cell-substratum adhesions, because the relationship between substratum adhesions and the cytoskeleton has not been thoroughly investigated for epithelial cells. Most of our results apply to contacts with gelatin substrata but the situation was similar on glass or tissue-culture plastic. By IRM, focal contacts similar to those of fibroblasts were present, mainly beneath the leading lamellae of the peripheral cells of monolayered islands. Fluorescent antibody staining revealed that each focal contact was positioned at the end of an actin microfilament bundle. However, there was no correspondence between focal contacts and either prekeratin filaments or microtubules. Fibronectin fibrils were found principally beneath peripheral cells, but evidence is presented suggesting that fibronectin is not directly involved in cell-substratum adhesion of these cells. We suggest that the fibrillar fibronectin pattern arises because cells physically reorganize fibronectin which adsorbs or binds to the substratum from the medium. Electron microscopy suggested that these cells formed two types of contacts with the substratum : small dense plaque-like structures, probably hemidesmosomes, were present in addition to focal contacts. The former were associated with tonofilaments and were the same size (about o-i fim in diameter) as the desmosomes and hemidesmosomes found in vivo. They were much smaller than focal contacts which were from one to several micrometers in length. These structures were not as well formed as the hemidesmosomes found in vivo, possibly because the substratum was not entirely appropriate. The significance of the two types of cell-substratum adhesions is discussed.