MOLECULAR ULTRASTRUCTURE UNDERLYING CELL ADHESION

细胞与细胞外物质的粘附相互作用是至关重要的 胚胎发生和癌细胞侵袭过程中的重要事件。 无论是粘附位点的分子组成，还是粘附分子的功能， 与细胞粘附相关的分子是目前已知的。 我们打算 以获得关于膜的分子解剖和功能的信息， 正常和病毒转化细胞中的附着位点，并测试 假设细胞粘附是细胞间特异性相互作用的结果， 跨膜糖蛋白及其外周细胞内和细胞外 件. 一种新的体外模型， 交联明胶基质将用于形态学、化学和 粘连的功能测定。 这项工作的目标是确定这些跨膜相互作用， 正常和病毒转化细胞，以评估其功能 重要性，并找出参与粘附的新分子。 到 为了实现这些目标，我们采用了针对纯化的 细胞表面蛋白作为双免疫标记探针，以阐明 超薄冰冻切片对粘连部位的分子解剖学和病理学研究 切片方法，然后使用这些纯化的蛋白质来确定它们的 体外结合特异性。 其他更注重功能的研究将 评估这些分子关联的重要性。 我们展示了 与纤连蛋白共定位的140千道尔顿膜粘附复合物 和α-辅肌动蛋白。 单克隆抗体 JG 22 E，直接针对140千道尔顿复合物，抑制附着和 正常细胞和转化细胞均铺展到纤连蛋白基质上。 然而，我们发现， 转化相关蛋白酶，降解细胞内的纤连蛋白 接触部位。 我们检查了超微结构定位，底物， 以及蛋白酶在入侵中的作用的抑制剂特异性 转化成细胞外基质。 我们还将继续 使用新的单克隆抗体鉴定其他跨膜蛋白 和免疫电镜。 （一）

Adhesive interactions of cells with extracellular materials are critically important events during embryogenesis and invasion by cancer cells. Neither the molecular composition of adhesion sites nor the function of molecules associated with cell adhesion is presently understood. We intend to obtain information on the molecular anatomy and function of the membrane attachment sites in normal and virally transformed cells and to test the hypothesis that cell adhesion is a result of specific interactions between transmembrane glycoproteins and their peripheral intra-\and extracellular components. A novel in vitro model involving cells cultured on planar, crosslinked gelatin substrata will be used for morphological, chemical, and functional assays of adhesions. The goals of this work are to define these transmembrane interactions in normal and virally transformed cells, to evaluate their functional significance, and to ferret out new molecules involved in adhesion. To accomplish these goals, we have employed antibodies directed to purified cell surface proteins as double-immunolabeled probes to elucidate the molecular anatomy and pathology of adhesion sites by the ultra-thin frozen sectioning method and then use these purified proteins to determine their binding specificity in vitro. Other more function-oriented studies will evaluate the significance of these molecular associations. We have showed a 140 kilodalton membrane adhesion complex co-localizing with fibronectin and alpha-actinin in normal and transformed cells. The monoclonal antibody JG22E, directed against the 140 kilodalton complex, inhibits attachment and spreading of both normal and transformed cells to fibronectin substratum. However, we found that there is an increased expression of transformation-associated proteases that degrade fibronectin at cell contact sites. We examined the ultrastructural localization, substrate, and inhibitor specificity of the proteases for their roles in the invasion of transformed cells into the extracellular matrix. We will also continue to identify other transmembrane proteins using new monoclonal antibodies and immunoelectron microscopy. (A)