Thom D, Powell A J, Rees D A
J Cell Sci. 1979 Feb;35:281-305. doi: 10.1242/jcs.35.1.281.
We have investigated the exogenous factors required for the transition from the round shape of suspended fibroblasts to the characteristic spread shape on serum-coated glass. Following the evidence of others that the transition is facilitated by adsorbed component(s) related to CIG/LETS (cold-insoluble globulin/large external transformation-sensitive) proteins, we have isolated 2 such preparations from chick serum. Their influence has been investigated on fibroblast adhesion, spreading and growth and they have been characterized by gel electrophoresis, immunological cross-reactivity, amino acid and carbohydrate residue analysis, sedimentation velocity behaviour and circular dichroism spectroscopy. The preparations have molecular weights of 225/215,000 and 140,000 Daltons respectively and are closely similar in composition and secondary structure. The 225/215 000 Dalton doublet is probably a product of limited proteolysis which almost certainly occurred in the avian circulation. For cells seeded on glass precoated in different ways and in different supplemented media we could detect no change in the extent of attachment but there were profound influences on cell shape following this initial adhesion. We confirm that prior adsorption of either CIG-related preparation to glass does indeed promote fibroblast spreading in the absence of other serum components and that CIG is the sole serum component with this type of activity. We now add 2 important qualifications: (i) the presence of substrate-adsorbed serum CIG is not essential for spreading when other serum components are present in the medium; and (ii) the adhesive organization shown by interference reflexion microscopy is incompletely formed unless the additional serum components are present in the medium. We therefore conclude that 16C fibroblasts have the ability when given the stimulus of soluble serum components other than CIG, but not otherwise, to synthesize all the components necessary for the highly organized contacts with glass, including endogenous CIG/LETS proteins.
我们研究了悬浮成纤维细胞从圆形转变为在血清包被玻璃上特征性铺展形状所需的外源性因素。根据其他人的证据，即这种转变由与CIG/LETS（冷不溶性球蛋白/大的外部转化敏感蛋白）相关的吸附成分促进，我们从鸡血清中分离出了2种这样的制剂。研究了它们对成纤维细胞黏附、铺展和生长的影响，并通过凝胶电泳、免疫交叉反应、氨基酸和碳水化合物残基分析、沉降速度行为和圆二色光谱对它们进行了表征。这些制剂的分子量分别为225/215,000和140,000道尔顿，在组成和二级结构上非常相似。225/215,000道尔顿的双峰可能是有限蛋白水解的产物，几乎可以肯定发生在禽类循环中。对于接种在以不同方式预包被且添加不同培养基的玻璃上的细胞，我们未检测到附着程度的变化，但在初始黏附后对细胞形状有深远影响。我们证实，在没有其他血清成分的情况下，将任何一种与CIG相关的制剂预先吸附到玻璃上确实能促进成纤维细胞铺展，并且CIG是具有这种活性的唯一血清成分。我们现在补充2个重要条件：（i）当培养基中存在其他血清成分时，底物吸附的血清CIG的存在对于铺展不是必需的；（ii）除非培养基中存在其他血清成分，否则干涉反射显微镜显示的黏附结构不完全形成。因此，我们得出结论，16C成纤维细胞在受到除CIG之外的可溶性血清成分刺激时（但其他情况下不行），有能力合成与玻璃进行高度组织化接触所需的所有成分，包括内源性CIG/LETS蛋白。
