Molecular mechanism of the interaction between fibronectin and cells in the tissue organization

为了揭示血浆纤维连接蛋白和组织纤维连接蛋白的区别，我们分离了胎盘纤维连接蛋白，并对其糖链的化学结构进行了研究。肼分解释放的低聚糖被放射性标记，并通过顺序的酶降解和甲基化分析进行检测。结果表明，胎盘纤维连接蛋白和血浆纤维连接蛋白具有明显不同的糖链。在胎盘组织培养中合成的纤维连接蛋白与凝集素的结合性质也显示出与血浆纤维连接蛋白不同的糖链。纤维连接蛋白在胎盘中的免疫组织化学定位表明，产生纤维连接蛋白的细胞包括内皮细胞和成纤维细胞。这些结果表明胎盘组织纤维连接蛋白不是从血浆中产生的，而是产生并保留了自己的组织纤维连接蛋白。我们已经分离并鉴定了人胎盘的纤维连接蛋白结合蛋白多糖。为了检测这种蛋白多糖的生物学活性，将FL羊膜上皮细胞培养在涂有纤维连接蛋白或层粘连蛋白的塑料培养皿上，并与该蛋白多糖预先孵育或不与其孵育。FL细胞在包被纤维连接蛋白或层粘连蛋白的培养皿上附着良好，但扩散程度较小。当涂布的培养皿与这种蛋白多糖预先孵育时，FL细胞变得很好地扩散。因此，蛋白多糖的生物活性似乎包括促进细胞扩散。通过三年的研究，我们证明了胎盘组织合成并保留了纤维连接蛋白，纤维连接蛋白在胎盘组织的组织尤其是上皮形成中起着重要的作用，纤维连接蛋白的功能受多种细胞外基质成分的调节，包括我们新发现的纤维连接蛋白结合蛋白多糖。

In order to reveal the difference between plasma fibroenctin and tissue fibronectin, we isolated placental fibronectin and investigated the chemical sturctures of its carbohydrate chains. The oligosaccharides liberated by hydrazinolysis were radiolabeled and examined by sequential enzymatic degradation and methylation analysis. The results indicated that the placenatal and plasma fibronectins have quite different carbohydrate chains. The fibronectin synthesized in the tissue culture of the placenta also had the different sugar chains from those of plasma fibronectin as revealed by their binding nature to lectins. The immunohistochemical localization of fibronectin in the placenta identified fibronectin-producing cells including endothelial and fibroblastic cells. These results indicate that placenta tissue fibronectin is not derived from plasma, but that own tissue fibronectin is produced and retained. We have isolated and characterized a fibronectin-binding proteoglycan of the human placenta. to examine the biological activity of this proteoglycan, FL amnion epithelial cells were culauted on plastic dishes coated with fibronection or laminin with or without preincubation with this proteoglycan. FL cells were well attached to the dishes coated with fibronectin or laminin, but spread to a minor extent. When the coated dishes were preincubated with this proteoglycan, FL cells became spread well. Thus, the biological activities of the proteoglycan appeared to include the promotion of the cell spreading. Through our investigation on this project for 3 years, we have demonstrated that the placental tissue synthesizes and retains the fibronectin of its own, that the fibronectin has an important role in the placental tissue organizttion particularly in the epithelial formation, and that the function of the fibronectin is modulated by various extracellular amatrix components including a fibronectinbinding proteoglycan newly found by us.