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

为了揭示血浆纤维结合蛋白与组织纤维结合蛋白的区别，我们分离了胎盘纤维结合蛋白，并对其糖链的化学结构进行了研究。通过肼解释放的寡糖进行放射性标记，并通过连续酶降解和甲基化分析进行检查。结果表明，胎盘和血浆纤维连接蛋白具有不同的糖链。胎盘组织培养物中合成的纤连蛋白也具有与血浆纤连蛋白不同的糖链，这是由它们与凝集素的结合性质所揭示的。纤维连接蛋白在胎盘中的免疫组织化学定位确定了纤维连接蛋白产生细胞，包括内皮细胞和成纤维细胞。这些结果表明，胎盘组织纤连蛋白不是来自血浆，而是自身组织纤连蛋白产生并保留。我们已经分离和鉴定了人胎盘的纤连蛋白结合蛋白聚糖。为了检测这种蛋白聚糖的生物活性，在用纤连蛋白或层粘连蛋白包被的塑料培养皿上培养FL羊膜上皮细胞，用或不用这种蛋白聚糖预孵育。FL细胞很好地附着在用纤连蛋白或层粘连蛋白包被的培养皿上，但在较小程度上扩散。当包被的培养皿与该蛋白聚糖预孵育时，FL细胞变得良好地铺展。因此，蛋白多糖的生物活性似乎包括促进细胞铺展。通过3年的研究，我们证实了胎盘组织自身合成并保留着纤维连接蛋白，纤维连接蛋白在胎盘组织的形成，特别是上皮的形成中起着重要的作用，纤维连接蛋白的功能受到多种细胞外基质成分的调节，其中包括我们新发现的一种纤维连接蛋白结合蛋白聚糖。

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.