DIFFERENTIATION AND DIFFERENTIATIVE FUNCTIONS OF TRACHEAL EPITHELIAL CELLS

兔气管上皮细胞在纤维连接蛋白-白蛋白-玻璃化氮上的生长 当达到高水平时，包被的培养皿经历鳞状细胞分化。 密度的 在终末分化的最后阶段， 角化 我们已经建立了几个因素来调节这一点 分化和几个生化参数，可以作为 这种分化的标志物。 我们已经证明， 血清中，从中，高密度和高钙EGF的遗漏 浓度可以促进分化，而类维生素A抑制 鳞状细胞分化 我们已经证明， 鳞状细胞分化伴随着几种 新的蛋白质，并由类维生素A调节。 未分化兔 气管上皮细胞表达7种主要角蛋白和一种新的48 kd角蛋白。 当细胞被诱导为鳞状细胞时， 分化 体外翻译实验表明， 这种48 kd角蛋白的合成在mRNA水平上受到调节。 细胞 也会被诱导合成 转氨酶活性 这种转氨酶已被鉴定为 “表皮”转氨酶基于其与 抗人转氨酶单克隆抗体 角质形成细胞 当细胞在胶原凝胶上生长时， 电镜下可见含有分泌颗粒的类视黄细胞 我们已经通过生物化学技术证明了这些培养物 产生粘蛋白糖蛋白。 维甲酸的存在似乎是 重要的是，因为在其缺失时，细胞不含分泌颗粒， 经历鳞状细胞分化。 研究正在进行中，以确定 分化是如何在分子水平上调节的。

Rabbit tracheal epithelial cells grown on fibronectin-albumin-vitrogen coated dishes undergo squamous cell differentiation when reaching high density. In the last stage of this terminal differentiation cells undergo cornification. We have established several factors that regulate this differentiation and several biochemical parameters that can function as markers for this differentiation. We have shown that the addition of serum, the omission of EGF from the medium, high density and high calcium concentrations can promote differentiation whereas retinoids inhibit squamous cell differentiation. We have shown that the induction of squamous cell differentiation is accompanied by the synthesis of several new proteins and is regulated by retinoids. Undifferentiated rabbit tracheal epithelial cells express seven major keratins and a new 48 kd keratin is expressed when cells are induced to squamous cell differentiation. In vitro translation experiments have indicated that the synthesis of this 48 kd keratin is regulated at the level of mRNA. Cells undergoing squamous cell differentiation are also induced to synthesize transglutaminase activity. This transglutaminase has been identified as the "epidermal" transglutaminase on basis of its immunoreactivity with a monoclonal antibody against human transglutaminase from human keratinocytes. When cells are grown on collagen gel and in the presence of retinoids cells containing secretory granules were observed by electron microscopy and we have shown via biochemical techniques that these cultures produce mucin glycoproteins. The presence of retinoids appears to be important since in its absence cells don't contain secretory granules and undergo squamous cell differentiation. Studies are underway to determine how differentiation is regulated at the molecular level.