DIFFERENTIATION AND DIFFERENTIATIVE FUNCTIONS OF AIRWAY 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 在无血清和无维生素A的培养基中， 在各种条件下的鳞状分化。 这 分化发生在几个阶段。 第一个细胞经历终末 细胞分裂;细胞聚集在细胞周期的G 0/G1期， 形成殖民地的能力。 这种细胞分裂发生在高 密度或诱导在低密度时，表皮生长因子， 从培养基中省略或当添加TGF β时。 其次是 鳞状表型的表达，其特征在于诱导 鳞状形态，转氨酶和胆固醇升高 硫酸盐水平，48和56 kd角蛋白表达增加， 形成交联的包膜。 胆固醇的增加 硫酸盐水平似乎与磺基转移酶的增强有关 活动 高钙浓度促进了 鳞状表型 维甲酸对承诺没有影响， 终末细胞分裂，但抑制鳞状上皮细胞的表达。 表型;视黄酸抑制转氨酶的增加， 硫酸胆固醇水平改变角蛋白的表达， 形成交联的包膜。 研究监管 在分子水平上的分化，我们建立了cDNA文库， 来自鳞状分化细胞和分离的重组体的poly（A）+ RNA 与从鳞状上皮细胞分离的mRNA杂交的cDNA克隆 分化细胞，而不是未分化和视黄质细胞 酸处理的细胞。 这表明这些克隆代表基因 作为分化标志物的产物。 我们正在 分析这些基因产物在什么水平上受到调控以及如何调控的过程 维甲酸控制它们。

Rabbit tracheal epithelial cells grown on fibronectin-albumin-vitrogen coated dishes in serum-free and vitamin A-free medium undergo terminal squamous differentiation under a variety of conditions. This differentiation occurs in several stages. First cells undergo terminal cell division; cells accumulate in G0/G1 phase of the cell cycle and loose the ability to form colonies. This terminal cell division occurs at high density or is induced at low density when epidermal growth factor is omitted from the medium or when TGFBeta is added. This is followed by the expression of a squamous phenotype that is characterized by the induction of a squamous morphology, increase in transglutaminase and cholesterol sulfate levels, increase in the expression of a 48 and 56 kd keratin and the formation of cross-linked envelopes. The increase in cholesterol sulfate levels appears to be related to an enhancement in sulfotransferase activity. High calcium concentration promotes the expression of the squamous phenotype. Retinoic acid has no effect on the commitment to terminal cell division but inhibits the expression of the squamous phenotype; retinoic acid inhibits the increase in transglutaminase and cholesterol sulfate levels the alterations in keratin expression and the formation of cross-linked envelopes. To study the regulation of differentiation at the molecular level, we established a cDNA library using poly (A)+ RNA from squamous differentiated cells and isolated recombinant cDNA clones that hybridize with mRNA's isolated from squamous differentiated cells but not from undifferentiated and retinoic acid-treated cells. This indicates that these clones represent gene products that function as markers for differentiation. We are in the process to analyze at what level these gene products are regulated and how retinoids control them.