REGULATION OF DIFFERENTIATION OF TRACHEOBRONCHIAL /EPIDERMAL EPITHELIAL CELLS

鳞状细胞分化是一个多阶段的过程。不可逆转的增长 停滞发生在这种分化压力的早期，并被诱导 当培养的细胞达到融合时或经干扰素处理后 伽马(IFNG)或佛波酯。我们一直将IFNG作为一种工具 在不可逆转增长停滞的控制方面获得洞察力。我们有 显示IFNG在G1期的某一特定点阻止生长。 细胞周期。大量的细胞周期调节蛋白和事件 被IFNG下调的基因，包括细胞周期蛋白A、增殖细胞核抗原、cdc2、p53、p21 和cMyc合成。此外，IFNG还抑制细胞过度磷酸化。 视网膜母细胞瘤蛋白Rb。使用IFNG添加的时间进程 为了使细胞同步，我们研究了因果关系 对IFNG诱导的多种细胞周期蛋白/cdk激酶活性的抑制作用 以及据报道调节G1进程的复合体。不可逆转 生长停滞之后是鳞状细胞的级联变化- 特定的基因。我们实验室已经鉴定并克隆了几个基因 它们在鳞状细胞分化过程中受到不同的调控，这些 包括转谷氨酰胺酶I型(TGase I)、角蛋白A和B、松弛素和 与PMP22相关的基因。为了研究这些基因的调控，我们 克隆了5‘侧翼区。足迹、缺失突变和 迁移率漂移分析被用来确定DNA元件在 这些基因的转录调控。维甲酸很重要 鳞状细胞分化的调节因子。维甲酸类化合物抑制该基因的表达 角蛋白13、TGase I和角蛋白a和b的表达，同时诱导其他 基因，如角蛋白19和TGase II.核维甲酸受体- 选择性激动剂、拮抗剂和显性负性RARA受体 用来研究维甲酸信号通路在这些 维甲酸的作用。我们的结果表明，诱导 TGase II的表达是由RARA依赖的机制介导的。

Squamous differentiation is a multi-stage process. Irreversible growth arrest occurs early during this press of differentiation and is induced when cultured cells reached confluence or after treatment with interferon gamma (IFNg) or phorbol esters. We have been using IFNg as a tool to obtain insight in the control of irreversible growth arrest. We have shown that IFNg blocks growth at a specific point in e G1 phase of the cell cycle. Numerous cell cycle regulatory proteins and events were found down-regulated by IFNg, including cyclin A, PCNA, cdc2, p53, p21 and cMyc synthesis. In addition, IFNg, inhibits the hyperphosphorylation of the retinoblastoma protein RB. Using a time course of IFNg addition to synchronized cells, we investigated the cause and effect relationship to IFNg-induced growth arrest of the various cyclin/cdk kinase activities and complexes that are reported to regulate G1 progression. Irreversible growth arrest is followed by a cascade of changes in squamous cell- specific genes. Our laboratory has identified and cloned several genes that are differentially regulated during squamous differentiation, these include transglutaminase type I (TGase I), cornifin a and b, relaxin and a gene related to PMP22. To study the regulation of these genes, we cloned the 5'-flanking region. Footprinting, deletion mutation and mobility shift assays ere used to identify DNA elements important in the transcriptional regulation of these genes. Retinoids are important regulators of squamous differentiation. Retinoids inhibit the expression of keratin 13, TGase I and cornifin a and b, while they induce other genes, such as keratin 19 and TGase II. Nuclear retinoid receptor- selective agonists, an antagonist and a dominant-negative RARa receptor were used to study the retinoid signaling pathways involved in these actions of retinoids. Our results have demonstrated that the induction of TGase II is mediated by an RARa-dependent mechanism.