REGULATION OF SQUAMOUS CELL DIFFERENTIATION

工作总结：鳞状细胞分化是一个多阶段的过程 出现在许多组织中。控制生长之间的分子联系 抑制和分化正在研究中。洞察这些 机制不仅对于理解正常的控制是重要的 分化还包括鳞状细胞癌等疾病的缺陷 化生和癌症。几种不同的信号通路可以诱导 鳞状细胞分化，包括干扰素引起的鳞状细胞分化 和佛波酯。我们证明了角质形成细胞可以生长 停滞在细胞周期的G1期的特定时间点。这是伴随着的 通过抑制Rb的磷酸化，降低cdk的活性和 Cdk抑制因子p27、p21和p16的诱导。尽管异国情结 P21或p27的表达导致生长停滞，细胞不分化 暗示终端中涉及到额外的信号 差异化。癌细胞对终末分化具有抵抗力 生长调节基因的表达和变化与鳞状细胞癌的诱导 没有观察到特定的基因。我们已经鉴定并克隆了几个 鳞状细胞分化过程中受调控的基因，包括 转谷氨酰胺酶I型(TGase I)、角蛋白a和b、松弛素和a 与PMP22相关的膜蛋白。研究转录本 这些基因的调控，我们克隆了其上游调控区 TGase I、Cornifin a和Cl20。足迹、缺失突变和 迁移率改变分析用于鉴定重要的DNA元件。 类似CREB和AP-1的位点正在进一步鉴定。我们分析了 2.9kb上游调控区的能力(TGase I基因) 控制氯霉素乙酰转移酶(CAT)的表达 报告基因在体内和体外。携带PTG(-)的转基因小鼠 2)CAT构建展示了相同的组织特异性模式 CAT的表达与已报道的TGase I相同。

Summary of Work: Squamous differentiation is a multi-stage process that occurs in many tissues. The molecular link between control of growth arrest and differentiation is being studied. Insight into these mechanisms are important not only for understanding the control of normal differentiation but also the defects in diseases such as squamous metaplasia and cancer. Several different signaling pathways can induce squamous differentiation including those initiated by interferon gamma and phorbol esters. We demonstrated that keratinocytes become growth arrested at specific point in G1 of the cell cycle. This is accompanied by inhibition of Rb phos- phorylation, decrease in cdk activity and induction of the cdk-inhibitors p27, p21 and p16. Although ectopic expression of p21 or p27 causes growth arrest, cells do not differentiate suggesting that additional signals are involved in terminal differentiation. Carcinoma cells are resistant to terminal differentia- tion and changes in growth-regulatory genes and induction of squamous- specific genes were not observed. We have identified and cloned several genes that are regulated during squamous differentiation, including transglutaminase type I (TGase I), cornifin a and b, relaxin and a membrane protein related to PMP22. To study the transcriptional regulation of these genes, we cloned the upstream regulatory region of TGase I, cornifin a and CL20. Footprinting, deletion mutation and mobility shift assays were used to identify important DNA elements. CREB- and AP-1-like sites are being further characterized. We analyzed the ability of a 2.9kb upstream regulatory region (of the TGase I gene) to control the expression of a chloramphenicol acetyltransferase (CAT) reporter gene in vivo and in vitro. Transgenic mice bearing the pTG(- 2.9)CAT construct exhibited the same pattern of tissue-specific expression of CAT as reported for TGase I.