REGULATION OF DIFFERENTIATION IN LUNG AND EPIDERMAL KERATINOCYTES

鳞状细胞分化是一个多阶段的过程，发生在许多组织中。环境侮辱会对生长和分化的控制产生巨大影响。控制生长停滞和分化之间的分子联系正在研究中。几种不同的信号通路可以诱导鳞状细胞分化，包括由干扰素g和佛波酯启动的信号通路。我们证明角质形成细胞在细胞周期的G1期的特定时间点停止生长。伴随而来的是Rb磷酸化的抑制，cdk活性的降低以及cdk抑制物p27、p21和p16的诱导。虽然p21或p27的异位表达导致生长停滞，但细胞不分化，这表明更多的信号参与了末端分化。癌细胞抵抗终末分化，没有观察到生长调节基因的变化和鳞状细胞特异性基因的诱导。我们已经鉴定并克隆了几个在鳞状细胞分化过程中受到调控的基因，包括转谷氨酰胺酶I(TGase I)和膜蛋白CL-20/EMP-1。为了研究这些基因的转录调控，我们克隆了TGase I和CL20的上游调控区，并通过足迹分析、缺失突变和迁移率改变分析确定了CREB/AP-1样位点在其转录调控中起重要作用。对TGase I基因上游2.9kb调控氯霉素乙酰转移酶(CAT)报告基因的表达进行了体内分析。这些研究表明，-2.9kb的启动子区域包含了TGase I适当的发行和分化特异性表达的所有信息。这些结果表明，p38 MAPK信号通路在mRNA稳定水平上调控COX-2，ERK信号通路在转录水平调控COX-2。与NHEK相比，干扰素-g或转化生长因子α在几种鳞癌细胞系中诱导TGFa或COX-2表达的效果不是很好，这表明干扰素-g和转化生长因子α的反应通路都发生了变化。干扰素-g诱导的TGFa和随后PGE2的增加产生了重要的信号，参与了触发与皮肤中许多炎症性疾病相关的过度增殖转化。-气管、皮肤、生长控制、鳞状细胞分化、基因调控、转谷氨酰胺酶、维甲酸、干扰素

Squamous differentiation is a multi-stage process that occurs in many tissues. Environmental insults can have a dramatic impact on the control of growth and differentiation. The molecular link between control of growth arrest and differentiation is being studied. Several different signaling pathways can induce squamous differentiation including those initiated by interferon g 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 phosphorylation, 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 differentiation 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) and a membrane protein CL-20/EMP-1. To study the transcriptional regulation of these genes, we cloned the upstream regulatory region of TGase I and CL20, and determined by footprinting, deletion mutation and mobility shift assays DNA elements that CREB/AP- 1-like sites are important in their transcriptional control. The 2.9kb upstream regulatory region of the TGase I gene to control the expression of a chloramphenicol acetyltransferase (CAT) reporter gene was also analyzed in vivo. These studies showed that the -2.9kb promoter region contains all the information for the proper issue- and differentiation-specific expression of TGase I. These results suggest that the p38 MAPK signaling pathway controls COX-2 at the level of mRNA stability while the ERK signaling pathway regulates COX-2 at the level of transcription. In contrast to NHEK, IFN-g or TGFa are not very effective in inducing TGFa or COX-2 expression in several squamous carcinoma cell lines indicating alterations in both IFN-g and TGFa response pathways. The induction of TGFa by IFN-g and the subsequent increase in PGE2 generate important signals involved in triggering the hyperproliferative transformation associated with many inflammatory diseases in the skin. - trachea, skin, growth control, squamous differentiation, gene regulation, transglutaminase, retinoic acid, interferon