Stellmach V, Leask A, Fuchs E
Howard Hughes Medical Institute, Department of Molecular Genetics and Cell Biology, University of Chicago, IL 60637.
Proc Natl Acad Sci U S A. 1991 Jun 1;88(11):4582-6. doi: 10.1073/pnas.88.11.4582.
Vitamin A and other retinoids profoundly inhibit morphological and biochemical features of epidermal differentiation in vivo and in vitro. To elucidate the molecular mechanisms underlying the differential expression of epidermal keratins and their regulation by retinoids, we examined retinoid-mediated changes in total protein expression, protein synthesis, mRNA expression, and transcription in cultured human keratinocytes and in squamous cell carcinoma (SCC-13) cells of epidermal origin. Our studies revealed that the epidermal keratins, K5, K6, K14, and K16, their mRNAs, and their transcripts were diminished relative to actin as a consequence of retinoic acid (RA) treatment. The effects were most pronounced in SCC-13 and were detected as early as 6 hr post-RA treatment, with enhancement over an additional 24-48 hr. Repression was also observed when 5' upstream sequences of K14 or K5 genes were used to drive expression of a chloramphenicol acetyltransferase reporter gene in SCC-13 keratinocytes. Both cell types were found to express mRNAs for the RA receptors alpha and gamma, which may be involved in the RA-mediated transcriptional changes in these cells. The rapid transcriptional changes in epidermal keratin genes were in striking contrast to the previously reported slow transcriptional changes in simple epithelial keratin genes.
维生素A及其他类视黄醇在体内和体外均可显著抑制表皮分化的形态学和生化特征。为阐明表皮角蛋白差异表达及其受类视黄醇调控的分子机制，我们检测了类视黄醇介导的培养人角质形成细胞以及表皮来源的鳞状细胞癌（SCC - 13）细胞中总蛋白表达、蛋白质合成、mRNA表达及转录的变化。我们的研究显示，经视黄酸（RA）处理后，相对于肌动蛋白，表皮角蛋白K5、K6、K14和K16及其mRNA和转录本均减少。这些效应在SCC - 13细胞中最为明显，在RA处理后6小时即可检测到，并在随后的24 - 48小时内增强。当使用K14或K5基因的5'上游序列驱动氯霉素乙酰转移酶报告基因在SCC - 13角质形成细胞中表达时，也观察到了抑制作用。发现这两种细胞类型均表达RA受体α和γ的mRNA，这可能参与了这些细胞中RA介导的转录变化。表皮角蛋白基因的快速转录变化与先前报道的简单上皮角蛋白基因的缓慢转录变化形成了鲜明对比。
