Molecular Dermatology Research Group, Unit of Dermatology and Venerology, Department of Medicine, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden.
J Invest Dermatol. 2010 Jan;130(1):124-34. doi: 10.1038/jid.2009.294.
Terminal differentiation of keratinocytes is a multistep process that requires a coordinated program of gene expression. We aimed to explore the possible involvement of a previously unreported class of non-coding RNA genes, microRNAs (miRNAs) in keratinocyte differentiation by using miRNA expression profiling. Out of 365 miRNAs tested, 7 showed significant change between keratinocytes cultured in low or high calcium concentration. The highest-ranked upregulated gene was miR-203, whose expression was significantly upregulated in response to calcium and other inducers of keratinocyte differentiation such as 12-O-tetradecanoylphorbol-13-acetate (TPA) and vitamin D(3). Differentiation-induced upregulation of miR-203 expression was blocked by treatment with specific inhibitors of protein kinase C (PKC), GF109203X, and Ro31-8220. Moreover, our results showed that the activator protein-1 (AP-1) proteins c-Jun and JunB regulate miR-203 expression in keratinocytes. In contrast to inducers of keratinocyte differentiation, epidermal growth factor and keratinocyte growth factor suppressed miR-203 expression in keratinocytes below the basal level. Overexpression of miR-203 in keratinocytes resulted in enhanced differentiation, whereas inhibition of miR-203 suppressed calcium-induced terminal differentiation as judged by involucrin expression. These results suggest that upregulation of miR-203 in human keratinocytes is required for their differentiation and is dependent on the activation of the PKC/AP-1 pathway.
角质形成细胞的终末分化是一个多步骤的过程，需要协调表达基因的程序。我们旨在通过 miRNA 表达谱来探索先前未报道的一类非编码 RNA 基因，即 microRNAs（miRNAs）在角质形成细胞分化中的可能参与。在 365 个测试的 miRNA 中，有 7 个在低钙或高钙浓度培养的角质形成细胞之间显示出显著变化。上调幅度最高的基因是 miR-203，其表达在钙和其他角质形成细胞分化诱导剂（如 12-O-十四烷酰佛波醇-13-乙酸酯（TPA）和维生素 D（3））的作用下显著上调。特异性蛋白激酶 C（PKC）抑制剂 GF109203X 和 Ro31-8220 处理可阻断分化诱导的 miR-203 表达上调。此外，我们的结果表明，激活蛋白-1（AP-1）蛋白 c-Jun 和 JunB 调节角质形成细胞中 miR-203 的表达。与角质形成细胞分化诱导剂相反，表皮生长因子和角质形成细胞生长因子将角质形成细胞中的 miR-203 表达抑制在基础水平以下。在角质形成细胞中过表达 miR-203 可导致分化增强，而抑制 miR-203 可抑制钙诱导的终末分化，如通过包裹蛋白表达判断。这些结果表明，miR-203 在人角质形成细胞中的上调是其分化所必需的，并且依赖于 PKC/AP-1 通路的激活。
