Human activated CD4+ T lymphocytes increase IL-2 expression by downregulating microRNA-181c

MicroRNAs, a large family of small regulatory RNAs, are posttranscriptional gene regulators that bind mRNA in a sequence-specific manner, thereby controlling diverse aspects of cell function, including immune reaction. In this study, we screened and identified a group of differentially expressed miRNAs in naive and activated CD4+ T cells. Among the miRNAs studied, miR-181c was proven to have the potential to regulate CD4+ T cell activation. miR-181c was downregulated in the process of CD4+ T cell activation, and transfection of miR-181c mimics partially repressed the activation of both Jurkat cells and human peripheral blood mononuclear cells (PBMC) CD4+ T cells. We further showed that miR-181c can bind to the IL-2 3′ UTR and repress its expression by inhibiting translation. Moreover, miR-181c mimics reduced activated CD4+ T cell proliferation. Taken together, our results show that miR-181c serves as a negative regulator that modulates the activation of CD4+ T cells.