MicroRNA-181a regulates IFN-γ expression in effector CD8+ T cell differentiation
Tiago Amado, Ana Amorim, Francisco J. Enguita, Paula Vargas Romero, Daniel Inácio, Marta Pires de Miranda, Samantha J. Winter, J. Pedro Simas, Andreas Krueger, Nina Schmolka, Bruno Silva‐Santos, Anita Quintal Gomes
Abstract
Abstract CD8 + T cells are key players in immunity against intracellular infections and tumors. The main cytokine associated with these protective responses is interferon-γ (IFN-γ), whose production is known to be regulated at the transcriptional level during CD8 + T cell differentiation. Here we found that microRNAs constitute a posttranscriptional brake to IFN-γ expression by CD8 + T cells, since the genetic interference with the Dicer processing machinery resulted in the overproduction of IFN-γ by both thymic and peripheral CD8 + T cells. Using a gene reporter mouse for IFN-γ locus activity, we compared the microRNA repertoires associated with the presence or absence of IFN-γ expression. This allowed us to identify a set of candidates, including miR-181a and miR-451, which were functionally tested in overexpression experiments using synthetic mimics in peripheral CD8 + T cell cultures. We found that miR-181a limits IFN-γ production by suppressing the expression of the transcription factor Id2 , which in turn promotes the Ifng expression program. Importantly, upon MuHV-4 challenge, miR-181a-deficient mice showed a more vigorous IFN-γ + CD8 + T cell response and were able to control viral infection significantly more efficiently than control mice. These data collectively establish a novel role for miR-181a in regulating IFN-γ–mediated effector CD8 + T cell responses in vitro and in vivo.