A microRNA-directed program of cytotoxic CD8+ T cell differentiation

Acquisition of effector properties is a key step in the generation of cytotoxic T lymphocytes (CTLs). Here we show that inflammatory signals regulate Dicer expression in CTL, and that deletion or depletion of Dicer in mouse or human activated CD8+ T cells causes upregulation of perforin, granzyme and effector cytokines. Genome-wide analysis of miRNA changes induced by exposure of differentiating CTLs to IL-2 and inflammatory signals identifies miR-139 and miR-150 as components of a miRNA network that controls perforin, eomesodermin (Eomes) and IL-2Ra expression in differentiating CTLs and whose activity is modulated by IL-2, inflammation and antigenic stimulation. Overall our data show that strong IL-2R and inflammatory signals act through Dicer and miRNAs to control the cytolytic program and other aspects of effector CTL differentiation. Comparison of control and Dicer knock-out CTLs differentiated in vitro; Comparison of wild type CTLs differentiated in vitro with or without inflammatory stimuli; Comparison of effector and memory precursor CTLs isolated from mice infected with LCMV-Armstrong