Gene expression profiling of WT or Dicer KO iNKT cells and T cells

iNKT cells are a T lymphocyte subset displaying an innate effector phenotype that is acquired through a thymic developmental program controlled by microRNAs (miRNAs). iNKT cells lacking all miRNAs by the deletion of Dicer (Dicer KO) are markedly reduced and display a complete maturation block. In this study, we sought to gain insight into the miRNA-regulated genetic program required for iNKT cell development. By systemic analysis, we identified transcripts differentially expressed between thymic WT or Dicer KO iNKT cells and targeted by the iNKT cell-specific miRNAs. TGF-βRII, a molecule critically implicated in iNKT cell maturation, was found upregulated in Dicer KO iNKT cells together with increased TGF-β-dependent signaling. miRNAs belonging to the paralog miR-106a~363, miR-106b~25 and miR-17~92 clusters were predicted to target TGF-βRII mRNA during iNKT cell development. Thymic iNKT cells lacking all three miRNA clusters displayed both increased TGF-βRII expression and signaling and a maturation block, recapitulating those found in Dicer KO iNKT cells. Consistently, inhibition of TGF-β-dependent signaling in the absence of miRNAs, by crossing TGF-βRII KO and Dicer KO mice, rescued iNKT cell maturation. Collectively, our results highlight a fundamental requirement of the modulation of TGF-β-dependent signaling by miRNAs for iNKT cell development invariant NKT cells (divided in stage 1-2 or stage 3 cells) and T lymphocytes were sorted from HSAlow enriched thymi of WT and Dicer KO 4-week old mice, in triplicate