GSE111427
TCR signal strength controls thymic differentiation of iNKT cell subsets
Three major phenotypically and functionally distinct invariant Natural Killer T (iNKT) cell subsets (iNKT1, iNKT17 and iNKT2), each with propensity to traffic to different tissues and to secrete different cytokines upon activation, have been defined. These fate assignments can be conferred upon iNKT cells during development in the thymus, but the cues that direct these decisions remain unclear. Here, we show that T cell antigen receptor (TCR) signal strength governs the development of iNKT cell subsets in the thymus, with high signaling strength necessary for iNKT2 and iNKT17 development. Alteration of TCR diversity and/or signaling dramatically diminished iNKT2 and iNKT17 cell subset development in a cell intrinsic manner. Decreased TCR signaling affected the persistence of Egr2 expression and the upregulation of PLZF both in vivo and in vitro. Genome-wide chromatin accessibility analysis revealed subset-specific activity of regulatory elements associated with unique signatures of transcription factor binding sites. NFAT and Egr binding motifs were found preferentially enriched in chromatin regulatory regions specifically accessible in iNKT2 cells that were lost in iNKT2 cells that had developed with reduced TCR signaling. Altogether, these data suggest a model of iNKT cell subset development where variable TCR signaling induces changes in chromatin accessibility at NFAT and Egr binding sites which exerts a determinative influence on the dynamic of gene enhancer accessibility that affects the developmental fate of iNKT cells. Overall design: ATAC-seq of invariant Natural Killer T cell populations from 2 genotypes of mice