Gene expression analysis of wild type and KAP1 KO mouse T cell progenitors

The modulation of chromatin status at specific genomic loci controls lymphoid differentiation. Here, we investigated the role played in this process by KAP1, the universal cofactor of KRAB-containing Zinc Finger Proteins (KRAB-ZFPs), a tetrapod-restricted family of transcriptional repressors. T cell-specific Kap1 knockout mice displayed a significant expansion of immature thymocytes and imbalances in the ratios of mature T cells in the thymus and the spleen, with impaired responses to TCR stimulation. Transcriptome and chromatin studies revealed that KAP1 directly controls the expression of a number of genes involved in TCR and cytokine signalling, among which Traf1 and FoxO1, and is strongly associated with cis-acting regulatory elements marked by the H3K9me3 repressive mark on the genome of thymic T cells. Likely responsible for tethering KAP1 to at least part of its genomic targets, a small number of KRAB/ZFPs are selectively expressed in T lymphoid cells. These results reveal the so far unsuspected yet important role of KRAB/KAP1-mediated epigenetic regulation in T lymphocyte differentiation and activation.

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Santoni de Sio FR, Barde I, Offner S, Kapopoulou A, Corsinotti A, Bojkowska K, Genolet R, Thomas JH, Luescher IF, Pinschewer D, Harris N, Trono D