GSE61148
Ikaros mediates gene silencing in T cells through Polycomb Repressive Complex 2 [ChIP-seq]
T cell development is accompanied by epigenetic changes that ensure the silencing of stem cell-related, and the activation of lymphocyte-specific programs. How transcription factors influence these changes remains unclear. We show that the Ikaros transcription factor interacts with the Polycomb Repressive Complex 2 (PRC2) in CD4-CD8- thymocytes, and allows its binding to >200 developmentally-regulated genes, many of which are expressed in hematopoietic stem cells. Loss of Ikaros in CD4-CD8- cells leads to diminished histone H3 Lys27 (H3K27) trimethylation and ectopic expression of these genes. Ikaros binding triggers PRC2 recruitment and H3K27 trimethylation. Furthermore, Ikaros interacts with PRC2 independently of the Nucleosome Remodeling and Deacetylation complex. Our results identify Ikaros as a fundamental regulator of PRC2 function in developing T cells. Overall design: Genome-wide comparison of different histone modifications, Ikaros, Suz12 and NuRD binding in different stages of T cell development in WT and Ikaros mutant mice. Profiling of H3K27me3 in DN1, DN2, DN3, DN4 and DP thymocytes and hematopoietic stem and progenitor cells (LSK cells) of WT and Ikaros mutant mice. Profiling of H3K4me3 and H3ac in WT and Ikaros mutant DP thymocytes. Global analysis of Ikaros binding in WT DN3, DN4 and DP cells, Suz12 binding in WT and Ikaros mutant DN3 cells, and Mta2 and Mi2beta binding in WT DN3 cells. Genome-wide profiling of Ikaros binding and H3K27me3 upon Ikaros activation in Ikaros-deficient leukemic T cells.