Project description:The goal of this experiment is to define how lack of Ikaros impacts gene expression in mature CD4 T cells, both in the resting and activated state. To do this, a conditional knockout mouse model was generated using Cre/lox technology. The floxed allele was designed such that the last translated exon and 3' UTR of the Ikaros gene (Ikzf1) are deleted in mature T cells (mediated by distal Lck-driven Cre). CD4 T cells from mice with floxed alleles that did not express Cre (Cre-) and those that did express Cre (Cre+) were analyzed.
Project description:We found by microarray analysis that Ikaros is critical to limit the expression of several pro-inflammatory genes during Th17 cell polarization. To unravel the role of Ikaros in the expression of pro-inflammatory genes without Th17 polarizing cytokines, we performed an RNA-seq analysis in naive CD4+ T cells and CD4+ T cells activated with anti-CD3+anti-CD28 antibodies (Th0 condition), from WT (Ikaros f/f CD4-Cre-) and Ikaros TKO mice (Ikaros f/f CD4-Cre+).
Project description:We found that Ikaros is critical to limit the expression of pro-inflammatory cytokines in TCR/CD28-activated CD4+ T cells. To understand if Ikaros could modify the chromatin accessibility in regions controling the expression of these pro-inflammatory genes, we examined the chromatin state in naive CD4+ T cells and CD4+ T cells activated with anti-CD3+anti-CD28 antibodies for 1 and 2 days, from WT (Ikaros f/f CD4-Cre-) and Ikaros TKO mice (Ikaros f/f CD4-Cre+), using the ATAC-seq approach.
Project description:The transcription factor Ikaros plays a critical role during lymphocyte differentiation, proliferation and activation. The deletion of Ikaros zinc finger 4 (Ikaros-Zn4-/-) results in the lowering of activation threshold and increased proliferation of mature T cells. Here we used CD8+ T cells from homozygous Ikaros-Zn4-/- mice to investigate its role in regulating gene expression downstream of T-cell receptor signaling.
Project description:The aim of the project is to determine the binding sites of Ikaros in CD4+ T cells. To perform this, CD4 naive T cells (CD4 TN; d0) either rested or activated with anti-CD3+anti-CD28 Abs for 1 day (Th0 d1) were subjected to a ChIP using anti-Ikaros Ab followed by high throughput sequencing.
Project description:Ikaros encodes a transcription factor that functions as a tumor suppressor in T-ALL. The mechanisms through which Ikaros regulates gene expression and cellular proliferation in T-ALL are unknown. Re-introduction of Ikaros into Ikaros-null T-ALL cells results in cessation of cellular proliferation and induction of T-cell differentiation. We performed dynamic global epigenomic and gene expression analyses to determine the role of Ikaros in tumor suppression during this process. Our results identified novel Ikaros functions in the epigenetic regulation of gene expression: Ikaros directly regulates de novo formation and depletion of enhancers, as well as de novo formation of active enhancers and activation of poised enhancers; Ikaros directly induces the formation of super-enhancers; and Ikaros demonstrates pioneering activity by directly regulating chromatin accessibility. Dynamic analyses demonstrate the long-lasting effect of Ikaros DNA binding on enhancer activation, de novo formation of enhancers and super-enhancers, and chromatin accessibility. Ikaros induces profound, global re-distribution of HDAC1 via recruitment of HDAC1 to promoter and enhancer regions of different target genes. Expression analysis identified a large number of novel signaling pathways that are directly regulated by Ikaros and Ikaros-induced enhancers, and that are responsible for the cessation of proliferation and induction of T-cell differentiation in T-ALL cells.
Project description: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. 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.
Project description:The aim of the experiment was to visualize genes under the control of Ikaros during early T cell development. We used mice carrying floxed Ikaros alleles that were crossed with the Rosa26-CreERT2 mice, and which were injected with tamoxifen for 4 days. DN4 thymocytes were sorted from 4 mice (5-6 week-old) which are positive or not for the Rosa26-CreERT2 transgene. DN4 cells were sorted from 2 Ikf/f Rosa26-CreERT2+ mice and 2 Ikf/f mice, which were all treated with tamoxifen for 4 days. Loss of Ikaros was confirmed in sorted cells from the Ikf/f Rosa26-CreERT2+ mice by western blot. Gene expression profiles were determined on total RNA from sorted cells with Affymetrix Mouse Gene arrays.