Project description:We used microarrays to analyze gene expression changes in the Ikaros null ILC87 T cell tumor line after re-expression of Ikaros. ILC87 cells were transduced to stably express the 4-hydroxytamoxifen-inducible (4OHT) Ikaros1-ER fusion protein. ILC87-Ik1-ER cells were treated with mock (EtOH) or 4OHT for 1 day and the global gene expression changes were assessed by microarray analysis.
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: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: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:The mouse Ikaros-deficient thymic lymphoma cell line T29 was transduced with an empty retrovirus (MigR1) or a retrovirus expressing an fusion proein between Ikaros1 and the ligand binding domain of the estrogen receptor. Cells trreated with ethanol or 4-hydroxy-tamoxyfen (4OHT) for 24h were profiled. We used expression of an inducible ersion of the Ikaros protein in an Ikaros-deficient cell line to identify Ikaros-regulated genes
Project description:Chromatin protein positive coactivator 4 (PC4) has multiple functions, including chromatin compaction. However, its role in immune cells is largely unknown. We show that PC4 orchestrates chromatin structure and gene expression in mature B cells. B-cell specific PC4-deficient mice showed impaired production of antibody upon antigen stimulation. The PC4 complex purified from B cells contained transcription factors IKAROS and IRF4. IKAROS protein was reduced in PC4-deficient mature B cells, resulting in de-repression of their target genes in part by diminished interactions with gene silencing components. Upon activation, IRF4 protein amount was not increased in PC4-deficient B cells, resulting in reduction of plasma cells. Importantly, IRF4 reciprocally induced PC4 expression via a super-enhancer. PC4 knockdown in human B-cell lymphoma cells reduced IKAROS protein as an anticancer drug lenalidomide. Our findings establish PC4 as a chromatin regulator of B cells and a possible therapeutic target adjoining IKAROS in B-cell malignancies.
Project description:The mouse Ikaros-deficient thymic lymphoma cell line T29 was transduced with a retrovirus expressing an fusion protein between a dominant-negative form of Mastermind and the ligand binding domain of the estrogen receptor. Cells trreated with Ethanol or 4-hydroxy-tamoxyfen for 24h were profiled. We used expression of an inducible ersion of the dominant negative Mastermind protein in an Ikaros-deficient cell line to identify Notch-regulated genes
Project description:We showed that the Ikaros transcription factor is essential for the pre-B cell differentiation. We analyzed the transcriptome of a Ikaros deficient pre-B cell line which was reconstituted with an inducible Ikaros-ER fusion protein. To determine the direct Ikaros targets, we did ChIP-sequencing on chromatin from this pre-B cell line, as cell numbers in mice were too limiting for these studies.