Integration of high-throughput reporter assays identify a critical enhancer of the Ikzf1 gene
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE147234 | GEO | 2021/03/31
REPOSITORIES: GEO
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Project description:Alterations of IKZF1, encoding the lymphoid transcription factor IKAROS, are a hallmark of high risk acute lymphoblastic leukemia (ALL), however the role of IKZF1 alterations in ALL pathogenesis is poorly understood. Here we show that in mouse models of BCR-ABL1 leukemia, Ikzf1 and Arf alterations synergistically promote the development of an aggressive lymphoid leukemia. Ikzf1 alterations were associated with acquisition of stem cell-like features, including self-renewal and increased bone marrow stromal adhesion. Rexinoid receptor agonists reversed this phenotype, in part by inducing expression of IKZF1, resulting in abrogation of adhesion and self-renewal, cell cycle arrest and attenuation of proliferation without direct cytotoxicity. Retinoids potentiated the activity of dasatinib in mouse and human BCR-ABL1 ALL, providing a new therapeutic option in IKZF1-mutated ALL. Significance: The outcome of therapy for high-risk acute lymphoblastic leukemia remains suboptimal despite contemporary chemotherapy and the advent of targeted therapeutic approaches. Recent genomic studies have identified deletions or mutations of IKZF1 as a hallmark of high-risk ALL, but an understanding of how IKZF1 alteration contribute to leukemia development are lacking. Here we show that IKZF1 alterations drive lymphoid lineage, a stem cell-like phenotype, abnormal bone marrow adhesion, and poor responsiveness to tyrosine kinase inhibitor (TKI) therapy. Using a high-content screen, we show that retinoids reverse this phenotype in part by inducing expression of wild type IKZF1, and increase responsiveness to TKIs. These findings provide new insight into the pathogenesis of high-risk ALL and potential new therapeutic approaches. Pre-B mRNA profiles of p185 MIG and IK6 cells, DMSO or drug treated, in 3 or 4 replicates, using Illumina HiSeq 2500.
2015-09-04 | E-GEOD-68391 | biostudies-arrayexpress
Project description:The IKZF1 gene encodes IKAROS – a DNA binding protein that acts as a tumor suppressor in T-cell acute lymphoblastic leukemia (T-ALL). IKAROS can act as a transcriptional repressor via chromatin remodeling, however the mechanisms through which Ikaros exerts its tumor suppressor function via heterochromatin in T-ALL are largely unknown. We studied human and mouse T-ALL using loss-of-function and Ikzf1 re-expression approach, along with Ikzf1-wildtype primary human and mouse T-ALL and thymocytes to establish the role of Ikaros and Ikaros-associated protein histone deacetylase 1 (HDAC1) in global regulation of facultative heterochromatin and transcriptional repression in T-ALL. Results identified novel Ikaros and HDAC1 functions in T-ALL: Ikaros and HDAC1 are essential for EZH2 histone methyltransferase activity, and formation of facultative heterochromatin; Recruitment of HDAC1 by Ikaros is critical for establishment of H3K27me3 and repression of active enhancers; and Ikaros-HDAC1 complexes promote formation and expansion of H3K27me3 large organized chromatin lysine domains (LOCKs) and broad genic repression domains (BGRDs) in T-ALL. Our results establish that Ikaros’ tumor suppressor function in T-ALL occurs via activation of EZH2 and HDAC1 function, global regulation of the facultative heterochromatin landscape and silencing of active enhancers that regulate oncogene expression.
2024-10-01 | GSE261181 | GEO
Project description:The IKZF1 gene encodes IKAROS – a DNA binding protein that acts as a tumor suppressor in T-cell acute lymphoblastic leukemia (T-ALL). IKAROS can act as a transcriptional repressor via chromatin remodeling, however the mechanisms through which Ikaros exerts its tumor suppressor function via heterochromatin in T-ALL are largely unknown. We studied human and mouse T-ALL using loss-of-function and Ikzf1 re-expression approach, along with Ikzf1-wildtype primary human and mouse T-ALL and thymocytes to establish the role of Ikaros and Ikaros-associated protein histone deacetylase 1 (HDAC1) in global regulation of facultative heterochromatin and transcriptional repression in T-ALL. Results identified novel Ikaros and HDAC1 functions in T-ALL: Ikaros and HDAC1 are essential for EZH2 histone methyltransferase activity, and formation of facultative heterochromatin; Recruitment of HDAC1 by Ikaros is critical for establishment of H3K27me3 and repression of active enhancers; and Ikaros-HDAC1 complexes promote formation and expansion of H3K27me3 large organized chromatin lysine domains (LOCKs) and broad genic repression domains (BGRDs) in T-ALL. Our results establish that Ikaros’ tumor suppressor function in T-ALL occurs via activation of EZH2 and HDAC1 function, global regulation of the facultative heterochromatin landscape and silencing of active enhancers that regulate oncogene expression.
2024-10-01 | GSE261180 | GEO
Project description:Ikaros is an essential regulator of lymphopoiesis. Here, we studied the B-cell-specific function of Ikaros by conditional Ikzf1 inactivation in pro-B cells. B-cell development was arrested at an aberrant ‘pro-B’ cell stage characterized by increased cell adhesion and loss of pre-B cell receptor signaling. Ikaros was found to activate genes coding for pre-BCR signal transducers and to repress genes involved in the downregulation of pre-BCR signaling and upregulation of the integrin signaling pathway. Unexpectedly, derepression of Aiolos expression could not compensate for the loss of Ikaros in pro-B cells. Ikaros differentially controlled active chromatin at promoters and enhancers of repressed and activated target genes. Notably, Ikaros binding and target gene expression was dynamically regulated at distinct stages of early B-lymphopoiesis. 16 RNA-Seq samples in pre-proB cells (4 replicates, for each 2 controls and 2 experimental samples); 4 RNA-Seq samples in pro-B cells in Rag2-/- backgrounds (Ikzf1 deleted versus non deleted, 2 replicates each); 4 RNA-Seq samples in c-Kit high pro-B cells (Ikzf1 deleted versus non deleted, 2 replicates each); 4 RNA-Seq samples in pro-B cells (Ikzf1 deleted versus non deleted, 2 replicates each); 2 RNA-Seq samples pre-B cells wild type; 8 chromatin ChIP-Seq samples (4x H3K9ac, 4x H3K4me3, Ikzf1 deleted/non deleted, two replicates each).; 4 Transcription factor ChIP-Seq samples in pro-B cells; 1 Transcription factor ChIP-Seq samples in DP-T cells; 1 Transcription factor ChIP-Seq samples in pre-pro-B cells; 2 Mi-2b Chip-Seq samples (Ikzf1 deleted versus non deleted); 1 ChIP-Seq input track for pro-B cells; 1 ChIP-Seq input track for DP-T cells
2014-02-09 | E-GEOD-53595 | biostudies-arrayexpress
Project description:Alterations of IKZF1, encoding the lymphoid transcription factor IKAROS, are a hallmark of high risk acute lymphoblastic leukemia (ALL), however the role of IKZF1 alterations in ALL pathogenesis is poorly understood. Here we show that in mouse models of BCR-ABL1 leukemia, Ikzf1 and Arf alterations synergistically promote the development of an aggressive lymphoid leukemia. Ikzf1 alterations were associated with acquisition of stem cell-like features, including self-renewal and increased bone marrow stromal adhesion. Rexinoid receptor agonists reversed this phenotype, in part by inducing expression of IKZF1, resulting in abrogation of adhesion and self-renewal, cell cycle arrest and attenuation of proliferation without direct cytotoxicity. Retinoids potentiated the activity of dasatinib in mouse and human BCR-ABL1 ALL, providing a new therapeutic option in IKZF1-mutated ALL. Significance: The outcome of therapy for high-risk acute lymphoblastic leukemia remains suboptimal despite contemporary chemotherapy and the advent of targeted therapeutic approaches. Recent genomic studies have identified deletions or mutations of IKZF1 as a hallmark of high-risk ALL, but an understanding of how IKZF1 alteration contribute to leukemia development are lacking. Here we show that IKZF1 alterations drive lymphoid lineage, a stem cell-like phenotype, abnormal bone marrow adhesion, and poor responsiveness to tyrosine kinase inhibitor (TKI) therapy. Using a high-content screen, we show that retinoids reverse this phenotype in part by inducing expression of wild type IKZF1, and increase responsiveness to TKIs. These findings provide new insight into the pathogenesis of high-risk ALL and potential new therapeutic approaches.
2015-09-04 | GSE68391 | GEO
Project description:Enhancers play key roles in gene regulation. However, comprehensive enhancer discovery is challenging because most enhancers, especially those affected in complex diseases, have weak effects on gene expression. Through gene regulatory network modeling, we identified that dynamic cell state transitions, a critical missing component in prevalent enhancer discovery strategies, can be utilized to improve the cells’ sensitivity to enhancer perturbation. Guided by the modeling results, we performed a mid-transition CRISPRi-based enhancer screen utilizing human embryonic stem cell definitive endoderm differentiation as a dynamic transition system. The screen discovered a comprehensive set of enhancers (4 to 9 per locus) for each of the core lineage-specifying transcription factors (TFs), including many enhancers with weak to moderate effects. Integrating the screening results with enhancer activity measurements (ATAC-seq, H3K27ac ChIP-seq) and three-dimensional enhancer-promoter interaction information (CTCF looping, Hi-C), we were able to develop a CTCF loop-constrained Interaction Activity (CIA) model that can better predict functional enhancers compared to models that rely on Hi-C-based enhancer-promoter contact frequency. Together, our dynamic network-guided enhancer screen and the CIA enhancer prediction model provide generalizable strategies for sensitive and more comprehensive enhancer discovery in both normal and pathological cell state transitions.
2023-06-17 | PXD043070 | Pride
Project description:Genome-wide association studies have identified statistically significant associations between genetic variants in or near the IKZF1 gene and several autoimmune disorders. IKZF1, encoding the transcription factor Ikaros, produces at least 10 distinct transcripts via alternative splicing. To explore the role of alternative splicing of IKZF1 in mature T cells, we generated a panel of Jurkat T-cell clones with various truncating mutations in IKZF1 exon 4, exon 6 or both. Differences among clones in gene expression, chromatin accessibility, and protein abundance were assessed by RNA-seq, ATAC-seq and immunoblotting. Clones with single targeting events in either exon 4 or 6 clustered separately from double-targeted clones on multiple parameters, but overall, clone responses were highly heterogeneous. Perturbation of IKZF1 splicing resulted in significant differences in expression and chromatin accessibility of other autoimmunity-associated genes and elicited compensatory expression changes in other IKZF family members. Our results suggest that even modest perturbations of IKZF1 splicing can have significant effects on gene expression and function in mature T cells.
2024-06-01 | GSE255337 | GEO
Project description:Genome-wide association studies have identified statistically significant associations between genetic variants in or near the IKZF1 gene and several autoimmune disorders. IKZF1, encoding the transcription factor Ikaros, produces at least 10 distinct transcripts via alternative splicing. To explore the role of alternative splicing of IKZF1 in mature T cells, we generated a panel of Jurkat T-cell clones with various truncating mutations in IKZF1 exon 4, exon 6 or both. Differences among clones in gene expression, chromatin accessibility, and protein abundance were assessed by RNA-seq, ATAC-seq and immunoblotting. Clones with single targeting events in either exon 4 or 6 clustered separately from double-targeted clones on multiple parameters, but overall, clone responses were highly heterogeneous. Perturbation of IKZF1 splicing resulted in significant differences in expression and chromatin accessibility of other autoimmunity-associated genes and elicited compensatory expression changes in other IKZF family members. Our results suggest that even modest perturbations of IKZF1 splicing can have significant effects on gene expression and function in mature T cells.
2024-06-01 | GSE252707 | GEO
Project description:Alterations of IKZF1, encoding the lymphoid transcription factor IKAROS, are a hallmark of high risk acute lymphoblastic leukemia (ALL), however the role of IKZF1 alterations in ALL pathogenesis is poorly understood. Here we show that in mouse models of BCR-ABL1 leukemia, Ikzf1 and Arf alterations synergistically promote the development of an aggressive lymphoid leukemia. Ikzf1 alterations were associated with acquisition of stem cell-like features, including self-renewal and increased bone marrow stromal adhesion. Rexinoid receptor agonists reversed this phenotype, in part by inducing expression of IKZF1, resulting in abrogation of adhesion and self-renewal, cell cycle arrest and attenuation of proliferation without direct cytotoxicity. Retinoids potentiated the activity of dasatinib in mouse and human BCR-ABL1 ALL, providing a new therapeutic option in IKZF1-mutated ALL. Significance: The outcome of therapy for high-risk acute lymphoblastic leukemia remains suboptimal despite contemporary chemotherapy and the advent of targeted therapeutic approaches. Recent genomic studies have identified deletions or mutations of IKZF1 as a hallmark of high-risk ALL, but an understanding of how IKZF1 alteration contribute to leukemia development are lacking. Here we show that IKZF1 alterations drive lymphoid lineage, a stem cell-like phenotype, abnormal bone marrow adhesion, and poor responsiveness to tyrosine kinase inhibitor (TKI) therapy. Using a high-content screen, we show that retinoids reverse this phenotype in part by inducing expression of wild type IKZF1, and increase responsiveness to TKIs. These findings provide new insight into the pathogenesis of high-risk ALL and potential new therapeutic approaches.
2015-09-04 | GSE54821 | GEO
Project description:The transcription factor IKZF1/Ikaros is essential for B cell development, and recurrently mutated in human B-ALL. Ikaros has been ascribed both activating and repressive functions via interactions with coactivator and corepressor complexes, but the relative abundance of Ikaros-associated coregulatory complexes and their contribution to Ikaros-mediated gene regulation are not well understood. To address this issue, we performed an unbiased identification of Ikaros-interacting proteins in pre-B cells, and found that Ikaros interacts overwhelmingly with corepressors and heterochromatin-associated proteins. Time-resolved analysis of transcription and chromatin state identified transcriptional repression as the immediate response to Ikaros induction. Transcriptional repression preceded transcriptional activation by several hours, and was accompanied by a rapid loss of chromatin accessibility and reduced levels of H3K27ac particularly at enhancers. Functional characterisation of intrinsically disordered regions in the Ikaros protein identified highly conserved helical motifs that mediate Ikaros association with the NuRD corepressor complex and contribute to the silencing of target genes in pre-B cells and antiproliferative functions of Ikaros in human B-ALL
2024-10-23 | PXD050989 | Pride