Project description:The transcription factor GATA-1 is required for terminal erythroid maturation and functions as an activator or repressor depending on gene context. Yet its in vivo site selectivity and ability to distinguish between activated versus repressed genes remain incompletely understood. In this study, we performed GATA-1 ChIP-seq in erythroid cells and compared it to GATA-1-induced gene expression changes. Bound and differentially expressed genes contain a greater number of GATA-binding motifs, a higher frequency of palindromic GATA sites, and closer occupancy to the transcriptional start site versus nondifferentially expressed genes. Moreover, we show that the transcription factor Zbtb7a occupies GATA-1-bound regions of some direct GATA-1 target genes, that the presence of SCL/TAL1 helps distinguish transcriptional activation versus repression, and that polycomb repressive complex 2 (PRC2) is involved in epigenetic silencing of a subset of GATA-1-repressed genes. These data provide insights into GATA-1-mediated gene regulation in vivo. Keywords: Gene regulation Examination of GATA-1 occupancy in MEL cell line.
Project description:The transcription factor GATA-1 is required for terminal erythroid maturation and functions as an activator or repressor depending on gene context. Yet its in vivo site selectivity and ability to distinguish between activated versus repressed genes remain incompletely understood. In this study, we performed GATA-1 ChIP-seq in erythroid cells and compared it to GATA-1-induced gene expression changes. Bound and differentially expressed genes contain a greater number of GATA-binding motifs, a higher frequency of palindromic GATA sites, and closer occupancy to the transcriptional start site versus nondifferentially expressed genes. Moreover, we show that the transcription factor Zbtb7a occupies GATA-1-bound regions of some direct GATA-1 target genes, that the presence of SCL/TAL1 helps distinguish transcriptional activation versus repression, and that polycomb repressive complex 2 (PRC2) is involved in epigenetic silencing of a subset of GATA-1-repressed genes. These data provide insights into GATA-1-mediated gene regulation in vivo. Keywords: Gene regulation
Project description:There are many examples of transcription factor families whose members control gene expression profiles of diverse cell types. However, the mechanism by which closely related factors occupy distinct regulatory elements and impart lineage specificity is largely undefined. Here we demonstrate on a genome wide scale that the hematopoietic GATA factors GATA-1 and GATA-2 bind overlapping sets of genes, often at distinct sites, as a means to differentially regulate target gene expression and to regulate the balance between proliferation and differentiation. We also reveal that the GATA switch, which entails a chromatin occupancy exchange between GATA2 and GATA1 in the course of differentiation, operates on more than a third of GATA1 bound genes. The switch is equally likely to lead to transcriptional activation or repression and, in general, GATA1 and GATA2 act oppositely on switch target genes. In addition, we reveal that genomic regions co-occupied by GATA2 and the ETS factor ETS1 are strongly enriched for regions marked by H3K4me3 and occupied by Pol II. Finally, by comparing GATA1 occupancy in erythroid cells and megakaryocytes, we find that the presence of ETS factor motifs is a major discriminator of megakaryocyte versus red cell specification.
Project description:We report ChIP-Seq data for GATA-1 and the FOG-binding mutant of GATA-1 (GATA-1^V205G) in G1ME cells, a Gata1-null cell line with both erythroid and megakaryocytic differentiation potential. We introduced HA-tagged GATA-1 or V205G into G1ME cells via retroviral transduction. The cells were crosslinked at 48h post-transduction, and an HA antibody was used for chromatin immunoprecipitation (ChIP). ChIP and input samples were sequenced on Illumina GAII high-throughput sequencer. The data reveal GATA-1-specific and V205G-specific bidning sites, indicating that FOG-1 both faacilitates and prohibits GATA-1 chromatin occupancy in a context-dependent manner. Examinaton of chromatin occupancy of GATA-1 anda FOG-binding mutant of GATA-1 in G1ME cells cultured in TPO.
Project description:There are many examples of transcription factor families whose members control gene expression profiles of diverse cell types. However, the mechanism by which closely related factors occupy distinct regulatory elements and impart lineage specificity is largely undefined. Here we demonstrate on a genome wide scale that the hematopoietic GATA factors GATA-1 and GATA-2 bind overlapping sets of genes, often at distinct sites, as a means to differentially regulate target gene expression and to regulate the balance between proliferation and differentiation. We also reveal that the GATA switch, which entails a chromatin occupancy exchange between GATA2 and GATA1 in the course of differentiation, operates on more than a third of GATA1 bound genes. The switch is equally likely to lead to transcriptional activation or repression and, in general, GATA1 and GATA2 act oppositely on switch target genes. In addition, we reveal that genomic regions co-occupied by GATA2 and the ETS factor ETS1 are strongly enriched for regions marked by H3K4me3 and occupied by Pol II. Finally, by comparing GATA1 occupancy in erythroid cells and megakaryocytes, we find that the presence of ETS factor motifs is a major discriminator of megakaryocyte versus red cell specification. We used Illumina ChIP-Seq to examine binding of GATA1, GATA2, and ETS1 transcription factors as well as the genomic locations of two histone methylation marks, H3K4me3 and H3K27me3. Except H3K4me3 (1 sample), all data were generated from at least 2 biological replicates of immunoprecipitations from megakaryocyte progenitor cells, G1ME. Input DNA was prepared and sequenced along with each immunoprecipitation and used as a control dataset for binding site identification.
Project description:Combinatorial actions of relatively few transcription factors control hematopoietic differentiation. To investigate this process in erythro-megakaryopoiesis, we correlated the genome-wide chromatin occupancy signatures of four master hematopoietic transcription factors (GATA1, GATA2, TAL1, and FLI1) and three diagnostic histone modification marks with the gene expression changes that occur during development of primary cultured megakaryocytes (MEG) and primary erythroblasts (ERY) from murine fetal liver hematopoietic stem/progenitor cells. We identified a robust, genome-wide mechanism of MEG-specific lineage priming by a previously described stem/progenitor cell-expressed transcription factor heptad (GATA2, LYL1, TAL1, FLI1, ERG, RUNX1, LMO2) binding to MEG-associated cis-regulatory modules (CRMs) in multipotential progenitors. This is followed by genome-wide GATA factor switching that mediates further induction of MEG-specific genes following lineage commitment. Interaction between GATA and ETS factors appears to be a key determinant of these processes. In contrast, ERY-specific lineage priming is biased toward GATA2-independent mechanisms. In addition to its role in MEG lineage priming, GATA2 plays an extensive role in late megakaryopoiesis as a transcriptional repressor at loci defined by a specific DNA signature. Our findings reveal important new insights into how ERY and MEG lineages arise from a common bipotential progenitor via overlapping and divergent functions of shared hematopoietic transcription factors. Genome-wide chromatin occupancy using ChIP-seq on 4 transcription factors (GATA1, GATA2, TAL1, and FLII) and three histone marks (H3K4me1, H3K4me3, and H3K27me3) in lineage-commited primary erythoblasts (ERY) and primary cultured megakaryocytes (MEG).
Project description:This SuperSeries is composed of the following subset Series: GSE35644: Genome-wide analysis of the role of FOG-1 in GATA-1 chromatin occupancy GSE35695: Differential gene regulation by disease-associated mutants of GATA-1 during megakaryocyte differentiation Refer to individual Series
Project description:In this project, we provide strong proteomic evidence for PcG interaction with classic co-activators, BRD4 and MOZ/MORF, captured on chromatin during embryogenesis in Drosophila, leading to a model in which developmental regulatory elements are universally ‘poised’ early in development via occupancy of composite protein complexes of PcG silencing proteins and classical co-activators. These bivalent protein interactions may resolve into full activation or repression, depending on the cell type-specific expression, binding, and function of transcription factors.
Project description:We report ChIP-Seq data for GATA-1 and the FOG-binding mutant of GATA-1 (GATA-1^V205G) in G1ME cells, a Gata1-null cell line with both erythroid and megakaryocytic differentiation potential. We introduced HA-tagged GATA-1 or V205G into G1ME cells via retroviral transduction. The cells were crosslinked at 48h post-transduction, and an HA antibody was used for chromatin immunoprecipitation (ChIP). ChIP and input samples were sequenced on Illumina GAII high-throughput sequencer. The data reveal GATA-1-specific and V205G-specific bidning sites, indicating that FOG-1 both faacilitates and prohibits GATA-1 chromatin occupancy in a context-dependent manner.
Project description:Interplays among lineage specific nuclear proteins, chromatin modifying enzymes and the basal transcription machinery govern cellular differentiation, but their dynamics of actions and coordination with transcriptional control are not fully understood. Alterations in chromatin structure appear to establish a permissive state for gene activation at some loci but they play an integral role in activation at other loci. To determine the predominant roles of chromatin states and factor occupancy in directing gene regulation during differentiation, we mapped chromatin accessibility, histone modifications, and nuclear factor occupancy genome-wide during mouse erythroid differentiation dependent on the master regulatory transcription factor GATA1. Remarkably, despite extensive changes in gene expression, the chromatin state profiles (proportions of a gene in a chromatin state dominated by activating or repressive histone modifications) and accessibility remain largely unchanged during GATA1-induced erythroid differentiation. In contrast, gene induction and repression are strongly associated with changes in patterns of transcription factor occupancy. Our results indicate that during erythroid differentiation, the broad features of chromatin states are established at the stage of lineage commitment, largely independently of GATA1. These determine permissiveness for expression, with subsequent induction or repression mediated by distinctive combinations of transcription factors. Using ChIP-Seq technology to examine DNase hypersensitivity, three transcription factors, and four histone modifications in Gata1-null murine G1E line and rescued G1E-ER4 subline, and also two of the transcription factors in mouse primary erythroblasts. ChIP input DNA was sequenced in each cell type as controls.