Expression data from G1E erythroid cells expressing GATA1 mutants
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ABSTRACT: Missense mutations in transcription factor GATA1 underlie several distinct forms of anemia and thrombocytopenia. Clinical severity depends on the site and type of substitution, and distinct substiutions of the same residue produce disparate phenotypes. To investigate the effect of GATA1 missense mutations on erythroid differentiation we expressed conditionally activated wild type or mutant versions of GATA1 in GATA1-null G1E cells. We used gene expression microarrays to explore how GATA1 missense mutations affect erythroid transcription programs. GATA1-null G1E cells ectopically expressing conditionally activated versions of GATA1 (GATA1-ER, GATA1(R216Q)-ER, GATA1(R216W)-ER, GATA1(D218G)-ER, or GATA1(D218Y)-ER) were treated with estradiol for 24 hours to initiate erythroid differentiation. Total RNA from treated cells was extracted for Affymetrix microarray. All data were generated from three biological replicates. Transcript levels were compared in wild type vs. mutant lines.
Project description:Missense mutations in transcription factor GATA1 underlie several distinct forms of anemia and thrombocytopenia. Clinical severity depends on the site and type of substitution, and distinct substiutions of the same residue produce disparate phenotypes. To investigate the effect of GATA1 missense mutations on erythroid differentiation we expressed conditionally activated wild type or mutant versions of GATA1 in GATA1-null G1E cells. We used gene expression microarrays to explore how GATA1 missense mutations affect erythroid transcription programs.
Project description:Analysis of erythroid differentiation using Gata1 gene-disrupted G1E ER4 clone cells. Estradiol addition activates an ectopically expressed Gata-1-estrogen receptor fusion protein, triggering synchronous differentiation. 30 hour time course corresponds roughly to late burst-forming unit-erythroid stage (t=0 hrs) through orthochromatic erythroblast stage (t=30 hrs). Experiment Overall Design: G1E ER4 cells cultured in G1E medium were treated at 6 time points with estradiol to initiate erythroid differentiation by activating Gata1 transcription factor and total RNAs from treated cells were extracted for microarray experiment. The erythroid differentiation status was confirmed by cell pellet color and expression of microRNA miR451. The design was similar to an earlier studies (Welch, J. J., Watts, J. A., Vakoc, C. R., Yao, Y., Wang, H., Hardison, R. C., Blobel, G. A., Chodosh, L. A., and Weiss, M. J. (2004)). Global regulation of erythroid gene expression by transcription factor GATA-1. Blood 104, 3136-3147), except that a more recent version of Affymetric chip was used to acheive greater transcriptome coverage.
Project description:Transcription factor GATA1 binding in erythroblasts in the presence and absence of BET inhibitor JQ1, and BET protein BRD3 and BRD4 binding in erythroblasts in the presence and absence of GATA1. Inhibitors of Bromodomain and Extra-Terminal motif proteins (BETs) are being evaluated for the treatment of cancer and other diseases yet their physiologic mechanisms remain largely unknown. We used genomic and genetic approaches to examine BET function in a hematopoietic maturation system driven by GATA1, an acetylated transcription factor previously shown to interact with BETs. We found that while BRD3 occupied the majority of GATA1 binding sites, BRD2 and BRD4 were also recruited to a subset of GATA1-occupied sites. Functionally, BET inhibition impaired GATA1-mediated transcriptional activation, but not repression, genome-wide. Co-activation by BETs was accomplished both by facilitating genomic occupancy of GATA1 and subsequently supporting transcription activation. Using a combination of CRISPR/CAS9-mediated genomic engineering and shRNA approaches we observed that depletion of either BRD2 or BRD4 alone blunted erythroid gene activation, while depletion of BRD3 only affected erythroid transcription in the setting of BRD2 deficiency. These results suggest that pharmacologic BET inhibition should be interpreted in the context of distinct steps in transcriptional activation and partially overlapping functions among BET family members. GATA1 null erythroblasts (G1E) conditionally expressing GATA1 as a GATA1-ER fusion protein were induced to express GATA1 by addition of 100nM estradiol for 24 hours. For GATA1 binding experiments this occurred in the absence or presence of 250nM JQ1. For BRD3 and BRD4 occupancy experiments G1E cells were compared to G1E cells with activated GATA1-ER fusion protein.
Project description:Erythroid development and differentiation from multiprogenitor cells to red blood cells requires precise transcriptional regulation. Key erythroid transcription factors, GATA1 and TAL1, co-operate, along with other proteins, to regulate many aspects of this process. How GATA1 and TAL1 are positionally organized with respect to each other and their cognate DNA binding site across the mouse genome remains unclear. We applied high resolution ChIP-exo to GATA1 and TAL1 to study their positional organization across the mouse genome during GATA1-dependent maturation. Two complementary methods, MultiGPS and peak-pairing, were used to determine high confidence binding locations by ChIP-exo. We identified ~10,000 GATA1 and ~15,000 TAL1 locations, which were essentially confirmed by ChIP-seq. Of these, ~4,000 locations were bound by both GATA1 and TAL1. About three-quarters of these were tightly linked (<40 bp away) to a partial E-box located 7-8 bp upstream of a WGATAA motif. Both TAL1 and GATA1 generated distinct characteristic ChIP-exo peaks around WGATAA motifs, that reflect on their positional arrangement within a complex. We show that TAL1 and GATA1 form a precisely organized complex at a compound motif consisting of a TG 7-8 bp upstream of a WGATAA motif across thousands of genomic locations. Genome wide analysis of GATA1 and TAL1 in G1E and G1E-ER4 cells using ChIP-exo experiments
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.
Project description:The ensemble of Foxo3-regulated genes in the erythroid G1E-ER-GATA-1 cell line was determined by knocking down Foxo3 using siRNA, and measuring genome wide transcription by microarray analysis G1E-ER-GATA-1 cells were treated with control or Foxo3-specific siRNA by nucleofection at t = 0 h and t = 24 h. At t = 24 h, cells were treated with M-CM-^_-estradiol to activate ER-GATA-1. RNA was harvested at t = 48 h and processed for microarray analysis.
Project description:We employed a gene complementation strategy combined with microarray screening to identify miRNAs involved in the formation of erythroid (red blood) cells. To search for GATA-1-regulated erythroid miRNAs, we used the Gata-1– erythroblast line G1E. These cells proliferate in culture as immature erythroid precursors and undergo terminal maturation when GATA-1 activity is restored. G1E-ER4 is a sub-line stably expressing an estrogen-activated form of GATA-1 (GATA-1 fused to the ligand binding domain of the estrogen receptor). Treatment of G1E-ER4 cells with estradiol induces a GATA-1-regulated program of gene expression with concomitant cellular maturation. We used a microarray to evaluate the expression of 292 different miRNAs in G1E-ER4 cells at 0 versus 24 hours after GATA-1 activation. Affymetrix gene expression profiling has previously been deposited (GEO accession no. GSE628). Keywords: microRNA analysis of a cell-line model of erythroid maturation Two condition experiment, 3 replicates each (independently grown and harvested) of untreated and estradiol-treated (24hrs) G1E-ER4 cells, which express an estrogen-responsive form of the GATA-1 transcription factor. Each sample is compared to a common reference sample, comprised of an equal mixture of all 6 experimental samples.
Project description:Tissue-specific transcription patterns are preserved throughout cell divisions to maintain lineage fidelity. We investigated whether transcription factor GATA1 plays a role in transmitting hematopoietic gene expression programs through mitosis when transcription is transiently silenced. Live cell imaging revealed that a fraction of GATA1 is retained focally within mitotic chromatin. ChIP-seq of highly purified mitotic cells uncovered that key hematopoietic regulatory genes are occupied by GATA1 in mitosis. The GATA1 co- regulators FOG1 and TAL1 dissociate from mitotic chromatin, suggesting that GATA1 functions as platform for their postmitotic recruitment. Mitotic GATA1 target genes tend to re-activate more rapidly upon entry into G1 than genes from which GATA1 dissociates. A novel system designed to destroy GATA1 specifically during mitosis revealed that mitotic occupancy is required for rapid target gene reactivation. These studies suggest a requirement of mitotic “bookmarking” by GATA1 for the faithful propagation of cell type-specific transcription programs through cell division GATA1 occupancy profiles in mitotic G1E-ER4 +E2 cells generated by ChIP-sequencing. ChIP input DNA was sequenced as control. Previously reported (GSE18164) GATA1 occupancy in asynchrnous G1E-ER4 +E2 cells was analysed and compared with mitotic GATA1 occupancy.
Project description:we mapped the locations of DNA segments occupied by GATA1 using chromatin immunoprecipitation (ChIP). We have produced genome-wide GATA1 ChIP datasets after restoration and activation in G1E-ER4 cells. we employed the sequence census methodology of ChIP-seq , using Illumina GA2 technology to produce 23 million reads (36 nucleotides long) uniquely mapped to the mouse genome (mm8 assembly) for the GATA1 ChIP DNA and 15 million mapped reads for the input DNA Examination of transcription factor GATA1 occupancy
Project description:Transcriptome analysis of effect of Lockd knockout on cells Many long non-coding (lnc) RNAs are reported to regulate gene expression and protein functions. However, the proportion of lncRNAs with biological activities among the thousands expressed in mammalian cells is controversial. We studied Lockd (Downstream of p27), a 434 bp polyadenylated lncRNA originating 4 kb 3â to the Cdkn1b gene. Heterozygous and homozygous deletion of the 25 kb Lockd locus reduced Cdkn1b transcription by approximately 35 and 70% respectively in a mouse erythroid cell line. In contrast, homozygous insertion of a polyadenylation cassette 80 bp downstream of the Lockd transcription start site reduced the entire lncRNA transcript level by > 90%, but had no effect on Cdkn1b transcription. The 5â region of the Lockd gene contains a DNase hypersensitive site, binds numerous transcription factors (TFs), and physically associates with the Cdkn1b promoter in chromosomal conformation capture (NG Capture-C) studies. Thus, the Lockd gene positively regulates Cdkn1b transcription through an enhancer-like cis element and not via the lncRNA transcript. These findings demonstrate that the biological functions of a lncRNA cannot be inferred simply from phenotypes that arise after deleting the corresponding genomic locus. We analyzed mouse G1E erythroid cell line clones with Control Lockd (C - 3 replicates) and with Lockd deletion with CRISPR (KO - 4 replicates) using Mouse Gene 2.0 ST Array platform (transcript version). Array data was processed by RMA algorithm.