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. 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:RP-LC-MS lipidomics data was collected to understand the role of GATA1 during erythroid maturation. GATA1 mutants and WT cells were treated with or without beta-estradiol. GATA1 mutant cells were additionally treated with or without 5-ALA.
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:RP-LC-MS lipidomics data was collected to understand the role of GATA1 during erythroid maturation. GATA1 mutants and WT cells were treated with or without beta-estradiol. GATA1 mutant cells were additionally treated with or without 5-ALA.
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: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:Gene expression during cellular differentiation is coordinated by combinatorial interactions between transcription factors (TFs) and cofactors at promoters and enhancers. The “master TF” GATA1 coordinates gene transcription in a subset of hematopoietic lineages, including erythroid, megakaryocytic, mast, and eosinophil, while repressing the development of other blood lineages. However, the specific cofactors required for GATA1-activated gene expression during hematopoiesis are incompletely defined. We identified the cofactor KMT2D, an H3K4 methyltransferase that collaborates with H3K27 acetyltransferases to activate transcription, in an unbiased CRISPR/Cas9 screen for epigenetic regulators of erythropoiesis. Loss of KMT2D in human erythroid precursors caused developmental arrest with impaired expression of numerous erythroid genes. Mechanistically, KMT2D colocalized with GATA1 on more than one thousand erythroid enhancers associated with over two hundred erythroid genes. In general, co-occupancy of GATA1 and KMT2D at erythroid enhancers was associated with stronger transcriptional activity than occupancy by GATA1 alone. Acute depletion of KMT2D in erythroid precursors caused rapid reductions of H3K4me1 and H3K27ac on a subset of GATA1-bound enhancers and impaired the expression of canonical erythroid genes, including ZFPM1, SLC4A1, and EPOR. Moreover, acute depletion of GATA1 or KMT2D individually caused downregulation of overlapping gene sets. Thus, KMT2D controls erythropoiesis by selectively activating GATA1-dependent erythroid enhancers. Our studies identify KMT2D as a novel cofactor for transcriptional activation by GATA1 during erythropoiesis. More generally, our findings demonstrate how a lineage-specific TF cooperates with a ubiquitous epigenetic regulator to drive lineage-specific gene expression during cellular differentiation.