Project description:Human erythropoiesis is a stepwise process in which multipotent hematopoietic stem/progenitor cells (HSPC) are initially committed towards the erythroid lineage and then differentiated into mature erythroid precursors. Commitment and differentiation are tightly regulated by the coordinated action of a host of transcription factors, including GATA2 and GATA1. Although the role of GATA factors in erythropoiesis has been extensively studied, how they regulate transcription from early to late stages of human erythropoiesis still remains underinvestigated. Here, we investigated GATA-mediated transcriptional regulation along erythroid development through the integrative analysis of gene expression, chromatin modifications, and GATA factors’ binding in human HSPC, early erythroid progenitors, and late precursors. A progressive loss of H3K27 acetylation, a mark of active regulatory elements, and diminished usage of active enhancers and super-enhancers was observed during erythroid lineage commitment and differentiation. We found that GATA factors mediate the transcriptional changes occurring during erythropoiesis through a stage-specific interplay with regulatory elements. In particular, GATA1 binds different sets of regulatory elements in early progenitors and late precursors, and controls the transcription of distinct genes in commitment and differentiation. By Chromosome Conformation Capture and CRISPR/Cas9-mediated genome editing, we demonstrated that the binding of GATA1 to a stage-specific super-enhancer sustains the expression of the stem cell factor receptor KIT in human erythroid progenitors. This study provides insights into the dynamics of epigenetic and transcriptional interactions during erythroid development and highlights a new layer of GATA1-mediated regulation in erythropoiesis.
Project description:Human erythropoiesis is a stepwise process in which multipotent hematopoietic stem/progenitor cells (HSPC) are initially committed towards the erythroid lineage and then differentiated into mature erythroid precursors. Commitment and differentiation are tightly regulated by the coordinated action of a host of transcription factors, including GATA2 and GATA1. Although the role of GATA factors in erythropoiesis has been extensively studied, how they regulate transcription from early to late stages of human erythropoiesis still remains underinvestigated. Here, we investigated GATA-mediated transcriptional regulation along erythroid development through the integrative analysis of gene expression, chromatin modifications, and GATA factors’ binding in human HSPC, early erythroid progenitors, and late precursors. A progressive loss of H3K27 acetylation, a mark of active regulatory elements, and diminished usage of active enhancers and super-enhancers was observed during erythroid lineage commitment and differentiation. We found that GATA factors mediate the transcriptional changes occurring during erythropoiesis through a stage-specific interplay with regulatory elements. In particular, GATA1 binds different sets of regulatory elements in early progenitors and late precursors, and controls the transcription of distinct genes in commitment and differentiation. By Chromosome Conformation Capture and CRISPR/Cas9-mediated genome editing, we demonstrated that the binding of GATA1 to a stage-specific super-enhancer sustains the expression of the stem cell factor receptor KIT in human erythroid progenitors. This study provides insights into the dynamics of epigenetic and transcriptional interactions during erythroid development and highlights a new layer of GATA1-mediated regulation in erythropoiesis.
Project description:The transcription factor GATA-1 is essential for erythroid and megakaryocytic cell differentiation and maturation. Previous reports show that GATA-1 is modulated through acetylation modification and through FOG-1 mediated indirect intereaction with HDAC1/2 containing NuRD corepressor complexes. In this study, we found that NuRD does not deacetylate GATA-1. However, HDAC1 alone can efficiently deacetylates GATA-1 and the direct interaction of HDAC1 and GATA-1 is required for the deacetylation. Two arginines within GATA-1 linker region are important for this interaction and arginine to alanine mutations (2RA mutant) largely reduces GATA-1 binding to HDAC1 in FOG-1 independent manner. GATA-1 2RA mutant were then introduced into G1E cells, a GATA-1-null erythroid progenitor cells. The 2RA mutant is acetylated but fails to induce erythroid differentiation. Gene expression analysis shows that GATA-1 2RA mutant affects GATA-1 function in both GATA-1 activated and repressed genes. The gene expression pattern partially overlap with gene expression profile of GATA-1V205M, a GATA-1 mutant with defective FOG-1 binding. ChIP-seq analysis further reveal that 2RA mutation largely reduced GATA-1 chromatin binding, most profoundly at gene promoter regions. HDAC1 recruitment on those promoters are also strongly reduced. These results revealed that GATA-1 recruits HDAC1 to GATA-1 regulated gene promoters and HDAC1 is required for GATA-1 mediated transcription regulation.
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:Nutrient-dependent gene regulation critically contributes to homeostatic control of animal physiology in changing nutrient landscape. In Drosophila, dietary sugars activate transcription factors (TFs), such as Mondo-Mlx, Sugarbabe and Cabut, which control metabolic gene expression to mediate physiological adaptation to high sugar diet. TFs that correspondingly control sugar responsive metabolic genes under conditions of low dietary sugar remain, however, poorly understood. We have used de novo motif prediction to uncover a significant over-representation of GATA-like motifs on the promoters of sugar-responsive genes in Drosophila larvae. GATA TF Grain was found to contribute to the regulation of sugar-responsive genes, and consequently to central carbon and lipid metabolism, primarily on low sugar diet. Grain targets include known sugar responsive TFs, cabut and smad on X (smox). Moreover, Grain promotes the expression of genes involved in de novo lipogenesis. Grain chromatin binding sites significantly converge with those of Sugarbabe. Grain and Sugarbabe both activate lipogenic genes, but display functional predominance on low and high sugar conditions, respectively. Collectively, our data provides evidence for a metazoan GATA transcription factor in nutrient-responsive metabolic regulation in vivo.