Project description:In mice lacking the heme exporter, FLVCR, differentiation fails at the CFU-E/proerythroblast stage from excessive heme and reactive oxygen species. We show that Flvcr1-deleted CFU-E/proerythroblasts have low GATA1 mRNA and GATA1-target gene mRNAs along with increased ribosomal protein mRNAs as a direct result of increased heme. Thus heme increases ribosomal protein transcription when globin production needs to be increased, and when heme is excessive, GATA1 is reduced allowing for normal termination of erythroid differentiation. This demonstrates that heme and GATA1 are co-master regulators of erythroid differentiation.
Project description:In mice lacking the heme exporter, FLVCR, differentiation fails at the CFU-E/proerythroblast stage from excessive heme and reactive oxygen species. We show that Flvcr1-deleted CFU-E/proerythroblasts have low GATA1 mRNA and GATA1-target gene mRNAs along with increased ribosomal protein mRNAs as a direct result of increased heme. Thus heme increases ribosomal protein transcription when globin production needs to be increased, and when heme is excessive, GATA1 is reduced allowing for normal termination of erythroid differentiation. This demonstrates that heme and GATA1 are co-master regulators of erythroid differentiation.
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.
Project description:Nuclear receptor binding SET domain protein 1 (NSD1) is recurrently mutated in human cancers including acute leukemia. We found that NSD1 knockdown altered erythroid clonogenic growth of human CD34+ hematopoietic cells. Ablation of Nsd1 in the hematopoietic system induced a transplantable erythroleukemia in mice. Despite abundant expression of the transcriptional master regulator GATA1, in vitro differentiation of Nsd1-/- erythroblasts was majorly impaired associated with reduced activation of GATA1-induced targets, while GATA1-repressed target genes were less affected. Retroviral expression of wildtype Nsd1, but not a catalytically-inactive Nsd1N1918Q SET-domain mutant induced terminal maturation of Nsd1-/- erythroblasts. Despite similar GATA1 levels, exogenous Nsd1 but not Nsd1N1918Q significantly increased GATA1 chromatin occupancy and target gene activation. Notably, Nsd1 expression reduced the association of GATA1 with the co-repressor SKI, and knockdown of SKI induced differentiation of Nsd1-/- erythroblasts. Collectively, we identified the NSD1 methyltransferase as a novel regulator of GATA1-controlled erythroid differentiation and leukemogenesis.
Project description:Mammalian erythroid cells development can be divided into three period: hematopoietic stem and progenitor cells (HSPC), erythroid progenitor (Ery-Pro) and erythroid precursor (Ery-Pre). To better understand human erythropoiesis and its regulation, we performed genome-wide studies of chromatin architecture, enhancer and select transcription factors binding, and transcriptomics profiling utilizing modified strategy to obtain defined progenitor and precursor populations from primary human erythroid cells. Integration and analysis of these data reveals that the TAD structure is stable but promoter - enhancer interactions are highly dynamic in a stage specific manner. Erythroid master regulator - GATA1 involves in the P-E interactions stepwisely. GATA1 binding is largely stable in erythroid progenitor and precursor, but dynamic GATA1 binding during this process regulate a productive erythroid gene expression and local chromatin rewiring. Additionally, we also have showed that dosage of GATA1 control the erythroid progenitor behavior and the erythroid progression. The valuable chromatin architecture and epigenome data will provide more comprehensive insight of human erythropoiesis and dynamic gene regulation of cellular differentiation even more broadly.