Project description:Analysis of hematopoietic stem/progenitors from GATA-1-GFP transgenic mouse bone marrow at gene expression level. Results provide changes in gene expression pattern accompanied with up-regulation of GATA-1 transcription factor at early stage of murine adult hematopoiesis. RNA samples obtained from isolated GATA1+LSK and other hemaopoietic stem/progenitor populations including GATA1-LSK, LMPP, CMP and LT-HSC were subjected to mRNA amplification and cDNA microarray analysis.
Project description:Analysis of hematopoietic stem/progenitors from GATA-1-GFP transgenic mouse bone marrow at gene expression level. Results provide changes in gene expression pattern accompanied with up-regulation of GATA-1 transcription factor at early stage of murine adult hematopoiesis.
Project description:Embryonic stem (ES) and induced pluripotent stem (iPS) cells represent a potential source of megakaryocytes and platelets for transfusion therapies. However, most current ES/iPS cell differentiation protocols are limited by low yields of hematopoietic progeny. Mutations in the mouse and human genes encoding transcription factor GATA1 cause accumulation of proliferating, developmentally arrested megakaryocytes. To exploit this clinical observation, we engineered wildtype (WT) murine ES cells to express doxycycline (dox)-regulated Gata1 short hairpin (sh) RNAs. In vitro differentiation with dox and thrombopoietin (Tpo) resulted in approximately 1013-fold expansion of immature hematopoietic progenitors. Upon dox withdrawal with multilineage cytokines, GATA1 expression was restored and the cells differentiated into erythroblasts and megakaryocytes. With Tpo alone, dox-deprived progenitors formed mainly mature megakaryocytes that generated functional platelets in vivo. Our findings provide a novel, readily reproducible strategy to expand ES-cell derived megakaryocyte-erythroid progenitors and direct their differentiation into megakaryocytes producing functional platelets in clinically relevant numbers. 3 classes of samples were compared 1) fetal liver derived megkaryocytes 2) G1ME (Gata1â megakaryocyte-erythroid) 3) G1ME2 (engineered wildtype (WT) murine ES cells to express doxycycline (dox)-regulated Gata1 short hairpin (sh) RNAs)
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, SCL/TAL1 and FLI1) and three diagnostic histone modification marks with the gene expression changes that occur during development of primary megakaryocytes (MEG) and 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, SCL/TAL1, FLI1, ERG, RUNX1, LMO2) binding to MEG-specific cis-regulatory modules in multipotential hematopoietic 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 occurs 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 precursor via overlapping and divergent functions of shared hematopoietic transcription factors. Gene expression changes during the development of primary megakaryocytes (MEG) and erythroblasts (ERY) from murine fetal liver hematopoietic stem/progenitor cells
Project description:We observe that HoxA3 represses hematopoieis by the repression of several transcription factors including Runx1 and Gata1. Up regulation of either Runx1 or Gata1 in the presence of HoxA3 reverted the hematopoietic repression. We have performed full genome analysis to determine the molecular signature of hematopoietic development in response to upregulation of Runx1 and Gata1. Endothelial progenitors were sorted from HoxA3 induced EBs, transduced with either control vector (control), Runx1 vector or Gata1 vector. Cells were co-cultured on Op9 for 5 days: in the following conditions: Control, HoxA3 upregulation, HoxA3 + Runx1 upregulation, HoxA3 + Gata1 upregulation in triplicate. After 5 days of culture,transduced cells were sorted (5000 cells) and prepared for microarray.
Project description:Loss of immune function and an increased incidence of myeloid leukemia are two of the most clinically significant consequences of aging of the hematopoietic system. To better understand the mechanisms underlying hematopoietic aging, we evaluated the cell intrinsic functional and molecular properties of highly purified long-term hematopoietic stem cells (LT-HSCs) from young and old mice. We found that LT-HSC aging was accompanied by cell autonomous changes, including increased stem cell self-renewal, differential capacity to generate committed myeloid and lymphoid progenitors, and diminished lymphoid potential. Expression profiling revealed that LT-HSC aging was accompanied by the systemic down-regulation of genes mediating lymphoid specification and function and up-regulation of genes involved in specifying myeloid fate and function. Moreover, LT-HSCs from old mice expressed elevated levels of many genes involved in leukemic transformation. These data support a model in which age-dependent alterations in gene expression at the stem cell level presage downstream developmental potential and thereby contribute to age-dependent immune decline, and perhaps also to the increased incidence of leukemia in the elderly.
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:Embryonic stem (ES) and induced pluripotent stem (iPS) cells represent a potential source of megakaryocytes and platelets for transfusion therapies. However, most current ES/iPS cell differentiation protocols are limited by low yields of hematopoietic progeny. Mutations in the mouse and human genes encoding transcription factor GATA1 cause accumulation of proliferating, developmentally arrested megakaryocytes. To exploit this clinical observation, we engineered wildtype (WT) murine ES cells to express doxycycline (dox)-regulated Gata1 short hairpin (sh) RNAs. In vitro differentiation with dox and thrombopoietin (Tpo) resulted in approximately 1013-fold expansion of immature hematopoietic progenitors. Upon dox withdrawal with multilineage cytokines, GATA1 expression was restored and the cells differentiated into erythroblasts and megakaryocytes. With Tpo alone, dox-deprived progenitors formed mainly mature megakaryocytes that generated functional platelets in vivo. Our findings provide a novel, readily reproducible strategy to expand ES-cell derived megakaryocyte-erythroid progenitors and direct their differentiation into megakaryocytes producing functional platelets in clinically relevant numbers.
Project description:Loss of immune function and an increased incidence of myeloid leukemia are two of the most clinically significant consequences of aging of the hematopoietic system. To better understand the mechanisms underlying hematopoietic aging, we evaluated the cell intrinsic functional and molecular properties of highly purified long-term hematopoietic stem cells (LT-HSCs) from young and old mice. We found that LT-HSC aging was accompanied by cell autonomous changes, including increased stem cell self-renewal, differential capacity to generate committed myeloid and lymphoid progenitors, and diminished lymphoid potential. Expression profiling revealed that LT-HSC aging was accompanied by the systemic down-regulation of genes mediating lymphoid specification and function and up-regulation of genes involved in specifying myeloid fate and function. Moreover, LT-HSCs from old mice expressed elevated levels of many genes involved in leukemic transformation. These data support a model in which age-dependent alterations in gene expression at the stem cell level presage downstream developmental potential and thereby contribute to age-dependent immune decline, and perhaps also to the increased incidence of leukemia in the elderly. 3 old mice and 5 young mice were assayed
Project description:This SuperSeries is composed of the SubSeries listed below. Germline GATA1 mutations resulting in the production of an amino-truncated protein termed GATA1s (for M-bM-^@M-^\shortM-bM-^@M-^]) cause congenital hypoplastic anemia. Similar somatic mutations promote transient myeloproliferative disease and acute megakaryoblastic leukemia in trisomy 21 patients. Here we show that induced pluripotent stem cells (iPSCs) from patients with GATA1-truncating mutations exhibit impaired erythroid potential but enhanced megakaryopoiesis and myelopoiesis, faithfully recapitulating the major phenotypes of associated diseases. Similarly, GATA1s promotes megakaryopoiesis but not erythropoiesis in developmentally arrested Gata1- murine megakaryocyte-erythroid progenitors derived from murine embryonic stem cells (ESCs). Transcriptome studies demonstrate a selective deficiency in the ability of GATA1s to activate erythroid-expressed genes within populations of hematopoietic progenitors. Although its DNA binding domain is intact, chromatin immunoprecipitation studies show that GATA1s binding at specific erythroid regulatory regions is impaired, while binding at many non-erythroid sites, including megakaryocytic and myeloid target genes, is normal. These observations point to lineage specific GATA1 co-factor associations essential for normal chromatin occupancy and provide mechanistic insights into how GATA1s mutations cause human disease. More broadly, our studies underscore the value of ESCs and iPSCs to recapitulate and study disease phenotypes. Refer to individual Series