Project description:This SuperSeries is composed of the following subset Series: GSE34537: Mesp1 induces a subset of hematopoietic-associated transcription factors in ES cell-derived Flk1+Tie2+ endothelium GSE34541: Identification of gene targets of Meis2 GSE34543: Identification of gene targets of Meis1 Refer to individual Series
Project description:Previously, we reported that the transcription factor Mesp1 promotes the cell fates of cardiomyocytes, smooth muscle, and vascular endothelium. Recently, hematopoietic stem cells (HSCs) were shown to derive from hemogenic endothelium. Since Mesp1 regulates development of endothelium, it potentially could influence gene expression related to hematopoietic development. Our present fate mapping study found that Mesp1-cre efficiently labeled hematopoietic lineages in vivo. This result suggested that Mesp1 might be expressed in progenitors of the hematopoietic system, such as hemogenic endothelium. To test this, we purified Flk1+ Tie2+ endothelium derived from differentiating ES cells with or without Mesp1 induction, and used microarray expression analysis to identify genes strongly up-regulated by Mesp1. Embryonic stem (ES) cells harboring a doxycycline (dox)-inducible Mesp1 gene (A2lox.Mesp1) were differentiated as embryoid bodies for 5 days in the absence (-) or presence (+) of dox from day 2 to day 4. Flk1+Tie2+ endothelial cells were purified by cell sorting for RNA extraction and hybridization on Affymetrix microarrays.
Project description:Previously, we reported that the transcription factor Mesp1 promotes the cell fates of cardiomyocytes, smooth muscle, and vascular endothelium. Recently, hematopoietic stem cells (HSCs) were shown to derive from hemogenic endothelium. Since Mesp1 regulates development of endothelium, it potentially could influence gene expression related to hematopoietic development. Our present fate mapping study found that Mesp1-cre efficiently labeled hematopoietic lineages in vivo. This result suggested that Mesp1 might be expressed in progenitors of the hematopoietic system, such as hemogenic endothelium. To test this, we purified Flk1+ Tie2+ endothelium derived from differentiating ES cells with or without Mesp1 induction, and used microarray expression analysis to identify genes strongly up-regulated by Mesp1.
Project description:Scl/Tal1 confers hemogenic competence and prevents cardiomyogenesis in embryonic endothelium. Here we show that Scl both directly activates a broad gene regulatory network required for hematopoietic stem/progenitor cell (HS/PC) development, and represses transcriptional regulators required for cardiogenesis. Cardiac repression occurs during a short developmental window through Scl binding to distant cardiac enhancers that harbor H3K4me1 at this stage. Scl binding to hematopoietic regulators extends throughout HS/PC and erythroid development and spreads from distant enhancers to promoters. Surprisingly, Scl complex partners Gata 1 and 2 are dispensable for hematopoietic versus cardiac specification and Scl binding to the majority of its target genes. Nevertheless, Gata factors co-operate with Scl to activate selected transcription factors to facilitate HS/PC emergence from hemogenic endothelium. These results uncover a dual function for Scl in dictating hematopoietic versus cardiac fate choice and suggest a mechanism by which lineage-specific bHLH factors direct the divergence of competing fates. ChIP-seq with Scl, Hand1, Lsd1, Ezh2, H3K4me1 and H3K27ac in different cell types with mesodermal origin. Scl ChIP-seq in WT, SclKO, SclKO-iScl and Gata12KO mES cell derived day4 EB (embryoid body) Flk1+ mesodermal cells, SclKO-iScl ES cells and MEL cells; Hand1 ChIP-seq in WT mES cell derived day4 EB Flk1+ mesodermal cells; Lsd1 and Ezh2 ChIP-seq in WT and SclKO mES cell derived day4 EB Flk1+ mesodermal cells. ChIP-seq of histone modifications H3K4me1 and H3K27ac in WT, SclKO and Gata12KO mES cell derived day4 EB Flk1+ mesodermal cells, HPC7 hematopoietic progenitor cells and HL1 cardiomyogenic cells
Project description:Scl/Tal1 confers hemogenic competence and prevents cardiomyogenesis in embryonic endothelium. Here we show that Scl both directly activates a broad gene regulatory network required for hematopoietic stem/progenitor cell (HS/PC) development, and represses transcriptional regulators required for cardiogenesis. Cardiac repression occurs during a short developmental window through Scl binding to distant cardiac enhancers that harbor H3K4me1 at this stage. Scl binding to hematopoietic regulators extends throughout HS/PC and erythroid development and spreads from distant enhancers to promoters. Surprisingly, Scl complex partners Gata 1 and 2 are dispensable for hematopoietic versus cardiac specification and Scl binding to the majority of its target genes. Nevertheless, Gata factors co-operate with Scl to activate selected transcription factors to facilitate HS/PC emergence from hemogenic endothelium. These results uncover a dual function for Scl in dictating hematopoietic versus cardiac fate choice and suggest a mechanism by which lineage-specific bHLH factors direct the divergence of competing fates. Examination of Scl and Gata 1 & 2 target genes in ES cell derived day4.75 EB (embryoid body) Tie2+CD31+CD41- endothelial cells
Project description:Scl/Tal1 confers hemogenic competence and prevents cardiomyogenesis in embryonic endothelium. Here we show that Scl both directly activates a broad gene regulatory network required for hematopoietic stem/progenitor cell (HS/PC) development, and represses transcriptional regulators required for cardiogenesis. Cardiac repression occurs during a short developmental window through Scl binding to distant cardiac enhancers that harbor H3K4me1 at this stage. Scl binding to hematopoietic regulators extends throughout HS/PC and erythroid development and spreads from distant enhancers to promoters. Surprisingly, Scl complex partners Gata 1 and 2 are dispensable for hematopoietic versus cardiac specification and Scl binding to the majority of its target genes. Nevertheless, Gata factors co-operate with Scl to activate selected transcription factors to facilitate HS/PC emergence from hemogenic endothelium. These results uncover a dual function for Scl in dictating hematopoietic versus cardiac fate choice and suggest a mechanism by which lineage-specific bHLH factors direct the divergence of competing fates. Examination of Scl and Gata 1 & 2 target genes in ES cell derived day4.75 EB (embryoid body) Tie2+CD31+CD41- endothelial cells
Project description:It has now been well established that hematopoietic stem and progenitor cells originate from a specialised subset of endothelium termed hemogenic endothelium (HE) via an endothelial-to-hematopoietic transition. However, the molecular mechanisms determining which endothelial progenitors possess or not this hemogenic potential is currently unknown. In this study, we investigated the changes in hemogenic potential in endothelial progenitors at the early stages of embryonic development. We use a microarray approach to profile the genes regulated between E7.5 and E8.5 embryonic day in the ETV2+FLK1+CD41- compartment. Cells were sorted based on ETV2::GFP+/FLK1+/CD41- immunophenotype from ETV2::GFP embryos at E7.5 and E8.5 developmental stage in triplicates
Project description:It has now been well established that hematopoietic stem and progenitor cells originate from a specialised subset of endothelium termed hemogenic endothelium (HE) via an endothelial-to-hematopoietic transition. However, the molecular mechanisms determining which endothelial progenitors possess or not this hemogenic potential is currently unknown. In this study, we investigated the changes in hemogenic potential in endothelial progenitors at the early stages of embryonic development. We use a microarray approach to profile the genes regulated between E7.5 and E8.5 embryonic day in the ETV2+FLK1+CD41- compartment.
Project description:Mouse hematopoietic stem cells (HSCs) first emerge at embryonic day 10.5 (E10.5) on the ventral surface of the dorsal aorta, by endothelial-to-hematopoietic transition (EHT). We investigated whether cells with mesenchymal stem cell-like cell (MSC-LCs) activity that provide an essential niche for HSCs in the bone marrow reside in the aorta-gonad-mesonephros (AGM) and contribute to the structural development of the dorsal aorta and EHT. Using transgenic mice, we demonstrate a lineage hierarchy for AGM MSC-LCs and trace the aortic endothelium and HSCs to mesoderm-derived (Mesp1) PDGFRA+ cells. Mesp1/PDGFRA+ MSC-LCs dominate the sub-endothelial and ventral stroma in the E10.5–E11.5 AGM but by E13.5 are replaced by neural crest (Wnt1) MSC-LCs. Co-aggregating endothelial cells with Mesp1 but not with Wnt1 MSC-LCs resulted in EHT and generation of LT-HSCs that is interrupted by dose-dependent inhibition of PDGFRA signalling. This partnership between endothelial cells and AGM Mesp1 MSC-LCs could be harnessed to manufacture HSCs from endothelium.
Project description:We have developed a protocol to generate hematopoietic and cardiac derivatives in vitro by Mesp1 induction in ES cells. The goal of this study is to analyze the heterogeneity of Mesp1+ mesoderm by single-cell RNA-seq