Project description:Formation of the three primary germ layers during gastrulation is an essential step in the establishment of the vertebrate body plan. Recent studies employing single cell RNA-sequencing have identified major transcriptional changes associated with germ layer specification. Global epigenetic reprogramming accompanies these changes, but the role of the epigenome in regulating early cell fate choice remains unresolved, and the coordination between different epigenetic layers is unclear. Here we describe the first single cell triple-omics map of chromatin accessibility, DNA methylation and RNA expression during the exit from pluripotency and the onset of gastrulation in mouse embryos. We find dynamic dependencies between the different molecular layers, with evidence for distinct modes of epigenetic regulation. The initial exit from pluripotency coincides with the establishment of a global repressive epigenetic landscape, followed by the emergence of local lineage-specific epigenetic patterns during gastrulation. Notably, cells committed to mesoderm and endoderm undergo widespread coordinated epigenetic rearrangements, driven by loss of methylation in enhancer marks and a concomitant increase of chromatin accessibility. In striking contrast, the epigenetic landscape of ectodermal cells is already established in the early epiblast. Hence, regulatory elements associated with each germ layer are either epigenetically primed or epigenetically remodelled prior to overt cell fate decisions during gastrulation, providing the molecular logic for a hierarchical emergence of the primary germ layers. Useful links: Parsed data: (ftp://ftp.ebi.ac.uk/pub/databases/scnmt_gastrulation) Github repository: (https://github.com/rargelaguet/scnmt_gastrulation)
Project description:Formation of the three primary germ layers during gastrulation is an essential step in the establishment of the vertebrate body plan. Recent studies employing single cell RNA-sequencing have identified major transcriptional changes associated with germ layer specification. Global epigenetic reprogramming accompanies these changes, but the role of the epigenome in regulating early cell fate choice remains unresolved, and the coordination between different epigenetic layers is unclear. Here we describe the first single cell triple-omics map of chromatin accessibility, DNA methylation and RNA expression during the exit from pluripotency and the onset of gastrulation in mouse embryos. We find dynamic dependencies between the different molecular layers, with evidence for distinct modes of epigenetic regulation. The initial exit from pluripotency coincides with the establishment of a global repressive epigenetic landscape, followed by the emergence of local lineage-specific epigenetic patterns during gastrulation. Notably, cells committed to mesoderm and endoderm undergo widespread coordinated epigenetic rearrangements, driven by loss of methylation in enhancer marks and a concomitant increase of chromatin accessibility. In striking contrast, the epigenetic landscape of ectodermal cells is already established in the early epiblast. Hence, regulatory elements associated with each germ layer are either epigenetically primed or epigenetically remodelled prior to overt cell fate decisions during gastrulation, providing the molecular logic for a hierarchical emergence of the primary germ layers. We strongly encourage anyone wanting to use these data to first try the parsed data in the link below together with the scripts we used in the paper which can be found in the GitHub repository. Useful links: Parsed data: (ftp://ftp.ebi.ac.uk/pub/databases/scnmt_gastrulation) Github repository: (https://github.com/rargelaguet/scnmt_gastrulation)
Project description:Primordial germ cell mRNA profiles from cells microdissected from e6.5, e7.5 and e8.5 embryos, e7.5 somatic neighbours and Blimp1-KO mice were generated by single cell library construction and sequencing in duplicate using Applied Biosystems SOLiD sequencer. Single cell library construction is described in: Tang f. et. al, Nature Protocols (2010), Vol. 5, p.516.
Project description:Formation of the three primary germ layers during gastrulation is an essential step in the establishment of the vertebrate body plan. Recent studies employing single cell RNA-sequencing have identified major transcriptional changes associated with germ layer specification. Global epigenetic reprogramming accompanies these changes, but the role of the epigenome in regulating early cell fate choice remains unresolved, and the coordination between different epigenetic layers is unclear. Here we describe the first single cell triple-omics map of chromatin accessibility, DNA methylation and RNA expression during the exit from pluripotency and the onset of gastrulation in mouse embryos. We find dynamic dependencies between the different molecular layers, with evidence for distinct modes of epigenetic regulation. The initial exit from pluripotency coincides with the establishment of a global repressive epigenetic landscape, followed by the emergence of local lineage-specific epigenetic patterns during gastrulation. Notably, cells committed to mesoderm and endoderm undergo widespread coordinated epigenetic rearrangements, driven by loss of methylation in enhancer marks and a concomitant increase of chromatin accessibility. In striking contrast, the epigenetic landscape of ectodermal cells is already established in the early epiblast. Hence, regulatory elements associated with each germ layer are either epigenetically primed or epigenetically remodelled prior to overt cell fate decisions during gastrulation, providing the molecular logic for a hierarchical emergence of the primary germ layers. Useful links: Parsed data: (ftp://ftp.ebi.ac.uk/pub/databases/scnmt_gastrulation) Github repository: (https://github.com/rargelaguet/scnmt_gastrulation)
Project description:Formation of the three primary germ layers during gastrulation is an essential step in the establishment of the vertebrate body plan. Recent studies employing single cell RNA-sequencing have identified major transcriptional changes associated with germ layer specification. Global epigenetic reprogramming accompanies these changes, but the role of the epigenome in regulating early cell fate choice remains unresolved, and the coordination between different epigenetic layers is unclear. Here we describe the first single cell triple-omics map of chromatin accessibility, DNA methylation and RNA expression during the exit from pluripotency and the onset of gastrulation in mouse embryos. We find dynamic dependencies between the different molecular layers, with evidence for distinct modes of epigenetic regulation. The initial exit from pluripotency coincides with the establishment of a global repressive epigenetic landscape, followed by the emergence of local lineage-specific epigenetic patterns during gastrulation. Notably, cells committed to mesoderm and endoderm undergo widespread coordinated epigenetic rearrangements, driven by loss of methylation in enhancer marks and a concomitant increase of chromatin accessibility. In striking contrast, the epigenetic landscape of ectodermal cells is already established in the early epiblast. Hence, regulatory elements associated with each germ layer are either epigenetically primed or epigenetically remodelled prior to overt cell fate decisions during gastrulation, providing the molecular logic for a hierarchical emergence of the primary germ layers. Useful links: Parsed data: (ftp://ftp.ebi.ac.uk/pub/databases/scnmt_gastrulation) Github repository: (https://github.com/rargelaguet/scnmt_gastrulation)
Project description:Much remains unknown about the signals that induce early mesoderm to initiate hematopoietic differentiation. Here we show that endoglin (Eng), a receptor for the TGFβ superfamily, identifies all cells with hematopoietic fate in the early embryo. These arise in an Eng+Flk1+ mesodermal precursor population at E7.5, a cell fraction also endowed with endothelial potential. In Eng knockout embryos, hematopoietic colony activity and numbers of CD71+Ter119+ erythroid progenitors were severely reduced. This coincided with severely reduced expression of embryonic globin and key BMP target genes including the hematopoietic regulators Scl, Gata1, Gata2 and Msx-1. To interrogate molecular pathways active in the earliest hematopoietic progenitors, we applied transcriptional profiling to sorted cells from E7.5 embryos. Eng+Flk-1+ progenitors co-expressed TGFβ and BMP receptors and target genes. Furthermore, Eng+Flk-1+ cells presented high levels of phospho-SMAD1/5, indicating active TGFβ and/or BMP signaling. Remarkably, under hematopoietic serum-free culture conditions, hematopoietic outgrowth of endoglin-expressing cells was dependent on TGFβ superfamily ligands: BMP4, BMP2, or TGF-β1. These data demonstrate that the E+F+ fraction at E7.5 represents mesodermal cells competent to respond to TGFb1, BMP4, or BMP2, shaping their hematopoietic development, and that endoglin is a critical regulator in this process by modulating TGF/BMP signaling. E7.5 pooled embryos (25 litters; 300 embryos approximately) were dissected and 3,000 cells were sorted in triplicate for Eng-Flk1-, Eng-Flk1+, Eng+Flk1+, and Eng+Flk1- fractions. Microarray results were analyzed with GeneSpring GX software.
Project description:Much remains unknown about the signals that induce early mesoderm to initiate hematopoietic differentiation. Here we show that endoglin (Eng), a receptor for the TGFβ superfamily, identifies all cells with hematopoietic fate in the early embryo. These arise in an Eng+Flk1+ mesodermal precursor population at E7.5, a cell fraction also endowed with endothelial potential. In Eng knockout embryos, hematopoietic colony activity and numbers of CD71+Ter119+ erythroid progenitors were severely reduced. This coincided with severely reduced expression of embryonic globin and key BMP target genes including the hematopoietic regulators Scl, Gata1, Gata2 and Msx-1. To interrogate molecular pathways active in the earliest hematopoietic progenitors, we applied transcriptional profiling to sorted cells from E7.5 embryos. Eng+Flk-1+ progenitors co-expressed TGFβ and BMP receptors and target genes. Furthermore, Eng+Flk-1+ cells presented high levels of phospho-SMAD1/5, indicating active TGFβ and/or BMP signaling. Remarkably, under hematopoietic serum-free culture conditions, hematopoietic outgrowth of endoglin-expressing cells was dependent on TGFβ superfamily ligands: BMP4, BMP2, or TGF-β1. These data demonstrate that the E+F+ fraction at E7.5 represents mesodermal cells competent to respond to TGFb1, BMP4, or BMP2, shaping their hematopoietic development, and that endoglin is a critical regulator in this process by modulating TGF/BMP signaling.