A single-cell atlas of pig gastrulation as a resource for comparative embryology
Ontology highlight
ABSTRACT: The bilaminar disc of early pig embryos closely mirrors that of humans making it a powerful model for studying gastrulation. Given the difficulties obtaining embryos in non-rodents, early cell-fate decisions during mammalian gastrulation remain ill-understood. Here we present a single-cell transcriptomic atlas of pig gastrulation and early organogenesis. We uncover the dynamics of cell fate emergence during pig peri-gastrulation and reveal conserved and species-specific transcriptional programs across different mammals. Combined with investigations in embryos and embryonic stem cells, we elucidate the spatial, molecular, and temporal events during definitive endoderm (DE) formation. We show that early FOXA2+ epiblast progenitors become DE without undergoing epithelial-to-mesenchymal transition, contrasting later emerging FOXA2/TBXT+ anterior primitive streak, which form node/notochord progenitors. We demonstrate that DE fate is driven by hypoblast-derived NODAL signalling, which is extinguished upon DE differentiation. These findings highlight the interplay between temporal and topological signalling during early cell fate decisions during mammalian gastrulation.
Project description:Rabbit embryos, as in humans, develop as bilaminar discs at gastrulation and unlike egg cylinders as in rodents. Mammalian primordial germ cells (PGCs) in all species originate during gastrulation. We sequence the transcriptomes of rabbit embryos during gastrulation, and show that rabbit PGC (rbPGC) specification occurs at the posterior epiblast at the onset of gastrulation
Project description:Rabbit embryos, as in humans, develop as bilaminar discs at gastrulation and unlike egg cylinders as in rodents. Mammalian primordial germ cells (PGCs) in all species originate during gastrulation. We sequence the transcriptomes of rabbit embryos during gastrulation, and show that rabbit PGC (rbPGC) specification occurs at the posterior epiblast at the onset of gastrulation
Project description:Rabbit embryos, as in humans, develop as bilaminar discs at gastrulation and unlike egg cylinders as in rodents. Mammalian primordial germ cells (PGCs) in all species originate during gastrulation. We sequence the transcriptomes of rabbit embryos during gastrulation, and show that rabbit PGC (rbPGC) specification occurs at the posterior epiblast at the onset of gastrulation
Project description:Precisely co-ordinated activation of lineage specific transcription factors direct cell fate decisions during mouse early development. The T-box transcription factor Eomes is dynamically expressed during mouse gastrulation and is a key regulator of the anterior visceral endoderm (AVE), cardiac mesoderm and definitive endoderm (DE) lineages. The cis-acting regulatory elements that direct spatiotemporally restricted Eomes expression domains have yet to be elucidated. To understand transcriptional regulation of Eomes in Definitive Endoderm open chromatin data was generated by ATAC-seq and histone modifications identified by ChIP-seq. Interactions at the Eomes locus and the loci of two related transcription factors Foxa2 and Lhx1, was also determined by NG Capture-C.
Project description:Precisely co-ordinated activation of lineage specific transcription factors direct cell fate decisions during mouse early development. The T-box transcription factor Eomes is dynamically expressed during mouse gastrulation and is a key regulator of the anterior visceral endoderm (AVE), cardiac mesoderm and definitive endoderm (DE) lineages. The cis-acting regulatory elements that direct spatiotemporally restricted Eomes expression domains have yet to be elucidated. To understand transcriptional regulation of Eomes in Definitive Endoderm open chromatin data was generated by ATAC-seq and histone modifications identified by ChIP-seq. Interactions at the Eomes locus and the loci of two related transcription factors Foxa2 and Lhx1, was also determined by NG Capture-C.
Project description:Precisely co-ordinated activation of lineage specific transcription factors direct cell fate decisions during mouse early development. The T-box transcription factor Eomes is dynamically expressed during mouse gastrulation and is a key regulator of the anterior visceral endoderm (AVE), cardiac mesoderm and definitive endoderm (DE) lineages. The cis-acting regulatory elements that direct spatiotemporally restricted Eomes expression domains have yet to be elucidated. To understand transcriptional regulation of Eomes in Definitive Endoderm open chromatin data was generated by ATAC-seq and histone modifications identified by ChIP-seq. Interactions at the Eomes locus and the loci of two related transcription factors Foxa2 and Lhx1, was also determined by NG Capture-C.
Project description:Human primordial germ cells (hPGCs), the precursors of sperm and eggs, originate in early postimplantation embryos. Since early human embryos cannot be investigated directly, we extended our recent in vitro model for hPGC fate, alongside direct analysis of early porcine embryos, which develop in a highly similar manner. Here we show that porcine PGCs (pPGCs) originate from the posterior pre-primitive streak epiblast in response to WNT and BMP-pSMAD signalling, followed by sequential induction of SOX17–BLIMP1 expression. This is reminiscent of our observations for the human in vitro counterpart. Mechanistic analysis in the culture model for hPGC specification and gastrulation shows that a balanced SOX17-BLIMP1 gene dosage is critical and sufficient for PGC specification; SOX17 subsequently induces definitive endoderm during gastrulation. We demonstrate that porcine embryos when combined with a tractable human model system can provide insights on early human development and mechanisms of early cell fate decisions.
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)