GRO-seq in mouse Epiblast-primed, Primitive endoderm-primed, and differentiated endoderm cells
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ABSTRACT: The identification of changes in transcriptional regulation during priming and differentiation of embryonic stem (ES) cells towards the endoderm lineage. Specific populations of ES cells, either primed or committed to endoderm, were isolated and subjected to global nuclear run on sequencing (GRO-Seq). The hHex-Venus (HV) reporter ES cell line, HVJu5.1 (Canham et al., 2010) was used to isolate HV- and HV+ ES cells. Primed ES cells were identified based on the expression of the HV marker in addition to the cell surface marker of undifferentiated ES cells, SSEA-1, (the lower and upper 25% of SSEA-1+, HV expressing cells). When challenged to differentiate, HV- ES cells are primed towards an epiblast fate, while HV+ ES cells are primed towards primitive endoderm. However, these populations are considered primed, rather than committed, as they will readily interconvert when re-introduced into standard ES cell culture conditions. ES cells were grown in self-renewing conditions (GMEM, LIF, 10% FCS, plated on gelatin coated dishes). Endoderm was obtained by differentiating ES cells in medium without the cytokine LIF for 5 days. The HV+, SSEA-1- differentiated fraction was then sorted and represents an early stage in endoderm differentiation.
Project description:We report that ES cells cultured in ground state (2i and 2i/LIF) culture conditions are heterogeneous and show heterogeneus expression of extraembryonic markers. Using a highly sensitive reporter for the endoderm marker Hex we can sort Hex high and low populations from either serum/LIF or 2i/LIF and demonstrate that they have different functional properties. Here we explored the transcriptional basis of these functional differences and noted that Hex low (HV-) and Hex high (HV+) populations showed more distinct expression profiles in 2i/LIF than in serum/LIF. Additionally in 2i/LIF the HV+ population showed an upregulation of extraembryonic markers (such as trophoblast stem cell specific genes) and also imprinted genes compared to the HV- population, which is not observed when these populations are sorted from serum/LIF. We also analysed the transcriptional effect of LIF in 2i by analysing unsorted ES cells cultured in either 2i alone or 2i with LIF. We observed that the addition of LIF led to an upregulation of extraembryonic markers but did not effect the expression of pluripotency genes, other than Klf4. Additionally, the most significantly upregulated genes from 2i/LIF cultured ES cells compared to 2i cultured ES cells showed the greatest correlation to placental tissue when compared to the GNF tissue specific expression database. This analysis, alongside functional experiments, suggested that HV+ ES cells in 2i/LIF corresponded to an extraembryonically primed population of cells and that the addition of LIF supported this population.
Project description:We report that ES cells cultured in ground state (2i and 2i/LIF) culture conditions are heterogeneous and show heterogeneus expression of extraembryonic markers. Using a highly sensitive reporter for the endoderm marker Hex we can sort Hex high and low populations from either serum/LIF or 2i/LIF and demonstrate that they have different functional properties. Here we explored the transcriptional basis of these functional differences and noted that Hex low (HV-) and Hex high (HV+) populations showed more distinct expression profiles in 2i/LIF than in serum/LIF. Additionally in 2i/LIF the HV+ population showed an upregulation of extraembryonic markers (such as trophoblast stem cell specific genes) and also imprinted genes compared to the HV- population, which is not observed when these populations are sorted from serum/LIF. We also analysed the transcriptional effect of LIF in 2i by analysing unsorted ES cells cultured in either 2i alone or 2i with LIF. We observed that the addition of LIF led to an upregulation of extraembryonic markers but did not effect the expression of pluripotency genes, other than Klf4. Additionally, the most significantly upregulated genes from 2i/LIF cultured ES cells compared to 2i cultured ES cells showed the greatest correlation to placental tissue when compared to the GNF tissue specific expression database. This analysis, alongside functional experiments, suggested that HV+ ES cells in 2i/LIF corresponded to an extraembryonically primed population of cells and that the addition of LIF supported this population. RNA-seq of sorted Hex low and high expressing ES cell populations cultured in serum/LIF or 2i/LIF as well as unsorted ES cells from 2i or 2i/LIF.
Project description:Quantitation of polyA mRNA levels in subpopulations of the HexVenus reporter (clone HV5.1) mouse ES cell line growing under self-renewing conditions. Subpopulations were identified and isolated based on the expression of the ES cell surface marker SSEA 1 and the expression of the venus protein. At approximately 70% confluence, cells were trypsinised, resuspended in FACs buffer (10%FCS in PBS) and incubated with a mouse monoclonal antibody to SSEA 1 (MC-480, Developmental Hybridoma Studies Bank, University of Iowa). Cells were then incubated with an Alexa-647 conjugated anti-mouse IgM antibody (Invitrogen) and subpopulations were fractionated by flow cytometry. The aim was to identify genes which are differentially expressed between FACS-sorted HV-S+ and HV+S+ primed mESC populations.
Project description:We report two chemically defined conditions that differ by the addition of the cytokine Lif and the β-catenin-stabilizing drug Chir99021 and enable permanent self-renewal as mesenchymal and epithelial morphotypes, respectively. The morphotypes are interconvertible and differentiate equipotently. Surprisingly, the proliferation of both morphotypes requires Lif/Gp130/Stat3 signaling (autocrine in the absence of added Lif) and non-canonical Wnt signaling (autocrine). Additionally, the epithelial version requires β-catenin for proliferation and morphology. Interestingly, the mesenchymal cells also express key epithelial markers, but those are improperly structured and/or not functional, indicating a primed state. The results provide an improved platform for studying the proliferation and plasticity of the early extraembryonic endoderm, which occurs in mesenchymal and epithelial forms in vivo.
Project description:Embryonic stem (ES) cells continuously decide whether to maintain pluripotency or differentiate. While exogenous LIF and BMP4 perpetuate a pluripotent state, less is known about factors initiating differentiation. We show that heparan sulfate (HS) proteoglycans are critical co-receptors for signals inducing ES cell differentiation. Genetic targeting of NDST1 and 2, two enzymes required for N-sulfation of proteoglycans, blocked differentiation. This phenotype was rescued by HS presented in trans or by soluble heparin. NaClO3-, which reduces sulfation of proteoglycans, potently blocked differentiation of wild type cells. Mechanistically, N-sulfation was identified to be critical for functional autocrine FGF4 signalling. Micro array analysis identified the pluripotency maintaining transcription factors Nanog, KLF2/4/8, Tbx3 and Tcf3 to be negatively regulated, whereas markers of differentiation such as Gbx2, Dnmt3b, FGF5 and Brachyury were induced by sulfation-dependent-FGFR signalling. We show that several of these genes are heterogeneously expressed in ES cells and targeting of heparan sulfation or FGFR-signalling facilitated a homogenous Nanog/KLF4/Tbx3 positive ES cell state. This finding suggests that the recently discovered heterogeneous state of ES cells is regulated by HS-dependent FGFR signalling. Similarly, culturing blastocysts with NaClO3- eliminated GATA6 positive primitive endoderm progenitors generating a homogenous Nanog positive inner cell mass. Functionally, reduction of sulfation robustly improved de novo ES cell derivation efficiency. We conclude that N-sulfated HS is required for FGF4 signalling to maintain ES cells primed for differentiation in a heterogeneous state. Inhibiting this pathway facilitates a more naïve ground state. Four groups with three biological replicates and a technical duplicate in each
Project description:Embryonic stem (ES) cells continuously decide whether to maintain pluripotency or differentiate. While exogenous LIF and BMP4 perpetuate a pluripotent state, less is known about factors initiating differentiation. We show that heparan sulfate (HS) proteoglycans are critical co-receptors for signals inducing ES cell differentiation. Genetic targeting of NDST1 and 2, two enzymes required for N-sulfation of proteoglycans, blocked differentiation. This phenotype was rescued by HS presented in trans or by soluble heparin. NaClO3-, which reduces sulfation of proteoglycans, potently blocked differentiation of wild type cells. Mechanistically, N-sulfation was identified to be critical for functional autocrine FGF4 signalling. Micro array analysis identified the pluripotency maintaining transcription factors Nanog, KLF2/4/8, Tbx3 and Tcf3 to be negatively regulated, whereas markers of differentiation such as Gbx2, Dnmt3b, FGF5 and Brachyury were induced by sulfation-dependent-FGFR signalling. We show that several of these genes are heterogeneously expressed in ES cells and targeting of heparan sulfation or FGFR-signalling facilitated a homogenous Nanog/KLF4/Tbx3 positive ES cell state. This finding suggests that the recently discovered heterogeneous state of ES cells is regulated by HS-dependent FGFR signalling. Similarly, culturing blastocysts with NaClO3- eliminated GATA6 positive primitive endoderm progenitors generating a homogenous Nanog positive inner cell mass. Functionally, reduction of sulfation robustly improved de novo ES cell derivation efficiency. We conclude that N-sulfated HS is required for FGF4 signalling to maintain ES cells primed for differentiation in a heterogeneous state. Inhibiting this pathway facilitates a more naïve ground state.
Project description:The visceral endoderm (VE) is an epithelial tissue in the early postimplantation mouse embryo that encapsulates the pluripotent epiblast distally and the extraembryonic ectoderm proximally. In addition to facilitating nutrient exchange before the establishment of a circulation, the VE is critical for patterning the epiblast. Since VE is derived from the primitive endoderm (PrE) of the blastocyst, and PrE-derived eXtraembryonic ENdoderm (XEN) cells can be propagated in vitro, XEN cells should provide an important tool for identifying factors that direct VE differentiation. In this study, we demonstrated that BMP4 signalling induces the formation of a polarized epithelium in XEN cells. This morphological transition was reversible, and was associated with the acquisition of a molecular signature comparable to extraembryonic (ex) VE. Resembling exVE which will form the endoderm of the visceral yolk sac, BMP4-treated XEN cells regulated hematopoiesis by stimulating the expansion of primitive erythroid progenitors. We also observed that LIF exerted an antagonistic effect on BMP4-induced XEN cell differentiation, thereby impacting the extrinsic conditions used for the isolation and maintenance of XEN cells in an undifferentiated state. Taken together, our data suggest that XEN cells can be differentiated towards an exVE identity upon BMP4 stimulation, and therefore represent a valuable tool for investigating PrE lineage differentiation.
Project description:Translational control plays a central role in regulation of gene expression and can lead to significant divergence between mRNA- and protein-abundance. The translational landscape of early mammalian development and its impact on cellular proteome, however, remains largely un-explored. Here we used genome-wide approaches combined with time-course analysis to measure the mRNA-abundance, mRNA-translation rate and protein expression during the transition of naïve into primed embryonic stem cells (ESCs). We found that the ground state ESCs cultured with GSK3- and MEK-inhibitors and LIF (2iL) display higher ribosome density on a selective set of mRNAs. These mRNAs show reduced translation during the exit from ground state pluripotency and transition to serum/LIF (SL) culture or upon commitment to primed epiblast-like stem cells (EpiLSCs). Strikingly, integrative analysis with cellular proteome indicate a strong translational buffering of this set of mRNAs in 2iL-ESCs leading to stable protein expression levels. Our data reveal that the global alteration of cellular proteome is largely accompanied by transcriptional rewiring. Furthermore, we identified a set of genes (including UHRF1 and KRAS) that undergo selective post-translational regulation during the transition of naïve into primed pluripotency and linked the observed changes to upstream GSK- and MEK/MAPK-signaling pathways using single inhibitor treated ESCs. Thus, we provide a comprehensive and detailed overview of the global changes in gene expression during the transition of naïve to primed pluripotency and dissect the relative contributions of RNA-transcription, translation and regulation of protein stability in controlling protein abundance.
Project description:The visceral endoderm (VE) is an epithelial tissue in the early postimplantation mouse embryo that encapsulates the pluripotent epiblast distally and the extraembryonic ectoderm proximally. In addition to facilitating nutrient exchange before the establishment of a circulation, the VE is critical for patterning the epiblast. Since VE is derived from the primitive endoderm (PrE) of the blastocyst, and PrE-derived eXtraembryonic ENdoderm (XEN) cells can be propagated in vitro, XEN cells should provide an important tool for identifying factors that direct VE differentiation. In this study, we demonstrated that BMP4 signalling induces the formation of a polarized epithelium in XEN cells. This morphological transition was reversible, and was associated with the acquisition of a molecular signature comparable to extraembryonic (ex) VE. Resembling exVE which will form the endoderm of the visceral yolk sac, BMP4-treated XEN cells regulated hematopoiesis by stimulating the expansion of primitive erythroid progenitors. We also observed that LIF exerted an antagonistic effect on BMP4-induced XEN cell differentiation, thereby impacting the extrinsic conditions used for the isolation and maintenance of XEN cells in an undifferentiated state. Taken together, our data suggest that XEN cells can be differentiated towards an exVE identity upon BMP4 stimulation, and therefore represent a valuable tool for investigating PrE lineage differentiation. Total RNA isolated in triplicate from XEN stem cell cultures that were untreated (samples 1-3) or treated with BMP4 growth factor (samples 4-6). Total RNA isolated in triplicate from XEN stem cells that were treated with BMP4 and were flow sorted as Afp::GFP-positive (samples 7-9) or Afp::GFP-negative (samples 10-12).
Project description:Transcriptional profiling of H9 human embryonic stem cells differentiated towards early endoderm over 72 hours in chemically defined media.