Project description: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:The epiblast is the first cell type that forms apical-basal polarity de novo as the mouse embryo implants into the maternal uterus, while the extraembryonic neighbours of the epiblast - trophectoderm and primitive endoderm - retain their pre-established polarity beyond implantation [1]; however, it is still unclear how the epiblast establishes apical-basal polarity de novo. Here, we focused on Rap1 signaling pathway, which is activated during the transition of the epiblast from the naïve to primed state of pluripotency during implantation [2]. Through the preestablished in vitro three-dimensional culture system [3], genetic knockouts and proximity-biotinylation analyses, we found that Rap1 integrates multiple signals that contribute to de novo formation of apical-basal polarity. Importantly, formation of apical-basal polarity in the epiblast is essential for its correct patterning and proper communication with the extraembryonic lineages. Altogether, these results not only dissect molecular details of de novo apical-basal polarity formation, but also have broader implications for epithelial polarity and development.
Project description:Mammalian embryonic development begins with the specification and segregation of the two extra-embryonic lineages, trophectoderm and primitive endoderm, from the pluripotent embryonic lineage, the epiblast. To establish a map of epiblast (EPI) versus primitive endoderm (PrE) lineage segregation which occurs within the inner cell mass (ICM), we comprehensively characterised the gene expression profiles of individual inner cells during blastocyst development. Lineage represents the two embryonic cell lineages: the epiblast (EPI), and the primitive endoderm (PE), which are segregated within the inner cell mass(ICM) during blastocyst development.
Project description:During mammalian pre-implantation development, the cells of the blastocyst’s inner cell mass differentiate into the epiblast and primitive endoderm lineages, which give rise to the fetus and extra-embryonic tissues, respectively. Extra-embryonic endoderm differentiation can be modeled in vitro by induced expression of GATA transcription factors in mouse embryonic stem cells. Here we use this GATA-inducible system to quantitatively monitor the dynamics of global proteomic changes during the early stages of this differentiation event and also investigate the fully differentiated phenotype, as represented by embryo-derived extra-embryonic endoderm (XEN) cells. Using mass spectrometry-based quantitative proteomic profiling with multivariate data analysis tools, we reproducibly quantified 2,336 proteins across three biological replicates and have identified clusters of proteins characterized by distinct, dynamic temporal abundance profiles. We first used this approach to highlight novel marker candidates of the pluripotent state and extra-embryonic endoderm differentiation. Through functional annotation enrichment analysis, we have shown that the downregulation of chromatin-modifying enzymes, the re-organization of membrane trafficking machinery and the breakdown of cell-cell adhesion are successive steps of the extra-embryonic differentiation process. Thus, applying a range of sophisticated clustering approaches to a time-resolved proteomic dataset has allowed the elucidation of complex biological processes which characterize stem cell differentiation and could establish a general paradigm for the investigation of these processes.
Project description:Expression profiling of stem cell lines derived from the early embryo representing the trophoblast, primitive endoderm, early epiblast (inner cell mass E3.5) and late post-implantation epiblast (E5.5). Cells were grown without feeders and harvested. Comparisons were made to provide evidence of unique gene expression between the cell lines. Specifically, pre-implantation (ICM, epiblast and primitive endoderm, and trophoblast), as well as pre-implantation and post-implantation epiblasts.
Project description:Embryonic stem cells (ESCs) can exist in at least two states that transcriptionally resemble different stages of embryonic development. Naïve ESCs resemble peri-implantation stages and primed ESCs the pre-gastrulation epiblast. In mouse, primed ESCs give rise to definitive endoderm in response to pathways downstream of Nodal and Wnt signalling. However, when these cytokines are applied to naïve ESCs, they differentiate to a cell type that approximates early primitive endoderm (PrE), the blastocyst stage progenitor layer that gives rise to the extra-embryonic endoderm. Here, we apply this context dependency to human ESCs, showing that these cytokines drive the differentiation of naïve pluripotent cells to generate extra-embryonic PrE, or hypoblast, and, as in mouse, expanded as an in vitro model for naïve extra-embryonic endoderm (nEnd) in defined conditions. Consistent with observations made in mouse, human PrE differentiation is dependent on FGF signalling in vitro, and we show, that by inhibiting FGF receptor signalling, we could simplify naïve pluripotent culture such that inhibitor requirements closer resembled those used in mouse. These nEnd cultures represent stable extra-embryonic endoderm, or human hypoblast, cell lines.
Project description:Embryonic stem cells (ESCs) can exist in at least two states that transcriptionally resemble different stages of embryonic development. Naïve ESCs resemble peri-implantation stages and primed ESCs the pre-gastrulation epiblast. In mouse, primed ESCs give rise to definitive endoderm in response to pathways downstream of Nodal and Wnt signalling. However, when these cytokines are applied to naïve ESCs, they differentiate to a cell type that approximates early primitive endoderm (PrE), the blastocyst stage progenitor layer that gives rise to the extra-embryonic endoderm. Here, we apply this context dependency to human ESCs, showing that these cytokines drive the differentiation of naïve pluripotent cells to generate extra-embryonic PrE, or hypoblast, and, as in mouse, expanded as an in vitro model for naïve extra-embryonic endoderm (nEnd) in defined conditions. Consistent with observations made in mouse, human PrE differentiation is dependent on FGF signalling in vitro, and we show, that by inhibiting FGF receptor signalling, we could simplify naïve pluripotent culture such that inhibitor requirements closer resembled those used in mouse. These nEnd cultures represent stable extra-embryonic endoderm, or human hypoblast, cell lines.
Project description:Expression profiling of stem cell lines derived from the early embryo representing the trophoblast, primitive endoderm, early epiblast (inner cell mass E3.5) and late post-implantation epiblast (E5.5).
Project description:The inner cell mass (ICM) of the early blastocyst at E3.5, a source of ES cell derivation, is a morphologically homogeneous population of undifferentiated pluripotent cells that give rise to all embryonic lineages. The immediate application of the newly developed V1V3 method to single cells in this stage of mouse embryos revealed the presence of two populations of cells, one with primitive endoderm expression and the other with pluripotent epiblast-like gene expression. The genes expressed differentially between these two populations were well preserved in morphologically differentiated primitive endoderm and epiblast in the embryos one day later (E4.5), demonstrating that the method successfully detects subtle but essential differences in gene expression at the single-cell level among seemingly homogeneous cell populations. This study provides a strategy to analyze biophysical events in medicine as well as in neural, stem cell, and developmental biology, where small numbers of distinctive or diseased cells play critical roles. Keywords: Single cell analysis
Project description:While the reprogramming factors OCT4, SOX2, KLF4, and MYC (OSKM) can reactivate the pluripotency network in terminally differentiated cells, they also regulate expression of non-pluripotency genes in other contexts, such as the mouse primitive endoderm. The primitive endoderm is an extraembryonic lineage established alongside the pluripotent epiblast in the blastocyst, and is the progenitor pool for extraembryonic endoderm stem (XEN) cells. Several studies have shown that endodermal genes are upregulated in fibroblasts undergoing reprogramming, although whether endodermal genes promote or inhibit acquisition of pluripotency is unclear. We show that, in fibroblasts undergoing conventional reprogramming, OSKM-induced expression of endodermal genes leads to formation of induced XEN (iXEN) cells, which possess key properties of blastocyst-derived XEN cells, including morphology, transcription profile, self-renewal, and multipotency. Our data show that iXEN cells arise in parallel to iPS cells, indicating that OSKM are sufficient to drive cells to two distinct fates during reprogramming. Sequence-based mRNA transcriptional profiling of three different cell lines (MEF, XEN, iXEN) with multiple biological replicates, under two different growth medium conditions (ESC medium, XEN medium) for XEN and iXEN cells.