Temporal RNA-seq expression profiling of Sox17-medaited XEN conversion of ESCs
ABSTRACT: The transcription factor Sox17 is expressed in early primitive endoderm-fated cells of the mouse embryo and in embryo-derived extraembryonic endoderm (ExEn) stem (XEN) cells. We have shown that overexpression of Sox17 in mouse embryonic stem cells (ESCs) drives cell fate to a committed XEN-like cell state (Sox17-XEN cells). When placed back into the embryo, Sox17-XEN cells contribute exclusively to the ExEn. Transient Sox17 expression is sufficient to drive this fate change during which time cells transit through distinct intermediate states prior to the generation of functional XEN-like cells. We identified dynamic regulatory networks driving Sox17-mediated XEN conversion by analyzing a dynamic regulatory map of gene expression bifurcation points throughout conversion, created using RNA-seq time series data. We found that Sox17 orchestrates this conversion process by acting in autoregulatory and feed-forward network motifs, regulating dynamic gene regulatory networks (GRNs) directing cell fate. We have shown that Sox17-mediated XEN conversion provides a powerful tool for understanding the regulation of cell fate changes and for the elucidation of GRNs regulating lineage decisions in the mouse embryo. Total RNA was extracted during a time course of Sox17 overexpression in mouse ESCs at 7 time points as well as from wild-type ESCs and wild-type XEN cells.
Project description:The inner cell mass of the mouse pre-implantation blastocyst is comprised of epiblast progenitor and primitive endoderm cells of which cognate embryonic (mESCs) or extra-embryonic (XEN) stem cell lines can be derived. Importantly, each stem cell type retains the defining properties and lineage restriction of their in vivo tissue of origin. Recently, we demonstrated that XEN-like cells arise within mESC cultures. This raises the possibility that mESCs can generate self-renewing XEN cells without the requirement for gene manipulation. We have developed a novel approach to convert mESCs to XEN cells (cXEN) using growth factors. We confirm that the down-regulation of the pluripotency transcription factor Nanog and the expression of primitive endoderm-associated genes Gata6, Gata4, Sox17 and Pdgfra are necessary for cXEN cell derivation. This approach highlights an important function for Fgf4 in cXEN cell derivation. Paracrine FGF-signalling compensates for the loss of endogenous Fgf4, which is necessary to exit mESC self-renewal, but not for XEN cell maintenance. Our cXEN protocol also reveals that distinct pluripotent stem cells respond uniquely to differentiation promoting signals. cXEN cells can be derived from mESCs cultured with Erk- and Gsk3-inhibitors (2i) and LIF, similarly to conventional mESCs. However, we find that epiblast stem cells (EpiSCs) derived from the post-implantation embryo are refractory to cXEN cell establishment, consistent with the hypothesis that EpiSCs represent a pluripotent state distinct from mESCs. In all, these findings suggest that the potential of mESCs includes the capacity to give rise to both extra-embryonic and embryonic lineages. A total of eight samples were analyzed. Three mouse embryonic stem cell (mESC) lines were used as a negative control, 2 embryo-derived extraembryonic endoderm (XEN) cell lines were used as a positive control, 3 converted XEN (cXEN) cells were used as the experiemental cell lines.
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:Embryonic (ES) and epiblast (EpiSC) stem cells are pluripotent but committed to an embryonic lineage fate. Conversely, trophoblast (TS) a nd extraembryonic endoderm (XEN) stem cells contribute predominantly to tissues of the placenta and yolk sac, respectively. Here we show that each of these four stem cell types is defined by a unique DNA methylation profile. Despite their distinct developmental origin, TS and XEN cells share key epigenomic hallmarks, chiefly characterized by robust DNA methylation of embryo-specific developmental regulators, as well as a subordinate role of 5-hydroxymethylation. We also observe a substantial methylation reinforcement of pre-existing epigenetic repressive marks that specifically occurs in extraembryonic stem cells compared to in vivo tissue, presumably due to continued high Dnmt3b expression levels. These differences establish a major epigenetic barrier between the embryonic and extraembryonic stem cell types. In addition, epigenetic lineage boundaries also separate the two extraembryonic stem cell types by mutual repression of key lineage-specific transcription factors. Thus, global DNA methylation patterns are a defining feature of each stem cell type that underpin lineage commitment and differentiative potency of early embryo-derived stem cells. Our detailed methylation profiles identify a cohort of developmentally regulated sequence elements, such as orphan CpG islands, that will be most valuable to uncover novel transcriptional regulators and pivotal gatekeeper genes in pluripotency and lineage differentiation.
Project description:XEN cells are derived from the primitive endoderm of mouse blastocysts. In culture and in chimeras they exhibit properties of parietal endoderm. However, BMP signaling promotes XEN cells to form an epithelium and differentiate into visceral endoderm (VE). Of the several different subtypes of VE described, BMP induces a subtype that is most similar to the VE adjacent to the trophoblast-derived extraembryonic ectoderm. The experiment was performed to gain insight into genes regulated by BMP and activin in XEN cells, and also to more precisely define the VE subtypes formed in culture. IM8A1 XEN cells were treated for 6 days with BMP2 (20 ng/ml, R&D Systems), activin A (30 ng/ml, Peprotech), both, or neither in GMEM + 10% fetal bovine serum.
Project description:Pluripotent stem cells can be generated from somatic cells by using pure chemicals.However, the cell fate dynamics and molecular events that occur during the chemical reprogramming process remain unclear. In this study, we found that the chemical reprogramming process requires the early formation of extra-embryonic endoderm (XEN)-like cells and a late transition from XEN-like cells to CiPSCs, a new route that differs from the pathway of transcription factor-induced reprogramming. Moreover, by more precisely manipulating the cell fate transition in a step-wise manner through the XEN-like state, we identified small-molecule boosters and established a robust chemical reprogramming system, with a yield up to 1,000-fold greater than that of the previously reported protocol. These findings demonstrate that chemical reprogramming is a unique and promising approach in the future manipulation of cell fates. We analyzed the gene expression profiles of intermediate cells obtained from diferent timepoints during chemical reprogramming process,using RNA-Sequencing. Embryo-derived XEN cells (eXENs), chemically-derived eXEN cell lines (CeXENs), embryonic stem cells (ESCs) and chemically-induced pluripotent stem cells (CiPSCs) are used as controls.
Project description:We investigated whether Sox17 directly or indirectly regulates extraembryonic endoderm gene expression by identifying Sox17 DNA-binding sites using chromatin-immunoprecipitation coupled with whole-genome promoter tiling array analysis (ChIP-Chip). We used the Sox17 and FLAG antibody to ask whether Sox17 was binding directly to the regulatory regions of genes in homogeneous extraembryonic endoderm (XEN) cell lines and in Sox17-inducible mouse embryonic stem (ES) cells. In XEN cells, Sox17 binding sites were located within the promoters or the introns of 2206 (3%) genes. We performed an ontology analysis for the genes with Sox17 binding sites and found that a significant number had adhesion functions in basement membrane establishment and maintenance. In addition to these ECM genes, Sox17 was also bound to promoter regions of a variety of other genes implicated in extraembryonic endoderm development including key transcription factors. Ontology analysis of all the Sox17 ChIP-chip binding targets identified in Sox17-induced ES cells, demonstrated a significant enrichment near genes involved in the cell cycle as well as genes involved in signaling pathways that function in embryonic stem cell maintenance. Sox17 was also observed to directly bind to the regulatory regions of many genes in pathways known to be functionally important for ES cell pluripotency and self-renewal. These studies suggest that one of Sox17’s functions in the differentiation of ICM and ES cells is to bind the regulatory regions of many genes that encode basement membrane components, thus leading to their activation. In addition to directly activating genes required for primitive endoderm differentiation, Sox17 may also function to activate and reinforce the transcriptional network governing differentiation. Overall design: Extraembryonic endoderm (XEN) mouse cell lines ChIPed with Sox17 vs. XEN cell Input; Sox17-inducible mouse ES cells (induced with doxycycline for 48hrs) ChIPed with Sox17 or FLAG vs. Input
Project description:Cardiac muscle differentiation in vivo is guided by sequential growth factor signals, including endoderm-derived diffusible factors, impinging on cardiogenic genes in the developing mesoderm. Previously, by RNA interference in AB2.2 mouse embryonic stem cells (mESCs), we identified the endodermal transcription factor Sox17 as essential for Mesp1 induction in primitive mesoderm and subsequent cardiac muscle differentiation. However, downstream effectors of Sox17 remained to be proven functionally. In this study, we used genome-wide profiling of Sox17-dependent genes in AB2.2 cells, RNA interference, chromatin immunoprecipitation, and luciferase reporter genes to dissect this pathway. Sox17 was required not only for Hhex (a second endodermal transcription factor) but also for Cer1, a growth factor inhibitor from endoderm that, like Hhex, controls mesoderm patterning in Xenopus toward a cardiac fate. Suppressing Hhex or Cer1 blocked cardiac myogenesis, although at a later stage than induction of Mesp1/2. Hhex was required but not sufficient for Cer1 expression. Over-expression of Sox17 induced endogenous Cer1 and sequence-specific transcription of a Cer1 reporter gene. Forced expression of Cer1 was sufficient to rescue cardiac differentiation in Hhex-deficient cells. Thus, Hhex and Cer1 are indispensable components of the Sox17 pathway for cardiopoiesis in mESCs, acting at a stage downstream from Mesp1/2. Keywords: Cardiac development, Embryonic stem cells, Endoderm, Myogenesis, RNA interference Genome-wide expression profiling of Sox17-dependent genes. Mouse embryonic stem cells expressing Sox17 or luciferase shRNA were differentiated for up to 10 days by the embryoid body method [PMID:8155574], then were analysed using Affymetrix microarrays. ESCs were transduced with lentiviral vectors coexpressing enhanced green fluorescent protein (eGFP) with shRNA against Sox17, or against firefly luciferase. Transduced cells were flow-sorted based on GFP fluorescence, grown as embryoid bodies, and transferred to tissue culture plates after 4.5 days [PMID:17360443]. Cells were harvested at days 0, 2, 4, 5, 6, 8 and 10 in two biological replicates, except where noted.
Project description:We found that the non-essential amino acid L-Proline (L-Pro) acts as a signaling molecule that promotes the conversion of embryonic stem cells (ESCs) into mesenchymal-like, spindle-shaped, highly motile, invasive pluripotent stem cells. This embryonic stem cell-to-mesenchymal-like transition (esMT) is accompanied by a genome-wide remodeling of the transcriptome We used microarrays to elucidate whether a diverse transcriptional program is the basis of the morphological and motility differences between ESCs and L- Proline treated ESCs (PiCs) Total RNA was extracted from Control (ESCs) and L-Proline treated mouse embryonic stem cells (PiCs) and hybridized on Affimetrix microarrays.
Project description:We found that the non-essential amino acid L-proline (L-Pro) acts as a signaling molecule that promotes the conversion of embryonic stem cells (ESCs) into mesenchymal-like, spindle-shaped, highly motile, invasive pluripotent stem cells.This embryonic stem cell-to-mesenchymal-like transition (esMT) is accompanied by a genome-wide remodeling of the H3K9me3 and H3K36me3 histone marks. Examination of 2 different histone modifications in untreated ESCs and L-Pro treated ESCs