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: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:The signaling pathway for Nodal, a ligand of the transforming growth factor-beta (TGF-beta) superfamily, plays a central role in regulating the maintenance and/or differentiation of stem cell types that can be derived from the peri-implantation mouse embryo. Extraembryonic endoderm stem (XEN) cells are derived from the primitive endoderm of the blastocyst, which normally gives rise to the parietal and the visceral endoderm in vivo, but XEN cells do not contribute efficiently to the visceral endoderm in chimeric embryos. We have found that treatment of XEN cells with Nodal and/or Cripto, an EGF-CFC co-receptor for Nodal, results in up-regulation of markers for visceral endoderm as well as anterior visceral endoderm (AVE). Re-introduction of treated XEN cells into chimeric embryos by blastocyst injection or morula aggregation results in contribution to visceral endoderm and AVE. In culture, XEN cells do not express Cripto, but do express the related EGF-CFC co-receptor Cryptic and require Cryptic for Nodal signaling. Notably, the response to Nodal can be blocked by treatment with the ALK4/ALK5/ALK7 inhibitor SB431542, but Cripto treatment is unaffected, suggesting that its activity is independent of type I activin receptors. Gene set enrichment analysis of genome-wide expression signatures generated from XEN cells under these treatment conditions confirms the differing responses of Nodal- and Cripto-treated XEN cells to SB431542. Our findings define distinct pathways for Nodal and Cripto in the differentiation of visceral endoderm and AVE from XEN cells, and provide new insights into the specification of these cell types in vivo. Murine Xen-eyfg cell line treated with Alk4 inhibitor SB431542, Nodal and Cripto recombinant proteins.
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: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.
Project description:The signaling pathway for Nodal, a ligand of the transforming growth factor-beta (TGF-beta) superfamily, plays a central role in regulating the maintenance and/or differentiation of stem cell types that can be derived from the peri-implantation mouse embryo. Extraembryonic endoderm stem (XEN) cells are derived from the primitive endoderm of the blastocyst, which normally gives rise to the parietal and the visceral endoderm in vivo, but XEN cells do not contribute efficiently to the visceral endoderm in chimeric embryos. We have found that treatment of XEN cells with Nodal and/or Cripto, an EGF-CFC co-receptor for Nodal, results in up-regulation of markers for visceral endoderm as well as anterior visceral endoderm (AVE). Re-introduction of treated XEN cells into chimeric embryos by blastocyst injection or morula aggregation results in contribution to visceral endoderm and AVE. In culture, XEN cells do not express Cripto, but do express the related EGF-CFC co-receptor Cryptic and require Cryptic for Nodal signaling. Notably, the response to Nodal can be blocked by treatment with the ALK4/ALK5/ALK7 inhibitor SB431542, but Cripto treatment is unaffected, suggesting that its activity is independent of type I activin receptors. Gene set enrichment analysis of genome-wide expression signatures generated from XEN cells under these treatment conditions confirms the differing responses of Nodal- and Cripto-treated XEN cells to SB431542. Our findings define distinct pathways for Nodal and Cripto in the differentiation of visceral endoderm and AVE from XEN cells, and provide new insights into the specification of these cell types in vivo.
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.
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: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.
Project description:Extraembryonic endoderm stem (XEN) cells are isolated from PrE (primitive endoderm) of blastocysts. We directly obtained cell lines with XEN characteristics from porcine embryos for the first time. the RNA-seq data indicated highly reproducible gene expression patterns among piPSCs or pXEN-like cell.the gene expression patterns of pXEN-like cells were significantly different from those of piPSCs