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.
Project description: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 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.
Project description:This study aimed to understand the transcriptional networks regulating endoderm specification from HESC and therefore explored the phenotype of CA1 and CA2 HESC constitutively over-expressing SOX7 or SOX17. Cell lines were created using an inducible construct whereby clonal populations containing transgene integration are selected by Neomycin resistance without expressing of the gene of interest (NoCre controls). Transgene expression is induced via Cre-mediated recombination and selected for puromycin resistance (SOX O/E). The phenotype of the resulting cells suggests that SOX7 expressing HESC represent stable extraembryonic endoderm progenitors, while SOX17 expressing HESC represent early definitive endoderm progenitors. Both in vitro and in vivo SOX7 expressing HESC are restricted to the extraembryonic endoderm lineage, while SOX17 expressing HESC demonstrate mesendodermal specificity. In vitro, SOX17 expressing HESC efficiently produce mature definitive endoderm derivatives. The molecular phenotype of the resulting SOX7 and SOX17 expressing HESC was characterized by microarray analysis Experiment Overall Design: Total RNA was extracted from confluent monolayer cultures of SOX7 over-expressing HESC, SOX17 over-expressing HESC, and their respective control parental HESC lines (designated NoCre Sox7 and NoCre Sox17).
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:Mouse embryonic stem cells containing a Sox17-GFP construct were differentiated using growth factors (Activin A and Wnt3A) to definitive endoderm. Sox17-GFP(+) cells were sorted using fluorescence activated cell sorting and either used for total RNA harvest OR continued in culture in the presence of primary pancreatic mesenchymal cell lines. At the end of 6 serial passages on mesenchyme, the Sox17-GFP(+) cells were again sorted and the RNA was harvested for arrays. Samples were prepared as described in summary, with technical duplicates for each of the following 3 categories: 1. Unpassaged (P0) endoderm, 2. Endoderm passaged 6 times (P6) on mesenchyme 1, and 3. Endoderm passaged 6 times (P6) on mesenchyme 2.
Project description:This study aimed to understand the transcriptional networks regulating endoderm specification from HESC and therefore explored the phenotype of CA1 and CA2 HESC constitutively over-expressing SOX7 or SOX17. Cell lines were created using an inducible construct whereby clonal populations containing transgene integration are selected by Neomycin resistance without expressing of the gene of interest (NoCre controls). Transgene expression is induced via Cre-mediated recombination and selected for puromycin resistance (SOX O/E). The phenotype of the resulting cells suggests that SOX7 expressing HESC represent stable extraembryonic endoderm progenitors, while SOX17 expressing HESC represent early definitive endoderm progenitors. Both in vitro and in vivo SOX7 expressing HESC are restricted to the extraembryonic endoderm lineage, while SOX17 expressing HESC demonstrate mesendodermal specificity. In vitro, SOX17 expressing HESC efficiently produce mature definitive endoderm derivatives. The molecular phenotype of the resulting SOX7 and SOX17 expressing HESC was characterized by microarray analysis Keywords: cell line comparison
Project description:Induction of the Arf tumor suppressor in response to hyperproliferative stress following oncogene activation activates a p53-dependent transcriptional program that limits the expansion of incipient cancer cells. Although Arf is not expressed in most tissues of fetal or young adult mice, it is physiologically expressed in the fetal yolk sac, a tissue derived from the extraembryonic endoderm. We demonstrate that expression of the mouse p19Arf protein marks late stages of extraembryonic endoderm differentiation in cultured embryoid bodies derived from either embryonic stem cells or induced pluripotent stem cells, and that Arf inactivation specifically delays the differentiation of the extraembryonic endoderm lineage, but not the formation of other germ cell lineages from pluripotent progenitors. Arf is required for the timely induction of extraembryonic endodermal cells in response to Ras/Erk signaling and, in turn, acts through p53 to ensure extraembryonic endoderm lineage development, but not maintenance. Remarkably, a significant temporal delay in extraembryonic endoderm differentiation detected during the maturation of Arf-null embryoid bodies is rescued by enforced expression of miR-205, a micro-RNA up-regulated by p19Arf and p53. Introduction of miR-205 into Arf-null embryonic stem cells rescues defective ExEn formation and elicits a program of gene expression that controls the migration and adhesion of embryonic endodermal cells. This occurs, at least in part, through atypical regulation of genes that control the epithelial-to-mesenchymal transition in cancer cells. Our findings suggest that noncanonical and canonical roles of Arf in extraembryonic endoderm development and tumor suppression, respectively, may be conceptually linked through mechanisms that govern cell-to-cell attachment and migration. 4 samples total two each at two time points in ESC development At each time point one sample was treted with miR-205 and the other with a GFP control vector