Project description:The Ets2 transcription factor is essential for the development of the mouse placenta and for generating signals for embryonic mesoderm and axis formation. Using a conditional targeted Ets2 allele, we show that Ets2 is essential for trophoblast stem (TS) cells self renewal. Inactivation of Ets2 results in slower growth, increased expression of a subset of differentiation associated genes and decreased expression of several genes implicated in TS self renewal. Among the direct TS targets of Ets2 is Cdx2, a key master regulator of TS cell state. In addition other Ets2 responsive genes include Pace4, Errb, Socs2 and Bmp4. Thus Ets2 contributes to the regulation of multiple genes important for maintaining the undifferentiated state of TS cells and as candidate signals for embryonic development. Keywords: cell type comparison
Project description:Trophoblast stem cells (TS cells), derived from the trophectoderm (TE) of blastocysts, require transcription factors (TFs) and external signals (Fgf4, Activin/Nodal/Tgfb) for self-renewal. While many reports have focused on TF networks that regulate embryonic stem cell (ES cell) self-renewal and pluripotency, little is know about TF networks that regulate self-renewal in TS cells. To further understand transcriptional networks in TS cells we used chromatin immunopreciptiation and DNA microarray analysis (ChIP-chip) to investigate targets of TFs Ap-2g (Tcfap2c), Eomes, Ets2, and Gata3, and a chromatin remodeling factor, Brg1 (Smarca4). We then evaluated the transcriptional states of target genes using transcriptome analysis and genome-wide analysis of histone H3 acetylation (AcH3). Our results describe previously unknown transcriptional networks in TS cells, including TF occupancy of genes involved in ES cell self-renewal and pluripotency, co-occupancy of multiple TFs at target genes, and transcriptional regulatory circuitry within the 5 factors. Through genome-wide mapping and global expression analysis of 5 TF target genes, our data provide a comprehensive analysis of transcriptional networks that regulate TS cell self-renewal.
Project description:Trophoblast stem cells represent the stem cell population of the extraembryonic lineage and arise as result of the first cell fate decision. From the blastocyst stage onwards, the extraembryonic lineage is strictly separated from the embryonic lineage by a distinct epigenetic lineage barrier. Recently, it has been shown, that this epigenetic barrier cannot be fully overcome as the expression of TS-determining factors in embryonic stem cells lead to incomplete trans-differentiation. Here we demonstrate that transient expression of Tfap2c, Gata3, Eomes and Ets2 in fibroblasts suffices to generate cells, which are almost equivalent to trophoblast stem cells based on morphology, expression and methylation patterns. Further, these induced trophoblast stem cells display self-renewal without exogenous factor expression, differentiate along the extraembryonic lineage and chimerize the placenta upon blastocyst injection. Our findings provide insights into transcription factor networks governing TSC identity and offer a new tool for studying the hierarchy of those factors.
Project description:Trophoblast stem cells represent the stem cell population of the extra-embryonic lineage and arise as a result of the first cell fate decision. From blastocyst stage onwards, a distinct epigenetic lineage barrier strictly separates mouse embryonic and extra-embryonic lineages. Recently, it has been shown that this epigenetic barrier cannot be fully overcome as the expression of TS-determining factors in embryonic stem cells lead to incomplete transdifferentiation. Here, we demonstrate that transient expression of Tfap2c, Gata3, Eomes and Ets2 in fibroblasts suffices to generate cells which are almost identical to trophoblast stem cells based on morphology, expression and methylation pattern. Further, these induced trophoblast stem cells display transgene independent self-renewal, differentiate along the extra-embryonic lineage and chimerize the placenta upon blastocyst injection. Our findings provide insights into the transcription factor networks governing trophoblast stem cell identity and offer a new tool for studying the hierarchy of those factors.
Project description:Esrrb is a transcription factor implicated in embryonic stem (ES) cell self-renewal, yet its knockout causes intrauterine lethality due to defects in trophoblast development. Here we show that in trophoblast stem (TS) cells, Esrrb is a downstream target of fibroblast growth factor (Fgf) signalling and is critical to drive TS cell self-renewal. In contrast to its occupancy of pluripotency-associated loci in ES cells, Esrrb sustains the stemness of TS cells by direct binding and regulation of TS cell-specific transcription factors including Elf5 and Eomes. To elucidate the mechanisms whereby Esrrb controls the expression of its targets, we characterized its TS cell-specific interactome by mass spectrometry. Unlike in ES cells, Esrrb interacts in TS cells with the histone demethylase Lsd1 and with the RNA Polymerase II-associated Integrator complex. Our findings provide new insights into both, the general and context-dependent wiring of transcription factor networks in stem cells by master transcription factors.
Project description:Placental trophoblasts are key determinants of in utero development. Mouse trophoblast stem cells (mTSCs), which were first derived over a decade ago, are a powerful cell culture model for studying their self-renewal or differentiation. Our attempts to isolate an equivalent population from the trophectoderm of human blastocysts generated colonies that quickly differentiated in vitro. This finding suggested that the human placenta has another progenitor niche. Here we show that the chorion is one such site. Initially, we immunolocalized pluripotency factors and trophoblast fate determinants in the early-gestation placenta, amnion and chorion. Immunoreactive cells were numerous in the chorion. We isolated these cells and plated them in medium containing FGF and an inhibitor of activin/nodal signaling, which is required for human embryonic SC self-renewal. Colonies of polarized cells with a limited lifespan emerged. Trypsin dissociation yielded continuously self-replicating monolayers. Colonies and monolayers formed the two major human trophoblast lineages—multinucleate syncytiotrophoblasts and invasive cytotrophoblasts (CTBs). Transcriptional profiling experiments revealed the factors associated with the self-renewal or differentiation of human chorionic trophoblast progenitor cells (TBPCs). They included imprinted genes, NR2F1/2, HMGA2 and adhesion molecules that were required for TBPC differentiation. Together, the results of these experiments suggested that the chorion is one source of epithelial CTB progenitors. These findings explain why CTBs of fully formed chorionic villi have a modest mitotic index and identify the chorionic mesoderm as a niche for TBPCs that support placental growth. TBPC colonies (3 biological replicates), TPBC monolayers (2 biological replicates), CTB (3 biological replicates), hESC (3 biological replicates)