Project description:Embryonic stem cells (ESCs), which are derived from the primitive ectoderm of pre-implantation blastocysts, are pluripotent cells and can thus contribute to the formation of all somatic cell lineages in chimeric animals. Similarly, epiblast stem cells (EpiSCs), which are derived from epiblast tissue of post-implantation embryos, are also pluripotent and can give rise to derivatives of all three germ layers in teratoma assays. Introduction of the four transcription factors Oct4/Sox2/Klf4/c-Myc into somatic cells has been shown to generate induced pluripotent stem cells (iPSCs). iPSCs exhibit ESC-like properties and are virtually identical to ESCs with respect to a number of charactertistics. However, generation of EpiSC-like cells by direct reprogramming of somatic cells using these transcription factors has not been shown to date. Here we show that Yamanaka’s four transcription factors can be used to directly generate EpiSC-like iPS cells (ePSCs) under EpiSC culture conditions. These ePSCs are identical to EpiSCs with respect to morphology, gene expression pattern, epigenetic status, and chimera formation. This is the first study to demonstrate that the culture environment in transcription factor-mediated reprogramming determines the cell fate of the reprogrammed cell. We could therefore envision that we eventually are able to shape the identity of a directly reprogrammed cell at will simply by modulating the culture conditions. RNA samples to be analyzed on microarrays were prepared using Qiagen RNeasy columns with on-column DNA digestion. 500 ng of total RNA per sample was used as input into a linear amplification protocol (Ambion), which involved synthesis of T7-linked double-stranded cDNA and 12 hrs of in-vitro transcription incorporating biotin-labelled nucleotides. Purified and labelled cRNA was then hybridized for 18 hrs onto MouseRef-8 v2 expression BeadChips (Illumina) according to the manufacturer's instructions. After washing, as recommended, chips were stained with streptavidin-Cy3 (GE Healthcare) and scanned using the iScan reader (Illumina) and accompanying software. Samples were hybridized as biological replicates. 24 samples were analyzed: MEF: Female mouse embryonic fibroblast, 2 biological rep ESC OG2: OG2 female embryonic stem cell, 2 biological rep EpiSC OG2: OG2 female EpiSC grown as single cells with conditioned medium, 2 biological rep EpiSC GOF18: GOF18 EpiSC grown as single cells with conditioned medium, 2 biological rep EpiSC T9b: T9 EpiSC on MEFs in activin-containing CDM, harvested w/o feeders, subconfluent, 2 biological rep ePSC L4: EpiSC-like iPS Cells L4, MEF reprogrammed to EpiSCs with 4F, line L4, grown with LIF and activin, 2 biological rep ePSC L7: EpiSC-like iPS cells L7, MEF reprogrammed to EpiSCs with 4F, line L7, grown with LIF and activin, 2 biological rep ePSC C1: EpiSC-like iPS Cells C1, MEF reprogrammed to EpiSCs with 4F, line C1, grown with LIF and activin, 2 biological rep ePSC C3: EpiSC-like iPS Cells C3, MEF reprogrammed to EpiSCs with 4F, line C3, grown with LIF and activin, 2 biological rep ePSC-R: EpiSC-like iPS Cells reverted, L4 ePSC cells reverted to an ESC-like state using Klf4 virus, 2 biological rep ePSC-RC1: EpiSC-like iPS Cells reverted, L4 ePSR Cre1, Cre-treated L4 ePSR cells, line 1, 2 biological rep ePSC-RC2: EpiSC-like iPS Cells reverted, L4 ePSR Cre2, Cre-treated L4 ePSR cells, line 2, 2 biological rep

Project description:Embryonic stem cells (ESCs) comprise at least two populations of cells with divergent states of pluripotency. Here, we show that epiblast stem cells (EpiSCs) also comprise two distinct cell populations that can be distinguished by the expression of a specific Oct4-GFP marker. These two subpopulations, Oct4-GFP positive and negative EpiSCs, are capable of converting into each other in vitro. Oct4-GFP positive and negative EpiSCs are distinct from ESCs with respect to global gene expression pattern, epigenetic profile, and Oct4 enhancer utilization. Oct4-GFP negative cells share features with cells of the late mouse epiblast and cannot form chimeras. However, Oct4-GFP positive EpiSCs, which only represent a minor EpiSC fraction, resemble cells of the early epiblast and can readily contribute to chimeras. Our findings suggest that the rare ability of EpiSCs to contribute to chimeras is due to the presence of the minor EpiSC fraction representing the early epiblast. RNA samples to be analyzed on microarrays were prepared using Qiagen RNeasy columns with on-column DNA digestion. 300 ng of total RNA per sample was used as input into a linear amplification protocol (Ambion), which involved synthesis of T7-linked double-stranded cDNA and 12 hrs of in-vitro transcription incorporating biotin-labelled nucleotides. Purified and labelled cRNA was then hybridized for 18 hrs onto MouseRef-8 v2 expression BeadChips (Illumina) according to the manufacturer's instructions. After washing, as recommended, chips were stained with streptavidin-Cy3 (GE Healthcare) and scanned using the iScan reader (Illumina) and accompanying software. Samples were hybridized as biological replicates. 6 samples were analyzed, five of them in duplicate and one of them (T9-EpiSC) a single time (11 total samples). ESC: Mouse ESC male; EpiSC: Mouse EpiSC male GOF18; Epi-Sox2: Mouse EpiSC Sox2 male GOF18 (Overexpressing WT Sox2) cultured in condition EpiSC medium (CM); EpiSC-GFP-: Mouse E3 EpiSC grown in CM and FACS-sorted for GFP-; EpiSC-GFP+: Mouse E3 EpiSC grown in CM and FACS-sorted for GFP+; T9-EpiSC: Mouse T9 EpiSC grown on medium-density CF1 MEFs in UM, 2d -Fgf2, harvested without MEFs. The supplementary file 'GSE17984_non-normalized_data.txt' contains non-normalized data for Samples GSM450294-GSM450304.

Project description:Recently, (in vitro) pluripotent EpiSCs were derived from the post-implantation egg cylinder stage epiblasts of mouse and rat. These EpiSCs resemble and correspond very closely to the conventional human embryonic stem cells (hESCs) in the colony morphology and culture/signaling requirements for maintaining pluripotency, but exhibit a range of significant phenotypic and signaling response differences from the conventional mouse ES cells (mESCs). These observations strongly support the notion that EpiSCs and hESCs are intrinsically similar, and raise an attractive hypothesis: as mESCs and EpiSCs/hESCs represent two distinct pluripotency states: the mESC-like state representing the ICM of pre-implantation blastcyst and the EpiSC-like state representing the post-implantation epiblasts, whether the epiblast state (including conventional hESCs) can be converted back to the ICM state. Despite studies providing evidence that epiblast-like cells exist and transition back and forth within colony of conventional mESCs; mESCs and EpiSCs share substantial set of pluripotency transcriptional factors, including Oct4, Sox2 and Nanog; and mESCs are more stable in culture, in the present study we found that EpiSCs differentiated rapidly under mESC culture conditions and no “spontaneously” converted mESC could be readily identified and isolated over serial passages at the population or clonal level. Remarkably, we found that blockage of the TGFβ pathway or inhibition of the H3K4 demethylase LSD1 with small molecule inhibitors induced dramatic morphological changes of EpiSCs towards mESC phenotypes with activation of some ICM-specific gene expression. However, full conversion of EpiSCs to a mESC-like state with competence to chimeric contribution can only be readily generated with a combination of inhibitors of LSD1 and ALK. These observations underscore a powerful and direct induction of reprogramming from the developmentally later-stage EpiSCs to a mESC-like stage by a synergy of signaling and direct epigenetic modulations. It also highlights a significant role for TGFβ pathway inhibition in promoting reprogramming to and sustaining true pluripotency, which further supports our recent studies in generating chimerism-competent rat pluripotent cells. Collectively, our studies provide a proof-of-concept demonstration that pluripotency-restricted EpiSCs can be readily converted to a mESC-like state in the absence of any genetic manipulation by precise pharmacological control of signaling pathways that distinguish the two pluripotency states and an epigenetic target simultaneously, and offer a convenient experimental system to further study the mechanism. Such method and concept may also provide an avenue for generating a new type of mESC-like human pluripotent cell.

Project description:Recently, (in vitro) pluripotent EpiSCs were derived from the post-implantation egg cylinder stage epiblasts of mouse and rat. These EpiSCs resemble and correspond very closely to the conventional human embryonic stem cells (hESCs) in the colony morphology and culture/signaling requirements for maintaining pluripotency, but exhibit a range of significant phenotypic and signaling response differences from the conventional mouse ES cells (mESCs). These observations strongly support the notion that EpiSCs and hESCs are intrinsically similar, and raise an attractive hypothesis: as mESCs and EpiSCs/hESCs represent two distinct pluripotency states: the mESC-like state representing the ICM of pre-implantation blastcyst and the EpiSC-like state representing the post-implantation epiblasts, whether the epiblast state (including conventional hESCs) can be converted back to the ICM state. Despite studies providing evidence that epiblast-like cells exist and transition back and forth within colony of conventional mESCs; mESCs and EpiSCs share substantial set of pluripotency transcriptional factors, including Oct4, Sox2 and Nanog; and mESCs are more stable in culture, in the present study we found that EpiSCs differentiated rapidly under mESC culture conditions and no âspontaneouslyâ converted mESC could be readily identified and isolated over serial passages at the population or clonal level. Remarkably, we found that blockage of the TGFÎ² pathway or inhibition of the H3K4 demethylase LSD1 with small molecule inhibitors induced dramatic morphological changes of EpiSCs towards mESC phenotypes with activation of some ICM-specific gene expression. However, full conversion of EpiSCs to a mESC-like state with competence to chimeric contribution can only be readily generated with a combination of inhibitors of LSD1 and ALK. These observations underscore a powerful and direct induction of reprogramming from the developmentally later-stage EpiSCs to a mESC-like stage by a synergy of signaling and direct epigenetic modulations. It also highlights a significant role for TGFÎ² pathway inhibition in promoting reprogramming to and sustaining true pluripotency, which further supports our recent studies in generating chimerism-competent rat pluripotent cells. Collectively, our studies provide a proof-of-concept demonstration that pluripotency-restricted EpiSCs can be readily converted to a mESC-like state in the absence of any genetic manipulation by precise pharmacological control of signaling pathways that distinguish the two pluripotency states and an epigenetic target simultaneously, and offer a convenient experimental system to further study the mechanism. Such method and concept may also provide an avenue for generating a new type of mESC-like human pluripotent cell. Global gene-expression analyses of the parnate/mAMFGi cells

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12h pathway stimulation / inhibition experiment in epiblast stem cells

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