Project description:scRNA-seq of mouse embryonic stem cells (mESC) derived from four different genetic backgrounds grown in ground state conditions and differentiated towards an epiblast stem cell like (EpiSCL) population.
Project description:Reversion from primed to naïve pluripotent status has been achieved by various signaling manipulation, but it is still unclear what signaling is the actual driving force to get over the hurdle from primed to naïve pluripotency. We previously reported that activation of AMP kinase (AMPK) contributed to maintenance of naïve pluripotency. Here, we further show that AMPK activators, AICAR, A769662 or metformin, can induce the reversion of primed mouse epiblast stem cells (mEpiSCs) to naïve pluripotent state. Primed mEpiSCs in our naïve cell culture condition with leukemia inhibitory factor (LIF) and 2 kinase inhibitors (2i) (2iL) never gave rise to naïve state cells. Addition of AICAR alone even in the absence of 2iL or either of AMPK inhibitors with LIF induced appearance of naïve-like cells from primed mEpiSCs. Through maintenance and passages of these cells in 2iL condition, clear naïve-like morphology colonies were purely obtained. They showed core naïve protein expression, and global naïve gene expression profiles. These cells contributed to chimeric mice including germline transmission. Inhibition of p38 signaling abolished the AMPK-elicited reversion and forced activation of p38 in primed mEpiSCs partially reproduced the naïve cell induction, suggesting that p38 is one of the critical downstream in AMPK activation. AMPK pathway should be a novel critical driving force in reversion of primed to naïve pluripotency.
Project description:Reversion from primed to naïve pluripotent status has been achieved by various signaling manipulation, but it is still unclear what signaling is the actual driving force to get over the hurdle from primed to naïve pluripotency. We previously reported that activation of AMP kinase (AMPK) contributed to maintenance of naïve pluripotency. Here, we further show that AMPK activators, AICAR, A769662 or metformin, can induce the reversion of primed mouse epiblast stem cells (mEpiSCs) to naïve pluripotent state. Primed mEpiSCs in our naïve cell culture condition with leukemia inhibitory factor (LIF) and 2 kinase inhibitors (2i) (2iL) never gave rise to naïve state cells. Addition of AICAR alone even in the absence of 2iL or either of AMPK inhibitors with LIF induced appearance of naïve-like cells from primed mEpiSCs. Through maintenance and passages of these cells in 2iL condition, clear naïve-like morphology colonies were purely obtained. They showed core naïve protein expression, and global naïve gene expression profiles. These cells contributed to chimeric mice including germline transmission. Inhibition of p38 signaling abolished the AMPK-elicited reversion and forced activation of p38 in primed mEpiSCs partially reproduced the naïve cell induction, suggesting that p38 is one of the critical downstream in AMPK activation. Single cell RNA-seq analysis under AICAR stimulation successfully demonstrated the reversion process with appearance of intermediate naïve-like population. AMPK pathway should be a novel critical driving force in reversion of primed to naïve pluripotency.
Project description:In the mammalian embryo, epiblast cells must exit the naïve state and acquire formative pluripotency. This cell state transition is recapitulated by mouse embryonic stem cells (ESCs), which undergo pluripotency progression in defined conditions in vitro. However, our understanding of the molecular cascades and gene networks involved in the exit from naïve pluripotency remains fragmentary. Here, we employed a combination of genetic screens in haploid ESCs, CRISPR/Cas9 gene disruption, large-scale transcriptomics and computational systems biology to delineate the regulatory circuits governing naïve state exit. Transcriptome profiles for 73 ESC lines deficient for regulators of the exit from naïve pluripotency predominantly manifest delays on the trajectory from naïve to formative epiblast. We find that gene networks operative in ESCs are also active during transition from pre- to post-implantation epiblast in utero. We identified 496 naïve state-associated genes tightly connected to the in vivo epiblast state transition and largely conserved in primate embryos. Integrated analysis of mutant transcriptomes revealed funnelling of multiple gene activities into discrete regulatory modules. Finally, we delineate how intersections with signalling pathways direct this pivotal mammalian cell state transition.
Project description:To characterize the EpiSCs (Epiblast stem cells) we established in our lab, we have employed whole genome microarray expression profiling as a platform to distinguish the EpiSCs (primed state) from ES cells (naïve state).
Project description:Embryonic stem cell (ESC) cultures display a heterogeneous gene expression profile, ranging from a pristine naïve pluripotent state to a primed epiblast state. While it is known that the addition of inhibitors of GSK3β and MEK (so-called 2i conditions) push ESC cultures towards a more homogeneous naïve pluripotent state, the molecular underpinnings of this naïve transition are not completely understood. Here we demonstrate that Dazl, a RNA-binding protein previously thought to be expressed specifically in developing primordial germ cells (PGCs), marks a subpopulation of ESCs in vitro that is actively transitioning toward naïve pluripotency. In the absence of Dazl expression, ESCs fail to induce proper expression of Tet enzymes required for 5-hydroxymethylation in 2i-culture conditions. As a result, 5-hydroxymethylation of methylated cystosine residues is impaired. Indeed, we demonstrate that Tet1 and Tet2 are mRNA targets of Dazl, indicating that Dazl might play a role in protection or stabilizing these mRNA molecules. Our results provide insight in the regulation of the acquisition of naïve pluripotency and demonstrate that Dazl is required for TET-mediated cytosine hydroxymethylation in cells that are actively reprogramming to a pluripotent ground state. RNA-IP experiments were used to identify the RNA species bound to DAZL.
Project description:The epiblast is the first cell type that forms apical-basal polarity de novo as the mouse embryo implants into the maternal uterus, while the extraembryonic neighbours of the epiblast - trophectoderm and primitive endoderm - retain their pre-established polarity beyond implantation [1]; however, it is still unclear how the epiblast establishes apical-basal polarity de novo. Here, we focused on Rap1 signaling pathway, which is activated during the transition of the epiblast from the naïve to primed state of pluripotency during implantation [2]. Through the preestablished in vitro three-dimensional culture system [3], genetic knockouts and proximity-biotinylation analyses, we found that Rap1 integrates multiple signals that contribute to de novo formation of apical-basal polarity. Importantly, formation of apical-basal polarity in the epiblast is essential for its correct patterning and proper communication with the extraembryonic lineages. Altogether, these results not only dissect molecular details of de novo apical-basal polarity formation, but also have broader implications for epithelial polarity and development.
Project description:Embryonic stem cell (ESC) cultures display a heterogeneous gene expression profile, ranging from a pristine naïve pluripotent state to a primed epiblast state. While it is known that the addition of inhibitors of GSK3? and MEK (so-called 2i conditions) push ESC cultures towards a more homogeneous naïve pluripotent state, the molecular underpinnings of this naïve transition are not completely understood. Here we demonstrate that Dazl, a RNA-binding protein previously thought to be expressed specifically in developing primordial germ cells (PGCs), marks a subpopulation of ESCs in vitro that is actively transitioning toward naïve pluripotency. In the absence of Dazl expression, ESCs fail to induce proper expression of Tet enzymes required for 5-hydroxymethylation in 2i-culture conditions. As a result, 5-hydroxymethylation of methylated cystosine residues is impaired. Indeed, we demonstrate that Tet1 and Tet2 are mRNA targets of Dazl, indicating that Dazl might play a role in protection or stabilizing these mRNA molecules. Our results provide insight in the regulation of the acquisition of naïve pluripotency and demonstrate that Dazl is required for TET-mediated cytosine hydroxymethylation in cells that are actively reprogramming to a pluripotent ground state. Two independent mouse ES cell lines, Dazl-GFP and Stella-GFP, were cultured on ?-irradiated feeder MEFs in DMEM containing 15% FBS or serum-free B27N2 medium both supplemented with leukemia inhibitory factor (LIF) (Ying 2008). For the 2i experiments, 1µM MEK inhibitor PD0325901 (Axon Medchem), and 5 µM GSK3? inhibitor Kenpaullone (Tocris), were used. Cells were harvest at 0, 3 and 10 days in each condition for expression microarray analysis.