Project description:Biomechanical cues are instrumental in guiding embryonic development and cell differentiation. Understanding how these physical stimuli translate into transcriptional programs could provide insight into mechanisms underlying mammalian pre-implantation development. Here, we explore this by exerting microenvironmental control over mouse embryonic stem cells (ESCs). Microfluidic encapsulation of ESCs in agarose microgels stabilized the naïve pluripotency network and specifically induced expression of Plakoglobin (Jup), a vertebrate homologue of β-catenin. Indeed, overexpression of Plakoglobin was sufficient to fully re-establish the naïve pluripotency gene regulatory network under metastable pluripotency conditions, as confirmed by single-cell transcriptome profiling. Finally, we found that in the epiblast, Plakoglobin was exclusively expressed at the blastocyst stage in human and mouse embryos – further strengthening the link between Plakoglobin and naïve pluripotency in vivo. Our work reveals Plakoglobin as a mechanosensitive regulator of naïve pluripotency and provides a paradigm to interrogate the effects of volumetric confinement on cell-fate transitions.
Project description:Although cell therapies require large numbers of quality-controlled hPSCs, existing technologies are limited in their ability to efficiently grow and scale stem cells. We report here that cell-state conversion from primed-to-naïve pluripotency enhances the biomanufacturing of hPSCs. Naïve hPSCs exhibit superior growth kinetics and aggregate formation characteristics in stirred suspension bioreactors compared to their primed counterparts. Moreover, we demonstrate the role of the bioreactor mechanical environment in the maintenance of naïve pluripotency, through transcriptomic enrichment of mechano-sensing signaling for cells in the bioreactor along with a decrease in expression of lineage-specific and primed pluripotency hallmarks. Bioreactor-cultured, naïve hPSCs express epigenetic regulatory transcripts associated with naïve pluripotency, and display hallmarks of X-chromosome reactivation. They exhibit robust production of naïve pluripotency metabolites and display reduced expression of primed pluripotency cell surface markers. We also show that these cells retain the ability to undergo targeted differentiation into beating cardiomyocytes, hepatocytes, and neural rosettes. They additionally display faster kinetics of teratoma formation compared to their primed counterparts. Naïve bioreactor hPSCs also retain structurally stable chromosomes. Our research corroborates that converting hPSCs to the naïve state enhances hPSC manufacturing and indicates a potentially important role for the bioreactor’s mechanical environment in maintaining naïve pluripotency.
Project description:Epigenetic reprogramming is a cancer hallmark but how it unfolds during early neoplastic events and its role in carcinogenesis and cancer progression is not fully understood. Here we show that resetting from primed to naïve human pluripotency results in acquisition of a DNA methylation landscape mirroring the cancer DNA methylome, with gradual hypermethylation of bivalent developmental genes. We hypothesised that unknown proteins and transcription factors play a role in the DNA hypermethylation process and analysed therefore the proteomics of the very early stages of the resetting process which involves overexpression of Nanog and Klf2. The samples analysed were Primed hESCs (Conventional stem cells), 72hours after induction and 1 week after induction, in triplicate. For our purposes we identified candidate transcription factors and subsequently knocked them down to test their involvement in the DNA hypermethylation (as described in the manuscript related to this data, Patani et al. Nature Communications). More broadly, we believe, this dataset is a useful resource for the wider community interested in pluripotency, resetting, reprogramming, cell identity transitions etc. Our results indicate that transition to naïve pluripotency and oncogenic transformation share common epigenetic trajectories, which implicates reprogramming and the pluripotency network as a central hub in cancer formation.
Project description:The transition of pluripotent stem cells (PSCs) from primed to naïve states constitutes a prototypical example of cellular plasticity. The naïve state can be stabilized by defined chemical cocktails that block extracellular signals, notably including the MEK pathway. However, little is known regarding the underlying transcriptional mechanisms. Here, we report that the transcriptional landscape of the naïve state can be mimicked in mouse and human PSCs by stimulating transcriptional enhancers. This is attained by inhibiting the CDK8 and CDK19 kinases, which are negative regulators of Mediator, a critical component of enhancer function. Mechanistically, CDK8/19i triggers a global increase in the recruitment of RNA Pol II at promoters and enhancers, hyperactivating enhancers and their target genes. Lastly, the emergence of naïve pluripotency in the pre-implantation epiblast coincides with a marked reduction in CDK8/19 activity, and CDK8/19i blocks its subsequent developmental progression. These findings suggest that naïve pluripotency during development includes hyperactivation of enhancers and can be captured in vitro, either by blunting extracellular signaling, or by stimulating enhancer-driven transcription. These principles may apply to other cellular transitions.
Project description:In this study we identify Mettl3, an m6A RNA modification writer, as a critical regulator for terminating naïve pluripotency and a positive maintainer of primed pluripotency in vitro and in vivo. Remarkably, Mettl3 knockout pre-implantation epiblasts and naïve ES cells, entirely lack m6A on coding mRNAs and are viable. Yet, they fail to adequately terminate the naïve pluripotent state, and subsequently undergo aberrant priming and early lineage commitment at the post-implantation stage. A comprehensive functional and genomic analysis involving profiling of m6A, RNA transcription and translation in Mettl3 wild-type and knockout pluripotent and differentiated cells, identified m6A as a critical determinant that destabilizes secondary naïve specific pluripotency genes Esrrb, Klf4 and Nanog, and restrains their transcript stability and translation efficiency. In summary, our findings provide for the first time evidence for a critical role for an mRNA epigenetic modification in early mammalian development in vivo, and identify a mechanism that functionally regulates mouse naïve and primed pluripotency in an opposing manner. Ribosome footprint (Ribo-Seq) was measured from mouse embryonic stem cells and mouse embriod bodies, in WT and Mettl3-KO cell lines.
Project description:Following implantation, mouse epiblast cells transit from a naïve to a primed state in which they are competent for both somatic and primordial germ cell (PGC) specification. Using mouse embryonic stem cells (mESC) as an in vitro model to study the transcriptional regulatory principles orchestrating peri-implantation development, here we show that the transcription factor Foxd3 is necessary for the exit from naïve pluripotency and the progression to a primed pluripotent state. During this transition, Foxd3 acts as a repressor that dismantles a significant fraction of the naïve pluripotency expression program through the decommissioning of active enhancers associated with key naïve pluripotency and early germline genes. Subsequently, Foxd3 needs to be silenced in primed pluripotent cells to allow the reactivation of relevant genes required for proper PGC specification. Our findings uncover a wave of activation-deactivation of Foxd3 as a crucial step for the exit from naïve pluripotency and subsequent PGC specification. Genome-wide binding profiles for Foxd3 were investigated in mouse embryonic stem cells (mESC). A mESC line (FH-Foxd3 mESC line) expressing exogenous Foxd3 tagged with Flag and HA epitope (FH-Foxd3) at nearly endogenous levels was generated. ChIPs were performed against FH-Foxd3 using anti-HA or anti-Flag antibodies.
Project description:Mouse embryonic stem cells (mESCs) fluctuate between a naïve inner cell mass (ICM)-like state and a primed epiblast-like state of pluripotency in serum, but are harnessed exclusively in a distinctive, apparently more naïve state of pluripotency (the ground state) with inhibitors for mitogen-activated protein kinase (MAPK) and glycogen synthase kinase 3 pathways (2i). Understanding the mechanism ensuring a naïve state of pluripotency would be critical in realizing a full potential of ESCs. We show here that PRDM14, a PR domain-containing transcriptional regulator, ensures a naïve pluripotency by a dual mechanism: Antagonizing fibroblast growth factor receptor (FGFR) signaling that is activated paradoxically by the core transcriptional circuitry for pluripotency and directs a primed state and repressing de novo DNA methyltransferases that create a primed epiblast-like epigenome. PRDM14 exerts these functions by recruiting polycomb repressive complex 2 (PRC2) specifically to key targets and repressing their expression. Mouse Embryonic Stem Cells (mESCs) or mESC-like cells with different Prdm14 genotypes {Prdm14(+/+), Prdm14(-/-), and Prdm14(-/-) rescued with Avitag-EGFP-Prdm14 transgene [Prdm14(-/-)+AGP14]} are cultured on MEF in different medium [2i, Serum(day 2), Serum+MEK inhibitor (PD0325901) (day 2), Serum without LIF (day2)].
Project description:It is now well recognized that human embryonic stem cells (hESCs)1 closely resemble mouse epiblast stem cells (mEpiSCs)2-5 exhibiting primed pluripotency unlike mouse ESCs (mESCs) which acquire a naïve pluripotent state4-8. Efforts have been made to trigger naïve pluripotency in hESCs9-11 for subsequent unbiased lineage-specific differentiation, a common conundrum faced by primed pluripotent hESCs due to heterogeneity in gene expression existing within and between hESC lines12. We report here a novel culture medium facilitating rapid induction of naïve pluripotency in established hESCs. Our medium also allows derivation of naïve mESCs from blastocyst stage which has not been shown earlier. The established naïve hESCs could survive long-term single cell passaging, maintain a normal karyotype, exhibit upregulation of naïve pluripotency genes and were dependent on signaling pathways similar to naïve mESCs. Also, they undergo global DNA demethylation, cluster together with previously described naïve hESCs13 and show a distinctive long non-coding RNA profile. Collectively, we demonstrate an alternate route to capture naïve pluripotency in hESCs which is fast, reproducible, can be employed to derive naïve mESCs and can induce efficient differentiation. Three primed and matching naive human embryonic stem cell lines were profiled in duplo.
Project description:Naïve and primed pluripotent states retain distinct molecular properties, yet limited knowledge exists on how their state transitions are regulated. Here, we identify Mettl3, an N6-methyladenosine (m6A) transferase, as a regulator for terminating murine naïve pluripotency. Mettl3 knockout pre-implantation epiblasts and naïve embryonic stem cells (ESCs) are depleted for m6A in mRNAs and yet, are viable. However, they fail to adequately terminate their naïve state, and subsequently undergo aberrant and restricted lineage priming at the post-implantation stage, leading to early embryonic lethality. m6A predominantly and directly reduces mRNA stability, including that of key naïve pluripotency promoting transcripts. This study highlights a critical role for an mRNA epigenetic modification in vivo, and identifies regulatory modules that functionally influence naïve and primed pluripotency in an opposing manner.