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: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. mRNA profiles were generated by RNA-seq in duplicates for each of the following mESC lines: Foxd3fl/fl;Cre-ER mESC maintained in "Serum+LIF" (SL) treated with TM for three days (SL Foxd3-/-); untreated Foxd3fl/fl;Cre-ER SL mESC (SL Foxd3fl/fl); tetON Foxd3 SL mESC treated with Dox for three days; WT SL mESC treated with Dox for three days; Foxd3fl/fl;Cre-ER mESC maintained in "2i+LIF" (2i) treated with TM for three days (2i Foxd3-/-); untreated Foxd3fl/fl;Cre-ER 2i mESC (2i Foxd3fl/fl).
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.
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.
Project description:Oct4, Sox2, Klf4, and cMyc (OSKM) reprogram somatic cells to pluripotency. To gain a mechanistic understanding of their function, we mapped OSKM-binding, stage-specific transcription-factors (TFs), and chromatin-states in discrete reprogramming stages and performed loss- and gain-of-function experiments. We found that early in reprogramming OSK extensively bind somatic-enhancers and initiate their decommissioning by recruiting Hdac1. Concurrently, OSK engage other sites, including specific pluripotency-enhancers, and induce the relocation of somatic TFs to these sites and away from somatic-enhancers, extending somatic-enhancer decommissioning genome-wide. Pluripotency-enhancer selection early in reprogramming occurs predominantly at sites with high OSK-motif densities and requires collaborative binding by OSK. Most pluripotency-enhancers are selected later and occupied by OS and stage-specific-TFs like Esrrb. Overexpression of stage-specific-TFs influences reprogramming efficiency by changing OSK-occupancy, somatic-enhancer decommissioning, and pluripotency-enhancer selection. We propose that collaborative interactions among OSK and with stage-specific-TFs direct both somatic-enhancer decommissioning and pluripotency-enhancer selection, which drives the enhancer reorganization underlying reprogramming
Project description:Oct4, Sox2, Klf4, and cMyc (OSKM) reprogram somatic cells to pluripotency. To gain a mechanistic understanding of their function, we mapped OSKM-binding, stage-specific transcription-factors (TFs), and chromatin-states in discrete reprogramming stages and performed loss- and gain-of-function experiments. We found that early in reprogramming OSK extensively bind somatic-enhancers and initiate their decommissioning by recruiting Hdac1. Concurrently, OSK engage other sites, including specific pluripotency-enhancers, and induce the relocation of somatic TFs to these sites and away from somatic-enhancers, extending somatic-enhancer decommissioning genome-wide. Pluripotency-enhancer selection early in reprogramming occurs predominantly at sites with high OSK-motif densities and requires collaborative binding by OSK. Most pluripotency-enhancers are selected later and occupied by OS and stage-specific-TFs like Esrrb. Overexpression of stage-specific-TFs influences reprogramming efficiency by changing OSK-occupancy, somatic-enhancer decommissioning, and pluripotency-enhancer selection. We propose that collaborative interactions among OSK and with stage-specific-TFs direct both somatic-enhancer decommissioning and pluripotency-enhancer selection, which drives the enhancer reorganization underlying reprogramming
Project description:Oct4, Sox2, Klf4, and cMyc (OSKM) reprogram somatic cells to pluripotency. To gain a mechanistic understanding of their function, we mapped OSKM-binding, stage-specific transcription-factors (TFs), and chromatin-states in discrete reprogramming stages and performed loss- and gain-of-function experiments. We found that early in reprogramming OSK extensively bind somatic-enhancers and initiate their decommissioning by recruiting Hdac1. Concurrently, OSK engage other sites, including specific pluripotency-enhancers, and induce the relocation of somatic TFs to these sites and away from somatic-enhancers, extending somatic-enhancer decommissioning genome-wide. Pluripotency-enhancer selection early in reprogramming occurs predominantly at sites with high OSK-motif densities and requires collaborative binding by OSK. Most pluripotency-enhancers are selected later and occupied by OS and stage-specific-TFs like Esrrb. Overexpression of stage-specific-TFs influences reprogramming efficiency by changing OSK-occupancy, somatic-enhancer decommissioning, and pluripotency-enhancer selection. We propose that collaborative interactions among OSK and with stage-specific-TFs direct both somatic-enhancer decommissioning and pluripotency-enhancer selection, which drives the enhancer reorganization underlying reprogramming
Project description:N6-methyladenosine (m6A) is the most prevalent mRNA modification with diverse regulatory roles in mammalian cells. While its functions are well-documented in mouse embryonic stem cells (mESCs), its role in human pluripotent stem cells (hPSCs) remains to be fully explored. METTL3 is the main enzyme responsible for m6A deposition. Here, using a METTL3 inducible knockout (iKO) system, we uncovered that, unlike in mESCs, METTL3 was indispensable for hPSC maintenance. Importantly, loss of METTL3 caused significant upregulation of pluripotency factors including naïve pluripotency genes and failure to exit pluripotency, thus impaired stem cell differentiation towards embryonic and extraembryonic cells including trophoblasts. Mechanistically, METTL3 iKO in hPSCs substantially increased expression and enhancer activities of two primate-specific transposable elements (TEs), SVA_D and HERVK/LTR5_Hs, which are normally modified by METTL3-dependent m6A. METTL3 loss activated SVA_D by lowering H3K9me3 deposition, and increased chromatin accessibility at LTR5_Hs through the naïve and other pluripotency factors. Conversely, we discovered that the activated SVA_D and LTR5_Hs loci positively regulated naïve gene expression by directly interacted with their promoters. These findings thus reveal that METTL3-dependent m6A RNA methylation has critical roles in suppressing TE expression and in the human pluripotency regulatory network.