Project description:Pluripotency can be induced in somatic cells by ectopic expression of defined transcription factors, however the identity of epigenetic regulators driving the progression of cellular reprogramming requires further investigation. Here we uncover a non-redundant role for the JmjC-domain-containing protein histone H3 methylated Lys 27 (H3K27) demethylase Utx, as a critical regulator for the induction, but not for the maintenance, of primed and naM-CM-/ve pluripotency in mice and in humans. Utx depletion results in aberrant H3K27me3 repressive chromatin demethylation dynamics, which subsequently hampers the reactivation of pluripotency promoting genes during reprogramming. Remarkably, Utx deficient primordial germ cells (PGCs) display a cell autonomous aberrant epigenetic reprogramming in vivo during their embryonic maturation, resulting in the lack of functional contribution to the germ-line lineage. H3K27me3 and H3K4me3 were measured genome-wide in the following cell types: Utx+/Y (WT) and Utx-/Y (KO) mouse ES cells and mouse embryonic fibroblast (MEF) before and after DOX induction (initiating reprogramming by OSKM factors).
Project description:Somatic cells can be directly reprogrammed to pluripotency by exogenous expression of transcription factors, classically Oct4, Sox2, Klf4 and c-Myc. While distinct types of somatic cells can be reprogramed with varying efficiencies and by different modified reprogramming protocols, induced pluripotent stem cell (iPSC) induction remains inefficient and stochastic where a fraction of the cells converts into iPSCs. The nature of rate limiting barrier(s) preventing majority of cells to convert into iPSCs remains elusive. Here we show that neutralizing Mbd3, a core member of the Mbd3/NURD co-repressor and chromatin-remodeling complex, results in deterministic and synchronized reprogramming of multiple differentiated cell types to pluripotency. 100% of Mbd3 depleted mouse and human somatic cells convert into iPSCs after seven days of reprogramming factor induction. Our findings delineate a critical pathway blocking the reestablishment of pluripotency, and offer a novel platform for future dissection of epigenetic dynamics leading to iPSC formation at high resolution. Samples include Mbd3+/+, Mbd3flox/- and Mbd3-/- cells from mouse ES cells and mouse embryonic fibroblast (MEF) before and after DOX induction (initiating reprogramming by OSKM factors). Two histone modifications are given: H3K4me3, H3K27me3. In addition binding data of Mbd3 and Mi2B in various stages.
Project description:This SuperSeries is composed of the following subset Series: GSE35775: The H3K27 demethylase Utx facilitates somatic and germ cell epigenetic reprogramming to pluripotency [Affymetrix gene expression] GSE37821: The H3K27 demethylase Utx facilitates somatic and germ cell epigenetic reprogramming to pluripotency [ChIP-Seq] Refer to individual Series
Project description:Mouse embryonic stem (ES) cells are isolated from the inner cell mass of blastocysts, and can be preserved in vitro in a naive inner-cell-mass-like configuration by providing exogenous stimulation with leukaemia inhibitory factor (LIF) and small molecule inhibition of ERK1/ERK2 and GSK3b signalling (termed 2i/LIF conditions). Hallmarks of naive pluripotency include driving Oct4 (also known as Pou5f1) transcription by its distal enhancer, retaining a pre-inactivation X chromosome state, global reduction in DNA methylation and in H3K27me3 repressive chromatin mark deposition on developmental regulatory gene promoters.Upon withdrawal of 2i/LIF, naM-CM-/ve mouse ES cells can drift towards a primed pluripotent state resembling that of the post-implantation epiblast. Although human ES cells share several molecular features with naive mouse ES cells, they also share a variety of epigenetic properties with primed murine epiblast stem cells (EpiSCs). These include use of the proximal enhancer element to maintain OCT4 expression, pronounced tendency for X chromosome inactivation in most female human ES cells, increase in DNA methylation and prominent deposition of H3K27me3 and bivalency acquisition on lineage regulatory genes. The feasibility for establishing human ground state naive pluripotency in vitro with equivalent molecular and functional features to those characterized in rodent ES cells remains to be defined. Here we establish defined conditions that facilitate the derivation of genetically unmodified human naive pluripotent stem cells from already established primed human ES cells, from somatic cells through induced pluripotent stem (iPS) cell reprogramming or directly from blastocysts. The novel naive pluripotent cells validated herein retain molecular characteristics and functional properties that are highly similar to mouse naive ES cells, and distinct from conventional primed human pluripotent cells. This includes competence in the generation of cross-species chimaeric embryos that underwent organogenesis following microinjection of human naive iPS cells into mouse morulas. Collectively, our findings establish new avenues for regenerative medicine, patient-specific iPS cell disease modelling and the study of early human development in vitro and in vivo. Four chromatin marks H3K4me1, H3K4me3, H3K27ac and H3K27me3 were measured from 3 cell lines: C1 and WIBR3 (naM-CM-/ve and conventional/primed stem cells), and BGO1 (only naM-CM-/ve stem cells).
Project description:Chromatin remodeling proteins are frequently dysregulated in human cancer, yet little is known about how they control tumorigenesis. Here, we uncover an epigenetic program mediated by the NAD+-dependent histone deacetylase Sirtuin 6 (SIRT6) that is critical for suppression of pancreatic ductal adenocarcinoma (PDAC), one of the most lethal malignancies. SIRT6 inactivation accelerates PDAC progression and metastasis via upregulation of Lin28b, a negative regulator of the let-7 microRNA. SIRT6 loss results in histone hyperacetylation at the Lin28b promoter, Myc recruitment, and pronounced induction of Lin28b and downstream let-7 target genes, HMGA2, IGF2BP1 and IGF2BP3. This epigenetic program defines a distinct subset representing 30-40% of human PDAC, characterized by poor prognosis and an exquisite dependence on Lin28b for tumor growth. Thus, we identify SIRT6 as an important PDAC tumor suppressor, and uncover the Lin28b pathway as a potential therapeutic target in a molecularlydefined PDAC subset. ChIP-Seq experiments to examine H3K56ac histone modifications in murine PDAC cells that are Sirt6 wild type (WT), Sirt6 knock-out (KO), and Sirt6 KO cells engineered to express Sirt6 WT (Sirt6 KO + Sirt6 WT Restored).
Project description:The pioneer interactions between incoming viral RNA genomes and host proteins are crucial to infection and immune response. Until now, the ability to study these events was lacking. We developed VIR-CLASP (VIRal Cross-Linking And Solid-phase Purification) to characterize the earliest interactions between viral RNA and cellular proteins. We investigated the infection of human cells using Chikungunya virus (CHIKV) and Influenza A virus and identified hundreds of direct RNA-protein interactions. Here, we validate the biological impact of three protein classes that bind CHIKV RNA within minutes of infection. We find CHIKV RNA binds and hijacks the lipid-modifying enzyme FASN for pro-viral activity. We show that CHIKV genomes are N6-methyladenosine modified and that YTHDF1 binds and suppresses its replication. Finally, we find that the innate immune DNA sensor IFI16 associates with CHIKV RNA, reducing viral replication and maturation. Our findings have direct applicability to the investigation of potentially all RNA viruses.
Project description:In this study we identify Mettl3, an m6A RNA modification writer, as a critical regulator for terminating naM-CM-/ve pluripotency and a positive maintainer of primed pluripotency in vitro and in vivo. Remarkably, Mettl3 knockout pre-implantation epiblasts and naM-CM-/ve ES cells, entirely lack m6A on coding mRNAs and are viable. Yet, they fail to adequately terminate the naM-CM-/ve 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 naM-CM-/ve 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 naM-CM-/ve and primed pluripotency in an opposing manner. 3' polyA RNA-sequencing (equivalent to Digital Gene Expression) measured in mouse Embryonic Stem Cells (ESCs) and mouse Embriod bodies (EBs) 0,4 & 8 hours after treatment with Actinomycin which halts transcription. Measured in both WT and Mettl3-KO cells.
Project description:Human pluripotent stem cell derived models that accurately recapitulate neural development in vitro and allow for the generation of specific neuronal subtypes are of major interest to the stem cell and biomedical community. Notch signaling, particularly through the Notch effector HES5, is a major pathway critical for the onset and maintenance of neural progenitor cells (NPCs) in the embryonic and adult nervous system1-3. Use of a HES5 reporter enables the isolation distinct populations of human embryonic stem (ES) cell derived NPCs that represent building blocks of cortical development in vitro4. Here, we report the transcriptional and epigenomic analysis of six consecutive stages of human ES cell differentiation along the neural lineage aimed at modeling key cell fate decisions including specification, expansion and patterning during the ontogeny of neural stem and progenitor cells. In order to dissect the regulatory mechanisms that orchestrate the stage-specific differentiation process we developed a computational framework to infer key regulators of each cell state transition based on the progressive remodeling of the epigenetic landscape and then validated these through a pooled shRNA screen. We were also able to refine our previous observations on epigenetic priming at transcription factor binding sites and show here that they are mediated by combinations of core and stage-specific factors. Taken together, we demonstrate the utility of our reference maps and outline a general framework, not limited to the context of the neural lineage, to dissect regulatory circuits of differentiation. hESC were differentiated in vitro into 5 different NPC populations (NE, ERG, MRG, LRG and LNP) over a time period of 220 days. The hESCs and the first 3 NPC populations (NE, ERG, MRG) were subjected to ChIP-Seq for H3K4m3, H3K4me1, H3K27ac and H3K27me3 as well as RNA-Seq with two biological replicates each as well as whole genome bisulfite sequencing in singlicate. The last two populations (LRG, LNP) were both profiled by RRBS and the LRG populations also by RNA-Seq. In addition, each of the first three NPC populations were differentiated into more mature neuronal populations (NEdN, ERGdN, MRGdN). The LRG population was differentiated along the astrocyte fate (LRGdA). Each of these more mature populations was subjected to RNA-Seq in replicate. Finally, the NE and MRG populations were profiled for the transcription facctor OTX2 by ChIP-Seq.