Project description:Covalent modification of DNA distinguishes cellular identities and is crucial for regulating the pluripotency and differentiation of embryonic stem (ES) cells. The recent demonstration that 5-methylcytosine (5-mC) may be further modified to 5-hydroxymethylcytosine (5-hmC) in ES cells has revealed a novel regulatory paradigm to modulate the epigenetic landscape of pluripotency. To understand the role of 5-hmC in the epigenomic landscape of pluripotent cells, here we profile the genome-wide 5-hmC distribution and correlate it with the genomic profiles of 11 diverse histone modifications and six transcription factors in human ES cells. By integrating genomic 5-hmC signals with maps of histone enrichment, we link particular pluripotency-associated chromatin contexts with 5-hmC. Intriguingly, through additional correlations with defined chromatin signatures at promoter and enhancer subtypes, we show distinct enrichment of 5-hmC at enhancers marked with H3K4me1 and H3K27ac. These results suggest potential role(s) for 5-hmC in the regulation of specific promoters and enhancers. In addition, our results provide a detailed epigenomic map of 5-hmC from which to pursue future functional studies on the diverse regulatory roles associated with 5-hmC. Genome wide enrichment profile of 5-hmC in H1 human embryonic stem cells
Project description:Upon retinal injury, zebrafish Müller glia (MG) transition from a quiescent supportive cell to a progenitor cell (MGPC). This event is accompanied by the induction of key transcription and pluripotency factors. Because somatic cell reprogramming during iPSC generation is accompanied by changes in DNA methylation, especially in pluripotency factor gene promoters, we were interested in determining if DNA methylation changes also underlie MG reprogramming following retinal injury. Consistent with this idea, we found that genes encoding components of the DNA methylation/demethylation machinery were induced in MGPCs and that manipulating MGPC DNA methylation with 5-aza-2’-deoxycytidine altered their properties. A comprehensive analysis of the DNA methylation landscape as MG reprogram to MGPCs revealed that demethylation predominates at early times, while levels of de novo methylation increase at later times. We found that these changes in DNA methylation were largely independent of Apobec2 protein expression. A correlation between promoter DNA demethylation and injury-dependent gene induction was noted. In contrast to iPSC formation, we found that pluripotency factor gene promoters were already hypomethylated in quiescent MG and remained unchanged in MGPCs. Interestingly, these pluripotency factor promoters were also found to be hypomethylated in mouse MG. Our data identify a dynamic DNA methylation landscape as zebrafish MG transition to a MGPC and suggest that DNA methylation changes will complement other regulatory mechanisms to ensure gene expression programs controlling MG reprogramming are appropriately activated during retina regeneration. Reduced representation bisulfite sequencing (MspI,~40-220bp size fraction) of zebrafish MG before and after injury. This dataset includes 4 replicated samples: The MG samples report the genomic methylation of a quiescent state. The 4dpi MGPC sampes report the methylation of a dedifferentiated, proliferating progenitor. The 2dpi morpholino samples report the genomic methylation of a dedifferentiated MGPC following a conrtol or Apobec2a,2b knockdown.
Project description:ATAC sequencing of bovine oocytes and early embryos revealed a genome-wide map of accessible chromatin of bovine early embryo development, highlighting the critical features of chromatin landscape and epigenetic reprogramming during bovine preimplantation embryo development.
Project description:Embryonic stem cells (ESCs) are derived from the inner cell mass of preimplantation blastocysts. From agricultural and biomedical perspectives, the derivation of stable ESCs from domestic ungulates is important for genomic testing and selection, genome engineering, and modeling human diseases. Cattle are one of the most important domestic ungulates that are commonly used for food and bioreactors. To date, however, it remains a challenge to produce stable pluripotent bovine ESC lines. Employing a culture system containing fibroblast growth factor 2 and an inhibitor of the canonical Wnt-signaling pathway, we derived pluripotent bovine ESCs (bESCs) with stable morphology, transcriptome, karyotype, population-doubling time, pluripotency marker gene expression, and epigenetic features. Under this condition bESC lines were efficiently derived (100% in optimal conditions), were established quickly (3–4 wk), and were simple to propagate (by trypsin treatment). When used as donors for nuclear transfer, bESCs produced normal blastocyst rates, thereby opening the possibility for genomic selection, genome editing, and production of cattle with high genetic value.
Project description:Here we report that the histone variant macroH2A acts as a barrier to induced pluripotency. Using fibroblasts isolated from macroH2A double knockout mice, we observed enhanced reprogramming efficiency compared to fibroblasts from wild type animals. We further show that macroH2A isoforms act synergistically in this process. Genomic analysis in wild type fibroblasts reveals that macroH2A1 and H3K27me3 domains co-localize and occupy pluripotency genes. While the absence of macroH2A does not affect H3K27me3 in fibroblasts, macroH2A1 is highly enriched at a set of Utx target genes that are reactivated early during iPS reprogramming. Mononucleosomes from Dermal Fibroblasts (from wt and macroH2A1 and macroH2A2 double knockout mice) were isolated and ChIP'd with mH2A1, H3K27me3 and H3K27ac antibodies. DNA from Input and ChIP samples was purified and sequenced on Illumina's Hiseq.
Project description:Embryonic stem cell (ESC) pluripotency is governed by a gene regulatory network centred on the transcription factors Oct4 and Nanog. ESCs fluctuate between states of high and low Nanog expression that direct efficient or inefficient self-renewal. To date, robust self-renewing ESC states have only been attained by chemical inhibition of signalling pathways or enforced transgene expression. Here we show that ESCs expressing a reduced range of Oct4 concentrations, typified by Oct4 heterozygous ESCs exhibit stable robust pluripotency. Despite this reduced Oct4 concentration range, this state is characterised by increased genome-wide binding of Oct4, particularly at pluripotency-associated enhancers, homogeneous expression of pluripotency transcription factors, enhanced self-renewal efficiency and delayed differentiation kinetics. In this state, ESCs exhibit increased wnt expression, enhanced LIF-sensitivity, non-responsiveness to FGF signalling and can clonally maintain pluripotency without BMP but remain dependent upon LIF. Robust pluripotency is destabilised either by alteration of the Oct4 level or by removal of LIF. Our findings suggest that robust pluripotency originates from cells with a reduced Oct4 protein concentration and that the wild-type Oct4 range enables effective differentiation.
Project description:Here we report that the histone variant macroH2A acts as a barrier to induced pluripotency. Using fibroblasts isolated from macroH2A double knockout mice, we observed enhanced reprogramming efficiency compared to fibroblasts from wild type animals. We further show that macroH2A isoforms act synergistically in this process. Genomic analysis in wild type fibroblasts reveals that macroH2A1 and H3K27me3 domains co-localize and occupy pluripotency genes. While the absence of macroH2A does not affect H3K27me3 in fibroblasts, macroH2A1 is highly enriched at a set of Utx target genes that are reactivated early during iPS reprogramming.
Project description:The proteome of undifferentiated human embryonic stem cells (hESCs) was profiled by deep mass spectrometry-based proteomics of whole-cell extracts from suspension cultures of TE03 cells, in four biological replicates. This data accompanies the manuscript: "Uncovering the RNA-binding protein landscape in the pluripotency network of human embryonic stem cells". Abstract: "Embryonic stem cell (ESC) self-renewal and cell-fate decisions are driven by a broad array of molecular signals. While transcriptional regulators have been extensively studied in human ESCs (hESCs), the extent to which RNA-binding proteins (RBPs) contribute to human pluripotency remains unclear. Here, we carry out a proteome-wide screen and identify 810 proteins that directly bind RNA in hESCs. We reveal that RBPs are preferentially expressed in hESCs and dynamically regulated during exit from pluripotency and early lineage specification. Moreover, we show that nearly 200 RBPs are affected by knockdown of OCT4, a master regulator of pluripotency, several dozen of which are directly bound by this factor. Intriguingly, over 20 percent of the proteins detected in our study are putative DNA- and RNA-binding proteins (DRBPs), among them key transcription factors (TFs). Using fluorescently labeled RNA and seCLIP (single-end enhanced crosslinking and immunoprecipitation) experiments, we discover that the pluripotency-associated STAT3 and OCT4 TFs interact with RNA in hESCs and confirm the direct binding of STAT3 to the conserved NORAD long-noncoding RNA. Taken together, our findings indicate that RBPs have a more widespread role in human pluripotency than previously appreciated, reinforcing the importance of post-transcriptional regulation in stem cell biology".