Project description:Inhibitors of MEK1/2 and Gsk3b, known as '2i' culture conditions, enhance the derivation of embryonic stem cells (ESCs) and promote ground-state pluripotency in rodents 1,2. Here we show that the derivation of female mouse ESCs in the presence of 2i (2i-ESCs) results in a widespread loss of DNA methylation including a massive erasure of genomic imprints. Despite this global loss of DNA methylation, the early-passage 2i-ESCs efficiently differentiate into somatic cells and this process requires genome-wide de novo DNA methylation. However, the majority of imprinting control regions (ICRs) remain unmethylated in the 2i-ESC-derived differentiated cells. Consistently, 2i-ESCs exhibit impairment of autonomous embryonic and placental development by tetraploid embryo complementation and nuclear transplantation. We identified the derivation conditions of female ESCs that display 2i-ESC-like transcriptional signatures while preserving gamete-derived DNA methylation and autonomous developmental potential. Upon prolonged culture, however, female ESCs exhibit ICR demethylation, regardless of culture conditions. Our results provide insights into derivation of female ESCs reminiscent of ICM of preimplantation embryos. S-ESCs are ESCs established under serum-containing medium. 2i_S_ESCs are ESCs established in 2i-containing medium, followed by maintenance in serum-containing medium.
Project description:Preimplantation embryos undergo a transient wave of genome-wide demethylation with the exception of imprinted genes that are critical for fetal development. Here we show that the derivation of female mouse embryonic stem cells (ESCs) in the presence of inhibitors of MEK1/2 and Gsk3 (2i-ESCs), known as ‘2i’ or “ground-state” culture conditions, results in a widespread loss of DNA methylation including a massive erasure of genomic imprints. In this study, we analyzed global gene expression profile and global DNA methylation status in 2i-ESCs and 2i-ESCs derived differentiated cells. S-ESCs are ESCs established under serum-containing medium. 2i_S_ESCs are ESCs established in 2i-containing medium, followed by maintenance in serum-containing medium.
Project description:Derivation of naive state of mouse embryonic stem cells (mESCs) in LIF+serum (LS) culture condition is strain dependent, whereas derivation of ground state mESCs is readily possible from all strains tested so far in “2i” culture condition. ESCs can be derived from the post-implantation stage mouse embryos (EpiSCs), showing primed characteristics. In the present study, we characterized and compared the transcriptional profile of naïve, primed and ground state mESCs. Considering the importance of genetic background of mouse model for ESCs derivation in conventional culture conditions, all ESCs lines used in the study were derived from the same strain of mice. We found distinct transcriptional profiles between naive, primed and ground state mESCs. Primed state mESCs exhibit lower expression of pluripotency markers along with higher expression of lineage specific markers compared to naive and ground state mESCs. We also demonstrate that the differentiation propensity of ESCs to specific germ layer varies depending on the pluripotency state of ESCs.
Project description:Here we report the derivation of human parthenogenetic haploid ESCs which contain only one set of chromosome. These two cell lines, which we designated hPGES1 and hPGES2, show conventional ESCs and parthenogenetic-derived DNA methylation state.
Project description:Dynamic reprogramming of global DNA methylation impacts on the genomic deposition of the Polycomb-mediated repressive histone mark H3K27me3. DNA hypomethylation in ground state embryonic stem cells (ESCs) results in a reversible redistribution of H3K27me3 from its normal target loci. Thus, a signalling induced shift of ESCs to ground state results in both DNA methylation and Polycomb patterns that are quite distinct from their primed counterparts. Here we investigated the impact of DNA methylation directed Polycomb redistribution on higher-order chromatin structure in the ground state. Using a targeted single-locus approach (FISH) we can demonstrate local decompaction at Hox loci in the ground state, which is consistent with genome-wide data (Hi-C) indicating that chromatin structure is globally altered in ground state relative to primed ESCs. Polycomb targets are similarly decompacted in hypomethylated E3.5 mouse blastocysts. ESC lines which maintain a high level of DNA methylation in ground state show no decompaction at Hox loci. Our results suggest that DNA-methylation mediated reprogramming of Polycomb binding drives higher order chromatin organisation in stem cells and early development.
Project description:The ground state of pluripotency is defined as a basal proliferative state free of epigenetic restriction, represented by mouse embryonic stem cells (ESCs) cultured with two kinase inhibitors (so-called “2i”). Through comparison with serum-grown ESCs, we identify epigenetic features characterizing 2i ESCs by proteome profiling of chromatin including post-translational histone modifications. The most prominent difference is H3K27me3 and its enzymatic writer complex PRC2 that are highly abundant on eu- and heterochromatin in 2i ESCs, with H3K27me3 redistributing outside canonical PRC2 targets in a CpG-dependent fashion. Using PRC2-deficient 2i ESCs, we identify epigenetic crosstalk with H3K27me3, including significant increases in H4 acetylation and DNA methylation. This suggests that the unique H3K27me3 configuration protects 2i ESCs from preparation to lineage priming. Interestingly, removal of DNA methylation in PRC2-deficient 2i ESCs lacking H3K27me3 using 5-azacytidine hardly affected ESC viability and transcriptome, showing that ESCs are independent of both major repressive epigenetic marks.
Project description:Inhibitors of Mek1/2 and Gsk3b, known as 2i, and together with leukemia inhibitory factor, enhance the derivation of embryonic stem cells (ESCs) and promote ground-state pluripotency (2i/L-ESCs). However, recent reports show prolonged Mek1/2 suppression impairs the developmental potential of ESCs, and is rescued by serum (S/L-ESCs). In spite of the unclear roles of growth factors in serum, the coculture system has remained the gold standard. Here we show that culturing ESCs in Activin A, BMP4 and in the absence of MEK1/2 inhibitor (ABC/L medium) establishes stable ESCs, named advanced pluripotent stem cells derived from ESCs (esASCs). We demonstrate that esASCs contributed to germline lineages, full term chimeras and generated esASCs-derived mice by tetraploid complementation. We show that in contrast to 2i/L-ESCs, these esASCs display distinct molecular signatures and stable hypermethylated epigenome which is reversible and similar to S/L-ESCs. Importantly, we also derived novel ASCs (blASCs) from blastocysts in ABC/L medium. These blASCs are persisting at an intermediate state between naïve and primed state of pluripotency and stable hypermethylated epigenome. Our results provide insights into the derivation of novel ESCs with DNA hypermethylation from blastocysts in a chemically defined medium.
Project description:The pluripotent ground state is defined as a basal state free of epigenetic restrictions, which influence lineage specification. While naive embryonic stem cells (ESCs) can be maintained in a hypomethylated state with open chromatin when grown using two small-molecule inhibitors (2i)/leukemia inhibitory factor (LIF), in contrast to serum/LIF-grown ESCs that resemble early post-implantation embryos, broader features of the ground-state pluripotent epigenome are not well understood. We identified epigenetic features of mouse ESCs cultured using 2i/LIF or serum/LIF by proteomic profiling of chromatin-associated complexes and histone modifications. Polycomb-repressive complex 2 (PRC2) and its product H3K27me3 are highly abundant in 2i/LIF ESCs, and H3K27me3 is distributed genome-wide in a CpG-dependent fashion. Consistently, PRC2-deficient ESCs showed increased DNA methylation at sites normally occupied by H3K27me3 and increased H4 acetylation. Inhibiting DNA methylation in PRC2-deficient ESCs did not affect their viability or transcriptome. Our findings suggest a unique H3K27me3 configuration protects naive ESCs from lineage priming, and they reveal widespread epigenetic crosstalk in ground-state pluripotency.