DNA methylation as a reprogramming modulator: An epigenomic roadmap to induced pluripotency
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ABSTRACT:
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| ERR357008_1.fastq.gz | Fastqsanger.gz | |||
| ERR357008_2.fastq.gz | Fastqsanger.gz | |||
| ERR357009_1.fastq.gz | Fastqsanger.gz | |||
| ERR357009_2.fastq.gz | Fastqsanger.gz | |||
| ERR357010_1.fastq.gz | Fastqsanger.gz |
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Project description:Reprogramming of somatic cells to induced pluripotent stem cells involves a dynamic rearrangement of the epigenetic landscape. To characterize this epigenomic roadmap, we have performed MethylC-seq, ChIP-seq (H3K4/K27/K36me3) and RNA-Seq on samples taken at several time points during murine secondary reprogramming as part of Project Grandiose. We find that DNA methylation gain during reprogramming occurs gradually, while loss is achieved only at the ESC-like state. Binding sites of activated factors exhibit focal demethylation during reprogramming, while ESC-like pluripotent cells are distinguished by extension of demethylation to the wider neighbourhood. We observed that genes with CpG-rich promoters demonstrate stable low methylation and strong engagement of histone marks, whereas genes with CpG-poor promoters are safeguarded by methylation. Such DNA methylation-driven control is the key to the regulation of ESC-pluripotency genes, including Dppa4, Dppa5a and Esrrb. These results reveal the crucial role that DNA methylation plays as an epigenetic switch driving somatic cells to pluripotency.
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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. Reduced representation bisulfite sequencing (RRBS) was applied to mouse iPS cells and mouse embryonic fibroblast (MEF) before and after DOX induction (initiating reprogramming by OSKM factors) from randomly selected Mbd3+/+ and Mbd3flox/- clonal cell line series. Polyclonal donor cell cultures were harvested at days 0,4 and 8 after DOX reprogramming without selection or sorting for any marker or passaging, and mapped for similarity to subcloned iPSC lines.
2014-12-13 | E-GEOD-64115 | biostudies-arrayexpress
Project description:Factor-induced reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) is inefficient, complicating mechanistic studies. Here, we examined defined intermediate cell populations poised to becoming iPSCs by genome-wide analyses. We show that induced pluripotency elicits two transcriptional waves, which are driven by c-Myc/Klf4 (first wave) and Oct4/Sox2/Klf4 (second wave). Cells that become refractory to reprogramming activate the first but fail to initiate the second transcriptional wave and can be rescued by elevated expression of all four factors. The establishment of bivalent domains occurs gradually after the first wave, whereas changes in DNA methylation take place after the second wave when cells acquire stable pluripotency. This integrative analysis allowed us to identify genes that act as roadblocks during reprogramming and surface markers that further enrich for cells prone to forming iPSCs. Collectively, our data offer new mechanistic insights into the nature and sequence of molecular events inherent to cellular reprogramming. DNA methylation profiles obtained at different timepoints during reprogramming of somatic cells: Day 0, +3, +6, +9 and iPSC
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Project description:We recently showed that some human induced pluripotent stem cell (iPSC) clones were defective in neural differentiation and were marked with the activation of long term repeats (LTRs) of human endogenous retroviruses (HERVs). We herein demonstrated that these LTRs were transiently overexpressed during the generation of iPSCs and contributed to reprogramming. When the generation of iPSCs was completed, LTRs were re-suppressed to levels similar to those in human ES cells. However, differentiation-defective iPSC clones maintained high LTR expression levels, which indicated that these clones failed to complete reprogramming. lincRNA-RoR, a long intergenic non-coding RNA (lincRNA) that was previously shown to support the induction and maintenance of pluripotency, was detected among the LTR-driven transcripts. Short hairpin RNAs against the conserved sequence in LTRs or lincRNA-RoR markedly reduced the efficiency of iPSC generation. Reprogramming factors including OCT3/4, SOX2, and KLF4 bound to most LTRs. The expression of KLF4 was low in normal iPSC clones, but remained high in differentiation-defective clones. The forced expression of KLF4 in human embryonic stem cells led to the activation of LTRs and defects in neural differentiation. These results demonstrated that the transient overexpression of KLF4/LTR/lincRNA-RoR played crucial roles in reprogramming toward pluripotency in humans, whereas a failure in its re-silence resulted in differentiation defects. Four human induced pluripotent stem cell lines were subcloned into 55 separate lines. Bisulfite converted genomic DNA lysates from fibroblast, induced pluripotent stem cell, intermediate reprogrammed cell and embryonic stem cell lines were hybridized to Illumina HumanMethylation450 BeadChip.
2014-08-04 | E-GEOD-54848 | biostudies-arrayexpress
Project description:Factor induced reprogramming is a slow and inefficient process with only rare cells progressing towards induced pluripotent stem cells (iPSCs). Owing to these restraints, mechanistic studies have been limited to analyses of heterogeneous bulk populations undergoing reprogramming and partially reprogrammed cell lines. Here, by combining surface markers (Thy1, SSEA1) and an Oct4-GFP fluorescent reporter allele, we analyzed defined intermediate cell populations poised to becoming iPSCs at the transcriptional and epigenetic levels using genome-wide and single cell technologies. We found that factor-induced reprogramming elicits two discernible transcriptional waves that are characterized by the initial extinction of the somatic gene expression program and the concomitant acquisition of an ESC-like proliferative and metabolic state, followed by the activation of an embryonic pluripotent state primed for differentiation. The first wave is mostly driven by gene activation through c-Myc and gene repression by Klf4, whereas the second wave is a result of gradually activated Oct4/Sox2 targets in cooperation with Klf4 targets and other downstream regulators. While microRNA expression and enrichment for individual histone modifications (H3K4me3 or H3K27me3 enriched promoters) mirrored the observed biphasic transcriptional pattern, the establishment of bivalent domains (H3K4me3/H3K27me3 enriched promoters) occurred more gradually. In contrast, changes in DNA methylation took place predominantly at the end of reprogramming when cells assumed a stable pluripotent state. Cells that became refractory to reprogramming activated the first but failed to initiate the second transcriptional wave. However, introduction of additional copies of the reprogramming transgenes into these cells rescued their ability to form iPSCs, indicating that suboptimal transcription factor levels are a limiting factor for efficient iPSC formation. This integrative analysis allowed us to identify novel genes and microRNAs that enhance reprogramming and surface markers that further subdivide intermediate cell populations. Collectively, our data offer new mechanistic insights into the nature and sequence of molecular events inherent to cellular reprogramming and provide a valuable resource of molecules that may act as roadblocks during iPSC formation. Time series design with samples sorted into subpopulations according to surface markers. 18 Samples total
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Project description:Differentiated cells can be converted into pluripotent stem cells by expressing the transcription factors OCT4, SOX2, KLF4, and MYC (OSKM) in a process known as reprogramming. Here, using single-cell RNA sequencing of pancreas undergoing reprogramming, we identify markers along the trajectory from acinar cell identity to pluripotency. These markers allow direct in situ visualization of cells undergoing dedifferentiation and acquiring features of early and advanced intermediate reprogramming. We also find that a fraction of cells do not dedifferentiate upon OSKM expression and are characterized by stress markers of the REG3 and AP-1 families. Importantly, most markers of intermediate reprogramming in the pancreas are also observed in stomach, colon, and cultured fibroblasts expressing OSKM. Among them is LY6A, a protein characteristic of progenitor cells and generally upregulated during tissue repair. Our roadmap defines intermediate reprogramming states that could be functionally relevant for tissue regeneration and rejuvenation.
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Project description:Factor induced reprogramming is a slow and inefficient process with only rare cells progressing towards induced pluripotent stem cells (iPSCs). Owing to these restraints, mechanistic studies have been limited to analyses of heterogeneous bulk populations undergoing reprogramming and partially reprogrammed cell lines. Here, by combining surface markers (Thy1, SSEA1) and an Oct4-GFP fluorescent reporter allele, we analyzed defined intermediate cell populations poised to becoming iPSCs at the transcriptional and epigenetic levels using genome-wide and single cell technologies. We found that factor-induced reprogramming elicits two discernible transcriptional waves that are characterized by the initial extinction of the somatic gene expression program and the concomitant acquisition of an ESC-like proliferative and metabolic state, followed by the activation of an embryonic pluripotent state primed for differentiation. The first wave is mostly driven by gene activation through c-Myc and gene repression by Klf4, whereas the second wave is a result of gradually activated Oct4/Sox2 targets in cooperation with Klf4 targets and other downstream regulators. While microRNA expression and enrichment for individual histone modifications (H3K4me3 or H3K27me3 enriched promoters) mirrored the observed biphasic transcriptional pattern, the establishment of bivalent domains (H3K4me3/H3K27me3 enriched promoters) occurred more gradually. In contrast, changes in DNA methylation took place predominantly at the end of reprogramming when cells assumed a stable pluripotent state. Cells that became refractory to reprogramming activated the first but failed to initiate the second transcriptional wave. However, introduction of additional copies of the reprogramming transgenes into these cells rescued their ability to form iPSCs, indicating that suboptimal transcription factor levels are a limiting factor for efficient iPSC formation. This integrative analysis allowed us to identify novel genes and microRNAs that enhance reprogramming and surface markers that further subdivide intermediate cell populations. Collectively, our data offer new mechanistic insights into the nature and sequence of molecular events inherent to cellular reprogramming and provide a valuable resource of molecules that may act as roadblocks during iPSC formation. Time series design with samples sorted into subpopulations according to surface markers.
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Project description:Factor induced reprogramming is a slow and inefficient process with only rare cells progressing towards induced pluripotent stem cells (iPSCs). Owing to these restraints, mechanistic studies have been limited to analyses of heterogeneous bulk populations undergoing reprogramming and partially reprogrammed cell lines. Here, by combining surface markers (Thy1, SSEA1) and an Oct4-GFP fluorescent reporter allele, we analyzed defined intermediate cell populations poised to becoming iPSCs at the transcriptional and epigenetic levels using genome-wide and single cell technologies. We found that factor-induced reprogramming elicits two discernible transcriptional waves that are characterized by the initial extinction of the somatic gene expression program and the concomitant acquisition of an ESC-like proliferative and metabolic state, followed by the activation of an embryonic pluripotent state primed for differentiation. The first wave is mostly driven by gene activation through c-Myc and gene repression by Klf4, whereas the second wave is a result of gradually activated Oct4/Sox2 targets in cooperation with Klf4 targets and other downstream regulators. While microRNA expression and enrichment for individual histone modifications (H3K4me3 or H3K27me3 enriched promoters) mirrored the observed biphasic transcriptional pattern, the establishment of bivalent domains (H3K4me3/H3K27me3 enriched promoters) occurred more gradually. In contrast, changes in DNA methylation took place predominantly at the end of reprogramming when cells assumed a stable pluripotent state. Cells that became refractory to reprogramming activated the first but failed to initiate the second transcriptional wave. However, introduction of additional copies of the reprogramming transgenes into these cells rescued their ability to form iPSCs, indicating that suboptimal transcription factor levels are a limiting factor for efficient iPSC formation. This integrative analysis allowed us to identify novel genes and microRNAs that enhance reprogramming and surface markers that further subdivide intermediate cell populations. Collectively, our data offer new mechanistic insights into the nature and sequence of molecular events inherent to cellular reprogramming and provide a valuable resource of molecules that may act as roadblocks during iPSC formation. Time series design with samples sorted into subpopulations according to surface markers.
2012-12-20 | E-GEOD-42379 | biostudies-arrayexpress
Project description:N6-methyladenosine (m6A) has been recently identified as a conserved epitranscriptomic modification of eukaryotic mRNAs, but its features, regulatory mechanisms, and functions in cell reprogramming are largely unknown. Here, we report m6A modification profiles in the mRNA transcriptomes of four cell types with different degrees of pluripotency. Comparative analysis reveals several features of m6A, especially gene- and cell-type-specific m6A mRNA modifications. We also show that microRNAs (miRNAs) regulate m6A modification via a sequence pairing mechanism. Manipulation of miRNA expression or sequences alters m6A modification levels through modulating the binding of METTL3 methyltransferase to mRNAs containing miRNA targeting sites. Increased m6A abundance promotes the reprogramming of mouse embryonic fibroblasts (MEFs) to pluripotent stem cells; conversely, reduced m6A levels impede reprogramming. Our results therefore uncover a role for miRNAs in regulating m6A formation of mRNAs and provide a foundation for future functional studies of m6A modification in cell reprogramming. m6A-seq in ESC, iPSC, NSC and sertoli cells.
2015-03-10 | E-GEOD-52125 | biostudies-arrayexpress
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).
2013-09-12 | E-GEOD-45352 | biostudies-arrayexpress