An epigenetic switch ensures transposon repression upon acute loss of DNA methylation in ES cells
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE71593 | GEO | 2016/01/27
SECONDARY ACCESSION(S): PRJNA291588
REPOSITORIES: GEO
Similar Datasets
Project description:DNA methylation is extensively remodeled during mammalian gametogenesis and embryogenesis. Most transposons become hypomethylated, raising the question of their regulation in the absence of DNA methylation. To reproduce a rapid and extensive demethylation, we subjected mouse ES cells to chemically defined hypomethylating culture conditions. Surprisingly, we observed two phases of transposon regulation. After an initial burst of de-repression, various transposon families were efficiently re-silenced. This was accompanied by a reconfiguration of the repressive chromatin landscape: while H3K9me3 was stable, H3K9me2 globally disappeared and H3K27me3 accumulated at transposons. Interestingly, we observed that H3K9me3 and H3K27me3 occupy different transposon families or different territories within the same family, defining three functional categories of adaptive chromatin responses to DNA methylation loss. Our work highlights that H3K9me3 and, most importantly, polycomb-mediated H3K27me3 chromatin pathways can secure the control of a large spectrum of transposons in periods of intense DNA methylation change, ensuring longstanding genome stability.
| S-EPMC4769179 | biostudies-literature
Project description:DNA methylation profoundly impacts genome regulation, notably through the control of transposons. DNA methylation is extensively remodeled during two developmental periods in mammals, gametogenesis and early embryogenesis. Most of transposons families become then hypomethylated, raising the question of their regulation in absence of DNA methylation. To induce genome-wide demethylation, we relied on hypomethylation-inducing culture conditions of murine embryonic stem cells. Surprisingly, we observed two phases of transposon regulation. After a burst of derepression, which correlates with DNA methylation disappearance, both LTR and non-LTR retrotransposons were efficiently re-silenced. While histone H3 lysine 9 trimethylation (H3K9me3) remained stable, H3 lysine 27 trimethylation (H3K27me3) was reorganized upon loss of DNA methylation and contributed to transposon re-silencing. Interestingly, we observed that H3K9me3 and H3K27me3 co-occurred but in distinct regions of unmethylated transposon sequences. This unusual pattern may provide a mechanistic relay ensuring genome stability during developmental periods of programmed loss of DNA methylation.
2016-01-27 | GSE71592 | GEO
Project description:DNA methylation profoundly impacts genome regulation, notably through the control of transposons. DNA methylation is extensively remodeled during two developmental periods in mammals, gametogenesis and early embryogenesis. Most of transposons families become then hypomethylated, raising the question of their regulation in absence of DNA methylation. To induce genome-wide demethylation, we relied on hypomethylation-inducing culture conditions of murine embryonic stem cells. Surprisingly, we observed two phases of transposon regulation. After a burst of derepression, which correlates with DNA methylation disappearance, both LTR and non-LTR retrotransposons were efficiently re-silenced. While histone H3 lysine 9 trimethylation (H3K9me3) remained stable, H3 lysine 27 trimethylation (H3K27me3) was reorganized upon loss of DNA methylation and contributed to transposon re-silencing. Interestingly, we observed that H3K9me3 and H3K27me3 co-occurred but in distinct regions of unmethylated transposon sequences. This unusual pattern may provide a mechanistic relay ensuring genome stability during developmental periods of programmed loss of DNA methylation.
2016-01-27 | GSE71591 | GEO
Project description:DNA methylation profoundly impacts genome regulation, notably through the control of transposons. DNA methylation is extensively remodeled during two developmental periods in mammals, gametogenesis and early embryogenesis. Most of transposons families become then hypomethylated, raising the question of their regulation in absence of DNA methylation. To induce genome-wide demethylation, we relied on hypomethylation-inducing culture conditions of murine embryonic stem cells. Surprisingly, we observed two phases of transposon regulation. After a burst of derepression, which correlates with DNA methylation disappearance, both LTR and non-LTR retrotransposons were efficiently re-silenced. While histone H3 lysine 9 trimethylation (H3K9me3) remained stable, H3 lysine 27 trimethylation (H3K27me3) was reorganized upon loss of DNA methylation and contributed to transposon re-silencing. Interestingly, we observed that H3K9me3 and H3K27me3 co-occurred but in distinct regions of unmethylated transposon sequences. This unusual pattern may provide a mechanistic relay ensuring genome stability during developmental periods of programmed loss of DNA methylation.
2016-01-27 | GSE71589 | GEO
Project description:An epigenetic switch ensures transposon repression upon acute loss of DNA methylation in ES cells
| PRJNA291588 | ENA
Project description:Reduced expression of the uptake transporter, OCTN1 (SLC22A4), has been reported as a strong predictor of poor event-free and overall survival in multiple cohorts of patients with acute myeloid leukemia (AML) receiving the cytidine nucleoside analog, cytarabine (Ara-C). To further understand the mechanistic basis of interindividual variability in the functional expression of OCTN1 in AML, we hypothesized a mechanistic connection to DNA methylation-based epigenetic repression of SLC22A4. We found increased basal SLC22A4 methylation was associated with decreased Ara-C uptake in AML cell lines. Pre-treatment with hypomethylating agents, 5-azacytidine, or decitabine, restored SLC22A4 mRNA expression, increased cellular uptake of Ara-C, and was associated with increased cellular sensitivity to Ara-C compared with vehicle-treated cells. Additionally, lower SLC22A4 methylation status was associated with distinct clinical advantages in both adult and pediatric patients with AML. These findings suggest a regulatory mechanism is involved in the interindividual variability in response to Ara-C, and provides a basis for the integration of hypomethylating agents into Ara-C-based treatment regimens.
| S-EPMC7877866 | biostudies-literature
Project description:BackgroundThe cis-acting promoter element responsible for epigenetic silencing of retinoic acid receptor responder 1 (RARRES1) by methylation is unclear. Likewise, how aberrant methylation interplays effectors and thus affects breast neoplastic features remains largely unknown.Methodology/principal findingsWe first compared methylation occurring at the sequences (-664~+420) flanking the RARRES1 promoter in primary breast carcinomas to that in adjacent benign tissues. Surprisingly, tumor cores displayed significantly elevated methylation occurring solely at the upstream region (-664~-86), while the downstream element (-85~+420) proximal to the transcriptional start site (+1) remained largely unchanged. Yet, hypermethylation at the former did not result in appreciable silencing effect. In contrast, the proximal sequence displayed full promoter activity and methylation of which remarkably silenced RARRES1 transcription. This phenomenon was recapitulated in breast cancer cell lines, in which methylation at the proximal region strikingly coincided with downregulation. We also discovered that CTCF occupancy was enriched at the unmethylayed promoter bound with transcription-active histone markings. Furthermore, knocking-down CTCF expression hampered RARRES1 expression, suggesting CTCF positively regulated RARRES1 transcription presumably by binding to unmethylated promoter poised at transcription-ready state. Moreover, RARRES1 restoration not only impeded cell invasion but also promoted death induced by chemotherapeutic agents, denoting its tumor suppressive effect. Its role of attenuating invasion agreed with data generated from clinical specimens revealing that RARRES1 was generally downregulated in metastatic lymph nodes compared to the tumor cores.Conclusion/significanceThis report delineated silencing of RARRES1 by hypermethylation is occurring at a proximal promoter element and is associated with a loss of binding to CTCF, an activator for RARRES1 expression. We also revealed the tumor suppressive roles exerted by RARRES1 in part by promoting breast epithelial cell death and by impeding cell invasion that is an important property for metastatic spread.
| S-EPMC3355180 | biostudies-literature
Project description:Changes in the enzymatic activity of protein arginine methyltransferase (PRMT) 5 have been associated with cancer; however, the protein's role in acute myeloid leukemia (AML) has not been fully evaluated. Here, we show that increased PRMT5 activity enhanced AML growth in vitro and in vivo while PRMT5 downregulation reduced it. In AML cells, PRMT5 interacted with Sp1 in a transcription repressor complex and silenced miR-29b preferentially via dimethylation of histone 4 arginine residue H4R3. As Sp1 is also a bona fide target of miR-29b, the miR silencing resulted in increased Sp1. This event in turn led to transcription activation of FLT3, a gene that encodes a receptor tyrosine kinase. Inhibition of PRMT5 via sh/siRNA or a first-in-class small-molecule inhibitor (HLCL-61) resulted in significantly increased expression of miR-29b and consequent suppression of Sp1 and FLT3 in AML cells. As a result, significant antileukemic activity was achieved. Collectively, our data support a novel leukemogenic mechanism in AML where PRMT5 mediates both silencing and transcription of genes that participate in a 'yin-yang' functional network supporting leukemia growth. As FLT3 is often mutated in AML and pharmacologic inhibition of PRMT5 appears feasible, the PRMT5-miR-29b-FLT3 network should be further explored as a novel therapeutic target for AML.
| S-EPMC8034866 | biostudies-literature
Project description:Transgenesis is a cornerstone of molecular biology. The ability to integrate a specifically engineered piece of DNA into the genome of a living system is fundamental to our efforts to understand life and exploit its implications for medicine, nanotechnology and bioprospecting. However, transgenesis has been hampered by position effects and multi-copy integration problems, which are mainly due to the use of small, plasmid-based transgenes. Large transgenes based on native genomic regions cloned into bacterial artificial chromosomes (BACs) circumvent these problems but are prone to fragmentation. Herein, we report that contrary to widely held notions, large BAC-sized constructs do not prohibit transposition. We also report the first reliable method for BAC transgenesis in human embryonic stem cells (hESCs). The PiggyBac or Sleeping Beauty transposon inverted repeats were integrated into BAC vectors by recombineering, followed by co-lipofection with the corresponding transposase in hESCs to generate robust fluorescent protein reporter lines for OCT4, NANOG, GATA4 and PAX6. BAC transposition delivers several advantages, including increased frequencies of single-copy, full-length integration, which will be useful in all transgenic systems but especially in difficult venues like hESCs.
| S-EPMC3479164 | biostudies-literature
Project description:Somaclonal variation arises in plants and animals when differentiated somatic cells are induced into a pluripotent state, but the resulting clones differ from each other and from their parents. In agriculture, somaclonal variation has hindered the micropropagation of elite hybrids and genetically modified crops, but the mechanism responsible remains unknown. The oil palm fruit 'mantled' abnormality is a somaclonal variant arising from tissue culture that drastically reduces yield, and has largely halted efforts to clone elite hybrids for oil production. Widely regarded as an epigenetic phenomenon, 'mantling' has defied explanation, but here we identify the MANTLED locus using epigenome-wide association studies of the African oil palm Elaeis guineensis. DNA hypomethylation of a LINE retrotransposon related to rice Karma, in the intron of the homeotic gene DEFICIENS, is common to all mantled clones and is associated with alternative splicing and premature termination. Dense methylation near the Karma splice site (termed the Good Karma epiallele) predicts normal fruit set, whereas hypomethylation (the Bad Karma epiallele) predicts homeotic transformation, parthenocarpy and marked loss of yield. Loss of Karma methylation and of small RNA in tissue culture contributes to the origin of mantled, while restoration in spontaneous revertants accounts for non-Mendelian inheritance. The ability to predict and cull mantling at the plantlet stage will facilitate the introduction of higher performing clones and optimize environmentally sensitive land resources.
| S-EPMC4857894 | biostudies-literature