Mus musculus
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PROVIDER: PRJNA257271 | ENA |
REPOSITORIES: ENA
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Project description:In this study, we analyzed the DNA methylation levels of 4799 IAP LTRs in three murine cell types: AB2.2 ES cells, somatic cells and a neuroblastoma cell line Neuro2A. According to the results, half of the IAP LTR retrotransposons show constant methylation patterns between the three cell types whereas the remaining half display variable levels of methylation. About half of the variably methylated IAP LTRs tend to be hypomethylated in ES cells, and nearly all of this group are hypomethylated in Neuro2A cells. Interestingly, the observed hypomethylation in both cell types occur in a non-uniform, locus-specific manner and to various degrees of severity, with some of them being easily detectible by COBRA. Overall, this study demonstrates the feasibility of HT-TREBS to study alterations in DNA methylation at retrotransposons in a locus-specific manner in multiple cell types and further suggests the potential utility of this technique in developing epigenetic biomarkers for tracking disease progression. HT-TREBS has been used with the Ion Torrent PGM platform to analyze the DNA methylation of 4799 IAP LTRs in a locus-specific manner in 3 cell types: somatic cells (previously submitted under GEO Accession GSE49222), AB2.2 ES cells and Neuro2A cells
2015-06-15 | E-GEOD-60007 | biostudies-arrayexpress
Project description:IAP is one of the most transpositinally active retrotransposons in the mouse. Its transcription starts from the 5' long terminal repeat (LTR), and the expression level varied between cell types. This variation is thought to arise from differences in the epigenetic states, such as DNA methylation, of some copies of the 5' LTR between the cells. However, due to the high copy number and high sequence similarity, it was difficult to comprehensively and individually analyze epigenetic state of the IAP LTRs. Here, we developed a method called TEPBAT (Target Enrichment after Post-Bisulfite Adaptor Tagging) to analyze DNA methylation of individual retrotransposon copies. Using the method, we determined DNA methylation levels of >8,500 copies of genomic IAP LTRs (>97% of the copies targeted by the PCR primer) in sperm and tail. This revealed that the vast majority of the LTRs were heavily methylated both in sperm and tail, but hypomethylated copies were more frequently found in sperm than in tail. Interestingly, most of these hypomethylated LTRs were solo-type, belonged to specific subfamilies, and carried binding sites for transcription factors (TFs) active in male germ cells. We discuss possible roles for these TF-binding sites and the IAP internal sequence in regulation of LTR methylation.
2018-02-13 | GSE102989 | GEO
Project description:In this study, we analyzed the DNA methylation levels of 4799 IAP LTRs in three murine cell types: AB2.2 ES cells, somatic cells and a neuroblastoma cell line Neuro2A. According to the results, half of the IAP LTR retrotransposons show constant methylation patterns between the three cell types whereas the remaining half display variable levels of methylation. About half of the variably methylated IAP LTRs tend to be hypomethylated in ES cells, and nearly all of this group are hypomethylated in Neuro2A cells. Interestingly, the observed hypomethylation in both cell types occur in a non-uniform, locus-specific manner and to various degrees of severity, with some of them being easily detectible by COBRA. Overall, this study demonstrates the feasibility of HT-TREBS to study alterations in DNA methylation at retrotransposons in a locus-specific manner in multiple cell types and further suggests the potential utility of this technique in developing epigenetic biomarkers for tracking disease progression.
2015-06-15 | GSE60007 | GEO
Project description:Mammalian genomes have evolutionary harbored numerous mobile elements, a part of which are still active and evoke genomic instability. Their movement and positional diversity occasionally result in phenotypic changes and variation by causing altered expression and disruption of neighboring genes in the host genome. Here, we describe a novel microarray-based method by which dispersed genomic locations of a type of retrotransposons in mammalian genome can be identified at a time. By this method, we mapped the DNA elements for a mouse retrotransposon, intracisternal A-particle (IAP), within genomes of C3H/He and C57BL/6J inbred mouse strains; consequently we detected hundreds of probable IAP cDNA-integrating genomic regions. Among 147 putative insertions located nearby the promoter regions, 91 were considered to be present discriminatively in the genome either of C3H/He or C57BL/6J mice, suggesting the existence of considerable strain differences. In addition, by comparing genomic DNAs from a radiation-induced myeloid leukemia and its reference normal tissue, we detected 3 genomic regions around which an IAP element was integrated. These results demonstrate for the first time the successful genome-wide survey of a type of retrotransposon in mammalian genome. Keywords: retrotransposon mapping Genomic DNA fragments containing sequences that flank a mouse retrotransposon are purified and hybridized to the microarray. Experiments are comparisions between signal intensities obtained from Cy3-labeled purified DNA fragments (test) and Cy5-labeled whole genomic DNA fragments (reference).
2008-05-03 | E-GEOD-9572 | biostudies-arrayexpress
Project description:Methylated mammalian promoters are transcriptionally silenced even in the presence of all the factors required for their expression. Repression requires the assembly of a methylation-dependent silencing complex that contains the TRIM28 (also known as KAP1 and TIF1β) protein. An internally controlled interaction screen identified O-linked β-N-acetylglucosamine transferase (O-GlcNAc transferase or OGT) as a protein that was complexed with TRIM28 in wild type em-bryonic stem cells but not in Dnmt1-/- cells that had severely demethylated genomes. In the ab-sence of DNA methylation, multiple proteins associated with TRIM28 failed to undergo modifica-tion by N-Acetylglucosamine (GlcNAc). Mass spectrometry identified several of these proteins as known mediators of transcriptional silencing. The most active transposon in the mouse ge-nome is the IAP LTR retrotransposon, which have been previously shown to be repressed by DNA methylation. A Bacteroides O-GlcNAc hydrolase was fused to a catalytically inactive Cas9 and targeted to methylated IAP retrotransposon promoter sequences via IAP-specific guide RNAs; fulminating reactivation of IAP transcription was induced. These data revealed that Glc-NAcylation is directly involved in the transcriptional repression of methylated promoters.
2020-05-29 | GSE93539 | GEO
Project description:Background: Global DNA methylation contributes to genomic integrity by supressing repeat associated transposition events. Several chromatin factors are required in addition to DNA methyltransferases to maintain DNA methylation at intergenic and satellite repeats. Embryos lacking Lsh, a member of the SNF2 superfamily of chromatin helicases, are hypomethylated. The interaction of Lsh with the de novo methyltransferase, Dnmt3b, facilitates the deposition of DNA methylation at stem cell genes. We wished to determine if a similar targeting mechanism operates to maintain DNA methylation at repetitive sequences. Results: We used HELP-seq to map genome wide DNA methylation patterns in Lsh-/- and Dnmt3b-/- somatic cells. DNA methylation is predominantly lost from specific genomic repeats in Lsh-/- cells: LTR-retrotransposons, LINE-1 repeats and mouse satellites. RNA-seq experiments demonstrate that specific IAP (Intracisternal A-type particle) LTRs and satellites, but not LINE-1 elements, are aberrantly transcribed inLsh-/- cells. LTR hypomethylation in Dnmt3b-/- cells is moderate and hypomethylated repetitive elements (IAP, LINE-1 and satellite) are silent. Chromatin immunoprecipitation (ChIP) indicates that repressed LINE-1 elements gain H3K4me3, but H3K9me3 levels are unaltered in Lsh-/- cells, indicating that DNA hypomethylation alone is not permissive for their transcriptional activation. Mis-expressed IAPs and satellites lose H3K9me3 and gain H3K4me3 in Lsh-/- cells. Conclusions: Our study emphasizes that regulation of repetitive elements by DNA methylation is selective and context dependent. We propose a model where Lsh is specifically required at a precise developmental window to target de novo methylation to repeat sequences, which is subsequently maintained by Dnmt1 in somatic cells to enforce repeat silencing thus contributing to genomic integrity. Two pairs of genomic samples compared: WT and Lsh-/- DNA isolations from tail-tip fibroblasts; WT and Dnmt3b knockout DNA isolations from mouse embryonic fibroblasts.
2013-12-09 | E-GEOD-52476 | biostudies-arrayexpress
Project description:Mammalian genomes have evolutionary harbored numerous mobile elements, a part of which are still active and evoke genomic instability. Their movement and positional diversity occasionally result in phenotypic changes and variation by causing altered expression and disruption of neighboring genes in the host genome. Here, we describe a novel microarray-based method by which dispersed genomic locations of a type of retrotransposons in mammalian genome can be identified at a time. By this method, we mapped the DNA elements for a mouse retrotransposon, intracisternal A-particle (IAP), within genomes of C3H/He and C57BL/6J inbred mouse strains; consequently we detected hundreds of probable IAP cDNA-integrating genomic regions. Among 147 putative insertions located nearby the promoter regions, 91 were considered to be present discriminatively in the genome either of C3H/He or C57BL/6J mice, suggesting the existence of considerable strain differences. In addition, by comparing genomic DNAs from a radiation-induced myeloid leukemia and its reference normal tissue, we detected 3 genomic regions around which an IAP element was integrated. These results demonstrate for the first time the successful genome-wide survey of a type of retrotransposon in mammalian genome. Keywords: retrotransposon mapping
2008-05-03 | GSE9572 | GEO
Project description:DNA methylation plays a critical role in development, particularly in repressing retrotransposons. The mammalian methylation landscape is dependent on the combined activities of the canonical maintenance enzyme Dnmt1 and the de novo Dnmts, 3a and 3b. Here we demonstrate that Dnmt1 displays de novo methylation activity in vitro and in vivo with specific retrotransposon targeting. We used whole-genome bisulfite and long-read Nanopore sequencing in genetically engineered methylation depleted embryonic stem cells to provide an in-depth assessment and quantification of this activity. Utilizing additional knockout lines and molecular characterization, we show that Dnmt1's de novo methylation activity depends on Uhrf1 and its genomic recruitment overlaps with targets that enrich for Trim28 and H3K9 trimethylation. Our data demonstrate that Dnmt1 can de novo add and maintain DNA methylation, especially at retrotransposons and that this mechanism may provide additional stability for long-term repression and epigenetic propagation throughout development.
2021-06-29 | PXD025736 | Pride
Project description:Background: Global DNA methylation contributes to genomic integrity by supressing repeat associated transposition events. Several chromatin factors are required in addition to DNA methyltransferases to maintain DNA methylation at intergenic and satellite repeats. Embryos lacking Lsh, a member of the SNF2 superfamily of chromatin helicases, are hypomethylated. The interaction of Lsh with the de novo methyltransferase, Dnmt3b, facilitates the deposition of DNA methylation at stem cell genes. We wished to determine if a similar targeting mechanism operates to maintain DNA methylation at repetitive sequences. Results: We used HELP-seq to map genome wide DNA methylation patterns in Lsh-/- and Dnmt3b-/- somatic cells. DNA methylation is predominantly lost from specific genomic repeats in Lsh-/- cells: LTR-retrotransposons, LINE-1 repeats and mouse satellites. RNA-seq experiments demonstrate that specific IAP (Intracisternal A-type particle) LTRs and satellites, but not LINE-1 elements, are aberrantly transcribed inLsh-/- cells. LTR hypomethylation in Dnmt3b-/- cells is moderate and hypomethylated repetitive elements (IAP, LINE-1 and satellite) are silent. Chromatin immunoprecipitation (ChIP) indicates that repressed LINE-1 elements gain H3K4me3, but H3K9me3 levels are unaltered in Lsh-/- cells, indicating that DNA hypomethylation alone is not permissive for their transcriptional activation. Mis-expressed IAPs and satellites lose H3K9me3 and gain H3K4me3 in Lsh-/- cells. Conclusions: Our study emphasizes that regulation of repetitive elements by DNA methylation is selective and context dependent. We propose a model where Lsh is specifically required at a precise developmental window to target de novo methylation to repeat sequences, which is subsequently maintained by Dnmt1 in somatic cells to enforce repeat silencing thus contributing to genomic integrity. Two pairs of RNA samples compared: WT and Lsh-/- RNA isolations from tail-tip fibroblasts; WT and Lsh-/- RNA isolations from E13.5 mouse embryos.
2013-12-09 | E-GEOD-52477 | biostudies-arrayexpress
Project description:Transcription of endogenous retroviruses (ERVs) is inhibited by de novo DNA methylation during gametogenesis, a process initiated after birth in oocytes and at ~E15.5 in prospermatogonia. Earlier in germline development however, the genome, including most retrotransposons, is progressively demethylated, with young ERVK and ERV1 elements retaining intermediate methylation levels. As DNA methylation reaches a low point in E13.5 primordial germ cells (PGCs) of both sexes, we determined whether retrotransposons are marked by H3K9me3 and H3K27me3 using a recently developed low input ChIP-seq method. Although these repressive histone modifications are predominantly found on distinct genomic regions in E13.5 PGCs, they concurrently mark partially methylated LTRs and LINE1 elements. Germline-specific conditional knock-out (KO) of the H3K9 methyltransferase SETDB1 yields a decrease of both histone marks and DNA methylation at H3K9me3 enriched retrotransposon families. Strikingly, Setdb1-KO E13.5 PGCs show concomitant de-repression of many marked ERVs, including IAP, ETn and ERVK10C elements and ERV-proximal genes, a subset in a sex-dependent manner. Furthermore, Setdb1 deficiency is associated with a reduced number of male PGCs and postnatal hypogonadism in both sexes. Taken together, these observations reveal that SETDB1 is an essential guardian against proviral expression prior to the onset of de novo DNA methylation in the germline. H3K9me3, H3K27me3 and expression profiles in Setdb1 WT, Het and KO male and female E13.5 PGCs.
2014-09-01 | E-GEOD-60377 | biostudies-arrayexpress