Genomic properties of variably-methylated retrotransposons in mouse
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PROVIDER: PRJNA667712 | ENA |
REPOSITORIES: ENA
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Project description:Transposable elements (TEs) are enriched in cytosine methylation, preventing their mobility within the genome. Two examples of TEs that escape this regulation are the murine-specific intracisternal A particle (IAP) elements Avy and AxinFu, which exhibit inter-individual variability in methylation associated with phenotypic variation. To determine the frequency of this phenomenon, its underlying mechanisms, and its effects on gene expression, we previously conducted a screen identifying variably methylated IAPs (VM-IAPs). Here, we fully validate these elements, categorising VM-IAPs for the first time into those exhibiting tissue specificity (tsVM-IAPs) and those showing uniform methylation among tissues (constitutive- or cVM-IAPs) with both types having the potential to regulate the genome in cis. Using our validated set of VM-IAPs, we explore how variable methylation is established and identify sequences enriched within cVM-IAPs, implicating genetics as a determinant of variability. CTCF, a methylation-sensitive transcription factor known for its role in facilitating chromatin interactions, is enriched at VM-IAPs and we show that CTCF binding is inversely correlated with methylation at cVM-IAPs. We uncover dynamic physical interactions between lowly-methylated cVM-IAPs and other genomic loci, suggesting that VM-IAPs have the potential for long-range genomic regulation. Lastly, screening for variably methylated regions in other TEs shows that this phenomenon is largely limited to IAPs, which are amongst the youngest and most active endogenous retroviruses. We propose that a recently evolved interplay between genetic sequence, CTCF binding, and DNA methylation at young TEs has the potential to cause inter-individual variability in transcriptional outcomes with implications for phenotypic variation.
2021-03-02 | GSE159110 | GEO
Project description:BackgroundTransposable elements (TEs) are enriched in cytosine methylation, preventing their mobility within the genome. We previously identified a genome-wide repertoire of candidate intracisternal A particle (IAP) TEs in mice that exhibit inter-individual variability in this methylation (VM-IAPs) with implications for genome function.ResultsHere we validate these metastable epialleles and discover a novel class that exhibit tissue specificity (tsVM-IAPs) in addition to those with uniform methylation in all tissues (constitutive- or cVM-IAPs); both types have the potential to regulate genes in cis. Screening for variable methylation at other TEs shows that this phenomenon is largely limited to IAPs, which are amongst the youngest and most active endogenous retroviruses. We identify sequences enriched within cVM-IAPs, but determine that these are not sufficient to confer epigenetic variability. CTCF is enriched at VM-IAPs with binding inversely correlated with DNA methylation. We uncover dynamic physical interactions between cVM-IAPs with low methylation ranges and other genomic loci, suggesting that VM-IAPs have the potential for long-range regulation.ConclusionOur findings indicate that a recently evolved interplay between genetic sequence, CTCF binding, and DNA methylation at young TEs can result in inter-individual variability in transcriptional outcomes with implications for phenotypic variation.
| S-EPMC7898769 | biostudies-literature
Project description:Human induced pluripotent stem cells (hiPSCs) show variable differentiation potential due to their epigenomic heterogeneity, whose extent/attributes remain unclear, except for well-studied elements/chromosomes such as imprints and the X chromosomes. Here, we show that seven hiPSC lines with variable germline potential exhibit substantial epigenomic heterogeneity, despite their uniform transcriptomes. Nearly a quarter of autosomal regions bear potentially differential chromatin modifications, with promoters/CpG islands for H3K27me3/H2AK119ub1 and evolutionarily young retrotransposons for H3K4me3. We identify 145 large autosomal blocks (≥100 kb) with differential H3K9me3 enrichment, many of which are lamina-associated domains (LADs) in somatic, but not in embryonic stem cells. A majority of these epigenomic heterogeneities are independent of genetic variations. We identify an X-chromosome state with chromosome-wide H3K9me3 that stably prevents X-chromosome erosion. Importantly, the germline potential of female hiPSCs correlates with X-chromosome inactivation. We propose that inherent genomic properties, including CpG density, transposons, and LADs, engender epigenomic heterogeneity in hiPSCs.
2021-11-03 | GSE166138 | GEO
Project description:Human induced pluripotent stem cells (hiPSCs) show variable differentiation potential due to their epigenomic heterogeneity, whose extent/attributes remain unclear, except for well-studied elements/chromosomes such as imprints and the X chromosomes. Here, we show that seven hiPSC lines with variable germline potential exhibit substantial epigenomic heterogeneity, despite their uniform transcriptomes. Nearly a quarter of autosomal regions bear potentially differential chromatin modifications, with promoters/CpG islands for H3K27me3/H2AK119ub1 and evolutionarily young retrotransposons for H3K4me3. We identify 145 large autosomal blocks (≥100 kb) with differential H3K9me3 enrichment, many of which are lamina-associated domains (LADs) in somatic, but not in embryonic stem cells. A majority of these epigenomic heterogeneities are independent of genetic variations. We identify an X-chromosome state with chromosome-wide H3K9me3 that stably prevents X-chromosome erosion. Importantly, the germline potential of female hiPSCs correlates with X-chromosome inactivation. We propose that inherent genomic properties, including CpG density, transposons, and LADs, engender epigenomic heterogeneity in hiPSCs.
2021-11-03 | GSE165868 | GEO
Project description:Human induced pluripotent stem cells (hiPSCs) show variable differentiation potential due to their epigenomic heterogeneity, whose extent/attributes remain unclear, except for well-studied elements/chromosomes such as imprints and the X chromosomes. Here, we show that seven hiPSC lines with variable germline potential exhibit substantial epigenomic heterogeneity, despite their uniform transcriptomes. Nearly a quarter of autosomal regions bear potentially differential chromatin modifications, with promoters/CpG islands for H3K27me3/H2AK119ub1 and evolutionarily young retrotransposons for H3K4me3. We identify 145 large autosomal blocks (≥100 kb) with differential H3K9me3 enrichment, many of which are lamina-associated domains (LADs) in somatic, but not in embryonic stem cells. A majority of these epigenomic heterogeneities are independent of genetic variations. We identify an X-chromosome state with chromosome-wide H3K9me3 that stably prevents X-chromosome erosion. Importantly, the germline potential of female hiPSCs correlates with X-chromosome inactivation. We propose that inherent genomic properties, including CpG density, transposons, and LADs, engender epigenomic heterogeneity in hiPSCs.
2021-11-03 | GSE165867 | GEO
Project description:Partially methylated domains are extended regions in the genome exhibiting a reduced average DNA methylation level. They cover gene poor and transcriptionally inactive regions and tend to be heterochromatic. We present a comprehensive comparative analysis of partially methylated domains in human and mouse cells, to identify structural and functional features associated with them.
| EGAS00001003157 | EGA
Project description:Temporal Lobe Epilepsy and Retrotransposons
| PRJNA647483 | ENA
Project description:Temporal Lobe Epilepsy and Retrotransposons
| PRJNA647484 | ENA
Project description:Mammalian genomes harbor millions of retrotransposon copies, some of which are transpositionally active. In mouse prospermatogonia, PIWI-interacting small RNAs called piRNAs combat retrotransposon activity. The piRNA system guides de novo DNA methylation at retrotransposon promoters, but it remains unclear whether DNA methylation is involved in retrotransposon silencing in prospermatogonia. We performed a genome-wide study of DNA methylation and RNA abundance for retrotransposons in developing mouse male germ cells, using Pld6/Mitopld and Dnmt3l knockout (KO) mice deficient in piRNA biogenesis and de novo DNA methylation, respectively. The Dnmt3l mutation greatly reduced DNA methylation at most retrotransposons but its effect on their RNA abundance was low in prospermatogonia. In the Pld6 mutants, only few retrotransposons exhibited reduced DNA methylation but many were more upregulated at the RNA level than in the Dnmt3l mutants. Moreover, the retrotransposon upregulation by the Pld6 mutation was observed even in the Dnmt3l KO background. Thus, in prospermatogonia, post-transcriptional RNA digestion by the piRNA system plays a more important role in retrotransposon regulation than transcriptional silencing by DNA methylation. However, their relative importance was changed in meiotic spermatocytes where hypomethylation of retrotransposons increased their expression by up to 100-fold in both mutants. Interestingly, retrotransposon activation disrupted the transcriptome integrity because intergenic and intronic retrotransposon sequences, in particular, the antisense promoter of LINE-1, drive expression of nearby genes.
2017-07-20 | GSE70891 | GEO
Project description:Retrotransposons encompass half of the human genome and contribute to the formation of heterochromatin, which provides nuclear structure and regulates gene expression. Here, we asked if the human silencing hub (HUSH) complex is necessary to silence retrotransposons and whether it collaborates with TRIM28 and the chromatin remodeler ATRX at specific genomic loci. We show that the HUSH complex contributes to de novo repression and DNA methylation of a SVA retrotransposon reporter. By using naïve vs. primed mouse pluripotent stem cells, we reveal a critical role for the HUSH complex in naïve cells, implicating it in programming epigenetic marks in development. While the HUSH component TASOR binds to endogenous retroviruses (ERVs) and L1s, it is mainly required to repress evolutionarily young L1s. TRIM28, in contrast, is necessary to repress both ERVs and young L1s. Genes co-repressed by TRIM28 and TASOR are evolutionarily young, or exhibit tissue-specific expression, are enriched in young L1s and display evidence for regulation through LTR promoters. Finally, we demonstrate that the HUSH complex is also required to repress L1 elements in human cells. Overall, these data indicate that the HUSH complex and TRIM28 co-repress young retrotransposons and new genes rewired by retrotransposon non-coding DNA.
2018-01-17 | GSE107840 | GEO