Arabidopsis thaliana
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA186008 | ENA |
REPOSITORIES: ENA
Similar Datasets
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:In plants, maintenance-methylation mediated by METHYLTRANSFERASE-1 (MET1), siRNA-directed de-novo methylation, and chromatin remodeling by DECREASE IN DNA METHYLATION -1 (DDM1) promote transcriptional gene-silencing of transposable elements (TEs). This process is mostly investigated at steady states reflecting how long-established silent conditions are maintained, faithfully re-iterated or temporarily modified during growth, stress and over generations. How invasive TEs are detected and silenced de novo, however, remains largely unknown. Using inbred lineages of hybrid Arabidopsis epigenomes combining wild-type and met1 or ddm1 chromosomes, we have deciphered the timing, spatial distribution and mechanisms underpinning the proliferation and eventual demise of the endogenous retrotransposon évadé (EVD). Both developmental and molecular features of EVD biology, including a remarkable ability to evade RNA interference, ultimately contribute to its silencing over multiple generations. The underlying processes are accompanied by widespread diversification of the Arabidopsis genome and de-novo epiallelism creating an extensive reservoir of selectable and potentially adaptive traits. Differential expression of EVADE small RNAs between three generations of one specific Col0 met1 derived EpiRIL.
2013-07-02 | E-GEOD-43412 | biostudies-arrayexpress
Project description:In plants, maintenance-methylation mediated by METHYLTRANSFERASE-1 (MET1), siRNA-directed de-novo methylation, and chromatin remodeling by DECREASE IN DNA METHYLATION -1 (DDM1) promote transcriptional gene-silencing of transposable elements (TEs). This process is mostly investigated at steady states reflecting how long-established silent conditions are maintained, faithfully re-iterated or temporarily modified during growth, stress and over generations. How invasive TEs are detected and silenced de novo, however, remains largely unknown. Using inbred lineages of hybrid Arabidopsis epigenomes combining wild-type and met1 or ddm1 chromosomes, we have deciphered the timing, spatial distribution and mechanisms underpinning the proliferation and eventual demise of the endogenous retrotransposon évadé (EVD). Both developmental and molecular features of EVD biology, including a remarkable ability to evade RNA interference, ultimately contribute to its silencing over multiple generations. The underlying processes are accompanied by widespread diversification of the Arabidopsis genome and de-novo epiallelism creating an extensive reservoir of selectable and potentially adaptive traits.
2013-07-02 | GSE43412 | GEO
Project description:Transposable elements are entangled in a constant evolutionary arms race with their host genomes, constantly evolving ways to evade host silencing mechanisms. One silencing mechanism used by many distantly related eukaryotes is dependent on cytosine methylation, an epigenetic mark deposited by C5 cytosine methyltransferases (CMTs). Therefore, it is expected transposable elements would acquire mechanisms to escape from being targeted by cytosine methylation. Here we report how two distantly related eukaryotic lineages have incorporated CMTs into the coding regions of distinct retrotransposon classes. Three of these events have occurred in the dinoflagellates of the genus Symbiodinium, where these CMT-encoding retrotransposons show hundreds of insertions. In a case of convergent evolution, the charophyte Klebsormidium nitens shows an independent expansion of CMT encoding retrotransposons. Concomitantly, we find that Symbiodinium genomes show cytosine methylation patterns unlike any other eukaryote with most of the genome hypermethylated in CpGs, while targeted CH methylation accumulates on transposable elements. Similarly, K. nitens shows CHH and CHG targeted methylation on repressed transposable elements, while CpG methylation is concentrated in gene bodies and transposable elements. Furthermore, we demonstrate the ability of retrotransposon CMTs to de novo methylate CpGs, indicating a putative role in mimicking retrotranscribed DNA as host active genomic DNA. Our results show an unprecedented example of how retrotransposons incorporate host-derived genes involved in DNA methylation as a source of adaptation to their host epigenomic environments.
2018-04-11 | GSE104474 | 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:DNA methylation plays a critical role in development, particularly in silencing transposable elements. Conserved across mammals, the 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 clear de novo activity in vitro and in vivo and is specifically directed to IAP retrotransposons. We provide an indepth characterization using whole genome bisulfite sequencing and long-read Nanopore sequencing in genetically engineered methylation depleted embryonic stem cells. Further using additional knockout and MassSpec experiments we show that Dnmt1’s de novo methylation activity is dependent on Uhrf1 and its genomic targeting linked to Trim28 and H3K9 trimethylation. Our data suggest that Dnmt1 is essential for adding and maintaining DNA methylation especially at IAPs and that this mechanism may be of physiological relevance for retrotransposon repression during certain phases of development.
2021-06-18 | GSE158460 | GEO
Project description:Histone modifications associated with gene silencing typically mark large contiguous regions of the genome forming repressive chromatin domain structures. Since the repressive domains exist in close proximity to active regions, maintenance of domain structure is critically important. This study shows that nickel, a nonmutagenic carcinogen, can disrupt histone H3 lysine 9 dimethylation (H3K9me2) domain structures genome-wide, resulting in spreading of H3K9me2 marks into the active regions, which is associated with gene silencing. Our results suggest inhibition of DNA binding of the insulator protein CCCTC-binding factor (CTCF) at the H3K9me2 domain boundaries as a potential reason for H3K9me2 domain disruption. These findings have major implications in understanding chromatin dynamics and the consequences of chromatin domain disruption during pathogenesis. Investigations into the genomic landscape of histone modifications in heterochromatic regions have revealed histone H3 lysine 9 dimethylation (H3K9me2) to be important for differentiation and maintaining cell identity. H3K9me2 is associated with gene silencing and is organized into large repressive domains that exist in close proximity to active genes, indicating the importance of maintenance of proper domain structure. Here we show that nickel, a nonmutagenic environmental carcinogen, disrupted H3K9me2 domains, resulting in the spreading of H3K9me2 into active regions, which was associated with gene silencing. We found weak CCCTC-binding factor (CTCF)-binding sites and reduced CTCF binding at the Ni-disrupted H3K9me2 domain boundaries, suggesting a loss of CTCF-mediated insulation function as a potential reason for domain disruption and spreading. We furthermore show that euchromatin islands, local regions of active chromatin within large H3K9me2 domains, can protect genes from H3K9me2-spreadingM-bM-^@M-^Sassociated gene silencing. These results have major implications in understanding H3K9me2 dynamics and the consequences of chromatin domain disruption during pathogenesis.
2014-09-24 | E-GEOD-56053 | biostudies-arrayexpress
Project description:CpG islands (CGIs) including those at imprinting control regions (ICRs) are protected from de novo methylation in somatic cells. However, many cancers often exhibit CGI hypermethylation, implying that the machinery is impaired in cancer cells. Here, we conducted a comprehensive analysis of CGI methylation during the somatic cell reprogramming. Although most CGIs remain hypomethylated, a small subset of CGIs, particularly at several ICRs, were often de novo methylated in reprogrammed pluripotent stem cells (PSCs). Such de novo ICR methylation was linked with the silencing of reprogramming factors, which occurs at a late stage of reprogramming. The ICR-preferred CGI hypermethylation was similarly observed in human PSCs. Mechanistically, ablation of Dnmt3a prevented PSCs from de novo ICR methylation. Notably, the ICR-preferred CGI hypermethylation was observed in pediatric cancers, while adult cancers exhibit genome-wide CGI hypermethylation. These results may have important implications in the pathogenesis of pediatric cancers and the application of PSCs.
2019-06-18 | GSE111173 | GEO
Project description:In mammals, the acquisition of the germline from the soma provides the germline with an essential challenge, the necessity to erase and reset genomic methylation. De novo genome methylation re-encodes the epigenome including transposable element (TE) silencing. In the male germline RNA-directed DNA methylation silences young active TEs. The PIWI protein MIWI2 (PIWIL4) and its associated PIWI-interacting RNA (piRNAs) act to tether MIWI2 to nascent TE transcripts and instruct DNA methylation of the active TE. The mechanism by which MIWI2 directs de novo TE methylation is poorly understood but central to the immortality of the germline. Here, we define the interactome of MIWI2 in fetal gonocytes that are undergoing de novo genome methylation and identify a novel MIWI2-associated factor SPOCD1 that is essential for TE silencing. The loss of Spocd1 in mice phenocopies that of Miwi2-deficient mice and does not impact on piRNA biogenesis nor localization of MIWI2 to the nucleus. SPOCD1 is a nuclear protein and its expression is restricted to the period of de novo genome methylation. We found SPOCD1 co-purified in vivo with constituents of several repressive chromatin remodelling complexes (NURD and BAF) as well as DNMT3L and DNMT3A, components of the de novo methylation machinery. We propose a model whereby tethering of MIWI2 to a nascent TE transcript recruits repressive chromatin remodelling activities and the de novo methylation apparatus through its association with SPOCD1. In summary, we have identified a novel and essential executor of mammalian piRNA-directed DNA methylation.
2020-06-17 | GSE131377 | GEO
Project description:The PIWI protein MIWI2 and its associated PIWI-interacting RNAs (piRNAs) instruct DNA methylation of young active transposable elements (TEs) in the male germline. Here we show that MIWI2 associates with TEX15 in foetal gonocytes. TEX15 is predominantly a nuclear protein that is not required for piRNA biogenesis but is essential for piRNA-directed TE de novo methylation and silencing. In summary, TEX15 is an essential executor of mammalian piRNA-directed DNA methylation.
2020-06-18 | PXD019087 | Pride