A Pair of Transposon-derived Proteins Function in A Histone Acetyltransferase Complex for Active DNA Demethylation
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PROVIDER: PRJNA351785 | ENA |
REPOSITORIES: ENA
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Project description:Transposons are generally kept silent by epigenetic mechanisms including DNA methylation. Here, we identified a pair of Harbinger transposon-derived proteins (HDPs), HDP1 and HDP2, as anti-silencing factors in Arabidopsis. hdp1 and hdp2 mutants displayed an enhanced silencing of transgenes and some transposons. Phylogenetic analyses revealed that HDP1 and HDP2 were co-domesticated from the Harbinger transposon-encoded transposase and DNA-binding protein, respectively. HDP1 interacts with HDP2 in the nucleus, analogous to their transposon counterparts. Moreover, HDP1 and HDP2 are associated with IDM1, IDM2, IDM3 and MBD7 that constitute a histone acetyltransferase complex functioning in DNA demethylation. HDP2 and the methyl-DNA-binding protein MBD7 share a large set of common genomic binding sites, indicating that they jointly determine the target specificity of the histone acetyltransferase complex. Thus, our data revealed that HDP1 and HDP2 constitute a functional module that has been recruited to a histone acetyltransferase complex to prevent DNA hypermethylation and epigenetic silencing.
| S-EPMC5339849 | biostudies-literature
Project description:The Arabidopsis thaliana central cell, the companion cell of the egg, undergoes DNA demethylation prior to fertilization, but the targeting preferences and biological significance of this process remain unclear. Here, we show that active DNA demethylation mediated by the DEMETER DNA glycosylase accounts for all of the demethylation in the central cell, and preferentially targets small, AT-rich and nucleosome-depleted transposable elements. The vegetative cell, the companion cell of sperm, also undergoes DEMETER-dependent demethylation of similar sequences, and lack of DEMETER in vegetative cells causes reduced small RNA-directed DNA methylation of transposons in sperm. Our results demonstrate that demethylation in companion cells reinforces transposon methylation in plant gametes, thereby assuring stable silencing of transposable elements across generations Examination of DNA methylation in Arabidopsis endosperm, embryo, and pollen
2012-09-21 | E-GEOD-38935 | biostudies-arrayexpress
Project description:This SuperSeries is composed of the SubSeries listed below.
2016-12-29 | GSE89320 | GEO
Project description:The Arabidopsis thaliana central cell, the companion cell of the egg, undergoes DNA demethylation prior to fertilization, but the targeting preferences and biological significance of this process remain unclear. Here, we show that active DNA demethylation mediated by the DEMETER DNA glycosylase accounts for all of the demethylation in the central cell, and preferentially targets small, AT-rich and nucleosome-depleted transposable elements. The vegetative cell, the companion cell of sperm, also undergoes DEMETER-dependent demethylation of similar sequences, and lack of DEMETER in vegetative cells causes reduced small RNA-directed DNA methylation of transposons in sperm. Our results demonstrate that demethylation in companion cells reinforces transposon methylation in plant gametes, thereby assuring stable silencing of transposable elements across generations
2012-09-21 | GSE38935 | GEO
Project description:Active DNA demethylation is an important part of epigenetic regulation in plants and animals. How active DNA demethylation is regulated and its relationship with histone modification patterns are unclear. Here, we report the discovery of IDM1, a regulator of DNA demethylation in Arabidopsis. IDM1 is required for preventing DNA hypermethylation of highly homologous multicopy genes and other repetitive sequences that are normally targeted for active DNA demethylation by Repressor of Silencing 1 and related 5-methylcytosine DNA glycosylases. IDM1 binds methylated DNA at chromatin sites lacking histone H3K4 di- or trimethylation and acetylates H3 to create a chromatin environment permissible for 5-methylcytosine DNA glycosylases to function. Our study reveals how some genes are indicated by multiple epigenetic marks for active DNA demethylation and protection from silencing.
| S-EPMC3575687 | biostudies-literature
Project description:The vertebrate body plan and organs are shaped during a highly conserved embryonic phase called the phylotypic stage, however the mechanisms that guide the epigenome through this transition and their evolutionary conservation remain elusive. Here we report widespread DNA demethylation of thousands of enhancers during the phylotypic period in zebrafish, Xenopus and mouse. These dynamic enhancers are linked to essential developmental genes that display coordinated transcriptional and epigenomic changes in the diverse vertebrates during embryogenesis. Phylotypic stage-specific binding of Tet proteins to (hydroxy)methylated DNA, and enrichment of hydroxymethylcytosine on these enhancers, implicated active DNA demethylation in this process. Furthermore, loss of function of Tet1/2/3 in zebrafish caused reduced chromatin accessibility and increased methylation levels specifically on these enhancers, indicative of DNA methylation being an upstream regulator of phylotypic enhancer function. Overall, our study reveals a novel regulatory module associated with the most conserved phase of vertebrate embryogenesis and uncovers an ancient developmental role for the Tet dioxygenases.
2016-01-27 | PXD001164 | Pride
Project description:The PIWI-interacting RNA (piRNA) pathway is an important mechanism to suppress transposon activation in the germline that is highly conserved between Drosophila and mammals. This pathway starts from transcribing piRNA clusters to generate long piRNA precursors. The majority of piRNA clusters lacks a conventional promoter, and therefore their transcription is considered to utilize a noncanonical mechanism. However, information regarding transcriptional regulation of piRNA clusters is limited. Here, we report that the fly KAT6 acetyltransferase, Enok, is important for transposon silencing in the germline. Further small RNA-seq analysis revealed that Enok is critical for piRNA production from a specific subset of piRNA clusters including 42AB, one of the two major sources of piRNAs. Enok is the major enzyme for establishing the H3K23ac mark, and was shown to promote gene expression by acetylating H3K23. Surprisingly, our RNA-seq and ChIP-seq/ChIP-qPCR results suggest that Enok regulates expression of genes involved in the piRNA production by H3K23ac-dependent mechanisms, and also promotes transcription at piRNA clusters through H3K23ac-independent pathways. Our co-immunoprecipitation assay further suggests that Enok interacts with RNA polymerase II to facilitate transcription of piRNA clusters. Taken together, our study provides novel insights into the regulation of noncanonical transcription at piRNA clusters and transposon silencing.
2021-01-07 | GSE105099 | GEO
Project description:The DNA methylation program is at the bottom layer of the epigenetic regulatory cascade of vertebrate development. While the methylation at C-5 position of the cytosine (C) residues on the vertebrate genomes is achieved through the catalytic activities of the DNA methyltransferases (DNMTs), the conversion of the methylated cytosine (5mC) could be accomplished by the combined actions of the TET enzyme and DNA repair. Interestingly, it has been found recently that the mouse and human DNMTs also possess active DNA demethylation activity in vitro in a Ca2+- and redox condition-dependent manner. We report here the study of tracking down the fate of the methyl group removed from 5mC on DNA during in vitro demethylation reaction by mouse de novo DNMTs, i.e. DNMT3A and DNMT3B. Remarkably, the methyl group becomes covalently linked to the catalytic cysteines utilized by the two de novo DNMTs in their DNA methylation reactions. Thus, the forward and reverse reactions of DNA methylations by the DNMTs may utilize the same cysteine residue(s) as the active site despite of their distinctive pathways. Secondly, we demonstrate that active DNA demethylation of a heavily methylated GFP reporter plasmid by ectopically expressed DNMT3A or DNMT3B occurs in vivo in transfected human HEK 293 cells in culture. Furthermore, the extent of DNA demethylation by the DNMTs in this cell-based system is affected by Ca2+ homeostasis as well as by mutation of their putative active cysteines. These findings substantiate the roles of the vertebrate DNMTs as double-edged swords in DNA methylation-demethylation in vitro as well as in a cellular context.
2022-02-24 | PXD003401 | Pride
Project description:The PIWI-interacting RNA (piRNA) pathway is an important mechanism to suppress transposon activation in the germline that is highly conserved between Drosophila and mammals. This pathway starts from transcribing piRNA clusters to generate long piRNA precursors. The majority of piRNA clusters lacks a conventional promoter, and therefore their transcription is considered to utilize a noncanonical mechanism. However, information regarding transcriptional regulation of piRNA clusters is limited. Here, we report that the fly KAT6 acetyltransferase, Enok, is important for transposon silencing in the germline. Further small RNA-seq analysis revealed that Enok is critical for piRNA production from a specific subset of piRNA clusters including 42AB, one of the two major sources of piRNAs. Enok is the major enzyme for establishing the H3K23ac mark, and was shown to promote gene expression by acetylating H3K23. Surprisingly, our RNA-seq and ChIP-seq/ChIP-qPCR results suggest that Enok regulates expression of genes involved in the piRNA production by H3K23ac-dependent mechanisms, and also promotes transcription at piRNA clusters through H3K23ac-independent pathways. Our co-immunoprecipitation assay further suggests that Enok interacts with RNA polymerase II to facilitate transcription of piRNA clusters. Taken together, our study provides novel insights into the regulation of noncanonical transcription at piRNA clusters and transposon silencing.
2021-01-07 | GSE133847 | GEO
Project description:The PIWI-interacting RNA (piRNA) pathway is an important mechanism to suppress transposon activation in the germline that is highly conserved between Drosophila and mammals. This pathway starts from transcribing piRNA clusters to generate long piRNA precursors. The majority of piRNA clusters lacks a conventional promoter, and therefore their transcription is considered to utilize a noncanonical mechanism. However, information regarding transcriptional regulation of piRNA clusters is limited. Here, we report that the fly KAT6 acetyltransferase, Enok, is important for transposon silencing in the germline. Further small RNA-seq analysis revealed that Enok is critical for piRNA production from a specific subset of piRNA clusters including 42AB, one of the two major sources of piRNAs. Enok is the major enzyme for establishing the H3K23ac mark, and was shown to promote gene expression by acetylating H3K23. Surprisingly, our RNA-seq and ChIP-seq/ChIP-qPCR results suggest that Enok regulates expression of genes involved in the piRNA production by H3K23ac-dependent mechanisms, and also promotes transcription at piRNA clusters through H3K23ac-independent pathways. Our co-immunoprecipitation assay further suggests that Enok interacts with RNA polymerase II to facilitate transcription of piRNA clusters. Taken together, our study provides novel insights into the regulation of noncanonical transcription at piRNA clusters and transposon silencing.
2021-01-07 | GSE105025 | GEO