Drosophila melanogaster
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA178167 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR605747.fastq.gz | Fastqsanger.gz | |||
| SRR605748.fastq.gz | Fastqsanger.gz | |||
| SRR605749.fastq.gz | Fastqsanger.gz | |||
| SRR605750.fastq.gz | Fastqsanger.gz | |||
| SRR605751.fastq.gz | Fastqsanger.gz |
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Project description:Transgenes containing a fragment of I transposon represent a powerful model of piRNA cluster de novo formation in the Drosophila germline. We revealed that the same transgenes located at different genomic loci form piRNA clusters with various capacity of small RNA production. Transgenic piRNA clusters are not established in piRNA pathway mutants. However, in wild-type context, the endogenous ancestral I-related piRNAs are sufficient to heterochromatinize and convert the I-containing transgenes into piRNA-producing loci. Here, we address how the quantitative level of piRNAs influences the heterochromatinization and piRNA production. We show that neither the piRNAs mediated by active I-element copies nor inheritance of abundant maternal I-derived piRNAs enable to stimulate additional changes of transgenes chromatin state or piRNA production from them. Therefore, chromatin changes and piRNA production are initiated by a minimum threshold level of complementary piRNAs suggesting a selective advantage of prompt cell response to the lowest level of piRNAs. Noteworthy, the weak piRNA clusters do not transform into strong ones after being targeted by a larger amount of I-specific piRNAs, indicating the importance of the genomic context for piRNA cluster establishment. Analysis of ovarian transcription profiles suggests that regions facilitating convergent transcription favor formation of transgenic piRNA clusters .
2020-04-10 | GSE138886 | GEO
Project description:PIWI interacting RNAs (piRNAs) provide defense against transposable element (TE) expansion in the germline of metazoans. piRNAs are processed from the transcripts encoded by specialized heterochromatic clusters enriched in damaged copies of transposons. How these regions are recognized as a source of piRNAs is still elusive. The aim of this study is to determine how transgenes that contain a fragment of the LINE-like I transposon lead to an acquired TE resistance in Drosophila. We show that such transgenes, being inserted in unique euchromatic regions which normally do not produce small RNAs, become de novo bidirectional piRNA clusters that silence I-element activity in the germline. Strikingly, small RNAs of both polarities are generated from the entire transgene and flanking genomic sequences — not only from the transposon fragment. Chromatin immunoprecipitation analysis shows that in ovaries the trimethylated histone 3 lysine 9 (H3K9me3) mark associates with transgenes producing piRNAs. We show that transgene-derived hsp70 piRNAs stimulate in trans cleavage of cognate endogenous transcripts with subsequent processing of the non-homologous parts of these transcripts into piRNAs.
2013-04-25 | GSE41780 | GEO
Project description:PIWI interacting RNAs (piRNAs) provide defense against transposable element (TE) expansion in the germline of metazoans. piRNAs are processed from the transcripts encoded by specialized heterochromatic clusters enriched in damaged copies of transposons. How these regions are recognized as a source of piRNAs is still elusive. The aim of this study is to determine how transgenes that contain a fragment of the LINE-like I transposon lead to an acquired TE resistance in Drosophila. We show that such transgenes, being inserted in unique euchromatic regions which normally do not produce small RNAs, become de novo bidirectional piRNA clusters that silence I-element activity in the germline. Strikingly, small RNAs of both polarities are generated from the entire transgene and flanking genomic sequences — not only from the transposon fragment. Chromatin immunoprecipitation analysis shows that in ovaries the trimethylated histone 3 lysine 9 (H3K9me3) mark associates with transgenes producing piRNAs. We show that transgene-derived hsp70 piRNAs stimulate in trans cleavage of cognate endogenous transcripts with subsequent processing of the non-homologous parts of these transcripts into piRNAs. The fractions of small RNAs (19-29 nt) from ovaries of wild type and 11 transgenic lines of Drosophila melanogaster were sequenced using Illumina HiSeq 2000.
2013-04-25 | E-GEOD-41780 | biostudies-arrayexpress
Project description:Expression of transposable elements in the germline is controlled by Piwi-interacting (pi) RNAs produced by genomic loci termed piRNA clusters and associated with Rhino, a Heterochromatin Protein 1 (HP1) homolog. Previously, we have shown that transgenes containing a fragment of the I retrotransposon form de novo piRNA clusters in the Drosophila germline providing suppression of I-element activity. We noted that identical transgenes located in different genomic sites vary considerably in piRNA production and classified them as “strong” and “weak” piRNA clusters. Here, we investigated what chromatin and transcriptional changes occur at the transgene insertion sites after their conversion into piRNA clusters. We found that the formation of a transgenic piRNA cluster is accompanied by activation of transcription from both genomic strands that likely initiates at multiple random sites. The chromatin of all transgene-associated piRNA clusters contain high levels of trimethylated lysine 9 of histone H3 (H3K9me3) and HP1a, whereas Rhino binding is considerably higher at the strong clusters. None of these chromatin marks was revealed at the “empty” sites before transgene insertion. Finally, we have shown that in the nucleus of polyploid nurse cells, the formation of a piRNA cluster at a given transgenic genomic copy works according to an “all– or– nothing” model: either there is high Rhino enrichment or there is no association with Rhino at all. As a result, genomic copies of a weak piRNA transgenic cluster show a mosaic association with Rhino foci, while the majority of strong transgene copies associate with Rhino and are hence involved in piRNA production.
2018-01-24 | GSE88774 | GEO
Project description:The piRNA pathway is a conserved small RNA-based immune system that protects animal germ cell genomes from the harmful effects of transposon mobilisation. In Drosophila ovaries, most piRNAs originate from dual-strand clusters, which generate piRNAs from both genomic strands. Dual-strand clusters use non-canonical transcription mechanisms. Although transcribed by RNA polymerase II, cluster transcripts lack splicing signatures and polyA tails. mRNA processing is important for general mRNA export mediated by Nuclear export factor 1. Although UAP56, a component of the transcription and export complex, has been implicated in piRNA precursor export, it remains unknown how dual-strand cluster transcripts are specifically targeted for piRNA biogenesis by export from the nucleus to cytoplasmic processing centers. Here we report that dual-strand cluster transcript export requires CG13741/Bootlegger and the Drosophila Nuclear export factor family protein, Nxf3. Bootlegger is specifically recruited to piRNA clusters and in turn brings Nxf3. We find that Nxf3 specifically binds to piRNA precursors and is essential for their export to piRNA biogenesis sites, a process that is critical for germline transposon silencing. Our data shed light on how dual-strand clusters bypass canonical mRNA features to be specifically exported via Nxf3, ensuring proper piRNA production
2019-07-29 | PXD014472 | Pride
Project description:Piwi-interacting RNAs (piRNAs) control transposable element (TE) activity in the germline. piRNAs are produced from single-stranded precursors transcribed from distinct genomic loci, enriched by TE fragments and termed piRNA clusters. The specific chromatin organization and transcriptional regulation of Drosophila germline-specific piRNA clusters ensure transcription and processing of piRNA precursors. TEs harbour various regulatory elements that could affect piRNA cluster integrity. One of such elements is the suppressor-of-hairy-wing (Su(Hw))-mediated insulator, which is harboured in the retrotransposon gypsy. To understand how insulators contribute to piRNA cluster activity, we studied the effects of transgenes containing gypsy insulators on local organization of endogenous piRNA clusters. We show that transgene insertions interfere with piRNA precursor transcription, small RNA production and the formation of piRNA cluster-specific chromatin, a hallmark of which is Rhino, the germline homolog of the heterochromatin protein 1 (HP1). The mutations of Su(Hw) restored the integrity of piRNA clusters in transgenic strains. Surprisingly, Su(Hw) depletion enhanced the production of piRNAs by the domesticated telomeric retrotransposon TART, indicating that Su(Hw)-dependent elements protect TART transcripts from piRNA processing machinery in telomeres. A genome-wide analysis revealed that Su(Hw)-binding sites are depleted in endogenous germline piRNA clusters, suggesting that their functional integrity is under strict evolutionary constraints.
2019-03-15 | GSE125173 | GEO
Project description:The mouse PIWI-interacting RNA (piRNA) pathway provides anti-transposon immunity to the developing male germline by directing transposon DNA methylation. The first step in this process is the recruitment of SPOCD1 to young LINE1 loci 1 followed in the second step by piRNA-mediated tethering of the PIWI protein MIWI2 (PIWIL4) to the nascent transposon transcript. To protect the germline, the piRNA pathway needs to methylate all active transposon copies but how this is achieved remains unknown. Here, we show that nuclear piRNA and de novo methylation factors are all euchromatic. We find that SPOCD1 directly interacts with the nuclear pore component TPR, which forms heterochromatin exclusion zones adjacent to nuclear pores. In foetal gonocytes undergoing piRNA-directed DNA methylation, TPR is found both at the nuclear periphery but also abundantly throughout the nucleoplasm. We found that the SPOCD1-TPR interaction is required for complete non-stochastic piRNA-directed LINE1 methylation. The loss of the SPOCD1-TPR interaction results in a fraction of SPOCD1 and other chromatin-bound piRNA factors to relocalise to constitutive heterochromatin where they are no longer accessible to MIWI2 and the de novo methylation machinery. We propose that TPR-mediated heterochromatin exclusion provides a nowhere-to-hide mechanism for SPOCD1-bound LINE1 loci throughout the nucleoplasm. In summary, the piRNA pathway has co-opted TPR to guarantee LINE1s are euchromatic and accessible to the piRNA and de novo methylation machineries.
2025-11-11 | PXD060851 | Pride
Project description:The mouse PIWI-interacting RNA (piRNA) pathway provides anti-transposon immunity to the developing male germline by directing transposon DNA methylation. The first step in this process is the recruitment of SPOCD1 to young LINE1 loci 1 followed in the second step by piRNA-mediated tethering of the PIWI protein MIWI2 (PIWIL4) to the nascent transposon transcript. To protect the germline, the piRNA pathway needs to methylate all active transposon copies but how this is achieved remains unknown. Here, we show that nuclear piRNA and de novo methylation factors are all euchromatic. We find that SPOCD1 directly interacts with the nuclear pore component TPR, which forms heterochromatin exclusion zones adjacent to nuclear pores. In foetal gonocytes undergoing piRNA-directed DNA methylation, TPR is found both at the nuclear periphery but also abundantly throughout the nucleoplasm. We found that the SPOCD1-TPR interaction is required for complete non-stochastic piRNA-directed LINE1 methylation. The loss of the SPOCD1-TPR interaction results in a fraction of SPOCD1 and other chromatin-bound piRNA factors to relocalise to constitutive heterochromatin where they are no longer accessible to MIWI2 and the de novo methylation machinery. We propose that TPR-mediated heterochromatin exclusion provides a nowhere-to-hide mechanism for SPOCD1-bound LINE1 loci throughout the nucleoplasm. In summary, the piRNA pathway has co-opted TPR to guarantee LINE1s are euchromatic and accessible to the piRNA and de novo methylation machineries.
2025-11-11 | PXD060850 | Pride
Project description:In the male mouse germline, PIWI-interacting RNAs (piRNAs), bound by the PIWI protein MIWI2 (PIWIL4), guide DNA methylation of young active transposons through SPOCD1. However, the underlying mechanisms of SPOCD1-mediated piRNA-directed transposon methylation and whether this pathway functions to protect the human germline remains unknown. We identified loss-of-function variants in human SPOCD1 that cause defective transposon silencing and male infertility. Through the analysis of one of these pathogenic alleles, we discovered that the uncharacterised protein C19ORF84 interacts with SPOCD1. DNMT3C, the DNA methyltransferase responsible for transposon methylation, associates with SPOCD1 and C19ORF84 in foetal gonocytes. Furthermore, C19ORF84 is essential for piRNA-directed DNA methylation and male mouse fertility. Finally, C19ORF84 mediates the in vivo association of SPOCD1 with the de novo methylation machinery. In summary, we have discovered a conserved role for the human piRNA pathway in transposon silencing and C19ORF84, an uncharacterised protein essential for orchestrating piRNA-directed DNA methylation.
2024-02-14 | PXD047331 | Pride
Project description:Accurate genome assemblies are critical for understanding small RNA-mediated genome defense. In animals, the PIWI-interacting RNA (piRNA) pathway protects genome integrity by silencing transposable elements. Studying how piRNAs are generated and how they guide heterochromatin formation requires complete reconstruction of genomic piRNA source loci and detailed transposon maps. Here, we present a high-quality de novo genome assembly of Drosophila melanogaster ovarian somatic cells (OSCs), a widely used cell line that recapitulates nuclear piRNA biology. The OSC genome differs substantially from the reference genome, with major differences in transposon content and piRNA cluster composition. Our assembly resolves the 700 kb flamenco locus, the primary piRNA cluster in OSCs, and provides a genome-wide transposon map. Using this resource, we characterize piRNA source loci, reveal how piRNA cluster composition determines transposon-derived piRNA profiles, and clarify the widespread impact of the nuclear piRNA pathway on heterochromatin. Finally, we provide an open platform for integrating user-generated datasets with the OSC genome, creating a community resource for studying transposon control and piRNA biology.
2025-11-17 | GSE310174 | GEO