Nuclear and Cytoplasmic factors involved in piRNA-mediated Paramutation in Drosophila
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ABSTRACT:
PROVIDER: PRJEB11491 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| ERR1092620.fastq.gz | Fastqsanger.gz | |||
| ERR1092630.fastq.gz | Fastqsanger.gz | |||
| ERR1092640.fastq.gz | Fastqsanger.gz | |||
| ERR1092650.fastq.gz | Fastqsanger.gz | |||
| ERR1090211.fastq.gz | Fastqsanger.gz |
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Project description:In the nematode Caenorhabditis elegans, different small RNA-dependent gene silencing mechanisms act in the germline to initiate transgenerational gene silencing. Piwi-interacting RNAs (piRNAs) can initiate transposon and gene silencing by acting upstream of endogenous short interfering RNAs (siRNAs), which engage a nuclear RNA interference (RNAi) pathway to trigger transcriptional gene silencing. Once gene silencing has been established, it can be stably maintained over multiple generations without the requirement of the initial trigger and is also referred to as RNAe or paramutation. This heritable silencing depends on the integrity of the nuclear RNAi pathway. However, the exact mechanism by which silencing is maintained across generations is not understood.Here we demonstrate that silencing of piRNA targets involves the production of two distinct classes of small RNAs with different genetic requirements. The first class, secondary siRNAs, are localized close to the direct target site for piRNAs. Nuclear import of the secondary siRNAs by the Argonaute HRDE-1 leads to the production of a distinct class of small RNAs that map throughout the transcript, which we term tertiary siRNAs. Both classes of small RNAs are necessary for full repression of the target gene and can be maintained independently of the initial piRNA trigger. Consistently, we observed a form of paramutation associated with tertiary siRNAs. Once paramutated, a tertiary siRNA generating allele confers dominant silencing in the progeny regardless of its own transmission, suggesting germline-transmitted siRNAs are sufficient for multigenerational silencing. C. elegans strains containing transgenes silenced by piRNAs were crossed to strains with transgenes with similar sequences but without piRNA target sites, to investigate the spreading of silencing between transgenes mediated by small RNAs. Mutant backgrounds were used to investigate the genetic requirements for this process.
2015-04-01 | E-GEOD-66344 | biostudies-arrayexpress
Project description:We show that heterologous RNA that lacks complementary piRNAs is processed into piRNAs upon recruitment of several piRNA pathway factors. Our approach utilizes tethering of components of the piRNA pathway to the transcript of a reporter and then small RNA cloning from total RNA from Drosophila ovaries. Our approach allows discrimination of proteins involved in transcription and export of piRNA precursors from components required for the cytoplasmic processing steps. piRNA processing correlates with localization of the substrate RNA to nuage, a distinct membraneless cytoplasmic compartment, which surrounds the nucleus of germ cells, suggesting that sequestration of RNA to this subcellular compartment is both necessary and sufficient for selecting piRNA biogenesis substrates.
2017-09-18 | GSE102961 | GEO
Project description:By using DNA methylation of introgression lines as a marker of past paramutation, we characterise in details the paramutation of the \textit{H06} locus in crosses between Solanum lycopersicum and a range of tomato relatives and cultivars. Paramutation of H06 depends on the timing of sRNA production and conforms to the RNA-directed model of paramutation. By scanning the methylomes of tomato introgression lines for shared regions of differential methylation, thousands of candidate regions for paramutation are identified. Analysing the segregation of the methylation patterns for a subset of these regions shows variations in the penetrance of paramutation-like interactions.
2017-08-18 | GSE97206 | GEO
Project description:By using DNA methylation of introgression lines as a marker of past paramutation, we characterise in details the paramutation of the \textit{H06} locus in crosses between Solanum lycopersicum and a range of tomato relatives and cultivars. Paramutation of H06 depends on the timing of sRNA production and conforms to the RNA-directed model of paramutation. By scanning the methylomes of tomato introgression lines for shared regions of differential methylation, thousands of candidate regions for paramutation are identified. Analysing the segregation of the methylation patterns for a subset of these regions shows variations in the penetrance of paramutation-like interactions.
2017-08-18 | GSE97192 | GEO
Project description:Transposable element activity is repressed in the germline in animals by PIWI-interacting RNAs (piRNAs), a class of small RNAs produced by genomic loci mostly composed of TE sequences. The mechanism of induction of piRNA production by these loci is still enigmatic. We have shown that, in Drosophila melanogaster, a cluster of tandemly repeated P-lacZ-white transgenes can be activated for piRNA production by maternal inheritance of a cytoplasm containing homologous piRNAs. This activated state is stably transmitted over generations and allows trans-silencing of a homologous transgenic target in the female germline. Such an epigenetic conversion displays the functional characteristics of a paramutation, i.e., a heritable epigenetic modification of one allele by the other. We report here that piRNA production and trans-silencing capacities of the paramutated cluster depend on the function of the rhino, cutoff, and zucchini genes involved in primary piRNA biogenesis in the germline, as well as on that of the aubergine gene implicated in the ping-pong piRNA amplification step. The 21-nt RNAs, which are produced by the paramutated cluster, in addition to 23- to 28-nt piRNAs are not necessary for paramutation to occur. Production of these 21-nt RNAs requires Dicer-2 but also all the piRNA genes tested. Moreover, cytoplasmic transmission of piRNAs homologous to only a subregion of the transgenic locus can generate a strong paramutated locus that produces piRNAs along the whole length of the transgenes. Finally, we observed that maternally inherited transgenic small RNAs can also impact transgene expression in the soma. In conclusion, paramutation involves both nuclear (Rhino, Cutoff) and cytoplasmic (Aubergine, Zucchini) actors of the piRNA pathway. In addition, since it is observed between nonfully homologous loci located on different chromosomes, paramutation may play a crucial role in epigenome shaping in Drosophila natural populations.
| S-EPMC4676525 | biostudies-literature
Project description:In the nematode Caenorhabditis elegans, different small RNA-dependent gene silencing mechanisms act in the germline to initiate transgenerational gene silencing. Piwi-interacting RNAs (piRNAs) can initiate transposon and gene silencing by acting upstream of endogenous short interfering RNAs (siRNAs), which engage a nuclear RNA interference (RNAi) pathway to trigger transcriptional gene silencing. Once gene silencing has been established, it can be stably maintained over multiple generations without the requirement of the initial trigger and is also referred to as RNAe or paramutation. This heritable silencing depends on the integrity of the nuclear RNAi pathway. However, the exact mechanism by which silencing is maintained across generations is not understood.Here we demonstrate that silencing of piRNA targets involves the production of two distinct classes of small RNAs with different genetic requirements. The first class, secondary siRNAs, are localized close to the direct target site for piRNAs. Nuclear import of the secondary siRNAs by the Argonaute HRDE-1 leads to the production of a distinct class of small RNAs that map throughout the transcript, which we term tertiary siRNAs. Both classes of small RNAs are necessary for full repression of the target gene and can be maintained independently of the initial piRNA trigger. Consistently, we observed a form of paramutation associated with tertiary siRNAs. Once paramutated, a tertiary siRNA generating allele confers dominant silencing in the progeny regardless of its own transmission, suggesting germline-transmitted siRNAs are sufficient for multigenerational silencing.
2015-04-01 | GSE66344 | GEO
Project description:Paramutation is an exception among eukaryotes, in which epigenetic information is conserved through mitosis and meiosis. It has been studied for over 70 years in maize, but the mechanisms involved are largely unknown. All previously described actors of paramutation encoding components of the RNA-dependent DNA-methylation pathway (RdDM) are involved in the biogenesis of 24nt small RNAs. However, no actors of paramutation have been identified in the effector complex of RdDM. Through a combination of reverse genetics, immunolocalization and immunoprecipitation (siRNA-IP) we found that ARGONAUTE104 (AGO104), AGO105 and AGO119 are members of the RdDM effector complex in maize and bind siRNAs produced from the tandem repeats required for paramutation at the b1 locus. We also showed that AGO104 is an effector of the b1 paramutation in maize.
2021-04-22 | GSE172479 | GEO
Project description:Primary piRNAs in Drosophila ovarian somatic cells arise from piRNA cluster transcripts and the 3′ UTRs of a subset of mRNAs, including Traffic jam (Tj) mRNA. However, it is unclear how these RNAs are determined as primary piRNA sources. Here, we identify a cis-acting 100-nt fragment in the Tj 3′ UTR that is sufficient for producing artificial piRNAs from unintegrated DNA. These artificial piRNAs were effective in endogenous gene transcriptional silencing. Yb, a core component of primary piRNA biogenesis center Yb bodies, directly bound the Tj-cis-element. Disruption of this interaction markedly reduced piRNA production. Thus, Yb is the trans-acting partner of the Tj-cis-element. Yb-CLIP revealed that Yb-binding correlated with somatic piRNA production but Tj-cis-element downstream sequences produced few artificial piRNAs. Thus, Yb determines primary piRNA sources by two modes of action; primary binding to cis-elements to specify substrates, and secondary binding to downstream regions to increase diversity in piRNA populations. HITS-CLIP of Yb in OSCs (Ovarian Somatic Cells) depleted for tj cis-element, and small RNA sequencing of Piwi-piRNAs in OSCs depleted for tj cis-element.
2015-06-05 | E-GEOD-69625 | biostudies-arrayexpress
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:In mice, the PIWI-piRNA pathway is essential to re-establish transposon silencing during male germline reprogramming. The cytoplasmic PIWI protein MILI mediates piRNA-guided transposon RNA cleavage as well as piRNA amplification. MIWI2-bound piRNAs and its nuclear localization are proposed to be dependent upon MILI function. Here, we demonstrate the existence of a piRNA biogenesis pathway that in the absence of MILI that sustains partial MIWI2 function and reprogramming activity.
2017-04-25 | E-MTAB-5561 | biostudies-arrayexpress