Paf1 modulates Piwi/piRNA silencing capacity in Drosophila
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ABSTRACT:
ORGANISM(S): Drosophila melanogaster
PROVIDER: GSE84766 | GEO | 2017/08/31
SECONDARY ACCESSION(S): PRJNA331099
REPOSITORIES: GEO
Similar Datasets
Project description:To test the directness of factors in initiating PIWI-directed gene silencing, we employed a Piwi-interacting RNA (piRNA)-targeted reporter assay in Drosophila ovary somatic sheet (OSS) cells [1]. This assay confirmed direct silencing roles for piRNA biogenesis factors and PIWI-associated factors [2-12] but suggested that chromatin-modifying proteins may act downstream of the initial silencing event. Our data also revealed that RNA-polymerase-II-associated proteins like PAF1 and RTF1 antagonize PIWI-directed silencing. PAF1 knockdown enhances PIWI silencing of reporters when piRNAs target the transcript region proximal to the promoter. Loss of PAF1 suppresses endogenous transposable element (TE) transcript maturation, whereas a subset of gene transcripts and long-non-coding RNAs adjacent to TE insertions are affected by PAF1 knockdown in a similar fashion to piRNA-targeted reporters. Additionally, transcription activation at specific TEs and TE-adjacent loci during PIWI knockdown is suppressed when PIWI and PAF1 levels are both reduced. Our study suggests a mechanistic conservation between fission yeast PAF1 repressing AGO1/small interfering RNA (siRNA)-directed silencing [13, 14] and Drosophila PAF1 opposing PIWI/piRNA-directed silencing.
| S-EPMC5611886 | biostudies-literature
Project description:This study examines the regulatory capacity of the Piwi protein in the Drosophila OSS cell. Piwi CLIP-Seq, mRNA-Seq and nascent RNAseq datasets were integrated to determine how Piwi proteins where using piRNAs and binding interactions to regulate the expression of transcripts. We also sequenced the genomes of various OSS cell lines.
2014-09-15 | GSE45112 | GEO
Project description:This study examines the regulatory capacity of the Piwi protein in the Drosophila OSS cell. Piwi CLIP-Seq, mRNA-Seq and nascent RNAseq datasets were integrated to determine how Piwi proteins where using piRNAs and binding interactions to regulate the expression of transcripts. We also sequenced the genomes of various OSS cell lines. We first performed several replicates of a Piw CLIP-Seq experiment to isolate RNA fragments as CLIP-tags to discover which transcripts are preferentially bound by the Piwi protein. Then we performed several types of mRNA expression profiling experiments using several forms of mRNA-Seq library construction formats. Finally, we sequenced the genomes from various OSS cell lines. The genomic sequencing component of the study is represented by BioProject PRJNA240323. The genomic sequencing raw data have been deposited at SRA (SRP039565).
2014-09-15 | E-GEOD-45112 | biostudies-arrayexpress
Project description:In the Metazoan germline, piwi proteins and associated piwi-interacting RNAs (piRNAs) provide a defense system against the expression of transposable elements. In the cytoplasm, piRNA sequences guide piwi complexes to destroy complementary transposon transcripts by endonucleolytic cleavage. However, some piwi family members are nuclear, raising the possibility of alternative pathways for piRNA-mediated regulation of gene expression. We found that Drosophila Piwi is recruited to chromatin, co-localizing with RNA polymerase II on polytene chromosomes. Knockdown of Piwi in the germline increases expression of transposable elements that are targeted by piRNAs, whereas protein-coding genes remain largely unaffected. De-repression of transposons upon Piwi depletion correlates with increased occupancy of RNA polymerase II on their promoters. Expression of piRNAs that target a reporter construct results in a decrease in Pol II occupancy and an increase in repressive H3K9me3 marks and HP1 on the reporter locus. Our results indicate that Piwi identifies targets complementary to the associated piRNA and induces transcriptional repression by establishing a repressive chromatin state when correct targets are found.
2013-02-11 | GSE43829 | GEO
Project description:In the Metazoan germline, piwi proteins and associated piwi-interacting RNAs (piRNAs) provide a defense system against the expression of transposable elements. In the cytoplasm, piRNA sequences guide piwi complexes to destroy complementary transposon transcripts by endonucleolytic cleavage. However, some piwi family members are nuclear, raising the possibility of alternative pathways for piRNA-mediated regulation of gene expression. We found that Drosophila Piwi is recruited to chromatin, co-localizing with RNA polymerase II on polytene chromosomes. Knockdown of Piwi in the germline increases expression of transposable elements that are targeted by piRNAs, whereas protein-coding genes remain largely unaffected. De-repression of transposons upon Piwi depletion correlates with increased occupancy of RNA polymerase II on their promoters. Expression of piRNAs that target a reporter construct results in a decrease in Pol II occupancy and an increase in repressive H3K9me3 marks and HP1 on the reporter locus. Our results indicate that Piwi identifies targets complementary to the associated piRNA and induces transcriptional repression by establishing a repressive chromatin state when correct targets are found. Examination of mRNA levels, Pol II occupancy, and chromatin repressive state in D. melanogaster ovaries upon Piwi knockdown and Piwi mutation. This records present the sequencing data related to Piwi knockdown study portion.
2013-02-11 | E-GEOD-43829 | biostudies-arrayexpress
Project description:Heterochromatin, representing the silenced state of transcription, largely consists of transposon-enriched and highly repetitive sequences. Implicated in heterochromatin formation and transcriptional silencing in Drosophila are PIWI and repeat-associated small interfering RNAs (rasiRNAs). Despite this, the role of PIWI in rasiRNA expression and heterochromatic silencing remains unknown. Here we report the identification and characterization of 12,903 PIWI-interacting RNAs (piRNAs) in Drosophila, demonstrating that rasiRNAs represent a subset of piRNAs. Keywords: PIWI, piRNA, epigenetic regulation, heterochromatin
2007-10-25 | GSE9138 | GEO
Project description:This study examines the population of transcripts associated with the Xenopus Piwi proteins, Xiwi and Xili, from X.laevis and X.tropicalis. RIP-seq, CLIP-seq, piRNA-seq, and mRNA-seq datasets were integrated to determine how the Xenopus Piwi proteins where using piRNAs and binding interactions to associate with transcripts in gonadal cells. We performed several replicates of a Piw CLIP-Seq experiment to isolate RNA fragments as CLIP-tags to discover which transcripts are preferentially bound by the Piwi protein. Then we performed several types of mRNA expression profiling experiments using several forms of mRNA-Seq library construction formats. Finally, we sequenced the piRNAs from the OSS cells
2015-11-10 | E-GEOD-63228 | biostudies-arrayexpress
Project description:Heterochromatin, representing the silenced state of transcription, largely consists of transposon-enriched and highly repetitive sequences. Implicated in heterochromatin formation and transcriptional silencing in Drosophila are PIWI and repeat-associated small interfering RNAs (rasiRNAs). Despite this, the role of PIWI in rasiRNA expression and heterochromatic silencing remains unknown. Here we report the identification and characterization of 12,903 PIWI-interacting RNAs (piRNAs) in Drosophila, demonstrating that rasiRNAs represent a subset of piRNAs. Keywords: PIWI, piRNA, epigenetic regulation, heterochromatin PIWI-associated small RNA cDNA library was sequenced for one time by high-throughput 454 pyrosequencing. Putative small RNA sequences were extracted and BLAST against the Drosophila melanogaster genome release 5. Presented here is a list of non-redundant PIWI-associated small RNAs, which have at least one genome match determined by BLASTn.
2007-10-24 | E-GEOD-9138 | biostudies-arrayexpress
Project description:Silencing of transposons in the Drosophila ovary relies on three Piwi-family proteins, Piwi, Aubergine (Aub), and Ago3, acting in concert with their small RNA guides, the piRNAs. Aub and Ago3 are found in the germ cell cytoplasm, where they function in the ping-pong cycle to consume transposon mRNAs. The nuclear Piwi protein is required for transposon silencing in both germ and somatic follicle cells, yet the precise mechanisms by which Piwi acts remain largely unclear. We investigated the role of Piwi by combining cell-type specific knockdowns with measurements of steady state transposon mRNA levels, nascent RNA synthesis, and small RNA abundance. In somatic cells, Piwi loss lead to concerted effects on nascent transcripts and transposon mRNAs, indicating that Piwi acts through transcriptional gene silencing (TGS). In germ cells, Piwi loss showed disproportionate impacts on steady state RNA levels, indicating that it also exerts an effect on post-transcriptional gene silencing (PTGS). Piwi knockdown affected levels of germ cell piRNAs presumably bound to Aub and Ago3, perhaps explaining its post-transcriptional impacts. Overall, our results indicate that Piwi plays multiple roles in the piRNA pathway, in part enforcing transposon repression through effects on transcription but also participating in germ cell piRNA biogenesis.
2013-02-09 | GSE43360 | GEO
Project description:PIWI-interacting RNAs (piRNAs) are germline-specific small RNAs that form effector complexes with PIWI proteins (Piwi–piRNA complexes), and plays a critical role for preserving genomic integrity by repressing transposable elements (TEs). Drosophila Piwi transcriptionally silences specific targets through heterochromatin formation, and increases H3K9me3 and histone H1. Additionally, Nxf2, a nuclear RNA export factor variant, has been identified as a co-factor. Using ChEP and DamID-seq, we uncover Piwi/Nxf2-dependent target association with nuclear lamins. Hi-C analysis of Piwi or Nxf2 depleted cells reveals decreased intra-TAD and increased inter-TAD interaction in regions harboring Piwi–piRNA target TEs. Using a forced tethering system, we analyze the functional effects of Piwi–piRNA/Nxf2-mediated recruitment of piRNA target regions to the nuclear periphery. Removal of active histone marks is followed by transcriptional silencing, chromatin conformational changes, and H3K9me3 and H1 association. Our data show that the Piwi–piRNA pathway can induce stepwise changes in nuclear architecture and chromatin state at target loci for transcriptional silencing.
2021-07-01 | GSE158082 | GEO