Piwi suppresses transcription of Brahma-dependent transposons via Maelstrom in ovarian somatic cells
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ABSTRACT:
PROVIDER: PRJNA423181 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR11969177.fastq.gz | Fastqsanger.gz | |||
| SRR11969178.fastq.gz | Fastqsanger.gz | |||
| SRR11969179.fastq.gz | Fastqsanger.gz | |||
| SRR11969180.fastq.gz | Fastqsanger.gz | |||
| SRR6395802_1.fastq.gz | Fastqsanger.gz |
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Project description:Drosophila Piwi associates with PIWI-interacting RNAs (piRNAs) and represses transposons transcriptionally through heterochromatinization; however, this process is poorly understood. Here, we identify Brahma (Brm), the core adenosine triphosphatase of the SWI/SNF chromatin remodeling complex, as a new Piwi interactor, and show Brm involvement in activating transcription of Piwi-targeted transposons before silencing. Bioinformatic analyses indicated that Piwi, once bound to target RNAs, reduced the occupancies of SWI/SNF and RNA polymerase II (Pol II) on target loci, abrogating transcription. Artificial piRNA-driven targeting of Piwi to RNA transcripts enhanced repression of Brm-dependent reporters compared with Brm-independent reporters. This was dependent on Piwi cofactors, Gtsf1/Asterix (Gtsf1), Panoramix/Silencio (Panx), and Maelstrom (Mael), but not Eggless/dSetdb (Egg)–mediated H3K9me3 deposition. The lambdaN-box B–mediated tethering of Mael to reporters repressed Brm-dependent genes in the absence of Piwi, Panx, and Gtsf1. We propose that Piwi, via Mael, can rapidly suppress transcription of Brm-dependent genes to facilitate heterochromatin formation.
2020-12-13 | GSE108329 | GEO
Project description:Drosophila Piwi associates with PIWI-interacting RNAs (piRNAs) and represses transposons transcriptionally through heterochromatinization; however, this process is poorly understood. Here, we identify Brahma (Brm), the core adenosine triphosphatase of the SWI/SNF chromatin remodeling complex, as a new Piwi interactor, and show Brm involvement in activating transcription of Piwi-targeted transposons before silencing. Bioinformatic analyses indicated that Piwi, once bound to target RNAs, reduced the occupancies of SWI/SNF and RNA polymerase II (Pol II) on target loci, abrogating transcription. Artificial piRNA-driven targeting of Piwi to RNA transcripts enhanced repression of Brm-dependent reporters compared with Brm-independent reporters. This was dependent on Piwi cofactors, Gtsf1/Asterix (Gtsf1), Panoramix/Silencio (Panx), and Maelstrom (Mael), but not Eggless/dSetdb (Egg)-mediated H3K9me3 deposition. The λN-box B-mediated tethering of Mael to reporters repressed Brm-dependent genes in the absence of Piwi, Panx, and Gtsf1. We propose that Piwi, via Mael, can rapidly suppress transcription of Brm-dependent genes to facilitate heterochromatin formation.
| S-EPMC7732180 | biostudies-literature
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: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. Piwi function in transcriptional and post-transcriptional transposon silencing was probed using deep-sequencing of small RNAs, steady-state and nascent transcripts, and DNA associated with H3K9me3 chromatin mark. In all cases comparison of two samples was performed: Tj- or nos-driven knock down of piwi to respective knock down of white gene (control sample). RNA-seq dataset has two replicates.
2013-02-09 | E-GEOD-43360 | biostudies-arrayexpress
Project description:Xenopus Piwi protein associated transcripts indicate regulation beyond transposons
| PRJNA267016 | ENA
Project description:Despite exciting progress in understanding the Piwi-associ-ated RNA (piRNA) pathway in the germ line, less is known about this pathway in somatic cells. We showed previously that Piwi, a key component of the piRNA pathway in Drosophila, is regulated in somatic cells by Yb, a novel protein containing an RNA helicase-like motif and a Tudor-like domain. Yb is specifically expressed in gonadal somatic cells and regulates piwi in somatic niche cells to control germ line and somatic stem cell self-renewal. However, the molecular basis of the regulation remains elusive. Here, we report that Yb recruits Armitage (Armi), a putative RNA helicase involved in the piRNA pathway, to the Yb body, a cytoplasmic sphere to which Yb is exclusively localized. Moreover, co-immunoprecipitation experiments show that Yb forms a complex with Armi. In Yb mu- tants, Armi is dispersed throughout the cytoplasm, and Piwi fails to enter the nucleus and is rarely detectable in the cytoplasm. Furthermore, somatic piRNAs are drastically diminished, and soma-expressing transposons are desilenced. These observations indicate a crucial role of Yb and the Yb body in piRNA biogenesis, possibly by regulating the activity of Armi that controls the entry of Piwi into the nucleus for its function. Finally, we discovered putative endo-siRNAs in the flamenco locus and the Yb dependence of their expression. These observations further implicate a role for Yb in transposon silencing via both the piRNA and endo-siRNA pathways.
2011-02-10 | GSE26407 | GEO
Project description:Despite exciting progress in understanding the Piwi-associ-ated RNA (piRNA) pathway in the germ line, less is known about this pathway in somatic cells. We showed previously that Piwi, a key component of the piRNA pathway in Drosophila, is regulated in somatic cells by Yb, a novel protein containing an RNA helicase-like motif and a Tudor-like domain. Yb is specifically expressed in gonadal somatic cells and regulates piwi in somatic niche cells to control germ line and somatic stem cell self-renewal. However, the molecular basis of the regulation remains elusive. Here, we report that Yb recruits Armitage (Armi), a putative RNA helicase involved in the piRNA pathway, to the Yb body, a cytoplasmic sphere to which Yb is exclusively localized. Moreover, co-immunoprecipitation experiments show that Yb forms a complex with Armi. In Yb mu- tants, Armi is dispersed throughout the cytoplasm, and Piwi fails to enter the nucleus and is rarely detectable in the cytoplasm. Furthermore, somatic piRNAs are drastically diminished, and soma-expressing transposons are desilenced. These observations indicate a crucial role of Yb and the Yb body in piRNA biogenesis, possibly by regulating the activity of Armi that controls the entry of Piwi into the nucleus for its function. Finally, we discovered putative endo-siRNAs in the flamenco locus and the Yb dependence of their expression. These observations further implicate a role for Yb in transposon silencing via both the piRNA and endo-siRNA pathways. Examination of the effect of Yb on piRNA pathway
2011-02-10 | E-GEOD-26407 | biostudies-arrayexpress
Project description:The piRNA pathway controls transposon expression in animal germ cells, thereby ensuring genome stability over generations. piRNAs are maternally deposited and required for proper transposon silencing in adult offspring. However, a long-standing question in the field is the precise function of maternally deposited piRNAs and its associated factors during embryogenesis. Here, we probe the spatio-temporal expression patterns of several piRNA pathway components during early stages of development. Amongst those, factors required for transcriptional gene silencing (TGS) showed ubiquitous abundance in somatic and pole cells throughout the first half of embryogenesis. We further analysed the transcriptomes of various embryo stages and correlated these with the presence of selected chromatin marks. We found that a number of transposon families show bursts of transcription during early embryonic stages. Transposons heavily targeted by maternally deposited piRNAs accumulated repressive chromatin marks following their spike in expression. Furthermore, depletion of maternally deposited Piwi protein in early embryos resulted in increased expression of transposons targeted by inherited piRNAs and was accompanied by a strong loss of repressive chromatin marks at coding sequences. Overall, our data suggests a pivotal role for the piRNA pathway in transposon defence during Drosophila embryogenesis in somatic cells.
2021-07-26 | PXD022409 | Pride
Project description:Transposable elements (TEs) can damage genomes, thus organisms employ a variety of mechanisms to repress TE expression. The PIWI-piRNA pathway is a small RNA pathway that represses TE expression in the germline of animals. Here we explore the function of the pathway in the somatic stem cells of Hydra, a long-lived freshwater cnidarian. Hydra have three stem cell populations, all of which express PIWI proteins; endodermal and ectodermal epithelial stem cells are somatic, whereas the interstitial stem cells have germline competence. To study somatic function of the pathway we isolated piRNAs from Hydra that lack the interstitial lineage and found that these somatic piRNAs map predominantly to TE transcripts and display the conserved sequence signatures typical of germline piRNAs. Three lines of evidence suggest that the PIWI-piRNA pathway represses TEs in Hydra epithelial stem cells. First, epithelial knockdown of the Hydra piwi gene hywi resulted in upregulation of TE expression. Second, degradome sequencing revealed evidence of PIWI-mediated cleavage of TE RNAs in epithelial cells using the ping-pong mechanism. Finally, we demonstrated a direct association between Hywi protein and TE transcripts in epithelial cells using RNA immunoprecipitation. Altogether, our data reveal that the PIWI-piRNA pathway represses TE expression in the somatic cell lineages of Hydra, which we propose contributes to the extreme longevity of the organism. Furthermore, our results, in combination with others, suggest that somatic TE repression is an ancestral function of the PIWI-piRNA pathway.
2019-08-07 | GSE135440 | GEO
Project description:The PIWI interacting RNA pathway is a small RNA silencing system that keeps selfish genetic elements such as transposons under control in animal gonads. Several lines of evidence indicate that nuclear PIWI family proteins guide transcriptional silencing of their targets, yet the composition of the underlying silencing complex is unknown. Here we demonstrate that the double CHHC zinc finger protein Gtsf1 is an essential factor for Piwi mediated transcriptional repression in Drosophila. Cells lacking Gtsf1 contain nuclear Piwi loaded with piRNAs, yet Piwi's silencing capacity is ablated. Gtsf1 interacts stably with a sub-population of nuclear Piwi and loss of Gtsf1 phenocopies loss of Piwi in terms of deregulation of transposons, loss of H3K9me3 marks at euchromatic transposon insertions and deregulation of genes in proximity to repressed transposons. We propose that only a small fraction of nuclear Piwi interacts productively with a target RNA, resulting in assembly of a silencing complex with Gtsf1 as one core component. impact of loss of DmGtsf1 on transcription and H3K9m3 in ovarian somatic cells (OSC)
2013-09-06 | E-GEOD-48317 | biostudies-arrayexpress