Drosophila melanogaster
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA274377 | ENA |
REPOSITORIES: ENA
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Project description:Drosophila Piwi-family proteins have been implicated in transposon control. Here, we examine piwi-interacting RNAs (piRNAs) associated with each Drosophila Piwi protein and find that Piwi and Aubergine bind RNAs that are predominantly antisense to transposons, whereas Ago3 complexes contain predominantly sense piRNAs. As in mammals, the majority of Drosophila piRNAs are derived from discrete genomic loci. These loci comprise mainly defective transposon sequences, and some have previously been identified as master regulators of transposon activity. Our data suggest that heterochromatic piRNA loci interact with potentially active, euchromatic transposons to form an adaptive system for transposon control. Complementary relationships between sense and antisense piRNA populations suggest an amplification loop wherein each piRNA-directed cleavage event generates the 5’ end of a new piRNA. Thus, sense piRNAs, formed following cleavage of transposon mRNAs, may enhance production of antisense piRNAs, complementary to active elements, by directing cleavage of transcripts from master control loci. Keywords: small RNA libraries from Drosophila ovaries
2007-03-08 | GSE6734 | GEO
Project description:Drosophila Piwi-family proteins have been implicated in transposon control. Here, we examine piwi-interacting RNAs (piRNAs) associated with each Drosophila Piwi protein and find that Piwi and Aubergine bind RNAs that are predominantly antisense to transposons, whereas Ago3 complexes contain predominantly sense piRNAs. As in mammals, the majority of Drosophila piRNAs are derived from discrete genomic loci. These loci comprise mainly defective transposon sequences, and some have previously been identified as master regulators of transposon activity. Our data suggest that heterochromatic piRNA loci interact with potentially active, euchromatic transposons to form an adaptive system for transposon control. Complementary relationships between sense and antisense piRNA populations suggest an amplification loop wherein each piRNA-directed cleavage event generates the 5’ end of a new piRNA. Thus, sense piRNAs, formed following cleavage of transposon mRNAs, may enhance production of antisense piRNAs, complementary to active elements, by directing cleavage of transcripts from master control loci. Keywords: small RNA libraries from Drosophila ovaries small RNAs (23-29nt) were isolated from total ovarian RNA or from immunopreciptated Piwi/Aubergine/Ago3 complexes. cDNA libraries were constructed after Pfeffer et al. 2005 (Nat. Methods) and sequenced at 454 Life Sciences. The used strain is OregonR. Only sequences matching the Release5 genome assembly (www.fruitfly.org) are considered.
2007-03-08 | E-GEOD-6734 | 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: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:Piwi in a complex with Piwi-interacting RNAs (piRNAs) triggers transcriptional silencing of Transposable Elements (TEs) in Drosophila ovaries, thus ensuring genome stability. To do this, Piwi must scan the nascent transcripts of genes and TEs for complementarity to piRNAs. The mechanism of this scanning is currently unknown. Here we report the DamID-seq mapping of multiple Piwi-interacting chromosomal domains in somatic cells of Drosophila ovaries. These domains significantly overlap with genomic regions tethered to Nuclear Pore Complexes (NPCs). Accordingly, Piwi was coimmunoprecipitated with the component of NPCs Elys and with the Xmas-2 subunit of RNA transcription and export complex, known to interact with NPCs. However, only a small Piwi fraction has transient access to DNA at nuclear pores. Importantly, although 36%of protein-coding genes overlap with Piwi-interacting domains and RNA-immunoprecipitation results demonstrate promiscuous Piwi binding to numerous genic and TE nuclear transcripts, according to available data Piwi does not silence these genes, likely due to the absence of perfect base-pairing between piRNAs and their transcripts.
2017-04-19 | GSE87346 | GEO
Project description:Belle has been known to be co-localized with piRNA-related proteins at the nuage of germline cells during Drosophila oogenesis. However, its role in piRNA biogenesis remains unclear. To reveal whether Belle is involved in regulating piRNA expression, we performed next-generation sequencing analysis of small non-coding RNAs on ovaries harvested from the wild type (W1118) and trans-heterozygous bel[74407/neo30] mutant. Small RNA-seq experiments were performed on three individual ovary samples with the same genotype. For piRNA expression analysis, we performed mapping of three sets of small RNA sequencing reads for each genotype to previously identified eight distinct piRNA clusters located in four different Drosophila chromosomes (from X to 4). Analysis of the piRNA expression profiling from these piRNA cluster loci indicates that some specific piRNA populations were either upregulated or downregulated in bel mutant ovaries compared with wild-type ovaries. Furthermore, we performed systematic analysis by mapping piRNA sequencing reads to sequences of all identified Drosophila transposable elements (TEs) to classify and measure piRNA reads based on their TE targets. Among 124 TE-classified piRNA populations, 9 and 20 of them were upregulated and downregulated (≥2 folds), respectively, in bel74407/neo30 mutant ovaries compared with those from wild-type ovaries. To examine the effect of the bel[74407/neo30] mutation on the ping-pong cycle for secondary piRNA biogenesis, analysis of the ping-pong signature of piRNAs specifically mapped to the retro-element Burdock was performed. The ping-pong signature for the generation of secondary piRNAs was not significantly altered in bel mutants compared with the wild type. These results, taken together, indicate that Bel is not required for primary and secondary piRNA biogenesis, but it is involved in regulating expression of specific subsets of piRNA populations.
2017-09-01 | GSE65565 | GEO
Project description:23-29 nt Piwi-interacting RNAs (piRNAs) are crucial components of the ribonucleoprotein complexes which silence the most abundant class of mobile genetic elements in human genome, retrotransposons, in germline (germ) cells. In these cells, antisense piRNAs serve as RNA guides for Piwi proteins, base pairing with transposon RNAs which are subsequently cleaved by Piwi proteins. Germ cells belong to special class of stem cells which ultimately give rise to eggs and sperm and therefore, to next generations. Therefore, piRNAs protect next-generation genomes from devastating mutations caused by transposon insertions. Although, role of piRNAs in germ cells has been studied, functions of piRNAs and their associated proteins in somatic cells are not well understood. Importantly, Piwi proteins are expressed in the fruit fly Drosophila brain and are required for the silencing of transposable elements there, clearly indicating that Piwi-associated piRNAs are involved in this process in the brain. Furthermore, piRNAs have been implicated in the memory formation mechanisms in Aplysia brain. In addition to Piwi proteins, their associated partner, molecular scaffold Tudor protein, participates in piRNA biogenesis in germ cells and it is absolutely required for germline development. However, although tudor gene is expressed in the fly brain, its role in the central nervous system is not understood. In this study, we look at the role of Tudor as an essential player in piRNA biogenesis in Drosophila brain.
2020-11-27 | GSE149748 | GEO
Project description:PIWI-interacting RNAs (piRNAs) are animal gonad-specific small RNAs that control the activity of transposable elements. Long single stranded RNAs from a variety of sources are substrates for the nebulous primary processing pathway that converts these into thousands of 24-30 nucleotide (nt) piRNAs. How these transcripts are selected as precursors is not known. Here we show that targeting a transcript with PIWI slicer activity of cysosolic Ago3 is sufficient to trigger ~30-nt waves of non-overlapping primary piRNAs in the fly ovarian germline. The generated primary piRNAs are almost exclusively loaded into the nuclear PIWI protein, Piwi. In the fly ovarian somatic environment we find that an RNA fragment from the 5? end of a piRNA cluster is able to direct a heterologous sequence into primary processing. This piRNA trigger sequence (PTS) element drives generation of overlapping piRNAs from the transcript. Both mechanisms proceed with general 5?-3? directionality. We propose that the former pathway serves to link cytoplasmic silencing of a target to nuclear transcriptional repression, while the latter extracts silencing information from a wide variety of genomic sources including piRNA clusters, select protein coding and transposon transcripts. Total or immunoprecipitated small RNAs were purified from transfected BmN4 cells, Drosophila ovarian somatic cells (OSC) and from fly ovaries and high-throughput sequencing libraries were prepared. The mouse testicular RNAs were purified after ribozero treatment.
2015-07-09 | E-GEOD-69102 | biostudies-arrayexpress
Project description:Piwi-interacting RNAs (piRNAs) suppress transposon activity in animal germ cells. In the Drosophila ovary, primary Aubergine (Aub)-bound antisense piRNAs initiate the ping-pong cycle to produce secondary AGO3-bound sense piRNAs. This increases the number of secondary Aub-bound antisense piRNAs that can act to destroy transposon mRNAs. Here we show that Krimper (Krimp), a Tudor-domain protein, directly interacts with piRNA-free AGO3 to promote symmetrical dimethylarginine (sDMA) modification, ensuring sense piRNA-loading onto sDMA-modified AGO3. In aub mutant ovaries, AGO3 associates with ping-pong signature piRNAs, suggesting AGO3’s compatibility with primary piRNA loading. Krimp sequesters ectopically expressed AGO3 within Krimp bodies in cultured ovarian somatic cells (OSCs), in which only the primary piRNA pathway operates. Upon krimp-RNAi in OSCs, AGO3 loads with piRNAs, further showing the capacity of AGO3 for primary piRNA loading. We propose that Krimp enforces an antisense bias on piRNA pools by binding AGO3 and blocking its access to primary piRNAs. In order to investigate function of Krimp in piRNA pathway, sequencing of Piwi subfamily protein associated small RNAs was performed using adult Drosophila ovaries and Ovarian Somatic Cells (OSCs) depleted for Krimp or Aub.
2015-05-28 | E-GEOD-69293 | biostudies-arrayexpress
Project description:Transposable elements (TEs), whose propagation can result in severe damage to the host genome, are silenced in the animal gonad by Piwi-interacting RNAs (piRNAs). piRNAs produced in the ovaries are deposited in the embryonic germline and initiate TE repression in the germline progeny. Whether the maternally transmitted piRNAs play a role in the silencing of somatic TEs is, however, unknown. Here we show that maternally transmitted piRNAs from the tirant retrotransposon in Drosophila are required for the somatic silencing of the TE and correlate with an increase in histone H3K9 trimethylation an active tirant copy. Comparison of tirant piRNAs in two Drosophila simulans natural populations.
2013-04-09 | E-GEOD-40592 | biostudies-arrayexpress