Drosophila melanogaster
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA119663 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR029028.fastq.gz | Fastqsanger.gz | |||
| SRR029029.fastq.gz | Fastqsanger.gz | |||
| SRR029030.fastq.gz | Fastqsanger.gz | |||
| SRR029031.fastq.gz | Fastqsanger.gz | |||
| SRR029032.fastq.gz | Fastqsanger.gz |
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Project description:In Drosophila, siRNAs are classified as endo- or exo-siRNAs based on their origin. Both are processed from double-stranded RNA precursors by Dcr-2, then loaded into the Argonaute protein Ago2. While exo-siRNAs serve to defend the cell against viruses, endo-siRNAs restrict the spread of selfish DNA in somatic cells, analogous to piRNAs in the germ line. Endo- and exo-siRNAs display a differential requirement for double-stranded RNA binding domain proteins (dsRBPs): R2D2 is needed to load exo-siRNAs into Ago2 while the PD isoform of Loquacious (Loqs-PD) stimulates Dcr-2 during the nucleolytic processing of hairpin-derived endo-siRNAs. In cell culture assays, R2D2 antagonizes Loqs-PD in endo-siRNA silencing and Loqs-PD is an inhibitor of RNA interference. Loqs-PD can interact via the C-terminus unique to this isoform with the DExH/D-helicase domain of Drosophila Dcr-2, where binding of R2D2 has also been localized. Separation of the two pathways is not complete; rather, the dicing and Ago2-loading steps appear uncoupled, analogous to the corresponding steps in miRNA biogenesis. Analysis of deep sequencing data further demonstrates that in r2d2 mutant flies, siRNAs can be loaded into Ago2 but not all siRNA classes are equally proficient for this. Thus, the canonical Ago2-RISC loading complex can be bypassed under certain circumstances.
2011-02-10 | GSE26230 | GEO
Project description:In Drosophila, siRNAs are classified as endo- or exo-siRNAs based on their origin. Both are processed from double-stranded RNA precursors by Dcr-2, then loaded into the Argonaute protein Ago2. While exo-siRNAs serve to defend the cell against viruses, endo-siRNAs restrict the spread of selfish DNA in somatic cells, analogous to piRNAs in the germ line. Endo- and exo-siRNAs display a differential requirement for double-stranded RNA binding domain proteins (dsRBPs): R2D2 is needed to load exo-siRNAs into Ago2 while the PD isoform of Loquacious (Loqs-PD) stimulates Dcr-2 during the nucleolytic processing of hairpin-derived endo-siRNAs. In cell culture assays, R2D2 antagonizes Loqs-PD in endo-siRNA silencing and Loqs-PD is an inhibitor of RNA interference. Loqs-PD can interact via the C-terminus unique to this isoform with the DExH/D-helicase domain of Drosophila Dcr-2, where binding of R2D2 has also been localized. Separation of the two pathways is not complete; rather, the dicing and Ago2-loading steps appear uncoupled, analogous to the corresponding steps in miRNA biogenesis. Analysis of deep sequencing data further demonstrates that in r2d2 mutant flies, siRNAs can be loaded into Ago2 but not all siRNA classes are equally proficient for this. Thus, the canonical Ago2-RISC loading complex can be bypassed under certain circumstances. Examination of small RNAs from two different mutant strains as well as the corresponding heterozygous controls
2011-02-10 | E-GEOD-26230 | biostudies-arrayexpress
Project description:Effect of Nbr on the length of piRNAs and endo-siRNAs in Drosophila
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Project description:Identification and analysis of transgene-derived endo-siRNAs in Drosophila Schneider cells by Solexa sequencing.
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Project description:Drosophila melanogaster expresses three classes of small RNAs, which are classified according to their mechanisms of biogenesis. MicroRNAs are ~22-23-nt, ubiquitously expressed small RNAs that are sequentially processed from hairpin-like precursors by Drosha/Pasha and Dcr-1/Loquacious complexes. MicroRNAs usually associate with AGO1 and regulate the expression of protein-coding genes. Piwi-interacting RNAs (piRNAs) of ~24-28-nt associate with Piwi-family proteins and can arise from single-stranded precursors. piRNAs function in transposon silencing and are mainly restricted to gonadal tissues. Endo-siRNAs are found in both germline and somatic tissues. These ~21-nt RNAs are produced by a distinct Dicer, Dcr-2, and do not depend on Drosha/Pasha complexes. They predominantly bind to AGO2 and target both mobile elements and protein-coding genes. Surprisingly, a subset of endo-siRNAs strongly depend for their production on the dsRNA-binding protein Loquacious (Loqs), thought generally to be a partner for Dcr-1 and a co-factor for miRNA biogenesis. Endo-siRNA production depends on a specific Loqs isoform, Loqs-PD, which is distinct from the one, Loqs-PB, required for the production of microRNAs. Paralleling their roles in the biogenesis of distinct small RNA classes, Loqs-PD and Loqs-PB bind to different Dicer proteins, with Dcr-1/Loqs-PB complexes and Dcr-2/Loqs-PD complexes driving microRNA and endo-siRNA biogenesis, respectively. Small RNA profiling by high throughput sequencing
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Project description:Unrestricted movement of mobile genetic elements could cause pre-mature lethality in Drosophila melanogaster. Specifically, retro transposons can disrupt genomic integrity through insertions, deletions and chromosomal rearrangements. Therefore, eukaryotes have developed defense mechanisms to silence these elements. In Drosophila, endogenous small interfering (endo-siRNAs) repress retro transposon mobility in somatic cells. The generation of endo-siRNAs requires Dicer-2 processing of double-stranded RNA precursors, yet the origins of this precursor are unknown. Here we show that retro transposons in Dmel-2 cells produce sense and antisense transcripts and identify bonafide transcription start sites for these RNAs. We determine that retro transposon antisense transcripts are less polyadenylated than sense transcripts. RNA-seq and small RNA-seq upon Dicer-2 depletion showed global decrease in endo-siRNAs mapping to retro transposons and increased expression of both S and AS retro transposon transcripts. These data support a model in which double-stranded RNA precursors are derived from convergent transcription and retained in the nucleus. Dicer-2 processes these precursors into endo-siRNAs that silence both sense and antisense retro transposon transcripts. Reduction of sense retro transposon transcripts potentially lowers element specific protein levels required for movement. This mechanism preserves genomic integrity and is especially important for Drosophila fitness because mobile genetic elements are highly active.
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Project description:Small interfering RNAs (siRNAs) direct RNA interference (RNAi) in eukaryotes. In flies, somatic cells produce siRNAs from exogenous double-stranded RNA as a defense against viral infection. Here, we identify 21-nt long, endogenous siRNAs (endo-siRNAs) corresponding to transposons and heterochromatic sequences in the somatic cells of Drosophila melanogaster. We also detected endo-siRNAs complementary to mRNAs: these siRNAs disproportionately mapped to the complementary regions of overlapping mRNAs predicted to form dsRNA in vivo. Normal accumulation of somatic endo-siRNAs requires the siRNA-generating ribonuclease, Dicer-2, and the RNAi effector protein, Ago2. We propose that endo-siRNAs generated by the fly RNAi pathway silence selfish genetic elements in the soma much as piRNAs do in the germ line. Keywords: Small RNA detection and quantification.
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Project description:Drosophila melanogaster expresses three classes of small RNAs, which are classified according to their mechanisms of biogenesis. MicroRNAs are ~22-23-nt, ubiquitously expressed small RNAs that are sequentially processed from hairpin-like precursors by Drosha/Pasha and Dcr-1/Loquacious complexes. MicroRNAs usually associate with AGO1 and regulate the expression of protein-coding genes. Piwi-interacting RNAs (piRNAs) of ~24-28-nt associate with Piwi-family proteins and can arise from single-stranded precursors. piRNAs function in transposon silencing and are mainly restricted to gonadal tissues. Endo-siRNAs are found in both germline and somatic tissues. These ~21-nt RNAs are produced by a distinct Dicer, Dcr-2, and do not depend on Drosha/Pasha complexes. They predominantly bind to AGO2 and target both mobile elements and protein-coding genes. Surprisingly, a subset of endo-siRNAs strongly depend for their production on the dsRNA-binding protein Loquacious (Loqs), thought generally to be a partner for Dcr-1 and a co-factor for miRNA biogenesis. Endo-siRNA production depends on a specific Loqs isoform, Loqs-PD, which is distinct from the one, Loqs-PB, required for the production of microRNAs. Paralleling their roles in the biogenesis of distinct small RNA classes, Loqs-PD and Loqs-PB bind to different Dicer proteins, with Dcr-1/Loqs-PB complexes and Dcr-2/Loqs-PD complexes driving microRNA and endo-siRNA biogenesis, respectively. Small RNA profiling by high throughput sequencing Total RNA was isolated using Trizol reagent (Invitrogen) and size-fractionated by PAGE into 19-24nt. These were independently processed and sequenced using the Illumina GAII platform. In total, six libraries were analyzed.
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