Small RNAs produced in the wild-type and mutant Dicer-2 transgenic flies
Ontology highlight
ABSTRACT:
OTHER RELATED OMICS DATASETS IN: PRJNA329574
ORGANISM(S): synthetic construct Drosophila melanogaster
PROVIDER: GSE84532 | GEO | 2017/02/10
SECONDARY ACCESSION(S): PRJNA329574
REPOSITORIES: GEO
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Project description:Examine the abundance and length of siRNAs produced by mutant Dicer-2 in vivo and in vitro in order to understand the mechanism by which Dicer-2 produces highly precise 21 nt siRNAs.
2017-09-08 | GSE94803 | GEO
Project description:small RNAs produced in the mutant Dicer-2 transgenic flies
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Project description:Drosophila Dicer-1 produces microRNAs (miRNAs) from pre-miRNA, whereas Dicer-2 generates small interfering RNAs (siRNAs) from long dsRNA. loquacious (loqs) encodes three Dicer partner proteins, Loqs-PA, Loqs-PB, and, Loqs-PD, generated by alternative splicing. To understand the function of each Loqs isoform, we constructed loqs isoform-specific rescue flies. Loqs-PD promotes siRNA production in vivo by Dicer-2. Loqs-PA or Loqs-PB is required for viability, but the proteins are not fully redundant: Loqs-PB is required to produce a specific subset of miRNAs. Surprisingly, Loqs-PB tunes the product size cleaved by Dicer-1 from pre-miR-307a, generating a longer miRNA isoform with a distinct seed sequence and target specificity. The mouse and human Dicer-binding partner TRBP, a homolog of Loqs-PB, similarly tunes the site of pre-miR-132 cleavage by mammalian Dicer. Thus, Dicer-binding partner proteins can change the choice of cleavage site by Dicer, producing miRNAs with different target specificities than those that would be made by Dicer alone.
2012-12-07 | GSE37443 | GEO
Project description:Drosophila Dicer-1 produces microRNAs (miRNAs) from pre-miRNA, whereas Dicer-2 generates small interfering RNAs (siRNAs) from long dsRNA. loquacious (loqs) encodes three Dicer partner proteins, Loqs-PA, Loqs-PB, and, Loqs-PD, generated by alternative splicing. To understand the function of each Loqs isoform, we constructed loqs isoform-specific rescue flies. Loqs-PD promotes siRNA production in vivo by Dicer-2. Loqs-PA or Loqs-PB is required for viability, but the proteins are not fully redundant: Loqs-PB is required to produce a specific subset of miRNAs. Surprisingly, Loqs-PB tunes the product size cleaved by Dicer-1 from pre-miR-307a, generating a longer miRNA isoform with a distinct seed sequence and target specificity. The mouse and human Dicer-binding partner TRBP, a homolog of Loqs-PB, similarly tunes the site of pre-miR-132 cleavage by mammalian Dicer. Thus, Dicer-binding partner proteins can change the choice of cleavage site by Dicer, producing miRNAs with different target specificities than those that would be made by Dicer alone. Examination of Dicer-binding proteins on small RNA profiles of female fly heads, fly ovaries, mouse embryonic fibroblasts, and mouse tail fibroblasts.
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Project description:small RNAs produced in the wild-type and mutant Dicer-2 transgenic flies
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Project description:In eukaryotes, small RNAs (sRNAs) play critical roles in multiple biological processes. Dicer endonucleases are central to sRNA biogenesis. In plants, DICER-LIKE PROTEIN 3 (DCL3) produces 24-nt small interfering RNAs (siRNAs) that determine the specificity of the RNA-directed DNA methylation (RdDM) pathway. Here, we determined structure of a DCL3-pre-siRNA complex in an active dicing-competent state. The 5′-phosphorylated-A1 of the guide strand and the 1-nt 3′-overhang of the complementary strand are specifically recognized by a positively charged pocket and an aromatic cap, respectively. The 24-nt siRNA length dependence relies on the separation between the 5′-phosphorylated-end of the guide RNA and dual cleavage sites formed by the paired RNaseIII domains. These structural studies, complemented by functional data, reveal insights into the dicing principle for Dicers in general.
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Project description:While RNA interference (RNAi) functions as a potent antiviral innate immune response in plants and invertebrates, mammalian somatic cells appear incapable of mounting an RNAi response and few small interfering RNAs (siRNAs) can be detected. To examine why siRNA production is inefficient, we have generated double knockout human cells lacking both Dicer and PKR. Using these cells, which tolerate dsRNA expression, we show that mutant forms of human Dicer lacking the amino-terminal helicase domain can process dsRNAs to produce high levels of siRNAs that are readily detectable by Northern blot and that can effectively and specifically inhibit the expression of cognate mRNAs. However, even these more active Dicer mutants produce only modest levels of viral siRNAs in infected cells that are insufficient to inhibit viral replication. We conclude that the production of siRNAs from viral dsRNAs is likely inefficient due to the poor accessibility of viral dsRNAs to Dicer.
2015-12-02 | GSE69433 | GEO
Project description:RNA silencing relies on specific and efficient processing of dsRNA by DICER which produces microRNAs (miRNAs) and small interfering RNAs (siRNAs). However, our current knowledge of DICER’s specificity is restricted to the secondary structures of its substrates: a dsRNA than 22 bp with a 2-nt 3′ overhang. We recently found evidence pointing to additional sequence-dependent determinant(s) beyond these features. To systematically interrogate the features of precursor miRNAs (pre-miRNAs), we carried out massively parallel assays with over a million pre-miRNA variants. Our analyses revealed a highly conserved cis-acting element, termed the “GYM” motif (paired G, paired pyrimidine, and mismatched C or A) at the cleavage site, which strongly promotes processing at a specific position. We find that the C-terminal double-stranded RNA binding domain (dsRBD) of DICER recognizes the GYM motif. Mutation of the dsRBD alters pre-miRNA cleavage sites and impairs processing in a motif-dependent fashion, which in turn affects the miRNA repertoire in cells. Consistently, integrating the GYM motif into short hairpin RNA (shRNA) or Dicer substrate siRNA (DsiRNA) potentiates RNA interference.
2022-12-16 | GSE202533 | GEO
Project description:Canonical small interfering RNAs (siRNAs) are generated by the cleavage of double-stranded RNA (dsRNA) by the ribonuclease Dicer. siRNAs are found in plants, animals, and some fungi where they bind to Argonautes to direct RNA silencing. In this study, we characterized the canonical Dicer-dependent siRNAs of C. elegans. We identified thousands of endogenous loci, representing dozens of unique elements, that give rise to low to moderate levels of siRNAs, called 23H-RNAs. These loci include repetitive elements, alleged coding genes, pseudogenes, non-coding RNAs, and unannotated features, many of which adopt hairpin structures. Using protein-small RNA co-immunoprecipitation, we identified the Argonautes that associate with 23H-RNAs and using mRNA-sequencing we explored their roles in gene regulation.
2024-01-29 | GSE254442 | GEO
Project description:RNA silencing relies on specific and efficient processing of dsRNA by DICER which produces microRNAs (miRNAs) and small interfering RNAs (siRNAs). However, our current knowledge of DICER’s specificity is restricted to the secondary structures of its substrates: a dsRNA than 22 bp with a 2-nt 3′ overhang. We recently found evidence pointing to additional sequence-dependent determinant(s) beyond these features. To systematically interrogate the features of precursor miRNAs (pre-miRNAs), we carried out massively parallel assays with over a million pre-miRNA variants. Our analyses revealed a highly conserved cis-acting element, termed the “GYM” motif (paired G, paired pyrimidine, and mismatched C or A) at the cleavage site, which strongly promotes processing at a specific position. We find that the C-terminal double-stranded RNA binding domain (dsRBD) of DICER recognizes the GYM motif. Mutation of the dsRBD alters pre-miRNA cleavage sites and impairs processing in a motif-dependent fashion, which in turn affects the miRNA repertoire in cells. Consistently, integrating the GYM motif into short hairpin RNA (shRNA) or Dicer substrate siRNA (DsiRNA) potentiates RNA interference.
2022-12-16 | GSE202530 | GEO