A low-abundance class of Dicer-dependent siRNAs produced from a variety of features in C. elegans
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ABSTRACT:
ORGANISM(S): Caenorhabditis elegans
PROVIDER: GSE254442 | GEO | 2024/01/29
REPOSITORIES: GEO
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Project description:We aim to comprehensively characterize the small RNA population in oocytes Pseudogenes populate the mammalian genome as remnants of artifactual incorporation of coding mRNAs into transposon pathways 1. Here, we show that a subset of pseudogenes generates endogenous small interfering RNAs (endo-siRNAs) in mouse oocytes. In these cases, endo-siRNAs are often processed from double-stranded RNAs formed by hybridization of spliced transcripts from protein coding genes to antisense transcripts from homologous pseudogenes. In at least one case, an inverted repeat pseudogene gives rise to abundant small RNAs directly. A second class of endo-siRNAs may enforce repression of mobile genetic elements, acting in concert with piwi-interacting RNAs (piRNAs). Loss of Dicer increases expression of endo-siRNA targets, demonstrating the regulatory activity of these small RNAs. Our findings provide a function for pseudogenes in regulating gene expression via the RNAi pathway and may, in part, explain the evolutionary pressure to conserve Argonaute-mediated catalysis in mammals. Keywords: small RNAs profile
2008-03-28 | GSE10364 | GEO
Project description:Dicer is a deeply conserved endoribonuclease with key functions in small RNA biogenesis. Here we employed PAR-CLIP/iPAR-CLIP to identify direct Dicer binding sites in the transcriptomes of human cells and human. We found hundreds of novel miRNAs and non-canonical Dicer substrates with high sensitivity. Small RNA production depended on structure of the binding site and is globally biased towards the 5' arm of hairpins. Unexpectedly, in both species Dicer bound numerous hairpins inside mRNAs without observable small RNA production. Our data revealed ~100 mRNAs of protein coding genes to be targeted in both human and worm. These mRNAs significantly overlapped with the RNAi pathway. We also, unexpectedly, found that mitochondrial transcripts are Dicer targets in both species. We demonstrate functional consequences of Dicer binding by perturbation analysis. Taken together,we provide the first genome-wide catalog of direct Dicer targets. Our results suggest widespread function outside of miRNA biogenesis. small RNAs were extracted from total RNA of lysed worms. Standard small RNA sequencing was performed to sequence 5' monophosphate bearing small RNAs. Alternatively, 5'polyphosphatase from Epicenter was used to catch also tri-phosphate bearing secondary endo-siRNAs.
2014-11-20 | E-GEOD-55332 | biostudies-arrayexpress
Project description:RNA silencing is a conserved mechanism in which small RNAs trigger various forms of sequence specific gene silencing by guiding Argonaute complexes to target RNAs via base-pairing. RNA silencing is thought to have evolved as a form of nucleic-acid-based immunity to inactivate viruses and transposable elements (TEs). Although the activity of TEs in animals has been thought to be largely restricted to the germline, recent studies have shown that they may also actively transpose in somatic cells, creating somatic mosaicism in animals3. In the Drosophila germline, piRNAs arise from repetitive intergenic elements including retrotransposons by a Dicer-independent pathway and function through the PIWI subfamily of Argonautes to ensure silencing of retrotransposons. Here we show that in Drosophila cultured S2 cells, Argonaute2 (AGO2), an AGO subfamily member of Argonautes, associates with endogenous small RNAs of 20-22 nucleotides in length, which we have collectively named esiRNAs (endogenous siRNAs). esiRNAs can be divided into two groups: one that mainly corresponds to a subset of retrotransposons, and the other that arises from stem-loop structures. esiRNAs are produced in a Dicer-2-dependent manner from distinctive genomic loci, are modified at their 3’ ends and can direct AGO2 to cleave target RNAs. Depletion of Dicer2 or AGO2 in S2 cells coincided with higher levels of retrotransposon transcripts. Together, our findings indicate that in Drosophila, different types of small RNAs and Argonautes are utilized to repress retrotransposons in germline and somatic cells. Keywords: AGO2, small RNA 454 sequencing - high throughput
2008-05-08 | GSE10277 | GEO
Project description:Canonical microRNAs (miRNAs) require two processing steps: the first by the Microprocessor, a complex of DGCR8 and Drosha, and the second by Dicer. dgcr8delta/delta mouse embryonic stem cells (mESCs) have less severe phenotypes than dicer1delta/delta mESCs, suggesting a physiological role for Microprocessor-independent, Dicer-dependent small RNAs. To identify these small RNAs with unusual biogenesis, we performed high-throughput sequencing from wild type, dgcr8delta/delta, and dicer1delta/delta mESCs. Several of the DGCR8-independent, Dicer-dependent RNAs were non-canonical miRNAs. These derived from mirtrons and a newly identified subclass of miRNA precursors, which appears to be the endogenous counterpart of short hairpin RNAs (shRNAs). Our analyses also revealed endogenous siRNAs resulting from Dicer cleavage of long hairpins, the vast majority of which originated from one genomic locus with tandem, inverted short interspersed nuclear elements (SINEs). Our results extend the known diversity of mammalian small-RNA generating pathways and show that mammalian siRNAs exist in tissues outside of oocytes.
2008-09-10 | GSE12521 | GEO
Project description:Canonical microRNAs (miRNAs) require two processing steps: the first by the Microprocessor, a complex of DGCR8 and Drosha, and the second by Dicer. dgcr8delta/delta mouse embryonic stem cells (mESCs) have less severe phenotypes than dicer1delta/delta mESCs, suggesting a physiological role for Microprocessor-independent, Dicer-dependent small RNAs. To identify these small RNAs with unusual biogenesis, we performed high-throughput sequencing from wild type, dgcr8delta/delta, and dicer1delta/delta mESCs. Several of the DGCR8-independent, Dicer-dependent RNAs were non-canonical miRNAs. These derived from mirtrons and a newly identified subclass of miRNA precursors, which appears to be the endogenous counterpart of short hairpin RNAs (shRNAs). Our analyses also revealed endogenous siRNAs resulting from Dicer cleavage of long hairpins, the vast majority of which originated from one genomic locus with tandem, inverted short interspersed nuclear elements (SINEs). Our results extend the known diversity of mammalian small-RNA generating pathways and show that mammalian siRNAs exist in tissues outside of oocytes. Small RNAs were sequenced from wt, dgcr8(-), and dicer(-) mouse ES cells and the frequencies of small RNA types compared between the three. This record includes Illumina-platform-generated datasets from all three samples and 454-platform-generated datasets from wt and dgcr8(-) samples. [raw data files are unavailable]
2008-09-09 | E-GEOD-12521 | biostudies-arrayexpress
Project description:Endogenous small RNAs (endo-siRNAs) interact with Argonaute (AGO) proteins to mediate sequence-specific regulation of diverse biological processes. Here, we combine deep-sequencing and genetic approaches to explore the biogenesis and function of endo-siRNAs in C. elegans. We describe conditional alleles of the dicer-related helicase, drh-3, that abrogate both RNA interference and the biogenesis of endo-siRNAs, called 22G-RNAs. DRH-3 is a core component of RNA-dependent RNA polymerase (RdRP) complexes essential for several distinct 22G-RNA systems. We show that in the germ-line, one system is dependent on worm-specific AGOs, including WAGO-1, which localizes to germ-line nuage structures called P-granules. WAGO-1 silences certain genes, transposons, pseudogenes and cryptic loci. Finally, we demonstrate that components of the nonsense-mediated decay pathway function in at least one WAGO-mediated surveillance pathway. These findings broaden our understanding of the biogenesis and diversity of 22G-RNAs and suggest novel regulatory functions for small RNAs.
2009-10-01 | GSE18230 | GEO
Project description:Non-canonical microRNAs (miRNAs) and endogenous small interfering RNAs (siRNAs) are distinct subclasses of small RNAs that bypass the DGCR8/Drosha Microprocessor but still require Dicer for their biogenesis. What, if any, role they have in mammals remains unknown. To identify potential roles for these Microprocessor-independent, Dicer-dependent small RNAs, we compared the phenotypes resulting from conditional deletion of dgcr8 versus dicer in post-mitotic neurons. Loss of dicer resulted in an earlier lethality, more severe structural abnormalities, and increased apoptosis relative to dgcr8 loss. Deep sequencing of small RNAs from the hippocampus and cortex of the conditional knockouts and control littermates identified multiple novel non-canonical microRNAs including new mirtrons H/ACA box snoRNA-derived small RNAs, and a previously unidentified mammalian subclass derived from C/D box snoRNAs. These non-canonical miRNAs were expressed at high levels in the brain relative to other tissues. In contrast, we found no evidence for endo-siRNAs in the brain. Taken together, our findings provide evidence for a diverse population of highly expressed non-canonical miRNAs that together play important functional roles in post-mitotic neurons. Examination of small RNA populations in the hippocampus and cortex of 2 conditional knockout and control littermates
2011-03-23 | E-GEOD-21090 | biostudies-arrayexpress
Project description:The endoribonuclease Dicer is known for its central role in the biogenesis of eukaryotic small RNAs/microRNAs. Despite its importance, Dicer target transcripts have not been directly mapped. Here, we apply biochemical methods to human cells and C. elegans and identify thousands of Dicer binding sites. We find known and hundreds of novel miRNAs with high sensitivity and specificity. We also report structural RNAs, promoter RNAs, and mitochondrial transcripts as Dicer targets. Interestingly, most Dicer binding sites reside on mRNAs/lncRNAs and are not significantly processed into small RNAs. These passive sites typically harbor small, Dicer-bound hairpins within intact transcripts and generally stabilize target expression. We show that passive sites can sequester Dicer and reduce microRNA expression. mRNAs with passive sites were in human and worm significantly associated with processing-body/granule function. Together, we provide the first transcriptome-wide map of Dicer targets and suggest conserved binding modes and functions outside the miRNA pathway. small RNAs were extracted from total RNA. Standard small RNA sequencing was performed to sequence 5' monophosphate bearing small RNAs. This was performed for siRNA knockdowns of DICER1 or DROSHA, with two independent siRNAs each, and for control cells. (5 samples in total)
2014-11-20 | E-GEOD-63458 | biostudies-arrayexpress
Project description:Non-canonical microRNAs (miRNAs) and endogenous small interfering RNAs (siRNAs) are distinct subclasses of small RNAs that bypass the DGCR8/Drosha Microprocessor but still require Dicer for their biogenesis. What, if any, role they have in mammals remains unknown. To identify potential roles for these Microprocessor-independent, Dicer-dependent small RNAs, we compared the phenotypes resulting from conditional deletion of dgcr8 versus dicer in post-mitotic neurons. Loss of dicer resulted in an earlier lethality, more severe structural abnormalities, and increased apoptosis relative to dgcr8 loss. Deep sequencing of small RNAs from the hippocampus and cortex of the conditional knockouts and control littermates identified multiple novel non-canonical microRNAs including new mirtrons H/ACA box snoRNA-derived small RNAs, and a previously unidentified mammalian subclass derived from C/D box snoRNAs. These non-canonical miRNAs were expressed at high levels in the brain relative to other tissues. In contrast, we found no evidence for endo-siRNAs in the brain. Taken together, our findings provide evidence for a diverse population of highly expressed non-canonical miRNAs that together play important functional roles in post-mitotic neurons.
2011-03-23 | GSE21090 | GEO
Project description:The endoribonuclease Dicer is known for its central role in the biogenesis of eukaryotic small RNAs/microRNAs. Despite its importance, Dicer target transcripts have not been directly mapped. Here, we apply biochemical methods to human cells and C. elegans and identify thousands of Dicer binding sites. We find known and hundreds of novel miRNAs with high sensitivity and specificity. We also report structural RNAs, promoter RNAs, and mitochondrial transcripts as Dicer targets. Interestingly, most Dicer binding sites reside on mRNAs/lncRNAs and are not significantly processed into small RNAs. These passive sites typically harbor small, Dicer-bound hairpins within intact transcripts and generally stabilize target expression. We show that passive sites can sequester Dicer and reduce microRNA expression. mRNAs with passive sites were in human and worm significantly associated with processing-body/granule function. Together, we provide the first transcriptome-wide map of Dicer targets and suggest conserved binding modes and functions outside the miRNA pathway. Regulatory impact of Dicer binding was assessed by knock down experiments in human HEK293 cells. Drosha knockdown and mock transfections were used as controls. Knockdown was performed with two independent siRNAs each. In total 5 samples.
2014-11-20 | E-GEOD-63475 | biostudies-arrayexpress