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Small-RNA asymmetry is directly driven by mammalian Argonautes

ABSTRACT: Asymmetric selection of single-stranded guide RNAs from double-stranded RNA (dsRNA) precursors is crucial for RNA silencing-mediated gene regulation. However, the precise mechanisms for small RNA asymmetry remain unclear, especially since asymmetric selection can still occur under depletion of putative asymmetry sensors, Drosophila R2D2 and mammalian Dicer. Here we report direct contribution of mammalian Argonaute 2 (Ago2) to microRNA (miRNA) asymmetry. Ago2 selects strands with 5´-uridine/adenosine and thermodynamically unstable 5´-ends in parallel through its two sensor regions, which contact 5´-nucleobase and 5´-phosphate(s) of the prospective guide strands, respectively. Consistently, miRNA asymmetry shows characteristic digital-analog superposed patterns reflecting 5'-end nucleotide identity and thermodynamic stability. Furthermore, we demonstrate that cancer-associated miRNA variations reprogram asymmetric selection. Finally, our study presents a model of this universal principle that will aid a comprehensive understanding of miRNA function and therapeutic reinvention of RNA silencing in precision medicine. Immunoprecipitation of WT or mutant Ago2 in mouse ES cells (Ago-null background) and small RNA sequencing

ORGANISM(S): Mus musculus

SUBMITTER: Hiroshi Suzuki

PROVIDER: E-GEOD-66022 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Small-RNA asymmetry is directly driven by mammalian Argonautes

Project description:Asymmetric selection of single-stranded guide RNAs from double-stranded RNA (dsRNA) precursors is crucial for RNA silencing-mediated gene regulation. However, the precise mechanisms for small RNA asymmetry remain unclear, especially since asymmetric selection can still occur under depletion of putative asymmetry sensors, Drosophila R2D2 and mammalian Dicer. Here we report direct contribution of mammalian Argonaute 2 (Ago2) to microRNA (miRNA) asymmetry. Ago2 selects strands with 5´-uridine/adenosine and thermodynamically unstable 5´-ends in parallel through its two sensor regions, which contact 5´-nucleobase and 5´-phosphate(s) of the prospective guide strands, respectively. Consistently, miRNA asymmetry shows characteristic digital-analog superposed patterns reflecting 5'-end nucleotide identity and thermodynamic stability. Furthermore, we demonstrate that cancer-associated miRNA variations reprogram asymmetric selection. Finally, our study presents a model of this universal principle that will aid a comprehensive understanding of miRNA function and therapeutic reinvention of RNA silencing in precision medicine.

2015-06-15 | GSE66022 | GEO

siRNA profiling of HeLa cells reveals strand-specific 5-O-methylation of siRNA duplexes controls guide strand selection and targeting specificity.

Project description:Small interfering RNAs (siRNAs) and microRNAs (miRNAs) guide catalytic sequence-specific cleavage of fully or nearly fully complementary target mRNAs or control translation and/or stability of many mRNAs that share 6-8 nucleotides (nt) of complementarity to the siRNA and miRNA 5' end. siRNA- and miRNA-containing ribonucleoprotein silencing complexes are assembled from double-stranded 21- to 23-nt RNase III processing intermediates that carry 5' phosphates and 2-nt overhangs with free 3' hydroxyl groups. Despite the structural symmetry of a duplex siRNA, the nucleotide sequence asymmetry can generate a bias for preferred loading of one of the two duplex-forming strands into the RNA-induced silencing complex (RISC). Here we show that the 5'-phosphorylation status of the siRNA strands also acts as an important determinant for strand selection. 5'-O-methylated siRNA duplexes refractory to 5' phosphorylation were examined for their biases in siRNA strand selection. Asymmetric, single methylation of siRNA duplexes reduced the occupancy of the silencing complex by the methylated strand with concomitant elimination of its off-targeting signature and enhanced off-targeting signature of the phosphorylated strand. Methylation of both siRNA strands reduced but did not completely abolish RNA silencing, without affecting strand selection relative to that of the unmodified siRNA. We conclude that asymmetric 5' modification of siRNA duplexes can be useful for controlling targeting specificity. Experiment Overall Design: For details please see: Chen PY, Weinmann L, Gaidatzis D, Pei Y, Zavolan M, Tuschl T, Meister G. RNA (2008) 14(2):263-74.

2008-06-11 | E-GEOD-10960 | biostudies-arrayexpress

Strand-specific 5'-O-methylation of siRNA duplexes controls guide strand selection and targeting specificity.

Project description:Small interfering RNAs (siRNAs) and microRNAs (miRNAs) guide catalytic sequence-specific cleavage of fully or nearly fully complementary target mRNAs or control translation and/or stability of many mRNAs that share 6-8 nucleotides (nt) of complementarity to the siRNA and miRNA 5' end. siRNA- and miRNA-containing ribonucleoprotein silencing complexes are assembled from double-stranded 21- to 23-nt RNase III processing intermediates that carry 5' phosphates and 2-nt overhangs with free 3' hydroxyl groups. Despite the structural symmetry of a duplex siRNA, the nucleotide sequence asymmetry can generate a bias for preferred loading of one of the two duplex-forming strands into the RNA-induced silencing complex (RISC). Here we show that the 5'-phosphorylation status of the siRNA strands also acts as an important determinant for strand selection. 5'-O-methylated siRNA duplexes refractory to 5' phosphorylation were examined for their biases in siRNA strand selection. Asymmetric, single methylation of siRNA duplexes reduced the occupancy of the silencing complex by the methylated strand with concomitant elimination of its off-targeting signature and enhanced off-targeting signature of the phosphorylated strand. Methylation of both siRNA strands reduced but did not completely abolish RNA silencing, without affecting strand selection relative to that of the unmodified siRNA. We conclude that asymmetric 5' modification of siRNA duplexes can be useful for controlling targeting specificity. Keywords: siRNA, transfection, chemical modification, off-targets

2008-04-02 | GSE10960 | GEO

Sorting of Drosophila small silencing RNAs partitions microRNA* strands into the RNA interference pathway

Project description:In flies, small silencing RNAs are sorted between Argonaute1 (Ago1), the central protein component of the microRNA (miRNA) pathway, and Argonaute2 (Ago2), which mediates RNA interference. Extensive double-stranded characterM-bM-^@M-^Tas is found in small interfering RNAs (siRNAs)M-bM-^@M-^Tdirects duplexes into Ago2, whereas central mismatches, like those found in miRNA/miRNA* duplexes, direct duplexes into Ago1. Central to this sorting decision is the affinity of the small RNA duplex for the Dcr-2/R2D2 heterodimer, which loads small RNAs into Ago2. Here, we show that while most Drosophila miRNAs are bound to Ago1, miRNA* strands accumulate bound to Ago2. Like siRNA loading, efficient loading of miRNA* strands in Ago2 favors duplexes with a paired central region and requires both Dcr-2 and R2D2. Those miRNA and miRNA* sequences bound to Ago2, like siRNAs diced in vivo from long double-stranded RNA, typically begin with cytidine, whereas Ago1-bound miRNA and miRNA* disproportionately begin with uridine. Consequently, some pre-miRNA generate two or more isoforms from the same side of the stem that differentially partition between Ago1 and Ago2. Our findings provide the first genome-wide test for the idea that Drosophila small RNAs are sorted between Ago1 and Ago2 according to their duplex structure and the identity of their first nucleotide. Sequencing of small RNAs (either total small RNAs or Ago1-associated small RNAs) in wild-type, dcr-2 and r2d2 mutant flies. Small RNA sequencing, Small RNAs (18-29 nt long), Size selection (18 to 30 nt).

2009-10-31 | E-GEOD-18806 | biostudies-arrayexpress

Sorting of Drosophila small silencing RNAs partitions microRNA* strands into the RNA interference pathway

Project description:In flies, small silencing RNAs are sorted between Argonaute1 (Ago1), the central protein component of the microRNA (miRNA) pathway, and Argonaute2 (Ago2), which mediates RNA interference. Extensive double-stranded character—as is found in small interfering RNAs (siRNAs)—directs duplexes into Ago2, whereas central mismatches, like those found in miRNA/miRNA* duplexes, direct duplexes into Ago1. Central to this sorting decision is the affinity of the small RNA duplex for the Dcr-2/R2D2 heterodimer, which loads small RNAs into Ago2. Here, we show that while most Drosophila miRNAs are bound to Ago1, miRNA* strands accumulate bound to Ago2. Like siRNA loading, efficient loading of miRNA* strands in Ago2 favors duplexes with a paired central region and requires both Dcr-2 and R2D2. Those miRNA and miRNA* sequences bound to Ago2, like siRNAs diced in vivo from long double-stranded RNA, typically begin with cytidine, whereas Ago1-bound miRNA and miRNA* disproportionately begin with uridine. Consequently, some pre-miRNA generate two or more isoforms from the same side of the stem that differentially partition between Ago1 and Ago2. Our findings provide the first genome-wide test for the idea that Drosophila small RNAs are sorted between Ago1 and Ago2 according to their duplex structure and the identity of their first nucleotide.

2009-10-31 | GSE18806 | GEO

A nuclear role for the Argonaute protein AGO2 in mammalian gametogenesis

Project description:The reduced sperm count observed in Ago2 cKO mice implies that AGO2 has non-redundant functions in the male germ line. Because AGO2 is a key protein in the RNA interference (RNAi) pathway, we first postulated that AGO2 loss disrupts normal transcriptional and translational dynamics of target mRNAs relevant to sperm maturation. To address this hypothesis, we took advantage of the apparently normal spermatogenesis in Ago2 cKO mice, which allowed us to purify matched meiotic and post-meiotic germ cells from Ago2 cKO and wild type controls. We examined changes in the transcriptome and proteome of these two spermatogenic stages in Ago2 cKO relative to control mice using RNA-seq and quantitative mass spectrometry (MS). To further examine if the changes in mRNA and protein levels detected in Ago2 cKO germ cells was due to a loss of regulation by the canonical AGO2-miRNA pathway, we characterized AGO2 protein interactors by AGO2 immunoprecipitation-mass spectrometry (IP-MS) in cytoplasmic and nuclear fractions of post-meiotic cells

2022-08-01 | PXD027935 | Pride

PARN mediates 3'-end trimming of Argonaute-cleaved precursor microRNAs

Project description:microRNAs (miRNAs) are typically generated as ~22-nucleotide double-stranded RNAs via processing of precursor hairpins by the RNase III enzyme Dicer, after which they are loaded into Argonaute (Ago) proteins to form RNA-induced silencing complex (RISC). However, the biogenesis of miR-451, an erythropoietic miRNA conserved in vertebrates, does not require Dicer processing. Instead, the short pre-miR-451 precursor hairpin is directly loaded into Ago, followed by cleavage of the 3' arm and trimming of the 3' end to the mature length by PARN. Here we show the in vivo activity of miR-430 Ago2-hairpin, a canonical microRNA engineered to fit the structure of miR-451 and hence become Ago2-dependent. Moreover, we test a modified miR-430 Ago2-haipin with 3x phoshorothioate bonds that impairs trimmng. Surprisingly, our data show that trimming of Ago-cleaved pre-miRNAs is not essential for target silencing, indicating that RISC is functional with miRNAs longer than 22-nucleotides. Rescue of MZdicer zebrafish mutant with the injection of trimmable and nontrimmable miR-430 Ago2 hairpins: Transcriptome of wild type, MZdicer mutant, and MZdicer mutant micoinjected with miR-430 duplex, miR-430 (Ago2-haripin), miR-430 (Ago2-haripin 3xPhosphorothioate)

2013-11-13 | E-GEOD-51036 | biostudies-arrayexpress

miRNAs associated with the different human Argonaute proteins

Project description:microRNAs (miRNAs) are small non-coding RNAs that function in literally all cellular processes. miRNAs interact with Argonaute (Ago) proteins and guide them to specific target sites located in the 3’ untranslated region (UTR) of target mRNAs leading to translational repression and deadenylation-induced mRNA degradation. Most miRNAs are processed from hairpin-structured precursors by the consecutive action of the RNase III enzymes Drosha and Dicer. However, processing of miR-451 is Dicer-independent and cleavage is mediated by the endonuclease Ago2. Here we have characterized miR-451 sequence and structure requirements for processing as well as sorting of miRNAs into different Ago proteins. Pre-miR-451 appears to be optimized for Ago2 cleavage and changes result in reduced processing. In addition, we show that the mature miR-451 only associates with Ago2 suggesting that mature miRNAs are not exchanged between different members of the Ago protein family. Based on cloning and deep sequencing of endogenous miRNAs associated with Ago1-3, we do not find evidence for miRNA sorting in human cells. However, Ago identity appears to influence the length of some miRNAs, while others remain unaffected. Examination of miRNAs associated with endogenous human Ago1-4 in HeLa cells

2013-03-29 | E-GEOD-45506 | biostudies-arrayexpress

RNA-seq of miR-CLIP double purified, miR-124/miR-132 miR-CLIP probe treated HEK293T cells and corresponding mock treated and intermediate samples

Project description:Targetome of miR-124/miR-132 was enriched in HEK293T cells, a cell line which lacks the expression of these miRNA. The targetome was captured using miR-CLIP, a transfection-based double-purification crosslinking and immunoprecipitation (CLIP) method. Therefore HEK293T cells were transfected with miR-124/miR-132 miR-CLIP probes, which are trioxsalen, biotin bis-modified pre-miRNAs. Unspecific RNA-protein and trioxsalen mediated RNA-RNA crosslinking were induced by UV-irradiation before cell lysis. Total RNA (input samples) was enriched for AGO2-bound RNA using AGO2 immunoprecipitation, by depleting non-RISC associated RNAs. A second enrichment for specific targets of the transfected miRNA is performed using magnetic streptavidin-beads. This step relies on the interaction of the biotinylated probe, on which the RNA target is crosslinked, with the beads. The method was shown to deliver high-quality miRNA targetomes of both 5p and 3p miRNAs.

2020-11-23 | E-MTAB-8517 | biostudies-arrayexpress

hsa-miR-503, hsa-miR-103, and hsa-miR-494 genome wide target profiles [RNA-Seq and RIP-Seq]

Project description:We constructed a genome wide target profile of hsa-miR-503, hsa-miR-103, and hsa-miR-494 by sequencing RNA isolated from Ago2 immunoprecipitations and total RNA samples following transfection of the respective miRNA in mature duplex form Examination of mRNA levels in HeLa cells and Ago2 immunoprecipitations from HeLa cells following miR-503, miR-103, or miR-494 mature duplex or control siRNA transfection

2015-02-04 | E-GEOD-64615 | biostudies-arrayexpress

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