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Differential RISC association of endogenous human microRNAs predicts their inhibitory potential

ABSTRACT: It has previously been assumed that the generally high stability of microRNAs (miRNAs) reflects their tight association with Argonaute (Ago) proteins, essential components of the RNA-induced silencing complex (RISC). However, recent data have suggested that the majority of mature miRNAs are not, in fact, Ago associated. Here, we demonstrate that endogenous human miRNAs vary widely, by >100-fold, in their level of RISC association and show that the level of Ago binding is a better indicator of inhibitory potential than is the total level of miRNA expression. While miRNAs of closely similar sequence showed comparable levels of RISC association in the same cell line, these varied between different cell types. Moreover, the level of RISC association could be modulated by overexpression of complementary target mRNAs. Together, these data indicate that the level of RISC association of a given endogenous miRNA is regulated by the available RNA targetome and predicts miRNA function.

ORGANISM(S): Homo sapiens

PROVIDER: GSE58127 | GEO | 2014/05/30

SECONDARY ACCESSION(S): PRJNA249069

REPOSITORIES: GEO

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Differential RISC association of endogenous human microRNAs predicts their inhibitory potential

Project description:It has previously been assumed that the generally high stability of microRNAs (miRNAs) reflects their tight association with Argonaute (Ago) proteins, essential components of the RNA-induced silencing complex (RISC). However, recent data have suggested that the majority of mature miRNAs are not, in fact, Ago associated. Here, we demonstrate that endogenous human miRNAs vary widely, by >100-fold, in their level of RISC association and show that the level of Ago binding is a better indicator of inhibitory potential than is the total level of miRNA expression. While miRNAs of closely similar sequence showed comparable levels of RISC association in the same cell line, these varied between different cell types. Moreover, the level of RISC association could be modulated by overexpression of complementary target mRNAs. Together, these data indicate that the level of RISC association of a given endogenous miRNA is regulated by the available RNA targetome and predicts miRNA function. This series includes microRNA sequencing data for human cell lines 293, C8166, A549, SH-SY5Y, and an EBV-transformed LCL line. For each cell line, total small RNA isolated by TRIzol was sequenced for comparison to RISC-associated microRNAs as determined by sequencing small RNAs from an Argonaute immunoprecipitation.

2014-05-30 | E-GEOD-58127 | biostudies-arrayexpress

Slicing-Independent RISC Activation Requires the Argonaute PAZ Domain

Project description:Small RNAs regulate the genetic networks through a ribonucleoprotein complex called the RNA induced silencing complexes (RISC), which in mammals contains at its center one of four Argonaute proteins (Ago1-4). A key regulatory event in the RNAi and miRNA pathways is Ago loading, where double stranded small RNA duplexes are incorporated into RISC (pre-RISC) and then become single stranded (mature-RISC), a process that is not well understood. The Agos contain an evolutionary conserved PAZ (Piwi/Argonaute/Zwille) domain whose primary function is to bind the 3’-end of small RNAs. We created multiple Paz domain disrupted Ago mutant proteins and studied their biochemical properties and biological functionality in cells. We found that the Paz domain is dispensable for Ago loading of slicing-competent RISC. In contrast, in the absence of slicer activity or slicer substrate duplex RNAs, Paz-disrupted Agos bound duplex siRNAs but were unable to unwind/eject the passenger strand and form functional RISC complexes. We have discovered that the highly conserved Paz domain plays an important role in RISC activation, providing new mechanistic insights into how miRNAs regulate genes, as well as new insights for future design of miRNA and RNAi-based therapeutics.

2012-07-12 | GSE39146 | GEO

The distribution of individual miRNA species between high-molecular weight and low-molecular weight RISC complexes by small RNA sequencing in thyroid cancer cell lines

Project description:Thyroid cancer is the most prevalent malignancy of the endocrine system. We and others have shown that several microRNAs, which are ~21-24nt post-transcriptional gene regulators, are aberrantly expressed in anaplastic thyroid cancer (ATC) and papillary thyroid cancer (PTC) tissues and cell lines. In the cell, miRNAs are bound to Argonaute (AGO) proteins as low molecular weight RNA Induced Silencing Complexes (LMW-RISCs) that can then assemble into high molecular weight RISCs (HMW-RISCs) that also include additional proteins and mRNA. In this study, we sought to analyze the association of miRNAs across RISC complexity in ATC and PTC. For both ATC and PTC lines, miRNAs were enriched in HMW-RISC and LMW-RISC fractions compared with intermediate fractions or very low molecular weight (AGO-poor) fractions. Furthermore, 60% of all miRNAs were more abundant in LMW-RISC versus HMW- RISC fractions by ~2-4 fold. Surprisingly, miR-21-5p, one of the most abundant miRNAs in both ATC and PTC lines, was consistently one the least abundant miRNAs in HMW-RISC and the most enriched miRNA in LMW-RISC fractions. These findings suggest that miR-21 may be uniquely distributed in RISCs relative to other miRNAs. Furthermore, the methodology described here is a useful way to assess the relative magnitude of miR-21association with HMW and LMW-RISCs and may help to reveal the true roles of this miRNA in thyroid cancer development, progression, and treatment.

2020-02-28 | GSE146015 | GEO

Slicing-Independent RISC Activation Requires the Argonaute PAZ Domain

2012-07-12 | E-GEOD-39146 | biostudies-arrayexpress

Dynamic Recruitment of miRNAs to their mRNA Targets in Regenerating Liver

Project description:Validation of physiologic miRNA targets has been met with significant challenges. We employed HITS-CLIP to identify which miRNAs participate in liver regeneration, and to identify their target mRNAs. miRNA recruitment to the RISC is highly dynamic, changing more than five-fold for several miRNAs. miRNA recruitment to the RISC did not correlate with changes in overall miRNA expression for these dynamically recruited miRNAs, emphasizing the necessity to determine miRNA recruitment to the RISC in order to fully assess the impact of miRNA regulation. We incorporated RNAseq quantification of total mRNA to identify expression-weighted Ago footprints, and developed a microRNA regulatory element (MRE) prediction algorithm that represents a greater than 20-fold refinement over computational methods. These high confidence MREs were used to generate candidate competing endogenous RNA (ceRNA) networks. Conclusion: HITS-CLIP analysis provide novel insights into global miRNA:mRNA relationships in the regenerating liver .

2013-04-25 | E-MTAB-1612 | biostudies-arrayexpress

The Integrator complex regulates microRNA abundance through RISC loading

Project description:MicroRNA (miRNA) homeostasis is crucial for the post-transcriptional regulation of their target genes and miRNA dysregulation has been linked to multiple diseases, including cancer. The mechanistic steps of miRNA biogenesis are well understood at molecular level1,2. Subsequent miRNA duplex loading into members of the Argonaute (Ago) protein family, representing the core of the RNA-induced silencing complex (RISC), is pivotal to miRNA-mediated gene silencing3-5. The Integrator complex has been previously identified as important regulator of RNA maturation, RNA polymerase II pause-release, and premature transcriptional termination, processes dependent on Integrator’s catalytical activity6-9. Here we report that absence of the Integrator complex leads to a global loss of mature miRNAs. By incorporating 4-Thiouridine (s4U) in nascent transcripts, we traced miRNA fate from biogenesis to stabilization and identified Integrator to be essential for proper miRNA assembly into RISC. Indeed, Integrator enhances miRNA-Ago2 interaction in vitro, which functionally translates to amplified miRNA target cleavage. These findings demonstrate for the first time cytoplasmic Integrator complex functions and stress an indirect role of Integrator in transcription regulation through modulation of miRNA abundance and stability.

2023-02-14 | GSE178127 | GEO

Identification of microRNA-668 and microRNA-489 targets by RISC immunoprecipitation

Project description:MicroRNAs inhibits their target mRNA translation by forming RISC complex. Immunoprecipitation of RISC will pull down both microRNA and their target mRNAs. To systemetically examine the potential targets of microRNA-668 and microRNA-489, HEK293 cells were overexpressed with negative control, microRNA-668, or microRNA-489 mimics. Both total RNA samples and RNA samples from RISC complex pulled down by Ago-2 immunoprecipitation were examined by RNA-seq.

2019-07-27 | GSE117805 | GEO

Farnesylated Heat Shock Protein 40 is a component of membrane-bound RISC in Arabidopsis

Project description:ARGONAUTE1 (AGO1) binds directly to small regulatory RNA and is a key effector protein of post-transcriptional gene silencing mediated by microRNA (miRNA) and small interfering RNA (siRNA). The formation of an RNA induced silencing complex (RISC) of AGO1 and small RNA requires the function of the Heat Shock Protein 70/90 chaperone system. Some functions of AGO1 occur in association with endomembranes, in particular the rough endoplasmic reticulum (rER), but proteins interacting with AGO1 in membrane fractions remain unidentified. In this study, we show that the farnesylated Heat Shock Protein 40 homologs, J2 and J3, associate with AGO1 in membrane fractions in a manner that involves protein farnesylation. We also show that three changes in AGO1 function are detectable in mutants in protein farnesylation and J2/J3. First, perturbations of the HSP40/70/90 pathway by mutation of j3, hsp90 and farnesyl transferase affect the amounts of AGO1 associated with membranes. Second, miRNA association with membrane-bound AGO1, and with membrane-bound polysomes is increased in farnesyl transferase and farnesylationdeficient J2/J3 mutants. Third, silencing by non-cell autonomously acting short interfering RNAs (siRNAs) is impaired. These observations highlight the involvement of farnesylated J2/J3 in small RNA-mediated gene regulation, and suggest that the importance of chaperone-AGO1 interaction is not limited to the RISC assembly process.

2018-09-10 | PXD010197 | Pride

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

Casein kinase 1 and 2 phosphorylate a conserved cluster of Argonaute to control microRNA functionCasein kinase 1 and 2 phosphorylate a conserved cluster of Argonaute to control microRNA function

Project description:MicroRNAs (miRNAs) together with Argonaute (AGO) proteins form the core of the RNA-induced silencing complex (RISC) to regulate gene expression of their target RNAs post-transcriptionally. Argonaute proteins are subjected to intensive regulation via various post-translational modifications that can affect their stability, silencing efficacy and specificity for targeted gene regulation. We report here that in C. elegans, two conserved serine/threonine kinases - Casein Kinase 1 alpha 1 (CK1A1) and Casein Kinase 2 (CK2) - regulate a highly conserved phosphorylation cluster of 4 Serine residues (S988:S998) on the miRNA-specific AGO protein ALG-1. We show that CK1A1 phosphorylates ALG-1 at sites S992 and S995, while CK2 phosphorylates ALG-1 at sites S988 and S998. Furthermore, we demonstrate that phospho-mimicking mutants of the entire S988:S998 cluster rescue the various developmental defects observed upon depleting CK1A1 and CK2. In humans, we show that CK1A1 also acts as a priming kinase of this cluster on AGO2. Altogether, our data suggest that phosphorylation of AGO within the cluster by CK1A1 and CK2 is required for efficient miRISC-target RNA binding and silencing

2023-09-13 | PXD044139 | Pride

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