Unknown,Transcriptomics,Genomics,Proteomics

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Unambiguous Identification of miRNA:target site Interactions by Different Types of Ligation Reactions

ABSTRACT: To exert regulatory function, miRNAs guide Argonaute (AGO) proteins to partially complementary sites on target RNAs. Crosslinking and immunoprecipitation (“re state-of-the-art to map AGO binding sites, but assigning the targeting miRNA to these sites relies on bioinformatics predictions and is therefore indirect. To directly and unambiguously identify miRNA:target site interactions, we modified our CLIP methodology in C. elegans to experimentally ligate miRNAs to their target sites. Unexpectedly, ligation reactions also occurred in absence of the exogenous ligase. Our in vivo dataset and re-analysis of published mammalian AGO-CLIP data for miRNA-chimeras yielded >17,000 miRNA:target site interactions. Analysis of interactions and extensive experimental validation of chimera-discovered targets of viral miRNAs suggest that our strategy identifies canonical, non-canonical, and non-conserved miRNA interactions. Our data suggest that ~80% of miRNA:targets have perfect or partial seed complementarity. In summary, analysis of miRNA:target chimeras enables the systematic, context-specific, in vivo discovery of miRNA interactions. In vivo PAR-CLIP basically as described previously (Jungkamp et al. 2011) using GFP-tagged ALG-1 expressing worms in L3 stage. Worm lysate was treated with RNase T1. Following immunoprecipitation and a second RNase T1 digest, it was proceeded as described in Hafner et al. 2010. For the modified iPAR-CLIP ligation samples and its control samples immuno-purified complexes were treated with PNK phospathase minus, subjected to ligation with T4 RNA ligase/no ligase added and subsequently phosphorylated with PNK. Protein purification and RNA library preparation essentially as described in Hafner et al., but with the selection of longer RNA products.

ORGANISM(S): Caenorhabditis elegans

SUBMITTER: Nikolaus Rajewsky

PROVIDER: E-GEOD-56180 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Small non-coding RNAs have emerged as key players in modulation of viral infection. A unique example is the critical dependence of hepatitis C virus (HCV) on the liver-specific microRNA (miRNA), miR-122, which has surfaced as therapeutic target. Here, we used crosslinking immunoprecipitation (CLIP) of the Argonaute (AGO) protein to characterize strengths and specificities of miRNA interactions across 15 viral genomes. Intriguingly, replication of pestiviruses, which are major threats to milk and meat industry, critically depends on cellular miR-17 and let-7 interactions with the viral 3âUTR. Like HCV, miRNA binding enhanced translation and prevented viral RNA degradation. On the cellular transcriptome, pestiviral miR-17 sequestration in vitro and ex vivo conferred reduced AGO binding and functional mRNA de-repression for miR-17 targets. These findings generalize the concept of RNA virus dependence on cellular miRNAs, highlight such interactions as therapeutic targets, and connect functional regulation of the transcriptome in primary cells to miRNA sequestration. Several subseries of analyses were performed. For each sample, subseries to which it belongs are indicated. In the âVirus AGO-CLIPâ subseries, AGO-CLIP was performed on cells infected with virus as indicated. Processed reads were aligned to the host genome (hg18 or BosTau7) and to the respective viral genome. The primary data of interest from this subseries concerns AGO binding to viral RNA, and is given as processed data file âTable S1â. In the âVirus AGO-CLIP: BVDV vs. Mockâ subseries, AGO-CLIP was performed on four replicates each of BVDV and mock infected MDBK cells. CLIP reads aligned to BosTau7 were clustered, and differential analysis was performed on binding to each cluster. In addition, differential analysis of AGO bound miRNAs was performed. The associated data is given as processed data file âTable S3 and S4â. In the âAGO-CLIP: tinyLNA-17 vs. Mockâ AGO-CLIP was performed on four replicates each of tinyLNA-17 and mock treated MDBK cells. CLIP reads aligned to BosTau7 were clustered, and differential analysis was performed on binding to each cluster. The associated data is given as processed data file âTable S5â. In the âRNA-seq: BVDV vs. Mockâ subseries, mRNA-seq was performed on two replicates each of MDBK cells infected with different biotypes of BVDV or with miR-17 seed site mutant BVDV. The latter (incl. mock controls) were trans-complemented with the corresponding mutated miR-17. Differential gene expression analysis was performed between selected conditions. The associated data is given as processed data file âTable S6â.

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Unambiguous Identification of miRNA:target site Interactions by Different Types of Ligation Reactions

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