Dataset Information

Feed-forward microprocessing and splicing activities at a microRNA-containing intron.

ABSTRACT: The majority of mammalian microRNA (miRNA) genes reside within introns of protein-encoding and non-coding genes, yet the mechanisms coordinating primary transcript processing into both mature miRNA and spliced mRNA are poorly understood. Analysis of melanoma invasion suppressor miR-211 expressed from intron 6 of melastatin revealed that microprocessing of miR-211 promotes splicing of the exon 6-exon 7 junction of melastatin by a mechanism requiring the RNase III activity of Drosha. Additionally, mutations in the 5' splice site (5'SS), but not in the 3'SS, branch point, or polypyrimidine tract of intron 6 reduced miR-211 biogenesis and Drosha recruitment to intron 6, indicating that 5'SS recognition by the spliceosome promotes microprocessing of miR-211. Globally, knockdown of U1 splicing factors reduced intronic miRNA expression. Our data demonstrate novel mutually-cooperative microprocessing and splicing activities at an intronic miRNA locus and suggest that the initiation of spliceosome assembly may promote microprocessing of intronic miRNAs.

SUBMITTER: Janas MM

PROVIDER: S-EPMC3197686 | biostudies-literature | 2011 Oct

REPOSITORIES: biostudies-literature

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Feed-forward microprocessing and splicing activities at a microRNA-containing intron.

Janas Maja M MM Khaled Mehdi M Schubert Steffen S Bernstein Jacob G JG Golan David D Veguilla Rosa A RA Fisher David E DE Shomron Noam N Levy Carmit C Novina Carl D CD

PLoS genetics 20111020 10

The majority of mammalian microRNA (miRNA) genes reside within introns of protein-encoding and non-coding genes, yet the mechanisms coordinating primary transcript processing into both mature miRNA and spliced mRNA are poorly understood. Analysis of melanoma invasion suppressor miR-211 expressed from intron 6 of melastatin revealed that microprocessing of miR-211 promotes splicing of the exon 6-exon 7 junction of melastatin by a mechanism requiring the RNase III activity of Drosha. Additionally, ...[more]

PMID: 22028668

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Project description:BACKGROUND:Mutations in minor spliceosome components such as U12 snRNA (cerebellar ataxia) and U4atac snRNA (microcephalic osteodysplastic primordial dwarfism type 1 (MOPD1)) result in tissue-specific symptoms. Given that the minor spliceosome is ubiquitously expressed, we hypothesized that these restricted phenotypes might be caused by the tissue-specific regulation of the minor spliceosome targets, i.e. minor intron-containing genes (MIGs). The current model of inefficient splicing is thought to apply to the regulation of the ~?500 MIGs identified in the U12DB. However this database was created more than 10?years ago. Therefore, we first wanted to revisit the classification of minor introns in light of the most recent reference genome. We then sought to address specificity of MIG expression, minor intron retention, and alternative splicing (AS) across mouse and human tissues. RESULTS:We employed position-weight matrices to obtain a comprehensive updated list of minor introns, consisting of 722 mouse and 770 human minor introns. These can be found in the Minor Intron DataBase (MIDB). Besides identification of 99% of the minor introns found in the U12DB, we also discovered ~?150 new MIGs. We then analyzed the RNAseq data from eleven different mouse tissues, which revealed tissue-specific MIG expression and minor intron retention. Additionally, many minor introns were efficiently spliced compared to their flanking major introns. Finally, we identified several novel AS events across minor introns in both mouse and human, which were also tissue-dependent. Bioinformatics analysis revealed that several of the AS events could result in the production of novel tissue-specific proteins. Moreover, like the major introns, we found that these AS events were more prevalent in long minor introns, while retention was favoured in shorter introns. CONCLUSION:Here we show that minor intron splicing and AS across minor introns is a highly organised process that might be regulated in coordination with the major spliceosome in a tissue-specific manner. We have provided a framework to further study the impact of the minor spliceosome and the regulation of MIG expression. These findings may shed light on the mechanism underlying tissue-specific phenotypes in diseases associated with minor spliceosome inactivation. MIDB can be accessed at https://midb.pnb.uconn.edu .

Dataset Information

Feed-forward microprocessing and splicing activities at a microRNA-containing intron.

Publications

Feed-forward microprocessing and splicing activities at a microRNA-containing intron.

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