title: Rat mir-155 generated from the lncRNA Bic is 'hidden' in the alternate genomic assembly and reveals the existence of novel mammalian miRNAs and clusters.
abstract: MicroRNAs (miRNAs) are a class of small noncoding RNAs acting as post-transcriptional gene expression regulators in many physiological and pathological conditions. During the last few years, many novel mammalian miRNAs have been predicted experimentally with bioinformatics approaches and validated by next-generation sequencing. Although these strategies have prompted the discovery of several miRNAs, the total number of these genes still seems larger. Here, by exploiting the species conservation of human, mouse, and rat hairpin miRNAs, we discovered a novel rat microRNA, mir-155. We found that mature miR-155 is overexpressed in rat spleen myeloid cells treated with LPS, similarly to humans and mice. Rat mir-155 is annotated only on the alternate genome, suggesting the presence of other "hidden" miRNAs on this assembly. Therefore, we comprehensively extended the homology search also to mice and humans, finally validating 34 novel mammalian miRNAs (two in humans, five in mice, and up to 27 in rats). Surprisingly, 15 of these novel miRNAs (one for mice and 14 for rats) were found only on the alternate and not on the reference genomic assembly. To date, our findings indicate that the choice of genomic assembly, when mapping small RNA reads, is an important option that should be carefully considered, at least for these animal models. Finally, the discovery of these novel mammalian miRNA genes may contribute to a better understanding of already acquired experimental data, thereby paving the way to still unexplored investigations and to unraveling the function of miRNAs in disease models.
authors: CRS4 Bioinformatics Laboratory, Parco Scientifico e Tecnologico POLARIS, 09010 Pula, Cagliari, Italy.
authors: Paolo
authors: P
authors: Uva
authors: Letizia
authors: L
authors: Da Sacco
authors: Manuela
authors: M
authors: Del Cornò
authors: Antonella
authors: A
authors: Baldassarre
authors: Paola
authors: P
authors: Sestili
authors: Massimiliano
authors: M
authors: Orsini
authors: Alessia
authors: A
authors: Palma
authors: Sandra
authors: S
authors: Gessani
authors: Andrea
authors: A
authors: Masotti
mesh_terms: D000818:Animals; D001483:Base Sequence; D019295:Computational Biology; D016678:Genome; D023281:Genomics; D006801:Humans; D051379:Mice; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D051381:Rats; D017423:Sequence Analysis, RNA
chemical_list: C580597:MIRN155 microRNA, rat; D035683:MicroRNAs