About this Research Topic
MicroRNAs (miRNAs) are non-coding RNAs of 20-24 nucleotides that have been identified in transcriptomes of eukaryotes two decades ago. They act as regulators of specific target genes. Target selection is mediated by the annealing of miRNAs to mRNAs (usually by imperfect base-pairing). As a consequence of the short size of miRNAs, of the tolerance to mismatches in miRNA:mRNA heteroduplex, and of the huge complexity of eukaryote transcriptomes, computational analyses identify a large set of putative targeted-mRNAs for each miRNA and suggest that miRNAs are master regulators controlling sizeable gene information networks.
Genomes of metazoans express hundreds of miRNAs, many of which display a tissue- or stage-specific expression. Dozens of miRNAs are conserved between nematodes and vertebrates. Ablation of miRNAs through deletion of enzymes involved in miRNA biogenesis has dramatic impacts demonstrating that miRNAs play fundamental roles in the viability of animals. Several studies also show that miRNAs play fundamental roles in animal adaptation to environmental changes. miRNAs therefore appear as essential regulators of gene expression in metazoans.
We want to focus our Research Topic on in vivo and ex vivo analysis of miRNA-mediated gene regulation in metazoans. Original research or review articles we would like to be submitted include:
• Exploration of the complexity and abundance of miRNAs, other ncRNAs and mRNAs. Such measurements are essential for a proper understanding of RNA:RNA interactions, keeping in mind that cell lines usually display transcriptomes highly distinct from those in tissues.
• Comprehensive descriptions of phenotypes corresponding to null or conditional mutants for miRNA-specifying genes. Articles could also address a lack of phenotype.
• Identification of miRNA-targeted mRNA repertoires. High-throughput experimental identification of miRNA-targeted mRNAs started a few years ago using the coupling of ultraviolet (UV) cross-linking, immuno-precipitation and high-throughput sequencing (HITS-CLIP and derived techniques). Such original research or review articles will document complexities of miRNA regulatory networks.
• Quantification of differences in the level of proteins encoded by predicted or experimentally-identified targets in response to miRNA expression changes. Articles could also address the lack of impact of miRNA expression changes. Those articles will enhance our knowledge about the extent of the impact of miRNA expression changes on protein synthesis. Articles reporting co-quantification of proteins and mRNAs will in particular allow to appreciate the relative importance of the mechanisms of mRNA destabilization and translation inhibition in various tissues.
• Innovative computational tools to predict miRNA-targeted mRNAs as they constitute a complementary addition to experimental methods.
Keywords: miRNA-mediated gene regulation, phenotypes of null or conditional mutants for miRNA genes, miRNA-targeted mRNA repertoires, quantification of miRNA action on mRNA and protein levels, predictive computational tools