Identification and characterization of known and new miRNAs from Nicotiana tabacum and nta-miR156's predictive role in Wnt Signalling Pathway

Computational methods have driven the rapid identification of tobacco microRNAs (miRNAs) from tissue-specific sequence data and witnessed success in associating miRNAs in response to stress, pollutants, viral infection and resistance, and cigarette smoking. Although tobacco exerted medicinal properties through phytochemicals, the role of its miRNAs in regulating tobacco and human genes and related functional implications is not elucidated thoroughly. In this present study, we have identified new and homologous miRNAs using a rigorous workflow of miRNA derivation and target prediction upon a comprehensive collection of tobacco expressed sequence tags and charted its putative roles in gene regulation via inter and intraspecies relationships. Current, computational approach have identified a total of 38 mature miRNAs comprising 31 tobacco-specific miRNAs from plant homologous families, and 7 new miRNA candidates. These seven new miRNAs were studied for tobacco target gene prediction in which most of them encode innate immunity, defense mechanism, plant development, F-box/Leucine rich-repeat protein and other protein kinases. Two out of these seven miRNAs have passed the updated emphasized criteria namely nta-miR403 and nta-miR8036. Interestingly, the workflow succeeded in establishing an intraspecies relationship by distinguishing the molecular targets already known in tobacco and homologous plants. Interspecies relationship between 38 tobacco miRNAs upon human transcriptome data revealed the most significant target CCDC88c (DAPLE) with perfect seed pairing of miR-156, regulating non-canonical WNT signaling pathways in cancer progression and metastasis. These findings may add to existing knowledge of impacting canonical WNT/β-catenin pathways. These decisive findings hold a strong clue for promoting tobacco miRNAs research and outlined the prediction of conserved miRNAs and their functions in inter and intraspecies relationships.