Identification and Functional Characterization of a Novel Long Non-Coding RNA NLRP14-OT in Turbot (Scophthalmus maximus) Immune Response Against Vibrio anguillarum Infection

As an important member of non-coding RNAs, lncRNAs play a significant role in various biological processes, including regulating the immune response after bacterial infection. In this study, we identified a novel lncRNA (NLRP14-OT) in turbot (Scophthalmus maximus). As a result, NLRP14-OT was more than 2234 bp in length and was detectable in the liver, spleen, head kidney, intestine, skin, gill, muscles, blood, and brain, with the highest expression levels in the blood, followed by the spleen. To better understand the biological significance of lncRNAs in the immune system, this study performed qPCR on mucosal tissues (intestine, skin, and gill) at 0, 2, 6, 12, 24, and 48 h after Vibrio anguillarum (V. anguillarum) infection. Following infection with V. anguillarum, the expression of NLRP14-OT was significantly upregulated in the skin but significantly downregulated in the gill. Given that lncRNAs can regulate target genes through different mechanisms depending on their subcellular localization, we explored the localization of NLRP14-OT. Both RNA nucleoplasmic isolation and FISH experiments showed that NLRP14-OT was predominantly localized in the nucleus. GO and KEGG analyses indicated that NLRP14-OT was involved in several pathways related to the immune response such as the Tight junction, the Ras signaling pathway, and the Rap1 signaling pathway. Moreover, overexpression of NLRP14-OT in SMK cells significantly upregulated all tested immune genes, and this effect was further enhanced upon LPS stimulation at 6 h, suggesting a potential regulatory role for NLRP14-OT in the immune system. Meanwhile, it was found that overexpression of NLRP14-OT could activate the promoter activity of NLRP14 gene and inhibit the NF-κB activity. The above results enrich the information of lncRNAs in teleost and provide a resource base for further research on the immune function of lncRNAs.