Abstract
Growing pieces of evidence show that the long noncoding RNAs (lncRNAs) as new regulators participate in the regulation of various physiological and pathological processes. The study of lncRNA in lower invertebrates is still unclear compared with that in mammals. Here, we identified a novel lncRNA, termed IRAK4-related lncRNA (IRL), as a key regulator for innate immunity in teleost fish. We find that miR-27c-3p inhibits IRAK4 expression and thus weakens the NF-κB-mediated signaling pathway. Furthermore, the Gram-negative bacterium Vibrio anguillarum and lipopolysaccharide significantly upregulated host lncRNA IRL expression. Results indicate that IRL functions as a competing endogenous RNA for miR-27c-3p to regulate protein abundance of IRAK4; thus, invading microorganisms are eliminated and immune responses are promoted. Our study also demonstrates the regulation mechanism that lncRNA IRL can competitively adsorb miRNA to regulate the miR-27c-3p/IRAK4 axis that is widespread in teleost fish.
Highlights
Innate immunity is the host’s first line of defense against the invasion of pathogenic microorganisms
We demonstrated that a Long ncRNAs (lncRNAs), named IRAK4-related lncRNA (IRL), can act as a competing endogenous RNAs (ceRNAs) for miR-27c-3p to facilitate IRAK4 expression; as a result, immune responses are modulated
Various Gramnegative bacteria have been identified as pathogens that result in high mortality in aquaculture species, especially V. anguillarum
Summary
Miichthys miiuy (50 g) was obtained from Zhoushan Fisheries Research Institute, Zhejiang Province, China. MICs were challenged with an LPS concentration of 10 μg/ml and harvested at different times for RNA extraction [33]. The scrambled control RNA sequences were 5’-UUCUCCGAACGUGUCACGUTT-3’ (sense) and 5’-ACGUGACACGUUCGG AGAATT-3’ (antisense) Both nuclear RNA and cytoplasmic RNA were extracted from MICs using the Cytoplasmic & Nuclear RNA Purification Kit (Norgen Biotek) according to the manufacturer’s instructions. The miR-27c-3p sensor was cotransfected with miR-27c-3p mimics or IRL expression plasmid into MICs. At 48 h post transfection, the cells were lysed for reporter activity. MICs were harvested after 48 h transfection and RIP assays were carried out with Magna RIP RNA-Binding Protein Immunoprecipitation Kit (Millipore) and anti-GFP antibody (Abcam) following the manufacturer’s protocol. The value of p < 0.05 was considered significant
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