The Regulatory Mechanism of MiR-122 in the Antiviral Immunity of Larimichthys crocea Kidney Cells

Larimichthys crocea is an important marine aquaculture fish in China, but its farming industry has long been threatened by viral diseases. MicroRNAs (miRNAs) are short non-coding RNAs that regulate gene expression post-transcriptionally, typically by inducing mRNA degradation or translational repression. And they have emerged as essential players in orchestrating antiviral-related cellular responses in fish. In the present study, the large yellow croaker kidney cell line (PCK) was used as an in vitro model. Through transfection of miR-122 mimics and inhibitors, combined with poly(I:C) immune stimulation, transcriptome, dual-luciferase reporter assays and qPCR validation were employed to systematically investigate the immune regulatory mechanism of miR-122. Transcriptome analysis revealed that 1995 and 1577 genes were differentially expressed after miR-122 overexpression and inhibition, respectively, and they were significantly enriched in pathways such as ECM–receptor interaction, focal adhesion, PPAR signaling, and TGF-β signaling. In these DEGs, prkci and slc40a1 were confirmed as direct target genes of miR-122 in large yellow croaker via target gene prediction and dual-luciferase reporter assays. Furthermore, miR-122 overexpression significantly inhibited poly(I:C)-induced superoxide dismutase (SOD) activity, suggesting its involvement in the regulation of oxidative stress. These results support miR-122-responsive transcriptional and redox changes in poly(I:C)-stimulated PCK cells, mediated by targeting prkci and slc40a1 and by affecting SOD-mediated redox balance. This study provides new insights into the miRNA-mediated immune regulatory network in teleosts and offers potential molecular targets for disease-resistant breeding and the development of disease prevention and control strategies in large yellow croaker.