Characterization of MDA5 and microRNA-203 negatively regulates the RLR signaling pathway via targeting MDA5 in miiuy croaker

MDA5 is a member of retinoic acid-inducible gene I (RIG-I)-like receptors (RLR receptors), which may play a crucial role in the immune regulation process. Recently, microRNAs (miRNAs) have been shown to act as an important regulator in the RLRs signaling pathway. Additionally, the MDA5 gene, as a significant cytosolic pathogen recognition receptor (PRR), its characteristics and functions have been extensively investigated, while less research has been done on the mechanisms of MDA5-miRNA mediated gene regulation. In this study, the evolution and functional characterization of MDA5 from miiuy croaker (mmiMDA5) were characterized. Comparative genomic analysis demonstrated that the ascidiacea and superclass do not have the MDA5 gene in the process of evolution. MDA5 contains four structural domains: CARD, ResIII, Helicase C, and RIG-I C-RD. The MDA5 was ubiquitously expressed in all tested miiuy croaker tissues. Moreover, the expressions were significantly up-regulated after stimulation with poly (I: C), which indicated that MDA5 might be involved in the antiviral immune response. The bioinformatics predicted programs have indicated that miR-203 has a direct negative regulatory effect on MDA5 in miiuy croaker. Furthermore, the dual-luciferase reporter assay have showed that miR-203 was the direct negative regulator of MDA5 in miiuy croaker. This study is the first to demonstrate that miRNA can suppress cytokines by regulating the RLR signaling pathway in teleost fish, providing some new ideas for studying miRNA-mediated regulation of immune responses in mammals.

Automated summary

MDA5, a crucial member of RIG-I-like receptors, plays a significant role in antiviral immune response. MicroRNAs have been discovered to regulate the RLR signaling pathway, with miR-203 directly negatively regulating MDA5 in miiuy croaker. This study sheds light on miRNA-mediated regulation of immune responses and cytokine suppression in teleost fish, offering new insights for mammalian immune response studies.