A novel teleost microRNA regulates autophagy and NF-KB activation during bacterial infection

MicroRNAs (miRNAs) are a class of non-coding RNAs with regulatory functions in many cellular processes, including immune defense. In this study, we identified novel-m0089-3p, a novel miRNA with unknown function, in the teleost fish Japanese flounder (Paralichthys olivaceus) and investigated its immune function. Novel-m0089 -3p was found to target the autophagy-associated gene ATG7 and negatively regulate ATG7 expression via interaction with the 3' UTR of ATG7. During the infection of the bacterial pathogen Edwardsiella tarda, novel -m0089-3p expression was induced in flounder, which in turn repressed ATG7 expression. Overexpression of novel-m0089-3p or blocking ATG7 expression inhibited autophagy and promoted the intracellular replication of E. tarda. Novel-m0089-3p overexpression, as well as E. tarda infection, activated NF -KB and stimulated the expression of inflammatory cytokines. Together these results revealed an important role of novel-m0089-3p in response to bacterial infection.

Automated summary

In this study, a novel miRNA called novel-m0089-3p was discovered in Japanese flounder and its immune function was investigated. It was found that novel-m0089-3p targets the autophagy-associated gene ATG7 and negatively regulates its expression. During bacterial infection, novel-m0089-3p expression is induced, leading to repression of ATG7 expression. Overexpression of novel-m0089-3p or blocking ATG7 expression inhibits autophagy and promotes intracellular replication of the bacteria.