lncRNA1386.1/novel-miR0032-5p Axis Targets CAT Gene to Modulate Redox and Immune Reponses of Apis cerana Larvae to Ascosphaera apis Infection

Abstract

Long non-coding RNAs (lncRNAs) participate in insect immune regulation, but their relationship with antioxidant responses during fungal infection remains unclear. Here, we examined a candidate regulatory relationship among lncRNA1386.1, novel-miR0032-5p, and the catalase gene (CAT) in Apis cerana worker larvae infected with Ascosphaera apis. Dual-luciferase reporter assays showed that M-miR0032-5p reduced the activity of reporters containing the predicted miRNA response element within lncRNA1386.1 or CAT, whereas mutation of these sequences weakened or abolished the response. In infected larvae, lncRNA1386.1 silencing and novel-miR0032-5p overexpression reduced CAT transcript abundance and CAT protein concentration, and increased dihydroethidium (DHE) fluorescence intensity. These treatments were also accompanied by alterations in the transcript abundance of the host genes Dorsal1 and Relish and the fungal genes Chit3 and STE11-like. Novel-miR0032-5p inhibition generally produced opposite changes in CAT-related measurements, DHE fluorescence intensity, and the selected host and fungal transcripts. lncRNA1386.1 silencing was associated with increased larval survival, whereas novel-miR0032-5p inhibition was associated with a higher hazard of first visible external mycelial growth without significantly affecting survival. These findings support a negative regulatory role of novel-miR0032-5p in CAT expression and indicate that lncRNA1386.1 participates in a candidate shared miRNA-responsive regulatory relationship. This candidate regulatory relationship was associated with CAT-related antioxidant regulation, superoxide-associated DHE fluorescence, immune-related transcription, selected fungal transcriptional responses, and visible external mycelial growth during A. apis infection.