ace-miR-182-x modulates host immunity and microsporidian proliferation through targeting MMP14 and CRQ genes in Apis...

As indispensable pollinators in nature, honey bees are of great importance for ecosystem equilibrium and agricultural development. Apis cerana cerana is a major bee species mainly reared in Asian countries, with high ecological and economic value. Nosema ceranae is a kind of fungal parasite for bees, causing a chronic disease named bee nosemosis, which results in severe losses for the worldwide apicultural industry. In this study, miR-182-x, a key microRNA identified in the midgut of A. c. cerana workers (ace-miR-182-x) challenge by N. ceranae. RT-qPCR assay was suggestive of the dynamic expression pattern of ace-miR-182-x at one - four days post inoculation (dpi) with N. ceranae. Bioinformatics analysis indicated that ace-miR-182-x targeted 300 genes. Among these, two key genes, AcMMP14 and AcCRQ, were validated experimentally utilizing dual-luciferase reporter gene assay. Overexpression of ace-miR-182-x significantly suppressed the expression of AcMMP14 and AcCRQ, upregulated the Acabaecin expression while downregulated the expression of Acapidaecin, Achymenoptaecin, and Acdefensin1. Although survival rates remained unchanged, sucrose consumption and spore load were significantly affected, indicating that ace-miR-182-x directly influenced host energy metabolism and indirectly controlled the fungal proliferation. These results elucidate the dual roles of ace-miR-182-x in the midgut of A. c. cerana worker defensing against N. ceranae, highlighting its modulation of host immune response and metabolism while influencing microsporidian gene expression. Our findings not only uncover the regulatory mechanism of ace-miR-182-x in honey bees defensing against microsporidian but also enhance our understanding of miRNA-mediated host-pathogen interactions in insects.