AUTHOR=Fan Xiaoxue , Zhang Wende , Zhang Kaiyao , Zhang Jiaxin , Long Qi , Wu Ying , Zhang Kuihao , Zhu Leran , Chen Dafu , Guo Rui 

TITLE=In-depth investigation of microRNA-mediated cross-kingdom regulation between Asian honey bee and microsporidian

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.1003294

DOI=10.3389/fmicb.2022.1003294

ISSN=1664-302X

ABSTRACT=<p>Asian honey bee <italic>Apis cerana</italic> is the original host for <italic>Nosema ceranae</italic>, a unicellular fungal parasite that causes bee nosemosis throughout the world. Currently, interaction between <italic>A. cerana</italic> and <italic>N. ceranae</italic> is largely unknown. Our group previously prepared <italic>A. c. cerana</italic> workers’ midguts at 7 days post inoculation (dpi) and 10 dpi with <italic>N. ceranae</italic> spores as well as corresponding un-inoculated workers’ midguts, followed by cDNA library construction and a combination of RNAs-seq and small RNA-seq. Meanwhile, we previously prepared clean spores of <italic>N. ceranae</italic>, which were then subjected to cDNA library construction and deep sequencing. Here, based on the gained high-quality transcriptome datasets, <italic>N. ceranae</italic> differentially expressed mRNAs (DEmiRNAs) targeted by host DEmiRNAs, and <italic>A. c. cerana</italic> DEmRNAs targeted by microsporidian DEmiRNAs were deeply investigated, with a focus on targets involved in <italic>N. ceranae</italic> glycolysis/glyconeogenesis as well as virulence factors, and <italic>A. c. cerana</italic> energy metabolism and immune response. In <italic>A. c. cerana</italic> worker’s midguts at 7 (10) dpi (days post inoculation), eight (seven) up-regulated and six (two) down-regulated miRNAs were observed to target 97 (44) down-regulated and 60 (15) up-regulated <italic>N. ceranae</italic> mRNAs, respectively. Additionally, two up-regulated miRNAs (miR-60-y and miR-676-y) in host midgut at 7 dpi could target genes engaged in <italic>N. ceranae</italic> spore wall protein and glycolysis/gluconeogenesis, indicating potential host miRNA-mediated regulation of microsporidian virulence factor and energy metabolism. Meanwhile, in <italic>N. ceranae</italic> at 7 (10) dpi, 121 (110) up-regulated and 112 (104) down-regulated miRNAs were found to, respectively, target 343 (247) down-regulated and 138 (110) down-regulated mRNAs in <italic>A. c. cerana</italic> workers’ midguts. These targets in host were relevant to several crucial cellular and humoral immune pathways, such as phagasome, endocytosis, lysosomes, regulation of autophagy, and Jak–STAT signaling pathway, indicative of the involvement of <italic>N. ceranae</italic> DEmiRNAs in regulating these cellular and humoral immune pathways. In addition, <italic>N. ceranae</italic> miR-21-x was up-regulated at 7 dpi and had a target relative to oxidative phosphorylation, suggesting that miR-21-x may be used as a weapon to modulate this pivotal energy metabolism pathway. Furthermore, potential targeting relationships between two pairs of host DEmiRNAs-microsporidian DEmRNAs and two pairs of microsporidian DEmiRNAs-host DEmRNAs were validated using RT-qPCR. Our findings not only lay a foundation for exploring the molecular mechanism underlying cross-kingdom regulation between <italic>A. c. cerana</italic> workers and <italic>N. ceranae</italic>, but also offer valuable insights into Asian honey bee-microsporidian interaction.</p>