Abstract
As microRNAs (miRNAs) are important expression regulators of coding RNA, it is important to characterize their role in the interaction between hosts and pathogens. To obtain a comprehensive understanding of the miRNA alternation in Bombyx mori (B. mori) infected with Nosema bombycis (N. bombycis), RNA sequencing and stem-loop qPCR were conducted to screen and identify the significantly differentially expressed miRNAs (DEmiRNAs). A total of 17 such miRNAs were identified in response to N. bombycis infection, among which miR6498-5p efficiently inhibited the proliferation of N. bombycis in BmE-SWU1 (BmE) cells by downregulating pyridoxal phosphate phosphatase 2 (BmPLPP2). In addition, a fluorescence in situ hybridization (FISH) assay showed that miR6498-5p was located in the cytoplasm of BmE cells, while it was not found in the schizonts of N. bombycis. Further investigation of the effect of BmPLPP2 on the proliferation of schizonts found that the positive factor BmPLPP2 could facilitate N. bombycis completing its life cycle in cells by overexpression and RNAi of BmPLPP2. Our findings offer multiple new insights into the role of miRNAs in the interaction between hosts and microsporidia.
Highlights
Microsporidia are obligate intracellular parasites that infect multiple species of invertebrates and vertebrates, including humans
To elucidate the regulatory mechanism of miRNA in response to N. bombycis infection in B. mori, we identified the DEmiRNAs in N. bombycis infected BmE cells and explored the mechanism of DEmiRNAs in the regulation of N. bombycis proliferation
The copy numbers of the N. bombycis small subunit rRNA gene in BmE cells were detected by Quantitative Polymerase Chain Reaction (qPCR) at 48 h post infection, and the results showed that 14 DEmiRNAs had various effects on the proliferation of schizonts, among which four miRNAs had a stimulative effect on N. bombycis, while the others could inhibit the proliferation of schizonts in BmE cells
Summary
Microsporidia are obligate intracellular parasites that infect multiple species of invertebrates and vertebrates, including humans. These parasites can lead to huge economic losses to sericulture, cause colony mortality in honey bees, and cause health concerns in human patients with immunodeficiency [1,2]. Microsporidia have an extremely reduced genome ranging from 2.3 to 23 Mb, indicating an extreme dependence of the parasite on the host for biochemical processes [3,4]. Transcriptomics analysis of microsporidia infection in hosts has revealed a complicated and interconnected interaction in which microRNA (miRNA) as a key gene expression regulator is involved. The functions of most miRNAs in the host-microsporidia interaction remain unclear
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