ame-miR-34 Modulates the Larval Body Weight and Immune Response of <i>Apis mellifera</i> Workers to <i>Ascosphara apis</i> Invasion
MiRNAs are critical regulators of numerous physiological and pathological processes. <i>Ascosphaera apis</i> exclusively infects bee larvae and causes chalkbrood disease. However, the function and mechanism of miRNAs in the bee larval response to <i>A. apis</i> infection is p...
| Main Authors: | , , , , , , , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2023-01-01
|
| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/24/2/1214 |
| Summary: | MiRNAs are critical regulators of numerous physiological and pathological processes. <i>Ascosphaera apis</i> exclusively infects bee larvae and causes chalkbrood disease. However, the function and mechanism of miRNAs in the bee larval response to <i>A. apis</i> infection is poorly understood. Here, ame-miR-34, a previously predicted miRNA involved in the response of <i>Apis mellifera</i> larvae to <i>A. apis</i> invasion, was subjected to molecular validation, and overexpression and knockdown were then conducted to explore the regulatory functions of ame-miR-34 in larval body weight and immune response. Stem-loop RT-PCR and Sanger sequencing confirmed the authenticity of ame-miR-34 in the larval gut of <i>A. mellifera</i>. RT-qPCR results demonstrated that compared with that in the uninfected larval guts, the expression level of ame-miR-34 was significantly downregulated (<i>p</i> < 0.001) in the guts of <i>A. apis</i>-infected 4-, 5-, and 6-day-old larvae, indicative of the remarkable suppression of host ame-miR-34 due to <i>A. apis</i> infection. In comparison with the corresponding negative control (NC) groups, the expression level of ame-miR-34 in the larval guts in the mimic-miR-34 group was significantly upregulated (<i>p</i> < 0.001), while that in the inhibitor-miR-34 group was significantly downregulated (<i>p</i> < 0.01). Similarly, effective overexpression and knockdown of ame-miR-34 were achieved. In addition, the body weights of 5- and 6-day-old larvae were significantly increased compared with those in the mimic-NC group; the weights of 5-day-old larvae in the inhibitor-miR-34 group were significantly decreased in comparison with those in the inhibitor-NC group, while the weights of 4- and 6-day-old larvae in the inhibitor-miR-34 group were significantly increased, indicating the involvement of ame-miR-34 in modulating larval body weight. Furthermore, the expression levels of both <i>hsp</i> and <i>abct</i> in the guts of <i>A. apis</i>-infected 4-, 5-, and 6-day-old larvae were significantly upregulated after ame-miR-34 overexpression. In contrast, after ame-miR-34 knockdown, the expression levels of the aforementioned two key genes in the <i>A. apis</i>-infected 4-, 5-, and 6-day-old larval guts were significantly downregulated. Together, the results demonstrated that effective overexpression and knockdown of ame-miR-34 in both noninfected and <i>A. apis</i>-infected <i>A. mellifera</i> larval guts could be achieved by the feeding method, and ame-miR-34 exerted a regulatory function in the host immune response to <i>A. apis</i> invasion through positive regulation of the expression of <i>hsp</i> and <i>abct</i>. Our findings not only provide a valuable reference for the functional investigation of bee larval miRNAs but also reveal the regulatory role of ame-miR-34 in <i>A. mellifera</i> larval weight and immune response. Additionally, the results of this study may provide a promising molecular target for the treatment of chalkbrood disease. |
|---|---|
| ISSN: | 1661-6596 1422-0067 |