Conserved microRNA miR-8 in fat body regulates innate immune homeostasis in Drosophila
Related Experiment Video
Updated: May 26, 2026
Enhanced Northern Blot Detection of Small RNA Species in Drosophila Melanogaster
Published on: August 21, 2014
1School of Biological Sciences, Chung-Ang University, Seoul 156-756, Republic of Korea.
Abstract:
Antimicrobial peptides (AMPs) constitute a major arm of the innate immune system across diverse organisms. In Drosophila, septic injury by microbial pathogens rapidly induces the production of the AMPs in fat body via well elucidated pathways such as Toll and IMD. However, several epithelial tissues were reported to locally express AMPs without septic injury via poorly characterized ways. Here, we report that microRNA miR-8 regulates the levels of AMPs basally expressed in Drosophila. The levels of AMPs such as Drosomycin and Diptericin are significantly increased in miR-8 null animals in non-pathogen stimulated conditions. Analysis of various larval tissues revealed that the increase of Drosomycin is fat body specific. Supporting this observation, re-introduction of miR-8 only in the fat body restored the altered AMP expression in miR-8 null flies. Although loss of miR-8 impedes PI3K in the fat body, inhibition of PI3K does not phenocopy the AMP expression of miR-8 null flies, indicating that miR-8 regulates AMP independently of PI3K. Together, our findings suggest a role of miR-8 in systemic immune homeostasis in generally non-pathogenic conditions in flies.
Insights
MicroRNA miR-8 normally controls basal levels of antimicrobial peptides (AMPs) in Drosophila. Loss of miR-8 increases AMPs, particularly in the fat body, suggesting a role in immune homeostasis.
Area of Science:
- Immunology
- Genetics
- Developmental Biology
Background:
- Antimicrobial peptides (AMPs) are key innate immune molecules induced by pathogens.
- While Toll and IMD pathways are known for AMP induction in Drosophila, basal expression in non-pathogenic conditions is less understood.
- Local AMP expression in epithelial tissues without septic injury suggests alternative regulatory mechanisms.
Purpose of the Study:
- To investigate the role of microRNA miR-8 in regulating basal antimicrobial peptide levels in Drosophila.
- To identify tissues and pathways involved in miR-8-mediated AMP regulation.
Main Methods:
- Analysis of AMP levels (Drosomycin, Diptericin) in miR-8 null Drosophila.
- Tissue-specific rescue experiments re-introducing miR-8 into the fat body.
- Investigation of the PI3K pathway's involvement in miR-8's regulatory function.
Main Results:
- miR-8 null animals exhibit significantly increased basal levels of AMPs like Drosomycin and Diptericin.
- The increase in Drosomycin is specific to the fat body.
- Restoring miR-8 in the fat body normalizes AMP expression in miR-8 null flies.
- miR-8 regulates AMPs independently of the PI3K pathway, despite affecting PI3K activity.
Conclusions:
- microRNA miR-8 plays a crucial role in maintaining basal antimicrobial peptide levels in Drosophila.
- miR-8 contributes to systemic immune homeostasis under non-pathogenic conditions.
- The regulation of AMPs by miR-8 in the fat body is independent of PI3K signaling.
Related Concept Videos
01:22MicroRNAs
01:22MicroRNAs