microRNA miR-275 is indispensable for blood digestion and egg development in the mosquito Aedes aegypti

• Published in: Proceedings of the National Academy of Sciences - PNAS 2010-12, Vol.107 (52), p.22391-22398
• Main Authors: Bryant, Bart, Macdonald, Warren, Raikhel, Alexander S.
• Format: Article
• Language: English
• Subjects: Aedes - genetics; Aedes - metabolism; Aedes - physiology; Aedes aegypti; Amino Acid Sequence; Animal reproduction; Animals; Biological Sciences; Blood; Blood - metabolism; Blotting, Western; Drosophila; Ecdysterone - pharmacology; Eggs; Fat body; Fat Body - metabolism; Feeding Behavior; Female; Follicles; Gene Expression Profiling; Gene expression regulation; Gene Expression Regulation - drug effects; Hormones; Insect Proteins - genetics; Insect Proteins - metabolism; MicroRNA; MicroRNAs - genetics; MicroRNAs - metabolism; Midgut; Molecular Sequence Data; Mosquitoes; Mosquitos; Oocytes - growth & development; Oocytes - metabolism; Phenotypes; Proteins; Rats; Reverse Transcriptase Polymerase Chain Reaction; Ribonucleic acid; RNA; RNA Interference; Sequence Homology, Amino Acid; Signal Transduction; Tissue Culture Techniques; TOR Serine-Threonine Kinases - genetics; TOR Serine-Threonine Kinases - metabolism
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1016230107

The mosquito Aedes aegypti is the major vector of arboviral diseases, particularly of Dengue fever, of which there are more than 100 million cases annually. Mosquitoes, such as A. aegypti, serve as vectors for disease pathogens because they require vertebrate blood for their egg production. Pathogen transmission is tightly linked to repeated cycles of obligatory blood feeding and egg maturation. Thus, the understanding of mechanisms governing egg production is necessary to develop approaches that limit the spread of mosquito-borne diseases. Previous studies have identified critical roles of hormonal- and nutrition-based target of rapamycin (TOR) pathways in controlling blood-meal—mediated egg maturation in mosquitoes. In this work, we uncovered another essential regulator of blood-meal—activated processes, the microRNA miR-275. The depletion of this microRNA in A. aegypti females after injection of its specific antagomir resulted in severe defects in blood digestion, fluid excretion, and egg development, clearly demonstrating that miR-275 is indispensable for these physiological processes. miR-275 exhibits an expression profile that suggests its regulation by a steroid hormone, 20-hydroxyecdysone (20E). In vitro organ culture experiments demonstrated that miR-275 is induced by this hormone in the presence of amino acids, indicative of a dual regulation by 20E and TOR. This report has uncovered the critical importance of microRNAs in controlling blood-meal—activated physiological events required for completion of egg development in mosquito disease vectors.