title: Juvenile hormone connects larval nutrition with target of rapamycin signaling in the mosquito Aedes aegypti.
abstract: Anautogenous mosquitoes require blood meals to promote egg development. If adequate nutrients are not obtained during larval development, the resulting "small" sized adult mosquitoes require multiple blood meals for egg development; markedly increasing host-vector contacts and the likelihood of disease transmission. Nutrient-sensitive target of rapamycin (TOR) signaling is a key signaling pathway that links elevated hemolymph amino acid levels derived from the blood meal to the expression of yolk protein precursors in the fat body. Here we report that the blood-meal-induced activation of the TOR-signaling pathway and subsequent egg maturation depends on the accumulation of adequate nutritional reserves during larval development. We have established well-nourished, "standard" mosquitoes and malnourished, "small" mosquitoes as models to address this nutrient sensitive pathway. This regulatory mechanism involves juvenile hormone (JH), which acts as a mediator of fat body competence, permitting the response to amino acids derived from the blood meal. We demonstrate that treatment with JH results in recovery of the TOR molecular machinery, Aedes aegypti cationic amino acid transporter 2 (AaiCAT2), TOR, and S6 kinase (S6K), in fat bodies of small mosquitoes, enabling them to complete their first gonotrophic cycle after a single blood meal. These findings establish a direct link between nutrient reserves and the establishment of TOR signaling in mosquitoes.
authors.affiliation: Department of Entomology and the Institute for Integrative Genome Biology, University of California, Riverside, California, Watkins Drive, CA 92521, USA.
authors.forename: Shin-Hong
authors.initials: SH
authors.lastname: Shiao
authors.forename: Immo A
authors.initials: IA
authors.lastname: Hansen
authors.forename: Jinsong
authors.initials: J
authors.lastname: Zhu
authors.forename: Douglas H
authors.initials: DH
authors.lastname: Sieglaff
authors.forename: Alexander S
authors.initials: AS
authors.lastname: Raikhel
mesh_terms: D000330:Aedes / Q000502:physiology*; D026905:Amino Acid Transport Systems / Q000378:metabolism; D000596:Amino Acids / Q000097:blood; D000824:Animal Nutritional Physiological Phenomena / Q000502:physiology*; D000818:Animals; D015153:Blotting, Western; D049628:Body Size; D004591:Electrophoresis, Polyacrylamide Gel; D005216:Fat Body / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D007605:Juvenile Hormones / Q000378:metabolism*; D007814:Larva / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D026905:Amino Acid Transport Systems; D000596:Amino Acids; D007605:Juvenile Hormones; D019869:Phosphatidylinositol 3-Kinases; D019893:Ribosomal Protein S6 Kinases