Juvenile hormone regulates body size and perturbs insulin signaling in Drosophila.
The role of juvenile hormone (JH) in regulating the timing and nature of insect molts is well-established. Increasing evidence suggests that JH is also involved in regulating final insect size. Here we elucidate the developmental mechanism through which JH regulates body size in developing Drosophila larvae by genetically ablating the JH-producing organ, the corpora allata (CA). We found that larvae that lack CA pupariated at smaller sizes than control larvae due to a reduced larval growth rate. Neither the timing of the metamorphic molt nor the duration of larval growth was affected by the loss of JH. Further, we show that the effects of JH on growth rate are dependent on the forkhead box O transcription factor (FOXO), which is negatively regulated by the insulin-signaling pathway. Larvae that lacked the CA had elevated levels of FOXO activity, whereas a loss-of-function mutation of FOXO rescued the effects of CA ablation on final body size. Finally, the effect of JH on growth appears to be mediated, at least in part, via ecdysone synthesis in the prothoracic gland. These results indicate a role of JH in regulating growth rate via the ecdysone- and insulin-signaling pathways.
Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, VA 20147;Development, Evolution and the Environment Laboratory, Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal; christen@igc.gulbenkian.pt shingleton@lakeforest.edu.
Christen Kerry
CK
Mirth
Department of Zoology, Michigan State University, East Lansing, MI 48824;Van Andel Institute, Grand Rapids, MI 49503; and.
Hui Yuan
HY
Tang
Department of Zoology, Michigan State University, East Lansing, MI 48824;
Sasha C
SC
Makohon-Moore
Department of Zoology, Michigan State University, East Lansing, MI 48824;
Samy
S
Salhadar
Department of Zoology, Michigan State University, East Lansing, MI 48824;
Rewatee H
RH
Gokhale
Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, VA 20147;
Raechel D
RD
Warner
Development, Evolution and the Environment Laboratory, Instituto Gulbenkian de Ciência, 2780-156 Oeiras, Portugal;
Takashi
T
Koyama
Howard Hughes Medical Institute, Janelia Farm Research Campus, Ashburn, VA 20147;
Lynn M
LM
Riddiford
Department of Zoology, Michigan State University, East Lansing, MI 48824;Department of Biology, Lake Forest College, Lake Forest, IL 60045 christen@igc.gulbenkian.pt shingleton@lakeforest.edu.
Alexander W
AW
Shingleton
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism; D049628:Body Size / Q000235:genetics*; D003335:Corpora Allata / Q000254:growth & development / Q000502:physiology / Q000601:surgery; D003714:Denervation; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development* / Q000502:physiology*; D004440:Ecdysone / Q000096:biosynthesis / Q000378:metabolism; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007605:Juvenile Hormones / Q000096:biosynthesis / Q000378:metabolism*; D007814:Larva / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology*
D051792:Basic Helix-Loop-Helix Proteins; D029721:Drosophila Proteins; D004440:Ecdysone; D051858:Forkhead Transcription Factors; D007328:Insulin; D007605:Juvenile Hormones; C477334:FOXO protein, Drosophila; C111234:MET protein, Drosophila
developmental hormones; insect physiology; size control