title: Ecdysone promotes growth of imaginal discs through the regulation of Thor in D. melanogaster.
abstract: Animals have a determined species-specific body size that results from the combined action of hormones and signaling pathways regulating growth rate and duration. In Drosophila, the steroid hormone ecdysone controls developmental transitions, thereby regulating the duration of the growth period. Here we show that ecdysone promotes the growth of imaginal discs in mid-third instar larvae, since imaginal discs from larvae with reduced or no ecdysone synthesis are smaller than wild type due to smaller and fewer cells. We show that insulin-like peptides are produced and secreted normally in larvae with reduced ecdysone synthesis, and upstream components of insulin/insulin-like signaling are activated in their discs. Instead, ecdysone appears to regulate the growth of imaginal discs via Thor/4E-BP, a negative growth regulator downstream of the insulin/insulin-like growth factor/Tor pathways. Discs from larvae with reduced ecdysone synthesis have elevated levels of Thor, while mutations in Thor partially rescue their growth. The regulation of organ growth by ecdysone is evolutionarily conserved in hemimetabolous insects, as shown by our results obtained using Blattella germanica. In summary, our data provide new insights into the relationship between components of the insulin/insulin-like/Tor and ecdysone pathways in the control of organ growth.
authors.affiliation: CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Bizkaia, Spain.
authors.forename: Leire
authors.initials: L
authors.lastname: Herboso
authors.affiliation: Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6, 2780-156 Oeiras, Portugal.
authors.forename: Marisa M
authors.initials: MM
authors.lastname: Oliveira
authors.affiliation: CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Bizkaia, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Talamillo
authors.affiliation: CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Bizkaia, Spain.
authors.forename: Coralia
authors.initials: C
authors.lastname: Pérez
authors.affiliation: CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Bizkaia, Spain.
authors.forename: Monika
authors.initials: M
authors.lastname: González
authors.affiliation: Institute of Evolutionary Biology, CSIC-Universitat Pompeu Fabra, 08003 Barcelona, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Martín
authors.affiliation: CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Bizkaia, Spain.
authors.forename: James D
authors.initials: JD
authors.lastname: Sutherland
authors.affiliation: Lake Forest College, 555 North Sheridan Road, Lake Forest, IL 60045, USA.
authors.forename: Alexander W
authors.initials: AW
authors.lastname: Shingleton
authors.affiliation: Instituto Gulbenkian de Ciência, Rua da Quinta Grande, 6, 2780-156 Oeiras, Portugal.
authors.forename: Christen K
authors.initials: CK
authors.lastname: Mirth
authors.affiliation: CIC bioGUNE, Bizkaia Technology Park, 48160 Derio, Bizkaia, Spain.
authors.forename: Rosa
authors.initials: R
authors.lastname: Barrio
mesh_terms: D000818:Animals; D049628:Body Size / Q000502:physiology; D029721:Drosophila Proteins / Q000378:metabolism; D004331:Drosophila melanogaster / Q000254:growth & development* / Q000378:metabolism; D004440:Ecdysone / Q000378:metabolism*; D005260:Female; D060227:Imaginal Discs / Q000254:growth & development*; D007328:Insulin / Q000378:metabolism; D007814:Larva / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D013002:Somatomedins / Q000378:metabolism*
chemical_list: D029721:Drosophila Proteins; D007328:Insulin; D013002:Somatomedins; D004440:Ecdysone