Ecdysone promotes growth of imaginal discs through the regulation of Thor in D. melanogaster

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.Spanish Ministry of Science and Consolider program grants: (BFU-2008-01884, BFU2011-25986, CSD2007-008-25120, BFU2009-10571 and BES-2009-016077); Departments of Education and Industry of the Basque Government grant: (PI2012/42); Bizkaia County; Instituto Gulbenkian de Ciência/Fundação Calouste Gulbenkian; Fundação Para a Ciência e a Tecnologia fellowship: (SFRH/BD/51181/2010)

Contribution of ecdysone to imaginal discs growth

Herboso, Leire et al.-- Trabajo presentado en el 2nd International Insect Hormone Workshop, celebrado en Creta del 12 al 18 de julio de 2015.Animals have a determined species-specific body size, which results from the combined action of hormones and signaling pathways regulating growth rate and duration. In Drosophila, the steroid hormone ecdysone regulates 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, as imaginal discs from larvae with reduced or no ecdysone synthesis are smaller than wild type due to smaller and fewer cells. Our data provide new insights into the relationship between insulin/insulin-like/Tor and ecdysone pathways in the control of organ growth. The role of ecdysone in growth control is conserved in hemimetabolous insects.N

Control of larval organ size by the steroid hormone ecdysone

Póster presentado en la IX Meeting of the Spanish Society for Developmental Biology (SEBD), celebrada en Granada del 12 al 14 de noviembre de 2012.The last peak of 20E before pupariation promotes differentiation of larval tissues to form the adult structures of the fly. We have seen that 20E is also necessary for wing imaginal disc growth between 112 and 120 hours AEL by promoting cell growth and cell division. We are exploring these two aspects in more detail.Peer Reviewe

Steroids synthesis and growth control

Trabajo presentado en el Insect Hormones (19th Ecdysone) International Workshop, celebrado en Minneapolis del 21 al 26 de julio de 2013.The steroid hormone ecdysone is produced in the prothoracic gland (PG) of insects. There, cholesterol intake is needed as source for ecdysone synthesis. We have demonstrated that the small ubiquitin-related modifier SUMO is necessary for lipid uptake in the PG. SUMO is required for the expression of Ftz-f1, an orphan nuclear receptor, which is in turn necessary for the expression of some members of the Scavenger Receptor Class B type I (SR-BI) family. These receptors belong to the mammalian CD36 family, which participates in the selective uptake of High Density Lipoprotein cholesteryl ester and in the formation of microvillar channels in the mammalian adrenal gland. Our results show that the SR-BI Snmp1 is involved in the cholesterol uptake mediated by SUMO and Ftz-f1. Snmp1 overexpression is able to rescue the lipid capture in PGs silenced for SUMO or Ftzf1. Furthermore, the requirement of SUMO/Ftz-f1/SR-BIs for lipid capture is conserved in other tissues. The ecdysone produced in the PG has non-autonomous consequences on the growth of other larval tissues, such as the imaginal discs. Without ecdysone, imaginal discs do not reach the proper size due to a reduction in cell proliferation and cell size. These parameters are recovered when the hormone is exogenously administrated. We are investigating the factors implicated in cell growth triggered by ecdysone.N

Steroids synthesis and growth control

Póster presentado en el 23rd European Drosophila Research Congress, celebrado en Barcelona del 16 al 19 de octubre de 2013.The steroid hormone ecdysone is produced in the prothoracic gland (PG) of insects. There, cholesterol intake is needed as source for ecdysone synthesis. We have demonstrated that the small ubiquitin-related modifier SUMO is necessary for lipid uptake in the PG. SUMO is required for the expression of Ftz-f1, an orphan nuclear receptor, which is in turn necessary for the expression of some members of the Scavenger Receptor Class B type I (SR-BI) family. These receptors belong to the mammalian CD36 family, which participates in the selective uptake of High Density Lipoprotein cholesteryl ester and in the formation of microvillar channels in the mammalian adrenal gland. Our results show that the SR-BI Snmp1 is involved in the cholesterol uptake mediated by SUMO and Ftz-f1. Snmp1 overexpression is able to rescue the lipid capture in PGs silenced for SUMO or Ftzf1. Furthermore, the requirement of SUMO/Ftz-f1/SR-BIs for lipid capture is conserved in other tissues. The ecdysone produced in the PG has non-autonomous consequences on the growth of other larval tissues, such as the imaginal discs. Without ecdysone, imaginal discs do not reach the proper size due to a reduction in cell proliferation and cell size. These parameters are recovered when the hormone is exogenously administrated. We are investigating the factors implicated in cell growth triggered by ecdysone.Peer Reviewe

The steroid homone ecdysone promotes growth of imagianl discs in drosophila melanogaster

Trabajo presentado en la X Meeting Society for Developmental Biology, celebrada en Madrid del 13 al 15 de octubre de 2014.Peer Reviewe

Regulation of Drosophila hematopoietic sites by Activin-β from active sensory neurons

An outstanding question in animal development, tissue homeostasis and disease is how cell populations adapt to sensory inputs. During Drosophila larval development, hematopoietic sites are in direct contact with sensory neuron clusters of the peripheral nervous system (PNS), and blood cells (hemocytes) require the PNS for their survival and recruitment to these microenvironments, known as Hematopoietic Pockets. Here we report that Activin-β, a TGF-β family ligand, is expressed by sensory neurons of the PNS and regulates the proliferation and adhesion of hemocytes. These hemocyte responses depend on PNS activity, as shown by agonist treatment and transient silencing of sensory neurons. Activin-β has a key role in this regulation, which is apparent from reporter expression and mutant analyses. This mechanism of local sensory neurons controlling blood cell adaptation invites evolutionary parallels with vertebrate hematopoietic progenitors and the independent myeloid system of tissue macrophages, whose regulation by local microenvironments remain undefined