title: Juvenile hormone biosynthesis in adult Blattella germanica requires nuclear receptors Seven-up and FTZ-F1.
abstract: In insects, the transition from juvenile development to the adult stage is controlled by juvenile hormone (JH) synthesized from the corpora allata (CA) glands. Whereas a JH-free period during the last juvenile instar triggers metamorphosis and the end of the growth period, the reappearance of this hormone after the imaginal molt marks the onset of reproductive adulthood. Despite the importance of such transition, the regulatory mechanism that controls it remains mostly unknown. Here, using the hemimetabolous insect Blattella germanica, we show that nuclear hormone receptors Seven-up-B (BgSvp-B) and Fushi tarazu-factor 1 (BgFTZ-F1) have essential roles in the tissue- and stage-specific activation of adult CA JH-biosynthetic activity. Both factors are highly expressed in adult CA cells. Moreover, RNAi-knockdown of either BgSvp-B or BgFTZ-F1 results in adult animals with a complete block in two critical JH-dependent reproductive processes, vitellogenesis and oogenesis. We show that this reproductive blockage is the result of a dramatic impairment of JH biosynthesis, due to the CA-specific reduction in the expression of two key JH biosynthetic enzymes, 3-hydroxy-3-methylglutaryl coenzyme A synthase-1 (BgHMG-S1) and HMG-reductase (BgHMG-R). Our findings provide insights into the regulatory mechanisms underlying the specific changes in the CA gland necessary for the proper transition to adulthood.
authors.affiliation: Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain.
authors.forename: Ferran
authors.initials: F
authors.lastname: Borras-Castells
authors.affiliation: Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain.
authors.forename: Claudia
authors.initials: C
authors.lastname: Nieva
authors.affiliation: Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Maestro
authors.affiliation: Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Maestro
authors.affiliation: Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Belles
authors.affiliation: Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) Passeig Marítim de la Barceloneta 37-49, 08003 Barcelona, Spain.
authors.forename: David
authors.initials: D
authors.lastname: Martín
mesh_terms: D000818:Animals; D020048:Blattellidae / Q000254:growth & development / Q000378:metabolism*; D049109:Cell Proliferation; D003335:Corpora Allata / Q000378:metabolism; D005260:Female; D019476:Insect Proteins / Q000378:metabolism*; D007605:Juvenile Hormones / Q000096:biosynthesis*; D020033:Protein Isoforms / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D012098:Reproduction; D054339:Steroidogenic Factor 1 / Q000378:metabolism*
chemical_list: D019476:Insect Proteins; D007605:Juvenile Hormones; D020033:Protein Isoforms; D018160:Receptors, Cytoplasmic and Nuclear; D054339:Steroidogenic Factor 1