title: Smads and insect hemimetabolan metamorphosis.
abstract: In contrast with Drosophila melanogaster, practically nothing is known about the involvement of the TGF-β signaling pathway in the metamorphosis of hemimetabolan insects. To partially fill this gap, we have studied the role of Smad factors in the metamorphosis of the German cockroach, Blattella germanica. In D. melanogaster, Mad is the canonical R-Smad of the BMP branch of the TGF-β signaling pathway, Smox is the canonical R-Smad of the TGF-β/Activin branch and Medea participates in both branches. In insects, metamorphosis is regulated by the MEKRE93 pathway, which starts with juvenile hormone (JH), whose signal is transduced by Methoprene-tolerant (Met), which stimulates the expression of Krüppel homolog 1 (Kr-h1) that acts to repress E93, the metamorphosis trigger. In B. germanica, metamorphosis is determined at the beginning of the sixth (final) nymphal instar (N6), when JH production ceases, the expression of Kr-h1 declines, and the transcription of E93 begins to increase. The RNAi of Mad, Smox and Medea in N6 of B. germanica reveals that the BMP branch of the TGF-β signaling pathway regulates adult ecdysis and wing extension, mainly through regulating the expression of bursicon, whereas the TGF-β/Activin branch contributes to increasing E93 and decreasing Kr-h1 at the beginning of N6, crucial for triggering adult morphogenesis, as well as to regulating the imaginal molt timing.
authors.affiliation: Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim 37, 08003 Barcelona, Spain.
authors.forename: Carolina G
authors.initials: CG
authors.lastname: Santos
authors.affiliation: Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim 37, 08003 Barcelona, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Fernandez-Nicolas
authors.affiliation: Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim 37, 08003 Barcelona, Spain. Electronic address: xavier.belles@ibe.upf-csic.es.
authors.forename: Xavier
authors.initials: X
authors.lastname: Belles
mesh_terms: D028341:Activins / Q000378:metabolism; D000818:Animals; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D003058:Cockroaches / Q000196:embryology*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster / Q000196:embryology*; D018507:Gene Expression Regulation, Developmental; D007605:Juvenile Hormones / Q000378:metabolism; D051741:Kruppel-Like Transcription Factors / Q000378:metabolism; D008675:Metamorphosis, Biological / Q000502:physiology*; D018978:Molting / Q000502:physiology*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction; D051785:Smad Proteins / Q000378:metabolism*; D051896:Smad Proteins, Receptor-Regulated / Q000235:genetics / Q000378:metabolism; D051901:Smad4 Protein / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C095837:Eip93F protein, Drosophila; D007605:Juvenile Hormones; C497242:Kr-h1 protein, Drosophila; D051741:Kruppel-Like Transcription Factors; C112506:MAD protein, Drosophila; C112504:Med protein, Drosophila; D034741:RNA, Small Interfering; D051785:Smad Proteins; D051896:Smad Proteins, Receptor-Regulated; D051901:Smad4 Protein; C115826:Smox protein, Drosophila; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D028341:Activins
keywords: Blattella; Bursicon; Insect metamorphosis; Mad; Medea; Smads; Smox