title: TGF-β signaling in insects regulates metamorphosis via juvenile hormone biosynthesis.
abstract: Although butterflies undergo a dramatic morphological transformation from larva to adult via a pupal stage (holometamorphosis), crickets undergo a metamorphosis from nymph to adult without formation of a pupa (hemimetamorphosis). Despite these differences, both processes are regulated by common mechanisms that involve 20-hydroxyecdysone (20E) and juvenile hormone (JH). JH regulates many aspects of insect physiology, such as development, reproduction, diapause, and metamorphosis. Consequently, strict regulation of JH levels is crucial throughout an insect's life cycle. However, it remains unclear how JH synthesis is regulated. Here, we report that in the corpora allata of the cricket, Gryllus bimaculatus, Myoglianin (Gb'Myo), a homolog of Drosophila Myoglianin/vertebrate GDF8/11, is involved in the down-regulation of JH production by suppressing the expression of a gene encoding JH acid O-methyltransferase, Gb'jhamt In contrast, JH production is up-regulated by Decapentaplegic (Gb'Dpp) and Glass-bottom boat/60A (Gb'Gbb) signaling that occurs as part of the transcriptional activation of Gb'jhamt Gb'Myo defines the nature of each developmental transition by regulating JH titer and the interactions between JH and 20E. When Gb'myo expression is suppressed, the activation of Gb'jhamt expression and secretion of 20E induce molting, thereby leading to the next instar before the last nymphal instar. Conversely, high Gb'myo expression induces metamorphosis during the last nymphal instar through the cessation of JH synthesis. Gb'myo also regulates final insect size. Because Myo/GDF8/11 and Dpp/bone morphogenetic protein (BMP)2/4-Gbb/BMP5-8 are conserved in both invertebrates and vertebrates, the present findings provide common regulatory mechanisms for endocrine control of animal development.
authors.affiliation: Department of Life Systems, Institute of Technology and Science, Tokushima University Graduate School, Tokushima City, Tokushima, 770-8506, Japan;
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Ishimaru
authors.affiliation: Division of Chemical and Physical Analyses, Center for Technical Support, Institute of Technology and Science, Tokushima University, Tokushima City, Tokushima, 770-8506, Japan;
authors.forename: Sayuri
authors.initials: S
authors.lastname: Tomonari
authors.affiliation: Department of Life Systems, Institute of Technology and Science, Tokushima University Graduate School, Tokushima City, Tokushima, 770-8506, Japan;
authors.forename: Yuji
authors.initials: Y
authors.lastname: Matsuoka
authors.affiliation: Center for Collaboration Among Agriculture, Industry and Commerce, Tokushima University, Tokushima City, Tokushima, 770-8506, Japan;
authors.forename: Takahito
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Center for Collaboration Among Agriculture, Industry and Commerce, Tokushima University, Tokushima City, Tokushima, 770-8506, Japan;
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Miyawaki
authors.affiliation: Department of Cytology and Histology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama City, Okayama, 700-8558, Japan;
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Bando
authors.affiliation: Department of Integrative Biology, Graduate School of Natural Science and Technology, Okayama University, Okayama City, Okayama, 700-8530, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tomioka
authors.affiliation: Department of Cytology and Histology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama City, Okayama, 700-8558, Japan;
authors.forename: Hideyo
authors.initials: H
authors.lastname: Ohuchi
authors.affiliation: Center for Collaboration Among Agriculture, Industry and Commerce, Tokushima University, Tokushima City, Tokushima, 770-8506, Japan; noji@tokushima-u.ac.jp mito.taro@tokushima-u.ac.jp.
authors.forename: Sumihare
authors.initials: S
authors.lastname: Noji
authors.affiliation: Department of Life Systems, Institute of Technology and Science, Tokushima University Graduate School, Tokushima City, Tokushima, 770-8506, Japan; noji@tokushima-u.ac.jp mito.taro@tokushima-u.ac.jp.
authors.forename: Taro
authors.initials: T
authors.lastname: Mito
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D029721:Drosophila Proteins / Q000502:physiology; D006135:Gryllidae / Q000254:growth & development*; D019476:Insect Proteins / Q000502:physiology*; D007605:Juvenile Hormones / Q000096:biosynthesis*; D008675:Metamorphosis, Biological; D034622:RNA Interference; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000737:chemistry / Q000235:genetics / Q000502:physiology*
chemical_list: D029721:Drosophila Proteins; D019476:Insect Proteins; D007605:Juvenile Hormones; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; C121965:myo protein, Drosophila
keywords: GDF8/11; Gryllus bimaculatus; RNA interference; juvenile hormone; metamorphosis