title: The POU factor ventral veins lacking/Drifter directs the timing of metamorphosis through ecdysteroid and juvenile hormone signaling.
abstract: Although endocrine changes are known to modulate the timing of major developmental transitions, the genetic mechanisms underlying these changes remain poorly understood. In insects, two developmental hormones, juvenile hormone (JH) and ecdysteroids, are coordinated with each other to induce developmental changes associated with metamorphosis. However, the regulation underlying the coordination of JH and ecdysteroid synthesis remains elusive. Here, we examined the function of a homolog of the vertebrate POU domain protein, Ventral veins lacking (Vvl)/Drifter, in regulating both of these hormonal pathways in the red flour beetle, Tribolium castaneum (Tenebrionidae). RNA interference-mediated silencing of vvl expression led to both precocious metamorphosis and inhibition of molting in the larva. Ectopic application of a JH analog on vvl knockdown larvae delayed the onset of metamorphosis and led to a prolonged larval stage, indicating that Vvl acts upstream of JH signaling. Accordingly, vvl knockdown also reduced the expression of a JH biosynthesis gene, JH acid methyltransferase 3 (jhamt3). In addition, ecdysone titer and the expression of the ecdysone response gene, hormone receptor 3 (HR3), were reduced in vvl knockdown larvae. The expression of the ecdysone biosynthesis gene phantom (phm) and spook (spo) were reduced in vvl knockdown larvae in the anterior and posterior halves, respectively, indicating that Vvl might influence ecdysone biosynthesis in both the prothoracic gland and additional endocrine sources. Injection of 20-hydroxyecdysone (20E) into vvl knockdown larvae could restore the expression of HR3 although molting was never restored. These findings suggest that Vvl coordinates both JH and ecdysteroid biosynthesis as well as molting behavior to influence molting and the timing of metamorphosis. Thus, in both vertebrates and insects, POU factors modulate the production of major neuroendocrine regulators during sexual maturation.
authors.affiliation: Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts, United States of America.
authors.forename: CeCe
authors.initials: C
authors.lastname: Cheng
authors.affiliation: Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts, United States of America.
authors.forename: Amy
authors.initials: A
authors.lastname: Ko
authors.affiliation: Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts, United States of America.
authors.forename: Leila
authors.initials: L
authors.lastname: Chaieb
authors.affiliation: Development, Evolution and the Environment Lab, Instituto Gulbenkian de Ciência, Oeiras, Portugal.
authors.forename: Takashi
authors.initials: T
authors.lastname: Koyama
authors.affiliation: Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts, United States of America.
authors.forename: Prioty
authors.initials: P
authors.lastname: Sarwar
authors.affiliation: Development, Evolution and the Environment Lab, Instituto Gulbenkian de Ciência, Oeiras, Portugal.
authors.forename: Christen K
authors.initials: CK
authors.lastname: Mirth
authors.affiliation: Department of Biology, Northeastern University, Boston, Massachusetts, United States of America.
authors.forename: Wendy A
authors.initials: WA
authors.lastname: Smith
authors.affiliation: Department of Biological Sciences, Wellesley College, Wellesley, Massachusetts, United States of America.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Suzuki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004441:Ecdysterone / Q000378:metabolism* / Q000494:pharmacology; D018507:Gene Expression Regulation, Developmental; D019476:Insect Proteins; D007605:Juvenile Hormones / Q000096:biosynthesis / Q000378:metabolism*; D008675:Metamorphosis, Biological / Q000235:genetics*; D008780:Methyltransferases / Q000096:biosynthesis; D006899:Mixed Function Oxygenases / Q000235:genetics; D018978:Molting / Q000187:drug effects / Q000235:genetics; D050809:POU Domain Factors / Q000235:genetics*; D034622:RNA Interference; D034741:RNA, Small Interfering; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis; D016415:Sequence Alignment; D014231:Tribolium / Q000201:enzymology / Q000235:genetics / Q000254:growth & development*
chemical_list: D004268:DNA-Binding Proteins; D019476:Insect Proteins; D007605:Juvenile Hormones; D050809:POU Domain Factors; D034741:RNA, Small Interfering; D018160:Receptors, Cytoplasmic and Nuclear; D004441:Ecdysterone; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D008780:Methyltransferases