title: Synaptotagmin I, a molecular target for steroid hormone signaling controlling the maturation of sexual behavior in an insect.
abstract: As in vertebrates, the insect steroid hormones, especially 20-hydroxyecdysone (20E), initiate and regulate sexual behavior by acting on the central nervous system. This 20E action is, in part, triggered by transcriptional events mediated through the binding of 20E to a heterodimer comprising the ecdysone receptor (EcR) and ultraspiracle (USP). However, to date, our knowledge about this genomic steroid pathway remains incomplete. In moths, males detect female sex pheromones, eliciting stereotyped sexual behavior. In Agrotis ipsilon males, the behavioral response and the neuronal sensitivity to sex pheromone in the olfactory center, the antennal lobe (AL), increase with age. We recently showed that 20E controlled this age-dependent olfactory plasticity via the activation of an EcR/USP-dependent pathway in the AL. Here, we cloned the gene encoding A. ipsilon synaptotagmin I (AisytI), a presynaptic vesicle protein known to act as a calcium sensor in neurotransmitter release. AisytI was expressed in the AL, where its amount increased with age, whereas its knockdown inhibited the sex pheromone-oriented flight of males. 20E administration to males induced AL AisytI expression in a dose-dependent and time-dependent manner. Moreover, A. ipsilon EcR silencing caused decreases in AL AisytI expression and the behavioral response to sex pheromone. Our results show that the synaptotagmin I gene is a target gene for the genomic steroid signaling that controls the expression of insect sexual behavior by acting on central sex pheromone processing. This study thus represents a significant advance in our understanding of the steroid actions that influence neural functions, and thereby behavioral plasticity, in various organisms.
  
  
  METHODS
  The nucleotide sequence of Agrotis ipsilon synaptotagmin I is available in the DDBJ/EMBL/GenBank databases under the accession number KJ863735.
authors: Département d'Ecologie Sensorielle, UMR 1392, Institut d'Ecologie et des Sciences de l'Environnement de Paris, Université Paris VI, France.
authors: Françoise
authors: F
authors: Bozzolan
authors: Line
authors: L
authors: Duportets
authors: Denis
authors: D
authors: Limousin
authors: Marie-Anne
authors: MA
authors: Wycke
authors: Elodie
authors: E
authors: Demondion
authors: Adrien
authors: A
authors: François
authors: Antoine
authors: A
authors: Abrieux
authors: Stéphane
authors: S
authors: Debernard
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D019295:Computational Biology; D004441:Ecdysterone / Q000494:pharmacology*; D005260:Female; D008297:Male; D009036:Moths; D034741:RNA, Small Interfering / Q000235:genetics; D011987:Receptors, Steroid / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012724:Sex Attractants / Q000494:pharmacology*; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects*; D050863:Synaptotagmin I / Q000235:genetics / Q000378:metabolism*
chemical_list: D034741:RNA, Small Interfering; D011987:Receptors, Steroid; D012724:Sex Attractants; D050863:Synaptotagmin I; C055469:ecdysone receptor; D004441:Ecdysterone
keywords: insect; olfactory plasticity; sexual behavior; steroid signaling pathway; synaptotagmin I