title: The Splice Isoforms of the Drosophila Ecdysis Triggering Hormone Receptor Have Developmentally Distinct Roles.
abstract: To grow, insects must periodically shed their exoskeletons. This process, called ecdysis, is initiated by the endocrine release of Ecdysis Trigger Hormone (ETH) and has been extensively studied as a model for understanding the hormonal control of behavior. Understanding how ETH regulates ecdysis behavior, however, has been impeded by limited knowledge of the hormone's neuronal targets. An alternatively spliced gene encoding a G-protein-coupled receptor (ETHR) that is activated by ETH has been identified, and several lines of evidence support a role in ecdysis for its A-isoform. The function of a second ETHR isoform (ETHRB) remains unknown. Here we use the recently introduced "Trojan exon" technique to simultaneously mutate the ETHR gene and gain genetic access to the neurons that express its two isoforms. We show that ETHRA and ETHRB are expressed in largely distinct subsets of neurons and that ETHRA- but not ETHRB-expressing neurons are required for ecdysis at all developmental stages. However, both genetic and neuronal manipulations indicate an essential role for ETHRB at pupal and adult, but not larval, ecdysis. We also identify several functionally important subsets of ETHR-expressing neurons including one that coexpresses the peptide Leucokinin and regulates fluid balance to facilitate ecdysis at the pupal stage. The general strategy presented here of using a receptor gene as an entry point for genetic and neuronal manipulations should be useful in establishing patterns of functional connectivity in other hormonally regulated networks.
authors.affiliation: Laboratory of Molecular Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: Feici
authors.initials: F
authors.lastname: Diao
authors.affiliation: Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Playa Ancha, Valparaiso, Chile.
authors.forename: Wilson
authors.initials: W
authors.lastname: Mena
authors.affiliation: Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri 63110.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Shi
authors.affiliation: Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri 63110.
authors.forename: Dongkook
authors.initials: D
authors.lastname: Park
authors.affiliation: Laboratory of Molecular Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892.
authors.forename: Fengqiu
authors.initials: F
authors.lastname: Diao
authors.affiliation: Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, Missouri 63110.
authors.forename: Paul
authors.initials: P
authors.lastname: Taghert
authors.affiliation: Centro Interdisciplinario de Neurociencia, Universidad de Valparaiso, Playa Ancha, Valparaiso, Chile.
authors.forename: John
authors.initials: J
authors.lastname: Ewer
authors.affiliation: Laboratory of Molecular Biology, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892 benjaminwhite@mail.nih.gov.
authors.forename: Benjamin H
authors.initials: BH
authors.lastname: White
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D004331:Drosophila melanogaster / Q000196:embryology*; D005260:Female; D007301:Insect Hormones / Q000502:physiology; D008297:Male; D018978:Molting / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D020033:Protein Isoforms / Q000502:physiology; D011679:Pupa / Q000502:physiology; D018000:Receptors, Peptide / Q000235:genetics / Q000502:physiology*
chemical_list: D007301:Insect Hormones; D020033:Protein Isoforms; D018000:Receptors, Peptide; C474803:ecdysis-triggering hormone receptor, Drosophila; C403307:ecdysis-triggering hormone, Drosophila
keywords: behavior; ecdysis; hormones; neural circuit; transgene targeting