title: Discovery of a cholecystokinin-gastrin-like signaling system in nematodes.
abstract: Members of the cholecystokinin (CCK)/gastrin family of peptides, including the arthropod sulfakinins, and their cognate receptors, play an important role in the regulation of feeding behavior and energy homeostasis. Despite many efforts after the discovery of CCK/gastrin immunoreactivity in nematodes 23 yr ago, the identity of these nematode CCK/gastrin-related peptides has remained a mystery ever since. The Caenorhabditis elegans genome contains two genes with high identity to the mammalian CCK receptors and their invertebrate counterparts, the sulfakinin receptors. By using the potential C. elegans CCK receptors as a fishing hook, we have isolated and identified two CCK-like neuropeptides encoded by neuropeptide-like protein-12 (nlp-12) as the endogenous ligands of these receptors. The neuropeptide-like protein-12 peptides have a very limited neuronal expression pattern, seem to occur in vivo in the unsulfated form, and react specifically with a human CCK-8 antibody. Both receptors and ligands share a high degree of structural similarity with their vertebrate and arthropod counterparts, and also display similar biological activities with respect to digestive enzyme secretion and fat storage. Our data indicate that the gastrin-CCK signaling system was already well established before the divergence of protostomes and deuterostomes.
authors.affiliation: Functional Genomics and Proteomics Unit, Department of Biology, Katholieke Universiteit Leuven, Naamsestraat 59, B-3000 Leuven, Belgium. Tom.Janssen@bio.kuleuven.be
authors.forename: Tom
authors.initials: T
authors.lastname: Janssen
authors.forename: Ellen
authors.initials: E
authors.lastname: Meelkop
authors.forename: Marleen
authors.initials: M
authors.lastname: Lindemans
authors.forename: Karen
authors.initials: K
authors.lastname: Verstraelen
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Husson
authors.forename: Liesbet
authors.initials: L
authors.lastname: Temmerman
authors.forename: Ronald J
authors.initials: RJ
authors.lastname: Nachman
authors.forename: Liliane
authors.initials: L
authors.lastname: Schoofs
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000235:genetics / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000235:genetics; D002766:Cholecystokinin / Q000502:physiology*; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular / Q000379:methods; D005755:Gastrins / Q000502:physiology*; D016366:Open Reading Frames; D054390:Receptors, CCR2 / Q000235:genetics; D011949:Receptors, Cholecystokinin / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D029742:Caenorhabditis elegans Proteins; D005755:Gastrins; D054390:Receptors, CCR2; D011949:Receptors, Cholecystokinin; D002766:Cholecystokinin