title: FGFR-ERK signaling is an essential component of tissue separation.
abstract: Formation of a constriction and tissue separation between parent and young polyp is a hallmark of the Hydra budding process and controlled by fibroblast growth factor receptor (FGFR) signaling. Appearance of a cluster of cells positive for double phosphorylated ERK (dpERK) at the late separation site indicated that the RAS/MEK/ERK pathway might be a downstream target of the Hydra Kringelchen FGFR. In fact, inhibition of ERK phosphorylation by the MEK inhibitor U0126 reversibly delayed bud detachment and prevented formation of the dpERK-positive cell cluster indicating de novo-phosphorylation of ERK at the late bud base. In functional studies, a dominant-negative Kringelchen FGFR prevented bud detachment as well as appearance of the dpERK-positive cell cluster. Ectopic expression of full length Kringelchen, on the other hand, induced a localized rearrangement of the actin cytoskeleton at sites of constriction, localized ERK-phosphorylation and autotomy of the body column. Our data suggest a model in which (i) the Hydra FGFR targets, via an unknown pathway, the actin cytoskeleton to induce a constriction and (ii) FGFR activates MEK/ERK signaling at the late separation site to allow tissue separation.
authors.affiliation: Philipps-Universität Marburg, Faculty of Biology, Morphology and Evolution of Invertebrates, D-35039 Marburg, Germany. Electronic address: ch.Hasse@web.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Hasse
authors.affiliation: Philipps-Universität Marburg, Faculty of Biology, Morphology and Evolution of Invertebrates, D-35039 Marburg, Germany. Electronic address: holzo@students.Uni-Marburg.DE.
authors.forename: Oliver
authors.initials: O
authors.lastname: Holz
authors.affiliation: Philipps-Universität Marburg, Faculty of Biology, Morphology and Evolution of Invertebrates, D-35039 Marburg, Germany. Electronic address: ellen.lange@biologie.uni-marburg.de.
authors.forename: Ellen
authors.initials: E
authors.lastname: Lange
authors.affiliation: Philipps-Universität Marburg, Faculty of Biology, Morphology and Evolution of Invertebrates, D-35039 Marburg, Germany. Electronic address: lisa.pisowodzki@t-online.de.
authors.forename: Lisa
authors.initials: L
authors.lastname: Pisowodzki
authors.affiliation: Philipps-Universität Marburg, Faculty of Biology, Morphology and Evolution of Invertebrates, D-35039 Marburg, Germany. Electronic address: rebscher@biologie.uni-marburg.de.
authors.forename: Nicole
authors.initials: N
authors.lastname: Rebscher
authors.affiliation: C719, Institut für Zoologie, Technikerstraße 25, Victor Franz Hess Haus, A-6020 Innsbruck, Austria. Electronic address: Marie-Kristin.Eder@uibk.ac.at.
authors.forename: Marie
authors.initials: M
authors.lastname: Christin Eder
authors.affiliation: C719, Institut für Zoologie, Technikerstraße 25, Victor Franz Hess Haus, A-6020 Innsbruck, Austria. Electronic address: bert.hobmayer@uibk.ac.at.
authors.forename: Bert
authors.initials: B
authors.lastname: Hobmayer
authors.affiliation: Philipps-Universität Marburg, Faculty of Biology, Morphology and Evolution of Invertebrates, D-35039 Marburg, Germany. Electronic address: Hassel@biologie.uni-marburg.de.
authors.forename: Monika
authors.initials: M
authors.lastname: Hassel
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006829:Hydra / Q000196:embryology / Q000254:growth & development / Q000378:metabolism*; D017403:In Situ Hybridization; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009024:Morphogenesis / Q000187:drug effects / Q000235:genetics; D009570:Nitriles / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011758:Pyrroles / Q000494:pharmacology; D017468:Receptors, Fibroblast Growth Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D002070:Butadienes; D004791:Enzyme Inhibitors; D009570:Nitriles; D011758:Pyrroles; D017468:Receptors, Fibroblast Growth Factor; C105686:SU 5402; C113580:U 0126; D049452:Green Fluorescent Proteins; D048049:Extracellular Signal-Regulated MAP Kinases
keywords: Actin cytoskeleton; Autotomy; Dominant-negative FGFR; Receptor tyrosine kinase