title: Glial cell line-derived neurotrophic factor (GDNF) induces neuritogenesis in the cochlear spiral ganglion via neural cell adhesion molecule (NCAM).
abstract: Glial cell line-derived neurotrophic factor (GDNF) increases survival and neurite extension of spiral ganglion neurons (SGNs), the primary neurons of the auditory system, via yet unknown signaling mechanisms. In other cell types, signaling is achieved by the GPI-linked GDNF family receptor α1 (GFRα1) via recruitment of transmembrane receptors: Ret (re-arranged during transformation) and/or NCAM (neural cell adhesion molecule). Here we show that GDNF enhances neuritogenesis in organotypic cultures of spiral ganglia from 5-day-old rats and mice. Addition of GFRα1-Fc increases this effect. GDNF/GFRα1-Fc stimulation activates intracellular PI3K/Akt and MEK/Erk signaling cascades as detected by Western blot analysis of cultures prepared from rats at postnatal days 5 (P5, before the onset of hearing) and 20 (P20, after the onset of hearing). Both cascades mediate GDNF stimulation of neuritogenesis, since application of the Akt inhibitor Wortmannin or the Erk inhibitor U0126 abolished GDNF/GFRα1-Fc stimulated neuritogenesis in P5 rats. Since cultures of P5 NCAM-deficient mice failed to respond by neuritogenesis to GDNF/GFRα1-Fc, we conclude that NCAM serves as a receptor for GDNF signaling responsible for neuritogenesis in early postnatal spiral ganglion.
authors.affiliation: Department of Surgery/Otolaryngology, University of California San Diego, School of Medicine, 9500 Gilman Drive #0666, La Jolla, CA 92093-0666, USA. sara.euteneuer@med.uni-heidelberg.de
authors.forename: Sara
authors.initials: S
authors.lastname: Euteneuer
authors.forename: Kuo H
authors.initials: KH
authors.lastname: Yang
authors.forename: Eduardo
authors.initials: E
authors.lastname: Chavez
authors.forename: Anke
authors.initials: A
authors.lastname: Leichtle
authors.forename: Gabriele
authors.initials: G
authors.lastname: Loers
authors.forename: Adel
authors.initials: A
authors.lastname: Olshansky
authors.forename: Kwang
authors.initials: K
authors.lastname: Pak
authors.forename: Melitta
authors.initials: M
authors.lastname: Schachner
authors.forename: Allen F
authors.initials: AF
authors.lastname: Ryan
mesh_terms: D000818:Animals; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000494:pharmacology*; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors / Q000378:metabolism; D066298:In Vitro Techniques; D020935:MAP Kinase Signaling System; D051379:Mice; D008822:Mice, Transgenic; D019006:Neural Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D016501:Neurites / Q000378:metabolism*; D055495:Neurogenesis / Q000187:drug effects; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013136:Spiral Ganglion / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism
chemical_list: D051100:Glial Cell Line-Derived Neurotrophic Factor; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D019006:Neural Cell Adhesion Molecules; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D048049:Extracellular Signal-Regulated MAP Kinases