title: The cysteine-rich region and the whey acidic protein domain are essential for anosmin-1 biological functions.
abstract: The protein anosmin-1, coded by the KAL1 gene responsible for the X-linked form of Kallmann syndrome (KS), exerts its biological effects mainly through the interaction with and signal modulation of fibroblast growth factor receptor 1 (FGFR1). We have previously shown the interaction of the third fibronectin-like type 3 (FnIII) domain and the N-terminal region of anosmin-1 with FGFR1. Here, we demonstrate that missense mutations reported in patients with KS, C172R and N267K did not alter or substantially reduce, respectively, the binding to FGFR1. These substitutions annulled the chemoattraction of the full-length protein over subventricular zone (SVZ) neuronal precursors (NPs), but they did not annul it in the N-terminal-truncated protein (A1Nt). We also show that although not essential for binding to FGFR1, the cysteine-rich (CR) region is necessary for anosmin-1 function and that FnIII.3 cannot substitute for FnIII.1 function. Truncated proteins recapitulating nonsense mutations found in KS patients did not show the chemotropic effect on SVZ NPs, suggesting that the presence behind FnIII.1 of any part of anosmin-1 produces an unstable protein incapable of action. We also identify the extracellular signal-regulated kinase 1/2 (ERK1/2) pathway as necessary for the chemotropic effect exerted by FGF2 and anosmin-1 on rat SVZ NPs.
authors.affiliation: Grupo de Neurobiología del Desarrollo-GNDe, Hospital Nacional de Parapléjicos, Toledo, Spain. pfesteban@externas.sescam.jccm.es
authors.forename: Pedro F
authors.initials: PF
authors.lastname: Esteban
authors.forename: Verónica
authors.initials: V
authors.lastname: Murcia-Belmonte
authors.forename: Diego
authors.initials: D
authors.lastname: García-González
authors.forename: Fernando
authors.initials: F
authors.lastname: de Castro
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D016326:Extracellular Matrix Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D017436:Kallmann Syndrome / Q000235:genetics / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000502:physiology; D008894:Milk Proteins / Q000737:chemistry; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D058953:Neural Stem Cells / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000737:chemistry / Q000378:metabolism*
chemical_list: C076266:ANOS1 protein, human; D016326:Extracellular Matrix Proteins; D008894:Milk Proteins; D009419:Nerve Tissue Proteins; C024471:whey acidic proteins; D051496:Receptor, Fibroblast Growth Factor, Type 1; D048049:Extracellular Signal-Regulated MAP Kinases