title: Ganglioside inhibition of neurite outgrowth requires Nogo receptor function: identification of interaction sites and development of novel antagonists.
abstract: Gangliosides are key players in neuronal inhibition, with antibody-mediated clustering of gangliosides blocking neurite outgrowth in cultures and axonal regeneration post injury. In this study we show that the ganglioside GT1b can form a complex with the Nogo-66 receptor NgR1. The interaction is shown by analytical ultracentrifugation sedimentation and is mediated by the sialic acid moiety on GT1b, with mutations in FRG motifs on NgR1 attenuating the interaction. One FRG motif was developed into a cyclic peptide (N-AcCLQKFRGSSC-NH(2)) antagonist of GT1b, reversing the GT1b antibody inhibition of cerebellar granule cell neurite outgrowth. Interestingly, the peptide also antagonizes neurite outgrowth inhibition mediated by soluble forms of the myelin-associated glycoprotein (MAG). Structure function analysis of the peptide point to the conserved FRG triplet being the minimal functional motif, and mutations within this motif inhibit NgR1 binding to both GT1b and MAG. Finally, using gene ablation, we show that the cerebellar neuron response to GT1b antibodies and soluble MAG is indeed dependent on NgR1 function. The results suggest that gangliosides inhibit neurite outgrowth by interacting with FRG motifs in the NgR1 and that this interaction can also facilitate the binding of MAG to the NgR1. Furthermore, the results point to a rational strategy for developing novel ganglioside antagonists.
authors.affiliation: Wolfson Centre for Age-Related Diseases, King's College London, London SE1 1UL, United Kingdom.
authors.forename: Gareth
authors.initials: G
authors.lastname: Williams
authors.forename: Andrew
authors.initials: A
authors.lastname: Wood
authors.forename: Emma-Jane
authors.initials: EJ
authors.lastname: Williams
authors.forename: Ying
authors.initials: Y
authors.lastname: Gao
authors.forename: Mary L
authors.initials: ML
authors.lastname: Mercado
authors.forename: Alan
authors.initials: A
authors.lastname: Katz
authors.forename: Diane
authors.initials: D
authors.lastname: Joseph-McCarthy
authors.forename: Brian
authors.initials: B
authors.lastname: Bates
authors.forename: Huai-Ping
authors.initials: HP
authors.lastname: Ling
authors.forename: Ann
authors.initials: A
authors.lastname: Aulabaugh
authors.forename: Joe
authors.initials: J
authors.lastname: Zaccardi
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Xie
authors.forename: Menelas N
authors.initials: MN
authors.lastname: Pangalos
authors.forename: Frank S
authors.initials: FS
authors.lastname: Walsh
authors.forename: Patrick
authors.initials: P
authors.lastname: Doherty
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001665:Binding Sites; D019556:COS Cells / Q000378:metabolism; D002522:Chlorocebus aethiops; D016000:Cluster Analysis; D005732:Gangliosides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation; D009185:Myelin Proteins / Q000378:metabolism*; D019158:N-Acetylneuraminic Acid / Q000737:chemistry; D016501:Neurites / Q000378:metabolism; D000070798:Nogo Proteins
chemical_list: D005732:Gangliosides; D009185:Myelin Proteins; D000070798:Nogo Proteins; C000603199:RTN4 protein, human; C000603201:Rtn4 protein, mouse; C016481:trisialoganglioside GT1; D019158:N-Acetylneuraminic Acid