title: Neuronal expression of Nogo-A mRNA and protein during neurite outgrowth in the developing rat olfactory system.
abstract: The major impediments to axonal regeneration in the central nervous system are growth-inhibitory proteins present in the myelin sheath, and Nogo-A is one of the most potent inhibitors synthesized by oligodendrocytes. However, neuronal expression of Nogo-A during development suggests that it may have an additional role. The spatio-temporal regulation of both Nogo-A mRNA and protein expression was examined by in situ hybridization and immunohistochemistry in the developing rat olfactory system. During embryonic and postnatal development (from E13 to P6), Nogo-A mRNA and protein were strongly expressed by differentiating neurons in the olfactory epithelium and in the olfactory bulb. From the second postnatal week, a progressive down-regulation of both Nogo-A mRNA and protein occurred, such that only a weak expression persisted in the adult olfactory system. Using double-immunostainings in the adult olfactory epithelium, we determined that Nogo-A was preferentially expressed by immature olfactory receptor neurons extending axonal processes toward the olfactory bulb. At all developmental stages, Nogo-A protein was preferentially targeted in olfactory axons emerging from the olfactory epithelium. Using an in vitro model of olfactory axon growth, we demonstrated that, in addition to its presence along the entire axon length, Nogo-A accumulated in axonal growth cone and at axonal branching points, with a distribution similar to that of microtubule-associated proteins. Moreover, Nogo-A was transiently expressed in dendritic processes in the postnatal olfactory bulb. Together, our data suggest that, in non-pathological conditions, Nogo-A may be involved in the processes of axonal growth and dendritic modeling through the regulation of microtubule dynamics.
authors.affiliation: Laboratoire Neurosciences et Systèmes Sensoriels, CNRS-UMR 5020, Université Claude Bernard--Lyon 1, IFR19, Institut Fédératif des Neurosciences de Lyon, Lyon, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Richard
authors.forename: Nathalie
authors.initials: N
authors.lastname: Giannetti
authors.forename: Diane
authors.initials: D
authors.lastname: Saucier
authors.forename: Joëlle
authors.initials: J
authors.lastname: Sacquet
authors.forename: François
authors.initials: F
authors.lastname: Jourdan
authors.forename: Véronique
authors.initials: V
authors.lastname: Pellier-Monnin
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D004622:Embryo, Mammalian; D019922:GAP-43 Protein / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization; D009185:Myelin Proteins / Q000235:genetics* / Q000378:metabolism*; D009414:Nerve Growth Factors / Q000378:metabolism; D039842:Neural Cell Adhesion Molecule L1 / Q000235:genetics / Q000378:metabolism; D016501:Neurites / Q000502:physiology*; D009474:Neurons / Q000378:metabolism*; D000070798:Nogo Proteins; D051842:Olfactory Marker Protein / Q000235:genetics / Q000378:metabolism; D009831:Olfactory Mucosa / Q000166:cytology / Q000378:metabolism; D009833:Olfactory Pathways / Q000166:cytology* / Q000196:embryology / Q000254:growth & development; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins / Q000378:metabolism; D012794:Sialic Acids / Q000235:genetics / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism
chemical_list: D019922:GAP-43 Protein; D009185:Myelin Proteins; D009414:Nerve Growth Factors; D039842:Neural Cell Adhesion Molecule L1; D000070798:Nogo Proteins; D051842:Olfactory Marker Protein; C497599:Omp protein, rat; D012333:RNA, Messenger; C000603197:Rtn4 protein, rat; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; D012794:Sialic Acids; D014404:Tubulin; C103469:polysialyl neural cell adhesion molecule