Evidence for a role of the chemorepellent semaphorin III and its receptor neuropilin-1 in the regeneration of primary olfactory axons

R. Jeroen Pasterkamp, Fred De Winter, A. J G D Holtmaat, Joost Verhaagen*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

167 Citations (Scopus)

Abstract

To explore a role for chemorepulsive axon guidance mechanisms in the regeneration of primary olfactory axons, we examined the expression of the chemorepellent semaphorin III (sema III), its receptor neuropilin-1, and collapsin response mediator protein-2 (CRMP-2) during regeneration of the olfactory system. In the intact olfactory system, neuropilin-1 and CRMP-2 mRNA expression define a distinct population of olfactory receptor neurons, corresponding to immature (B-50/GAP-43-positive) and a subset of mature (olfactory marker protein-positive) neurons located in the lower half of the olfactory epithelium. Sema III mRNA is expressed in pial sheet cells and in second-order olfactory neurons that are the target cells of neuropilin-1- positive primary olfactory axons. These data suggest that in the intact olfactory bulb sema III creates a molecular barrier, which helps restrict ingrowing olfactory axons to the nerve and glomerular layers of the bulb. Both axotomy of the primary olfactory nerve and bulbectomy induce the formation of new olfactory receptor neurons expressing neuropilin-1 and CRMP- 2 mRNA. After axotomy, sema III mRNA is transiently induced in cells at the site of the lesion. These cells align regenerating bundles of olfactory axons. In contrast to the transient appearance of sema III-positive cells at the lesion site after axotomy, sema III-positive cells increase progressively after bulbectomy, apparently preventing regenerating neuropilin-1-positive nerve bundles from growing deeper into the lesion area. The presence of sema III in scar tissue and the concomitant expression of its receptor neuropilin- 1 on regenerating olfactory axons suggests that semaphorin-mediated chemorepulsive signal transduction may contribute to the regenerative failure of these axons after bulbectomy.

Original languageEnglish
Pages (from-to)9962-9976
Number of pages15
JournalJournal of Neuroscience
Volume18
Issue number23
Publication statusPublished - 1 Dec 1998

Keywords

  • CNS
  • CRMP
  • Neuropilin
  • Olfactory bulb
  • Olfactory receptor neuron
  • Plasticity
  • Primary olfactory system
  • Regeneration
  • Semaphorin/collapsin

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