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Article Dans Une Revue Brain Structure and Function Année : 2014

In vivo assembly of the axon initial segment in motor neurons

Barbara Le Bras
  • Fonction : Auteur
Amelie Freal
  • Fonction : Auteur
Antonny Czarnecki
  • Fonction : Auteur
Erika Bullier
  • Fonction : Auteur
Masayuki Komada
  • Fonction : Auteur
Peter J. Brophy
  • Fonction : Auteur
Marc Davenne
  • Fonction : Auteur
Francois Couraud
  • Fonction : Auteur

Résumé

The axon initial segment (AIS) is responsible for both the modulation of action potentials and the maintenance of neuronal polarity. Yet, the molecular mechanisms controlling its assembly are incompletely understood. Our study in single electroporated motor neurons in mouse embryos revealed that AnkyrinG (AnkG), the AIS master organizer, is undetectable in bipolar migrating motor neurons, but is already expressed at the beginning of axonogenesis at E9.5 and initially distributed homogeneously along the entire growing axon. Then, from E11.5, a stage when AnkG is already apposed to the membrane, as observed by electron microscopy, the protein progressively becomes restricted to the proximal axon. Analysis on the global motor neurons population indicated that Neurofascin follows an identical spatio-temporal distribution, whereas sodium channels and beta 4-spectrin only appear along AnkG(+) segments at E11.5. Early patch-clamp recordings of individual motor neurons indicated that at E12.5 these nascent AISs are already able to generate spikes. Using knock-out mice, we demonstrated that neither beta 4-spectrin nor Neurofascin control the distal-to-proximal restriction of AnkG.

Dates et versions

hal-01542732 , version 1 (20-06-2017)

Identifiants

Citer

Barbara Le Bras, Amelie Freal, Antonny Czarnecki, Pascal Legendre, Erika Bullier, et al.. In vivo assembly of the axon initial segment in motor neurons. Brain Structure and Function, 2014, 219 (4), pp.1433-1450. ⟨10.1007/s00429-013-0578-7⟩. ⟨hal-01542732⟩
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