EphrinB2 sharpens lateral motor column division in the developing spinal cord.
BACKGROUND
During sensori-motor circuit development, the somas of motoneurons (MN) are distributed in a topographic manner in the ventral horn of the neural tube. Indeed, their position within the lateral motor columns (LMC) correlates with axonal trajectories and identity of target limb muscles. The mechanisms by which this topographic distribution is established remains poorly understood. To address this issue, we assessed the role of ephrinB2 in MN topographic organization in the developing mouse spinal cord.


RESULTS
First, we used a reporter mouse line to establish the spatio-temporal expression pattern of EfnB2 in the developing LMC. We show that early in LMC development, ephrinB2 is differentially expressed in MN of the lateral versus medial LMC, suggesting a possible role in MN sorting and/or migration. We demonstrate that while MN-specific excision of EfnB2 did not perturb specification or migration of MN, conditional loss of ephrinB2 led to the blurring of the LMC divisional boundary and to errors in the selection of LMC axon trajectory in the limb.


CONCLUSIONS
Altogether, our study uncovered a novel cell autonomous role for ephrinB2 in LMC MN thus emphasizing the prevalent role of this ephrin member in maintaining cell population boundaries.
Centre de Biologie du Développement, CNRS, 118 Route de Narbonne, 31062, Toulouse, France.|Université de Toulouse, Toulouse, France.|Institut de Recherche Clinique de Montréal, 110 avenue des Pins Ouest, Montréal (Québec), H2W 1R7, Canada.
Maëva
M
Luxey
Centre de Biologie du Développement, CNRS, 118 Route de Narbonne, 31062, Toulouse, France.|Université de Toulouse, Toulouse, France.
Julien
J
Laussu
Centre de Biologie du Développement, CNRS, 118 Route de Narbonne, 31062, Toulouse, France. alice.davy@univ-tlse3.fr.|Université de Toulouse, Toulouse, France. alice.davy@univ-tlse3.fr.
Alice
A
Davy
D000818:Animals; D019521:Body Patterning / Q000502:physiology*; D002460:Cell Line; D036388:Ephrin-B2 / Q000378:metabolism*; D007091:Image Processing, Computer-Assisted; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D008817:Mice, Mutant Strains; D009046:Motor Neurons / Q000166:cytology* / Q000378:metabolism; D055495:Neurogenesis / Q000502:physiology*; D016133:Polymerase Chain Reaction; D013116:Spinal Cord / Q000196:embryology*
C000601240:EFNB2 protein, mouse; D036388:Ephrin-B2