Nr-CAM and TAG-1 are expressed in distinct populations of developing precerebellar and cerebellar neurons.
Nr-CAM and TAG-1 interact at the floor-plate during the formation of spinal cord commissural projections [Stoeckli, E.T., Landmesser, L.T., Sci. 274 (1995) 1123-1133; Fitzli, D., Stoeckli, E.T., Kunz, S., Siribour, K., Rader, C., Kunz, B., Kozlov, S.V., Buchstaller, A., Lane, R.P., Suter, D.M., Dreyer, W.J., Sonderegger, P., J. Cell. Biol. 149 (2000) 951-968]. We report here the spatio-temporal patterns of expression of these two adhesion molecules during the development of the lower brainstem (medulla and pons) and cerebellum. Nr-CAM and Tag-1 label distinct populations of precerebellar neurons at key steps of their development. Nr-CAM expression starts at E11.5-E12 in the floor-plate, that constitutes an intermediate target during axon outgrowth and nuclear migration of precerebellar neurons. At E13-E14, it is expressed in both floor-plate and inferior olivary nuclei (ION) neurons before being strictly restricted to ION neurons from E15 onwards. Furthermore Nr-CAM, which is widely expressed in the cerebellum during embryonic development, becomes strictly confined to Purkinje and Golgi cells in postnatal cerebellum, suggesting a possible role of Nr-CAM for the maturation or stabilization of the synaptic contacts, in particular between climbing fibers and Purkinje cells. On the other hand, Tag-1 is expressed by migrating neurons that will form the lateral reticular and basilar pontine nuclei. These results emphasize the possibility that TAG-1/Nr-CAM interactions are also involved in the development of the cerebellar system (precerebellar and cerebellar neurons). However, the pattern of cerebellar expression of TAG-1--early migrating Purkinje cells up to E14 and external granular cells--prevents the implication of this adhesion molecule in the organization of extracerebellar projections.
Backer
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S
INSERM U106, Hôpital de la Salpêtrière, 75013 Paris, France.
Sakurai
T
T
Grumet
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M
Sotelo
C
C
Bloch-Gallego
E
E
D000818:Animals; D015815:Cell Adhesion Molecules / Q000096:biosynthesis*; D015816:Cell Adhesion Molecules, Neuronal / Q000096:biosynthesis*; D002531:Cerebellum / Q000196:embryology / Q000378:metabolism*; D058969:Contactin 2; D018507:Gene Expression Regulation, Developmental / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats
D015815:Cell Adhesion Molecules; D015816:Cell Adhesion Molecules, Neuronal; C548675:Cntn2 protein, mouse; D058969:Contactin 2; C491151:Nrcam protein, mouse; D012333:RNA, Messenger