An endogenous lectin and one of its neuronal glycoprotein ligands are involved in contact guidance of neuron migration.

In the central nervous system, postmitotic neurons migrate along astrocytic processes to reach their adult position. The molecular mechanisms of this guided migration are not clearly defined, although some steps have been shown to involve proteases and cell adhesion molecules. We report that monovalent antibodies (Fab fragments) raised against an endogenous cerebellar soluble lectin (CSL) completely inhibit neuronal migration in cultures of cerebellar explants at concentrations as low as 50 micrograms/ml. A similar inhibition pattern was obtained with Fab fragments prepared against one of the endogenous glycoprotein ligands of CSL, the 31-kDa glycoprotein (this glycoprotein is a membrane-bound glycoprotein specifically occurring, in the cerebellum, at the surface of immature neurons). We propose that this lectin-glycoprotein interaction supports the adhesion between neurons and the astrocyte guide during the migration of cerebellar immature neurons.