N-cadherin provides a

Significance Glial-guided neuronal migration is a key step in the histogenesis of cortical regions in the mammalian brain and requires the expression of adhesion proteins by the migrating neuron and the glial fiber. The neuronal receptor astrotactin (ASTN1) regulates glial-guided migration, but the glial ligand has long been unknown. Here we demonstrate that neuron–glia attachment and neuronal migration depend on glial expression of the neural cadherin (CDH2) and that ASTN1 promotes migration by a direct interaction with neuronal and glial CDH2. Thus, ASTN1 and CDH2 form a cis and trans asymmetric bridge complex in the migration junction that is essential for glial-guided neuronal migration.
Prior studies demonstrate that astrotactin (ASTN1) provides a neuronal receptor for glial-guided CNS migration. Here we report that ASTN1 binds N-cadherin (CDH2) and that the ASTN1:CDH2 interaction supports cell–cell adhesion. To test the function of ASTN1:CDH2 binding in glial-guided neuronal migration, we generated a conditional loss of Cdh2 in cerebellar granule cells and in glia. Granule cell migration was slowed in cerebellar slice cultures after a conditional loss of neuronal Cdh2, and more severe migration defects occurred after a conditional loss of glial Cdh2. Expression in granule cells of a mutant form of ASTN1 that does not bind CDH2 also slowed migration. Moreover, in vitro chimeras of granule cells and glia showed impaired neuron–glia attachment in the absence of glial, but not neuronal, Cdh2. Thus, cis and trans bindings of ASTN1 to neuronal and glial CDH2 form an asymmetric neuron–glial bridge complex that promotes glial-guided neuronal migration.