Long-Range Ca2+ Signaling from Growth Cone to Soma Mediates Reversal of Neuronal Migration Induced by Slit-2

Neuronal migration and growth-cone extension are both guided by extracellular factors in the developing brain, but whether these two forms of guidance are mechanistically linked is unclear. Application of a Slit-2 gradient in front of the leading process of cultured cerebellar granule cells led to the collapse of the growth cone and the reversal of neuronal migration, an event preceded by a propagating Ca2+ wave from the growth cone to the soma. The Ca2+ wave was required for the Slit-2 effect and was sufficient by itself to induce the reversal of migration. The Slit-2-induced reversal of migration required active RhoA, which was accumulated at the front of the migrating neuron, and this polarized RhoA distribution was reversed during the migration reversal induced by either the Slit-2 gradient or the Ca (2+) wave. Thus, longrange Ca (2+) signaling coordinates the Slit-2induced changes in motility at two distant parts of migrating neurons by regulating RhoA distribution.