Abstract
The formation of neuronal networks depends critically on the growth cone, a motile ameboid structure at the tip of elongating axon. Graded distributions of extracellular guidance cues attract or repel the growth cone by generating asymmetric cytosolic Ca2+ signals across the growth cone. We showed that the directional polarity of growth cone guidance is determined by the source of Ca2+ signals. We also demonstrated that, downstream of Ca2+ signals, asymmetric exocytosis and endocytosis drive growth cone attraction and repulsion, respectively. These findings provide a novel concept that polarized membrane trafficking acts as an instructive mechanism to spatially localize the steering apparatus such as cytoskeletal components and adhesion molecules.
