Inter-growth cone communication mediated by planar cell polarity pathway in axon guidance

The emergence of exquisitely organized axonal projections is one of the greatest wonders of nervous system development. In addition to growing along stereotyped directions, axons join one another as they extend. It is well known that axonal growth cones recognize cell surface guidance cues on axons and either grow along the axons or away from the axons. However, it is less well understood whether and how the growth cones communicate with each other and, if so, what do these interactions mean. Recent studies from our lab provided direct evidence that the growth cones do interact with each other during axon pathfinding. And this interaction is regulated by highly regulated protein-protein interactions among components of the planar cell polarity pathway. The disruption of these interactions lead to guidance defects and disorganization of axons. We propose that this local inter-growth cone PCP-like signaling mechanism reinforces and increases the sensitivity of the growth cone response to shallow Wnt gradients to turn in a precise and organized fashion.