The role of Slit/Robo signaling in neuronal morphogenesis

The Slit family of guidance cues signals via the Robo family of receptors to guide migrating axons in the developing spinal cord and forebrain. In addition to its ability to repel axons, Slit can promote the growth and branching of axons and dendrites. To better understand how Slit elicits such diverse responses in neurons, I studied mutant mice that lack Robot and Robo2 function. I found that both receptors are capable of mediating axon outgrowth, whereas only Robo2 is required for Slit-induced dendrite outgrowth in vitro. Subsequent Golgi analysis of dendrite morphology in Robo2 mutant mice revealed no significant reduction in dendrite branching, but Robot mutant mice displayed a small decrease in basal dendrite length in vivo. I also found that the cytoplasmic adaptor protein Nck binds to Robo in vitro and is required for the growth of axons and dendrites in response to Slit. Future studies should continue the effort to understand Robo's role in shaping dendrite arbors and further characterize the intracellular signaling events that link Robo/Nck to changes in neuron morphology.