Abstract
A molecule that may be important for sorting presynaptic components into the developing axon is now revealed by a study using the genetic tools available in C. elegans.
Neurons often extend multiple processes, but usually only one becomes the axon whereas the others become dendrites. How one process is chosen to become the axon is largely unknown. In this issue, Hallam et al. characterize a molecule that may be important in keeping axons and dendrites distinct1.
Much of our current understanding of how a neuronal process becomes an axon or dendrite comes from a series of studies using cultured rat hippocampal neurons2,3. Each hippocampal neuron extends multiple neurites, and these neurites compete with one another to become the axon, with the 'losers' becoming dendrites. Current models suggest that some factors promote axon formation, whereas others inhibit it; a combination of negative and positive feedback loops may ensure that one—and only one—neurite of each neuron becomes the axon2,3.