Traffic signaling: new functions of huntingtin and axonal transport in neurological disease.

•Subtle changes in axonal transport can modulate protein accumulation at the synapse.•The huntingtin mutation underlying Huntington’s disease disrupts axonal transport.•Huntingtin (HTT) scaffolds/transports many key neuronal proteins, including BDNF.•Post-translational modifications in HTT regulate direction and speed of transport.•Tweaking HTT-mediated transport could help in Rett Syndrome and Alzheimer’s disease.