Nerve damage surveillance

The regeneration of damaged nerves relies on a JNK-dependent MAPK pathway and the stress-responsive transcription factor it activates, c-Jun. In relatively small epithelial cells, JNK can simply diffuse to the nucleus to turn on c-Jun. But human neurons can be up to a meter long—too long for diffusion to suffice. On page 775, Cavalli et al. suggest that damage communication might be achieved quickly by hooking JNK to axonal vesicles.JNK interacts with a scaffold protein called Sunday Driver (syd). Syd, in turn, has been proposed to link vesicles to the microtubule motor protein kinesin. With this knowledge in hand, the group now shows that JNK is a surveillance molecule ready to detect and report axonal injuries to the cell body.

JNK and syd were found in murine axons on vesicles that were...