Redistribution of cytoskeletal proteins in mammalian axons disconnected from their cell bodies

Mice of the strain C57/BL/Ola exhibit a delay of Wallerian degeneration, such that axons survive for several weeks after a nerve transection that separates the axons from the cell bodies. In this Ola strain we have examined the distribution of cytoskeletal proteins in a 5 mm segment of the sciatic nerve for as long as 2 weeks after proximal and distal transections that prevent entry or exit of proteins via axonal transport. By 7 d after transections, there was a marked accumulation of alpha- and beta-tubulin, actin, and nonphosphorylated neurofilament epitopes at the proximal and at the distal ends of the transected axons, and loss of these proteins from the center of the isolated nerve segment. Highly phosphorylated neurofilament epitopes did not redistribute along the nerve, but there was a gradual loss of phosphorylated neurofilament immunoreactivity. These observations indicate the potential for bidirectional transport of a substantial portion of certain cytoskeletal proteins within axons of the PNS.