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

Abstract

Mice of the strain C57/BL/OIa 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 alter 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 α- and β-tubulin, actin, and nonphosphorylated neurofitament epitopes at the proximal and at the distal ends of the transected axons, and loss of these pro-teins 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 sub-stantial portion of certain cytoskeletal proteins within axons of the PNS.