The Journal of neuroscience : the official journal of the Society for Neuroscience
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The effects of peripheral nerve injury on the content, synthesis, and axonal transport of the class III beta-tubulin protein in adult rat dorsal root ganglion (DRG) neurons were examined. Recent reports of selective increases in the steady-state levels of the beta III-tubulin mRNA during axonal regeneration (Moskowitz et al., 1993) led to the hypothesis that upregulated levels of expression of the beta III-tubulin isotype that alter the composition of neuronal microtubules is important for effective axonal regrowth. If this is the case, the increases in mRNA levels must be translated into increased beta III-tubulin protein levels and subsequently modify the axonal cytoskeleton via axonal transport mechanisms. ⋯ Immunoprecipitation experiments using proximal peripheral nerve segments showed that SCb in distally injured DRG neurons was enriched in the beta III-tubulin isotype. These findings demonstrate that the augmented synthesis of beta III-tubulin after axotomy alters the composition of the axonally transported cytoskeleton that moves with SCb. The increased amounts and rate of delivery of beta III-tubulin in axons of regenerating DRG neurons suggest that the altered pattern of tubulin gene expression that is initiated by axotomy impacts on the composition and organization of the axonal cytoskeleton in a manner that can facilitate axonal regrowth.