Differential display reveals transcriptional up-regulation of the motor molecules for both anterograde and retrograde axonal transport during nerve regeneration.

RNA fingerprinting using an arbitrary primed polymerase chain reaction was carried out to compare differences in expression of mRNAs between axotomized and normal hypoglossal motoneurons in the mouse. In this survey, the kinesin light chain (KLC) was identified as a nerve injury-associated molecule. This was also confirmed by in situ hybridization using hemihypoglossal nerve-transected brain sections. In order to identify the exact species of molecules belonging to the KLC family, in situ hybridization was carried out with oligonucleotide probes specific to rat KLC A, KLC B and KLC C, using the rat hypoglossal nerve injury model. In addition, expression of both ubiquitous and neuron-specific kinesin heavy chain and cytoplasmic dynein which is a retrograde motor, was also examined. Expression of all the members of the KLC (A-C) family and dynein was up-regulated during nerve regeneration, whereas the abundant expression of the neuron-specific KHC mRNA was not changed. The present results indicate that the molecules associated with both anterograde and retrograde axonal transport are up-regulated in their expression during efferent motor nerve regeneration, suggesting that the retrograde transport of growth factors and anterograde transport of vesicles, providing membrane material, could be increased during motor nerve regeneration.