Incorporation of axonally transported glycoproteins into axolemma during nerve regeneration

To follow the fate of the "pulse- labeled" glycoproteins, we examined the nerves by correlative radiometric and EM radioautographic approaches

JW Griffin


Scholarcy highlights

  • The results showed, first, that rapidly transportedfucosyl glycoproteins were inserted into the axolemma of regenerating sprouts as well as parent axons
  • One role of fast axonal transport in nerve regeneration is the contribution to the regenerating sprout of glycoproteins inserted into the axolemma ; these membrane elements are added both during longitudinal outgrowth and during lateral growth and maturation of the sprout
  • There was a "valley" that preceded a larger peak of accumulated radioactivity. This peak of radioactivity represented in large part [ 3Hlfucosyl glycoproteins transported to, and accumulated within, sprout endings ; as discussed below, radioautographic studies showed that growth cones were heavily labeled and were most numerous in this region
  • This study was designed to construct a spatial and temporal picture of aspects of the insertion of glycoproteins into the axolemma of regenerating sprouts. Interpretation of these correlative radiometric and radioautographic studies is based on the fact that labeled fucosyl glycoproteins are synthesized in the cell body and delivered to regenerating axon in relatively "pulsed" fashion, with fast axonal transport providing the means of delivery 40
  • The autoradiographic results showed that some axonally transportedfucosyl glycoproteins were incorporated into the axolemma of the regenerating sprouts within the first day after synthesis. 1 d after labeling, in addition to the silver grains located within the axon, another fraction was clearly associated with axolemma
  • By 7 d after labeling, the grains remaining in the regenerating sprouts were associated almost exclusively with axolemma, and the grain distribution closely approximated that expected for a hollow circular source
  • That this increase was not the result of the increased fast transport of fucosyl glycoprotein that occurs during regeneration was shown by the fact that no greater retention was seen in parent axons than in the control nerves 7 or 14 d after labeling (Figs

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