Characterization of a chondroitin sultate proteoglycan associated with regeneration in goldfish optic tract

Regeneration of goldfish optic nerve axons is accompanied by a major increase in axonally transported proteoglycans (21). To identify specific proteoglycans increased during regeneration, we have used proteoglycan preparations from regenerating goldfish optic tracts to produce monoclonal antibodies. Western blot analysis shows a 28-kD antigen reacting with our 1G4/G5 antibody is present in optic tract 21 days after nerve crush, but absent in nonregenerating tract. Treatment with chondroitinase AC removes IG4/G5 immunostaining of the 28-kD molecule. An anti-CS antibody further confirmed this molecule as a chondroitin sulfate proteoglycan. A slightly smaller core protein following chondroitinase AC treatment indicates a low level of glycosylation. The N-terminal amino acid sequence of its core protein is not similar to any known proteoglycans. The CSPG sediments through 1.4 M sucrose, indicative of an extracellular matrix localization. It is expressed during the outgrowth of regenerating axons. Cut nerve and retinal explant studies demonstrate that the 1G4/G5 CSPG is not axonal, suggesting a glial localization.