Carbohydrate diversity of chondroitin sulfate proteoglycans and its functional specificity in retinotectal pathway formation

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Chondroitin sulfates (CSs) are carbohydrate polymers consisting of disaccharide units of glucuronic acid and N-acetylgalactosamine. Depending on sulfation positions, different units are distinguished, and combinations of the various CSs' units demonstrate structural diversity. Although CSs are known to be involved in inhibition of axonal growth, it has not been shown that their inhibitions are direct effect, or that their structural diversity is related to differential effects.MO-225 monoclonal antibody recognizes particular structural motifs in CSs. To know CSs structure recognized by MO-225, polystyrene beads were coated with preparations of CSs in which particular units are enriched. Binding MO-225 to the CSs coated polystyrene beads were examined by using fluorocytometry ; MO-225 preferentially bound to the CSs rich in C, D, and E unit.Immunohistochemical analyses in chick embryos revealed that MO-225 recognized that (1)neuropil encircling the optic tract and (2)outer surface of the retinal axons running in an interface layer between the optic tract and its encircling neuropil. The results suggest that the CSs recognized by MO-225 containing C,D, or E unit in rich are involved with setting up boundary of the optic tract and chronological sorting of the retinal axons in the optic tract.To know effects of the CSs particularly recognized by MO-225, behaviors of retinal growth cones have been examined during their encounter on the beads coated with the CSs rich in C,D, or E unit. CSs rich in C or D unit were not likely to induce considerable effects on the retinal growth cones. Other types of CSs are presently being examined.