Chondroitin sulphate proteoglycans in the central nervous system: changes and synthesis after injury.

Chondroitin sulphate proteoglycans (CSPGs) are up-regulated in the central nervous system after injury, specifically around the lesion site where the glial scar forms. This structure contains astrocytes, oligodendrocyte precursor cells, microglia and meningeal cells, and forms an inhibitory substrate for axon re-growth. CSPGs have been shown to be closely involved in this neuronal growth inhibition, specifically through their sugar chains. These chains are composed of repeats of the same disaccharide unit carrying sulphate groups in different positions. The sulphation pattern directly influences the CSPG binding properties and function; the specific sulphation pattern required for the inhibitory activity of these molecules on axon growth is unknown at present. The expression of the chondroitin sulphotransferases, which sulphate the disaccharide residues of CSPGs and thus are responsible for the structural diversity of the chondroitin sulphate sugar chains, is regulated differently in central nervous system during development and after injury, suggesting the implication of a specific sulphation pattern in the inhibitory activity of CSPGs.