Molecular interaction of recombinant decorin and biglycan with type I collagen influences crystal growth

This study has investigated the interaction of recombinant chondroitin sulphate (CS)-substituted decorin and biglycan on collagen fibrillogenesis, their interaction with hydroxyapatite (HAP), and HAP-induced crystal growth. The core proteins of the recombinant decorin and biglycan were obtained following chondroitinase ABC digestion and their influence on the above physical mechanisms were investigated in parallel. CS-decorin promoted collagen fibrillogenesis, with the interaction mediated principally through the core protein. Both decorin and biglycan demonstrated a strong association for HAP, predominately facilitated through the glycosaminoglycan chains. HAP-induced crystal growth was inhibited by decorin and biglycan, although the degree of inhibition was reduced when these proteoglycans were complexed with type I collagen. Thus, this study has highlighted potentially differing roles for decorin and biglycan, as both promoters and inhibitors in the regulation of the mineralization process.