Functional Involvement of Sciatic Nerve‐derived Versicanand Decorin‐like Molecules and other Chondroitin Sulphate Proteoglycans in ECM‐mediated Cell Adhesion and Neurite Outgrowth

We have previously described two proteoglycans from human sciatic nerve which are immunochemically related to the chondroitin sulphate proteoglycans versican and decorin. The chondroitin sulphate of the versican‐like molecule and the core protein of the decorin‐like molecule have been found previously to be up‐regulated after lesioning the adult mouse sciatic nerve. To investigate if the versican‐ and decorin‐like molecules are involved in cell‐extracellular matrix interactions, we studied the effect of both molecules on cell adhesion. The versican‐ and decorin‐like molecules, substrate‐coated in a mixture with fibronectin, but not with laminin or collagen types I or IV, inhibited the adhesion of several cell lines, neonatal dorsal root ganglion neurons and Schwann cells. The inhibitory activity was concentration‐dependent and mediated by the chondroitin sulphate. Furthermore, when different proteoglycans were incubated with fibronectin, only the versican‐ and decorin‐like molecules and the chondroitin sulphate proteoglycan aggrecan, but not the heparan sulphate proteoglycan perlecan, were able to inhibit fibronectin‐mediated cell adhesion. The versican‐ and decorin‐like molecules, substrate‐coated alone or in a mixture with fibronectin or laminin, were at most slightly inhibitory to neurite outgrowth from PC12 phaeochromocytoma cells and neonatal dorsal root ganglion neurons. In a solid‐phase ligand‐binding assay theversican‐ and decorin‐like molecules interacted with fibronectin, but not with laminin or collagen types I and IV. Binding of the versican‐like molecule to fibronectin and inhibition of cell adhesion by this molecule was mediated via the heparin and cell‐binding domains of fibronectin. These observations suggest that binding of the two proteoglycans to fibronectin is involved in the modulation of adhesion of cells to fibronectin.