Interactions of cellular glycosaminoglycans with plasma fibronectin and collagen

Abstract

The interactions of metabolically radiolabelled glycosaminoglycans, isolated from Swiss mouse 3T3 and SV3T3 cells, with plasma fibronectin and collagen were studied by affinity column chromatography in Hepes-buffered saline (150 mM NaCl in 10 mM Hepes buffer). Cell surface heparan sulfate glycosaminoglycan bound to plasma fibronectin and to native calf skin collagen in the absence of Ca 2+ and Mg 2+ with maximal binding at slightly acidic pH. Elution could be effected with elevated ionic strength. 3T3 and SV3T3 heparan sulfates coeluted when exposed to a salt concentration gradient. The core protein of the heparan sulfate proteoglycan did not bind to either fibronectin or collagen. Reference standard chondroitin 4-sulfate and chondroitin 6-sulfate had no effect upon heparan sulfate binding, whereas 90% of the heparan sulfate bound to fibronection or collagen was eluted with heparin and 60% removed from fibronectin with dermatan sulfate. Cell surface chondroitin sulfate proteoglycan bound only to collagen at acidic pH and no interaction was seen with fibronectin. Trypsin treatment of chondroitin sulfate proteoglycan reduced the binding to collagen. Cell surface hyaluronic acid did not display any affinity for either fibronectin or collagen.