CELL-SURFACE HEPARAN-SULFATE PROTEOGLYCAN AND CHONDROITIN SULFATE PROTEOGLYCAN OF ARTERIAL SMOOTH-MUSCLE CELLS

Cell surface proteoglycans of aortic smooth muscle cells of atherosclerosis-susceptible White Carneau (WC) and atherosclerosis-resistant Show Racer (SR) pigeons were compared to determine differences that may be involved in the greater proliferative properties of cultured WC cells. Using [S-35]-sodium sulfate and [H-3]-glucosamine as labeling precursors, chondroitin sulfate-proteoglycan (CS-PG) and heparan sulfate-proteoglycan (HS-PG) were identified as distinct molecules associated with the plasma membrane. Heparan sulfate-proteoglycan was reduced up to 50% in WC compared with SR cells, and, based on interaction with ion-exchange resin, had a lower charge density. These differences were not observed for the CS-PG from the two cell types. The mode of association of the cell surface PG with the plasma membrane was examined. Dissociation with 1 mol/l (molar) sodium chloride indicated that < 10% of total cell surface PG were ironically associated with the cells. The remainder required detergent extraction, suggesting hydrophobic interactions with the plasma membrane. Both CS-PG and HS-PG displayed affinity for octyl sepharose and both were identified in isolated plasma membranes. These data present the first description of a hydrophobic CS-PG that is a significant and distinct cell-associated PG in arterial smooth muscle cells. The observation of decreased and structurally altered HS-PG in WC compared with SR cells is consistent with a potential growth regulatory function for this molecule.