title: Evidence for thrombin binding to dermatan sulphate sites in the rabbit aorta subendothelium in vitro.
abstract: The proposal that thrombin binds to dermatan sulphate chains of extracellular proteoglycans has been examined directly using the subendothelium of the rabbit aorta. Freshly excised aortas were de-endothelialized by balloon catheter in vitro and then incubated with 125I-thrombin to allow adsorption of 20-30 fmol of thrombin/cm2. Pretreatment of the subendothelium with FPR-thrombin or chondroitinase ABC partially inhibited thrombin binding, each by approximately 40-45%. The addition of dermatan sulphate inhibited, competitively, up to 50% of thrombin from binding to the subendothelium whereas chondroitin-4 or -6 sulphates had little or no effect. By contrast, protamine inhibited 90% of FPR-thrombin binding. Of subendothelium-bound thrombin, chondroitinase ABC released only a small proportion (3-12%) of bound thrombin but up to 44% of bound FPR-thrombin. It is concluded that, when 125I-thrombin is bound in vitro at a concentration of < 30 fmol/cm2 of aorta intima-media, approximately 50% of subendothelial 125I-thrombin is bound to dermatan sulphate chains of proteoglycan in the extracellular matrix. The possibility is discussed that dermatan sulphate chains may function as thrombin-binding loci to control or augment thrombin activity in the ECM of the injured vascular wall in vivo.
authors.affiliation: Department of Pathology, McMaster University Health Sciences Centre, Hamilton, Ontario, Canada.
authors.forename: M W
authors.initials: MW
authors.lastname: Hatton
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000378:metabolism*; D001665:Binding Sites / Q000502:physiology; D002808:Chondroitin Lyases / Q000494:pharmacology; D003871:Dermatan Sulfate / Q000378:metabolism*; D005688:Galactosamine / Q000737:chemistry; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D008297:Male; D008566:Membranes / Q000378:metabolism; D010978:Platelet Factor 4 / Q000494:pharmacology; D011134:Polysaccharides / Q000737:chemistry / Q000494:pharmacology; D011479:Protamines / Q000494:pharmacology; D011485:Protein Binding; D011817:Rabbits; D013917:Thrombin / Q000378:metabolism*
chemical_list: D007457:Iodine Radioisotopes; D011134:Polysaccharides; D011479:Protamines; D003871:Dermatan Sulfate; D010978:Platelet Factor 4; D005688:Galactosamine; D013917:Thrombin; D002808:Chondroitin Lyases