Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.6.4 (chondroitinase)
 2,039 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tissue factor pathway inhibitor (TFPI) is mainly bound to the vessel wall and is released to circulating blood after injections of heparin. It has been suggested that the highly positively charged carboxy terminal end of heparin releasable TFPI is bound to negatively charged binding molecule(s), presumably glycosaminoglycans (GAGs), on the luminal surface of endothelial cells. The aim of the present study was to characterize this binding. Confluent monolayers of human umbilical vein endothelial cells (HUVECs) and Ea.hy926 cells were incubated with 125I-labelled recombinant TFPI (rTFPI). Two different rTFPI preparations were used in the experiments; one preparation was full-length rTFPI and one preparation was truncated at the C-terminal end (rTFPI1-161). Binding of 125I-rTFPI reached equilibrium conditions after 2 hours incubation at room temperature. Scatchard plots indicated a single class of binding sites with a mean Kd value of 164 +/- 16 nmol/L for HUVECs and a Kd value of 296 +/- 10 nmol/L for Ea.hy926 cells. The number of rTFPI binding sites per cell were approximately 1.10(7). Binding of 125I-rTFPI1-161 was non-specific. GAGs reduced binding of 125I-rTFPI in a dose-dependent manner by 50-75%. The potency of different GAGs to displace bound rTFPI was in the following order: Unfractionated heparin (UF) > low-molecular weight (LMW) heparin > hexadecasaccharides/octasaccharides/dodecasaccharides > heparan sulfate > dermatan sulfate. Treatment of the cells with heparinase III, with chondroitinase ABC lyase, or with sodium chlorate (to prevent sulfation) did not influence the binding of TFPI. We conclude that the C-terminal end is necessary for binding of TFPI to endothelial cells, but the binding is weak and does not involve GAGs.
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PMID:Binding of tissue factor pathway inhibitor to cultured endothelial cells-influence of glycosaminoglycans. 894 51

Tissue factor pathway inhibitor (TFPI) is a potent inhibitor of blood coagulation factor Xa (fXa) and factor VIIa. We have recently shown that fXa binding stimulates the uptake and degradation of cell surface-bound 125I-TFPI (Ho, G., Toomey, J. R., Broze, G. J., Jr., and Schwartz, A. L. (1996) J. Biol. Chem. 271, 9497-9502). In the present study we examined the role of cell surface glycosaminoglycans (GAGs) in this process. Removal of cell surface GAG chains by treatment of cells with heparinase or heparitinase but not chondroitinase markedly reduced fXa-stimulated 125I-TFPI uptake and degradation. Inhibition of GAG sulfation by growth of cells in chlorate-containing medium similarly decreased fXa-stimulated 125I-TFPI degradation. These results suggest that heparan sulfate proteoglycans (HSPGs) are required for the uptake and degradation of 125I-TFPI.fXa complexes. Chemical cross-linking/immunoprecipitation analyses revealed that 125I-TFPI was directly associated with HSPGs on the cell surface and that fXa binding increased the amount of 125I-TFPI bound. Of the several cell lines evaluated, bend endothelial cells demonstrated the greatest fXa stimulation of 125I-TFPI uptake and degradation. Cross-linking/immunoprecipitation analyses on bend cells also revealed that HSPGs were specifically associated with TFPI and fXa. These data suggest that HSPGs may directly act as the uptake and degradation receptor for TFPI.fXa complexes.
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PMID:Role of heparan sulfate proteoglycans in the uptake and degradation of tissue factor pathway inhibitor-coagulation factor Xa complexes. 920 90