Laminin G1 residues of protein S mediate its TFPI cofactor function and are competitively regulated by C4BP
| Autor: | Salvatore Santamaria, Patricia Badia Folgado, Anastasis Petri, David A. Lane, Magdalena Gierula, Adrienn Teraz-Orosz, James T. B. Crawley, David A. Jones, Josefin Ahnström, Renos Keniyopoullos |
|---|---|
| Přispěvatelé: | British Heart Foundation |
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
chemistry.chemical_classification
Alanine Glycosylation biology C4b-binding protein Complement C4b-Binding Protein Lipoproteins Thrombin Factor V Hematology Protein S Cofactor Thrombosis and Hemostasis Amino acid Cell biology chemistry.chemical_compound Tissue factor pathway inhibitor chemistry medicine biology.protein Laminin Protein C medicine.drug |
| Zdroj: | Blood Advances |
| Popis: | Key Points Protein S LG1 residues Lys255/Glu257/Asp287/Arg410/Lys423/Glu424 are critical for its TFPI cofactor function.Binding of the C4BP β-chain to protein S blocks the function of this region. Visual Abstract Protein S is a cofactor in the tissue factor pathway inhibitor (TFPI) anticoagulant pathway. It enhances TFPIα-mediated inhibition of factor (F)Xa activity and generation. The enhancement is dependent on a TFPIα-protein S interaction involving TFPIα Kunitz 3 and protein S laminin G-type (LG)-1. C4b binding protein (C4BP), which binds to protein S LG1, almost completely abolishes its TFPI cofactor function. However, neither the amino acids involved in TFPIα enhancement nor the mechanisms underlying the reduced TFPI cofactor function of C4BP-bound protein S are known. To screen for functionally important regions within protein S LG1, we generated 7 variants with inserted N-linked glycosylation attachment sites. Protein S D253T and Q427N/K429T displayed severely reduced TFPI cofactor function while showing normal activated protein C (APC) cofactor function and C4BP binding. Based on these results, we designed 4 protein S variants in which 4 to 6 surface-exposed charged residues were substituted for alanine. One variant, protein S K255A/E257A/D287A/R410A/K423A/E424A, exhibited either abolished or severely reduced TFPI cofactor function in plasma and FXa inhibition assays, both in the presence or absence of FV-short, but retained normal APC cofactor function and high-affinity C4BP binding. The C4BP β-chain was expressed to determine the mechanisms behind the reduced TFPI cofactor function of C4BP-bound protein S. Like C4BP-bound protein S, C4BP β-chain-bound protein S had severely reduced TFPI cofactor function. These results show that protein S Lys255, Glu257, Asp287, Arg410, Lys423, and Glu424 are critical for protein S-mediated enhancement of TFPIα and that binding of the C4BP β-chain blocks this function. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|