Factor V anticoagulant cofactor activity that targets the early phase of coagulation

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Title: Factor V anticoagulant cofactor activity that targets the early phase of coagulation
Authors: Santamaria, S
Reglińska-Matveyev, N
Gierula, M
Camire, RM
Crawley, JTB
Lane, DA
Ahnström, J
Item Type: Journal Article
Abstract: Tissue factor pathway inhibitor (TFPI), the main inhibitor of initiation of coagulation, exerts an important anticoagulant role through the factor Xa (FXa)-dependent inhibition of tissue factor/factor VIIa (FVIIa). Protein S is a TFPI cofactor, enhancing the efficiency of FXa inhibition. TFPI can also inhibit prothrombinase assembly by directly interacting with coagulation factor V (FV) which has been activated by FXa. Since full-length TFPI associates with FV in plasma, we hypothesized that FV may influence TFPI inhibitory function. Using pure component FXa inhibition assays, we found that while FV alone did not influence TFPI-mediated FXa inhibition, it further enhanced TFPI in the presence of protein S, resulting in an ~8-fold reduction in Ki compared with TFPI alone. A FV variant (R709Q/R1018Q/R1545Q, FVΔIIa) that cannot be cleaved/activated by thrombin or FXa, also enhanced TFPI-mediated inhibition of FXa ~12-fold in the presence of protein S. In contrast, neither activated FV (FVa) nor recombinant B-domain-deleted FV could enhance TFPI-mediated inhibition of FXa in the presence of protein S, suggesting a functional contribution of the B domain. Using TFPI and protein S variants we show further that the enhancement of TFPI-mediated FXa inhibition by protein S and FV depends on a direct protein S/TFPI interaction and that the TFPI C-terminal tail is not essential for this enhancement. In FXa-catalyzed prothrombin activation assays, both FV and FVΔIIa (but not FVa) enhanced TFPI function in the presence of protein S. These results demonstrate a new anticoagulant (cofactor) function of FV that targets the early phase of coagulation before prothrombinase assembly.
Issue Date: 18-Apr-2017
Date of Acceptance: 18-Apr-2017
URI: http://hdl.handle.net/10044/1/49754
DOI: https://dx.doi.org/10.1074/jbc.M116.769570
ISSN: 0021-9258
Publisher: American Society for Biochemistry and Molecular Biology
Start Page: 9335
End Page: 9344
Journal / Book Title: Journal of Biological Chemistry
Volume: 292
Copyright Statement: © 2017 by The American Society for Biochemistry and Molecular Biology, Inc. Author's Choice—Final version free via Creative Commons CC-BY license (https://creativecommons.org/licenses/by/4.0/)
Sponsor/Funder: British Heart Foundation
British Heart Foundation
Funder's Grant Number: PG/14/63/31036
Keywords: Science & Technology
Life Sciences & Biomedicine
Biochemistry & Molecular Biology
coagulation factor
enzyme inhibitor
inhibition mechanism
protein S
protein-protein interaction
tissue factor pathway inhibitor
Amino Acid Substitution
Blood Coagulation
Factor V
Factor Xa
Mutation, Missense
Protein Domains
Protein S
06 Biological Sciences
11 Medical And Health Sciences
03 Chemical Sciences
Publication Status: Published
Conference Place: United States
Appears in Collections:Department of Medicine
Faculty of Medicine

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