Aptamer BAX 499 mediates inhibition of tissue factor pathway inhibitor via interaction with multiple domains of the protein.

Autor: Waters EK; Baxter Healthcare Corporation, Cambridge, MA, USA., Genga RM, Thomson HA, Kurz JC, Schaub RG, Scheiflinger F, McGinness KE
Jazyk: angličtina
Zdroj: Journal of thrombosis and haemostasis : JTH [J Thromb Haemost] 2013 Jun; Vol. 11 (6), pp. 1137-45.
DOI: 10.1111/jth.12201
Abstrakt: Background: Tissue factor pathway inhibitor (TFPI) is a multidomain protein that negatively regulates the coagulation cascade. TFPI inhibits the tissue factor (TF)-activated factor VII-activated FX (FXa) complex during TF-mediated coagulation initiation. The aptamer BAX 499 binds specifically to TFPI and inhibits its function, mediating a procoagulant effect in both in vitro and in vivo models of hemophilia.
Objectives: This study sought to identify the regions of TFPI that are critical for BAX 499 binding, and to determine how binding mediates aptamer inhibition of TFPI.
Methods and Results: In vitro biochemical methods were used to evaluate the BAX 499 interaction with and inhibition of TFPI. Binding experiments indicated that the full-length TFPI protein is required for tight aptamer binding. Binding-competition experiments implicated the Kunitz 1, Kunitz 3 and C-terminal domains of TFPI in aptamer binding, a finding that is supported by hydrogen-deuterium exchange experiments, and indicated that aptamer and FXa can bind simultaneously to TFPI. In enzymatic assays, BAX 499 inhibited TFPI in a manner that is distinct from domain-specific antibodies, and aptamer inhibitory activity is reduced in the presence of the TFPI cofactor protein S.
Conclusions: These studies demonstrate that BAX 499 binds to TFPI via multiple domains of the protein in a manner that is distinct from other TFPI inhibitors, mediating a mechanism of inhibition that does not involve direct competition with FXa. With this unique inhibitory mechanism, BAX 499 provides a useful tool for studying TFPI biology in health and disease.
(© 2013 International Society on Thrombosis and Haemostasis.)
Databáze: MEDLINE
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