A Novel Antithrombotic Role for High Molecular Weight Kininogen as Inhibitor of Plasminogen Activator Inhibitor-1 Function

• Published in: The Journal of biological chemistry Vol. 277; no. 36; pp. 32677 - 32682
• Main Authors: Chavakis, Triantafyllos, Pixley, Robin A., Isordia-Salas, Irma, Colman, Robert W., Preissner, Klaus T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 06.09.2002; American Society for Biochemistry and Molecular Biology
• Subjects: Binding, Competitive; Cells, Cultured; Dose-Response Relationship, Drug; Endothelium, Vascular - cytology; Extracellular Matrix - metabolism; Fibrin - chemistry; Fibrin - metabolism; Fibrinolysin - metabolism; Fibrinolytic Agents - pharmacology; Glycine - chemistry; Humans; Kinetics; Kininogens - metabolism; Kininogens - pharmacology; Kininogens - physiology; Lysine - chemistry; Plasminogen Activator Inhibitor 1 - physiology; Protein Binding; Protein Isoforms; Protein Structure, Tertiary; Signal Transduction; Umbilical Veins - cytology; Vitronectin - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M204010200

The adhesive glycoprotein vitronectin (VN) forms a function-stabilizing complex with plasminogen activator inhibitor-1 (PAI-1), the major fibrinolysis inhibitor in both plasma and vessel wall connective tissue. VN also interacts with two-chain high molecular weight kininogen (HKa), particularly its His-Gly-Lys-rich domain 5, and both HKa and PAI-1 are antiadhesive factors that have been shown to compete for binding to VN. In this study the influence of HKa and domain 5 on the antifibrinolytic function of PAI-1 was investigated. In a purified system, HKa and particularly domain 5 inhibited the binding of PAI-1 to VN and promoted PAI-1 displacement from both isolated VN as well as subendothelial extracellular matrix-associated VN. The sequence Gly486-Lys502 of HKa domain 5 was identified as responsible for this inhibition. Although having no direct effect on PAI-1 activity itself, HKa domain 5 or the peptide Gly486-Lys502 markedly destabilized the VN·PAI-1 complex interaction, resulting in a significant reduction of PAI-1 inhibitory function on plasminogen activators, resembling the effect of VN antibodies that prevent stabilization of PAI-1. Furthermore, high affinity fibrin binding of PAI-1 in the presence of VN as well as the VN-dependent fibrin clot stabilization by the inhibitor were abrogated in the presence of the kininogen forms mentioned. Taken together, our data indicate that the peptide Gly486-Lys502 derived from domain 5 of HKa serves to interfere with PAI-1 function. Based on these observations potential low molecular weight PAI-1 inhibitors could be designed for the use in therapeutic interventions against thromboembolic complications.