title: Inhibition of platelet adhesion and aggregation by a defined region (Gly-486-Lys-502) of high molecular weight kininogen.
abstract: Proteolytic cleavage of single chain high molecular weight kininogen (HK) by kallikrein releases the short-lived vasodilator bradykinin and leaves behind two-chain high molecular weight kininogen (HKa). HKa and particularly its His-Gly-Lys-rich domain 5 have been previously reported to exert anti-adhesive properties by binding to the extracellular matrix protein vitronectin (VN). In this study the ability of HKa and domain 5 to interfere with platelet adhesion and aggregation was investigated. In a purified system HKa and particularly domain 5 but not HK inhibited the binding of VN to the alpha(IIb)beta(3) integrin, whereas the binding of fibrinogen to this integrin was not affected. The region Gly-486-Lys-502 from the carboxyl terminus of the domain 5 was identified as responsible for inhibition of the VN-alpha(IIb)beta(3)-integrin interaction, as this portion was also found to mediate kininogen binding to VN. Through these interactions, HKa, the isolated domain 5, and the peptide Gly-486-Lys-502 abrogated the alpha(IIb)beta(3)-integrin-dependent adhesion of human platelets to VN but not to fibrinogen. The codistribution of VN and HKa at sites of ex vivo platelet aggregation was demonstrated by transmission immune electron microscopy, indicating that the described interaction is likely to take place in vivo. Moreover, domain 5 and the peptide Gly-486-Lys-502 dose-dependently blocked platelet aggregation, resembling the inhibitory effect of monoclonal antibody 13H1 against multimeric VN. Finally, treatment of mice with isolated domain 5 resulted in a significantly prolonged tail bleeding time. Taken together, our data emphasize the inhibitory role of HK domain 5 on platelet adhesion and aggregation; new anti-thrombotic compounds may become available on the basis of peptide Gly-486-Lys-502 of HK domain 5.
authors.affiliation: Institute for Biochemistry, Justus-Liebig-University, D-35392 Giessen, Germany.
authors.forename: Triantafyllos
authors.initials: T
authors.lastname: Chavakis
authors.forename: Nicole
authors.initials: N
authors.lastname: Boeckel
authors.forename: Sentot
authors.initials: S
authors.lastname: Santoso
authors.forename: Reinhard
authors.initials: R
authors.lastname: Voss
authors.forename: Irma
authors.initials: I
authors.lastname: Isordia-Salas
authors.forename: Robin A
authors.initials: RA
authors.lastname: Pixley
authors.forename: Eberhard
authors.initials: E
authors.lastname: Morgenstern
authors.forename: Robert W
authors.initials: RW
authors.lastname: Colman
authors.forename: Klaus T
authors.initials: KT
authors.lastname: Preissner
mesh_terms: D000595:Amino Acid Sequence; D001792:Blood Platelets / Q000378:metabolism; D006801:Humans; D019679:Kininogen, High-Molecular-Weight / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000494:pharmacology*; D010973:Platelet Adhesiveness / Q000187:drug effects*; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D019039:Platelet Glycoprotein GPIIb-IIIa Complex / Q000378:metabolism; D019096:Vitronectin / Q000378:metabolism
chemical_list: D019679:Kininogen, High-Molecular-Weight; D010446:Peptide Fragments; D010975:Platelet Aggregation Inhibitors; D019039:Platelet Glycoprotein GPIIb-IIIa Complex; D019096:Vitronectin