RT Journal Article
SR Electronic
T1 Antithrombotic Effect of a Protein-Type I Class Snake Venom Metalloproteinase, Kistomin, Is Mediated by Affecting Glycoprotein Ib-von Willebrand Factor Interaction
JF Molecular Pharmacology
JO Mol Pharmacol
FD American Society for Pharmacology and Experimental Therapeutics
SP 984
OP 992
DO 10.1124/mol.107.038018
VO 72
IS 4
A1 Chun-Chieh Hsu
A1 Wen-Bin Wu
A1 Ya-Hui Chang
A1 Heng-Lan Kuo
A1 Tur-Fu Huang
YR 2007
UL http://molpharm.aspetjournals.org/content/72/4/984.abstract
AB Binding of von Willebrand factor (vWF) to platelet glycoprotein (GP) Ib-IX-V mediates platelet activation in the early stage of thrombus formation. Kistomin, a snake venom metalloproteinase (SVMP) purified from venom of Calloselasma rhodostoma, has been shown to inhibit vWF-induced platelet aggregation. However, its action mechanism, structure-function relationship, and in vivo antithrombotic effects are still largely unknown. In the present study, cDNA encoding kistomin precursor was cloned and revealed that kistomin is a P-I class SVMP with only a proteinase domain. Further analysis indicated that kistomin specifically inhibited vWF-induced platelet aggregation through binding and cleavage of platelet GPIbα and vWF. Cleavage of platelet GPIbα by kistomin resulted in release of 45- and 130-kDa soluble fragments, indicating that kistomin cleaves GPIbα at two distinct sites. In parallel, cleavage of vWF by kistomin also resulted in the formation of low-molecular-mass multimers of vWF. In ex vivo and in vivo studies, kistomin cleaved platelet GPIbα in whole blood. Moreover, GPIbα agonist-induced platelet aggregation ex vivo was inhibited, and tail-bleeding time was prolonged in mice administered kistomin intravenously. Kistomin's in vivo antithrombotic effect was also evidenced by prolonging the occlusion time in mesenteric microvessels of mice. In conclusion, kistomin, a P-I class metalloproteinase, has a relative specificity for GPIbα and vWF and its proteolytic activity on GPIbα-vWF is responsible for its antithrombotic activity both in vitro and in vivo. Kistomin can be useful as a tool for studying metalloproteinase-substrate interactions and has a potential being developed as an antithrombotic agent. The American Society for Pharmacology and Experimental Therapeutics