TMVA, a snake C-type lectin-like protein from Trimeresurus mucrosquamatus venom, activates platelet via GPIb

TMVA is a C-type lectin-like protein with potent platelet activating activity from Trimeresurus mucrosquamatus venom. In the absence of von Willebrand factor (vWF), TMVA dose-dependently induced aggregation of washed platelets. Anti-GP Ib monoclonal antibodies (mAbs), HIP1, specifically inhibited TM...

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Bibliographic Details
Published in:Toxicon (Oxford) 2004-11, Vol.44 (6), p.649-656
Main Authors: Tai, Hong, Wei, Qin, Jin, Yang, Su, Min, Song, Jian-Xin, Zhou, Xin-Ding, Ouyang, Hong-Mei, Wang, Wan-Yu, Xiong, Yu-Liang, Zhang, Yun
Format: Article
Language:English
Subjects:
Animal poisons toxicology. Antivenoms
Animals
Biological and medical sciences
Crotalid Venoms - chemistry
Dose-Response Relationship, Drug
Flow Cytometry
Fluorescein-5-isothiocyanate - metabolism
GPIb
Humans
Lectins, C-Type - metabolism
Medical sciences
Metalloendopeptidases - pharmacology
Mocarhagin
Platelet Activating Factor - metabolism
Platelet Activating Factor - pharmacology
Platelet Activation - drug effects
Platelet aggregation
Platelet Glycoprotein GPIb-IX Complex - metabolism
TMVA
Toxicology
Trimeresurus
Trimeresurus mucrosquamatus
Viper Venoms - metabolism
Viper Venoms - pharmacology
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Summary:TMVA is a C-type lectin-like protein with potent platelet activating activity from Trimeresurus mucrosquamatus venom. In the absence of von Willebrand factor (vWF), TMVA dose-dependently induced aggregation of washed platelets. Anti-GP Ib monoclonal antibodies (mAbs), HIP1, specifically inhibited TMVA-induced aggregation in a dose-dependent manner. The aggregation was also inhibited by mAb P2 (an anti-GP IIb mAb). Flow cytometric analysis revealed that FITC-TMVA bound to human formalin-fixed platelets in a saturable manner, and its binding was specifically blocked by HIP1 in a dose-dependent manner. Flow cytometric analysis showed that TMVA did not bind to platelet GPIX, GPIIb, GPIIIa, GPIa, GPIIa and GPIV. Moreover, the platelet aggregation induced by TMVA was partially inhibited when platelet was pretreated with mocarhagin, a snake venom protease that specifically cleaves human GPIb. These results suggest that TMVA is a strong platelet agonist via GPIb and it might have multiple functional binding-sites on GPIb molecule or on other unknown receptor.
ISSN:0041-0101
1879-3150
DOI:10.1016/j.toxicon.2004.07.022