Modifying murine von Willebrand factor A1 domain for in vivo assessment of human platelet therapies.
The A1 domain of von Willebrand factor (VWF-A1) plays a crucial role in hemostasis and thrombosis by initiating platelet adhesion at sites of arterial injury through interactions with the platelet receptor glycoprotein Ib alpha (GPIbalpha). Here we report that murine VWF-A1 supports limited binding of human platelets. However, atomic models of GPIbalpha-VWF-A1 complexes identified an electrostatic 'hot-spot' that, when mutated in murine VWF-A1, switches its binding specificity from mouse to human GPIbalpha. Furthermore, mice expressing this mutant VWF-A1 display a bleeding phenotype that can be corrected by infusion of human platelets. Mechanistically, human platelets correct the phenotype by forming occlusive thrombi, an event that can be abrogated by blockade of GPIbalpha or by the preadministration of inhibitors of platelet activation or adhesion (clopidogrel (Plavix) and abciximab (ReoPro), respectively). Thus, by modifying a protein interface, we have generated a potential biological platform for preclinical screening of antithrombotics that specifically target human platelets.
Chen
Jianchun
J
Department of Pediatrics, Columbia University Medical Center, Irving Cancer Research Institute, 1130 St. Nicholas Ave., New York, NY 10032, USA.
Tan
Kui
K
Zhou
Hairu
H
Lo
Hsuan-Fu
HF
Tronik-Le Roux
Diana
D
Liddington
Robert C
RC
Diacovo
Thomas G
TG
D000818:Animals; D001792:Blood Platelets / Q000276:immunology*; D002478:Cells, Cultured; D004195:Disease Models, Animal; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic / Q000276:immunology*; D015202:Protein Engineering; D017434:Protein Structure, Tertiary; D013927:Thrombosis / Q000235:genetics* / Q000276:immunology*; D014841:von Willebrand Factor / Q000235:genetics* / Q000276:immunology*
D014841:von Willebrand Factor