A mechanism to safeguard platelet adhesion under high shear flow: von Willebrand factor-glycoprotein Ib and integrin alphabeta-collagen interactions make complementary, collagen-type-specific contributions to adhesion.
BACKGROUND
Blood vessels contain different types of collagen, with types I and III being the major components of vascular collagen. Platelet adhesion under high shear stress has been suggested to depend on the binding of von Willebrand factor (VWF) to collagen.


OBJECTIVE
We analyzed the collagen type specificity for the interaction with VWF and high shear stress platelet adhesion.


METHODS
VWF binding to different types of immobilized collagen and effects of antibodies against glycoprotein Ib (gpIb) and integrin alpha(2)beta(1) on platelet adhesion to type I and III collagens under high shear were analyzed.


RESULTS
VWF showed high-affinity, selective binding to human and bovine type III collagens, but weak or no affinity for types I, II, IV and V under static conditions. Anti-integrin alpha(2)beta(1) markedly inhibited adhesion to type I collagen, but did not affect that to type III collagen. Anti-gpIb antibody significantly inhibited adhesion to type III collagen. Adding both antibodies abrogated the adhesion to either type I or III collagen.


CONCLUSIONS
Both the gpIb-VWF interaction and the integrin alpha(2)beta(1)-collagen interaction contribute to platelet adhesion to collagen under high shear stress, and integrin alpha(II)beta(1) makes a greater contribution to adhesion to type I collagen because less VWF is bound to it.
Moroi
M
M
Department of Protein Biochemistry, Institute of Life Science, Kurume University, Kurume, Fukuoka, Japan. mmoroi@lsi.kurume-u.ac.jp
Jung
S M
SM
D000818:Animals; D001792:Blood Platelets / Q000378:metabolism; D002417:Cattle; D003094:Collagen / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D039001:Integrin alpha Chains / Q000737:chemistry*; D039641:Integrin beta Chains / Q000737:chemistry*; D007700:Kinetics; D010973:Platelet Adhesiveness; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000737:chemistry*; D011485:Protein Binding; D013314:Stress, Mechanical; D014841:von Willebrand Factor / Q000737:chemistry*
D039001:Integrin alpha Chains; D039641:Integrin beta Chains; D019038:Platelet Glycoprotein GPIb-IX Complex; D014841:von Willebrand Factor; D003094:Collagen