A critical role for 14-3-3zeta protein in regulating the VWF binding function of platelet glycoprotein Ib-IX and its therapeutic implications.
The platelet receptor for von Willebrand factor (VWF), glycoprotein (GP) Ib-IX, mediates platelet adhesion and activation. The cytoplasmic domains of the GPIb alpha and beta subunits contain binding sites for the phosphorylation-dependent signaling molecule, 14-3-3zeta. Here we show that a novel membrane-permeable inhibitor of 14-3-3zeta-GPIbalpha interaction, MPalphaC, potently inhibited VWF binding to platelets and VWF-mediated platelet adhesion under flow conditions. MPalphaC also inhibited VWF-dependent platelet agglutination induced by ristocetin. Furthermore, activation of the VWF binding function of GPIb-IX induced by GPIbbeta dephosphorylation is diminished by mutagenic disruption of the 14-3-3zeta binding site in the C-terminal domain of GPIbalpha, mimicking MPalphaC-induced inhibition, indicating that the inhibitory effect of MPalphaC is likely to be caused by disruption of 14-3-3zeta binding to GPIbalpha. These data suggest a novel 14-3-3zeta-dependent regulatory mechanism that controls the VWF binding function of GPIb-IX, and also suggest a new type of antiplatelet agent that may be potentially useful in preventing or treating thrombosis.
Dai
Kesheng
K
Department of Pharmacology, College of Medicine, University of Illinois at Chicago, 835 South Wolcott Ave, Chicago, IL 60612, USA.
Bodnar
Richard
R
Berndt
Michael C
MC
Du
Xiaoping
X
D048948:14-3-3 Proteins / Q000502:physiology*; D001665:Binding Sites / Q000235:genetics; D001792:Blood Platelets / Q000378:metabolism / Q000502:physiology; D005434:Flow Cytometry; D006801:Humans; D009154:Mutation; D010973:Platelet Adhesiveness; D010974:Platelet Aggregation; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D014841:von Willebrand Factor / Q000037:antagonists & inhibitors / Q000378:metabolism*
D048948:14-3-3 Proteins; D019038:Platelet Glycoprotein GPIb-IX Complex; D014841:von Willebrand Factor