GPIb-dependent platelet activation is dependent on Src kinases but not MAP kinase or cGMP-dependent kinase

• Published in: Blood 2004-04, Vol.103 (7), p.2601-2609
• Main Authors: Marshall, Stuart J., Senis, Yotis A., Auger, Jocelyn M., Feil, Robert, Hofmann, Franz, Salmon, Gary, Peterson, J. Thomas, Burslem, Frank, Watson, Steve P.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Blood coagulation. Blood cells; Blood Platelets - drug effects; Blood Platelets - physiology; Cyclic GMP - blood; Cyclic GMP-Dependent Protein Kinases - blood; Cyclic GMP-Dependent Protein Kinases - deficiency; Cyclic GMP-Dependent Protein Kinases - genetics; Fundamental and applied biological sciences. Psychology; Humans; Kinetics; Mice; Mice, Knockout; Mitogen-Activated Protein Kinases - blood; Molecular and cellular biology; Nitric Oxide Donors - pharmacology; Platelet; Platelet Activation - physiology; Platelet Glycoprotein GPIb-IX Complex - physiology; Platelet Membrane Glycoproteins; Receptors, Antigen, B-Cell - blood; von Willebrand Factor - pharmacology
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2003-09-3319

Glycoprotein Ib-IX-V (GPIb-IX-V) mediates platelet tethering to von Willebrand factor (VWF), recruiting platelets into the thrombus, and activates integrin αIIbβ3 through a pathway that is dependent on Src kinases. In addition, recent reports indicate that activation of αIIbβ3 by VWF is dependent on protein kinase G (PKG) and mitogen-activated protein (MAP) kinases. The present study compares the importance of these signaling pathways in the activation of αIIbβ3 by GPIb-IX-V. In contrast to a recent report, VWF did not promote an increase in cyclic guanosine monophosphate (cGMP), while agents that elevate cGMP, such as the nitrous oxide (NO) donor glyco–SNAP-1 (N-(β-D-glucopyranosyl)-N2-acetyl-S-nitroso-D,L-penicillaminamide) or the type 5 phosphosdiesterase inhibitor, sildenafil, inhibited rather than promoted activation of αIIbβ3 by GPIb-IX-V and blocked aggregate formation on collagen at an intermediate rate of shear (800 s-1). Additionally, sildenafil increased blood flow in a rabbit model of thrombus formation in vivo. A novel inhibitor of the MAP kinase pathway, which is active in plasma, PD184161, had no effect on aggregate formation on collagen under flow conditions, whereas a novel inhibitor of Src kinases, which is also active in plasma, PD173952, blocked this response. These results demonstrate a critical role for Src kinases but not MAP kinases in VWF-dependent platelet activation and demonstrate an inhibitory role for cGMP-elevating agents in regulating this process.