Protein kinase C is activated in platelets subjected to pathological shear stress.

M.H Kroll,J.D Hellums,Z Guo,W Durante,K Razdan,J.K Hrbolich,A.I Schafer

doi:10.1016/s0021-9258(18)53725-x

M.H Kroll, J.D Hellums + Show 5 more

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https://doi.org/10.1016/s0021-9258(18)53725-x

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Abstract

High levels of fluid shear stress at the blood vessel wall directly stimulate von Willebrand factor (vWF)-mediated platelet adhesion and aggregation and thereby contribute to the pathogenesis of arterial thrombosis. We have found that a pathological level of arterial wall shear stress (90 dynes/cm2) induces platelet aggregation that is associated with the phosphorylation of pleckstrin, a M(r) 47,000 protein kinase C substrate (p47). Shear-induced p47 phosphorylation depends entirely on vWF binding to platelet glycoprotein (Gp) Ib and GpIIb-IIIa, and the specific inhibition of protein kinase C with the staurosporine analogue Ro 31-7549 inhibits the full aggregation response to shear. Shear stress-induced platelet p47 phosphorylation occurs independent of any measurable change in diacylglycerol mass or hydrolysis of phosphatidylinositol 4,5-bisphosphate. These results indicate that mechanical shear stress induces vWF to bind to platelet GpIb and GpIIb-IIIa, stimulating a diacylglycerol-independent pathway of protein kinase C activation that contributes to platelet aggregation in response to shear.

Highlights

High levels of fluid shear stress at the blood vessel wall directly stimulate von Willebrand factormediated platelet adhesion and aggregation and thereby contribute to the pathogenesis of arterial thrombosis
We report that a pathological level of arterial wall shear stress induces diacylgylcerol-independent protein kinase C activation that depends on von Willebrand factor (vWF) binding to GpIb and GpIIb-IIIa, and that protein kinase C contributes to thefull aggregation response of platelets to shear stress
Shear-induced protein kinase C (PKC) activation is inhibited by the specific PKC inhibitor Ro 31-7549 (Fig. lB, bottom).At this concentration (30 p ~ )R,o 31-7549specifically inhibits p47 phosphorylation in response to thrombin

Summary

Introduction

High levels of fluid shear stress at the blood vessel wall directly stimulate von Willebrand factor (vWF)mediated platelet adhesion and aggregation and thereby contribute to the pathogenesis of arterial thrombosis. Shear-induced p47 phosphorylation depends entirely on vWF binding to platelet glycoprotein (Gp) Ib and GpIIb-IIIa, and the specific inhibition of protein kinase C with the staurosporine analogue Ro 31-7549 inhibits the full aggregation response to shear. Shear stress-induced platelet p47 phosphorylation occurs independent of any measurable change in diacylglycerol mass or hydrolysis of phosphatidylinositol4,5-bisphosphate These results indicate that mechanical shear stress induces vWF to bind to platelet GpIb and GpIIb-IIIa, stimulating a diacylglycerol-independent pathway of protein kinase C activation that contributes to platelet aggregation in response to shear. We report that a pathological level of arterial wall shear stress induces diacylgylcerol-independent protein kinase C activation that depends on vWF binding to GpIb and GpIIb-IIIa, and that protein kinase C contributes to thefull aggregation response of platelets to shear stress. Escherichia coli diacylglycerol kinase was obtained from Lipidex (Westfield, NJ). p-Octylglucoside was obtained from Calbiochem (San Diego, CA), BAPTA from Molecular Probes (Eugene, OR), and all lipids were obtained from Avanti (Birmingham, AL)

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