Affiliation:
1. Department of Cardiology and Angiology, University Hospital Tübingen, Eberhard Karls University Tübingen, Tübingen, Germany
2. Department of Pharmaceutical and Medicinal Chemistry, Institute of Pharmaceutical Sciences, University of Tübingen, Tübingen, Germany
Abstract
Introduction Hemolysis results in release of free hemoglobin and hemin liberation from erythrocytes. Hemin has been described to induce platelet activation and to trigger thrombosis.
Methods We evaluated the effect of hemin on platelet function and surface expression of the platelet collagen receptor glycoprotein VI (GPVI). Isolated platelets were stimulated with increasing concentrations of hemin.
Results We found that hemin strongly enhanced platelet activation, aggregation, and aggregate formation on immobilized collagen under flow. In contrast, we found that surface expression of GPVI was significantly reduced upon hemin stimulation with high hemin concentrations indicating that hemin-induced loss of surface GPVI does not hinder platelet aggregation. Loss of hemin-induced surface expression of GPVI was caused by shedding of the ectodomain of GPVI as verified by immunoblotting and is independent of the GPVI or CLEC-2 mediated ITAM (immunoreceptor-tyrosine-based-activation-motif) signaling pathway as inhibitor studies revealed. Hemin-induced GPVI shedding was independent of metalloproteinases such as ADAM10 or ADAM17, which were previously described to regulate GPVI degradation. Similarly, concentration-dependent shedding of CD62P was also induced by hemin. Unexpectedly, we found that the subtilisin-like proprotein convertase furin controls hemin-dependent GPVI shedding as shown by inhibitor studies using the specific furin inhibitors SSM3 and Hexa-D-arginine. In the presence of SSM3 and Hexa-D-arginine, hemin-associated GPVI degradation was substantially reduced. Further, SSM3 inhibited hemin-induced but not CRP-XL-induced platelet aggregation and thrombus formation, indicating that furin controls specifically hemin-associated platelet functions.
Conclusion In summary, we describe a novel mechanism of hemin-dependent GPVI shedding and platelet function mediated by furin.
Funder
Deutsche Forschungsgemeinschaft
German Research Foundation
Cited by
4 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献