Thromb Haemost 2006; 95(02): 243-252
DOI: 10.1160/TH05-08-0561
Platelets and Blood Cells
Schattauer GmbH

The serpin proteinase inhibitor 8: An endogenous furin inhibitor released from human platelets

Julie Leblond
1   Immunology Division, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Qc, Canada
,
Marie-Hélène Laprise
1   Immunology Division, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Qc, Canada
,
Simon Gaudreau
1   Immunology Division, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Qc, Canada
,
Francine Grondin
1   Immunology Division, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Qc, Canada
,
Walter Kisiel
2   Department of Pathology, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
,
Claire M. Dubois
1   Immunology Division, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Qc, Canada
› Author Affiliations

Financial support: This work was supported by the Canadian Institutes of Health research grant #MOP-5309-(TO C. M. D. ). J. L. is a recipient of a doctoral award from the Canadian Institutes of Health research.
Further Information

Publication History

Received 16 August 2005

Accepted after resubmission 28 January 2005

Publication Date:
28 November 2017 (online)

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Summary

The cornerstone of hemostasis is the ability of the organism to limit the enzymatic processes involved, thereby avoiding thrombosis. For this, anticoagulant systems in place involve serpins, such as PAI-1 and antithrombin III, which bind to their targeted serine proteases and limit their period of activity. We have previously identified the serine protease furin as a platelet-derived enzyme with an intrinsic role in platelet functions. We now report that furin enzymatic activity decreased rapidly following platelet activation, corresponding with the increase in formation of a high 180 M r SDS-stable complex composed of furin and the PI8 serpin. PI8 is shown to be a platelet-derived constituent, synthesized by megakaryocytes and stored in platelets prior to its release. Immunoprecipitation and purification of the PI8-furin complex confirmed their direct interaction and indicates that one of the roles of PI8 is to inhibit furin enzymatic activity. Furthermore, our findings demonstrate the inhibitory capacity of exogenous PI8 in platelet aggregation assays. The finding that PI8 is released by platelets and controls functional responses suggests a role for this serpin in platelet-regulated pathophysiological responses.