Cationic zinc is required for factor XII recruitment and activation by stimulated platelets and for thrombus formation in vivo. (30th July 2020)

• Record Type: Journal Article
• Authors: Chaudhry, Sharjeel A.; Serrata, Matthew; Tomczak, Lindsay; Higgins, Sarah; Ryu, Justine; Laprise, Dylan; Enjyoji, Keiichi; Bekendam, Roelof; Kaushik, Virendar; Flaumenhaft, Robert; Bendapudi, Pavan K.
• Is Part Of: Journal of thrombosis and haemostasis. Volume 18:Number 9(2020)
• Page Start: 2318
• Page End: 2328
• Publication Date: 2020-07-30
• Subjects: contact pathway -- factor XII -- FXII knockout mice -- platelet‐dependent thrombin generation -- zinc; Thrombosis -- Periodicals; Hemostasis -- Periodicals; Blood coagulation disorders -- Periodicals; 616.1
• DOI: 10.1111/jth.14964
• Languages: English
• ISSNs: 1538-7933

Abstract

Abstract: Background: Although divalent zinc (Zn 2+ ) is known to bind factor (F)XII and affect its sensitivity to autoactivation, little is known about the role of Zn 2+ in the binding of FXII to platelets, where FXII activation is thought to occur in vivo, and the function of Zn 2+ during thrombus formation following vascular injury remains poorly understood. Objectives: To evaluate the role of Zn 2+ in platelet‐dependent FXIIa generation. Methods: FXII binding to platelets and FXII activation by stimulated platelets were assessed using flow cytometry and a platelet‐dependent thrombin generation assay. The mouse cremaster laser injury model was used to evaluate the impact of Zn 2+ chelation on thrombus formation in vivo. Results: Our data demonstrate that stimulated platelets support FXII‐dependent thrombin generation and that FXII activation by platelets requires the presence of Zn 2+ . By contrast, thrombin generation by stimulated endothelial cells occurred independently of FXII and Zn 2+ . Using flow cytometry, we found that FXII‐fluorescein‐5‐isothiocyanate binds to the surfaces of stimulated platelets in a specific and Zn 2+ ‐dependent manner, whereas resting platelets demonstrated minimal binding. Other physiologically‐relevant divalent cations are unable to support this interaction. Consistent with these findings, the Zn 2+ ‐specific chelator ethylenediaminetetraacetic acid calcium disodium salt confers thromboprotection in the mouse cremaster laser injury model without causing increased bleeding. We observed an identical phenotype in FXII null mice tested in the same system. Conclusions: Our results suggest a novel role for Zn 2+ in the binding and activation of FXII at the platelet surface, an interaction that appears crucial to FXII‐dependent thrombin generation but dispensable for hemostasis.