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Cationic zinc is required for factor XII recruitment and activation by stimulated platelets and for thrombus formation in vivo
Author(s) -
Chaudhry Sharjeel A.,
Serrata Matthew,
Tomczak Lindsay,
Higgins Sarah,
Ryu Justine,
Laprise Dylan,
Enjyoji Keiichi,
Bekendam Roelof,
Kaushik Virendar,
Flaumenhaft Robert,
Bendapudi Pavan K.
Publication year - 2020
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/jth.14964
Subject(s) - chemistry , platelet , thrombin , platelet activation , factor xii , divalent , in vivo , flow cytometry , biophysics , thrombus , coagulation , biochemistry , microbiology and biotechnology , immunology , medicine , biology , organic chemistry
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.