1
Department of Internal Medicine, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
,
Neha Bhasin
2
Department of Pediatrics, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
,
Edward F. Plow
3
Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Department of Molecular Cardiology, Cleveland Clinic, Cleveland, Ohio, USA
,
Pier Paolo Pandolfi
4
Cancer Research Institute, Beth Israel Deaconess Cancer Center, Departments of Medicine and Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
,
Paul B. Rothman
5
Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
,
Anil K. Chauhan
1
Department of Internal Medicine, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
,
Steven R. Lentz
1
Department of Internal Medicine, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
› Author AffiliationsFinancial Support: This work was supported by grants from the National Cancer Institute (CA134671) to PR and MN and the National Heart, Lung, and Blood Institute (HL118246 and HL118742 to AKC, HL062984 to SRL, and HL080070), a grant from the American Society of Hematology to SRL, and an American Heart Association postdoctoral award to HJ.
Adaptor proteins play a critical role in the assembly of signalling complexes after engagement of platelet receptors by agonists such as collagen, ADP and thrombin. Recently, using proteomics, the Dok (downstream of tyrosine kinase) adapter proteins were identified in human and mouse platelets. In vitro studies suggest that Dok-1 binds to platelet integrin β3, but the underlying effects of Dok-1 on αIIbβ3 signalling, platelet activation and thrombosis remain to be elucidated. In the present study, using Dok-1-deficient (Dok-1-/-) mice, we determined the phenotypic role of Dok-1 in αIIbβ3 signalling. We found that platelets from Dok-1-/- mice displayed normal aggregation, activation of αIIβ3 (assessed by binding of JON/A), P-selectin surface expression (assessed by anti-CD62P), and soluble fibrinogen binding. These findings indicate that Dok-1 does not affect “inside-out” platelet signalling. Compared with platelets from wild-type (WT) mice, platelets from Dok-1-/- mice exhibited increased clot retraction (p < 0.05 vs WT), increased PLCγ2 phosphorylation, and enhanced spreading on fibrinogen after thrombin stimulation (p < 0.01 vs WT), demonstrating that Dok-1 negatively regulates αIIbβ3 “outside-in” signalling. Finally, we found that Dok-1-/- mice exhibited significantly shortened bleeding times and accelerated carotid artery thrombosis in response to photochemical injury (p < 0.05 vs WT mice). We conclude that Dok-1 modulates thrombosis and haemostasis by negatively regulating αIIbβ3 outside-in signalling.
Supplementary Material to this article is available online at www.thrombosis-online.com.
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