CC BY 4.0 · TH Open 2018; 02(04): e411-e419
DOI: 10.1055/s-0038-1676358
Original Article
Georg Thieme Verlag KG Stuttgart · New York

TULA-2 Deficiency Enhances Platelet Functional Responses to CLEC-2 Agonists

John C. Kostyak
1   Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
,
Benjamin R. Mauri
1   Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
,
Carol Dangelmaier
1   Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
,
Akruti Patel
1   Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
,
Yuhang Zhou
2   Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
,
Johannes A. Eble
3   Institute of Physiological Chemistry and Pathobiochemistry, University of Munster, Waldeyerstasse, Munster, Germany
,
Alexander Y. Tsygankov
1   Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
4   Department of Immunology and Microbiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
,
Steven E. McKenzie
2   Cardeza Foundation for Hematologic Research, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania, United States
,
Satya P. Kunapuli
1   Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
› Institutsangaben
Funding This work was supported by grants from the National Institutes of Health (HL93231, HL132171, HL137207, and HL137721) to S. P. K., the American Heart Association (17SDG33370020) to J. C. K. and by Deutsche Forschungsgemeinschaft (DFG grant: Eb177/13–1) to J. A. E.
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Publikationsverlauf

15. Juli 2018

10. Oktober 2018

Publikationsdatum:
05. Dezember 2018 (online)

Abstract

Platelet activation is essential for hemostasis. Central to platelet activation are the signals transmitted through surface receptors such as glycoprotein VI, the protease-activated receptors, and C-type lectin-like receptor 2 (CLEC-2). CLEC-2 is a HemITAM (hem-immunoreceptor tyrosine activation motif)-bearing receptor that binds podoplanin and signals through spleen tyrosine kinase (Syk). T-cell ubiquitin ligand-2 (TULA-2) is a protein tyrosine phosphatase that is highly expressed in platelets and targets phosphorylated Y352 of Syk. We wanted to determine whether TULA-2 regulates Syk phosphorylation and activity downstream of CLEC-2. To that end, we used TULA-2 knockout mice and wild-type (WT) littermate controls. We found that TULA-2 deficiency enhances the aggregation and secretion response following stimulation with an excitatory CLEC-2 antibody or the CLEC-2 agonist rhodocytin. Consistently, Syk phosphorylation of Y346 is enhanced, as well as phosphorylation of the downstream signaling molecule PLCγ2, in TULA-2 knockout platelets treated with either CLEC-2 antibody or rhodocytin, compared with WT control platelets. Furthermore, the kinetics of Syk phosphorylation, as well as that of PLCγ2 and SLP-76, is enhanced in TULA-2 knockout platelets treated with 2.5-μg/mL CLEC-2 antibody compared with WT platelets. Similarly, thromboxane production was enhanced, in both amount and kinetics, in TULA-2−/− platelets treated with 2.5-μg/mL CLEC-2 antibody. TULA-2 acts as a negative regulator of CLEC-2 signaling by dephosphorylating Syk on Y346 and restraining subsequent Syk-mediated signaling.