Thromb Haemost
DOI: 10.1055/s-0039-1692422
Cellular Haemostasis and Platelets
Georg Thieme Verlag KG Stuttgart · New York

Impaired Glycoprotein VI-Mediated Signaling and Platelet Functional Responses in CD45 Knockout Mice

Vaishali V. Inamdar
1  Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
,
John C. Kostyak
1  Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
,
Rachit Badolia
1  Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
,
Carol A. Dangelmaier
1  Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
,
Bhanu Kanth Manne
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
,
Soochong Kim
1  Sol Sherry Thrombosis Research Center, Lewis Katz School of Medicine, Temple 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
2  Department of Physiology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
3  Department of Pharmacology, Lewis Katz School of Medicine, Temple University, Philadelphia, Pennsylvania, United States
› Author Affiliations
Further Information

Publication History

10 August 2018

16 April 2019

Publication Date:
21 June 2019 (eFirst)

Abstract

Background and Objective CD45 is a receptor protein tyrosine phosphatase present on the surface of all hematopoietic cells except for erythrocytes and platelets. Proteomics studies, however, have demonstrated the presence of a CD45 c-terminal catalytic peptide in platelets. Therefore, we investigated the functional role of this truncated isoform of CD45 in platelets, which contains the c-terminal catalytic domain but lacks the extracellular region.

Methods and Results We used an antibody specific to the c-terminus of CD45 to confirm the presence of a truncated CD45 isoform in platelets. We also examined ex vivo and in vivo platelet function using CD45 knockout (KO) mice. Aggregation and secretion mediated by the glycoprotein VI (GPVI) receptor was impaired in CD45 KO platelets. Consequently, CD45 KO mice had impaired hemostasis indicated by increased tail bleeding times. Also, using a model of pulmonary embolism we showed that CD45 KO mice had defective in vivo thrombus formation. Next, we investigated whether or not the truncated isoform of CD45 had a role in GPVI signaling. The full-length isoform of CD45 is known to regulate Src family kinase (SFK) activation in lymphocytes. We find a similar role for the truncated isoform of CD45 in platelets. SFK activation was impaired downstream of the GPVI receptor in the CD45 KO murine platelets. Consequently, Syk, PLCγ2, and pleckstrin phosphorylations were also impaired in CD45 KO murine platelets.

Conclusion We conclude that the truncated CD45 isoform regulates GPVI-mediated signaling and platelet functional responses by regulating SFK activation.

Authors' Contributions

V.V.I. designed and performed experiments, analyzed and interpreted data, and wrote the manuscript; J.C.K. performed experiments, analyzed data, and edited the manuscript. R.B., C.A.D., B.K.M., A.P., and S.K. performed experiments. S.P.K. designed experiments, analyzed data, and interpreted data.


Supplementary Material