Amplification of human platelet activation by surface pannexin-1 channels..pdf (1.57 MB)
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Amplification of human platelet activation by surface pannexin-1 channels

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journal contribution
posted on 14.10.2015, 10:22 by K. A. Taylor, J. R. Wright, C. Vial, Richard J. Evans, M. P. Mahaut-Smith
BACKGROUND: Pannexin-1 (Panx1) forms an anion-selective channel with a permeability up to ~1 kDa and represents a non-lytic, non-vesicular ATP release pathway in erythrocytes, leukocytes and neurons. Related connexin gap junction proteins have been reported in platelets; however, the expression and function of the pannexins remain unknown. OBJECTIVE: To determine the expression and function of pannexins in human plate-lets, using molecular, cellular and functional techniques. METHODS: Panx1 expression in human platelets was det-ermined using qPCR and antibody-based techniques. Contributions of Panx1 to agonist-evoked efflux of cytoplasmic calcein, Ca(2+) influx, ATP release and aggregation were assessed in washed platelets under conditions where the P2X1 receptor response was preserved (0.32 U mL(-1) apyrase). Thrombus formation in whole blood was assessed in vitro using a shear chamber assay. Two structurally unrelated and widely used Panx1 inhibitors, probenecid and carbenoxolone, were used throughout this study, at concentrations that do not affect connexin channels. RESULTS: PANX1, but not PANX2 or PANX3, mRNA was detected in human platelets. Furthermore, Panx1 protein is glycosylated and present on the plasma membrane of platelets, and displays weak physical association with P2X1 receptors. Panx1 inhibition blocked thrombin-evoked efflux of calcein, and reduced Ca(2+) influx, ATP release, platelet aggregation and thrombus formation under arterial shear rates in vitro. The Panx1-dependent contribution was not additive to that of P2X1 receptors. CONCLUSIONS: Panx1 is expressed on human platelets and amplifies Ca(2+) influx, ATP release and aggregation through the secondary activation of P2X1 receptors. We propose that Panx1 represents a novel target for the management of arterial thrombosis.

History

Citation

Journal of Thrombosis and Haemostasis, 2014, 12 (6), pp. 987-998

Author affiliation

/Organisation/COLLEGE OF MEDICINE, BIOLOGICAL SCIENCES AND PSYCHOLOGY/MBSP Non-Medical Departments/Molecular & Cell Biology

Version

VoR (Version of Record)

Published in

Journal of Thrombosis and Haemostasis

eissn

1538-7836

Acceptance date

04/03/2014

Copyright date

2014

Available date

14/10/2015

Publisher version

http://onlinelibrary.wiley.com/doi/10.1111/jth.12566/abstract

Language

en