GRK6 regulates the hemostatic response to injury through its rate-limiting effects on GPCR signaling in platelets.

Authors

Xi Chen, Thomas Jefferson UniversityFollow
Shuchi Gupta, University of Pennsylvania
Matthew Cooper, Thomas Jefferson UniversityFollow
Daniel DeHelian, University of Pennsylvania
Xuefei Zhao, Thomas Jefferson University; Soochow UniversityFollow
Meghna U. Naik, Thomas Jefferson UniversityFollow
Jeremy G.T. Wurtzel, Thomas Jefferson UniversityFollow
Timothy J. Stalker, University of Pennsylvania
Lawrence E. Goldfinger, Thomas Jefferson UniversityFollow
Jeffrey Benovic, Thomas Jefferson UniversityFollow
Lawrence F. Brass, University of Pennsylvania
Steven E. McKenzie, Thomas Jefferson UniversityFollow
Ulhas P. Naik, Thomas Jefferson UniversityFollow
Peisong Ma, Thomas Jefferson UniversityFollow

Document Type

Article

Publication Date

1-3-2020

Comments

This article is the author’s final published version in Blood Advances, Volume 4, Issue 1, January 2020, Pages 76-86.

The published version is available at https://doi.org/10.1182/bloodadvances.2019000467. Copyright © The American Society of Hematology

Publication made possible in part by support from the Thomas Jefferson University + Philadelphia University Open Access Fund

Abstract

G protein-coupled receptors (GPCRs) mediate the majority of platelet activation in response to agonists. However, questions remain regarding the mechanisms that provide negative feedback toward activated GPCRs to limit platelet activation and thrombus formation. Here we provide the first evidence that GPCR kinase 6 (GRK6) serves this role in platelets, using GRK6-/- mice generated by CRISPR-Cas9 genome editing to examine the consequences of GRK6 knockout on GPCR-dependent signaling. Hemostatic thrombi formed in GRK6-/- mice are larger than in wild-type (WT) controls during the early stages of thrombus formation, with a rapid increase in platelet accumulation at the site of injury. GRK6-/- platelets have increased platelet activation, but in an agonist-selective manner. Responses to PAR4 agonist or adenosine 5'-diphosphate stimulation in GRK6-/- platelets are increased compared with WT littermates, whereas the response to thromboxane A2 (TxA2) is normal. Underlying these changes in GRK6-/- platelets is an increase in Ca2+ mobilization, Akt activation, and granule secretion. Furthermore, deletion of GRK6 in human MEG-01 cells causes an increase in Ca2+ response and PAR1 surface expression in response to thrombin. Finally, we show that human platelet activation in response to thrombin causes an increase in binding of GRK6 to PAR1, as well as an increase in the phosphorylation of PAR1. Deletion of GRK6 in MEG-01 cells causes a decrease in PAR1 phosphorylation. Taken together, these data show that GRK6 regulates the hemostatic response to injury through PAR- and P2Y12-mediated effects, helping to limit the rate of platelet activation during thrombus growth and prevent inappropriate platelet activation.

Recommended Citation

Chen, Xi; Gupta, Shuchi; Cooper, Matthew; DeHelian, Daniel; Zhao, Xuefei; Naik, Meghna U.; Wurtzel, Jeremy G.T.; Stalker, Timothy J.; Goldfinger, Lawrence E.; Benovic, Jeffrey; Brass, Lawrence F.; McKenzie, Steven E.; Naik, Ulhas P.; and Ma, Peisong, "GRK6 regulates the hemostatic response to injury through its rate-limiting effects on GPCR signaling in platelets." (2020). Cardeza Foundation for Hematologic Research. Paper 52.
https://jdc.jefferson.edu/cardeza_foundation/52

Language

English