Clin Res Cardiol (2022). https://doi.org/10.1007/s00392-022-02002-5

Platelet-specific deletion of catalytic α subunit of Casein Kinase 2 (Csnk2α) results in a robust protection against GPVI-dependent arterial thrombosis and myocardial ischemia/reperfusion injury
M.-C. Manke1, F. Kollotzek1, J. P. Schütte1, C. Liang2, S. Geue1, P. Münzer3, T. Dandekar2, A. Sickmann4, M. Gawaz1, S. Loroch4, O. Borst1
1Department of Cardiology and Cardiovascular Medicine, University of Tübingen, Tübingen; 2Department of bioinformatics, University of Würzburg, Würzburg; 3Boston Children’s Hospital, Harvard Medical School, Boston, US; 4Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Dortmund;

Background: Thrombo-occlusive disorders such as myocardial infarction or ischemic stroke and accompanying ischemia/reperfusion injuries are crucially dependent on platelet adhesion, secretion and aggregation. Thereby, platelet activation is affected by a wide variety of intracellular phosphorylation-dependent signaling cascades. The tetrameric serine/threonine kinase casein kinase 2 (CK2) is highly expressed in platelets and is composed of two regulatory β and two catalytic α or α’ subunits respectively. While deficiency of the regulatory β subunit is associated with impaired thrombopoiesis and platelet function, nothing is known about the role of the α subunit during platelet activation and thrombus formation.

Aims: Thus, the present study investigated the impact of the CK2 catalytic α subunit on platelet activation and thrombus formation.

Methods and Results: Using platelet-specific CK2α-deficient mice (csnk2αPf4∆/Pf4∆) and corresponding wild-type littermates (csnk2αlox/lox), flow cytometric analysis revealed an impaired integrin αIIbβ3 activation and P-selectin surface exposure in platelets from csnk2αPf4∆/Pf4∆ mice upon stimulation with collagen-related peptide (CRP), which serves as GPVI-specific platelet agonist. Consequently, platelet aggregation and dense granule secretion was diminished in csnk2αPf4∆/Pf4∆ mice in a CRP-dependent fashion when compared to wild-type littermates as verified by lumino-aggregometry. In CK2α-deficient platelets, activation-dependent time-courses of phospho-proteomic approaches revealed a significant CK2a-dependent regulation of phosphorylation of intracellular proteins in platelets strongly associated with cytoskeletal rearrangement and calcium signaling. Indeed, DIC-microscopy analysis showed diminished platelet spreading on a fibrinogen-coated surface and serial spectrofluorimetric measurements detected a significantly decreased intracellular Ca2+ release and extracellular Ca2+ influx after CRP stimulation in CK2α-deficient cells. In line with these findings, we observed a defective arterial thrombus formation in a flow chamber using a collagen-coated surface and in a murine model of FeCl3-induced carotid artery injury in csnk2αPf4∆/Pf4∆ mice when compared to csnk2αlox/lox mice. Even more importantly, csnk2αPf4∆/Pf4∆ mice displayed a significantly decreased infarct size, a better cardiac output and an increased stroke volume in a myocardial ischemia/reperfusion model after 7 days of reperfusion when compared to csnk2αPf4∆/Pf4∆ mice. Of note, there was no difference in the bleeding time in both groups of mice when employing a tail tip transection model.

Conclusions: The present study discloses CK2α as pivotal regulator of platelet activation with subsequent thrombus formation and ischemia/reperfusion injury. Since CK2α deficiency does not affect the bleeding time of mice, CK2 may thus represent a promising new pharmacological target for the treatment of thrombo-occlusive diseases circumventing the bleeding complications of the most common current treatment regimens.


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