Thromb Haemost 2020; 120(11): 1536-1547
DOI: 10.1055/s-0040-1714745
Cellular Haemostasis and Platelets

PAK Membrane Translocation and Phosphorylation Regulate Platelet Aggregation Downstream of Gi and G12/13 Pathways

Jianjun Zhang*
1  Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
,
Yan Zhang*
1  Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
,
Shuang Zheng
1  Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
,
Yangyang Liu
2  Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
,
Lin Chang
1  Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
,
Guanxing Pan
1  Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
,
Liang Hu
2  Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
,
Si Zhang
1  Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
,
Junling Liu
3  Department of Biochemistry and Molecular Biology, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
,
Soochong Kim
4  College of Veterinary Medicine, Chungbuk National University, Cheongju, Korea
,
Jianzeng Dong
2  Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
,
Zhongren Ding
1  Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Fudan University, Shanghai, China
2  Department of Cardiology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
› Author Affiliations
Funding This work was partially supported by the National Natural Science Foundation of China (grant numbers: 81673429, 81872862, and 81402920) to Z.D. and Y.Z. and Startup Fund from The First Affiliated Hospital of Zhengzhou University to Z.D.

Abstract

Platelet activation plays a pivotal role in physiological hemostasis and pathological thrombosis causing heart attack and stroke. Previous studies conclude that simultaneous activation of Gi and G12/13 signaling pathways is sufficient to cause platelet aggregation. However, using Gq knockout mice and Gq-specific inhibitors, we here demonstrated that platelet aggregation downstream of coactivation of Gi and G12/13 depends on agonist concentrations; coactivation of Gi and G12/13 pathways only induces platelet aggregation under higher agonist concentrations. We confirmed Gi and G12/13 pathway activation by showing cAMP (cyclic adenosine monophosphate) decrease and RhoA activation in platelets stimulated at both low and high agonist concentrations. Interestingly, we found that though Akt and PAK (p21-activated kinase) translocate to the platelet membrane upon both low and high agonist stimulation, membrane-translocated Akt and PAK only phosphorylate at high agonist concentrations, correlating well with platelet aggregation downstream of concomitant Gi and G12/13 pathway activation. PAK inhibitor abolishes Akt phosphorylation, inhibits platelet aggregation in vitro and arterial thrombus formation in vivo. We propose that the PAK-PI3K/Akt pathway mediates platelet aggregation downstream of Gi and G12/13, and PAK may represent a potential antiplatelet and antithrombotic target.

Authors' Contributions

Conceptualization: Z.D.; methodology: J.Z., Y.Z., and L.H.; investigation: J.Z., Y.Z., Sh.Z., L.C., G.P., L.H., S.Z., and Z.D.; resources: Z.D. and J.D.; mouse models: J.L.; writing—original draft: Y.Z., J.Z., and Z.D.; writing—review and editing: Z.D. and S.K.; supervision: Z.D.; funding acquisition: Z.D. and Y.Z.


* These authors contributed equally to this study.


Supplementary Material



Publication History

Received: 24 December 2019

Accepted: 25 June 2020

Publication Date:
27 August 2020 (online)

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