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AGK Potentiates Arterial Thrombosis by Affecting Talin-1 and αIIbβ3-Mediated Bidirectional Signaling Pathway
Peng Zhang1, Haojie Jiang2, Mina Yang2
1Department of Cardiology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, China (P.Z., C.B., K.Z., D.L., M.W., Z.J., T.Z., J.Z.).
Background:
AGK (acylglycerol kinase) was first identified as a mitochondrial transmembrane protein that exhibits a lipid kinase function. Recent studies have established that AGK promotes cancer growth and metastasis, enhances glycolytic metabolism and function fitness of CD8+ T cells, or regulates megakaryocyte differentiation. However, the role of AGK in platelet activation and arterial thrombosis remains to be elaborated.
Methods:
We performed hematologic analysis using automated hematology analyzer and investigated platelets morphology by transmission electron microscope. We explored the role of AGK in platelet activation and arterial thrombosis utilizing transgenic mice, platelet functional experiments in vitro, and thrombosis models in vivo. We revealed the regulation effect of AGK on Talin-1 by coimmunoprecipitation, mass spectrometry, immunofluorescence, and Western blot. We tested the role of AGK on lipid synthesis of phosphatidic acid/lysophosphatidic acid and thrombin generation by specific Elisa kits.
Results:
In this study, we found that AGK depletion or AGK mutation had no effect on the platelet average volumes, the platelet microstructures, or the expression levels of the major platelet membrane receptors. However, AGK deficiency or AGK mutation conspicuously decreased multiple aspects of platelet activation, including agonists-induced platelet aggregation, granules secretion, JON/A binding, spreading on Fg (fibrinogen), and clot retraction. AGK deficiency or AGK mutation also obviously delayed arterial thrombus formation but had no effect on tail bleeding time and platelet procoagulant function. Mechanistic investigation revealed that AGK may promote Talin-1Ser425 phosphorylation and affect the αIIbβ3-mediated bidirectional signaling pathway. However, AGK does not affect lipid synthesis of phosphatidic acid/lysophosphatidic acid in platelets.
Conclusions:
AGK, through its kinase activity, potentiates platelet activation and arterial thrombosis by promoting Talin-1 Ser425 phosphorylation and affecting the αIIbβ3-mediated bidirectional signaling pathway.
Insights
Acylglycerol kinase (AGK) is crucial for platelet activation and arterial thrombosis. AGK promotes Talin-1 phosphorylation, enhancing platelet aggregation and thrombus formation without affecting bleeding time.
Area of Science:
- Biochemistry
- Hematology
- Molecular Biology
Background:
- Acylglycerol kinase (AGK) is a mitochondrial protein with lipid kinase function.
- AGK is implicated in cancer, T cell metabolism, and megakaryocyte differentiation.
- The role of AGK in platelet activation and arterial thrombosis requires further investigation.
Purpose of the Study:
- To elucidate the function of AGK in platelet activation.
- To investigate the role of AGK in arterial thrombosis.
- To determine the molecular mechanisms underlying AGK's effects on platelets.
Main Methods:
- Hematologic analysis and platelet morphology assessment (TEM).
- In vitro platelet functional assays and in vivo thrombosis models.
- Coimmunoprecipitation, mass spectrometry, immunofluorescence, and Western blot to study Talin-1 regulation.
- ELISA kits for lipid synthesis and thrombin generation.
Main Results:
- AGK deficiency or mutation impaired platelet activation (aggregation, secretion, spreading, clot retraction).
- AGK deficiency delayed arterial thrombus formation but did not affect bleeding time or procoagulant function.
- AGK promotes Talin-1 Ser425 phosphorylation, impacting the αIIbβ3 signaling pathway, but not platelet lipid synthesis.
Conclusions:
- AGK potentiates platelet activation and arterial thrombosis via its kinase activity.
- AGK's mechanism involves promoting Talin-1 phosphorylation and influencing the αIIbβ3 signaling pathway.
- AGK is a key regulator of platelet function in thrombosis.
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