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DOI: 10.1055/a-2569-6439
Asn384Ser Mutation in Protein C is Associated with Multiple-Site Thrombosis in a Young Heterozygous Male
Funding This study was supported by Shanghai Natural Science Foundation Program (22ZR1439500), and the General Program of National Natural Science Foundation of China (81870107) to YL; Young Talent Support Program of College of Health Science and Technology, Shanghai Jiao Tong University School of Medicine (YX20230015) to XW; the General Program of National Natural Science Foundation of China (82070137) to XW; and the General Program of National Natural Science Foundation of China (81970127) to JD.
Abstract
Background
Protein C (PC) is an important physiological anticoagulant factor in humans. Activated protein C (APC) is generated from the PC zymogen through proteolytic activation by thrombin. APC inhibits thrombin generation by inactivating activated factors V and VIII via limited proteolysis. In addition to its anticoagulant function, APC also exhibits potent cytoprotective and anti-inflammatory properties. We have identified a young male with multiple-site thrombosis, who carries a heterozygous mutation c.1151A > G,p.Asn384Ser(N384S) in PC. Although this mutation has been previously documented, limited functional research has been conducted to elucidate its pathogenesis.
Objective
To elucidate the functional alternations of the N384S mutant protein C and delineate the molecular mechanism underlying thrombosis in the patient carrying this mutation.
Methods
We expressed the recombinant PC-N384S in mammalian cells and characterized its properties in established coagulation and anti-inflammatory assay systems.
Results
The expression level of the PC-N384S was reduced to approximately 7% of that observed for PC-WT. The activation of PC-N384S by thrombin or thrombin–thrombomodulin (TM) complex was significantly impaired, although the addition of TM exhibited a slight enhancement in the activation process. In terms of cleaving a chromogenic substrate, the catalytic efficiency reduced to approximately 50% of that observed in the wild type. In addition, in comparison with APC-WT, APC-N384S demonstrated a pronounced decline in amidolytic activity following an extended incubation period at 37°C. APC-N384S exhibited slightly impaired anticoagulant activity in either FVa inhibition assay or plasma-based assay systems. Furthermore, anti-inflammatory activity of APC-N384S was dramatically impaired as determined by evaluating the barrier-protective effect.
Conclusion
The Asn384Ser mutation impairs both the anticoagulant and barrier-protective activities of protein C, thereby increasing the thrombosis risk in the heterozygous young male.
Authors' Contribution
J.Y. performed the research and wrote the manuscript; X.W. performed genetic analysis and coagulation assays of the subjects' plasma; F.L. performed structural analyses; S.Z. and Z.L. performed research; Q.D., W.W., and X.W. collected and provided clinical data; J.D. and X.H. supervised studies; and L.Y. designed experiments, analyzed data, supervised the project, and revised the manuscript. All authors approved the final version of this manuscript.
* These authors contributed equally to this work.
Publication History
Received: 17 December 2024
Accepted: 30 March 2025
Article published online:
18 April 2025
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