1. Ser252Asn Mutation Introduces a New N-Linked Glycosylation Site and Causes Type IIb Protein C Deficiency.
- Author
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Zhou S, Wu X, Song Y, Li L, Shi C, Lai Z, Ding Q, Wu W, Dai J, Wang X, and Lu Y
- Subjects
- Humans, Glycosylation, Female, Mutation, Thrombomodulin genetics, Thrombomodulin metabolism, Thrombomodulin chemistry, Thrombosis genetics, Thrombosis blood, HEK293 Cells, Animals, Protein Binding, Serine, Male, Heterozygote, Protein C metabolism, Protein C genetics, Protein C chemistry, Protein C Deficiency genetics, Blood Coagulation genetics, Thrombin metabolism
- Abstract
Background: Protein C (PC) is a vitamin K-dependent anticoagulant serine protease zymogen which upon activation by the thrombin-thrombomodulin (TM) complex downregulates the coagulation cascade by degrading cofactors Va and VIIIa by limited proteolysis. We identified a thrombosis patient who carried a heterozygous mutation c.881G > A, p.Ser252Asn (S252N) in PROC . This mutation was originally described in a report of novel mutations in patients presenting with defective PC anticoagulant activity in Paris. The research identified PC-S252N (the "Paris" mutation) in a propositus and her family members and highlighted the critical role of Ser252 in the anticoagulation process of activated PC (APC)., Material and Methods: We expressed the PC-S252N mutant in mammalian cells and characterized the properties in coagulation assays to decipher the molecular basis of anticoagulant defect of this mutation., Results: We demonstrated that PC-S252N had a diminished ability to TM binding, which resulted in its impaired activation by the thrombin-TM complex. However, APC-S252N exhibited a slightly stronger cleavage capacity for the chromogenic substrate. Meanwhile, the catalytic activity of APC-S252N toward FVa was significantly reduced. Sequence analysis revealed that Ser252 to Asn substitution introduced a new potential N-linked glycosylation site (
252 NTT254 ) in the catalytic domain of PC, which adversely affected both the activation process of PC and anticoagulant activity of APC., Conclusion: The new N-glycosylation site (252 NTT254 ) resulting from the mutation of Ser252 to Asn252 in PROC affects the overall structure of the protease, thereby adversely affecting the anticoagulant function of protein C. This modification has a negative impact on both TM-promoted activation of protein C and APC cleavage of FVa, ultimately leading to thrombosis in the patient., Competing Interests: None declared., (Thieme. All rights reserved.)- Published
- 2024
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