VWF-Gly2752Ser, a novel non-cysteine substitution variant in the CK domain, exhibits severe secretory impairment by hampering C-terminal dimer formation.

Abstract

BACKGROUND:

Von Willebrand factor (VWF) is a multimeric glycoprotein that plays important roles in hemostasis and thrombosis. C-terminal interchain-disulfide bonds in the cystine knot (CK) domain are essential for VWF dimerization. Previous studies have reported that missense variants of cysteine in the CK domain disrupt the intrachain-disulfide bond and cause type 3 von Willebrand disease (VWD). However, type 3 VWD-associated noncysteine substitution variants in the CK domain have not been reported.

OBJECTIVE:

To investigate the molecular mechanism of a novel non-cysteine variant in the CK domain, VWF c.8254 G>A (p.Gly2752Ser), which was identified in a patient with type 3 VWD as homozygous.

METHODS:

Genetic analysis was performed by whole exome sequencing and Sanger sequencing. VWF multimer analysis was performed using SDS-agarose electrophoresis. VWF production and subcellular localization were analyzed using ex vivo endothelial colony forming cells (ECFCs) and an in vitro recombinant VWF (rVWF) expression system.

RESULTS:

The patient was homozygous for VWF-Gly2752Ser. Plasma VWF enzyme-linked immunosorbent assay showed that the VWF antigen level of the patient was 1.2% compared with healthy subjects. A tiny amount of VWF was identified in the patient's ECFC. Multimer analysis revealed that the circulating VWF-Gly2752Ser presented only low molecular weight multimers. Subcellular localization analysis of VWF-Gly2752Ser-transfected cell lines showed that rVWF-Gly2752Ser was severely impaired in its ER-to-Golgi trafficking.

CONCLUSION:

VWF-Gly2752Ser causes severe secretory impairment because of its dimerization failure. This is the first report of a VWF variant with a noncysteine substitution in the CK domain that causes type 3 VWD.

• Authors: Shuichi Okamoto, Shogo Tamura, Naomi Sanda, Koya Odaira, Yuri Hayakawa, Masato Mukaide, Atsuo Suzuki, Takeshi Kanematsu, Fumihiko Hayakawa, Akira Katsumi, Hitoshi Kiyoi, Tetsuhito Kojima, Tadashi Matsushita, Nobuaki Suzuki
• Journal: Journal of thrombosis and haemostasis : JTH (J Thromb Haemost) Vol. 20 Issue 8 Pg. 1784-1796 (08 2022) ISSN: 1538-7836 [Electronic] England
• PMID: 35491445 (Publication Type: Journal Article)
• Copyright: © 2022 International Society on Thrombosis and Haemostasis.

Chemical References

• von Willebrand Factor
• Cystine
• Cysteine

Topics

• Cysteine (chemistry)
• Cystine
• Humans
• Protein Domains
• Protein Multimerization
• von Willebrand Disease, Type 3
• von Willebrand Factor (genetics)