Thromb Haemost 2004; 92(03): 606-613
DOI: 10.1160/TH04-04-0240
Platelets and Blood Cells
Schattauer GmbH

A novel mutation in the transmembrane region of glycoprotein IX associated with Bernard-Soulier syndrome

Zhaoyue Wang
1   Jiangsu Institute of Hematology,The First Affiliated Hospital of Soochow University, China
,
Xiaojuan Zhao
1   Jiangsu Institute of Hematology,The First Affiliated Hospital of Soochow University, China
,
Weiming Duan
1   Jiangsu Institute of Hematology,The First Affiliated Hospital of Soochow University, China
,
Jianxin Fu
1   Jiangsu Institute of Hematology,The First Affiliated Hospital of Soochow University, China
,
Mingen Lu
1   Jiangsu Institute of Hematology,The First Affiliated Hospital of Soochow University, China
,
Giamin Wang
1   Jiangsu Institute of Hematology,The First Affiliated Hospital of Soochow University, China
,
Xia Bai
1   Jiangsu Institute of Hematology,The First Affiliated Hospital of Soochow University, China
,
Changgeng Ruan
1   Jiangsu Institute of Hematology,The First Affiliated Hospital of Soochow University, China
› Institutsangaben

Financial support: This study was supported in part by a grant to Z. Wang from the Natural Science Foundation of China number 38970343, Beijing, China
Weitere Informationen

Publikationsverlauf

Received 16. April 2004

Acccepted after revision 13. Juni 2004

Publikationsdatum:
30. November 2017 (online)

Preview

Summary

We describe here a novel mutation in glycoprotein (GP) IX transmembrane region in a patient with Bernard-Soulier syndrome (BSS). Flow cytometric analysis of the patient’s platelets showed that GP Iba and GP IX were expressed at decreased levels. Sequence analysis of the gene coding for GP IX revealed a homozygous (G to A) transition at nucleotide 2113, resulting in a Ala 140 (GCC) to Thr (ACC) replacement in the mature peptide, whereas no defects were found in the coding region of the GP Iba and GP Ib? gene. Allele-specific restriction enzyme analysis using HPYCH4 III revealed that the patient was homozygous and her mother and brother were heterozygous for the defect, and excluded the possibility that the mutation was a polymorphism of GP IX.To clarify the effect of this mutation on the surface expression of the GP Ib/IX complex, we introduced this mutation into the cDNA of GP IX by site-directed mutagenesis and performed in vitro transfection studies with plasmids harboring GP Iba, GP Ib? and wild-type GP IX or mutant GP IX. Mutant GP IX decreased the surface expression of GP Iba and GP IX, whereas both immunostaining and immunoblotting of the transfected Chinese hamster ovary (CHO) cells showed abundant GP Iba and GP IX in the cytoplasm of the CHO cells transfected with plasmids harboring GP Iba, GP Ib? and wild-type GP IX or mutant GP IX These findings indicate that the Ala140→Thr mutation in the transmembrane region of GP IX does not induce intracellular GP Ib/IX complex degradation, but prevents its insertion in the cytoplasmic membrane of platelets and CHO cells.