Thromb Haemost 2007; 98(06): 1257-1265
DOI: 10.1160/TH07-04-0248
Platelets and Blood Cells
Schattauer GmbH

Disulfide bond disruption by a β3-Cys549Arg mutation in six Jordanian families with Glanzmann thrombasthenia causes diminished production of constitutively active αIIbβ3

Ronit Mor-Cohen*
1   Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel-Hashomer and Sackler School of Medicine, Tel Aviv University, Israel
,
Nurit Rosenberg*
1   Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel-Hashomer and Sackler School of Medicine, Tel Aviv University, Israel
,
Hava Peretz
2   Clinical Biochemistry Laboratory, Sourasky Medical Center, Tel-Aviv, Israel
,
Meytal Landau
1   Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel-Hashomer and Sackler School of Medicine, Tel Aviv University, Israel
3   Department of Biochemistry, George S.Wise Faculty of Life Sciences, Tel Aviv University, Israel
,
Barry S. Coller
4   Laboratory of Blood and Vascular Biology, Rockefeller University New York, New York, USA
,
Abdalla Awidi
5   Rawhi medical Center, Amman, Jordan
,
Uri Seligsohn
1   Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel-Hashomer and Sackler School of Medicine, Tel Aviv University, Israel
› Author Affiliations

Financial support: This study was supported, in part, by grant 19278 from the Heart Lung and Blood Institute.
Further Information

Publication History

Received 05 April 2007

Accepted after resubmission 17 October 2007

Publication Date:
30 November 2017 (online)

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Summary

αIIbβ3 integrin mediates platelet aggregation following its activation. Its absence or dysfunction causes Glanzmann thrombasthenia (GT), an inherited bleeding disorder that is rare worldwide but relatively frequent in several populations with high rates of consanguinity, including Arabs in Israel and Jordan. Cysteine residues in the β3 epidermal growth factor (EGF) domains are involved in αIIbβ3 formation and activation. In this study we present a novel Cys549Arg mutation in β3 identified in six Jordanian families, which in the homozygous state is manifested by severe GT. The mutation is located in EGF-3 of β3 predicting disruption of a conserved disulfide bond between Cys549 and Cys558. Haplotype analysis disclosed a common founder whose age estimate was 120–150 years. Flow cytometry revealed 1–14% of normal αIIbβ3 expression at the patients' platelet surface. The Cys549Arg or artificial Cys549Ser mutations were introduced into a β3 expression vector. Co-transfection of baby hamster kidney cells with normal or mutant β3 along with normal αIIb demonstrated reduced surface expression of αIIbβ3 by both mutants. The mutants were constitutively active as demonstrated by 20-fold increased binding of the ligand-mimetic antibody PAC-1. Immunoblotting and immunoprecipitation experiments showed reduced β3 and αIIbβ3 expression and a higher than normal ratio of pro-αIIb to mature αIIb. Immunofluorescence experiments showed that β3 and αIIbβ3 were mostly retained in the endoplasmic reticulum. In conclusion, the novel ancestral mutation found in a cluster of Jordanian GT patients disrupts a conserved Cys549-Cys558 bond which results in reduced production of constitutively active αIIbβ3.

* These authors contributed equally to this work.