Blood, Vol. 95 No. 10 (May 15), 2000:
pp. 3139-3145
Conformational changes in the D' domain of von Willebrand
factor induced by CYS 25 and CYS 95 mutations lead to factor VIII
binding defect and multimeric impairment
Sylvie Jorieux,
Edith Fressinaud,
Jenny Goudemand,
Christine Gaucher,
Dominique Meyer,
Claudine Mazurier, and
the INSERM Network on
Molecular Abnormalities in von Willebrand Disease
From the Département Recherche et Développement,
Laboratoire Français du Fractionnement et des Biotechnologies,
Lille; Centre hospitalier universitaire (CHU), Nantes; Centre
hospitalier régional universitaire (CHRU), Hôpital Huriez,
Lille; and INSERM U143, Hôpital Bicêtre, Le
Kremlin-Bicêtre, France.
We report 2 new mutations identified in 3 patients and characterized
by the markedly decreased affinity of von Willebrand factor (vWF) for
factor VIII (FVIII). Patients 2 and 3, who have a typical type 2N
phenotype, were found to be compound heterozygous for Arg91Gln and
Cys25Tyr or Cys95Phe, respectively. Patient 1, who is the first cousin
of patient 2, had an FVIII binding defect of vWF, low levels of vWF,
and multimeric impairment. She was found to be compound heterozygous
for the mutations Cys25Tyr and a stop codon (D93ter) in exon 4. Transient expression of recombinant vWF (rvWF) containing either
Cys25Tyr or Cys95Phe mutations resulted in mutated rvWF with markedly
reduced FVIII binding ability, multimeric structure impairment, and a
significant decrease in the vWF expression level. Moreover, the use of
anti-vWF monoclonal antibodies that inhibit the FVIII binding showed
that these 2 mutations likely induce a conformational change in the
D' domain. These results show that the native
conformation of the D' domain of vWF is not only required for
FVIII binding but also for normal multimerization and optimal secretion.
