title: Impact of mutations in the von Willebrand factor A2 domain on ADAMTS13-dependent proteolysis.
abstract: Classical von Willebrand disease (VWD) type 2A, the most common qualitative defect of VWD, is caused by loss of high-molecular-weight multimers (HMWMs) of von Willebrand factor (VWF). Underlying mutations cluster in the A2 domain of VWF around its cleavage site for ADAMTS13. We investigated the impact of mutations commonly found in patients with VWD type 2A on ADAMTS13-dependent proteolysis of VWF. We used recombinant human ADAMTS13 (rhuADAMTS13) to digest recombinant full-length VWF and a VWF fragment spanning the VWF A1 through A3 domains, harboring 13 different VWD type 2A mutations (C1272S, G1505E, G1505R, S1506L, M1528V, R1569del, R1597W, V1607D, G1609R, I1628T, G1629E, G1631D, and E1638K). With the exception of G1505E and I1628T, all mutations in the VWF A2 domain increased specific proteolysis of VWF independent of the expression level. Proteolytic susceptibility of mutant VWF in vitro closely correlated with the in vivo phenotype in patients. The results imply that increased VWF susceptibility for ADAMTS13 is a constitutive property of classical VWD type 2A, thus explaining the pronounced proteolytic fragments and loss of HMWM seen in multimer analysis in patients.
authors.affiliation: Dept of Pediatric Hematology and Oncology, University Medical Center Hamburg-Eppendorf, Martinistrasse 52, D-20246 Hamburg, Germany.
authors.forename: Wolf Achim
authors.initials: WA
authors.lastname: Hassenpflug
authors.forename: Ulrich
authors.initials: U
authors.lastname: Budde
authors.forename: Tobias
authors.initials: T
authors.lastname: Obser
authors.forename: Dorothea
authors.initials: D
authors.lastname: Angerhaus
authors.forename: Elke
authors.initials: E
authors.lastname: Drewke
authors.forename: Sonja
authors.initials: S
authors.lastname: Schneppenheim
authors.forename: Reinhard
authors.initials: R
authors.lastname: Schneppenheim
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism*; D000071120:ADAMTS13 Protein; D019943:Amino Acid Substitution; D019281:Dimerization; D020022:Genetic Predisposition to Disease; D006801:Humans; D009154:Mutation; D010446:Peptide Fragments; D010641:Phenotype; D017434:Protein Structure, Tertiary / Q000235:genetics; D014842:von Willebrand Diseases / Q000235:genetics; D014841:von Willebrand Factor / Q000235:genetics* / Q000378:metabolism
chemical_list: D010446:Peptide Fragments; D014841:von Willebrand Factor; D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C099604:ADAMTS13 protein, human