Functional characterization of a 13-bp deletion (c.-1522_-1510del13) in the promoter of the von Willebrand factor gene in type 1 von Willebrand disease.
We have studied the effect of a 13-bp deletion in the promoter of the von Willebrand factor (VWF) gene in a patient with type 1 von Willebrand disease. The index case has a VWF:Ag of 0.49 IU/mL and is heterozygous for the deletion. The deletion is located 48 bp 5' of the transcription start site, and in silico analysis, electrophoretic mobility shift assays, and chromatin immunoprecipitation studies all predict aberrant binding of Ets transcription factors to the site of the deletion. Transduction of reporter gene constructs into blood outgrowth endothelial cells showed a 50.5% reduction in expression with the mutant promoter (n = 16, P < .001). A similar 40% loss of transactivation was documented in transduced HepG2 cells. A similar marked reduction of transgene expression was shown in the livers of mice injected with the mutant promoter construct (n = 8, P = .003). Finally, in studies of BOEC mRNA, the index case showed a 4.6-fold reduction of expression of the VWF transcript associated with the deletion mutation. These studies show that the 13-bp deletion mutation alters the binding of Ets (and possibly GATA) proteins to the VWF promoter and significantly reduces VWF expression, thus playing a central pathogenic role in the type 1 von Willebrand disease phenotype in the index case.
Othman
Maha
M
Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, Canada.
Chirinian
Yvette
Y
Brown
Christine
C
Notley
Colleen
C
Hickson
Nicholas
N
Hampshire
Daniel
D
Buckley
Suzanne
S
Waddington
Simon
S
Parker
Alan L
AL
Baker
Andrew
A
James
Paula
P
Lillicrap
David
D
D000818:Animals; D002460:Cell Line; D042783:Endothelial Cells / Q000378:metabolism; D050980:GATA Transcription Factors / Q000378:metabolism; D056945:Hep G2 Cells; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D010641:Phenotype; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D050783:Proto-Oncogene Proteins c-ets / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D017384:Sequence Deletion; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D019076:Transgenes; D056725:von Willebrand Disease, Type 1 / Q000235:genetics* / Q000378:metabolism; D014841:von Willebrand Factor / Q000235:genetics* / Q000378:metabolism
D050980:GATA Transcription Factors; D050783:Proto-Oncogene Proteins c-ets; D012333:RNA, Messenger; D014157:Transcription Factors; D014841:von Willebrand Factor