Storage of factor VIII variants with impaired von Willebrand factor binding in Weibel-Palade bodies in endothelial cells.

PLoS One 2011 31;6(8):e24163. Epub 2011 Aug 31.

Department of Plasma Proteins, Sanquin Research, Amsterdam, The Netherlands.

Background: Point mutations resulting in reduced factor VIII (FVIII) binding to von Willebrand factor (VWF) are an important cause of mild/moderate hemophilia A. Treatment includes desmopressin infusion, which concomitantly increases VWF and FVIII plasma levels, apparently from storage pools containing both proteins. The source of these VWF/FVIII co-storage pools and the mechanism of granule biogenesis are not fully understood.

Methodology/principal Findings: We studied intracellular trafficking of FVIII variants implicated in mild/moderate hemophilia A together with VWF in HEK293 cells and primary endothelial cells. The role of VWF binding was addressed using FVIII variants displaying reduced VWF interaction. Binding studies using purified FVIII proteins revealed moderate (Arg2150His, Del2201, Pro2300Ser) to severe (Tyr1680Phe, Ser2119Tyr) VWF binding defects. Expression studies in HEK293 cells and primary endothelial cells revealed that all FVIII variants were present within VWF-containing organelles. Quantitative studies showed that the relative amount of FVIII storage was independent of various mutations. Substantial amounts of FVIII variants are co-stored in VWF-containing storage organelles, presumably by virtue of their ability to interact with VWF at low pH.

Conclusions: Our data suggest that the potential of FVIII co-storage with VWF is not affected in mild/moderate hemophilia A caused by reduced FVIII/VWF interaction in the circulation. These data support the hypothesis that Weibel-Palade bodies comprise the desmopressin-releasable FVIII storage pool in vivo.

Download full-text PDF

Source
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0024163PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3166073PMC
January 2012
2 Reads

Publication Analysis

Top Keywords

fviii variants
16
endothelial cells
12
mild/moderate hemophilia
12
fviii
10
von willebrand
8
weibel-palade bodies
8
vwf binding
8
fviii storage
8
willebrand factor
8
hek293 cells
8
vwf mild/moderate
8
factor viii
8
primary endothelial
8
cells primary
8
vwf
8
cells
5
storage
5
binding
5
variants
5
severe tyr1680phe
4

References

(Supplied by CrossRef)
The life cycle of coagulation factor VIII in view of its structure and function.
PJ Lenting et al.
Blood 1998
Structure and function of the factor VIII gene and protein.
AR Thompson et al.
Semin Thromb Hemost 2003
Molecular mechanisms of mild and moderate hemophilia A.
M Jacquemin et al.
J Thromb Haemost 2003
Regulated release of VWF and FVIII and the biologic implications.
SL Haberichter et al.
Pediatr Blood Cancer 2006

Similar Publications