Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

The pro-polypeptide of von Willebrand factor is required for the formation of a functional factor VIII-binding site on mature von Willebrand factor.

ABSTRACT: We have established that a recombinant von Willebrand Factor (vWF) mutant (vWFdelpro) that lacks the propolypeptide, in contrast with mature wild-type vWF, with which it is identical in terms of primary amino acid sequence, is not able to form a complex with Factor VIII. Wild-type vWF (flvWF) and vWFdelpro were expressed in AtT-20 cells. Under the culture conditions employed, completely processed multimerized flvWF and dimeric vWFdelpro were secreted into the medium. FlvWF and vWFdelpro were compared for their Factor VIII-binding properties in two distinct assay systems. In a direct binding assay, purified human Factor VIII was shown to bind to flvWF that had been immobilized on the surface of microtitre wells by using an anti-vWF monoclonal antibody. In contrast, Factor VIII did not bind to immobilized vWFdelpro. In a competition assay, fluid-phase flvWF appeared to inhibit efficiently the binding of Factor VIII to immobilized vWF isolated from plasma, whereas vWFdelpro did not influence Factor VIII binding. From these observations, it is argued that the pro-polypeptide serves an essential role in the post-translational processes that lead to the expression of a functional Factor VIII-binding site on the mature vWF subunit.

SUBMITTER: Leyte A

PROVIDER: S-EPMC1149946 | biostudies-other | 1991 Feb

REPOSITORIES: biostudies-other

ACCESS DATA

Json Xml

Similar Datasets

Population pharmacokinetics of the von Willebrand factor-factor VIII interaction in patients with von Willebrand disease.

Project description:Recent studies have reported that patients with von Willebrand disease treated perioperatively with a von Willebrand factor (VWF)/factor VIII (FVIII) concentrate with a ratio of 2.4:1 (Humate P/Haemate P) often present with VWF and/or FVIII levels outside of prespecified target levels necessary to prevent bleeding. Pharmacokinetic (PK)-guided dosing may resolve this problem. As clinical guidelines increasingly recommend aiming for certain target levels of both VWF and FVIII, application of an integrated population PK model describing both VWF activity (VWF:Act) and FVIII levels may improve dosing and quality of care. In total, 695 VWF:Act and 894 FVIII level measurements from 118 patients (174 surgeries) who were treated perioperatively with the VWF/FVIII concentrate were used to develop this population PK model using nonlinear mixed-effects modeling. VWF:Act and FVIII levels were analyzed simultaneously using a turnover model. The protective effect of VWF:Act on FVIII clearance was described with an inhibitory maximum effect function. An average perioperative VWF:Act level of 1.23 IU/mL decreased FVIII clearance from 460 mL/h to 264 mL/h, and increased FVIII half-life from 6.6 to 11.4 hours. Clearly, in the presence of VWF, FVIII clearance decreased with a concomitant increase of FVIII half-life, clarifying the higher FVIII levels observed after repetitive dosing with this concentrate. VWF:Act and FVIII levels during perioperative treatment were described adequately by this newly developed integrated population PK model. Clinical application of this model may facilitate more accurate targeting of VWF:Act and FVIII levels during perioperative treatment with this specific VWF/FVIII concentrate (Humate P/Haemate P).

| S-EPMC7948283 | biostudies-literature

von Willebrand factor variant p.Arg924Gln marks an allele associated with reduced von Willebrand factor and factor VIII levels.

Project description:von Willebrand factor (VWF) variant c.2771G>A; p.R924Q has been described as a benign polymorphism or a possible marker for a null allele and been associated with mild bleeding phenotypes. It was identified in several patients in recent type 1 von Willebrand disease (VWD) studies.To determine whether the p.R924Q allele contributes to reduced VWF levels and type 1 VWD.One thousand one hundred and fifteen healthy controls and 148 index cases from the MCMDM-1VWD study were genotyped for c.2771G>A; VWF and FVIII levels were analyzed in ABO blood group stratified individuals and the p.R924Q variant was expressed in 293 EBNA cells.c.2771G>A was present in six index cases, five of whom had a second VWF variant which probably contributed to the phenotype. A common core haplotype identified in families, which included the rare G allele of c.5843-8C>G, was present in the majority of 35 c.2771G>A heterozygous controls. c.2771G>A contributed about 10% variance in VWF and FVIII levels in controls and 35% variance when co-inherited with blood group O. Recombinant p.R924Q VWF had no effect on in vitro expression and heterozygous family members had normal VWF-FVIII binding and normal clearance of VWF and FVIII.The allele bearing c.2771A leads to reductions in VWF and FVIII levels particularly in combination with blood group O. Its inheritance alone may be insufficient for VWD diagnosis, but it appears to be associated with a further VWF level reduction in individuals with a second VWF mutation and it contributes to population variance in VWF and FVIII levels.

| S-EPMC3856360 | biostudies-literature

Molecular coevolution of coagulation factor VIII and von Willebrand factor.

Project description:Ancestral sequence reconstruction provides a unique platform for investigating the molecular evolution of single gene products and recently has shown success in engineering advanced biological therapeutics. To date, the coevolution of proteins within complexes and protein-protein interactions is mostly investigated in silico via proteomics and/or within single-celled systems. Herein, ancestral sequence reconstruction is used to investigate the molecular evolution of 2 proteins linked not only by stabilizing association in circulation but also by their independent roles within the primary and secondary hemostatic systems of mammals. Using sequence analysis and biochemical characterization of recombinant ancestral von Willebrand factor (VWF) and coagulation factor VIII (FVIII), we investigated the evolution of the essential macromolecular FVIII/VWF complex. Our data support the hypothesis that these coagulation proteins coevolved throughout mammalian diversification, maintaining strong binding affinities while modulating independent and distinct hemostatic activities in diverse lineages.

| S-EPMC7876868 | biostudies-literature

Factor VIII accelerates proteolytic cleavage of von Willebrand factor by ADAMTS13.

Project description:Proteolytic processing of von Willebrand factor (VWF) by ADAMTS13 metalloproteinase is crucial for normal hemostasis. In vitro, cleavage of VWF by ADAMTS13 is slow even at high shear stress and is typically studied in the presence of denaturants. We now show that, under shear stress and at physiological pH and ionic strength, coagulation factor VIII (FVIII) accelerates, by a factor of approximately 10, the rate of specific cleavage at the Tyr(1605)-Met(1606) bond in VWF. Multimer analysis reveals that FVIII preferentially accelerates the cleavage of high-molecular-weight multimers. This rate enhancement is not observed with VWF predenatured with 1.5 M guanidine. The ability of FVIII to enhance VWF cleavage by ADAMTS13 is rapidly lost after pretreatment of FVIII with thrombin. A FVIII derivative lacking most of the B domain behaves equivalently to full-length FVIII. In contrast, a derivative lacking both the B domain and the acidic region a3 that contributes to the high-affinity interaction of FVIII with VWF exhibits a greatly reduced ability to enhance VWF cleavage. Our data suggest that FVIII plays a role in regulating proteolytic processing of VWF by ADAMTS13 under shear stress, which depends on the high-affinity interaction between FVIII and its carrier protein, VWF.

| S-EPMC2396690 | biostudies-literature

Interaction of factor VIII-von Willebrand Factor with phospholipid vesicles.

Project description:The interaction of Factor VIII-von Willebrand Factor with phospholipid vesicles has been studied by using sucrose-density-gradient ultracentrifugation. When purified Factor VIII-von Willebrand Factor was run alone. Factor VIII activity and Factor VIIIR-Ag sedimented together to the lower half of the tube. Addition of phosphatidylserine/phosphatidylethanolamine vesicles at concentrations above 250 microgram/ml resulted in complete separation of Factor VIII activity and Factor VIIIR-Ag, the former appearing with the phospholipid on the top of the tube and the latter sedimenting as before. This separation was obtained even in the presence of proteinase inhibitors. Activation of Factor VIII-von Willebrand Factor by thrombin resulted in formation of a slow sedimenting component containing essentially all the Factor VIII activity, whereas the Factor VIIIR-Ag sedimented towards the bottom of the tube as before. The thrombin-induced Factor VIII activity was strongly bound to phospholipid vesicles as determined by density-gradient centrifugations at various Factor VIII concentrations and low concentrations of phospholipid. Based on certain assumptions a dissociation constant of 2.5 nM was calculated, a mechanism for the formation in vivo of the Factor X-activator complex is suggested.

| S-EPMC1163514 | biostudies-other

Proteomic characterization of plasma-derived clotting factor VIII-von Willebrand factor concentrates.

Project description:Proteomic methods were used to identify the levels of impurities in three commercial plasma-derived clotting factor VIII-von Willebrand factor (FVIII/VWF) concentrates. In all three concentrates, significant amounts of other plasma proteins were found. In Octanate and Haemoctin, two concentrates developed in the 1990s, the major impurities identified were inter-alpha inhibitor proteins, fibrinogen and fibronectin. These two concentrates were also found to contain additional components such as clotting factor II (prothrombin) that are known activators of FVIII. In Wilate, a recently developed FVIII/VWF concentrate, the amount of these impurities was significantly reduced. Batch-to-batch variations and differences between three investigated products were detected using iTRAQ, an isotope labeling technique for comparative MS, demonstrating the potential value of this technique for quality control analysis. The importance of thorough proteomic investigations of therapeutic FVIII/VWF preparations from human plasma is also discussed.

| S-EPMC3030255 | biostudies-literature

Factor VIII-von Willebrand factor complex inhibits osteoclastogenesis and controls cell survival.

Project description:Factor VIII-von Willebrand factor (FVIII.vWF) complex, a molecule involved in coagulation, can be physically associated with osteoprotegerin (OPG). OPG is an anti-osteoclastic protein and a soluble receptor for the proapoptotic protein TRAIL (tumor necrosis factor-related apoptosis-inducing ligand), suggesting a potential role of FVIII.vWF complex in bone and cancer biology. We, thus, assessed the effects of FVIII.vWF complex on osteoclastogenesis and cell survival. We first evidenced that FVIII.vWF complex inhibited RANKL-induced osteoclastogenesis and enhanced the inhibitory effect of OPG. Interestingly, we revealed by surface plasmon resonance that FVIII.vWF complex bound to RANKL, whereas recombinant FVIII and vWF did not. By modeling, we showed that the OPG binding domain to the A1 domain of vWF was closely located and partially overlapped to its binding site to RANKL. Then, we demonstrated that FVIII.vWF complex cancelled the inhibitory activity of OPG on TRAIL-induced apoptosis and characterized interactions between these molecules. The present work evidenced a direct activity of FVIII.vWF complex on osteoclasts and on induced cell apoptosis, pointing out its potential involvement in physiological bone remodeling or in bone damages associated with severe hemophilia and cancer development.

| S-EPMC2797241 | biostudies-literature

The impact of von Willebrand factor on factor VIII memory immune responses.

Project description:Immune tolerance induction (ITI) with aggressive infusion of factor VIII (FVIII) is the current strategy used to eradicate FVIII inhibitors and restore normal FVIII pharmacokinetics in inhibitor patients. Whether the use of FVIII products containing von Willebrand factor (VWF) will affect the efficacy of ITI is still controversial. In this study, we explored the impact of VWF on FVIII memory immune responses in hemophilia A (HA) mice. A T-cell proliferation assay and cytokine profile analysis were used to study FVIII-primed CD4+ T cells. When CD4+ T cells from primed FVIIInull mice were restimulated with recombinant human FVIII (rhF8) plus recombinant human VWF (rhVWF) in vitro, the percentages of daughter CD4+ T cells were significantly decreased compared with the groups cultured with rhF8 only. Levels of interferon-γ and interleukin 10 were significantly lower in the rhF8 plus rhVWF groups than in the rhF8 groups. When memory B-cell pools from primed FVIIInull mice were cultured with rhF8 with or without rhVWF to induce differentiation of memory B cells into antibody-secreting cells (ASCs), the number of ASCs was significantly lower in the rhF8 plus VWF group than in the rhF8 group. When memory B-cell pools were transferred into NSGF8KO mice followed by rhF8 immunization with or without rhVWF, the titers of anti-F8 inhibitors and total immunoglobulin G were significantly higher in the rhF8 group than in the rhF8 plus rhVWF group, with an average difference of 2.23- and 2.04-fold. Together, our data demonstrate that VWF attenuates FVIII memory immune responses in HA mice.

| S-EPMC5600162 | biostudies-literature

The interaction between human blood-coagulation factor VIII and von Willebrand factor. Characterization of a high-affinity binding site on factor VIII.

Project description:The interaction between human Factor VIII and immobilized multimeric von Willebrand Factor (vWF) was characterized. Equilibrium binding studies indicated the presence of multiple classes of Factor VIII-binding sites on vWF. The high-affinity binding (Kd = 2.1 x 10(-10) M) was restricted to only 1-2% of the vWF subunits. Competition studies with monoclonal antibodies with known epitopes demonstrated that the Factor VIII sequence Lys1673-Arg1689 is involved in the high-affinity interaction with vWF.

| S-EPMC1135641 | biostudies-other

Solution structure of the major factor VIII binding region on von Willebrand factor.

Project description:Although much of the function of von Willebrand factor (VWF) has been revealed, detailed insight into the molecular structure that enables VWF to orchestrate hemostatic processes, in particular factor VIII (FVIII) binding and stabilization in plasma, is lacking. Here, we present the high-resolution solution structure and structural dynamics of the D' region of VWF, which constitutes the major FVIII binding site. D' consists of 2 domains, trypsin-inhibitor-like (TIL') and E', of which the TIL' domain lacks extensive secondary structure, is strikingly dynamic and harbors a cluster of pathological mutations leading to decreased FVIII binding affinity (type 2N von Willebrand disease [VWD]). This indicates that the backbone malleability of TIL' is important for its biological activity. The principal FVIII binding site is localized to a flexible, positively charged region on TIL', which is supported by the rigid scaffold of the TIL' and E' domain ? sheets. Furthermore, surface-charge mapping of the TIL'E' structure reveals a potential mechanism for the electrostatically guided, high-affinity VWF?FVIII interaction. Our findings provide novel insights into VWF?FVIII complex formation, leading to a greater understanding of the molecular basis of the bleeding diathesis type 2N VWD.

| S-EPMC4073327 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data