References of "Ouwehand, Willem H"
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See detailThe Human Phenotype Ontology in 2017
Köhler, Sebastian; Vasilevsky, Nicole A.; Engelstad, Mark et al

in Nucleic Acids Research (2016)

Deep phenotyping has been defined as the precise and comprehensive analysis of phenotypic abnormalities in which the individual components of the phenotype are observed and described. The three components ... [more ▼]

Deep phenotyping has been defined as the precise and comprehensive analysis of phenotypic abnormalities in which the individual components of the phenotype are observed and described. The three components of the Human Phenotype Ontology (HPO; www.human-phenotype-ontology.org) project are the phenotype vocabulary, disease-phenotype annotations and the algorithms that operate on these. These components are being used for computational deep phenotyping and precision medicine as well as integration of clinical data into translational research. The HPO is being increasingly adopted as a standard for phenotypic abnormalities by diverse groups such as international rare disease organizations, registries, clinical labs, biomedical resources, and clinical software tools and will thereby contribute toward nascent efforts at global data exchange for identifying disease etiologies. This update article reviews the progress of the HPO project since the debut Nucleic Acids Research database article in 2014, including specific areas of expansion such as common (complex) disease, new algorithms for phenotype driven genomic discovery and diagnostics, integration of cross-species mapping efforts with the Mammalian Phenotype Ontology, an improved quality control pipeline, and the addition of patient-friendly terminology. [less ▲]

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See detailOverexpression of the partially activated alpha(IIb)beta3D723H integrin salt bridge mutant downregulates RhoA activity and induces microtubule-dependent proplatelet-like extensions in Chinese hamster ovary cells
Schaffner-Reckinger, Elisabeth UL; Salsmann, Alexandre UL; Debili, Najet et al

in Journal of Thrombosis and Haemostasis [=JTH] (2009), 7(7), 1207-1217

BACKGROUND: We have recently reported a novel mutation in the beta3 subunit of the platelet fibrinogen receptor (alpha(IIb)beta3D723H) identified in a patient with dominantly inherited ... [more ▼]

BACKGROUND: We have recently reported a novel mutation in the beta3 subunit of the platelet fibrinogen receptor (alpha(IIb)beta3D723H) identified in a patient with dominantly inherited macrothrombocytopenia, and we have shown that this mutation promotes a new phenotype in Chinese hamster ovary (CHO) cells, characterized by fibrinogen-dependent, microtubule-driven proplatelet-like cell extensions. RESULTS: Here we demonstrate that the partially activated alpha(IIb)beta3D723H or alpha(IIb)beta3D723A salt bridge mutants, but not fully activated alpha(IIb)beta3 mutants, cause this phenotype. Time-lapse videomicroscopy clearly differentiated these stable microtubule-driven and nocodazole-sensitive extensions from common dynamic actin-driven pseudopodia. In addition, overexpression of a mitochondrial marker confirmed their functional role in organelle transport. Comparative immunofluorescence analysis of the subcellular localization of alpha(IIb)beta3, the focal adhesion proteins talin or vinculin and actin revealed a similar membrane labeling of CHO cell extensions and CD34+-derived megakaryocyte proplatelets. Mutant alpha(IIb)beta3D723H signaling was independent of Src, protein kinase C or phosphoinositide 3-kinase, but correlated with decreased RhoA activity as compared with wild-type alpha(IIb)beta3 signaling, reminiscent of integrin signaling during neurite outgrowth. Accordingly, overexpression of constitutively active RhoA in CHO alpha(IIb)beta3D723H cells prevented protrusion formation on fibrinogen. Most interestingly, RhoA/ROCK inhibition was necessary, but not sufficient, and integrin activity was additionally required to induce CHO cell extension formation. CONCLUSIONS: CHO alpha(IIb)beta3D723H cell protrusions and megakaryocyte proplatelets, like neuronal cell neurites, result from a common integrin-dependent signaling pathway, promoting strongly decreased RhoA activity and leading to microtubule-driven formation of cytoplasmic extensions. [less ▲]

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See detailA nonsynonymous SNP in the ITGB3 gene disrupts the conserved membrane-proximal cytoplasmic salt bridge in the αIIbβ3 integrin and cosegregates dominantly with abnormal proplatelet formation and macrothrombocytopenia
Ghevaert, Cedric; Salsmann, Alexandre UL; Watkins, Nicholas A. et al

in Blood (2008), 111(7), 3407-3414

We report a 3-generation pedigree with 5 individuals affected with a dominantly inherited macrothrombocytopenia. All 5 carry 2 nonsynonymous mutations resulting in a D723H mutation in the beta3 integrin ... [more ▼]

We report a 3-generation pedigree with 5 individuals affected with a dominantly inherited macrothrombocytopenia. All 5 carry 2 nonsynonymous mutations resulting in a D723H mutation in the beta3 integrin and a P53L mutation in glycoprotein (GP) Ibalpha. We show that GPIbalpha-L53 is phenotypically silent, being also present in 3 unaffected pedigree members and in 7 of 1639 healthy controls. The beta3-H723 causes constitutive, albeit partial, activation of the alphaIIbbeta3 complex by disruption of the highly conserved cytoplasmic salt bridge with arginine 995 in the alphaIIb integrin as evidenced by increased PAC-1 but not fibrinogen binding to the patients' resting platelets. This was confirmed in CHO alphaIIbbeta3-H723 transfectants, which also exhibited increased PAC-1 binding, increased adhesion to von Willebrand factor (VWF) in static conditions and to fibrinogen under shear stress. Crucially, we show that in the presence of fibrinogen, alphaIIbbeta3-H723, but not wild-type alphaIIbbeta3, generates a signal that leads to the formation of proplatelet-like protrusions in transfected CHO cells. Abnormal proplatelet formation was confirmed in the propositus's CD34+ stem cell-derived megakaryocytes. We conclude that the constitutive activation of the alphaIIbbeta3-H723 receptor causes abnormal proplatelet formation, leading to incorrect sizing of platelets and the thrombocytopenia observed in the pedigree. [less ▲]

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See detailThe effect of recombinant IgG antibodies against the leucine-33 form of the platelet beta3 integrin (HPA-1a) on platelet function.
Joutsi-Korhonen, Lotta; Preston, Sandy; Smethurst, Peter A. et al

in Thrombosis and haemostasis (2004), 91(4), 743-54

Recombinant HPA-1a antibodies with Fc, mutated to remove destructive effector functions, have been developed as a potential therapy for fetomaternal alloimmune thrombocytopenia (FMAIT), via blockade of ... [more ▼]

Recombinant HPA-1a antibodies with Fc, mutated to remove destructive effector functions, have been developed as a potential therapy for fetomaternal alloimmune thrombocytopenia (FMAIT), via blockade of binding of human HPA-1a polyclonal antibodies to fetal HPA-1a1b platelets. We have assessed the effect of the IgG1 HPA-1a antibody B2G1 and two mutated derivatives in various functional assays in resting and agonist-stimulated platelets of the three HPA-1 genotypes. With HPA-1a1b platelets (fetal genotype), the antibodies did not activate signalling or CD62P expression in resting platelets, did not change in vitro bleeding time (IVBT), and did not inhibit platelet adhesion to collagen in flowing blood. Adhesion of HPA-1a1b platelets to fibrinogen was reduced by 20%, and aggregation induced by ADP by 50%, but collagen-related peptide (CRP-XL)-induced aggregation was normal. With HPA-1a1a platelets, aggregation to both ADP and CRP-XL was inhibited, with total blockade of adhesion to fibrinogen and of IVBT responses. Interestingly, a monovalent antibody fragment with identical specificity had no inhibitory effect on aggregation. In static adhesion assays using human alphaIIbbeta3 or alphaVbeta3 transfectants of HPA-1a (Leu(33)) phenotype, attachment to fibrinogen of the latter but not of the former was completely blocked by the HPA-1a antibodies. These observations are best explained by antibody-mediated blockade of the RGD binding site on beta3 by a mechanism of steric hindrance. As the effect on platelet function is modest with HPA-1a1b (fetal type) platelets, the mutated HPA-1a antibodies described here could be developed further for FMAIT therapy. [less ▲]

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See detailHPA-1a phenotype-genotype discrepancy reveals a naturally occurring Arg93Gln substitution in the platelet beta 3 integrin that disrupts the HPA-1a epitope.
Watkins, Nicholas A.; Schaffner-Reckinger, Elisabeth UL; Allen, David L. et al

in Blood (2002), 99(5), 1833-9

A single nucleotide polymorphism (SNP) at position 196 in the beta 3 integrin causes a Leu33Pro substitution in the mature protein. Alloimmunization against the beta 3Leu33 form (human platelet antigen ... [more ▼]

A single nucleotide polymorphism (SNP) at position 196 in the beta 3 integrin causes a Leu33Pro substitution in the mature protein. Alloimmunization against the beta 3Leu33 form (human platelet antigen [HPA]-1a, Pl(A1), Zw(a)) in patients who are beta 3Pro33 homozygous (HPA-1b1b, Pl(A2A2), Zw(bb)) causes neonatal alloimmune thrombocytopenia, posttransfusion purpura, or refractoriness to platelet transfusion. Studies with recombinant proteins have demonstrated that amino acids 1 to 66 and 288 to 490 of the beta 3 integrin contribute to HPA-1a epitope formation. In determining the HPA-1a status of more than 6000 donors, we identified a donor with an HPA-1a(weak) phenotype and an HPA-1a1b genotype. The platelets from this donor had normal levels of surface alpha IIb beta 3 but reacted only weakly with monoclonal and polyclonal anti-HPA-1a by whole blood enzyme-linked immunosorbent assay (ELISA), flow cytometry, and sandwich ELISA. We reasoned that an alteration in the primary nucleotide sequence of the beta 3Leu33 allele of this donor was disrupting the HPA-1a epitope. In agreement with this hypothesis, sequencing platelet RNA-derived alpha IIb and beta 3 cDNA identified a novel G/A SNP at position 376 of the beta 3 integrin that encodes for an Arg93Gln replacement in the beta 3Leu33 allele. Coexpression of the beta 3Leu33Gln93 encoding cDNA in Chinese hamster ovary cells with human alpha IIb cDNA showed that the surface-expressed alpha IIb beta 3 reacted normally with beta 3 integrin-specific monoclonal antibodies but only weakly with monoclonal anti-HPA-1a. Our results show that an Arg93Gln mutation in the beta 3Leu33 encoding allele disrupts the HPA-1a epitope, suggesting that Arg93 contributes to the formation of the HPA-1a B-cell epitope. [less ▲]

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