Total inhibition of high shear stress induced platelet aggregation by homodimeric von Willebrand factor A1‐loop fragments

Miura, S.; Sakurai, Yoshihiko; Takatsuka, Hideo; Yoshioka, Akira; Matsumoto, Masanori; Yano, Hideo; Kokubo, Tetsuro; Ikeda, Yasuo; Matsui, Taei; Titani, Koiti; Fujimura, Yoshihiro

doi:10.1046/j.1365-2141.1999.01454.x

Cited by 7 publications

(4 citation statements)

References 27 publications

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“…This indicates that platelet activation via GPIb␣ in solution requires both binding of A1 domain and a minimum threshold of shear force. Moreover, the differential effect of the mutant A1A2A3 in ristocetin-induced platelet agglutination and shear-induced platelet aggregation contrasts previous studies reporting that single monomeric or homodimeric A1 domain proteins effectively inhibited both ristocetin-induced platelet agglutination and shear-induced platelet aggregation (9,14,42). A possible explanation for this dissimilarity is that other structural features present in the A1A2A3 sequence influence on the A1-GPIb␣ binding.…”

contrasting

confidence: 49%

Destabilization of the A1 Domain in von Willebrand Factor Dissociates the A1A2A3 Tri-domain and Provokes Spontaneous Binding to Glycoprotein Ibα and Platelet Activation under Shear Stress

Auton

Sowa

Smith

et al. 2010

Journal of Biological Chemistry

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This study used recombinant A1A2A3 tri-domain proteins to demonstrate that A domain association in von Willebrand factor (VWF) regulates the binding to platelet glycoprotein Ib␣ (GPIb␣). We performed comparative studies between wild type (WT) A1 domain and the R1450E variant that dissociates the tri-domain complex by destabilizing the A1 domain. Using urea denaturation and differential scanning calorimetry, we demonstrated the destabilization of the A1 domain structure concomitantly results in a reduced interaction among the three A domains. This dissociation results in spontaneous binding of R1450E to GPIb␣ without ristocetin with an apparent K D of 85 ؎ 34 nM, comparable with that of WT (36 ؎ 12 nM) with ristocetin. The mutant blocked 100% ristocetin-induced platelet agglutination, whereas WT failed to inhibit. The mutant enhanced shear-induced platelet aggregation at 500 and 5000 s ؊1 shear rates, reaching 42 and 66%, respectively. Shear-induced platelet aggregation did not exceed 18% in the presence of WT. A1A2A3 variants were added before perfusion over a fibrin(ogen)-coated surface. At 1500 s ؊1 , platelets from blood containing WT adhered <10% of the surface area, whereas the mutant induced platelets to rapidly bind, covering 100% of the fibrin(ogen) surface area. Comparable results were obtained with multimeric VWF when ristocetin (0.5 mg/ml) was added to blood before perfusion. EDTA or antibodies against GPIb␣ and ␣IIb␤3 blocked the effect of the mutant and ristocetin on platelet activation/adhesion. Therefore, the termination of A domain association within VWF in solution results in binding to GPIba and platelet activation under high shear stress.Platelet adhesion at sites of vascular injury contributes to the arrest of bleeding as well as to the pathologic occlusion of diseased vessels under elevated shear stress. Under this high shear stress, the platelet-von Willebrand factor (VWF) 3 interaction is essential for platelet adhesion. The interaction between VWF and the exposed subendothelium permits the VWF to interact with circulating platelets via the receptor glycoprotein (GP)Ib/ IX/V complex (1). Mature VWF consists of a 2050-residue subunit that contains domains that are arranged in the order DЈ-D3-A1-A2-A3-D4-B1-B2-B3-C1-C2-CK (cystine knot) (2-4). The VWF contains a triplicate repeat sequence or A domains in the central portion of the subunit. Binding sites for platelet GPIb␣, heparin, sulfatides, and collagen (5-9) are within the A1 domain, whereas its homologous A3 domain only binds to collagen, and the A2 domain contains the cleavage site for the metalloprotease ADAMTS-13 (10 -12). The functions of these A domains relevant to the biology of VWF have been characterized by individual recombinant expression of each of the A domains (9, 10, 13).The interaction between VWF and GPIb␣ occurs when the binding site for GPIb␣ in the A1 domain of VWF has been exposed by the influence of high fluid forces or when the multimeric protein has been immobilized (14). This activation can also be induced by nat...

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confidence: 49%

Destabilization of the A1 Domain in von Willebrand Factor Dissociates the A1A2A3 Tri-domain and Provokes Spontaneous Binding to Glycoprotein Ibα and Platelet Activation under Shear Stress

Auton

Sowa

Smith

et al. 2010

Journal of Biological Chemistry

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“…We recently purified a unique metalloproteinase, named kaouthiagin, from the venom of the cobra snake Naja kaouthia (20). Kaouthiagin is an o-phenanthroline or EDTA sensitive metalloproteinase which binds to and cleaves human von Willebrand factor (VWF) (20,21). VWF is a multimeric plasma protein essential for platelet adhesion to the damaged subendothelial matrixes to form a hemostatic plug (22).…”

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confidence: 99%

Complete Amino Acid Sequence of Kaouthiagin, a Novel Cobra Venom Metalloproteinase with Two Disintegrin-like Sequences

et al. 2001

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The primary structure of kaouthiagin, a metalloproteinase from the venom of the cobra snake Naja kaouthia which specifically cleaves human von Willebrand factor (VWF), was determined by amino acid sequencing. Kaouthiagin is composed of 401 amino acid residues and one Asn-linked sugar chain. The sequence is highly similar to those of high-molecular mass snake venom metalloproteinases from viperid and crotalid venoms comprised of metalloproteinase, disintegrin-like, and Cys-rich domains. The metalloproteinase domain had a zinc-binding motif (HEXXHXXGXXH), which is highly conserved in the metzincin family. Kaouthiagin had an HDCD sequence in the disintegrin-like domain and uniquely had an RGD sequence in the Cys-rich domain. Metalloproteinase-inactivated kaouthiagin had no effect on VWF-induced platelet aggregation but still had an inhibitory effect on the collagen-induced platelet aggregation with an IC(50) of 0.2 microM, suggesting the presence of disintegrin-like activity in kaouthiagin. To examine the effects of these HDCD and RGD sequences, we prepared synthetic peptides cyclized by an S-S linkage. Both the synthetic cyclized peptides from the disintegrin-like domain and from the Cys-rich domain) had an inhibitory effect on collagen-induced platelet aggregation with IC(50) values of approximately 90 and approximately 4.5 microM, respectively. The linear peptide (RAAKHDCDLPELC) and the cyclized peptide had little effect on collagen-induced platelet aggregation. These results suggest that kaouthiagin not only inhibits VWF-induced platelet aggregation by cleaving VWF but also disturbs the agonist-induced platelet aggregation by both the disintegrin-like domain and the RGD sequence in the Cys-rich domain. Furthermore, our results imply that the corresponding part of the Cys-rich domain in other snake venom metalloproteinases also has a synergistic disturbing effect on platelet aggregation, serving as a second disintegrin-like domain. This is the first report of an elapid venom metalloproteinase with two disintegrin-like sequences.

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“…VWF, a multimeric protein, incurs integrin αII b β 3 -dependent platelet aggregation under high shear stress. The dimeric VWF A1 peptides, but not monomeric A1, induce platelet aggregation (25), suggesting dimerisation or clustering of GPIbα by VWF leads to platelet aggregation. We established that, similar to VWF-induced platelet activation, AN51 binding triggers signalling cascades leading to integrin αII b β 3 -dependent platelet aggregation.…”

Section: Discussionmentioning

confidence: 94%

Glycoprotein Ibα clustering induces macrophage-mediated platelet clearance in the liver

Yan¹,

Chen²,

Ma³

et al. 2015

Thromb Haemost

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Many immune thrombocytopenia (ITP) patients, particularly patients with anti-glycoprotein (GP) Ib-IX autoantibodies, do not respond to the conventional treatments such as splenectomy. However, the underlying mechanism remains unclear. Here we found that anti-GPIbα N-terminus antibody AN51, but not other anti-GPIbα antibodies (AK2, HIP1, VM16d, or WM23), induced GPIbα clustering that led to integrin αIIbβ3-dependent platelet aggregation. After intravenous injection, AN51 dose-dependently induced thrombocytopenia in guinea pigs, and the platelets were mainly removed by macrophages in the liver. N-acetyl-D-glucosamine, previously shown to inhibit integrin αMβ2-mediated phagocytosis of refrigerated platelets, dose-dependently inhibited AN51-induced platelet clearance. Furthermore, AN51 but not VM16d, induced rapid platelet clearance in the liver of cynomolgus macaques. Five of 22 chronic ITP patients had anti-GPIbα autoantibodies, and the autoantibodies from four of the five patients competed with AN51 for binding to platelets. These data indicate that GPIbα clustering induced by anti-GPIbα N-terminus antibody causes integrin αIIbβ3-dependent platelet aggregation, phagocytosis, and rapid platelet clearance in the liver. Our findings reveal a novel Fc-independent mechanism underlying the pathogenesis of ITP, and suggest new therapeutic strategies for ITP patients with anti-GPIbα autoantibodies.

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Total inhibition of high shear stress induced platelet aggregation by homodimeric von Willebrand factor A1‐loop fragments

Cited by 7 publications

References 27 publications

Destabilization of the A1 Domain in von Willebrand Factor Dissociates the A1A2A3 Tri-domain and Provokes Spontaneous Binding to Glycoprotein Ibα and Platelet Activation under Shear Stress

Destabilization of the A1 Domain in von Willebrand Factor Dissociates the A1A2A3 Tri-domain and Provokes Spontaneous Binding to Glycoprotein Ibα and Platelet Activation under Shear Stress

Complete Amino Acid Sequence of Kaouthiagin, a Novel Cobra Venom Metalloproteinase with Two Disintegrin-like Sequences

Glycoprotein Ibα clustering induces macrophage-mediated platelet clearance in the liver

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