N-terminal Flanking Region of A1 Domain in von Willebrand Factor Stabilizes Structure of A1A2A3 Complex and Modulates Platelet Activation under Shear Stress

Auton, Matthew; Sowa, Katie E.; Behymer, Molly; Crúz, Miguel A.

doi:10.1074/jbc.m112.348573

Cited by 42 publications

(71 citation statements)

References 33 publications

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“…Similar results were observed when blood was perfused over the fragment A1A2A3 domain protein, which functions like VWF but lacks the site for the GPIIb/IIIa receptor. 19 Contrary to the rolling platelets with whole blood (Figure 2C), 18 free Hb induced the formation of both firmly stable microthrombi and rolling microaggregates ( Figure 2D and supplemental Figure 2A, respectively). Free Hb also increased the adhesion of flowing fixed platelets to the VWF-coated surface at high shear stress (supplemental Figure 2B).…”

Section: Flow Assaysmentioning

confidence: 87%

Free hemoglobin increases von Willebrand factor–mediated platelet adhesion in vitro: implications for circulatory devices

Teruya

Guchhait

et al. 2015

Blood

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• Extracellular Hb alters the GPIba-VWF interaction.Intravascular hemolysis occurs in patients on extracorporeal membrane oxygenation. High levels of free acellular adult hemoglobin (free HbA) are associated with clotting in this mechanical device that can result in thrombotic complications. Adsorption of fibrinogen onto the surface of biomaterial correlates with platelet adhesion, which is mediated by von Willebrand factor (VWF). Because free Hb interacts with VWF, we studied the effect of hemoglobin (Hb) on platelet adhesion to fibrin(ogen) under conditions of different hydrodynamic forces. This effect was investigated using purified human HbA and fibrinogen, extracellular matrix, collagen, or purified plasma VWF as surface-coated substrates to examine flow-dependent platelet adhesion. Antibodies and VWF-deficient plasma were also used. Free Hb ( ‡50 mg/dL) effectively augmented platelet adhesion, and microthrombi formation on fibrin(ogen), extracellular matrix, and collagen at high shear stress. The effect of free Hb was effectively blocked by anti-glycoprotein Iba (GPIba) antibodies or depletion of VWF. Unexpectedly, free Hb also promoted firm platelet adhesion and stable microthrombi on VWF. Lastly, we determined that Hb interacts directly with the A1 domain. This study is the first to demonstrate that extracellular Hb directly affects the GPIba-VWF interaction in thrombosis, and describes another mechanism by which hemolysis is connected to thrombotic events. (Blood. 2015; 126(20):2338-2341 IntroductionThe excessive release of hemoglobin (Hb) from erythrocytes into the circulation of patients on mechanical circulatory support devices is a well-recognized major clinical complication.1 Increasing incidence of hemolysis and thrombosis is associated with morbidity and mortality in patients on extracorporeal membrane oxygenation (ECMO).2 Prevention of circuit clotting in ECMO can improve clinical outcome.von Willebrand factor (VWF) is a multimeric plasma glycoprotein that mediates platelet adhesion, activation, and aggregation under high flow conditions. 3-7 Plasma VWF mediates platelet adhesion to surfaces coated with fibrin(ogen), 8,9 which is adsorbed onto surfaces of many materials used in biomedical instruments, including ECMO.10,11 Previously, we reported that free Hb interacts with the A2 domain of VWF 12 and, moreover, we and many others have described that the A2 domain regulates the binding of its neighboring A1 domain in VWF to platelet receptor glycoprotein Iba (GPIba).13-15 Thus, in this study, we examined the effect of the free Hb-VWF interaction on mediating platelet adhesion to immobilized fibrin(ogen) at high shear stress; a mechanism not previously investigated. Study design ReagentsPurified Hb and plasma VWF were obtained using established methods.13,16 Human collagen type III was purchased from Advanced BioMatrix, human fibrinogen from Calbiochem, and extracellular matrix (ECM) from Sigma-Aldrich. Anti-GPIba antibody 6D1 was a gift from Dr Barry Coller (The Rockefeller University, New Yor...

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Section: Flow Assaysmentioning

confidence: 87%

Free hemoglobin increases von Willebrand factor–mediated platelet adhesion in vitro: implications for circulatory devices

Teruya

Guchhait

et al. 2015

Blood

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“…2C) (30). In addition, it was recently suggested that this A1 N-terminal sequence may bind A1 noncovalently (31). We therefore measured direct binding of BFP probes bearing a similar polypeptide Gln 1238 -Glu 1260 (Lp) to BFP targets coated with GPIb␣, VWF, 1238-A1, or 1261-A1.…”

Section: Gpib␣ Dissociates From 1238-a1 As a Triphasic Slip-catchslipmentioning

confidence: 99%

“…Furthermore, it has been shown that a 15-residue N-terminal sequence (1237-1251) can completely inhibit the binding of VWF to GPIb␣ (30). Recently, another sequence (Gln 1238 -Glu 1260 ) was suggested to be part of an autoinhibitory mechanism that stabilizes A1A2A3 interdomain associations (31). Still, how this short N-terminal flanking sequence regulates VWF-GPIb␣ interaction under force remains unclear.…”

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The N-terminal Flanking Region of the A1 Domain Regulates the Force-dependent Binding of von Willebrand Factor to Platelet Glycoprotein Ibα

Ju¹,

Dong

Crúz

et al. 2013

Journal of Biological Chemistry

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196

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“…Several lines of evidence indicate that plasma vWF is autoinhibited by internal domain-domain interactions between A2 and A1 (7), DЈD3 and A1 (8), as well as the N-terminal flanking region of A1 and A1A2A3 tridomain (9). An isolated recombinant A1 domain binds GPIb␣ spontaneously (10).…”

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A Mechanism for Localized Dynamics-driven Affinity Regulation of the Binding of von Willebrand Factor to Platelet Glycoprotein Ibα

Liu

Fang

2013

Journal of Biological Chemistry

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Background: Gain of function (GOF) mutations enhance the vWF-GPIb␣ interaction. Results: GOF mutations induce destabilization of the N-terminal arm and increase mobility of the ␣2-helix. Conclusion: Dynamics-driven up-regulation of A1 affinity to GPIb␣ serves as a GOF mechanism of type 2B mutations. Significance: These results are helpful in understanding the structural basis of GOF mutants and in developing allosteric drugs against the activated A1 domain.

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N-terminal Flanking Region of A1 Domain in von Willebrand Factor Stabilizes Structure of A1A2A3 Complex and Modulates Platelet Activation under Shear Stress

Cited by 42 publications

References 33 publications

Free hemoglobin increases von Willebrand factor–mediated platelet adhesion in vitro: implications for circulatory devices

Free hemoglobin increases von Willebrand factor–mediated platelet adhesion in vitro: implications for circulatory devices

The N-terminal Flanking Region of the A1 Domain Regulates the Force-dependent Binding of von Willebrand Factor to Platelet Glycoprotein Ibα

A Mechanism for Localized Dynamics-driven Affinity Regulation of the Binding of von Willebrand Factor to Platelet Glycoprotein Ibα

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