Constitutive Dimerization of Glycoprotein VI (GPVI) in Resting Platelets Is Essential for Binding to Collagen and Activation in Flowing Blood

Jung, Stéphanie; Moroi, Masaaki; Soejima, Kenji; Nakagaki, Tomohiro; Miura, Yoshiki; Berndt, Michael C.; Gardiner, Elizabeth E.; Howes, Joanna‐Marie; Pugh, Nicholas; Bihan, Dominique; Watson, Steve P.; Farndale, Richard W.

doi:10.1074/jbc.m112.359125

Cited by 87 publications

(132 citation statements)

References 33 publications

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“…Recent studies indicate that elevation of cAMP, cGMP, and prostacyclin inhibit GPVI dimerization, which is essential for its function. 23,31 It is likely that the GPVI activation defect observed in Bdkrb2 2/2 platelets is related to this mechanism.…”

Section: Discussionmentioning

confidence: 99%

Angiotensin 1-7 and Mas decrease thrombosis in Bdkrb2−/− mice by increasing NO and prostacyclin to reduce platelet spreading and glycoprotein VI activation

Fang

Stavrou²,

Schmaier

et al. 2013

Blood

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Section: Discussionmentioning

confidence: 99%

Angiotensin 1-7 and Mas decrease thrombosis in Bdkrb2−/− mice by increasing NO and prostacyclin to reduce platelet spreading and glycoprotein VI activation

Fang

Stavrou²,

Schmaier

et al. 2013

Blood

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“…Moreover, GPVI lateral mobility on the cell surface was reduced by approximately 50% in the absence of Tspan9. Since GPVI clustering is important for its activation and signalling [10, 11], a reduction in its lateral diffusion could explain the observed platelet aggregation and secretion defects. No defects in GPVI clustering on collagen were observed by super-resolution imaging, but these experiments were done on fully spread platelets and would not detect a delay in the kinetics of clustering.…”

Section: Discussionmentioning

confidence: 99%

“…This is followed by downstream phosphorylation and assembly of a signalosome nucleated by the adapter protein LAT, phospholipase Cγ2 (PLCγ2) activation, Ca 2+ mobilisation, platelet shape change, granule secretion, integrin activation and platelet spreading and aggregation [1, 4]. GPVI recognises collagen as a dimer, and a proportion of GPVI exists as a dimer on resting platelets, with dimer levels increasing upon platelet activation [10, 11]. GPVI has been reported to be lipid raft-associated [12–14] and more recently to be a component of a distinct type of microdomain formed by tetraspanin transmembrane proteins [15].…”

Section: Introductionmentioning

confidence: 99%

Tetraspanin Tspan9 regulates platelet collagen receptor GPVI lateral diffusion and activation

et al. 2016

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The tetraspanins are a superfamily of four-transmembrane proteins, which regulate the trafficking, lateral diffusion and clustering of the transmembrane proteins with which they interact. We have previously shown that tetraspanin Tspan9 is expressed on platelets. Here we have characterised gene-trap mice lacking Tspan9. The mice were viable with normal platelet numbers and size. Tspan9-deficient platelets were specifically defective in aggregation and secretion induced by the platelet collagen receptor GPVI, despite normal surface GPVI expression levels. A GPVI activation defect was suggested by partially impaired GPVI-induced protein tyrosine phosphorylation. In mechanistic experiments, Tspan9 and GPVI co-immunoprecipitated and co-localised, but super-resolution imaging revealed no defects in collagen-induced GPVI clustering on Tspan9-deficient platelets. However, single particle tracking using total internal reflection fluorescence microscopy showed that GPVI lateral diffusion was reduced by approximately 50% in the absence of Tspan9. Therefore, Tspan9 plays a fine-tuning role in platelet activation by regulating GPVI membrane dynamics.

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“…22,23 Collagen binds with high affinity to dimeric but not to monomeric GPVI, with conversion of monomers to dimers being a key step in collagen-mediated platelet activation. 19,24 In the present study, we measured binding of monomeric and dimeric GPVI to immobilized fibrin using SPR.…”

Section: Fibrin Binds To Monomeric Gpvimentioning

confidence: 99%

Fibrin and D-dimer bind to monomeric GPVI

et al. 2017

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Key Points• GPVI is the major signaling receptor for fibrin in human platelets; the GPVI binding site is located in the fibrin D-dimer region.• D-dimer blocks platelet aggregation by fibrin and collagen but not by a collagen-related peptide, suggesting a distinct binding epitope.Fibrin has recently been shown to activate platelets through the immunoglobulin receptor glycoprotein VI (GPVI). In the present study, we show that spreading of human platelets on fibrin is abolished in patients deficient in GPVI, confirming that fibrin activates human platelets through the immunoglobulin receptor. Using a series of proteolytic fragments, weshow that D-dimer, but not the E fragment of fibrin, binds to GPVI and that immobilized D-dimer induces platelet spreading through activation of Src and Syk tyrosine kinases. In contrast, when platelets are activated in suspension, soluble D-dimer inhibits platelet aggregation induced by fibrin and collagen, but not by a collagen-related peptide composed of a repeat GPO sequence or by thrombin. Using surface plasmon resonance, we demonstrate that fibrin binds selectively to monomeric GPVI with a K D of 302 nM, in contrast to collagen, which binds primarily to dimeric GPVI. These results establish GPVI as the major signaling receptor for fibrin in human platelets and provide evidence that fibrin binds to a distinct configuration of GPVI. This indicates that it may be possible to develop agents that selectively block the interaction of fibrin but not collagen with the immunoglobulin receptor. Such agents are required to establish whether selective targeting of either interaction has the potential to lead to development of an antithrombotic agent with a reduced effect on bleeding relative to current antiplatelet drugs.

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Constitutive Dimerization of Glycoprotein VI (GPVI) in Resting Platelets Is Essential for Binding to Collagen and Activation in Flowing Blood

Cited by 87 publications

References 33 publications

Angiotensin 1-7 and Mas decrease thrombosis in Bdkrb2−/− mice by increasing NO and prostacyclin to reduce platelet spreading and glycoprotein VI activation

Angiotensin 1-7 and Mas decrease thrombosis in Bdkrb2−/− mice by increasing NO and prostacyclin to reduce platelet spreading and glycoprotein VI activation

Tetraspanin Tspan9 regulates platelet collagen receptor GPVI lateral diffusion and activation

Fibrin and D-dimer bind to monomeric GPVI

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