Glycoprotein VI is the collagen receptor in platelets which underlies tyrosine phosphorylation of the Fc receptor ??-chain

1997 ◽  
Vol 8 (7) ◽  
pp. 459
Author(s):  
J. M. Gibbins ◽  
M. Okuma ◽  
R. Farndale ◽  
M. Barnes ◽  
S. P. Watson
Keyword(s):  
Tyrosine Phosphorylation ◽  
Fc Receptor ◽  
Glycoprotein Vi ◽  
Receptor Chain ◽  
Collagen Receptor

scholarly journals Glycoprotein VI/Fc receptor γ chain-independent tyrosine phosphorylation and activation of murine platelets by collagen

2004 ◽  
Vol 383 (3) ◽  
pp. 581-588 ◽  
Author(s):  
Gavin E. JARVIS ◽  
Denise BEST ◽  
Steve P. WATSON
Keyword(s):  
Tyrosine Phosphorylation ◽  
Chain Complex ◽  
Fc Receptor ◽  
Adapter Protein ◽  
Wild Type ◽  
Functional Responses ◽  
Glycoprotein Vi ◽  
Src Homology 2 ◽  
Src Homology ◽  
Collagen Receptor

We have investigated the ability of collagen to induce signalling and functional responses in suspensions of murine platelets deficient in the FcRγ (Fc receptor γ) chain, which lack the collagen receptor GPVI (glycoprotein VI). In the absence of the FcRγ chain, collagen induced a unique pattern of tyrosine phosphorylation which was potentiated by the thromboxane analogue U46619. Immunoprecipitation studies indicated that neither collagen alone nor the combination of collagen plus U46619 induced phosphorylation of the GPVI-regulated proteins Syk and SLP-76 (Src homology 2-containing leucocyte protein of 76 kDa). A low level of tyrosine phosphorylation of phospholipase Cγ2 was observed, which was increased in the presence of U46619, although the degree of phosphorylation remained well below that observed in wild-type platelets (∼10%). By contrast, collagen-induced phosphorylation of the adapter ADAP (adhesion- and degranulation-promoting adapter protein) was substantially potentiated by U46619 to levels equivalent to those observed in wild-type platelets. Collagen plus U46619 also induced significant phosphorylation of FAK (focal adhesion kinase). The functional significance of collagen-induced non-GPVI signals was highlighted by the ability of U46619 and collagen to induce the secretion of ATP in FcRγ chain-deficient platelets, even though neither agonist was effective alone. Protein tyrosine phosphorylation and the release of ATP were abolished by the anti-(α2 integrin) antibodies Ha1/29 and HMα2, but not by blockade of αIIbβ3. These results illustrate a novel mechanism of platelet activation by collagen which is independent of the GPVI–FcRγ chain complex, and is facilitated by binding of collagen to integrin α2β1.

scholarly journals Glycoprotein VI is the collagen receptor in platelets which underlies tyrosine phosphorylation of the Fc receptor γ-chain

FEBS Letters ◽  
1997 ◽  
Vol 413 (2) ◽  
pp. 255-259 ◽  
Author(s):  
Jonathan M Gibbins ◽  
Minoru Okuma ◽  
Richard Farndale ◽  
Michael Barnes ◽  
Stephen P Watson
Keyword(s):  
Tyrosine Phosphorylation ◽  
Fc Receptor ◽  
Glycoprotein Vi ◽  
Collagen Receptor

scholarly journals Physical and Functional Association of the Src Family Kinases Fyn and Lyn with the Collagen Receptor Glycoprotein VI-Fc Receptor γ Chain Complex on Human Platelets

1998 ◽  
Vol 188 (2) ◽  
pp. 267-276 ◽  
Author(s):  
Yasuharu Ezumi ◽  
Keisuke Shindoh ◽  
Masaaki Tsuji ◽  
Hiroshi Takayama
Keyword(s):  
Tyrosine Phosphorylation ◽  
Platelet Activation ◽  
Critical Role ◽  
Specific Inhibitor ◽  
Chain Complex ◽  
Human Platelets ◽  
Fc Receptor ◽  
Cross Linking ◽  
Glycoprotein Vi ◽  
Collagen Receptor

We have previously shown that uncharacterized glycoprotein VI (GPVI), which is constitutively associated and coexpressed with Fc receptor γ chain (FcRγ) in human platelets, is essential for collagen-stimulated tyrosine phosphorylation of FcRγ, Syk, and phospholipase Cγ2 (PLCγ2), leading to platelet activation. Here we investigated involvement of the Src family in the proximal signals through the GPVI–FcRγ complex, using the snake venom convulxin from Crotalus durissus terrificus, which specifically recognizes GPVI and activates platelets through cross-linking GPVI. Convulxin-coupled beads precipitated the GPVI–FcRγ complex from platelet lysates. Collagen and convulxin induced tyrosine phosphorylation of FcRγ, Syk, and PLCγ2 and recruited tyrosine-phosphorylated Syk to the GPVI–FcRγ complex. Using coprecipitation methods with convulxin-coupled beads and antibodies against FcRγ and the Src family, we showed that Fyn and Lyn, but not Yes, Src, Fgr, Hck, and Lck, were physically associated with the GPVI–FcRγ complex irrespective of stimulation. Furthermore, Fyn was rapidly activated by collagen or cross-linking GPVI. The Src family–specific inhibitor PP1 dose-dependently inhibited collagen- or convulxin-induced tyrosine phosphorylation of proteins including FcRγ, Syk, and PLCγ2, accompanied by a loss of aggregation and ATP release reaction. These results indicate that the Src family plays a critical role in platelet activation via the collagen receptor GPVI–FcRγ complex.

Fyn and Lyn phosphorylate the Fc receptor γ chain downstream of glycoprotein VI in murine platelets, and Lyn regulates a novel feedback pathway

Blood ◽  
2000 ◽  
Vol 96 (13) ◽  
pp. 4246-4253 ◽  
Author(s):  
Lynn S. Quek ◽  
Jean-Max Pasquet ◽  
Ingeborg Hers ◽  
Richard Cornall ◽  
Graham Knight ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Fc Receptor ◽  
Inhibitory Pathway ◽  
Functional Responses ◽  
Glycoprotein Vi ◽  
Granule Secretion ◽  
Activation Motif ◽  
Additional Role ◽  
Feedback Pathway

Abstract Activation of platelets by collagen is mediated by the complex glycoprotein VI (GPVI)/Fc receptor γ (FcRγ chain). In the current study, the role of 2 Src family kinases, Fyn and Lyn, in GPVI signaling has been examined using murine platelets deficient in one or both kinases. In the fyn−/−platelets, tyrosine phosphorylation of FcRγ chain, phopholipase C (PLC) activity, aggregation, and secretion are reduced, though the time of onset of response is unchanged. In the lyn−/−platelets, there is a delay of up to 30 seconds in the onset of tyrosine phosphorylation and functional responses, followed by recovery of phosphorylation and potentiation of aggregation and α-granule secretion. Tyrosine phosphorylation and aggregation in response to stimulation by collagen-related peptide is further attenuated and delayed in fyn−/−lyn−/−double-mutant platelets, and potentiation is not seen. This study provides the first genetic evidence that Fyn and Lyn mediate FcR immune receptor tyrosine-based activation motif phosphorylation and PLCγ2 activation after the ligation of GPVI. Lyn plays an additional role in inhibiting platelet activation through an uncharacterized inhibitory pathway.

A new monoclonal antibody, mAb 204-11, that influences the binding of platelet GPVI to fibrous collagen

2003 ◽  
Vol 89 (06) ◽  
pp. 996-1003 ◽  
Author(s):  
Jun Mizuguchi ◽  
Sachiko Kawashima ◽  
Michiko Nagamatsu ◽  
Yoshiki Miura ◽  
Tomohiro Nakagaki ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Platelet Aggregation ◽  
Binding Site ◽  
Tyrosine Phosphorylation ◽  
Platelet Activation ◽  
Collagen Binding ◽  
Glycoprotein Vi ◽  
Phosphorylation Of Proteins ◽  
Dimeric Form ◽  
Collagen Receptor

SummaryThe newly identified platelet collagen receptor glycoprotein VI binds to fibrous collagen, inducing platelet activation. Several antibodies against GPVI have been reported, including a patient’s auto-antibodies, that activates platelets through their ability to crosslink this glycoprotein. We have developed a monoclonal antibody (mAb) against GPVI using the recombinant extracellular domain of GPVI as an antigen. This antibody, mAb 204-11, induced platelet aggregation and tyrosine phosphorylation of proteins similar to those induced by GPVI-reactive proteins, collagen and convulxin. Its interaction with GPVI was analyzed by measuring the effect of the antibody on GPVI binding to collagen using a dimeric form of recombinant GPVI, GPVI-Fc2. MAb 204-11 inhibited the binding of GPVI-Fc2 to fibrous collagen particles, but enhanced the GPVI binding to immobilized collagen, suggesting that the antibody binds to a region near the collagen binding site of GPVI. MAb 204-11 also inhibited the GPVI binding to convulxin at a low concentration, but not completely. Since mAb 204-11 reacts specifically with GPVI and is applicable for immunoblotting and immunoprecipitation, this antibody would be useful for studies on GPVI.

Regulation and Function of WASp in Platelets by the Collagen Receptor, Glycoprotein VI

Blood ◽  
1999 ◽  
Vol 94 (12) ◽  
pp. 4166-4176 ◽  
Author(s):  
Barbara S. Gross ◽  
Jonathan I. Wilde ◽  
Lynn Quek ◽  
Helen Chapel ◽  
David L. Nelson ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Intracellular Signaling ◽  
Kinase Inhibitors ◽  
Critical Role ◽  
Functional Expression ◽  
Apparent Difference ◽  
Gene Encoding ◽  
Glycoprotein Vi ◽  
Dense Granules ◽  
Collagen Receptor

Abstract Wiskott Aldrich syndrome (WAS) is an X-linked recessive disorder associated with abnormalities in platelets and lymphocytes giving rise to thrombocytopenia and immunodeficiency. WAS is caused by a mutation in the gene encoding the cytoskeletal protein (WASp). Despite its importance, the role of WASp in platelet function is not established. WASp was recently shown to undergo tyrosine phosphorylation in platelets after activation by collagen, suggesting that it may play a selective role in activation by the adhesion molecule. In the present study, we show that WASp is heavily tyrosine phosphorylated by a collagen-related peptide (CRP) that binds to the collagen receptor glycoprotein (GP) VI, but not to the integrin 2β1. Tyrosine phosphorylation of WASp was blocked by Src family kinase inhibitors and reduced by treatment with wortmannin and in patients with X-linked agammaglobulinemia (XLA), a condition caused by a lack of functional expression of Btk. This indicates that Src kinases, phosphatidylinositol 3-kinase (PI 3-kinase), and Btk all contribute to the regulation of tyrosine phosphorylation of WASp. The functional importance of WASp was investigated in 2 WAS brothers who show no detectable expression of WASp. Platelet aggregation and secretion from dense granules induced by CRP and thrombin was slightly enhanced in the WAS platelets relative to controls. Furthermore, there was no apparent difference in morphology in WAS platelets after stimulation by these agonists. These observations suggest that WASp does not play a critical role in intracellular signaling downstream of tyrosine kinase-linked and G protein-coupled receptors in platelets.

Fyn and Lyn phosphorylate the Fc receptor γ chain downstream of glycoprotein VI in murine platelets, and Lyn regulates a novel feedback pathway

Blood ◽  
2000 ◽  
Vol 96 (13) ◽  
pp. 4246-4253 ◽  
Author(s):  
Lynn S. Quek ◽  
Jean-Max Pasquet ◽  
Ingeborg Hers ◽  
Richard Cornall ◽  
Graham Knight ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Fc Receptor ◽  
Inhibitory Pathway ◽  
Functional Responses ◽  
Glycoprotein Vi ◽  
Granule Secretion ◽  
Activation Motif ◽  
Additional Role ◽  
Feedback Pathway

Activation of platelets by collagen is mediated by the complex glycoprotein VI (GPVI)/Fc receptor γ (FcRγ chain). In the current study, the role of 2 Src family kinases, Fyn and Lyn, in GPVI signaling has been examined using murine platelets deficient in one or both kinases. In the fyn−/−platelets, tyrosine phosphorylation of FcRγ chain, phopholipase C (PLC) activity, aggregation, and secretion are reduced, though the time of onset of response is unchanged. In the lyn−/−platelets, there is a delay of up to 30 seconds in the onset of tyrosine phosphorylation and functional responses, followed by recovery of phosphorylation and potentiation of aggregation and α-granule secretion. Tyrosine phosphorylation and aggregation in response to stimulation by collagen-related peptide is further attenuated and delayed in fyn−/−lyn−/−double-mutant platelets, and potentiation is not seen. This study provides the first genetic evidence that Fyn and Lyn mediate FcR immune receptor tyrosine-based activation motif phosphorylation and PLCγ2 activation after the ligation of GPVI. Lyn plays an additional role in inhibiting platelet activation through an uncharacterized inhibitory pathway.

scholarly journals Differential role of glycolipid-enriched membrane domains in glycoprotein VI- and integrin-mediated phospholipase Cγ2 regulation in platelets

2002 ◽  
Vol 364 (3) ◽  
pp. 755-765 ◽  
Author(s):  
Peter WONEROW ◽  
Achim OBERGFELL ◽  
Jonathan I. WILDE ◽  
Régis BOBE ◽  
Naoki ASAZUMA ◽  
...  
Keyword(s):  
Tyrosine Phosphorylation ◽  
Membrane Domains ◽  
Adapter Protein ◽  
Glycoprotein Vi ◽  
Receptor Signalling ◽  
Fibrinogen Receptor ◽  
Fibrinogen Binding ◽  
Collagen Receptor ◽  
Lines Of Evidence

The platelet collagen receptor glycoprotein VI (GPVI) and the fibrinogen receptor integrin αIIbβ3 trigger intracellular signalling cascades involving the tyrosine kinase Syk, the adapter SLP-76 and phospholipase Cγ2 (PLCγ2). Similar pathways are activated downstream of immune receptors in lymphocytes, where they have been localized in part to glycolipid-enriched membrane domains (GEMs). Here we provide several lines of evidence that GPVI-mediated tyrosine phosphorylation of PLCγ2 in platelets is dependent on GEM-organized signalling and utilizes the GEM resident adapter protein LAT (linker for activation of T cells). In sharp contrast, although fibrinogen binding to platelets stimulates αIIbβ3-dependent activation of Syk and tyrosine phosphorylation of SLP-76 and PLCγ2, it does not utilize GEMs to promote these responses or to support platelet aggregation. These results establish that GPVI and αIIbβ3 trigger distinct patterns of receptor signalling in platelets, leading to tyrosine phosphorylation of PLCγ2, and they highlight the role of GEMs in compartmentalizing signalling reactions involved in haemostasis.

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