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.
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20 July 1998
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July 20 1998
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
Yasuharu Ezumi,
Yasuharu Ezumi
From the Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
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Keisuke Shindoh,
Keisuke Shindoh
From the Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
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Masaaki Tsuji,
Masaaki Tsuji
From the Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
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Hiroshi Takayama
Hiroshi Takayama
From the Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
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Yasuharu Ezumi
From the Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
Keisuke Shindoh
From the Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
Masaaki Tsuji
From the Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
Hiroshi Takayama
From the Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
Address correspondence to Hiroshi Takayama, The Department of Hematology and Oncology, Clinical Sciences for Pathological Organs, Graduate School of Medicine, Kyoto University, 54 Shogoin-Kawaracho, Sakyo-ku, Kyoto 606-8507, Japan. Phone: 81-75-751-3151; Fax: 81-75-751-3201; E-mail: [email protected]
Received:
March 04 1998
Revision Received:
April 30 1998
Online ISSN: 1540-9538
Print ISSN: 0022-1007
1998
J Exp Med (1998) 188 (2): 267–276.
Article history
Received:
March 04 1998
Revision Received:
April 30 1998
Citation
Yasuharu Ezumi, Keisuke Shindoh, Masaaki Tsuji, Hiroshi Takayama; 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 . J Exp Med 20 July 1998; 188 (2): 267–276. doi: https://doi.org/10.1084/jem.188.2.267
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