Collagen Receptor Signaling in Platelets and Megakaryocytes

Introduction

The extracellular matrix protein, collagen, plays a primary role in hemostasis. Collagen fibers provide an important site for adhesion of platelets to the exposed subendothelium, trapping them at the site of vascular damage and enabling the formation of a monolayer of cells over the damaged area. Collagen fibers also stimulate platelet activation, leading to inside-out regulation of the integrin glycoprotein (GP) IIb-IIIa (also known as α_IIbβ₃), secretion from dense and α granules, generation of thromboxanes, and expression of procoagulant activity, all of which support the hemostatic process. The role of collagen in supporting platelet adhesion to the subendothelium is mediated through indirect and direct interactions. The indirect interaction is mediated through von Willebrand factor (vWF), which binds to the GP Ib-IX-V complex on the platelet surface.^1-3 The interaction with vWF is critical for platelet adhesion at medium to high rates of flow because of the fast rate of association between vWF and GP Ib-IX. The importance of this interaction is demonstrated by the severe bleeding problems experienced by individuals with functional impairment of vWF (von Willebrand disease) or GP Ib-IX (Bernard-Soulier syndrome). At low rates of flow, collagen fibers are able to support adhesion in the absence of vWF through a direct interaction with a number of platelet surface glycoproteins i.e. collagen receptors,^4,5 this also serves to support vWF-dependent adhesion at higher rates of flow by preventing dissociation. Crosslinking of platelet surface glycoproteins by collagen also generates intracellular signals, leading to platelet activation.

The number of proteins on the platelet surface proposed to be collagen receptors is approaching double figures, but it is generally accepted that the integrin GP Ia-IIa (also known as α₂β₁) and glycoprotein VI (GP VI) are among the most important of these, playing critical roles in adhesion and activation, respectively⁶ (Fig. 1). This is illustrated by the mild bleeding problems of patients with a low level of expression or the presence of autoantibodies to GP Ia-IIa and the spontaneous, severe bleeding episodes that are occasionally seen in patients whose platelets are deficient in GP VI.⁶ There is evidence, however, that other collagen receptors have supporting roles in adhesion and activation. For example, GP VI supports platelet adhesion to collagen⁷ and GP IV, also known as CD36, may also play a similar role.⁸ The role of the recently cloned collagen receptor p65 in adhesion is not known. Evidence that the interaction of collagen with receptors, such as GPIV and p65, is of less importance than for interactions with GP Ia-IIa, and GP VI is provided by the absence of individuals with bleeding problems caused by deficiencies in these proteins. This is illustrated most clearly for GP IV, which is absent in 3% to 5 % of the Japanese population, and yet such individuals display no major vascular problems.

Due to the large number of glycoproteins that bind collagen on the platelet surface, it has been difficult to gain a full understanding of the role of individual collagen receptors in adhesion and activation responses. This is complicated further by the interactions between vWF and GP Ib-IX-V, vWF or fibrinogen to activated GP IIb-IIIa especially as both glycoprotein receptors generate intracellular signals. The relative importance of individual collagen receptors in adhesion also varies with the rate of flow and between collagen types. A full discussion of platelet adhesion to collagen is beyond the scope of this article, and the reader is referred to a number of excellent recent reviews for further information.^4-6,9,10 The present chapter focuses on the signaling events generated by the activation (or more correctly crosslinking) of platelet surface glycoproteins by collagen and the implications that this has for platelet activation under normal and diseased conditions.

• References

• 1 Ruggeri ZM. Mechanisms initiating platelet thrombus formation. Thromb Haemost 1997; 78: 611-616.
• 2 Savage B, Almus-Jacobs F, Ruggeri ZM. Specific synergy of multiple substrate-receptor interactions in platelet thrombus formation under flow. Cell 1998; 94: 657-666.
• 3 Berndt MC. The GPIb IX-V complex in platelet adhesion and signaling. Thromb Haemost. In press.
• 4 Sixma JJ, van Zanten GH, Saelman EU, Verkleij M, Lankhof H, Nieuwenhuis HK, de Groot PG. Platelet adhesion to collagen. Thromb Haemost 1995; 74: 454-459.
• 5 Sixma JJ, van Zanten GH, Huizinga EG, van der Plas RM, Verkley M, Wu YP, Gros P, de Groot PG. Platelet adhesion to collagen: an update. Thromb Haemost 1997; 78: 434-438.
• 6 Watson SP, Gibbins J. Collagen receptor signaling in platelets: extending the role of the ITAM. Immunol Today 1998; 19: 260-265.
• 7 Moroi M, Jung SM, Shinmyozu K, Tomiyama Y, Ordinas A, Diaz-Ricart M. Analysis of platelet adhesion to a collagen-coated surface under flow conditions: the involvement of glycoprotein VI in the platelet adhesion. Blood 1996; 68: 2081-2092.
• 8 Nakamura T, Jamieson GA, Okuma M, Kambayashi J-I, Tandon NN. Platelet adhesion to native type I collagen fibrils: role of GPVI in divalent cation-dependent and -independent adhesion and thromboxane A₂ generation. J Biol Chem 1998; 273: 4338-4344.
• 9 Moroi M, Jung SM. Platelet receptors for collagen. Thromb Haemost 1997; 78: 439-444.
• 10 Barnes MJ, Knight CG, Farndale RW. The collagen-platelet interaction. Curr Opin Hematol 1998; 5: 314-320.
• 11 Sugiyama T, Okuma M, Ushikubi F, Sensaki S, Kanaji K, Uchino H. A novel platelet aggregating factor found in a patient with defective collagen-induced platelet aggregation and autoimmune thrombocytopenia. Blood 1987; 69: 1712-1720.
• 12 Blake RA, Schieven GL, Watson SP. Collagen stimulates tyrosine phosphorylation of phospholipase C-γ2 but not phospholipase C-γ1 in human platelets. FEBS Lett 1994; 353: 212-216.
• 13 Daniel JL, Dangelmaier C, Smith JB. Evidence for a role for tyrosine phosphorylation of phospholipase Cγ2 in collagen-induced platelet cytosolic calcium mobilisation. Biochem J 1994; 302: 617-622.
• 14 Ichinohe T, Takayama H, Ezumi Y, Arai M, Yamamoto N, Takahasi H, Okuma M. Collagen-stimulated activation of Syk but not c-Src is severely compromised in human platelets lacking membrane glycoprotein VI. J Biol Chem 1997; 272: 63-68.
• 15 Ichinohe T, Takayama H, Ezumi Y, Yanagi S, Yamamura H, Okuma M. Cyclic AMP-insensitive activation of c-Src and Syk protein-tyrosine kinases through platelet membrane of glycoprotein VI. J Biol Chem 1995; 270: 28029-28036.
• 16 Blake RA, Asselin J, Walker T, Watson S. Fcγ receptor II stimulated formation of inositol phosphates in human platelets is blocked by tyrosine kinase inhibitors and associated with tyrosine phosphorylation of the receptor. FEBS Lett 1994; 342: 15-18.
• 17 Yanaga F, Poole A, Asselin J, Blake R, Schieven GL, Clark EA, Law CL, Watson SP. Syk interacts with tyrosine-phosphorylated proteins in human platelets activated by collagen and crosslinking of the Fcγ-IIA receptor. Biochem J 1995; 311: 471-478.
• 18 Gibbins JM, Asselin J, Farndale RW, Barnes MJ, Law CL, Watson SP. Tyrosine phosphorylation of the Fc receptor γ-chain in collagen-stimulated platelets. J Biol Chem 1996; 271: 18095-18099.
• 19 Poole A, Gibbins JM, Turner M, van Vugt MJ, van de Winkel JG, Saito T, Tybulewicz VL, Watson SP. The Fc receptor gamma-chain and the tyrosine kinase Syk are essential for activation of mouse platelets by collagen. EMBO J 1997; 16: 2333-2341.
• 20 Gibbins JM, Okuma M, Farndale RW, Barnes MJ, Watson SP. Glycoprotein VI is the collagen receptor in platelets which underlie tyrosine phosphorylation of the Fc receptor gamma-chain. FEBS Lett 1997; 413: 255-259.
• 21 Tsuji M, Ezumi Y, Arai M, Takayama H. A novel association of Fc receptor γ-chain with glycoprotein VI and their co-expression as a collagen receptor in human platelets. J Biol Chem 1997; 272: 23528-23531.
• 22 Morton LF, Hargreaves PG, Farndale RW, Young RD, Barnes MJ. Integrin alpha 2 beta 1-independent activation of platelets by simple collagen-like peptides: collagen tertiary triple-helical) and quaternary polymeric) structures are sufficient alone for alpha 2 beta 1-independent platelet reactivity. Biochem J 1995; 306: 337-344.
• 23 Asselin J, Gibbins JM, Achison M, Lee Y-H, Morton LF, Farndale RW, Barnes MJ, Watson SP. A collagen-like peptide stimulates tyrosine phosphorylation of syk and phospholipase Cγ2 in platelets independent of the integrin α₂β₁ . Blood 1997; 89: 1235-1242.
• 24 Kehrel B, Wierwille S, Clemetson KJ, Anders O, Steiner M, Knight CG, Farndale RW, Okuma M, Barnes MJ. Glycoprotein VI is a major collagen receptor for platelet activation: it recognizes the platelet activating quaternary structure of collagen, whereas CD36, glycoprotein IIb/IIIa, and von Willebrand factor do not. Blood 1998; 91: 491-499.
• 25 Jandrot-Perrus M, Lagrue AH, Okuma M, Bon C. Adhesion and activation of human platelets induced by convulxin involves glycoprotein GI and integrin α₂β₁ . J Biol Chem 1997; 272: 27035-27041.
• 26 Polgar J, Clemetson JM, Kehrel BE, Wiedemann M, Magnenat EM, Well TNC, Clemetson KJ. Platelet activation and signal transduction by convulxin, a C-type lectin from Crotalus durissus terrificus (tropical rattlesnake) venom via the p62/GPVI collagen receptor. J Biol Chem 1997; 272: 13576-13583.
• 27 Quek LS, Bolen J, Watson SP. Regulation of Bruton’s tyrosine kinase and phospholipase Cγ2 in collagen-stimulated platelets. Curr Biol 1998; 8: 1137-1140.
• 28 Robinson A, Gibbins J, Rodriguez-Linares B, Finan P, Wilson L, Kellie S, Findall P, Watson S. Characterisation of Grb2-binding proteins in human platelets activated by FcγRIIA crosslinking. Blood 1996; 88: 522-530.
• 29 Gross B, Lee JR, Clements JL, Turner M, Tybulewicz VL, Findell PR, Koretzky GA, Watson SP. Tyrosine phoshorylation of SLP-76 is downstream of Syk following stimulation of the collagen receptor GPVI in platelets. J Biol Chem 1999; 274: 5963-5971.
• 30 Gibbins JM, Briddon S, Shutes A, van Vugt MJ, van de Winkel JG, Saito T, Watson SP. The p85 subunit of phosphatidylinositol 3-kinase associates with the Fc receptor gamma-chain and LAT in platelets stimulated by collagen and convulxin. J Biol Chem 1998; 273: 34437-34443.
• 31 Oda A, Ochs H, Druker B, Ozaki K, Watanabe C, Handa M, Miyakawa Y, Ikeda Y. Collagen induces tyrosine phosphorylation of Wiskott-Aldrich Syndrome protein in human platelets. Blood 1998; 92: 1852-1858.
• 32 Ezumi Y, Shindoh K, Tsuji M, Takayama H. 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 1998; 188: 267-276.
• 33 Briddon SJ, Watson SP. Evidence for the involvement of p59 fyn and p53/56lyn in signaling via the collagen receptor in human platelets. Biochem J 1999; 337: 203-209.
• 34 Furlong MT, Mahrenholz AM, Kim K-H, Ashendel CL, Marrison ML, Geahlen RL. Identification of the major sites of autophosphorylation of the murine protein-tyrosine kinase syk. Biochim Biophys Acta 1997; 1355: 177-180.
• 35 Zhang W, Sloan-Lancaster J, Kitchen J, Trible RP, Samelson LE. LAT: the zap-70 tyrosine kinase substrate that links T cell receptor to cellular activation. Cell 1998; 92: 83-92.
• 36 Sieh M, Batzer A, Schlessinger J, Weiss A. GRB2 and phospholipase C-γ1 asociate with a 36- to 38-kilodalton phosphotyrosine protein after T-cell receptor stimulation. Mol Cell Biol 1994; 14: 4435-4442.
• 37 Finco TS, Kadlecek T, Zhang W, Samelson LE, Weiss A. LAT is required for TCR-mediated activation of PLCγ1 and the Ras pathway. Immunity 1998; 9: 617-626.
• 38 Jackman JK, Motto DG, Sun Q, Tanemoto M, Turck CW, Peltz GA, Koretzky GA, Findell PR. Molecular cloning of SLP-76, a 76-kDa tyrosine phosphoprotein associated with Grb2 in T cells. J Biol Chem 1995; 270: 7029-7032.
• 39 Yablonski D, Kuhne MR, Kadlecek T, Weiss A. Uncoupling of nonreceptor tyrosine kinases form PLC-γ1 in an SLP-76-deficient T cell. Science 1998; 281: 413-416.
• 40 Gross BS, Melford SK, Watson SP. Evidence that PLC-γ2 interacts with SLP-76, Syk, Lat, Lyn and the FcR γ-chain following stimulation of the collagen receptor in human platelets. Eur J Biochem..
• 41 Clements JL, Lee JR, Gross B, Yang B, Olson JD, Sandra A, Watson SP, Lentz SR, Koretzky GA. Fetal hemorrhage and platelet dysfunction in SLP-76-deficient mice. J Clin Invest 1999; 103: 19-25.
• 42 Pasquet JM, Bobe R, Gross B, Gratacap MP, Tomlinson M, Payrastre B, Watson SP. A collagen related peptide regulates phospholipase Cγ2 via phosphatidylinositol 3-kinase in human platelets. Biochem J. 1999 in press.
• 43 Pasquet JM, Gross BG, Mountford JC, Quek L, Gratacap MP, Pasquet S, Asselin JA, Payrastre B, van Willigen G, Watson SP. The cytokine thrombopoietin potentiates ITAM-mediated receptor signaling in platelets through phosphatidylinositol 3-kinase. 1999 Submitted.
• 44 Falasca M, Logan SK, Lehto VP, Baccante G, Lemmon MA, Schlessinger J. Activation of phospholipase Cγ by PI 3-kinase-induced PH domain-mediated membrane targeting. EMBO J 1998; 17: 414-422.
• 45 Bae YS, Cantley LG, Chen C-S, Kim S-R, Kwon K-S, Rhee SG. Activation of phospholipase C-γ by phosphatidylinositol 3,4,5-trisphosphate. J Biol Chem 1998; 273: 4465-4469.
• 46 Gratacap MP, Payrastre B, Viala C, Mauco G, Plantavid M, Chap H. Phosphatidylinositol 3,4,5-trisphosphate-dependent stimulation of phospholipase C-γ2 is an early key event in FcγRIIA-mediated activation of human platelets. J Biol Chem 1998; 273: 24314-24321.
• 47 Scharenberg AM, El-Hillal O, Fruman DA, Beitz LO, Li Z, Lin S, Gout I, Cantley LC, Rawlings DJ, Kinet JP. Phosphatidylinositol-3,4,5-trisphosphate PtdIns-2,3,4-P3)/Tec kinase dependent calcium signaling pathway: a target for SHIP-mediated inhibitory signals. EMBO J 1998; 17: 1961-1972.
• 48 Bauer M, Retzer M, Wilde JI, Maschberger P, Essler M, Aepfelbacher M, Watson S, Siess W. Dichotomous regulation of myosin phosphorylation and shape change by Rho-kinase and calcium in intact platelets. Blood. in press.
• 49 Essen LO, Perisic O, Cheung R, Katan M, Williams RL. Crystal structure of a mammalian phosphoinositide-specific phospholipase C delta. Nature 1996; 380: 595-602.
• 50 Crespo P, Schuebel KE, Ostrom AA, Gutkind JS, Bustelo XR. Phosphotyrosine-dependent activation of Rac-1 GDP/GTP exchange by the vav proto-oncogene product. Nature 1997; 385: 169-172.
• 51 Deckert M, Tartare-Deckert S, Couture C, Mustelin T, Altman A. Functional and physical interactions of syk family kinases with the vav proto-oncogene. Immunity 1996; 95: 591-604.
• 52 Brickell PM, Katz DR, Thrasher AJ. Wiskott-Aldrich syndrome: current research concepts. J Haemost 1998; 101: 603-608.
• 53 Borsch-Haubold AG, Kramer RM, Watson SP. Cytosolic phospholipase A2 is phosphorylated in collagen-and thrombin-stimulated human platelets independent of protein kinase C and mitogen activated protein kinase. J Biol Chem 1995; 270: 25885-25892.
• 54 Borsch-Haubold AG, Bartoli F, Asselin J, Dudler T, Kramer RM, Apitz-Castro R, Watson SP, Gelb MH. Identification of the phosphorylation sites of cytosolic phospholipase A2 in agonist-stimulated human platelets and HeLa cells. J Biol Chem 1998; 273: 4449-4458.
• 55 Borsch-Haubold AG, Kramer RM, Watson SP. Regulation of cytosolic phospholipase A2 by p38mapk in collagen-stimulated human platelets. Eur J Biochem 1997; 245: 751-759.
• 56 Borsch-Haubold AG, Schieltz D, Ghomashchi F, Yates JR, Hunter T, Watson SP, Gelb M. Mnk1 phosphorylates cytosolic phospholipase A2 at serine 727. Submitted for publication.
• 57 Knight CG, Morton LF, Onley DJ, Peachey AR, Ichinohe T, Okuma M, Farndale RW, Barnes MJ. Collagen-platelet interaction: Gly-Pro-Hyp is uniquely specific for platelet Gp VI and mediates platelet activation by collagen. Cardiovasc Res 1999; 41: 450-457.
• 58 Barnes MJ, Knight CG, Farndale RW. The use of collagen-based model peptides to investigate platelet-reactive sequences in collagen. Biopolymers 1996; 40: 383-397.
• 59 Rudd CE, Janssen O, Cai Y-C, Silva AJ, Raab M, Prasad KV. Two-step TCRz/CD3-CD4 and CD28 signaling in T cells: SH2/SH3 domains, protein-tyrosine and lipid kinases. Immunol Today 1994; 15: 225-234.
• 60 Keely PJ, Parise LV. The α₂β₁ integrin is a necessary co-receptor for collagen-induced activation of Syk and the subsequent phosphorylation of phospholipase C-γ2 in platelets. J Biol Chem 1996; 271: 26668-26676.
• 61 Coller BS, Beer JH, Scudder LE, Steinberg MH. Collagen-platelet interactions: evidence for a direct interaction of collagen with platelet GPIa/IIa and an indirect interaction with platelet GP IIb/IIIa mediated by adhesive proteins. Blood 1989; 74: 182-189.
• 62 Kamiguti AS, Hay CR, Zuzel M. Inhibition of collagen-induced platelet aggregation as the result of cleavage of α₂β₁-integrin by the snake venom metalloproteinase jararhagin. Biochem J 1996; 320: 635-641.
• 63 Kamiguti AS, Markland FS, Zhou Q, Laing GD, Theakston RD, Zuzel M. Proteolytic cleavage of the beta1 subunit of platelet alpha2beta1 integrin by the metalloproteinase jararhagin compromises collagen-stimulated phosphorylation of pp72. J Biol Chem 1997; 272: 32599-32605.
• 64 Huang T-F, Liu C-Z, Yang S-H. Aggretin, a novel platelet-aggregation inducer from snake Calloselasma rhodostoma) venom, activates phospholipase C by acting as a glycoprotein Ia/IIa agonist. Biochem J 1995; 309: 1021-1027.
• 65 Teng CM, Ko FN, Tsai IH, Hung ML, Huang TF. Trimucytin: a collagen-like aggregating inducer isolated from Trimeresurus mucrosquamatus snake venom. Thromb Haemost 1993; 69: 286-292.
• 66 Knight CG, Morton LF, Onley DJ, Peachey AR, Messent AJ, Smethurst PA, Tuckwell DS, Farndale RW, Barnes MJ. Identification in collagen type I of an integrin α₂β₁-binding site containing an essential GER sequence. J Biol Chem 1998; 273: 33287-33294.
• 67 Chiang TM, Rinaldy A, Kang AH. Cloning, characterization, and functional studies of a nonintegrin platelet receptor for type I collagen. J Clin Invest 1997; 100: 514-521.
• 68 Daniel JL, Dangelmaier C, Strouse R, Smith JB. Collagen induces normal signal transduction in platelets deficient in CD36 platelet glycoprotein IV). Thromb Haemost 1994; 71: 353-356.
• 69 Huang M-M, Bolen JB, Barnwell JW, Shattil SJ, Brugge JS. Membrane glycoprotien IC CD36) is physically associated with the Fyn, Lyn, and Yes protein-tyrosine kinases in human platelets. Proc Natl Acad Sci USA 1991; 88: 7844-7848.
• 70 Shattil S. Thromb Haemost. 1999
• 71 Mountford JC, Melford SK, Bunce CM, Gibbins JM, Watson SP. Collagen elevates Ca2+ in human megakaryocytes but not in megakaryocyte-like cell lines. Thromb Haemost. in press.
• 72 Melford SK, Turner M, Briddon SJ, Tybulewicz VL, Watson SP. Syk and Fyn are required by mouse megakaryocytes for the rise in intracellular calcium induced by a collagen-related peptide. J Biol Chem 1997; 272: 27539-27542.
• 73 Briddon SJ, Melford SK, Turner M, Tybulewicz VL, Watson SP. Collagen mediates changes in intracellular calcium in primary mouse megakaryocytes through Syk-dependent and -independent pathways. Blood 1999; 93: 3847-3855.
• 74 Nahamura T, Kambayahi J, Okuma M, Tandan NN. Activation of the GPIIb-IIIa complex induced by platelet adhesion to collagen in medicated by both α₂β₁ integrin and GPVI. J Biol Chem 1999; 274: 11897-11903.
• 75 Hheemskerk JWM, Siljander P, Vuist WM, Breikers G, Reutelingsperger CPM, Barnes M, Knight CG, Lassila R, Farndale RW. Function of glycoprotien VI an integrin α₂β₁ in the procoagulant response of single collagen-adherent platelets. Thrombo Haemost 81: 782-792.