Expression of Fibrinogen on the Surface of ADP-Stimulated Platelets: Comparison of Human and Rabbit Platelets

Harfenist, EJ; Packham, MA; Mustard, J. F.

doi:10.1055/s-0038-1642779

Cited by 13 publications

(8 citation statements)

References 19 publications

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“…The tetrapeptide RGDS has been shown to inhibit aggregation by inhibiting the binding of fibrinogen, fibronectin, and von Willebrand factor to activated gpIlb-IIIa, without inhibiting shape change or secretion (24)(25)(26)(27). In agreement with these reports, we found that RGDS inhibited thrombin-induced aggregation without altering the extent or kinetics of thrombin-induced shape change (not shown).…”

Section: Resultssupporting

confidence: 81%

Tyrosine-specific protein phosphorylation is regulated by glycoprotein IIb-IIIa in platelets.

Ferrell

Martin

1989

Proc. Natl. Acad. Sci. U.S.A.

244

101

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We have previously shown that a number of platelet proteins become phosphorylated at tyrosine residues in response to platelet-activating agents. Here we present two lines of evidence implicating a platelet integrin, glycoprotein lib-HIa, in the regulation of a specific subset of these tyrosine phosphorylations. (i) Two peptides that inhibit the binding of fibrinogen and other ligands to gpllb-IIIa, Arg-Gly-Asp-Ser and His-His-!Leu-Gly-Gly-Ala-Lys-Gln-Ala-Gly-Asp-Val, also inhibited the thrombin-induced tyrosine phosphorylation of this subset of proteins. The tetrapeptide Arg-Gly-Glu-Ser, which does not inhibit fibrinogen binding, did not inhibit thrombin-stimulated tyrosine phosphorylation. (u) Platelets lacking gpIlb-IIla (from a subject with Glanzmann thrombasthenia) did not undergo this subset of tyrosine phosphorylations in response to thrombin, although other serine, threonine, and tyrosine phosphorylations proceeded normally. These findings suggest a role for tyrosine-specific protein phosphorylation in integrin-mediated cell-matrix recognition.

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Section: Resultssupporting

confidence: 81%

Tyrosine-specific protein phosphorylation is regulated by glycoprotein IIb-IIIa in platelets.

Ferrell

Martin

1989

Proc. Natl. Acad. Sci. U.S.A.

244

101

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“…This is in contrast with RGDS and trigramin peptides shown to inhibit thrombininduced platelet aggregation without preventing the granule release reaction [31,33,391. The tetrapeptide KRDS could thus interfere with earlier steps such as the signaling system.…”

Section: Discussionmentioning

confidence: 99%

KRDS, a new peptide derived from human lactotransferrin, inhibits platelet aggregation and release reaction

Mazoyer

Lévy-Toledano

Rendu

et al. 1990

European Journal of Biochemistry

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KRDS (Lys-Arg-Asp-Ser), a tetrapeptide from human lactotransferrin, was tested in vitro on human platelet function, and its effects were compared to those of RGDS, a tetrapeptide from human fibrinogen. Both peptides had a high probability of initiating a p-turn and were highly hydrophilic. KRDS inhibited ADP-induced platelet aggregation [median inhibitory concentration (1C5,J 350 pM] and fibrinogen binding 360 pM) to a lesser extent than RGDS (IC50 75 pM and 20 pM, respectively). Different from RGDS, thrombin-induced serotonin release was inhibited by KRDS (750 pM) on normal platelets (55 loo/,) and type I Glanzmann's thrombasthenia platelets (43% f 1). However, KRDS had no effect on cytoplasmic Ca2 + mobilization, inositol phospholipid metabolism or protein phosphorylation (myosin light chain P20 and P43). In contrast to RGDS, KRDS does not inhibit the binding of monoclonal antibody PAC-1 to activated platelets. KRDS and RGDS inhibited 4P-phorbol-12-myristate-13-acetate (PMA)-induced aggregation and fibrinogen binding, while proteins were normally phosphorylated. Thus, the tetrapeptide KRDS is (a) an inhibitor of serotonin release by a mechanism independent of protein phosphorylation and (b) an inhibitor of fibrinogen binding and, hence, aggregation by a mechanism that may not necessarily involve its direct binding to the glycoprotein IIb-IIIa-complex.It is well established [l, 21 that fibrinogen interaction with platelets is essential for platelet aggregation and that fibrinogen binds to a specific receptor on the platelet surface: the glycoprotein IIb-IIIa complex (GPIIb-IIIa). Unstimulated platelets do not bind fibrinogen. In type I Glanzmann's thrombasthenia, characterized by the absence of platelet membrane GPIIb-IIIa, fibrinogen binding and ADP-or thrombininduced platelet aggregation are not observed. Yet the mechanisms of fibrinogen receptor exposure on the platelet surface and of fibrinogen interaction with GPIIb-IITa are not completely understood. Two binding sites have been identified on the fibrinogen molecule: a decapeptide in the carboxy-terminal region of the y-chain (LGGAKQAGDV; residues 402 -41 1) and a tetrapeptide in the carboxy-terminal region of the a-chain (RGDS; residues 572-575). Both peptides inhibit aggregation and fibrinogen binding to ADP-activated platelets [3]. Recently it has been shown that RGDS becomes more chemically cross-linked to residues 109-171 of GPIIIa number of similarities have been previously reported between these two clotting processes [6, 71. Moreover, structural homology has been found between cow K-casein and human fibrinogen y-chain [8]. Recently, Jolles et al. [9] showed that both the natural and the corresponding synthetic undecapeptide MAIPPKKNQDK of cow K-casein (residues 106-116) were more inhibitory of ADP-induced platelet aggregation and fibrinogen binding than the C-terminal dodecapeptide, HHLGGAKQAGDV, of the human fibrinogen y-chain (residues 400-411). Based on these observations, we looked for a peptide from a milk protein that is structurally and fun...

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“…3), although the A16 mutant does not bind to ligandmimetic antibodies. It is well known that RGD peptide does not effectively block fibrinogen binding to rat and rabbit (44) and mouse ␣ IIb ␤ 3 . It is possible that ␣ IIb ␤ 3 from these species may have higher affinity to fibrinogen than human ␣ IIb ␤ 3 due to species difference in site A16.…”

Section: What Do the Discontinuous Binding Sites In ␣ Iib For Ligandmmentioning

confidence: 99%

Multiple Discontinuous Ligand-mimetic Antibody Binding Sites Define a Ligand Binding Pocket in Integrin αIIbβ3

Puzon-McLaughlin

Kamata

Takada

2000

Journal of Biological Chemistry

102

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Integrin ␣ IIb ␤ 3 , a platelet fibrinogen receptor, is critically involved in thrombosis and hemostasis. However, how ligands interact with ␣ IIb ␤ 3 has been controversial. Ligand-mimetic anti-␣ IIb ␤ 3 antibodies (PAC-1, LJ-CP3, and OP-G2) contain the RGD-like RYD sequence in their CDR3 in the heavy chain and have structural and functional similarities to native ligands. We have located binding sites for ligand-mimetic antibodies in ␣ IIb and ␤ 3 using human-to-mouse chimeras, which we expect to maintain functional integrity of ␣ IIb ␤ 3 . Here we report that these antibodies recognize several discontinuous binding sites in both the ␣ IIb and ␤ 3 subunits; these binding sites are located in residues 156 -162 and 229 -230 of ␣ IIb and residues 179 -183 of ␤ 3 . In contrast, several nonligand-mimetic antibodies (e.g. 7E3) recognize single epitopes in either subunit. Thus, binding to several discontinuous sites in both subunits is unique to ligand-mimetic antibodies. Interestingly, these binding sites overlap with several (but not all) of the sequences that have been reported to be critical for fibrinogen binding (e.g. N-terminal repeats 2-3 but not repeats 4 -7, of ␣ IIb ). These results suggest that ligand-mimetic antibodies and probably native ligands may make direct contact with these discontinuous binding sites in both subunits, which may constitute a ligand-binding pocket.Integrin ␣ IIb ␤ 3 is a platelet fibrinogen receptor that is critically involved in platelet aggregation (1). Thus ␣ IIb ␤ 3 -fibrinogen interaction is a therapeutic target for thrombosis and hemostasis. However, how ligands interact with the integrin ␣ IIb and ␤ 3 subunits has been the subject of much discussion.The ␣ IIb subunit has seven repeated sequences of 60 -70 residues each in its N-terminal portion. Two different regions of the ␣ IIb subunit have been implicated in ligand binding. The second metal binding site of ␣ IIb (residues 294 -314 in N-terminal repeat 5 of ␣ IIb ) has been identified as a ligand binding site by chemically cross-linking the ␥-peptide (HHLGGAKQ-AGDV 400 -411 ) of the fibrinogen ␥ chain C-terminal domain (2). Both the peptide derived from this ␣ IIb sequence and its antibodies have been shown to block fibrinogen binding to ␣ IIb ␤ 3 (3). Consistently, recombinant bacterial proteins that consist of repeats 4 -7 of ␣ IIb (residues 171-464) have been shown to bind to ligands in a cation-dependent manner (4). On the other hand, alanine-scanning mutagenesis (5) 1 suggests that the predicted loops in repeats 2 and 3 are critical for ligand binding. Also, function-blocking anti-␣ IIb ␤ 3 monoclonal antibodies (mAbs) 2 are mapped in repeats 2 and 3 (5). 1 It has not been established which regions of ␣ IIb actually interact with ligands.The presence of an I-domain-like structure within the ␤ subunit has been suggested based on the similarity in hydropathy profiles between the I-domain of the ␣ M subunit and part of the ␤ subunit (6). The N-terminal region of the ␤ 3 subunit has components that are critical for ligand...

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Expression of Fibrinogen on the Surface of ADP-Stimulated Platelets: Comparison of Human and Rabbit Platelets

Cited by 13 publications

References 19 publications

Tyrosine-specific protein phosphorylation is regulated by glycoprotein IIb-IIIa in platelets.

Tyrosine-specific protein phosphorylation is regulated by glycoprotein IIb-IIIa in platelets.

KRDS, a new peptide derived from human lactotransferrin, inhibits platelet aggregation and release reaction

Multiple Discontinuous Ligand-mimetic Antibody Binding Sites Define a Ligand Binding Pocket in Integrin αIIbβ3

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