GPIIb-IIIa, integrin alphaIIb-beta3, mediates platelet aggregation by serving as an inducible receptor for fibrinogen and other adhesive proteins. This function establishes an essential role for GPIIb-IIIa in hemostasis and thrombotic diseases, the leading cause of death in the U.S. Because of the central contribution of GPIIb-IIIa in physiology and pathophysiology, detailed understanding of the structure and function of this adhesion receptor is essential, and this objective is the ultimate goal of this proposal. The applicants hypothesize that an unidentified discrete amino acid sequence within GPIIb-IIIa serves as a contact site for the carboxy-terminus of the gamma chain of fibrinogen, and engagement of this site is essential for platelet aggregation. Accordingly, the gamma-chain contact site within the receptor will be localized utilizing chemical crosslinking, synthetic peptides and molecular biology approaches (Specific Aim 1). Recently, they have proposed a molecular mechanism for ligand binding to GPIIb-IIIa: recognition sequences within the ligand, contact sequences within the receptor, and divalent cations form a ternary intermediate complex; and, subsequently, cation is displaced from this complex during the ligand binding event. This model will be put to a critical test (Specific Aim 2). The cytoplasmic domain of GPIIb-IIIa forms a binding site for intercellular constituents, such as cytoskeletal elements and signaling molecules. They hypothesize that the cytoplasmic domain of each subunit exists in a specific conformation and may, in fact, interact with each other to form a unique structure. They propose to characterize the conformation and interaction of these cytoplasmic tails utilizing specifically designed and constrained synthetic peptides (Specific Aim 3). They further hypothesize that the conformation and complexation of the cytoplasmic tails of the GPIIb and GPIIIa subunits control the activation state of the receptor and mediate specific interactions with intracellular constituents. These specific functions of he cytoplasmic tails will be tested (Specific Aim 4). Overall, the proposed studies are anticipated to provide insights into the structure and function of GPIIb-IIIa, may lead to the design of more effective and safer agents to control and prevent thrombosis, and should yield broadly applicable information regarding ligand binding and activation of other members of the integrin adhesion family.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL054924-03
Application #
2460150
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
1995-08-01
Project End
2000-07-31
Budget Start
1997-08-01
Budget End
1998-07-31
Support Year
3
Fiscal Year
1997
Total Cost
Indirect Cost
Name
Cleveland Clinic Lerner
Department
Type
DUNS #
017730458
City
Cleveland
State
OH
Country
United States
Zip Code
44195
Song, Xianqiang; Yang, Jun; Hirbawi, Jamila et al. (2012) A novel membrane-dependent on/off switch mechanism of talin FERM domain at sites of cell adhesion. Cell Res 22:1533-45
Podolnikova, Nataly P; Yakubenko, Valentin P; Volkov, George L et al. (2003) Identification of a novel binding site for platelet integrins alpha IIb beta 3 (GPIIbIIIa) and alpha 5 beta 1 in the gamma C-domain of fibrinogen. J Biol Chem 278:32251-8
Cierniewska-Cieslak, Aleksandra; Cierniewski, Czeslaw S; Blecka, Kamila et al. (2002) Identification and characterization of two cation binding sites in the integrin beta 3 subunit. J Biol Chem 277:11126-34
Plow, E F; Cierniewski, C S; Xiao, Z et al. (2001) AlphaIIbbeta3 and its antagonism at the new millennium. Thromb Haemost 86:34-40
Forsyth, C B; Solovjov, D A; Ugarova, T P et al. (2001) Integrin alpha(M)beta(2)-mediated cell migration to fibrinogen and its recognition peptides. J Exp Med 193:1123-33
Yakubenko, V P; Solovjov, D A; Zhang, L et al. (2001) Identification of the binding site for fibrinogen recognition peptide gamma 383-395 within the alpha(M)I-domain of integrin alpha(M)beta2. J Biol Chem 276:13995-4003
Byzova, T V; Kim, W; Midura, R J et al. (2000) Activation of integrin alpha(V)beta(3) regulates cell adhesion and migration to bone sialoprotein. Exp Cell Res 254:299-308
Cierniewski, C S; Byzova, T; Papierak, M et al. (1999) Peptide ligands can bind to distinct sites in integrin alphaIIbbeta3 and elicit different functional responses. J Biol Chem 274:16923-32
Forsyth, C B; Plow, E F; Zhang, L (1998) Interaction of the fungal pathogen Candida albicans with integrin CD11b/CD18: recognition by the I domain is modulated by the lectin-like domain and the CD18 subunit. J Immunol 161:6198-205
Byzova, T V; Plow, E F (1998) Activation of alphaVbeta3 on vascular cells controls recognition of prothrombin. J Cell Biol 143:2081-92

Showing the most recent 10 out of 17 publications