This proposal will test the hypothesis that platelet membrane glycoprotein GPIIb-IIIa is a member of the cytoadhesin family of structurally, immunochemically and functionally related membrane proteins. The involvement of platelets in thrombotic diseases and in hemostasis is dependent upon their adhesive properties. Platelet adhesive reactions are regulated by their interaction with a set of adhesive proteins, which includes fibrinogen, fibronectin and von Willebrand Factor. GPIIb-IIIa serves as a receptor for these adhesive proteins and has a recognition specificity for the Arg-Gyl-Asp sequence. This sequence occurs in the three platelet adhesive proteins, and Arg- Gly-Asp containing peptides inhibit the binding of these proteins to platelets. GPIIb-IIIa is not restricted to platelets as immunologically related molecules have now been identified on endothelial cells, fibroblasts, smooth muscle cells, erythoroleukemic cells and monocytoid cells. These widely distributed cell surface molecules share the gross structural properties of being comprised of two similar subunits, one of approximately 100 kD and the second of approximately 140 kD. At least two of these molecules, GPIIb-IIIa and the vitronectin receptor, are Arg-Gly-Asp receptors. Based upon these lines of evidence, the existence of the cytoadhesin family and the membership of GPIIb-IIIa in this family is postulated, and this hypothesis will be explored. The structural and immunochemical relationship among the cytoadhesins will be examined to determine if their subunits are comprised of common and cell- specific regions. This will be accomplished by developing and characterizing the reactivity of a series of anti-peptide antibody reagents. In addition, the immunological relationship between GPIIb-IIIa and the endothelial cell cytoadhesin will be explored in detail. The primary structure of GPIIb-IIIa will be deduced by gene cloning approaches, and the distribution of mRNA for the cytoadnesins in cells and in tissues will be established. A functional linkage among the cytoadhesins will be sought by assessing their role as Arg-Gly-Asp receptors and their capacity to bind adhesive proteins. Finally, specific roles of cytoadhesins in selected cellular functions will be evaluated. The role of vitronectin as a platelet adhesive protein and the contribution of the cytoadhesins and the Arg-Gly-Asp recognition specificity in platelets-monocytes and neutrophil-endothelial cell interactions will be evaluated. On an overall basis, these studies should provide fundamental insight into the mechanisms underlying cell adhesion.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL038292-03
Application #
3354473
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
1987-07-01
Project End
1992-06-30
Budget Start
1989-07-01
Budget End
1990-06-30
Support Year
3
Fiscal Year
1989
Total Cost
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
City
San Diego
State
CA
Country
United States
Zip Code
92037
Suehiro, K; Gailit, J; Plow, E F (1997) Fibrinogen is a ligand for integrin alpha5beta1 on endothelial cells. J Biol Chem 272:5360-6
Zhang, L; Plow, E F (1996) A discrete site modulates activation of I domains. Application to integrin alphaMbeta2. J Biol Chem 271:29953-7
Suehiro, K; Smith, J W; Plow, E F (1996) The ligand recognition specificity of beta3 integrins. J Biol Chem 271:10365-71
Zhang, L; Plow, E F (1996) Overlapping, but not identical, sites are involved in the recognition of C3bi, neutrophil inhibitory factor, and adhesive ligands by the alphaMbeta2 integrin. J Biol Chem 271:18211-6
Ugarova, T P; Ljubimov, A V; Deng, L et al. (1996) Proteolysis regulates exposure of the IIICS-1 adhesive sequence in plasma fibronectin. Biochemistry 35:10913-21
Haas, T A; Plow, E F (1996) The cytoplasmic domain of alphaIIb beta3. A ternary complex of the integrin alpha and beta subunits and a divalent cation. J Biol Chem 271:6017-26
Ugarova, T P; Zamarron, C; Veklich, Y et al. (1995) Conformational transitions in the cell binding domain of fibronectin. Biochemistry 34:4457-66
Cierniewski, C S; Haas, T A; Smith, J W et al. (1994) Characterization of cation-binding sequences in the platelet integrin GPIIb-IIIa (alpha IIb beta 3) by terbium luminescence. Biochemistry 33:12238-46
D'Souza, S E; Haas, T A; Piotrowicz, R S et al. (1994) Ligand and cation binding are dual functions of a discrete segment of the integrin beta 3 subunit: cation displacement is involved in ligand binding. Cell 79:659-67
Muchowski, P J; Zhang, L; Chang, E R et al. (1994) Functional interaction between the integrin antagonist neutrophil inhibitory factor and the I domain of CD11b/CD18. J Biol Chem 269:26419-23

Showing the most recent 10 out of 26 publications