This renewal application proposes to continue ongoing studies of the structure and function of integrin (cytoadhesin) adhesion receptors. Integrins, cell-surface heterodimeric molecules, mediate a very broad range of cell-cell and cell-matrix interactions and, thereby, control a diverse set of cellular functions and responses. Two integrins, alpha4/beta1, and alphaM/beta2, have been implicated in many physiological events, including the development of the immune response and hematopoiesis, and pathophysiologic events, including inflammation, reprefusion injury and atherosclerosis. The overall objective of this proposal is to establish the molecular basis for ligand binding to these two integrins as a means of understanding their function. It is further anticipated that insights derived from studies of these two integrins will be broadly applicable and contribute to a general understanding of the ligand binding functions of integrin receptors. Small peptide ligands for alpha4/beta1 and alphaM/beta2 have been identified, and these will be used to define the precise recognition specificities of these two receptors. Covalent crosslinking strategies, similar to those which we have successfully employed to identify ligand recognition sites in alphaIIb/beta3, will then be used to localize sequences within these integrins that mediate ligand binding. Synthetic peptides, monoclonal antibody and mutational strategies will then be brought to bear to definitively establish the role of identified regions in receptor function. Independent strategies, cobalt oxidation to evaluate the role of the metal binding domains and hydropathic complementarity, will also be applied to define the ligand binding mechanisms of alpha4/beta1 and alphaM/beta2. In addition to these studies, a novel hypothesis that fibrinogen functions as a bridging molecule for linking leukocytes to endothelium will be tested. Fibrinogen markedly enhances alphaM/beta2-dependent leukocyte adhesion to endothelial cells, and the molecular and cellular specificity of this effect will be assessed under both static and flowing conditions. By defining the molecular basis for ligand binding functions of alphaM/beta2 and alpha4/beta1 and other integrins and by providing insights into the basis for leukocyte : endothelial cell interactions, which are central to many physiological and pathophysiological processes, our studies have the potential to lead to new approaches to treat inflammation, atherosclerosis and other vascular disorders and diseases.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL038292-06
Application #
3354471
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
1987-07-01
Project End
1992-12-31
Budget Start
1992-07-01
Budget End
1992-12-31
Support Year
6
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Scripps Research Institute
Department
Type
DUNS #
City
La Jolla
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

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