C1q, the recognition unit of the classical complement pathway, is a multifunctional glycoprotein consisting of collagen-like and globular domains. Evidence is accumulating to suggest that many cells including platelets and endothelial cells possess recognition sites for both the collagen-like region of C1q and for the globular domain. Because C1q accumulates at sites of vascular injury and inflammation, and has been identified in atherosclerotic lesions, platelet and endothelial cell C1q receptors may play an important role in the cellular response of blood to injury. To better understand the structure and function of platelet and endothelial cell C1qR, the present application will 1) investigate the cell surface expression and distribution of both cC1qR and gC1qR using immunochemical techniques and confocal scanning laser microscopy, 2) define ligand binding to cC1qR and gC1qR using purified c1, C1q, or its globular and collagen-like domains as well as monoclonal and polyclonal anti cC1qR and anti gC1qR antibodies, 3) identify gC1qR sequences responsible for ligand binding using site directed mutagenesis, 4) characterize the cellular response to C1qR occupancy using scanning electron microscopy to evaluate cell adhesion to immobilized C1q and extracellular matrix proteins, and biochemical and functional assays to assess platelet and endothelial cell activation, as well as C1q-induced heterotypic interactions between platelets, endothelial cells, monocytes, and neutrophils, and 5) evaluate the biosynthesis of endothelial cell cC1qR and gC1qR particularly in response to C1qR occupancy and inflammatory cytokines using biosynthetic and immunochemical assays. Results from these studies will provide new insights into the contribution of platelet and endothelial cell C1q receptors to vascular lesions and inflammation.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL050291-05
Application #
2750383
Study Section
Hematology Subcommittee 2 (HEM)
Project Start
1995-09-01
Project End
2000-07-31
Budget Start
1998-08-01
Budget End
2000-07-31
Support Year
5
Fiscal Year
1998
Total Cost
Indirect Cost
Name
Weill Medical College of Cornell University
Department
Pathology
Type
Schools of Medicine
DUNS #
201373169
City
New York
State
NY
Country
United States
Zip Code
10065
Bossi, Fleur; Fischetti, Fabio; Regoli, Domenico et al. (2009) Novel pathogenic mechanism and therapeutic approaches to angioedema associated with C1 inhibitor deficiency. J Allergy Clin Immunol 124:1303-10.e4
Ghebrehiwet, Berhane; Feng, Xiaodong; Kumar, Rajeev et al. (2003) Complement component C1q induces endothelial cell adhesion and spreading through a docking/signaling partnership of C1q receptors and integrins. Int Immunopharmacol 3:299-310
Kumar, Rajeev; Peerschke, Ellinor I B; Ghebrehiwet, Berhane (2002) Zinc induces exposure of hydrophobic sites in the C-terminal domain of gC1q-R/p33. Mol Immunol 39:69-75
Feng, Xiaodong; Tonnesen, Marcia G; Peerschke, Ellinor I B et al. (2002) Cooperation of C1q receptors and integrins in C1q-mediated endothelial cell adhesion and spreading. J Immunol 168:2441-8
Ghebrehiwet, Berhane; Jesty, Jolyon; Peerschke, Ellinor I B (2002) gC1q-R/p33: structure-function predictions from the crystal structure. Immunobiology 205:421-32
Szabo, J; Cervenak, L; Toth, F D et al. (2001) Soluble gC1q-R/p33, a cell protein that binds to the globular ""heads"" of C1q, effectively inhibits the growth of HIV-1 strains in cell cultures. Clin Immunol 99:222-31
Peerschke, E I; Ghebrehiwet, B (2001) Human blood platelet gC1qR/p33. Immunol Rev 180:56-64
Nguyen, T; Ghebrehiwet, B; Peerschke, E I (2000) Staphylococcus aureus protein A recognizes platelet gC1qR/p33: a novel mechanism for staphylococcal interactions with platelets. Infect Immun 68:2061-8
Peerschke, E I (1999) Maintenance of GPIIb-IIIa avidity supporting ""irreversible"" fibrinogen binding is energy-dependent. J Lab Clin Med 134:398-404
Lu, P D; Galanakis, D K; Ghebrehiwet, B et al. (1999) The receptor for the globular ""heads"" of C1q, gC1q-R, binds to fibrinogen/fibrin and impairs its polymerization. Clin Immunol 90:360-7

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