Hemostasis can be viewed as a complex series of membrane-mediated events culminating in platelet adhesion, surface activation, and aggregation. The mechanisms through which a receptor-mediated stimulus at the platelet surface leads to platelet plug formation and generation of thrombin are largely unknown. It is generally recognized, however, that the platelet cytoskeleton plays a critical role in shape change, degranulation, and surface adhesion during the hemostatic process. In the erythrocyte, the spectrin-ankyrin-band 3 axis provides a detailed linkage between the cell surface and the submembranous cytoskeleton. To date, immunoreactive forms of both spectrin and ankyrin have been found in a variety of cells and tissues, although their precise roles are not yet fully defined.
The aims of this study will be to identify an analog of the spectrin-ankyrin-band 3 complex in human platelets, and to examine its role as a potential mediator of platelet surface activation, aggregation and adhesion. These investigations will employ standard biochemial separation techniques, as well as two-dimensional peptide mapping, immunoprecipitation methods using monospecific antibodies to purified proteins, anad fluorescence and electron microscopy. It is anticipated that these studies will provide insight, on a molecular level, into the mechanisms of normal platelet function. In addition, the present work could be extended to include an analysis of cytoskeletal protein interactions in platelets from patients with clinical disorders of hemostasis and thrombosis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08HL001352-04
Application #
3081771
Study Section
(SRC)
Project Start
1984-06-01
Project End
1989-05-31
Budget Start
1987-06-01
Budget End
1988-05-31
Support Year
4
Fiscal Year
1987
Total Cost
Indirect Cost
Name
Weill Medical College of Cornell University
Department
Type
Schools of Medicine
DUNS #
201373169
City
New York
State
NY
Country
United States
Zip Code
10065
Hajjar, D P; Nicholson, A C; Hajjar, K A et al. (1989) Decreased messenger RNA translation in herpesvirus-infected arterial cells: effects on cholesteryl ester hydrolase. Proc Natl Acad Sci U S A 86:3366-70
Hajjar, K A; Nachman, R L (1988) Endothelial cell-mediated conversion of Glu-plasminogen to Lys-plasminogen. Further evidence for assembly of the fibrinolytic system on the endothelial cell surface. J Clin Invest 82:1769-78
Staiano-Coico, L; Hajjar, D P; Hefton, J M et al. (1988) Interactions of arterial cells: III. Stathmokinetic analyses of smooth muscle cells cocultured with endothelial cells. J Cell Physiol 134:485-90
Hajjar, K A; Hamel, N M; Harpel, P C et al. (1987) Binding of tissue plasminogen activator to cultured human endothelial cells. J Clin Invest 80:1712-9
Hajjar, K A; Hajjar, D P; Silverstein, R L et al. (1987) Tumor necrosis factor-mediated release of platelet-derived growth factor from cultured endothelial cells. J Exp Med 166:235-45
Hajjar, D P; Marcus, A J; Hajjar, K A (1987) Interactions of arterial cells. Studies on the mechanisms of endothelial cell modulation of cholesterol metabolism in co-cultured smooth muscle cells. J Biol Chem 262:6976-81
Hajjar, K A; Harpel, P C; Jaffe, E A et al. (1986) Binding of plasminogen to cultured human endothelial cells. J Biol Chem 261:11656-62
Nachman, R L; Hajjar, K A; Silverstein, R L et al. (1986) Interleukin 1 induces endothelial cell synthesis of plasminogen activator inhibitor. J Exp Med 163:1595-600
Hajjar, K A (1985) Structural and functional analysis of spectrin from neonatal erythrocytes. Biochim Biophys Acta 827:460-5
Hajjar, K A (1985) Philadelphia chromosome-positive chronic myelogenous leukemia following apparent acute lymphoblastic leukemia. Clin Pediatr (Phila) 24:402-5