The purpose of this investigation is to develop a highly selective proteolytic inhibitor of a-thrombin that prevents its interaction with platelet receptors but does not interfere wit a-thrombin cleaving other substrates. The hypothesis of this proposal is that bradykinin-related sequences are inhibitors of a -thrombin cleaving certain physiologic substrates. Developing a highly selective thrombin inhibitor directed to the cloned thrombin receptor on cells would have applicability to prevent arterial thrombosis due to platelet thrombus. A new generation of selective a-thrombin inhibitors needs to be developed since nonspecific proteolytic inhibitors of a-thrombin, e.g. hirudin and hirulog, are associated with increased cerebral hemorrhage. This project will create a new class of selective a-thrombin inhibitors. These agents will be the first of a second generation a-thrombin inhibitors that selectively block a-thrombin s ability to activate platelets without interfering with its ability to activate factor V and VIII and clot fibrinogen The specific aims of this proposal are as follows: 1. The mechanism of selective inhibition of a-thrombin by RPPGF will be characterized. Investigations will be performed to determine if RPPGF binds to platelets and insect cells which express the clone thrombin receptor. Further, investigations will be performed to determine if RPPGF binds to Protein C and Protein S. 2. The structural requirements for RPPGF to inhibit a-thrombin will be characterized with the aim towards the development of a novel class of selective, a-thrombin inhibitors. 3. Animal experiments will be performed in rabbits to determine the efficacy of these peptides to prevent arterial thrombosis in vivo models. These proposed investigations will determine the mechanism of inhibition and efficacy of using RPPGF and its congers as selective anti-thrombins. These investigations should characterize a new class of a-thrombin inhibitors which inhibit this enzyme's ability to cleave the cloned thrombin receptor. The importance of these studies is that they could introduce a novel pharmacologic approach to prevent arterial thrombosis.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL056415-01A1
Application #
2030050
Study Section
Surgery and Bioengineering Study Section (SB)
Project Start
1997-02-01
Project End
2000-01-31
Budget Start
1997-02-01
Budget End
1998-01-31
Support Year
1
Fiscal Year
1997
Total Cost
Indirect Cost
Name
University of Michigan Ann Arbor
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
791277940
City
Ann Arbor
State
MI
Country
United States
Zip Code
48109
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Hasa, A A; Schmaier, A H; Warnock, M et al. (2001) Thrombostatin inhibits cyclic flow variations in stenosed canine coronary arteries. Thromb Haemost 86:1296-304
Mahdi, F; Shariat-Madar, Z; Todd 3rd, R F et al. (2001) Expression and colocalization of cytokeratin 1 and urokinase plasminogen activator receptor on endothelial cells. Blood 97:2342-50
Hasan, A A; Warnock, M; Srikanth, S et al. (2001) Developing peptide inhibitors to thrombin activation of platelets from bradykinin analogs. Thromb Res 104:451-65
Hasan, A A; Rebello, S S; Smith, E et al. (1999) Thrombostatin inhibits induced canine coronary thrombosis. Thromb Haemost 82:1182-7
Schmaier, A H (1998) Plasma contact activation: a revised hypothesis. Biol Res 31:251-62
Rojkjaer, R; Hasan, A A; Motta, G et al. (1998) Factor XII does not initiate prekallikrein activation on endothelial cells. Thromb Haemost 80:74-81