A central goal of my laboratory has been to determine how thrombin regulates cellular behaviors involved in hemostasis, thrombosis, inflammation and other processes, and to elucidate the roles of thrombin signaling in vivo. This grant has focused on hemostasis and thrombosis. Our previous work showed that protease- activated receptors (PARs) are necessary for platelet activation by thrombin and important for thrombosis and hemostasis in mouse models. These and other studies support exploration of PAR antagonism for the prevention or treatment of thrombosis in humans. We now propose studies to define the roles of PARs in more detail and to determine how thrombin signaling integrates with other platelet activation and coagulation mechanisms in vivo. We shall ask:1) Are vWF, collagen and thrombin the major initiators of platelet activation in vivo? How do these pathways interact? Using sophisticated mouse models, we will test the hypothesis that GPIb and GP-VI signaling is necessary and sufficient to drive platelet adhesion and juxtamural thrombus formation at a site of injury but that PAR signalingis necessary for propagation of the thrombus away from the vessel wall. Genetic and pharmacological approaches will be used. PAR interactions with P2Y12 and Tbxa2r (TP) will also be probed. 2) How do thrombin-inducedplatelet activation and fibrin formation interact in hemostasis and thrombosis? Does their relative importance change when thrombin generation or activity is reduced or inhibited? We shall determine whether platelet activation by thrombin is important for propagation of thrombin generation and fibrin formation away from the vessel wall. We shall also ask whether disruption of PAR signalingin the setting of low thrombin generation has synergistic effects on thrombosis or hemostasis. 3) What is the role of tissue factor expression in endothelial and hematopoietic cells in hemostasis and thrombosis? In endotoxemia? Can roles for such tissue factor be uncovered or amplified by knockout of alternative mechanisms for propagation of coagulation? Tissue factor expression will be ablated in endothelial and hematopoietic tissues to probe the source and roles of """"""""circulatingtissue factor"""""""". These studies will illuminate how key effectors of hemostasis and thrombosis interact.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL065185-10
Application #
7729851
Study Section
Special Emphasis Panel (ZRG1-HEME-F (02))
Program Officer
Link, Rebecca P
Project Start
2000-09-05
Project End
2012-11-30
Budget Start
2009-12-01
Budget End
2012-11-30
Support Year
10
Fiscal Year
2010
Total Cost
$375,049
Indirect Cost
Name
University of California San Francisco
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
094878337
City
San Francisco
State
CA
Country
United States
Zip Code
94143
Zhang, Cheng; Srinivasan, Yoga; Arlow, Daniel H et al. (2012) High-resolution crystal structure of human protease-activated receptor 1. Nature 492:387-92
Yang, Huanghe; Kim, Andrew; David, Tovo et al. (2012) TMEM16F forms a Ca2+-activated cation channel required for lipid scrambling in platelets during blood coagulation. Cell 151:111-22
Shao, Bojing; Wahrenbrock, Mark G; Yao, Longbiao et al. (2011) Carcinoma mucins trigger reciprocal activation of platelets and neutrophils in a murine model of Trousseau syndrome. Blood 118:4015-23
Cornelissen, Ivo; Palmer, Daniel; David, Tovo et al. (2010) Roles and interactions among protease-activated receptors and P2ry12 in hemostasis and thrombosis. Proc Natl Acad Sci U S A 107:18605-10
Hamilton, J R; Cornelissen, I; Mountford, J K et al. (2009) Atherosclerosis proceeds independently of thrombin-induced platelet activation in ApoE-/- mice. Atherosclerosis 205:427-32
Regard, Jean B; Sato, Isaac T; Coughlin, Shaun R (2008) Anatomical profiling of G protein-coupled receptor expression. Cell 135:561-71
Camerer, Eric; Cornelissen, Ivo; Kataoka, Hiroshi et al. (2006) Roles of protease-activated receptors in a mouse model of endotoxemia. Blood 107:3912-21
Su, Xiao; Camerer, Eric; Hamilton, Justin R et al. (2005) Protease-activated receptor-2 activation induces acute lung inflammation by neuropeptide-dependent mechanisms. J Immunol 175:2598-605
Hamilton, J R; Cornelissen, I; Coughlin, S R (2004) Impaired hemostasis and protection against thrombosis in protease-activated receptor 4-deficient mice is due to lack of thrombin signaling in platelets. J Thromb Haemost 2:1429-35
Camerer, Eric; Duong, Daniel N; Hamilton, Justin R et al. (2004) Combined deficiency of protease-activated receptor-4 and fibrinogen recapitulates the hemostatic defect but not the embryonic lethality of prothrombin deficiency. Blood 103:152-4

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