Tissue factor (TF)-dependent blood coagulation plays a primary role in hemostasis after tissue injury and also in pathogenesis. Binding of factor VII to TF is the initial step in TF-dependent blood coagulation. A key reaction must then follow: activation of the bound factor VII to give rise to catalytically active VIIa/TF complexes. Little is known about how the activation of factor VII and the subsequent VIIa/TF-catalytic activity are regulated in vivo and to what extent anti-coagulantly active cell surface heparin sulfate proteoglycans play a role in the regulation of these critical steps in TF-induced coagulation. Further, which specific amino acid side chains in VIIa and TF are involved in the recognition of tissue factor pathway inhibitor (TFPI) and the cell biology of VIIa/TF remain unknown. The primary focus of the present proposal is to obtain important information on these unanswered questions. The specific goals are: (1) Test a hypothesis, both in vitro and in vivo, that cell surface heparin sulfate proteoglycans limit activation of factor VII bound to TF expressed on cell surfaces and thereby regulated TF-induced coagulation (2) Test a hypothesis that recognition structures for substrate factor X presents in VIIa/TF complex contribute to the enhancing effect of Xa during the quaternary complex formation of VIIa/TF/TFPI/Xa (3) Test a hypothesis that cell surface TF redistributes upon complex formation with VIIa, Xa and TFPI and define the role of TFPI in this process (4) Test a hypothesis that the binding of TFPI/Xa to cell surface VIIa/TF affects internalization of cell surface VIIa/TF complexes and elucidate the intracellular trafficking of internalized VIIa and TF. In the proposed studies, various well established techniques, such as radioligand binding, coagulation assays, electron microscopy, and a rabbit intravascular coagulation model system will be used. Information obtained from these studies will aid in understanding important clinical issues, such as why infused factor VIIa is effective in controlling the bleeding in hemophiliacs. The above studies will further our understanding of the structural mechanism of macromolecular assembly of VIIa/TF/TFPI/Xa. Such an understanding may lead to the design and application of therapeutic measures aimed at the treatment of hemorrhagic disease and thrombotic complications.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL058869-04
Application #
6389737
Study Section
Hematology Subcommittee 2 (HEM)
Program Officer
Link, Rebecca P
Project Start
1998-04-01
Project End
2005-03-31
Budget Start
2001-04-01
Budget End
2005-03-31
Support Year
4
Fiscal Year
2001
Total Cost
$188,850
Indirect Cost
Name
University of Texas Health Center at Tyler
Department
Biochemistry
Type
Other Domestic Higher Education
DUNS #
City
Tyler
State
TX
Country
United States
Zip Code
75708
Nayak, Ramesh C; Keshava, Shiva; Esmon, Charles T et al. (2013) Rab GTPases regulate endothelial cell protein C receptor-mediated endocytosis and trafficking of factor VIIa. PLoS One 8:e59304
Vatsyayan, Rit; Kothari, Hema; Pendurthi, Usha R et al. (2013) 4-Hydroxy-2-nonenal enhances tissue factor activity in human monocytic cells via p38 mitogen-activated protein kinase activation-dependent phosphatidylserine exposure. Arterioscler Thromb Vasc Biol 33:1601-11
Kothari, H; Pendurthi, U R; Rao, L V M (2013) Analysis of tissue factor expression in various cell model systems: cryptic vs. active. J Thromb Haemost 11:1353-63
Keshava, S; Kothari, H; Rao, L V M et al. (2013) Influence of endothelial cell protein C receptor on breast cancer development. J Thromb Haemost 11:2062-5
Kothari, H; Pendurthi, U R; Rao, L V M (2013) Tissue factor purified from different cellular sources and non-glycosylated tissue factor show similar procoagulant activity. J Thromb Haemost 11:2066-8
Gopalakrishnan, R; Pendurthi, U R; Hedner, U et al. (2012) Influence of endothelial cell protein C receptor on plasma clearance of factor VIIa. J Thromb Haemost 10:971-3
Kothari, Hema; Rao, L Vijaya Mohan; Vankayalapati, Ramakrishna et al. (2012) Mycobacterium tuberculosis infection and tissue factor expression in macrophages. PLoS One 7:e45700
Sen, Prosenjit; Clark, Curtis A; Gopalakrishnan, Ramakrishnan et al. (2012) Factor VIIa binding to endothelial cell protein C receptor: differences between mouse and human systems. Thromb Haemost 107:951-61
Rao, L Vijaya Mohan; Kothari, Hema; Pendurthi, Usha R (2012) Tissue factor encryption and decryption: facts and controversies. Thromb Res 129 Suppl 2:S13-7
Rao, L V M; Pendurthi, U R (2012) Regulation of tissue factor coagulant activity on cell surfaces. J Thromb Haemost 10:2242-53

Showing the most recent 10 out of 61 publications