The coagulation cascade is initiated by binding of the coagulation factor VII(a) (FVIIa) to its cell surface receptor, tissue factor (TF). An aberrant expression of TF is the primary reason for thrombotic disorders associated with various diseases. Proper regulation of TF expression is critical for the maintenance of hemostatic balance and for health in general. The broad and long-term objective of the present proposal is to understand the mechanisms controlling the initiation and regulation of TF-dependent blood coagulation. The majority of TF on cell surfaces exists in a cryptic (coagulant inactive) state. A variety of cellular alterations could transform cryptic TF to coagulant active TF but at present it is unclear even how the coagulant active TF differs from the cryptic form or the mechanics involved in de-encryption of TF. The studies proposed in Aim 1 will examine the conflicting mechanisms that have been proposed to explain TF de-encryption and obtain new data that would provide a better understanding of the process of TF activation. In addition to TF encryption, TF endocytosis and exocytosis could also play a role in the regulation of TF activity at the cell surface but little is known about the molecular processes that regulate TF trafficking. Studies described in Aim 2 will identify and delineate mechanisms that are responsible for TF endocytosis and trafficking. Thus, the specific aims of the proposed studies are (1) delineate the molecular basis for TF activation, particularly in reference to thiol oxidation and phospholipid changes at the outer membrane, and (2) define mechanisms that regulate TF endocytosis and trafficking. The proposed studies will employ a variety of biochemical, molecular and cell biology techniques, including state-of-the art confocal microscopy. Data obtained from the proposed studies will provide new insights towards understanding how TF activity is regulated at cell surfaces and will resolve the recent controversy on TF activation. Overall, the knowledge gained from the proposed studies will be helpful in understanding the pathogenesis of thrombotic disorders and useful for designing better treatment strategies for both hemorrhagic and thrombotic disease 3.

Public Health Relevance

Thrombus formation is the precipitating event in acute myocardial infarction, unstable angina and ischemic stroke. Aberrant expression or activation of tissue factor (TF), a cellular receptor and cofactor for plasma coagulation factor VII/VIIa, contributes to thrombus formation. Investigation of how tissue factor activity is regulated on cell surfaces provides important information in understanding of thrombotic disease and also critical knowledge in improving efficacy of treatment of bleeding and thrombotic disorders.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL058869-10
Application #
7851246
Study Section
Hemostasis and Thrombosis Study Section (HT)
Program Officer
Link, Rebecca P
Project Start
2009-09-30
Project End
2012-08-31
Budget Start
2010-09-01
Budget End
2012-08-31
Support Year
10
Fiscal Year
2010
Total Cost
$421,199
Indirect Cost
Name
University of Texas Health Center at Tyler
Department
Type
Organized Research Units
DUNS #
800772337
City
Tyler
State
TX
Country
United States
Zip Code
75708
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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
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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
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Kothari, Hema; Rao, L Vijaya Mohan; Vankayalapati, Ramakrishna et al. (2012) Mycobacterium tuberculosis infection and tissue factor expression in macrophages. PLoS One 7:e45700
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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

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