scholarly journals Relations between factor VIIa binding and expression of factor VIIa/tissue factor catalytic activity on cell surfaces.

1992 ◽  
Vol 267 (22) ◽  
pp. 15447-15454
Author(s):  
D.T. Le ◽  
S.I. Rapaport ◽  
L.V. Rao
Keyword(s):  
Catalytic Activity ◽  
Tissue Factor ◽  
Factor Viia ◽  
Cell Surfaces

scholarly journals Cellular localization and trafficking of tissue factor

Blood ◽  
2006 ◽  
Vol 107 (12) ◽  
pp. 4746-4753 ◽  
Author(s):  
Samir K. Mandal ◽  
Usha R. Pendurthi ◽  
L. Vijaya Mohan Rao
Keyword(s):  
Cell Surface ◽  
Tissue Factor ◽  
Cellular Localization ◽  
Factor Viia ◽  
Coagulation Cascade ◽  
Clotting Factor ◽  
Cell Surfaces ◽  
Caveolin 1 ◽  
Intracellular Compartments ◽  
Resultant Increase

AbstractTissue factor (TF) is the cellular receptor for clotting factor VIIa (FVIIa). The formation of TF-FVIIa complexes on cell surfaces triggers the activation of coagulation cascade and cell signaling. In the present study, we characterized the subcellular distribution of TF and its transport in fibroblasts by dual immunofluorescence confocal microscopy and biochemical methods. Our data show that a majority of TF resides in various intracellular compartments, predominantly in the Golgi. Tissue factor at the cell surface is localized in cholesterol-rich lipid rafts and extensively colocalized with caveolin-1. FVIIa binding to TF induces the internalization of TF. Of interest, we found that TF-FVIIa complex formation at the cell surface leads to TF mobilization from the Golgi with a resultant increase in TF expression at the cell surface. This process is dependent on FVIIa protease activity. Overall, the present data suggest a novel mechanism for TF expression at the cell surface by FVIIa. This mechanism could play an important role in hemostasis in response to vascular injury by increasing TF activity where and when it is needed.

scholarly journals Binding of factor VIIa to tissue factor permits rapid antithrombin III/heparin inhibition of factor VIIa

Blood ◽  
1993 ◽  
Vol 81 (10) ◽  
pp. 2600-2607 ◽  
Author(s):  
LV Rao ◽  
SI Rapaport ◽  
AD Hoang
Keyword(s):  
Catalytic Activity ◽  
Tissue Factor ◽  
Antithrombin Iii ◽  
Carcinoma Cell ◽  
Factor Viia ◽  
Surface Membrane ◽  
Factor X ◽  
Ovarian Carcinoma Cell Line ◽  
Coagulant Activity ◽  
At Iii

Abstract Because free factor VIIa is inactivated only very slowly by a plasma concentration of antithrombin III (AT III) even in the presence of heparin, it has been assumed that AT III plays no significant role in regulating the initiation of tissue factor-dependent blood coagulation. However, in the present study, we present evidence that factor VIIa bound to tissue factor, unlike free factor VIIa, is readily inactivated by AT III in the presence of heparin. In a reaction mixture containing calcium ions and approximately equimolar concentrations of relipidated tissue factor (8.9 nmol/L) and factor VIIa (10 nmol/L), AT III (100 micrograms/mL) plus heparin (1 U/mL) inhibited 50% of the factor VIIa coagulant activity of the reaction mixture within 5 minutes. AT III/heparin was also shown to inhibit the catalytic activity towards factor X of factor VIIa/tissue factor complexes formed on monolayers of an ovarian carcinoma cell line (OC-2008) that constitutively expresses surface membrane tissue factor. AT III, even in the absence of exogenously added heparin, substantially inhibited the functional activity of factor VIIa/cell surface tissue factor complexes on intact monolayers. AT III alone and AT III/heparin, to a greater extent, also inhibited factor VIIa on “nonfunctional” factor VIIa/tissue factor complexes on intact monolayers, with resultant inhibition of their expression of factor VIIa/tissue factor catalytic activity toward factor X after cell lysis. The potential physiologic significance of these findings is discussed.

scholarly journals The 99 and 170 Loop-modified Factor VIIa Mutants Show Enhanced Catalytic Activity without Tissue Factor

2002 ◽  
Vol 277 (50) ◽  
pp. 49027-49035 ◽  
Author(s):  
Kenji Soejima ◽  
Masato Yuguchi ◽  
Jun Mizuguchi ◽  
Kazuhiko Tomokiyo ◽  
Toshihiro Nakashima ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Tissue Factor ◽  
Factor Viia

scholarly journals Binding of factor VIIa to tissue factor permits rapid antithrombin III/heparin inhibition of factor VIIa

Blood ◽  
1993 ◽  
Vol 81 (10) ◽  
pp. 2600-2607
Author(s):  
LV Rao ◽  
SI Rapaport ◽  
AD Hoang
Keyword(s):  
Catalytic Activity ◽  
Tissue Factor ◽  
Antithrombin Iii ◽  
Carcinoma Cell ◽  
Factor Viia ◽  
Surface Membrane ◽  
Factor X ◽  
Ovarian Carcinoma Cell Line ◽  
Coagulant Activity ◽  
At Iii

Because free factor VIIa is inactivated only very slowly by a plasma concentration of antithrombin III (AT III) even in the presence of heparin, it has been assumed that AT III plays no significant role in regulating the initiation of tissue factor-dependent blood coagulation. However, in the present study, we present evidence that factor VIIa bound to tissue factor, unlike free factor VIIa, is readily inactivated by AT III in the presence of heparin. In a reaction mixture containing calcium ions and approximately equimolar concentrations of relipidated tissue factor (8.9 nmol/L) and factor VIIa (10 nmol/L), AT III (100 micrograms/mL) plus heparin (1 U/mL) inhibited 50% of the factor VIIa coagulant activity of the reaction mixture within 5 minutes. AT III/heparin was also shown to inhibit the catalytic activity towards factor X of factor VIIa/tissue factor complexes formed on monolayers of an ovarian carcinoma cell line (OC-2008) that constitutively expresses surface membrane tissue factor. AT III, even in the absence of exogenously added heparin, substantially inhibited the functional activity of factor VIIa/cell surface tissue factor complexes on intact monolayers. AT III alone and AT III/heparin, to a greater extent, also inhibited factor VIIa on “nonfunctional” factor VIIa/tissue factor complexes on intact monolayers, with resultant inhibition of their expression of factor VIIa/tissue factor catalytic activity toward factor X after cell lysis. The potential physiologic significance of these findings is discussed.

An Anti-Tissue Factor Monoclonal Antibody which Inhibits TF Vlla Complex Is a Potent Anticoagulant in Plasma

1991 ◽  
Vol 66 (05) ◽  
pp. 529-533 ◽  
Author(s):  
Wolfram Ruf ◽  
Thomas S Edgington
Keyword(s):  
Monoclonal Antibody ◽  
Cell Surface ◽  
Tissue Factor ◽  
Slow Rate ◽  
Factor Viia ◽  
Plasma Binding ◽  
Cell Surfaces ◽  
Therapeutic Principle ◽  
Catalytic Function

SummaryTissue factor (TF) functions as the receptor and cofactor for factor VIIa (VIIa) to form a proteolytically active TFVIIa complex on cell surfaces. We here demonstrate that most MAbs against human TF were poor inhibitors of TF function in plasma and that they inhibited preformed TF-VIIa complex at a slow rate which was dependent on dissociation of VIIa from the cell surface TF. An exception was defined by one MAb (TF8-5G9) which was an effective immediate anticoagulant in plasma. Binding of TF8-5G9 to TF-VIIa inhibited catalytic function prior to dissociation of the TF-VIIa complex. This analysis thus establishes two distinct mechanisms by which MAbs interfere with TF function. The MAb TF8-5G9 introduces a therapeutic principle for rapid arrest of inappropriate triggering of coagulation by TF as well as the TF-VIIa complex in vivo.

Mechanism of antithrombin III inhibition of factor VIIa/tissue factor activity on cell surfaces. Comparison with tissue factor pathway inhibitor/factor Xa-induced inhibition of factor VIIa/tissue factor activity

Blood ◽  
1995 ◽  
Vol 85 (1) ◽  
pp. 121-129 ◽  
Author(s):  
LV Rao ◽  
O Nordfang ◽  
AD Hoang ◽  
UR Pendurthi
Keyword(s):  
Cell Surface ◽  
Tissue Factor ◽  
Tissue Factor Pathway Inhibitor ◽  
Antithrombin Iii ◽  
Factor Viia ◽  
Factor Xa ◽  
Cell Surfaces ◽  
Tissue Factor Activity ◽  
At Iii ◽  
Tissue Factor Pathway

Recent studies have shown that antithrombin III (AT III)/heparin is capable of inhibiting the catalytic activity of factor VIIa bound either to relipidated tissue factor (TF) in suspension or to TF expressed on cell surfaces. We report studies of the mechanism of which by AT III inhibits factor VIIa bound to cell surface TF and compare this inhibitory mechanism with that of tissue factor pathway inhibitor (TFPI)-induced inhibition of factor VIIa/TF. AT III alone and AT III/heparin to a greater extent reduced factor VIIa bound to cell surface TF. Our data show that the decrease in the amount of factor VIIa associated with cell surface TF in the presence of AT III was the result of (1) accelerated dissociation of factor VIIa from cell surface TF after the binding of AT III to factor VIIa/TF complexes and (2) the inability of the resultant free factor VIIa-AT III complexes to bind effectively to a new cell surface TF site. Binding of TFPI/factor Xa to cell surface factor VIIa/TF complexes markedly decreased the dissociation of factor VIIa from the resultant quaternary complex of factor VIIa/TF/TFPI/factor Xa. Addition of high concentrations of factor VIIa could reverse the AT III-induced inhibition of cell surface factor VIIa/TF activity but not TFPI/factor Xa-induced inhibition of factor VIIa/TF activity.

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