Abstract
The putative role of tissue factor (TF) as a receptor involved in signal transduction is indicated by its sequence homology to cytokine receptors (Bazan, J. F. (1990) Proc. Natl. Acad. Sci. U. S. A. 87, 6934-6938). Signal transduction induced by binding of FVIIa to cells expressing TF was studied with baby hamster kidney (BHK) cells stably transfected with TF and with a reporter gene construct encoding a luciferase gene under transcriptional control of tandem cassettes of signal transducer and activator of transcription (STAT) elements and one serum response element (SRE). FVIIa induced a significant luciferase response in cells expressing TF, BHK(+TF), but not in cells without TF. The BHK(+TF) cells responded to the addition of FVIIa in a dose-dependent manner, whereas no response was observed with active site-inhibited FVIIa, which also worked as an antagonist to FVIIa-induced signaling. Activation of the p44/42 MAPK pathway upon binding of FVIIa to TF was demonstrated by suppression of signaling with the specific kinase inhibitor PD98059 and demonstration of a transient p44/42 MAPK phosphorylation. No stimulation of p44/42 MAPK phosphorylation was observed with catalytically inactive FVIIa derivatives suggesting that the catalytic activity of FVIIa was obligatory for activation of the MAPK pathway. Signal transduction caused by a putative generation of FXa activity was excluded by experiments showing that FVIIa/TF-induced signaling was not quenched by tick anticoagulant protein, just as addition of FXa could not induce phosphorylation of p44/42 MAPK in BHK(+TF) cells. These results suggest a specific mechanism by which binding of FVIIa to cell surface TF independent of coagulation can modulate cellular functions and possibly play a role in angiogenesis and tumor metastasis as indicated by several recent observations.
Original language | English |
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Journal | Journal of Biological Chemistry |
Volume | 273 |
Issue number | 11 |
Pages (from-to) | 6228-32 |
Number of pages | 5 |
ISSN | 0021-9258 |
Publication status | Published - 1998 |
Externally published | Yes |
Keywords
- Animals
- Calcium-Calmodulin-Dependent Protein Kinases
- Cells, Cultured
- Cricetinae
- Dogs
- Factor VII
- Factor VIIa
- Factor X
- Factor Xa
- Flavonoids
- Gene Expression Regulation
- Genes, Reporter
- Kidney
- Mitogen-Activated Protein Kinase 3
- Mitogen-Activated Protein Kinases
- Phosphorylation
- Protein Binding
- Recombinant Proteins
- Signal Transduction
- Thromboplastin