TF:FVIIa-specific activation of CREB upregulates proapoptotic proteins via protease-activated receptor-2.
BACKGROUND
Tissue factor (TF) and factor (F) VIIa are the primary initiators of the coagulation cascade, but also promote non-hemostatic events, such as angiogenesis and tumor growth, via activation of protease activated receptor-2 (PAR2). Our previous findings indicated that the TF:FVIIa complex activates signal transducer and activator of transcription (STAT) signaling, leading to cell survival in TF-transfected baby hamster kidney (BHK) cells.


METHODS
Using BHK TF, keratinocytes (HaCaT) and human umbilical vein endothelial cells (HUVEC), FVIIa-induced phosphorylation and activation of the transcription factor cyclic AMP-responsive binding protein (CREB) were tested and compared to that elicited by thrombin and FXa. In addition, the effect of these factors on cell survival and expression of apoptosis-associated proteins was monitored.


RESULTS
Factor VIIa led to a TF-dependent, but TF cytoplasmic domain-independent phosphorylation and activation of CREB in BHK TF, HaCaT and HUVEC. CREB activation was sensitive to blockade of the extracellular-signal regulated kinase 1/2 pathway and PAR2. Surprisingly, FVIIa decreased cell survival in HaCaT cells but not other cell types and upregulated the pro-apoptotic proteins Bak and Puma in a CREB-dependent manner. Factor Xa, but not FIIa, induced phosphorylation of CREB, but did not have an effect on apoptosis.


CONCLUSIONS
TF:FVIIa induces CREB phosphorylation and activation in several cell types, but TF:FVIIa induces pro-apoptotic proteins and apoptosis only in selected cell types.
Versteeg
H H
HH
Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands. h.h.versteeg@lumc.nl
Borensztajn
K S
KS
Kerver
M E
ME
Ruf
W
W
Reitsma
P H
PH
Spek
C A
CA
Peppelenbosch
M P
MP
D000818:Animals; D017209:Apoptosis; D015153:Blotting, Western; D002478:Cells, Cultured; D006224:Cricetinae; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D015942:Factor VIIa / Q000378:metabolism*; D015951:Factor Xa / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D044464:Receptor, PAR-2 / Q000378:metabolism*; D015398:Signal Transduction; D013917:Thrombin / Q000378:metabolism; D013925:Thromboplastin / Q000378:metabolism*; D015854:Up-Regulation
D017362:Cyclic AMP Response Element-Binding Protein; D044464:Receptor, PAR-2; D013925:Thromboplastin; D015942:Factor VIIa; D013917:Thrombin; D015951:Factor Xa; D019204:GTP-Binding Proteins