Binding of factor VIIa to tissue factor on human fibroblasts leads to activation of phospholipase C and enhanced PDGF-BB-stimulated chemotaxis.
Tissue factor (TF) is the cellular receptor for factor FVIIa (FVIIa), and the complex is the principal initiator of blood coagulation. The effects of FVIIa binding to TF on cell migration and signal transduction of human fibroblasts, which express high amounts of TF, were studied. Fibroblasts incubated with FVIIa migrated toward a concentration gradient of PDGF-BB at approximately 100 times lower concentration than do fibroblasts not ligated with FVIIa. Anti-TF antibodies inhibited the increase in chemotaxis induced by FVIIa/TF. Moreover, a pronounced suppression of chemotaxis induced by PDGF-BB was observed with active site-inhibited FVIIa (FFR-FVIIa). The possibility that hyperchemotaxis was induced by a putative generation of FXa and thrombin activity was excluded. FVIIa/TF did not induce increased levels of PDGF beta-receptors on the cell surface. Thus, the hyperchemotaxis was not a result of this mechanism. FVIIa induced the production of inositol-1,4, 5-trisphosphate to the same extent as PDGF-BB; the effects of FVIIa and PDGF-BB were additive. FFR-FVIIa did not induce any release of inositol-1,4,5,-trisphosphate. Thus, binding of catalytically active FVIIa to TF can, independent of coagulation, modulate cellular responses, such as chemotaxis.
Siegbahn
A
A
Department of Medical Sciences, Laboratory for Coagulation Research, Clinical Chemistry, University Hospital, Uppsala, Sweden. agneta.siegbahn@klinkem.uas.lul.se
Johnell
M
M
Rorsman
C
C
Ezban
M
M
Heldin
C H
CH
Rönnstrand
L
L
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000077214:Becaplermin; D001665:Binding Sites; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000187:drug effects; D004789:Enzyme Activation; D015942:Factor VIIa / Q000378:metabolism* / Q000494:pharmacology; D015951:Factor Xa / Q000494:pharmacology; D005347:Fibroblasts / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000187:drug effects / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D051966:Phospholipase C gamma; D010766:Phosphorylation / Q000187:drug effects; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011485:Protein Binding; D020574:Proto-Oncogene Proteins c-sis; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction; D013917:Thrombin / Q000494:pharmacology; D013925:Thromboplastin / Q000378:metabolism*; D010738:Type C Phospholipases / Q000187:drug effects / Q000378:metabolism*
D000590:Amino Acid Chloromethyl Ketones; D007527:Isoenzymes; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D015842:Serine Proteinase Inhibitors; D000077214:Becaplermin; C027587:phenylalanyl-phenylalanyl-arginine chloromethyl ketone; D013925:Thromboplastin; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D015942:Factor VIIa; D013917:Thrombin; D015951:Factor Xa