Fibrinogen binding potentiates FGF-2 but not VEGF induced expression of u-PA, u-PAR, and PAI-1 in endothelial cells.
Endothelial cell responses at sites of injury occur in a fibrin matrix and are regulated by growth factors including those of the FGF and VEGF families. The pericellular proteolytic balance is important in these responses, and FGF-2 and VEGF up-regulate endothelial cell u-PA, u-PAR and PAI-1. Because both VEGF and FGF-2 bind to fibrinogen, we have examined the capacity of fibrinogen to modulate the up-regulation of these proteins by FGF-2 and VEGF. Confluent cultures of endothelial cells were exposed to FGF-2, VEGF, and fibrinogen or to combinations of growth factors with fibrinogen. Changes in mRNA levels of u-PA, u-PAR and PAI-1 were measured by Northern blot. FGF-2 increased u-PA, u-PAR, and PAI-1 mRNA, but there was a significantly greater induction when fibrinogen was added to FGF-2 at all concentrations. The potentiation by fibrinogen was particularly evident at an FGF-2 concentration of 0.1 ng mL(-1), which resulted in non-significant change in transcript levels by itself, but significantly increased up to 2.6-fold with fibrinogen. VEGF also increased endothelial cell expression of u-PA, u-PAR and PAI-1, but this effect was not potentiated by fibrinogen. Addition of LM609, a monoclonal antibody to alphaVbeta3, significantly inhibited induction of u-PA mRNA and activity by fibrinogen-bound FGF-2 compared to FGF-2. A monoclonal antibody to FGFR1 also inhibited u-PA mRNA expression induced by fibrinogen-bound FGF-2. We conclude that fibrinogen increases the capacity of FGF-2, but not of VEGF, to up-regulate u-PA, u-PAR, and PAI-1 in endothelial cells and that fibrinogen-bound FGF-2 requires alphaVbeta3 binding to up-regulate endothelial cell u-PA.
Sahni
A
A
Department of Medicine, Hematology/Oncology Unit, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA. Abha_Sahni@urmc.rochester.edu
Sahni
S K
SK
Simpson-Haidaris
P J
PJ
Francis
C W
CW
D001483:Base Sequence; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000235:genetics; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism*; D005340:Fibrinogen / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics*; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics*; D055293:Receptors, Urokinase Plasminogen Activator; D011994:Recombinant Proteins / Q000494:pharmacology; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics*; D042461:Vascular Endothelial Growth Factor A / Q000494:pharmacology*
D018076:DNA, Complementary; C524898:PLAUR protein, human; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D011994:Recombinant Proteins; D042461:Vascular Endothelial Growth Factor A; D016222:Fibroblast Growth Factor 2; D005340:Fibrinogen; D014568:Urokinase-Type Plasminogen Activator