Urokinase and tissue-type plasminogen activator are required for the mitogenic and chemotactic effects of bovine fibroblast growth factor and platelet-derived growth factor-BB for vascular smooth muscle cells.
The present study was undertaken to evaluate in vitro the relative importance of tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA) in the mitogenic and chemotactic potential of bovine fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF)-BB for smooth muscle cells (SMC). Aortic SMC were isolated from transgenic mice showing single inactivations of the t-PA, u-PA, plasminogen activator inhibitor-1, or urokinase-type plasminogen activator receptor (u-PAR) genes. With regard to serum-induced proliferation, all cell types showed similar responses. However, SMC isolated from t-PA-deficient mice did not proliferate or migrate in response to PDGF, whereas SMC isolated from u-PA-deficient animals appeared to be much less sensitive to bFGF than the cells isolated from the other animals. Supplementation of cells from deficient animals with exogenous murine t-PA or u-PA restored the normal response of the growth factors with regard to both migration and proliferation. The mitogenic and chemotactic responses of bFGF were specifically inhibited in u-PAR-deficient cells or in wild-type SMC, cultured in the presence of antibodies to u-PAR. The role of u-PA and t-PA in bFGF and PDGF-induced growth and migration of SMC was not dependent on plasmin generation and activity as demonstrated by the inactivity of epsilon-aminocaproic acid and aprotinin. A 4-5-fold increase in the steady-state levels of u-PA and t-PA mRNA and proteins were observed after 24 h of incubation of the cell cultures with bFGF and PDGF-BB, respectively. These results therefore indicate that, at least in vitro, t-PA is an important element of the activity of PDGF-BB with regard to the proliferation and migration of SMC whereas u-PA is a key factor in the effect of bFGF on SMC.
Herbert
J M
JM
Haemobiology Research Department, Sanofi Recherche, 31036 Toulouse, France. jean-marc.herbert@tls1.elfsanofi.fr
Lamarche
I
I
Carmeliet
P
P
D000818:Animals; D000077214:Becaplermin; D002384:Catalysis; D002417:Cattle; D002478:Cells, Cultured; D002633:Chemotaxis / Q000502:physiology; D016222:Fibroblast Growth Factor 2 / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D008934:Mitogens / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D010982:Platelet-Derived Growth Factor / Q000502:physiology*; D020574:Proto-Oncogene Proteins c-sis; D010959:Tissue Plasminogen Activator / Q000502:physiology*; D014568:Urokinase-Type Plasminogen Activator / Q000502:physiology*
D008934:Mitogens; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D016222:Fibroblast Growth Factor 2; D000077214:Becaplermin; D010959:Tissue Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator