Involvement of u-PA in the anti-apoptotic activity of TGFbeta for vascular smooth muscle cells.
Previous studies suggest a role for the plasminogen or fibrinolytic system in the activation of latent-transforming growth beta (L-TGFbeta) into active TGFbeta. In the present study, the anti-apoptotic activity of TGFbeta on cultured vascular smooth muscle cells (SMC) isolated from the aorta of transgenic mice with single inactivation of genes encoding the tissue-type plasminogen activator (t-PA(-/-)), urokinase-type plasminogen activator (u-PA(-/-)), urokinase receptor (u-PAR(-/-)) or plasminogen (Plg(-/-)) genes was examined. Latent-TGFbeta inhibited serum deprivation-induced apoptosis of SMC isolated from wild-type and t-PA(-/-) mice but failed to reduce apoptosis of SMC isolated from u-PA(-/-), u-PAR(-/-) or Plg(-/-) mice. Active TGFbeta, however, was able to inhibit serum deprivation-induced apoptosis of these 5 cell types, indicating that u-PA and/or plasmin were involved in the activation of L-TGFbeta. The anti-apoptotic effect of L-TGFbeta could not be evoked by addition of exogenous t-PA to u-PA(-/-) cells, but was revealed by addition of exogenous u-PA or plasmin. This effect was dependent on the catalytic activity of plasmin as revealed by the dose-dependent inhibition of aprotinin or epsilon aminocaproic acid (EACA). These results therefore indicate that, at least in vitro, u-PA-mediated plasmin, through the generation of active TGFbeta from L-TGFbeta, is required for the anti-apoptotic activity of TGFbeta on SMC.
Herbert
J M
JM
Haemobiology Research Department, Sanofi Recherche, Toulouse, France. jean-marc.herbert@tls1.elfsanofi.fr
Carmeliet
P
P
D000818:Animals; D001011:Aorta; D017209:Apoptosis / Q000187:drug effects*; D007611:Aprotinin / Q000494:pharmacology; D002478:Cells, Cultured; D005341:Fibrinolysin / Q000037:antagonists & inhibitors; D015971:Gene Expression Regulation, Enzymologic; D007700:Kinetics; D051379:Mice; D008822:Mice, Transgenic; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D010958:Plasminogen / Q000096:biosynthesis; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000096:biosynthesis; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000494:pharmacology* / Q000502:physiology; D014568:Urokinase-Type Plasminogen Activator / Q000096:biosynthesis / Q000378:metabolism*
D015842:Serine Proteinase Inhibitors; D016212:Transforming Growth Factor beta; D010958:Plasminogen; D007611:Aprotinin; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator