Regulation of gelatinase activity in mice with targeted inactivation of components of the plasminogen/plasmin system.
To investigate a potential physiological role of the plasminogen/plasmin system in activation of the matrix metalloproteinase (MMP) system, the distribution of latent and active MMP-2 (gelatinase A) or MMP-9 (gelatinase B) was monitored in aorta extracts and in serum-free conditioned cell culture medium obtained from wild-type (WT) mice and from mice with deficiency of tissue-type plasminogen activator (t-PA(-/-)), urokinase-type plasminogen activator (u-PA(-/-)), plasminogen activator inhibitor-1 (PAI-1(-/-)) or plasminogen (Plg(-/-)). In aorta extracts, the contribution of active MMP-2 to the total MMP-2 level ranged between 7 and 16% for the different genotypes, whereas active MMP-9 was not detected. The contribution of active 58 kDa MMP-2 to the total MMP-2 level (active plus latent) ranged between 14 and 29% (mean of 3 experiments) for fibroblasts of the different genotypes, and between 18 and 32% for smooth muscle cells, and was relatively constant in time (7-72 h). The contribution of active 83 kDa MMP-9 to the total MMP-9 level ranged between 15 and 29% for fibroblasts of the different genotypes and was relatively constant in time (24-72 h); corresponding values were 17 to 57% for smooth muscle cells, with the exception of Plg(-/-) smooth muscle cells which had undetectable levels of active MMP-9. Addition of plasmin(ogen) to the cell culture medium of fibroblasts did not significantly affect the distribution of active and latent MMP-2, but resulted in an approximately two-fold enhancement of the contribution of active MMP-9. In macrophages of Plg(-/-) mice, active MMP-9 was detected only when the cells were cultured in the presence of plasminogen. These data indicate that activation of proMMP-2 occurs independently of the physiological plasminogen activators and of plasmin(ogen) in all the cell types evaluated. Activation of proMMP-9 was enhanced in the presence of plasmin(ogen), but active MMP-9 was also detected in fibroblasts of Plg(-/-) mice, indicating that in vivo activation may occur via plasmin(ogen)-independent mechanisms.
Lijnen
H R
HR
Center for Molecular and Vascular Biology, University of Leuven, Belgium. roger.lijnen@med.kuleuven.ac.be
Silence
J
J
Lemmens
G
G
Frederix
L
L
Collen
D
D
D000818:Animals; D001011:Aorta / Q000166:cytology; D002478:Cells, Cultured; D017364:Collagenases / Q000378:metabolism*; D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D004622:Embryo, Mammalian / Q000166:cytology; D004789:Enzyme Activation; D004790:Enzyme Induction; D005260:Female; D005341:Fibrinolysin / Q000037:antagonists & inhibitors / Q000502:physiology*; D005347:Fibroblasts / Q000201:enzymology; D018093:Gelatinases / Q000378:metabolism*; D018390:Gene Targeting; D017737:Macrophages, Peritoneal / Q000201:enzymology; D008297:Male; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D008666:Metalloendopeptidases / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000201:enzymology; D010958:Plasminogen / Q000172:deficiency / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D017395:Plasminogen Activator Inhibitor 1 / Q000172:deficiency / Q000235:genetics; D012867:Skin / Q000166:cytology; D010959:Tissue Plasminogen Activator / Q000172:deficiency; D014568:Urokinase-Type Plasminogen Activator / Q000172:deficiency / Q000235:genetics
D017077:Culture Media, Conditioned; D016895:Culture Media, Serum-Free; D017395:Plasminogen Activator Inhibitor 1; D010958:Plasminogen; D010959:Tissue Plasminogen Activator; D005341:Fibrinolysin; D014568:Urokinase-Type Plasminogen Activator; D017364:Collagenases; D018093:Gelatinases; D008666:Metalloendopeptidases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9