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Elements of the fibrinolytic system
1Center for Molecular and Vascular Biology, University of Leuven, Belgium. roger.lijnen@med.kuleuven.ac.be
Annals of the New York Academy of Sciences
|July 20, 2001
Summary
Matrix metalloproteinase-3 (MMP-3) can reduce cell-associated plasmin activity. It achieves this by cleaving plasminogen and urokinase (u-PA), thereby decreasing available plasminogen for activation.
Area of Science:
- Biochemistry
- Molecular Biology
- Proteolysis
Background:
- The fibrinolytic system regulates blood clot breakdown via plasminogen activation.
- Tissue-type plasminogen activator (t-PA) and urokinase-type plasminogen activator (u-PA) are key activators.
- Inhibitors like PAI and alpha 2-antiplasmin regulate fibrinolysis.
Purpose of the Study:
- To investigate the molecular interactions between the fibrinolytic and matrix metalloproteinase (MMP) systems.
- To elucidate the specific role of stromelysin-1 (MMP-3) in modulating plasminogen and u-PA activity.
Main Methods:
- Biochemical assays to study protein cleavage.
- Analysis of MMP-3 interactions with plasminogen and u-PA.
- Assessment of cell-associated plasmin activity.
Main Results:
- MMP-3 cleaves plasminogen, removing a fragment containing lysine binding sites.
- MMP-3 also cleaves u-PA, removing an N-terminal fragment involved in cellular binding.
- These actions by MMP-3 decrease the amount of activatable plasminogen, downregulating cell-associated plasmin activity.
Conclusions:
- MMP-3 negatively regulates cell-associated fibrinolytic activity.
- This interaction highlights a cooperative mechanism between MMPs and the fibrinolytic system.
- MMP-3's action may influence processes involving cell-associated plasmin, independent of cell-bound u-PA activity.