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Lipoprotein(a), fibrin binding, and plasminogen activation
J Loscalzo1, M Weinfeld, G M Fless
1Department of Medicine, Harvard Medical School, Brigham and Women's Hospital, Boston, Massachusetts 02115.
Arteriosclerosis (Dallas, Tex.)
|March 1, 1990
Summary
Lipoprotein(a) (Lp[a]) interferes with the body's clot-dissolving system. This lipoprotein binds to fibrin, inhibiting the breakdown of blood clots and impacting fibrinolysis.
Area of Science:
- Biochemistry
- Cardiovascular Biology
- Hematology
Background:
- Lipoprotein(a) (Lp[a]) is a complex plasma lipoprotein.
- Apolipoprotein (apo) B-100 is linked to apolipoprotein (apo)(a).
- Apo(a) shares homology with human plasminogen.
Purpose of the Study:
- To investigate the interaction of Lp(a) with the fibrinolytic system.
- To determine if Lp(a) affects tissue-type plasminogen activator (t-PA) activity.
- To elucidate the functional consequences of Lp(a)-fibrin binding.
Main Methods:
- Assessing Lp(a) binding to fibrin.
- Evaluating Lp(a)'s competition with plasminogen and t-PA for fibrin binding.
- Measuring the effect of Lp(a) on t-PA activity and clot lysis in plasma.
Main Results:
- Lp(a) binds to fibrin, similar to plasminogen.
- Lp(a) competes with plasminogen and t-PA for fibrin binding sites.
- Lp(a) inhibits fibrin-dependent t-PA activity (Ki = 15 nM) and attenuates clot lysis in plasma.
Conclusions:
- Lp(a) significantly influences the fibrinolytic system.
- The fibrin-binding properties of apo(a), specifically kringle repeats, mediate Lp(a)'s inhibitory effects.
- Lp(a) likely plays a role in regulating blood clot dissolution.