Kinetic analysis of the interactions between plasminogen activator inhibitor 1 and both urokinase and tissue plasminogen activator

Hekman, Carla M.; Loskutoff, David J.

doi:10.1016/0003-9861(88)90182-8

Cited by 138 publications

(51 citation statements)

References 40 publications

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“…The preferential binding of t-PA to PAI-1, instead of binding to fibrin, is in accord with the kinetic parameters reported for these interactions with the separate components (52,53). (b) Upon formation of a stable complex with t-PA, PAI-1 apparently undergoes a conformational change and loses its affinity for fibrin.…”

Section: Resultssupporting

confidence: 85%

Interaction between plasminogen activator inhibitor type 1 (PAI-1) bound to fibrin and either tissue-type plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA). Binding of t-PA/PAI-1 complexes to fibrin mediated by both the finger and the kringle-2 domain of t-PA.

Wagner¹,

Vries²,

Hohmann³

et al. 1989

J. Clin. Invest.

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Plasminogen activation is catalyzed both by tissue-type-(t-PA) and by urokinase-type plasminogen activator (u-PA). This reaction is controlled by plasminogen activator inhibitor type 1 (PAI-1) that is either present in plasma or bound to fibrin, present in a thrombus. We studied the mechanism of in vitro inhibition of both t-PA and u-PA activity by PAI-1 bound to fibrin. It is shown that activation of latent PAI-1 unmasks a specific fibrin-binding site that is distinct from its reactive site. This reactive site of activated PAI-1 bound to fibrin is fully exposed to form complexes with t-PA and u-PA, that are unable to activate plasminogen. Upon complex formation with either one of the plasminogen activators, PAI-1 apparently undergoes a conformational change and loses its affinity for fibrin. Consequently, complexes of u-PA and PAI-1 dissociate from the fibrin matrix and are encountered in the fluid phase. In contrast, t-PA/PAI-1 complexes remain bound to fibrin. By employing recombinant t-PA deletion-mutant proteins, that precisely lack domains involved in fibrin binding, we demonstrate that binding of t-PA/PAI-1 complexes is mediated by both the "finger" (F) and the "kringle-2" (K2) domain of t-PA. A model is proposed that explains inhibition of the fibrinolytic process, at the level of plasminogen activation by t-PA, directed by PAI-1 bound to fibrin. An implication of the proposed model is that t-PA/PAI-1 complexes and free t-PA compete for the same binding sites on fibrin.

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Section: Resultssupporting

confidence: 85%

Interaction between plasminogen activator inhibitor type 1 (PAI-1) bound to fibrin and either tissue-type plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA). Binding of t-PA/PAI-1 complexes to fibrin mediated by both the finger and the kringle-2 domain of t-PA.

Wagner¹,

Vries²,

Hohmann³

et al. 1989

J. Clin. Invest.

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“…Type 1 plasminogen activator inhibitor (PAI-1)' is a rapid and specific inhibitor of both tissue-(t-PA) and urokinase-(u-PA) type plasminogen activators (1), and may be the primary regulator of plasminogen activation in vivo (2). Deficiencies in its activity lead to accelerated fibrinolysis and bleeding (3,4), while abnormally high levels are frequently observed in conditions where an increased risk of thrombosis exists.…”

Section: Introductionmentioning

confidence: 99%

Regulation of murine type 1 plasminogen activator inhibitor gene expression in vivo. Tissue specificity and induction by lipopolysaccharide, tumor necrosis factor-alpha, and transforming growth factor-beta.

Sawdey

Loskutoff²

1991

J. Clin. Invest.

395

270

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The regulation of type 1 plasminogen activator inhibitor (PAI-1) gene expression was studied in vivo employing a murine model system. Nuclease protection analysis revealed relatively high concentrations of PAT-i mRNA in the aorta, adipose tissue, heart, and lungs of untreated CB6 (BalbC X C57B16) mice. Treatment of CB6 mice with LPS, TNF-a, or transforming growth factor-,@ (TGF-ft) increased the steady-state levels of PAM-i mRNA within 3 h in all tissues examined. However, the greatest responses to TGF-ft were observed in adipose tissue and the kidney, while LPS and TNF-a strongly stimulated PAM-i gene expression in the liver, kidney, lung, and adrenals.

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“…Because rat uPAR does not bind human uPA (10), the results suggest that uPAR is not directly responsible for the observed vasoactivity, but they leave the identity of this other "uPA receptor" unresolved. Also uncertain is the effect of PAI-1, which binds to tcuPA with high affinity and neutralizes its proteolytic activity (11). The results of several studies indicate that PAI-1 is elevated in the plasma of patients with hypertension, and reduction of blood pressure by certain classes of anti-hypertensive agents is associated with a decrease in PAI-1 concentration (12)(13)(14)(15).…”

mentioning

confidence: 99%

Binding of Urokinase to Low Density Lipoprotein-related Receptor (LRP) Regulates Vascular Smooth Muscle Cell Contraction

Nassar¹,

Haj‐Yehia

Akkawi³

et al. 2002

Journal of Biological Chemistry

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Urokinase plasminogen activator (uPA) is a multifunctional protein that has been implicated in several physiological and pathological processes involving cell adhesion and migration in addition to fibrinolysis. In a previous study we found that two-chain urokinase plasminogen activator (tcuPA) stimulates phenylephrine-induced vasoconstriction of isolated rat aortic rings. In the present paper we report that uPA ؊/؊ mice have a significantly lower mean arterial blood pressure than do wild type mice and that aortic rings from uPA ؊/؊ mice show an attenuated contractile response to phenylephrine. In contrast, the blood pressure of urokinase receptor knockout (uPAR ؊/؊ ) mice and the response of their isolated aortic rings to phenylephrine were normal, indicating that the effect of uPA on vascular contraction is independent of uPAR. Addition of mouse and human uPA almost completely reversed both the impaired vascular contractility and the lower arterial blood pressure in vivo. The in vitro and in vivo effects of infused uPA on aortic contractility and the restoration of normal blood pressure in uPA ؊/؊ mice were prevented by antibody to low-density lipoprotein receptor-related protein/␣ 2 -macroglobulin receptor (LRP). A modified form of uPA that lacks the kringle failed to restore the blood pressure in uPA ؊/؊ mice, notwithstanding having a longer half-life in the circulation. Ligands that regulate the interaction of uPA with LRP, such as PAI-1 or the PAI-1-derived peptide (EEIIMD), abolished the vasoactivity of tcuPA in vitro and in vivo. These studies identify a novel signal transducing cellular receptor pathway involved in the regulation of vascular contractility.Urokinase plasminogen activator (uPA) 1 is a multifunctional protein that has been implicated in several physiological and pathological processes, including fibrinolysis. Transgenic mice with a targeted disruption in the uPA gene (uPA Ϫ/Ϫ ) are prone to form thrombi when exposed to endotoxin (1) or hypoxia (2, 3) or when the uPA gene is disrupted in otherwise healthy tPA Ϫ/Ϫ mice (1, 4). We recently reported that clearance of pulmonary microemboli in uPA Ϫ/Ϫ mice is delayed, despite the presence of an intact tPA system (5).uPA has also been implicated in other pathophysiological processes, such as pulmonary inflammation and repair, in which the relationship to fibrinolysis is less clear. For example, uPA Ϫ/Ϫ mice are more susceptible to lethal pulmonary infection (6) and to the development of pulmonary fibrosis (7), endpoints that might reflect contribution of uPA in cell adhesion (8) and migration to these phenotypes. However, the mechanism by which uPA is involved in these processes has not been established.In a previous study we found that uPA enhances phenylephrine and endothelin-induced vasoconstriction of aortic rings isolated from rats (9). The possibility that uPA contributes to the regulation of vascular tone may help to explain some of the phenotypic changes described in uPA Ϫ/Ϫ mice and perhaps provide a broader understanding of the role pl...

show abstract

Kinetic analysis of the interactions between plasminogen activator inhibitor 1 and both urokinase and tissue plasminogen activator

Cited by 138 publications

References 40 publications

Interaction between plasminogen activator inhibitor type 1 (PAI-1) bound to fibrin and either tissue-type plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA). Binding of t-PA/PAI-1 complexes to fibrin mediated by both the finger and the kringle-2 domain of t-PA.

Interaction between plasminogen activator inhibitor type 1 (PAI-1) bound to fibrin and either tissue-type plasminogen activator (t-PA) or urokinase-type plasminogen activator (u-PA). Binding of t-PA/PAI-1 complexes to fibrin mediated by both the finger and the kringle-2 domain of t-PA.

Regulation of murine type 1 plasminogen activator inhibitor gene expression in vivo. Tissue specificity and induction by lipopolysaccharide, tumor necrosis factor-alpha, and transforming growth factor-beta.

Binding of Urokinase to Low Density Lipoprotein-related Receptor (LRP) Regulates Vascular Smooth Muscle Cell Contraction

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