PAI-1 Plays an Important Role in the Expression of t-PA Activity in the Euglobulin Clot Lysis by Controlling the Concentration of Free t-PA

Urano, Tetsumei; Sumiyoshi, Kenichi; Pietraszek, M.H.; Takada, Yumiko; Takada, Akikazu

doi:10.1055/s-0038-1646441

Cited by 69 publications

(40 citation statements)

References 22 publications

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“…Also, the assay of fibrinolytic activity in the euglobulin fraction has been re ported to measure the t-PA activity, although the intrinsic fibrinolytic pathway is reported to be important [36].…”

Section: Discussionmentioning

confidence: 99%

Lipoprotein(a) Levels and Fibrinolytic Activity in Patients with Nephrotic Syndrome

Hong¹,

Yang²

1995

Nephron

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Recently there has been a renewed interest in the possibility that lipoprotein(a) -Lp(a) – may be important in the pathogenesis of thrombosis-related disease. In nephrotic syndrome, hyperlipidemia is a common finding, and thrombosis is a major complication. With this regard, if Lp(a) levels increase concomitantly with low-density lipoprotein and/or very-low-density lipoprotein levels in nephrotic syndrome, this may be considered a thrombogenic factor. To probe this possibility and to corroborate the relationship between Lp(a) and fibrinolytic profiles, we measured the Lp(a) levels in patients with nephrotic syndrome (n=43), in patients with chronic glomerulonephritis with less proteinuria than in nephrotic syndrome (n=28), and in healthy controls (n=50) and observed the relation between Lp(a) levels and tissue-type plasminogen activator (t-PA) activity, euglobulin fibrinolytic activity, and t-PA antigen. The Lp(a) levels were significantly higher in the patients with nephrotic syndrome as compared with both patients with chronic glomerulonephritis and healthy controls (p < 0.001). There was a direct correlation with serum cholesterol level (r=0.780; p = 0.0001), triglyceride level (r=0.445; p = 0.0001), and urine protein level (r = 0.675; p=0.0001) and a reverse correlation with serum albumin levels (r = 0.566; p = 0.0001). The Lp(a) levels showed a reverse correlation with t-pA activity (r = 0.627; p = 0.0001), total fibrinolytic activity in euglobulin fraction (r = 0.458; p = 0.0001), and t-PA activity divided by the t-PA antigen (r = 0.567; p = 0.0001), but no correlation with t-PA antigen. Our results suggest that Lp(a) may be an important thrombogenic factor in patients with nephrotic syndrome.

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Section: Discussionmentioning

confidence: 99%

Lipoprotein(a) Levels and Fibrinolytic Activity in Patients with Nephrotic Syndrome

Hong¹,

Yang²

1995

Nephron

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“…1 The expression of its activity is finely tuned by the amount of its specific inhibitor, plasminogen activator inhibitor-1 (PAI-1), 2,3 which is present in molar excess over tPA in human plasma. Thus, only a relatively small fraction of tPA circulates in blood in a functionally active form.…”

Section: Introductionmentioning

confidence: 99%

Unique secretory dynamics of tissue plasminogen activator and its modulation by plasminogen activator inhibitor-1 in vascular endothelial cells

Mogami

Ihara

Urano

2009

Blood

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We analyzed the secretory dynamics of tissue plasminogen activator (tPA) in EA.hy926 cells, an established vascular endothelial cell (VEC) line producing GFPtagged tPA, using total internal reflectionfluorescence (TIR-F) microscopy. tPA-GFP was detected in small granules in EA.hy926 cells, the distribution of which was indistinguishable from intrinsically expressed tPA. Its secretory dynamics were unique, with prolonged (> 5 minutes) retention of the tPA-GFP on the cell surface, appearing as fluorescent spots in two-thirds of the exocytosis events. The rapid disappearance (mostly by 250 ms) of a domain-deletion mutant of tPA-GFP possessing only the signal peptide and catalytic domain indicates that the amino-terminal heavy chain of tPA-GFP is essential for binding to the membrane surface. The addition of PAI-1 dosedependently facilitated the dissociation of membrane-retained tPA and increased the amounts of tPA-PAI-1 high-molecularweight complexes in the medium. Accordingly, suppression of PAI-1 synthesis in EA.hy926 cells by siRNA prolonged the dissociation of tPA-GFP, whereas a catalytically inactive mutant of tPA-GFP not forming complexes with PAI-1 remained on the membrane even after PAI-1 treatment. Our results provide new insights into the relationship between exocytosed, membrane-retained tPA and PAI-1, which would modulate cell surfaceassociated fibrinolytic potential. (Blood. 2009;113:470-478) IntroductionTissue plasminogen activator (tPA) is a 68-kDa serine protease that cleaves a single peptide bond in plasminogen to generate plasmin, which subsequently dissolves fibrin clots in the vasculature. 1 The expression of its activity is finely tuned by the amount of its specific inhibitor, plasminogen activator inhibitor-1 (PAI-1), 2,3 which is present in molar excess over tPA in human plasma. Thus, only a relatively small fraction of tPA circulates in blood in a functionally active form. Therefore, not only an elevation of plasma concentration of PAI-1 but an impairment of tPA release results in decreased fibrinolytic activity, which is regarded as a risk factor for ischemic cardiovascular events. [4][5][6] Although the enzymologic interactions of these 2 molecules in the fluid phase have been extensively studied, interactions at the interface between fluid-phase and solid-phase structures such as fibrin and the cell surface where functional fibrinolysis actually takes place are not fully elucidated. 7 In blood, tPA is secreted primarily from vascular endothelial cells (VECs) as an active single-chain enzyme, 8 in contrast to most other serine proteases involved in coagulation and fibrinolysis, which are secreted as zymogens. Facilitated secretion, therefore, is directly related to the enhancement of fibrinolytic activity, which protects the VEC surface from clot accumulation and maintains vascular patency. Clinically, impairment of acute tPA release is reported in atherosclerosis, hypertension, and cigarette smoking. 9-12 VECs secrete tPA through both constitutive and regulated pathways 13-17 from small s...

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“…In the case of adding genistein and biochanin A, it is believed that the protein bands with a larger molecular weight for tPA are a complex of tPA and its inhibiting factor PAI-1, and that this is an example of the effects of using plasma components such as euglobulin [21] . No previous tests have involved a type of sample without blood components of HeLa cells, so this is a completely new experiment in this regard.…”

Section: Discussionmentioning

confidence: 99%

Genistein and Its Analogue Enhanced Tissue Plasminogen Activator Activity in HeLa S3

Yatagai

Singu²,

Maruyama³

et al. 2007

Pathophysiol Haemos Thromb

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Soybean isoflavones of genistein and biochanin A, its analogue, promote the activity for generating tissue-plasminogen activator (tPA) from human cervical cancer cells (HeLa S3) and human umbilical vein endothelial cells (HUVEC). At a concentration of 50 µM, each of 14 types of isoflavones were added to HeLa culture solution and incubated. After 24 h, the culture solution was replaced, and then incubated for another 24 h. When fibrinolytic activity was checked in the resulting culture solution using the fibrin plate method, substantial fibrinolytic activity was confirmed for two types of isoflavones. Genistein showed the highest level of fibrinolytic activity at 12.4 times the control, and for biochanin A, an analogue of genistein, the level was 3.5 times the control. Checking fibrinolytic activity and molecular weight of the protein bands separated by zymography, a rise in the protein band concentration in proportion to the concentration of the reagents added was confirmed for the protein band with activity in the same position as the standard reference tPA, which has a molecular weight of about 68 kDa. ELISA also demonstrated that the concentration of tPA in the culture solution was higher than that of plasminogen activator-1. Fibrinolytic activity of HUVEC incubated with 25 µM of biochanin A was much higher than that of the control, which suggests that these soybean isoflavones could have beneficial effects on blood circulation in vivo.

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PAI-1 Plays an Important Role in the Expression of t-PA Activity in the Euglobulin Clot Lysis by Controlling the Concentration of Free t-PA

Cited by 69 publications

References 22 publications

Lipoprotein(a) Levels and Fibrinolytic Activity in Patients with Nephrotic Syndrome

Lipoprotein(a) Levels and Fibrinolytic Activity in Patients with Nephrotic Syndrome

Unique secretory dynamics of tissue plasminogen activator and its modulation by plasminogen activator inhibitor-1 in vascular endothelial cells

Genistein and Its Analogue Enhanced Tissue Plasminogen Activator Activity in HeLa S3

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