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Valle-Garay E, Montes AH, Corte JR, Meana A, Fierer J, Asensi V. tPA Alu (I/D) polymorphism associates with bacterial osteomyelitis. J Infect Dis 2013; 208:218-23. [PMID: 23570848 DOI: 10.1093/infdis/jit158] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Coagulation and fibrinolysis are important in infections and systemic inflammatory response syndrome. Polymorphisms in plasminogen activator inhibitor-1 (PAI-1, SERPINE1) and tissue plasminogen activator (tPA, PLAT), such as PAI-1 (-675 4G/5G deletion/insertion) and tPA (Alu insertion/deletion [I/D]), are associated with strokes, myocardial infarctions, bacterial infections and septic shock severity, and trauma. Osteomyelitis is a mostly posttraumatic, Staphylococcal bone infection. PATIENTS AND METHODS tPA Alu (I/D) (rs4646972) and PAI-1 (4G/5G) (rs1799889) polymorphisms were studied by DNA amplification with polymerase chain reaction in 261 patients with osteomyelitis and in 299 matched blood donors. Plasma PAI-1/tPA complex was assessed by enzyme-linked immuosorbent assay. RESULTS II homozygotes (37.9% vs 19.1%) and I allele carriers (56.3% vs 46.3%) for the tPA Alu (I/D) polymorphism were significantly more frequent in osteomyelitis patients compared to controls (P < .001). II genotype carrier osteomyelitis patients had lower PAI-1/tPA complex levels compared to those with the D allele (P ≤ .04). There was no association between these genotypes and chronicity of osteomyelitis, post-traumatic etiology, or with a specific bacterial etiology. PAI-1 (4G/4G) homozygotes were not significantly different between osteomyelitis patients and controls (P = .1). CONCLUSIONS We report for the first time to our knowledge an association between the tPA Alu (I/D) polymorphism and susceptibility to bacterial osteomyelitis, perhaps by fibrinolysis dysfunction.
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Affiliation(s)
- Eulalia Valle-Garay
- Biochemistry and Molecular Biology, Oviedo University School of Medicine and Hospital Universitario Central de Asturias, Oviedo, Spain
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Komissarov AA, Florova G, Idell S. Effects of extracellular DNA on plasminogen activation and fibrinolysis. J Biol Chem 2011; 286:41949-41962. [PMID: 21976662 DOI: 10.1074/jbc.m111.301218] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The increased levels of extracellular DNA found in a number of disorders involving dysregulation of the fibrinolytic system may affect interactions between fibrinolytic enzymes and inhibitors. Double-stranded (ds) DNA and oligonucleotides bind tissue-(tPA) and urokinase (uPA)-type plasminogen activators, plasmin, and plasminogen with submicromolar affinity. The binding of enzymes to DNA was detected by EMSA, steady-state, and stopped-flow fluorimetry. The interaction of dsDNA/oligonucleotides with tPA and uPA includes a fast bimolecular step, followed by two monomolecular steps, likely indicating slow conformational changes in the enzyme. DNA (0.1-5.0 μg/ml), but not RNA, potentiates the activation of Glu- and Lys-plasminogen by tPA and uPA by 480- and 70-fold and 10.7- and 17-fold, respectively, via a template mechanism similar to that known for fibrin. However, unlike fibrin, dsDNA/oligonucleotides moderately affect the reaction between plasmin and α(2)-antiplasmin and accelerate the inactivation of tPA and two chain uPA by plasminogen activator inhibitor-1 (PAI-1), which is potentiated by vitronectin. dsDNA (0.1-1.0 μg/ml) does not affect the rate of fibrinolysis by plasmin but increases by 4-5-fold the rate of fibrinolysis by Glu-plasminogen/plasminogen activator. The presence of α(2)-antiplasmin abolishes the potentiation of fibrinolysis by dsDNA. At higher concentrations (1.0-20 μg/ml), dsDNA competes for plasmin with fibrin and decreases the rate of fibrinolysis. dsDNA/oligonucleotides incorporated into a fibrin film also inhibit fibrinolysis. Thus, extracellular DNA at physiological concentrations may potentiate fibrinolysis by stimulating fibrin-independent plasminogen activation. Conversely, DNA could inhibit fibrinolysis by increasing the susceptibility of fibrinolytic enzymes to serpins.
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Affiliation(s)
- Andrey A Komissarov
- Texas Lung Injury Institute, University of Texas Health Science Center at Tyler, Tyler, Texas 75708-3154.
| | - Galina Florova
- Texas Lung Injury Institute, University of Texas Health Science Center at Tyler, Tyler, Texas 75708-3154
| | - Steven Idell
- Texas Lung Injury Institute, University of Texas Health Science Center at Tyler, Tyler, Texas 75708-3154
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Prognostic value of plasma fibrinolysis activation markers in cardiovascular disease. J Am Coll Cardiol 2010; 55:2701-9. [PMID: 20538163 DOI: 10.1016/j.jacc.2009.11.095] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 10/26/2009] [Accepted: 11/02/2009] [Indexed: 11/24/2022]
Abstract
The pivotal role of hypoactive endogenous fibrinolysis in the occurrence of thrombotic cardiovascular events is now well-recognized. To evaluate the diagnostic and prognostic role of impaired fibrinolysis, plasma fibrinolysis markers have been investigated in large prospective studies in both healthy individuals and patients with established coronary disease. Antigen and activity levels of components of the fibrinolytic system were measured by immunoassays, which replaced earlier global fibrinolysis tests. This review covers 45 studies in nearly 50,000 subjects, examining the association between plasma markers of fibrinolysis and coronary artery disease, to establish the usefulness of these markers in predicting future cardiovascular events. The predictive value of plasma levels of tissue-type plasminogen activator, platelet activator inhibitor-1, plasmin-antiplasmin complex, D-dimer, thrombin activatable fibrinolysis inhibitor, and lipoprotein(a) for major adverse cardiac events is highly variable and conflicting, especially after adjusting for conventional risk factors, judging from the published data in the last decade. The value of fibrinolysis activity markers is very limited in aiding diagnosis and risk stratification in the individual patient, on the basis of the weak prognostic values obtained in some studies and the lack of power in others. The physiological limitations of such markers in reflecting endogenous fibrinolysis is discussed. The emerging novel global assays of fibrinolysis will require large-scale clinical trials before their prognostic power or superiority to multiple biomarker measurements can be evaluated.
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Changes in plasma C-reactive protein and hemostatic factors prior to and after a first myocardial infarction with a median follow-up time of 8 years. Blood Coagul Fibrinolysis 2009; 20:340-6. [DOI: 10.1097/mbc.0b013e32832a5fd1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Dewilde M, Strelkov SV, Rabijns A, Declerck PJ. High quality structure of cleaved PAI-1-stab. J Struct Biol 2008; 165:126-32. [PMID: 19059484 DOI: 10.1016/j.jsb.2008.11.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Revised: 09/30/2008] [Accepted: 11/06/2008] [Indexed: 11/16/2022]
Abstract
Here we report the crystal structure of a stablilized plasminogen activator inhibitor-1 variant (PAI-1-N150H-K154T-Q301P-Q319L-M354I (PAI-1-stab)) that shows a cleavage within the reactive centre loop. The new structure is of superior quality compared to the previously determined structure of the cleaved PAI-1-A335P mutant. We present a detailed comparison of the two structures and also compare them with the structure of the active PAI-1-stab. The structural data give important insights into the working mechanism of PAI-1 and also explain the role of various stabilizing mutations.
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Affiliation(s)
- M Dewilde
- Katholieke Universiteit Leuven, Belgium
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Komissarov AA, Zhou A, Declerck PJ. Modulation of serpin reaction through stabilization of transient intermediate by ligands bound to alpha-helix F. J Biol Chem 2007; 282:26306-15. [PMID: 17613529 DOI: 10.1074/jbc.m702089200] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mechanism-based inhibition of proteinases by serpins involves enzyme acylation and fast insertion of the reactive center loop (RCL) into the central beta-sheet of the serpin, resulting in mechanical inactivation of the proteinase. We examined the effects of ligands specific to alpha-helix F (alphaHF) of plasminogen activator inhibitor-1 (PAI-1) on the stoichiometry of inhibition (SI) and limiting rate constant (k(lim)) of RCL insertion for reactions with beta-trypsin, tissue-type plasminogen activator (tPA), and urokinase. The somatomedin B domain of vitronectin (SMBD) did not affect SI for any proteinase or k(lim) for tPA but decreased the k(lim) for beta-trypsin. In contrast to SMBD, monoclonal antibodies MA-55F4C12 and MA-33H1F7, the epitopes of which are located at the opposite side of alphaHF, decreased k(lim) and increased SI for every enzyme. These effects were enhanced in the presence of SMBD. RCL insertion for beta-trypsin and tPA is limited by different subsequent steps of PAI-1 mechanism as follows: enzyme acylation and formation of a loop-displaced acyl complex (LDA), respectively. Stabilization of LDA through the disruption of the exosite interactions between PAI-1 and tPA induced an increase in the k(lim) but did not affect the SI. Thus it is unlikely that LDA contributes significantly to the outcome of the serpin reaction. These results demonstrate that the rate of RCL insertion is not necessarily correlated with SI and indicate that an intermediate, different from LDA, which forms during the late steps of PAI-1 mechanism, and could be stabilized by ligands specific to alphaHF, controls bifurcation between the inhibitory and the substrate pathways.
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Affiliation(s)
- Andrey A Komissarov
- Department of Chemistry, Portland State University, Portland, Oregon 97207-0751, USA.
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Abstract
As in other Western countries, cardiovascular disease (CVD) is the leading cause of death among women in Taiwan, exceeding the mortality from cervical or breast cancer. Women generally present with CVD after menopause and later than men, since menopause-related estrogen deficiency has been considered to be associated with an increased risk for CVD. Thus, coronary artery diseases and stroke are the two main contributors of mortality among postmenopausal women. Observational studies have reported a reduction in coronary artery disease risk after hormone therapy (HT) ranging from 31-44%. However, recent randomized controlled trials that evaluated the effect of HT on primary and secondary CVD prevention have questioned the efficacy of HT, despite confirming the lipid-lowering effect of estrogen. However, a cluster of factors are responsible for the genesis and progression of CVD. Until we further evaluate their specific actions and how these different factors interact, the issue related to HT and cardiovascular risk will remain unsettled. Since these studies have contributed to our understanding of the benefits and risks associated with HT, HT use should be individualized after consideration of the condition of each postmenopausal patient. Ideally, the efficacy of different preparations and dosages of HT in postmenopausal women who are at risk of CVD, before atheromatous lesions have developed, should be investigated.
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Affiliation(s)
- Fang-Ping Chen
- Department of Obstetrics and Gynecology, Keelung Chang Gung Memorial Hospital and Chang Gung University, Keelung, Taiwan.
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Teng LF, Chen FP, Lee N. Changes in Hemostasis and Lipid Metabolism in Postmenopausal Women Receiving Hormone Replacement Therapy: Effects of Natural and Synthetic Progestogens. Taiwan J Obstet Gynecol 2004. [DOI: 10.1016/s1028-4559(09)60061-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Verheyden S, Sillen A, Gils A, Declerck PJ, Engelborghs Y. Tryptophan properties in fluorescence and functional stability of plasminogen activator inhibitor 1. Biophys J 2003; 85:501-10. [PMID: 12829505 PMCID: PMC1303106 DOI: 10.1016/s0006-3495(03)74495-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2002] [Accepted: 03/13/2003] [Indexed: 11/18/2022] Open
Abstract
Plasminogen activator inhibitor 1 harbors four tryptophan residues at positions 86, 139, 175, and 262. To investigate the contribution of each tryptophan residue to the total fluorescence and to reveal the mutual interactions of the tryptophan residues and interactions with the other amino acids, 15 mutants in which tryptophan residues have been replaced by phenylalanines were constructed, purified, and characterized. Conformational distribution analysis revealed that the tryptophan mutants have a similar conformational distribution pattern as wild-type plasminogen activator inhibitor 1. Mutants in which tryptophan residue 175 was replaced by a phenylalanine displayed an increased functional half-life of the active conformation, whereas the functional half-life of mutants in which tryptophan residue 262 was replaced by a phenylalanine was substantially decreased. Comparative analysis of the fluorescence lifetimes, the extinction coefficients, and the quantum yields of the individual tryptophan residues demonstrates that tryptophan residue 262 gives the highest contribution to the total fluorescence. The other tryptophan residues have a very low quantum yield. In the wild-type protein, the fluorescence of all tryptophan residues is partially quenched as compared to the mutants that contain single tryptophan residues, due to conformational effects. The fluorescence of tryptophan residue 262 is very likely also partially quenched by energy transfer to tryptophan residue 175.
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Affiliation(s)
- Stefan Verheyden
- Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, B3001 Leuven, Belgium
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Li WY, Chong SSN, Huang EY, Tuan TL. Plasminogen activator/plasmin system: a major player in wound healing? Wound Repair Regen 2003; 11:239-47. [PMID: 12846910 DOI: 10.1046/j.1524-475x.2003.11402.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The role of the plasminogen activator/plasmin system in fibrinolysis has been well established. Indeed, clinicians worldwide have successfully utilized recombinant tissue-type plasminogen activator as first-line treatment of acute myocardial infarction for almost 2 decades. Outside the field of cardiology, there has been increasing excitement regarding the possible contribution of this system in many other important biological processes, including cell adhesion, cell migration, cell-cell signaling, tumor invasion and metastasis, ovulation, and wound healing. In this review, we present evidence in the current literature that the plasminogen activator/plasmin system does have a role in wound healing, looking at both normal and abnormal healing. Furthermore, the invaluable insights provided by numerous transgenic animal experiments are summarized.
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Affiliation(s)
- Wai-Yee Li
- Department of Surgery, Childrens Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, California 90027, USA
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Bijnens AP, Gils A, Stassen JM, Komissarov AA, Knockaert I, Brouwers E, Shore JD, Declerck PJ. The distal hinge of the reactive site loop and its proximity: a target to modulate plasminogen activator inhibitor-1 activity. J Biol Chem 2001; 276:44912-8. [PMID: 11559698 DOI: 10.1074/jbc.m103077200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serpin plasminogen activator inhibitor type 1 (PAI-1) plays a regulatory role in various physiological processes (e.g. fibrinolysis and pericellular proteolysis) and forms a potential target for therapeutic interventions. In this study we identified the epitopes of three PAI-1 inhibitory monoclonal antibodies (MA-44E4, MA-42A2F6, and MA-56A7C10). Differential cross-reactivities of these monoclonals with PAI-1 from different species and sequence alignments between these PAI-1s, combined with the three-dimensional structure, revealed several charged residues as possible candidates to contribute to the respective epitopes. The production, characterization, and subsequent evaluation of a variety of alanine mutants using surface plasmon resonance revealed that the residues His(185), Arg(186), and Arg(187) formed the major sites of interaction for MA-44E4. In contrast, the epitopes of MA-42A2F6 and MA-56A7C10 were found to be conformational. The epitope of MA-42A2F6 comprises residues Lys(243) and Glu(350), whereas the epitope of MA-56A7C10 comprises residues Glu(242), Lys(243), Glu(244), Glu(350), Asp(355), and Arg(356). The participation of Glu(350), Asp(355), and Arg(356) provides a molecular explanation for the differential exposure of this epitope in the different conformations of PAI-1 and for the effect of these antibodies on the kinetics of the formation of the initial PAI-1-proteinase complexes. The localization of the epitopes of MA-44E4, MA42A2F6, and MA-56A7C10 elucidates two previously unidentified molecular mechanisms to modulate PAI-1 activity and opens new perspectives for the rational development of PAI-1 neutralizing compounds.
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Affiliation(s)
- A P Bijnens
- Laboratory for Pharmaceutical Biology and Phytopharmacology, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, Belgium
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Chen FP, Lee N, Soong YK, Huang KE. Comparison of transdermal and oral estrogen-progestin replacement therapy: effects on cardiovascular risk factors. Menopause 2001; 8:347-52. [PMID: 11528361 DOI: 10.1097/00042192-200109000-00009] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To determine the effects of oral and transdermal hormone replacement therapy on lipid profile and hemostatic factors in postmenopausal women. DESIGN Twenty subjects were treated with oral E2 valerate (2 mg) combined with cyproterone acetate (1 mg) (group I) and 21 with transdermal E2 (1.5 mg) plus oral medroxyprogesterone acetate (5 mg) (group II). The effects on lipid profile and hemostatic parameters were evaluated at baseline and after 3, 6, and 12 months of treatment. RESULTS Group I showed a stronger increase of high-density lipoprotein (HDL) cholesterol levels (2-8%) and stronger reduction of atherogenic indices (total cholesterol/HDL cholesterol and low-density lipoprotein/HDL cholesterol) than group II. Group II showed a more pronounced reduction of triglyceride (21-31%) and factor VII (6-10%) levels than group I. Both groups showed reduced concentrations of total cholesterol, low-density lipoprotein cholesterol, tissue plasminogen activator, plasminogen activator inhibitor-1, antithrombin III, and protein S, whereas protein C was increased after 12 months of treatment. CONCLUSIONS The cardioprotective effects of hormone replacement therapy are demonstrated by favorable effects on lipid profile and fibrinolytic activity. Oral hormone replacement therapy showed a more prominent effect on lipoprotein metabolism than did transdermal administration, but transdermal medication had a stronger effect on triglyceride and coagulation factors. However, it needs to be considered that there is an increased risk of venous thrombotic events in the first year of treatment.
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Affiliation(s)
- F P Chen
- Department of Obstetrics and Gynecology, Keelung Chang Gung Memorial Hospital, Keelung, Taiwan, Republic of China
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Ngo TH, Hoylaerts MF, Knockaert I, Brouwers E, Declerck PJ. Identification of a target site in plasminogen activator inhibitor-1 that allows neutralization of its inhibitor properties concomitant with an allosteric up-regulation of its antiadhesive properties. J Biol Chem 2001; 276:26243-8. [PMID: 11342530 DOI: 10.1074/jbc.m008241200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The serpin plasminogen activator inhibitor-1 (PAI-1) has a dual function: 1) it plays an important role as a direct inhibitor of the plasminogen activation system, and 2) its interaction with the adhesive glycoprotein vitronectin suggests a role in tissue remodeling and metastasis, independent from its proteinase inhibitory properties. Unique to this serpin is the close association between its conformational and functional properties. Indeed, PAI-1 can occur in an active and a latent conformation, but both functions are exclusively present in the active conformation. We report here the epitope localization and functional effects of a monoclonal antibody (MA-124K1) that inhibits rat PAI-1 activity and simultaneously increases the binding of inactive PAI-1 to vitronectin (the affinity constant of PAI-1 for vitronectin is 2 x 10(7) m(-1) in the absence of MA-124K1 and 160 x 10(7) m(-1) in the presence of MA-124K1). To the best of our knowledge, this is the first monoclonal antibody dissociating the proteinase inhibitory properties from the vitronectin binding properties in PAI-1. Mutation of Glu(212) and/or Glu(220) in rat PAI-1 to Ala results in a strongly reduced affinity or absence of binding to MA-124K1. The three-dimensional structure of PAI-1 reveals that these residues constitute a conformational epitope close to the reactive-site loop and compatible with the effect of MA-124K1 on the inhibitory properties of PAI-1. However, the vitronectin binding site is localized at the opposite site of the molecule, indicating that the effect of MA-124K1 involves an allosteric modulation of the vitronectin binding site. Cell culture experiments revealed a significant reduction of cell attachment and migration in the presence of MA-124K1, providing evidence for the functional relevance of this antibody-mediated up-regulation of the vitronectin binding properties of PAI-1. In conclusion, a novel mechanism for interference with PAI-1 functions has been identified and is of importance in the modulation of cell migration and related events (e.g. tumor metastasis).
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Affiliation(s)
- T H Ngo
- Laboratory for Pharmaceutical Biology and Phytopharmacology, Faculty of Pharmaceutical Sciences, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium
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Lijnen HR, Arza B, Van Hoef B, Collen D, Declerck PJ. Inactivation of plasminogen activator inhibitor-1 by specific proteolysis with stromelysin-1 (MMP-3). J Biol Chem 2000; 275:37645-50. [PMID: 10967118 DOI: 10.1074/jbc.m006475200] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Matrix metalloproteinase-3 (MMP-3 or stromelysin-1) specifically hydrolyzes the Ser(337)-Ser(338) (P10-P9) and Val(341)-Ile(342) (P6-P5) peptide bonds in human plasminogen activator inhibitor-1 (PAI-1). Cleavage is completely abolished in the presence of the metal chelators EDTA or 1,10-phenanthroline. A stabilized active PAI-1 variant was also cleaved by MMP-3. At an enzyme/substrate ratio of 1/10 at 37 degrees C, PAI-1 protein cleavage occurred with half-lives of 27 or 14 min for active or stable PAI-1 and was associated with rapid loss of inhibitory activity toward tissue-type plasminogen activator with half-lives of 15 or 13 min, respectively. A substrate-like variant of PAI-1, lacking inhibitory activity but with exposed reactive site loop, was cleaved with a half-life of 23 min, whereas latent PAI-1 in which a major part of the reactive site loop is inserted into the molecule, was resistant to cleavage. Biospecific interaction analysis indicated comparable binding of active, stable, and substrate PAI-1 to both proMMP-3 and MMP-3 (K(A) of 12-22 x 10(6) m(-1)), whereas binding of latent PAI-1 occurred with lower affinity (1.7-2.3 x 10(6) m(-1)). Stable PAI-1 bound to vitronectin was cleaved and inactivated by MMP-3 in a manner comparable with that of free PAI-1; however, the cleaved protein did not bind to vitronectin. Cleavage and inactivation of PAI-1 by MMP-3 may thus constitute a mechanism decreasing the antiproteolytic activity of PAI-1 and impairing the potential inhibitory effect of vitronectin-bound PAI-1 on cell adhesion and/or migration.
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Affiliation(s)
- H R Lijnen
- Center for Molecular and Vascular Biology and Laboratory for Pharmaceutical Biology and Phytopharmacology, University of Leuven, B-3000 Leuven, Belgium.
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Abstract
Trans fatty acids are unsaturated fatty acids that contain at least one double bond in the trans configuration. In the diet they occur at relatively low levels in meat and dairy products as a by-product of fermentation in ruminant animals or in hydrogenated fats as a consequence of the hydrogenation process. In general, dietary hydrogenated fat/trans fatty acids have been reported to increase LDL cholesterol levels relative to oil in the natural state or cis fatty acids. In contrast, dietary hydrogenated fat/trans fatty acids have been reported have to have little effect or decrease HDL cholesterol levels, the later observation restricted to relatively high intakes of trans fatty acids. These two effects result in higher, therefore less favorable, total or LDL cholesterol/HDL cholesterol ratios. Significant increases in Lp(a) levels have been reported after consumption of diets relatively high in trans fatty acids compared with either unsaturated or saturated fatty acids. However, the magnitude of the change is for the most part small and the physiological significance of this observation has yet to be resolved. Data related to the mechanism by which hydrogenated fat/trans fatty acids alter serum lipid levels and other risk factors for cardiovascular disease are in the nascent stages. At this time it would appear prudent that public health recommendations should be aimed at encouraging the moderate consumption of products low in saturated fat or minimally hydrogenated. Trans fatty acids intake should not be stressed at the expense of saturated fat but should augment it.
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Affiliation(s)
- A H Lichtenstein
- Lipid Metabolism Laboratory, Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.
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