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Sandmark J, Tigerström A, Akerud T, Althage M, Antonsson T, Blaho S, Bodin C, Boström J, Chen Y, Dahlén A, Eriksson PO, Evertsson E, Fex T, Fjellström O, Gustafsson D, Herslöf M, Hicks R, Jarkvist E, Johansson C, Kalies I, Karlsson Svalstedt B, Kartberg F, Legnehed A, Martinsson S, Moberg A, Ridderström M, Rosengren B, Sabirsh A, Thelin A, Vinblad J, Wellner AU, Xu B, Östlund-Lindqvist AM, Knecht W. Identification and analyses of inhibitors targeting apolipoprotein(a) kringle domains KIV-7, KIV-10, and KV provide insight into kringle domain function. J Biol Chem 2020; 295:5136-5151. [PMID: 32132173 DOI: 10.1074/jbc.ra119.011251] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 02/17/2020] [Indexed: 11/06/2022] Open
Abstract
Increased plasma concentrations of lipoprotein(a) (Lp(a)) are associated with an increased risk for cardiovascular disease. Lp(a) is composed of apolipoprotein(a) (apo(a)) covalently bound to apolipoprotein B of low-density lipoprotein (LDL). Many of apo(a)'s potential pathological properties, such as inhibition of plasmin generation, have been attributed to its main structural domains, the kringles, and have been proposed to be mediated by their lysine-binding sites. However, available small-molecule inhibitors, such as lysine analogs, bind unselectively to kringle domains and are therefore unsuitable for functional characterization of specific kringle domains. Here, we discovered small molecules that specifically bind to the apo(a) kringle domains KIV-7, KIV-10, and KV. Chemical synthesis yielded compound AZ-05, which bound to KIV-10 with a Kd of 0.8 μm and exhibited more than 100-fold selectivity for KIV-10, compared with the other kringle domains tested, including plasminogen kringle 1. To better understand and further improve ligand selectivity, we determined the crystal structures of KIV-7, KIV-10, and KV in complex with small-molecule ligands at 1.6-2.1 Å resolutions. Furthermore, we used these small molecules as chemical probes to characterize the roles of the different apo(a) kringle domains in in vitro assays. These assays revealed the assembly of Lp(a) from apo(a) and LDL, as well as potential pathophysiological mechanisms of Lp(a), including (i) binding to fibrin, (ii) stimulation of smooth-muscle cell proliferation, and (iii) stimulation of LDL uptake into differentiated monocytes. Our results indicate that a small-molecule inhibitor targeting the lysine-binding site of KIV-10 can combat the pathophysiological effects of Lp(a).
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Affiliation(s)
- Jenny Sandmark
- Structure, Biophysics and Fragment-Based Lead Generation, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Anna Tigerström
- Precision Medicine BioPharmaceuticals, Precision Medicine, Oncology R&D, AstraZeneca, Gothenburg, Sweden
| | - Tomas Akerud
- Structure, Biophysics and Fragment-Based Lead Generation, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Magnus Althage
- Translational Science and Experimental Medicine, Early CVRM Biopharmaceutical R&D, AstraZeneca, Gothenburg, Sweden
| | - Thomas Antonsson
- Medicinal Chemistry, Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Stefan Blaho
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Cristian Bodin
- Structure, Biophysics and Fragment-Based Lead Generation, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Jonas Boström
- Medicinal Chemistry, Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Yantao Chen
- Medicinal Chemistry, Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Anders Dahlén
- Medicinal Chemistry, Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Per-Olof Eriksson
- Structure, Biophysics and Fragment-Based Lead Generation, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Emma Evertsson
- Medicinal Chemistry, Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Tomas Fex
- Medicinal Chemistry, Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Ola Fjellström
- Research and Early Development, Cardiovascular, Renal and Metabolism, Biopharmaceutical R&D, AstraZeneca, Gothenburg, Sweden
| | - David Gustafsson
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Margareta Herslöf
- Medicinal Chemistry, Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Ryan Hicks
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Emelie Jarkvist
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Carina Johansson
- Structure, Biophysics and Fragment-Based Lead Generation, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Inge Kalies
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Birgitta Karlsson Svalstedt
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Fredrik Kartberg
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Anne Legnehed
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Sofia Martinsson
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Andreas Moberg
- Structure, Biophysics and Fragment-Based Lead Generation, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Marianne Ridderström
- Drug Metabolism and Pharmacokinetics, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Birgitta Rosengren
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Alan Sabirsh
- Advanced Drug Delivery, Pharmaceutical Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Anders Thelin
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Johanna Vinblad
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Annika U Wellner
- Medicinal Chemistry, Cardiovascular, Renal and Metabolism, Biopharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Bingze Xu
- Discovery Biology, Discovery Sciences, R&D, AstraZeneca, Gothenburg, Sweden
| | - Ann-Margret Östlund-Lindqvist
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
| | - Wolfgang Knecht
- Bioscience Cardiovascular, Cardiovascular, Renal and Metabolism, BioPharmaceuticals R&D, AstraZeneca, Gothenburg, Sweden
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Månsson M, Kalies I, Bergström G, Schmidt C, Legnehed A, Hultén LM, Amrot-Fors L, Gustafsson D, Knecht W. Lp(a) is not associated with diabetes but affects fibrinolysis and clot structure ex vivo. Sci Rep 2014; 4:5318. [PMID: 24937703 PMCID: PMC4060502 DOI: 10.1038/srep05318] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 05/21/2014] [Indexed: 01/17/2023] Open
Abstract
Lipoprotein (a) [Lp(a)] is a low density lipoprotein (LDL) with one apolipoprotein (a) molecule bound to the apolipoprotein B-100 of LDL. Lp(a) is an independent risk factor for cardiovascular disease (CVD). However, the relationship of Lp(a) to diabetes and metabolic syndrome, both known for increased CVD risk, is controversial. In a population based study on type two diabetes mellitus (T2DM) development in women, Lp(a) plasma levels showed the well known skewed distribution without any relation to diabetes or impaired glucose tolerance. A modified clot lysis assay on a subset of 274 subjects showed significantly increased clot lysis times in T2DM subjects, despite inhibition of PAI-1 and TAFI. Lp(a) plasma levels significantly increased the maximal peak height of the clot lysis curve, indicating a change in clot structure. In this study Lp(a) is not related to the development of T2DM but may affect clot structure ex vivo without a prolongation of the clot lysis time.
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Affiliation(s)
| | - Inge Kalies
- AstraZeneca R&D Mölndal, 431 83 Mölndal, Sweden
| | - Göran Bergström
- Wallenberg Laboratory for Cardiovascular Research, Sahlgrenska Academy, University of Gothenburg, S-41345 Göteborg, Sweden
| | - Caroline Schmidt
- Wallenberg Laboratory for Cardiovascular Research, Sahlgrenska Academy, University of Gothenburg, S-41345 Göteborg, Sweden
| | | | - Lillemor Mattsson Hultén
- Wallenberg Laboratory for Cardiovascular Research, Sahlgrenska Academy, University of Gothenburg, S-41345 Göteborg, Sweden
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3
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Knapp JP, Herrmann W. In vitro inhibition of fibrinolysis by apolipoprotein(a) and lipoprotein(a) is size- and concentration-dependent. Clin Chem Lab Med 2005; 42:1013-9. [PMID: 15497466 DOI: 10.1515/cclm.2004.205] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Lipoprotein(a) (Lp(a)) is considered an independent risk factor for atherosclerotic heart and circulatory diseases. The unique, polymorphic character of Lp(a) is based on its apolipoprotein(a) (apo(a)), which has remarkable structural analogies with plasminogen, an important protein for fibrinolysis. The formation of plasmin from plasminogen is a fundamental step in the dissolution of fibrin. Repression of this step may lead to a deceleration of fibrinolysis. It has been suggested that Lp(a) has antifibrinolytic properties through apo(a) and that the apo(a)-size polymorphism has a distinct influence on the prothrombotic properties of Lp(a). However, the results on this topic are controversial. Therefore we used a standardized in vitro fibrinolysis model to provide further information on the influence of Lp(a) on plasmin formation. Monitoring the time-course of plasmin formation, we investigated the inhibition of plasmin formation through dependence on Lp(a), respectively, free apo(a) concentration. Furthermore, we investigated the influence of three Lp(a)/apo(a) phenotypes ((22K)Lp(a), 22 kringle-4 repeats; (30K)Lp(a), 30 kringle-4 repeats; (35K)Lp(a), 35 kringle-4 repeats). Adding varying amounts of Lp(a) to our model, we observed that the rate of plasmin formation was inversely related to the Lp(a) concentration. At 0.1 micromol/l (30K)Lp(a), for example, the plasmin formation was reduced by 12.7% and decreased further by 40.7% at 0.25 micromol/l Lp(a). A similar but more distinct effect was observed when free (30K)apo(a) was added to the model (25.3% at 0.1 micromol/l vs. 59.3% at 0.25 micromol/l). Comparing the antifibrinolytic influence of different apo(a) phenotypes we found that the reduction of plasmin generation advanced with the size of apo(a). At 0.1 micromol/l Lp(a) the reduction of the plasmin formation increased in the order (22K)Lp(a), (30K)Lp(a) and (35K)Lp(a) from 3.7% to 10.7% and 22.3%, respectively. Experiments with different phenotypes of free apo(a) showed similar results (0.5 micromol/l: (22K)apo(a), 56.4% vs. (30K)Lp(a), 80.4%). Summarizing these results, our study indicates a distinct interrelation of Lp(a)/apo(a) phenotype and concentration with the formation of plasmin. From the antifibrinolytic Lp(a)/apo(a) effect in vitro it may be hypothesized that Lp(a)/apo(a) also has an inhibitory influence on in vivo fibrinolysis.
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Affiliation(s)
- Jean-Pierre Knapp
- Department of Clinical Chemistry, Central Laboratory, Saarland Medical School, Homburg/Saar, Germany
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Abstract
Fibrinogen is a large, complex, fibrous glycoprotein with three pairs of polypeptide chains linked together by 29 disulfide bonds. It is 45 nm in length, with globular domains at each end and in the middle connected by alpha-helical coiled-coil rods. Both strongly and weakly bound calcium ions are important for maintenance of fibrinogen's structure and functions. The fibrinopeptides, which are in the central region, are cleaved by thrombin to convert soluble fibrinogen to insoluble fibrin polymer, via intermolecular interactions of the "knobs" exposed by fibrinopeptide removal with "holes" always exposed at the ends of the molecules. Fibrin monomers polymerize via these specific and tightly controlled binding interactions to make half-staggered oligomers that lengthen into protofibrils. The protofibrils aggregate laterally to make fibers, which then branch to yield a three-dimensional network-the fibrin clot-essential for hemostasis. X-ray crystallographic structures of portions of fibrinogen have provided some details on how these interactions occur. Finally, the transglutaminase, Factor XIIIa, covalently binds specific glutamine residues in one fibrin molecule to lysine residues in another via isopeptide bonds, stabilizing the clot against mechanical, chemical, and proteolytic insults. The gene regulation of fibrinogen synthesis and its assembly into multichain complexes proceed via a series of well-defined steps. Alternate splicing of two of the chains yields common variant molecular isoforms. The mechanical properties of clots, which can be quite variable, are essential to fibrin's functions in hemostasis and wound healing. The fibrinolytic system, with the zymogen plasminogen binding to fibrin together with tissue-type plasminogen activator to promote activation to the active enzyme plasmin, results in digestion of fibrin at specific lysine residues. Fibrin(ogen) also specifically binds a variety of other proteins, including fibronectin, albumin, thrombospondin, von Willebrand factor, fibulin, fibroblast growth factor-2, vascular endothelial growth factor, and interleukin-1. Studies of naturally occurring dysfibrinogenemias and variant molecules have increased our understanding of fibrinogen's functions. Fibrinogen binds to activated alphaIIbbeta3 integrin on the platelet surface, forming bridges responsible for platelet aggregation in hemostasis, and also has important adhesive and inflammatory functions through specific interactions with other cells. Fibrinogen-like domains originated early in evolution, and it is likely that their specific and tightly controlled intermolecular interactions are involved in other aspects of cellular function and developmental biology.
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Affiliation(s)
- John W Weisel
- Department of Cell and Developmental Biology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-6058, USA
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Caplice NM, Panetta C, Peterson TE, Kleppe LS, Mueske CS, Kostner GM, Broze GJ, Simari RD. Lipoprotein (a) binds and inactivates tissue factor pathway inhibitor: a novel link between lipoproteins and thrombosis. Blood 2001; 98:2980-7. [PMID: 11698280 DOI: 10.1182/blood.v98.10.2980] [Citation(s) in RCA: 136] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lipoprotein (a) [Lp(a)] has been associated with both anti-fibrinolytic and atherogenic effects. However, no direct link currently exists between this atherogenic lipoprotein and intravascular coagulation. The current study examined the binding and functional effects of Lp(a), its lipoprotein constituents, apoliprotein (a) [apo(a)] and low-density lipoprotein (LDL), and lysine-plasminogen (L-PLG), which shares significant homology with apo(a), on tissue factor pathway inhibitor (TFPI), a major regulator of tissue factor-mediated coagulation. Results indicate that Lp(a), apo(a), and PLG but not LDL bound recombinant TFPI (rTFPI) in vitro and that apo(a) bound to a region spanning the last 37 amino acid residues of the c-terminus of TFPI. The apparent binding affinity for TFPI was much higher for Lp(a) (KD approximately 150 nM) compared to PLG (KD approximately 800 nM) and nanomolar concentrations of apo(a) (500 nM) inhibited PLG binding to TFPI. Lp(a) also inhibited in a concentration-dependent manner rTFPI activity and endothelial cell surface TFPI activity in vitro, whereas PLG had no such effect. Moreover physiologic concentrations of PLG (2 microM) had no effect on the concentration-dependent inhibition of TFPI activity induced by Lp(a). In human atherosclerotic plaque, apo(a) and TFPI immunostaining were shown to coexist in smooth muscle cell-rich areas of the intima. These data suggest a novel mechanism whereby Lp(a) through its apo(a) moiety may promote thrombosis by binding and inactivating TFPI.
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Affiliation(s)
- N M Caplice
- Department of Internal Medicine and Cardiovascular Diseases, Mayo Clinic and Foundation, Rochester, MN 55905, USA.
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Higazi AAR, Cines DB, Bdeir K. α-Defensins. ATHEROSCLEROSIS AND AUTOIMMUNITY 2001:73-85. [DOI: 10.1016/b978-044450669-6/50009-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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7
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Sangrar W, Koschinsky ML. Characterization of the interaction of recombinant apolipoprotein(a) with modified fibrinogen surfaces and fibrin clots. Biochem Cell Biol 2000. [DOI: 10.1139/o00-065] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elevated levels of lipoprotein(a) [Lp(a)] in plasma are a significant risk factor for the development of atherosclerotic disease, a property which may arise from the ability of this lipoprotein to inhibit fibrinolysis. In the present study we have quantitated the binding of recombinant forms of apolipoprotein(a) [17K and 12K r-apo(a); containing 8 and 3 copies, respectively, of the major repeat kringle sequence (kringle IV type 2)] to modified fibrinogen surfaces. Iodinated 17K and 12K r-apo(a) bound to immobilized thrombin-modified fibrinogen (i.e., fibrin) surfaces with similar affinities (Kd~ 1.2 - 1.6 µM). The total concentration of binding sites (Bmax) present on the fibrin surface was ~4-fold greater for the 12K than for the 17K (Bmaxvalues of 0.81 ± 0.09 nM, and 0.20 ± 0.01 nM respectively), suggesting that the total binding capacity on fibrin surfaces is reduced for larger apolipoprotein(a) (apo(a)) species. Interestingly, binding of apo(a) to intact fibrin was not detected as assessed by measurement of intrinsic fluorescence of free apo(a) present in the supernatants of sedimented fibrin clots. In other experiments, the total concentration apo(a) binding sites available on plasmin-modified fibrinogen surfaces was shown to be 13.5-fold higher than the number of sites available on unmodified fibrin surfaces (Bmaxvalues of 2.7 ± 0.3 nM and 0.20 ± 0.01 nM respectively) while the affinity of apo(a) for these surfaces was similar. The increase in Bmaxwas correlated with plasmin-mediated exposure of C-terminal lysines since treatment of plasmin-modified fibrinogen surfaces with carboxypeptidase B produced a significant decrease in total binding signal as detected by ELISA (enzyme linked immunosorbent assay). Taken together, these data suggest that apo(a) binds to fibrin with poor affinity (low µM) and that the total concentration of apo(a) binding sites available on modified-fibrinogen surfaces is affected by both apo(a) isoform size and by the increased availability of C-terminal lysines on plasmin-degraded fibrinogen surfaces. However, the low affinity of apo(a) for fibrin indicates that Lp(a) may inhibit fibrinolysis through a mechanism distinct from binding to fibrin, such as binding to plasminogen.Key words: fibrinolysis, lipoprotein(a), plasminogen activation.
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Testa R, Marcovina SM. The rate of plasmin formation after in vitro clotting is inversely related to lipoprotein(a) plasma levels. INTERNATIONAL JOURNAL OF CLINICAL & LABORATORY RESEARCH 1999; 29:128-32. [PMID: 10592111 DOI: 10.1007/s005990050077] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Lipoprotein(a) levels are largely genetically determined and are linked to increased risk of coronary artery disease. The hypothesis that elevated lipoprotein(a) levels lead to decreased fibrinolysis, due to the close structural homology with plasminogen, could in part explain the genesis of this risk, although contrasting results have been obtained in different studies. The aim of our study was to evaluate whether the rate of plasmin formation, enhanced in vitro by a fixed amount of human tissue plasminogen activator after clotting, was related to plasma lipoprotein(a) levels in 45 healthy subjects. Aliquots of human plasma were clotted with calcium chloride and thrombin followed by addition of tissue plasminogen activator. We then measured the time course of plasmin formation, determined as hydrolysis of H-D-valyl-L-leucyl-L-lysine-p-nitroanilide dihydrocortide (S-2251). The log of lipoprotein(a) level was negatively related to the rate of plasmin formation (r(s)=-0.46, P=0. 002), and multiple regression analysis indicated that this relationship was not influenced by the amount of plasminogen, fibrinogen, plasminogen activator inhibitor-1, tissue plasminogen activator, or by the size of apo(a) isoforms. These data support the concept that lipoprotein(a) can inhibit plasminogen activation and plasmin formation and can thereby play an important role in the genesis of atherosclerosis as an antifibrinolytic agent.
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Affiliation(s)
- R Testa
- Istituto Nazionale di Riposo e Cura per Anziani V.E.II, Via S. Margherita, 5-60121 Ancona, Italy
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Canziani G, Zhang W, Cines D, Rux A, Willis S, Cohen G, Eisenberg R, Chaiken I. Exploring biomolecular recognition using optical biosensors. Methods 1999; 19:253-69. [PMID: 10527730 DOI: 10.1006/meth.1999.0855] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Understanding the basic forces that determine molecular recognition helps to elucidate mechanisms of biological processes and facilitates discovery of innovative biotechnological methods and materials for therapeutics, diagnostics, and separation science. The ability to measure interaction properties of biological macromolecules quantitatively across a wide range of affinity, size, and purity is a growing need of studies aimed at characterizing biomolecular interactions and the structural elements that drive them. Optical biosensors have provided an increasingly impactful technology for such biomolecular interaction analyses. These biosensors record the binding and dissociation of macromolecules in real time by transducing the accumulation of mass of an analyte molecule at the sensor surface coated with ligand molecule into an optical signal. Interactions of analytes and ligands can be analyzed at a microscale and without the need to label either interactant. Sensors enable the detection of bimolecular interaction as well as multimolecular assembly. Most notably, the method is quantitative and kinetic, enabling determination of both steady-state and dynamic parameters of interaction. This article describes the basic methodology of optical biosensors and presents several examples of its use to investigate such biomolecular systems as cytokine growth factor-receptor recognition, coagulation factor assembly, and virus-cell docking.
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Affiliation(s)
- G Canziani
- Department of Medicine, School of Medicine, University of Pennsylvania, Philadelphia 19104, USA
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10
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Abstract
AbstractTissue factor (TF) has been implicated in several important biologic processes, including fibrin formation, atherogenesis, angiogenesis, and tumor cell migration. In that plasminogen activators have been implicated in the same processes, the potential for interactions between TF and the plasminogen activator system was examined. Plasminogen was found to bind directly to the extracellular domain of TF apoprotein (amino acids 1-219) as determined by optical biosensor interaction analysis. A fragment of plasminogen containing kringles 1 through 3 also bound to TF apoprotein, whereas isolated kringle 4 and miniplasminogen did not. Expression of TF on the surface of a stably transfected Chinese hamster ovary (CHO) cell line stimulated plasminogen binding to the cells by 70% more than to control cells. Plasminogen bound to a site on the TF apoprotein that appears to be distinct from the binding site for factors VII and VIIa as judged by a combination of biosensor and cell assays. TF enhanced two-chain urokinase (tcuPA) activation of Glu-plasminogen, but not of miniplasminogen, in a dose-dependent, saturable manner (half maximal stimulation at 59 pmol/L). TF apoprotein induced an effect similar to that of relipidated TF, but a relatively higher concentration of the apoprotein was required (half maximal stimulation at 3.8 nmol/L). The stimulatory effect of TF on plasminogen activation was confirmed when plasmin formation was examined directly on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In accord with this, TF inhibited fibrinolysis by approximately 74% at a concentration of 14 nmol/L and almost totally inhibited the binding of equimolar concentrations of plasminogen to human umbilical vein endothelial cells and human trophoblasts. Further, CHO cells expressing TF inhibited uPA-mediated fibrinolysis relative to a wild-type control. TF apoprotein and plasminogen were found to colocalize in atherosclerotic plaque. These data suggest that plasminogen localization and activation may be modulated at extravascular sites through a high-affinity interaction between kringles 1 through 3 of plasminogen and the extracellular domain of TF.
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11
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Tissue Factor Regulates Plasminogen Binding and Activation. Blood 1998. [DOI: 10.1182/blood.v91.6.1987.1987_1987_1998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Tissue factor (TF) has been implicated in several important biologic processes, including fibrin formation, atherogenesis, angiogenesis, and tumor cell migration. In that plasminogen activators have been implicated in the same processes, the potential for interactions between TF and the plasminogen activator system was examined. Plasminogen was found to bind directly to the extracellular domain of TF apoprotein (amino acids 1-219) as determined by optical biosensor interaction analysis. A fragment of plasminogen containing kringles 1 through 3 also bound to TF apoprotein, whereas isolated kringle 4 and miniplasminogen did not. Expression of TF on the surface of a stably transfected Chinese hamster ovary (CHO) cell line stimulated plasminogen binding to the cells by 70% more than to control cells. Plasminogen bound to a site on the TF apoprotein that appears to be distinct from the binding site for factors VII and VIIa as judged by a combination of biosensor and cell assays. TF enhanced two-chain urokinase (tcuPA) activation of Glu-plasminogen, but not of miniplasminogen, in a dose-dependent, saturable manner (half maximal stimulation at 59 pmol/L). TF apoprotein induced an effect similar to that of relipidated TF, but a relatively higher concentration of the apoprotein was required (half maximal stimulation at 3.8 nmol/L). The stimulatory effect of TF on plasminogen activation was confirmed when plasmin formation was examined directly on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In accord with this, TF inhibited fibrinolysis by approximately 74% at a concentration of 14 nmol/L and almost totally inhibited the binding of equimolar concentrations of plasminogen to human umbilical vein endothelial cells and human trophoblasts. Further, CHO cells expressing TF inhibited uPA-mediated fibrinolysis relative to a wild-type control. TF apoprotein and plasminogen were found to colocalize in atherosclerotic plaque. These data suggest that plasminogen localization and activation may be modulated at extravascular sites through a high-affinity interaction between kringles 1 through 3 of plasminogen and the extracellular domain of TF.
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Papagrigorakis E, Iliopoulos D, Asimacopoulos PJ, Safi HJ, Weilbaecher DJ, Ghazzaly KG, Nava ML, Gaubatz JW, Morrisett JD. Lipoprotein(a) in plasma, arterial wall, and thrombus from patients with aortic aneurysm. Clin Genet 1997; 52:262-71. [PMID: 9520116 DOI: 10.1111/j.1399-0004.1997.tb04343.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The plasma concentration of lipoprotein(a) [Lp(a)] is highly correlated with the incidence of cardiovascular and peripheral vascular disease. A positive physiological role for Lp(a) has not yet been clearly identified, although elevated plasma levels in pregnant women, long-distance runners, subjects given growth hormone, patients after cardiovascular surgery, and patients with cancer, diabetes, or renal disease suggest its involvement in tissue synthesis and repair. The hypothesis that Lp(a) is involved in repair/reinforcement of the aorta was tested in 38 patients undergoing surgery for aortic aneurysm. In 29 patients 1 day before surgery, the mean plasma Lp(a) protein level was 10.7 mg/dl. At about 1, 2, and 8 weeks after surgery, the level was 14.1, 15.1, and 15.2 mg/dl, respectively. These levels are significantly higher than those of a comparable group of normal subjects (6.4 mg/dl; n = 274). Specimens of resected aortic aneurysm showed extensive medial degeneration, discontinuous elastic fibers, and deposition of mucopolysaccharides; these specimens were treated with a detergent-containing buffer to extract entrapped lipoproteins. The mean Lp(a) protein level in aortic wall extracts was 14.6 ng/mg tissue; these individual values were significantly associated with plasma Lp(a) levels before surgery (r2 = 0.31, p = 0.0003). The mean Lp(a) protein level in aortic thrombus extracts was substantially higher at 69.6 ng/mg tissue; these individual levels also were significantly associated with plasma Lp(a) concentrations before surgery (r2 = 0.68, p < 0.0001). The observations that: (i) plasma Lp(a) protein is about 1.7-fold higher in patients with aortic aneurysms than in normal subjects; and (ii) that Lp(a) protein in the aneurysmic thrombus is about 4.8-fold higher than in the aortic wall suggest that this lipoprotein plays a significant and direct role in thrombus formation and in reinforcement of the aneurysmic aortic wall.
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Affiliation(s)
- E Papagrigorakis
- Department of Medicine, The Methodist Hospital and Baylor College of Medicine, Houston, Texas 77030, USA
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13
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Defensin Stimulates the Binding of Lipoprotein (a) to Human Vascular Endothelial and Smooth Muscle Cells. Blood 1997. [DOI: 10.1182/blood.v89.12.4290] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractThere is evidence to suggest that elevated plasma levels of lipoprotein (a) [Lp(a)] represent a risk factor for the development of atherosclerotic vascular disease, but the mechanism by which this lipoprotein localizes to involved vessels is only partially understood. In view of studies suggesting a link between inflammation and atherosclerosis and our previous finding that leukocyte defensin modulates the interaction of plasminogen and tissue-type plasminogen activator with cultured human endothelial cells, we examined the effect of this peptide on the binding of Lp(a) to cultured vascular endothelium and vascular smooth muscle cells. Defensin increased the binding of Lp(a) to endothelial cells approximately fourfold and to smooth muscle cells approximately sixfold. Defensin caused a comparable increase in the amount of Lp(a) internalized by each cell type, but Lp(a) internalized as a consequence of defensin being present was not degraded, resulting in a marked increase in the total amount of cell-associated lipoprotein. Abundant defensin was found in endothelium and in intimal smooth muscle cells of atherosclerotic human cerebral arteries, regions also invested with Lp(a). These studies suggest that defensin released from activated or senescent neutrophils may contribute to the localization and persistence of Lp(a) in human vessels and thereby predispose to the development of atherosclerosis.
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14
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Higazi AA, Ganz T, Kariko K, Cines DB. Defensin modulates tissue-type plasminogen activator and plasminogen binding to fibrin and endothelial cells. J Biol Chem 1996; 271:17650-5. [PMID: 8663495 DOI: 10.1074/jbc.271.30.17650] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Defensins are naturally occurring antimicrobial peptides that may participate in host defense against microorganisms. We previously reported that the amino acid sequence of leukocyte defensins resembles the lysine-binding site in the kringles of plasminogen and that defensin inhibits fibrinolysis mediated by tissue-type plasminogen activator (tPA) and plasminogen. In the present paper we analyze the mechanisms of this inhibition. Defensin binds specifically to cultured human umbilical vein endothelial cells (HUVEC) (half-maximal binding = 3 microM) as well as to fibrin. At saturating concentrations (5-10 microM), defensin stimulates the maximum binding of plasminogen to HUVEC and to fibrin approximately 10-fold. However, defensin inhibits plasminogen binding to both surfaces at concentrations >10 microM. Defensin also inhibits tPA and plasminogen-mediated fibrinolysis in a dose-dependent manner at all concentrations tested. Fibrinolysis is almost totally inhibited by 6 microM defensin, a concentration that stimulates the binding of plasminogen to fibrin. Discordance between the enhancement of plasminogen binding and its activation cannot be explained by an inhibitory effect of defensin on tPA binding nor by inhibition of plasmin activity, each of which occur only at higher concentrations. Rather, these results suggest that plasminogen bound to fibrin in the presence of defensin is less susceptible to activation by tPA.
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Affiliation(s)
- A A Higazi
- Department of Pathology, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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15
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Li XN, Koons JC, Benza RL, Parks JM, Varma VK, Bradley WA, Gianturco SH, Taylor KB, Grammer JR, Tabengwa EM, Booyse FM. Hypertriglyceridemic VLDL decreases plasminogen binding to endothelial cells and surface-localized fibrinolysis. Biochemistry 1996; 35:6080-8. [PMID: 8634250 DOI: 10.1021/bi952032i] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The effect of normo (NTG)- and hypertriglyceridemic (HTG)-VLDL on cultured human umbilical vein endothelial cell (HUVEC) surface-localized fibrinolysis was examined following pre-incubation with NTG-, HTG-VLDL, LDL (1-20 micrograms/mL) or buffer (control). Ligand binding assays, using 125I-labeled tcu-PA, t-PA, or Glu-plasminogen (Glu-Pmg) were carried out in the absence/presence of lipoproteins. Scatchard analyses showed that HTG-VLDL decreased the Bmax for 125I-labeled Glu-Pmg ligand binding approximately 35% [(2.11 +/- 0.39)-(1.40 +/- 0.32) x 10(6) sites/cell, p < 0.005] and increased the Kd, app approximately 5-fold (0.32 +/- 0.03 to 1.74 +/- 0.08 microM, p < 0.01), while NTG-VLDL, LDL, and buffer had no effect. 125I-labeled PA ligand binding was unaffected by these lipoproteins. Receptor-bound PA activation of cell-bound 125I-labeled Glu-Pmg was measured by quantitation of either the M(r) 20 kDa light- or M(r) 60 kDa heavy-chain of 125I-labeled plasmin, following SDS-PAGE. Kinetic analysis of these data (HTG-VLDL vs controls) indicated that HTG-VLDL decreased the V(max) of tcu-PA- and t-PA-mediated activation of plasminogen approximately 2.7-fold (0.317 +/- 0.023 vs 0.869 +/- 0.068 nM s-1, p < 0.01) and approximately 2.9-fold (0.391 +/- 0.098 vs 1.152 +/- 0.265 nM s-1, p < 0.01), respectively. Increasing concentrations of the HTG-VLDL increased 1/V(max), yielding a series of parallel plots, typical for uncompetitive inhibition with a Ki for inhibition of approximately 10 micrograms/mL. The combined ligand binding and kinetic data best fit an uncompetitive inhibition model in which the binding of the large HTG-VLDL particle to the EC surface may directly affect Glu-Pmg binding and activation, thus contributing to early fibrin deposition and the increased thrombotic risk associated with HTG.
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Affiliation(s)
- X N Li
- Department of Medicine, University of Alabama at Birmingham 35294-2170, USA
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16
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van den Ende A, van der Hoek YY, Kastelein JJ, Koschinsky ML, Labeur C, Rosseneu M. Lipoprotein [a]. Adv Clin Chem 1996; 32:73-134. [PMID: 8899071 DOI: 10.1016/s0065-2423(08)60426-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- A van den Ende
- Center for Vascular Medicine, Academic Medical Center of the University of Amsterdam, The Netherlands
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17
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Mantzoros CS, Evagelopoulou K, Moses AC. Outcome of percutaneous transluminal coronary angioplasty in patients with subclinical hypothyroidism. Thyroid 1995; 5:383-7. [PMID: 8563477 DOI: 10.1089/thy.1995.5.383] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
To determine the outcomes of percutaneous transluminal angioplasty (PTCA) in patients with subclinical hypothyroidism and to compare them with those in euthyroid patients, we studied retrospectively 48 hypothyroid (4 overtly and 44 subclinically hypothyroid) and 122 euthyroid patients who had a PTCA in Boston's Beth Israel Hospital between 1984 and 1994. No significant differences were detected in bradycardia (relative risk, RR: 0.96), tachyarrhythmia (RR: 0.62), heart failure (RR: 2.27), hypotension (RR: 1.95), or bleeding (RR: 2.48) in the immediate postprocedure period between euthyroid and subclinically hypothyroid patients. There was a trend towards an increased incidence of chest pain (43.2 vs 27.5%, RR: 1.57, p = 0.084), dissection (50 vs 33%, RR: 1.51, p = 0.06) as an immediate, and reocclusion as an early (within 2 weeks) postprocedure complication (6.25 vs .9%, RR: 6.81, p = 0.08). However, chest pain accompanied by electrocardiographic changes was not significantly different between the two groups (20.5 vs 14.7%, RR: 1.4, p = 0.47). There was no difference in the number of procedures rated as successful (subclinically hypothyroid vs euthyroid: 90.2 vs 92.7%). Hospital charges, discharge destination, interval to next admission to the hospital, and in-hospital mortality were not different between the two groups. Subclinical hypothyroidism does not appear to be a risk factor for significant morbidity or increased mortality following PTCA. Prospective long-term studies with increased statistical power are needed to clarify whether there is an association between hypothyroidism and complications (especially chest pain, dissection, and/or reocclussion) in the early (2 weeks) and late (6 months) post-PTCA period.
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Affiliation(s)
- C S Mantzoros
- Division of Endocrinology, Charles A. Dana Research Institute, Boston, Massachusetts 02215, USA
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18
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Stegnar M, Ambrožič J, Berger B, Keber I. In vitro plasma and euglobulin clot lysis in subjects with elevated lipoprotein(a). ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s0268-9499(95)80020-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Császár A, Karádi I, Juhász E, Romics L. High lipoprotein(a) levels with predominance of high molecular weight apo(a) isoforms in patients with pulmonary embolism. Eur J Clin Invest 1995; 25:368-70. [PMID: 7628525 DOI: 10.1111/j.1365-2362.1995.tb01715.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Lipoprotein(a) (Lp(a)) may interact with the cellular components and protein co-factors of fibrinolysis. To evaluate the effect of Lp(a) in thromboembolic diseases of the venous system, we measured serum levels and the isoform distribution of apo(a) in 25 patients with pulmonary embolism (18 men, 7 women, aged 21-77 years). The control group was adjusted for sex and age (P = 0.189). Serum Lp(a) concentration was significantly higher in the study group (median: 9.3 vs. 4.3 mg dL-1). As the distribution of high and low molecular weight subtypes of apo(a) did not show any differences (P = 0.127) between the two groups, the elevated Lp(a) levels in patients with pulmonary embolism could not be attributed to the investigated kringle-4 polymorphism of the apo(a) gene and therefore other genetic or non-genetic implications are indicated.
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Affiliation(s)
- A Császár
- 3rd Department of Medicine, Semmelweis University of Medicine, Budapest, Hungary
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