scholarly journals A Serpin With a Finger in Many PAIs: PAI-1's Central Function in Thromboinflammation and Cardiovascular Disease

2021 ◽  
Vol 8 ◽  
Author(s):  
Gael B. Morrow ◽  
Claire S. Whyte ◽  
Nicola J. Mutch
Keyword(s):  
Cardiovascular Disease ◽  
Metabolic Syndrome ◽  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Plasminogen Activator Inhibitor 1 ◽  
Central Function ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Thrombotic Complications ◽  
Pai 1

Plasminogen activator inhibitor 1 (PAI-1) is a member of the serine protease inhibitor (serpin) superfamily. PAI-1 is the principal inhibitor of the plasminogen activators, tissue plasminogen activator (tPA), and urokinase-type plasminogen activator (uPA). Turbulence in the levels of PAI-1 tilts the balance of the hemostatic system resulting in bleeding or thrombotic complications. Not surprisingly, there is strong evidence that documents the role of PAI-1 in cardiovascular disease. The more recent uncovering of the coalition between the hemostatic and inflammatory pathways has exposed a distinct role for PAI-1. The storm of proinflammatory cytokines liberated during inflammation, including IL-6 and TNF-α, directly influence PAI-1 synthesis and increase circulating levels of this serpin. Consequently, elevated levels of PAI-1 are commonplace during infection and are frequently associated with a hypofibrinolytic state and thrombotic complications. Elevated PAI-1 levels are also a feature of metabolic syndrome, which is defined by a cluster of abnormalities including obesity, type 2 diabetes, hypertension, and elevated triglyceride. Metabolic syndrome is in itself defined as a proinflammatory state associated with elevated levels of cytokines. In addition, insulin has a direct impact on PAI-1 synthesis bridging these pathways. This review describes the key physiological functions of PAI-1 and how these become perturbed during disease processes. We focus on the direct relationship between PAI-1 and inflammation and the repercussion in terms of an ensuing hypofibrinolytic state and thromboembolic complications. Collectively, these observations strengthen the utility of PAI-1 as a viable drug target for the treatment of various diseases.

scholarly journals Deep mutational scanning of the plasminogen activator inhibitor-1 functional landscape

2021 ◽  
Author(s):  
Zachary M Huttinger ◽  
Laura M Haynes ◽  
Andrew Yee ◽  
Colin A Kretz ◽  
David R Siemieniak ◽  
...  
Keyword(s):  
Amino Acid ◽  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Single Amino Acid ◽  
Plasminogen Activator Inhibitor 1 ◽  
Missense Variants ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Activator Inhibitor ◽  
Pai 1

The serine protease inhibitor (SERPIN) plasminogen activator inhibitor-1 (PAI-1) is a key regulator of the fibrinolytic system, inhibiting the serine proteases tissue- and urokinase-type plasminogen activator (tPA and uPA, respectively). Missense variants may render PAI-1 non-functional through misfolding, leading to its turnover as a protease substrate, or to a more rapid transition to the latent/inactive state. Deep mutational scanning was performed to evaluate the impact of amino acid sequence variation on PAI-1 inhibition of uPA using an M13 filamentous phage display system. The effects of single amino acid substitutions on PAI-1's functional inhibition of its canonical target proteases, tPA and uPA , have been determined for only a small fraction of potential mutations. To construct a more comprehensive dataset, a mutagenized PAI-1 library, encompassing ~70% of potential single amino acid substitutions, was displayed on M13 filamentous phage. From this library, the relative effects of 27% of all possible missense variants on PAI-1 inhibition of urokinase-type plasminogen activator were determined using high-throughput DNA sequencing with 826 missense variants demonstrating conserved inhibitory activity and 1137 resulting in loss of PAI-1 function. Comparison of these deep mutational scanning results to predictions from PolyPhen-2 and SIFT demonstrate the limitations of these algorithms, consistent with similar reports for other proteins. Comparison to common human PAI-1 gene variants present in the gnomAD database is consistent with evolutionary selection against loss of PAI-1 function. These findings provide insight into structure-function relationships for PAI-1 and other members of the SERPIN superfamily.

scholarly journals Is plasminogen activator inhibitor-1 the molecular switch that governs urokinase receptor-mediated cell adhesion and release?

1996 ◽  
Vol 134 (6) ◽  
pp. 1563-1571 ◽  
Author(s):  
G Deng ◽  
S A Curriden ◽  
S Wang ◽  
S Rosenberg ◽  
D J Loskutoff
Keyword(s):  
Cell Adhesion ◽  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Migration And Invasion ◽  
Binding Motif ◽  
Plasminogen Activator Inhibitor 1 ◽  
Amino Terminal ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Pai 1

Induction of the urokinase type plasminogen activator receptor (uPAR) promotes cell adhesion through its interaction with vitronectin (VN) in the extracellular matrix, and facilitates cell migration and invasion by localizing uPA to the cell surface. We provide evidence that this balance between cell adhesion and cell detachment is governed by PA inhibitor-1 (PAI-1). First, we demonstrate that uPAR and PAI-1 bind to the same site in VN (i.e., the amino-terminal somatomedin B domain; SMB), and that PAI-1 competes with uPAR for binding to SMB. Domain swapping and mutagenesis studies indicate that the uPAR-binding sequence is located within the central region of the SMB domain, a region previously shown to contain the PAI-1-binding motif. Second, we show that PAI-1 dissociates bound VN from uPAR and detaches U937 cells from their VN substratum. This PAI-1 mediated release of cells from VN appears to occur independently of its ability to function as a protease inhibitor, and may help to explain why high PAI-1 levels indicate a poor prognosis for many cancers. Finally, we show that uPA can rapidly reverse this effect of PAI-1. Taken together, these results suggest a dynamic regulatory role for PAI-1 and uPA in uPAR-mediated cell adhesion and release.

scholarly journals Down-regulation of Plasminogen Activator Inhibitor 1 Expression Promotes Myocardial Neovascularization by Bone Marrow Progenitors

2004 ◽  
Vol 200 (12) ◽  
pp. 1657-1666 ◽  
Author(s):  
Guosheng Xiang ◽  
Michael D. Schuster ◽  
Tetsunori Seki ◽  
Alfred A. Kocher ◽  
Shawdee Eshghi ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Plasminogen Activator Inhibitor 1 ◽  
Down Regulation ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Mrna And Protein Expression ◽  
Activator Inhibitor ◽  
Pai 1

Human adult bone marrow–derived endothelial progenitors, or angioblasts, induce neovascularization of infarcted myocardium via mechanisms involving both cell surface urokinase-type plasminogen activator, and interactions between β integrins and tissue vitronectin. Because each of these processes is regulated by plasminogen activator inhibitor (PAI)-1, we selectively down-regulated PAI-1 mRNA in the adult heart to examine the effects on postinfarct neovascularization and myocardial function. Sequence-specific catalytic DNA enzymes inhibited rat PAI-1 mRNA and protein expression in peri-infarct endothelium within 48 h of administration, and maintained down-regulation for at least 2 wk. PAI-1 inhibition enhanced vitronectin-dependent transendothelial migration of human bone marrow–derived CD34+ cells, and resulted in a striking augmentation of angioblast-dependent neovascularization. Development of large, thin-walled vessels at the peri-infarct region was accompanied by induction of proliferation and regeneration of endogenous cardiomyocytes and functional cardiac recovery. These results identify a causal relationship between elevated PAI-1 levels and poor outcome in patients with myocardial infarction through mechanisms that directly inhibit bone marrow–dependent neovascularization. Strategies that reduce myocardial PAI-1 expression appear capable of enhancing cardiac neovascularization, regeneration, and functional recovery after ischemic insult.

Analysis of a two-domain binding site for the urokinase-type plasminogen activator–plasminogen activator inhibitor-1 complex in low-density-lipoprotein-receptor-related protein

2001 ◽  
Vol 357 (1) ◽  
pp. 289-296 ◽  
Author(s):  
Olav M. ANDERSEN ◽  
Helle H. PETERSEN ◽  
Christian JACOBSEN ◽  
S⊘ren K. MOESTRUP ◽  
Michael ETZERODT ◽  
...  
Keyword(s):  
Binding Site ◽  
Plasminogen Activator ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Plasminogen Activator Inhibitor ◽  
Plasminogen Activator Inhibitor 1 ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Density Lipoprotein Receptor ◽  
Pai 1

The low-density-lipoprotein-receptor (LDLR)-related protein (LRP) is composed of several classes of domains, including complement-type repeats (CR), which occur in clusters that contain binding sites for a multitude of different ligands. Each ≈ 40-residue CR domain contains three conserved disulphide linkages and an octahedral Ca2+ cage. LRP is a scavenging receptor for ligands from extracellular fluids, e.g. α2-macroglobulin (α2M)–proteinase complexes, lipoprotein-containing particles and serine proteinase–inhibitor complexes, like the complex between urokinase-type plasminogen activator (uPA) and the plasminogen activator inhibitor-1 (PAI-1). In the present study we analysed the interaction of the uPA–PAI-1 complex with an ensemble of fragments representing a complete overlapping set of two-domain fragments accounting for the ligand-binding cluster II (CR3–CR10) of LRP. By ligand blotting, solid-state competition analysis and surface-plasmon-resonance analysis, we demonstrate binding to multiple CR domains, but show a preferential interaction between the uPA–PAI-1 complex and a two-domain fragment comprising CR domains 5 and 6 of LRP. We demonstrate that surface-exposed aspartic acid and tryptophan residues at identical positions in the two homologous domains, CR5 and CR6 (Asp958,CR5, Asp999,CR6, Trp953,CR5 and Trp994,CR6), are critical for the binding of the complex as well as for the binding of the receptor-associated protein (RAP)–the folding chaperone/escort protein required for transport of LRP to the cell surface. Accordingly, the present work provides (1) an identification of a preferred binding site within LRP CR cluster II; (2) evidence that the uPA–PAI-1 binding site involves residues from two adjacent protein domains; and (3) direct evidence identifying specific residues as important for the binding of uPA–PAI-1 as well as for the binding of RAP.

A Specific Immunologic Assay for Functional Plasminogen Activator Inhibitor 1 in Plasma – Standardized Measurements of the Inhibitor and Related Parameters in Patients with Venous Thromboembolic Disease

1992 ◽  
Vol 68 (05) ◽  
pp. 486-494 ◽  
Author(s):  
Malou Philips ◽  
Anne-Grethe Juul ◽  
Johan Selmer ◽  
Bent Lind ◽  
Sixtus Thorsen
Keyword(s):  
Plasminogen Activator ◽  
Plasminogen Activator Inhibitor ◽  
Normal Subjects ◽  
Tissue Type ◽  
Blood Collection ◽  
Plasminogen Activator Inhibitor 1 ◽  
Type Plasminogen Activator ◽  
Significant Difference ◽  
Activator Inhibitor ◽  
Pai 1

SummaryA new assay for functional plasminogen activator inhibitor 1 (PAI-1) in plasma was developed. The assay is based on the quantitative conversion of PAI-1 to urokinase-type plasminogen activator (u-PA)-PAI-l complex the concentration of which is then determined by an ELISA employing monoclonal anti-PAI-1 as catching antibody and monoclonal anti-u-PA as detecting antibody. The assay exhibits high sensitivity, specificity, accuracy, and precision. The level of functional PAI-1, tissue-type plasminogen activator (t-PA) activity and t-PA-PAI-1 complex was measured in normal subjects and in patients with venous thromboembolism in a silent phase. Blood collection procedures and calibration of the respective assays were rigorously standardized. It was found that the patients had a decreased fibrinolytic capacity. This could be ascribed to high plasma levels of PAI-1. The release of t-PA during venous occlusion of an arm for 10 min expressed as the increase in t-PA + t-PA-PAI-1 complex exhibited great variation and no significant difference could be demonstrated between the patients with a thrombotic tendency and the normal subjects.

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