scholarly journals Regulation of α5β1 integrin conformation and function by urokinase receptor binding

2005 ◽  
Vol 168 (3) ◽  
pp. 501-511 ◽  
Author(s):  
Ying Wei ◽  
Ralf-Peter Czekay ◽  
Liliane Robillard ◽  
Matthias C. Kugler ◽  
Feng Zhang ◽  
...  
Keyword(s):  
Cell Attachment ◽  
Alternative Activation ◽  
Cis Acting ◽  
Type Iii ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Β1 Integrins ◽  
Direct Binding ◽  
And Function ◽  
Interfering Rna

Urokinase-type plasminogen activator receptors (uPARs), up-regulated during tumor progression, associate with β1 integrins, localizing urokinase to sites of cell attachment. Binding of uPAR to the β-propeller of α3β1 empowers vitronectin adhesion by this integrin. How uPAR modifies other β1 integrins remains unknown. Using recombinant proteins, we found uPAR directly binds α5β1 and rather than blocking, renders fibronectin (Fn) binding by α5β1 Arg-Gly-Asp (RGD) resistant. This resulted from RGD-independent binding of α5β1–uPAR to Fn type III repeats 12–15 in addition to type III repeats 9–11 bound by α5β1. Suppression of endogenous uPAR by small interfering RNA in tumor cells promoted weaker, RGD-sensitive Fn adhesion and altered overall α5β1 conformation. A β1 peptide (res 224NLDSPEGGF232) that models near the known α-chain uPAR-binding region, or a β1-chain Ser227Ala point mutation, abrogated effects of uPAR on α5β1. Direct binding and regulation of α5β1 by uPAR implies a modified “bent” integrin conformation can function in an alternative activation state with this and possibly other cis-acting membrane ligands.

scholarly journals Urokinase-type plasminogen activator (uPA) regulates the expression and function of growth-associated protein 43 (GAP-43) in the synapse

2019 ◽  
Vol 295 (2) ◽  
pp. 619-630 ◽  
Author(s):  
Paola Merino ◽  
Ariel Diaz ◽  
Enrique R. Torre ◽  
Manuel Yepes
Keyword(s):  
Plasminogen Activator ◽  
Cortical Neurons ◽  
Release Site ◽  
Axonal Growth ◽  
Presynaptic Terminals ◽  
Type Plasminogen Activator ◽  
Mature Brain ◽  
Urokinase Type Plasminogen Activator ◽  
Vesicle Cycle ◽  
And Function

Growth-associated protein 43 (GAP-43) plays a central role in the formation of presynaptic terminals, synaptic plasticity, and axonal growth and regeneration. During development, GAP-43 is found in axonal extensions of most neurons. In contrast, in the mature brain, its expression is restricted to a few presynaptic terminals and scattered axonal growth cones. Urokinase-type plasminogen activator (uPA) is a serine proteinase that, upon binding to its receptor (uPAR), catalyzes the conversion of plasminogen into plasmin and activates signaling pathways that promote cell migration, proliferation, and survival. In the developing brain, uPA induces neuritogenesis and neuronal migration. In contrast, the expression and function of uPA in the mature brain are poorly understood. However, recent evidence reveals that different forms of injury induce release of uPA and expression of uPAR in neurons and that uPA/uPAR binding triggers axonal growth and synapse formation. Here we show that binding of uPA to uPAR induces not only the mobilization of GAP-43 from the axonal shaft to the presynaptic terminal but also its activation in the axonal bouton by PKC-induced calcium-dependent phosphorylation at Ser-41 (pGAP-43). We found that this effect requires open presynaptic N-methyl-d-aspartate receptors but not plasmin generation. Furthermore, our work reveals that, following its activation by uPA/uPAR binding, pGAP-43 colocalizes with presynaptic vesicles and triggers their mobilization to the synaptic release site. Together, these data reveal a novel role of uPA as an activator of the synaptic vesicle cycle in cerebral cortical neurons via its ability to induce presynaptic recruitment and activation of GAP-43.

Evaluation of Fibrinolytic Capacity in Plasma during Thrombolytic Therapy with Single (scu-PA) or Two-chain Urokinase Type Plasminogen Activator (tcu-PA) by a Combined Assay System for Urokinase Type Plasminogen Activator Antigen and Function

1989 ◽  
Vol 61 (02) ◽  
pp. 289-293 ◽  
Author(s):  
Johann Wojta ◽  
Bernd R Binder ◽  
Kurt Huber ◽  
Richard L Hoover
Keyword(s):  
Thrombolytic Therapy ◽  
Plasminogen Activator ◽  
Microtiter Plate ◽  
Assay System ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Coefficients Of Variation ◽  
Antigen Determination ◽  
And Function

SummaryA combined assay for urokinase type plasminogen activator (u-PA) activity and antigen determination in plasma samples is described. This assay is based on binding of u-PA to an antibody immobilized on a microtiter plate followed by determination of the enzymatic activity of the bound u-PA. Thereafter bound u-PA antigen can be quantified by means of a specific peroxidase labelled monoclonal antibody against u-PA. By use of this assay system u-PA activity and antigen can be determined with lower detection limits of 0.08 IU/ml and 1.0 ng/ml, respectively, and intraassay as well as interassay coefficients of variation of 10% and 12% for activity and 5% and 7% for antigen determinations, respectively. Normal plasma levels of u-PA antigen could be determined to be 1.88 nglml ± 0.61. Furthennore, this assay system allows specific quantification of u-PA antigen and activity during thrombolytic therapy.

scholarly journals Plasminogen Activators in Neurovascular and Neurodegenerative Disorders

2021 ◽  
Vol 22 (9) ◽  
pp. 4380
Author(s):  
Manuel Yepes ◽  
Yena Woo ◽  
Cynthia Martin-Jimenez
Keyword(s):  
Plasminogen Activator ◽  
Neurodegenerative Disorders ◽  
Neurovascular Unit ◽  
Dynamic Structure ◽  
Plasminogen Activators ◽  
Tissue Type ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
And Function ◽  
Cellular Components

The neurovascular unit (NVU) is a dynamic structure assembled by endothelial cells surrounded by a basement membrane, pericytes, astrocytes, microglia and neurons. A carefully coordinated interplay between these cellular and non-cellular components is required to maintain normal neuronal function, and in line with these observations, a growing body of evidence has linked NVU dysfunction to neurodegeneration. Plasminogen activators catalyze the conversion of the zymogen plasminogen into the two-chain protease plasmin, which in turn triggers a plethora of physiological events including wound healing, angiogenesis, cell migration and inflammation. The last four decades of research have revealed that the two mammalian plasminogen activators, tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA), are pivotal regulators of NVU function during physiological and pathological conditions. Here, we will review the most relevant data on their expression and function in the NVU and their role in neurovascular and neurodegenerative disorders.

scholarly journals Osteopontin ablation ameliorates muscular dystrophy by shifting macrophages to a pro-regenerative phenotype

2016 ◽  
Vol 213 (2) ◽  
pp. 275-288 ◽  
Author(s):  
Joana Capote ◽  
Irina Kramerova ◽  
Leonel Martinez ◽  
Sylvia Vetrone ◽  
Elisabeth R. Barton ◽  
...  
Keyword(s):  
Muscular Dystrophy ◽  
Muscle Strength ◽  
Macrophage Polarization ◽  
Inflammatory Cells ◽  
Mdx Mice ◽  
Muscle Weight ◽  
Cell Counts ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
And Function

In the degenerative disease Duchenne muscular dystrophy, inflammatory cells enter muscles in response to repetitive muscle damage. Immune factors are required for muscle regeneration, but chronic inflammation creates a profibrotic milieu that exacerbates disease progression. Osteopontin (OPN) is an immunomodulator highly expressed in dystrophic muscles. Ablation of OPN correlates with reduced fibrosis and improved muscle strength as well as reduced natural killer T (NKT) cell counts. Here, we demonstrate that the improved dystrophic phenotype observed with OPN ablation does not result from reductions in NKT cells. OPN ablation skews macrophage polarization toward a pro-regenerative phenotype by reducing M1 and M2a and increasing M2c subsets. These changes are associated with increased expression of pro-regenerative factors insulin-like growth factor 1, leukemia inhibitory factor, and urokinase-type plasminogen activator. Furthermore, altered macrophage polarization correlated with increases in muscle weight and muscle fiber diameter, resulting in long-term improvements in muscle strength and function in mdx mice. These findings suggest that OPN ablation promotes muscle repair via macrophage secretion of pro-myogenic growth factors.

Urokinase type plasminogen activator and inhibitor type-1 plasma levels in colorectal cancer

2001 ◽  
Vol 120 (5) ◽  
pp. A599-A600 ◽  
Author(s):  
L HERSZENYI ◽  
F FARINATI ◽  
G ISTVAN ◽  
M PAOLI ◽  
G ROVERONI ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Plasminogen Activator ◽  
Plasma Levels ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Inhibitor Type

Expression and Characterization of Clustered Charge-to-Alanine Mutants of Low Mr Single-Chain Urokinase-Type Plasminogen Activator

1994 ◽  
Vol 71 (01) ◽  
pp. 134-140 ◽  
Author(s):  
S Ueshima ◽  
P Holvoet ◽  
H R Lijnen ◽  
L Nelles ◽  
V Seghers ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Solvent Accessibility ◽  
Site Directed Mutagenesis ◽  
Clot Lysis ◽  
Wild Type ◽  
Single Chain ◽  
Charged Amino Acids ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Pharmacokinetic Properties

SummaryIn an effort to modify the fibrinolytic and/or pharmacokinetic properties of recombinant low M r single-chain urokinase-type plasminogen activator (rscu-PA-32k), mutants were prepared by site-directed mutagenesis of clusters of charged amino acids with the highest solvent accessibility. The following mutants of rscu-PA-32k were prepared: LUK-2 (Lys 212, Glu 213 and Asp 214 to Ala), LUK-3 (Lys 243 and Asp 244 to Ala), LUK-4 (Arg 262, Lys 264, Glu 265 and Arg 267 to Ala), LUK-5 (Lys 300, Glu 301 and Asp 305 to Ala) and LUK-6 (Arg 400, Lys 404, Glu 405 and Glu 406 to Ala).The rscu-PA 32k moictic3 were expressed in High Five Ttichoplasiani cells, and purified to humugciicily from the conditioned cell culture medium, with recoveries of 0.8 to 3.7 mg/1. The specific fibrinolytic activities (220,000 to 300,000 IU/mg), the rates of plasminogen activation by the single-chain moieties and the rates of conversion In lwo chain moieties by plasmin were comparable for mutant and wild-type rscu PA 32k moieties, with the exception of LUK-5 which was virtually inactive. Equi-effective lysis (50% in 2 h) of 60 pi 125I-fibrin labeled plasma clots submerged in 0.5 ml normal human plasma was obtained with 0.7 to 0.8 μg/ml of wild-type or mutant rscu-PA-3?.k, except with LUK-5 (no significant lysis with 16 pg/ml). Following bolus injection in hamsters, all rscu-PA-32k moieties had a comparably rapid plasma clearance (1.3 to 2.7 ml/min), as a result of a short initial half-life (1.4 to 2.5 min). In hamsters with pulmonary embolism, continuous intravenous infusion over 60 min at a dose of 1 mg/kg, resulted in 53 to 72% clot lysis with the mutants, but only 23% with LUK-5, as compared to 36% for wild-type rscu-PA-32k.These data indicate that clustered charge-to-alanine mutants of rscu-PA-32k, designed to eliminate charged regions with the highest solvent accessibility, do not have significantly improved functional, fibrinolytic or pharmacokinetic properties.

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