Sometimes a cigar is just a cigar

Blood ◽  
2010 ◽  
Vol 116 (9) ◽  
pp. 1394-1395
Author(s):  
Shih-Hon Li ◽  
Daniel A. Lawrence
Keyword(s):  
Plasminogen Activator ◽  
Molecular Interactions ◽  
Mouse Strain ◽  
Mutant Form ◽  
Primary Role ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator

In this issue of Blood, Connolly and colleagues describe an elegant approach to studying the significance of specific molecular interactions in vivo. The authors have “knocked-in” a mutant form of the protease, urokinase-type plasminogen activator (uPA), into the murine uPA locus, to create a mouse strain (PlauGFDhu/GFDhu) where the interaction between endogenous uPA and its receptor (uPAR) is selectively disrupted, while leaving other functions of both uPA and uPAR intact. Their findings suggest that the primary role of uPAR in vivo is to promote fibrinolysis within tissues through localization of uPA, and that many of the previously described activities of uPAR may be secondary to this process.1

Evidence for the Expression of Urokinase-type Plasminogen Activator by Human Venous Endothelial Cells In Vivo

1998 ◽  
Vol 80 (12) ◽  
pp. 961-967 ◽  
Author(s):  
L. Camoin ◽  
R. Pannell ◽  
F. Anfosso ◽  
J. P. Lefevre ◽  
J. Sampol ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Plasminogen Activator ◽  
Animal Studies ◽  
Normal Subjects ◽  
Immunomagnetic Beads ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Tissue Plasminogen

SummaryEndothelial cells (ECs) in culture synthesize and secrete urokinase-type plasminogen activator (u-PA), but the normal vascular endothelium is believed to synthesize only tissue plasminogen activator (t-PA), which is thought to be responsible for intravascular fibrinolysis. More recently, animal studies have shown that the biological role of u-PA in fibrinolysis has been underestimated, prompting a re-examination of its synthesis by the endothelium. In this study, we investigated whether u-PA was synthesized by non-atherosclerotic endothelial cells in vivo by testing ECs dislodged by venipuncture from 12 normal volunteers and 17 patients admitted for plasmapheresis. The ECs were isolated with an anti-endothelial monoclonal antibody coupled to immunomagnetic beads and characterized by morphology and by labelling for vWF, CD31, and UEA-1 binding. U-PA antigen was found in 50% of the ECs from the normal subjects and in 60% of those from patients. U-PA enzymatic activity on zymograms was detected in 50% of the normal samples and 60% of the patient samples, with the latter being more frequently and more strongly positive. U-PA mRNA was found in all the normal and patient samples tested. The results indicate that u-PA is synthesized by the venous endothelium in vivo but that its expression is highly variable.

The Role of the Low-Density Lipoprotein Receptor-Related Protein (LRP) in the Plasma Clearance and Liver Uptake of Recombinant Single-chain Urokinase-type Plasminogen Activator in Rats

1997 ◽  
Vol 77 (04) ◽  
pp. 710-717 ◽  
Author(s):  
Marieke E van der Kaaden ◽  
Dingeman C Rijken ◽  
J Kar Kruijt ◽  
Theo J C van Berkel ◽  
Johan Kuiper
Keyword(s):  
Plasminogen Activator ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Single Chain ◽  
Liver Uptake ◽  
Type Plasminogen Activator ◽  
Parenchymal Liver ◽  
Urokinase Type Plasminogen Activator ◽  
Density Lipoprotein Receptor

SummaryUrokinase-type plasminogen activator (u-PA) is used as a thrombolytic agent in the treatment of acute myocardial infarction. In vitro, recombinant single-chain u-PA (rscu-PA) expressed in E.coli is recognized by the Low-Density Lipoprotein Receptor-related Protein (LRP) on rat parenchymal liver cells. In this study we investigated the role of LRP in the liver uptake and plasma clearance of rscu-PA in rats. A preinjection of the LRP inhibitor GST-RAP reduced the maximal liver uptake of 125I-rscu-PA at 5 min after injection from 50 to 30% of the injected dose and decreased the clearance of rscu-PA from 2.37 ml/min to 1.58 ml/min. Parenchymal, Kupffer and endothelial cells were responsible for 40, 50 and 10% of the liver uptake, respectively. The reduction in liver uptake of rscu-PA by the preinjection of GST-RAP was caused by a 91 % and 62% reduction in the uptake by parenchymal and Kupffer cells, respectively. In order to investigate the part of rscu-PA that accounted for the interaction with LRP, experiments were performed with a mutant of rscu-PA lacking residues 11-135 (= deltal25- rscu-PA). Deletion of residues 11-135 resulted in a 80% reduction in liver uptake and a 2.4 times slower clearance (0.97 ml/min). The parenchymal, Kupffer and endothelial cells were responsible for respectively 60, 33 and 7% of the liver uptake of 125I-deltal25-rscu-PA. Preinjection of GST-RAP completely reduced the liver uptake of delta 125-rscu-PA and reduced its clearance to 0.79 ml/min. Treatment of isolated Kupffer cells with PI-PLC reduced the binding of rscu-PA by 40%, suggesting the involvement of the urokinase-type Plasminogen Activator Receptor (u-PAR) in the recognition of rscu-PA. Our results demonstrate that in vivo LRP is responsible for more than 90% of the parenchymal liver cell mediated uptake of rscu-PA and for 60% of the Kupffer cell interaction. It is also suggested that u-PAR is involved in the Kupffer cell recognition of rscu-PA.

Urokinase-type plasminogen activator receptor is associated with the development of adipose tissue

2010 ◽  
Vol 104 (12) ◽  
pp. 1124-1132 ◽  
Author(s):  
Hiroyuki Matsuno ◽  
Eri Kawashita ◽  
Kiyotaka Okada ◽  
Hidetaka Suga ◽  
Shigeru Ueshima ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Plasminogen Activator ◽  
Adipocyte Differentiation ◽  
Cellular Adhesion ◽  
Wild Type ◽  
Tissue Mass ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator ◽  
Plasminogen Activator Receptor

SummaryUrokinase-type plasminogen activator receptor (uPAR) plays a role in cellular responses which include cellular adhesion, differentiation, proliferation and migration. The aim of this study was to clarify the role of uPAR on the development of adipose tissue. To clarify the role of uPAR on adipogenesis, we examined the effect of uPAR overexpression and uPAR deficiency on the adipocyte differentiation. Adipocyte differentiation was induced by incubation of 3T3-L1 cells with differentiation media containing insulin, dexamethasone, and 1-methyl-3-isobutylxanthin. uPAR overexpression by transfection of uPAR expression vector induced adipocyte differentiation. In addition, we examined the difference in adipocyte differentiation of mesenchymal stem cells from wild-type mice and uPAR knockout (uPAR-/-) mice. The uPAR deficiency attenuated differentiation media-induced adipocyte differentiation. Moreover, we found that the inhibition of phosphatidylinositol 3-kinase (PI3K) pathway attenuated uPAR overexpression-induced adipocyte differentiation, and uPAR overexpression induced the activation of Akt. We also found that an increase of the adipose tissue mass in uPAR-/- mice was less than that observed in wild-type mice. The present results suggest that uPAR plays a pivotal role in the development of adipose tissue through PI3K/Akt pathway.

scholarly journals Constriction of carotid arteries by urokinase-type plasminogen activator requires catalytic activity and is independent of NH2-terminal domains

2009 ◽  
Vol 102 (11) ◽  
pp. 983-992 ◽  
Author(s):  
Philip Massey ◽  
Shinji Tanaka ◽  
Joshua Buckler ◽  
Bo Jiang ◽  
Anton McCourtie ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Plasminogen Activator ◽  
Carotid Arteries ◽  
Artery Wall ◽  
Kringle Domains ◽  
Type Plasminogen Activator ◽  
Endothelial Surface ◽  
Urokinase Type Plasminogen Activator ◽  
Human Arteries

SummaryUrokinase-type plasminogen activator (uPA) is expressed at increased levels in stenotic, atherosclerotic human arteries. However, the biological roles of uPA in the artery wall are poorly understood. Previous studies associate uPA with both acute vasoconstriction and chronic vascular remodeling and attribute uPA-mediated vasoconstriction to the kringle – not the catalytic domain of uPA. We used an in-vivo uPA overexpression model to test the hypothesis that uPA-induced vasoconstriction is a reversible vasomotor process that can be prevented – and uPA fibrinolytic activity preserved – by: 1) removing the growth factor and kringle domains; or 2) anchoring uPA to the endothelial surface. To test this hypothesis we constructed adenoviral vectors that express: wild-type rabbit uPA (AduPA); a uPA mutant lacking the NH2-terminal growth-factor and kringle domains (Adu-PAdel); a mutant lacking catalytic activity (AduPAS→A), and a cell-surface anchored mutant (AdTMuPA). uPA mutants were expressed and characterised in vitro and in carotid arteries in vivo. uPAS→A had no plasminogen activator activity. Activity was similar for uPA and uPAdel, whereas AdTMuPA had only cell-associated activity. AduPAS→A arteries were not constricted. AduPA, AduPAdel, and AdTM-uPA arteries were constricted (approximately 30% smaller lumens; p≤0.008 vs. AdNull arteries). Papaverine reversed constriction of AduPA arteries. uPA-mediated arterial constriction is a vasomotor process that is mediated by uPA catalytic activity, not by the NH2-terminal domains. Anchoring uPA to the endothelial surface does not prevent vasoconstriction. uPA catalytic activity, generated by artery wall cells, may contribute to lumen loss in human arteries. Elimination of uPA vasoconstrictor activity requires concomitant loss of fibrinolytic activity.

Urokinase-type plasminogen activator and plasminogen mediate activation of macrophage phagocytosis during liver repair in vivo

2012 ◽  
Vol 107 (04) ◽  
pp. 749-759 ◽  
Author(s):  
Naoyuki Kawao ◽  
Nobuo Nagai ◽  
Yukinori Tamura ◽  
Yoshitaka Horiuchi ◽  
Katsumi Okumoto ◽  
...  
Keyword(s):  
Plasminogen Activator ◽  
Golgi Complex ◽  
Border Region ◽  
Primary Role ◽  
Wild Type ◽  
Macrophage Phagocytosis ◽  
Type Plasminogen Activator ◽  
Cellular Debris ◽  
Urokinase Type Plasminogen Activator ◽  
Liver Repair

SummaryUrokinase-type plasminogen activator (u-PA) and plasminogen play a primary role in liver repair through the accumulation of macrophages and alteration of their phenotype. However, it is still unclear whether u-PA and plasminogen mediate the activation of macrophage phagocytosis during liver repair. Herein, we investigated the morphological changes in macrophages that accumulated at the edge of damaged tissue induced by a photochemical reaction or hepatic ischaemia-reperfu-sion in mice with u-PA (u-PA−/− ) or plasminogen (Plg−/− ) gene deficiency by using transmission electron and fluorescence microscopy. In wild-type mice, the macrophages aligned at the edge of the damaged tissue and extended a large number of long pseudopodia. These macrophages clearly engulfed cellular debris and showed well-developed organelles, including lysosome-like vacuoles, nuclei, and Golgi complexes. In wild-type mice, the distribution of the Golgi complex in these macrophages was biased towards the direction of the damaged tissue, indicating the extension of their pseudopodia in this direction. Conversely, in u-PA−/− and Plg−/− mice, the macrophages located at the edge of the damaged tissue had few pseudopodia and less developed organelles. The Golgi complex was randomly distributed in these macrophages in u-PA−/− mice. Furthermore, interferon γ and IL-4 were expressed at a low level at the border region of the damaged tissue in u-PA−/− mice. Our data provide novel evidence that u-PA and plasminogen are essential for the phagocytosis of cellular debris by macrophages during liver repair. Furthermore, u-PA plays a critical role in the induction of macrophage polarity by affecting the microenvironment at the edge of damaged tissue.

ON THE MECHANISM OF THE IN VIVO SYNERGISM BETWEEN TISSUE-TYPE PLASMINOGEN ACTIVATOR (t-PA) AND SINGLE CHAIN UROKINASE-TYPE PLASMINOGEN ACTIVATOR (scu-PA)

1987 ◽  
Author(s):  
J M Stassen ◽  
D Collen
Keyword(s):  
Plasminogen Activator ◽  
Rabbit Model ◽  
Sequential Therapy ◽  
Tissue Type ◽  
Single Chain ◽  
Molar Ratios ◽  
Type Plasminogen Activator ◽  
Urokinase Type Plasminogen Activator

t-PA and scu-PA, in molar ratios between 1:4 and 4:1 do not act synergically in vitro (Thromb. Haemost. 56,35,1986) but display marked synergism in a rabbit model (Circulation 74, 838, 1986) and in man (Am. Heart J. 112, 1083, 1986). To investigate the mechanism of in vivo synergism in the rabbit model (J. Clin. Invest. 71, 368, 1983), t-PA and scu-PA were infused 1) simultaneously over 4 hrs, 2) t-PA over 1 hr, then 15 min later scu-PA over 2 hrs and 3) scu-PA over 1 hr, then 15 min later t-PA over 2 hrs.Significant synergism on thrombolysis is observed when t-PA and scu-PA are infused simultaneously or when t-PA is followed by scu-PA but not when scu-PA is followed by t-PA. These results suggest that low dose t-PA induces some plasminogen activation, sufficient to partially degrade fibrin, exposing COOH-terminal lysines with high affinity for plasminogen (Eur. J. Biochem. 140, 513, 1984). scu-PA might then activate surface-bound Glu-pla-minogen more efficiently.Sequential therapy with t-PA (or any other agent which "predigests" the thrombus), followed by scu-PA might constitute an alternative to simultaneous infusion of synergistic thrombolytic agents.

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