The Plasminogen Activator System in Fibroblasts from Systemic Sclerosis (original) (raw)
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Annals of the Rheumatic Diseases, 2013
Objective Urokinase-type plasminogen activator receptor (uPAR) is a key component of the fibrinolytic system involved in extracellular matrix remodelling and angiogenesis. The cleavage/inactivation of uPAR is a crucial step in fibroblast-to-myofibroblast transition and has been implicated in systemic sclerosis (SSc) microvasculopathy. In the present study, we investigated whether uPAR gene inactivation in mice could result in tissue fibrosis and peripheral microvasculopathy resembling human SSc. Methods The expression of the native full-length form of uPAR in human skin biopsies was determined by immunohistochemistry. Skin and lung sections from uPAR-deficient (uPAR −/− ) and wild-type (uPAR +/+ ) mice at 12 and 24 weeks of age were stained with haematoxylin-eosin, Masson's trichrome and Picrosirius red. Dermal thickness and hydroxyproline content in skin and lungs were quantified. Dermal myofibroblast and microvessel counts were determined by immunohistochemistry for α-smooth muscle actin and CD31, respectively. Endothelial cell apoptosis was assessed by TUNEL/CD31 immunofluorescence assay. Results Full-length uPAR expression was significantly downregulated in SSc dermis, especially in fibroblasts and endothelial cells. Dermal thickness, collagen content and myofibroblast counts were significantly greater in uPAR −/− than in uPAR +/+ mice. In uPAR −/− mice, dermal fibrosis was paralleled by endothelial cell apoptosis and severe loss of microvessels. Lungs from uPAR −/− mice displayed non-specific interstitial pneumonia-like pathological features, both with inflammation and collagen deposition. Pulmonary pathology worsened significantly from 12 to 24 weeks, as shown by a significant increase in alveolar septal width and collagen content. Conclusions uPAR −/− mice are a new animal model closely mimicking the histopathological features of SSc. This model warrants future studies. Manetti M, et al. Ann Rheum Dis 2013;0:1-10.
The Journal of Cell Biology, 1987
We studied the immunocytochemical localization of urokinase-type plasminogen activator (u-PA) and the type 1 plasminogen activator inhibitor (PAI-1) in human fibroblasts and sarcoma cells, using both polyclonal and monoclonal antibodies. The u-PA was found to be located at discrete cell-substratum contact sites, and also at areas of cell-cell contacts, whereas PAI-1 was distributed as a homogenous carpet excluding strialike areas on the substrate under the cells. To confirm the extracellular localization of u-PA and PAIl, we stained the cells live at 0°C before fixation. A double-labeling experiment showed different distribution of u-PA and PAI-1 under the cells, and especially their peripheral parts. The staining pattern of u-PA and PAI-1 resisted treatment with 0.2% saponin 2. Nomenclature recommended by the Subcommittee on Fibrinolysis of the
Journal of Biological …, 1986
An approximately 75% pure form of a human M,-54,000 plasminogen activator inhibitor from conditioned culture fluid of the fibrosarcoma cell line HT-1080 was obtained by a single step of chromatography on concanavalin A-Sepharose. The inhibitor inhibited human urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator, but not plasmin. Rabbit antibodies against this plasminogen activator inhibitor also reacted with a plasminogen activator inhibitor with identical electrophoretic mobility in extracts of human blood platelets, indicating that the HT-1080-inhibitor is of the same type as the inhibitor of blood platelets. As revealed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by fibrin-agarose zymography, incubation of HT-1080inhibitor with the active form of human u-PA led to the formation of an equimolar sodium dodecyl sulfateresistant complex between them; in contrast, no complex formation was observed between the inhibitor and the proenzyme form of human u-PA (pro-u-PA). Likewise, using a column of anti-inhibitor antibodies coupled to Sepharose for removal of excess inhibitor and activator-inhibitor complexes, the potential enzymatic activity of pro-u-PA was found to be unaffected by incubation with inhibitor under conditions in which more than 95% of the active u-PA had formed complex with inhibitor. Plasminogen activators comprise a group of serine proteases, which by limited proteolysis convert the abundant extracellular proenzyme plasminogen to the active protease plasmin. Plasmin has a relatively broad trypsin-like specificity. Release of plasminogen activators from cells may thus initiate localized extracellular proteolysis. TWO types of plasminogen activators have been recognized in mammals, the urokinase-type (u-PA1) and the tissue-type (t-PA), with M I of-50,000 and-70,000, respectively. They are products of different genes (1-3). Several functions have been proposed
Biological Chemistry, 2002
domain, kringle(s), a serine protease domain and also a finger domain for t-PA] (Ny et al., 1984; Danø et al., 1994). As serine proteases, PAs are involved in many physiological and pathological processes, including embryogenesis, tissue repair, chemotaxis, fibrinolysis, angiogenesis and tumor invasion. These processes are complex and may involve different types of events, including proteolysis, migration and/or proliferation of a variety of cell types. t-PA is thought to be mainly involved in fibrinolysis, whereas u-PA in association with its receptor (u-PAR) is thought to play a role in the tissue processes of localized and directional proteolysis (Pollanen et al., 1991; Johnsen et al., 1998). u-PA and t-PA control a variety of proteolytic processes: a cascade of events mediated by the activation of plasminogen (PG) in plasmin, which in turn may activate the procollagenases in collagenases (Johnsen et al., 1998); the biological activation of HGF, from the single-to the two-chain form (Mars et al., 1993); and the direct degradation of plasma and cellular FN (pFN, cFN) at specific sites (Gold et al., 1992; Marchina and Barlati, 1996). PAs are involved in many processes. In particular, the following has been demonstrated: u-PA stimulates the migration and proliferation of a variety of tumor and normal cells (Kirchheimer et al., 1989; Blasi, 1997; Chapman, 1997); t-PA is involved in the mitogenesis of cultured human skin fibroblasts (De Petro et al., 1994) and of human aortic smooth muscle cells (Herbert et al., 1994); u-PA, in association with its receptor, and independently of its serine protease domain, may transduce intracellular signals (via PTK, CK2…), which are involved in cell migration and proliferation (Dumler et al., 1999). For the role of PAs in the process of tumor growth and invasion, evidence is emerging that they may play a distinct role, at least in certain types of solid tumors. Indeed, the high levels of u-PA, and not of t-PA, are unfavorable prognostic factors for cancer patients with several types of tumors (Schmitt et al., 2000), whereas the high levels of t-PA detected in certain malignant conditions are associated with a better prognosis (Yamashita et al., 1993; Ferrier et al., 2000). According to our previous data, in human hepatocellular carcinoma the high levels of u-PA mRNA, and not of t-PA mRNA, detected in the tumor biopsies were inversely related to patient survival (De Petro et al., 1998). In breast carcinoma and in primary melanoma of the limb, the high levels of t-PA were correlated with a better prognosis (
Clinical & Experimental Immunology, 2005
Accumulative data have demonstrated that plasminogen activator inhibitor-1 (PAI-1) plays an important role in the extracellular matrix metabolism; however, the involvement of PAI-1 in scleroderma has not been fully elucidated. In this study, we investigated the role of PAI-1 in bleomycin-induced murine scleroderma. 100 m m m m g of bleomycin was injected subcutaneously to the back skin of C3H/HeJ mice on alternate day for 4 weeks. Histopathological findings revealed that PAI-1 was positive in macrophage-like cells and fibroblastic cells in the dermis, in parallel with the induction of dermal sclerosis. PAI-1 mRNA expression in the whole skin was up-regulated at 1 and 4 weeks. The production of active PAI-1 protein in the lesional skin was significantly increased 3 and 4 weeks after bleomycin treatment. Next, we examined whether dermal sclerosis is induced by bleomycin in PAI-1-deficient (PAI-1-/-) mice. 10 m m m m g of bleomycin was subcutaneously injected to PAI-1-/-and wild type (WT) mice 5 days per week for 4 weeks. Histological examination revealed that dermal sclerosis was similarly induced even in PAI-1-/-as well as WT mice. Dermal thickness and collagen contents in the skin were significantly increased by bleomycin injection in both PAI-1-/-and WT mice, and the rate of increase was similar. These data suggest that PAI-1 plays an important role, possibly via TGF-b b b b pathway activation. However, the fact that PAI-1 deficiency did not ameliorate skin sclerosis suggest that PAI-1 is not the essential factor in the development of bleomycin-induced scleroderma, and more complex biochemical effects other than PA/plasmin system are greatly suspected.
Annals of the Rheumatic Diseases
Urokinase type plasminogen activator (uPA) catalyses the formation of the proteolytic enzyme plasmin, which is involved in matrix degradation in the processes of tissue remodelling. Because of a surface bound uPA receptor (uPAR), expressed by some cell types (for example, macrophages, malignant cells and inflammatory activated synoviocytes), the action of uPA can be localised and intensified. uPAR seems to have a role in the mechanisms leading to invasive growth of malignant tissue and the rheumatoid pannus. uPAR may become cleaved at its cell surface anchor, thus forming a free soluble receptor (suPAR). suPAR is detectable in low but constant values in plasma of healthy people, while increased concentrations are found in patients with disseminated malignant disease, so that suPAR may be an indicator of invasive growth and tissue remodelling. suPAR concentrations in plasma have not previously been measured in rheumatic patients. A controlled cross sectional measurement was performed...
Frontiers in oncology, 2018
The plasminogen activator (PA) system is an extracellular proteolytic enzyme system associated with various physiological and pathophysiological processes. A large body of evidence support that among the various components of the PA system, urokinase-type plasminogen activator (uPA), its receptor (uPAR), and plasminogen activator inhibitor-1 and-2 (PAI-1 and PAI-2) play a major role in tumor progression and metastasis. The binding of uPA with uPAR is instrumental for the activation of plasminogen to plasmin, which in turn initiates a series of proteolytic cascade to degrade the components of the extracellular matrix, and thereby, cause tumor cell migration from the primary site of origin to a distant secondary organ. The components of the PA system show altered expression patterns in several common malignancies, which have identified them as ideal diagnostic, prognostic, and therapeutic targets to reduce cancer-associated morbidity and mortality. This review summarizes the various components of the PA system and focuses on the role of uPA-uPAR in different biological processes especially in the context of malignancy. We also discuss the current state of knowledge of uPA-uPAR-targeted diagnostic and therapeutic strategies for various malignancies.
The urokinase plasminogen activator and its receptor
Thrombosis and Haemostasis, 2005
SummaryThe urinary-type plasminogen activator, or uPA, controls matrix degradation through the conversion of plasminogen into plasmin and is regarded as the critical trigger for plasmin generation during cell migration and invasion, under physiological and pathological conditions (such as cancer metastasis).The proteolytic activity of uPA is responsible for the activation or release of several growth factors and modulates the cell survival/apoptosis ratio through the dynamic control of cell-matrix contacts. The urokinase receptor (uPAR), binding to the EGF-like domain of uPA, directs membrane-associated extracellular proteolysis and signals through transmembrane proteins, thus regulating cell migration, adhesion and cytoskeletal status. However, recent evidence highlights an intricate relationship linking the uPA/uPAR system to cell growth and apoptosis.
1995
The ability of p53 to activate or repress transcription suggests that its biological function as tumor suppressor is in part accomplished by regulating a number of genes including such required for inhibition of cell growth. We here give evidence that p53 also may regulate genes responsible for the proteolytic degradation of the extracellular matrix, which is considered a crucial feature for local invasion and metastasis of neoplastic cells. An important and highly regulated cascade of such proteolytic events involves the plasminogen activator system. We show that wild-type p53 represses transcription from the enhancer and promoter of the human urokinase-type (u-PA) and the tissue-type plasminogen activator (t-PA) gene through a non-DNA binding mechanism. Oncogenic mutants lost the repressing activity. In contrast, wild-type but not mutant p53 specifically binds to and activates the promoter of the plasminogen activator inhibitor type-1 (PAI-1) gene. Interestingly, one of the p53 mutants (273his) inhibited PAI-1 promoter activity. Our results suggest that altered function of oncogenic forms of p53 may lead to altered expression of the plasminogen activators and their inhibitor(s) and thus to altered activation of the plasminogen/plasmin system during tumor progression.