Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.27.1 (RNase)
 16,360 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The relatively large size and dynamics of oligosaccharides can result in substantial shielding of functionally important areas of proteins to which they are attached, modulate the interactions of glycoconjugates with other molecules and affect the rate of processes which involve conformational changes. This review focuses on the occupancy of N-linked glycosylation sites on three enzymes, ribonuclease, plasminogen and tissue plasminogen activator. Each of these proteins occurs naturally as two populations of molecules, distinguished from each other only by the presence or absence of an oligosaccharide at one glycosylation site. The presence of an oligomannose sugar on ribonuclease (at Asn-34) alters its overall dynamics, increases its stability towards proteinases and decreases its functional activity towards double-stranded RNA. The N-linked sugar on plasminogen (at Asn-288) within kringle 3 reduces the rate of the beta- to alpha-conformational change, modulates the transport of plasminogen into the extravascular compartment, decreases plasminogen binding to U937 cells and downregulates the activation of plasminogen by both urokinase and tissue plasminogen activator. Additionally, in fibrinolysis, within a ternary complex of fibrin, plasminogen and tissue plasminogen activator, the N-linked sugar of plasminogen hinders the initial interaction with tissue plasminogen activator (i.e., it alters Km). The presence of an N-linked glycan (at Asn-184) in the kringle 2 domain of tissue plasminogen activator hinders the rearrangement of this ternary complex, decreasing the turnover rate (Kcat).
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PMID:The effects of variable glycosylation on the functional activities of ribonuclease, plasminogen and tissue plasminogen activator. 771 Oct 52

Three major components of the plasminogen activators (PA)/plasmin system are synthesized physiologically in glomeruli, and can be involved in glomerular proteolysis and extracellular matrix metabolism: tissue-type PA (tPA), urokinase (uPA) and PA inhibitor type 1 (PAI-1). To explore the possible role of a dysregulation of the plasmin protease system in the development and progression of lupus-like glomerulonephritis, we studied the expression of the renal plasmin protease components during the course of the disease, either acute, induced by IgG3 monoclonal cryoglobulins, or chronic, occurring spontaneously in three different lupus-prone mice: (NZBxNZW)F1, BXSB and MRL-lpr/lpr. RNase protection assays and in situ hybridizations revealed a marked glomerular induction of PAI-1 mRNA abundance without any significant changes in renal tPA and uPA mRNA levels in the two different types of lupus-like glomerulonephritis. The overexpression of PAI-1 mRNA occurred in parallel with a significant decrease in glomerular tPA-catalyzed enzymatic activity as determined by zymographic analysis. In addition, a concomitant increase in glomerular expression of transforming growth factor beta 1 (TGF-beta 1) mRNA was observed. The demonstration of a close correlation between the PAI-1 and TGF-beta 1 mRNA levels and the severity of lupus-like glomerular lesions suggests that a pertubation of the glomerular PA/PAI balance, resulting from a marked TGF-beta 1-mediated induction of PAI-1 gene expression, plays an important role in the progression of lupus-like glomerular lesions, leading to glomerulosclerosis.
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PMID:Induction of plasminogen activator inhibitor type 1 in murine lupus-like glomerulonephritis. 854 2

Rapid regeneration of the endothelium is a critical component of vascular wall repair because limitations of this process enhance early thrombotic and vasospastic complications, as well as late sequelae of recurrent lesion formation. We have postulated that direct activation of the thrombin receptor initiates both mitogenic and chemokinetic endothelial behavior which facilitates intimal repair. To characterize the role of the thrombin receptor in human endothelial cell (EC) proliferation and migration, we investigated the effects of both alpha-thrombin (0.5-10 U/ml) and its receptor-activating peptide (TRAP; 1-100 microM). Responses of human aortic (HAEC) and umbilical vein (HUVEC) were characterized using [3H]thymidine and 61Cr microcarrier bead assays of proliferation and migration, respectively. Expression of motility-related genes was evaluated using a ribonuclease protection assay. Thrombin exerts both of its chemokinetic and mitogenic effects differentially in human endothelial cells. Following 2 or 4 days in culture, HUVEC proliferation increased two- to threefold after exposure to thrombin, primarily in the low concentration range (P < 0.05). However, HACE proliferation was inhibited up to 50% after a 4-day incubation period (P < 0.005). These mitogenic effects, including the inhibition of aortic endothelial cell proliferation, were reproduced, in part, by thrombin receptor activation with TRAP. In contrast, thrombin stimulates migratory responses in HAEC, but not HUVEC. However, this behavior was not reproduced by TRAP. It is noteworthy that urokinase-plasminogen activator (u-PA) expression was much more strongly expressed in migrating HAEC than in the HUVEC population. Moreover, when stimulated with thrombin, u-PA gene expression was significantly augmented in HAEC. It has been speculated that an effective human thrombin receptor (HTR) antagonist may reduce the proliferation of vascular smooth muscle cells and the development of a restenotic lesion following arterial wall injury. Our data suggest that such an inhibitor will likely also accelerate intimal regeneration through a dominant effect on limiting the HTR inhibitory effect on endothelial proliferation.
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PMID:Endothelial cells exhibit differential chemokinetic and mitogenic responsiveness to alpha-thrombin. 918 72

The urokinase receptor (uPAR) influences several biological functions relevant to lung injury and repair, including proteolysis, cell migration, and adhesion. In malignant mesothelioma cells, we recently found that a posttranscriptional mechanism involving a cis-trans interaction between a uPAR mRNA sequence and a cytoplasmic uPAR mRNA binding protein (mRNABP) regulates uPAR gene expression (S. Shetty, A. Kumar, and S. Idell. Mol. Cell Biol. 17: 1075-1083, 1997). In this study, we sought to determine if uPAR expression in lung and pleural cells involves a similar posttranscriptional pathway. We first identified and characterized the uPAR mRNABP in rabbit tissues using gel mobility shift, ultraviolet (UV) cross-linking, and RNase protection assays and detected it in liver, heart, brain, spleen, colon, and lung. Phorbol 12-myristate 13-acetate, lipopolysaccharide, transforming growth factor-beta, tumor necrosis factor-alpha, or cycloheximide induced uPAR and uPAR mRNA expression in cultured rabbit pleural mesothelial cells and lung fibroblasts and concurrently reduced the uPAR mRNA-uPAR mRNABP interaction. Using conventional and affinity chromatography, we purified a 50-kDa uPAR mRNABP that selectively binds to a 51-nucleotide fragment of the uPAR coding region. This protein migrates as a monomer when analyzed by SDS-PAGE and UV cross-linking and does not possess intrinsic RNase activity in vitro. A uPAR mRNABP physicochemically and functionally similar to that of human malignant mesothelioma is constitutively expressed in the rabbit lung and other nonneoplastic tissues. In rabbit lung fibroblasts and mesothelial cells, expression of uPAR involves posttranscriptional regulation whereby the uPAR mRNABP appears to interact with a specific coding region cis-element to decrease the stability of uPAR mRNA.
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PMID:A urokinase receptor mRNA binding protein from rabbit lung fibroblasts and mesothelial cells. 960 25

During liver fibrogenesis, hepatic stellate cells (HSC) proliferate and migrate under the influence of growth factors, including platelet-derived growth factor (PDGF) and basic-fibroblast growth factor (b-FGF). The plasminogen activation system regulates extracellular matrix (ECM) catabolism and cell movement. We evaluated the expression and biological functions of the plasminogen activation system in human HSC and its interaction with PDGF and b-FGF. Urokinase-plasminogen activator receptors (u-PAR) were measured by radioligand binding, cell cross-linking, immunoassay, and RNAse protection assay. u-PA and plasminogen activator inhibitors (PAIs) expression and activities were analyzed by zymography, immunoassay, and RNase protection assay. Cell migration and proliferation, studied in Boyden chambers and by microscopic counting, were evaluated after the addition of PDGF, b-FGF, and blockade with anti-u-PA, anti-u-PAR antibodies, and antisense oligodeoxynucleotides (aODN) against u-PAR mRNA. We have shown that HSC produce u-PAR, u-PA, and PAI-1. PDGF and b-FGF up-regulate u-PA and u-PAR, but not PAI-1, and exogenous addition of u-PA stimulates HSC proliferation, chemotaxis, and chemoinvasion. Inhibition of u-PA/u-PAR with antibodies against u-PA or u-PAR and with u-PAR aODN inhibit the proliferative, chemotactic, and chemoinvasive activity of PDGF and b-FGF. These findings indicate that u-PA and u-PAR are required for the mitogenic and chemoinvasive activity of PDGF and b-FGF on HSC.
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PMID:Functions of the fibrinolytic system in human Ito cells and its control by basic fibroblast and platelet-derived growth factor. 1005 91

The urokinase-type plasminogen activator (uPA) interacts with its receptor (uPAR) to promote proteolysis as well as cell proliferation and migration. These functions contribute to the pathogenesis of neoplastic growth and invasiveness. Expression of uPAR in tumor extracts also inversely correlates with prognosis in many forms of cancer. In this study, we sought to determine if differences in uPAR expression were distinguishable between cultured human lung carcinoma and malignant mesothelioma subtypes. We also sought to determine if, as in malignant mesothelioma cells, uPAR expression is regulated at the posttranscriptional level in cultured malignant lung carcinoma cells. Using 125I-uPA binding and ligand blotting techniques, uPAR was expressed by phenotypically diverse lung carcinoma cell lines, including the H460, H157 and H1395 non-small cell lines and the H146 small cell lung carcinoma line. Increased uPAR expression was also detected in spindle-shaped (M33K) and epithelioid (M9K and MS-1) malignant mesothelioma cells. Selected mediators, including TGF-beta, TNF-alpha, LPS and PMA, uniformly enhanced uPAR expression in each of the tumor cell lines. Steady state uPAR mRNA expression was determined by RNase protection assay and correlated directly with the changes in cell surface uPAR expression. By gel mobility shift and UV-cross linking assays, a uPAR mRNA binding protein (uPAR mRNABp) implicated in the posttranscriptional control of message stability, was identified in each of the cell lines. Expression of uPAR and its message in cultured lung carcinoma and malignant mesothelioma cells is similarly influenced by effectors present in the tumor microenvironment. Regulation of the uPAR message occurs at the posttranscriptional level in cultured small and non-small cell lung carcinoma cells as well as spindle-shaped and fibrous malignant mesothelioma cell lines. Posttranscriptional regulation of uPAR in all these cells involves the interaction of the uPAR mRNABp with uPAR mRNA, which promotes uPAR mRNA destabilization.
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PMID:Posttranscriptional regulation of urokinase receptor gene expression in human lung carcinoma and mesothelioma cells in vitro. 1054 67

Components of the extracellular matrix take part in tissue rebuilding as well as activating surface-bound growth factors. In the present study, expression and selected activities of urokinase-type plasminogen activator (uPA), matrix metalloproteinases (MMPs), their inhibitors (plasminogen activator inhibitor 1 (PAI-1) and tissue inhibitors of metalloproteinases (TIMPs)) were examined in bovine oviducts by RT--PCR, ribonuclease protection assay and activity assays. A high content of mRNA encoding for uPA was detected before ovulation with a three-fold decrease after ovulation. In contrast, PAI-1 expression appeared to be stable during the oestrous cycle. Oviductal flushings produced caseinolytic zones in zymograms containing plasminogen at approximately 50 kDa and 28 kDa. An activity assay for uPA showed highest net activity during the early to mid-luteal phase. Increased TIMP-1 and MMP-2 mRNA concentrations were found around the time of ovulation compared with the luteal phase. In contrast, MMP-1 mRNA transcripts were enriched during the early to mid-luteal phase. Gelatin zymograms detected a 70--72 kDa protease activity showing an oestrous cycle-dependent activity with highest activity before ovulation. Reverse zymography detecting TIMPs revealed proteins between 21 kDa and 24 kDa. Only for the smallest (21 kDa) protein were amounts increased around the time of ovulation compared with the luteal phase. The observation that several extracellular matrix components were regulated distinctly in bovine oviducts indicates that local interactions between these components, growth factors, gametes and the embryo are possible and may influence fertilization and early embryonic development.
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PMID:Differential expression of extracellular matrix components in the bovine oviduct during the oestrous cycle. 1142 36

We previously demonstrated doxorubicin-induced urokinase expression in human H69 SCLC cells by the microarray technique using Human Cancer CHIP version 2 (Takara Shuzo, Kyoto, Japan), in which 425 human cancer-related genes were spotted on glass plates (Kiguchi et al., Int J Cancer 2001;93:792-7). Microarray analysis also revealed significant induction of IL-8, a member of the CXC chemokines. We have, therefore, extended the observation by testing the effects of doxorubicin on expression of the chemokine family and provide here definitive evidence that doxorubicin induces IL-8 and MCP-1, one of the CC chemokines, at least in 2 human SCLC cells, H69 and SBC-1. IL-8 antigen levels, measured by ELISA, were markedly increased in both H69 and SBC-1 conditioned media after doxorubicin treatment, in parallel with mRNA levels; and this was dependent on the dose of doxorubicin. The ribonuclease protection assay, using a multiprobe template set for human chemokines, revealed induction of not only IL-8 but also MCP-1 in doxorubicin-treated H69 cells. MCP-1 antigen levels increased approximately 100-fold in doxorubicin-treated H69 cells. RT-PCR using specific primers for MCP-1 suggested that doxorubicin also induced MCP-1 expression in SBC-1 and SBC-3 SCLC cells. Futhermore, CAT analysis using IL-8 promoter implicated the PEA3 transcriptional factor, whose binding site was located immediately upstream of the AP-1 and NF-kappaB binding sites. Thus, it is suggested that doxorubicin induces IL-8 and MCP-1 chemokines in human SCLC cells by activating gene expression, in which at least PEA3 is involved. IL-8 and MCP-1 are major chemoattractants for neutrophils and monocytes/macrophages, respectively; therefore, extensive induction of IL-8 and MCP-1 may provoke the interaction between inflammatory/immune cells and tumor cells under doxorubicin stimulation and influence many aspects of tumor cell biology.
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PMID:Induction of IL-8 and monoclyte chemoattractant protein-1 by doxorubicin in human small cell lung carcinoma cells. 1247 21

The accumulation of fibrillar amyloid-beta protein (A beta) in cerebral blood vessels, a condition known as cerebral amyloid angiopathy (CAA), is a key pathological feature of Alzheimer's disease and certain related disorders and is intimately associated with cerebrovascular cell death both in vivo and in vitro. Moreover, severe CAA leads to loss of vessel wall integrity and cerebral hemorrhage. Although the basis for these latter pathological consequences in CAA remains unresolved alterations in local proteolytic mechanisms may be involved. Here we show that pathogenic forms of A beta stimulate the expression of plasminogen activator activity in cultured human cerebrovascular smooth muscle (HCSM) cells, an in vitro model of CAA. RNase protection assays and plasminogen zymography showed that urokinase-type plasminogen activator (uPA) was responsible for this activity. There was preferential accumulation of uPA on the HCSM cell surface that was mediated through a concomitant increase in expression of the uPA receptor. In the presence of plasminogen there was robust degradation of A beta that was added to the HCSM cells resulting in restoration of cell viability. This suggests that increased expression of uPA may initially serve as a protective mechanism leading to localized degradation and clearance of the pathogenic stimulus A beta. On the other hand, chronic expression of uPA and plasminogen activation led to a profound loss of HCSM cell attachment. This suggests that a similar prolonged effect in vivo in the cerebral vessel wall may contribute to loss of integrity and cerebral hemorrhage in CAA.
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PMID:Amyloid beta-protein stimulates the expression of urokinase-type plasminogen activator (uPA) and its receptor (uPAR) in human cerebrovascular smooth muscle cells. 1275 71