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At least 145 records · Page 8Linked to original sources
PubMed1976

SV 40 related papova-viruses in human meningiomas.

Human meningiomas show characteristic chromosome aberrations very similar to those reported in human cell cultures experimentally transformed by Simian virus 40 (SV 40). Three out of eight meningiomas tested showed SV 40 specific tumor antigen but no virus capsid antigen. Experiments to rescue virus were successfully performed. Electron microscopic studies of these cell cultures revealed cytoplasmic inclusions containing virus particles which corresponded in size and morphology to Papova viruses.

Antigens, Viral↗
PubMed1990

A comparison of BKV, JCV, and SV 40 transcriptional enhancers in primate cells. Application of the two-phase partition assay for chloramphenicol acetyl transferase (CAT).

The activities of the transcriptional enhancers of the prototype human polyomaviruses, BKV (Dun) and JCV (MAD-1), were compared with that of the rhesus virus SV 40 in Old World African green monkey kidney cells (CV-1) and in New World owl monkey kidney cells (OMK). Enhancer activities were tested in CAT-expression plasmids. CAT activity in transfected cell extracts were measured by the novel two-phase partition assay. The activities of the BKV and JCV enhancers were 45% and 20% that of SV 40, respectively, in CV-1 cells. The effectiveness of each viral enhancer was less in OMK cells than in CV-1 cells, as would be expected if the viruses co-evolved with their natural hosts. In CV-1 cells, the BKV enhancer was more active than that of JCV, but in OMK cells the reverse was true. This result is significant in view of the fact that JCV, but not BKV, is oncogenic in owl monkeys.

Animals↗
PubMed1999

Genomic insertion of the SV-40 large T oncogene in normal adult human trabecular osteoblastic cells induces cell growth without loss of the differentiated phenotype.

In the present study, we established a new adult human trabecular osteoblastic (AHTO) cell line, immortalized by SV-40 Large T (LT) oncogene. From seven proliferative colonies identified, we selected clone 7 with high alkaline phosphatase (ALP) activity for further analysis. AHTO-7 cells were able to grow for at least 8 months and 25 passages, with a doubling time of about 22 hours. Immunocytochemistry staining and RT-PCR analysis indicated that the extended life-span of AHTO-7 cells results in genomic insertion of SV-40 LT oncogene. The cells responded to PTH and PGE2 in terms of cAMP accumulation. The time course study, in the presence of 10(-8) M vitamin D3 (vit D3) showed a marked increase (fourfold) in ALP activity with a peak at day 3. Furthermore, in the presence of ascorbic acid (50 microg/ml) and inorganic phosphate (3 mM), AHTO-7 cells produced abundant calcified extracellular matrix, as examined by the von Kossa staining after 2 weeks of culture. Molecular analysis of mRNAs for phenotypic osteoblast markers at day 15 showed the expression of ALP, osteocalcin (OC), and collagen type I (Col I) mRNAs constitutively. Col I expression was inhibited by vit D3 and dexamethasone treatment. In contrast, treatment with vit D3 induced a marked increase of ALP and OC transcripts. Therefore, the immortalized AHTO-7 cells express osteoblast markers that are induced by calciotropic hormones, and constitute a suitable model for identifying specific osteoblastic genes and their regulation during human osteoblast differentiation.

Aged↗
PubMed2002

Molecular and biochemical characterization of a novel two-component signal transduction system, amrA- amkA, involved in rifamycin SV production in Amycolatopsis mediterranei U32.

Two-component and phosphorelay signal transduction systems are the major means by which bacteria recognize and respond to a variety of environmental stimuli. Although several model systems, including sporulation in Bacillus subtilis and chemotaxis in Escherichia coli, have been extensively studied, the two-component signal transduction systems in industrially important actinomycetes are not well studied. We report the molecular and biochemical characterization of a novel two-component signal system, amrA-amkA,from the rifamycin-SV-producing Amycolatopsis mediterranei U32. The deduced sequences of amkAand amrA contain all the structural features that are highly conserved in the typical bacterial histidine kinases and response regulators, respectively. BLAST analyses showed that AmrA and AmkA displayed high similarities to AfsQ1/AfsQ2 of Streptomyces coelicolor and MtrA/MtrB of Mycobacterium tuberculosis. The amrAand amkA genes were over-expressed and the gene products were purified from E. coli. Biochemical studies showed that AmkA is able to autophosphorylate, supporting its functional assignment as a histidine kinase. That AmrA functions as the cognate response regulator for histidine kinase AmkA was demonstrated by in vitro phosphotransfer from [gamma-(32)P]ATP-labeled AmkA to AmrA. Rifamycin SV production was also decreased by 10-20% in amrAor amkA gene disruption mutants under the tested condition. Although the detailed regulatory mechanism is still unknown, this is the first report regarding the involvement of two-component signal systems in rifamycin biosynthesis in the genus Amycolatopsis.

Actinomycetales↗
PubMed2000

Expression in Escherichia coli, purification and kinetic analysis of the aspartokinase and aspartate semialdehyde dehydrogenase from the rifamycin SV-producing Amycolatopsis mediterranei U32.

The operon encoding aspartokinase and aspartate semialdehyde dehydrogenase was cloned and sequenced from rifamycin-SV-producing Amycolatopsis mediterranei U32 previously. In the present work, these two genes were introduced into the auxotrophic Escherichia coli strain CGSC5074 (ask-) and E. coli X6118 (asd-), respectively. The A. mediterranei U32 asparto-kinase and aspartate semialdehyde dehydrogenase genes can be functionally expressed in E. coli and the gene products are able to substitute for the E. coli enzymes. Histidine-tagged aspartokinase and aspartate semialdehyde dehydrogenase were partially purified from E. coli cellular extracts and their kinetic characteristics were studied. Both aspartokinase and aspartate semialdehyde dehydrogenase showed typical Michaelis-Menten type substrate saturation patterns. Aspartokinase has Km values of 3.4 mM for aspartate and 2.3 mM for ATP, while aspartate semialdehyde dehydrogenase has Km values of 1.25 mM for DL-aspartate semialdehyde and 0.73 mM for NADP, respectively. Aspartokinase was inhibited by L-threonine, L-lysine, and L-methionine, but not by L-isoleucine and diaminopimelate. Aspartate semialdehyde dehydrogenase was not inhibited by any of the end-product amino acids at a concentration of less than 5 mM. Hill plot analysis suggested that asparto-kinase was subject to allosteric control by L-threonine. Repression of both aspartokinase and aspartate semi-aldehyde dehydrogenase gene transcription in A. mediterranei U32 by L-lysine, L-methionine, L-threonine, and L-isoleucine were found. The network of regulation of aspartokinase and aspartate semialdehyde dehydrogenase in rifamycin SV-producing A. mediterranei U32 is presented.

Actinomycetales↗
PubMed2004

A novel two-component system amrB-amkB involved in the regulation of central carbohydrate metabolism in rifamycin SV-producing Amycolatopsis mediterranei U32.

A novel two-component signal transduction system amrB-amkB was cloned from rifamycin SV-producing Amycolatopsis mediterranei U32, and their biochemical functions as a response regulator and a histidine protein kinase, respectively, were proven. The amrB disruption mutant was generated by insertional inactivation with the aparmycin resistance gene. The metabolic response to the absence of amrB gene was determined by a biochemical profiling technique in which the concentration changes of metabolic intermediates were measured by gas chromatography with time-of-flight mass spectrometry (GC/TOF-MS). Although the phenotype analyses of the amrB gene disruption mutant showed no significant change with respect to rifamycin SV production and morphological differentiation, the global metabolomic analyses found the concentration levels of some key intermediates in the TCA cycle and glycolysis pathway were affected by an amrB gene disruption event. The primary results suggested that amrB-amkB genes might be involved in the regulation of central carbohydrate metabolism in A. mediterranei U32.

Actinobacteria↗
PubMed1985

Lowered level of translatable messenger RNAs for manganese superoxide dismutase in human fibroblasts transformed by SV 40.

The activity of manganese superoxide dismutase (MnSOD) revealed by specific staining after gel electrophoresis of cell extracts, is decreased in human fibroblasts transformed by SV40. The decrease in enzyme activity is attributable to decreased amount of enzyme protein as determined by radial immunodiffusion. Total fibroblast RNAs were translated in the presence of (35S) methionine in a cell-free translation system and the neo synthesized proteins submitted to immunoprecipitation with an anti MnSOD antiserum. Gel electrophoresis of the immunoprecipitated material followed by fluorography shows that MnSOD is translated as a peptide which is 2000 daltons larger than the mature enzyme subunit. This precursor (pre-MnSOD) is processed in vitro to mature MnSOD by the action of an isolated mitochondrial preparation. Levels of translatable MnSOD mRNA in normal and SV 40 transformed cells were compared in terms of the radioactivities incorporated into pre MnSOD bands. The results indicate that the decreased amount of MnSOD in SV 40 transformed fibroblasts is due to a decreased level of translatable mRNA for MnSOD.

Cell Transformation, Viral↗
PubMed1990

In vivo and in vitro inhibition of platelet aggregation by SV-IV, a major protein secreted from the rat seminal vesicle epithelium.

In summary, the present study documents that platelet aggregation triggered by thrombin, ADP, collagen and PAF both in vivo and in vitro, was prevented by SV-IV in a dose-dependent manner. Only platelet aggregation by AA was not affected by the protein, thus suggesting a possible involvement of PLA2 inhibition in the molecular mechanism at the basis of SV-IV anti-thrombotic effect.

Animals↗
PubMed1987

Synthetic peptides containing a region of SV 40 large T-antigen involved in nuclear localization direct the transport of proteins into the nucleus.

We studied the mechanism of transport of proteins into the nucleus using synthetic peptides containing the nuclear location signal sequence of Simian virus 40 (SV 40) large T-antigen. When chick erythrocytes containing a synthetic large T-antigen nuclear translocation signal were fused with SV 40-transformed human fibroblasts, the migration of native large T-antigen into the chick nuclei was suppressed. Migration of proteins detected by human specific antinuclear autoimmune antibody was not blocked. An analog of the nuclear location signal peptide did not inhibit entry of large T-antigen into the chick nuclei. This result suggests that the peptide blocked the migration of only native large T-antigen into the nucleus, and that the signal of the majority of nuclear proteins for nuclear transport is not the same as that of the large T-antigen. The synthetic peptide was conjugated chemically with bovine serum albumin (BSA) and introduced into the cytoplasm of cultured human cells by red blood cell ghost-mediated microinjection. The BSA-synthetic peptide conjugate was found predominantly in the nucleus within 2 h after its introduction into the cells. BSA conjugated with the cross-linking reagent alone was not transported into the nucleus. Acetylated synthetic peptide was not effective in promoting nuclear localization of BSA. Mild trypsin treatment of the BSA-synthetic peptide conjugate suppressed nuclear localization. Conjugates of the synthetic peptide with phycoerythrin (Mr about 150 kD) and with secretory IgA (Mr about 380 kD) were both found in the nucleus very shortly after their introduction into the cytoplasm. These results suggest that the synthetic peptide containing the nuclear location signal sequence provides exogenous proteins with the ability to migrate into the nucleus. But, since a conjugate of the synthetic peptide with IgM (Mr about 940 kD) did not migrate into the nucleus after its microinjection, there may be a size limit in nuclear transport of conjugated proteins.

Amino Acid Sequence↗
PubMed1995

Transforming growth factor-beta 1 downregulates dexamethasone-induced tetranectin gene expression during the in vitro mineralization of the human osteoblastic cell line SV-HFO.

In the present study, we examined the regulation of tetranectin gene expression using a human osteoblastic cell line, SV-HFO, that undergoes mineralization upon treatment with dexamethasone. We found that the expression of tetranectin and alkaline phosphatase mRNA was induced by dexamethasone treatment as evidenced by Northern blotting. When transforming growth factor-beta 1 (TGF-beta 1) was added together with dexamethasone to the SV-HFO cell cultures, the mineralization process was markedly suppressed and the expression of tetra nectin and alkaline phosphatase was downregulated in a dose-dependent manner. These results demonstrate that the expression of tetranectin in these osteoblastic cells is regulated by dexamethasone and TGF-beta 1 and that tetranectin expression is tightly linked to the process of mineralization.

Biomarkers, Tumor↗
PubMed1995

Enantiomeric resolution using the macrocyclic antibiotics rifamycin B and rifamycin SV as chiral selectors for capillary electrophoresis.

Rifamycin B and rifamycin SV belong to the class of macrocyclic antibiotics known as ansamycins. These macrocyclic antibiotics were used as chiral selectors in capillary electrophoresis to enantioselectively resolve a number of chiral compounds. They contain groups capable of providing the types of multiple interactions necessary to achieve chiral recognition between enantiomers. In fact, they appear to be complimentary in the types of compounds they can enantiomerically resolve. Rifamycin B is shown to be enantioselective towards positively charged compounds, while rifamycin SV was enantioselective towards negatively charged solutes. The choice of wavelength for detection significantly affects sensitivity. Monitoring one of the wavelengths which coincide with the absorption minima of the chiral selector enhances sensitivity. Resolution is enhanced by keeping the amount of analyte injected on column as low as possible and it is demonstrated that it is possible to detect as little as 0.1% of one enantiomer in the presence of the other enantiomer using indirect detection.

Anti-Bacterial Agents↗
PubMed1982

The effect of ribavirin and rifamycin SV on age-dependent changes of the immune system during the adult life of SJL mice.

Ribavirin and Rifamycin SV, given from birth to adult life, arrest the loss of suppressor capacity, normally occurring in older SJL mice. The two drugs differ in their effect on Th-2-type help for the indirect plaque-forming response, i.e. for help which is independent of the carrier-hapten bridge. This type of help normally increases with age. Ribavirin treatment inhibits development of Th-2-type of help; Rifamycin SV does not interfere with the development of this type of help. Neither of the two drugs had an effect on the ability of SJL mice, not treated with aggregate-freed RGG, to make a plaque-forming response to aggregated RGG.

Aging↗
PubMed1996

Transformation of liver by SV-40 T-antigen in transgenic mice is unaffected by metallothionein.

Transgenic mice expressing excess metallothionein-I and SV-40 T-antigen were generated to test the hypothesis that metallothionein may influence the rate of neoplastic transformation induced by T-antigen within the liver. The livers of the double transgenic mice grew at the same rate (to 32% body weight), had similar morphological and histological appearance, had similar chromosomal instability, and released identical amounts of serine and alanine aminotransferases into the blood as mice bearing SV-40 T-antigen alone, despite the fact that metallothionein levels were elevated five- to ten-fold. We conclude that elevated levels of metallothionein-I do not influence either the initial hyperplasia or the subsequent neoplastic transformation that is induced by T-antigen, which is thought to act by sequestering the P53 and retinoblastoma gene products.

Alanine Transaminase↗
PubMed2005

Identification of cell surface marker candidates on SV-T2 cells using DNA microarray on DLC-coated glass.

We analyzed gene expression profiles of normal mouse fibroblast BALB/c 3T3 cells and its SV40 transformant SV-T2 cells using our originally developed cell surface marker DNA microarray, which is prepared on a diamond-like carbon-coated glass. As a result, CD62L and IL-6 receptor alpha gene expressions were upregulated in SV-T2 and were thought to be candidates for call surface markers of the cells. The result of microarray analysis was validated by real-time quantitative PCR immunohistochemistry and biological assays. These data show that our cell surface marker DNA microarray should be useful in finding the candidates of cell type-specific surface markers.

Animals↗
PubMed2000

Inhibition of antithrombin by protein SV-IV normalizes the coagulation of hemophilic blood.

The aim of the study was to evaluate the effect of the protein Seminal Vesicle Protein No. 4 (SV-IV), a potent inhibitor of antithrombin III (antithrombin), on the coagulation of blood obtained from patients affected by hemophilia A. In the coagulating blood of these patients, the antithrombin/thrombin ratio was found to be markedly higher (about 44) than in normal individuals (about 4. 4). This high ratio was related to the low efficiency of thrombin-generating reactions induced by the factor VIII deficiency and to the high levels of free (not bound to serine proteases) antithrombin present in the hemophilic serum (antithrombin concentration was the same in normal and hemophilic plasma). The elevated concentration of free antithrombin in hemophiliacs was primarily a consequence of a reduced consumption caused by the scarce availability in the hemophilic serum of factors Xa and IIa, which are serine proteases possessing strong binding affinity for antithrombin. Addition of SV-IV to coagulating hemophilic blood reduced markedly the serum antithrombin and thrombin-antithrombin complexes, normalizing, as a consequence, the clotting time and other coagulation parameters. Similar results were obtained by using appropriate concentration of factor VIII.

Antithrombin III↗
PubMed2002

KCO1 is a component of the slow-vacuolar (SV) ion channel.

The Arabidopsis double pore K+ channel KCO1 was fused to green fluorescent protein and expressed in tobacco protoplasts. Microscopic analysis revealed a bright green fluorescence at the vacuolar membrane. RT-PCR experiments showed that KCO1 is expressed in the mesophyll. Vacuoles from Arabidopsis wild-type and kco1 knockout plants were isolated for patch-clamp analyses. Currents mediated by slow-activating vacuolar (SV) channels of mesophyll cell vacuoles were significantly smaller in kco1 plants compared to the wild-type. This shows that KCO1 is involved in the formation of SV channels.

Arabidopsis↗
PubMed1996

Phase-Dependent effects of transforming growth factor beta 1 on osteoblastic markers of human osteoblastic cell line sV-HFO during mineralization.

A human osteoblastic cell line (SV-HFO) established in our laboratory expresses osteoblastic markers, including mineralization in vitro, in response to differentiation-inducing agents such as dexamethasone. In this study, we examined the effects of transforming growth factor beta 1 (TGF-beta 1) on the mineralization of SV-HFO cells and show that TGF-beta 1 inhibited the mineralization of the cells via down regulation of tetranectin and alkaline phosphatase without influencing other osteoblastic markers. To examine precisely the effects of TGF-beta 1 on the process of mineralization, we tentatively divided the whole process of mineralization into four phases: induced ALP activity (days 0-5), maximal ALP activity (days 5-10), early mineralization (days 10-15), and progressive mineralization (days 15-20). These inhibitory effects of TGF-beta 1 on the expression of tetranectin and alkaline phosphatase, like that on mineralization, were observed only when TGF-beta 1 was applied in the early phase of the process of mineralization. On the other hand, the other osteoblastic markers were not influenced by treatment with TGF-beta 1. These results suggest that TGF-beta 1 may inhibit mineralization of osteoblasts by the downregulation of tetranectin and alkaline phosphatase expression in the early phase. Thus, TGF-beta 1 has phase-dependent effects on a human osteoblastic cell line during the process of mineralization.

Alkaline Phosphatase↗