Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A type II DNA topoisomerase, topoIImt, was shown previously to be associated with the kinetoplast DNA of the trypanosomatid Crithidia fasciculata. The gene encoding this kinetoplast-associated topoisomerase has been cloned by immunological screening of a Crithidia genomic expression library with monoclonal antibodies raised against the purified enzyme. The gene CfaTOP2 is a single copy gene and is expressed as a 4.8-kb polyadenylated transcript. The nucleotide sequence of CfaTOP2 has been determined and encodes a predicted polypeptide of 1239 amino acids with a molecular mass of 138,445. The identification of the cloned gene is supported by immunoblot analysis of the beta-galactosidase-CfaTOP2 fusion protein expressed in Escherichia coli and by analysis of tryptic peptide sequences derived from purified topoIImt. CfaTOP2 shares significant homology with nuclear type II DNA topoisomerases of other eukaryotes suggesting that in Crithidia both nuclear and mitochondrial forms of topoisomerase II are encoded by the same gene.
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PMID:Molecular cloning and expression of the gene encoding the kinetoplast-associated type II DNA topoisomerase of Crithidia fasciculata. 131 98

A group of 191 patients with systemic scleroderma and 12 patients with silicosis-associated scleroderma were investigated for connective tissue turnover. The serum levels of type III collagen aminopropeptide (P-III-P), the laminin PI (Lam PI) fragment and the acid lysosomal beta-galactosidase (beta-Gal) were determined by specific radioimmunoassays and spectrofluorometry, respectively. Increased levels of type III collagen aminopropeptide strongly correlated with enhanced activity of beta-galactosidase. Both parameters correlated with the clinical course in idiopathic systemic scleroderma and in silicosis-associated scleroderma. Serum levels of Lam PI were also found to be elevated in both groups, although there was no correlation with the severity of the disease. Autoantibodies directed against the DNA topoisomerase Scl-70 and against centromeric proteins were found in a similar range in patients with idiopathic systemic and silicosis-associated scleroderma. These results suggest that P-III-P, Lam PI and beta-Gal are useful serological markers of fibrotic activity and demonstrate similarities between idiopathic systemic scleroderma and scleroderma associated with silica-dust exposure.
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PMID:Type III collagen aminopropeptide and laminin P1 levels in serum of patients with silicosis-associated and idiopathic systemic scleroderma. 211 68

Enoxacin inhibits growth of Escherichia coli K12 strains primarily by binding to the GyrA subunit of DNA gyrase (topoisomerase II); strains with gyrA, but not gyrB, mutations are less susceptible to the bactericidal effects of this agent. In sensitive strains, enoxacin completely inhibits DNA synthesis within 5 min and produces drug-gyrase-DNA complexes at numerous sites throughout the E. coli chromosome, as shown by the formation of linear DNA molecules after detergent treatment. Enoxacin, even at subminimal inhibitory concentrations, induces the bacterial SOS system, even in partially resistant gyrA strains. This drug also inhibits the induced expression of the lacZ encoded beta-galactosidase, regardless of whether this gene is located on the chromosome, a low copy number F' plasmid or high copy number Col E1 related plasmids. This inhibition of gene expression at subminimal inhibitory concentrations is likely to be a factor, in addition to gyrase inhibition, in the elimination of Col E1 plasmids and to the reduction in R plasmid conjugal transfer. Enoxacin enhances the bactericidal effects of kanamycin in both in-vitro and in-vivo models, suggesting that this quinolone may be effective in the treatment of infections due to strains resistant to antibacterials as a consequence of plasmid encoded resistance determinants.
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PMID:Alteration of bacterial DNA structure, gene expression, and plasmid encoded antibiotic resistance following exposure to enoxacin. 283 13

Mutations in top, the structural gene for Escherichia coli DNA topoisomerase I, have been identified and mapped at 28 min on the chromosome, near cysB. Strains carrying deletions of the top gene are viable. The top mutations, however, do exert pleiotropic effects on transcription and transposition. Mutants lacking DNA topoisomerase I have a more rapid rate of induction and a higher level of catabolite-sensitive enzymes including tryptophanase and beta-galactosidase. This general activation of transcription by top mutations can be attributed to an increase in the negative superhelicity of the DNA in vivo when the topoisomerase activity is abolished. The frequency of transposition of Tn5, a transposon carrying kanamycin resistance, is decreased by a factor of 40 or more in top mutants. A direct or indirect role of the topoisomerase in transposition is discussed. The transposition frequency of Tn3, however, is not dependent on top. Based on the studies of the E. coli top mutants, it appears that the supX gene, which was originally studied in Salmonella typhimurium [Dubnau, E. & Margolin, P. (1972) Mol. Gen. Genet. 117, 91-112] is likely to be the structural gene for DNA topoisomerase I.
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PMID:Mutations in the gene coding for Escherichia coli DNA topoisomerase I affect transcription and transposition. 626 7

To study the involvement of DNA topoisomerase (topo) II on nonhomologous (illegitimate) recombination, we examined the effect of topo II inhibitors on random integration of exogenous vectors into human chromosomes. We transfected human cell lines PA1, HeLa and EJ-1 with linearized plasmid pSV2neo by electroporation, treated with topo II inhibitors and determined the frequency of Geneticin-resistant (G418r) colonies. We found that three topo II inhibitors, etoposide (VP-16), ICRF-193 and amsacrine (m-AMSA), greatly enhanced the frequency of G418r colonies. These effects were maximally expressed by as little as 12 hrs treatment with the drugs. Similar enhancements were found with different vectors (closed-circular and linear), different cell types, or by different transfection methods (calcium precipitation and lipofection). In contrast, the inhibitor treatments did not affect the transient expression of chloramphenicol acetyltransferase and beta-galactosidase activity following transfection with pSV2CAT and pCH110, respectively. Southern blot analysis revealed that the integration pattern of transfected pSV2neo into PA1 chromosomes was random and not characteristic for each inhibitor. These results suggest that topo II inhibitors directly act at a nonhomologous recombination reaction, promoting the integration process of transfected vectors into human chromosomes. We discuss the enhancement mechanism with a special emphasis on DNA strand breaks induced by the inhibitors.
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PMID:DNA topoisomerase II inhibitors enhance random integration of transfected vectors into human chromosomes. 900 Jan 72

The ability of recombinant adeno-associated virus (AAV) vectors to integrate into the host genome and to transduce nondividing cells makes them attractive as vehicles for gene delivery. In this study, we assessed the ability of several AAV vectors to transduce airway cells in rabbits by measuring marker gene expression. AAV vectors that transferred either a beta-galactosidase (beta-gal) or a human placental alkaline phosphatase (AP) gene were delivered to one lobe of the rabbit lung by use of a balloon catheter placed under fluoroscopic guidance. We observed vector-encoded beta-gal or AP staining almost exclusively in the epithelial and smooth muscle cells in the bronchus at the region of balloon placement. The overall efficiency of transduction in the balloon-treated bronchial epithelium was low but reached 20% in some areas. The majority of the staining was in ciliated cells but was also observed in basal cells and airway smooth muscle cells. We observed an 80-fold decrease in marker-positive epithelial cells during the 60-day period after vector infusion, whereas the number of marker-positive smooth muscle cells stayed constant. Although treatment with the topoisomerase inhibitor etoposide dramatically enhanced AAV transduction in primary airway epithelial cells in culture, treatment of rabbits did not improve transduction rates in the airway. Vector readministration failed to produce additional transduction events, which correlated with the appearance of neutralizing antibodies. These results indicate that both readministration and immune modulation will be required in the use of AAV vectors for gene therapy to the airway epithelium.
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PMID:Transduction by adeno-associated virus vectors in the rabbit airway: efficiency, persistence, and readministration. 922 83

We have analyzed the subcellular distribution of the beta isoform of human topoisomerase II using both isoform-specific antisera and an epitope-tagging approach. Previous immunocytochemical studies have yielded differing results with one reporting this isoform to be predominantly nucleolar. Later studies seem to refute this finding, as do our results with isoform-specific antisera reported here. Epitope tagging minimizes potential complications arising from the use of anti-topoisomerase II antisera that may recognize epitopes that are modified or masked in vivo and could lead to misleading results in immunocytochemical studies. A second strength of this approach is that it allowed a comparison with similarly tagged control proteins (derived from the nucleolar transcription factor UBF) that were known to localize unambiguously to the cytoplasmic, nucleoplasmic, or nucleolar compartments. We report that the C-terminal domain of topoisomerase IIbeta fused to a beta-galactosidase tag localizes to the nucleus (but not the nucleolar compartment) and that this is indistinguishable from the localization of native topoisomerase IIbeta detected by isoform-specific antisera. Further analysis revealed that the nuclear localization determinant lies within the 116-residue C-terminal tail of human topoisomerase IIbeta.
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PMID:Nuclear distribution of human DNA topoisomerase IIbeta: a nuclear targeting signal resides in the 116-residue C-terminal tail. 974 83

Inhibitors of DNA topoisomerases I and II induced arrest in cell division in normal human fibroblasts depending on cell divisions. Arrested cells showed morphology similar to those of normally senesced cells and strongly induced senescence-associated beta-galactosidase. In these cells, p16ink4a was upregulated, whereas p21waf1 or p53 was not altered. Upon removal of the inhibitors, the cells resumed growth but their cumulative population doublings were reduced dose dependently. Accelerated telomere shortening was not observed in the arrested cells. These results suggest that DNA topoisomerase inhibitors are efficient and reversible inducers of premature senescence in normal human cells.
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PMID:DNA topoisomerase inhibitors induce reversible senescence in normal human fibroblasts. 991 85

Recently, it has been demonstrated that Etoposide, a topoisomerase II inhibitor, can induce apoptosis in MDM2-overexpressing tumor cells by inhibition of MDM2 synthesis. We have previously shown that E2F-1 overexpression induces apoptosis of MDM2-overexpressing sarcoma cells, which is related to the inhibition of MDM2 expression. Therefore, the present study was designed to investigate the in vitro and in vivo effect of combined treatment of adenovirus-mediated E2F-1 and topoisomerase II inhibitors on the growth inhibition and apoptosis in human sarcoma cells. Two human sarcoma cell lines, OsACL and U2OS, were treated with topoisomerase II inhibitors (Etoposide and Adriamycin), alone or in combination with adenoviral vectors expressing beta-galactosidase (Ad-LacZ) or E2F-1 (Ad-E2F-1). E2F-1 expression was confirmed by Western blot analysis. Ad-E2F-1 gene transfer at a low dose (multiplicity of infection, 2) markedly increased the sensitivity of human sarcoma cells to topoisomerase II inhibitor treatment. This cooperative effect of E2F-1 and topoisomerase II inhibitors was less marked in SAOS-2 cells (p53 and pRb null). Topoisomerase II inhibitors also cooperated with E2F-1 overexpression to enhance tumor cell killing in an in vivo model using xenografts in nude mice. When combined with Adriamycin or Etoposide, E2F-1 adenovirus therapy resulted in approximately 95% and 85% decrease in tumor size, respectively, compared to controls (P<.05). These results suggest a new chemosensitization strategy that is effective in MDM2-overexpressing tumors and may have clinical utility.
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PMID:Additive effect of adenovirus-mediated E2F-1 gene transfer and topoisomerase II inhibitors on apoptosis in human osteosarcoma cells. 1139 76

Melanoma has proven to be resistant to conventional chemotherapy; however,the mechanism of chemoresistance is still unclear. Recent reports show that the transcription factor, E2F-1, may play a role in mediating cytotoxicity of certain chemotherapeutic agents. We have shown in a previous study that adenovirus-mediated overexpression of E2F-1 can efficiently induce apoptosis in melanoma cells. In the present study, the effect of E2F-1 expression on drug sensitivity of melanoma cells was evaluated. Two human melanoma cell lines, SK-MEL-28 and SK-MEL-2, were treated with drugs (etoposide, Adriamycin, roscovitine, cisplatin, 5-fluorouracil, or cycloheximide), alone or in combination with adenoviral vectors expressing beta-galactosidase (Ad-LacZ) or E2F-1 (Ad-E2F-1) at a multiplicity of infection of 1 in vitro. E2F-1 expression was confirmed by Western blot analysis. Sublethal concentrations of each drug alone or infection with Ad-E2F-1 alone produced <5% apoptosis by 3 days posttreatment. Conversely, cotreatment with Ad-E2F-1 and low concentrations of etoposide or Adriamycin markedly sensitized melanoma cells to apoptotic cell death. A slight enhancement of the cytotoxicity of roscovitine was demonstrated in combination with E2F-1 overexpression, but not to cisplatin, 5-fluorouracil, or cycloheximide. Ad-LacZ infection showed no obvious effects on drug sensitivity. Overexpression of p21 can block apoptosis induced by the combination chemogene therapy of Ad-E2F-1 and topoisomerase II poisons and does not require its proliferating cell nuclear antigen-binding ability. The protein synthesis inhibitor cycloheximide also has a cytotoxicity-protective effect against topoisomerase II inhibitor/E2F-1-induced apoptosis and suggests that new protein synthesis is required for this process. Topoisomerase II inhibitors also cooperated with Ad-E2F-1 to enhance antitumor activity in an in vivo model using xenografts in nude mice. When combined with Adriamycin or etoposide, E2F-1 adenovirus therapy resulted in an 87% or 91% decrease in tumor size, respectively, compared with controls (P < 0.002). Our results show that adenovirus-mediated E2F-1 gene transfer can sensitize melanoma cells to some chemotherapeutic agents, particularly topoisomerase II poisons, in vitro and in vivo. These results suggest a new chemosensitization strategy for melanoma gene therapy.
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PMID:Adenovirus-mediated E2F-1 gene transfer sensitizes melanoma cells to apoptosis induced by topoisomerase II inhibitors. 1191 54


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