Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cell cycle regulatory events that interface with polyamine requirements for cell growth have not yet been clearly identified. Here we use specific inhibitors of polyamine biosynthetic enzymes to investigate the effect of polyamine pool depletion on cell cycle regulation. Treatment of MALME-3M cells with either the ornithine decarboxylase inhibitor alpha-difluoromethylornithine or the S-adenosylmethionine decarboxylase inhibitor MDL-73811 lowered specific polyamine pools and slowed cell growth but did not induce cell cycle arrest. By contrast, treatment with the combination of inhibitors halted cell growth and caused a distinct G1 arrest. The latter was associated with marked reduction of all three polyamine pools, a strong increase in p21(WAF1/CIP1/SDI1) (p21), and hypophosphorylation of retinoblastoma protein. All effects were fully prevented by exogenous polyamines. p21 induction preceded p53 stabilization in MALME-3M cells and also occurred in a polyamine-depleted, p53-nonfunctional melanoma cell line, indicating that p21 is induced at least in part through p53-independent mechanisms. Conditional overexpression of p21 in a fibrosarcoma cell line was shown previously to inhibit the expression of multiple proliferation-associated genes and to induce the expression of genes associated with various aspects of cell senescence and organism aging. Polyamine depletion in MALME-3M cells was associated with inhibition of seven of seven tested p21-inhibited genes and with induction of 13 of 14 tested p21-induced genes. p21 expression is also known to induce a senescence-like phenotype, and phenotypic features of senescence were observed in polyamine-depleted MALME-3M cells. Cells increased in size, appeared more granular, and expressed senescence-associated beta-galactosidase. Cells released from the polyamine inhibition lost the ability to form colonies, failed to replicate their DNA, and approximately 25% became bi- or multinucleated. These events parallel the outcome of prolonged p21 induction in fibrosarcoma cells. The results of this study indicate that polyamine pool depletion achieved by specific biosynthetic enzyme inhibitors causes p21-mediated G1 cell cycle arrest followed by p21-mediated changes in gene expression, development of a senescence-like phenotype, and loss of cellular proliferative capacity.
 ...
PMID:Polyamine depletion in human melanoma cells leads to G1 arrest associated with induction of p21WAF1/CIP1/SDI1, changes in the expression of p21-regulated genes, and a senescence-like phenotype. 1169 89

A facultatively anaerobic bacterium, designated strain COOI3B(T) (= ATCC BAA 136T = DSM 13966T), was isolated from the waters emitted by a bore well tapping the deep subterranean thermal waters of the Great Artesian Basin of Australia. The cells were straight to slightly curved rods (0.5-0.8 x 2-25 microm) that occurred singly and rarely in pairs or in chains. Strain COOI3B(T) was motile by peritrichous flagella. It stained gram-negative, but electron micrographs showed a gram-positive-type cell wall. Spores were never observed and cells were heat-sensitive. Yeast extract at 0.02% (w/v) was required for growth and could also be used as a sole carbon and energy source at concentrations higher than 0.1% (w/v). The strain utilized amorphous iron(III), manganese(IV), nitrate, nitrite and fumarate as electron acceptors in the presence of yeast extract, glucose, sucrose, fructose, maltose, xylose, starch, glycerol, ethanol or lactate. Electron acceptors were not obligately required and growth was better in the presence of nitrate than in its absence. Acid was not produced from growth on carbohydrates. Tryptophan deaminase, H2S, arginine dihydrolase, lysine decarboxylase, beta-galactosidase, arabinosidase, glucuronidase, glucosaminidase, nitroanilidase, xylosidase and ornithine decarboxylase were not produced. Starch and gelatin, but not casein, were hydrolysed. Aesculin and catalase, but not oxidase and urease, were produced. Strain COOI3B(T) grew optimally at temperatures between 37 and 40 degrees C (the temperature growth range was 25-45 degrees C) and at pH 7.0-9.0 (the pH growth range was 6.0 to 9.5) with 5% (w/v) NaCl (the NaCl concentration growth range was 0.9%, w/v). The DNA base composition was 43 +/- 1 mol % G+C. Phylogenetic analysis indicated that it was a member of the family Bacillaceae, Bacillus infernus and Bacillus firmus being the closest phylogenetic neighbours (having a mean similarity value of 96%); hence, strain COOI3B(T) is designated as a novel species, Bacillus subterraneus sp. nov.
 ...
PMID:Bacillus subterraneus sp. nov., an iron- and manganese-reducing bacterium from a deep subsurface Australian thermal aquifer. 1205 51

Mutation/deletion of the adenomatous polyposis coli (APC) tumor suppressor gene in germline cells of rodents and humans is associated with increased intestinal activity of ornithine decarboxylase (ODC), the first enzyme in polyamine synthesis, and intestinal neoplasia. To study the role of APC in signaling ODC expression, we used the human colon tumor cell line HT29 (wtAPC-/-), which has been stably transfected with a zinc-inducible wild-type APC gene. The addition of ZnCl(2) to HT29-APC cells increased wild-type APC protein and Mad1 RNA and protein and decreased levels of c-myc and ODC RNA and protein, relative to these parameters in HT29 cells transfected with the same plasmid containing the beta-galactosidase gene in place of APC. Upon induction of APC expression, ODC promoter activity and RNA levels were suppressed. When the e-box domain in the 5' flanking region of the ODC gene was mutated, ODC promoter activity was unaffected by wild-type APC expression. Antisense, but not missense, c-myc oligonucleotides decreased ODC activity in HT29 cells expressing mutant APC. These results demonstrated that wild-type APC suppressed c-myc and activated Mad1 expression in HT29 colon-derived cells. These proteins, in turn, regulated the transcription of target genes, including ODC. The data presented indicate that ODC is a modifier of APC-dependent signaling in intestinal cells and tissues.
 ...
PMID:APC-dependent regulation of ornithine decarboxylase in human colon tumor cells. 1211 18

The action of electromagnetic fields (EMF) on different pathways related to cell physiology, proliferation, toxicity of chemicals, gene expression, etc., are currently being investigated although the results are still not conclusive and even conflicting. In laboratory and animal studies, EMF has been found to produce a great variety of effects such as: increase in ornithine decarboxylase activity in breast, increase in beta-galactosidase gene expression and oncogene transcription after exposure to 50/60 Hz. Animal studies have shown that the use of EMF can enhance drug delivery across biological barriers (rat abdominal skin), using benzoic acid as the drug candidate. It has been reported by different authors that pulsed EMF (PEMF) can produce alterations in antineoplastic drugs potency. In the present study, we investigated the effects of PEMF on methotrexate cytotoxicity in MCF-7 breast cancer cells and the effects with simultaneous exposure to FeCl3. The data presented in the current report indicate that PEMF (25 Hz, 1.5 mT) do not induce modulation of the action of methotrexate (with and without iron-III) in MCF-7 cells when they are exposed to PEMF for 2 h/day during 3 days.
 ...
PMID:Methotrexate cytotoxicity on MCF-7 breast cancer cells is not altered by exposure to 25 Hz, 1.5 mT magnetic field and iron (III) chloride hexahydrate. 1289 13

The ectopic expression of antibody fragments inside mammalian cells (intrabodies) is a challenging approach for probing and modulating target activities. We previously described the shuttling activity of intracellularly expressed Escherichia coli beta-galactosidase conferred by the single-chain Fv (scFv) fragment 13R4 equipped with nuclear import/export signals. Here, by appending to scFvs the proteolytic PEST signal sequence (a protein region rich in proline, glutamic acid, serine and threonine) of mouse ornithine decarboxylase, we tested whether short-lived or destabilized intrabodies could affect the steady-state level of target by redirecting it to the proteasomes. In the absence of antigen, the half-life of the modified scFv 13R4, relative to untagged molecules, was considerably reduced in vivo. However, after coexpression with either cytoplasmic or nuclear antigen, the destabilized 13R4 fragments were readily maintained in the cell and strictly colocalized with beta-galactosidase. Analysis of destabilized site-directed mutants, that were as soluble as 13R4 in the intracellular context, demonstrated that binding to antigen was essential for survival under these conditions. This unique property allowed specific detection of beta-galactosidase, even when expressed at low level in stably transformed cells, and permitted isolation by flow cytometry from a transfected cell mixture of those living cells specifically labeled with bound intrabody. Altogether, we show that PEST-tagged intrabodies of sufficient affinity and solubility are powerful tools for imaging the presence and likely the dynamics of protein antigens that are resistant to proteasomal degradation in animal cells.
 ...
PMID:Extended half-life upon binding of destabilized intrabodies allows specific detection of antigen in mammalian cells. 1594 19

It has been hypothesized that translational efficiency is determined by the amount of secondary structure in the 5'-untranslated region (5'-UTR) of mRNA. Here, we examined whether specific 5'-UTRs with excessive secondary structure selectively regulate translational efficiency in adult cardiocytes. Recombinant adenoviruses were generated to express reporter mRNAs consisting of the 5'-UTR derived from c-jun or ornithine decarboxylase (ODC) fused to beta-galactosidase (betaGal) coding sequence. Each adenovirus expressed GFP mRNA as a control for 5'-UTRs with minimal secondary structure. Subsequently, cardiocytes were electrically stimulated to contract at 1 Hz to accelerate protein synthesis as compared to quiescent controls. Translational efficiency was calculated by measuring protein expression as a function of mRNA levels. Translational efficiency of c-jun/betaGal mRNA increased significantly by 3.7-fold in contracting vs. quiescent cardiocytes, but ODC/betaGal mRNA was unchanged. Contraction increased c-jun/betaGal mRNA levels in polyribosomes by 2.3-fold, which indicates that translational efficiency was enhanced by mobilization. A short, unstructured 5'-UTR was sufficient for efficient translation of betaGal mRNA in quiescent and contracting cardiocytes. GFP mRNA produced similar results. These studies demonstrate that the 5'-UTR functions as a determinant of translational efficiency of specific mRNAs, such as c-jun, that regulate growth of the adult cardiocyte.
 ...
PMID:Role of the 5'-untranslated region in regulating translational efficiency of specific mRNAs in adult cardiocytes. 1941 87


<< Previous 1 2