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

---

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

We have isolated several mutant herpes simplex viruses, specifically mutated in the infected cell protein 8 (ICP8) gene, to define the functional domains of ICP8, the major viral DNA-binding protein. To facilitate the isolation of these mutants, we first isolated a mutant virus, HD-2, with the lacZ gene fused to the ICP8 gene so that an ICP8-beta-galactosidase fusion protein was expressed. This virus formed blue plaques on ICP8-expressing cell lines in the presence of 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside. Mutated ICP8 gene plasmids cotransfected with HD-2 DNA yielded recombinant viruses with the mutant ICP8 gene incorporated into the viral genome. These recombinants were identified by formation of white plaques. Four classes of mutants were defined: (i) some expressed ICP8 that could bind to DNA but could not localize to the cell nucleus; (ii) some expressed ICP8 that did not bind to DNA but localized to the nucleus; (iii) some expressed ICP8 that neither bound to DNA nor localized to the nucleus; and (iv) one expressed ICP8 that localized to the cell nucleus and bound to DNA in vitro, but the mutant virus did not replicate its DNA. These classes of mutants provide genetic evidence that DNA binding and nuclear localization are distinct functions of ICP8 and that ICP8 has nuclear functions other than binding to DNA. Furthermore, the portion of ICP8 needed for a nuclear function(s) distinct from DNA binding is the part of ICP8 showing sequence similarity to that of the cellular protein cyclin or proliferating cell nuclear antigen.
...
PMID:Genetic evidence for multiple nuclear functions of the herpes simplex virus ICP8 DNA-binding protein. 255 53

The regulatory region of Drosophila proliferating cell nuclear antigen (PCNA) gene consists of a promoter region (-168 to +24 with respect to the transcription initiation site) and an upstream region containing three homeodomain protein binding sites (HDB) (-357 to -165). The PCNA gene regulatory regions with HDB (-607 to +137) or without HDB (-168 to +137) were fused with the lacZ and transgenic flies were established by P-element-mediated transformation. Male transgenic flies were crossed with wild-type females, and zygotic expression of the lacZ was monitored by quantitative beta-galactosidase assay, at various stages of development. Expression of the lacZ was high in embryos, first and second instar larvae, and adult females, and low at other stages of development. Only a marginal difference in expression was observed between flies carrying the homeodomain protein binding region and those not carrying it. Spatial pattern of the lacZ expression in the embryo visualized by immunostaining with the anti-lacZ antibody was similar to the distribution of the endogenous PCNA protein. Here, too, only a marginal difference was observed between transgenic flies carrying two different constructs of the PCNA lacZ. In genetic crossing experiments of transgenic flies with those carrying mutation in homeobox genes, no significant change in the lacZ expression pattern was observed. However, when male transgenic flies were crossed with female flies homozygous for a torso gain-of-function allele, repression of the lacZ expression was observed in the central region of the embryo. Because these local changes in the lacZ expression depend on the homeodomain protein binding region, unidentified homeodomain proteins are probably involved. Our results suggest that the promoter region is practically sufficient for expression of the PCNA gene and that the homeodomain protein binding region functions as a silencer when torso is activated ectopically.
...
PMID:Role of homeodomain protein binding region in the expression of Drosophila proliferating cell nuclear antigen gene: analysis with transgenic flies. 778 11

p53 induction and cell cycle arrest occur following DNA damage, possibly to allow repair prior to replication. p21WAF1/CIP1, a cyclin-cyclin-dependent kinase inhibitor and proliferating cell nuclear antigen-interacting protein, is induced by p53 and mediates the cell cycle arrest. To investigate a role for p21 in DNA repair in vivo, we studied the expression of in vitro damaged reporter DNA transfected into p21 +/+ or -/- HCT116 human colon cancer cells. Introduction of UV-damaged or cisplatinum-damaged cytomegalovirus-driven beta-galactosidase reporter DNA into tumor cells revealed a significant decrease (2-5-fold) in reporter expression in p21 -/- versus +/+ cells. In the absence of DNA damage, there was a significant increase (2-3-fold) in the number of 6-TG-resistant colonies derived from p21 -/- versus +/+ cells. Reintroduction of wild-type p21, but not a p21 C-terminal truncation mutant which lacks the proliferating cell nuclear antigen interaction domain, stimulated (2-3-fold) the repair capacity of the p21-deficient cells. We conclude that p21 deficiency is associated with a defect in DNA repair, which could lead to an increased sensitivity of tumor cells to DNA damage.
...
PMID:Repair Defect in p21 WAF1/CIP1 -/- human cancer cells. 862 93

The expression of genes involved in DNA replication is closely correlated with the proliferating state of cells and is repressed with the progression of differentiation during development. Promoter regions of the Drosophila proliferating cell nuclear antigen (PCNA) gene and the DNA polymerase alpha gene contain a common 8-base pair promoter element (DRE: DNA replication-related element). The examination of a common expression mechanism for DNA replication-related genes, which is regulated positively by growth signals and negatively by differentiation signals would be of interest. We generated PCNA-LacZ fusion genes in which the 5'-flanking sequence of the PCNA gene has been mutated. An examination of the expression of these fusion genes, introduced into flies by germ-line transformation, led to the identification of another distinct regulatory element, URE (upstream regulatory element), within the region from -168 to -119 with respect to the transcription initiation site. During embryogenesis, the region containing the DRE sequence (-108 to -91) greatly stimulated the PCNA gene minimal promoter (-86 to +130), when it was placed upstream of the promoter in both normal and reverse orientations. Addition of the URE sequence further stimulated the promoter activity twofold. During larval stages, both DRE and URE were indispensable to the promoter activity, since neither of the sequences alone activated the minimal promoter. Demonstration of beta-galactosidase activity indicated URE plays an essential role in various larval tissues such as salivary gland and imaginal disc. While the minimal promoter region alone directed maternal expression of lacZ in ovaries of adult females, both DRE and URE further stimulated promoter activity. These results show several elements of the PCNA gene promoter play roles during Drosophila development.
...
PMID:Roles of multiple promoter elements of the proliferating cell nuclear antigen gene during Drosophila development. 907 66

Proliferation and dedifferentiation of tubular cells are the hallmark of early regeneration after renal ischemic injury. Vimentin, a class III intermediate filament expressed only in mesenchymal cells of mature mammals, was shown to be transiently expressed in post-ischemic renal tubular epithelial cells. Vimentin re-expression was interpreted as a marker of cellular dedifferentiation, but its role in tubular regeneration after renal ischemia has also been hypothesized. This role was evaluated in mice bearing a null mutation of the vimentin gene. Expression of vimentin, proliferating cell nuclear antigen (a marker of cellular proliferation), and villin (a marker of differentiated brush-border membranes) was studied in wild-type (Vim+/+), heterozygous (Vim+/-), and homozygous (Vim-/-) mice subjected to transient ischemia of the left kidney. As expected, vimentin was detected by immunohistochemistry at the basal pole of proximal tubular cells from post-ischemic kidney in Vim+/+ and Vim+/- mice from day 2 to day 28. The expression of the reporter gene beta-galactosidase in Vim+/- and Vim-/- mice confirmed the tubular origin of vimentin. No compensatory expression of keratin could be demonstrated in Vim-/- mice. The intensity of proliferating cell nuclear antigen labeling and the pattern of villin expression were comparable in Vim-/-, Vim+/- and Vim+/+ mice at any time of the study. After 60 days, the structure of post-ischemic kidneys in Vim-/- mice was indistinguishable from that of normal non-operated kidneys in Vim+/+ mice. In conclusion, 1) the pattern of post-ischemic proximal tubular cell proliferation, differentiation, and tubular organization was not impaired in mice lacking vimentin and 2) these results suggest that the transient tubular expression of vimentin is not instrumental in tubular regeneration after renal ischemic injury.
...
PMID:Normal tubular regeneration and differentiation of the post-ischemic kidney in mice lacking vimentin. 909 92

The development of the tubular heart into a complex four-chambered organ requires precise temporal and region-specific regulation of cell proliferation, migration, death and differentiation. While the regulatory mechanisms in heart morphogenesis are not well understood, increasing attention has focused on the homeodomain proteins, which are generally linked to morphogenetic processes. The homeodomain containing gene Gax has been shown to be expressed in heart and smooth muscle tissues. In this study, the Gax protein was detected in the nuclei of myocardial cells relatively late in chicken heart development, at a time when myocyte proliferation is declining. To test the hypothesis that the Gax protein functions as a negative regulator of cardiomyocyte proliferation, a replication-defective adenovirus was used to force its precocious nuclear expression during chicken heart morphogenesis. In experiments in which Gax- and beta-galactosidase-expressing adenoviruses were co-injected, clonal expansion of myocytes was reduced, consistent with inhibition of myocyte proliferation. This effect on proliferation was corroborated by the finding that the percentage of exogenous Gax-expressing myocytes that were positive for the cell cycle marker PCNA decreased over time and was lower than in control myocytes. The precocious nuclear expression of Gax in tubular hearts resulted in abnormal heart morphology, including small ventricles with rounded apices, a thinned compact zone and coarse trabeculae. These results suggest a role for the Gax protein in heart morphogenesis causing proliferating cardiomyocytes to withdraw from the cell cycle, thus influencing the size and shape that the heart ultimately attains.
...
PMID:Forced expression of the homeodomain protein Gax inhibits cardiomyocyte proliferation and perturbs heart morphogenesis. 933 88

Treatment of hepatitis B virus carriers with the nucleoside analog lamivudine suppresses virus replication. However, rather than completely eliminating the virus, long-term treatment often ends in the outgrowth of drug-resistant variants. Using woodchucks chronically infected with woodchuck hepatitis virus (WHV), we investigated the consequences of combining lamivudine treatment with immunotherapy mediated by an adenovirus superinfection. Eight infected woodchucks were treated with lamivudine and four were infected with approximately 10(13) particles of an adenovirus type 5 vector expressing beta-galactosidase. Serum samples and liver biopsies collected following the combination therapy revealed a 10- to 20-fold reduction in DNA replication intermediates in three of four woodchucks at 2 weeks after adenovirus infection. At the same time, covalently closed circular DNA (cccDNA) and viral mRNA levels both declined about two- to threefold in those woodchucks, while mRNA levels for gamma interferon and tumor necrosis factor alpha as well as for the T-cell markers CD4 and CD8 were elevated about twofold. Recovery from adenovirus infection was marked by elevation of sorbitol dehydrogenase, a marker for hepatocyte necrosis, as well as an 8- to 10-fold increase in expression of proliferating cell nuclear antigen, a marker for DNA synthesis, indicating significant hepatocyte turnover. The fact that replicative DNA levels declined more than cccDNA and mRNA levels following adenovirus infection suggests that the former decline either was cytokine induced or reflects instability of replicative DNA in regenerating hepatocytes. Virus titers in all four woodchucks were only transiently suppressed, suggesting that the effect of combination therapy is transient and, at least under the conditions used, does not cure chronic WHV infections.
...
PMID:Combination therapy with lamivudine and adenovirus causes transient suppression of chronic woodchuck hepatitis virus infections. 1109 Jan 75

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.
...
PMID:Adenovirus-mediated E2F-1 gene transfer sensitizes melanoma cells to apoptosis induced by topoisomerase II inhibitors. 1191 54

The translation initiation rate is greatly affected by the secondary structure of the translation initiation region (TIR) of mRNA. A novel system was established for improving the translation initiation rate of a foreign gene in E. coli. As a model, the 5' 114 bp coding sequence (38 amino acids from the start codon) of human proliferating cell nuclear antigen (PCNA) gene was fused with the lacZ' gene at its 5' end in vector pTZ19R. A Shine/Dalgarno (SD) sequence GAGGT was inserted to the -8 position of AUG by site-directed mutation. Then the flanking sequences of SD, which were the 6 nucleotides upstream the SD and the 7 nucleotides between SD and AUG, were randomly changed by PCR using a synthetic primer with partially random sequences. This random mutation led to potential variations in the secondary structure of the TIR of mRNA through base pairing with the 5' coding sequence. The 5' PCNA-LacZ' mRNA could be efficiently and specifically transcribed by inducible T7 RNA polymerase in E. coli strain JM 109 (DE3). There were 269 clones of 5' PCNA-LacZ' fusion plasmid selected first by the blue color on X-gal plate and then by hybridization with a 5' PCNA probe. Eight clones with different blue colors among the 269 clones were chosen for beta-galactosidase activity assay. The results showed that the difference between their enzyme activities was more than 20 fold, but there seemed no apparent difference at the transcription level as assayed by RNA dot hybridization, which suggested that the difference in the expression of the fusion protein was due to the different rate of translation initiation. Thus, by this strategy, an effective translation initiation region for the high expression of human PCNA gene in E. coli was obtained.
...
PMID:A New Strategy for Optimizing the Translation Initiation Rate of Foreign Gene Expression in E. coli. 1216 85

Transfection of the wild-type p53 gene into an immortalized human endothelial cell line (ECV-304) by recombinant adenoviral delivery resulted in high level expression of the wild-type p53 protein and induction of apoptosis. Increases in the number of apoptotic cells were observed within 12 h after infection of ECV-304 cells with recombinant p53 adenovirus, as deter-mined by the appearance of internucleosomal DNA fragmentation ladders and by TUNEL and electron microscopic analyses. Control cells infected with a beta-galactosidase recombinant adenovirus exhibited little or no increase in apoptosis over uninfected cells. The expression of Waf-1 and Bax gene products were in-creased substantially in apoptotic ECV-304 cells as determined by Northern blot, reverse transcription-PCR and immunoblotting analyses. Lesser increases in the expression of the PCNA gene were detected in ECV-304 cells undergoing apoptosis. Both control and apoptotic ECV-304 cells did not express detectable levels of Bcl-2 mRNA or protein in Northern blotting and immunoblotting analyses, respectively. The data suggest a role for the Bax gene product in p53-mediated apoptosis of endothelial cells.
...
PMID:Expression of Bax, Bcl-2, Waf-1, and PCNA gene products in an immortalized human endothelial cell line undergoing p53-mediated apoptosis. 1464 27


1 2 Next >>

---