1
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Avraham S, Avraham H, Austen KF, Stevens RL. Negative and positive cis-acting elements in the promoter of the mouse gene that encodes the serine/glycine-rich peptide core of secretory granule proteoglycans. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)48538-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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2
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Jasin M, Liang F. Mouse embryonic stem cells exhibit high levels of extrachromosomal homologous recombination in a chloramphenicol acetyltransferase assay system. Nucleic Acids Res 1991; 19:7171-5. [PMID: 1766877 PMCID: PMC332558 DOI: 10.1093/nar/19.25.7171] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Mouse embryonic stem (ES) cells were compared to COS1 and CV1 cells for their ability to perform extrachromosomal homologous recombination. RSVCAT plasmid substrates consisting of overlapping chloramphenicol acetyltransferase (CAT) gene fragments were transiently transfected into cells and extracts were assayed for CAT activity. Approximately 10% activity, relative to transfection with a complete CAT gene, was recovered for the recombination substrates in each of the cell lines tested. ES cells, therefore, as other cell lines, are capable of high levels of extrachromosomal recombination.
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Affiliation(s)
- M Jasin
- Department of Cell Biology and Genetics, New York, NY
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3
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Vargula hilgendorfii luciferase: a secreted reporter enzyme for monitoring gene expression in mammalian cells. Gene 1990. [DOI: 10.1016/0378-1119(90)90261-o] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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4
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Sparkowski J, Das A. The nucleotide sequence of greA, a suppressor gene that restores growth of an Escherichia coli RNA polymerase mutant at high temperature. Nucleic Acids Res 1990; 18:6443. [PMID: 2243801 PMCID: PMC332557 DOI: 10.1093/nar/18.21.6443] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- J Sparkowski
- Department of Microbiology, University of Connecticut Health Center, Farmington 06030
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5
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Paulssen RH, Paulssen EJ, Aleström P, Gautvik KM. Electroporation of rat pituitary (GH) cell lines: optimal parameters and effects on endogenous hormone production. Biochem Biophys Res Commun 1990; 171:1029-36. [PMID: 2222425 DOI: 10.1016/0006-291x(90)90787-n] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
An efficient electroporation procedure was established for the genetic transformation of two clonal strains of hormone producing rat pituitary cells (GH12C1 and GH3). We used the bacterial chloramphenicol acetyltransferase (CAT) gene as reporter gene to determine optimal conditions for electroporation. The conditions found to be optimal, measured as expression of the highest CAT activity, were 240-300 V and a DNA concentration of 30-60 micrograms/ml in sucrose buffer. Cell viability was then about 50 per cent. Maximum CAT activity was seen 24 hours after electroporation. The electroporation procedure, in the presence or absence of DNA, caused a transient decrease in endogenous growth hormone (GH) and prolactin (PRL) production.
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Affiliation(s)
- R H Paulssen
- Institute of Medical Biochemistry, University of Oslo, Norway
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6
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Thomas SM, Crowne HM, Pidsley SC, Sedgwick SG. Structural characterization of the Salmonella typhimurium LT2 umu operon. J Bacteriol 1990; 172:4979-87. [PMID: 2203737 PMCID: PMC213153 DOI: 10.1128/jb.172.9.4979-4987.1990] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The umuDC operon of Escherichia coli encodes functions required for mutagenesis induced by radiation and a wide variety of chemicals. The closely related organism Salmonella typhimurium is markedly less mutable than E. coli, but a umu homolog has recently been identified and cloned from the LT2 subline. In this study the nucleotide sequence and structure of the S. typhimurium LT2 umu operon have been determined and its gene products have been identified so that the molecular basis of umu activity might be understood more fully. S. typhimurium LT2 umu consists of a smaller 417-base-pair (bp) umuD gene ending 2 bp upstream of a larger 1,266-bp umuC gene. The only apparent structural difference between the two operons is the lack of gene overlap. An SOS box identical to that found in E. coli is present in the promoter region upstream of umuD. The calculated molecular masses of the umuD and umuC gene products were 15.3 and 47.8 kilodaltons, respectively, which agree with figures determined by transpositional disruption and maxicell analysis. The S. typhimurium and E. coli umuD sequences were 68% homologous and encoded products with 71% amino acid identity; the umuC sequences were 71% homologous and encoded products with 83% amino acid identity. Furthermore, the potential UmuD cleavage site and associated catalytic sites could be identified. Thus the very different mutagenic responses of S. typhimurium LT2 and E. coli cannot be accounted for by gross differences in operon structure or gene products. Rather, the ability of the cloned S. typhimurium umuD gene to give stronger complementation of E. coli umuD77 mutants in the absence of a functional umuC gene suggests that Salmonella UmuC protein normally constrains UmuD protein activity.
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Affiliation(s)
- S M Thomas
- Genetics Division, National Institute for Medical Research, Mill Hill, London, United Kingdom
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7
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Kagawa N, Waterman MR. cAMP-dependent transcription of the human CYP21B (P-450C21) gene requires a cis-regulatory element distinct from the consensus cAMP-regulatory element. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38591-6] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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8
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Chu G, Chang E. Cisplatin-resistant cells express increased levels of a factor that recognizes damaged DNA. Proc Natl Acad Sci U S A 1990; 87:3324-7. [PMID: 2333286 PMCID: PMC53892 DOI: 10.1073/pnas.87.9.3324] [Citation(s) in RCA: 95] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Cancer treatment with the drug cisplatin is often thwarted by the emergence of drug-resistant cells. To study this phenomenon, we identified two independent cellular factors that recognize cisplatin-damaged DNA. One of the two factors, designated XPE binding factor, is deficient in complementation group E of xeroderma pigmentosum, an inherited disease characterized by defective repair of DNA damaged by ultraviolet radiation, cisplatin, and other agents. Human tumor cell lines selected for resistance to cisplatin showed more efficient DNA repair and increased expression of XPE binding factor. These results suggest that XPE binding factor may be responsible, at least in part, for the development of cisplatin resistance in human tumors and that the mechanism may be increased DNA repair.
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Affiliation(s)
- G Chu
- Department of Medicine, Stanford University School of Medicine, CA 94305
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9
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Abrams JM, Schimke RT. Deletion of stably integrated DNA is suppressed by cadmium and zinc. Proc Natl Acad Sci U S A 1989; 86:9380-4. [PMID: 2594774 PMCID: PMC298499 DOI: 10.1073/pnas.86.23.9380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The bacterial xanthine-guanine phosphoribosyltransferase (GPT) gene was fused to a metal-responsive promoter and transfected into a murine cell line. Clonal transformants harboring metal-responsive or nonresponsive GPT genes (using a thymidine kinase promoter) were then studied for the loss of transfected gene function either during periods of constitutive expression or during periods of induced activity. Nontoxic levels of cadmium and zinc markedly reduced the frequency of mutagenesis in all transfected lines irrespective of transcriptional status. A survey of 17 GPT-clones derived from two original transfectants showed partial or complete excisions of the transfected gene in every case. These studies show that quantities of cadmium and zinc that induce metallothioneins also suppress the incidence of deletions in murine cells.
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Affiliation(s)
- J M Abrams
- Department of Biological Sciences, Stanford University, CA 94305
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10
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Smith-Ravin J, Jeggo PA. Use of damaged plasmid to study DNA repair in X-ray sensitive (xrs) strains of Chinese hamster ovary (CHO) cells. Int J Radiat Biol 1989; 56:951-61. [PMID: 2574223 DOI: 10.1080/09553008914552411] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The effect of gamma-irradiation of pSV2gpt DNA on its transfection frequency has been analysed using CHO xrs mutants. Xrs mutants are sensitive to ionizing radiation and show a defect in double-strand break (dsb) rejoining. At low doses a sharp decrease in relative transfection frequency, i.e. transfection frequency of irradiated plasmid relative to untreated plasmid, was observed in the xrs mutants compared with the parent line K1. Electrophoresis of the irradiated plasmid DNA showed that the decrease in transfection frequency in the xrs mutants correlated with the change of supercoiled molecules into open-circular forms. One explanation for these results is that the xrs gene could play a part in the integration or repair of open-circular molecules produced by gamma-radiation. In the parent line CHO-K1, open-circular and supercoiled molecules have the same transfection frequency. The effect of linearization of pSV2gpt DNA by restriction enzymes on transfection frequency in xrs and wild-type strains has also been examined. In contrast to the above results we have not detected a difference in the relative transfection frequency between xrs and wild-type strains. The results suggest that restricted plasmid DNA is subject to extensive nucleolytic degradation, and this occurs to equal extents in wild type and mutant strains.
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Affiliation(s)
- J Smith-Ravin
- Genetics Division, National Institute for Medical Research, London, U.K
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11
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Abstract
We examined causes for high variability in data from enzymatic transient gene expression assays. Our results strongly suggest that variation in transfection efficiency is the major cause of data variation and can seriously compromise valid interpretation of data. We compared averaging data from multiple transfections and cotransfection of a second reporter gene as methods for correcting for variation in transfection efficiency. We found that transfection efficiency can be so highly variable that neither method necessarily overcomes the resulting bias in data. Depending upon the degree in variation in transfection efficiency, a combination of the two methods may be advisable. The need to normalize data for transfection efficiency is dependent upon the difference in strengths of promoters being tested and the relative variability of the transfection method used. We also show that the level of reporter gene expression between transfection experiments performed on different days can vary by more than 10-fold.
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Affiliation(s)
- T Hollon
- Department of Microbiology, University of Washington, Seattle 98195
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12
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Jeggo PA, Smith-Ravin J. Decreased stable transfection frequencies of six X-ray-sensitive CHO strains, all members of the xrs complementation group. Mutat Res 1989; 218:75-86. [PMID: 2770766 DOI: 10.1016/0921-8777(89)90013-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Six X-ray-sensitive strains (xrs) of the Chinese hamster ovary (CHO) cell line, all of which have a defect in double-strand break (dsb) rejoining, have been investigated for their proficiency in DNA transfection assays. All 6 strains and clonal isolates derived from them, show a decreased stable transfection frequency using the plasmids pSV2neo and pSV2gpt after transfection by either the CaPh method or the polybrene method. The magnitude of this effect is DNA concentration dependent and is more marked after transfection with higher DNA concentrations (5-20 micrograms DNA). A spontaneous X-ray-resistant reactivant (or revertant) of one xrs strain also acquired the elevated transfection frequency of the wild-type strain providing evidence for a causal relationship between the decreased transfection frequency and the xrs phenotype. In contrast, the strains show no defect when transfection is assayed using a transient transfection system. Since the transient transfection assay only depends on the uptake and transcriptional activity of foreign DNA, and does not necessitate DNA integration, this suggests that the xrs strains do not have a defect in the uptake of foreign DNA, but might have a defect in integration or the processing of DNA molecules prior to integration.
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Affiliation(s)
- P A Jeggo
- National Institute for Medical Research, Mill Hill, London, Great Britain
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13
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14
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Veldhuisen G, Van Dijk M, Meijer J, Enger-Valk BE, Pouwels PH. Transient expression in mammalian cells of the bacterial reporter gene encoding mercuric reductase: effects of various regulatory elements. Gene 1988; 71:381-90. [PMID: 3224830 DOI: 10.1016/0378-1119(88)90055-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The effect of several transcriptional regulatory elements on gene expression in mammalian cells was investigated. As a reporter gene we have used the bacterial gene merA coding for the enzyme mercuric reductase. Several plasmids were constructed with different promoter/enhancer sequences (pSV/E, pSV/L, pMT, pRSV or pAd) at the 5' end and different splicing (small intron of the T antigen of SV40 or the second intron of the rabbit beta-globin gene) and/or polyadenylation signals (AEn, ALn or AR beta Gn) at the 3' end of the merA gene. Expression was measured in five different mammalian cell lines. In COS cells the highest level of expression is obtained with pSV/L and the lowest level with pSV/E. In HeLa, CV-1, Ltk-, and CHO cells merA expression is relatively high, under control of pRSV and pMT and relatively low under control of pSV/L and pAd. The introns studied have a negative effect on the expression of merA. The presence of a polyadenylation signal downstream from the gene is essential for its expression. The three different polyadenylation signals studied give a similar stimulatory effect on the level of expression of the merA gene.
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Affiliation(s)
- G Veldhuisen
- TNO Medical Biological Laboratory, Rijswijk, The Netherlands
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15
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Fromont-Racine M, Pictet R. Fast non-chromatographic method to assay for xanthine-guanosine phosphoribosyl transferase. Nucleic Acids Res 1988; 16:7204. [PMID: 3405776 PMCID: PMC338385 DOI: 10.1093/nar/16.14.7204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- M Fromont-Racine
- Institut J. Monod (CNRS), Unité INSERM 257, Université Paris, France
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16
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Berger J, Hauber J, Hauber R, Geiger R, Cullen BR. Secreted placental alkaline phosphatase: a powerful new quantitative indicator of gene expression in eukaryotic cells. Gene 1988; 66:1-10. [PMID: 3417148 DOI: 10.1016/0378-1119(88)90219-3] [Citation(s) in RCA: 551] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
This paper describes a novel eukaryotic reporter gene, secreted alkaline phosphatase (SEAP). In transient expression experiments using transfected mammalian cells, we demonstrate that SEAP yields results that are qualitatively and quantitatively similar, at both the mRNA and protein levels, to parallel results obtained using established reporter genes. However, SEAP offers significant advantages in terms of ease of assay and assay expense, and also has the potential for quantitative assay at levels as low as 0.2 pg/ml of culture medium. These attributes suggest that SEAP may have general utility in experiments which rely on the accurate measurement of reporter gene expression levels.
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Affiliation(s)
- J Berger
- Roche Institute of Molecular Biology, Hoffmann-La Roche, Inc., Nutley, NJ 07110
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17
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Abstract
We have developed a method for efficiently generating transient pores in the outer membranes of Escherichia coli K-12 derivatives by using a new type of electroporation apparatus. The pores are large enough and persist long enough to facilitate the equilibration of plasmid molecules between the intracellular and extracellular spaces. The method has been used to transform bacterial cells with an efficiency greater than 10(9) transformants per microgram of plasmid. It has also been used to extract intact plasmid from transformed cells with efficiencies comparable to those of the traditional alkaline lysis or CsCl equilibrium density gradient techniques. The technique is simple and rapid, allowing a transformation or the preparation of microgram quantities of plasmid to be accomplished in minutes.
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Affiliation(s)
- N M Calvin
- Department of Biological Sciences, Stanford University, California 94305-5020
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18
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Abstract
Two separate domains within the 134-base-pair rat elastase I enhancer and a third domain at the enhancer-promoter boundary are required for selective expression in pancreatic acinar cells. The domains were detected by a series of 10-base-pair substitution mutations across the elastase I gene regulatory region from positions -200 to -61. The effect of each mutant on the pancreas-specific expression of a linked chloramphenicol acetyltransferase gene was assayed by transfection into pancreatic 266-6 acinar cells and control NIH/3T3 cells. The two enhancer domains are nonredundant, because mutations in either eliminated (greater than 100-fold reduction) expression in 266-6 cells. DNase I protection studies of the elastase I enhancer-promoter region with partially purified nuclear extracts from pancreatic tissue and 266-6 cells revealed nine discrete protected regions (footprints) on both DNA strands. One of three footprints that lie within the two functional domains of the enhancer contained a sequence, conserved among several pancreas-specific genes, which when mutated decreased linked chloramphenicol acetyltransferase expression up to 170-fold in 266-6 cells. This footprint may represent a binding site for one or more pancreas-specific regulatory proteins.
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19
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A new genetic approach for studying hormonal regulation of urokinase-type plasminogen activator gene expression in LLC-PK1 cells. Mol Cell Biol 1988. [PMID: 2830499 DOI: 10.1128/mcb.7.12.4535] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In LLC-PK1 cells, a cyclic AMP (cAMP)-elevating peptide hormone, calcitonin, induces urokinase-type plasminogen activator (uPA) gene transcription without concomitant protein synthesis. To understand the molecular mechanism of the uPA gene regulation by cAMP, we developed a system which allows us to obtain mutant cells with modified regulatory proteins. A uPA-gpt hybrid gene was constructed, in which the regulatory region of the uPA gene was linked to a bacterial xanthine-guanine phosphoribosyltransferase gene (gpt), and it was transfected into LLC-PK1 cells. A stably transformed cell line, which expressed gpt only in the presence of calcitonin, was obtained, and then these cells were treated with a chemical mutagen, ethyl methanesulfonate. Cells were screened for constitutive gpt expression and, as mutations in regulatory proteins should affect the two genes at the same time, cells were further screened for an increased basal uPA mRNA level. Several such clones were obtained and none of them had modified cAMP-dependent protein kinase activity, suggesting that mutations were in the post-protein kinase step in the pathway of hormone action. Five clones were fused with the parent LLC-PK1 cells, and all of the fusion cells showed reduced basal uPA mRNA levels, indicating that they were recessive mutants. One clone was analyzed further for sensitivity to calcitonin in the induction of uPA mRNA, and it showed a significantly different dose-response pattern compared with parent cells. These results suggest that the uPA gene is regulated, at least partly, by a negatively regulating factor and that the action of cAMP is linked to this factor.
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20
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Kruse F, Komro CT, Michnoff CH, MacDonald RJ. The cell-specific elastase I enhancer comprises two domains. Mol Cell Biol 1988; 8:893-902. [PMID: 3352608 PMCID: PMC363221 DOI: 10.1128/mcb.8.2.893-902.1988] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Two separate domains within the 134-base-pair rat elastase I enhancer and a third domain at the enhancer-promoter boundary are required for selective expression in pancreatic acinar cells. The domains were detected by a series of 10-base-pair substitution mutations across the elastase I gene regulatory region from positions -200 to -61. The effect of each mutant on the pancreas-specific expression of a linked chloramphenicol acetyltransferase gene was assayed by transfection into pancreatic 266-6 acinar cells and control NIH/3T3 cells. The two enhancer domains are nonredundant, because mutations in either eliminated (greater than 100-fold reduction) expression in 266-6 cells. DNase I protection studies of the elastase I enhancer-promoter region with partially purified nuclear extracts from pancreatic tissue and 266-6 cells revealed nine discrete protected regions (footprints) on both DNA strands. One of three footprints that lie within the two functional domains of the enhancer contained a sequence, conserved among several pancreas-specific genes, which when mutated decreased linked chloramphenicol acetyltransferase expression up to 170-fold in 266-6 cells. This footprint may represent a binding site for one or more pancreas-specific regulatory proteins.
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Affiliation(s)
- F Kruse
- Department of Biochemistry, University of Texas Health Science Center, Dallas 75235
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21
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Hofstetter P, Kikinis Z, Altus MS, Pearson D, Nagamine Y. A new genetic approach for studying hormonal regulation of urokinase-type plasminogen activator gene expression in LLC-PK1 cells. Mol Cell Biol 1987; 7:4535-41. [PMID: 2830499 PMCID: PMC368138 DOI: 10.1128/mcb.7.12.4535-4541.1987] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
In LLC-PK1 cells, a cyclic AMP (cAMP)-elevating peptide hormone, calcitonin, induces urokinase-type plasminogen activator (uPA) gene transcription without concomitant protein synthesis. To understand the molecular mechanism of the uPA gene regulation by cAMP, we developed a system which allows us to obtain mutant cells with modified regulatory proteins. A uPA-gpt hybrid gene was constructed, in which the regulatory region of the uPA gene was linked to a bacterial xanthine-guanine phosphoribosyltransferase gene (gpt), and it was transfected into LLC-PK1 cells. A stably transformed cell line, which expressed gpt only in the presence of calcitonin, was obtained, and then these cells were treated with a chemical mutagen, ethyl methanesulfonate. Cells were screened for constitutive gpt expression and, as mutations in regulatory proteins should affect the two genes at the same time, cells were further screened for an increased basal uPA mRNA level. Several such clones were obtained and none of them had modified cAMP-dependent protein kinase activity, suggesting that mutations were in the post-protein kinase step in the pathway of hormone action. Five clones were fused with the parent LLC-PK1 cells, and all of the fusion cells showed reduced basal uPA mRNA levels, indicating that they were recessive mutants. One clone was analyzed further for sensitivity to calcitonin in the induction of uPA mRNA, and it showed a significantly different dose-response pattern compared with parent cells. These results suggest that the uPA gene is regulated, at least partly, by a negatively regulating factor and that the action of cAMP is linked to this factor.
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22
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Epinette WW, Parker CM, Jones EL, Greist MC. Mycophenolic acid for psoriasis. A review of pharmacology, long-term efficacy, and safety. J Am Acad Dermatol 1987; 17:962-71. [PMID: 3429723 DOI: 10.1016/s0190-9622(87)70285-0] [Citation(s) in RCA: 188] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
In previous studies of up to 2 years' duration, mycophenolic acid has been shown to be an effective psoriasis suppressant. As the result of questions raised regarding the possible immunosuppressive and carcinogenic potentials of the drug, in addition to its apparent acute gastrointestinal side effects, widespread clinical trials were discontinued in 1977. We were given the unique opportunity of continuing to administer the drug on a compassionate-use basis to 85 patients for up to 13 years. In this review we report continued efficacy without dose escalation. Gastrointestinal side effects, prominent in the early years of the study, became infrequent. Although 11.6% of the patients developed uncomplicated zoster, no clinical evidence of immunosuppression was noted. The seven malignant neoplasms that arose in six of the patients were not unusual considering the age of the study population. Six patients died of conditions believed to be unrelated to drug therapy. We continue to believe that mycophenolic acid is an effective drug for the treatment of moderate to severe psoriasis and that the risks of its long-term administration are acceptable. With appropriate clinical and laboratory monitoring it can be given safely to patients who cannot take methotrexate and who may not be candidates for PUVA, retinoids, or other systemic chemotherapy.
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Affiliation(s)
- W W Epinette
- Department of Dermatology, Indiana University School of Medicine, Indianapolis 46223
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23
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Leadon SA, Ganesan AK, Hanawalt PC. Enhanced transforming activity of ultraviolet-irradiated pSV2-gpt is due to damage outside the gpt transcription unit. Plasmid 1987; 18:135-41. [PMID: 2829251 DOI: 10.1016/0147-619x(87)90041-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We have shown that when pSV2-gpt is introduced into human cells by calcium phosphate coprecipitation, the yield of Gpt+ transformants is increased by irradiating the plasmid with 254 nm uv. To elucidate the mechanism underlying this response, we constructed pSV2-gpt molecules in which the uv damage was confined to a particular region: a 3.0-kb region containing the pBR322 sequences and simian virus 40 (SV40) sequences not required for expression of the gpt gene, or a 2.3-kb fragment containing the Escherichia coli gpt gene together with the SV40 early promoter and sequences needed for splicing and polyadenylation. The transforming activity of the plasmid was greatly enhanced by uv damage confined to the 3.0-kb pBR322 region and increased linearly with uv dose up to 1 kJ/m2, but remained relatively constant at doses between 2 and 8 kJ/m2. Positioning the damaged region upstream, or both upstream and downstream, from the gpt transcription unit increased the uv enhancement slightly compared to positioning the damaged region only downstream. In contrast, transforming activity was significantly decreased by damage in the 2.3-kb gpt transcription unit. These results suggest that uv damage outside a selectable marker gene in a plasmid can increase the probability of stable integration of the plasmid into the genome of recipient cells without inhibiting expression of of the gene.
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Affiliation(s)
- S A Leadon
- Department of Biological Sciences, Stanford University, California 94305-5020
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24
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Engler P, Storb U. High-frequency deletional rearrangement of immunoglobulin kappa gene segments introduced into a pre-B-cell line. Proc Natl Acad Sci U S A 1987; 84:4949-53. [PMID: 3110776 PMCID: PMC305224 DOI: 10.1073/pnas.84.14.4949] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
We describe an immunoglobulin gene recombination indicator in which a specific rearrangement via deletion results in the acquisition of a dominant phenotype. The indicator consists of the Escherichia coli xanthine/guanine phosphoribosyltransferase (gpt) gene, whose translation is prevented by the presence of an upstream initiation codon out of frame with respect to the gpt coding sequence. Flanking this barrier initiation codon are the heptamer-spacer-nonamer recognition sequences from a kappa chain variable region (V kappa) and from a kappa chain joining region (J kappa). A proper V-J joint results in the deletion of the translational barrier and allows expression of the selectable marker. When tested by transfection into fibroblasts, no rearrangements were detected and the presence of the barrier initiation codon was sufficient to completely abolish gpt expression in these cells. Similarly, no rearrangements were detected after transfer of the test gene into myeloma cells. However, when the construct was introduced into the pre-B-cell line 38B9, greater than 80% of the transfected cells showed evidence of a specific rearrangement. These rearrangements were associated with the translation of gpt, although no selection for its expression was needed. DNA sequence analysis of six different V-J joints revealed that the rearrangement proceeded with a high degree of accuracy. These results indicate that only very minimal DNA sequences (21 base pairs 5' of the V heptamer and 4 base pairs 3' of its nonamer; less than 45 base pairs 5' of the J nonamer and 3' of its heptamer) are required for efficient rearrangement and provide formal proof that kappa gene segments can rearrange by a deletional mechanism.
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Smith WJ, Tunnacliffe A, Rabbitts TH. Germline sequence of two human T-cell receptor V beta genes: V beta 8.1 is transcribed from a TATA-box promoter. Nucleic Acids Res 1987; 15:4991. [PMID: 2955286 PMCID: PMC305936 DOI: 10.1093/nar/15.12.4991] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
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Shimada T. A rapid and sensitive assay system for bacterial gpt activity in transfected mammalian cells. Nucleic Acids Res 1987; 15:4992. [PMID: 3601663 PMCID: PMC305937 DOI: 10.1093/nar/15.12.4992] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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27
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Abstract
Insulin gene transcription relies on enhancer and promoter elements which are active in pancreatic beta cells. We showed that adenovirus type 5 infection of HIT T-15 cells, a transformed hamster beta cell line, represses insulin gene transcription and mRNA levels. Using expression plasmids transiently introduced into HIT T-15 cells, we showed that adenovirus type 5 E1a transcription regulatory proteins repress insulin enhancer-promoter element activity as assayed with a surrogate xanthine-guanine phosphoribosyltransferase gene. We relate E1a repression of the insulin gene to other examples of repression of enhancer-dependent genes by E1a and discuss the possible relationship of this repression to insulin gene regulation.
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Abstract
Insulin gene transcription relies on enhancer and promoter elements which are active in pancreatic beta cells. We showed that adenovirus type 5 infection of HIT T-15 cells, a transformed hamster beta cell line, represses insulin gene transcription and mRNA levels. Using expression plasmids transiently introduced into HIT T-15 cells, we showed that adenovirus type 5 E1a transcription regulatory proteins repress insulin enhancer-promoter element activity as assayed with a surrogate xanthine-guanine phosphoribosyltransferase gene. We relate E1a repression of the insulin gene to other examples of repression of enhancer-dependent genes by E1a and discuss the possible relationship of this repression to insulin gene regulation.
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Chu G, Hayakawa H, Berg P. Electroporation for the efficient transfection of mammalian cells with DNA. Nucleic Acids Res 1987; 15:1311-26. [PMID: 3029703 PMCID: PMC340526 DOI: 10.1093/nar/15.3.1311] [Citation(s) in RCA: 629] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
A simple and reproducible procedure for the introduction of DNA into mammalian cells by electroporation is described. The parameters involving the cells, the DNA, and the electric field are investigated. The procedure has been applied to a broad range of animal cells. It is capable of transforming more than 1% of the viable cells to the stable expression of a selectable marker.
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Human growth hormone as a reporter gene in regulation studies employing transient gene expression. Mol Cell Biol 1986. [PMID: 3023965 DOI: 10.1128/mcb.6.9.3173] [Citation(s) in RCA: 374] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human growth hormone (hGH) transient assay system described here is based on the expression of hGH directed by cells transfected with hGH fusion genes. Levels of secreted hGH in the medium, measured by a simple radioimmunoassay, are proportional to both levels of cytoplasmic hGH mRNA and the amount of transfected DNA. The system is extremely sensitive, easy to perform, and is qualitatively different from other transient expression systems in that the medium is assayed and the cells themselves are not destroyed. The hGH transient assay system is appropriate for analyses of regulation of gene expression and was utilized here to investigate the effect of the simian virus 40 enhancer on the herpes simplex virus thymidine kinase promoter and the effect of zinc on the mouse metallothionein-I promoter. The expression of hGH can also be used as an internal control to monitor transfection efficiency along with any other transient expression system. All cell types tested thus far (including AtT-20, CV-1, GC, GH4, JEG, L, and primary pituitary cells) were able to secrete hGH into the medium.
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Selden RF, Howie KB, Rowe ME, Goodman HM, Moore DD. Human growth hormone as a reporter gene in regulation studies employing transient gene expression. Mol Cell Biol 1986; 6:3173-9. [PMID: 3023965 PMCID: PMC367053 DOI: 10.1128/mcb.6.9.3173-3179.1986] [Citation(s) in RCA: 216] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The human growth hormone (hGH) transient assay system described here is based on the expression of hGH directed by cells transfected with hGH fusion genes. Levels of secreted hGH in the medium, measured by a simple radioimmunoassay, are proportional to both levels of cytoplasmic hGH mRNA and the amount of transfected DNA. The system is extremely sensitive, easy to perform, and is qualitatively different from other transient expression systems in that the medium is assayed and the cells themselves are not destroyed. The hGH transient assay system is appropriate for analyses of regulation of gene expression and was utilized here to investigate the effect of the simian virus 40 enhancer on the herpes simplex virus thymidine kinase promoter and the effect of zinc on the mouse metallothionein-I promoter. The expression of hGH can also be used as an internal control to monitor transfection efficiency along with any other transient expression system. All cell types tested thus far (including AtT-20, CV-1, GC, GH4, JEG, L, and primary pituitary cells) were able to secrete hGH into the medium.
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Abstract
We have constructed two sets of plasmids for analysis of factors affecting mammalian gene expression. The pOCAT series contains a bacterial chloramphenicol-resistance expression unit (cat) and no eukaryotic promoter. The pUTKAT series contains the same cat unit under the control of the thymidine-kinase promoter of Herpes simplex virus. These plasmids are designed for testing effects of inserted regulatory elements on cat expression after transient transfection of mammalian cells in culture. We demonstrate here that the pOCAT series is useful for studying activities of inserted eukaryotic promoters, and the pUTKAT series is useful for studying activities of inserted eukaryotic enhancers.
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Burke JF, Green MH, Lowe JE. Transient assay, by [3H]guanine incorporation of Escherichia coli xanthine-guanine phosphoribosyl transferase (GPT) in transfected human fibroblasts. Gene X 1985; 40:93-8. [PMID: 3005132 DOI: 10.1016/0378-1119(85)90027-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
We have used [3H]guanine incorporation as a rapid and sensitive assay of xanthine-guanine phosphoribosyl transferase (GPT) activity in SV40 transformed human fibroblasts. The SV40 early promoter is more efficient than the Rous sarcoma virus long terminal repeat for transient expression of the gpt gene. The assay works well in a derivative of AT5BIVA which lacks hypoxanthine-guanine phosphoribosyl transferase (hprt-) and we show here how the assay has been adapted to work in the hprt+ AT5BIVA parent.
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