Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HeLa S3 cells, which have been fractionated into sequential and synchronous cell cycle phase-specific fractions, express c-fos at twice the basal levels in the earliest part of G1 phase. To determine whether this peak in c-fos synthesis has regulatory significance, a DNA construct was prepared which contained the human c-fos gene under the transcriptional control of the SV40 promoter complex. The pc-fos(human)-1 gene (9 kilobases) was inserted into the eukaryotic expression vector pSG5 (4.076 kilobases) at the EcoRI site. Electroporation with an exponentially decaying pulse was employed to cotransfect this construct into HeLa S3 cells along with the plasmids pRSVcat and the neomycin-resistance plasmid pF beta fos3' neo. The level of transient expression of each plasmid was determined. Transfection efficiency was determined as percentage fluorescent cells by measurement of immunofluorescence with a chloramphenicol acetyltransferase (CAT) antibody. Efficiency of transfection ranged up to approximately 5% of the cells. Transfected cells were selected on the basis of resistance to Geneticin (G418) at 400 micrograms/mL. CAT fluorescence and Geneticin resistance were employed to select permanently transformed cell lines. Compared with exponentially growing cells, successfully transfected cell lines expressed more than twice the level of c-fos mRNA as determined by dot-blot analysis and 16 times more of the 62-kilodalton c-fos protein as determined by Western blot analysis. As all cells in the population were not stable c-fos transfectants, this value is likely to be an underestimate of the overexpression level. In addition, expression was under the control of a strong serum induction insensitive promoter, unlike the native c-fos promoter.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Growth of HeLa S3 cells cotransfected with plasmids containing a c-fos gene under the control of the SV40 promoter complex, pRSVcat, and G418 resistance. 132 4

Lipofection, a recently-developed method for gene transfer, was tested in secretory epithelial cells. Lipofection facilitated both transient DNA transfection with plasmids containing the chloramphenicol acetyltransferase gene and stable transfection with a plasmid containing the neomycin resistance gene, which confers resistance to the antibiotic G418 (Geneticin). Gene transfer occurred efficiently in a rabbit kidney medullary thick ascending limb cell line and in primary cultures of rabbit tracheal epithelial cells. The method was also effective in Simian virus 40-transformed human airway cells isolated from a normal individual and from a patient with cystic fibrosis (CF). Cytotoxicity was minimal, particularly when the time of exposure to the lipofectin-DNA was limited to 3-5 h (less than 5% cell loss). Thus, the lipofection method is useful for gene transfer in a variety of secretory epithelial cells and should be ideal for studies of defective secretory epithelial cell function in CF.
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PMID:Gene transfer by lipofection in rabbit and human secretory epithelial cells. 259 76

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