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)

We previously reported that 17 beta-estradiol inhibits cytokine-stimulated bioassayable IL-6 and the steady-state level of IL-6 mRNA. To determine the molecular basis of this effect, the transient expression of chloramphenicol acetyltransferase (CAT) reporter plasmid driven by the human IL-6 promoter was studied here in HeLa or murine bone marrow stromal cells (MBA 13.2). 17 beta-estradiol (10(-8) M) completely suppressed stimulated CAT expression in HeLa cells cotransfected with IL-6/CAT constructs and a human estrogen receptor (hER) expression plasmid; but had no effect on reporter expression in HeLa cells not transfected with hER. 17 beta-estradiol also inhibited stimulated expression in MBA 13.2 cells (which express the estrogen receptor constitutively) without the requirement of cotransfection of the hER plasmid. The hormonal effects were indistinguishable between constructs containing a 1.2-kb fragment of the 5' flanking region of the IL-6 gene or only the proximal 225-bp fragment. However, yeast-derived recombinant hER did not bind to the 225-bp segment in DNA band shift assays, nor did the 225-bp fragment compete for binding of an estrogen response element oligonucleotide to yeast-derived estrogen receptor. These data suggest that 17 beta-estradiol inhibits the stimulated expression of the human IL-6 gene through an estrogen receptor mediated indirect effect on the transcriptional activity of the proximal 225-bp sequence of the promoter.
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PMID:17 beta-Estradiol inhibits expression of human interleukin-6 promoter-reporter constructs by a receptor-dependent mechanism. 813 80

Nitrogen mustard (HN2) and quinacrine mustard (QM) both inhibited the binding of NF kappa B to the GC-rich consensus sequence in the HIV long terminal repeat (LTR), as assessed by gel-shift assays. QM also inhibited the binding of OTF-1 to the AT-rich octamer present in the H2B promoter whereas HN2 was inactive. Inhibition of the binding of transcription factors was due to the drug interaction with DNA, since it also occurred when transcription factors were added to DNA after removal of free drug. In Jurkat cells transfected with pI3CAT, where the chloramphenicol acetyltransferase (CAT) gene is under the control of the HIV LTR, both HN2 and QM inhibited CAT gene expression. However, in Jurkat cells transfected with plasmid -147, where the CAT gene is under the control of the H2B promoter, QM inhibited CAT expression but HN2 did not. These results were obtained at concentrations of HN2 or QM that inhibited total DNA and RNA synthesis to a similar extent. The present results suggest that the more selective pharmacological activity of HN2 (HN2 is an active antineoplastic agent whereas QM is inactive and very toxic) might be related to its preferential functional inhibition of GC-rich consensus sequence, possibly important in the regulation of genes involved in the malignant proliferation and behavior of some tumors.
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PMID:Differential inhibition of the DNA binding of transcription factors NF kappa B and OTF-1 by nitrogen mustard and quinacrine mustard: transcriptional implications. 840 25

Elements of the lactose operon were used to study parameters affecting gene expression in cultured cells and transgenic animals. A Lac repressor protein containing a nuclear transport signal was shown to inhibit expression of a reporter gene by interacting with lac operator sequences. In cultured cells, operator sequence, operator placement and induction parameters were all shown to be important for obtaining tight repression of a reporter gene followed by high level expression upon induction. Induction levels were also dependent on the reporter gene, with the luciferase gene yielding higher induction levels than the chloramphenicol acetyltransferase gene. In transgenic animals, the lacI mRNA was not detected in the C57BL/6 mouse strain until the animal was exposed to a demethylating agent. After 5-azacytidine treatment, expression of lacI mRNA was detected in the brain, heart, kidney, lung and ovary. In the FVB transgenic mouse strain, expression of lacI mRNA was detected without 5-azacytidine treatment in the kidney, liver, lung, and testes. Preliminary experiments with double transgenic animals containing both lacI and operator/luciferase transgenes showed a decrease in luciferase expression compared to the luciferase-only animals in both tissue extracts and transgenic fetal primary cultures, although IPTG induction was not achieved in these animals or primary cultures. The applicability and challenges of the system for regulation of gene expression are discussed.
Environ Mol Mutagen 1996
PMID:Parameters affecting the use of the lac repressor system in eukaryotic cells and transgenic animals. 899 Oct 77