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)

Cell signaling events are known to affect human immunodeficiency virus type 1 (HIV-1) replication. Treatment of lymphoid CEM cells with the calcium channel blocker verapamil (25-75 microM) enhanced HIV-1 expression in acute, whole virus infection experiments, despite lowering intracellular calcium levels, ablating the acute rise in intracellular calcium normally seen with infection, and lengthening the doubling time of cell replication. Verapamil had no effect on cell surface CD4 expression. Transfection of CEM cells with plasmids containing the HIV-1 long terminal repeat linked to the chloramphenicol acetyltransferase reporter gene showed that verapamil enhanced expression of the HIV-1 long terminal repeat in a dose-dependent fashion. This effect was abolished by mutations in the binding sites for nuclear factor kappa-B. Electrophoretic mobility shift assays confirmed that verapamil induced nuclear factor kappa-B activity in CEM cells. Thus, verapamil, in high concentrations, can potentiate HIV-1 replication in lymphoid cells, and this effect may be mediated by induction of nuclear factor kappa-B.
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PMID:Effect of the calcium channel blocker verapamil on human immunodeficiency virus type 1 replication in lymphoid cells. 171 54

To study the regulation of insulin gene expression by physiological regulators, primary cultures of rat islet cells were transfected with portions of the rat insulin I gene 5'-flanking sequence linked to the reporter gene chloramphenicol acetyltransferase (CAT). Incubation of the cells in increasing glucose concentrations led to a parallel increase in both CAT activity and CAT mRNA levels. Pretreatment of the cells with the beta-cell-specific toxin streptozotocin reduced CAT activity 97%. Beta-Cell-specific expression of CAT was also demonstrated by co-staining the transfected cells with antisera to both CAT and insulin. Experiments showing a reduction in the response to glucose in the presence of the calcium channel blocker verapamil suggest that calcium plays a role in the glucose response, possibly via regulation of factors interacting with this limited portion of the insulin gene.
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PMID:Regulation of insulin gene expression by glucose and calcium in transfected primary islet cultures. 197 79

Release of prolactin from both normal pituitary cells and rat pituitary tumor (GH) cells is an osmotic process that is dependent upon chloride. The long term growth rate of GH-cells in medium in which chloride was exchanged with isethionate was completely normal, but, by 48 h, isethionate substitution resulted in a 70% decrease in the concentration of internal and secreted prolactin. Isethionate caused a much smaller reduction in growth hormone production (less than 20%). These results suggest that exchange of chloride with isethionate is inhibiting the synthesis of prolactin. Reduction of intracellular levels of prolactin in cells grown in isethionate-containing medium was evident by 30 h, and the level of prolactin was reduced 92% at 96 h. This reduction in the internal concentrations of prolactin was reversed when the cells were returned to normal medium containing chloride with a t1/2 of 48 h. Addition of epidermal growth factor and the calcium channel agonist BAY K 8644 to cells in medium containing chloride increased internal prolactin by 400%, and isethionate exchange reduced the response by 85%. To confirm that isethionate exchange was inhibiting the synthesis of prolactin, mRNA concentrations for prolactin and actin were determined. Both basal and hormone-stimulated levels of prolactin mRNA were reduced 70 to 90% by isethionate exchange, while actin mRNA levels did not change. To determine whether the effect of isethionate was at the level of gene transcription, GH-cells were transfected with a prolactin-chloramphenicol acetyltransferase fusion gene and chloramphenicol acetyltransferase expression was assessed using cells in chloride and isethionate-containing media. Both basal and hormone-stimulated synthesis of chloramphenicol acetyltransferase driven by the prolactin promoter was inhibited by isethionate exchange. These studies demonstrate that exchange of medium chloride with isethionate inhibits the synthesis of prolactin at the level of transcription.
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PMID:Prolactin synthesis in cultured pituitary cells is chloride-dependent. 246 Apr 42

We have studied the role of intracellular calcium sequestration on human immunodeficiency virus (HIV) production by latently infected T-lymphocytic cells. Inhibition of the sarco-endoplasmic reticulum-type calcium transport ATPases by thapsigargin or cyclopiazonic acid induced activation of HIV production in the CEM-derived ACH-2 cells. An approximately 50% depletion of the thapsigargin-sensitive calcium pools as measured fluorimetrically of Indo-loaded cells fully activated virus production. Viral activation was manifest by increases in soluble viral core p24 production, increases in cellular immunofluorescent staining for viral antigens, and increased viral transcription as measured by HIV long terminal repeat-directed expression of the chloramphenicol acetyltransferase reporter gene. Virus induction could be blocked in a dose-dependent manner by the calcium channel blocker econazole. Virus production by the Jurkat-derived HIV-1-inducible J1.1 cells was not significantly stimulated by thapsigargin. These data indicate that intracellular calcium pool function is involved in the control of the transcription of proviral HIV in a cell type-specific manner within the T-lymphoid lineage and that ACH-2 cells represent a useful model for the study of calcium dependent activation of the transcription of proviral HIV.
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PMID:Stimulation of HIV expression by intracellular calcium pump inhibition. 773 Mar 32

We studied the regulation of the hamster CYP11B2 gene in the NCI-H295 cell line, which is known to produce aldosterone in response to stimulation by angiotensin II (AII) and KCl. Ten deletion plasmids harboring the 5'-untranslated region of the CYP11B2 gene were used for chloramphenicol acetyltransferase (CAT) assays. Transient transfections showed progressively increasing basal promoter activity by constructs beyond the TATA box, with a peak occurring with the -167 bp construct which contains putative Adl, Ad2, Ad5 and the newly reported -143/-161 cis-element sequences. The promoter activity was lower with the construct containing the putative Ad3 cis-element and increased with longer constructs. This indicates the presence of both inhibitory and stimulatory cis-elements in this area of the gene. Expression of the reporter gene of all constructs was stimulated by AII and KCl, with the exception of the construct containing only the TATA box, which showed 6-fold and 10-fold increases occurring with the -167 bp deletion plasmid. The patterns of increase in CAT activity with AII and KCI treatment were similar, showing that these two regulators can stimulate hamster CYP11B2 promoter activity through common cis-elements. The calcium channel antagonist nifedipine blocked the stimulatory effects of KCl on CAT activity, showing the involvement of calcium channels in the regulation of CYP11B2 gene transcription by KCl. 12-O-Tetradecanoylphorbol 13-acetate, a known stimulator of the protein kinase C (PKC) signaling pathway, was without significant effect on CAT activity. Bisindolylmaleimide, a specific inhibitor of PKC, had a significant enhancing effect (3.4- to 6-fold), indicating that PKC may negatively regulate the expression of the hamster CYP11B2 gene in NCI-H295 cells. A mutation was induced in the sequence -143/-161 of the - 350 bp construct in order to determine its importance in the regulation of hamster CYP11B2 promoter activity. The stimulatory effects of AII, KCl, forskolin and bisindolylmaleimide on CAT activity were significantly less in the mutant than in the wild type. These results confirm that this cis-element is necessary in maintaining a high level of transcriptional activity in stimulated NCI-295H cells. In conclusion, using NCI-295H transfected cells, we have found that the 5'-untranslated region of the hamster CYP11B2 gene possesses transcriptional activity with stimulatory and also inhibitory cis-elements; CYP11B2 promoter activity can be stimulated by AII, KCl, forskolin, dibutyryl cAMP and bisindolylmaleimide. Our results suggest that this gene is positively regulated through the protein kinase A signaling pathway and through calcium channels, whereas PKC may have a negative regulatory effect upon the transcription of the CYP11B2 gene. Furthermore, we have shown that the cis-element -143/-161 in the 5'-untranslated region of the hamster CYP11B2 gene is important in maintaining a high level of promoter activity in stimulated NCI-295H cells.
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PMID:Transcriptional activity of the hamster CYP11B2 promoter in NCI-H295 cells stimulated by angiotensin II, potassium, forskolin and bisindolylmaleimide. 958 33