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:2.3.1.28 (chloramphenicol acetyltransferase)
5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have developed a novel, highly efficient DNA delivery system to accomplish gene transfer through the asialoglycoprotein receptor-mediated endocytosis pathway. Natural nuclear DNA-binding proteins, the histones (H1, H2a, H2b, H3, and H4), were modified and used as receptor-targeted DNA carriers. Galactosylated with a coupling agent, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, the histones and albumin were conjugated to DNA and then used to transfect HepG2 cells, which display the asialoglycoprotein receptor. The extent of galactosylation was determined for all histone subgroups and albumin with 14C-labeled galactose. A reporter gene for the bacterial chloramphenicol acetyltransferase (CAT), under the control of the 5' long terminal repeat (LTR) of Rous sarcoma virus, was used for comparisons of transfection efficiency of various carrier proteins. The CAT activity resulting from histone H1-mediated transfection was 1.66 unit per 10(6) cells, the highest among histone subgroups. The galactyosylated histone H1 was also eleven times more effective than the asialo-orosomucoid-polylysine. Ten galactosyl units are attached to histone H1 by the galactosylation reaction. Differences in the extent of galactosylation could not explain different transfection efficiencies among various proteins studied in this report. Treatment with galactose oxidase abolished the transfection ability of both the galactosylated histone H1 and asialo-orosomucoid. The intrinsic DNA-binding domains and nuclear location signal sequences are unique to histones as receptor-targeted DNA carriers, and are advantageous for effective gene delivery.
...
PMID:Galactosylated histone-mediated gene transfer and expression. 804 1

We have previously described replication-competent Schmidt Ruppin-A Rous sarcoma virus (RSV)-based retroviral vectors that can be used to deliver and express genes in avian cells. We have continued to modify the prototype vectors to develop a more versatile and efficient system. Substitution of the polymerase (pol) region from the Bryan high-titer RSV (BH-RSV) for the SR-A RSV pol region of these retroviral vectors causes these viruses to replicate more efficiently. We cloned the gag regions from two independent BH-RSV-transformed cell lines and tested whether substituting either of these gag regions would improve the replication and/or gene expression of the vectors. Chimeric vectors were constructed in which the gag region of the prototype vector (SR-A RSV) was replaced with the corresponding segment of BH-RSV gag in vectors that had either the original SR-A RSV pol or the BH-RSV pol region. All vectors contained the bacterial chloramphenicol acetyltransferase gene (CAT). The results indicate that different SR-A RSV and BH-RSV gag-pol chimeras can significantly affect the level of viral and CAT gene expression. The insertion of one of the BH-RSV gag regions, but not the other, gave rise to viruses with unstable genomes.
...
PMID:Effects of the gag region on genome stability: avian retroviral vectors that contain sequences from the Bryan strain of Rous sarcoma virus. 805 45

We have examined the effect of 1,25-dihydroxyvitamin D3 on the promoter activity of the atrial natriuretic peptide (ANP) gene in cultured neonatal rat atrial myocytes. In acute transfection studies 1,25-dihydroxyvitamin D3 inhibited the expression of a human ANP (hANP) promoter-driven chloramphenicol acetyltransferase reporter (-1150 hANP CAT) in a dose-dependent fashion (10(-10)-10(-8) M). When an expression vector for the vitamin D receptor (VDR) (pSVL-VDR) was introduced together with the reporter plasmid, there was a significant ligand-dependent amplification of the vitamin D-dependent inhibition. Deletion analysis of the 5'-flanking sequence localized the suppressible promoter sequence to within 104 base pairs of the transcription start site of the hANP gene. Thyroid hormone, glucocorticoid, estrogen, and retinoic acid receptor were incapable of mimicking the VDR-dependent inhibition. Retinoid X receptor, on the other hand, effected a significant reduction in hANP promoter activity which was at least additive with that produced by the liganded VDR. The VDR-dependent inhibition displayed promoter selectivity. Both the SV40 promoter and a conventional vitamin D response element linked to a truncated SV40 promoter were activated by the liganded vitamin D receptor, whereas the Rous sarcoma virus promoter was unaffected. On the other hand, the cardiac-specific troponin T promoter was suppressed in a fashion similar to ANP. These findings imply a potentially important role for vitamin D3 in the regulation of gene transcription in myocardial cells.
...
PMID:Negative regulation of the human atrial natriuretic peptide gene by 1,25-dihydroxyvitamin D3. 810 67

Transcription of type 1 human immunodeficiency virus (HIV-1) is governed by the viral long terminal repeat (LTR). By using HIV-1 LTR-directed reporter gene systems, we found that the DNA topoisomerase I inhibitor camptothecin inhibits Tat-mediated transactivation of HIV-1 LTR. The 293.27.2 cells that carry a stably transfected HIV-1 LTR-directed lacZ gene expression vector (pNAZ) were used. Inhibitions of LTR were observed at camptothecin concentrations (IC50 about 0.03 microM, which was an order of magnitude lower than for Ro 24-7429), which had minor effects on cell survival, expression of the cellular gene gro, or Rous sarcoma virus-directed chloramphenicol acetyltransferase (CAT) gene expression. Inhibition was also seen with RPMI 8402, which is a human CD4-positive lymphocyte line transiently transfected with a HIV-1 LTR-directed (CAT) gene. Experiments with HIV-1 LTR mutants suggest that transactivation response sequence but not NF-kappa B is responsible for the inhibition by camptothecin. The target for camptothecin may be a cellular factor that is important for the activation of HIV-1 LTR by Tat and thus may offer a potential target for therapy of HIV-1 infection.
...
PMID:Camptothecin inhibits Tat-mediated transactivation of type 1 human immunodeficiency virus. 812 9

The involvement of altered c-jun activity in medroxyprogesterone acetate (MPA)-induced growth responses in human endometrial carcinoma cells is examined in this paper. Under conditions of MPA-induced growth inhibition, c-jun mRNA and protein levels are decreased in Ishikawa cells. This decrease is accompanied by an overall decrease in endogenous AP-1 activity in these cells. Only a transient decrease in c-jun mRNA level without any effect on endogenous AP-1 activity is seen in HEC-50 human endometrial carcinoma cells after MPA treatment. Increased expression and activity of c-jun was achieved in Ishikawa cells by transient transfection of Rous sarcoma virus (RSV)-c-jun alone or RSV-c-jun plus AP-1 binding sites (5x-4-beta-phorobol 12-myristate 13-acetate response element-thymidine kinase-chloramphenicol acetyltransferase), respectively. These treatments were accompanied by an increase in cell numbers due to MPA treatment in Ishikawa cells. In contrast, MPA treatment of mock-transfected, RSV-jun-B-transfected, or 5x-4 beta-phorbol 12-myristate 13-acetate response element-thymidine kinase-chloramphenicol acetyltransferase alone transfected Ishikawa cells resulted in the expected decrease in cell numbers. The data presented in this paper are consistent with the hypothesis that altered c-jun activity in a target cell can alter proliferative responsiveness to MPA and suggest that such a mechanism may be associated with resistance to hormonal manipulative therapies used in the treatment of both human breast and endometrial cancer.
...
PMID:Enhanced c-jun activity alters responsiveness to medroxyprogesterone acetate in Ishikawa human endometrial carcinoma cells. 814 69

Varicella-zoster virus (VZV) open reading frame 4 (ORF4) encodes a protein with a predicted molecular weight of 51,540 presenting amino acid sequence homology with the immediate-early regulatory protein ICP27 of herpes simplex virus type 1. To investigate the regulatory properties of the ORF4 gene product, we performed a series of transient expression assays in Vero cells, using a plasmid expressing ORF4 as effector and several VZV genes and heterologous genes as targets. The VZV target plasmids contained promoter/regulatory regions from genes belonging to the three putative VZV kinetic classes fused to the chloramphenicol acetyltransferase (CAT) gene. The heterologous target plasmids consisted of promoter/regulatory regions of human cytomegalovirus, Rous sarcoma virus, and human immunodeficiency virus type 1 fused to the reporter gene. These experiments demonstrated that the ORF4 gene product activated expression of ORF62 in a dose-dependent fashion but had no effect on the expression of the three other putative immediate-early genes (ORF4, ORF61, and ORF63). When various amounts of ORF4 were transfected in the presence of early gene promoters, dose-dependent transactivation was evidenced with the thymidine kinase gene (ORF36) and the major DNA-binding protein gene (ORF29) promoters; interestingly, little activity was detected with the promoter of the DNA polymerase gene (ORF28). No activation of late gene expression, represented by the glycoprotein I and glycoprotein II genes, was seen even over a wide range of concentrations of input ORF4 plasmid. Expression of pCMVCAT, pRSVCAT, and pHIVCAT was also stimulated by the ORF4 gene product. CAT mRNA analysis showed that activation of VZV target promoters occurs at the transcriptional and/or posttranscriptional level.
...
PMID:Characterization of the regulatory functions of varicella-zoster virus open reading frame 4 gene product. 838 35

Several vectors containing (1) regulatory regions from Rous sarcoma virus (RSV), human cytomegalovirus (CMV), and herpes simplex thymidine kinase (TK); (2) introns from early or late SV40 genes and from trout growth hormone gene (tGH); (3) chloramphenicol acetyltransferase gene (CAT); and (4) transcription terminators from SV40 were transfected into carp EPC cells, salmon CHSE cells, tilapia TO2 cells, quail QT6 cells, and hamster CHO cells. CAT activity was measured in extracts from several cell lines 3 days after transfection and in the fish EPC stable clones. The CMV and RSV promoters were the most potent in all cell types. The intron from late SV40 genes (VP1 intron) worked properly in QT6 and CHO cells but not in EPC and very weakly in TO2 cells. The tGH intron was efficient in all cell types but preferentially in fish cells. The small t intron from SV40 was processed in all cell types. The small t and, to a lesser extent, the tGH introns amplified expression of cat gene in stable clones, in comparison to the transiently transfected cells. These results indicate that elements from mammalian genes may not be properly recognized by the fish cellular machinery and in an unpredictable manner. This finding suggests that vectors prepared to express foreign genes in transfected cultured fish cells and transgenic fish should preferably contain DNA sequences from fish genes or, alternatively, those sequences from mammalian genes that have been previously proved to be compatible with the fish cellular machinery.
...
PMID:Efficiency of introns from various origins in fish cells. 839 51

We have investigated the regulated expression of genes injected into the heart of large mammals in situ. Reporter constructs using the chloramphenicol acetyltransferase gene under the control of muscle-specific beta-myosin heavy chain (beta-MHC) or promiscuous (mouse sarcoma virus) promoters were injected into the canine myocardium. There was a linear dose-response relation between the level of gene expression and the quantity of plasmid DNA injected between 10 and 200 micrograms per injection site. The level of reporter gene expression did not correlate with the amount of injury imposed on the cardiac tissue. There was no regional variation in expression of injected reporter genes throughout the left ventricular wall. By use of both the mouse sarcoma virus and a muscle-specific beta-MHC promoter, reporter gene expression was one to two orders of magnitude greater in the heart than in skeletal muscle. Expression in the left ventricle was threefold higher than in the right ventricle. Chloramphenicol acetyltransferase activity was detected at 3, 7, 14, and 21 days after injection, with maximal expression at 7 days after injection. Statistical analysis of coinjection experiments revealed that coinjection of a second gene construct (Rous sarcoma virus-luciferase) is useful in the control of transfection efficiency in vivo. Furthermore, using reporter constructs containing serial deletions of the 5' flanking region of the beta-MHC gene, we performed a series of experiments that demonstrate the utility of this model in mapping promoter regions and identifying important regulatory gene sequences in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Gene injection into canine myocardium as a useful model for studying gene expression in the heart of large mammals. 843 91

Neuronal migration in brain is followed by differentiation of committed neurons and simultaneous apoptosis of uncommitted preneuronal cells due to a limiting supply of trophic factors and nutrients. We have dissected differentiation and apoptosis by designing a simple in vitro model for this nutrient deprivation using engineered neuronal cell lines stably transfected with a promoterless segment (G-21) of the intronless human serotonin1A receptor (5-HT1A-R) gene. Despite the use of widely different heterologous promoters (cytomegalovirus and Rous sarcoma virus) for the stable expression of G-21, a dramatic increase in expression of the 5-HT(1A)-R (five- to 15-fold) and its mRNA was always observed during degeneration and apoptosis of nutrient-deprived neuronal cells. Involvement in this induction of a 170-bp 5'-end untranslated sequence (5'-UT) (tail end of the 500-bp natural promoter) of G-21 was confirmed by stable transfection of neuronal cells with an SV-40 promoter-driven construct harboring the 5'-UT and the reporter chloramphenicol acetyltransferase (CAT) cDNA. Presence of the 5'-UT resulted in a threefold increase in CAT expression during nutrient deprivation in randomly chosen clones. The induction was also observed in the endogenous 5-HT1A-R, expressed by embryonic day 16 mouse hippocampal neurons, subsequent to nutrient deprivation and onset of degeneration. A trophic role of the 5-HT1A-R has been suggested in earlier studies. Considering the example of protective heat shock proteins, which are induced during various types of stress, our results suggest that stressed neuronal cells undergoing degeneration and apoptosis synthesize increased levels of 5-HT1A-R as a final attempt to survive.
...
PMID:Induction of the serotonin1A receptor in neuronal cells during prolonged stress and degeneration. 863 58

The A20 gene product is a novel zinc finger protein originally described as a tumor necrosis factor alpha (TNF)-inducible early response gene in human umbilical vein endothelial cells (HUVEC). Its described function is to block TNF-induced apoptosis in fibroblasts and B lymphocytes, but more recently it has also been shown to play a role in lymphoid cell maturation. The mechanism of action of A20 is unknown. The aim of our study was to assess the effect of A20 upon endothelial cell activation. By transfecting bovine aortic endothelial cells (BAEC) with A20 as well as reporter constructs consisting of the promoters of genes known to be up-regulated during endothelial cell activation, i.e. E-selectin, interleukin (IL)-8, tissue factor (TF), and inhibitor of nuclear factor kappaBalpha (IkappaBalpha), we demonstrate that A20 expression inhibits gene up-regulation associated with TNF, lipopolysaccharide (LPS), phorbol 12-myristate 13-acetate (PMA), and hydrogen peroxide (H2O2)-induced endothelial cell (EC) activation. The mechanism of action of A20 is in part, or totally, due to the blockade of nuclear factor kappaB (NF-kappaB), as shown by its ability to suppress the activity of a NF-kappaB reporter. This effect is specific, as A20 does not block a noninducible, constitutively expressed reporter, Rous sarcoma virus-luciferase (RSV-LUC); nor does it block the c-Tat-inducible, NF-kappaB-independent reporter, human immunodeficiency virus-chloramphenicol acetyltransferase (HIV-CAT). How A20 blocks NF-kappaB is unclear, although we demonstrate that it does not affect p65 (RelA)-mediated gene transactivation. The inhibition of endothelial cell activation by A20 is a novel function for A20.
...
PMID:A20 blocks endothelial cell activation through a NF-kappaB-dependent mechanism. 866 99


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>

---