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)

Growth factors coordinately regulate a variety of genes associated with pathological states including tumor invasion and metastasis. Overexpressed epidermal growth factor receptor (EGFR) on tumor cell surfaces is associated with enhanced cell attachment and migration into extracellular matrices, which promotes tumor aggressiveness. We have demonstrated that epidermal growth factor (EGF) up-regulates the cell surface adhesion molecule CD44 at both the mRNA and protein levels on mouse fibroblasts expressing full-length wild-type EGFR (NR6-WT) but not on EGFR-deficient cells (NR6-P). This increases cell attachment to hyaluronic acid. In this investigation, transcriptional regulation of CD44 by EGF was confirmed by defining an EGF-regulatory element. By employing human CD44 gene promoter-chloramphenicol acetyltransferase (CAT) constructs transfected into NR6-WT cells, EGF inducibility was observed within a 120-base pair (bp) DNA fragment located 450 bp upstream of the RNA initiation site. Differential EGF inducibility was found among different cell lines chosen, indicating a 3.2- and 1.8-fold enhancement in DU145 cells carrying exogenous wild-type EGFR and in MCF-7 cells, respectively, while minimal EGF induction was found in cervical cancer HeLa cells. Utilizing gel shift assays, a time-dependent increase of DNA-protein complex formation was found upon EGF stimulation in NR6-WT cells but not in NR6-P cells. Based upon these observations, a novel 22-bp EGF regulatory element (ERE) (5'--604CCCTCTCTCCAGCTCCTCTCCC-583-3') was isolated from the CD44 gene promoter. This ERE conferred DNA-protein binding ability in vitro, as well as the full functional recovery of EGF inducibility of CAT activity when linked to a homologous CD44 promoter or a SV40 promoter driving a CAT reporter gene. A two-base mutation of the ERE completely eliminated its binding activity as well as its EGF inducibility of CAT expression. Our studies indicate that EGF induces CD44 gene expression through an interaction between a specific ERE and putative novel transcriptional factor so as to regulate cell attachment to extracellular matrix.
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PMID:Epidermal growth factor induces CD44 gene expression through a novel regulatory element in mouse fibroblasts. 916 42

We previously mapped the sequences responsive to insulin/glucose stimulation and polyunsaturated fatty-acid suppression in the proximal promoter region between positions -104 and -20 of the ATP citrate-lyase (ACL) gene [Fukuda, H., Iritani, N., Katsurada, A. & Noguchi, T. (1996) FEBS Lett. 380, 204-207]. To investigate further the regulatory DNA sequences required for stimulation and suppression of this gene, primary cultured hepatocytes were transfected with plasmids containing the 5'-flanking sequences of the rat ACL gene fused to the chloramphenicol acetyltransferase (CAT) gene. When two copies of the sequences spanning -64 to -41 (linked to ACLcat20) were used for transfection, CAT activity significantly increased in response to insulin/glucose treatment. This increase was inhibited by addition of polyunsaturated fatty acid. Mutational analysis of this region showed that sequences between -55 and -51 are essential for recognition and interaction with trans-acting factors. Gel mobility shift assays using the sequence from -64 to -41 as a probe revealed nuclear factor(s) from rat liver that specifically complexed with the sequences. In addition, by antibody supershift assays, we have detected the binding of the transcriptional factor Sp1 at the G+C-rich region located within -64 to -41 of the ACL promoter. On the other hand, the formations of DNA-protein complexes with Sp1 binding site or ACL(-64 to -41) were decreased in rats fed a high-carbohydrate diet in comparison with those in rats fasted or fed a polyunsaturated fatty-acid-rich diet. Cotransfection studies in rat hepatocytes, with the Sp1 expression vector and ACLcat constructs, showed the inactivation of the promoter. These results demonstrated that the region from -64 to -41 of the ACL gene was responsible for stimulation due to insulin/glucose, the stimulation was suppressed by polyunsaturated fatty acid, and Sp1 may be involved in the regulation.
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PMID:Transcriptional regulatory region for expression of the rat ATP citrate-lyase gene. 926 90

Endothelial cell surface expression of VCAM-1 is one of the initial steps in the pathogenesis of atherosclerosis. The inflammatory response transcription factor nuclear factor (NF)-kappaB plays an important role in the regulation of VCAM-1 expression by various stimuli including tumor necrosis factor (TNF)-alpha. Other transcription factors may modulate this response through interaction with NF-kappaB factors. Since c-Fos/c-Jun (activating protein-1 (AP-1)) are expressed in vascular endothelium during proinflammatory conditions, we investigated the role of AP-1 proteins in the expression of VCAM-1 by TNF-alpha in SV40 immortalized human microvascular endothelial cells (HMEC). TNF-alpha induced expression of both early protooncogenes, c-fos and c-jun. The ability of TNF-alpha to activate the kappaB-motif (kappaL-kappaR)-dependent VCAM-1 promoter-chloramphenicol acetyltransferase (CAT) reporter gene lacking a consensus AP-1 element was markedly inhibited by co-transfection of the expression vector encoding c-fos ribozyme, which decreases the level of c-fos by degrading c-fos mRNA, or c-fos or c-jun oligonucleotides. Conversely, co-transfection of c-Fos and c-Jun encoding expression vectors potentiated the p65/NF-kappaB-mediated transactivation of the VCAM-1 promoter-CAT reporter gene. Furthermore the c-Fos encoding expression vector potentiated by 2-fold the transactivation activity of a chimeric transcriptional factor Gal/p65 (containing the transactivation domain of p65 and the DNA binding domain of the yeast transcriptional factor Gal-4). Consistent with the promoter studies, curcumin and NDGA, inhibitors of AP-1 activation, markedly inhibited the ability of TNF-alpha to activate the expression of VCAM-1 mRNA levels at concentrations that did not inhibit the activation of NF-kappaB. In gel mobility supershift assays, the antibodies to c-Fos or c-Jun inhibited the binding of TNF-alpha-activated nuclear NF-kappaB to the kappaL-kappaR, suggesting that both c-Fos and c-Jun interacted with NF-kappaB. These results suggest that AP-1 proteins may mediate the effect of TNF-alpha in the regulation of VCAM-1 expression through interaction with NF-kappaB factors in endothelial cells.
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PMID:Role of activating protein-1 in the regulation of the vascular cell adhesion molecule-1 gene expression by tumor necrosis factor-alpha. 946 19

The human TR4 orphan receptor (TR4) is a member of the nuclear receptor superfamily. It functions as a transcriptional factor which regulates and controls many important physiological functions. It has been documented that TR4 may bind as a homodimer to a DNA response element containing two direct repeats of the AGGTCA consensus motif. Surprisingly, our data reveal that the expression of the human steroid 21-hydroxylase (21-OHase) gene could be repressed by TR4 via the monomeric AGGTCA motif (-228TR4RE) at its 5' flanking region (nucleotide numbers 1431-1444, 5'-GGAAAAAGGTCAGG-3'). Electrophoretic mobility shift assay showed specific binding with a dissociation constant of 0.4 nM between TR4 and the monomeric -288TR4RE motif. However, TR4 does not form heterodimers with either retinoid X receptor alpha or SHP (short heterodimer partner) orphan receptor. Additionally, both dual-luciferase and chloramphenicol acetyltransferase assays demonstrated that TR4 can function as a repressor via the -228TR4RE of the 21-OHase gene. In conclusion, our data suggest that TR4 may bind to a monomeric DNA response element and play an important role in the suppression of the 21-OHase gene expression.
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PMID:TR4 orphan receptor represses the human steroid 21-hydroxylase gene expression through the monomeric AGGTCA motif. 1147 8

Vascular endothelial growth factor (VEGF) is an angiogenic growth factor known to be up-regulated in ischemic heart and hypoxic endothelial cells. However, the transcriptional regulation of VEGF in hypoxia-induced angiogenesis is not fully understood. Transcriptional enhancer factor-1 (TEF-1) is a transcriptional factor family that can regulate many genes expressed in cardiac and skeletal muscle cells by binding to myocyte-specific chloramphenicol acetyltransferase heptamer elements in the promoters of these genes. In this study, we demonstrated that related TEF-1 (RTEF-1), a member of the TEF-1 family, is up-regulated in hypoxic endothelial cells. Overexpression of RTEF-1 increases VEGF promoter activity and VEGF expression. Sequential deletion and site-directed mutation analyses of the VEGF promoter demonstrated that a GC-rich region containing four Sp1 response elements, located between -114 and -50, was essential for RTEF-1 function. This region is beyond the hypoxia-inducible factor-1alpha binding site and does not consist of M-CAT-related elements. By electrophoretic mobility shift assay, RTEF-1 was found to interact with the first Sp1 residue (-97 to -87) of the four consecutive Sp1 elements. Binding activity of RTEF-1 to VEGF promoter is also confirmed by chromatin immunoprecipitation. In addition, induction of VEGF promoter activity by RTEF-1 results in an increase of angiogenic processes including endothelial cells proliferation and vascular structure formation. These results indicate that RTEF-1 acts as a transcriptional stimulator of VEGF by regulating VEGF promoter activity through binding to Sp1 site. In addition, RTEF-1-induced VEGF promoter activity was enhanced in a hypoxic condition, indicating that RTEF-1 may play an important role in the regulation of VEGF under hypoxia.
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PMID:RTEF-1, a novel transcriptional stimulator of vascular endothelial growth factor in hypoxic endothelial cells. 1507 66


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