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)

Nicotine, a major component of tobacco smoke, stimulates catecholamine secretion and activates catecholamine biosynthetic enzymes such as tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH) in adrenal medullary cells. We investigated the effect of long term treatment with nicotine on TH and DBH gene expression in rat PC12 pheochromocytoma cells. Nicotine treatment for 1-2 days increased both the TH and DBH mRNA levels. The effect of nicotine on TH mRNA seems to be transcriptionally mediated. Deletion analysis of the 5' promoter region of the TH gene showed that the region containing a cyclic AMP/calcium regulatory element is sufficient for the nicotinic induction of TH. Nicotine did not induce TH mRNA or chloramphenicol acetyltransferase reporter activity in mutant PC12 cells deficient in protein kinase A activity. However, the deficiency in protein kinase A activity did not affect the elevation in intracellular calcium concentration caused by nicotine, indicating normal receptor function. These results suggest that a cAMP-mediated pathway plays a crucial role in the long term nicotine-induced activation of the TH gene.
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PMID:Nicotine increases expression of tyrosine hydroxylase gene. Involvement of protein kinase A-mediated pathway. 790 Dec 11

Protein kinase C (PKC) activation after treatment of human neuroblastoma SK-N-BE(2)C cells with phorbol 12-myristate 13-acetate (PMA) was found to enhance transcription of the human dopamine beta-hydroxylase (DBH) in those cells. To identify which cis-acting element is responsive to the PMA treatment during DBH gene expression, we employed transient transfection assays with serially deleted constructs of the human DBH gene's 5' upstream region fused to the chloramphenicol acetyltransferase (CAT) gene. Treatment of transfected cells with PMA resulted in an approximate threefold increase in CAT expression for all deletion constructs ranging from -978 bp to -262 bp, while the enhancement did not occur with a construct shortened to -114 bp. The region between -262 and -114 bp from the initiation site of transcription contains several cis-regulatory elements including a cyclic AMP response element (CRE) and putative AP1 and YY1 sequences. Site-directed mutagenesis of those cis-acting elements were performed to identify which of the elements mediated the PMA-induced transcriptional enhancement. Substitution of bases in the putative AP1 site containing in part a putative YY1 sequence did not effect the PMA inducibility. However, specific mutations in the CRE sequence abolished the PMA-inducible effect. Changing the CRE sequence into an authentic AP1 sequence (TGACGTCC --> TGACTCA) did not affect the PMA inducibility, suggesting that AP1 factors might interact with the new AP1 site upon PKC activation. A specific PKC inhibitor, GF109203X, completely inhibited the stimulatory effect of PMA on the expression of the human DBH gene. PMA induced an increase in the DBH mRNA level as detected by Northern blot analysis. Gel retardation showed that the binding of nuclear factors to CRE, putative YY1, and AP1 was sequence specific. Our data suggest that the enhancement of the human DBH gene expression by PMA treatment is mediated by the CRE motif in the 5' upstream region of the gene, and occurs via a PKC-dependent pathway.
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PMID:A protein kinase C-activating phorbol ester enhances transcription of the human DBH gene through a cyclic AMP response element in SK-N-BE(2)C cells. 942 17

Prostaglandin E2 (PGE2) enhances transcription of the human dopamine beta-hydroxylase (DBH) gene in human neuroblastoma SK-N-BE(2)C cells. To identify a PGE2-responsive cis-acting element in the human DBH gene, serial deletion constructs of the human DBH 5'-upstream region fused to the chloramphenicol acetyltransferase (CAT) reporter gene were transiently transfected into SK-N-BE(2)C cells. Treatment of the transformed cells with PGE2 increased CAT expression two- to threefold in all constructs except where the promoter region was shortened beyond position -114 bp. There are several cis-regulatory elements in the region between -262 and -114 bp from the transcription initiation site that include a cyclic AMP response element (CRE) and a putative AP1 sequence. We presupposed that the CRE and AP1 might be candidates for PGE2 stimulation, and therefore, used site-directed mutagenesis to change the CRE and AP1 motives and test which of the two elements mediated the transcriptional enhancement. Only a specific mutation within the CRE sequence abolished the PGE2 effect. In addition, cotransfection with an expression vector expressing PKA inhibitor resulted in the specific blockage of the PGE2 effect on DBH gene expression. Northern blot analysis revealed that the increase in DBH gene transcription caused by PGE2 results in elevated DBH mRNA levels. Gel-retardation and competition assays confirmed that the binding of nuclear factors to the CRE site is sequence specific. Our data, therefore, indicate that PGE2 enhances the transcription of the human DBH gene. The effect is mediated by the CRE motif through activation of PKA.
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PMID:Stimulation of human DBH gene expression by prostaglandin E2 in human neuroblastoma SK-N-BE(2)C cells. 948 16

The synaptic action of norepinephrine is terminated by NaCl-dependent uptake into presynaptic noradrenergic nerve endings, mediated by the norepinephrine transporter (NET). NET is expressed only in neuronal tissues that synthesize and secrete norepinephrine and in most cases is co-expressed with the norepinephrine-synthetic enzyme dopamine beta-hydroxylase (DBH). To understand the molecular mechanisms regulating human NET (hNET) gene expression, we isolated and characterized an hNET genomic clone encompassing approximately 9. 5 kilobase pairs of the 5' upstream promoter region. Here we demonstrate that the hNET gene contains an as-yet-unidentified intron of 476 base pairs within the 5'-untranslated region. Furthermore, both primer extension and 5'-rapid amplification of cDNA ends analyses identified multiple transcription start sites from mRNAs expressed only in NET-expressing cell lines. The start sites clustered in two subdomains, each preceded by a TATA-like sequence motif. As expected for mature mRNAs, transcripts from most of these sites each contained an additional G residue at the 5' position. Together, the data strongly support the authenticity of these sites as the transcriptional start sites of hNET. We assembled hNET-chloramphenicol acetyltransferase reporter constructs containing different lengths of hNET 5' sequence in the presence or the absence of the first intron. Transient transfection assays indicated that the combination of the 5' upstream sequence and the first intron supported the highest level of noradrenergic cell-specific transcription. Forced expression of the paired-like homeodomain transcription factor Phox2a did not affect hNET promoter activity in NET-negative cell lines, in marked contrast to its effect on a DBH-chloramphenicol acetyltransferase reporter construct. Together with our previous studies suggesting a critical role of Phox2a for noradrenergic-specific expression of the DBH gene, these data support a model in which distinct, or partially distinct, molecular mechanisms regulate cell-specific expression of the NET and DBH genes.
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PMID:A previously undescribed intron and extensive 5' upstream sequence, but not Phox2a-mediated transactivation, are necessary for high level cell type-specific expression of the human norepinephrine transporter gene. 1003 44