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)

The expression of the principal opioid peptide gene, preproenkephalin A, is exquisitely regulated by primary afferent inputs to the spinal and medullary dorsal horns. This regulated expression in response to neural synaptic activity has been referred to as trans-synaptic regulation. To define which DNA regions could mediate this trans-synaptic regulation, transgenic 'HEC' mice whose genomes include 193 bp of the human preproenkephalin A promoter fused to a chloramphenicol acetyltransferase (CAT) reporter gene were studied. Mice received unilateral electrical stimulation of the trigeminal ganglion or adjuvant injection into the hindpaw, stimuli known to regulate dorsal horn proenkephalin expression in vivo. CAT activity conferred by this promoter displayed trans-synaptic upregulation with both stimuli. Although the level of the upregulation was 2- to 3-fold higher than the change in the wild type gene, several features of this induction paralleled aspects of the behavior of the wild-type gene: the rapidity of responses to trigeminal ganglion stimulation, the stimulation intensity dependence of responses to trigeminal ganglion stimulation and the time course of upregulation noted following adjuvant injection. Regulatory proteins binding to this restricted promoter region are thus likely to mediate aspects of dorsal horn enkephalin regulation by pain and other somatic stimuli.
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PMID:Primary afferent stimulation acts through a 193 base pair promoter region to upregulate preproenkephalin expression in dorsal horn of transgenic mice. 131 94

The preproenkephalin A gene is a neurotransmitter gene whose expression can be modulated "trans-synaptically" by changes in neuronal activity. DNA sequences lying within 200 base pairs of this gene's transcription start site resemble consensus binding sites for several transcription factor families. In nonneuronal cell cultures, this promoter region is sufficient to mediate gene responses to depolarization, phorbol esters, adenylate cyclase, and calcium fluxes. To assess the role that these cis-acting elements could play in preproenkephalin expression and regulation in vivo, the expression of a construct containing this 200-base-pair region fused to the chloramphenicol acetyltransferase gene was examined in transgenic mice. This promoter confers modest expression in brain, adrenal, and small intestine, with substantially higher levels in testis. These elements confer trans-synaptic regulation in two well-studied models of trans-synaptic preproenkephalin upregulation but not in a third system, underscoring the specificity of the regulatory sequence elements implicated in the synaptic regulation of neuronal genes.
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PMID:Preproenkephalin promoter "cassette" confers brain expression and synaptic regulation in transgenic mice. 137 43

Preproenkephalin metabolism, in the rat, was studied in primary striatal neurons maintained in a chemically defined medium. Acute treatment (30 min) with forskolin (10(-5) M) or phorbol 12 myristate 13 acetate (10(-7) M) resulted, respectively, in a two- and seven-fold increase in methionine-enkephalin secretion. Chronic treatment with forskolin or phorbol 12 myristate 13 acetate (24 h) induced a 100% increase in methionine-enkephalin content (forskolin) and on the other hand a 50% decrease in methionine-enkephalin (phorbol 12 myristate 13 acetate). Both treatments increased preproenkephalin mRNA levels in a time-dependent manner, this augmentation being observable after 180 min by Northern blot analysis and in situ hybridization. These data indicate that under chronic stimulation, with either forskolin or phorbol 12 myristate 13 acetate, proenkephalin turnover is accelerated. However, after stimulation with phorbol 12 myristate 13 acetate, the more potent methionine-enkephalin secretagogue, increased peptide synthesis is not sufficient to replenish methionine-enkephalin intracellular stores. Preproenkephalin gene transcription was analysed by introducing the preproenkephalin gene promoter fused to the bacterial acetyl chloramphenicol transferase reporter gene into primary neurons. Chronic stimulation (48 h) by forskolin (10(-5) M) or phorbol 12 myristate 13 acetate (10(-7) M) of striatal neurons transfected with this fusion gene increased chloramphenicol acetyltransferase activity six-fold and the two effects were additive. These data suggest that the cyclic AMP and the protein kinase C pathways directly activate preproenkephalin gene transcription.
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PMID:Striatal proenkephalin turnover and gene transcription are regulated by cyclic AMP and protein kinase C-related pathways. 165 16

The regulation and possible function of the preproenkephalin gene in testis were studied in vivo in transgenic mice containing: (1) bases -193 to +210 of the human proenkephalin gene and an additional one kilobase of 3' proenkephalin flanking sequence driving expression of bacterial chloramphenicol acetyltransferase (CAT), and (2) the same promoter and flanking sequences driving expression of a rat proenkephalin cDNA. Five lines of mice, designated HEC1-5, expressed the first construct and 10, HER1-10, the second. Each HEC male and many HER males showed dramatic expression of the transgene in the testis, although much lower expression was observed in the brain and other enkephalin-producing tissues. High levels of expression in testis can thus be achieved with a very short promoter region and do not require intron A sequences previously considered necessary. Altered enkephalin expression may affect testicular function. One founder, HER8, displayed grossly abnormal testicular morphology and was completely infertile. A second founder, HER6, had low sperm motility. Two offspring from other lines also displayed subnormal fertility. These studies support a role for specific promoter sequences in testis expression and may further support a significant role for proenkephalin in testicular function.
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PMID:Proenkephalin transgenic mice: a short promoter confers high testis expression and reduced fertility. 791 79

Estrogen receptor (ER) and thyroid hormone receptors (TRs) are ligand-dependent nuclear transcription factors that can bind to an identical half-site, AGGTCA, of their cognate hormone response elements. By in vitro transfection analysis in CV-1 cells, we show that estrogen induction of chloramphenicol acetyltransferase (CAT) activity in a construct containing a CAT reporter gene under the control of a minimal thymidine kinase (tk) promoter and a copy of the consensus ER response element was attenuated by cotransfection of TR alpha 1 plus triiodothyronine treatment. This inhibitory effect of TR was ligand-dependent and isoform-specific. Neither TR beta 1 nor TR beta 2 cotransfection inhibited estrogen-induced CAT activity, although both TR alpha and TR beta can bind to a consensus ER response element. Furthermore, cotransfection of a mutated TR alpha 1 that lacks binding to the AGGTCA sequence also inhibited the estrogen effect. Thus, the repression of estrogen action by liganded TR alpha 1 may involve protein-protein interactions although competition of ER and TR at the DNA level cannot be excluded. A similar inhibitory effect of liganded TR alpha 1 on estrogen induction of CAT activity was observed in a construct containing the preproenkephalin (PPE) promoter. A study in hypophysectomized female rats demonstrated that the estrogen-induced increase in PPE mRNA levels in the ventromedial hypothalamus was diminished by coadministration of triiodothyronine. These results suggest that ER and TR may interact to modulate estrogen-sensitive gene expression, such as for PPE, in the hypothalamus.
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PMID:Estrogen and thyroid hormone interaction on regulation of gene expression. 890 26

CV-1 cells were stably transfected with a preproenkephalin A (PPE) promoter-chloramphenicol acetyltransferase (CAT) reporter plasmid containing -176 to +171 bp of the human PPE gene. Low levels of CAT were expressed constitutively. The reporter enzyme activity was induced by treatment of the cells for 6 h with drugs that increased intracellular cAMP (forskolin and 8-bromo-cAMP), intracellular calcium (A23187), or protein kinase C activity (tetradecanoyl phorbol-4-acetate, TPA) in the presence of the phosphodiesterase inhibitor isobutylmethylxanthine. Co-administration of dexamethasone reduced the magnitude of phorbol ester-stimulated CAT activity by about 50%, while there were smaller but not significant effects on forskolin- or A23187-stimulated expression of this reporter construct. In transient transfections which included the PPE-CAT reporter gene and a glucocorticoid receptor expression plasmid, dexamethasone significantly reduced stimulated expression of the reporter by TPA, forskolin, and A23187. The effect was observed with 10(-8)-10(-6) M dexamethasone and was blocked by the presence of the glucocorticoid antagonist RU486, suggesting that the effect of dexamethasone was mediated by the glucocorticoid receptor. The promoter region contained in this construct lacks a classical glucocorticoid response element or known negative elements; thus, dexamethasone may reduce stimulated expression of the PPE promoter via indirect effects.
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PMID:Dexamethasone represses phorbol ester-, forskolin-, and calcium-stimulated expression of a preproenkephalin A promoter-chloramphenicol acetyltransferase gene via a receptor-mediated mechanism. 891 85