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)

Tyrosine hydroxylase (TH) is the rate-limiting enzyme in the biosynthesis of catecholamines. We describe here the isolation of the chicken TH gene and the analysis of 3 kb of its 5' flanking region. The chicken TH transcription unit spans 19 kb. The 60-bp proximal promoter contains a TATA box and a cyclic AMP response element (CRE) sequence. The 5' flanking region contains several AP1-, AP2-, and octamer-like sequences as well as a glucocorticoid response element at position -1.4 kb. A construct containing the 3-kb 5' flanking DNA fused to the chloramphenicol acetyltransferase (CAT) gene was transiently transfected into PC12 cells, and the effect of various effectors was tested. Only forskolin increased the CAT activity, likely owing to the presence of the CRE sequence. Constructs prepared by progressively deleting the 5' flanking DNA were transfected into PC12 and QT6 (quail transformed fibroblasts) cells. In both cell types, the transcriptional activity increased with deletion of the 5' flanking region. These results show that the 60-bp region containing the TATA box and the CRE is sufficient to act as a constitutive promoter for the chicken TH gene and that this region appears to be negatively controlled by upstream sequences.
...
PMID:Chicken tyrosine hydroxylase gene: isolation and functional characterization of the 5' flanking region. 750 87

We reported recently that the gene that encodes tyrosine hydroxylase (TH), the rate-limiting enzyme in the biosynthesis of catecholamines, is regulated by hypoxia in the dopaminergic cells of the mammalian carotid body (Czyzyk-Krzeska, M. F., Bayliss, D. A., Lawson, E. E. & Millhorn, D. E. (1992) J. Neurochem. 58, 1538-1546) and in pheochromocytoma (PC12) cells (Czyzyk-Krzeska, M. F., Furnari, B. A., Lawson, E. E. & Millhorn, D. E. (1994) J. Biol. Chem. 269, 760-764). Regulation of this gene during low O2 conditions occurs at both the level of transcription and RNA stability. Increased transcription during hypoxia is regulated by a region of the proximal promoter that extends from -284 to + 27 bases, relative to transcription start site. The present study was undertaken to further characterize the sequences that confer O2 responsiveness of the TH gene and to identify hypoxia-induced protein interactions with these sequences. Results from chloramphenicol acetyltransferase assays identified a region between bases -284 and -150 that contains the essential sequences for O2 regulation. This region contains a number of regulatory elements including AP1, AP2, and HIF-1. Gel shift assays revealed enhanced protein interactions at the AP1 and HIF-1 elements of the native gene. Further investigations using supershift and shift-Western analysis showed that c-Fos and JunB bind to the AP1 element during hypoxia and that these protein levels are stimulated by hypoxia. Mutation of the AP1 sequence prevented stimulation of transcription of the TH-chloramphenicol acetyltransferase reporter gene by hypoxia.
...
PMID:Hypoxia-induced protein binding to O2-responsive sequences on the tyrosine hydroxylase gene. 755 51

We report the first evidence that differential transcriptional regulation of human chromogranin A (CHGA) gene expression occurs during in vitro treatment of tumorigenic neuroblastoma (NB) cells with retinoic acid (5 microM) and/or dibutyryl-cAMP (1 mM). The CHGA gene encodes a tissue specific protein restricted to cells of the diffuse neuroendocrine system, but also widely expressed among NB tumours. We previously reported that CHGA as well as other neuroendocrine markers are modulated during NB differentiation in vitro. To investigate, at the molecular level, the mechanisms leading to NB tumour cell differentiation during the treatment with biologically active compounds, we sequenced and functionally characterised 2169 bp of a genomic DNA clone encompassing the 5' flanking region of the human CHGA gene. Computer-assisted analysis of the sequence revealed the presence of a cAMP responsive element at positions -56 to -49, and Sp1 binding sites at positions -181 to -176 and -216 to -210. Two novel 9 bp motifs, located at position -462 to -454 and -91 to -83 of the CHGA promoter were identified in the regulatory regions of two other neuroendocrine genes encoding for tyrosine hydroxylase and neuropeptide Y. In addition, in the first 1000 bp of the untranslated 5' region, we found the presence of several putative DNA binding sites of bHLH molecules, a protein family regulating tissue specific differentiation. Transient transfection experiments of chloramphenicol acetyltransferase (CAT) deletion constructs, showed the presence of an active promoter within the first 455 bp upstream from the start site. This region conferred tissue specific expression to a CAT reporter gene. In addition, the transcriptional activity of this fragment was modulated during the induction of differentiation of NB cells treated by retinoic acid and/or dibutyryl-cAMP. These observations provide preliminary data regarding CHGA transcriptional regulation in NB cells, and indicate that retinoic acid and cAMP activate distinct, apparently competitive, transcriptional pathways during NB cell differentiation. The molecular characterisation of the mechanisms regulating CHGA expression in tumour and normal neuroendocrine tissue could lead to the identification of novel molecules potentially relevant for future gene therapy of NB tumours.
...
PMID:Retinoic acid and cAMP differentially regulate human chromogranin A promoter activity during differentiation of neuroblastoma cells. 757 43

Enhancer elements regulating the neuronal gene, tyrosine hydroxylase (TH), were identified in TH-expressing peripheral nervous system PATH and central nervous system CATH cell lines. Mutational analysis in which rat TH 5'-flanking sequences directed chloramphenicol acetyltransferase (CAT) reporter gene expression demonstrated that mutating the cyclic AMP response element (CRE) at -45 base pair reduced expression by 80-90%. A CRE linked to an enhancerless TH promoter fully supported expression. Cotransfection of a dominant-negative CREB protein reduced expression 50-60%, suggesting that the CRE is bound by CREB or a CREB dimerization partner. Although mutating the AP1/dyad (AD) element at -205 base pair only modestly reduced CAT levels, AD minimal enhancer constructs gave 45-80% of wild type expression when positioned at -91 or -95. However, in its native context at -205, the AD could not support expression. In contrast, a CRE, moved from its normal position at -45 to -206, gave full activity. These results indicate that the CRE is critical for TH transcription in central nervous system CATH and peripheral nervous system PATH cells, whereas the AD is less important and its enhancer activity is context-and/or position-dependent. These results represent the first attempts to map regulatory elements directing TH expression in central nervous system cell lines.
...
PMID:The cyclic AMP response element directs tyrosine hydroxylase expression in catecholaminergic central and peripheral nervous system cell lines from transgenic mice. 766 71

Cell type-specific expression of the catecholamine synthetic enzyme, tyrosine hydroxylase (TH), appears to be mediated in part by cis-acting elements located at the 3' end of the human gene. Further delineation of this region indicated sequences corresponding to a CACGTG motif significantly stimulated transcription of a heterologous promoter in various cell types. Mutation of this site led to a complete loss of activity. DNase footprinting, gel retardation, and UV cross-linking experiments indicated that a 74-kDa cellular factor(s) bound specifically to the CACGTG motif in the pheochromocytoma cell line PC12. The size of this protein and its pattern of expression are compatible with those of the CACGTG binding protein TFE3. Transgenic animals were created using a 261-bp human TH 3' fragment encompassing the CACGTG motif in front of a thymidine kinase promoter/chloramphenicol acetyltransferase reporter gene. In three lines of mice this fragment was sufficient to direct a pattern of mRNA expression in peripheral neuroendocrine tissues that mimicked TH mRNA distribution. However, these sequences were not sufficient for CNS-specific patterns of expression. Thus, multiple cell type-specific enhancers may regulate TH gene expression in the CNS and periphery.
...
PMID:The 3' flanking region of the human tyrosine hydroxylase gene directs reporter gene expression in peripheral neuroendocrine tissues. 779 Aug 65

We have produced transgenic (Tg) mice carrying 5.0-kb fragment from the 5'-flanking region of the human tyrosine hydroxylase (hTH) gene fused to a reporter gene, chloramphenicol acetyltransferase (CAT) [Sasaoka et al. (1992) Mol Brain Res 16: 274-286]. In the brain of the Tg mice, CAT expression has been observed in catecholaminergic (CAnergic) neurons and also in non-CAnergic neurons. The aim of the present study is to examine in detail the cell-type specific expression of the hTH-CAT fusion gene in the brain of the Tg mice, by use of immunohistochemistry for CAT, TH, and aromatic L-amino acid decarboxylase (AADC). CAT-immunoreactive cells were found in CAnergic brain regions which contained TH-positive cells, and also in non-CAnergic brain regions which contained no TH-labeled cells. The non-CAnergic brain regions that represented CAT-stained cells were further divided into two groups: (i) regions containing AADC-labeled cells, for example, bed nucleus of the stria terminalis, nucleus suprachiasmaticus, mammillary body, nucleus raphe dorsalis, inferior colliculus, and nucleus parabrachialis, and (ii) regions containing no AADC-positive cells, for example, main olfactory bulb (except A16), accessory olfactory bulb, nucleus olfactorius anterior, caudoputamen, septum, nucleus accumbens, hippocampus, medial nucleus of the amygdala, entorhinal cortex, nucleus supraopticus, and parasubiculum. The results indicate that the 5.0-kb DNA fragment flanking the 5' end of the hTH gene may contain the element(s) specific for neuron-specific TH expression but which may be insufficient to attenuate ectopic expression.
...
PMID:Expression of human tyrosine hydroxylase-chloramphenicol acetyltransferase (CAT) fusion gene in the brains of transgenic mice as examined by CAT immunocytochemistry. 785 98

Tyrosine hydroxylase (TH), the first and rate-limiting enzyme in the biosynthesis of catecholamine neurotransmitters, is expressed within central and peripheral catecholaminergic cells. To delineate DNA sequences necessary for tissue-specific expression of the rat TH gene, transgenic mice were produced containing 0.15 kb, 2.4 kb, and 9.0 kb of 5' flanking sequence fused to the E. coli lacZ (beta-galactosidase) reporter gene. The reporter gene expression in the transgenic animals was monitored by both X-gal histochemical staining and beta-galactosidase immunohistochemistry and compared to TH mRNA and protein expression. Transgenic mice bearing 9.0 kb, but not the smaller constructs with either 2.4 kb or 0.15 kb of 5' flanking sequence, fused to lacZ were able to direct high level expression of beta-galactosidase at levels equivalent to the endogenous TH in central catecholaminergic cells, and to a lesser degree to adrenal gland. Previously, 4.8 kb of 5' flanking region was reported to contain some tissue-specific element(s) determined by chloramphenicol acetyltransferase (CAT) assay using regional brain dissections and was not able to demonstrate cellular localization of the CAT expression [2]. Using histological procedures which allow for spatial resolution, this study demonstrated that the crucial catecholaminergic neuron-specific DNA element(s) resides between -9 kb and -2.4 kb of the 5' flanking region of the rat TH gene; this assertion is substantiated by the high-level of tissue-specific expression of lacZ in catecholaminergic cells.
...
PMID:5' upstream DNA sequence of the rat tyrosine hydroxylase gene directs high-level and tissue-specific expression to catecholaminergic neurons in the central nervous system of transgenic mice. 789 12

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.
...
PMID:Nicotine increases expression of tyrosine hydroxylase gene. Involvement of protein kinase A-mediated pathway. 790 Dec 11

The aim of this study is to examine whether protein products of the bacterial reporter gene are localized within axon terminals in transgenic mice. We have previously created transgenic mice carrying a chimeric gene composed of the human tyrosine hydroxylase gene promoter and the bacterial gene encoding chloramphenicol acetyltransferase (CAT). In the present study, we used an antiserum that detects specifically CAT, and examined immunocytochemically the brain of the transgenic mice. At a light microscopic level, CAT immunoreactivity was found in a dense plexus of fibers in the central nucleus of the amygdala, and in cell bodies of the ventral tegmental area. At an electron microscopic level, in the central nucleus of the amygdala, CAT immunoreactivity was observed in axon terminals. In the ventral tegmental area, the immunoreactivity was found in the perikaryal cytoplasm and on the microtubule of dendrites. The present findings suggest that protein products of the bacterial gene may be transported in axons up to their terminals, and also moved along the microtubules of dendrites.
...
PMID:Protein products of the bacterial reporter gene are found within axon terminals in the brain of transgenic mice. 791 18

Vasoactive intestinal peptide (VIP) is widely recognized as a regulator of tyrosine hydroxylase via a mechanism of trans-synaptic activation. Subsets of adrenal medullary cells and postganglionic sympathetic nerves coexpress the peptide neurotransmitter neuropeptide Y (NPY) with catecholamines. Using PC12 cells transiently expressing a fusion gene in which the bacterial enzyme chloramphenicol acetyltransferase (CAT) is under the control of 700 base pairs of the 5' flanking region of the NPY gene, we have studied the role of VIP and the related peptide pituitary adenylate cyclase activating peptide (PACAP) in regulating NPY gene transcription. Both VIP and PACAP stimulated expression of the NPY gene through activation of cAMP-dependent protein kinase. PACAP was 1000-fold more potent in eliciting this response compared to VIP and activity resided in its N-terminal 27 amino acids. Both VIP and PACAP caused a subpopulation (approximately 50%) of PC12 cells to undergo profound morphological changes in that the cells extended long, slender neurites with prominent growth cones. This change in morphology was unaffected by preincubating cells with inhibitors of either cAMP-dependent protein kinase or calcium/phospholipid-dependent protein kinase. A trophic role for either VIP or PACAP in regulating sympathetic nerve function is proposed.
...
PMID:Vasoactive intestinal peptide stimulates neuropeptide Y gene expression and causes neurite extension in PC12 cells through independent mechanisms. 796 4


<< Previous 1 2 3 4 Next >>

---