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

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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)

We produced transgenic mice carrying about 3 kb of the 5'-flanking sequence of the rat pyruvate kinase L gene linked to the chloramphenicol acetyltransferase (CAT) structural gene. Expression of the transgene was observed only in tissues in which the endogenous L-type pyruvate kinase is expressed. Dietary glucose or insulin induced similar increases in the levels of CAT and L-type pyruvate kinase mRNAs in the liver. However, the fructose-induced level of CAT mRNA was about 3- and 6- fold lower than those of endogenous L-type pyruvate kinase mRNA in the liver and kidney, respectively, confirming our previous finding that stabilization of the transcripts of the pyruvate kinase L gene is an important regulatory step in fructose induction, especially in the kidney. Thus we conclude that all the cis-acting elements responsible for tissue-specific expression of the L-type pyruvate kinase and its stimulation by dietary components and insulin are localized in the sequence from about nucleotide -3000 to +37 in the pyruvate kinase L gene.
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PMID:Tissue-specific expression of rat pyruvate kinase L/chloramphenicol acetyltransferase fusion gene in transgenic mice and its regulation by diet and insulin. 220 46

Tubulointerstitial changes in the diabetic kidney correlate closely with the decline in glomerular filtration. In this study, we used a cell culture system of mouse proximal tubule epithelial cells to test the effects of glucose on cell growth, size, and matrix biosynthesis. [3H]thymidine incorporation was significantly inhibited in cells grown in 450 mg/dl glucose, compared with cells grown in 100 mg/dl glucose. The cells grown in the higher glucose concentration were slightly larger, their protein content and the total protein synthetic rate were significantly increased, and they secreted approximately twice as much procollagens type IV and type I. Concordantly, steady-state procollagen mRNA levels were also increased: 2.6-fold for the alpha 1(IV) and 2.2-fold for the alpha 2(I) procollagens. Additionally, nuclear run-off studies demonstrated that procollagen gene transcription rate was stimulated approximately 50%; beta-actin transcription rate was not altered. We used chloramphenicol acetyltransferase (CAT) reporter gene constructs to determine whether the increased transcription rate of alpha 2(I) gene was associated with activation of its enhancer sequence. Cells transfected with the enhancer demonstrated more than fivefold increase in CAT activity when cultured in the high-glucose medium. These studies demonstrate a multitude of effects of high ambient glucose concentrations on proximal tubule cell growth and collagen biosynthesis; cell proliferation is decreased although cell hypertrophy occurs. Procollagen gene transcription rate is stimulated and this response contributes to the observed increase in procollagen mRNA content. Activation of an enhancer sequence may be one possible mode through which high glucose levels increase the transcription of procollagen type I, presumably involving trans-acting factor(s).
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PMID:High glucose induces cell hypertrophy and stimulates collagen gene transcription in proximal tubule. 222 Nov 6

Adipose tissue and skeletal and heart muscle, which exhibit insulin-stimulated glucose uptake, express a specific, insulin-responsive glucose transporter. Previously, a cDNA (GT2) encoding this protein was isolated from a mouse 3T3-L1 adipocyte library and was sequenced. Here we report the isolation and characterization of the corresponding mouse gene designated GLUT4. The GLUT4 gene spans 7 kilobases and consists of 11 exons and 10 introns. The start site of transcription was mapped 180 nucleotides upstream of the initial methionine codon. The GLUT4 promoter contains four potential binding sites for the nuclear transcription factor Sp1 as well as a CCAAT box. DNase I footprinting of the GLUT4 promoter with nuclear extracts from undifferentiated and differentiated 3T3-L1 cells revealed that a differentiation-specific nuclear factor binds in the region at position -258 relative to the start site of transcription. Purified CCAAT/enhancer binding protein (C/EBP) was found to bind at the same position. Transient cotransfection into 3T3-L1 preadipocytes of a GLUT4 promoter-chloramphenicol acetyltransferase gene construct that contains the C/EBP binding site, together with a C/EBP expression vector, revealed that C/EBP trans-activates the GLUT4 promoter. We suggest that C/EBP plays an important role in tissue-specific, as well as metabolic, regulation of the insulin-responsive glucose transporter gene.
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PMID:Mouse insulin-responsive glucose transporter gene: characterization of the gene and trans-activation by the CCAAT/enhancer binding protein. 240 78

The amyR2 allele of the Bacillus subtilis alpha-amylase cis-regulatory region enhances production of amylase and transcription of amyE, the structural gene, by two- to threefold over amyR1. The amylase gene bearing each of these alleles was cloned on plasmids of about 10 to 15 copies per chromosome. Transcription of the cloned amylase gene by each amyR allele was activated at the end of exponential growth and was subject to catabolite repression by glucose. The amount of amylase produced was roughly proportional to the copy number of the plasmid, and cells containing the amyR2-bearing plasmid, pAR2, produced two- to threefold more amylase than cells with the amyR1 plasmid, pAMY10. Deletion of DNA 5' to the alpha-amylase promoter, including deletion of the A + T-rich inverted repeat found in amyR1 and amyR2, had no effect on expression or transcription of alpha-amylase. Deletion of DNA 3' to the amyR1 promoter did not impair temporal activation of chloramphenicol acetyltransferase in amyR1-cat-86 transcriptional fusions, but catabolite repression was abolished. When an 8-base-pair linker was inserted in pAMY10 at the same site from which the 3' deletion was made, amylase expression doubled and was repressed less by glucose. Both the deletion and the insertion disrupted four bases at the 3' end of the putative amylase operator region. Site-directed mutagenesis was used to change bases in the promoter-operator region of amyR1 to their amyR2 counterparts. Either change alone increased amylase production twofold, but only the change at +7, next to the linker insertion of 3' deletion site, yielded the increased amylase activity in the presence of glucose that is characteristic of the amyR2 strain. The double mutant behaved most like strains carrying the amyR2 allele.
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PMID:Genetic analysis of the promoter region of the Bacillus subtilis alpha-amylase gene. 250 Apr 16

We have studied the ability of the neu tyrosine kinase to induce a signal for the activation of cell growth-regulated genes. Serum-starved NIH 3T3 cells expressing an epidermal growth factor receptor (EGF-R)/neu construct encoding a hybrid receptor protein were stimulated with EGF and the activation of the neu tyrosine kinase and stimulation of growth factor inducible genes were followed at the mRNA, protein, and activity levels, and compared to the corresponding responses in the neu proto-oncogene and oncogene expressing cells. Induction of the expression of jun mRNAs was an immediate early effect of EGF stimulation, followed by a marked increase in the biosynthesis of the fos/jun transcription factor complex and an increased transcription factor activity as measured by a recombinant transcription unit using chloramphenicol acetyltransferase assays. In distinction, elevated AP-1/PEA-1 activity in the absence of a significant increase in jun and fos expression was characteristic of the neu oncogene-expressing cells. The glucose transporter mRNA increased at 2 h of EGF stimulation and was associated with enhanced glucose transport of the EGF-treated cells. An increase of ornithine decarboxylase (ODC) mRNA and activity followed these changes. In contrast, serum-starved, EGF-treated neu proto-oncogene- and oncogene-expressing cells showed constitutively low and high glucose transporter and ODC activities, respectively. These findings demonstrate that the chimeric EGF-R/neu receptor is capable of activating the expression of both immediate early genes and biochemical activities associated with cell growth stimulation.
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PMID:Activation of the neu tyrosine kinase induces the fos/jun transcription factor complex, the glucose transporter and ornithine decarboxylase. 257 1

The DNA sequences involved in control of S14 gene expression in response to carbohydrate have been studied. The levels of S14 mRNA in primary hepatocytes increase when glucose in the media is elevated from 5.5 to 27.7 mM in the presence of insulin. Following lipofection of primary hepatocytes, plasmids containing S14 genomic sequences from -4316 to +19 relative to the start of transcription were sufficient to confer glucose regulation to the linked marker gene, chloramphenicol acetyltransferase. Deletions of the S14 sequences between -4316 and -1601 led to a significant reduction in glucose-stimulated activity with each successive deletion, suggesting the presence of multiple regulatory elements. The response of the transfected construct containing 4316 base pairs of S14 5'-flanking region mimicked changes in the endogenous S14 mRNA levels in all hormonal and nutritional conditions tested, supporting the physiological significance of the response.
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PMID:Sequences within the 5'-flanking region of the S14 gene confer responsiveness to glucose in primary hepatocytes. 280 35

Treatment of the rat pancreatic acinar cell line AR4-2J with the calcium ionophore A23187 selectively increases, within a few hours, the steady-state level of trypsin mRNA. Addition of the tumor-promoting phorbol ester phorbol 12-myristate 13-acetate potentiates the calcium-induced increase. The mRNA level of the other tested exocrine pancreatic genes decreases. These results were confirmed by DNA transfection experiments, using the 5' flanking region of the trypsin and chymotrypsin genes linked to the coding sequence of the chloramphenicol acetyltransferase (CAT) gene. In calcium-induced cells transfected with the trypsin constructs, an increase in CAT activity was observed, whereas the chymotrypsin constructs revealed a decreased CAT activity. Glucose starvation of AR4-2J cells similarly elicited a selective increase in trypsin mRNA. This selective regulation of trypsin may reflect its role as the key activator of the other zymogen species.
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PMID:Selective regulation of trypsin gene expression by calcium and by glucose starvation in a rat exocrine pancreas cell line. 308 79

Expression of the glucose-regulated protein, GRP78, is markedly increased when cells are placed in a variety of stressful environments (i.e., low glucose medium, calcium ionophore treatment). In this report, the genomic organization of the rat GRP78 gene is described. This gene comprises eight exons and encodes a protein which is highly hydrophilic with the notable exception of several short hydrophobic domains. The first hydrophobic region, 18 amino acids at the N-terminus of the protein, putatively acts as a signal sequence to target GRP78 into the endoplasmic reticulum (ER). By ligating portions of the GRP78 gene and its promoter to the bacterial gene encoding chloramphenicol acetyltransferase (CAT), we created heterologous CAT genes inducible by calcium ionophore A23187. Through immunofluorescence analysis, the intracellular localizations of endogenous GRP78 and fusion CAT proteins under normal growth and A23187-induced conditions are identified. By fusing the GRP78 signal sequence to CAT, we influence intracellular targeting of the CAT protein into the ER.
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PMID:The organization of the rat GRP78 gene and A23187-induced expression of fusion gene products targeted intracellularly. 313 85

Bacillus subtilis 168GR10 was shown to contain a mutation, gra-10, which allowed normal temporal activation of alpha-amylase synthesis in the presence of a concentration of glucose that is inhibitory to activation of amylase synthesis in the parent strain, 168. The gra-10 mutation was mapped by phage PBS-1-mediated transduction and by transformation to a site between lin-2 and aroI906, very tightly linked to amyE, the alpha-amylase structural gene. The gra-10 mutation did not pleiotropically affect catabolite repression of sporulation or of the synthesis of extracellular proteases or RNase and was unable to confer glucose-resistance to the synthesis of chloramphenicol acetyltransferase encoded by the cat-86 gene driven by the amyE promoter region (amyR1) inserted into the promoter-probe plasmid pPL603B. It therefore appears that gra-10 defines a cis-regulatory site for catabolite repression, but not for temporal activation, of amyE expression. The evidence shows that temporal activation and glucose-mediated repression of alpha-amylase synthesis in B. subtilis 168 are distinct phenomena that can be separated by mutation.
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PMID:Isolation and characterization of a cis-acting mutation conferring catabolite repression resistance to alpha-amylase synthesis in Bacillus subtilis. 391 91

Two restriction fragments of Bacillus subtilis DNA were identified which caused the cat-86 gene present on the promoter cloning plasmid pPL703 to be activated predominantly during postexponential growth of host cells. The postexponential increase was observed in both sporulation-positive strains and in a spoOA mutant of B. subtilis. However, the postexponential increase in the cat-86 gene product, chloramphenicol acetyltransferase, was diminished or not observed when the plasmid-containing cells were grown in the presence of excess glucose. The promoter-containing fragment, designated as 33, was mapped to a site on the B. subtilis chromosome adjacent to hisA. The other fragment, 14, mapped to a site adjacent to ctrA. When present on a high-copy vector, both fragments caused a reduction in the sporulation frequency of host cells. Fragment 33 in high copy number conferred on B. subtilis cells three additional phenotypic changes: brown colony color, intracellular inclusions, and, in a protease-deficient mutant, the production of extracellular protease activity. These activities were observed only in postexponential-phase cultures.
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PMID:Restriction fragments that exert promoter activity during postexponential growth of Bacillus subtilis. 630 49


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