Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Transcription of the lactoferrin gene is stimulated by estrogen in mouse uterus. To study direct estrogen regulation of this gene at the molecular level, we cloned and analyzed the 5'-flanking region of the mouse lactoferrin gene. Sequence analysis revealed a putative estrogen-responsive element (ERE) overlapping with a chicken ovalbumin up-stream promoter (COUP) element located at position -349 to -329 from the transcription initiation site. The ERE element differed from the consensus ERE sequence by one nucleotide at the second position of the 3' half of the element (G to A); the COUP element differed by one nucleotide from the chicken COUP element. Synthetic oligonucleotide containing the mouse lactoferrin COUP/ERE element was inserted into the reporter chloramphenicol acetyltransferase vector, then transiently transfected into human endometrium carcinoma RL95-2 cells to assess hormone responsiveness. We found that the COUP/ERE element confers estrogen action to both homologous and heterologous promoters. Nuclear proteins from diethylstilbestrol-treated mouse uteri and proteins from estrogen receptor expression vector-transfected RL95-2 whole cell extract bound in vitro to COUP/ERE element specifically, as assessed by band-shift assay. By using antibodies specific to the estrogen receptor and the COUP transcription factor, we demonstrated that both proteins were present in mouse uterine tissue and interacted specifically with the COUP/ERE element, as shown by the superband shift. Competition experiments with specific ERE or COUP oligonucleotides also confirmed the interaction between lactoferrin COUP/ERE element with the estrogen receptor and the COUP transcription factor. Therefore, we named this sequence mERM, the mouse lactoferrin estrogen response module.
Mol Endocrinol 1992 Mar
PMID:Estrogen response module of the mouse lactoferrin gene contains overlapping chicken ovalbumin upstream promoter transcription factor and estrogen receptor-binding elements. 158 12

The peripherin gene, which encodes a neuronal-specific intermediate filament protein, is transcriptionally induced with a late time course when nerve growth factor (NGF) stimulates PC12 cells to differentiate into neurons. We have studied its transcriptional regulation in order to better understand the neuronal-specific end steps of the signal transduction pathway of NGF. By 5' deletion mapping of the peripherin promoter, we have localized two positive regulatory elements necessary for full induction by NGF: a distal positive element and a proximal constitutive element within 111 bp of the transcriptional start site. In addition, there is a negative regulatory element (NRE; -179 to -111), the deletion of which results in elevated basal expression of the gene. Methylation interference footprinting of the NRE defined a unique sequence, GGCAGGGCGCC, as the binding site for proteins present in nuclear extracts from both undifferentiated and differentiated PC12 cells. However, DNA mobility shift assays using an oligonucleotide probe containing the footprinted sequence demonstrate a prominent retarded complex in extracts from undifferentiated PC12 cells which migrates with slower mobility than do the complexes produced by using differentiated PC12 cell extract. Transfection experiments using peripherin-chloramphenicol acetyltransferase constructs in which the footprinted sequence has been mutated confirm that the NRE has a functional, though not exclusive, role in repressing peripherin expression in undifferentiated and nonneuronal cells. We propose a two-step model of activation of peripherin by NGF in which dissociation of a repressor from the protein complex at the NRE, coupled with a positive signal from the distal positive element, results in depression of the gene.
Mol Cell Biol 1992 Jun
PMID:Nerve growth factor-induced derepression of peripherin gene expression is associated with alterations in proteins binding to a negative regulatory element. 158 54

The CYP2C6 gene becomes maximally transcriptionally activated in livers of postpubertal rats. We examined the role of upstream DNA and liver-specific transcription factors in regulation of this promoter by use of transient transfection of heterologous chloramphenicol acetyltransferase gene constructs and vectors containing cDNAs encoding the liver-enriched transcription factors HNF-1 alpha, C/EBP, and DBP. Only DBP was able to activate the CYP2C6 promoter in HepG2 cells. Transactivation was not observed in one mouse and two human nonhepatic origin cell lines tested. Analysis of various constructs in which CYP2C6 upstream DNA was deleted revealed that DNA between -38 to -103 was involved in DBP-mediated activation. A partially purified preparation of DBP produced a footprint between -43 and -64 bp upstream of the transcription start site. A 32P-labeled double-stranded oligonucleotide, containing sequence information corresponding to -40 to -65, bound to both partially pure DBP and extracts from livers of rats as young as 1 week and as old as 25 weeks of age, as assessed by gel mobility shift analysis. This binding was eliminated by coincubation with excess unlabeled -40/-65 double-stranded oligonucleotide and by an oligonucleotide corresponding to the D site of the rat albumin gene. A gel mobility shift-Western immunoblot analysis revealed that the -40/-65 sequence bound to DBP only in liver nuclear extracts from rats older than 3 weeks; maximal binding was observed by 7 weeks of age, and no binding was detected from 1-week-old rat liver extracts. Interestingly, the DBP-binding regions of both CYP2C6 and albumin bind to C/EBP, but this factor is capable of transactivating only the latter gene. Although the DBP-binding regions in these two genes share no obvious sequence similarities, the CYP2C6 region contains consensus palindromic half sites for DBP-related binding proteins and affinity for recombinant DBP of 17-fold greater than that of the D site of albumin. This difference in affinity is probably responsible for the markedly lower amounts of DBP required for half-maximal activation of the CYP2C6 promoter, as compared with the albumin promoter, in transactivation transfection assays. These data indicate that the CYP2C6 gene may be regulated, at least in part, by DBP, a liver transcription factor produced when rats reach puberty that may also be involved in maintenance of albumin gene transcription.
Mol Cell Biol 1992 Jun
PMID:Role of the liver-enriched transcription factor DBP in expression of the cytochrome P450 CYP2C6 gene. 158 73

We have tested the hypothesis that antidepressants affect the expression of the glucocorticoid receptor gene, by looking at glucocorticoid receptor gene promoter activity, glucocorticoid receptor mRNA levels, and glucocorticoid-binding activity after treatment of different cell lines with desipramine. Treatment of LTK- cells or Neuro 2A cells with desipramine produced a 50-200% increase in chloramphenicol acetyltransferase activity transcribed from a 2.7-kilobase glucocorticoid receptor gene promoter region. In cell lines derived from both neuronal and non-neuronal sources, glucocorticoid receptor mRNA concentration doubled after desipramine treatment, and this was associated with a 2-fold higher functional glucocorticoid binding capacity and increased glucocorticoid sensitivity, as measured with the reporter plasmid pMMTVCAT. Antidepressant-induced increases in glucocorticoid receptor gene promoter activity, glucocorticoid receptor mRNA levels, and functional glucocorticoid binding activity suggest a novel mechanism of action for these drugs on the hypothalamic-pituitary-adrenal axis.
Mol Pharmacol 1992 Jun
PMID:Increased glucocorticoid receptor gene promoter activity after antidepressant treatment. 161 6

Bacillus subtilis can exist in a diploid state in which two genetically distinct chromosomes co-exist in the same cell and yet only one of them is expressed, thereby determining the phenotype. Such cells are called non-complementing diploids (Ncds). In this study, two types of experiments are reported which indicate that a previously known pleiotropic gene, spo0A, plays a role in the maintaining the diploid state, as follows. (i) When protoplasts of two Spo0A mutant strains were fused, the resulting products continued to segregate cells of both parental phenotypes for many more divisions than had been reported previously. (ii) When a stable Ncd (an Ncd in which the unexpressed markers are not spontaneously activated at a detectable level) harbouring a chloramphenicol acetyltransferase gene on the silent chromosome was transformed with spo0A null alleles the transformants often expressed chloramphenicol acetyltransferase activity. Together these results indicate that the spo0A gene is involved in maintenance of the diploid state in both unstable and stable Ncds.
Mol Microbiol 1992 Jun
PMID:The spo0A gene is implicated in the maintenance of non-complementing diploids in Bacillus subtilis. 162 79

Inverted sequences of the chloramphenicol acetyltransferase (CAT) reporter gene were fused to a soybean tRNA(met(i)) gene lacking a terminator such that the tRNA(met(i)) sequences caused the co-transcription of CAT antisense sequences by RNA polymerase III. When electroporated into carrot protoplasts, these antisense DNA constructs suppressed CAT enzyme activity expressed from co-electroporated DNAs containing the CAT gene downstream of the cauliflower mosaic virus (CaMV) 35S RNA promoter. Our most effective construct, an antisense sequence complementary to the 3' portion of the CAT gene, inhibited CAT activity five-fold greater than an antisense construct expressed by RNA polymerase II from the cauliflower mosaic virus 35S RNA promoter. These results indicate that antisense sequences transcribed by RNA polymerase III should efficiently suppress gene expression in plants.
Plant Mol Biol 1992 Jul
PMID:Suppression of gene expression in plant cells utilizing antisense sequences transcribed by RNA polymerase III. 162 77

The proteins encoded by cellular and viral src genes are believed to be involved in the transmission of mitogenic signals, the nuclear recipients of which are largely unknown. In this work, we report that four different v-src-transformed cell lines from three different species possess elevated levels of junB transcripts. Transient expression of junB promoter-chloramphenicol acetyltransferase constructs in NIH 3T3 cells was used to demonstrate that the increase in junB transcripts was specifically associated with v-src expression and could not be recapitulated with a c-src, v-H-ras, or v-raf expression vector. Deletion mutants were used to localize the v-src-responsive region in the junB promoter to a 121-nucleotide region encompassing the CCAAT and TATAA elements. This region is distinct from one in the 5' untranslated region of the junB gene which is required to maintain its high-level basal expression. Point mutagenesis of the junB TATAA box completely abolished v-src responsiveness, suggesting that proteins which bind to this element are modified by src transformation. Several v-src and c-src mutants were used to demonstrate that elevated tyrosine kinase activity of src proteins is required for the observed effects on junB expression. Finally, homology between the TATAA box regions of junB and the unrelated but src-responsive gene 9E3/CEF-4 suggests that modulation of gene activity through proteins which bind to this region may be a recurrent, although not exclusive, theme in src transforming action. Our results suggest that src proteins may modulate some nuclear effectors through pathways not involving cellular ras or raf gene products.
Mol Cell Biol 1992 Aug
PMID:Regulation of the junB gene by v-src. 163 Apr 51

Shionogi Carcinoma 115 (SC 115) is an androgen-dependent mouse tumor. Chiba Subline 2 (CS 2) is an androgen-independent subline derived from SC 115. CS 2 contains androgen receptors (AR), but is refractory to androgen and does not exhibit androgen-related responses which are observed in SC 115. In the present study the structure and function of AR in SC 115 and CS 2 are examined using cloned cells. There were no gross rearrangements or deletions in the AR genes of these cell lines when compared by Southern blot analysis with the AR gene in the mouse seminal vesicle. SC 115 and CS 2 expressed AR mRNA of normal size. When the cDNA containing DNA- and androgen-binding domains of the AR genes of both cell lines were amplified by polymerase chain reaction, no mutations were found in these regions. SC 115 and CS 2 were transfected with a plasmid containing a long terminal repeat of mouse mammary tumor virus linked to the chloramphenicol acetyltransferase (CAT) gene. Androgen stimulation of these transfectants resulted in equal elevation of CAT activity. These results indicated that the androgen-independent CS 2 contained functionally normal AR which were identical to those in the androgen-dependent parent tumor.
J Steroid Biochem Mol Biol 1992 Jul
PMID:Loss of androgen dependency with preservation of functional androgen receptors in androgen-dependent mouse tumor (Shionogi Carcinoma 115). 163 20

Quail myogenic cells infected with temperature sensitive (ts) mutants of Rous sarcoma virus (RSV) exhibit a temperature-dependent transformation and block of differentiation. When the cells are allowed to differentiate at the restrictive temperature (41 degrees C) and then shifted back to the permissive temperature (35 degrees C), a sharp reduction in the accumulation of muscle-specific mRNAs is observed, following reactivation of the transforming protein pp60v-src. A kinetic analysis of this down-regulation reveals that the reduction in the accumulation of muscle-specific transcripts occurs fairly rapidly within 6 to 20 h after the shift back, depending on the mRNA analyzed. Studies on transcription of endogenous muscle-specific genes and a transfected chloramphenicol acetyltransferase reporter gene under the control of muscle-specific promoters, at the different temperatures, suggest that the oncogene exerts its control mainly at the transcriptional level. On the contrary, transcription of the CMD1 gene, the avian homolog of the mouse muscle regulatory MyoD gene, is not significantly affected by the oncogene both in proliferating myoblasts and in myotubes shifted back to 35 degrees C. These findings are consistent with the conclusion that v-src blocks myogenesis by controlling transcription of muscle-specific genes independently of cell proliferation. Furthermore, they suggest the existence of an alternative pathway, not requiring the silencing of CMD1 transcription, through which the oncogene exerts its effect.
Mol Cell Biol 1991 Jun
PMID:Transcription of muscle-specific genes is repressed by reactivation of pp60v-src in postmitotic quail myotubes. 164 48

The brain tissues of the rat and mouse express two types of corticosteroid binding proteins, the glucocorticoid (GR) and aldosterone (MR) receptors. Unlike the type II (GR) receptor, type I receptor has a high affinity for aldosterone (ALDO) and corticosterone and is structurally similar to the kidney mineralocorticoid receptor (MR). The results reported in this study provide direct evidence for the interaction of dexamethasone (DEX), triamcinolone acetonide (TA), dexamethasone-21-mesylate (DXM) and 11-deoxycorticosterone (DOC) with human MR expressed in cells by transient co-transfection of a hMR expression vector. The interactions of hMR with DEX, TA, DXM, DOC, promegestone (R5020) and methyltrienelone (R1881) were measured by trans-activation of mouse mammary tumor virus long terminal repeat fused to bacterial chloramphenicol acetyltransferase (MMTV-tk-CAT) in gene co-transfection experiments and by cell free hormone binding assay. The incubation of various steroid hormones in the presence of [3H]ALDO in a competition assay with extracts prepared from HeLa cells co-transfected with hMR expression vector, showed that hMR expressed under these conditions has a high relative affinity for DEX which is similar to ALDO, TA and DOC. Incubation with DXM under these conditions showed very little competition, as was observed with R1881 and R5020. Incubation of the co-transfected cells with DEX, ALDO, DOC, R5020, TA, R1881 and DXM demonstrated that the level of trans-activation did not reflect the previously observed order of binding affinity for the hMR. The level of transactivation was always higher with DEX and TA compared to ALDO and DOC. Analysis of the binding of labeled glucocorticoid regulatory element (GRE) and hMR incubated with DEX, ALDO and DXM by gel shift analysis demonstrated that the trans-activation of MMTV-tk-CAT by hMR is a result of the interaction of hMR with GRE in the MMTV-LTR.
J Steroid Biochem Mol Biol 1991 Jul
PMID:Differential regulation of mouse mammary tumor virus-bacterial chloramphenicol acetyltransferase chimeric gene by human mineralocorticoid hormone-receptor complexes. 164 51


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>