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)

To study the mechanism of a novel herpes simplex virus (HSV) activity that stimulates expression of reporter genes containing beta interferon (IFN-beta)-coding sequences, we have established permanent DNA-transfected cell lines that each contain two distinct hybrid genes encoding mRNA species with different half-lives. These reporter genes comprised either the human IFN-beta- or bacterial chloramphenicol acetyltransferase (CAT)-coding and 3' untranslated regions placed under the transcriptional control of the powerful major immediate-early promoter-enhancer region (IE94) from simian cytomegalovirus. Most of the dual-transfected cell lines yielded significant levels of steady-state IE94-CAT mRNA and abundant constitutive synthesis of CAT enzyme activity, whereas no accumulation of IE94-IFN mRNA could be detected. However, infection with HSV type 1 resulted in a 300-fold increase in IE94-IFN-specific mRNA transcripts, compared with no more than 3- to 5-fold stimulation of IE94-CAT-specific mRNA. In contrast, cycloheximide treatment increased stable mRNA levels and transcription initiation rates from both the IE94-IFN and IE94-CAT hybrid genes. Run-on transcription assays in isolated nuclei suggested that induction of IE94-IFN gene expression by HSV type 1 occurred predominantly at the posttranscriptional level. Enhancement of the unstable IFN mRNA species after HSV infection was also observed in cell lines containing a simian virus 40 enhancer-driven IFN gene (SV2-IFN). Similarly, in transient-transfection assays, both SV2-IFN and IE94-IFN gave only low basal mRNA synthesis, but superinfection with HSV again led to high-level accumulation of IFN mRNA. Finally, substitution of the SV2-IFN gene 3' region with poly(A) and splicing signals from the SV2-CAT gene cassette led to stabilization of the IFN mRNA even in the absence of HSV. Therefore, we conclude that HSV infection leads to selective accumulation of IFN-beta mRNA by a posttranscriptional mechanism that is reporter gene specific and promoter independent.
 ...
PMID:Herpes simplex virus infection selectively stimulates accumulation of beta interferon reporter gene mRNA by a posttranscriptional mechanism. 131 84

Expression of the gene for the porcine transplacental iron transport protein uteroferrin (UF) is largely restricted to the uterus, where it is differentially regulated by estrogen (E) and progesterone (P). To study the regulatory mechanisms subserving these effects, a 2-kilobase genomic fragment corresponding to -2005 to 48 nucleotides of the UF gene was ligated up-stream to the reporter gene chloramphenicol acetyltransferase (CAT). This construct (UF-CAT) was transiently transfected into rabbit endometrial (HRE-H9), mouse fibroblastic (AKR-2B), and human choriocarcinoma (JEG-3) cells. The basal gene promoter activity of UF-CAT was exhibited in H9 cells, but not in AKR-2B or JEG-3 cells. In contrast, a simian virus-40 early promoter (SV2) was functional in all three cell lines. The H9 cells were used to examine steroid regulation of the UF gene promoter. The CAT expression in H9 cells primed with E and PRL, but not with E or PRL alone, was stimulated by P. In contrast, basal activity of SV2 in these cells was unaffected by hormones, singly or in combination. To examine the basis for the E/PRL-dependent response to P, levels of P and E receptors in H9 cells were quantified. PRL and E plus PRL increased the number of high affinity sites for P, but had little effect on levels of high affinity sites for E in treated vs. untreated H9 cells. In vivo administration of PRL to cyclic gilts had no effect on levels of endometrial UF mRNA and secreted UF protein; however, E- plus PRL-treated gilts had higher (P less than 0.05) levels of endometrial UF mRNA and luminal UF than PRL-treated gilts. These results demonstrate in vitro functional activity of the UF gene promoter and associated 5' flanking region and suggest that sequences within this region may mediate tissue-specific and steroid hormone-regulated expression of the UF gene. Moreover, interactions among E, PRL, and P modulate UF gene expression in vivo and in vitro.
 ...
PMID:Regulation of the uteroferrin gene promoter in endometrial cells: interactions among estrogen, progesterone, and prolactin. 185 67

The major immediate-early (IE) gene region mapping at coordinates 0.71 to 0.74 in the genome of human cytomegalovirus (HCMV) gives rise to a series of overlapping spliced IE mRNAs that are all under the transcriptional control of the complex IE68 promoter-enhancer region. We show here that one of the phosphorylated nuclear proteins encoded by this region behaves as a powerful but nonspecific trans-activator of gene expression. In transient chloramphenicol acetyltransferase (CAT) assay experiments with Vero cells all relatively weak heterologous target promoters tested, including those of herpes simplex virus IE175 and delayed-early genes, adenovirus E3, the enhancerless simian virus 40 early gene, and the human beta interferon gene, were stimulated between 30- and 800-fold by cotransfection with the HindIII C fragment of HCMV (Towne) DNA. In contrast, expression of the homologous HCMV IE68-CAT gene but not SV2-CAT was specifically repressed. Inactivation mapping studies of the effector DNA, together with dose-response comparisons with subclones from the region, revealed that an intact 7.1-kilobase sequence encompassing both the IE1 and IE2 coding regions (exons 1 to 5) in the major IE transcription complex was required for both the nonspecific trans-activation and autoregulatory responses. The IE1 coding region alone (exons 1 to 4) was inactive, but both functions were restored by insertion of the IE2 coding region (exon 5) in the correct orientation downstream from the IE1 coding region. Internal deletions or inserted terminator codons in IE1 (exon 4) still gave efficient trans-activation and autoregulation, whereas the insertion of terminator codons in IE2 (exon 5) abolished both activities. Finally, IE2 (exon 5) sequences only (under the direct transcriptional control of the strong simian CMV IE94 promoter) were still able to specifically down regulate IE68-CAT expression but failed to exhibit trans-activation properties. Therefore, the IE2 gene product(s) of HCMV appear likely to be key control proteins involved in gene regulation during HCMV infection.
 ...
PMID:trans-activation and autoregulation of gene expression by the immediate-early region 2 gene products of human cytomegalovirus. 283 79