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Query: UNIPROT:P51532 (transcriptional activator)
 6,546 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The proto-oncogene C-jun acts as a transcriptional activator or repressor for numerous cellular genes, and the overexpression of these genes may cause malignant transformation. JunB inhibits c-jun's transforming activities. We investigated the expression of jun genes in renal cell cancer (RCC) and their regulation by cytokines and transforming growth factor beta 1 (TGF-b1). The constitutive expression of c-jun was detected in 39 of 43 fresh frozen RCC, 5 of 10 normal kidneys, and the expression of junB detected in 28 of 34 RCC, 5 of 6 normal kidneys. C-jun was also found expressed in all 10 RCC tumor lines examined and junB was expressed at low levels in 6 of 10 renal tumor lines. TGF-b1 and tumor necrosis factor alpha (TNF-a) have been shown to alter the expression of jun genes in other tissue types. Additionally, TGF-b1, TNF-a, and gamma interferon (g-IFN) were shown to inhibit the growth of RCC. We found that TGF-b1 highly augmented the expression of junB (mean of 34 folds, p less than .05), but did not significantly alter the expression of c-jun, the transforming gene. In contrast, TNF-a significantly enhanced the expression of both c-jun (mean fold enhancement of 2.1, p less than .05) and junB (2.2 folds, p less than .05). Interleukin-2 (IL-2), interleukin-4 (IL-4) and g-IFN did not significantly alter jun expression. The findings presented suggest that c-jun may have a role in inducing malignant transformation in RCC and a novel mechanism by which TGF-b1 may exert its anti-tumor effects, via the activation of junB. Additionally, although TGF-b1, TNF-a, and g-IFN all have anti-proliferative actions on RCC in vitro, they were found to have different effects in altering jun expressions.
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PMID:The expression of C-jun and junB mRNA in renal cell cancer and in vitro regulation by transforming growth factor beta 1 and tumor necrosis factor alpha 1. 140 66

The angiotensinogen gene encodes the precursor protein for the potent vasoconstrictor angiotensin II. Although the gene is expressed in several tissues, the liver is the major source of circulating protein. In previous in-vivo studies we have found that a mini-gene containing 750 bp of 5'-flanking sequence is transcribed in a manner which largely parallels the expression of the endogenous gene. In this report, we characterized conserved elements in the promoter region, in order to determine their role in the transcription of the angiotensinogen gene. Constructs fused to the chloramphenicol acetyl transferase (CAT) reporter gene were transfected into hepatocarcinoma Hep G2 cells as well as into nonhepatic cell lines. We found that 5'-deletion mutant constructs, containing sequences from +25 to -90 bp and -321 to -750 bp, were each able to activate transcription. These constructs contain the TATA box and core promoter sequences, including an Sp1-binding site, and two glucocorticoid responsive elements respectively. In the non-hepatic cell lines, HeLa and Jeg-3, we found that the constructs were transcribed at a much lower rate when compared with the expression of a plasmid containing the Rous sarcoma virus long terminal repeat fused to the CAT gene. Constructs which included sequence 5' to -244 were oestrogen inducible. An element which is conserved between rodent and human angiotensinogen promoters is contained within a sequence which is oestrogen responsive, while another binds the liver-enriched transcriptional activator hepatocyte nuclear factor 1. However, the role of this transactivator in the transcription of angiotensinogen remains uncertain.
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PMID:The function of conserved elements in the promoter of the mouse angiotensinogen gene. 151 23

We have replaced the polyomavirus (Py) enhancer, which is an essential component of the Py origin of DNA replication (ori), with five repeats of a 17-bp oligonucleotide including the yeast GAL4 upstream activating sequence (5xGAL4 sites). Plasmids containing this modified Py ori, designated test plasmids, and plasmids encoding either the GAL4 transcriptional activator protein or various derivatives of this protein were cotransfected into mouse cells which constitutively synthesize a temperature-sensitive Py large tumor antigen (T-Ag). Replication of the test plasmids was monitored by Southern blot determinations of the amounts of plasmid DNA that became resistant to cleavage by the enzyme DpnI. These studies showed that in the presence of a functional T-Ag, the GAL4 protein, and hybrid proteins including the GAL4 DNA-binding domain and the activating domain of the adenovirus E1a or herpesvirus VP16 protein transactivated the modified Py ori. A truncated protein including just the GAL4 DNA-binding domain was inactive in these assays. The authentic GAL4 protein was found to be a more efficient replication transactivator than the hybrid proteins. In contrast, chloramphenicol acetyltransferase assays showed that the hybrid proteins were more efficient transcriptional activators than the GAL4 protein. The extent of the GAL4-dependent replication of a plasmid in which the Py early promoter was deleted was 55% lower than that of a plasmid including the promoter. However, the extents of replication of plasmids including two tandem repeats of the remaining Py origin core and 5xGAL4 sites or two origin cores flanking a single cluster of 5xGAL4 sites were 4.8- and 1.6-fold higher than that of the plasmid including a single copy of each element. The replication of a plasmid including two clusters of 5xGAL4 sites flanking a single origin core was below the limit of detection of our assays. These results indicate that the GAL4 and hybrid transactivators do not activate the Py ori by virtue of their interactions with transcription factors that bind promoter elements. Rather, it appears that these activator proteins may interact with the replication initiation complexes, thereby facilitating or inhibiting the initiation of replication.
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PMID:The yeast GAL4 protein transactivates the polyomavirus origin of DNA replication in mouse cells. 164 81

Using a DNA probe from the DNA-binding portion of the NF-IL6 gene and an antibody against the DNA-binding domain of NF-IL6, we isolated a gene homologous to NF-IL6 in the DNA-binding and leucine zipper domains. This intronless gene, termed NF-IL6 beta encodes a 269-amino acid protein with a potential leucine zipper structure, and the gene product can bind to the CCAAT homology as well as the viral enhancer core sequence, as in the cases of NF-IL6 and C/EBP. This gene is expressed at an undetectable or a minor level in normal tissues but is induced by lipopolysaccharide or inflammatory cytokines, as in the case of NF-IL6. NF-IL6 beta easily forms a heterodimer with NF-IL6 in vitro and the heterodimeric complex binds to the same DNA sequence as the respective homodimers. When examined by transient luciferase assays, NF-IL6 beta is consistently a stronger transactivator than NF-IL6. Furthermore, NF-IL6 beta shows a synergistic transcriptional effect with NF-IL6. These data suggest that NF-IL6 beta is an important transcriptional activator in addition to NF-IL6 in regulation of the genes involved in the immune and inflammatory responses.
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PMID:A member of the C/EBP family, NF-IL6 beta, forms a heterodimer and transcriptionally synergizes with NF-IL6. 174 2

In-frame codon insertion and deletion mutants were constructed in a plasmid containing the sequence that encodes ICP0, a transcriptional activator of herpes simplex virus type 1 (HSV-1). The effect of these mutations was analyzed in a transient expression assay using the promoters for, the IE-0 gene (an immediate early (alpha) gene), the thymidine kinase gene (an early (beta) gene), and the glycoprotein C gene (a late (gamma) gene) fused to reporter cassettes that encoded either beta-galactosidase or chloramphenicol acetyl transferase. Assays were performed in the presence or absence of a plasmid encoding ICP4, the major regulatory protein of HSV-1. Our results demonstrate that ICP0-mediated transactivation varied depending on the position of the insertion in the gene. One region of this protein was consistently shown to be required for full activation of each promoter examined either in the presence or in the absence of ICP4. This region overlaps with a cysteine-rich region and coincides with a transactivator domain identified in another extensive mutational analysis of this sequence. Analysis of the deletion mutants generated in this study demonstrated that the carboxy-terminal regions were required for activation in certain circumstances and that this varied depending on the promoter being assayed and the cell type in which the analysis was performed.
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PMID:Mutational analysis of the sequence encoding ICP0 from herpes simplex virus type 1. 184 23

We have developed a binary transgenic system that activates an otherwise silent transgene in the progeny of a simple genetic cross. The system consists of two types of transgenic mouse strains, targets and transactivators. A target strain bears a transgene controlled by yeast regulatory sequences (UAS) that respond only to the yeast transcriptional activator GAL4. A transactivator strain expresses an active GAL4 gene that can be driven by any selected promoter. The current paradigm uses the murine growth factor int-2 cDNA as the target gene and the GAL4 gene driven by the mouse mammary tumor virus long terminal repeat as the transactivator. Both target and transactivator strains are phenotypically normal. By contrast, the bigenic offspring of these two strains express high levels of the target int-2 gene in each organ expressing the GAL4 transactivator. They also display a characteristic dominant int-2 phenotype that consists of epithelial hyperplasia in mammary and salivary glands, as well as prostatic and epididymal hypertrophy, which results in male sterility.
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PMID:Binary system for regulating transgene expression in mice: targeting int-2 gene expression with yeast GAL4/UAS control elements. 184 61

The human c-myb proto-oncogene is the cellular progenitor of the viral v-myb oncogene and codes for a 75 kD protein involved in growth regulation and differentiation in a number of cells. Fusion proteins in which human c-myb sequences are linked to the DNA binding domain of the yeast transcriptional activator GAL4 can activate transcription from a reporter gene which carries the chloramphenicol acetyl transferase (CAT) gene linked in cis to a repeat of the GAL4 binding site. Deletions of carboxyterminal sequences allowed the identification of the domain responsible for transcriptional activation, which is located between amino acid residues 275 to 327. Deletion of this activator domain results in abrogation of the transcriptional activation. The GAL4-v-myb fusion protein can also activate transcription whereas no transactivation by GAL4-c-myb is observed, indicating that a carboxyterminal domain of c-myb which is absent from v-myb apparently negatively regulates transcriptional activation. Dimer formation which is required for transactivation by GAL4 fusion proteins can, when GAL4 is truncated, be mediated by a region of the c-myb protein upstream of the transactivator domain possibly including the transactivator domain itself but not a putative leucine zipper located downstream of this region.
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PMID:Transcriptional activation by human c-myb and v-myb genes. 218 2

We have shown that the murine c-rel protein can act as a transcriptional transactivator in both yeast and mammalian cells. Fusion proteins generated by linking rel sequences to the DNA-binding domain of the yeast transcriptional activator GAL4 activate transcription from a reporter gene linked in cis to a GAL4 binding site. The full-length mouse c-rel protein (588 amino acids long) is a poor transactivator; however, the C-terminal portion of the protein between amino acid residues 403 to 568 is a potent transcriptional transactivator. Deletion of the N-terminal half of the c-rel protein augments its transactivation function. We propose that c-rel protein has an N-terminal regulatory domain and a C-terminal transactivation domain which together modulate its function as a transcriptional transactivator.
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PMID:The mouse c-rel protein has an N-terminal regulatory domain and a C-terminal transcriptional transactivation domain. 220 16

The NS1 polypeptide of minute virus of mice (MVM) is a potent transcriptional activator of the MVM P38 promoter. The minimum region of this promoter required for transactivation has been identified and termed the transactivation region (tar). However, the function of tar and the biochemical steps involved in NS1-mediated transactivation are not well understood. Here we provide evidence that NS1 binds directly and specifically to tar in a strictly ATP-dependent manner. A DNA fragment containing tar was specifically coimmunoprecipitated with purified baculovirus-expressed MVM NS1, using antibodies directed against NS1 amino- or carboxy-terminal peptides. Using this immunoprecipitation assay, we found that the NS1-tar interaction was enhanced approximately 10-fold by ATP, but subsequent incubation at elevated temperatures in the presence, but not the absence, of MgCl2 caused rapid loss of tar binding. This finding suggests that the tar-NS1 complex has a short half-life under assay conditions which favor ATP hydrolysis. Specific binding was efficiently inhibited by self-ligated oligonucleotides containing the core DNA sequence (ACCA)3, but the same nonligated 20- and 21-mer oligonucleotides were unable to compete effectively, indicating that NS1 only binds to its cognate site when this site is presented on DNA fragments of sufficient size. DNase I footprinting experiments performed in the presence of gamma S-ATP revealed that NS1 protects a 43-bp sequence extending asymmetrically from the (ACCA)2 sequence toward the TATA box of the promoter. NS1 footprints obtained at other sites in the MVM genome were similarly large and asymmetric, all extending approximately 31 bp 5' from the core (ACCA)2-3 sequence. Surprisingly, no footprints were obtained in the absence of gamma S-ATP even under low-stringency binding conditions. However, ATP could be omitted from the reactions if NS1 was first incubated with antibodies directed against its 16-amino-acid carboxy-terminal peptide. Since these antibodies probably create intermolecular cross-links, this finding suggests that NS1 may only bind its cognate site efficiently, or perhaps at all, if the transactivator is first induced to form oligomers. From these data, we hypothesize that ATP binding may also induce NS1 to oligomerize and that such assembly is required before the protein can bind effectively to the tar sequence. The functional implications of the NS1-tar interaction will be discussed.
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PMID:Minute virus of mice transcriptional activator protein NS1 binds directly to the transactivation region of the viral P38 promoter in a strictly ATP-dependent manner. 763 87

The herpes simplex virus transactivator VP16 directs the assembly of a multicomponent protein-DNA complex with cellular components Oct-1 and VCAF-1, contributing a potent carboxyl-terminal acidic activation domain that is essential for activation of gene expression in mammalian cells. We show here that VP16, devoid of this acidic activation domain, functions as a strong transcriptional activator in the yeast Saccharomyces cerevisiae when appended onto a heterologous GAL4 DNA binding domain, as determined by measuring activation of a resident GAL1:lacZ reporter gene. Deletion analysis indicated that sequences contained within the amino-terminal 369 amino acids of VP16 were necessary for transactivation by truncated VP16. Activation by truncated VP16 in yeast was comparable to that observed with a hybrid protein consisting of the GAL4 DNA binding domain linked to the VP16 acidic activation domain. Similar GAL4-VP16 hybrid proteins were only marginally active in mammalian cells. Sequence requirements for transactivation by truncated VP16 can be demarcated from domains of VP16 that are required for interaction with VCAF-1 and for protein-DNA complex formation with Oct-1. Our findings indicate that VP16 contains additional sequences upstream of the acidic activation domain that may play a direct role in transactivation.
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PMID:Transcriptional activation by DNA-binding derivatives of HSV-1 VP16 that lack the carboxyl-terminal acidic activation domain. 774 69


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