Characterization of SV40 enhancer motifs involved in positive and negative regulation of the constitutive late promoter activity; effect of T-antigen

Scieller, Patrick; Omilli, Francis; Borde, J; May, Evelyne

doi:10.1016/0042-6822(91)90918-2

Cited by 9 publications

(13 citation statements)

References 30 publications

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“…We have presented evidence that SV40 large T antigen can interact with a major component of basal transcription complexes, TBP, as well as with an upstream-binding factor, TEF-1, which has previously been suggested to be a significant target for T-antigen-mediated transcriptional activation of the SV40 late promoter (8,20,39). That T antigen activates through such protein-protein interactions has been suspected because (i) it is known that direct binding of T antigen to the DNA is not necessary for transcriptional activation (3, 15, 16, 25, 52); (ii) specific factor binding appears to be altered in the presence of T antigen (15,16); (iii) T antigen requires only a simple promoter structure for activation (17,20, this study); and (iv) T antigen has been reported to modestly activate transcription in vitro (12,47).…”

Section: Discussionmentioning

confidence: 99%

“…3) that contained the glutathione binding site of GST and either (i) full-length WT large T antigen, (ii) full-length WT TEF-1, or (iii) the amino-terminal 167 amino acids of TEF-1, containing the DNA-binding domain (TEFb [50] (OBS). In previous studies, we and others have shown that it is the TEF-1 sites which are necessary for transcriptional activation by T antigen (8,20,39). The GTIIc element has been shown to be an alternative TEF-1 binding site which has a sequence quite different from the sites in the OTE (13).…”

Section: Sv40mentioning

confidence: 99%

“…We and others have shown these sites to be specific upstream elements * Corresponding author. necessary for T-antigen transcriptional activation of the late promoter (8,20,39). We have previously shown that T antigen can activate a relatively simple promoter consisting of repeated TEF-1 binding sites upstream of the 1-globin TATA element (20).…”

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confidence: 99%

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Transcriptional activation by simian virus 40 large T antigen: interactions with multiple components of the transcription complex.

Gruda¹,

Zabolotny²,

Xiao³

et al. 1993

Mol. Cell. Biol.

115

158

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Simian virus 40 (SV40) large T antigen is a potent transcriptional activator of both viral and cellular promoters. Within the SV40 late promoter, a specific upstream element necessary for T-antigen transcriptional activation is the binding site for transcription-enhancing factor 1 (TEF-1). The promoter structure necessary for T-antigen-mediated transcriptional activation appears to be simple. For example, a promoter consisting of upstream TEF-1 binding sites (or other factor-binding sites) and a downstream TATA or initiator element is efficiently activated. It has been demonstrated that transcriptional activation by T antigen does not require direct binding to the DNA; thus, the most direct effect that T antigen could have on these simple promoters would be through protein-protein interactions with either upstream-bound transcription factors, the basal transcription complex, or both. To determine whether such interactions occur, full-length T antigen or segments of it was fused to the glutathione-binding site (GST fusions) or to the Gal4 DNA-binding domain (amino acids 1 to 147) (Gal4 fusions). With the GST fusions, it was found that TEF-1 and the TATA-binding protein (TBP) bound different regions of T antigen. A GST fusion containing amino acids 5 to 172 (region Ti) efficiently bound TBP. TEF-1 bound neither region Ti nor a region between amino acids 168 and 373 (region T2); however, it bound efficiently to the combined region (T5) containing amino acids 5 to 383. The Gal4 fusions demonstrated that no region of T antigen could activate a promoter containing Gal4-binding sites, suggesting that T antigen does not contain an activation domain of the type defined by this assay. However, the Gal4 fusion proteins maintained their ability to activate promoters known to be activated by wild-type T antigen. The fusion with region Ti, which binds only TBP, modestly activated the SV40 late promoter and the simple TEF-1/TATA promoter. Region T5, which binds both TBP and TEF-1, activated each of these promoters to levels equivalent to that of wild-type T antigen. The correlation between the binding of both TEF-1 and TBP and the ability to mediate wild-type levels of transcriptional activation suggests that T antigen causes activation through direct interactions with multiple factors in the transcription complex.The simian virus 40 (SV40) early-gene product large T antigen is a potent viral oncoprotein that interacts with a number of cellular proteins known to affect cell growth and gene expression. These interactions may account for the wide variety of functions attributed to T antigen (reviewed in references 14, 28, and 36). One of these functions is the transcriptional activation of both viral and cellular promoters, which was first detected through studies of activation of the SV40 late promoter (Fig. 1A) (7, 24). Subsequently, large T antigen was shown to be a promiscuous transcriptional activator because of its effect on many viral and cellular promoters (1,17,31,42, 52). This activation of cellular promoters may be as...

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Section: Discussionmentioning

confidence: 99%

Section: Sv40mentioning

confidence: 99%

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Transcriptional activation by simian virus 40 large T antigen: interactions with multiple components of the transcription complex.

Gruda¹,

Zabolotny²,

Xiao³

et al. 1993

Mol. Cell. Biol.

115

158

View full text Add to dashboard Cite

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“…The data indicate that JCV T-antigen can activate transcription from a single transcriptional initiation site. Although these data stand in contrast to the SV40 promoter, where SV40 T-antigen requires both a transcriptional initiator and an upstream element (Casaz et al, 1991 ;Sceiller et al, 1991), the possibility of upstream cryptic sites within pBLCAT3 has not been conclusively ruled out.…”

Section: Figmentioning

confidence: 93%

T-antigen-dependent transcriptional initiation and its role in the regulation of human neurotropic JC virus late gene expression.

Raj

Gallia

Chang

et al. 1998

Journal of General Virology

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The multifunctional protein of papovaviruses, Tantigen, regulates the virus lytic cycle partly by exerting transcriptional control over viral and cellular gene expression. In this study, the ability of the T-antigen of human neurotropic JC virus (JCV) to enhance expression from the virus late promoter has been further examined. By deletion analysis, a T-antigen-responsive region was mapped within the JCV 98 bp enhancer/promoter between nucleotides 139 and 168. Interestingly, T-antigen appears to mediate transactivation by increasing expression from a basal transcriptional initiation site and through a novel T-antigen-dependent initiation site (TADI). The TADI element contains a region hom-

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“…Likewise, simian virus 40 late gene expression is subjected to negative regulation by specific sequences located in the enhancer and in the GC motifs. In presence of the T antigen, these negative elements lose the ability to down-regulate the late promoter (17,26).…”

mentioning

confidence: 99%

Identification of a negative element in the human vimentin promoter: modulation by the human T-cell leukemia virus type I Tax protein.

Salvetti¹,

Lilienbaum²,

Li³

et al. 1993

Mol. Cell. Biol.

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The vimentin gene is a member of the intermediate filament multigene family and encodes a protein expressed, in vivo, in all mesenchymal derivatives and, in vitro, in cell types of various origin. We have previously demonstrated that the expression of this growth-regulated gene could be trans activated by the 40-kDa Tax protein of HTLV-I (human T-cell leukemia virus tpe I) and that responsiveness to this viral protein was mediated by the presence of an NF-KB binding site located between -241 and -210 bp upstream of the mRNA cap site (A. Lilienbaum, M. Duc Dodon, C. Alexandre, L. Gazzolo, and D. Paulin, J. Virol. 64:256-263, 1990). These previous assays, performed with deletion mutants of the vimentin promoter linked to the chloramphenicol acetyltransferase gene, also revealed the presence of an upstream negative region between -529 and -241 bp. Interestingly, the inhibitory activity exerted by this negative region was overcome after cotransfection of a Tax-expressing plasmid. In this study, we further characterize the vimentin negative element and define the effect of the Tax protein on the inhibitory activity of this element. We first demonstrate that a 187-bp domain (-424 to -237 bp) behaves as a negative region when placed upstream either of the NF-KB binding site of vimentin or of a heterologous enhancer such as that present in the desmin gene promoter. The negative effect can be further assigned to a 32-bp element which is indeed shown to repress the basal or induced activity of the NF-KB binding site. Indeed, the negative effect is still observed in HeLa cells treated with phorbol myristate acetate, an inducer of nuclear NF-KB activity. Furthermore, deletion experiments allowed identification within the NE site of 19 bp which bind in vitro a protein complex and which are essential to exert the negative effect. We further demonstrate that expression of the Tax protein is required for overcoming the down-regulation of the NF-KB binding site by the'negative element. Indeed, the negative effect can be relieved in HeLa cells cotransfected with a Tax-expressing plasmid or in a clone of HeLa cells stably producing this viral protein. Collectively, these observations give a new insight into the complex regulation of the human vimentin gene expression and suggest that the Tax protein of human T-cell leukemia virus type I up-regulates this cellular promoter through a dual mechanism consisting of the activation ofthe NF-KB binding site and the relief of the negative effect exerted by the negative element.

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Characterization of SV40 enhancer motifs involved in positive and negative regulation of the constitutive late promoter activity; effect of T-antigen

Cited by 9 publications

References 30 publications

Transcriptional activation by simian virus 40 large T antigen: interactions with multiple components of the transcription complex.

Transcriptional activation by simian virus 40 large T antigen: interactions with multiple components of the transcription complex.

T-antigen-dependent transcriptional initiation and its role in the regulation of human neurotropic JC virus late gene expression.

Identification of a negative element in the human vimentin promoter: modulation by the human T-cell leukemia virus type I Tax protein.

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