Repression of RNA polymerase III transcription by adenovirus E1A

Sollerbrant, Kerstin; Akusjärvi, Göran; Svensson, Christina

doi:10.1128/jvi.67.7.4195-4204.1993

Cited by 14 publications

(6 citation statements)

References 66 publications

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“…Although the E1A-243R protein has a capacity to activate transcription of certain promoters it has also been described as a potent repressor of transcription (10,12,15,17,49,57,58,59, 60, 61, 62, 63). As we show here, the CR1 domain alone can inhibit SV40 enhancer dependent transcription (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…This hypothesis is in agreement with several other studies. For example, ElA repression of MyoD transactivation and VA RNA transcription has been shown to require EIA sequences encompassing both CR1 and CR2 (15,61). Furthermore, CR2 and sequences in the carboxy-terminal exon have been shown to contribute to transrepression of certain genes and transcription factors (14,22,61,64).…”

Section: Discussionmentioning

confidence: 99%

“…In addition to activating a restricted set of promoters the EIA-243R protein has been shown to repress transcription of many RNA polymerase 11 genes (10,11,12,13,14 and references therein) and the adenovirus VA RNA genes, transcribed by RNA polymerase 11 (15). The CR1 domain is of critical importance for this ElA-mediated repression of transcription (13,16,17,18,19).…”

Section: Introductionmentioning

confidence: 99%

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An adenovirus E1A transcriptional repressor domain functions as an activator when tethered to a promoter

et al. 1994

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The adenovirus E1A protein contains three well conserved regions, designated conserved region (CR) 1, 2 and 3, which are important for the multiple activities ascribed to E1A. The CR3 domain constitutes a prototypic transcription activator, consisting of a promoter targeting region and a transactivating region. Here we demonstrate the existence of a second transactivating region located within amino acids 28 to 90 (essentially the CR1 domain) of the E1A protein. A fusion protein, containing the Gal4 DNA binding domain linked to CR1, was as efficient as the classical CR3 transactivator in activating transcription from a reporter plasmid containing Gal4 binding sites. However, competition experiments suggest that Gal/CR1 and Gal/CR3 work through different cellular targets. The E1A-243R protein has previously been extensively characterized as a repressor of transcription. Here we show that a Gal4 fusion protein expressing the CR1 domain is indeed sufficient for repression of SV40 enhancer activity. Collectively, our results suggest that CR1 functions as an activator if tethered to a promoter and as a repressor in the absence of promoter association.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An adenovirus E1A transcriptional repressor domain functions as an activator when tethered to a promoter

et al. 1994

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“…This hypothesis can be rejected because of the lack of activity of the control viruses Ad-MLP-gD and Ad-VAfull, which also express E1B. Another explanation could be that delivery of the E1B gene favored the transcription of the endogenous VAI transcripts, because the products of the E1A gene repress the synthesis of the VAI and the E1B 19K protein increases it (20). The direct effect of the E1B 19K protein on the transcription of the endogenous VAI gene of the luciferase-expressing viruses can be excluded because of the lack of efficacy of Ad-MLP-gD, which was used as a control because it expresses E1B (Fig.…”

Section: Discussionmentioning

confidence: 99%

High level of transgene expression in cell cultures and in the mouse by replication-incompetent adenoviruses harboring modified VAI genes

Éloit

Adam

Gallais

et al. 1997

J Virol

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Replication-incompetent adenoviruses are currently used in gene therapy trials. Most of the work designed to increase the expression from these vectors concerns the modification of cis sequences of the foreign transcription unit, so as to improve the transcription level or the stability of the mRNA. In this report, we show that an alternative strategy based on the coexpression of modified VAI genes can efficiently increase gene expression both in cell cultures and in animals. The VAI RNA is synthesized mainly during the late phase of the adenovirus cycle and increases the translation of late adenovirus gene products by counteracting the effect of an interferon-induced kinase, the PKR. We have constructed several modified VAI genes in which the central domain was deleted or substituted by exogenous sequences. These modified VAI genes, or the native VAI gene, were cloned into the left part of adenovirus type 5 genomes harboring their own endogenous VAI gene. One of the resulting viruses (Ad-VAr) increased 12.5-to 502-fold the expression level of reporter genes, either expressed as a constitutive cell line from an extrachromosomal DNA or introduced into cells by coinfection with another adenovirus vector. This effect was independent of the promoter, the coding sequence, and the 5 untranslated mRNA sequence and was obvious in the two non-E1-complementing cell lines tested (HeLa and Vero). Coinfection of Ad-VAr with adenoviruses expressing the luciferase gene from the major late promoter or Rous sarcoma virus (RSV) promoter by the intravenous route in mice increased by more than 33 (MLP)to 128 (RSV)-and 4,700 (MLP)-to 30,000 (RSV)-fold the expression level of the reporter gene in the lungs and liver, respectively. The intramuscular coinoculation of Ad-VAr and Ad-MLP-gD (a recombinant adenovirus vaccine expressing gD from the pseudorabies herpes virus) led to a 10-fold decrease in the protective dose of Ad-gD in mice. Ad-VAfull, a similar adenovirus in which the native VAI gene was cloned at the left part of the genome, showed no evidence of efficacy in cell culture and in mice. These results suggest that the use of modified VAI genes expressed at the early phase of the cycle can be helpful in the design of potent adenovirus vectors.

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“…This plasmid is identical to pKGO-007SVRI (33) except that it lacks the E1B coding sequences and the simian virus 40 enhancer (4). The cDNA clone encoding the E1A-243R protein (previously named pML00512S) has been described elsewhere (30). The reporter plasmids E1ACAT (15), E1BCAT (9), E2CAT(p2CAT) (36), E3CAT (pKCAT23) (36), and E4CAT (20) have previously been described.…”

Section: Methodsmentioning

confidence: 99%

AR1 Is an Integral Part of the Adenovirus Type 2 E1A-CR3 Transactivation Domain

Ström

Ohlsson

Akusjärvi

1998

J Virol

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We have previously shown that the nonconserved carboxy-terminal exon of the adenovirus type 2 E1A-289R protein contains two interchangeable sequence elements, auxiliary region (AR) 1 and AR2, that are required for efficient CR3-mediated transcriptional activation of the viral E4 promoter (M. Bondesson, C. Svensson, S. Linder, and G. Akusjärvi, EMBO J. 11:3347–3354, 1992). Here we show that CR3-mediated transactivation of all adenovirus early promoters and the HSP70 promoter requires the AR1 element. We further show that AR2 can substitute for AR1 only when artificially juxtaposed to CR3. AR1 consists of six tandem glutamic acid-proline (EP) repeats and is positioned immediately downstream of CR3. Genetic dissection of AR1 showed that the number of EP repeats in AR1 is critical for CR3 function. Thus, reducing or increasing the number of EP repeats reduces the CR3 transactivation capacity. Furthermore, the introduction of amino acid substitutions into AR1 suggested that the net negative charge in AR1 is of critical importance for its function as an enhancer of CR3-mediated transcriptional activation. Using an in vitro binding approach, we showed that the AR1 element is not part of the CR3 promoter localization signal mediating contact with the Sp1, ATF-2, or c-Jun upstream-binding transcription factors. Previous studies have suggested that the 49-amino-acid sequence constituting CR3 represents the minimal domain required for E1A-induced activation of viral early promoters. Since AR1 was required for efficient CR3-mediated transcriptional activation of all tested promoters, we suggest that the carboxy-terminal boundary for the CR3 transactivation domain should be extended to include the AR1 element.

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Repression of RNA polymerase III transcription by adenovirus E1A

Cited by 14 publications

References 66 publications

An adenovirus E1A transcriptional repressor domain functions as an activator when tethered to a promoter

An adenovirus E1A transcriptional repressor domain functions as an activator when tethered to a promoter

High level of transgene expression in cell cultures and in the mouse by replication-incompetent adenoviruses harboring modified VAI genes

AR1 Is an Integral Part of the Adenovirus Type 2 E1A-CR3 Transactivation Domain

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