A trans-acting factor is responsible for the simian virus 40 enhancer activity in vitro

Sassone–Corsi, Paolo; Wildeman, Alan G.; Chambon, Pierre

doi:10.1038/313458a0

Cited by 197 publications

(136 citation statements)

References 34 publications

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“…The properties of these elements are consistent with the hypothesis that differentiated cells contain positive trans-acting proteins (differentiators) that interact with the specific cis-acting sequences to stimulate the expression of the associated genes. This idea is also consistent with the observations and concepts of other workers (8)(9)(10)(11)(12).…”

supporting

confidence: 80%

Regulation of rat insulin 1 gene expression: evidence for negative regulation in nonpancreatic cells.

Nir¹,

Walker²,

Rutter³

1986

Proc. Natl. Acad. Sci. U.S.A.

170

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Two cis-acting elements, the enhancer and the promoter,, independently contribute to the cell-specific expression of the rat insulin 1 gene. The activities of these elements are presumably mediated by trans-acting factors. We have performed intracellular competition experiments that suggest the presence of a negative factor(s) that represses the enhancer activity in cells that do not express the insulin gene.In these experiments fibroblast cells (COS-7) were transfected with two plasmids: a test plasmid containing the gene for chlorampheiiicol acetyltransferase under the control of the thymidine kinase promoter and the insulin enhancer; and a competitor plasmid containing insulin enhancer sequences and the simian virus 40 origin of replication to permit its replication in the recipient cells. The presence of the competitor plasmid led to a 5-to 6-fold -increase in chloramphenicol acetyltransferase activity as compared with the activity detected when insulin enhancer was absent from either the competitor or the test plasmid. A 5-fold increase in chloramphenicol acetyltransferase activity was also seen when the rat amylase enhancer was present on the competitor plasmid; in contrast the simian virus 40 enhancer exerted no effect. Efficient derepression required additional sequences downstream from those essential for enhancer activity. We propose that the activity ofthe rat insulin 1 enhancer is modulated by a negative tbans-acting factor(s) that is active in cells not expressing insulin but is overridden by the dominant positive trans-acting factor(s) present in insulinproducing cells.During cellular differentiation, cell types acquire the ability to stably express a characteristic set of genes. The. molecular mechanisms by which this occurs are poorly understood. Several genes whose expression is restricted to a specific subset of cells contain cis-acting sequences required for efficient transcription in the appropriate differentiated cells (1-6). We have demonstrated (7) that 5' flanking DNA sequences of the rat insulin 1 gene contain two such cellspecific elements. The properties of these elements are consistent with the hypothesis that differentiated cells contain positive trans-acting proteins (differentiators) that interact with the specific cis-acting sequences to stimulate the expression of the associated genes. This idea is also consistent with the observations and concepts of other workers (8-12). On the other hand, "extinction" of the differentiated phenotype after fusion of differentiated cells with fibroblasts is frequently observed (13). We have also noted that specific sequence deletions in the insulin gene 5' flanking sequences can lead to increases in expression in nondifferentiated cells (unpublished observations). These results are consistent with a role for repressor-like molecules in nonexpressing cells.

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supporting

confidence: 80%

Regulation of rat insulin 1 gene expression: evidence for negative regulation in nonpancreatic cells.

Nir¹,

Walker²,

Rutter³

1986

Proc. Natl. Acad. Sci. U.S.A.

170

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“…It appears, therefore, that enhancers are made up of several sequence motifs which have been combined in various ways during evolution. Results reported elsewhere (Wildeman et al, in preparation) strongly suggest that the role of the various SV40 motifs is to bind specific trans-acting factors involved in enhancer function (Scholer and Gruss, 1984;Mercola et al, 1985;Wildeman et al, 1984;Sergeant et al, 1984;Sassone-Corsi et al, 1985). Thus, the redundancy of enhancer motifs in SV40 may only be apparent if one assumes that some of the trans-acting factors are host-or cell-type specific, and that the ubiquitous activity of the SV40 enhancer is related to the multiplicity of its enhancer motifs.…”

Section: Modular Organisation Of Enhancersmentioning

confidence: 93%

Multiple sequence motifs are involved in SV40 enhancer function.

Zenke¹,

Grundström²,

Matthes³

et al. 1986

The EMBO Journal

493

322

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A systematic mutagenesis of the SV40 enhancer indicates that it spans -100 bp and is composed of at least two distinct DNA domains which exhibit very little enhancing activity on their own. Their association results in a 400-fold enhancement of transcription, virtually irrespective of their relative orientation and, to some extent, of the distance between them. Enhancer activity can also be generated by duplication of either domain. We show also that the activity of each domain is due to the presence of several specific sequence motifs. These motifs are found assorted in different combinations in other viral and cellular enhancers. Key words: transcription/site-directed mutagenesis/promoter/ RNA polymerase B(ll)/simian virus 40 1983;Lusky et al., 1983;Hearing and Shenk, 1983;Veldman et al., 1985). However, such enhancer consensus sequences occur in DNA segments without enhancer properties, and enhancer activity can be generated by duplicating DNA sequences without enhancer activity on their own (Weber et al., 1984;Swimmer and Shenk, 1984), thus questioning the real functional significance of these consensus sequences.Therefore, we decided to determine, at the nucleotide level, the DNA sequences essential for the activity of the prototype SV40 enhancer. Systematic deletions and point mutations have been constructed throughout the enhancer region and their effect on SV40 early transcription investigated in vivo, using a transient expression assay in HeLa cells. We show here that the SV40 enhancer encompasses a large DNA segment of -100 nucleotides containing the 72-bp sequence, but also extending further upstream. Furthermore, the present study reveals that the enhancer is composed of at least two distinct DNA domains which exhibit very little enhancing activity on their own. However, their association results in a dramatic 400-fold enhancement of transcription, virtually irrespective of their relative orientation and, to some extent, of the distance between them. Enhancer activity can also be generated by duplication of either domain. In addition, we show that the activity of each domain is due to the presence of several specific sequence motifs. Various assortments of these motifs are found in other viral and cellular enhancers, suggesting that enhancers are mosaics of a limited number of basic evolutionary related sequence motifs.

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“…For RNA polymerase II enhancers, data is beginning to accumulate suggesting that they are binding sites for some specific protein (12,13). Whether this protein is the RNA polymerase itself, some transcription factor whose eventual role is to translocate to the promoter, or a protein whose role is to stay at the enhancer and help establish "active" chromatin structure is still unclear.…”

Section: Introductionmentioning

confidence: 99%

Xenopusribosomal gene enhancers function when inserted inside the gene they enhance

Labhart

Reeder

1985

Nucl Acids Res

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The ribosomal DNA of Xenopus laevis contains repeated sequence elements in the intergenic spacer region that enhance transcription from the adjacent gene promoter (1,2). Previous work has shown that these RNA polymerase I enhancers influence the target promoter when they are in either orientation, at a distance of several kilobases, and only when they are in cis (3-5). In this work, we further show that enhancer activity is unaffected by inserting the enhancers within the transcription unit whose promoter is being enhanced.In addition, enhancer activity does not interfere with transcription through its sequences. The results suggest that the enhancers act at a point prior to the initiation of transcription and that they are likely to be dispensable once transcription has begun.

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A trans-acting factor is responsible for the simian virus 40 enhancer activity in vitro

Cited by 197 publications

References 34 publications

Regulation of rat insulin 1 gene expression: evidence for negative regulation in nonpancreatic cells.

Regulation of rat insulin 1 gene expression: evidence for negative regulation in nonpancreatic cells.

Multiple sequence motifs are involved in SV40 enhancer function.

Xenopusribosomal gene enhancers function when inserted inside the gene they enhance

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