Negative regulation of viral enhancers in undifferentiated embryonic stem cells

Gorman, Cornelia M.; Rigby, Peter; Lane, David P.

doi:10.1016/0092-8674(85)90109-6

Cited by 337 publications

(247 citation statements)

References 22 publications

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“…It is particularly interesting that, in undifferentiated embryonal carcinoma cells, enhancer-independent viral transcription is antagonized by the presence of enhancer sequences, while in the differentiated state, the enhancer sequences are absolutely required for transcription (19). The situation in MEL cells may parallel these findings, although we do not yet have evidence for enhancer-independent retroviral transcription in uninduced MEL cells, perhaps because of the nature of our enhancer deletions.…”

Section: Resultsmentioning

confidence: 47%

“…Evidence that the site of action of the repression of transcription also lies in the enhancer sequences of the retroviral LTR came from studies using the enhancerless (5,19). It is particularly interesting that, in undifferentiated embryonal carcinoma cells, enhancer-independent viral transcription is antagonized by the presence of enhancer sequences, while in the differentiated state, the enhancer sequences are absolutely required for transcription (19).…”

Section: Resultsmentioning

confidence: 99%

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Regulated expression of a complete human beta-globin gene encoded by a transmissible retrovirus vector.

Cone¹,

Weber-Benarous²,

Baorto³

et al. 1987

Mol. Cell. Biol.

150

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We introduced a human 0-globin gene into murine erythroleukemia (MEL) MATERIALS AND METHODSPlasmid constructions. A detailed account of the construction of pSVX has been presented previously (6). pSVXenwas constructed by first digesting a single long terminal repeat (LTR)-containing plasmid completely with XbaI and partially with PvuIl and then religating the appropriate fragment after addition of SalI linkers. A fragment containing the deleted LTR was then introduced in place of the 3' LTR of pSVX. All P-globin vectors were constructed by inserting a BclI-linkered 3.0-kb human 3-globin fragment, from the HpaI site to the PstI site, into the BamHI site of pSVX or pSVXen-. The human ,-globin gene and the SP6 plasmids used for synthesis of probes complementary to mouse and human f-globin mRNAs were kindly provided by

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Section: Resultsmentioning

confidence: 47%

Section: Resultsmentioning

confidence: 99%

Regulated expression of a complete human beta-globin gene encoded by a transmissible retrovirus vector.

Cone¹,

Weber-Benarous²,

Baorto³

et al. 1987

Mol. Cell. Biol.

150

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“…On the other hand, evidence for negative control elements has also been reported: when cells expressing a differentiated liver phenotype are fused to fibroblasts, one typically observes loss or extinction of the differentiated product, a result which can be most easily attributed to activity of trans-acting repressors (13). Negative regulation is also involved in modulating the activity of viral enhancers in embryonic cells (29) and in cells expressing the adenovirus EIA gene (30,31). Further, the activity of the rat insulin 1 enhancer is reduced in pancreatic cells expressing the EJA gene (unpublished data).…”

Section: Discussionmentioning

confidence: 99%

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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“…In addition, negative regulation of the enhancer is also an important mechanism for the control of heavy-chain expression. Negative-enhancer regulation may be a general mechanism for tissue-specific expression as negativeregulatory elements also have been found that are associated with the insulin 1 gene enhancer (Laimins et al 1986;Nit et al 1986), the B-interferon gene enhancer {Goodbourn et al 1986), and viral enhancers in embryonic stem cells (Gorman et al 1985), and mouse mammary epithelial cells (Langer and Ostrowski 1988).…”

Section: Models For Enhancer Repressionmentioning

confidence: 99%

“…Subsequently, enhancers have been found in association with a variety of cellular genes^ many of which seem to function in a tissue-specific or inducible manner (Chan dler et al 1983;Walker et al 1983;Gorman et al 1985;Rossi and deCrombrugghe 1987). Thus, enhancer regula tion appears to be an important aspect of developmental gene regulation.…”

mentioning

confidence: 99%

A developmental-specific factor binds to suppressor sites flanking the immunoglobulin heavy-chain enhancer.

Scheuermann¹,

Chen²

1989

Genes Dev.

108

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We identified a novel nuclear protein, NF-|jiNR, that binds to multiple sites flanking the immunoglobulin heavy-chain enhancer. The expression of NF-|jiNR shows a unique developmental pattern; the activity is present in all cells representing early stages of B-cell development, but is absent from more mature cells that express a high level of immunoglobulin heavy chains. NF-|iNR also is present in most cell lines outside of the B-cell lineage (e.g., T cells, macrophages, and fibroblasts). The binding sites for NF-|jiNR correlate very well with cisacting negative regulatory elements of the heavy-chain enhancer defined previously. Indeed, when the segments bound by NF-^.NR are deleted from the enhancer, it is now found to function as a positive transcription element in T cells and macrophages. Taken together, these results suggest that NF-|jiNR may function as a negative regulator of enhancer function. The observation that the segments bound by NF-ftNR correspond to the segments bound to the nuclear matrix suggests an intriguing model not only of how enhancers might function but also of how negative regulation might occur.

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Negative regulation of viral enhancers in undifferentiated embryonic stem cells

Cited by 337 publications

References 22 publications

Regulated expression of a complete human beta-globin gene encoded by a transmissible retrovirus vector.

Regulated expression of a complete human beta-globin gene encoded by a transmissible retrovirus vector.

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

A developmental-specific factor binds to suppressor sites flanking the immunoglobulin heavy-chain enhancer.

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