What does the locus control region control?

Epner, Elliot; Kim, Chul G.; Groudine, Mark

doi:10.1016/0960-9822(92)90379-o

Cited by 24 publications

(5 citation statements)

References 15 publications

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“…A range in the level of transgene expression (up to 10-fold), however, has been found indicating LCR function can be subject to position effects (Ryan et al, 1989). Our analysis of the tyrosinase -12 kb HS-site in transgenic mice as well as experiments investigating LCR function of the human f-globin locus are limited by the use of minigene constructs (Epner et al, 1992). the human CD2 gene , the human oxglobin cluster (Vyas et al, 1992;Sharpe et al, 1993) and the phosphoenolpyruvate carboxykinase (PEPCK) gene (Cheyette et al, 1992).…”

Section: Discussionmentioning

confidence: 99%

“…the human CD2 gene , the human oxglobin cluster (Vyas et al, 1992;Sharpe et al, 1993) and the phosphoenolpyruvate carboxykinase (PEPCK) gene (Cheyette et al, 1992). Our analysis of the tyrosinase -12 kb HS-site in transgenic mice as well as experiments investigating LCR function of the human f-globin locus are limited by the use of minigene constructs (Epner et al, 1992). For the tyrosinase gene it remains unclear whether the identified upstream element would be sufficient to guarantee transgene expression as an independent regulatory unit when embedded in the natural chromatin context.…”

Section: Discussionmentioning

confidence: 99%

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A cell-specific enhancer far upstream of the mouse tyrosinase gene confers high level and copy number-related expression in transgenic mice.

et al. 1994

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The tyrosinase gene encodes the key enzyme of melanin production and is tightly regulated during development. A yeast artificial chromosome covering the mouse tyrosinase gene has been shown to rescue completely the albino phenotype of recipient mouse strains, conferring copy number‐dependent, position‐independent expression. To investigate the presence of cis‐acting regulatory elements responsible for the appropriate expression of the tyrosinase gene, DNase I hypersensitive site mapping was performed. A melanoma cell‐specific DNase I hypersensitive site was identified at ‐12 kb upstream of the tyrosinase gene. Functional analysis of the corresponding cis‐acting element in transgenic mice and transient transfection assays revealed properties of a strong cell‐specific enhancer. RNA expression levels of the transgene correlate with copy number, which is reflected in coat colour and eye pigmentation of transgenic mice. Full enhancer activity in transient transfections is obtained with a minimal sequence of 200 bp. Protein binding analysis reveals the presence of a melanoma cell‐specific complex which might contribute to the faithful expression of the tyrosinase gene.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A cell-specific enhancer far upstream of the mouse tyrosinase gene confers high level and copy number-related expression in transgenic mice.

et al. 1994

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“…If this protein binding model applies to the CAD replicon, the effects of transcription factors would have to be transferred over at least 8 kb, the distance between the CAD OBR and the promoter. The substantial effects of the ␤-globin locus control region (located 60 kb from the ␤-globin OBR) on chromatin structure, gene activity, and replication timing provides precedent for the involvement of distantly located DNA sequences on DNA replication (36,40,41).…”

Section: Discussionmentioning

confidence: 99%

Identification of an Origin of Bidirectional DNA Replication in the Ubiquitously Expressed Mammalian CAD Gene

Kelly

Rose

Draper

et al. 1995

Molecular and Cellular Biology

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Most DNA replication origins in eukaryotes localize to nontranscribed regions, and there are no reports of origins within constitutively expressed genes. This observation has led to the proposal that there may be an incompatibility between origin function and location within a ubiquitously expressed gene. The biochemical and functional evidence presented here demonstrates that an origin of bidirectional replication (OBR) resides within the constitutively expressed housekeeping gene CAD, which encodes the first three reactions of de novo uridine biosynthesis (carbamoyl-phosphate synthetase, aspartate carbamoyltransferase, and dihydroorotase). The OBR was localized to a 5-kb region near the center of the Syrian hamster CAD transcriptional unit. DNA replication initiates within this region in the single-copy CAD gene in Syrian baby hamster kidney cells and in the large chromosomal amplicons that were generated after selection with N-phosphonacetyl-L-aspartate, a specific inhibitor of CAD. DNA synthesis also initiates within this OBR in autonomously replicating extrachromosomal amplicons (CAD episomes) located in an N-phosphonacetyl-L-aspartate-resistant clone (5P20) of CHOK1 cells. CAD episomes consist entirely of a multimer of Syrian hamster CAD cosmid sequences (cCAD1). These data limit the functional unit of replication initiation and timing control to the 42 kb of Syrian hamster sequences contained in cCAD1. In addition, the data indicate that the origin recognition machinery is conserved across species, since the same OBR region functions in both Syrian and Chinese hamster cells. Importantly, while cCAD1 exhibits characteristics of a complete replicon, we have not detected autonomous replication directly following transfection. Since the CAD episome was generated after excision of chromosomally integrated transfected cCAD1 sequences, we propose that prior localization within a chromosome may be necessary to ''license'' some biochemically defined OBRs to render them functional.The replicon hypothesis proposes that DNA replication initiates within specific cis-acting sequences referred to as origins (8, 62) (Fig. 1). Origins interact with trans-acting factors that enable the DNA duplex to unwind into a suitable template for DNA synthesis. A direct genetic prediction of this elegant model is that the capacity for replication is transferable; replication-incompetent DNA should replicate upon introduction of an origin. Indeed, extrachromosomal replicons that follow the cellular replication program in Escherichia coli and Saccharomyces cerevisiae can be generated by inserting a small DNA fragment into replication-defective plasmids (15, 37). Mutations within sequences that confer autonomous replication (ARS) reduce initiation efficiency or prevent it from occurring (63,80,115). The prediction that proteins involved in initiation should bind to origins has been confirmed in prokaryotes (44,47,81,90,99) and mammalian DNA viruses (24,29,88), and recent data obtained for S. cerevisiae demonstrate that ARSs are footprint...

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“…The P-globin LCR has two important properties associated with it: a very strong erythroid-specific enhancer activity and the ability to confer position-independent, copy number-dependent expression onto globin genes under its control (reviewed in Townes and Behringer, 1990;Epner et al, 1992;Dillon and Grosveld, 1993). Although it is still unclear how this latter property functions, it is sometimes referred to as chromatin opening activity.…”

Section: Introductionmentioning

confidence: 99%

The beta-globin locus control region enhances transcription of but does not confer position-independent expression onto the lacZ gene in transgenic mice.

et al. 1996

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The beta‐globin locus control region (LCR) confers high levels of position‐independent, copy number‐dependent expression onto globin transgenes. Here > 40 independent transgenic mouse lines and founders that carried the LCR in cis with the beta‐globin gene promoter driving a lacZ reporter gene were studied. Expression of the lacZ transgene was assayed by measuring beta‐galactosidase enzyme activity in fetal liver extracts, the levels of which correlated with the quantity of lacZ mRNA determined using RNase protection assays. Unexpectedly, expression of the lacZ transgene was found to show strong position effects, varying as much as 700‐fold per transgene copy. These position effects occurred even if the whole beta‐globin gene was incorporated as part of the lacZ reporter gene. Moreover, DNase I‐hypersensitive sites appeared in the transgene LCR in high expressing but not in low expressing lines, suggesting that the LCR itself was position dependent. In contrast, MEL cell clones, in which transcriptionally active integration sites were selected for, gave < 13‐fold variation in expression per copy of an LCR‐lacZ construct. These results show that the lacZ reporter affects the ability of the LCR to activate chromatin in mice and that culture cells are not an adequate model for position‐independent gene expression studies.

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What does the locus control region control?

Cited by 24 publications

References 15 publications

A cell-specific enhancer far upstream of the mouse tyrosinase gene confers high level and copy number-related expression in transgenic mice.

A cell-specific enhancer far upstream of the mouse tyrosinase gene confers high level and copy number-related expression in transgenic mice.

Identification of an Origin of Bidirectional DNA Replication in the Ubiquitously Expressed Mammalian CAD Gene

The beta-globin locus control region enhances transcription of but does not confer position-independent expression onto the lacZ gene in transgenic mice.

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