β-globin Gene Switching and DNase I Sensitivity of the Endogenous β-globin Locus in Mice Do Not Require the Locus Control Region

Bender, Michael A.; Bulger, Michael; Close, Jennie; Groudine, Mark

doi:10.1016/s1097-2765(00)80433-5

Cited by 223 publications

(203 citation statements)

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“…Given this observation and the presence of DNasehypersensitive sites at both of these regions in erythroid cells, these sequences are candidates for erythroid regulatory elements. The results of the LCR deletions (24)(25)(26) suggest that formation of a generalized nuclease-sensitive chromatin structure in erythroid cells is accomplished by sequences other than the LCR, and one or both of these conserved hypersensitive sites may play a role in this process. We cannot at present eliminate the possibility, however, that either or both of these regions also may be involved in regulation of the proximal ORGs.…”

Section: Discussionmentioning

confidence: 99%

“…The LCR is a major cis-regulatory sequence in erythroid cells, and so we examined the possibility that it also could play a role in regulation of linked genes in olfactory tissue by comparing ORG expression in olfactory epithelium of wildtype mice and mice homozygous for a deletion of the ␤-globin LCR (26). Using the exon assignments derived from the 5Ј RACE products, we designed PCR primers to amplify cDNAs from spliced mRNA in mouse olfactory epithelium.…”

Section: Org Expression Is Unaffected By Deletion Of the ␤-Globin Lcrmentioning

confidence: 99%

“…The major enhancer of the ␤-globin locus, termed the locus control region (LCR), is a 20-kb segment of DNA containing several DNase-hypersensitive sites, located to the 5Ј side of the genes (20)(21)(22). In contrast to the view that the LCR controls chromatin ''opening'' of the globin locus (23), deletion of the LCR from the endogenous Hbb locus leaves the globin genes in a DNasesensitive domain in erythroid cells, albeit with much lower levels of expression (24)(25)(26). These results suggest that other DNA sequences may be involved in opening a chromatin domain and that these sequences might be found within the adjacent ORG clusters.…”

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confidence: 99%

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Comparative structural and functional analysis of the olfactory receptor genes flanking the human and mouse β-globin gene clusters

Bulger

Bender

Doorninck

et al. 2000

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

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By sequencing regions flanking the ␤-globin gene complex in mouse (Hbbc) and human (HBBC), we have shown that the ␤-globin gene cluster is surrounded by a larger cluster of olfactory receptor genes (ORGs). To facilitate sequence comparisons and to investigate the regulation of ORG expression, we have mapped 5 sequences of mRNA from olfactory epithelium encoding ␤-globinproximal ORGs. We have found that several of these genes contain multiple noncoding exons that can be alternatively spliced. Surprisingly, the only common motifs found in the promoters of these genes are a ''TATA'' box and a purine-rich motif. Sequence comparisons between human and mouse reveal that most of the conserved regions are confined to the coding regions and transcription units of the genes themselves, but a few blocks of conserved sequence also are found outside of ORG transcription units. The possible influence of ␤-globin regulatory sequences on ORG expression in olfactory epithelium was tested in mice containing a deletion of the endogenous ␤-globin locus control region, but no change in expression of the neighboring ORGs was detected. We evaluate the implications of these results for possible mechanisms of regulation of ORG transcription.O lfactory receptors are a family of seven-transmembrane G protein-coupled receptors expressed in sensory neurons of nasal epithelium, where they bind to odorant epitopes and transduce this primary signal into membrane potential (1-3). These molecules are encoded by a family of up to 1,000 genes in mouse and human, which are grouped into discrete clusters at different chromosomal locations (4-7). Production of a given olfactory receptor is restricted to one of four spatially defined domains within the olfactory epithelium (8,9). Despite the large size of this gene family, each olfactory neuron appears to express only a single olfactory receptor gene (ORG) (10, 11) in an allele-specific manner (12). The mechanisms that underlie any of these regulatory decisions-expression in olfactory neurons, zonal specificity, one receptor per neuron, or allelic exclusionare undefined. In addition, expression of some ORGs has been documented in nonolfactory tissues (13-17), but the significance of such expression is also unknown.The characterization of DNA sequences required for proper gene expression, such as promoters and enhancers, represents a basic approach to such questions. Functional studies of putative ORG regulatory elements, however, are hindered by the lack of a viable cell culture model for olfactory neurons. Although analysis of transgenes in mice provides a suitable model system, the production of mouse lines is time-consuming and expensive. Thus, genomic approaches are particularly relevant to the identification of ORG regulatory sequences, in part to guide the selection of regions to be examined by functional studies in transgenic mice. Candidates for such regions can be recognized as noncoding sequences that are conserved between species (18).Previously, we reported that ORGs surround the complex o...

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Section: Discussionmentioning

confidence: 99%

Section: Org Expression Is Unaffected By Deletion Of the ␤-Globin Lcrmentioning

confidence: 99%

mentioning

confidence: 99%

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Comparative structural and functional analysis of the olfactory receptor genes flanking the human and mouse β-globin gene clusters

Bulger

Bender

Doorninck

et al. 2000

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

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“…Analysis of targeted deletions of the endogenous ␤-globin LCR in mice and in cultured cells have revealed that the LCR is not required for initiation or maintenance of general DNase I sensitivity of the locus, hyperacetylation of histones, or low-level transcription, but it is essential for achieving high levels of transcription (Epner et al 1998;Bender et al 2000;Schübeler et al 2001). Given the similar chromatin structure and expression of the ␤-globin loci in uninduced MEL cells and the ⌬LCR cells, we wished to determine if the differentiation-dependent events such as NF-E2 binding, PIC assembly, and elongation were LCR-dependent steps.…”

Section: Allele-specific Chip Analysis For ⌬Lcr/wt Heterozygous Micementioning

confidence: 99%

“…Surprisingly, studies of the targeted deletion of the LCR from the endogenous ␤-globin gene locus (⌬LCR) have revealed that the LCR is not required for the generalized DNaseI sensitive conformation of the locus or chromatin remodeling and histone hyperacetylation of the ␤-globin promoter (Epner et al 1998;Bender et al 2000;Schübeler et al 2001); however, transcription from the ⌬LCR allele is decreased to 1%-4% of wild-type (WT) levels (Bender et al 2000;Schübeler et al 2001). These results suggest that the LCR stimulates transcription at an event downstream of promoter remodeling, although the molecular mechanism of LCR function has not been determined.…”

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confidence: 99%

The β-globinlocus control region (LCR) functions primarily by enhancing the transition from transcription initiation to elongation

Sawado¹,

Halow²,

Bender³

et al. 2003

Genes Dev.

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166

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To investigate the molecular basis of ␤-globin gene activation, we analyzed factor recruitment and histone modification at the adult ␤-globin gene in wild-type (WT)/locus control region knockout (⌬LCR) heterozygous mice and in murine erythroleukemia (MEL) cells. Although histone acetylation and methylation (Lys 4) are high before and after MEL differentiation, recruitment of the erythroid-specific activator NF-E2 to the promoter and preinitiation complex (PIC) assembly occur only after differentiation. We reported previously that targeted deletion of the LCR reduces ␤-globin gene expression to 1%-4% of WT without affecting promoter histone acetylation. Here, we report that NF-E2 is recruited equally efficiently to the adult ␤-globin promoters of the ⌬LCR and WT alleles. Moreover, the LCR deletion reduces PIC assembly only twofold, but has a dramatic effect on Ser 5 phosphorylation of RNA polymerase II and transcriptional elongation. Our results suggest at least three distinct stages in ␤-globin gene activation: (1) [Keywords: Allele-specific chromatin immunoprecipitation analysis; locus control region; ␤-globin locus; transcription elongation; NF-E2; CTD-phosphorylation] Supplemental material is available at http://www.genesdev.org. Received January 6, 2003; revised version accepted February 19, 2003. In higher eukaryotes, gene activation involves several events including chromatin opening, activator binding to regulatory regions, recruitment of basal transcription factors (TFIIA to TFIIJ) and RNA polymerase II (pol II) to the promoter [preinitiation complex (PIC) assembly], and transcription elongation. A general model has emerged in which activators function to stabilize or modulate transcription through interactions with histone acetyltransferases, as well as components of the basal transcription machinery, such as TATA binding protein (TBP), TBP-associated factors (TAFs), and TFIIB (for review, see Lemon and Tjian 2000). PIC assembly is followed by initiation and elongation, during which the Cterminal domain (CTD) of the RPB1 subunit of pol II is phosphorylated (for review, see Dahmus 1996). These steps in gene activation are often regulated by distal elements called enhancers (for review, see Blackwood and Kadonaga 1998;Martin 2001). Enhancers increase either the rate of transcription, the number of the templates engaged in transcription, or both. Studies using transgenes or in vitro templates have linked enhancer activities to various events such as PIC assembly (Kim et al. 1998;Yie et al. 1999), histone acetylation at the promoter (Madisen et al. 1998), and nuclear localization (Francastel et al. 1999). However, it is poorly understood which events in transactivation are the actual targets of long-range enhancer function at native gene loci.The murine ␤-globin gene locus is a model system for studying the molecular mechanisms of enhancer-dependent gene activation at a native locus. The locus contains embryonic and adult ␤-like globin genes that are ordered as they are expressed during development. Hig...

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Globin Gene Clusters

Hardison

2002

Wiley Encyclopedia of Molecular Medicine

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β-globin Gene Switching and DNase I Sensitivity of the Endogenous β-globin Locus in Mice Do Not Require the Locus Control Region

Cited by 223 publications

References 40 publications

Comparative structural and functional analysis of the olfactory receptor genes flanking the human and mouse β-globin gene clusters

Comparative structural and functional analysis of the olfactory receptor genes flanking the human and mouse β-globin gene clusters

The β-globinlocus control region (LCR) functions primarily by enhancing the transition from transcription initiation to elongation

Globin Gene Clusters

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