scholarly journals NF-E2 disrupts chromatin structure at human beta-globin locus control region hypersensitive site 2 in vitro.

1996 ◽  
Vol 16 (10) ◽  
pp. 5634-5644 ◽  
Author(s):  
J A Armstrong ◽  
B M Emerson
Keyword(s):  
Control Region ◽  
Chromatin Structure ◽  
Locus Control Region ◽  
Dnase I ◽  
Hematopoietic Cell ◽  
Beta Globin ◽  
Hypersensitive Site ◽  
Dnase I Hypersensitive Sites ◽  
Hypersensitive Sites

The human beta-globin locus control region (LCR) is responsible for forming an active chromatin structure extending over the 100-kb locus, allowing expression of the beta-globin gene family. The LCR consists of four erythroid-cell-specific DNase I hypersensitive sites (HS1 to -4). DNase I hypersensitive sites are thought to represent nucleosome-free regions of DNA which are bound by trans-acting factors. Of the four hypersensitive sites only HS2 acts as a transcriptional enhancer. In this study, we examine the binding of an erythroid protein to its site within HS2 in chromatin in vitro. NF-E2 is a transcriptional activator consisting of two subunits, the hematopoietic cell-specific p45 and the ubiquitous DNA-binding subunit, p18. NF-E2 binds two tandem AP1-like sites in HS2 which form the core of its enhancer activity. In this study, we show that when bound to in vitro-reconstituted chromatin, NF-E2 forms a DNase I hypersensitive site at HS2 similar to the site observed in vivo. Moreover, NF-E2 binding in vitro results in a disruption of nucleosome structure which can be detected 200 bp away. Although NF-E2 can disrupt nucleosomes when added to preformed chromatin, the disruption is more pronounced when NF-E2 is added to DNA prior to chromatin assembly. Interestingly, the hematopoietic cell-specific subunit, p45, is necessary for binding to chromatin but not to naked DNA. Interaction of NF-E2 with its site in chromatin-reconstituted HS2 allows a second erythroid factor, GATA-1, to bind its nearby sites. Lastly, nucleosome disruption by NF-E2 is an ATP-dependent process, suggesting the involvement of energy-dependent nucleosome remodeling factors.

scholarly journals Essential role of NF-E2 in remodeling of chromatin structure and transcriptional activation of the epsilon-globin gene in vivo by 5' hypersensitive site 2 of the beta-globin locus control region.

1996 ◽  
Vol 16 (11) ◽  
pp. 6055-6064 ◽  
Author(s):  
Q H Gong ◽  
J C McDowell ◽  
A Dean
Keyword(s):  
Control Region ◽  
Chromatin Structure ◽  
Transcriptional Activation ◽  
Globin Gene ◽  
Locus Control Region ◽  
Dnase I ◽  
Beta Globin ◽  
Hypersensitive Site

Much of our understanding of the process by which enhancers activate transcription has been gained from transient-transfection studies in which the DNA is not assembled with histones and other chromatin proteins as it is in the cell nucleus. To study the activation of a mammalian gene in a natural chromatin context in vivo, we constructed a minichromosome containing the human epsilon-globin gene and portions of the beta-globin locus control region (LCR). The minichromosomes replicate and are maintained at stable copy number in human erythroid cells. Expression of the minichromosomal epsilon-globin gene requires the presence of beta-globin LCR elements in cis, as is the case for the chromosomal gene. We determined the chromatin structure of the epsilon-globin gene in both the active and inactive states. The transcriptionally inactive locus is covered by an array of positioned nucleosomes extending over 1,400 bp. In minichromosomes with a (mu)LCR or DNase I-hypersensitive site 2 (HS2) which actively transcribe the epsilon-globin gene, the nucleosome at the promoter is altered or disrupted while positioning of nucleosomes in the rest of the locus is retained. All or virtually all minichromosomes are simultaneously hypersensitive to DNase I both at the promoter and at HS2. Transcriptional activation and promoter remodeling, as well as formation of the HS2 structure itself, depended on the presence of the NF-E2 binding motif in HS2. The nucleosome at the promoter which is altered upon activation is positioned over the transcriptional elements of the epsilon-globin gene, i.e., the TATA, CCAAT, and CACCC elements, and the GATA-1 site at -165. The simple availability of erythroid transcription factors that recognize these motifs is insufficient to allow expression. As in the chromosomal globin locus, regulation also occurs at the level of chromatin structure. These observations are consistent with the idea that one role of the beta-globin LCR is to maintain promoters free of nucleosomes. The restricted structural change observed upon transcriptional activation may indicate that the LCR need only make a specific contact with the proximal gene promoter to activate transcription.

scholarly journals Synergistic and Additive Properties of the Beta-Globin Locus Control Region (LCR) Revealed by 5′HS3 Deletion Mutations: Implication for LCR Chromatin Architecture

2005 ◽  
Vol 25 (16) ◽  
pp. 7033-7041 ◽  
Author(s):  
Xiangdong Fang ◽  
Jin Sun ◽  
Ping Xiang ◽  
Man Yu ◽  
Patrick A. Navas ◽  
...  
Keyword(s):  
Histone Acetylation ◽  
Control Region ◽  
Chromatin Structure ◽  
Globin Gene ◽  
Dnase I ◽  
Beta Globin ◽  
Pol Ii ◽  
Dnase I Hypersensitive Sites ◽  
Chromatin Architecture ◽  
Hypersensitive Sites

ABSTRACT Deletion of the 234-bp core element of the DNase I hypersensitive site 3 (5′HS3) of the locus control region (LCR) in the context of a human beta-globin locus yeast artificial chromosome (β-YAC) results in profound effects on globin gene expression in transgenic mice. In contrast, deletion of a 2.3-kb 5′HS3 region, which includes the 234-bp core sequence, has a much milder phenotype. Here we report the effects of these deletions on chromatin structure in the beta-globin locus of adult erythroblasts. The 234-bp 5′HS3 deletion abolished histone acetylation throughout the β-globin locus; recruitment of RNA polymerase II (pol II) to the LCR and beta-globin gene promoter was reduced to a basal level; and formation of all the 5′ DNase I hypersensitive sites of the LCR was disrupted. The 2.3-kb 5′HS3 deletion mildly reduced the level of histone acetylation but did not change the profile across the whole locus; the 5′ DNase I hypersensitive sites of the LCR were formed, but to a lesser extent; and recruitment of pol II was reduced, but only marginally. These data support the hypothesis that the LCR forms a specific chromatin structure and acts as a single entity. Based on these results we elaborate on a model of LCR chromatin architecture which accommodates the distinct phenotypes of the 5′HS3 and HS3 core deletions.

scholarly journals Human beta-globin locus control region: analysis of the 5' DNase I hypersensitive site HS 2 in transgenic mice.

1991 ◽  
Vol 88 (5) ◽  
pp. 1626-1630 ◽  
Author(s):  
J. J. Caterina ◽  
T. M. Ryan ◽  
K. M. Pawlik ◽  
R. D. Palmiter ◽  
R. L. Brinster ◽  
...  
Keyword(s):  
Transgenic Mice ◽  
Control Region ◽  
Locus Control Region ◽  
Dnase I ◽  
Beta Globin ◽  
Hypersensitive Site ◽  
Region Analysis ◽  
Dnase I Hypersensitive Site

scholarly journals Hypersensitive site 5 of the human beta locus control region functions as a chromatin insulator

Blood ◽  
1994 ◽  
Vol 84 (5) ◽  
pp. 1399-1401 ◽  
Author(s):  
Q Li ◽  
G Stamatoyannopoulos
Keyword(s):  
Control Region ◽  
Globin Gene ◽  
Locus Control Region ◽  
Beta Globin ◽  
Hypersensitive Site ◽  
Reporter Expression ◽  
Chromatin Insulator ◽  
Hypersensitive Sites ◽  
Globin Gene Expression ◽  
Beta Gene

Abstract The human beta locus control region (LCR) consists of five DNAse I hypersensitive sites (HS), four of which are erythroid specific and one, the further upstream located 5′HS5, is constitutive. To characterize the function of 5′HS5 we analyzed globin gene expression of various constructs containing HS3 as an enhancer, HS5, and the beta gene as a reporter. Expression was analyzed in stably transfected MEL cells. We found that the enhancing effect of hypersensitive site 3 is blocked when the HS5 is interposed between HS3 and the beta globin gene. These data suggest that the human 5′HS5 has the properties of a chromatin insulator.

scholarly journals Hb S/ +-thalassemia due to Hb sickle and a novel deletion of DNase I hypersensitive sites HS3 and HS4 of the   locus control region

Haematologica ◽  
2015 ◽  
Vol 100 (5) ◽  
pp. e166-e168 ◽  
Author(s):  
A. Amid ◽  
M. Cheong ◽  
B. Eng ◽  
M. Hanna ◽  
B.-A. Hohenadel ◽  
...  
Keyword(s):  
Control Region ◽  
Locus Control Region ◽  
Dnase I ◽  
Dnase I Hypersensitive Sites ◽  
Hypersensitive Sites ◽  
Hb S

scholarly journals Hypersensitive site 5 of the human beta locus control region functions as a chromatin insulator

Blood ◽  
1994 ◽  
Vol 84 (5) ◽  
pp. 1399-1401 ◽  
Author(s):  
Q Li ◽  
G Stamatoyannopoulos
Keyword(s):  
Control Region ◽  
Globin Gene ◽  
Locus Control Region ◽  
Beta Globin ◽  
Hypersensitive Site ◽  
Reporter Expression ◽  
Chromatin Insulator ◽  
Hypersensitive Sites ◽  
Globin Gene Expression ◽  
Beta Gene

The human beta locus control region (LCR) consists of five DNAse I hypersensitive sites (HS), four of which are erythroid specific and one, the further upstream located 5′HS5, is constitutive. To characterize the function of 5′HS5 we analyzed globin gene expression of various constructs containing HS3 as an enhancer, HS5, and the beta gene as a reporter. Expression was analyzed in stably transfected MEL cells. We found that the enhancing effect of hypersensitive site 3 is blocked when the HS5 is interposed between HS3 and the beta globin gene. These data suggest that the human 5′HS5 has the properties of a chromatin insulator.

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