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Cluster specific regulation pattern of upstream regulatory elements in human alpha- and beta-globin gene clusters. Exp Cell Res 2007; 314:115-22. [PMID: 17996867 DOI: 10.1016/j.yexcr.2007.08.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 08/15/2007] [Accepted: 08/18/2007] [Indexed: 11/22/2022]
Abstract
Located in different chromatin contexts and with different developmental switching mode, human alpha- and beta-globin gene clusters are co-regulated temporally and quantitatively to keep balanced expression. Here, by exchanging their key upstream regulatory elements (UREs) in cluster level, and investigating the expression level of exogenous globin genes in the bacterial artificial chromosome (BAC) mediated transgenic mice, we explored the similarities and differences in the regulatory effects between alpha-upstream regulatory element (alpha-URE) and beta-locus control region (beta-LCR). The results showed that, after exchange, the developmental switching modes of human alpha- and beta-like globin genes had changed, with lost expression of epsilon- and alpha1-genes. Their expression levels also decreased. Our study suggests that the regulation of alpha-URE and beta-LCR on the expression level and developmental switching mode of downstream globin genes is cluster specific.
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Tang Y, Wang Z, Huang Y, Liu DP, Liu G, Shen W, Tang X, Feng D, Liang CC. Gene order in human alpha-globin locus is required for their temporal specific expressions. Genes Cells 2007; 11:123-31. [PMID: 16436049 DOI: 10.1111/j.1365-2443.2006.00923.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The human alpha-globin cluster represents a unique model of transcriptional regulation and provides challenges to the current understanding of interactions between distal and proximal regulatory elements. Although the gene proximal regions are believed to possess almost all the necessary elements for temporal and spatial specificity of gene transcription, it is still not clear whether the relative distance of embryonic zeta- and fetal/adult alpha-genes to their distal regulatory element alpha-URE plays any role in transcriptional switching. To investigate the role of gene order in regulating temporal expression, we inverted the entire structure gene region of human alpha-globin locus in a BAC clone bringing alpha-genes closest to alpha-URE and zeta-gene the farthest away. Expression analysis of the reverted locus in transgenic mice showed that alpha-globin genes, now relocated closer to alpha-URE, maintained their expression levels through all developmental stages. However, the zeta-globin gene suffered a total loss at both embryonic and fetal/adult stages. It indicates that proximal location of zeta-globin gene to alpha-URE is necessary for its normal embryonic expression and necessary to prevent embryonic expression of the alpha-globin gene. We proved that, in the human alpha-globin gene cluster, the normal order of structural genes relative to alpha-URE plays a crucial role in the regulation of developmental switching.
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Affiliation(s)
- Yi Tang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Peking Union Medical College & Chinese Academy of Medical Sciences, 5 Dong Dan San Tiao, Beijing, 100005, China
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Abstract
The alpha-globin gene cluster is located at the very tip of the short arm of chromosome 16. It produces the alpha-like globins, which is combined with the beta-like globins to form hemoglobin, and its mutants cause alpha-thalassemia, which is one of the most common genetic diseases. Its expression shows a tissue and developmental stage specificity that is balanced with that of the beta-globin gene cluster. In this article, we summarize the research on the control of expression of the alpha-globin gene cluster, mainly with respect to the alpha-major regulatory element (alpha-MRE): HS-40, the tissue-specific and developmental control of its expression, and its chromosomal environment. In summary, the alpha-globin gene cluster is expressed in an open chromosomal environment; HS-40, the 5'-flanking sequence, the transcribed region, and the 3'-flanking sequence interact to fully regulate its expression.
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Affiliation(s)
- Hua-bing Zhang
- National Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, P. R. China
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Huang BL, Fan-Chiang IR, Wen SC, Koo HC, Kao WY, Gavva NR, Shen CK. Derepression of human embryonic zeta-globin promoter by a locus-control region sequence. Proc Natl Acad Sci U S A 1998; 95:14669-74. [PMID: 9843947 PMCID: PMC24507 DOI: 10.1073/pnas.95.25.14669] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
A multiple protein-DNA complex formed at a human alpha-globin locus-specific regulatory element, HS-40, confers appropriate developmental expression pattern on human embryonic zeta-globin promoter activity in humans and transgenic mice. We show here that introduction of a 1-bp mutation in an NF-E2/AP1 sequence motif converts HS-40 into an erythroid-specific locus-control region. Cis-linkage with this locus-control region, in contrast to the wild-type HS-40, allows erythroid lineage-specific derepression of the silenced human zeta-globin promoter in fetal and adult transgenic mice. Furthermore, zeta-globin promoter activities in adult mice increase in proportion to the number of integrated DNA fragments even at 19 copies/genome. The mutant HS-40 in conjunction with human zeta-globin promoter thus can be used to direct position-independent and copy number-dependent expression of transgenes in adult erythroid cells. The data also supports a model in which competitive DNA binding of different members of the NF-E2/AP1 transcription factor family modulates the developmental stage specificity of an erythroid enhancer. Feasibility to reswitch on embryonic/fetal globin genes through the manipulation of nuclear factor binding at a single regulatory DNA motif is discussed.
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Affiliation(s)
- B L Huang
- Institute of Molecular Biology, Academia Sinica, Nankang, Taipei, Republic of China
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Liebhaber SA, Russell JE. Expression and developmental control of the human alpha-globin gene cluster. Ann N Y Acad Sci 1998; 850:54-63. [PMID: 9668527 DOI: 10.1111/j.1749-6632.1998.tb10462.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The human alpha-globin gene cluster contains three functional genes zeta, alpha 2 and alpha 1. The zeta-globin gene is expressed exclusively in the primitive erythroblasts of the embryonic yolk sac and is selectively silenced during the transition from primitive to definitive erythropoesis. The two alpha-globin genes are expressed through development; they are expressed at equivalent levels in embryonic cells at a 2.6:1 ratio of alpha 2:alpha 1 in fetal and adult cells. The dominant contribution of the alpha 2-globin locus to overall expression of adult alpha-globin is reflected in the more severe phenotype resulting from mutations that affect this locus. Developmental silencing of the zeta-globin gene reflects both transcriptional and posttranscriptional mechanisms. Transcriptional silencing is mediated by an interaction between the zeta-globin gene promoter and a silencer located in the 3' flanking region. This transcriptional silencing is only partial, and residual levels of zeta-globin mRNA are subject to subsequent degredation. This instability of zeta-globin mRNA relative to that of alpha-globin mRNA reflects differences in their respective 3'UTR segments; the zeta-globin mRNA 3'UTR has a lower affinity for a sequence-specific mRNP stability complex which assembles at this site. The alpha-globin mRNA assembles this complex at a higher efficiency and mutations which interfere with 3'UTR function result in corresponding loss of alpha-globin gene expression. These data outline a developmental pathway for the alpha-globin gene cluster which reflects transcriptional and posttranscriptional controls.
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Affiliation(s)
- S A Liebhaber
- Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia 19104-6148, USA.
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Russell JE, Morales J, Liebhaber SA. The role of mRNA stability in the control of globin gene expression. PROGRESS IN NUCLEIC ACID RESEARCH AND MOLECULAR BIOLOGY 1997; 57:249-87. [PMID: 9175436 DOI: 10.1016/s0079-6603(08)60283-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- J E Russell
- Department of Genetics, University of Pennsylvania, Philadelphia 19104, USA
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Pondel MD, Sharpe JA, Clark S, Pearson L, Wood WG, Proudfoot NJ. Proximal promoter elements of the human zeta-globin gene confer embryonic-specific expression on a linked reporter gene in transgenic mice. Nucleic Acids Res 1996; 24:4158-64. [PMID: 8932366 PMCID: PMC146237 DOI: 10.1093/nar/24.21.4158] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We have investigated the transcriptional regulation of the human embryonic zeta-globin gene promoter. First, we examined the effect that deletion of sequences 5' to zeta-globin's CCAAT box have on zeta-promoter activity in erythroid cell lines. Deletions of sequences between -116 and -556 (cap = 0) had little effect while further deletion to -84 reduced zeta-promoter activity by only 2-3-fold in both transiently and stably transfected erythroid cells. Constructs containing 67, 84 and 556 bp of zeta-globin 5' flanking region linked to a beta-galactosidase reporter gene (lacZ) and hypersensitive site -40 (HS-40) of the human alpha-globin gene cluster were then employed for the generation of transgenic mice. LacZ expression from all constructs, including a 67 bp zeta-globin promoter, was erythroid-specific and most active between 8.5 and 10.5 days post-fertilisation. By 16.5 days gestation, lacZ expression dropped 40-100-fold. These results suggest that embryonic-specific activation of the human zeta-globin promoter is conferred by a 67 bp zeta-promoter fragment containing only a CCAAT and TATA box.
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Affiliation(s)
- M D Pondel
- The Sir William Dunn School of Pathology, Chemical Pathology Unit, University of Oxford, UK
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Liebhaber SA, Wang Z, Cash FE, Monks B, Russell JE. Developmental silencing of the embryonic zeta-globin gene: concerted action of the promoter and the 3'-flanking region combined with stage-specific silencing by the transcribed segment. Mol Cell Biol 1996; 16:2637-46. [PMID: 8649371 PMCID: PMC231254 DOI: 10.1128/mcb.16.6.2637] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Globin gene switching is a well-described model of eucaryotic developmental control. In the case of the human alpha-globin gene cluster, migration of erythropoietic activity from the embryonic yolk sac to the fetal liver is parallaled by the zeta-globin gene silencing and enhanced expression of the alpha-globin genes. To map critical cis determinants of this switch, the human zeta-globin gene, the alpha-globin gene, and chimeric recombinants were introduced into the mouse genome. Consistent with previous studies, expression of the individual alpha- and zeta-globin transgenes was found to be developmentally appropriate. Contrary to current models, however, the alpha- and zeta-globin gene promoters were not sufficient to establish this control. Instead, full silencing of the zeta-globin gene required the combined activities of this promoter, transcribed region, and 3'-flanking sequences. Individually, the silencing activities of the zeta-globin gene promoter and 3'-flanking region were minimal but increased markedly when both regions were present. The zeta-globin transcribed region appeared to contribute to gene silencing by a mechanism specifically activated in definitive erythroblasts in the fetal liver. These data demonstrate that a complex set of controls, requiring at least three determinants and involving at least two independent mechanisms, is necessary for full developmental silencing of the human zeta-globin gene.
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Affiliation(s)
- S A Liebhaber
- Howard Hughes Medical Institute, University of Pennsylvania School of Medicine, Philadelphia 19104, USA
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Sharpe JA, Wells DJ, Whitelaw E, Vyas P, Higgs DR, Wood WG. Analysis of the human alpha-globin gene cluster in transgenic mice. Proc Natl Acad Sci U S A 1993; 90:11262-6. [PMID: 8248238 PMCID: PMC47962 DOI: 10.1073/pnas.90.23.11262] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
A 350-bp segment of DNA associated with an erythroid-specific DNase I-hypersensitive site (HS-40), upstream of the alpha-globin gene cluster, has been identified as the major tissue-specific regulator of the alpha-globin genes. However, this element does not direct copy number-dependent or developmentally stable expression of the human genes in transgenic mice. To determine whether additional upstream hypersensitive sites could provide more complete regulation of alpha gene expression we have studied 17 lines of transgenic mice bearing various DNA fragments containing HSs -33, -10, -8, and -4, in addition to HS -40. Position-independent, high-level expression of the human zeta- and alpha-globin genes was consistently observed in embryonic erythroid cells. However, the additional HSs did not confer copy-number dependence, alter the level of expression, or prevent the variable down-regulation of expression in adults. These results suggest that the region upstream of the human alpha-globin genes is not equivalent to that upstream of the beta locus and that although the two clusters are coordinately expressed, there may be differences in their regulation.
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Affiliation(s)
- J A Sharpe
- Medical Research Council Molecular Haematology Unit, University of Oxford, John Radcliffe Hospital
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Grosveld F, Dillon N, Higgs D. The regulation of human globin gene expression. BAILLIERE'S CLINICAL HAEMATOLOGY 1993; 6:31-55. [PMID: 8353317 DOI: 10.1016/s0950-3536(05)80065-4] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The haemopoietic system provides a well-characterized and accessible system for studying the mechanisms of developmental regulation and differentiation in higher eukaryotes. Our current understanding of the steps involved in the early stages of differentiation are poorly understood but a great deal is now known about the mechanisms by which globin expression is regulated in cells committed to the erythroid lineage. Many of the critical cis-acting sequences and some of the important trans-acting factors involved have been identified and current work is focusing on how these interact to produce high levels of tissue-specific and developmentally regulated expression of the human globin genes.
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Affiliation(s)
- F Grosveld
- Laboratory of Gene Structure and Expression, National Institute for Medical Research, London, UK
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Pondel MD, Proudfoot NJ, Whitelaw C, Whitelaw E. The developmental regulation of the human zeta-globin gene in transgenic mice employing beta-galactosidase as a reporter gene. Nucleic Acids Res 1992; 20:5655-60. [PMID: 1454528 PMCID: PMC334399 DOI: 10.1093/nar/20.21.5655] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We have investigated the developmental and tissue specific expression of the human embryonic zeta-globin gene in transgenic mice. A construct containing 550 bp of zeta-globin 5' flanking region, fused to a beta-galactosidase (lacZ) reporter gene and linked to the locus control region (LCR)-like alpha positive regulatory element (alpha PRE) was employed for the production of transgenic mice. Firstly, we compared the number of live born transgenic mice containing this construct to the number of live born transgenic mice containing the entire zeta-globin gene linked to the alpha PRE or the beta LCR. Data showed that 12% of mice generated from eggs injected with zeta-promoter/lacZ/alpha PRE DNA were transgenic compared to only 2% of mice generated from eggs injected with the entire zeta-globin gene linked to the alpha PRE or the beta LCR. The reduced number of live born transgenic mice containing the latter constructs suggests that death of transgenic embryos, possibly due to thalassaemia, may be occurring. X-gal staining of whole embryos containing the lacZ gene revealed that zeta-globin promoter activity was most pronounced at 8.5-9.5 days of development and was restricted to erythroid cells. By 15 days of development, no zeta-globin promoter activity was detected. These results suggest that the alpha PRE can direct high level expression from the zeta-globin promoter and that sequences required for the correct tissue and developmental specific expression of the human zeta-globin gene are present within 550 bp's of 5' flanking region. Sequences within the body of the zeta-globin gene or 3' of the cap site do not appear to be necessary for correct zeta-globin developmental regulation.
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Affiliation(s)
- M D Pondel
- Sir William Dunn School of Pathology, Oxford University, UK
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