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Arnaud P, Feil R. Epigenetic deregulation of genomic imprinting in human disorders and following assisted reproduction. ACTA ACUST UNITED AC 2005; 75:81-97. [PMID: 16035043 DOI: 10.1002/bdrc.20039] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Imprinted genes play important roles in the regulation of growth and development, and several have been shown to influence behavior. Their allele-specific expression depends on inheritance from either the mother or the father, and is regulated by "imprinting control regions" (ICRs). ICRs are controlled by DNA methylation, which is present on one of the two parental alleles only. These allelic methylation marks are established in either the female or the male germline, following the erasure of preexisting DNA methylation in the primordial germ cells. After fertilization, the allelic DNA methylation at ICRs is maintained in all somatic cells of the developing embryo. This epigenetic "life cycle" of imprinting (germline erasure, germline establishment, and somatic maintenance) can be disrupted in several human diseases, including Beckwith-Wiedemann syndrome (BWS), Prader-Willi syndrome (PWS), Angelman syndrome and Hydatidiform mole. In the neurodevelopmental Rett syndrome, the way the ICR mediates imprinted expression is perturbed. Recent studies indicate that assisted reproduction technologies (ART) can sometimes affect the epigenetic cycle of imprinting as well, and that this gives rise to imprinting disease syndromes. This finding warrants careful monitoring of the epigenetic effects, and absolute risks, of currently used and novel reproduction technologies.
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Affiliation(s)
- Philippe Arnaud
- Institute of Molecular Genetics, Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier II, 1919 Route de Mende, 34293 Montpellier Cedex 05, France.
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Abstract
The abnormal pregnancy hydatidiform mole (HM) can be classified as complete (CHM) or partial (PHM) on the basis of both morphology and genetic origin. PHM are diandric triploids while almost all CHM are androgenetic. Thus the characteristic trophoblastic hyperplasia seen in both CHM and PHM is usually associated with the presence of two paternal genomes. Very occasionally CHM may be diploid, but biparental, in origin. These rare BiCHM are found in patients with recurrent HM and appear to be associated with an autosomal recessive condition predisposing to molar pregnancies. Since they are pathologically indistinguishable from androgenetic CHM, BiCHM are also likely to result from defects in genomic imprinting. There is evidence that the gene mutated in this condition, provisionally mapped to 19q13.3-13.4, may be important in setting the maternal imprint in the ovum. Women with BiCHM have a much higher risk of recurrent HM than women with AnCHM and an appreciable risk of persistent trophoblastic disease. Investigation of these unusual BiCHM and isolation of the defective gene will lead to a greater understanding of the function of genomic imprinting in early development.
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Affiliation(s)
- R A Fisher
- Division of Medicine, Imperial College London, Charing Cross Hospital, Fulham Palace Road, UK.
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Chamberlain SJ, Brannan CI. The Prader–Willi Syndrome Imprinting Center Activates the Paternally Expressed Murine Ube3a Antisense Transcript but Represses Paternal Ube3a. Genomics 2001; 73:316-22. [PMID: 11350123 DOI: 10.1006/geno.2001.6543] [Citation(s) in RCA: 156] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The imprinted UBE3A gene exhibits maternal-only expression in specific cell types in the brain, but exhibits biallelic expression in other cell types. UBE3A is located adjacent to a cluster of imprinted, paternally expressed genes that are known to be positively regulated by the Prader-Willi syndrome imprinting center (PWS-IC). Here, we examined the effect of the PWS-IC on the UBE3A locus. Using intersubspecific crosses, we found that deletion of the PWS-IC causes an upregulation of the paternal Ube3a allele. This indicates that unlike its positive effect on all the other paternally expressed transcripts in the region, the PWS-IC negatively regulates the levels of paternal UBE3A. Interestingly, we found that like the human UBE3A locus, the murine Ube3a locus includes an imprinted, paternally expressed antisense transcript. We show that this paternal antisense transcript is positively regulated by the PWS-IC. These results are consistent with a model in which the PWS-IC mediates activation and maintenance of paternal gene expression in the 15q11-q13 region, with repression of the paternal UBE3A gene occurring as an indirect result of expression of the antisense transcript.
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Affiliation(s)
- S J Chamberlain
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, Florida 32610, USA
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Abstract
The Zfp127 gene is located on mouse chromosome 7 in an imprinted region that is homologous to the 2-Mb Prader-Willi and Angelman Syndromes region on human chromosome 15q11-q13. Here, we show that the gene is differentially methylated, the maternal allele being methylated and the paternal allele being unmethylated. This maternal methylation is established promptly after fertilization prior to syngamy. We also provide data that demonstrate the significance of methylation in the paternal expression of the gene. The expression of the Zfp127 gene in methyltransferase-deficient mice is significantly higher, suggesting that the gene is biallelically expressed in these mice. The data presented here will help to understand the mechanism by which the monoallelic expression of the entire 2-Mb Prader-Willi and Angelman Syndrome region is regulated.
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Affiliation(s)
- A Hershko
- Department of Cellular Biochemistry, The Hebrew University Hadassah Medical School, Jerusalem 91120, Israel
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Schweizer J, Zynger D, Francke U. In vivo nuclease hypersensitivity studies reveal multiple sites of parental origin-dependent differential chromatin conformation in the 150 kb SNRPN transcription unit. Hum Mol Genet 1999; 8:555-66. [PMID: 10072422 DOI: 10.1093/hmg/8.4.555] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Human chromosome region 15q11-q13 contains a cluster of oppositely imprinted genes. Loss of the paternal or the maternal alleles by deletion of the region or by uniparental disomy 15 results in Prader-Willi syndrome (PWS) or Angelman syndrome (AS), respectively. Hence, the two phenotypically distinct neurodevelopmental disorders are caused by the lack of products of imprinted genes. Subsets of PWS and AS patients exhibit 'imprinting mutations', such as small microdeletions within the 5' region of the small nuclear ribonucleoprotein polypeptide N ( SNRPN ) transcription unit which affect the transcriptional activity and methylation status of distant imprinted genes throughout 15q11-q13 in cis. To elucidate the mechanism of these long-range effects, we have analyzed the chromatin structure of the 150 kb SNRPN transcription unit for DNase I- and Msp I-hypersensitive sites. By using an in vivo approach on lymphoblastoid cell lines from PWS and AS individuals, we discovered that the SNRPN exon 1 is flanked by prominent hypersensitive sites on the paternal allele, but is completely inaccessible to nucleases on the maternal allele. In contrast, we identified several regions of increased nuclease hypersensitivity on the maternal allele, one of which coincides with the AS minimal microdeletion region and another lies in intron 1 immediately downstream of the paternal-specific hypersensitive sites. At several sites, parental origin-specific nuclease hypersensitivity was found to be correlated with hypermethylation on the allele contributed by the other parent. The differential parental origin-dependent chromatin conformations might govern access of regulatory protein complexes and/or RNAs which could mediate interaction of the region with other genes.
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Affiliation(s)
- J Schweizer
- Howard Hughes Medical Institute and Department of Genetics, Stanford University School of Medicine, Stanford CA 94305-5323, USA
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Gabriel JM, Higgins MJ, Gebuhr TC, Shows TB, Saitoh S, Nicholls RD. A model system to study genomic imprinting of human genes. Proc Natl Acad Sci U S A 1998; 95:14857-62. [PMID: 9843980 PMCID: PMC24540 DOI: 10.1073/pnas.95.25.14857] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Somatic-cell hybrids have been shown to maintain the correct epigenetic chromatin states to study developmental globin gene expression as well as gene expression on the active and inactive X chromosomes. This suggests the potential use of somatic-cell hybrids containing either a maternal or a paternal human chromosome as a model system to study known imprinted genes and to identify as-yet-unknown imprinted genes. Testing gene expression by using reverse transcription followed by PCR, we show that functional imprints are maintained at four previously characterized 15q11-q13 loci in hybrids containing a single human chromosome 15 and at two chromosome 11p15 loci in hybrids containing a single chromosome 11. In contrast, three gamma-aminobutyric acid type A receptor subunit genes in 15q12-q13 are nonimprinted. Furthermore, we have found that differential DNA methylation imprints at the SNRPN promoter and at a CpG island in 11p15 are also maintained in somatic-cell hybrids. Somatic-cell hybrids therefore are a valid and powerful system for studying known imprinted genes as well as for rapidly identifying new imprinted genes.
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Affiliation(s)
- J M Gabriel
- Department of Genetics, Case Western Reserve University School of Medicine, University Hospitals of Cleveland, 10900 Euclid Avenue, Cleveland, OH 44106-4955, USA
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Saitoh S, Buiting K, Cassidy SB, Conroy JM, Driscoll DJ, Gabriel JM, Gillessen-Kaesbach G, Glenn CC, Greenswag LR, Horsthemke B, Kondo I, Kuwajima K, Niikawa N, Rogan PK, Schwartz S, Seip J, Williams CA, Nicholls RD. Clinical spectrum and molecular diagnosis of Angelman and Prader-Willi syndrome patients with an imprinting mutation. ACTA ACUST UNITED AC 1998. [DOI: 10.1002/(sici)1096-8628(19970120)68:2<195::aid-ajmg15>3.0.co;2-p] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are caused by deficiencies of gene expression from paternal or maternal chromosome 15q11-q13, respectively. Many advances have occurred during the past year. The gene for necdin was mapped in the PWS candidate region and found to be paternally expressed in mouse and human. The bisulfite method for analysis of methylation was established for genomic sequencing and diagnostics, and the methylation of Snrpn was studied in detail in the mouse. A region near the Snrpn promoter was shown to function as a silencer in Drosophila. Point mutations were found in the gene for E6-AP ubiquitin-protein ligase (UBE3A) identifying it as the AS gene, and tissue-specific imprinting (maternal expression) was shown in the human brain and in hippocampal neurons and Purkinje cells in the mouse.
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Affiliation(s)
- Y Jiang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
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Lee MJ, Nishio H, Nagai T, Okamoto N, Yuki T, Sumino K. Molecular genetic analysis of the Prader-Willi syndrome by using fluorescent multiplex PCR of the dinucleotide repeats on chromosome 15q11-q13. Clin Chim Acta 1998; 271:89-96. [PMID: 9564560 DOI: 10.1016/s0009-8981(97)00238-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- M J Lee
- Department of Public Health, Kobe University School of Medicine, Japan
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Meguro M, Mitsuya K, Sui H, Shigenami K, Kugoh H, Nakao M, Oshimura M. Evidence for uniparental, paternal expression of the human GABAA receptor subunit genes, using microcell-mediated chromosome transfer. Hum Mol Genet 1997; 6:2127-33. [PMID: 9328477 DOI: 10.1093/hmg/6.12.2127] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We have constructed mouse A9 hybrids containing a single normal human chromosome 15, via microcell-mediated chromosome transfer. Cytogenetic and DNA-polymorphic analyses identified mouse A9 hybrids that contained either a paternal or maternal human chromosome 15. Paternal specific expression of the known imprinted genes SNRPN (small nuclear ribonucleoprotein-associated polypeptide N gene) and IPW (imprinted gene in the Prader-Willi syndrome region) was maintained in the A9 hybrids. Using this system, we first demonstrated that human GABAAreceptor subunit genes, GABRB3 , GABRA5 and GABRG3 , were expressed exclusively from the paternal allele and that E6-AP (E6-associated protein or UBE3A ) was biallelically expressed. Moreover, the 5' portion of the GABRB3 gene was found to be hypermethylated on the paternal allele. Our data imply that GABAAreceptor subunit genes are imprinted and are possible candidates for Prader-Willi syndrome, and that this human monochromosomal hybrid system enables the efficient analysis of imprinted loci.
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Affiliation(s)
- M Meguro
- Department of Molecular and Cell Genetics, School of Life Sciences, Faculty of Medicine, Tottori University, Nishimachi 86, Yonago, Tottori 683, Japan
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Alders M, Hodges M, Hadjantonakis AK, Postmus J, van Wijk I, Bliek J, de Meulemeester M, Westerveld A, Guillemot F, Oudejans C, Little P, Mannens M. The human Achaete-Scute homologue 2 (ASCL2,HASH2) maps to chromosome 11p15.5, close to IGF2 and is expressed in extravillus trophoblasts. Hum Mol Genet 1997; 6:859-67. [PMID: 9175731 DOI: 10.1093/hmg/6.6.859] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Here we describe the cloning of the human Achaete Scute Homologue 2 (HASH2) gene, officially designated ASCL2 (Achaete Scute complex like 2), a homologue of the Drosophila Achaete and Scute genes. In mouse, this gene is imprinted and maps to chromosome 7. We mapped the human homologue close to IGF2 and H19 at 11p15.5, the human region syntenic with mouse chromosome 7, indicating that this imprinted region is highly conserved in mouse and man. HASH2 is expressed in the extravillus trophoblasts of the developing placenta only. The lack of HASH2 expression in non-malignant hydatidiform (androgenetic) moles indicates that HASH2 is also imprinted in man.
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Affiliation(s)
- M Alders
- Institute of Human Genetics, University of Amsterdam, Academisch Medisch Centrum, The Netherlands
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Affiliation(s)
- L H Looijenga
- Dr. Daniel den Hoed Cancer Center, University Hospital Rotterdam, the Netherlands
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