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Samra N, Toubiana S, Yttervik H, Tzur-Gilat A, Morani I, Itzkovich C, Giladi L, Abu Jabal K, Cao JZ, Godley LA, Mory A, Baris Feldman H, Tveten K, Selig S, Weiss K. RBL2 bi-allelic truncating variants cause severe motor and cognitive impairment without evidence for abnormalities in DNA methylation or telomeric function. J Hum Genet 2021; 66:1101-1112. [PMID: 33980986 DOI: 10.1038/s10038-021-00931-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 04/14/2021] [Accepted: 04/14/2021] [Indexed: 02/01/2023]
Abstract
RBL2/p130, a member of the retinoblastoma family of proteins, is a key regulator of cell division and propagates irreversible senescence. RBL2/p130 is also involved in neuronal differentiation and survival, and eliminating Rbl2 in certain mouse strains leads to embryonic lethality accompanied by an abnormal central nervous system (CNS) phenotype. Conflicting reports exist regarding a role of RBL2/p130 in transcriptional regulation of DNA methyltransferases (DNMTs), as well as the control of telomere length. Here we describe the phenotype of three patients carrying bi-allelic RBL2-truncating variants. All presented with infantile hypotonia, severe developmental delay and microcephaly. Malignancies were not reported in carriers or patients. Previous studies carried out on mice and human cultured cells, associated RBL2 loss to DNA methylation and telomere length dysregulation. Here, we investigated whether patient cells lacking RBL2 display related abnormalities. The study of primary patient fibroblasts did not detect abnormalities in expression of DNMTs. Furthermore, methylation levels of whole genome DNA, and specifically of pericentromeric repeats and subtelomeric regions, were unperturbed. RBL2-null fibroblasts show no evidence for abnormal elongation by telomeric recombination. Finally, gradual telomere shortening, and normal onset of senescence were observed following continuous culturing of RBL2-mutated fibroblasts. Thus, this study resolves uncertainties regarding a potential non-redundant role for RBL2 in DNA methylation and telomere length regulation, and indicates that loss of function variants in RBL2 cause a severe autosomal recessive neurodevelopmental disorder in humans.
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Affiliation(s)
- Nadra Samra
- Genetic Unit, Ziv Medical Center, Tzfat, Israel.,Faculty of Medicine, Bar Ilan University, Tzfat, Israel
| | - Shir Toubiana
- Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | - Hilde Yttervik
- Department of Medical Genetics, University Hospital of North Norway, Tromsø, Norway
| | - Aya Tzur-Gilat
- Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - Chen Itzkovich
- The Clinical Research Institute at Rambam Health Care Campus, Haifa, Israel
| | - Liran Giladi
- Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
| | | | - John Z Cao
- Section of Hematology Oncology, Departments of Medicine and Human Genetics, The University of Chicago, Chicago, IL, USA
| | - Lucy A Godley
- Section of Hematology Oncology, Departments of Medicine and Human Genetics, The University of Chicago, Chicago, IL, USA
| | - Adi Mory
- The Genetics Institute, Rambam Health Care Campus, Haifa, Israel.,The Genetics Institute, Tel Aviv Sourasky Medical Center and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Hagit Baris Feldman
- The Genetics Institute, Rambam Health Care Campus, Haifa, Israel.,The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.,The Genetics Institute, Tel Aviv Sourasky Medical Center and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Kristian Tveten
- Department of Medical Genetics, Telemark Hospital Trust, Skien, Norway
| | - Sara Selig
- Department of Genetics and Developmental Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel. .,Laboratory of Molecular Medicine, Rambam Health Care Campus, Haifa, Israel.
| | - Karin Weiss
- The Genetics Institute, Rambam Health Care Campus, Haifa, Israel.,The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel
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2
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Toubiana S, Gagliardi M, Papa M, Manco R, Tzukerman M, Matarazzo MR, Selig S. Persistent epigenetic memory impedes rescue of the telomeric phenotype in human ICF iPSCs following DNMT3B correction. eLife 2019; 8:e47859. [PMID: 31738163 PMCID: PMC6897513 DOI: 10.7554/elife.47859] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Accepted: 11/17/2019] [Indexed: 12/15/2022] Open
Abstract
DNA methyltransferase 3B (DNMT3B) is the major DNMT that methylates mammalian genomes during early development. Mutations in human DNMT3B disrupt genome-wide DNA methylation patterns and result in ICF syndrome type 1 (ICF1). To study whether normal DNA methylation patterns may be restored in ICF1 cells, we corrected DNMT3B mutations in induced pluripotent stem cells from ICF1 patients. Focusing on repetitive regions, we show that in contrast to pericentromeric repeats, which reacquire normal methylation, the majority of subtelomeres acquire only partial DNA methylation and, accordingly, the ICF1 telomeric phenotype persists. Subtelomeres resistant to de novo methylation were characterized by abnormally high H3K4 trimethylation (H3K4me3), and short-term reduction of H3K4me3 by pharmacological intervention partially restored subtelomeric DNA methylation. These findings demonstrate that the abnormal epigenetic landscape established in ICF1 cells restricts the recruitment of DNMT3B, and suggest that rescue of epigenetic diseases with genome-wide disruptions will demand further manipulation beyond mutation correction.
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Affiliation(s)
- Shir Toubiana
- Molecular Medicine LaboratoryRappaport Faculty of Medicine, TechnionHaifaIsrael
- Rambam Health Care CampusHaifaIsrael
| | | | | | - Roberta Manco
- Institute of Genetics and Biophysics, ABT CNRNaplesItaly
| | - Maty Tzukerman
- Molecular Medicine LaboratoryRappaport Faculty of Medicine, TechnionHaifaIsrael
- Rambam Health Care CampusHaifaIsrael
| | | | - Sara Selig
- Molecular Medicine LaboratoryRappaport Faculty of Medicine, TechnionHaifaIsrael
- Rambam Health Care CampusHaifaIsrael
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3
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Toubiana S, Velasco G, Chityat A, Kaindl AM, Hershtig N, Tzur-Gilat A, Francastel C, Selig S. Subtelomeric methylation distinguishes between subtypes of Immunodeficiency, Centromeric instability and Facial anomalies syndrome. Hum Mol Genet 2018; 27:3568-3581. [PMID: 30010917 DOI: 10.1093/hmg/ddy265] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2018] [Accepted: 07/11/2018] [Indexed: 12/16/2022] Open
Abstract
Human telomeres and adjacent subtelomeres are packaged as heterochromatin. Subtelomeric DNA undergoes methylation during development by DNA methyltransferase 3B (DNMT3B), including the CpG-rich promoters of the long non-coding RNA (TERRA) embedded in these regions. The factors that direct DNMT3B methylation to human subtelomeres and maintain this methylation throughout lifetime are yet unknown. The importance of subtelomeric methylation is manifested through the abnormal telomeric phenotype in Immunodeficiency, Centromeric instability and Facial anomalies (ICF) syndrome type 1 patients carrying mutations in DNMT3B. Patient cells demonstrate subtelomeric hypomethylation, accompanied by elevated TERRA transcription, accelerated telomere shortening and premature senescence of fibroblasts. ICF syndrome can arise due to mutations in at least three additional genes, ZBTB24 (ICF2), CDCA7 (ICF3) and HELLS (ICF4). While pericentromeric repeat hypomethylation is evident in all ICF syndrome subtypes, the status of subtelomeric DNA methylation had not been described for patients of subtypes 2-4. Here we explored the telomeric phenotype in cells derived from ICF2-4 patients with the aim to determine whether ZBTB24, CDCA7 and HELLS also play a role in establishing and/or maintaining human subtelomeric methylation. We found normal subtelomeric methylation in ICF2-4 and accordingly low TERRA levels and unperturbed telomere length. Moreover, depleting the ICF2-4-related proteins in normal fibroblasts did not influence subtelomeric methylation. Thus, these gene products are not involved in establishing or maintaining subtelomeric methylation. Our findings indicate that human subtelomeric heterochromatin has specialized methylation regulation and highlight the telomeric phenotype as a characteristic that distinguishes ICF1 from ICF2-4.
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Affiliation(s)
- Shir Toubiana
- Molecular Medicine Laboratory, Rambam Health Care Campus and Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Guillaume Velasco
- Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate, CNRS, Paris Cedex, France
| | - Adi Chityat
- Molecular Medicine Laboratory, Rambam Health Care Campus and Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Angela M Kaindl
- Charité - Universitätsmedizin Berlin, Department of Pediatric Neurology, Center for Chronically Sick Children, Institute of Cell Biology and Neurobiology, Augustenburger Platz 1, Berlin, Germany
| | | | - Aya Tzur-Gilat
- Molecular Medicine Laboratory, Rambam Health Care Campus and Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Claire Francastel
- Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate, CNRS, Paris Cedex, France
| | - Sara Selig
- Molecular Medicine Laboratory, Rambam Health Care Campus and Rappaport Faculty of Medicine, Technion, Haifa, Israel
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4
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Asakawa JI, Kodaira M, Cullings HM, Katayama H, Nakamura N. The genetic risk in mice from radiation: an estimate of the mutation induction rate per genome. Radiat Res 2013; 179:293-303. [PMID: 23368417 DOI: 10.1667/rr3095.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Restriction Landmark Genome Scanning (RLGS) is a method that uses end-labeled (32)P NotI sites that are mostly associated with coding genes to visualizes thousands of DNA fragments as spots in two-dimensional autoradiograms. This approach allows direct detection of autosomal deletions as spots with half normal intensity. The method was applied to mouse offspring derived from spermatogonia exposed to 4 Gy of X rays. A genome-wide assessment of the mutation induction rate was estimated from the detected deletions. Examinations were made of 1,007 progeny (502 derived from control males and 505 from irradiated males) and 1,190 paternal and 1,240 maternal spots for each mouse. The results showed one deletion mutation in the unirradiated paternal genomes of 502 offspring (0.2%) and 5 deletions in the irradiated paternal genomes of 505 offspring (1%). The difference was marginally significant, with the deletion sizes ranged from 2-13 Mb. If the frequencies are taken at face value, the net increase was 0.8% after an exposure of 4 Gy, or 0.2% per Gy per individual if a linear dose response is assumed. Since the present RLGS analysis examined 1,190 NotI sites, while the mouse genome contains ∼25,000 genes, the genomic probability of any gene undergoing a deletion mutation would be 25× 0.2%, or 5% per Gy. Furthermore, since the present RLGS screened about 0.2% of the total genome, the probability of detecting a deletion anywhere in the total genome would be estimated to be 500 times 0.2% or 100% (i.e., 1 deletion per Gy). These results are discussed with reference to copy number variation in the human genome.
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Affiliation(s)
- Jun-ichi Asakawa
- Departments of Genetics, Radiation Effects Research Foundation, 5-2 Hijiyama Park, Minami-ku, Hiroshima 732-0815, Japan.
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5
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Abstract
Advocates of chimpanzee research claim the genetic similarity of humans and chimpanzees make them an indispensable research tool to combat human diseases. Given that cancer is a leading cause of human death worldwide, one might expect that if chimpanzees were needed for, or were productive in, cancer research, then they would have been widely used. This comprehensive literature analysis reveals that chimpanzees have scarcely been used in any form of cancer research, and that chimpanzee tumours are extremely rare and biologically different from human cancers. Often, chimpanzee citations described peripheral use of chimpanzee cells and genetic material in predominantly human genomic studies. Papers describing potential new cancer therapies noted significant concerns regarding the chimpanzee model. Other studies described interventions that have not been pursued clinically. Finally, available evidence indicates that chimpanzees are not essential in the development of therapeutic monoclonal antibodies. It would therefore be unscientific to claim that chimpanzees are vital to cancer research. On the contrary, it is reasonable to conclude that cancer research would not suffer, if the use of chimpanzees for this purpose were prohibited in the US. Genetic differences between humans and chimpanzees, make them an unsuitable model for cancer, as well as other human diseases.
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Affiliation(s)
- Jarrod Bailey
- New England Anti-Vivisection Society, Boston, MA 02108-5100, USA.
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6
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Yehezkel S, Segev Y, Viegas-Péquignot E, Skorecki K, Selig S. Hypomethylation of subtelomeric regions in ICF syndrome is associated with abnormally short telomeres and enhanced transcription from telomeric regions. Hum Mol Genet 2008; 17:2776-89. [PMID: 18558631 DOI: 10.1093/hmg/ddn177] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Telomeres and adjacent subtelomeric regions are packaged as heterochromatin in many organisms. The heterochromatic features include DNA methylation, histones H3-Lys9 (Lysine 9) and H4-Lys20 (Lysine 20) methylation and heterochromatin protein1 alpha binding. Subtelomeric DNA is hypomethylated in human sperm and ova, and these regions are subjected to de novo methylation during development. In mice this activity is carried out by DNA methyltransferase 3b (Dnmt3b). Mutations in DNMT3B in humans lead to the autosomal-recessive ICF (immunodeficiency, centromeric region instability, facial anomalies) syndrome. Here we show that, in addition to several satellite and non-satellite repeats, the subtelomeric regions in lymphoblastoid and fibroblast cells of ICF patients are also hypomethylated to similar levels as in sperm. Furthermore, the telomeres are abnormally short in both the telomerase-positive and -negative cells, and many chromosome ends lack detectable telomere fluorescence in situ hybridization signals from either one or both sister-chromatids. In contrast to Dnmt3a/b(-/-) mouse embryonic stem cells, increased telomere sister-chromatid exchange was not observed in ICF cells. Hypomethylation of subtelomeric regions was associated in the ICF cells with advanced telomere replication timing and elevated levels of transcripts emanating from telomeric regions, known as TERRA (telomeric-repeat-containing RNA) or TelRNA. The current findings provide a mechanistic explanation for the abnormal telomeric phenotype observed in ICF syndrome and highlights the link between TERRA/TelRNA and structural telomeric integrity.
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Affiliation(s)
- Shiran Yehezkel
- Department of Nephrology and Laboratory of Molecular Medicine, Rambam Medical Center and Rappaport Faculty of Medicine and Research Institute, Technion, Haifa 31096, Israel
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7
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Abstract
There is a continuing need for more efficient methods to examine mutations in humans and other species resulting from exposures to environmental toxins and radiation. Environmental genomic studies, which often utilize nonmodel system species and as a result, there is a particular need for a method that does not rely on the availability of genome sequence information. Restriction landmark genome scanning (RLGS) is a two-dimensional electrophoresis (2-DE) of end-labeled DNA fragments. A vertical giant gel 2-DE system has been developed and applied to the RLGS. On a single RLGS pattern of mouse or human DNA, approx 2000 DNA fragments (spots) varying in size from 1.0 to 5.0 kb in the first dimension and 0.2 to 3.0 kb in the second dimension are visualized. In principle, this system will detect genomic alterations of two types: (1) that due to gain or loss of a cut site for the three restriction fragment enzymes employed in the study and (2) that due to insertion/deletion/rearrangement (I/D/R) events. After optimization of the sample preparation and electrophoresis conditions, the gel quality reached a level such that the electrophoresis patterns derived from a single DNA sample gave distribution patterns of spots able to be superimposed. This technology can visualize up to 3000 DNA fragments per gel without using any probes, and thus should be highly efficient in monitoring for mutations resulting in I/D/R events in DNA fragments distributed throughout the genome. This method relies on direct labeling of DNA fragments rather than hybridization and therefore precise information on genome sequences is not required. As a result this method is applicable to any species.
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Affiliation(s)
- Jun-ichi Asakawa
- Department of Genetics, Radiation Effects Research Foundation, Hiroshima, Japan
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8
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DNA methylation and cancer-associated genetic instability. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2006; 570:363-92. [PMID: 18727508 DOI: 10.1007/1-4020-3764-3_13] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
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9
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Asakawa JI, Kuick R, Kodaira M, Nakamura N, Katayama H, Pierce D, Funamoto S, Preston D, Satoh C, Neel JV, Hanash S. A Genome Scanning Approach to Assess the Genetic Effects of Radiation in Mice and Humans. Radiat Res 2004; 161:380-90. [PMID: 15038760 DOI: 10.1667/rr3146] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We used Restriction Landmark Genome Scanning (RLGS) to assess, on a genome-wide basis, the mutation induction rate in mouse germ cells after radiation exposure. Analyses of 1,115 autosomal NotI DNA fragments per mouse for reduced spot intensity, indicative of loss of one copy, in 506 progeny derived from X-irradiated spermatogonia (190, 237 and 79 mice in 0-, 3-, and 5-Gy groups, respectively), permitted us to identify 16 mutations affecting 23 fragments in 20 mice. The 16 mutations were composed of eight small changes (1-9 bp) at microsatellite sequences, five large deletions (more than 25 kb), and three insertions of SINE B2 or LINE1 transposable elements. The maximum induction rate of deletion mutations was estimated as (0.17 +/- 0.09) x 10(-5)/locus Gy(-1). The estimate is considerably lower than 1 x 10(-5)/locus Gy(-1), the mean induction rate of deletion mutations at Russell's 7 loci, which assumed that deletion mutations comprise 50% of all mutations. We interpret the results as indicating that the mean induction rate of mutations in the whole genome may be substantially lower than that at the 7 loci. We also demonstrate the applicability of RLGS for detection of human mutations, which allows direct comparisons between the two species.
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Affiliation(s)
- Jun-ichi Asakawa
- Department of Genetics, Radiation Effects Research Foundation, 5-2 Hijiyama-Park, Minami-ku, Hiroshima 732-0815, Japan.
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10
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Keith JM, Cochran DAE, Lala GH, Adams P, Bryant D, Mitchelson KR. Unlocking hidden genomic sequence. Nucleic Acids Res 2004; 32:e35. [PMID: 14973330 PMCID: PMC373418 DOI: 10.1093/nar/gnh022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Despite the success of conventional Sanger sequencing, significant regions of many genomes still present major obstacles to sequencing. Here we propose a novel approach with the potential to alleviate a wide range of sequencing difficulties. The technique involves extracting target DNA sequence from variants generated by introduction of random mutations. The introduction of mutations does not destroy original sequence information, but distributes it amongst multiple variants. Some of these variants lack problematic features of the target and are more amenable to conventional sequencing. The technique has been successfully demonstrated with mutation levels up to an average 18% base substitution and has been used to read previously intractable poly(A), AT-rich and GC-rich motifs.
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Affiliation(s)
- Jonathan M Keith
- Department of Mathematics, University of Queensland, St Lucia, Queensland 4072, Australia.
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11
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Zhu X, Wimmer K, Kuick R, Lamb BJ, Motyka S, Jasty R, Castle VP, Hanash SM. N-myc modulates expression of p73 in neuroblastoma. Neoplasia 2002; 4:432-9. [PMID: 12192602 PMCID: PMC1564122 DOI: 10.1038/sj.neo.7900255] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2001] [Accepted: 06/11/2001] [Indexed: 12/22/2022]
Abstract
The human p73 gene is a homolog of p53, which has been localized to chromosome 1p36 in a region that is frequently deleted in neuroblastoma. Transfection of the p73 gene into neuroblastoma cells that lack detectable p73 protein has been shown to result in growth suppression and to induce neuronal differentiation. In this study, we have identified by means of restriction landmark genome scanning (RLGS) a genomic fragment that was frequently reduced in intensity in neuroblastomas. The cloned fragment contained exon 1 of p73 as well as intronic and promoter sequences. We investigated the genomic and expression status of p73 and N-myc in 34 neuroblastoma tumors and 12 neuroblastoma cell lines. Approximately a third of neuroblastomas in our series exhibited deletion of p73. Most tumors analyzed exhibited reduced expression of p73, as determined by quantitative RT-PCR, in the absence of detectable p73 gene deletion. The reduced expression of p73 correlated with overexpression of N-myc in a statistically significant manner. The N-myc gene was transfected into two neuroblastoma cell lines that lacked N-myc amplification to determine its effect on p73 RNA levels. p73 was detectable at low level by RT-PCR in untransfected SK-N-AS cells and became undetectable following N-myc transfection, whereas in SH-EP1 cells, p73 levels were substantially reduced following transfection but remained detectable. Our data suggest that the N-myc gene modulates expression of p73, allowing neuroblastoma cells to escape the growth suppressing properties of p73.
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Affiliation(s)
- Xiaoxiang Zhu
- Department of Pediatrics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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12
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Misek DE, Chang CL, Kuick R, Hinderer R, Giordano TJ, Beer DG, Hanash SM. Transforming properties of a Q18-->E mutation of the microtubule regulator Op18. Cancer Cell 2002; 2:217-28. [PMID: 12242154 DOI: 10.1016/s1535-6108(02)00124-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
We have identified a somatic mutation in Op18 in a human esophageal adenocarcinoma. The mutant form of Op18 (M-Op18) was cloned and sequenced, revealing a substitution of a G for C at nucleotide 155, which results in a Q18-->E substitution in the protein. M-Op18 cDNA was expressed in NIH/3T3 cells, which resulted in foci formation and tumor growth in immunodeficient mice. Cell cycle analysis of M-Op18-expressing cells revealed a doubling in the percentage of cells in G2/M relative to cells overexpressing wild-type Op18, a decrease in M-Op18-specific phosphorylation, and alterations in tubulin ultrastructure in M-Op18-expressing cells. These results suggest that the somatic mutation identified in Op18 has profound effects on cell homeostasis that may lead to tumorigenicity.
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Affiliation(s)
- David E Misek
- Department of Pediatrics, University of Michigan, Ann Arbor, MI 48109, USA.
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13
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Tra J, Kondo T, Lu Q, Kuick R, Hanash S, Richardson B. Infrequent occurrence of age-dependent changes in CpG island methylation as detected by restriction landmark genome scanning. Mech Ageing Dev 2002; 123:1487-503. [PMID: 12425956 DOI: 10.1016/s0047-6374(02)00080-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Hypermethylation of CpG islands, resulting in the inactivation of tumor suppressor genes, is an early event in the development of some malignancies. Recent studies suggest that this abnormal methylation may be a function of aging. The number of CpG islands that methylate with age is unknown. We used restriction landmark genome scanning (RLGS) to approximate the extent to which CpG islands change methylation status during aging. Comparison of more than 2000 loci in T lymphocytes isolated from newborn, middle age, and elderly people revealed that 29 loci ( approximately 1%) changed methylation status during aging, with 23 increasing methylation, and six decreasing. The same subset also changed methylation status with age in the esophagus, lung, and pancreas, but in variable directions. Virtual genome scanning identified one of these loci as a member of the forkhead family, recently implicated in aging, and another as an EST fragment. The methylation status of both correlated with level of expression. Confirming studies in multiple tissues from normal and DNMT1(+/-) mice demonstrated only one age dependent change in the methylation of more than 2000 loci, occurring in liver and kidney. These results indicate that the methylation status of the majority of CpG islands in both mice and humans is tightly controlled during aging, and that changes are infrequent and in humans confined to a specific subset of genes.
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Affiliation(s)
- John Tra
- Department of Pediatrics and Infectious Diseases, University of Michigan, Ann Arbor, MI 48109, USA
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14
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Rush LJ, Plass C. Restriction landmark genomic scanning for DNA methylation in cancer: past, present, and future applications. Anal Biochem 2002; 307:191-201. [PMID: 12202234 DOI: 10.1016/s0003-2697(02)00033-7] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The field of molecular biology was revolutionized by the advent of gel electrophoresis. Restriction landmark genomic scanning (RLGS) is a type of two-dimensional electrophoresis employed in the genome-wide assessment of genomic alterations. RLGS has been used to study genetic and epigenetic changes in normal tissues, primary tumors, cancer cell lines, and various organisms such as mice, rats, hamsters, bacteria, and plants. An RLGS profile displays over 2000 radiolabeled restriction landmark sites in a single assay. When conducted with methylation-sensitive restriction enzymes whose sites are preferentially located in CpG island regulatory regions, RLGS becomes a very versatile tool for the investigation of both normal and aberrant methylation patterns. Early studies performed on tumor DNA were mainly descriptive in nature, essentially a catalogue of loci that were changed to varying degrees in different tumor types. Over time, as investigators have become more proficient with RLGS and have undertaken high-throughput studies, the need for efficient cloning, imaging, and analysis systems has become paramount. Current studies focus on identifying specific genes and pathways involved in deregulated methylation in cancer. As such, RLGS analysis of tumor samples has made tremendous contributions to our understanding of the role of DNA methylation in cancer. Future directions will take advantage of the abundant genomic sequence data available to link all of the RLGS loci to genes and create biologically relevant methylation profiles of cancer. This review discusses practical considerations of using RLGS as a genome scanning tool and the past, present, and future applications in cancer biology.
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Affiliation(s)
- Laura J Rush
- Department of Veterinary Biosciences, Division of Human Cancer Genetics, The Ohio State University, Columbus, OH 43210, USA.
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15
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Abstract
Cancer-associated DNA hypomethylation is as prevalent as cancer-linked hypermethylation, but these two types of epigenetic abnormalities usually seem to affect different DNA sequences. Much more of the genome is generally subject to undermethylation rather than overmethylation. Genomic hypermethylation in cancer has been observed most often in CpG islands in gene regions. In contrast, very frequent hypomethylation is seen in both highly and moderately repeated DNA sequences in cancer, including heterochromatic DNA repeats, dispersed retrotransposons, and endogenous retroviral elements. Also, unique sequences, including transcription control sequences, are often subject to cancer-associated undermethylation. The high frequency of cancer-linked DNA hypomethylation, the nature of the affected sequences, and the absence of associations with DNA hypermethylation are consistent with an independent role for DNA undermethylation in cancer formation or tumor progression. Increased karyotypic instability and activation of tumor-promoting genes by cis or trans effects, that might include altered heterochromatin-euchromatin interactions, may be important consequences of DNA hypomethylation which favor oncogenesis. The relationship of DNA hypomethylation to tumorigenesis is important to be considered in the light of cancer therapies involving decreasing DNA methylation. Inducing DNA hypomethylation may have short-term anticancer effects, but might also help speed tumor progression from cancer cells surviving the DNA demethylation chemotherapy.
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Affiliation(s)
- Melanie Ehrlich
- Human Genetics Program/SL31, Department of Biochemistry, Tulane Medical School, New Orleans, Louisiana, LA 70122, USA.
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16
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Wimmer K, Zhu Xx XX, Rouillard JM, Ambros PF, Lamb BJ, Kuick R, Eckart M, Weinhäusl A, Fonatsch C, Hanash SM. Combined restriction landmark genomic scanning and virtual genome scans identify a novel human homeobox gene, ALX3, that is hypermethylated in neuroblastoma. Genes Chromosomes Cancer 2002; 33:285-94. [PMID: 11807986 DOI: 10.1002/gcc.10030] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Restriction landmark genome scanning (RLGS) allows comparative analysis of several thousand DNA fragments in the genome and provides a means to identify CpG islands that are altered in tumor cells as a result of amplification, deletion, or methylation changes. We have developed a novel informatics tool, designated virtual genome scan (VGS), that makes it possible to predict automatically the sequence of fragments in RLGS patterns by matching to the human genome sequence. A combination of RLGS and VGS was utilized to identify changes of chromosome 1-derived fragments in neuroblastoma. A NotI-EcoRV fragment was found to be absent frequently in neuroblastoma cell line RLGS patterns. Sequence prediction by VGS as well as cloning of the fragment showed that it contained a CpG island that is part of the human orthologue of the hamster homeobox gene Alx3. Expression analysis in a panel of human and mouse tissues showed predominant expression of ALX3 in brain tissue. Methylation-sensitive sequence analysis of the promoter region in neuroblastoma cell lines indicated that methylation of specific sequences correlated with repression of the ALX3 gene. Expression was re-induced after treatment with the methylation inhibitor 5-aza-2'-deoxycytidine. Promoter methylation analysis of ALX3 in primary neuroblastoma tumors, using methylation-sensitive polymerase chain reaction, found preferential ALX3 methylation in advanced-stage tumors. The VGS approach we have implemented in combination with RLGS is useful for the identification of genomic CpG island-related methylation changes or deletions in cancer.
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Affiliation(s)
- Katharina Wimmer
- Institut für Medizinische Biologie, Universität Wien, Vienna, Austria.
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Rouillard JM, Erson AE, Kuick R, Asakawa J, Wimmer K, Muleris M, Petty EM, Hanash S. Virtual genome scan: a tool for restriction landmark-based scanning of the human genome. Genome Res 2001; 11:1453-9. [PMID: 11483587 PMCID: PMC311067 DOI: 10.1101/gr.181601] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
There is substantial interest in implementing technologies that allow comparisons of whole genomes of individuals and of tissues and cell populations. Restriction landmark genome scanning (RLGS) is a highly resolving gel-based technique in which several thousand fragments in genomic digests are visualized simultaneously and quantitatively analyzed. The widespread use of RLGS has been hampered by difficulty in deriving sequence information for displayed fragments and a lack of whole-genome sequence-based framework for interpreting RLGS patterns. We have developed informatics tools for comparisons of sample derived RLGS patterns with patterns predicted from the human genome sequence and displayed as Virtual Genome Scans (VGS). The tools developed allow sequence prediction of fragments in RLGS patterns obtained with different restriction enzyme combinations. The utility of VGS is demonstrated by the identification of restriction fragment length polymorphisms, and of amplifications, deletions, and methylation changes in tumor-derived CpG islands and the characterization of an amplified region in a breast tumor that spanned <230 kb on 17q23.
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Affiliation(s)
- J M Rouillard
- Department of Pediatrics, University of Michigan, Ann Arbor 48109, USA
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18
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Wimmer K, Zhu XX, Lamb BJ, Kuick R, Ambros P, Kovar H, Thoraval D, Elkahloun A, Meltzer P, Hanash SM. Two-dimensional DNA electrophoresis identifies novel CpG islands frequently coamplified with MYCN in neuroblastoma. MEDICAL AND PEDIATRIC ONCOLOGY 2001; 36:75-9. [PMID: 11464910 DOI: 10.1002/1096-911x(20010101)36:1<75::aid-mpo1018>3.0.co;2-o] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Amplification of the oncogene MYCN in neuroblastoma has been found to correlate with aggressive tumour growth and is used as a predictor of clinical outcome. The MYCN amplicon is known to involve coamplification of extensive DNA regions. Therefore it is possible that other genes are coamplified in this amplicon and that they may play a role in the poor outcome of MYCN amplified tumours. PROCEDURE We have implemented an approach for the two-dimensional separation of human genomic restriction fragments to detect and isolate as yet unknown amplified sequences in the MYCN amplicon in neuroblastoma. Using this approach we have recently cloned a novel gene referred to as NAG that is frequently coamplified with MYCN in neuroblastoma. RESULTS AND CONCLUSIONS We report here the identification and cloning of two additional CpG islands that are amplified in neuroblastoma. One contains a sequence that is identical to the first intron of DDX1. The other represents a novel CpG island that is associated with an as yet unidentified gene. We show that the novel CpG island is located in close proximity to the MYCN locus on chromosome 2 and is as frequently coamplified with MYCN in neuroblastoma as NAG and DDX1.
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MESH Headings
- Chromosomes, Human, Pair 1/genetics
- Chromosomes, Human, Pair 1/ultrastructure
- Cloning, Molecular
- CpG Islands
- DNA, Neoplasm/genetics
- Electrophoresis, Gel, Two-Dimensional
- Gene Amplification
- Genes, myc
- Humans
- In Situ Hybridization, Fluorescence
- Neuroblastoma/genetics
- Polymorphism, Restriction Fragment Length
- Tumor Cells, Cultured
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Affiliation(s)
- K Wimmer
- Department of Pediatrics, University of Michigan, Ann Arbor, USA.
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Csonka E, Cserpán I, Fodor K, Holló G, Katona R, Keresö J, Praznovszky T, Szakál B, Telenius A, deJong G, Udvardy A, Hadlaczky G. Novel generation of human satellite DNA-based artificial chromosomes in mammalian cells. J Cell Sci 2000; 113 ( Pt 18):3207-16. [PMID: 10954419 DOI: 10.1242/jcs.113.18.3207] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An in vivo approach has been developed for generation of artificial chromosomes, based on the induction of intrinsic, large-scale amplification mechanisms of mammalian cells. Here, we describe the successful generation of prototype human satellite DNA-based artificial chromosomes via amplification-dependent de novo chromosome formations induced by integration of exogenous DNA sequences into the centromeric/rDNA regions of human acrocentric chromosomes. Subclones with mitotically stable de novo chromosomes were established, which allowed the initial characterization and purification of these artificial chromosomes. Because of the low complexity of their DNA content, they may serve as a useful tool to study the structure and function of higher eukaryotic chromosomes. Human satellite DNA-based artificial chromosomes containing amplified satellite DNA, rDNA, and exogenous DNA sequences were heterochromatic, however, they provided a suitable chromosomal environment for the expression of the integrated exogenous genetic material. We demonstrate that induced de novo chromosome formation is a reproducible and effective methodology in generating artificial chromosomes from predictable sequences of different mammalian species. Satellite DNA-based artificial chromosomes formed by induced large-scale amplifications on the short arm of human acrocentric chromosomes may become safe or low risk vectors in gene therapy.
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Affiliation(s)
- E Csonka
- Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, Hungary
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Tuck-Muller CM, Narayan A, Tsien F, Smeets DF, Sawyer J, Fiala ES, Sohn OS, Ehrlich M. DNA hypomethylation and unusual chromosome instability in cell lines from ICF syndrome patients. CYTOGENETICS AND CELL GENETICS 2000; 89:121-8. [PMID: 10894953 DOI: 10.1159/000015590] [Citation(s) in RCA: 154] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The ICF syndrome (immunodeficiency, centromeric region instability, facial anomalies) is a unique DNA methylation deficiency disease diagnosed by an extraordinary collection of chromosomal anomalies specifically in the vicinity of the centromeres of chromosomes 1 and 16 (Chr1 and Chr16) in mitogen-stimulated lymphocytes. These aberrations include decondensation of centromere-adjacent (qh) heterochromatin, multiradial chromosomes with up to 12 arms, and whole-arm deletions. We demonstrate that lymphoblastoid cell lines from two ICF patients exhibit these Chr1 and Chr16 anomalies in 61% of the cells and continuously generate 1qh or 16qh breaks. No other consistent chromosomal abnormality was seen except for various telomeric associations, which had not been previously noted in ICF cells. Surprisingly, multiradials composed of arms of both Chr1 and Chr16 were favored over homologous associations and cells containing multiradials with 3 or >4 arms almost always displayed losses or gains of Chr1 or Chr16 arms from the metaphase. Our results suggest that decondensation of 1qh and 16qh often leads to unresolved Holliday junctions, chromosome breakage, arm missegregation, and the formation of multiradials that may yield more stable chromosomal abnormalities, such as translocations. These cell lines maintained the abnormal hypomethylation in 1qh and 16qh seen in ICF tissues. The ICF-specific hypomethylation occurs in only a small percentage of the genome, e.g., ICF brain DNA had 7% less 5-methylcytosine than normal brain DNA. The ICF lymphoblastoid cell lines, therefore, retain not only the ICF-specific pattern of chromosome rearrangements, but also of targeted DNA hypomethylation. This hypomethylation of heterochromatic DNA sequences is seen in many cancers and may predispose to chromosome rearrangements in cancer as well as in ICF.
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Affiliation(s)
- C M Tuck-Muller
- Department of Medical Genetics, University of South Alabama, Mobile, AL, USA
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21
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Zhu X, Deng C, Kuick R, Yung R, Lamb B, Neel JV, Richardson B, Hanash S. Analysis of human peripheral blood T cells and single-cell-derived T cell clones uncovers extensive clonal CpG island methylation heterogeneity throughout the genome. Proc Natl Acad Sci U S A 1999; 96:8058-63. [PMID: 10393947 PMCID: PMC22187 DOI: 10.1073/pnas.96.14.8058] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Methylation of cytosine residues in CpG dinucleotides is generally associated with silencing of gene expression. DNA methylation, as a somatic event, has the potential of diversifying gene expression in individual cells of the same lineage. There is little quantitative data available concerning the extent of methylation heterogeneity in individual cells across the genome. T cells from the peripheral blood can be grown as single-cell-derived clones and can be analyzed with respect to their DNA methylation patterns by restriction landmark genomic scanning. The use of the methylation-sensitive enzyme NotI to cut and end-label DNA fragments before their separation in two dimensions provides a quantitative assessment of methylation at NotI sites that characteristically occur in CpG islands. We have undertaken quantitative analysis of two-dimensional DNA patterns to determine the extent of methylation heterogeneity at NotI sites between peripheral blood single-cell-derived T cell clones from the same individual. A total of 1,068 NotI-tagged fragments were analyzed. A subset of 156 fragments exhibited marked methylation heterogeneity at NotI sites between clones. Their average intensity among clones correlated with their intensity in uncultured, whole-blood-derived T cells, indicating that the methylation heterogeneity observed in clones was largely attributable to methylation heterogeneity between the individual cells from which the clones were derived. We have cloned one fragment that exhibited variable NotI-site methylation between clones. This fragment contained a novel CpG island for a gene that we mapped to chromosome 4. The methylation status of the NotI site of this fragment correlated with expression of the corresponding gene. Our data suggest extensive diversity in vivo in the methylation and expression profiles of individual T cells at multiple unrelated loci across the genome.
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Affiliation(s)
- X Zhu
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, MI 48109, USA
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22
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Abstract
We have developed a simplified procedure for the separation of enzyme-digested genomic DNA, or of complex mixtures of cloned DNA, into two dimensions. The procedure relies on the use of precast gels for horizontal electrophoretic separations. Precast agarose-type gels are used for the first-dimensional separation of fragments based on size. Precast polyacrylamide gels are used for the second-dimensional separation of fragments. The separated fragments are subjected to enzymatic digestion in situ prior to their transfer to the second-dimensional gel. Applications of this procedure include the analysis of DNA libraries, analysis of yeast artificial chromosomes (YACs) as well as other similar preparations, and the screening of genomic DNA for the occurrence of multi-copy DNA fragments as in the case of genomic amplifications in cancer.
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Affiliation(s)
- H Schickle
- ETC Elektrophorese-Technik, Kirchentellinsfurt, Germany
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23
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Wimmer K, Zhu XX, Lamb BJ, Kuick R, Ambros PF, Kovar H, Thoraval D, Motyka S, Alberts JR, Hanash SM. Co-amplification of a novel gene, NAG, with the N-myc gene in neuroblastoma. Oncogene 1999; 18:233-8. [PMID: 9926938 DOI: 10.1038/sj.onc.1202287] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Substantial evidence implicates amplification of the N-myc gene with aggressive tumor growth and poor outcome in neuroblastoma. However some evidence suggests that this gene alone is not the sole determinant of outcome in N-myc amplified tumors. We have searched for genes that co-amplify with N-myc in neuroblastoma by means of two-dimensional analysis of genomic restriction digests. Using this approach, we have identified and cloned a novel genomic fragment which is co-amplified with N-myc in neuroblastomas. This fragment was mapped in close vicinity to N-myc on chromosome arm 2p24. It was amplified in 5/8 N-myc amplified neuroblastoma cell lines and in 9/13 N-myc amplified tumors. Using a PCR-based approach we isolated a 4.5 kb c-DNA sequence that is partly contained in the genomic fragment. The open reading frame of the cDNA encodes a predicted protein of 1353 amino acids (aa). The homology of the predicted protein, which we designated NAG (neuroblastoma amplified gene), to a C. elegans protein of as yet unknown function, and its ubiquitous expression suggest that NAG may serve an essential function. By Northern blot analysis we showed that amplification of the cloned gene correlates with over-expression in neuroblastoma cell lines. Amplification and consequent over-expression of NAG may, therefore, contribute to the phenotype of a subset of neuroblastomas.
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Affiliation(s)
- K Wimmer
- University of Michigan, Department of Pediatrics, Ann Arbor 48109-0510, USA
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Shiels C, Coutelle C, Huxley C. Contiguous arrays of satellites 1, 3, and beta form a 1.5-Mb domain on chromosome 22p. Genomics 1997; 44:35-44. [PMID: 9286698 DOI: 10.1006/geno.1997.4817] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The centromeric heterochromatin of all the human chromosomes is composed of megabases of tandemly repeated satellite DNA. Some of these sequences have been implicated in centromere formation and/or segregation but the arrangement of most of them on a large scale remains largely uncharacterized because of the difficulties in analyzing repetitive DNA. The alpha satellite is the best studied and is present in large tandem arrays at all centromeres, but satellites 1, 3, and beta have also been detected on a number of chromosomes. Here we have used FISH to extended DNA fibers to analyze these satellites on the short arm of the acrocentric chromosome 22. The satellite sequences were found to form a continuous domain spanning about 1.5 Mb and consisting of a major block of satellite 1 flanked by two blocks of beta satellite and three blocks of satellite 3. These six blocks of satellite DNA appear to form contiguous arrays with little intervening DNA.
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Affiliation(s)
- C Shiels
- Department of Biochemistry and Molecular Genetics, Imperial College School of Medicine at St. Mary's, London, United Kingdom
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25
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Mostoslavsky R, Bergman Y. DNA methylation: regulation of gene expression and role in the immune system. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1333:F29-50. [PMID: 9294017 DOI: 10.1016/s0304-419x(97)00010-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- R Mostoslavsky
- The Hubert H. Humphrey Center for Experimental Medicine and Cancer Research, The Hebrew University Hadassah Medical School, Jerusalem, Israel
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Thoraval D, Asakawa J, Wimmer K, Kuick R, Lamb B, Richardson B, Ambros P, Glover T, Hanash S. Demethylation of repetitive DNA sequences in neuroblastoma. Genes Chromosomes Cancer 1996; 17:234-44. [PMID: 8946205 DOI: 10.1002/(sici)1098-2264(199612)17:4<234::aid-gcc5>3.0.co;2-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Altered genomic methylcytosine content has been described for a number of tumor types, including neuroblastoma. However, it remains to be determined for different tumor types whether specific loci or chromosomal regions are affected by a methylation change or whether the change is random. We have implemented a computer-based approach for the analysis of two-dimensional separations of human genomic restriction fragments. Through the use of methylation-sensitive restriction enzymes, methylation differences in genomic DNA between tumor and normal tissues can be detected. We report the cloning and sequencing of two fragments detectable in two-dimensional separations of genomic DNA of neuroblastomas. These fragments were found to be a part of repetitive units that exhibited demethylation in neuroblastoma relative to other tumor types. Our finding of a distinct pattern of methylation of repetitive units in neuroblastoma suggests that altered methylation at certain loci may contribute to the biology of this tumor.
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Affiliation(s)
- D Thoraval
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor 48109-0510, USA
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27
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Wimmer K, Kuick R, Thoraval D, Hanash SM. Two-dimensional separations of the genome and proteome of neuroblastoma cells. Electrophoresis 1996; 17:1741-51. [PMID: 8982607 DOI: 10.1002/elps.1150171112] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Two-dimensional (2-D) electrophoretic methods have been available that allow separation of the protein constituents of a cell population. It has also become feasible to electrophoretically separate in two dimensions and to display DNA fragments derived from genomic digests. Through the appropriate choice of restriction enzymes, the functional component of the genome that encompasses CpG islands can be preferentially visualized in 2-D gels. The same computerized approach for the analysis of 2-D patterns can be applied to investigations at either the protein or DNA levels. Our group has utilized 2-D electrophoresis to investigate both protein and DNA changes in cancer. The emphasis to date has been on the identification of proteins, the abundance of which is related to specific biological features of the tumors analyzed and of DNA fragments encompassed in genomic amplifications, as the latter commonly contain growth-related genes. Findings derived from our analysis of neuroblastoma tumors and cell lines using 2-D approaches are reviewed. Data for four proteins observed in 2-D gels are presented because of our demonstrated association of these proteins with differentiation and proliferation properties of neuroblastoma. At the genomic level, the detection of amplifications using 2-D gels has necessitated an understanding of the variability displayed by multi-copy genomic fragments, which we have accomplished to a large part and which we present. An important benefit of 2-D approaches is the efficiency of scale and the ease with which abundant proteins or multicopy genomic fragments can be detected, identified and quantitatively analyzed.
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Affiliation(s)
- K Wimmer
- University of Michigan School of Medicine, Department of Pediatric Hematology/Oncology, Ann Arbor, USA
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