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Mirceta M, Shum N, Schmidt MHM, Pearson CE. Fragile sites, chromosomal lesions, tandem repeats, and disease. Front Genet 2022; 13:985975. [PMID: 36468036 PMCID: PMC9714581 DOI: 10.3389/fgene.2022.985975] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 09/02/2022] [Indexed: 09/16/2023] Open
Abstract
Expanded tandem repeat DNAs are associated with various unusual chromosomal lesions, despiralizations, multi-branched inter-chromosomal associations, and fragile sites. Fragile sites cytogenetically manifest as localized gaps or discontinuities in chromosome structure and are an important genetic, biological, and health-related phenomena. Common fragile sites (∼230), present in most individuals, are induced by aphidicolin and can be associated with cancer; of the 27 molecularly-mapped common sites, none are associated with a particular DNA sequence motif. Rare fragile sites ( ≳ 40 known), ≤ 5% of the population (may be as few as a single individual), can be associated with neurodevelopmental disease. All 10 molecularly-mapped folate-sensitive fragile sites, the largest category of rare fragile sites, are caused by gene-specific CGG/CCG tandem repeat expansions that are aberrantly CpG methylated and include FRAXA, FRAXE, FRAXF, FRA2A, FRA7A, FRA10A, FRA11A, FRA11B, FRA12A, and FRA16A. The minisatellite-associated rare fragile sites, FRA10B, FRA16B, can be induced by AT-rich DNA-ligands or nucleotide analogs. Despiralized lesions and multi-branched inter-chromosomal associations at the heterochromatic satellite repeats of chromosomes 1, 9, 16 are inducible by de-methylating agents like 5-azadeoxycytidine and can spontaneously arise in patients with ICF syndrome (Immunodeficiency Centromeric instability and Facial anomalies) with mutations in genes regulating DNA methylation. ICF individuals have hypomethylated satellites I-III, alpha-satellites, and subtelomeric repeats. Ribosomal repeats and subtelomeric D4Z4 megasatellites/macrosatellites, are associated with chromosome location, fragility, and disease. Telomere repeats can also assume fragile sites. Dietary deficiencies of folate or vitamin B12, or drug insults are associated with megaloblastic and/or pernicious anemia, that display chromosomes with fragile sites. The recent discovery of many new tandem repeat expansion loci, with varied repeat motifs, where motif lengths can range from mono-nucleotides to megabase units, could be the molecular cause of new fragile sites, or other chromosomal lesions. This review focuses on repeat-associated fragility, covering their induction, cytogenetics, epigenetics, cell type specificity, genetic instability (repeat instability, micronuclei, deletions/rearrangements, and sister chromatid exchange), unusual heritability, disease association, and penetrance. Understanding tandem repeat-associated chromosomal fragile sites provides insight to chromosome structure, genome packaging, genetic instability, and disease.
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Affiliation(s)
- Mila Mirceta
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Natalie Shum
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Monika H. M. Schmidt
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Christopher E. Pearson
- Program of Genetics and Genome Biology, The Hospital for Sick Children, The Peter Gilgan Centre for Research and Learning, Toronto, ON, Canada
- Program of Molecular Genetics, University of Toronto, Toronto, ON, Canada
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Campos AS, Favarato RM, Feldberg E. Interspecific cytogenetic relationships in three Acestrohynchus species (Acestrohynchinae, Characiformes) reveal the existence of possible cryptic species. COMPARATIVE CYTOGENETICS 2020; 14:27-42. [PMID: 31998448 PMCID: PMC6976687 DOI: 10.3897/compcytogen.v14i1.33483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 11/27/2019] [Indexed: 06/10/2023]
Abstract
The karyotypes and chromosomal characteristics of three Acestrorhynchus Eigenmann et Kennedy, 1903 species were examined using conventional and molecular protocols. These species had invariably a diploid chromosome number 2n = 50. Acestrorhynchus falcatus (Block, 1794) and Acestrorhynchus falcirostris (Cuvier, 1819) had the karyotype composed of 16 metacentric (m) + 28 submetacentric (sm) + 6 subtelocentric (st) chromosomes while Acestrorhynchus microlepis (Schomburgk, 1841) had the karyotype composed of 14m+30sm+6st elements. In this species, differences of the conventional and molecular markers between the populations of Catalão Lake (AM) and of Apeu Stream (PA) were found. Thus the individuals of Pará (Apeu) were named Acestrorhynchus prope microlepis. The distribution of the constitutive heterochromatin blocks was species-specific, with C-positive bands in the centromeric and telomeric regions of a number of different chromosomes, as well as in interstitial sites and completely heterochromatic arms. The phenotypes of nucleolus organizer region (NOR) were simple, i. e. in a terminal position on the p arm of pair No. 23 except in A. microlepis, in which it was located on the q arm. Fluorescence in situ hybridization (FISH) revealed 18S rDNA sites on one chromosome pair in karyotype of A. falcirostris and A. prope microlepis (pair No. 23) and three pairs (Nos. 12, 23, 24) in A. falcatus and (Nos. 8, 23, 24) in A. microlepis; 5S rDNA sites were detected in one chromosome pair in all three species. The mapping of the telomeric sequences revealed terminal sequences in all the chromosomes, as well as the presence of interstitial telomeric sequences (ITSs) in a number of chromosome pairs. The cytogenetic data recorded in the present study indicate that A. prope microlepis may be an unnamed species.
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Affiliation(s)
- Alber Sousa Campos
- Programa de Pós-Graduação em Genética, Conservação e Biologia Evolutiva (PPG GCBEv). Coordenação de Biodiversidade, Instituto Nacional de Pesquisas da Amazônia, , Av. André Araújo, 2936, Petrópolis, Manaus, Amazonas, BrazilInstituto Nacional de Pesquisas da AmazôniaManausBrazil
| | - Ramon Marin Favarato
- Programa de Pós-Graduação em Genética, Conservação e Biologia Evolutiva (PPG GCBEv). Coordenação de Biodiversidade, Instituto Nacional de Pesquisas da Amazônia, , Av. André Araújo, 2936, Petrópolis, Manaus, Amazonas, BrazilInstituto Nacional de Pesquisas da AmazôniaManausBrazil
| | - Eliana Feldberg
- Programa de Pós-Graduação em Genética, Conservação e Biologia Evolutiva (PPG GCBEv). Coordenação de Biodiversidade, Instituto Nacional de Pesquisas da Amazônia, , Av. André Araújo, 2936, Petrópolis, Manaus, Amazonas, BrazilInstituto Nacional de Pesquisas da AmazôniaManausBrazil
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Silva CEFE, Souza ÉMSD, Eler ES, Silva MNFD, Feldberg E. Comparison of the heterochromatin and telomeric sequences distribuition in chromosomes of 11 species of Amazonian marsupials (Didelphimorphia; Didelphidae). Genet Mol Biol 2020; 43:e20190357. [PMID: 32396598 PMCID: PMC7216969 DOI: 10.1590/1678-4685-gmb-2019-0357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 02/18/2020] [Indexed: 12/02/2022] Open
Abstract
In recent decades the diploid numbers recorded in the New World marsupials have
been widely discussed in the context of the processes of karyotype evolution in
these mammals. While Interstitial Telomeric Sequences (ITS) have long been
interpreted as remnants of chromosomal fusion, the biological role of these
features, together with their intraspecific variation, has raised a number of
questions. In the present study, we analyzed the karyotype of 11 species of
Amazonian didelphids, comparing the distribution of the heterochromatin with
that of the telomeric signals, and found that, in six species, the ITS coincided
with the blocks of heterochromatin. While ITS were found in the X chromosomes of
all Marmosa murina individuals, they were variable in all the
other species, representing a specific character of each lineage. Our results
support the conclusion that ITS may not always be a consequence of chromosomal
rearrangements, and that the mechanisms that produce them are still unclear.
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Affiliation(s)
| | | | - Eduardo Schmidt Eler
- Instituto Nacional de Pesquisas da Amazônia, Brazil; Universidade Anhembi Morumbi, Brazil
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Ojima M, Hirouchi T, Etani R, Ariyoshi K, Fujishima Y, Kai M. Dose-Rate-Dependent PU.1 Inactivation to Develop Acute Myeloid Leukemia in Mice Through Persistent Stem Cell Proliferation After Acute or Chronic Gamma Irradiation. Radiat Res 2019; 192:612-620. [PMID: 31560640 DOI: 10.1667/rr15359.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Radiation-induced acute myeloid leukemia (rAML) in C3H mice is commonly developed through inactivation of PU.1 transcription factor encoded in Sfpi1 on chromosome 2. PU.1 inactivation involves two steps: hemizygous deletion of the Sfpi1 gene (DSG) and point mutation of the allele Sfpi1 gene (PMASG). In this study, we investigated the dose-rate dependence of the frequency of both DSG and PMASG in hematopoietic stem cells (HSCs) of C3H mice that received a total of 3 Gy gamma-ray exposure at dose rates of 20 mGy/day, 200 mGy/day or 1,000 mGy/min. All mice were followed for 250 days from start of irradiation. Fluorescent in situ hybridization of the Sfpi1 gene site indicated that frequency of HSCs with DSG was proportional to dose rate. In cell surface profiles, PU.1-inactivated HSCs by both DSG and PMASG were still positive for PU.1, but negative for GM-CSF receptor-α (GMCSFRα), which is transcriptionally regulated by PU.1. Immunofluorescent staining analysis of both PU.1 and GM-CSFRα also showed dose-rate-dependent levels of PU.1-inactivated HSCs. This study provides evidence that both DSG and PMASG are dose-rate dependent; these experimental data offer new insights into the dose-rate effects in HSCs that can lead to radiation-induced leukemogenesis.
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Affiliation(s)
- Mitsuaki Ojima
- Department of Environmental Health Science, Oita University of Nursing and Health Sciences, Oita 840-1201, Japan
| | | | - Reo Etani
- Department of Environmental Health Science, Oita University of Nursing and Health Sciences, Oita 840-1201, Japan
| | - Kentaro Ariyoshi
- Institute of Radiation Emergency Medicine, Hirosaki University, Aomori 036-8564, Japan and Department of Radiation Biology, Tohoku University School of Medicine, Sendai, Japan
| | - Yohei Fujishima
- Institute of Radiation Emergency Medicine, Hirosaki University, Aomori 036-8564, Japan and Department of Radiation Biology, Tohoku University School of Medicine, Sendai, Japan
| | - Michiaki Kai
- Department of Environmental Health Science, Oita University of Nursing and Health Sciences, Oita 840-1201, Japan
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Ren L, Chen L, Wu W, Garribba L, Tian H, Liu Z, Vogel I, Li C, Hickson ID, Liu Y. Potential biomarkers of DNA replication stress in cancer. Oncotarget 2018; 8:36996-37008. [PMID: 28445142 PMCID: PMC5514887 DOI: 10.18632/oncotarget.16940] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 03/28/2017] [Indexed: 11/25/2022] Open
Abstract
Oncogene activation is an established driver of tumorigenesis. An apparently inevitable consequence of oncogene activation is the generation of DNA replication stress (RS), a feature common to most cancer cells. RS, in turn, is a causal factor in the development of chromosome instability (CIN), a near universal feature of solid tumors. It is likely that CIN and RS are mutually reinforcing drivers that not only accelerate tumorigenesis, but also permit cancer cells to adapt to diverse and hostile environments. This article reviews the genetic changes present in cancer cells that influence oncogene-induced RS and CIN, with a particular emphasis on regions of the human genome that show enhanced sensitivity to the destabilizing effects of RS, such as common fragile sites. Because RS exists in a wide range of cancer types, we propose that the proteins involved counteracting this stress are potential biomarkers for indicating the degree of RS in cancer specimens. To test this hypothesis, we conducted a pilot study to validate whether some of proteins that are known from in vitro studies to play an essential role in the RS pathway could be suitable as a biomarker. Our results indicated that this is possible. With this review and pilot study, we aim to accelerate the development of a biomarker for analysis of RS in tumor biopsy specimens, which could ultimately help to stratify patients for different forms of therapy such as the RS inhibitors already undergoing clinical trials.
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Affiliation(s)
- Liqun Ren
- Basic Medical Research Institute, Chengde Medical University, Chengde, China
| | - Long Chen
- Basic Medical Research Institute, Chengde Medical University, Chengde, China
| | - Wei Wu
- Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Lorenza Garribba
- Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Huanna Tian
- Basic Medical Research Institute, Chengde Medical University, Chengde, China
| | - Zihui Liu
- Pathology Department, Affiliated Hospital, Chengde Medical University, Chengde, China
| | - Ivan Vogel
- Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Chunhui Li
- Pathology Department, Affiliated Hospital, Chengde Medical University, Chengde, China
| | - Ian D Hickson
- Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark.,Center for Healthy Aging, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Ying Liu
- Center for Chromosome Stability, Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
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Bolzán AD. Interstitial telomeric sequences in vertebrate chromosomes: Origin, function, instability and evolution. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2017; 773:51-65. [PMID: 28927537 DOI: 10.1016/j.mrrev.2017.04.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Revised: 03/13/2017] [Accepted: 04/17/2017] [Indexed: 12/21/2022]
Abstract
By definition, telomeric sequences are located at the very ends or terminal regions of chromosomes. However, several vertebrate species show blocks of (TTAGGG)n repeats present in non-terminal regions of chromosomes, the so-called interstitial telomeric sequences (ITSs), interstitial telomeric repeats or interstitial telomeric bands, which include those intrachromosomal telomeric-like repeats located near (pericentromeric ITSs) or within the centromere (centromeric ITSs) and those telomeric repeats located between the centromere and the telomere (i.e., truly interstitial telomeric sequences) of eukaryotic chromosomes. According with their sequence organization, localization and flanking sequences, ITSs can be classified into four types: 1) short ITSs, 2) subtelomeric ITSs, 3) fusion ITSs, and 4) heterochromatic ITSs. The first three types have been described mainly in the human genome, whereas heterochromatic ITSs have been found in several vertebrate species but not in humans. Several lines of evidence suggest that ITSs play a significant role in genome instability and evolution. This review aims to summarize our current knowledge about the origin, function, instability and evolution of these telomeric-like repeats in vertebrate chromosomes.
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Affiliation(s)
- Alejandro D Bolzán
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE, CICPBA-UNLP-CONICET La Plata), C.C. 403, 1900 La Plata, Argentina; Facultad de Ciencias Naturales y Museo, UNLP, Calle 60 y 122, 1900 La Plata, Argentina.
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Bolzán AD. Chromosomal aberrations involving telomeres and interstitial telomeric sequences. Mutagenesis 2011; 27:1-15. [PMID: 21857006 DOI: 10.1093/mutage/ger052] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Telomeres are specialised nucleoproteic complexes localised at the physical ends of linear eukaryotic chromosomes that maintain their stability and integrity. In vertebrate chromosomes, the DNA component of telomeres is constituted by (TTAGGG)n repeats, which can be localised at the terminal regions of chromosomes (true telomeres) or at intrachromosomal sites (interstitial telomeric sequences or ITSs, located at the centromeric region or between the centromere and the telomere). In the past two decades, the use of molecular cytogenetic techniques has led to a new spectrum of spontaneous and clastogen-induced chromosomal aberrations being identified, involving telomeres and ITSs. Some aberrations involve the chromosome ends and, indirectly, the telomeric repeats located at the terminal regions of chromosomes (true telomeres). A second type of aberrations directly involves the telomeric sequences located at the chromosome ends. Finally, there is a third class of aberrations that specifically involves the ITSs. The aims of this review are to provide a detailed description of these aberrations and to summarise the available data regarding their induction by physical and chemical mutagens.
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Affiliation(s)
- Alejandro D Bolzán
- La Carrera del Investigador Científico y Tecnológico del CONICET, Argentina, Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (CCT-CONICET La Plata-CICPBA), C.C. 403, 1900 La Plata, Argentina.
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Piskorowska J, Gajewska M, Szymańska H, Krysiak E, Quan L, Grygalewicz B, Skurzak HM, Czarnomska A, Pienkowska-Grela B, Demant P. Susceptibility loci and chromosomal abnormalities in radiation induced hematopoietic neoplasms in mice. JOURNAL OF RADIATION RESEARCH 2011; 52:147-158. [PMID: 21343679 DOI: 10.1269/jrr.10035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Genetics of susceptibility to radiation-induced hematopoietic neoplasms and somatic chromosomal aberrations were analyzed in 305 backcross (CcS-17xCcS-2)xCcS-2 mice of two CcS/Dem recombinant congenic strains. Irradiated CcS-2 mice were previously shown to exhibit high frequency of myeloid neoplasms whereas irradiated CcS-17 mice were susceptible to T-cell lymphomas. Mice were exposed to four whole-body irradiation doses of 1.7 Gy at one week intervals, which resulted in 139 hematopoietic neoplasms. The hematopoietic neoplasms were classified according to the Bethesda proposals for classification of lymphoid and nonlymphoid hematopoietic neoplasms in mice. Genotyping of mice with 24 microsatellite markers and subsequent statistical analysis indicated linkage of the radiation induced T-lymphomas to two loci on chromosome 10 (D10Mit134) and chromosome 12 (D12Mit52). T-lymphoma susceptibility appeared to be linked to D10Mit134 in a sex dependent way. In contrast, the myeloid-granulocytic leukemias susceptibility is linked to combined effects of chromosome 5 (D5Mit179) and 16 (D16Mit34). Cytogenetic analysis was performed according to the standard G-bands procedure and confirmed using FISH method. We found non-random numerical and structural chromosomal changes in lymphoid neoplasms. Cytogenetic analysis indicated chromosomal aberrations presumably associated with lymphomagenesis, no specific cancer-related rearrangements were observed.
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Affiliation(s)
- Joanna Piskorowska
- Department of Genetics and Laboratory Animal Breeding, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland
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Peng Y, Brown N, Finnon R, Warner CL, Liu X, Genik PC, Callan MA, Ray FA, Borak TB, Badie C, Bouffler SD, Ullrich RL, Bedford JS, Weil MM. Radiation Leukemogenesis in Mice: Loss ofPU.1on Chromosome 2 in CBA and C57BL/6 Mice after Irradiation with 1 GeV/nucleon56Fe Ions, X Rays or γ Rays. Part I. Experimental Observations. Radiat Res 2009; 171:474-83. [PMID: 19397448 DOI: 10.1667/rr1547.1] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- Yuanlin Peng
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523, USA.
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Comparison of murine gene expression profiles between spontaneous and radiation-induced myelogenous leukemias: Stochastic and probabilistic expression variances in the former vs radiation-specific expression commonalities in the latter. Exp Hematol 2009; 37:195-205. [DOI: 10.1016/j.exphem.2008.10.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2008] [Revised: 09/29/2008] [Accepted: 10/06/2008] [Indexed: 11/20/2022]
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Bolzán AD, Bianchi MS. Telomeres, interstitial telomeric repeat sequences, and chromosomal aberrations. Mutat Res 2006; 612:189-214. [PMID: 16490380 DOI: 10.1016/j.mrrev.2005.12.003] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Revised: 12/29/2005] [Accepted: 12/30/2005] [Indexed: 11/18/2022]
Abstract
Telomeres are specialized nucleoproteic complexes localized at the physical ends of linear eukaryotic chromosomes that maintain their stability and integrity. The DNA component of telomeres is characterized by being a G-rich double stranded DNA composed by short fragments tandemly repeated with different sequences depending on the species considered. At the chromosome level, telomeres or, more properly, telomeric repeats--the DNA component of telomeres--can be detected either by using the fluorescence in situ hybridization (FISH) technique with a DNA or a peptide nucleic acid (PNA) (pan)telomeric probe, i.e., which identifies simultaneously all of the telomeres in a metaphase cell, or by the primed in situ labeling (PRINS) reaction using an oligonucleotide primer complementary to the telomeric DNA repeated sequence. Using these techniques, incomplete chromosome elements, acentric fragments, amplification and translocation of telomeric repeat sequences, telomeric associations and telomeric fusions can be identified. In addition, chromosome orientation (CO)-FISH allows to discriminate between the different types of telomeric fusions, namely telomere-telomere and telomere-DNA double strand break fusions and to detect recombination events at the telomere, i.e., telomeric sister-chromatid exchanges (T-SCE). In this review, we summarize our current knowledge of chromosomal aberrations involving telomeres and interstitial telomeric repeat sequences and their induction by physical and chemical mutagens. Since all of the studies on the induction of these types of aberrations were conducted in mammalian cells, the review will be focused on the chromosomal aberrations involving the TTAGGG sequence, i.e., the telomeric repeat sequence that "caps" the chromosomes of all vertebrate species.
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Affiliation(s)
- Alejandro D Bolzán
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE), C.C. 403, 1900 La Plata, Argentina.
| | - Martha S Bianchi
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE), C.C. 403, 1900 La Plata, Argentina
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Galkina S, Lukina N, Zakharova K, Rodionov AV. Interstitial (TTAGGG)(n) sequences are not hot spots of recombination in the chicken lampbrush macrochromosomes 1-3. Chromosome Res 2006; 13:551-7. [PMID: 16170619 DOI: 10.1007/s10577-005-0980-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2005] [Accepted: 05/04/2005] [Indexed: 11/26/2022]
Abstract
To study the role of telomere (TTAGGG)(n) sequences in promoting of crossing over in chicken female meiosis, we have localized telomere repeats by FISH and studied the distribution of chiasmata in the giant diplotene bivalents, the chicken lampbrush macrochromosomes 1--3. We show that all interstitial clusters of the (TTAGGG)(n) repeat in these chromosomes do not coincide with hot spots of genetic recombination (crossing over) in the chicken female. Moreover, terminal TTAGGG-positive chromomeres also are not chiasma hot spots. We conclude that, at least in chicken macrochromosomes in female meiosis, a role for canonical telomere sequences in promoting of crossing over is not confirmed.
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Affiliation(s)
- Svetlana Galkina
- Biological Institute of St. Petersburg State University, Stary Peterhof, St. Petersburg 198504, Russia
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Delany ME, Daniels LM, Swanberg SE, Taylor HA. Telomeres in the chicken: genome stability and chromosome ends. Poult Sci 2003; 82:917-26. [PMID: 12817446 DOI: 10.1093/ps/82.6.917] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Telomeres are the complex nucleoprotein structures at the termini of linear chromosomes. Telomeric DNA consists of a highly conserved hexanucleotide arranged in tandem repeats. Telomerase, a ribonucleoprotein of the reverse transcriptase family, specifies the sequence of telomeric DNA and maintains telomere array length. Numerous studies in model organisms established the significance of telomere structure and function in regulating genome stability, cellular aging, and oncogenesis. Our overall research objectives are to understand the organization of the telomere arrays in chicken in the context of the unusual organization and specialized features of this higher vertebrate genome (which include a compact genome, numerous microchromosomes, and high recombination rate) and to elucidate the role telomeres play in genome stability impacting cell function and life span. Recent studies found that the chicken genome contains three overlapping size classes of telomere arrays that differ in location and age-related stability: Class I 0.5 to 10 kb, Class II 10 to 40 kb, and Class III 40 kb to 2 Mb. Some notable features of chicken telomere biology are that the chicken genome contains ten times more telomeric DNA than the human genome and the Class III telomere arrays are the largest described for any vertebrate species. In vivo, chicken telomeres (Class II) shorten in an age-related fashion and telomerase activity is high in early stage embryos and developing organs but down-regulates during late embryogenesis or postnatally in most somatic tissues. In vitro, chicken cells down-regulate telomerase activity unless transformed. Knowledge of chicken telomere biology contributes information relevant to present and future biotechnology applications of chickens in vivo and chicken cells in vitro.
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Affiliation(s)
- M E Delany
- Department of Animal Science, University of California, One Shields Ave., Davis, California 95616, USA.
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Hanmoto H, Fujikawa K, Itoh T, Yonezawa Y. Repetitious Production of Similar Karyotypes in Different Plants of Haplopappus gracilis, an Annual Asteraceae, Following Exposure to Ionizing Radiation. CYTOLOGIA 2003. [DOI: 10.1508/cytologia.68.413] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Bedford JS, Dewey WC. Radiation Research Society. 1952-2002. Historical and current highlights in radiation biology: has anything important been learned by irradiating cells? Radiat Res 2002; 158:251-91. [PMID: 12175305 DOI: 10.1667/0033-7587(2002)158[0251:hachir]2.0.co;2] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Around 30 years ago, a very prominent molecular biologist confidently proclaimed that nothing of fundamental importance has ever been learned by irradiating cells! The poor man obviously did not know about discoveries such as DNA repair, mutagenesis, connections between mutagenesis and carcinogenesis, genomic instability, transposable genetic elements, cell cycle checkpoints, or lines of evidence historically linking the genetic material with nucleic acids, or origins of the subject of oxidative stress in organisms, to name a few things of fundamental importance learned by irradiating cells that were well known even at that time. Early radiation studies were, quite naturally, phenomenological. They led to the realization that radiations could cause pronounced biological effects. This was followed by an accelerating expansion of investigations of the nature of these radiobiological phenomena, the beginnings of studies aimed toward better understanding the underlying mechanisms, and a better appreciation of the far-reaching implications for biology, and for society in general. Areas of principal importance included acute tissue and tumor responses for applications in medicine, whole-body radiation effects in plants and animals, radiation genetics and cytogenetics, mutagenesis, carcinogenesis, cellular radiation responses including cell reproductive death, cell cycle effects and checkpoint responses, underlying molecular targets leading to biological effects, DNA repair, and the genetic control of radiosensitivity. This review summarizes some of the highlights in these areas, and points to numerous examples where indeed, many things of considerable fundamental importance have been learned by irradiating cells.
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Affiliation(s)
- Joel S Bedford
- Department of Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523-1673, USA.
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16
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Finnon R, Moody J, Meijne E, Haines J, Clark D, Edwards A, Cox R, Silver A. A major breakpoint cluster domain in murine radiation-induced acute myeloid leukemia. Mol Carcinog 2002; 34:64-71. [PMID: 12112312 DOI: 10.1002/mc.10054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Cytogenetic and molecular studies have provided evidence of the clustering of chromosome 2 deletion breakpoints in radiation-induced murine acute myeloid leukemia (AML). Moreover, clustering occurs in at least two fragile domains rich in telomere-like arrays. Here we describe a physical map of the distal breakpoint cluster and confirm the presence of inverted head-to-head telomeric sequence arrays. These potentially recombinogenic sequences were not, however, the direct focus for post-irradiation chromosome breakage in AML. Instead, the two arrays bordered a 2.5-kb sequence with properties expected of a nuclear matrix attachment region (MAR). The putative MAR co-localized in the fragile domain with genes important to the hemopoietic system (leukocyte tyrosine kinase, zinc finger protein 106, erythrocyte protein band 4.2, and beta(2)-microglobulin (beta2m)); the beta2m subdomain was a particular focus of breakage. On the basis of these and other data, we suggest that AML-associated chromosome 2 fragility in the mouse is a consequence of domain-specific fragility in genomic domains containing numerous genes critical to the hemopoietic system. Recorded with the permission of the controller of Her Majesty's Stationery Office. Published by Wiley-Liss, Inc.
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MESH Headings
- Acute Disease
- Animals
- Base Sequence
- Chromosomes, Artificial, Bacterial
- Chromosomes, Artificial, Yeast
- Cloning, Molecular
- DNA, Neoplasm
- Leukemia, Myeloid/etiology
- Leukemia, Myeloid/genetics
- Mice
- Molecular Sequence Data
- Neoplasms, Radiation-Induced/genetics
- Repetitive Sequences, Nucleic Acid
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Affiliation(s)
- Rosemary Finnon
- Radiation Effects Department, National Radiological Protection Board, Chilton, England
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17
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Abstract
The distribution of telomeric sequence (TTAGGG)n in the genomes of Chondrichthian species at different stages of evolution was investigated both by DNA genomic hybridization, and by fluorescence in-situ hybridization (FISH) of metaphase chromosomes. The sequence is highly conserved in all the species examined. FISH revealed a label uptake only by the telomeres in Raja asterias. However, in Torpedo ocellata, we revealed pericentromeric and interstitial sequence localization on some chromosome pairs in addition to the hybridization signal on telomeres. These findings confirm that the karyotype evolution of these fish began by Robertsonian fusion.
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Affiliation(s)
- L Rocco
- Dipartimento di Scienze della Vita, Second University of Naples, Via Vivaldi 43, 81100 Caserta, Italy.
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18
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Abstract
Two assumptions are commonly made in the estimation of genetic risk: (1) that the seven specific loci in the mouse constitute a suitable basis for extrapolation to genetic disease in humans, and (2) that mutations are induced by radiation damage (energy-loss events leading to double-stranded damage) occurring within the gene and are induced linearly with dose, at least at low doses. Recent evidence on the mutability of repeat sequences is reviewed that suggests that neither of these assumptions is as well founded as we like to think. Repeat sequences are common in the human genome, and alterations in them may have health consequences. Many of them are unstable, both spontaneously and after irradiation. The fact that changes in DNA repeat sequences can clearly arise as a result of radiation damage outside the sequence concerned and the likely involvement of some sort of signal transduction process mean that the nature of the radiation dose response cannot be assumed. While the time has not come to abandon the current paradigms, it would seem sensible to invest more effort in exploring the induction of changes in repeat sequences after irradiation and the consequences of such changes for health.
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Affiliation(s)
- B A Bridges
- MRC Cell Mutation Unit, University of Sussex, Brighton, BN1 9RR, England, UK.
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19
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Bolzán AD, Páez GL, Bianchi MS. FISH analysis of telomeric repeat sequences and their involvement in chromosomal aberrations induced by radiomimetic compounds in hamster cells. Mutat Res 2001; 479:187-96. [PMID: 11470491 DOI: 10.1016/s0027-5107(01)00162-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The behaviour of telomeric repeat sequences in Chinese hamster CHO and CHE cell lines treated with the radiomimetic drugs bleomycin (BLM) and streptonigrin (STN) and the effect of these drugs on telomerase activity was investigated. Fluorescence in situ hybridisation revealed that 18% of the scored aberrations induced by BLM and 14% of those induced by STN in CHO cells exhibited telomeric repeat signals. In CHE cells, 29% of the total aberrations induced by BLM and 45% of those induced by STN involved telomeric repeat sequences. Acentric fragments labelled along their entire length and translocations of telomeric repeat sequences were also found in both cell lines. These results suggest that telomeric repeat sequences are preferentially involved in chromosome breakage, fragility and recombination induced by radiomimetic agents. In addition, some of the damaged CHE cells exhibited one or more chromosomes with additional zones of hybridisation, indicating the possible amplification of (TTAGGG)(n) repeats by telomerase. However, the fact that none of the radiomimetic compounds tested produced any effect on telomerase activity suggests that this enzyme is not related to the assumed amplification events induced by BLM and STN in CHE cells.
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Affiliation(s)
- A D Bolzán
- Laboratorio de Citogenética y Mutagénesis, Instituto Multidisciplinario de Biología Celular (IMBICE), C.C. 403, 1900, La Plata, Argentina.
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20
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Kasai F, Takahashi E, Koyama K, Terao K, Suto Y, Tokunaga K, Nakamura Y, Hirai M. Comparative FISH mapping of the ancestral fusion point of human chromosome 2. Chromosome Res 2001; 8:727-35. [PMID: 11196135 DOI: 10.1023/a:1026745505264] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
It is known that human chromosome 2 originated from the fusion of two ancestral primate chromosomes. This has been confirmed by chromosome banding and fluorescence in-situ hybridization (FISH) with human chromosome-2-specific DNA libraries. In this study, the order of 38 cosmid clones derived from the human chromosome region 2q12-q14 was exactly determined by high-resolution FISH in human chromosome 2 and its homologous chromosomes in chimpanzees (Pan trogrodydes, 2n=48) and cynomolgus monkeys (Macacafascicularis, 2n = 42). This region includes the telomere-to-telomere fusion point of two ancestral ape-type chromosomes. As a result of comparative mapping, human chromosome region 2q12-q14 was found to correspond to the short arms of chimpanzee chromosomes 12 and 13 and cynomolgus monkey chromosomes 9 and 15. It is noted that no difference was detected in the relative order of the cosmid clones between human and chimpanzee chromosomes. This suggests that two ancestral ape-type chromosomes fused tandemly at telomeres to form human chromosome 2, and the genomic organization of this region is thought to be considerably conserved. In the cynomolgus monkey, however, the order of clones in each homologue was inverted. In addition to cosmid mapping, two chromosome-2-specific yeast artificial chromosome (YAC) clones containing the fusion point were identified by FISH.
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Affiliation(s)
- F Kasai
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, Japan
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21
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Mondello C, Pirzio L, Azzalin CM, Giulotto E. Instability of interstitial telomeric sequences in the human genome. Genomics 2000; 68:111-7. [PMID: 10964508 DOI: 10.1006/geno.2000.6280] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The length variability of four human interstitial telomeric sequences (ITs) is described. Three of the ITs contain short telomeric stretches ranging between 53 and 84 bp and are localized in 21q22, 2q31, and 7q36; the fourth IT derives from the subtelomeric domain of chromosome 6p and contains a tract of a few hundred basepairs of exact and degenerate repeats. Using primers flanking the repeats, we amplified the genomic DNA from unrelated individuals and from family members, and we found that all the loci are polymorphic. At the 21q22 IT locus, two equally frequent alleles were found, while the number of alleles at the 2q31, 7q36, and 6pter IT loci was 8, 6, and 4, respectively. Sequence analysis revealed that in the three loci containing short ITs the alleles differ from one another for multiples of the hexanucleotide; it is likely that the mechanism leading to the polymorphism is DNA polymerase slippage. These loci were also unstable in gastric tumor cells characterized by microsatellite instability. At the 6pter IT locus, the four alleles range in length from about 500 to about 700 bp; this variability is probably due to unequal exchange or gene conversion. Our data indicate that stretches of exact internal telomeric repeats can be highly unstable, like microsatellites with shorter units, and that they can be useful polymorphic markers for linkage analysis, for forensic applications, and for the detection of genetic instability in tumors.
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MESH Headings
- Alleles
- Base Sequence
- Chromosomes, Human, Pair 2/genetics
- Chromosomes, Human, Pair 21/genetics
- Chromosomes, Human, Pair 7/genetics
- DNA/genetics
- Female
- Gene Frequency
- Genome, Human
- Genotype
- Humans
- Male
- Molecular Sequence Data
- Polymorphism, Restriction Fragment Length
- Repetitive Sequences, Nucleic Acid/genetics
- Sequence Homology, Nucleic Acid
- Stomach Neoplasms/genetics
- Telomere/genetics
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Affiliation(s)
- C Mondello
- Istituto di Genetica Biochimica ed Evoluzionistica, CNR, Via Abbiategrasso 207, Pavia, 27100, Italy.
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22
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Hofer KG, Lin X, Schneiderman MH. Paradoxical effects of iodine-125 decays in parent and daughter DNA: a new target model for radiation damage. Radiat Res 2000; 153:428-35. [PMID: 10761003 DOI: 10.1667/0033-7587(2000)153[0428:peoidi]2.0.co;2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Chinese hamster ovary cells were synchronized at the G(1)/S-phase boundary of the cell cycle and were pulse-labeled with (125)I-iododeoxyuridine 30 min after they entered the S phase. Cell samples were harvested and frozen for accumulation of (125)I decays during the first and second G(2) phase after labeling. Cell aliquots that had accumulated the desired number of decays were thawed and plated for evaluation micronucleus formation and cell death. Cells subjected to (125)I decays during the first G(2) phase after labeling exhibited single-hit kinetics of cell killing (n = 1, D(0) 41 decays/cell). In contrast, decays accumulated during the second G(2) phase killed cells with dual-hit kinetics (n = 1.9, D(0) 81 decays/cell). A similar divergence in the action of (125)I was noted for micronucleus formation. These findings indicate that the effects of (125)I varied depending on whether the decays occurred in daughter DNA (first G(2) phase) or parent DNA (second G(2) phase). Control studies with external X rays showed no such divergence of the action of radiation. To account for this paradox, a model is proposed that invokes higher-order chromatin structures as radiation targets. This model implies differential spatial arrangements for parent and daughter DNA in the genome, with DNA strands organized such that a single (125)I decay originating in daughter DNA damages two targets during the first G(2) phase, but identical decays occurring during the second G(2) phase damage only one of the targets.
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Affiliation(s)
- K G Hofer
- Institute of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306-3015, USA
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23
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Pazzaglia S, Pariset L, Rebessi S, Saran A, Coppola M, Covelli V, Moody J, Bouffler S, Cox R, Silver A. Somatic cell hybrids for high-density mapping of chromosome 2 breakpoints in radiation-induced myeloid leukemia cell lines from inbred mice. Mol Carcinog 2000. [DOI: 10.1002/(sici)1098-2744(200003)27:3<219::aid-mc9>3.0.co;2-s] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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24
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Cox R. The role of animal models in the development of knowledge of radiation carcinogenesis and their potential contribution to judgements of risk at low doses. COMPTES RENDUS DE L'ACADEMIE DES SCIENCES. SERIE III, SCIENCES DE LA VIE 1999; 322:135-8. [PMID: 10196664 DOI: 10.1016/s0764-4469(99)80035-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- R Cox
- National Radiological Protection Board, Chilton, Didcot, Oxon, UK
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25
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Abstract
The genomes of higher eukaryotes are not homogeneous in terms of structure or function. Many examples of chromosomal regions particularly prone to involvement in aberrations have been reported. The molecular structures of some of these regions have now been determined, most notably the folate-sensitive fragile sites and FRA16B-a distamycin A-sensitive fragile site. In addition, a number of cytological studies suggest that telomeric sequences can in some circumstances be involved in chromosomal aberrations more frequently than expected. Here, the roles of telomeric DNA sequences, both terminal and interstitial, and telomerase in chromosomal aberration formation are reviewed.
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Affiliation(s)
- S D Bouffler
- Radiation Effects Department, National Radiological Protection Board, Chilton, Didcot, Oxon, OX11 ORQ, UK
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26
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Abstract
The salient points of three currently debated theories for chromosomal aberration origins (the Classic Breakage-and-Reunion theory, the Exchange theory, and the Molecular theory) are outlined, and some comments are made on each in the light of recent research.
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Affiliation(s)
- J R Savage
- MRC Radiation and Genome Stability Unit, Harwell, Didcot, OX11 0RD, UK
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27
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Bouffler SD, Meijne EI, Morris DJ, Papworth D. Chromosome 2 hypersensitivity and clonal development in murine radiation acute myeloid leukaemia. Int J Radiat Biol 1997; 72:181-9. [PMID: 9269311 DOI: 10.1080/095530097143400] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Acute myeloid leukaemias induced by ionizing radiation in mouse are characterized by chromosome (chr) 2 aberrations. While it is known that chr 2 aberrations form early and in abundance post-irradiation, unequivocal evidence for hypersensitivity of chr 2 in the first post-irradiation mitoses is lacking. Here it is established that chromosomal aberrations detected in bone marrow cells by chromosome painting are induced in all mice at an approximately 2-fold greater frequency in chr 2 by comparison with chrs 1 and 3 at 24 and 48 h following in vivo whole-body X-irradiation. Long-term follow up studies (to 15 months post-irradiation) indicated that chromosomal hypersensitivity is accounted for largely by the existence of hot-spots for aberration formation on sensitive chromosomes. Analysis of clonal developments suggested that chr 2 aberrant clones are selected for entry into the proliferating bone marrow cell compartment in preference to cells with other aberrations and that these clones in general have a higher proliferative potential. However, neither the induction of chr 2 aberrations nor the presence of a chr 2 aberrant clone specifically predict the development of AML in an individual irradiated mouse. Nonetheless these events or sub-groups of these events are necessary for AML development.
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Affiliation(s)
- S D Bouffler
- Biomedical Effects Department, National Radiological Protection Board, Chilton, Didcot, UK
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28
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Boldog F, Gemmill RM, West J, Robinson M, Robinson L, Li E, Roche J, Todd S, Waggoner B, Lundstrom R, Jacobson J, Mullokandov MR, Klinger H, Drabkin HA. Chromosome 3p14 homozygous deletions and sequence analysis of FRA3B. Hum Mol Genet 1997; 6:193-203. [PMID: 9063739 DOI: 10.1093/hmg/6.2.193] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Loss of heterozygosity (LOH) involving 3p occurs in many carcinomas but is complicated by the identification of four distinct homozygous deletion regions. One putative target, 3p14.2, contains the common fragile site, FRA3B, a hereditary renal carcinoma-associated 3;8 translocation and the candidate tumor suppressor gene, FHIT. Using a approximately 300 kb comsid/lambda contig, we identified homozygous deletions in cervix, breast, lung and colorectal carcinoma cell lines. The smallest deletion (CC19) was shown not to involve FHIT coding exons and no DNA sequence alterations were present in the transcript. We also detected discontinuous deletions as well as deletions in non-tumor DNAs, suggesting that FHIT is not a selective target. Further, we demonstrate that some reported FHIT aberrations represent normal splicing variation. DNA sequence analysis of 110 kb demonstrated that the region is high in A-T content, LINEs and MER repeats, whereas Alu elements are reduced. We note an intriguing similarity in repeat sequence composition between FRA3B and a 152 kb segment from the Fragile-X region. We also identified similarity between a FRA3B segment and a small polydispersed circular DNA. In contrast to the selective loss of a tumor suppressor gene, we propose an alternative hypothesis, that some putative targets including FRA3B may undergo loss as a consequence of genomic instability. This instability is not due to DNA mismatch repair deficiency, but may correlate in part with p53 inactivation.
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Affiliation(s)
- F Boldog
- Division of Medical Oncology, University of Colorado Health Sciences Center, Denver 80262, USA
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29
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Rithidech KN, Dunn JJ, Gordon CR, Cronkite EP, Bond VP. Evidence for an uncommon microsatellite instability on mouse chromosomes 2 and 4 and its possible role in radiation leukemogenesis. Blood Cells Mol Dis 1997; 23:99-109. [PMID: 9215755 DOI: 10.1006/bcmd.1997.0126] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Although microsatellite instability (MSI), usually detected by DNA length polymorphisms, has been implicated in the induction of solid tumors in both humans and animals, its role in leukemogenesis is unclear. The goal of this study was to investigate whether there is an association between MSI and radiation leukemogenesis in CBA/Ca mice. Microsatellite lengths at 55 loci, mapped to eight different mouse chromosomes, were examined in two groups of DNA samples: 1) 10 normal DNA samples collected from the bone marrow cells of control male CBA/Ca mice, and 2) 17 DNA samples isolated from the spleens of mice that developed myeloid leukemia (ML) after exposure to neutrons, or X rays, or gamma rays. Microsatellite markers were amplified using the non-radioisotopic multiplex-touchdown PCR protocols developed in our laboratory, and the sizes of amplicons were examined on 6% non-denaturing polyacrylamide gels. Although no correlation between microsatellite length polymorphisms and radiation leukemogenesis was observed at the 55 CBA/Ca mouse loci tested in this study, an uncommon MSI, manifested as the absence of DNA bands after PCR amplification at 2 loci (D2MIT140 and D4MIT104), was observed in both control and ML samples. However, the frequency of ML samples showing this type of MSI is statistically significant (p<0.05). Although there is no direct evidence that this type of MSI predisposes mice to the development of leukemia, the results suggests that genes flanking the D2MIT140 and D4MIT104 are susceptible to spontaneous mutation and perhaps to damage caused by ionizing radiation.
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Affiliation(s)
- K N Rithidech
- Medical Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
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30
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Bouffler SD, Morgan WF, Pandita TK, Slijepcevic P. The involvement of telomeric sequences in chromosomal aberrations. Mutat Res 1996; 366:129-35. [PMID: 9001579 DOI: 10.1016/s0165-1110(96)90033-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Three functional elements are required for the stable transmission of eukaryotic chromosomes: replication origins, centromeres and telomeres. In the yeast Saccharomyces cerivisiae the DNA sequences defining each of these elements are known. The simplest and most widely conserved of these sequences is that of the telomere. As the name implies, the telomere is the end of a linear eukaryotic chromosome. Two of the main functions of the telomere are to prevent DNA loss as a consequence of replication and to prevent interactions with other chromosomal ends. Thus, telomeres play a major role in maintaining chromosome stability and consequently they have been considered as likely to be involved in some aspects of chromosomal aberration formation. The involvement of telomeric DNA sequences in stabilizing normal and broken chromosome ends, in "hot spots' for aberration formation and in delayed chromosomal instability will be reviewed here drawing on material presented at the Workshop and the published literature.
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Affiliation(s)
- S D Bouffler
- Biomedical Effects Department, National Radiological Protection Board, Didcot, Oxon, UK
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31
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Abstract
Spatial factors conditioning the formation of radiation-induced chromosome exchange aberrations are reviewed, and concepts such as 'rejoining distance' and 'site' are re-examined in the light of the unexpectedly high frequencies of multi-break ('Complex') exchanges being revealed by FISH painting. Given the anticipated densities of dsb within a nucleus, and assuming random 3-D break distribution, nearest-neighbour analysis indicates that the most likely break interaction distance is a well defined shell, several hundred nm from each break. The sharpness with which this shell is defined increases with break density, and therefore with dose. It is argued that random movement and chance meeting over such distances will not account for the Complex frequencies observed, and that other factors, or modes of formation, must be invoked.
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Affiliation(s)
- J R Savage
- MRC Radiobology Unit, Chilton, Didcot, UK
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32
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Dominguez I, Boei JJ, Balajee AS, Natarajan AT. Analysis of radiation-induced chromosome aberrations in Chinese hamster cells by FISH using chromosome-specific DNA libraries. Int J Radiat Biol 1996; 70:199-208. [PMID: 8794849 DOI: 10.1080/095530096145193] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The frequencies of chromosome aberrations induced by different doses of X-rays were determined in both splenocytes and primary lung fibroblasts of Chinese hamster by bi-colour FISH using a combination of four chromosome-specific DNA libraries. The results indicate that the X-rays induced more translocations than dicentrics in Chinese hamster cells, in which the karyotype is comprised of both metacentric and acrocentric chromosomes. These results are similar to those reported in human lymphocytes, in which the karyotype contains many metacentric chromosomes. On the contrary, in mouse, which is characterized by acrocentric chromosomes only, the frequencies of translocations and dicentrics are induced in nearly equal proportions by X-rays. The ratio of translocations to dicentrics obtained in Chinese hamster cells was approximately 1.4-1.5, which supports the importance of the karyotypic features of a species in the relative induction of translocations to dicentrics. An analysis was also made on the yield of translocations and dicentrics involving individual chromosomes and the results indicate a non-random involvement of these chromosomes in the formation of aberrations.
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Affiliation(s)
- I Dominguez
- Department of Radiation Genetics and Chemical Mutagenesis, Leiden University, The Netherlands
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33
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Meijne EI, Silver AR, Bouffler SD, Morris DJ, van Kampen EW, Spanjer S, Huiskamp R, Cox R. Role of telomeric sequences in murine radiation-induced myeloid leukaemia. Genes Chromosomes Cancer 1996; 16:230-7. [PMID: 8875236 DOI: 10.1002/(sici)1098-2264(199608)16:4<230::aid-gcc2>3.0.co;2-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
A previous study indicated that a highly inbred CBA/H mouse colony contained four genotypic variants for telomere-like repeat (TLR) sequence arrays and that one variant subpopulation that constituted 20% of the colony contributed the vast majority (> 90%) of radiation-induced acute myeloid leukaemias (AMLs). Through screening of a satellite CBA/H colony and rescreening of the original colony, we show that, whereas germline telomere sequence polymorphism is frequent in CBA/H mice, there is no genetic link between a specific TLR locus variant and susceptibility to AML. Studies on telomere-hybridising fragments between 200 bp and 150 kb revealed that the germline telomere mutation frequency was highest for restriction fragments > 50 kb. The hypervariability of these high-molecular-weight fragments resulted in each CBA/H mouse from the highly inbred colony having a different genotype. Although it was not possible to ascribe a specific somatic telomere mutation to AML development, telomere rearrangements were common in induced AMLs. Some terminal telomere-hybridising restriction fragments were shortened in AML samples in comparison with normal tissue, but, insofar as the reduction in size was relatively small, it seems unlikely that telomere erosion is a major contributor to the molecular pathology of murine radiation-induced AML.
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Affiliation(s)
- E I Meijne
- Netherlands Energy Research Foundation (ECN), Petten, The Netherlands
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34
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Clark DJ, Meijne EI, Bouffler SD, Huiskamp R, Skidmore CJ, Cox R, Silver AR. Microsatellite analysis of recurrent chromosome 2 deletions in acute myeloid leukaemia induced by radiation in F1 hybrid mice. Genes Chromosomes Cancer 1996; 16:238-46. [PMID: 8875237 DOI: 10.1002/(sici)1098-2264(199608)16:4<238::aid-gcc3>3.0.co;2-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Deletions and/or rearrangements involving one copy of chromosome 2 are consistent and early events in the development of murine acute myeloid leukaemia (AML) by radiation. More than 90% of AMLs induced in the CBA strain of mice express such cytogenetic alterations, with chromosome 2 breakpoints clustering in the C and F regions of the chromosome. In inbred mouse strains, the molecular resolution of these breakpoints is problematic. However, by using x-ray-induced AMLs in FI progeny of genetically divergent CBA/H x C57BI, it has been possible to show region-specific loss of heterozygosity (LOH) in genetically linked sets of chromosome 2 microsatellite alleles from one of the two parental chromosomes. In the majority of cases, an acceptable concordance was shown for AML chromosome 2 deletion, as defined by microsatellites and as revealed by G-band cytogenetics. A degree of breakpoint clustering was found, but the identification of a number of deletion types, based on the position of proximal and distal breakpoints as defined by microsatellite analysis, strongly supports a leukaemogenic mechanism involving gene deletion. No bias towards loss of CBA or C57BI alleles was observed, and the gender of AML-presenting animals did not appear to influence the parental origin of the deletions. A molecular map of chromosome 2 breakpoints has now been established in FI AMLs as a first step towards the molecular cloning of breakpoint sequences.
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Affiliation(s)
- D J Clark
- National Radiological Protection Board, Didcot, Oxon, United Kingdom
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35
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Slijepcevic P, Xiao Y, Dominguez I, Natarajan AT. Spontaneous and radiation-induced chromosomal breakage at interstitial telomeric sites. Chromosoma 1996; 104:596-604. [PMID: 8662252 DOI: 10.1007/bf00352299] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The Chinese hamster genome contains a total of 18 cytologically detectable arrays of interstitial telomeric sequences. A combination of G-banding and two-colour fluorescence in situ hybridization revealed that 25 out of 27 (93%) breakpoints of spontaneously occurring terminal deletions in four immortalized Chinese hamster cell lines were located in chromosomal regions containing interstitial telomeric sequences. Each of the four immortalized Chinese hamster cell lines expressed telomerase. Radiation experiments revealed the sensitivity of interstitial telomeric sequences to radiation-induced chromosomal breakage in all telomerase-positive cell lines. However, radiation-induced chromosomal breakage at interstitial telomeric sites in non-transformed, primary Chinese hamster cells was almost non-existent. Telomerase activity in primary Chinese hamster cells was not detected. These results indirectly suggest that interstitial telomeric sites represent a favourable substrate for chromosomal healing.
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Affiliation(s)
- P Slijepcevic
- Department of Radiation Genetics and Chemical Mutagenesis, University of Leiden, Wassenaarseweg 72, NL-2300 RA Leiden, The Netherlands
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36
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Yen CH, Pazik J, Elliott RW. A polymorphic interstitial telomere array near the center of mouse chromosome 8. Mamm Genome 1996; 7:218-21. [PMID: 8833245 DOI: 10.1007/s003359900059] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- C H Yen
- Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, Buffalo, New York 14263, USA
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37
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Role of induced genetic instability in the mutagenic effects of chemicals and radiation. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0165-1218(96)90017-8] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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38
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Fernández JL, Gosálvez J, Goyanes V. High frequency of mutagen-induced chromatid exchanges at interstitial telomere-like DNA sequence blocks of Chinese hamster cells. Chromosome Res 1995; 3:281-4. [PMID: 7551541 DOI: 10.1007/bf00713065] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Interstitial telomere-like DNA sequence arrays of Chinese hamster Don cells were delineated by fluorescence in situ hybridization in quadriradial and triradial chromosome configurations induced by X-rays, mitomycin C and teniposide (VM-26). Around 40% of the scored exchanges involved a telomeric-like block of sequences at a rearrangement site. This frequency was independent of the DNA-damaging agent, and the result suggests a general recombinogenic capacity of interstitial telomere-like DNA sequence repeats that, at least in the case of the agents employed, seems not to be related to the initial mechanism of DNA damage.
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39
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Griffin CS, Marsden SJ, Stevens DL, Simpson P, Savage JR. Frequencies of complex chromosome exchange aberrations induced by 238Pu alpha-particles and detected by fluorescence in situ hybridization using single chromosome-specific probes. Int J Radiat Biol 1995; 67:431-9. [PMID: 7738406 DOI: 10.1080/09553009514550491] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We undertook an analysis of chromosome-type exchange aberrations induced by alpha-particles using fluorescence in situ hybridization (FISH) with whole chromosome-specific probes for human chromosomes 1 or 4, together with a pan-centromeric probe. Contact-inhibited primary human fibroblasts (in G1) were irradiated with 0.41-1.00 Gy 238Pu alpha-particles and aberrations were analysed at the next mitosis following a single chromosome paint. Exchange and aberration painting patterns were classified according to Savage and Simpson (1994a). Of exchange aberrations, 38-47% were found to be complex derived, i.e. resulting from three or more breaks in two or more chromosomes, and the variation with dose was minimal. The class of complex aberrations most frequently observed were insertions, derived from a minimum of three breaks in two chromosomes. There was also an elevated frequency of rings. The high level of complex aberrations observed after alpha-particle irradiation indicates that, when chromosome domains are traversed by high linear energy transfer alpha-particle tracks, there is an enhanced probability of production of multiple localized double-strand breaks leading to more complicated interactions.
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40
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Yen CH, Matsuda Y, Chapman VM, Elliott RW. A genomic clone containing a telomere array maps near the centromere of mouse chromosome 6. Mamm Genome 1995; 6:96-102. [PMID: 7767012 DOI: 10.1007/bf00303251] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A lambda clone of mouse DNA containing a short array of telomere hexamers has been localized by FISH to a region close to the centromere of Chromosome (Chr) 6. Amplification of DNA with primers flanking an SSR showed that most inbred strains carry one of two alleles, although five other alleles were found among the inbred strains and 11 other alleles were found in wild-derived mice. Analysis of the DNA from four Robertsonian translocations suggests that the amplified sequence is still present in these chromosomes. The finding of two fragments associated with the Sig mutant suggests that the clone lies within a congenic region created when the mutant, obtained in a (C3H x 101)F1, was backcrossed to C57BL/6J. This region might include all or part of the centromere. Comparison of the segregation of the amplification product with the segregation of centromeric heterochromatin in an interspecies backcross, (C57BL/6 x M. spretus)F1 x M. spretus, (BSS) shows 1/72 recombinants with the centromeric heterochromatin, while 1/62 recombinants occurred in a BSB backcross. Analysis of other loci at the proximal end of Chr 6 gives the combined map Hc6-0.73-D6Mit86-0.73-D6Rp2-2.2-D6Mitl-2.2-Wn t2-3.0-Cpa. Data from a third cross show that Cola2 lies between D6Mit82 and D6Rp2. The portion of the telomere array, Tel-rs3, that has been sequenced contains only 13/31 repeats of the consensus sequence. A variety of sequence changes from the consensus hexamer suggests that this array has been removed for a long time from evolutionary pressures to retain the TTAGGG sequence.
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Affiliation(s)
- C H Yen
- Department of Molecular and Cellular Biology, Roswell Park Cancer Institute, New York State Department of Health, Buffalo 14263, USA
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41
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Natarajan AT, Balajee AS, Boei JJ, Chatterjee S, Darroudi F, Grigorova M, Noditi M, Oh HJ, Slijepcevic P, Vermeulen S. Recent developments in the assessment of chromosomal damage. Int J Radiat Biol 1994; 66:615-23. [PMID: 7983455 DOI: 10.1080/09553009414551711] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Ionizing radiation and restriction endonucleases are very efficient in inducing chromosomal aberrations (CAs). These aberrations are mainly consequences of misrepair of DNA double-strand breaks (DSBs). The fast repairing component of DSBs induced by ionizing radiation seems to be responsible for exchange aberration. Use of premature chromosome condensation technique in combination with DNA repair inhibitors such as ara A has given valuable information on the assessment of the frequencies of initial chromosome breaks and the kinetics of their repair following low LET radiation. The recently developed 'chromosome painting' technique using chromosome-specific libraries has also increased considerably the resolution of identifying and scoring of CAs. After low LET radiation, stable chromosome exchanges (translocations) are induced more frequently than unstable chromosome exchanges (dicentrics). Fluorescence in situ hybridization employing telomeric probe has made it possible to score efficiently exchange aberrations involving the acrocentric chromosomes of mouse. Chinese hamster cells have several intercalary telomeric sequences present in most of the chromosomes. These telomeric blocks have been found to be associated with chromosomal aberrations induced by restriction endonucleases and short wave UV and evidence has been obtained for apparent amplification of telomeric sequences at the break points.
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Affiliation(s)
- A T Natarajan
- Department of Radiation Genetics and Chemical Mutagenesis, State University of Leiden, The Netherlands
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42
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Abstract
The integration of transfected plasmid DNA at the telomere of chromosome 13 in an immortalized simian virus 40-transformed human cell line provided the first opportunity to study polymorphism in the number of telomeric repeat sequences on the end of a single chromosome. Three subclones of this cell line were selected for analysis: one with a long telomere on chromosome 13, one with a short telomere, and one with such extreme polymorphism that no distinct band was discernible. Further subcloning demonstrated that telomere polymorphism resulted from both gradual changes and rapid changes that sometimes involved many kilobases. The gradual changes were due to the shortening of telomeres at a rate similar to that reported for telomeres of somatic cells without telomerase, eventually resulting in the loss of nearly all of the telomere. However, telomeres were not generally lost completely, as shown by the absence of polymorphism in the subtelomeric plasmid sequences. Instead, telomeres that were less than a few hundred base pairs in length showed a rapid, highly heterogeneous increase in size. Rapid changes in telomere length also occurred on longer telomeres. The frequency of this type of change in telomere length varied among the subclones and correlated with chromosome fusion. Therefore, the rapid changes in telomere length appeared occasionally to result in the complete loss of telomeric repeat sequences. Rapid changes in telomere length have been associated with telomere loss and chromosome instability in yeast and could be responsible for the high rate of chromosome fusion observed in many human tumor cell lines.
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Affiliation(s)
- J P Murnane
- Laboratory of Radiobiology and Environmental Health, University of California, San Francisco 94143-0750
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43
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Kunz BA, Kohalmi SE, Kunkel TA, Mathews CK, McIntosh EM, Reidy JA. International Commission for Protection Against Environmental Mutagens and Carcinogens. Deoxyribonucleoside triphosphate levels: a critical factor in the maintenance of genetic stability. Mutat Res 1994; 318:1-64. [PMID: 7519315 DOI: 10.1016/0165-1110(94)90006-x] [Citation(s) in RCA: 185] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
DNA precursor pool imbalances can elicit a variety of genetic effects and modulate the genotoxicity of certain DNA-damaging agents. These and other observations indicate that the control of DNA precursor concentrations is essential for the maintenance of genetic stability, and suggest that factors which offset this control may contribute to environmental mutagenesis and carcinogenesis. In this article, we review the biochemical and genetic mechanisms responsible for regulating the production and relative amounts of intracellular DNA precursors, describe the many outcomes of perturbations in DNA precursor levels, and discuss implications of such imbalances for sensitivity to DNA-damaging agents, population monitoring, and human diseases.
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Affiliation(s)
- B A Kunz
- Microbiology Department, University of Manitoba, Winnipeg, Canada
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44
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Abstract
Chromosomes not only carry transcribed genes and their regulatory DNA sequences, but also contain regions that are required for the stability and maintenance of the chromosome as a unit. These include centromeres, telomeres and origins of replication. It is clear for replication origins and centromeres that the positions of these chromosomal organelles are determined by sites of the appropriate DNA sequences, but also that functional performance requires one or more contributing proteins. Telomeres are also structurally complex, with one or more DNA components, including simple telomeric repeats and more complex telomere-associated sequences, as well as one or more specific proteins that recognize these sequences. Accumulating evidence suggests that the simple telomeric repeats are required in most, but not all species, although they are not sufficient to determine the chromosomal position of a telomere.
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Affiliation(s)
- H Biessmann
- Developmental Biology Center, University of California, Irvine 92717
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45
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Abstract
Telomeres are essential for stable chromosome maintenance. The simple G-rich sequence motif d(TTAGGG)n is all that is required in cis for telomere function in mammalian cells, as in other eukaryotes. Using this fact, telomeres have been used to specifically fragment mammalian chromosomes to dissect their structure and function. Telomere length maintenance is altered in cancer cells. Trans-acting factors, such as telomerase and telomere-binding proteins, may determine telomere function in both normal and cancer cells. Current experiments are aimed at understanding the role of telomerase and telomere-binding proteins in cellular senescence and immortalization.
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46
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Abstract
Resolving the molecular mechanisms of radiation oncogenesis represents an important but daunting challenge in radiation research. This brief review outlines the principal oncogenic mechanisms that need to be considered in the context of radiation effects on the genome, how these might relate to specific gene and chromosomal changes relevant to neoplasia and the possible implications of such knowledge for the modelling of cancer risk. The long-term application of this mechanistic knowledge to the determination of tumour causality and for the assessment of individual cancer risk is also briefly discussed.
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Affiliation(s)
- R Cox
- Biomedical Effects Department, National Radiological Protection Board, Chilton, Didcot, UK
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47
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48
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Bouffler S, Silver A, Cox R. The role of DNA repeats and associated secondary structures in genomic instability and neoplasia. Bioessays 1993; 15:409-12. [PMID: 8357343 DOI: 10.1002/bies.950150607] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Tumour-associated genetic changes frequently involve DNA translocation or deletion. Many of these events will have arisen from initial genomic damage, induced by either the activity of endogenous metabolic processes or from exposure to environmental genotoxic agents. Although initial genomic damage will have been widely distributed, tumorigenic events are confined to certain DNA target sites. Furthermore, within these target sites there appear to be regions of preferential DNA rearrangement, and examination of these sites implies that the location and extent of such rearrangement may be influenced by DNA primary and secondary structure rather than simply by the point of damage. We selectively review evidence relating to DNA structures that may predispose certain regions of the genome to damage-induced rearrangement, and discuss the possible role of interstitial, inverted telomere-like sequence arrays in promoting chromosomal events of a type known to be associated with some human and animal tumours.
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Affiliation(s)
- S Bouffler
- Biomedical Effects Department, National Radiological Protection Board, Didcot, Oxon, UK
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49
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Goodhead DT, Thacker J, Cox R. Weiss Lecture. Effects of radiations of different qualities on cells: molecular mechanisms of damage and repair. Int J Radiat Biol 1993; 63:543-56. [PMID: 8099101 DOI: 10.1080/09553009314450721] [Citation(s) in RCA: 195] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Studies of ionizing radiations of different quality are discussed with particular emphasis on damage to DNA of mammalian cells. Three related themes are followed. Firstly, inactivation and mutation experiments with ultrasoft X-rays and slow heavy ions, coupled with theoretical analyses of the structures of the radiation tracks, have emphasized the biological importance of localized track features over nanometre dimensions. This led to the suggestion that the critical physical features of the tracks are the stochastic clusterings of ionizations, directly in or very near to DNA, resulting in clustered initial molecular damage including various combinations of breaks, base damages, cross-links, etc. in the DNA. The quantitative hypotheses imply that final cellular effects from high-LET radiations are dominated by their more severe, and therefore less repairable, clustered damage, and that these are qualitatively different from the dominant low-LET damage. Second, relative effectiveness of different types of radiation led to questions on the mechanisms of induction of chromosome exchanges. The high efficiency of ultrasoft X-rays, despite their very short track lengths, suggested that single sites of DNA damage may lead to exchanges by a molecular process involving interaction with undamaged DNA. Also it is shown that a single site-specific DNA break, introduced by restriction enzymes, sometimes leads to a large deletion when misrepaired by cell extracts. These deletions occur between short DNA repeats, and are therefore a form of 'illegitimate' recombination, but clearly do not involve the interaction of two damage sites. Third, it was shown that cells from patients with the radiosensitive disorder ataxia-telangiectasia (AT) lack a post-irradiation recovery process. The sensitivity of AT cells to high LET radiations was found to be reduced relative to that for normal cells, reinforcing the concept that high LET damage is less easy to repair. AT patients are prone to lymphoreticular cancers, and their cells show characteristic chromosomal rearrangements, which may be associated with misrepair at specific genomic sequences. Similarly, studies of radiation-induced leukaemia in the mouse have implicated rearrangement at specific interstitial chromosome sites, which are rich in telomere-like repeat sequences.
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Affiliation(s)
- D T Goodhead
- Medical Research Council Radiobiology Unit, Chilton, Didcot, UK
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50
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Ionizing Radiation Damage and Its Early Development in Chromosomes. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/b978-0-12-035417-7.50010-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
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