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Vaquero-Sedas MI, Vega-Palas MA. Epigenetic nature of Arabidopsis thaliana telomeres. PLANT PHYSIOLOGY 2023; 191:47-55. [PMID: 36218957 PMCID: PMC9806604 DOI: 10.1093/plphys/kiac471] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 09/22/2022] [Indexed: 05/15/2023]
Abstract
The epigenetic features of defined chromosomal domains condition their biochemical and functional properties. Therefore, there is considerable interest in studying the epigenetic marks present at relevant chromosomal loci. Telomeric regions, which include telomeres and subtelomeres, have been traditionally considered heterochromatic. However, whereas the heterochromatic nature of subtelomeres has been widely accepted, the epigenetic status of telomeres remains controversial. Here, we studied the epigenetic features of Arabidopsis (Arabidopsis thaliana) telomeres by analyzing multiple genome-wide ChIP-seq experiments. Our analyses revealed that Arabidopsis telomeres are not significantly enriched either in euchromatic marks like H3K4me2, H3K9ac, and H3K27me3 or in heterochromatic marks such as H3K27me1 and H3K9me2. Thus, telomeric regions in Arabidopsis have a bimodal chromatin organization with telomeres lacking significant levels of canonical euchromatic and heterochromatic marks followed by heterochromatic subtelomeres. Since heterochromatin is known to influence telomere function, the heterochromatic modifications present at Arabidopsis subtelomeres could play a relevant role in telomere biology.
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Affiliation(s)
- María I Vaquero-Sedas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, IBVF (CSIC-US), Seville E41092, Spain
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2
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Srinivas N, Rachakonda S, Kumar R. Telomeres and Telomere Length: A General Overview. Cancers (Basel) 2020; 12:E558. [PMID: 32121056 PMCID: PMC7139734 DOI: 10.3390/cancers12030558] [Citation(s) in RCA: 140] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/24/2020] [Accepted: 02/26/2020] [Indexed: 02/06/2023] Open
Abstract
Telomeres are highly conserved tandem nucleotide repeats that include proximal double-stranded and distal single-stranded regions that in complex with shelterin proteins afford protection at chromosomal ends to maintain genomic integrity. Due to the inherent limitations of DNA replication and telomerase suppression in most somatic cells, telomeres undergo age-dependent incremental attrition. Short or dysfunctional telomeres are recognized as DNA double-stranded breaks, triggering cells to undergo replicative senescence. Telomere shortening, therefore, acts as a counting mechanism that drives replicative senescence by limiting the mitotic potential of cells. Telomere length, a complex hereditary trait, is associated with aging and age-related diseases. Epidemiological data, in general, support an association with varying magnitudes between constitutive telomere length and several disorders, including cancers. Telomere attrition is also influenced by oxidative damage and replicative stress caused by genetic, epigenetic, and environmental factors. Several single nucleotide polymorphisms at different loci, identified through genome-wide association studies, influence inter-individual variation in telomere length. In addition to genetic factors, environmental factors also influence telomere length during growth and development. Telomeres hold potential as biomarkers that reflect the genetic predisposition together with the impact of environmental conditions and as targets for anti-cancer therapies.
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Affiliation(s)
| | | | - Rajiv Kumar
- Division of Functional Genome Analysis, German Cancer Research Center, Im Neunheimer Feld 580, 69120 Heidelberg, Germany; (N.S.); (S.R.)
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Achrem M, Szućko I, Kalinka A. The epigenetic regulation of centromeres and telomeres in plants and animals. COMPARATIVE CYTOGENETICS 2020; 14:265-311. [PMID: 32733650 PMCID: PMC7360632 DOI: 10.3897/compcytogen.v14i2.51895] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 05/18/2020] [Indexed: 05/10/2023]
Abstract
The centromere is a chromosomal region where the kinetochore is formed, which is the attachment point of spindle fibers. Thus, it is responsible for the correct chromosome segregation during cell division. Telomeres protect chromosome ends against enzymatic degradation and fusions, and localize chromosomes in the cell nucleus. For this reason, centromeres and telomeres are parts of each linear chromosome that are necessary for their proper functioning. More and more research results show that the identity and functions of these chromosomal regions are epigenetically determined. Telomeres and centromeres are both usually described as highly condensed heterochromatin regions. However, the epigenetic nature of centromeres and telomeres is unique, as epigenetic modifications characteristic of both eu- and heterochromatin have been found in these areas. This specificity allows for the proper functioning of both regions, thereby affecting chromosome homeostasis. This review focuses on demonstrating the role of epigenetic mechanisms in the functioning of centromeres and telomeres in plants and animals.
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Affiliation(s)
- Magdalena Achrem
- Institute of Biology, University of Szczecin, Szczecin, PolandUniversity of SzczecinSzczecinPoland
- Molecular Biology and Biotechnology Center, University of Szczecin, Szczecin, PolandUniversity of SzczecinSzczecinPoland
| | - Izabela Szućko
- Institute of Biology, University of Szczecin, Szczecin, PolandUniversity of SzczecinSzczecinPoland
- Molecular Biology and Biotechnology Center, University of Szczecin, Szczecin, PolandUniversity of SzczecinSzczecinPoland
| | - Anna Kalinka
- Institute of Biology, University of Szczecin, Szczecin, PolandUniversity of SzczecinSzczecinPoland
- Molecular Biology and Biotechnology Center, University of Szczecin, Szczecin, PolandUniversity of SzczecinSzczecinPoland
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Vaquero-Sedas MI, Vega-Palas MA. Assessing the Epigenetic Status of Human Telomeres. Cells 2019; 8:cells8091050. [PMID: 31500249 PMCID: PMC6770363 DOI: 10.3390/cells8091050] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 08/29/2019] [Accepted: 09/05/2019] [Indexed: 12/21/2022] Open
Abstract
The epigenetic modifications of human telomeres play a relevant role in telomere functions and cell proliferation. Therefore, their study is becoming an issue of major interest. These epigenetic modifications are usually analyzed by microscopy or by chromatin immunoprecipitation (ChIP). However, these analyses could be challenged by subtelomeres and/or interstitial telomeric sequences (ITSs). Whereas telomeres and subtelomeres cannot be differentiated by microscopy techniques, telomeres and ITSs might not be differentiated in ChIP analyses. In addition, ChIP analyses of telomeres should be properly controlled. Hence, studies focusing on the epigenetic features of human telomeres have to be carefully designed and interpreted. Here, we present a comprehensive discussion on how subtelomeres and ITSs might influence studies of human telomere epigenetics. We specially focus on the influence of ITSs and some experimental aspects of the ChIP technique on ChIP analyses. In addition, we propose a specific pipeline to accurately perform these studies. This pipeline is very simple and can be applied to a wide variety of cells, including cancer cells. Since the epigenetic status of telomeres could influence cancer cells proliferation, this pipeline might help design precise epigenetic treatments for specific cancer types.
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Affiliation(s)
- María I Vaquero-Sedas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, 41092 Seville, Spain.
| | - Miguel A Vega-Palas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, 41092 Seville, Spain.
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Cubiles MD, Barroso S, Vaquero-Sedas MI, Enguix A, Aguilera A, Vega-Palas MA. Epigenetic features of human telomeres. Nucleic Acids Res 2019; 46:2347-2355. [PMID: 29361030 PMCID: PMC5861411 DOI: 10.1093/nar/gky006] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Accepted: 01/09/2018] [Indexed: 01/02/2023] Open
Abstract
Although subtelomeric regions in humans are heterochromatic, the epigenetic nature of human telomeres remains controversial. This controversy might have been influenced by the confounding effect of subtelomeric regions and interstitial telomeric sequences (ITSs) on telomeric chromatin structure analyses. In addition, different human cell lines might carry diverse epigenetic marks at telomeres. We have developed a reliable procedure to study the chromatin structure of human telomeres independently of subtelomeres and ITSs. This procedure is based on the statistical analysis of multiple ChIP-seq experiments. We have found that human telomeres are not enriched in the heterochromatic H3K9me3 mark in most of the common laboratory cell lines, including embryonic stem cells. Instead, they are labeled with H4K20me1 and H3K27ac, which might be established by p300. These results together with previously published data argue that subtelomeric heterochromatin might control human telomere functions. Interestingly, U2OS cells that exhibit alternative lengthening of telomeres have heterochromatic levels of H3K9me3 in their telomeres.
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Affiliation(s)
- María D Cubiles
- Departamento de Estadística e Investigación Operativa, Facultad de Matemáticas, Universidad de Sevilla, 41012 Seville, Spain
| | - Sonia Barroso
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Avd. Américo Vespucio s/n, 41092 Seville, Spain
| | - María I Vaquero-Sedas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, IBVF (CSIC-US), Avd. Américo Vespucio n° 49, 41092 Seville, Spain
| | - Alicia Enguix
- Departamento de Estadística e Investigación Operativa, Facultad de Matemáticas, Universidad de Sevilla, 41012 Seville, Spain
| | - Andrés Aguilera
- Centro Andaluz de Biología Molecular y Medicina Regenerativa CABIMER, Universidad de Sevilla-CSIC-Universidad Pablo de Olavide, Avd. Américo Vespucio s/n, 41092 Seville, Spain
| | - Miguel A Vega-Palas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, IBVF (CSIC-US), Avd. Américo Vespucio n° 49, 41092 Seville, Spain
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Vega-Vaquero A, Bonora G, Morselli M, Vaquero-Sedas MI, Rubbi L, Pellegrini M, Vega-Palas MA. Novel features of telomere biology revealed by the absence of telomeric DNA methylation. Genome Res 2016; 26:1047-56. [PMID: 27405804 PMCID: PMC4971770 DOI: 10.1101/gr.202465.115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 06/20/2016] [Indexed: 12/21/2022]
Abstract
Cytosine methylation regulates the length and stability of telomeres, which can affect a wide variety of biological features, including cell differentiation, development, or illness. Although it is well established that subtelomeric regions are methylated, the presence of methylated cytosines at telomeres has remained controversial. Here, we have analyzed multiple bisulfite sequencing studies to address the methylation status of Arabidopsis thaliana telomeres. We found that the levels of estimated telomeric DNA methylation varied among studies. Interestingly, we estimated higher levels of telomeric DNA methylation in studies that produced C-rich telomeric strands with lower efficiency. However, these high methylation estimates arose due to experimental limitations of the bisulfite technique. We found a similar phenomenon for mitochondrial DNA: The levels of mitochondrial DNA methylation detected were higher in experiments with lower mitochondrial read production efficiencies. Based on experiments with high telomeric C-rich strand production efficiencies, we concluded that Arabidopsis telomeres are not methylated, which was confirmed by methylation-dependent restriction enzyme analyses. Thus, our studies indicate that telomeres are refractory to de novo DNA methylation by the RNA-directed DNA methylation machinery. This result, together with previously reported data, reveals that subtelomeric DNA methylation controls the homeostasis of telomere length.
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Affiliation(s)
- Alejandro Vega-Vaquero
- Technical Superior School of Informatics Engineering, University of Seville, 41080 Seville, Spain
| | - Giancarlo Bonora
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California 90095, USA
| | - Marco Morselli
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California 90095, USA
| | - María I Vaquero-Sedas
- Institute of Vegetal Biochemistry and Photosynthesis, CSIC-University of Seville, IBVF (CSIC-US), 41092 Seville, Spain
| | - Liudmilla Rubbi
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California 90095, USA
| | - Matteo Pellegrini
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California 90095, USA
| | - Miguel A Vega-Palas
- Institute of Vegetal Biochemistry and Photosynthesis, CSIC-University of Seville, IBVF (CSIC-US), 41092 Seville, Spain
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Zhou Y, Hartwig B, James GV, Schneeberger K, Turck F. Complementary Activities of TELOMERE REPEAT BINDING Proteins and Polycomb Group Complexes in Transcriptional Regulation of Target Genes. THE PLANT CELL 2016; 28:87-101. [PMID: 26721861 PMCID: PMC4746681 DOI: 10.1105/tpc.15.00787] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 11/11/2015] [Accepted: 12/25/2015] [Indexed: 05/19/2023]
Abstract
In multicellular organisms, Polycomb Repressive Complex 1 (PRC1) and PRC2 repress target genes through histone modification and chromatin compaction. Arabidopsis thaliana mutants strongly compromised in the pathway cannot develop differentiated organs. LIKE HETEROCHROMATIN PROTEIN1 (LHP1) is so far the only known plant PRC1 component that directly binds to H3K27me3, the histone modification set by PRC2, and also associates genome-wide with trimethylation of lysine 27 of histone H3 (H3K27me3). Surprisingly, lhp1 mutants show relatively mild phenotypic alterations. To explain this paradox, we screened for genetic enhancers of lhp1 mutants to identify novel components repressing target genes together with, or in parallel to, LHP1. Two enhancing mutations were mapped to TELOMERE REPEAT BINDING PROTEIN1 (TRB1) and its paralog TRB3. We show that TRB1 binds to thousands of genomic sites containing telobox or related cis-elements with a significant increase of sites and strength of binding in the lhp1 background. Furthermore, in combination with lhp1, but not alone, trb1 mutants show increased transcription of LHP1 targets, such as floral meristem identity genes, which are more likely to be bound by TRB1 in the lhp1 background. By contrast, expression of a subset of LHP1-independent TRB1 target genes, many involved in primary metabolism, is decreased in the absence of TRB1 alone. Thus, TRB1 is a bivalent transcriptional modulator that maintains downregulation of Polycomb Group (PcG) target genes in lhp1 mutants, while it sustains high expression of targets that are regulated independently of PcG.
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Affiliation(s)
- Yue Zhou
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
| | - Benjamin Hartwig
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
| | - Geo Velikkakam James
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
| | - Korbinian Schneeberger
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
| | - Franziska Turck
- Department Plant Developmental Biology, Max Planck Institute for Plant Breeding Research, 50829 Köln, Germany
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8
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Suárez P, Cardozo D, Baldo D, Pereyra MO, Faivovich J, Orrico VGD, Catroli GF, Grabiele M, Bernarde PS, Nagamachi CY, Haddad CFB, Pieczarka JC. Chromosome evolution in dendropsophini (Amphibia, Anura, Hylinae). Cytogenet Genome Res 2013; 141:295-308. [PMID: 24107475 DOI: 10.1159/000354997] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2013] [Indexed: 11/19/2022] Open
Abstract
Dendropsophini is the most species-rich tribe within Hylidae with 234 described species. Although cytogenetic information is sparse, chromosome numbers and morphology have been considered as an important character system for systematic inferences in this group. Using a diversity of standard and molecular techniques, we describe the previously unknown karyotypes of the genera Xenohyla, Scarthyla and Sphaenorhynchus and provide new information on Dendropsophus and Lysapsus. Our results reveal significant karyotype diversity among Dendropsophini, with diploid chromosome numbers ranging from 2n = 22 in S. goinorum, 2n = 24 in Lysapsus, Scinax, Xenohyla, and almost all species of Sphaenorhynchus and Pseudis, 2n = 26 in S. carneus, 2n = 28 in P. cardosoi, to 2n = 30 in all known Dendropsophus species. Although nucleolar organizer regions (NORs) and C-banding patterns show a high degree of variability, NOR positions in 2n = 22, 24 and 28 karyotypes and C-banding patterns in Lysapsus and Pseudis are informative cytological markers. Interstitial telomeric sequences reveal a diploid number reduction from 24 to 22 in Scarthyla by a chromosome fusion event. The diploid number of X. truncata corroborates the character state of 2n = 30 as a synapomorphy of Dendropsophus.
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Affiliation(s)
- P Suárez
- Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
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Vaquero-Sedas MI, Vega-Palas MA. Differential association of Arabidopsis telomeres and centromeres with histone H3 variants. Sci Rep 2013; 3:1202. [PMID: 23383372 PMCID: PMC3563029 DOI: 10.1038/srep01202] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 01/11/2013] [Indexed: 01/25/2023] Open
Abstract
Two different groups, using ChIP-seq data, have recently published the genome-wide distribution of histones H3.1 and H3.3 in Arabidopsis thaliana. In one report, Stroud and colleagues determined that, whereas H3.1 was enriched in repetitive pericentromeric and silent chromatin, H3.3 was enriched in transcriptionally active regions. This work was performed using seedlings, which contained dividing and non-dividing cells. In a second report, Wollmann and colleagues found similar results analyzing dividing or non-dividing tissue. None of these reports addressed the analysis of telomeres or centromeres. Our group has recently described an experimental approach that allows the study of the epigenetic status of some Arabidopsis repetitive sequences by analyzing ChIP-seq data. By using this approach and the data generated by Stroud, Wollmann and colleagues, we found that telomeres are enriched in H3.3 with regard to the centromeric 178 bp repeats, whereas the centromeric repeats are enriched in H3.1 with regard to telomeres.
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Affiliation(s)
- María I Vaquero-Sedas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, IBVF (CSIC-US), c/Américo Vespucio n° 49, 41092 Seville, Spain
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10
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Vaquero-Sedas MI, Vega-Palas MA. Human Long Telomeres and Epigenetic Marks. Cell 2013. [DOI: 10.4236/cellbio.2013.22009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Vaquero-Sedas MI, Luo C, Vega-Palas MA. Analysis of the epigenetic status of telomeres by using ChIP-seq data. Nucleic Acids Res 2012; 40:e163. [PMID: 22855559 PMCID: PMC3505975 DOI: 10.1093/nar/gks730] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 07/06/2012] [Indexed: 01/17/2023] Open
Abstract
The chromatin structure of eukaryotic telomeres plays an essential role in telomere functions. However, their study might be impaired by the presence of interstitial telomeric sequences (ITSs), which have a widespread distribution in different model systems. We have developed a simple approach to study the chromatin structure of Arabidopsis telomeres independently of ITSs by analyzing ChIP-seq data. This approach could be used to study the chromatin structure of telomeres in some other eukaryotes. The analysis of ChIP-seq experiments revealed that Arabidopsis telomeres have higher density of histone H3 than centromeres, which might reflects their short nucleosomal organization. These experiments also revealed that Arabidopsis telomeres have lower levels of heterochromatic marks than centromeres (H3K9(Me2) and H3K27(Me)), higher levels of some euchromatic marks (H3K4(Me2) and H3K9Ac) and similar or lower levels of other euchromatic marks (H3K4(Me3), H3K36(Me2), H3K36(Me3) and H3K18Ac). Interestingly, the ChIP-seq experiments also revealed that Arabidopsis telomeres exhibit high levels of H3K27(Me3), a repressive mark that associates with many euchromatic genes. The epigenetic profile of Arabidopsis telomeres is closely related to the previously defined chromatin state 2. This chromatin state is found in 23% of Arabidopsis genes, many of which are repressed or lowly expressed. At least, in part, this scenario is similar in rice.
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Affiliation(s)
- María I. Vaquero-Sedas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, IBVF (CSIC-USE), c/ Américo Vespucio n° 49, 41092 Seville, Spain and Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ, USA
| | - Chongyuan Luo
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, IBVF (CSIC-USE), c/ Américo Vespucio n° 49, 41092 Seville, Spain and Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ, USA
| | - Miguel A. Vega-Palas
- Instituto de Bioquímica Vegetal y Fotosíntesis, CSIC-Universidad de Sevilla, IBVF (CSIC-USE), c/ Américo Vespucio n° 49, 41092 Seville, Spain and Department of Plant Biology and Pathology, Rutgers University, New Brunswick, NJ, USA
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Lobetti-Bodoni C, Ferrero D, Genuardi E, Passera R, Bernocco E, Sia D, Grignani G, Crisà E, Monitillo L, Rocci A, Drandi D, Giai V, Zanni M, Boi M, Isaia G, Barbero D, Lunghi M, Abruzzese E, Radaelli F, Pini M, Pregno P, Carlo-Stella C, Gaidano G, Boccadoro M, Ladetto M. Telomere loss in Philadelphia-negative hematopoiesis after successful treatment of chronic myeloid leukemia: evidence for premature aging of the myeloid compartment. Mech Ageing Dev 2012; 133:479-88. [PMID: 22687638 DOI: 10.1016/j.mad.2012.05.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2012] [Revised: 04/11/2012] [Accepted: 05/29/2012] [Indexed: 01/08/2023]
Abstract
Telomere shortening, a well-known marker of aging and cellular stress, occurs under several conditions in the hematopoietic compartment, including aplastic anemia and following iatrogenic noxae. We decided to verify whether pathological telomere erosion also arises in restored Philadelphia-negative (Ph-negative) hematopoiesis following successful treatment of chronic myeloid leukemia (CML). Eighty-one CML patients in complete cytogenetic remission were compared to 76 age-matched healthy subjects. Myeloid cells of CML patients had shorter telomeres than controls (6521 bp vs 7233 bp, p<0.001). This difference was specific for the myeloid compartment, since it was not observed in lymphoid cells (6774 bp vs 6909 bp, p=0.620). Acquired Ph-negative cytogenetic abnormalities (p=0.010), lack of complete molecular remission (p=0.016) and age (p=0.013) were independent predictors of telomere shortening. Telomere dynamics were assessed over a median follow-up period of 22 months. We documented accelerated non-physiological ongoing telomere shortening in 17/59 CML patients (28%). Patients experiencing grade 2-4 hematological toxicity, during CML remission possessed significantly shorter telomeres compared to those lacking toxicity (p=0.005 for any toxicity, p=0.007 for anemia). CML patients suffer from significant and often ongoing telomere stress resulting in premature and selective aging of the myeloid compartment which might have long-term consequences on function and integrity of Ph-negative hematopoiesis.
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Affiliation(s)
- Chiara Lobetti-Bodoni
- Division of Hematology, University of Turin, A.O.U. San Giovanni Battista, Turin, Italy
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Vaquero-Sedas MI, Vega-Palas MA. DNA methylation at tobacco telomeric sequences. PLANT MOLECULAR BIOLOGY 2011; 77:529-31; author reply 533-6. [PMID: 22016003 DOI: 10.1007/s11103-011-9833-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Accepted: 10/06/2011] [Indexed: 05/31/2023]
Abstract
Majerová et al. (Plant Mol Biol, 2011) have recently reported that a considerable fraction of cytosines at tobacco telomeres is methylated. Although the data presented in this report indicate that tobacco telomeric sequences undergo certain levels of DNA methylation, it is not clear whether the methylated sequences are at telomeres, at internal chromosomal loci or at both.
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