Sample records for abnormally short telomeres

  1. The Short and Long Telomere Syndromes: Paired Paradigms for Molecular Medicine

    PubMed Central

    Stanley, Susan E.; Armanios, Mary

    2016-01-01

    Summary Recent advances have defined a role for abnormally short telomeres in a broad spectrum of genetic disorders. They include rare conditions such as dyskeratosis congenita as well pulmonary fibrosis and emphysema. Now, there is new evidence that some familial cancers, such as melanoma, are caused by mutations that lengthen telomeres. Here, we examine the significance of these short and long telomere length extremes for understanding the molecular basis of age-related disease and cancer. PMID:26232116

  2. Short Telomeres, but Not Telomere Attrition Rates, Are Associated With Carotid Atherosclerosis.

    PubMed

    Toupance, Simon; Labat, Carlos; Temmar, Mohamed; Rossignol, Patrick; Kimura, Masayuki; Aviv, Abraham; Benetos, Athanase

    2017-08-01

    Short telomeres are associated with atherosclerosis. However, the temporal relationship between atherosclerosis and telomere length is unclear. The objective of this work was to examine the temporal formation and progression of carotid atherosclerotic plaques in relation to telomere dynamics. In a longitudinal study, comprising 154 French men and women (aged 31-76 years at baseline), carotid plaques were quantified by echography, and telomere length on leucocytes was measured by Southern blots at baseline and follow-up examinations. Telomere attrition rates during the 9.5-year follow-up period were not different in individuals with plaques at both baseline and follow-up examinations (23.3±2.0 base pairs/y) than in individuals who developed plaques during the follow-up period (26.5±2.0 base pairs/y) and those without plaques at either baseline or follow-up examination (22.5±2.3 base pairs/y; P =0.79). At baseline, telomere length was associated with presence of carotid plaques ( P =0.02) and with the number of regions with plaques ( P =0.005). An interaction ( P =0.03) between age and the presence of plaques was observed, such that the association between plaques and telomere length was more pronounced at a younger age. In conclusion, carotid atherosclerosis is not associated with increased telomere attrition during a 9.5-year follow-up period. Short telomere length is more strongly associated with early-onset than late-onset carotid atherosclerosis. Our results support the thesis that heightened telomere attrition during adult life might not explain the short telomeres observed in subjects with atherosclerotic disease. Rather, short telomeres antecedes the clinical manifestation of the disease. © 2017 American Heart Association, Inc.

  3. Cloned cows with short telomeres deliver healthy offspring with normal-length telomeres.

    PubMed

    Miyashita, Norikazu; Kubo, Yasuaki; Yonai, Miharu; Kaneyama, Kanako; Saito, Norio; Sawai, Ken; Minamihashi, Akira; Suzuki, Toshiyuki; Kojima, Toshiyuki; Nagai, Takashi

    2011-10-01

    Dolly, the first mammal cloned from a somatic cell, had shorter telomeres than age-matched controls and died at an early age because of disease. To investigate longevity and lifetime performance in cloned animals, we produced cloned cows with short telomeres using oviductal epithelial cells as donor cells. At 5 years of age, despite the presence of short telomeres, all cloned cows delivered multiple healthy offspring following artificial insemination with conventionally processed spermatozoa from noncloned bulls, and their milk production was comparable to that of donor cows. Moreover, this study revealed that the offspring had normal-length telomeres in their leukocytes and major organs. Thus, cloned animals have normal functional germ lines, and therefore germ line function can completely restore telomere lengths in clone gametes by telomerase activity, resulting in healthy offspring with normal-length telomeres.

  4. Telomere dysfunction and chromosome structure modulate the contribution of individual chromosomes in abnormal nuclear morphologies.

    PubMed

    Pampalona, J; Soler, D; Genescà, A; Tusell, L

    2010-01-05

    The cytokinesis-block micronucleus assay has emerged as a biomarker of chromosome damage relevant to cancer. Although it was initially developed to measure micronuclei, it is also useful for measuring nucleoplasmic bridges and nuclear buds. Abnormal nuclear morphologies are frequently observed in malignant tissues and short-term tumour cell cultures. Changes in chromosome structure and number resulting from chromosome instability are important factors in oncogenesis. Telomeres have become key players in the initiation of chromosome instability related to carcinogenesis by means of breakage-fusion-bridge cycles. To better understand the connection between telomere dysfunction and the appearance of abnormal nuclear morphologies, we have characterised the presence of micronuclei, nucleoplasmic bridges and nuclear buds in human mammary primary epithelial cells. These cells can proliferate beyond the Hayflick limit by spontaneously losing expression of the p16(INK4a) protein. Progressive telomere shortening leads to the loss of the capping function, and the appearance of end-to-end chromosome fusions that can enter into breakage-fusion-bridge cycles generating massive chromosomal instability. In human mammary epithelial cells, different types of abnormal nuclear morphologies were observed, however only nucleoplasmatic bridges and buds increased significantly with population doublings. Fluorescent in situ hybridisation using centromeric and painting specific probes for chromosomes with eroded telomeres has revealed that these chromosomes are preferentially included in the different types of abnormal nuclear morphologies observed, thus reflecting their common origin. Accordingly, real-time imaging of cell divisions enabled us to determine that anaphase bridge resolution was mainly through chromatin breakage and the formation of symmetric buds in daughter nuclei. Few micronuclei emerged in this cell system thus validating the scoring of nucleoplasmic bridges and nuclear

  5. Disrupted lymphocyte homeostasis in hepatitis‐associated acquired aplastic anemia is associated with short telomeres

    PubMed Central

    Babushok, Daria V.; Grignon, Anne‐Laure; Li, Yimei; Atienza, Jamie; Xie, Hongbo M.; Lam, Ho‐Sun; Hartung, Helge; Bessler, Monica

    2016-01-01

    Hepatitis‐associated aplastic anemia (HAA) is a variant of acquired aplastic anemia (AA) in which immune‐mediated bone marrow failure (BMF) develops following an acute episode of seronegative hepatitis. Dyskeratosis congenita (DC) is an inherited BMF syndrome characterized by the presence of short telomeres, mucocutaneous abnormalities, and cancer predisposition. While both conditions may cause BMF and hepatic impairment, therapeutic approaches are distinct, making it imperative to establish the correct diagnosis. In clinical practice, lymphocyte telomere lengths (TL) are used as a first‐line screen to rule out inherited telomeropathies before initiating treatment for AA. To evaluate the reliability of TL in the HAA population, we performed a retrospective analysis of TL in 10 consecutively enrolled HAA patients compared to 19 patients with idiopathic AA (IAA). HAA patients had significantly shorter telomeres than IAA patients (P = 0.009), including four patients with TL at or below the 1st percentile for age‐matched controls. HAA patients had no clinical features of DC and did not carry disease‐causing mutations in known genes associated with inherited telomere disorders. Instead, short TLs were significantly correlated with severe lymphopenia and skewed lymphocyte subsets, features characteristic of HAA. Our results indicate the importance of caution in the interpretation of TL measurements in HAA, because, in this patient population, short telomeres have limited specificity. Am. J. Hematol. 91:243–247, 2016. © 2015 The Authors. American Journal of Hematology Published by Wiley Periodicals, Inc. PMID:26615915

  6. Telomerase and Tel1p Preferentially Associate with Short Telomeres in S. cerevisiae

    PubMed Central

    Sabourin, Michelle; Tuzon, Creighton T.; Zakian, Virginia A.

    2009-01-01

    SUMMARY In diverse organisms, telomerase preferentially elongates short telomeres. We generated a single short telomere in otherwise wild-type (WT) S. cerevisiae cells. The binding of the positive regulators Ku and Cdc13p was similar at short and WT-length telomeres. The negative regulators Rif1p and Rif2p were present at the short telomere, although Rif2p levels were reduced. Two telomerase holoenzyme components, Est1p and Est2p, were preferentially enriched at short telomeres in late S/G2 phase, the time of telomerase action. Tel1p, the yeast ATM-like checkpoint kinase, was highly enriched at short telomeres from early S through G2 phase and even into the next cell cycle. Nonetheless, induction of a single short telomere did not elicit a cell-cycle arrest. Tel1p binding was dependent on Xrs2p and required for preferential binding of telomerase to short telomeres. These data suggest that Tel1p targets telomerase to the DNA ends most in need of extension. PMID:17656141

  7. Frequency of chromosome healing and interstitial telomeres in 40 cases of constitutional abnormalities.

    PubMed

    Fortin, F; Beaulieu Bergeron, M; Fetni, R; Lemieux, N

    2009-01-01

    Human telomeres play a major role in stabilizing chromosome ends and preventing fusions. Chromosomes bearing a broken end are rescued by the acquisition of a new telomeric cap without any subtelomeric sequences being present at the breakpoint, a process referred to as chromosome healing. Conversely, a loss of telomeric function or integrity can lead to the presence of interstitial telomeres at the junction site in translocations or ring chromosomes. In order to determine the frequency at which interstitial telomeres or chromosome healing events are observed in target chromosome abnormalities, we conducted a retrospective FISH study using pan-telomeric and chromosome-specific subtelomeric probes on archival material from 40 cases of terminal deletions, translocations or ring chromosomes. Of the 19 terminal deletions investigated, 17 were negative for the subtelomeric probe specific to the deleted arm despite being positive for the pan-telomeric probe. These 17 cases were thus considered as having been rescued through chromosome healing, suggesting that this process is frequent in terminal deletions. In addition, as 2 of these cases were inherited from a parent bearing the same deletion, chromosomes healed by this process are thus stable through mitosis and meiosis. Regarding the 13 cases of translocations and 8 ring chromosomes, 4 and 2 cases respectively demonstrated pan-telomeric sequences at the interstitial junction point. Furthermore, 2 cases of translocations and 1 ring chromosome had both interstitial pan-telomeres and subtelomeres, whereas 2 other cases of ring chromosomes and 1 case of translocation only showed interstitial subtelomeres. Therefore, interstitial (sub)telomeric sequences in translocations and ring chromosomes are more common than previously thought, as we found a frequency of 43% in this study. Moreover, our results illustrate the necessity of performing FISH with both subtelomeric and pan-telomeric probes when investigating these

  8. Telomere Length Maintenance and Cardio-Metabolic Disease Prevention Through Exercise Training.

    PubMed

    Denham, Joshua; O'Brien, Brendan J; Charchar, Fadi J

    2016-09-01

    Telomeres are tandem repeat DNA sequences located at distal ends of chromosomes that protect against genomic DNA degradation and chromosomal instability. Excessive telomere shortening leads to cellular senescence and for this reason telomere length is a marker of biological age. Abnormally short telomeres may culminate in the manifestation of a number of cardio-metabolic diseases. Age-related cardio-metabolic diseases attributable to an inactive lifestyle, such as obesity, type 2 diabetes mellitus and cardiovascular disease, are associated with short leukocyte telomeres. Exercise training prevents and manages the symptoms of many cardio-metabolic diseases whilst concurrently maintaining telomere length. The positive relationship between exercise training, physical fitness and telomere length raises the possibility of a mediating role of telomeres in chronic disease prevention via exercise. Further elucidation of the underpinning molecular mechanisms of how exercise maintains telomere length should provide crucial information on how physical activity can be best structured to combat the chronic disease epidemic and improve the human health span. Here, we synthesise and discuss the current evidence on the impact of physical activity and cardiorespiratory fitness on telomere dynamics. We provide the molecular mechanisms with a known role in exercise-induced telomere length maintenance and highlight unexplored, alternative pathways ripe for future investigations.

  9. Rad59-Facilitated Acquisition of Y′ Elements by Short Telomeres Delays the Onset of Senescence

    PubMed Central

    Churikov, Dmitri; Charifi, Ferose; Simon, Marie-Noëlle; Géli, Vincent

    2014-01-01

    Telomerase-negative yeasts survive via one of the two Rad52-dependent recombination pathways, which have distinct genetic requirements. Although the telomere pattern of type I and type II survivors is well characterized, the mechanistic details of short telomere rearrangement into highly evolved pattern observed in survivors are still missing. Here, we analyze immediate events taking place at the abruptly shortened VII-L and native telomeres. We show that short telomeres engage in pairing with internal Rap1-bound TG1–3-like tracts present between subtelomeric X and Y′ elements, which is followed by BIR-mediated non-reciprocal translocation of Y′ element and terminal TG1–3 repeats from the donor end onto the shortened telomere. We found that choice of the Y′ donor was not random, since both engineered telomere VII-L and native VI-R acquired Y′ elements from partially overlapping sets of specific chromosome ends. Although short telomere repair was associated with transient delay in cell divisions, Y′ translocation on native telomeres did not require Mec1-dependent checkpoint. Furthermore, the homeologous pairing between the terminal TG1–3 repeats at VII-L and internal repeats on other chromosome ends was largely independent of Rad51, but instead it was facilitated by Rad59 that stimulates Rad52 strand annealing activity. Therefore, Y′ translocation events taking place during presenescence are genetically separable from Rad51-dependent Y′ amplification process that occurs later during type I survivor formation. We show that Rad59-facilitated Y′ translocations on X-only telomeres delay the onset of senescence while preparing ground for type I survivor formation. PMID:25375789

  10. The effect of Ku on telomere replication time is mediated by telomere length but is independent of histone tail acetylation.

    PubMed

    Lian, Hui-Yong; Robertson, E Douglas; Hiraga, Shin-ichiro; Alvino, Gina M; Collingwood, David; McCune, Heather J; Sridhar, Akila; Brewer, Bonita J; Raghuraman, M K; Donaldson, Anne D

    2011-05-15

    DNA replication in Saccharomyces cerevisiae proceeds according to a temporal program. We have investigated the role of the telomere-binding Ku complex in specifying late replication of telomere-proximal sequences. Genome-wide analysis shows that regions extending up to 80 kb from telomeres replicate abnormally early in a yku70 mutant. We find that Ku does not appear to regulate replication time by binding replication origins directly, nor is its effect on telomere replication timing mediated by histone tail acetylation. We show that Ku instead regulates replication timing through its effect on telomere length, because deletion of the telomerase regulator Pif1 largely reverses the short telomere defect of a yku70 mutant and simultaneously rescues its replication timing defect. Consistent with this conclusion, deleting the genome integrity component Elg1 partially rescued both length and replication timing of yku70 telomeres. Telomere length-mediated control of replication timing requires the TG(1-3) repeat-counting component Rif1, because a rif1 mutant replicates telomeric regions early, despite having extended TG(1-3) tracts. Overall, our results suggest that the effect of Ku on telomere replication timing results from its impact on TG(1-3) repeat length and support a model in which Rif1 measures telomere repeat length to ensure that telomere replication timing is correctly programmed.

  11. Abnormal mRNA Expression Levels of Telomere-Binding Proteins Represent Biomarkers in Myelodysplastic Syndromes: A Case-Control Study.

    PubMed

    Liu, Baoshan; Yan, Rongdi; Zhang, Jie; Wang, Bin; Sun, Hu; Cui, Xing

    2017-08-02

    As evidence was shown that abnormal shortening of telomeres begins to accumulate in myelodysplastic syndrome (MDS) patients, this study was conducted to determine the relationship between the mRNA expression levels of telomere-binding proteins (TRF1/TRF2/TIN2/TPP1/POT1/RAP1) and the risk level in MDS. There were 40 patients with MDS and 40 normal controls in this study. Methods including telomere content assays and quantitative reverse transcription-polymerase chain reaction were used to examine the mRNA levels of TRF1/TRF2/TIN2/TPP1/POT1/RAP1 in patients with MDS. Compared to the normal group used as a control, the mRNA expression levels of RAP1/POT1/TPP1 of the patients with MDS were decreased, whereas their levels of TRF1/TRF2 and TIN2 were increased. A positive correlation was found between the TRF1, TRF2, and TIN2 mRNA expression levels and the risk level of the International Prognostic Scoring System (IPSS) and the World Health Organization Prognostic Scoring System (WPSS) criteria; however, a negative correlation was found between RAP1/POT1/TPP1 mRNA expression levels and the risk levels of IPSS and WPSS criteria. Because the reduction of TRF1/TRF2/TIN2 mRNA expression and the increase of RAP1/POT1/TPP1 mRNA expression are closely related to the risk levels of the IPSS and WPSS criteria in MDS, it is thought that these telomere-binding proteins could lead to abnormal telomere length and function, which cause chromosomal abnormalities in MDS. With this evidence, we suggest that those proteins' mRNA expressions could be used as biomarkers for the assessment of the risk degree of MDS patients.

  12. Germline mutations of regulator of telomere elongation helicase 1, RTEL1, in Dyskeratosis congenita.

    PubMed

    Ballew, Bari J; Yeager, Meredith; Jacobs, Kevin; Giri, Neelam; Boland, Joseph; Burdett, Laurie; Alter, Blanche P; Savage, Sharon A

    2013-04-01

    Dyskeratosis congenita (DC) is an inherited bone marrow failure and cancer predisposition syndrome caused by aberrant telomere biology. The classic triad of dysplastic nails, abnormal skin pigmentation, and oral leukoplakia is diagnostic of DC, but substantial clinical heterogeneity exists; the clinically severe variant Hoyeraal Hreidarsson syndrome (HH) also includes cerebellar hypoplasia, severe immunodeficiency, enteropathy, and intrauterine growth retardation. Germline mutations in telomere biology genes account for approximately one-half of known DC families. Using exome sequencing, we identified mutations in RTEL1, a helicase with critical telomeric functions, in two families with HH. In the first family, two siblings with HH and very short telomeres inherited a premature stop codon from their mother who has short telomeres. The proband from the second family has HH and inherited a premature stop codon in RTEL1 from his father and a missense mutation from his mother, who also has short telomeres. In addition, inheritance of only the missense mutation led to very short telomeres in the proband's brother. Targeted sequencing identified a different RTEL1 missense mutation in one additional DC proband who has bone marrow failure and short telomeres. Both missense mutations affect the helicase domain of RTEL1, and three in silico prediction algorithms suggest that they are likely deleterious. The nonsense mutations both cause truncation of the RTEL1 protein, resulting in loss of the PIP box; this may abrogate an important protein-protein interaction. These findings implicate a new telomere biology gene, RTEL1, in the etiology of DC.

  13. Germline Mutations of Regulator of Telomere Elongation Helicase 1, RTEL1, In Dyskeratosis Congenita

    PubMed Central

    Ballew, Bari J.; Yeager, Meredith; Jacobs, Kevin; Giri, Neelam; Boland, Joseph; Burdett, Laurie; Alter, Blanche P.; Savage, Sharon A.

    2013-01-01

    Dyskeratosis congenita (DC) is an inherited bone marrow failure and cancer predisposition syndrome caused by aberrant telomere biology. The classic triad of dysplastic nails, abnormal skin pigmentation, and oral leukoplakia is diagnostic of DC, but substantial clinical heterogeneity exists; the clinically severe variant Hoyeraal Hreidarsson syndrome (HH) also includes cerebellar hypoplasia, severe immunodeficiency, enteropathy, and intrauterine growth retardation. Germline mutations in telomere biology genes account for approximately one-half of known DC families. Using exome sequencing, we identified mutations in RTEL1, a helicase with critical telomeric functions, in two families with HH. In the first family, two siblings with HH and very short telomeres inherited a premature stop codon from their mother who has short telomeres. The proband from the second family has HH and inherited a premature stop codon in RTEL1 from his father and a missense mutation from his mother, who also has short telomeres. Additionally, inheritance of only the missense mutation led to very short telomeres in the proband’s brother. Targeted sequencing identified a different RTEL1 missense mutation in one additional DC proband who has bone marrow failure and short telomeres. Both missense mutations affect the helicase domain of RTEL1, and three in silico prediction algorithms suggest that they are likely deleterious. The nonsense mutations both cause truncation of the RTEL1 protein, resulting in loss of the PIP box; this may abrogate an important protein-protein interaction. These findings implicate a new telomere biology gene, RTEL1, in the etiology of DC. PMID:23329068

  14. Short Telomeres Result in Organismal Hypersensitivity to Ionizing Radiation in Mammals

    PubMed Central

    Goytisolo, Fermín A.; Samper, Enrique; Martín-Caballero, Juan; Finnon, Paul; Herrera, Eloísa; Flores, Juana M.; Bouffler, Simon D.; Blasco, María A.

    2000-01-01

    Here we show a correlation between telomere length and organismal sensitivity to ionizing radiation (IR) in mammals. In particular, fifth generation (G5) mouse telomerase RNA (mTR)−/− mice, with telomeres 40% shorter than in wild-type mice, are hypersensitive to cumulative doses of gamma rays. 60% of the irradiated G5 mTR−/− mice die of acute radiation toxicity in the gastrointestinal tract, lymphoid organs, and kidney. The affected G5 mTR−/− mice show higher chromosomal damage and greater apoptosis than similarly irradiated wild-type controls. Furthermore, we show that G5 mTR−/− mice show normal frequencies of sister chromatid exchange and normal V(D)J recombination, suggesting that short telomeres do not significantly affect the efficiency of DNA double strand break repair in mammals. The IR-sensitive phenotype of G5 mTR−/− mice suggests that telomere function is one of the determinants of radiation sensitivity of whole animals. PMID:11104804

  15. Telomere-driven diseases and telomere-targeting therapies

    PubMed Central

    2017-01-01

    Telomeres, the protective ends of linear chromosomes, shorten throughout an individual’s lifetime. Telomere shortening is proposed to be a primary molecular cause of aging. Short telomeres block the proliferative capacity of stem cells, affecting their potential to regenerate tissues, and trigger the development of age-associated diseases. Mutations in telomere maintenance genes are associated with pathologies referred to as telomere syndromes, including Hoyeraal-Hreidarsson syndrome, dyskeratosis congenita, pulmonary fibrosis, aplastic anemia, and liver fibrosis. Telomere shortening induces chromosomal instability that, in the absence of functional tumor suppressor genes, can contribute to tumorigenesis. In addition, mutations in telomere length maintenance genes and in shelterin components, the protein complex that protects telomeres, have been found to be associated with different types of cancer. These observations have encouraged the development of therapeutic strategies to treat and prevent telomere-associated diseases, namely aging-related diseases, including cancer. Here we review the molecular mechanisms underlying telomere-driven diseases and highlight recent advances in the preclinical development of telomere-targeted therapies using mouse models. PMID:28254828

  16. Human RTEL1 deficiency causes Hoyeraal-Hreidarsson syndrome with short telomeres and genome instability.

    PubMed

    Le Guen, Tangui; Jullien, Laurent; Touzot, Fabien; Schertzer, Michael; Gaillard, Laetitia; Perderiset, Mylène; Carpentier, Wassila; Nitschke, Patrick; Picard, Capucine; Couillault, Gérard; Soulier, Jean; Fischer, Alain; Callebaut, Isabelle; Jabado, Nada; Londono-Vallejo, Arturo; de Villartay, Jean-Pierre; Revy, Patrick

    2013-08-15

    Hoyeraal-Hreidarsson syndrome (HHS), a severe variant of dyskeratosis congenita (DC), is characterized by early onset bone marrow failure, immunodeficiency and developmental defects. Several factors involved in telomere length maintenance and/or protection are defective in HHS/DC, underlining the relationship between telomere dysfunction and these diseases. By combining whole-genome linkage analysis and exome sequencing, we identified compound heterozygous RTEL1 (regulator of telomere elongation helicase 1) mutations in three patients with HHS from two unrelated families. RTEL1 is a DNA helicase that participates in DNA replication, DNA repair and telomere integrity. We show that, in addition to short telomeres, RTEL1-deficient cells from patients exhibit hallmarks of genome instability, including spontaneous DNA damage, anaphase bridges and telomeric aberrations. Collectively, these results identify RTEL1 as a novel HHS-causing gene and highlight its role as a genomic caretaker in humans.

  17. Selective disappearance of great tits with short telomeres in urban areas.

    PubMed

    Salmón, Pablo; Nilsson, Johan F; Watson, Hannah; Bensch, Staffan; Isaksson, Caroline

    2017-09-13

    Urban environments pose novel challenges, as well as opportunities, for urban-dwelling wildlife. Although differences have been reported in several phenotypic traits (e.g. morphology, physiology and behaviour) between urban and rural populations, it is poorly understood whether this affects individual fitness. Telomere dynamics are posited as one possible mechanism underlying senescence and mortality. It was recently shown that telomere shortening is accelerated when growing up in an urban, compared with a rural, environment. However, the implications of accelerated telomere attrition for fitness are still unclear. Here, we examine the relationship between telomere length (TL) and survival in a bird common to urban and rural environments, and during both early and later life. The results reveal that TL is a strong predictor of post-fledging survival and recruitment in both habitats but, crucially, selective disappearance of individuals with short telomeres early in life is more pronounced in the urban environment, resulting in a longer average TL among the adult population. However, following recruitment, we found no difference in the relationship between TL and survival between the urban and rural environments. This indicates that the urban environment has negative effects in early life, while during later life the benefits could potentially outweigh the costs. © 2017 The Author(s).

  18. Recombination Can Cause Telomere Elongations as Well as Truncations Deep within Telomeres in Wild-Type Kluyveromyces lactis Cells ▿

    PubMed Central

    Bechard, Laura H.; Jamieson, Nathan; McEachern, Michael J.

    2011-01-01

    In this study, we examined the role of recombination at the telomeres of the yeast Kluyveromyces lactis. We demonstrated that an abnormally long and mutationally tagged telomere was subject to high rates of telomere rapid deletion (TRD) that preferentially truncated the telomere to near-wild-type size. Unlike the case in Saccharomyces cerevisiae, however, there was not a great increase in TRD in meiosis. About half of mitotic TRD events were associated with deep turnover of telomeric repeats, suggesting that telomeres were often cleaved to well below normal length prior to being reextended by telomerase. Despite its high rate of TRD, the long telomere showed no increase in the rate of subtelomeric gene conversion, a highly sensitive test of telomere dysfunction. We also showed that the long telomere was subject to appreciable rates of becoming elongated substantially further through a recombinational mechanism that added additional tagged repeats. Finally, we showed that the deep turnover that occurs within normal-length telomeres was diminished in the absence of RAD52. Taken together, our results suggest that homologous recombination is a significant process acting on both abnormally long and normally sized telomeres in K. lactis. PMID:21148753

  19. Therapeutic effects of telomerase in mice with pulmonary fibrosis induced by damage to the lungs and short telomeres.

    PubMed

    Povedano, Juan Manuel; Martinez, Paula; Serrano, Rosa; Tejera, Águeda; Gómez-López, Gonzalo; Bobadilla, Maria; Flores, Juana Maria; Bosch, Fátima; Blasco, Maria A

    2018-01-30

    Pulmonary fibrosis is a fatal lung disease characterized by fibrotic foci and inflammatory infiltrates. Short telomeres can impair tissue regeneration and are found both in hereditary and sporadic cases. We show here that telomerase expression using AAV9 vectors shows therapeutic effects in a mouse model of pulmonary fibrosis owing to a low-dose bleomycin insult and short telomeres. AAV9 preferentially targets regenerative alveolar type II cells (ATII). AAV9- Tert -treated mice show improved lung function and lower inflammation and fibrosis at 1-3 weeks after viral treatment, and improvement or disappearance of the fibrosis at 8 weeks after treatment. AAV9- Tert treatment leads to longer telomeres and increased proliferation of ATII cells, as well as lower DNA damage, apoptosis, and senescence. Transcriptome analysis of ATII cells confirms downregulation of fibrosis and inflammation pathways. We provide a proof-of-principle that telomerase activation may represent an effective treatment for pulmonary fibrosis provoked or associated with short telomeres. © 2018, Povedano et al.

  20. Therapeutic effects of telomerase in mice with pulmonary fibrosis induced by damage to the lungs and short telomeres

    PubMed Central

    Serrano, Rosa; Tejera, Águeda; Gómez-López, Gonzalo; Bobadilla, Maria; Flores, Juana Maria; Bosch, Fátima

    2018-01-01

    Pulmonary fibrosis is a fatal lung disease characterized by fibrotic foci and inflammatory infiltrates. Short telomeres can impair tissue regeneration and are found both in hereditary and sporadic cases. We show here that telomerase expression using AAV9 vectors shows therapeutic effects in a mouse model of pulmonary fibrosis owing to a low-dose bleomycin insult and short telomeres. AAV9 preferentially targets regenerative alveolar type II cells (ATII). AAV9-Tert-treated mice show improved lung function and lower inflammation and fibrosis at 1–3 weeks after viral treatment, and improvement or disappearance of the fibrosis at 8 weeks after treatment. AAV9-Tert treatment leads to longer telomeres and increased proliferation of ATII cells, as well as lower DNA damage, apoptosis, and senescence. Transcriptome analysis of ATII cells confirms downregulation of fibrosis and inflammation pathways. We provide a proof-of-principle that telomerase activation may represent an effective treatment for pulmonary fibrosis provoked or associated with short telomeres. PMID:29378675

  1. A quantitative telomeric chromatin isolation protocol identifies different telomeric states

    NASA Astrophysics Data System (ADS)

    Grolimund, Larissa; Aeby, Eric; Hamelin, Romain; Armand, Florence; Chiappe, Diego; Moniatte, Marc; Lingner, Joachim

    2013-11-01

    Telomere composition changes during tumourigenesis, aging and in telomere syndromes in a poorly defined manner. Here we develop a quantitative telomeric chromatin isolation protocol (QTIP) for human cells, in which chromatin is cross-linked, immunopurified and analysed by mass spectrometry. QTIP involves stable isotope labelling by amino acids in cell culture (SILAC) to compare and identify quantitative differences in telomere protein composition of cells from various states. With QTIP, we specifically enrich telomeric DNA and all shelterin components. We validate the method characterizing changes at dysfunctional telomeres, and identify and validate known, as well as novel telomere-associated polypeptides including all THO subunits, SMCHD1 and LRIF1. We apply QTIP to long and short telomeres and detect increased density of SMCHD1 and LRIF1 and increased association of the shelterins TRF1, TIN2, TPP1 and POT1 with long telomeres. Our results validate QTIP to study telomeric states during normal development and in disease.

  2. Telomere length in the two extremes of abnormal fetal growth and the programming effect of maternal arterial hypertension.

    PubMed

    Tellechea, Mariana; Gianotti, Tomas Fernandéz; Alvariñas, Jorge; González, Claudio D; Sookoian, Silvia; Pirola, Carlos J

    2015-01-19

    We tested the hypothesis that leukocyte telomere length (LTL) is associated with birth weight in both extremes of abnormal fetal growth: small (SGA) and large for gestational age newborns (LGA). Clinical and laboratory variables of the mothers and the neonates were explored; 45 newborns with appropriate weight for gestational age (AGA), 12 SGA and 12 LGA were included. Whether the differences might be explained by variation in OBFC1 (rs9419958) and CTC1 (rs3027234) genes associated with LTL was determined. A significant association between birth weight and LTL was observed; LTL was significantly shorter in LGA newborns (1.01 ± 0.12) compared with SGA (1.73 ± 0.19) p < 0.005, mean ± SE. Maternal (Spearman R = -0.6, p = 0.03) and neonatal LTL (R = -0.25, p = 0.03) were significantly and inversely correlated with maternal history of arterial hypertension in previous gestations. Neonatal LTL was not significantly associated with either rs9419950 or rs3027234, suggesting that the association between neonatal LTL and birth weight is not influenced by genetic variation in genes that modify the interindividual LTL. In conclusion, telomere biology seems to be modulated by abnormal fetal growth; modifications in telomere length might be programmed by an adverse environment in utero.

  3. Telomeres and telomerase.

    PubMed Central

    Chan, Simon R W L; Blackburn, Elizabeth H

    2004-01-01

    Telomeres are the protective DNA-protein complexes found at the ends of eukaryotic chromosomes. Telomeric DNA consists of tandem repeats of a simple, often G-rich, sequence specified by the action of telomerase, and complete replication of telomeric DNA requires telomerase. Telomerase is a specialized cellular ribonucleoprotein reverse transcriptase. By copying a short template sequence within its intrinsic RNA moiety, telomerase synthesizes the telomeric DNA strand running 5' to 3' towards the distal end of the chromosome, thus extending it. Fusion of a telomere, either with another telomere or with a broken DNA end, generally constitutes a catastrophic event for genomic stability. Telomerase acts to prevent such fusions. The molecular consequences of telomere failure, and the molecular contributors to telomere function, with an emphasis on telomerase, are discussed here. PMID:15065663

  4. Telomere length analysis.

    PubMed

    Canela, Andrés; Klatt, Peter; Blasco, María A

    2007-01-01

    Most somatic cells of long-lived species undergo telomere shortening throughout life. Critically short telomeres trigger loss of cell viability in tissues, which has been related to alteration of tissue function and loss of regenerative capabilities in aging and aging-related diseases. Hence, telomere length is an important biomarker for aging and can be used in the prognosis of aging diseases. These facts highlight the importance of developing methods for telomere length determination that can be employed to evaluate telomere length during the human aging process. Telomere length quantification methods have improved greatly in accuracy and sensitivity since the development of the conventional telomeric Southern blot. Here, we describe the different methodologies recently developed for telomere length quantification, as well as their potential applications for human aging studies.

  5. Telomerase gene therapy rescues telomere length, bone marrow aplasia, and survival in mice with aplastic anemia.

    PubMed

    Bär, Christian; Povedano, Juan Manuel; Serrano, Rosa; Benitez-Buelga, Carlos; Popkes, Miriam; Formentini, Ivan; Bobadilla, Maria; Bosch, Fatima; Blasco, Maria A

    2016-04-07

    Aplastic anemia is a fatal bone marrow disorder characterized by peripheral pancytopenia and marrow hypoplasia. The disease can be hereditary or acquired and develops at any stage of life. A subgroup of the inherited form is caused by replicative impairment of hematopoietic stem and progenitor cells due to very short telomeres as a result of mutations in telomerase and other telomere components. Abnormal telomere shortening is also described in cases of acquired aplastic anemia, most likely secondary to increased turnover of bone marrow stem and progenitor cells. Here, we test the therapeutic efficacy of telomerase activation by using adeno-associated virus (AAV)9 gene therapy vectors carrying the telomerase Tert gene in 2 independent mouse models of aplastic anemia due to short telomeres (Trf1- and Tert-deficient mice). We find that a high dose of AAV9-Tert targets the bone marrow compartment, including hematopoietic stem cells. AAV9-Tert treatment after telomere attrition in bone marrow cells rescues aplastic anemia and mouse survival compared with mice treated with the empty vector. Improved survival is associated with a significant increase in telomere length in peripheral blood and bone marrow cells, as well as improved blood counts. These findings indicate that telomerase gene therapy represents a novel therapeutic strategy to treat aplastic anemia provoked or associated with short telomeres. © 2016 by The American Society of Hematology.

  6. Telomeres and age-related disease: how telomere biology informs clinical paradigms

    PubMed Central

    Armanios, Mary

    2013-01-01

    Telomere length shortens with age and predicts the onset of replicative senescence. Recently, short telomeres have been linked to the etiology of degenerative diseases such as idiopathic pulmonary fibrosis, bone marrow failure, and cryptogenic liver cirrhosis. These disorders have recognizable clinical manifestations, and the telomere defect explains their genetics and informs the approach to their treatment. Here, I review how telomere biology has become intimately connected to clinical paradigms both for understanding pathophysiology and for individualizing therapy decisions. I also critically examine nuances of interpreting telomere length measurement in clinical studies. PMID:23454763

  7. Therapeutic effect of androgen therapy in a mouse model of aplastic anemia produced by short telomeres

    PubMed Central

    Bär, Christian; Huber, Nicolas; Beier, Fabian; Blasco, Maria A.

    2015-01-01

    Aplastic anemia is a rare but life-threatening disorder characterized by cytopenia in at least two of the three blood lineages. A frequent feature of patients with aplastic anemia is that they have shorter telomeres than those of age-matched controls. Testosterone has been used for over half a century in the treatment of aplastic anemia. However, although remissions are frequent following hormone therapy, the molecular mechanism underlying the response to treatment has remained unknown. Here we explored the possibility that the recently described regulation of telomerase activity by sex hormones may be the mechanism responsible. To this end, we used a mouse model of aplastic anemia induced by short telomeres in the bone marrow compartment. We found that testosterone therapy results in telomerase up-regulation, improved blood counts, and a significant extension of life-span of these mice. Importantly, longitudinal follow-up studies revealed longer telomeres in peripheral blood in mice subjected to hormone treatment. Our results demonstrate that testosterone-mediated telomerase activation can attenuate or reverse aplastic anemia disease progression associated with the presence of short telomeres. PMID:26206796

  8. Short telomeres in hatchling snakes: erythrocyte telomere dynamics and longevity in tropical pythons.

    PubMed

    Ujvari, Beata; Madsen, Thomas

    2009-10-16

    Telomere length (TL) has been found to be associated with life span in birds and humans. However, other studies have demonstrated that TL does not affect survival among old humans. Furthermore, replicative senescence has been shown to be induced by changes in the protected status of the telomeres rather than the loss of TL. In the present study we explore whether age- and sex-specific telomere dynamics affect life span in a long-lived snake, the water python (Liasis fuscus). Erythrocyte TL was measured using the Telo TAGGG TL Assay Kit (Roche). In contrast to other vertebrates, TL of hatchling pythons was significantly shorter than that of older snakes. However, during their first year of life hatchling TL increased substantially. While TL of older snakes decreased with age, we did not observe any correlation between TL and age in cross-sectional sampling. In older snakes, female TL was longer than that of males. When using recapture as a proxy for survival, our results do not support that longer telomeres resulted in an increased water python survival/longevity. In fish high telomerase activity has been observed in somatic cells exhibiting high proliferation rates. Hatchling pythons show similar high somatic cell proliferation rates. Thus, the increase in TL of this group may have been caused by increased telomerase activity. In older humans female TL is longer than that of males. This has been suggested to be caused by high estrogen levels that stimulate increased telomerase activity. Thus, high estrogen levels may also have caused the longer telomeres in female pythons. The lack of correlation between TL and age among old snakes and the fact that longer telomeres did not appear to affect python survival do not support that erythrocyte telomere dynamics has a major impact on water python longevity.

  9. A single-cell assay for telomere DNA content shows increasing telomere length heterogeneity, as well as increasing mean telomere length in human spermatozoa with advancing age.

    PubMed

    Antunes, Danielle M F; Kalmbach, Keri H; Wang, Fang; Dracxler, Roberta C; Seth-Smith, Michelle L; Kramer, Yael; Buldo-Licciardi, Julia; Kohlrausch, Fabiana B; Keefe, David L

    2015-11-01

    The effect of age on telomere length heterogeneity in men has not been studied previously. Our aims were to determine the relationship between variation in sperm telomere length (STL), men's age, and semen parameters in spermatozoa from men undergoing in vitro fertilization (IVF) treatment. To perform this prospective cross-sectional pilot study, telomere length was estimated in 200 individual spermatozoa from men undergoing IVF treatment at the NYU Fertility Center. A novel single-cell telomere content assay (SCT-pqPCR) measured telomere length in individual spermatozoa. Telomere length among individual spermatozoa within an ejaculate varies markedly and increases with age. Older men not only have longer STL but also have more variable STL compared to younger men. STL from samples with normal semen parameters was significantly longer than that from samples with abnormal parameters, but STL did not differ between spermatozoa with normal versus abnormal morphology. The marked increase in STL heterogeneity as men age is consistent with a role for ALT during spermatogenesis. No data have yet reported the effect of age on STL heterogeneity. Based on these results, future studies should expand this modest sample size to search for molecular evidence of ALT in human testes during spermatogenesis.

  10. Telomere length variation: A potential new telomere biomarker for lung cancer risk

    PubMed Central

    Sun, Bing; Wang, Ying; Kota, Krishna; Shi, Yaru; Motlak, Salaam; Makambi, Kepher; Loffredo, Christopher A.; Shields, Peter G.; Yang, Qin; Harris, Curtis C.; Zheng, Yun-Ling

    2015-01-01

    Objectives In this report the associations between telomere length variation (TLV), mean telomere length in blood lymphocytes and lung cancer risk were examined. Materials and Methods The study design is case-control. Cases (N = 191) were patients newly diagnosed with histologically confirmed non-small cell lung cancer. Controls (N = 207) were healthy individuals recruited from the same counties as cases and matched to cases on age and gender. Telomere fluorescent in situ hybridization was used to measure telomere features using short-term cultured blood lymphocytes. Logistic regression was used to estimate the strength of association between telomere features and lung cancer risk. Results Telomere length variation across all chromosomal ends was significantly associated with lung cancer risk; adjusted odds ratios 4.67 [95% confidence interval (CI): 1.46 – 14.9] and 0.46 (95% CI: 0.25 – 0.84) for younger (age ≤ 60) and older (age > 60) individuals, respectively. TLV and mean telomere length jointly affected lung cancer risk: when comparing individuals with short telomere length and high TLV to those with long telomere length and low TLV, adjusted odd ratios were 8.21 (95% CI: 1.71 – 39.5) and 0.33 (95% CI: 0.15 – 0.72) for younger and older individuals, respectively. Conclusions TLV in blood lymphocytes is significantly associated with lung cancer risk and the associations were modulated by age. TLV in combination with mean telomere length might be useful in identifying high risk population for lung cancer computerized tomography screening. PMID:25840848

  11. Therapeutic effect of androgen therapy in a mouse model of aplastic anemia produced by short telomeres.

    PubMed

    Bär, Christian; Huber, Nicolas; Beier, Fabian; Blasco, Maria A

    2015-10-01

    Aplastic anemia is a rare but life-threatening disorder characterized by cytopenia in at least two of the three blood lineages. A frequent feature of patients with aplastic anemia is that they have shorter telomeres than those of age-matched controls. Testosterone has been used for over half a century in the treatment of aplastic anemia. However, although remissions are frequent following hormone therapy, the molecular mechanism underlying the response to treatment has remained unknown. Here we explored the possibility that the recently described regulation of telomerase activity by sex hormones may be the mechanism responsible. To this end, we used a mouse model of aplastic anemia induced by short telomeres in the bone marrow compartment. We found that testosterone therapy results in telomerase up-regulation, improved blood counts, and a significant extension of life-span of these mice. Importantly, longitudinal follow-up studies revealed longer telomeres in peripheral blood in mice subjected to hormone treatment. Our results demonstrate that testosterone-mediated telomerase activation can attenuate or reverse aplastic anemia disease progression associated with the presence of short telomeres. Copyright© Ferrata Storti Foundation.

  12. Fanconi anemia proteins in telomere maintenance.

    PubMed

    Sarkar, Jaya; Liu, Yie

    2016-07-01

    Mammalian chromosome ends are protected by nucleoprotein structures called telomeres. Telomeres ensure genome stability by preventing chromosome termini from being recognized as DNA damage. Telomere length homeostasis is inevitable for telomere maintenance because critical shortening or over-lengthening of telomeres may lead to DNA damage response or delay in DNA replication, and hence genome instability. Due to their repetitive DNA sequence, unique architecture, bound shelterin proteins, and high propensity to form alternate/secondary DNA structures, telomeres are like common fragile sites and pose an inherent challenge to the progression of DNA replication, repair, and recombination apparatus. It is conceivable that longer the telomeres are, greater is the severity of such challenges. Recent studies have linked excessively long telomeres with increased tumorigenesis. Here we discuss telomere abnormalities in a rare recessive chromosomal instability disorder called Fanconi Anemia and the role of the Fanconi Anemia pathway in telomere biology. Reports suggest that Fanconi Anemia proteins play a role in maintaining long telomeres, including processing telomeric joint molecule intermediates. We speculate that ablation of the Fanconi Anemia pathway would lead to inadequate aberrant structural barrier resolution at excessively long telomeres, thereby causing replicative burden on the cell. Published by Elsevier B.V.

  13. Do Telomeres Adapt to Physiological Stress? Exploring the Effect of Exercise on Telomere Length and Telomere-Related Proteins

    PubMed Central

    Ludlow, Andrew T.; Ludlow, Lindsay W.; Roth, Stephen M.

    2013-01-01

    Aging is associated with a tissue degeneration phenotype marked by a loss of tissue regenerative capacity. Regenerative capacity is dictated by environmental and genetic factors that govern the balance between damage and repair. The age-associated changes in the ability of tissues to replace lost or damaged cells is partly the cause of many age-related diseases such as Alzheimer's disease, cardiovascular disease, type II diabetes, and sarcopenia. A well-established marker of the aging process is the length of the protective cap at the ends of chromosomes, called telomeres. Telomeres shorten with each cell division and with increasing chronological age and short telomeres have been associated with a range of age-related diseases. Several studies have shown that chronic exposure to exercise (i.e., exercise training) is associated with telomere length maintenance; however, recent evidence points out several controversial issues concerning tissue-specific telomere length responses. The goals of the review are to familiarize the reader with the current telomere dogma, review the literature exploring the interactions of exercise with telomere phenotypes, discuss the mechanistic research relating telomere dynamics to exercise stimuli, and finally propose future directions for work related to telomeres and physiological stress. PMID:24455708

  14. Short telomeres: from dyskeratosis congenita to sporadic aplastic anemia and malignancy.

    PubMed

    Gramatges, Maria M; Bertuch, Alison A

    2013-12-01

    Telomeres are DNA-protein structures that form a protective cap on chromosome ends. As such, they prevent the natural ends of linear chromosomes from being subjected to DNA repair activities that would result in telomere fusion, degradation, or recombination. Both the DNA and protein components of the telomere are required for this essential function, because insufficient telomeric DNA length, loss of the terminal telomeric DNA structure, or deficiency of key telomere-associated factors may elicit a DNA damage response and result in cellular senescence or apoptosis. In the setting of failed checkpoint mechanisms, such DNA-protein defects can also lead to genomic instability through telomere fusions or recombination. Thus, as shown in both model systems and in humans, defects in telomere biology are implicated in cellular and organismal aging as well as in tumorigenesis. Bone marrow failure and malignancy are 2 life-threatening disease manifestations in the inherited telomere biology disorder dyskeratosis congenita. We provide an overview of basic telomere structure and maintenance. We outline the telomere biology defects observed in dyskeratosis congenita, focusing on recent discoveries in this field. Last, we review the evidence of how telomere biology may impact sporadic aplastic anemia and the risk for various cancers. Copyright © 2013 Mosby, Inc. All rights reserved.

  15. Decreasing initial telomere length in humans intergenerationally understates age-associated telomere shortening

    PubMed Central

    Holohan, Brody; De Meyer, Tim; Batten, Kimberly; Mangino, Massimo; Hunt, Steven C; Bekaert, Sofie; De Buyzere, Marc L; Rietzschel, Ernst R; Spector, Tim D; Wright, Woodring E; Shay, Jerry W

    2015-01-01

    Telomere length shortens with aging, and short telomeres have been linked to a wide variety of pathologies. Previous studies suggested a discrepancy in age-associated telomere shortening rate estimated by cross-sectional studies versus the rate measured in longitudinal studies, indicating a potential bias in cross-sectional estimates. Intergenerational changes in initial telomere length, such as that predicted by the previously described effect of a father’s age at birth of his offspring (FAB), could explain the discrepancy in shortening rate measurements. We evaluated whether changes occur in initial telomere length over multiple generations in three large datasets and identified paternal birth year (PBY) as a variable that reconciles the difference between longitudinal and cross-sectional measurements. We also clarify the association between FAB and offspring telomere length, demonstrating that this effect is substantially larger than reported in the past. These results indicate the presence of a downward secular trend in telomere length at birth over generational time with potential public health implications. PMID:25952108

  16. The long and short of it: the role of telomeres in fetal origins of adult disease.

    PubMed

    Hallows, Stephanie E; Regnault, Timothy R H; Betts, Dean H

    2012-01-01

    Placental insufficiency, maternal malnutrition, and other causes of intrauterine growth restriction (IUGR) can significantly affect short-term growth and long-term health. Following IUGR, there is an increased risk for cardiovascular disease and Type 2 Diabetes. The etiology of these diseases is beginning to be elucidated, and premature aging or cellular senescence through increased oxidative stress and DNA damage to telomeric ends may be initiators of these disease processes. This paper will explore the areas where telomere and telomerase biology can have significant effects on various tissues in the body in IUGR outcomes.

  17. Genomic Instability and Telomere Fusion of Canine Osteosarcoma Cells

    PubMed Central

    Maeda, Junko; Yurkon, Charles R.; Fujisawa, Hiroshi; Kaneko, Masami; Genet, Stefan C.; Roybal, Erica J.; Rota, Garrett W.; Saffer, Ethan R.; Rose, Barbara J.; Hanneman, William H.; Thamm, Douglas H.; Kato, Takamitsu A.

    2012-01-01

    Canine osteosarcoma (OSA) is known to present with highly variable and chaotic karyotypes, including hypodiploidy, hyperdiploidy, and increased numbers of metacentric chromosomes. The spectrum of genomic instabilities in canine OSA has significantly augmented the difficulty in clearly defining the biological and clinical significance of the observed cytogenetic abnormalities. In this study, eight canine OSA cell lines were used to investigate telomere fusions by fluorescence in situ hybridization (FISH) using a peptide nucleotide acid probe. We characterized each cell line by classical cytogenetic studies and cellular phenotypes including telomere associated factors and then evaluated correlations from this data. All eight canine OSA cell lines displayed increased abnormal metacentric chromosomes and exhibited numerous telomere fusions and interstitial telomeric signals. Also, as evidence of unstable telomeres, colocalization of γ-H2AX and telomere signals in interphase cells was observed. Each cell line was characterized by a combination of data representing cellular doubling time, DNA content, chromosome number, metacentric chromosome frequency, telomere signal level, cellular radiosensitivity, and DNA-PKcs protein expression level. We have also studied primary cultures from 10 spontaneous canine OSAs. Based on the observation of telomere aberrations in those primary cell cultures, we are reasonably certain that our observations in cell lines are not an artifact of prolonged culture. A correlation between telomere fusions and the other characteristics analyzed in our study could not be identified. However, it is important to note that all of the canine OSA samples exhibiting telomere fusion utilized in our study were telomerase positive. Pending further research regarding telomerase negative canine OSA cell lines, our findings may suggest telomere fusions can potentially serve as a novel marker for canine OSA. PMID:22916246

  18. E-type cyclins modulate telomere integrity in mammalian male meiosis.

    PubMed

    Manterola, Marcia; Sicinski, Piotr; Wolgemuth, Debra J

    2016-06-01

    We have shown that E-type cyclins are key regulators of mammalian male meiosis. Depletion of cyclin E2 reduced fertility in male mice due to meiotic defects, involving abnormal pairing and synapsis, unrepaired DNA, and loss of telomere structure. These defects were exacerbated by additional loss of cyclin E1, and complete absence of both E-type cyclins produces a meiotic catastrophe. Here, we investigated the involvement of E-type cyclins in maintaining telomere integrity in male meiosis. Spermatocytes lacking cyclin E2 and one E1 allele (E1+/-E2-/-) displayed a high rate of telomere abnormalities but can progress to pachytene and diplotene stages. We show that their telomeres exhibited an aberrant DNA damage repair response during pachynema and that the shelterin complex proteins TRF2 and RAP2 were significantly decreased in the proximal telomeres. Moreover, the insufficient level of these proteins correlated with an increase of γ-H2AX foci in the affected telomeres and resulted in telomere associations involving TRF1 and telomere detachment in later prophase-I stages. These results suggest that E-type cyclins are key modulators of telomere integrity during meiosis by, at least in part, maintaining the balance of shelterin complex proteins, and uncover a novel role of E-type cyclins in regulating chromosome structure during male meiosis.

  19. Recombinogenic Telomeres in Diploid Sorex granarius (Soricidae, Eulipotyphla) Fibroblast Cells

    PubMed Central

    Draskovic, I.; Minina, J. M.; Karamysheva, T. V.; Novo, C. L.; Liu, W.-Y.; Porreca, R. M.; Gibaud, A.; Zvereva, M. E.; Skvortsov, D. A.; Rubtsov, N. B.

    2014-01-01

    The telomere structure in the Iberian shrew Sorex granarius is characterized by unique, striking features, with short arms of acrocentric chromosomes carrying extremely long telomeres (up to 300 kb) with interspersed ribosomal DNA (rDNA) repeat blocks. In this work, we investigated the telomere physiology of S. granarius fibroblast cells and found that telomere repeats are transcribed on both strands and that there is no telomere-dependent senescence mechanism. Although telomerase activity is detectable throughout cell culture and appears to act on both short and long telomeres, we also discovered that signatures of a recombinogenic activity are omnipresent, including telomere-sister chromatid exchanges, formation of alternative lengthening of telomeres (ALT)-associated PML-like bodies, production of telomere circles, and a high frequency of telomeres carrying marks of a DNA damage response. Our results suggest that recombination participates in the maintenance of the very long telomeres in normal S. granarius fibroblasts. We discuss the possible interplay between the interspersed telomere and rDNA repeats in the stabilization of the very long telomeres in this organism. PMID:24842907

  20. Telomere Length Determines TERRA and R-Loop Regulation through the Cell Cycle.

    PubMed

    Graf, Marco; Bonetti, Diego; Lockhart, Arianna; Serhal, Kamar; Kellner, Vanessa; Maicher, André; Jolivet, Pascale; Teixeira, Maria Teresa; Luke, Brian

    2017-06-29

    Maintenance of a minimal telomere length is essential to prevent cellular senescence. When critically short telomeres arise in the absence of telomerase, they can be repaired by homology-directed repair (HDR) to prevent premature senescence onset. It is unclear why specifically the shortest telomeres are targeted for HDR. We demonstrate that the non-coding RNA TERRA accumulates as HDR-promoting RNA-DNA hybrids (R-loops) preferentially at very short telomeres. The increased level of TERRA and R-loops, exclusively at short telomeres, is due to a local defect in RNA degradation by the Rat1 and RNase H2 nucleases, respectively. Consequently, the coordination of TERRA degradation with telomere replication is altered at shortened telomeres. R-loop persistence at short telomeres contributes to activation of the DNA damage response (DDR) and promotes recruitment of the Rad51 recombinase. Thus, the telomere length-dependent regulation of TERRA and TERRA R-loops is a critical determinant of the rate of replicative senescence. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Extreme Telomere Length Dimorphism in the Tasmanian Devil and Related Marsupials Suggests Parental Control of Telomere Length

    PubMed Central

    Bender, Hannah S.; Murchison, Elizabeth P.; Pickett, Hilda A.; Deakin, Janine E.; Strong, Margaret A.; Conlan, Carly; McMillan, Daniel A.; Neumann, Axel A.; Greider, Carol W.; Hannon, Gregory J.; Reddel, Roger R.; Graves, Jennifer A. Marshall.

    2012-01-01

    Telomeres, specialised structures that protect chromosome ends, play a critical role in preserving chromosome integrity. Telomere dynamics in the Tasmanian devil (Sarcophilus harrisii) are of particular interest in light of the emergence of devil facial tumour disease (DFTD), a transmissible malignancy that causes rapid mortality and threatens the species with extinction. We used fluorescent in situ hybridisation to investigate telomere length in DFTD cells, in healthy Tasmanian devils and in four closely related marsupial species. Here we report that animals in the Order Dasyuromorphia have chromosomes characterised by striking telomere length dimorphism between homologues. Findings in sex chromosomes suggest that telomere length dimorphism may be regulated by events in the parental germlines. Long telomeres on the Y chromosome imply that telomere lengthening occurs during spermatogenesis, whereas telomere diminution occurs during oogenesis. Although found in several somatic cell tissue types, telomere length dimorphism was not found in DFTD cancer cells, which are characterised by uniformly short telomeres. This is, to our knowledge, the first report of naturally occurring telomere length dimorphism in any species and suggests a novel strategy of telomere length control. Comparative studies in five distantly related marsupials and a monotreme indicate that telomere dimorphism evolved at least 50 million years ago. PMID:23049977

  2. An increase in telomere sister chromatid exchange in murine embryonic stem cells possessing critically shortened telomeres

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yisong; Giannone, Richard J; Wu, Jun

    Telomerase deficiency leads to a progressive loss of telomeric DNA that eventually triggers cell apoptosis in human primary cells during prolonged growth in culture. Rare survivors can maintain telomere length through either activation of telomerase or recombination-based telomere lengthening, and thus proliferate indefinitely. We have explored the possibility that telomeres may be maintained through telomere sister chromatid exchange (T-SCE) in murine telomere reverse transcriptase-deficient (mTert -/-) splenocytes and ES cells. Because telomerase deficiency leads to gradual loss of telomeric DNA in mTert -/- splenocytes and ES cells and eventually to chromosomes with telomere signal-free ends (SFEs), we examined these cellmore » types for evidence of sister chromatid exchange at telomeres, and observed an increase in T-SCEs only in a subset of mTert -/- splenocytes or ES cells that possessed multiple SFEs. Furthermore, T-SCEs were more often detected in ES cells than in splenocytes that harbored a similar frequency of SFEs. In mTert heterozygous (mTert +/-) ES cells or splenocytes, which are known to exhibit a decrease in average telomere length but no SFEs, no increase in T-SCE was observed. In addition to T-SCE, other genomic rearrangements (i.e., SCE) were also significantly increased in mTert -/- ES cells possessing critically short telomeres, but not in splenocytes. Our results suggest that animals and cell culture differ in their ability to carry out genomic rearrangements as a means of maintaining telomere integrity when telomeres become critically shortened.« less

  3. The role of telomeres and telomerase complex in haematological neoplasia: the length of telomeres as a marker of carcinogenesis and prognosis of disease.

    PubMed

    Gancarcíková, M; Zemanová, Z; Brezinová, J; Berková, A; Vcelíková, S; Smigová, J; Michalová, K

    2010-01-01

    Human telomeres (discovery of telomere structure and function has been recently awarded The Nobel Prize) consist of approximately 5-12 kb of tandem repeated sequences (TTAGGG)n and associated proteins capping chromosome ends which prevent degradation, loss of genetic information, end-to-end fusion, senescence and apoptosis. Due to the end-replication problem, telomere repeats are lost with each cell division, eventually leading to genetic instability and cellular senescence when telomeres become critically short. Stabilization of the telomeric DNA through telomerase activation, unique reverse transcriptase, or activation of the alternative mechanism of telomere maintenance is essential if the cells are to survive and proliferate indefinitely. Telomerase is expressed during early development and remains fully active in specific germline cells, but is undetectable in most normal somatic cells. High level of telomerase activity is detected in almost 90% of human tumours and immortalized cell lines. The hematopoietic compartment may develop genetic instability as a consequence of telomere erosion, resulting in aplastic anaemia (AA) and increased risk of myelodysplastic syndrome (MDS) and acute myeloid leukaemia (AML). Genetic instability associated with telomere dysfunction (i.e. short telomeres) is an early event in carcinogenesis. The molecular cytogenetic method telomere/centromere fluorescence in situ hybridization (T/C-FISH) can be used to characterize the telomere length of hematopoietic cells. This review describes recent advances in the molecular characterization of telomere system, the regulation of telomerase activity in cancer pathogenesis and shows that the telomeric length could be a potential clinical marker of hematologic neoplasia and prognosis of disease.

  4. Telomere Dysfunction Induced Foci (TIF) Analysis.

    PubMed

    Mender, Ilgen; Shay, Jerry W

    2015-11-20

    Telomerase maintains telomeric DNA in eukaryotes during early developments, ~90% of cancer cells and some proliferative stem like cells. Telomeric repeats at the end of chromosomes are associated with the shelterin complex. This complex consists of TRF1, TRF2, Rap1, TIN2, TPP1, POT1 which protect DNA from being recognized as DNA double-stranded breaks. Critically short telomeres or impaired shelterin proteins can cause telomere dysfunction, which eventually induces DNA damage responses at the telomeres. DNA damage responses can be identified by antibodies to 53BP1, gammaH2AX, Rad17, ATM, and Mre11. DNA damage foci at uncapped telomeres are referred to as Telomere dysfunction-Induced Foci (TIFs) (de Lange, 2005; Takai et al. , 2003). The TIF assay is based on the co-localization detection of DNA damage by an antibody against DNA damage markers, such as gamma-H2AX, and telomeres using an antibody against one of the shelterin proteins such as TRF2 (Takai et al. , 2003; de Lange, 2002; Karlseder et al. , 1999). The method we describe here can be used in normal human and cancer cells. Other commonly used methods-Telomere Restriction Fragment (TRF) Analysis (Mender and Shay, 2015b) and Telomere Repeat Amplification Protocol (TRAP) (Mender and Shay, 2015a)- in telomere biology can be found by clicking on the indicated links.

  5. Cancer telomeres and white crows.

    PubMed

    Meeker, Alan K

    2018-01-01

    This mini-review article discusses past and present prostate-focused research on telomere and telomerase biology conducted at Johns Hopkins, through the eyes of a Donald S Coffey trainee. Included are past discoveries of abnormalities in telomere biology in the context of prostate cancer and its pre-malignant precursor prostatic intraepithelial neoplasia (PIN); the finding that telomerase activity is androgen-regulated in the prostate, and the potential role of telomerase in prostate epithelial stem cells. Also reviewed are more recent results showing that in situ telomere length measurements in patient tissue specimens may have utility in risk assessment and as a prognostic biomarker. Highlighted throughout the article are some of the training and mentorship approaches employed by the late Dr. Coffey, former Director of Urologic Research at the Brady Urological Research Institute, which inspired new research ideas, team science, and discovery.

  6. Telomere biology: Rationale for diagnostics and therapeutics in cancer.

    PubMed

    Rousseau, Philippe; Autexier, Chantal

    2015-01-01

    The key step of carcinogenesis is the malignant transformation which is fundamentally a telomere biology dysfunction permitting cells to bypass the Hayflick limit and to divide indefinitely and uncontrollably. Thus all partners and structures involved in normal and abnormal telomere maintenance, protection and lengthening can be considered as potential anti-cancer therapeutic targets. In this Point of View we discuss, highlight and provide new perspectives from the current knowledge and understanding to position the different aspects of telomere biology and dysfunction as diagnostic, preventive and curative tools in the field of cancer.

  7. Telomere biology: Rationale for diagnostics and therapeutics in cancer

    PubMed Central

    Rousseau, Philippe; Autexier, Chantal

    2015-01-01

    The key step of carcinogenesis is the malignant transformation which is fundamentally a telomere biology dysfunction permitting cells to bypass the Hayflick limit and to divide indefinitely and uncontrollably. Thus all partners and structures involved in normal and abnormal telomere maintenance, protection and lengthening can be considered as potential anti-cancer therapeutic targets. In this Point of View we discuss, highlight and provide new perspectives from the current knowledge and understanding to position the different aspects of telomere biology and dysfunction as diagnostic, preventive and curative tools in the field of cancer. PMID:26291128

  8. Telomere erosion in NF1 tumorigenesis.

    PubMed

    Jones, Rhiannon E; Grimstead, Julia W; Sedani, Ashni; Baird, Duncan; Upadhyaya, Meena

    2017-06-20

    Neurofibromatosis type 1 (NF1; MIM# 162200) is a familial cancer syndrome that affects 1 in 3,500 individuals worldwide and is inherited in an autosomal dominant fashion. Malignant Peripheral Nerve Sheath Tumors (MPNSTs) represent a significant cause of morbidity and mortality in NF1 and currently there is no treatment or definite prognostic biomarkers for these tumors. Telomere shortening has been documented in numerous tumor types. Short dysfunctional telomeres are capable of fusion and it is considered that the ensuing genomic instability may facilitate clonal evolution and the progression to malignancy. To evaluate the potential role of telomere dysfunction in NF1-associated tumors, we undertook a comparative analysis of telomere length in samples derived from 10 cutaneous and 10 diffused plexiform neurofibromas, and 19 MPNSTs. Telomere length was determined using high-resolution Single Telomere Length Analysis (STELA). The mean Xp/Yp telomere length detected in MPNSTs, at 3.282 kb, was significantly shorter than that observed in both plexiform neurofibromas (5.793 kb; [p = 0.0006]) and cutaneous neurofibromas (6.141 kb; [p = 0.0007]). The telomere length distributions of MPNSTs were within the length-ranges in which telomere fusion is detected and that confer a poor prognosis in other tumor types. These data indicate that telomere length may play a role in driving genomic instability and clonal progression in NF1-associated MPNSTs.

  9. Maintenance of telomere length in AML.

    PubMed

    Lansdorp, Peter M

    2017-11-28

    The importance of telomere length to human health, aging, and cancer continues to be underappreciated. This review examines some basics of telomere biology and relates how telomere function, telomerase activity, and mutations in TERC or TERT are involved in bone marrow failure, leukemias, and other cancers. Given the challenge to obtain accurate data on telomerase activity and telomere length in specific cell types, the situation in acute myeloid leukemia (AML) remains puzzling. In most cancers, telomerase levels are increased after cells have encountered a "telomere crisis," which is typically associated with poor prognosis. Cells emerging from "telomere crisis" have defective DNA damage responses, resulting, for example, from loss of p53. Such cells often express elevated telomerase levels as a result of point mutations in the TERT promoter or amplification of the TERT gene. While telomeres in AML blasts are typically shorter than expected for normal leukocytes, most AML cells do not show evidence of having gone through a "telomere crisis." In chronic myeloid leukemia (CML), the difference between the telomere length in nonmalignant T cells and malignant blasts from the same patient was found to correlate with the remaining duration of the chronic phase. This observation supports that a mitotic clock is ticking in CML stem cells and that disease progression in CML heralds the onset of a "telomere crisis." The presence of very short telomeres in tumor cells was found to predict disease progression in chronic lymphocytic leukemia, myeloma, and various solid tumors. In view of these findings longitudinal studies of telomere length in AML appear worthwhile.

  10. The influence of the telomere-telomerase system on diabetes mellitus and its vascular complications.

    PubMed

    Qi Nan, Wu; Ling, Zhang; Bing, Chen

    2015-06-01

    The telomere-telomerase system plays an important role in the pathogenesis and disease progression of diabetes mellitus as well as in its vascular complications. Recent studies suggest that telomere shortening and abnormal telomerase activity occur in patients with diabetes mellitus, and targeting the telomere-telomerase system has become a prospective treatment for diabetes mellitus and its vascular complications. This review highlights the significance of the telomere-telomerase system and supports its role as a possible therapeutic target for patients with diabetes mellitus and its vascular complications Areas covered: This review covers the advances in understanding the telomere-telomerase system over the last 30 years and its significance in diabetes mellitus. In addition, it provides knowledge regarding the significance of the telomere-telomerase system in diabetes mellitus and its vascular complications as well as its role and mechanisms in oxidative stress, cell therapy and antioxidant activity Expert opinion: The telomere-telomerase system may be a potential therapeutic target that can protect against DNA damage and apoptosis in patients with diabetes mellitus and its vascular complications. DNA damage and apoptosis are associated with oxidative stress and are involved in the dysfunction of pancreatic β cells, insulin resistance, and its vascular complications. Abnormalities in the telomere-telomerase system may be associated with diabetes mellitus and its vascular complications. Therapies targeting telomere-telomerase system, telomerase reverse transcriptase transfection and alterative telomere lengthening must be identified before gene therapy can commence.

  11. Significantly lengthened telomere in granulosa cells from women with polycystic ovarian syndrome (PCOS).

    PubMed

    Wei, Duo; Xie, Juanke; Yin, Baoli; Hao, Haoying; Song, Xiaobing; Liu, Qi; Zhang, Cuilian; Sun, Yingpu

    2017-07-01

    Polycystic ovary syndrome (PCOS) is the most common endocrinopathy among women at reproductive age. However, its etiology remains poorly understood. Recent studies indicated that telomere length was related to PCOS. However, the association between telomere length and PCOS has only been shown in leucocytes and remained controversial across different studies. To clarify the association between telomere length and PCOS, the current study interrogated telomere length not only in leucocytes, but also in follicular granulosa cells, which is essential for folliculogenesis and steroidogenesis. Seventy-five patients with PCOS and 81 controls with mechanical infertility undergoing their first in vitro fertilization cycle were enrolled. Their peripheral blood and granulosa cells were collected on the oocyte retrieval day. Telomere length of both leucocytes in the blood and granulosa cells was assayed by quantitative polymerase chain reaction. No significant difference was found in the leucocyte telomere length between controls and PCOS patients (0.99 ± 0.44 vs. 1.00 ± 0.38, p = 0.93). Interestingly, when comparing telomere length in granulosa cells between controls and PCOS subjects, significantly lengthened telomere length was found in PCOS subjects (1.00 ± 0.37 vs. 1.57±0.67, p < 0.0001). After adjustments for age and body mass index, the p value remained significant (p < 0.0001). This finding reinforced the association between telomere abnormalities and PCOS. Given the importance of telomere length in cellular proliferation, our findings provided novel insights into the pathophysiology of PCOS that abnormalities in telomere length possibly disturb folliculogenesis and subsequently result in PCOS.

  12. High-throughput single-molecule telomere characterization.

    PubMed

    McCaffrey, Jennifer; Young, Eleanor; Lassahn, Katy; Sibert, Justin; Pastor, Steven; Riethman, Harold; Xiao, Ming

    2017-11-01

    We have developed a novel method that enables global subtelomere and haplotype-resolved analysis of telomere lengths at the single-molecule level. An in vitro CRISPR/Cas9 RNA-directed nickase system directs the specific labeling of human (TTAGGG)n DNA tracts in genomes that have also been barcoded using a separate nickase enzyme that recognizes a 7-bp motif genome-wide. High-throughput imaging and analysis of large DNA single molecules from genomes labeled in this fashion using a nanochannel array system permits mapping through subtelomere repeat element (SRE) regions to unique chromosomal DNA while simultaneously measuring the (TTAGGG)n tract length at the end of each large telomere-terminal DNA segment. The methodology also permits subtelomere and haplotype-resolved analyses of SRE organization and variation, providing a window into the population dynamics and potential functions of these complex and structurally variant telomere-adjacent DNA regions. At its current stage of development, the assay can be used to identify and characterize telomere length distributions of 30-35 discrete telomeres simultaneously and accurately. The assay's utility is demonstrated using early versus late passage and senescent human diploid fibroblasts, documenting the anticipated telomere attrition on a global telomere-by-telomere basis as well as identifying subtelomere-specific biases for critically short telomeres. Similarly, we present the first global single-telomere-resolved analyses of two cancer cell lines. © 2017 McCaffrey et al.; Published by Cold Spring Harbor Laboratory Press.

  13. Dietary restriction ameliorates haematopoietic ageing independent of telomerase, whilst lack of telomerase and short telomeres exacerbates the ageing phenotype.

    PubMed

    Al-Ajmi, Nouf; Saretzki, Gabriele; Miles, Colin; Spyridopoulos, Ioakim

    2014-10-01

    Ageing is associated with an overall decline in the functional capacity of tissues and stem cells, including haematopoietic stem and progenitor cells (HSPCs), as well as telomere dysfunction. Dietary restriction (DR) is a recognised anti-ageing intervention that extends lifespan and improves health in several organisms. To investigate the role of telomeres and telomerase in haematopoietic ageing, we compared the HSPC profile and clonogenic capacity of bone marrow cells from wild type with telomerase-deficient mice and the effect of DR on these parameters. Compared with young mice, aged wild type mice demonstrated a significant accumulation of HSPCs (1.3% vs 0.2%, P=0.002) and elevated numbers of granulocyte/macrophage colony forming units (CFU-GM, 26.4 vs 17.3, P=0.0037) consistent with myeloid "skewing" of haematopoiesis. DR was able to restrict the increase in HSPC number as well as the myeloid "skewing" in aged wild type mice. In order to analyse the influence of short telomeres on the ageing phenotype we examined mice lacking the RNA template for telomerase, TERC(-/-). Telomere shortening resulted in a similar bone marrow phenotype to that seen in aged mice, with significantly increased HSPC numbers and an increased formation of all myeloid colony types but at a younger age than wild type mice. However, an additional increase in erythroid colonies (BFU-E) was also evident. Mice lacking telomerase reverse transcriptase without shortened telomeres, TERT(-/-), also presented with augmented haematopoietic ageing which was ameliorated by DR, demonstrating that the effect of DR was not dependent on the presence of telomerase in HSPCs. We conclude that whilst shortened telomeres mimic some aspects of haematopoietic ageing, both shortened telomeres and the lack of telomerase produce specific phenotypes, some of which can be prevented by dietary restriction. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. Telomere dynamics in an immortal human cell line.

    PubMed Central

    Murnane, J P; Sabatier, L; Marder, B A; Morgan, W F

    1994-01-01

    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. Images PMID:7957062

  15. The role of telomeres in Etoposide induced tumor cell death.

    PubMed

    Jeyapalan, Jessie; Leake, Alan; Ahmed, Shaheda; Saretzki, Gabriele; Tilby, Michael; von Zglinicki, Thomas

    2004-09-01

    Etoposide, a topoisomerase II poison is used in the treatment of a number of solid tumors. Contradictory data exist on the role of the telomere/telomerase complex in etoposide induced apoptosis. Therefore we examined the effects of etoposide treatment in the neuroblastoma cell line SHSY5Y, with very short telomeres and the acute lymphoblastic T cell line 1301, which displays extremely long telomeres. Both short-term and continuous exposure to the drug were examined. Etoposide induced widespread DNA damage followed by DNA damage foci formation and ultimately growth arrest and apoptosis in a concentration-dependent manner. However, length of telomeres and of single stranded telomeric G rich overhangs did not change significantly under the treatments in any cell line. There was no significant induction of single-strand breaks in the G-rich strand of telomeres. Telomerase activity was transiently upregulated under low concentrations of etoposide, while high concentrations resulted in decreased telomerase activity only after onset of apoptosis. Telomerase overexpression protected against etoposide induced apoptosis in fibroblasts. The data suggest that telomeres are not major signal transducers towards growth arrest or apoptosis after etoposide treatment. However, upregulation of telomerase might be part of an attempted adaptative response, which protects cells by a mechanism that might be independent of telomere length maintenance.

  16. Strand exchange of telomeric DNA catalyzed by the Werner syndrome protein (WRN) is specifically stimulated by TRF2

    PubMed Central

    Edwards, Deanna N.; Orren, David K.; Machwe, Amrita

    2014-01-01

    Werner syndrome (WS), caused by loss of function of the RecQ helicase WRN, is a hereditary disease characterized by premature aging and elevated cancer incidence. WRN has DNA binding, exonuclease, ATPase, helicase and strand annealing activities, suggesting possible roles in recombination-related processes. Evidence indicates that WRN deficiency causes telomeric abnormalities that likely underlie early onset of aging phenotypes in WS. Furthermore, TRF2, a protein essential for telomere protection, interacts with WRN and influences its basic helicase and exonuclease activities. However, these studies provided little insight into WRN's specific function at telomeres. Here, we explored the possibility that WRN and TRF2 cooperate during telomeric recombination processes. Our results indicate that TRF2, through its interactions with both WRN and telomeric DNA, stimulates WRN-mediated strand exchange specifically between telomeric substrates; TRF2's basic domain is particularly important for this stimulation. Although TRF1 binds telomeric DNA with similar affinity, it has minimal effects on WRN-mediated strand exchange of telomeric DNA. Moreover, TRF2 is displaced from telomeric DNA by WRN, independent of its ATPase and helicase activities. Together, these results suggest that TRF2 and WRN act coordinately during telomeric recombination processes, consistent with certain telomeric abnormalities associated with alteration of WRN function. PMID:24880691

  17. Telomere length regulation during cloning, embryogenesis and ageing.

    PubMed

    Schaetzlein, S; Rudolph, K L

    2005-01-01

    Telomeres are nucleoprotein complexes at the end of eukaryotic chromosomes with an essential role in chromosome capping. Owing to the end-replication problem of DNA polymerase, telomeres shorten during each cell division. When telomeres become critically short, they loose their capping function, which in turn induces a DNA damage-like response. This mechanism inhibits cell proliferation at the senescence stage and there is evidence that it limits the regenerative capacity of tissues and organs during chronic diseases and ageing. The holoenzyme telomerase synthesises telomeric DNA de novo, but, in humans, it is active only during embryogenesis, in immature germ cells and in a subset of stem/progenitor cells during postnatal life. Telomere length can be maintained or increased by telomerase, a process that appears to be regulated by a variety of telomere-binding proteins that control telomerase recruitment and activity at the telomeres. During embryogenesis, telomerase is strongly activated at the morula/blastocyst transition. At this transition, telomeres are significantly elongated in murine and bovine embryos. Early embryonic telomere elongation is telomerase dependent and leads to a rejuvenation of telomeres in cloned bovine embryos. Understanding of the molecular mechanisms underlying this early embryonic telomere elongation programme is of great interest for medical research in the fields of regeneration, cell therapies and therapeutic cloning.

  18. TERRA Promotes Telomere Shortening through Exonuclease 1–Mediated Resection of Chromosome Ends

    PubMed Central

    Pfeiffer, Verena; Lingner, Joachim

    2012-01-01

    The long noncoding telomeric repeat containing RNA (TERRA) is expressed at chromosome ends. TERRA upregulation upon experimental manipulation or in ICF (immunodeficiency, centromeric instability, facial anomalies) patients correlates with short telomeres. To study the mechanism of telomere length control by TERRA in Saccharomyces cerevisiae, we mapped the transcriptional start site of TERRA at telomere 1L and inserted a doxycycline regulatable promoter upstream. Induction of TERRA transcription led to telomere shortening of 1L but not of other chromosome ends. TERRA interacts with the Exo1-inhibiting Ku70/80 complex, and deletion of EXO1 but not MRE11 fully suppressed the TERRA–mediated short telomere phenotype in presence and absence of telomerase. Thus TERRA transcription facilitates the 5′-3′ nuclease activity of Exo1 at chromosome ends, providing a means to regulate the telomere shortening rate. Thereby, telomere transcription can regulate cellular lifespan through modulation of chromosome end processing activities. PMID:22719262

  19. Telomere sister chromatid exchange in telomerase deficient murine cells.

    PubMed

    Wang, Yisong; Giannone, Richard J; Liu, Yie

    2005-10-01

    We have recently demonstrated that several types of genomic rearrangements (i.e., telomere sister chromatid exchange (T-SCE), genomic-SCE, or end-to-end fusions) were more often detected in long-term cultured murine telomerase deficient embryonic stem (ES) cells than in freshly prepared murine splenocytes, even through they possessed similar frequencies of critically short telomeres. The high rate of genomic rearrangements in telomerase deficient ES cells, when compared to murine splenocytes, may reflect the cultured cells' gained ability to protect chromosome ends with eroded telomeres allowing them to escape "end crisis". However, the possibility that ES cells were more permissive to genomic rearrangements than other cell types or that differences in the microenvironment or genetic background of the animals might consequentially determine the rate of T-SCEs or other genomic rearrangements at critically short telomeres could not be ruled out.

  20. Telomere shortening triggers a feedback loop to enhance end protection.

    PubMed

    Yang, Chia-Wei; Tseng, Shun-Fu; Yu, Chia-Jung; Chung, Chia-Yu; Chang, Cheng-Yen; Pobiega, Sabrina; Teng, Shu-Chun

    2017-08-21

    Telomere homeostasis is controlled by both telomerase machinery and end protection. Telomere shortening induces DNA damage sensing kinases ATM/ATR for telomerase recruitment. Yet, whether telomere shortening also governs end protection is poorly understood. Here we discover that yeast ATM/ATR controls end protection. Rap1 is phosphorylated by Tel1 and Mec1 kinases at serine 731, and this regulation is stimulated by DNA damage and telomere shortening. Compromised Rap1 phosphorylation hampers the interaction between Rap1 and its interacting partner Rif1, which thereby disturbs the end protection. As expected, reduction of Rap1-Rif1 association impairs telomere length regulation and increases telomere-telomere recombination. These results indicate that ATM/ATR DNA damage checkpoint signal contributes to telomere protection by strengthening the Rap1-Rif1 interaction at short telomeres, and the checkpoint signal oversees both telomerase recruitment and end capping pathways to maintain telomere homeostasis. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  1. Telomere Shortening and Associated Chromosomal Instability in Peripheral Blood Lymphocytes of Patients With Hodgkin's Lymphoma Prior to Any Treatment Are Predictive of Second Cancers

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    M'kacher, Radhia; Bennaceur-Griscelli, Annelise; Girinsky, Theodore

    Purpose: To investigate a potential link between telomere length, chromosomal instability, and the advent of a second cancer (SC) in patients with Hodgkin's lymphoma (HL), who are known to be at risk for SCs. This study was premised on the finding that telomere dysfunction and DNA repair pathways were related to many pathologic conditions. Methods and Materials: Three cohorts of patients with HL were studied: 73 who were prospectively followed >5 years after diagnosis (prospective HL cohort), 28 who developed a SC (SC HL cohort), and 18 long-term survivors with no evidence of disease or complication since their initial treatmentmore » (NED HL cohort). Telomere length was analyzed by a telomeric restriction fragment assay in peripheral blood lymphocytes. Thirty healthy donors and 70 patients with a newly diagnosed solid tumor were the control population. Results: Compared with controls, patients from the prospective HL cohort, before any treatment, showed age-independent shorter telomeres (mean, 8.3 vs. 11.7 kb in healthy donors; <6 kb in 18% in HL patients), increased spontaneous chromosomal abnormalities, and increased in vitro radiation sensitivity (p < 10{sup -4} each). After treatment, telomere shortening was associated with cytogenetic profiles characterized by the persistence of complex chromosomal rearrangement and clonal aberrations. Moreover, the two cases of SC in the prospective HL patients had short telomeres and CCR initially. In addition, the SC HL cohort was characterized by markedly short telomeres (6.6 vs. 9.7 kb in the NED HL cohort), the presence of complex chromosome rearrangements, and increased in vitro radiation sensitivity. Conclusions: An intimate relationship between pre-treatment telomere shortening, chromosomal instability, radiation sensitivity and occurrence of SC was found in HL patients.« less

  2. Role of arterial telomere dysfunction in hypertension: relative contributions of telomere shortening and telomere uncapping.

    PubMed

    Morgan, R Garrett; Ives, Stephen J; Walker, Ashley E; Cawthon, Richard M; Andtbacka, Robert H I; Noyes, Dirk; Lesniewski, Lisa A; Richardson, Russell S; Donato, Anthony J

    2014-06-01

    Telomere shortening in arteries could lead to telomere uncapping and cellular senescence, which in turn could promote the development of hypertension. To assess the novel role of arterial telomere dysfunction in hypertension, we compared mean telomere length (qPCR), telomere uncapping (serine 139 phosphorylated histone γ-H2A.X (γ-H2) localized to telomeres: ChIP), and tumor suppressor protein p53 (P53)/cyclin-dependent kinase inhibitor 1A (P21)-induced senescence (P53 bound to P21 gene promoter: ChIP) in arteries from 55 age-matched hypertensive and nonhypertensive individuals. Arterial mean telomere length was not different in hypertensive patients compared with nonhypertensive individuals (P = 0.29). Arterial telomere uncapping and P53/P21-induced senescence were two-fold greater in hypertensive patients compared with nonhypertensive individuals (P = 0.04 and P = 0.02, respectively). Arterial mean telomere length was not associated with telomere uncapping or P53/P21-induced senescence (r = -0.02, P = 0.44 and r = 0.01, P = 0.50, respectively), but telomere uncapping was a highly influential covariate for the hypertension group difference in P53/P21-induced senescence (r = 0.62, P < 0.001, η(p)(2) = 0.35). Finally, telomere uncapping was a significant predictor of hypertension status (P = 0.03), whereas mean telomere length was not (P = 0.68). Collectively, these findings demonstrate that arterial telomere uncapping and P53/P21-induced senescence are linked to hypertension independently of mean telomere length, and telomere uncapping influences hypertension status more than mean telomere length.

  3. Role of arterial telomere dysfunction in hypertension: relative contributions of telomere shortening and telomere uncapping

    PubMed Central

    Morgan, R. Garrett; Ives, Stephen J.; Walker, Ashley E.; Cawthon, Richard M.; Andtbacka, Robert H.I.; Noyes, Dirk; Lesniewski, Lisa A.; Richardson, Russell S.; Donato, Anthony J.

    2014-01-01

    Objective Telomere shortening in arteries could lead to telomere uncapping and cellular senescence, which in turn could promote the development of hypertension. Methods and results To assess the novel role of arterial telomere dysfunction in hypertension, we compared mean telomere length (qPCR), telomere uncapping (serine 139 phosphorylated histone γ-H2A.X (γ-H2) localized to telomeres: ChIP), and tumor suppressor protein p53 (P53)/cyclin-dependent kinase inhibitor 1A (P21)-induced senescence (P53 bound to P21 gene promoter: ChIP) in arteries from 55 age-matched hypertensive and nonhypertensive individuals. Arterial mean telomere length was not different in hypertensive patients compared with nonhypertensive individuals (P = 0.29). Arterial telomere uncapping and P53/P21- induced senescence were two-fold greater in hypertensive patients compared with nonhypertensive individuals (P = 0.04 and P = 0.02, respectively). Arterial mean telomere length was not associated with telomere uncapping or P53/P21-induced senescence (r=– 0.02, P = 0.44 and r = 0.01, P = 0.50, respectively), but telomere uncapping was a highly influential covariate for the hypertension group difference in P53/P21-induced senescence (r = 0.62, P < 0.001, ηp2 = 0.35). Finally, telomere uncapping was a significant predictor of hypertension status (P = 0.03), whereas mean telomere length was not (P = 0.68). Conclusion Collectively, these findings demonstrate that arterial telomere uncapping and P53/P21-induced senescence are linked to hypertension independently of mean telomere length, and telomere uncapping influences hypertension status more than mean telomere length. PMID:24686009

  4. Sub-fertile sperm cells exemplify telomere dysfunction.

    PubMed

    Biron-Shental, Tal; Wiser, Amir; Hershko-Klement, Anat; Markovitch, Ofer; Amiel, Aliza; Berkovitch, Arie

    2018-01-01

    The purpose of this study was to evaluate telomere homeostasis in sub-fertile compared to fertile human sperm. This observational, comparative study included 16 sub-fertile men who required intracytoplasmic sperm injection and 10 fertile men. At least 100 sperm cells from each participant were assessed. Main outcome measures were telomere length and telomere aggregates. Telomerase RNA component (TERC) copy number and telomere capture were assessed using fluorescence in situ hybridization technique and human telomerase reverse transcriptase (hTERT) using immunohistochemistry. Clinical backgrounds were similar. The percentage of sperm cells with shorter telomeres was higher among the sub-fertile compared to the fertile participants (3.3 ± 3.1 vs. 0.6 ± 1.2%, respectively; P < 0.005). The percentage of cells with telomere aggregates was significantly higher in the sub-fertile group (15.12 ± 3.73 vs. 4.73 ± 3.73%; P < 0.005). TERC gene copy number was similar between groups. The percentage of cells that were positive for hTERT was lower in the sub-fertile group (3.81 ± 1.27 vs. 8.42 ± 1.80%; P < 0.005). Telomere capture rates were higher among the sub-fertile sperm cells (P < 0.005). Sub-fertile sperm cells have short telomeres that are elongated by the alternative pathway of telomere capture. Dysfunctional telomeres may affect sperm fertilizability.

  5. Drosophila cell cycle under arrest: uncapped telomeres plead guilty.

    PubMed

    Cenci, Giovanni

    2009-04-01

    Telomeres are specialized structures that protect chromosome ends from degradation and fusion events. In most organisms, telomeres consist of short, repetitive G-rich sequences added to chromosome ends by a reverse transcriptase with an internal RNA template, called telomerase. Specific DNA-binding protein complexes associate with telomeric sequences preventing chromosome ends from being recognized as DNA double strand breaks (DSBs). Telomeres that lose their cap activate the DNA damage response (DDR) likewise DSBs and, if inappropriately repaired, generate telomeric fusions, which eventually lead to genome instability. In Drosophila there is not telomerase, and telomere length is maintained by transposition of three specialized retroelements. However, fly telomeres are protected by multi protein complexes like their yeast and vertebrate counterparts; these complexes bind chromosome ends in a sequence-independent fashion and are required to prevent checkpoint activation and end-to-end fusion. Uncapped Drosophila telomeres elicit a DDR just as dysfunctional human telomeres. Most interestingly, uncapped Drosophila telomeres also activate the spindle assembly checkpoint (SAC) by recruiting the SAC kinase BubR1. BubR1 accumulations at chromosome ends trigger the SAC that inhibits the metaphase-to-anaphase transition. These findings, reviewed here, highlight an intriguing and unsuspected connection between telomeres and cell cycle regulation, providing a clue to understand human telomere function.

  6. F19. TELOMERE SHORTENING IN YOUNG PEOPLE WITH FIRST EPISODE PSYCHOSIS: A 12-MONTH FOLLOW-UP STUDY

    PubMed Central

    Fraguas, David; Recio, Sandra; Diaz-Caneja, Covadonga M; Blasco, Maria A; Moisés, Ana Carolina; Arango, Celso

    2018-01-01

    Abstract Background Short telomere length is a biomarker of cell oxidation and aging. Patients with first-episode psychosis (FEP) have been reported to have shorter telomeres than healthy controls (HC), suggesting that there is a premature and accelerated cellular aging in FEP. However, there are not data on longitudinal changes of telomere length in people with FEP relative to HC. We present preliminary results on 1-year longitudinal changes in peripheral blood mononuclear cells (PBMCs) telomere length and the proportion of PBMCs with short telomeres in young people with FEP and HC. Methods 16 young patients with FEP (43.8% female, mean age 17.9 years) and 21 young HC (61.9% female, mean age 16.6 years) were enrolled in the study. PBMCs telomere length and the proportion of PBMCs with short telomeres (i.e. <3kb) were determined using high-throughput quantitative fluorescence in situ hybridization (HT Q-FISH) at baseline (16 patients with FEP and 21 HC) and 12-month follow-up (4 patients with FEP and 4 HC). Results At baseline, we did not find significant differences in telomere length nor in proportion of PBMCs with short telomeres between FEP patients and HC. During the one-year follow-up, we found a significantly greater loss of telomere length (p=0.019; explained variance=69.7%) and a non-significantly trend for greater increase in the proportion of PBMCs with short telomeres (p=0.097; explained variance=45.5%) in patients with FEP than in HC. Discussion Telomere length changes during the first years of the illness can represent an early marker of accelerated cellular aging in patients with first-episode psychosis.

  7. Telomere sister chromatid exchange in telomerase deficient murine cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yisong; Giannone, Richard J; Liu, Yie

    2005-01-01

    We have recently demonstrated that several types of genomic rearrangements (i.e., telomere sister chromatid exchange (T-SCE), genomic-SCE, or end-to-end fusions) were more often detected in long-term cultured murine telomerase deficient embryonic stem (ES) cells than in freshly prepared murine splenocytes, even through they possessed similar frequencies of critically short telomeres. The high rate of genomic rearrangements in telomerase deficient ES cells, when compared to murine splenocytes, may reflect the cultured cells' gained ability to protect chromosome ends with eroded telomeres allowing them to escape 'end crisis'. However, the possibility that ES cells were more permissive to genomic rearrangements than othermore » cell types or that differences in the microenvironment or genetic background of the animals might consequentially determine the rate of T-SCEs or other genomic rearrangements at critically short telomeres could not be ruled out.« less

  8. Stabilization of Reversed Replication Forks by Telomerase Drives Telomere Catastrophe.

    PubMed

    Margalef, Pol; Kotsantis, Panagiotis; Borel, Valerie; Bellelli, Roberto; Panier, Stephanie; Boulton, Simon J

    2018-01-25

    Telomere maintenance critically depends on the distinct activities of telomerase, which adds telomeric repeats to solve the end replication problem, and RTEL1, which dismantles DNA secondary structures at telomeres to facilitate replisome progression. Here, we establish that reversed replication forks are a pathological substrate for telomerase and the source of telomere catastrophe in Rtel1 -/- cells. Inhibiting telomerase recruitment to telomeres, but not its activity, or blocking replication fork reversal through PARP1 inhibition or depleting UBC13 or ZRANB3 prevents the rapid accumulation of dysfunctional telomeres in RTEL1-deficient cells. In this context, we establish that telomerase binding to reversed replication forks inhibits telomere replication, which can be mimicked by preventing replication fork restart through depletion of RECQ1 or PARG. Our results lead us to propose that telomerase inappropriately binds to and inhibits restart of reversed replication forks within telomeres, which compromises replication and leads to critically short telomeres. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  9. Telomere shortening triggers a feedback loop to enhance end protection

    PubMed Central

    Yang, Chia-Wei; Tseng, Shun-Fu; Yu, Chia-Jung; Chung, Chia-Yu; Chang, Cheng-Yen; Pobiega, Sabrina

    2017-01-01

    Abstract Telomere homeostasis is controlled by both telomerase machinery and end protection. Telomere shortening induces DNA damage sensing kinases ATM/ATR for telomerase recruitment. Yet, whether telomere shortening also governs end protection is poorly understood. Here we discover that yeast ATM/ATR controls end protection. Rap1 is phosphorylated by Tel1 and Mec1 kinases at serine 731, and this regulation is stimulated by DNA damage and telomere shortening. Compromised Rap1 phosphorylation hampers the interaction between Rap1 and its interacting partner Rif1, which thereby disturbs the end protection. As expected, reduction of Rap1–Rif1 association impairs telomere length regulation and increases telomere–telomere recombination. These results indicate that ATM/ATR DNA damage checkpoint signal contributes to telomere protection by strengthening the Rap1–Rif1 interaction at short telomeres, and the checkpoint signal oversees both telomerase recruitment and end capping pathways to maintain telomere homeostasis. PMID:28575419

  10. Break-induced telomere synthesis underlies alternative telomere maintenance

    PubMed Central

    Dilley, Robert L.; Verma, Priyanka; Cho, Nam Woo; Winters, Harrison D.; Wondisford, Anne R.; Greenberg, Roger A.

    2017-01-01

    Homology-directed DNA repair is essential for genome maintenance through templated DNA synthesis. Alternative lengthening of telomeres (ALT) necessitates homology-directed DNA repair to maintain telomeres in about 10–15% of human cancers. How DNA damage induces assembly and execution of a DNA replication complex (break-induced replisome) at telomeres or elsewhere in the mammalian genome is poorly understood. Here we define break-induced telomere synthesis and demonstrate that it utilizes a specialized replisome, which underlies ALT telomere maintenance. DNA double-strand breaks enact nascent telomere synthesis by long-tract unidirectional replication. Proliferating cell nuclear antigen (PCNA) loading by replication factor C (RFC) acts as the initial sensor of telomere damage to establish predominance of DNA polymerase δ (Pol δ) through its POLD3 subunit. Break-induced telomere synthesis requires the RFC–PCNA–Pol δ axis, but is independent of other canonical replisome components, ATM and ATR, or the homologous recombination protein Rad51. Thus, the inception of telomere damage recognition by the break-induced replisome orchestrates homology-directed telomere maintenance. PMID:27760120

  11. Telomeres, Reproductive Aging, and Genomic Instability During Early Development.

    PubMed

    Keefe, David L

    2016-12-01

    Implantation rate decreases and miscarriage rate increases with advancing maternal age. The oocyte must be the locus of reproductive aging because donation of oocytes from younger to older women abrogates the effects of aging on fecundity. Nuclear transfer experiments in a mouse model of reproductive aging show that the reproductive aging phenotype segregates with the nucleus rather than the cytoplasm. A number of factors within the nucleus have been hypothesized to mediate reproductive aging, including disruption of cohesions, reduced chiasma, aneuploidy, disrupted meiotic spindles, and DNA damage caused by chronic exposure to reactive oxygen species. We have proposed telomere attrition as a parsimonious way to explain these diverse effects of aging on oocyte function. Telomeres are repetitive sequences of DNA and associated proteins, which form a loop (t loop) at chromosome ends. Telomeres prevent the blunt end of DNA from triggering a DNA damage response. Previously, we showed that experimental telomere shortening phenocopies reproductive aging in mice. Telomere shortening causes reduced synapsis and chiasma, chromosome fusions, embryo arrest and fragmentation, and abnormal meiotic spindles. Telomere length of polar bodies predicts the fragmentation of human embryos. Telomerase, the reverse transcriptase capable of reconstituting shortened telomeres, is only minimally active in oocytes and preimplantation embryos. Intriguingly, during the first cell cycles following activation, telomeres robustly elongate via a DNA double-strand break mechanism called alternative lengthening of telomeres (ALTs). Alternative lengthening of telomere takes place even in telomerase-null mice. This mechanism of telomere elongation previously had been found only in cancer cells lacking telomerase activity. We propose that ALT elongates telomeres across generations but does so at the cost of extensive genomic instability in preimplantation embryos. © The Author(s) 2016.

  12. Telomeres in aging and disease: lessons from zebrafish.

    PubMed

    Carneiro, Madalena C; de Castro, Inês Pimenta; Ferreira, Miguel Godinho

    2016-07-01

    Age is the highest risk factor for some of the most prevalent human diseases, including cancer. Telomere shortening is thought to play a central role in the aging process in humans. The link between telomeres and aging is highlighted by the fact that genetic diseases causing telomerase deficiency are associated with premature aging and increased risk of cancer. For the last two decades, this link has been mostly investigated using mice that have long telomeres. However, zebrafish has recently emerged as a powerful and complementary model system to study telomere biology. Zebrafish possess human-like short telomeres that progressively decline with age, reaching lengths in old age that are observed when telomerase is mutated. The extensive characterization of its well-conserved molecular and cellular physiology makes this vertebrate an excellent model to unravel the underlying relationship between telomere shortening, tissue regeneration, aging and disease. In this Review, we explore the advantages of using zebrafish in telomere research and discuss the primary discoveries made in this model that have contributed to expanding our knowledge of how telomere attrition contributes to cellular senescence, organ dysfunction and disease. © 2016. Published by The Company of Biologists Ltd.

  13. Diet-related telomere shortening and chromosome stability

    PubMed Central

    Marcon, Francesca; Siniscalchi, Ester; Crebelli, Riccardo; Saieva, Calogero; Sera, Francesco; Fortini, Paola; Simonelli, Valeria; Palli, Domenico

    2012-01-01

    Recent evidences have highlighted an influence of micronutrients in the maintenance of telomere length (TL). In order to explore whether diet-related telomere shortening had any physiological relevance and was accompanied by significant damage in the genome, in the present study, TL was assessed by terminal restriction fragment (TRF) analysis in peripheral blood lymphocytes of 56 healthy subjects for which detailed information on dietary habits was available and data were compared \\with the incidence of nucleoplasmic bridges (NPBs), a marker of chromosomal instability related to telomere dysfunction visualised with the cytokinesis-blocked micronucleus assay. To increase the capability to detect even slight impairment of telomere function, the incidence of NPBs was also evaluated on cells exposed in vitro to ionising radiation. Care was taken to control for potential confounding factors that might influence TL, viz. age, hTERT genotype and smoking status. Data showed that higher consumption of vegetables was related with significantly higher mean TL (P = 0.013); in particular, the analysis of the association between micronutrients and mean TL highlighted a significant role of antioxidant intake, especially beta-carotene, on telomere maintenance (P = 0.004). However, the diet-related telomere shortening did not result in associated increased spontaneous or radiation-induced NPBs. The distribution of TRFs was also analysed and a slight prevalence of radiation-induced NPBs (P = 0.03) was observed in subjects with higher amount of very short TRFs (<2 kb). The relative incidence of very short TRFs was positively associate with ageing (P = 0.008) but unrelated to vegetables consumption and daily intake of micronutrients, suggesting that the degree of telomere erosion related with low dietary intake of antioxidants observed in this study was not so extensive to lead to chromosome instability. PMID:21857007

  14. ATM kinase is required for telomere elongation in mouse and human cells

    PubMed Central

    Lee, Stella Suyong; Bohrson, Craig; Pike, Alexandra Mims; Wheelan, Sarah Jo; Greider, Carol Widney

    2015-01-01

    Summary Short telomeres induce a DNA damage response, senescence and apoptosis; thus, maintaining telomere length equilibrium is essential for cell viability. Telomerase addition of telomere repeats is tightly regulated in cells. To probe pathways that regulate telomere addition, we developed the ADDIT assay to measure new telomere addition at a single telomere in vivo. Sequence analysis showed telomerase specific addition of repeats onto a new telomere occurred in just 48 hr. Using the ADDIT assay, we found that ATM is required for addition of new repeats onto telomeres in mouse cells. Evaluation of bulk telomeres, in both human and mouse cells, showed that blocking ATM inhibited telomere elongation. Finally, the activation of ATM through the inhibition of PARP1 resulted in increased telomere elongation, supporting the central role of the ATM pathway in regulating telomere addition. Understanding this role of ATM may yield new areas for possible therapeutic intervention in telomere-mediated disease. PMID:26586427

  15. Telomeres and Mitochondria in the Aging Heart

    PubMed Central

    Moslehi, Javid; DePinho, Ronald A.; Sahin, Ergün

    2013-01-01

    Studies in humans and in mice have highlighted the importance of short telomeres and impaired mitochondrial function in driving age-related functional decline in the heart. Although telomere and mitochondrial dysfunction have been viewed mainly in isolation, recent studies in telomerase-deficient mice have provided evidence for an intimate link between these two processes. Telomere dysfunction induces a profound p53-dependent repression of the master regulators of mitochondrial biogenesis and function, peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and PGC-1β in the heart, which leads to bioenergetic compromise due to impaired oxidative phosphorylation and ATP generation. This telomere-p53-PGC mitochondrial/metabolic axis integrates many factors linked to heart aging including increased DNA damage, p53 activation, mitochondrial, and metabolic dysfunction and provides a molecular basis of how dysfunctional telomeres can compromise cardiomyocytes and stem cell compartments in the heart to precipitate cardiac aging. PMID:22539756

  16. Telomeres and replicative senescence: Is it only length that counts?

    PubMed

    von Zglinicki, T

    2001-07-26

    Telomeres are well established as a major 'replicometer', counting the population doublings in primary human cell cultures and ultimately triggering replicative senescence. However, neither is the pace of this biological clock inert, nor is there a fixed threshold telomere length acting as the universal trigger of replicative senescence. The available data suggest that opening of the telomeric loop and unscheduled exposure of the single-stranded G-rich telomeric overhang might act like a semaphore to signal senescent cell cycle arrest. Short telomere length, telomeric single-strand breaks, low levels of loop-stabilizing proteins, or other factors may trigger this opening of the loop. Thus, both telomere shortening and the ultimate signalling into senescence are able to integrate different environmental and genetic factors, especially oxidative stress-mediated damage, which might otherwise become a thread to genomic stability.

  17. Telomere dysfunction in alveolar epithelial cells causes lung remodeling and fibrosis

    PubMed Central

    Naikawadi, Ram P.; Disayabutr, Supparerk; Mallavia, Benat; Donne, Matthew L.; Green, Gary; La, Janet L.; Rock, Jason R.; Looney, Mark R.; Wolters, Paul J.

    2016-01-01

    Telomeres are short in type II alveolar epithelial cells (AECs) of patients with idiopathic pulmonary fibrosis (IPF). Whether dysfunctional telomeres contribute directly to development of lung fibrosis remains unknown. The objective of this study was to investigate whether telomere dysfunction in type II AECs, mediated by deletion of the telomere shelterin protein TRF1, leads to pulmonary fibrosis in mice (SPC-Cre TRF1fl/fl mice). Deletion of TRF1 in type II AECs for 2 weeks increased γH2AX DNA damage foci, but not histopathologic changes in the lung. Deletion of TRF1 in type II AECs for up to 9 months resulted in short telomeres and lung remodeling characterized by increased numbers of type II AECs, α-smooth muscle actin+ mesenchymal cells, collagen deposition, and accumulation of senescence-associated β-galactosidase+ lung epithelial cells. Deletion of TRF1 in collagen-expressing cells caused pulmonary edema, but not fibrosis. These results demonstrate that prolonged telomere dysfunction in type II AECs, but not collagen-expressing cells, leads to age-dependent lung remodeling and fibrosis. We conclude that telomere dysfunction in type II AECs is sufficient to cause lung fibrosis, and may be a dominant molecular defect causing IPF. SPC-Cre TRF1fl/fl mice will be useful for assessing cellular and molecular mechanisms of lung fibrosis mediated by telomere dysfunction. PMID:27699234

  18. Telomere length elongation after weight loss intervention in obese adults.

    PubMed

    Carulli, L; Anzivino, C; Baldelli, E; Zenobii, M F; Rocchi, M B L; Bertolotti, M

    2016-06-01

    Telomeres may be considered markers of biological aging, shorter telomere length is associated with some age-related diseases; in several studies short telomere length has also been associated to obesity in adults and adolescents. However the relationship between telomere complex functions and obesity is still not clear. Aim of the study was to assess telomere length (TL) in adults' obese subjects before and after weight loss obtained by placement of bioenteric intragastric balloon (BIB) for 6months. We enrolled 42 obese subjects before and after BIB placement as weight loss intervention. Blood samples were collected in order to obtain DNA from leukocyte to measure TL by quantitative PCR. Data were analyzed only in 37 subjects with complete data; all presented important body weight loss (124.06±26.7 vs 105.40±23.14, p<0.001) and more interesting they presented a significant increase in TL (3.58±0.83 vs 5.61±3.29, p<0.001). Moreover we observed a significant positive correlation between TL elongation and weight loss (r=0.44, p=0.007) as well as an inverse correlation between TL at baseline and TL elongation (r=-0.35, p=0.03).The predictors of TL elongation were once again weight loss and short TL at baseline (respectively p=0.007 and p=0.003). Our study shows that weight loss is associated to telomere lengthening in a positive correlation: the greater weight loss the greater telomere lengthening; moreover telomere lengthening is more significant in those subjects with shortest telomeres at baseline. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Saccharomyces cerevisiae as a Model to Study Replicative Senescence Triggered by Telomere Shortening

    PubMed Central

    Teixeira, M. Teresa

    2013-01-01

    In many somatic human tissues, telomeres shorten progressively because of the DNA-end replication problem. Consequently, cells cease to proliferate and are maintained in a metabolically viable state called replicative senescence. These cells are characterized by an activation of DNA damage checkpoints stemming from eroded telomeres, which are bypassed in many cancer cells. Hence, replicative senescence has been considered one of the most potent tumor suppressor pathways. However, the mechanism through which short telomeres trigger this cellular response is far from being understood. When telomerase is removed experimentally in Saccharomyces cerevisiae, telomere shortening also results in a gradual arrest of population growth, suggesting that replicative senescence also occurs in this unicellular eukaryote. In this review, we present the key steps that have contributed to the understanding of the mechanisms underlying the establishment of replicative senescence in budding yeast. As in mammals, signals stemming from short telomeres activate the DNA damage checkpoints, suggesting that the early cellular response to the shortest telomere(s) is conserved in evolution. Yet closer analysis reveals a complex picture in which the apparent single checkpoint response may result from a variety of telomeric alterations expressed in the absence of telomerase. Accordingly, the DNA replication of eroding telomeres appears as a critical challenge for senescing budding yeast cells and the easy manipulation of S. cerevisiae is providing insights into the way short telomeres are integrated into their chromatin and nuclear environments. Finally, the loss of telomerase in budding yeast triggers a more general metabolic alteration that remains largely unexplored. Thus, telomerase-deficient S. cerevisiae cells may have more common points than anticipated with somatic cells, in which telomerase depletion is naturally programed, thus potentially inspiring investigations in mammalian cells

  20. Correlation of cord blood telomere length with birth weight.

    PubMed

    Lee, Siew-Peng; Hande, Prakash; Yeo, George Sh; Tan, Ene-Choo

    2017-09-08

    Intrauterine growth restriction affects 3% of newborns; and the lightest 10% of whom are classified as small for gestational age (SGA). These low-birth weight newborns are at increased risk of neonatal morbidity such as hypoxia and hypoglycaemia. In later life, they are at higher risk of several age-related diseases such as cardiovascular and metabolic disorders and dementia. As having short telomeres is also associated with these diseases, we tested if these newborns might already start with shorter telomeres at birth. Relative telomere lengths were determined using quantitative real-time PCR in cord blood samples from 195 newborns of Chinese ancestry. Based on the telomere length normalised to a single copy gene and a reference DNA sample as internal control, we found statistically significant correlations between relative telomere length and both unadjusted and gestational age-adjusted birth weight, with the lighter newborns having shorter telomeres. The SGA birth weight group comprising the bottom 10% of the samples also had the shortest telomeres compared to the medium and heaviest birth weight groups. Our results indicate that there is reduction of cord blood telomere length for newborns with lower birth weight.

  1. High-throughput telomere length quantification by FISH and its application to human population studies.

    PubMed

    Canela, Andrés; Vera, Elsa; Klatt, Peter; Blasco, María A

    2007-03-27

    A major limitation of studies of the relevance of telomere length to cancer and age-related diseases in human populations and to the development of telomere-based therapies has been the lack of suitable high-throughput (HT) assays to measure telomere length. We have developed an automated HT quantitative telomere FISH platform, HT quantitative FISH (Q-FISH), which allows the quantification of telomere length as well as percentage of short telomeres in large human sample sets. We show here that this technique provides the accuracy and sensitivity to uncover associations between telomere length and human disease.

  2. Patients with gout have short telomeres compared with healthy participants: association of telomere length with flare frequency and cardiovascular disease in gout.

    PubMed

    Vazirpanah, N; Kienhorst, L B E; Van Lochem, E; Wichers, C; Rossato, M; Shiels, P G; Dalbeth, N; Stamp, L K; Merriman, T R; Janssen, M; Radstake, T R D J; Broen, J Ca

    2017-07-01

    Chronic inflammation associates with increased senescence, which is a strong predictor for cardiovascular disease. We hypothesised that inflammation accelerates senescence and thereby enhances the risk of cardiovascular disease in gout. We assessed replicative senescence by quantifying telomere length (TL) in a discovery cohort of 145 Dutch patients with gout and 273 healthy individuals and validated our results in 474 patients with gout and 293 healthy participants from New Zealand. Subsequently, we investigated the effect of cardiovascular disease on TL of all participants. Also, we measured TL of CD4 + and CD8 + T lymphocytes, B lymphocytes, monocytes, natural killer cells and plasmacytoid dendritic cells. Additionally, we assessed the potential temporal difference in TL and telomerase activity. TL in PBMCs of healthy donors decreased over time, reflecting normal ageing. Patients with gout demonstrated shorter telomeres (p=0.001, R 2 =0.01873). In fact, the extent of telomere erosion in patients with gout was higher at any age compared with healthy counterparts at any age (p<0.0001, R 2 =0.02847). Patients with gout with cardiovascular disease had the shortest telomeres and TL was an independent risk factor for cardiovascular disease in patients with gout (p=0.001). TL was inversely associated with the number of gouty flares (p=0.005). Patients with gout have shorter telomeres than healthy participants, reflecting increased cellular senescence. Telomere shortening was associated with the number of flares and with cardiovascular disease in people with gout. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  3. Salivary Telomere Length and Lung Function in Adolescents Born Very Preterm: A Prospective Multicenter Study.

    PubMed

    Hadchouel, Alice; Marchand-Martin, Laetitia; Franco-Montoya, Marie-Laure; Peaudecerf, Laetitia; Ancel, Pierre-Yves; Delacourt, Christophe

    2015-01-01

    Preterm birth is associated with abnormal respiratory functions throughout life. The mechanisms underlying these long-term consequences are still unclear. Shortening of telomeres was associated with many conditions, such as chronic obstructive pulmonary disease. We aimed to search for an association between telomere length and lung function in adolescents born preterm. Lung function and telomere length were measured in 236 adolescents born preterm and 38 born full-term from the longitudinal EPIPAGE cohort. Associations between telomere length and spirometric indices were tested in univariate and multivariate models accounting for confounding factors in the study population. Airflows were significantly lower in adolescents born preterm than controls; forced expiratory volume in one second was 12% lower in the extremely preterm born group than controls (p<0.001). Lower birth weight, bronchopulmonary dysplasia and postnatal sepsis were significantly associated with lower airflow values. Gender was the only factor that was significantly associated with telomere length. Telomere length correlated with forced expiratory flow 25-75 in the extremely preterm adolescent group in univariate and multivariate analyses (p = 0.01 and p = 0.02, respectively). We evidenced an association between telomere length and abnormal airflow in a population of adolescents born extremely preterm. There was no evident association with perinatal events. This suggests other involved factors, such as a continuing airway oxidative stress leading to persistent inflammation and altered lung function, ultimately increasing susceptibility to chronic obstructive pulmonary disease.

  4. Association between maternal symptoms of sleep disordered breathing and fetal telomere length.

    PubMed

    Salihu, Hamisu M; King, Lindsey; Patel, Priyanshi; Paothong, Arnut; Pradhan, Anupam; Louis, Judette; Naik, Eknath; Marty, Phillip J; Whiteman, Valerie

    2015-04-01

    Our investigation aims to assess the impact of symptoms of maternal sleep-disordered breathing, specifically sleep apnea risk and daytime sleepiness, on fetal leukocyte telomere length. Pregnant women were recruited upon hospital delivery admission. Sleep exposure outcomes were measured using the Berlin Questionnaire to quantify sleep apnea and the Epworth Sleepiness Scale to measure daytime sleepiness. Participants were classified as "High Risk" or "Low Risk" for sleep apnea based on responses to the Berlin, while "Normal" or "Abnormal" daytime sleepiness was determined based on responses to the Epworth. Neonatal umbilical cord blood samples (N = 67) were collected and genomic DNA was isolated from cord blood leukocytes using Quantitative PCR. A ratio of relative telomere length was derived by telomere repeat copy number and single copy gene copy number (T/S ratio) and used to compare telomere lengths. Bootstrap and ANOVA statistical procedures were employed. On the Berlin, 68.7% of participants were classified as Low Risk while 31.3% were classified as High Risk for sleep apnea. According to the Epworth scale, 80.6% were determined to have Normal daytime sleepiness, and 19.4% were found to have Abnormal daytime sleepiness. The T/S ratio among pregnant women at High Risk for sleep apnea was significantly shorter than for those at Low Risk (P value < 0.05), and the T/S ratio among habitual snorers was significantly shorter than among non-habitual snorers (P value < 0.05). Although those with Normal Sleepiness had a longer T/S ratio than those with Abnormal Sleepiness, the difference was not statistically significant. Our results provide the first evidence demonstrating shortened telomere length among fetuses exposed to maternal symptoms of sleep disordered breathing during pregnancy, and suggest sleep disordered breathing as a possible mechanism of accelerated chromosomal aging. © 2015 Associated Professional Sleep Societies, LLC.

  5. Telomere erosion varies during in vitro aging of normal human fibroblasts from young and adult donors.

    PubMed

    Figueroa, R; Lindenmaier, H; Hergenhahn, M; Nielsen, K V; Boukamp, P

    2000-06-01

    The life span of normal fibroblasts in vitro (Hayflick limit) depends on donor age, and telomere shortening has been proposed as a potential mechanism. By quantitative fluorescence in situ hybridization and Southern blot analysis, we show progressive telomere loss to about 5 kb mean telomere restriction fragment length in fibroblasts from two adult donors within 40 population doublings, whereas in fibroblasts from two infant donors, telomere erosion is reduced, leaving a mean telomere restriction fragment length of approximately 7 kb at senescence (after approximately 60 population doublings). Aging of fibroblasts from both infant and adult donors was not accompanied by chromosomal abnormalities but was correlated with increased telomere repeat-binding factor 2 expression at both the protein and transcriptional level.

  6. Vanishing honey bees: Is the dying of adult worker bees a consequence of short telomeres and premature aging?

    PubMed

    Stindl, Reinhard; Stindl, Wolfgang

    2010-10-01

    Einstein is often quoted to have said that without the bee, mankind would have but 4years to live. It is highly unlikely that he made this comment, which was even mentioned in a Lancet article on honey bees. However, the current vanishing of the bees can have serious consequences for human health, because 35% of the human diet is thought to benefit from pollination. Colony collapse disorder (CCD) in honey bees is characterized by the rapid decline of the adult bee population, leaving the brood and the queen poorly or completely unattended, with no dead bodies in or around the hive. A large study found no evidence that the presence or amount of any individual pesticide or infectious agent occurred more frequently or abundantly in CCD-affected colonies. The growing consensus is that honey bees are suffering from comprised immune systems, which allow various infectious pathogens to invade. The question remains, what causes immunosuppression in many colonies of Apis mellifera in North America and Europe? Telomeres are protective DNA structures located at eukaryotic chromosome tips that shorten in the somatic tissues of animals with age. Lifelong tissue regeneration takes place in Apis mellifera, and worker bees have been shown to senesce. In humans, a vast amount of literature has accumulated on exhausted telomere reserves causing impaired tissue regeneration and age-associated diseases, specifically cancer and immunosuppression. Therefore, we propose a new causative mechanism for the vanishing of the bees: critically short telomeres in long-lived winter bees. We term this the telomere premature aging syndrome. Copyright 2010 Elsevier Ltd. All rights reserved.

  7. Telomeres and telomere dynamics: relevance to cancers of the gastrointestinal tract

    PubMed Central

    Basu, Nivedita; Skinner, Halcyon G.; Litzelman, Kristin; Vanderboom, Russell; Baichoo, Esha; Boardman, Lisa A.

    2013-01-01

    Summary Aberrations in telomere length and telomere maintenance contribute to cancer development. In this article, we review basic principles of telomere length in normal and tumor tissue and the presence of the two main telomere maintenance pathways as they pertain to GI tract cancer. Peripheral blood telomeres are shorter in patients with many types of GI tract cancers. Telomere length in tumor DNA also appears to shorten early in cancer development. Tumor telomere shortening is often accompanied by telomerase activation to protect genetically damaged DNA from normal cell senescence or apoptosis, allowing immortalized but damaged DNA to persist. Alternative lengthening of telomeres (ALT) is another mechanism used by cancer to maintain telomere length in cancer cells. Telomerase and ALT activators and inhibitors may become important chemopreventive or chemotherapeutic agents as our understanding of telomere biology, specific telomere related phenotypes, and its relationship to carcinogenesis increases. PMID:24161135

  8. High-resolution telomere fluorescence in situ hybridization reveals intriguing anomalies in germ cell tumors.

    PubMed

    Shekhani, Mohammed Talha; Barber, John R; Bezerra, Stephania M; Heaphy, Christopher M; Gonzalez Roibon, Nilda Diana; Taheri, Diana; Reis, Leonardo O; Guner, Gunes; Joshu, Corinne E; Netto, George J; Meeker, Alan K

    2016-08-01

    Testicular germ cell tumor (TGCT) is the most common malignancy of young men. Most patients are completely cured, which distinguishes these from most other malignancies. Orchiectomy specimens (n=76) were evaluated using high-resolution (single-cell discriminative) telomere-specific fluorescence in situ hybridization (FISH) with simultaneous Oct4 immunofluorescence to describe telomere length phenotype in TGCT neoplastic cells. For the first time, the TGCT precursor lesion, germ cell neoplasia in situ (GCNIS) is also evaluated in depth. The intensity of the signals from cancerous cells was compared to the same patient's reference cells-namely, healthy germ cells (defined as "medium" length) and interstitial/somatic cells (defined as "short" telomere length). We observed short telomeres in most GCNIS and pure seminomas (P=.006 and P=.0005, respectively). In contrast, nonseminomas displayed longer telomeres. Lesion-specific telomere lengths were documented in mixed tumor cases. Embryonal carcinoma (EC) demonstrated the longest telomeres. A fraction of EC displays the telomerase-independent alternative lengthening of telomeres (ALT) phenotype (24% of cases). Loss of ATRX or DAXX nuclear expression was strongly associated with ALT; however, nuclear expression of both proteins was retained in half of ALT-positive ECs. The particular distribution of telomere lengths among TGCT and GCNIS precursors implicate telomeres anomalies in pathogenesis. These results may advise management decisions as well. Copyright © 2016. Published by Elsevier Inc.

  9. Biology of telomeres: importance in etiology of esophageal cancer and as therapeutic target.

    PubMed

    Pal, Jagannath; Gold, Jason S; Munshi, Nikhil C; Shammas, Masood A

    2013-12-01

    The purpose of this review is to highlight the importance of telomeres, the mechanisms implicated in their maintenance, and their role in the etiology as well as the treatment of human esophageal cancer. We will also discuss the role of telomeres in the maintenance and preservation of genomic integrity, the consequences of telomere dysfunction, and the various factors that may affect telomere health in esophageal tissue predisposing it to oncogenesis. There has been growing evidence that telomeres, which can be affected by various intrinsic and extrinsic factors, contribute to genomic instability, oncogenesis, as well as proliferation of cancer cells. Telomeres are the protective DNA-protein complexes at chromosome ends. Telomeric DNA undergoes progressive shortening with age leading to cellular senescence and/or apoptosis. If senescence/apoptosis is prevented as a consequence of specific genomic changes, continued proliferation leads to very short (ie, dysfunctional) telomeres that can potentially cause genomic instability, thus, increasing the risk for activation of telomere maintenance mechanisms and oncogenesis. Like many other cancers, esophageal cancer cells have short telomeres and elevated telomerase, the enzyme that maintains telomeres in most cancer cells. Homologous recombination, which is implicated in the alternate pathway of telomere elongation, is also elevated in Barrett's-associated esophageal adenocarcinoma. Evidence from our laboratory indicates that both telomerase and homologous recombination contribute to telomere maintenance, DNA repair, and the ongoing survival of esophageal cancer cells. This indicates that telomere maintenance mechanisms may potentially be targeted to make esophageal cancer cells static. The rate at which telomeres in healthy cells shorten is determined by a number of intrinsic and extrinsic factors, including those associated with lifestyle. Avoidance of factors that may directly or indirectly injure esophageal tissue

  10. Unraveling the Pathogenesis of Hoyeraal-Hreidarsson Syndrome, a Complex Telomere Biology Disorder

    PubMed Central

    Glousker, Galina; Touzot, Fabien; Revy, Patrick; Tzfati, Yehuda; Savage, Sharon A.

    2015-01-01

    SUMMARY Hoyeraal-Hreidarsson (HH) syndrome is a multisystem genetic disorder characterized by very short telomeres and considered a clinically severe variant of dyskeratosis congenita (DC). The main cause of mortality, usually in early childhood, is bone marrow failure. Mutations in several telomere biology genes have been reported to cause HH in about 60% of the HH patients, but the genetic defects in the rest of the patients are still unknown. Understanding the aetiology of HH and its diverse manifestations is challenging because of the complexity of telomere biology and the multiple telomeric and non-telomeric functions played by telomere-associated proteins in processes such as telomere replication, telomere protection, DNA damage response and ribosome and spliceosome assembly. Here we review the known clinical complications, molecular defects and germline mutations associated with HH, and elucidate possible mechanistic explanations and remaining questions in our understanding of the disease. PMID:25940403

  11. Segregating YKU80 and TLC1 alleles underlying natural variation in telomere properties in wild yeast.

    PubMed

    Liti, Gianni; Haricharan, Svasti; Cubillos, Francisco A; Tierney, Anna L; Sharp, Sarah; Bertuch, Alison A; Parts, Leopold; Bailes, Elizabeth; Louis, Edward J

    2009-09-01

    In yeast, as in humans, telomere length varies among individuals and is controlled by multiple loci. In a quest to define the extent of variation in telomere length, we screened 112 wild-type Saccharomyces sensu stricto isolates. We found extensive telomere length variation in S. paradoxus isolates. This phenotype correlated with their geographic origin: European strains were observed to have extremely short telomeres (<150 bp), whereas American isolates had telomeres approximately three times as long (>400 bp). Insertions of a URA3 gene near telomeres allowed accurate analysis of individual telomere lengths and telomere position effect (TPE). Crossing the American and European strains resulted in F1 spores with a continuum of telomere lengths consistent with what would be predicted if many quantitative trait loci (QTLs) were involved in length maintenance. Variation in TPE is similarly quantitative but only weakly correlated with telomere length. Genotyping F1 segregants indicated several QTLs associated with telomere length and silencing variation. These QTLs include likely candidate genes but also map to regions where there are no known genes involved in telomeric properties. We detected transgressive segregation for both phenotypes. We validated by reciprocal hemizygosity that YKU80 and TLC1 are telomere-length QTLs in the two S. paradoxus subpopulations. Furthermore, we propose that sequence divergence within the Ku heterodimer generates negative epistasis within one of the allelic combinations (American-YKU70 and European-YKU80) resulting in very short telomeres.

  12. Segregating YKU80 and TLC1 Alleles Underlying Natural Variation in Telomere Properties in Wild Yeast

    PubMed Central

    Liti, Gianni; Haricharan, Svasti; Cubillos, Francisco A.; Tierney, Anna L.; Sharp, Sarah; Bertuch, Alison A.; Parts, Leopold; Bailes, Elizabeth; Louis, Edward J.

    2009-01-01

    In yeast, as in humans, telomere length varies among individuals and is controlled by multiple loci. In a quest to define the extent of variation in telomere length, we screened 112 wild-type Saccharomyces sensu stricto isolates. We found extensive telomere length variation in S. paradoxus isolates. This phenotype correlated with their geographic origin: European strains were observed to have extremely short telomeres (<150 bp), whereas American isolates had telomeres approximately three times as long (>400 bp). Insertions of a URA3 gene near telomeres allowed accurate analysis of individual telomere lengths and telomere position effect (TPE). Crossing the American and European strains resulted in F1 spores with a continuum of telomere lengths consistent with what would be predicted if many quantitative trait loci (QTLs) were involved in length maintenance. Variation in TPE is similarly quantitative but only weakly correlated with telomere length. Genotyping F1 segregants indicated several QTLs associated with telomere length and silencing variation. These QTLs include likely candidate genes but also map to regions where there are no known genes involved in telomeric properties. We detected transgressive segregation for both phenotypes. We validated by reciprocal hemizygosity that YKU80 and TLC1 are telomere-length QTLs in the two S. paradoxus subpopulations. Furthermore, we propose that sequence divergence within the Ku heterodimer generates negative epistasis within one of the allelic combinations (American-YKU70 and European-YKU80) resulting in very short telomeres. PMID:19763176

  13. The power of exercise: buffering the effect of chronic stress on telomere length.

    PubMed

    Puterman, Eli; Lin, Jue; Blackburn, Elizabeth; O'Donovan, Aoife; Adler, Nancy; Epel, Elissa

    2010-05-26

    Chronic psychological stress is associated with detrimental effects on physical health, and may operate in part through accelerated cell aging, as indexed by shorter telomeres at the ends of chromosomes. However, not all people under stress have distinctly short telomeres, and we examined whether exercise can serve a stress-buffering function. We predicted that chronic stress would be related to short telomere length (TL) in sedentary individuals, whereas in those who exercise, stress would not have measurable effects on telomere shortening. 63 healthy post-menopausal women underwent a fasting morning blood draw for whole blood TL analysis by a quantitative polymerase chain reaction method. Participants completed the Perceived Stress Scale (Cohen et al., 1983), and for three successive days reported daily minutes of vigorous activity. Participants were categorized into two groups-sedentary and active (those getting Centers for Disease Control-recommended daily amount of activity). The likelihood of having short versus long telomeres was calculated as a function of stress and exercise group, covarying age, BMI and education. Logistic regression analyses revealed a significant moderating effect of exercise. As predicted, among non-exercisers a one unit increase in the Perceived Stress Scale was related to a 15-fold increase in the odds of having short telomeres (p<.05), whereas in exercisers, perceived stress appears to be unrelated to TL (B = -.59, SE = .78, p = .45). Vigorous physical activity appears to protect those experiencing high stress by buffering its relationship with TL. We propose pathways through which physical activity acts to buffer stress effects.

  14. Molecular characterisation of a mosaicism with a complex chromosome rearrangement: evidence for coincident chromosome healing by telomere capture and neo‐telomere formation

    PubMed Central

    Chabchoub, Elyes; Rodríguez, Laura; Galán, Enrique; Mansilla, Elena; Martínez‐Fernandez, Maria Luisa; Martínez‐Frías, Maria Luisa; Fryns, Jean‐Pierre; Vermeesch, Joris Robert

    2007-01-01

    Background Broken chromosomes must acquire new telomeric “caps” to be structurally stable. Chromosome healing can be mediated either by telomerase through neo‐telomere synthesis or by telomere capture. Aim To unravel the mechanism(s) generating complex chromosomal mosaicisms and healing broken chromosomes. Methods G banding, array comparative genomic hybridization (aCGH), fluorescence in‐situ hybridisation (FISH) and short tandem repeat analysis (STR) was performed on a girl presenting with mental retardation, facial dysmorphism, urogenital malformations and limb anomalies carrying a complex chromosomal mosaicism. Results & discussion The karyotype showed a de novo chromosome rearrangement with two cell lines: one cell line with a deletion 9pter and one cell line carrying an inverted duplication 9p and a non‐reciprocal translocation 5pter fragment. aCGH, FISH and STR analysis enabled the deduction of the most likely sequence of events generating this complex mosaic. During embryogenesis, a double‐strand break occurred on the paternal chromosome 9. Following mitotic separation of both broken sister chromatids, one acquired a telomere vianeo‐telomere formation, while the other generated a dicentric chromosome which underwent breakage during anaphase, giving rise to the del inv dup(9) that was subsequently healed by chromosome 5 telomere capture. Conclusion Broken chromosomes can coincidently be rescued by both telomere capture and neo‐telomere synthesis. PMID:17172463

  15. Effect of vitamin E administration on the elevated oxygen stress and the telomeric and subtelomeric status in Alzheimer's disease.

    PubMed

    Guan, Jing-Zhi; Guan, Wei-Ping; Maeda, Toyoki; Makino, Naoki

    2012-01-01

    Oxidative stress (OS) may be involved in the neurodegenerative process in Alzheimer's disease (AD). Telomeres, the repeated sequences that cap chromosome ends, undergo shortening with each cell division, are sensitive to OS, and serve as markers of a cell's replicative history. Telomere length shortening has been reported to relate to OS with aging process and aging-associated diseases, but the telomeric changes were not always identical, especially in change of telomere length distribution and subtelomeric methylation. The involvement of an OS-associated telomere change in the pathogenesis of AD has been discussed for decades, and the telomere length and telomerase activity were analyzed. However, other telomeric factors, such as the telomere distribution and subtelomeric methylation status, have not yet been analyzed. The subtelomeric methylation status as well as the telomere length were studied in AD with an antioxidant vitamin in terms of OS. We measured urinary 8-iso-PGF2α, a lipid-peroxidation product as an OS marker, and methylated and non-methylated telomere lengths in the peripheral blood mononuclear cells by Southern blotting in AD patients before and after vitamin E treatment. The level of urinary 8-iso-PGF2α was found to have increased in AD. Middle-ranged telomeres (4.4-9.4 kb) increased and the shortest telomeres (<4.4 kb) decreased in AD patients. Telomeres were more methylated in both long telomeres and in short telomeres in AD compared with the control. The oral administration of the antioxidant vitamin E in 400 mg/day for 6 months in AD patients partly reversed AD-associated alterations in OS marker levels. AD patients showed an elevated OS marker level, and vitamin E lowered the OS level. In comparison with controls, AD patients showed shorter telomere lengths. Cells with short and long telomeres bore relatively hypermethylated subtelomeres in AD patients. Aging-associated accumulation of cells bearing short telomeres was not observed in AD

  16. Telomere length reflects phenotypic quality and costs of reproduction in a long-lived seabird.

    PubMed

    Bauch, Christina; Becker, Peter H; Verhulst, Simon

    2013-02-07

    Telomere length is associated with cellular senescence, lifestyle and ageing. Short telomeres indicate poor health in humans and reduced life expectancy in several bird species, but little is known about telomeres in relation to phenotypic quality in wild animals. We investigated telomere lengths in erythrocytes of known-age common terns (Sterna hirundo), a migratory seabird, in relation to arrival date and reproductive performance. Cross-sectional data revealed that, independent of age, individuals with short telomeres performed better: they arrived and reproduced earlier in the season and had more chicks in the nest. The latter effect was stronger the older the brood and stronger in males, which do most of the chick provisioning. Longitudinal data confirmed this pattern: compared with birds that lost their brood, birds that raised chicks beyond the 10th nestling day experienced higher telomere attrition from one year to the next. However, more detailed analysis revealed that the least and most successful individuals lost the fewest base pairs compared with birds with intermediate success. Our results suggest that reproductive success is achieved at the expense of telomeres, but that individual heterogeneity in susceptibility to such detrimental effects is important, as indicated by low telomere loss in the most successful birds.

  17. Interstitial telomeric sequences in vertebrate chromosomes: Origin, function, instability and evolution.

    PubMed

    Bolzán, Alejandro D

    2017-07-01

    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. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Super-resolution optical microscopy study of telomere structure.

    PubMed

    Phipps, Mary Lisa; Goodwin, Peter M; Martinez, Jennifer S; Goodwin, Edwin H

    2016-09-01

    Chromosome ends are shielded from exonucleolytic attack and inappropriate end-joining by terminal structures called telomeres; these structures are potential targets for anticancer drugs. Telomeres are composed of a simple DNA sequence (5?-TTAGGG-3? in humans) repeated more than a thousand times, a short 3? single-stranded overhang, and numerous proteins. Electron microscopy has shown that the 3? overhang pairs with the complementary strand at an internal site creating a small displacement loop and a large double-stranded “t-loop.” Our goal is to determine whether all telomeres adopt the t-loop configuration, or whether there are two or more distinct configurations. Progress in optimizing super-resolution (SR) microscopy for this ongoing investigation is reported here. Results suggest that under certain conditions sample preparation procedures may disrupt chromatin by causing loss of nucleosomes. This finding may limit the use of SR microscopy in telomere studies.

  19. Super-resolution optical microscopy study of telomere structure

    NASA Astrophysics Data System (ADS)

    Phipps, Mary Lisa; Goodwin, Peter M.; Martinez, Jennifer S.; Goodwin, Edwin H.

    2016-09-01

    Chromosome ends are shielded from exonucleolytic attack and inappropriate end-joining by terminal structures called telomeres; these structures are potential targets for anticancer drugs. Telomeres are composed of a simple DNA sequence (5‧-TTAGGG-3‧ in humans) repeated more than a thousand times, a short 3‧ single-stranded overhang, and numerous proteins. Electron microscopy has shown that the 3‧ overhang pairs with the complementary strand at an internal site creating a small displacement loop and a large double-stranded "t-loop." Our goal is to determine whether all telomeres adopt the t-loop configuration, or whether there are two or more distinct configurations. Progress in optimizing super-resolution (SR) microscopy for this ongoing investigation is reported here. Results suggest that under certain conditions sample preparation procedures may disrupt chromatin by causing loss of nucleosomes. This finding may limit the use of SR microscopy in telomere studies.

  20. Different requirements of functional telomeres in neural stem cells and terminally differentiated neurons.

    PubMed

    Lobanova, Anastasia; She, Robert; Pieraut, Simon; Clapp, Charlie; Maximov, Anton; Denchi, Eros Lazzerini

    2017-04-01

    Telomeres have been studied extensively in peripheral tissues, but their relevance in the nervous system remains poorly understood. Here, we examine the roles of telomeres at distinct stages of murine brain development by using lineage-specific genetic ablation of TRF2, an essential component of the shelterin complex that protects chromosome ends from the DNA damage response machinery. We found that functional telomeres are required for embryonic and adult neurogenesis, but their uncapping has surprisingly no detectable consequences on terminally differentiated neurons. Conditional knockout of TRF2 in post-mitotic immature neurons had virtually no detectable effect on circuit assembly, neuronal gene expression, and the behavior of adult animals despite triggering massive end-to-end chromosome fusions across the brain. These results suggest that telomeres are dispensable in terminally differentiated neurons and provide mechanistic insight into cognitive abnormalities associated with aberrant telomere length in humans. © 2017 Lobanova et al.; Published by Cold Spring Harbor Laboratory Press.

  1. Baseline biopsychosocial determinants of telomere length and 6-year attrition rate.

    PubMed

    Révész, Dóra; Milaneschi, Yuri; Terpstra, Erik M; Penninx, Brenda W J H

    2016-05-01

    Short leukocyte telomere length (TL) and accelerated telomere attrition have been associated with various deleterious health outcomes, although their determinants have not been explored collectively in a large-scale study. Leukocyte TL was measured (baseline N=2936; 6-year follow-up N=1860) in participants (18-65 years) from the NESDA study. Baseline determinants of TL included sociodemographics, lifestyle, chronic diseases, psychosocial stressors, and metabolic and physiological stress markers. Multivariate linear regression models were used to examine the associations between these determinants and (1) baseline TL, and (2) 6-year TL change. Multinomial logistic regression analyses were used to examine the predictors of telomere attrition and lengthening, as compared to stable TL. Short baseline TL was associated with older age, male sex, non-European ethnicity, cigarette smoking, recent life events, and higher triglycerides, glucose and pre-ejection period (R(2)=11.3%). The 6-year telomere attrition was inversely associated with baseline TL (R(2)=51.6%); also older age, long sleep, not having a partner, high childhood trauma index, and gastrointestinal disease were associated with 6-year TL attrition (additional R(2)=3.7%). Telomere attrition seemed to have slightly more predictors than lengthening. Sociodemographic, lifestyle, psychosocial stress and metabolic and physiological stress factors are cross-sectionally linked with TL. Telomere attrition over six years was strongly associated with baseline TL, suggesting an internal homeostatic influence. Modulation of the identified determinants may become target of future studies to promote telomere maintenance and healthy aging. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Quantification of telomere length by FISH and laser scanning cytometry

    NASA Astrophysics Data System (ADS)

    Mahoney, John E.; Sahin, Ergun; Jaskelioff, Mariela; Chin, Lynda; DePinho, Ronald A.; Protopopov, Alexei I.

    2008-02-01

    Telomeres play a critical role in the maintenance of chromosomal stability. Telomere erosion, coupled with loss of DNA damage checkpoint function, results in genomic instability that promotes the development of cancer. The critical role of telomere dynamics in cancer has motivated the development of technologies designed to monitor telomere reserves in a highly quantitative and high-throughput manner in humans and model organisms. To this end, we have adapted and modified two established technologies, telomere-FISH and laser scanning cytometry. Specifically, we have produced a number of enhancements to the iCys LSC (CompuCyte) package including software updates, use of 60X dry objectives, and increased spatial resolution by 0.2 um size of stage steps. In addition, the 633 nm HeNe laser was replaced with a 532 nm green diode laser to better match the viewing options. Utilization of telomere-deficient mouse cells with short dysfunctional telomeres and matched telomerase reconstituted cultures demonstrated significantly higher mean integral specific fluorescence values for mTR transfectants relative to empty vector controls: 4.485M vs. 1.362M (p<0.0001). Histograms of average telomere intensities for individual cells were obtained and demonstrated intercellular heterogeneity in telomere lengths. The validation of the approach derives from a strong correlation between iCys LSC values and Southern blotting. This validated method greatly increases our experimental throughput and objectivity.

  3. Genetic Inactivation of ATRX Leads to a Decrease in the Amount of Telomeric Cohesin and Level of Telomere Transcription in Human Glioma Cells

    PubMed Central

    Eid, Rita; Demattei, Marie-Véronique; Episkopou, Harikleia; Augé-Gouillou, Corinne; Decottignies, Anabelle; Grandin, Nathalie

    2015-01-01

    Mutations in ATRX (alpha thalassemia/mental retardation syndrome X-linked), a chromatin-remodeling protein, are associated with the telomerase-independent ALT (alternative lengthening of telomeres) pathway of telomere maintenance in several types of cancer, including human gliomas. In telomerase-positive glioma cells, we found by immunofluorescence that ATRX localized not far from the chromosome ends but not exactly at the telomere termini. Chromatin immunoprecipitation (ChIP) experiments confirmed a subtelomeric localization for ATRX, yet short hairpin RNA (shRNA)-mediated genetic inactivation of ATRX failed to trigger the ALT pathway. Cohesin has been recently shown to be part of telomeric chromatin. Here, using ChIP, we showed that genetic inactivation of ATRX provoked diminution in the amount of cohesin in subtelomeric regions of telomerase-positive glioma cells. Inactivation of ATRX also led to diminution in the amount of TERRAs, noncoding RNAs resulting from transcription of telomeric DNA, as well as to a decrease in RNA polymerase II (RNAP II) levels at the telomeres. Our data suggest that ATRX might establish functional interactions with cohesin on telomeric chromatin in order to control TERRA levels and that one or the other or both of these events might be relevant to the triggering of the ALT pathway in cancer cells that exhibit genetic inactivation of ATRX. PMID:26055325

  4. Pulmonary phenotypes associated with genetic variation in telomere-related genes.

    PubMed

    Hoffman, Thijs W; van Moorsel, Coline H M; Borie, Raphael; Crestani, Bruno

    2018-05-01

    Genomic mutations in telomere-related genes have been recognized as a cause of familial forms of idiopathic pulmonary fibrosis (IPF). However, it has become increasingly clear that telomere syndromes and telomere shortening are associated with various types of pulmonary disease. Additionally, it was found that also single nucleotide polymorphisms (SNPs) in telomere-related genes are risk factors for the development of pulmonary disease. This review focuses on recent updates on pulmonary phenotypes associated with genetic variation in telomere-related genes. Genomic mutations in seven telomere-related genes cause pulmonary disease. Pulmonary phenotypes associated with these mutations range from many forms of pulmonary fibrosis to emphysema and pulmonary vascular disease. Telomere-related mutations account for up to 10% of sporadic IPF, 25% of familial IPF, 10% of connective-tissue disease-associated interstitial lung disease, and 1% of COPD. Mixed disease forms have also been found. Furthermore, SNPs in TERT, TERC, OBFC1, and RTEL1, as well as short telomere length, have been associated with several pulmonary diseases. Treatment of pulmonary disease caused by telomere-related gene variation is currently based on disease diagnosis and not on the underlying cause. Pulmonary phenotypes found in carriers of telomere-related gene mutations and SNPs are primarily pulmonary fibrosis, sometimes emphysema and rarely pulmonary vascular disease. Genotype-phenotype relations are weak, suggesting that environmental factors and genetic background of patients determine disease phenotypes to a large degree. A disease model is presented wherever genomic variation in telomere-related genes cause specific pulmonary disease phenotypes whenever triggered by environmental exposure, comorbidity, or unknown factors.

  5. Long telomere length predicts poor clinical outcome in esophageal cancer patients.

    PubMed

    Lv, Yanyan; Zhang, Yong; Li, Xinru; Ren, Xiaojuan; Wang, Meichen; Tian, Sijia; Hou, Peng; Shi, Bingyin; Yang, Qi

    2017-02-01

    Abnormal telomere length is widely reported in various human cancers, and it is considered to be an important hallmark of cancer. However, there is remarkably little consensus on the value of telomere length in the prognostic evaluation of esophageal cancers. Here, we attempted to determine the association of variable telomere length with clinical outcome of esophageal cancer patients. Using real-time quantitative PCR, we examined relative telomere lengths (RTL) in a cohort of esophageal cancer and normal esophageal tissues, and statistically investigated the association between RTL and clinical outcomes of esophageal cancer patients. The majority of esophageal cancers in this study had longer RTLs as compared to adjacent non-tumor tissues. Enhanced tumor RTL was associated with smoking habit, poor differentiation, advanced tumor stage, lymph node metastasis and cancer related death. In particular, a close relationship between longer RTL and poor survival was fully demonstrated by using cox regression and Kaplan-Maier survival curves. We found frequent telomere elongation in esophageal cancer tissues, and demonstrated longer RTL may be an independent poor prognostic factor for esophageal cancer patients. Copyright © 2016 Elsevier GmbH. All rights reserved.

  6. Leukocyte Telomere Length in Newborns: Implications for the Role of Telomeres in Human Disease

    PubMed Central

    Factor-Litvak, Pam; Susser, Ezra; Kezios, Katrina; McKeague, Ian; Kark, Jeremy D.; Hoffman, Matthew; Kimura, Masayuki; Wapner, Ronald

    2016-01-01

    BACKGROUND AND OBJECTIVE: In adults, leukocyte telomere length (LTL) is variable, familial, and longer in women and in offspring conceived by older fathers. Although short LTL is associated with atherosclerotic cardiovascular disease, long LTL is associated with major cancers. The prevailing notion is that LTL is a “telomeric clock,” whose movement (expressed in LTL attrition) reflects the pace of aging. Accordingly, individuals with short LTL are considered to be biologically older than their peers. Recent studies suggest that LTL is largely determined before adulthood. We examined whether factors that largely characterize LTL in adults also influence LTL in newborns. METHODS: LTL was measured in blood samples from 490 newborns and their parents. RESULTS: LTL (mean ± SD) was longer (9.50 ± 0.70 kb) in newborns than in their mothers (7.92 ± 0.67 kb) and fathers (7.70 ± 0.71 kb) (both P < .0001); there was no difference in the variance of LTL among the 3 groups. Newborn LTL correlated more strongly with age-adjusted LTL in mothers (r = 0.47; P < .01) than in fathers (r = 0.36; P < .01) (P for interaction = .02). Newborn LTL was longer by 0.144 kb in girls than in boys (P = .02), and LTL was longer by 0.175 kb in mothers than in fathers (P < .0001). For each 1-year increase in father’s age, newborn LTL increased by 0.016 kb (95% confidence interval: 0.04 to 0.28) (P = .0086). CONCLUSIONS: The large LTL variation across newborns challenges the telomeric clock model. Having inherently short or long LTL may be largely determined at birth, anteceding by decades disease manifestation in adults. PMID:26969272

  7. Air pollution, ethnicity and telomere length in east London schoolchildren: An observational study.

    PubMed

    Walton, Robert T; Mudway, Ian S; Dundas, Isobel; Marlin, Nadine; Koh, Lee C; Aitlhadj, Layla; Vulliamy, Tom; Jamaludin, Jeenath B; Wood, Helen E; Barratt, Ben M; Beevers, Sean; Dajnak, David; Sheikh, Aziz; Kelly, Frank J; Griffiths, Chris J; Grigg, Jonathan

    2016-11-01

    Short telomeres are associated with chronic disease and early mortality. Recent studies in adults suggest an association between telomere length and exposure to particulate matter, and that ethnicity may modify the relationship. However associations in children are unknown. We examined associations between air pollution and telomere length in an ethnically diverse group of children exposed to high levels of traffic derived pollutants, particularly diesel exhaust, and to environmental tobacco smoke. Oral DNA from 333 children (8-9years) participating in a study on air quality and respiratory health in 23 inner city London schools was analysed for relative telomere length using monochrome multiplex qPCR. Annual, weekly and daily exposures to nitrogen oxides and particulate matter were obtained from urban dispersion models (2008-10) and tobacco smoke by urinary cotinine. Ethnicity was assessed by self-report and continental ancestry by analysis of 28 random genomic markers. We used linear mixed effects models to examine associations with telomere length. Telomere length increased with increasing annual exposure to NO x (model coefficient 0.003, [0.001, 0.005], p<0.001), NO 2 (0.009 [0.004, 0.015], p<0.001), PM 2.5 (0.041, [0.020, 0.063], p<0.001) and PM 10 (0.096, [0.044, 0.149], p<0.001). There was no association with environmental tobacco smoke. Telomere length was increased in children reporting black ethnicity (22% [95% CI 10%, 36%], p<0.001) CONCLUSIONS: Pollution exposure is associated with longer telomeres in children and genetic ancestry is an important determinant of telomere length. Further studies should investigate both short and long-term associations between pollutant exposure and telomeres in childhood and assess underlying mechanisms. Copyright © 2016. Published by Elsevier Ltd.

  8. The association of telomere length and genetic variation in telomere biology genes.

    PubMed

    Mirabello, Lisa; Yu, Kai; Kraft, Peter; De Vivo, Immaculata; Hunter, David J; Prescott, Jennifer; Wong, Jason Y Y; Chatterjee, Nilanjan; Hayes, Richard B; Savage, Sharon A

    2010-09-01

    Telomeres cap chromosome ends and are critical for genomic stability. Many telomere-associated proteins are important for telomere length maintenance. Recent genome-wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) in genes encoding telomere-associated proteins (RTEL1 and TERT-CLPTM1) as markers of cancer risk. We conducted an association study of telomere length and 743 SNPs in 43 telomere biology genes. Telomere length in peripheral blood DNA was determined by Q-PCR in 3,646 participants from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial and Nurses' Health Study. We investigated associations by SNP, gene, and pathway (functional group). We found no associations between telomere length and SNPs in TERT-CLPTM1L or RTEL1. Telomere length was not significantly associated with specific functional groups. Thirteen SNPs from four genes (MEN1, MRE11A, RECQL5, and TNKS) were significantly associated with telomere length. The strongest findings were in MEN1 (gene-based P=0.006), menin, which associates with the telomerase promoter and may negatively regulate telomerase. This large association study did not find strong associations with telomere length. The combination of limited diversity and evolutionary conservation suggest that these genes may be under selective pressure. More work is needed to explore the role of genetic variants in telomere length regulation. Published 2010 Wiley-Liss, Inc.

  9. Short placental telomere was associated with cadmium pollution in an electronic waste recycling town in China.

    PubMed

    Lin, Shuiqin; Huo, Xia; Zhang, Qingying; Fan, Xiaojuan; Du, Li; Xu, Xijin; Qiu, Shaoshan; Zhang, Yuling; Wang, Yun; Gu, Jiang

    2013-01-01

    In Guiyu, an electronic waste recycling site near Shantou, Guangdong province, China, primitive ways of e-waste processing have caused severe cadmium and lead pollution to the local residents. However, the possible effects of cadmium or lead pollution to genomic integrity of the local residents have not been investigated. We examined the possible relationship between cadmium and lead concentrations in placenta and placental telomere length in Guiyu and compared the data with that of a non-polluted town. Graphite furnace atomic absorption spectrometry and real-time PCR were used to determine placental cadmium and lead concentrations, and placental telomere length. We found that placental cadmium concentration was negatively correlated with placental telomere length (r = -0.138, p = 0.013). We also found that placental cadmium concentration of 0.0294 µg/g might be a critical point at which attrition of placental telomere commenced. No significant correlation between placental lead concentration and placental telomere length was detected (r = 0.027, p = 0.639). Our data suggest that exposure to cadmium pollution during pregnancy may be a risk factor for shortened placental telomere length that is known to be related to cancer development and aging. Furthermore, grave consequence on the offspring from pregnancies in e-waste polluted area is indicated.

  10. Short Placental Telomere was Associated with Cadmium Pollution in an Electronic Waste Recycling Town in China

    PubMed Central

    Zhang, Qingying; Fan, Xiaojuan; Du, Li; Xu, Xijin; Qiu, Shaoshan; Zhang, Yuling; Wang, Yun; Gu, Jiang

    2013-01-01

    In Guiyu, an electronic waste recycling site near Shantou, Guangdong province, China, primitive ways of e-waste processing have caused severe cadmium and lead pollution to the local residents. However, the possible effects of cadmium or lead pollution to genomic integrity of the local residents have not been investigated. We examined the possible relationship between cadmium and lead concentrations in placenta and placental telomere length in Guiyu and compared the data with that of a non-polluted town. Graphite furnace atomic absorption spectrometry and real-time PCR were used to determine placental cadmium and lead concentrations, and placental telomere length. We found that placental cadmium concentration was negatively correlated with placental telomere length (r = −0.138, p = 0.013). We also found that placental cadmium concentration of 0.0294 µg/g might be a critical point at which attrition of placental telomere commenced. No significant correlation between placental lead concentration and placental telomere length was detected (r = 0.027, p = 0.639). Our data suggest that exposure to cadmium pollution during pregnancy may be a risk factor for shortened placental telomere length that is known to be related to cancer development and aging. Furthermore, grave consequence on the offspring from pregnancies in e-waste polluted area is indicated. PMID:23565277

  11. Zen meditation, Length of Telomeres, and the Role of Experiential Avoidance and Compassion.

    PubMed

    Alda, Marta; Puebla-Guedea, Marta; Rodero, Baltasar; Demarzo, Marcelo; Montero-Marin, Jesus; Roca, Miquel; Garcia-Campayo, Javier

    Mindfulness refers to an awareness that emerges by intentionally focusing on the present experience in a nonjudgmental or evaluative manner. Evidence regarding its efficacy has been increasing exponentially, and recent research suggests that the practice of meditation is associated with longer leukocyte telomere length. However, the psychological mechanisms underlying this potential relationship are unknown. We examined the telomere lengths of a group of 20 Zen meditation experts and another 20 healthy matched comparison participants who had not previously meditated. We also measured multiple psychological variables related to meditation practice. Genomic DNA was extracted for telomere measurement using a Life Length proprietary program. High-throughput quantitative fluorescence in situ hybridization (HT-Q-FISH) was used to measure the telomere length distribution and the median telomere length (MTL). The meditators group had a longer MTL ( p  = 0.005) and a lower percentage of short telomeres in individual cells ( p  = 0.007) than those in the comparison group. To determine which of the psychological variables contributed more to telomere maintenance, two regression analyses were conducted. In the first model, which applied to the MTL, the following three factors were significant: age, absence of experiential avoidance, and Common Humanity subscale of the Self Compassion Scale. Similarly, in the model that examined the percentage of short telomeres, the same factors were significant: age, absence of experiential avoidance, and Common Humanity subscale of the Self Compassion Scale. Although limited by a small sample size, these results suggest that the absence of experiential avoidance of negative emotions and thoughts is integral to the connection between meditation and telomeres.

  12. Genetic Inactivation of ATRX Leads to a Decrease in the Amount of Telomeric Cohesin and Level of Telomere Transcription in Human Glioma Cells.

    PubMed

    Eid, Rita; Demattei, Marie-Véronique; Episkopou, Harikleia; Augé-Gouillou, Corinne; Decottignies, Anabelle; Grandin, Nathalie; Charbonneau, Michel

    2015-08-01

    Mutations in ATRX (alpha thalassemia/mental retardation syndrome X-linked), a chromatin-remodeling protein, are associated with the telomerase-independent ALT (alternative lengthening of telomeres) pathway of telomere maintenance in several types of cancer, including human gliomas. In telomerase-positive glioma cells, we found by immunofluorescence that ATRX localized not far from the chromosome ends but not exactly at the telomere termini. Chromatin immunoprecipitation (ChIP) experiments confirmed a subtelomeric localization for ATRX, yet short hairpin RNA (shRNA)-mediated genetic inactivation of ATRX failed to trigger the ALT pathway. Cohesin has been recently shown to be part of telomeric chromatin. Here, using ChIP, we showed that genetic inactivation of ATRX provoked diminution in the amount of cohesin in subtelomeric regions of telomerase-positive glioma cells. Inactivation of ATRX also led to diminution in the amount of TERRAs, noncoding RNAs resulting from transcription of telomeric DNA, as well as to a decrease in RNA polymerase II (RNAP II) levels at the telomeres. Our data suggest that ATRX might establish functional interactions with cohesin on telomeric chromatin in order to control TERRA levels and that one or the other or both of these events might be relevant to the triggering of the ALT pathway in cancer cells that exhibit genetic inactivation of ATRX. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  13. Expression of Telomere-Associated Proteins is Interdependent to Stabilize Native Telomere Structure and Telomere Dysfunction by G-Quadruplex Ligand Causes TERRA Upregulation.

    PubMed

    Sadhukhan, Ratan; Chowdhury, Priyanka; Ghosh, Sourav; Ghosh, Utpal

    2018-06-01

    Telomere DNA can form specialized nucleoprotein structure with telomere-associated proteins to hide free DNA ends or G-quadruplex structures under certain conditions especially in presence of G-quadruplex ligand. Telomere DNA is transcribed to form non-coding telomere repeat-containing RNA (TERRA) whose biogenesis and function is poorly understood. Our aim was to find the role of telomere-associated proteins and telomere structures in TERRA transcription. We silenced four [two shelterin (TRF1, TRF2) and two non-shelterin (PARP-1, SLX4)] telomere-associated genes using siRNA and verified depletion in protein level. Knocking down of one gene modulated expression of other telomere-associated genes and increased TERRA from 10q, 15q, XpYp and XqYq chromosomes in A549 cells. Telomere was destabilized or damaged by G-quadruplex ligand pyridostatin (PDS) and bleomycin. Telomere dysfunction-induced foci (TIFs) were observed for each case of depletion of proteins, treatment with PDS or bleomycin. TERRA level was elevated by PDS and bleomycin treatment alone or in combination with depletion of telomere-associated proteins.

  14. Impact of chemotherapy on telomere-length in sporadic and familial breast cancer patients

    PubMed Central

    Benitez-Buelga, C.; Sanchez-Barroso, L.; Gallardo, M.; Apellániz-Ruiz, María; Inglada-Pérez, L.; Yanowski, K.; Carrillo, J.; Garcia-Estevez, L.; Calvo, I.; Perona, R.; Urioste, M.; Osorio, A.; Blasco, MA.; Rodriguez-Antona, C.; Benitez, J.

    2015-01-01

    Purpose Recently, we observed that telomeres of BRCA1/2 mutation carriers were shorter than those of controls or sporadic breast cancer patients, suggesting that mutations in these genes might be responsible for this event. Given the contradictory results reported in the literature, we tested whether other parameters, such as chemotherapy, could be modifying telomere-length. Methods We performed a cross-sectional study measuring leukocyte telomere-length of 266 sporadic breasts cancer patients treated with first-line chemotherapy, with a median follow up of 240 days. Additionally, we performed both cross-sectional and longitudinal studies in a series of 236 familial breast cancer patients that included affected and non-affected BRCA1/2 mutation carriers. We have measured in leukocytes from peripheral blood: The telomere-length, percentage of short telomeres (<3Kb), telomerase activity levels and the annual telomere shortening speed. Results In sporadic cases we found that chemotherapy exerts a transient telomere shortening effect (around 2 years) that varies depending on the drug combination. In familial cases, only patients receiving treatment were associated with telomere shortening but they recovered normal telomere-length after a period of two years. Conclusion Chemotherapy affects telomere-length and should be considered in the studies that correlate telomere-length with disease susceptibility. PMID:25528024

  15. Realizing the Translational Potential of Telomere Length Variation as a Tissue-Based Prognostic Marker for Prostate Cancer

    DTIC Science & Technology

    2014-10-01

    Telomere Length Variation as a Tissue- Based Prognostic Marker for Prostate Cancer PRINCIPAL INVESTIGATOR: Elizabeth A. Platz CONTRACTING...Translational Potential of Telomere Length Variation as a Tissue- Based Prognostic Marker for Prostate Cancer 5b. GRANT NUMBER W81XWH-12-1-0545 5c...combination of telomere length variability in prostate cancer cells and short telomere length in cancer-associated stromal cells is an independent

  16. Mutations in CTC1, Encoding the CTS Telomere Maintenance Complex Component 1, Cause Cerebroretinal Microangiopathy with Calcifications and Cysts

    PubMed Central

    Polvi, Anne; Linnankivi, Tarja; Kivelä, Tero; Herva, Riitta; Keating, James P.; Mäkitie, Outi; Pareyson, Davide; Vainionpää, Leena; Lahtinen, Jenni; Hovatta, Iiris; Pihko, Helena; Lehesjoki, Anna-Elina

    2012-01-01

    Cerebroretinal microangiopathy with calcifications and cysts (CRMCC) is a rare multisystem disorder characterized by extensive intracranial calcifications and cysts, leukoencephalopathy, and retinal vascular abnormalities. Additional features include poor growth, skeletal and hematological abnormalities, and recurrent gastrointestinal bleedings. Autosomal-recessive inheritance has been postulated. The pathogenesis of CRMCC is unknown, but its phenotype has key similarities with Revesz syndrome, which is caused by mutations in TINF2, a gene encoding a member of the telomere protecting shelterin complex. After a whole-exome sequencing approach in four unrelated individuals with CRMCC, we observed four recessively inherited compound heterozygous mutations in CTC1, which encodes the CTS telomere maintenance complex component 1. Sanger sequencing revealed seven more compound heterozygous mutations in eight more unrelated affected individuals. Two individuals who displayed late-onset cerebral findings, a normal fundus appearance, and no systemic findings did not have CTC1 mutations, implying that systemic findings are an important indication for CTC1 sequencing. Of the 11 mutations identified, four were missense, one was nonsense, two resulted in in-frame amino acid deletions, and four were short frameshift-creating deletions. All but two affected individuals were compound heterozygous for a missense mutation and a frameshift or nonsense mutation. No individuals with two frameshift or nonsense mutations were identified, which implies that severe disturbance of CTC1 function from both alleles might not be compatible with survival. Our preliminary functional experiments did not show evidence of severely affected telomere integrity in the affected individuals. Therefore, determining the underlying pathomechanisms associated with deficient CTC1 function will require further studies. PMID:22387016

  17. Repetitive telomeric sequences in chromosomal translocations involving chromosome 21

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qu, J.; Dallaire, L.; Fetni, R.

    Telomeres perform key functions in maintaining chromosome integrity. In some structural rearrangements the structure and polymorphism in human telomeres may play a significant role. However, of all the telomeric and subtelomeric sequences, only the terminal TTAGGG repeats are believed essential for telomere function. During the course of a study on the role of telomere structure and polymorphism in chromosomal rearrangements observed in families referred for prenatal diagnosis, we studied three cases in which chromosome 21 was involved. Repetitive TTAGGG sequences for all human chromosomes were used as probes (Oncor). Case 1, a de novo cryptic translocation (2;21) was initially identifiedmore » as monosomy 21 in a child with psychomotor delay and mild dysmorphism. Using a cosmid probe specific for region 21q22.3 and whole chromosome 21 specific painting probe, the long arm of 21 was found on the short arm of chromosome 2 with an interstitial telomere at the breakpoint junction. All the cells were monosomic for 21pter{yields}q21. Case 2 is a familial (19;21) translocation. GTG-banding and FISH with a satellite probe showed no apparent loss of material at the end of either 19q or 21q, with an interstitial telomere at the fusion site of the two intact chromosomes. In case 3, a four generation reciprocal (20;21) translocation, there was no interstitial telomere. The persistence of an interstitial telomere is a relatively rare event which can now be observed with in situ hybridization. Its study may lead to a better understanding of the dynamics of translocations and of chromosome imbalance.« less

  18. Cdc13 prevents telomere uncapping and Rad50-dependent homologous recombination

    PubMed Central

    Grandin, Nathalie; Damon, Christelle; Charbonneau, Michel

    2001-01-01

    Cdc13 performs an essential function in telomere end protection in budding yeast. Here, we analyze the consequences on telomere dynamics of cdc13-induced telomeric DNA damage in proliferating cells. Checkpoint-deficient cdc13-1 cells accumulated DNA damage and eventually senesced. However, these telomerase-proficient cells could survive by using homologous recombination but, contrary to telomerase-deficient cells, did so without prior telomere shortening. Strikingly, homologous recombination in cdc13-1 mec3, as well as in telomerase-deficient cdc13-1 cells, which were Rad52- and Rad50-dependent but Rad51-independent, exclusively amplified the TG1–3 repeats. This argues that not only short telomeres are substrates for type II recombination. The Cdc13-1 mutant protein harbored a defect in its association with Stn1 and Ten1 but also an additional, unknown, defect that could not be cured by expressing a Cdc13-1– Ten1–Stn1 fusion. We propose that Cdc13 prevents telomere uncapping and inhibits recombination between telomeric sequences through a pathway distinct from and complementary to that used by telomerase. PMID:11689452

  19. Tired telomeres: Poor global sleep quality, perceived stress, and telomere length in immune cell subsets in obese men and women.

    PubMed

    Prather, Aric A; Gurfein, Blake; Moran, Patricia; Daubenmier, Jennifer; Acree, Michael; Bacchetti, Peter; Sinclair, Elizabeth; Lin, Jue; Blackburn, Elizabeth; Hecht, Frederick M; Epel, Elissa S

    2015-07-01

    Poor sleep quality and short sleep duration are associated with increased incidence and progression of a number of chronic health conditions observed at greater frequency among the obese and those experiencing high levels of stress. Accelerated cellular aging, as indexed by telomere attrition in immune cells, is a plausible pathway linking sleep and disease risk. Prior studies linking sleep and telomere length are mixed. One factor may be reliance on leukocytes, which are composed of varied immune cell types, as the sole measure of telomere length. To better clarify these associations, we investigated the relationships of global sleep quality, measured by the Pittsburgh Sleep Quality Index (PSQI), and diary-reported sleep duration with telomere length in different immune cell subsets, including granulocytes, peripheral blood mononuclear cells (PBMCs), CD8+ and CD4+ T lymphocytes, and B lymphocytes in a sample of 87 obese men and women (BMI mean=35.4, SD=3.6; 81.6% women; 62.8% Caucasian). Multiple linear regression analyses were performed adjusting for age, gender, race, education, BMI, sleep apnea risk, and perceived stress. Poorer PSQI global sleep quality was associated with statistically significantly shorter telomere length in lymphocytes but not granulocytes and in particular CD8+ T cells (b=-56.8 base pairs per one point increase in PSQI, SE=20.4, p=0.007) and CD4+ T cells (b=-37.2, SE=15.9, p=0.022). Among separate aspects of global sleep quality, low perceived sleep quality and decrements in daytime function were most related to shorter telomeres. In addition, perceived stress moderated the sleep-CD8+ telomere association. Poorer global sleep quality predicted shorter telomere length in CD8+ T cells among those with high perceived stress but not in low stress participants. These findings provide preliminary evidence that poorer global sleep quality is related to telomere length in several immune cell types, which may serve as a pathway linking sleep and

  20. BLM helicase facilitates telomere replication during leading strand synthesis of telomeres

    PubMed Central

    Kosiyatrakul, Settapong T.

    2015-01-01

    Based on its in vitro unwinding activity on G-quadruplex (G4) DNA, the Bloom syndrome–associated helicase BLM is proposed to participate in telomere replication by aiding fork progression through G-rich telomeric DNA. Single molecule analysis of replicated DNA (SMARD) was used to determine the contribution of BLM helicase to telomere replication. In BLM-deficient cells, replication forks initiating from origins within the telomere, which copy the G-rich strand by leading strand synthesis, moved slower through the telomere compared with the adjacent subtelomere. Fork progression through the telomere was further slowed in the presence of a G4 stabilizer. Using a G4-specific antibody, we found that deficiency of BLM, or another G4-unwinding helicase, the Werner syndrome-associated helicase WRN, resulted in increased G4 structures in cells. Importantly, deficiency of either helicase led to greater increases in G4 DNA detected in the telomere compared with G4 seen genome-wide. Collectively, our findings are consistent with BLM helicase facilitating telomere replication by resolving G4 structures formed during copying of the G-rich strand by leading strand synthesis. PMID:26195664

  1. RTEL1 dismantles T loops and counteracts telomeric G4-DNA to maintain telomere integrity.

    PubMed

    Vannier, Jean-Baptiste; Pavicic-Kaltenbrunner, Visnja; Petalcorin, Mark I R; Ding, Hao; Boulton, Simon J

    2012-05-11

    T loops and telomeric G-quadruplex (G4) DNA structures pose a potential threat to genome stability and must be dismantled to permit efficient telomere replication. Here we implicate the helicase RTEL1 in the removal of telomeric DNA secondary structures, which is essential for preventing telomere fragility and loss. In the absence of RTEL1, T loops are inappropriately resolved by the SLX4 nuclease complex, resulting in loss of the telomere as a circle. Depleting SLX4 or blocking DNA replication abolished telomere circles (TCs) and rescued telomere loss in RTEL1(-/-) cells but failed to suppress telomere fragility. Conversely, stabilization of telomeric G4-DNA or loss of BLM dramatically enhanced telomere fragility in RTEL1-deficient cells but had no impact on TC formation or telomere loss. We propose that RTEL1 performs two distinct functions at telomeres: it disassembles T loops and also counteracts telomeric G4-DNA structures, which together ensure the dynamics and stability of the telomere. Copyright © 2012 Elsevier Inc. All rights reserved.

  2. Realizing the Translational Potential of Telomere Length Variation as a Tissue Based Prognostic Marker for Prostate Cancer

    DTIC Science & Technology

    2016-10-01

    Award Number: W81XWH-12-1-0545 TITLE: Realizing the Translational Potential of Telomere Length Variation as a Tissue- Based Prognostic Marker for...30 Sep 2015 - 29 Sep 2016 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Realizing the Translational Potential of Telomere Length Variation as a Tissue...HPFS), whether the combination of telomere length variability in prostate cancer cells and short telomere length in cancer-associated stromal cells is

  3. Telomere Dynamics and Homeostasis in a Transmissible Cancer

    PubMed Central

    Ujvari, Beata; Pearse, Anne-Maree; Taylor, Robyn; Pyecroft, Stephen; Flanagan, Cassandra; Gombert, Sara; Papenfuss, Anthony T.; Madsen, Thomas; Belov, Katherine

    2012-01-01

    Background Devil Facial Tumour Disease (DFTD) is a unique clonal cancer that threatens the world's largest carnivorous marsupial, the Tasmanian devil (Sarcophilus harrisii) with extinction. This transmissible cancer is passed between individual devils by cell implantation during social interactions. The tumour arose in a Schwann cell of a single devil over 15 years ago and since then has expanded clonally, without showing signs of replicative senescence; in stark contrast to a somatic cell that displays a finite capacity for replication, known as the “Hayflick limit”. Methodology/Principal Findings In the present study we investigate the role of telomere length, measured as Telomere Copy Number (TCN), and telomerase and shelterin gene expression, as well as telomerase activity in maintaining hyperproliferation of Devil Facial Tumour (DFT) cells. Our results show that DFT cells have short telomeres. DFTD TCN does not differ between geographic regions or between strains. However, TCN has increased over time. Unlimited cell proliferation is likely to have been achieved through the observed up-regulation of the catalytic subunit of telomerase (TERT) and concomitant activation of telomerase. Up-regulation of the central component of shelterin, the TRF1-intercating nuclear factor 2 (TINF2) provides DFT a mechanism for telomere length homeostasis. The higher expression of both TERT and TINF2 may also protect DFT cells from genomic instability and enhance tumour proliferation. Conclusions/Significance DFT cells appear to monitor and regulate the length of individual telomeres: i.e. shorter telomeres are elongated by up-regulation of telomerase-related genes; longer telomeres are protected from further elongation by members of the shelterin complex, which may explain the lack of spatial and strain variation in DFT telomere copy number. The observed longitudinal increase in gene expression in DFT tissue samples and telomerase activity in DFT cell lines might indicate a

  4. Telomere dynamics and homeostasis in a transmissible cancer.

    PubMed

    Ujvari, Beata; Pearse, Anne-Maree; Taylor, Robyn; Pyecroft, Stephen; Flanagan, Cassandra; Gombert, Sara; Papenfuss, Anthony T; Madsen, Thomas; Belov, Katherine

    2012-01-01

    Devil Facial Tumour Disease (DFTD) is a unique clonal cancer that threatens the world's largest carnivorous marsupial, the Tasmanian devil (Sarcophilus harrisii) with extinction. This transmissible cancer is passed between individual devils by cell implantation during social interactions. The tumour arose in a Schwann cell of a single devil over 15 years ago and since then has expanded clonally, without showing signs of replicative senescence; in stark contrast to a somatic cell that displays a finite capacity for replication, known as the "Hayflick limit". In the present study we investigate the role of telomere length, measured as Telomere Copy Number (TCN), and telomerase and shelterin gene expression, as well as telomerase activity in maintaining hyperproliferation of Devil Facial Tumour (DFT) cells. Our results show that DFT cells have short telomeres. DFTD TCN does not differ between geographic regions or between strains. However, TCN has increased over time. Unlimited cell proliferation is likely to have been achieved through the observed up-regulation of the catalytic subunit of telomerase (TERT) and concomitant activation of telomerase. Up-regulation of the central component of shelterin, the TRF1-intercating nuclear factor 2 (TINF2) provides DFT a mechanism for telomere length homeostasis. The higher expression of both TERT and TINF2 may also protect DFT cells from genomic instability and enhance tumour proliferation. DFT cells appear to monitor and regulate the length of individual telomeres: i.e. shorter telomeres are elongated by up-regulation of telomerase-related genes; longer telomeres are protected from further elongation by members of the shelterin complex, which may explain the lack of spatial and strain variation in DFT telomere copy number. The observed longitudinal increase in gene expression in DFT tissue samples and telomerase activity in DFT cell lines might indicate a selection for more stable tumours with higher proliferative potential.

  5. Telomere Chromatin Condensation Assay (TCCA): a novel approach to study structural telomere integrity.

    PubMed

    Gonzalez-Vasconcellos, Iria; Alonso-Rodríguez, Silvia; López-Baltar, Isidoro; Fernández, José Luis

    2015-01-01

    Telomeres, the DNA-protein complexes located at the end of linear eukaryotic chromosomes are essential for genome stability. Improper higher-order chromatin organization at the chromosome ends can give rise to telomeric recombination and genomic instability. We report the development of an assay to quantify differences in the condensation of telomeric chromatin, thereby offering new opportunities to study telomere biology and stability. We have combined a DNA nuclease digestion with a quantitative PCR (qPCR) assay of telomeric DNA, which we term the Telomere Chromatin Condensation Assay (TCCA). By quantifying the relative quantities of telomeric DNA that are progressively digested with the exonuclease Bal 31 the method can discriminate between different levels of telomeric chromatin condensation. The structural chromatin packaging at telomeres shielded against exonuclease digestion delivered an estimate, which we term Chromatin Protection Factor (CPF) that ranged from 1.7 to 2.3 fold greater than that present in unpacked DNA. The CPF was significantly decreased when cell cultures were incubated with the DNA hypomethylating agent 5-azacytidine, demonstrating the ability of the TCCA assay to discriminate between packaging levels of telomeric DNA. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. HIV Infection Is Associated with Shortened Telomere Length in Ugandans with Suspected Tuberculosis

    PubMed Central

    Auld, Elizabeth; Lin, Jue; Chang, Emily; Byanyima, Patrick; Ayakaka, Irene; Musisi, Emmanuel; Worodria, William; Davis, J. Lucian; Segal, Mark; Blackburn, Elizabeth; Huang, Laurence

    2016-01-01

    Introduction HIV infection is a risk factor for opportunistic pneumonias such as tuberculosis (TB) and for age-associated health complications. Short telomeres, markers of biological aging, are also associated with an increased risk of age-associated diseases and mortality. Our goals were to use a single cohort of HIV-infected and HIV-uninfected individuals hospitalized with pneumonia to assess whether shortened telomere length was associated with HIV infection, TB diagnosis, and 2-month mortality. Methods This was a sub-study of the IHOP Study, a prospective observational study. Participants consisted of 184 adults admitted to Mulago Hospital in Kampala, Uganda who underwent evaluation for suspected TB and were followed for 2 months. Standardized questionnaires were administered to collect demographic and clinical data. PBMCs were isolated and analyzed using quantitative PCR to determine telomere length. The association between HIV infection, demographic and clinical characteristics, and telomere length was assessed, as were the associations between telomere length, TB diagnosis and 2-month mortality. Variables with a P≤0.2 in bivariate analysis were included in multivariate models. Results No significant demographic or clinical differences were observed between the HIV-infected and HIV-uninfected subjects. Older age (P<0.0001), male gender (P = 0.04), total pack-years smoked (P<0.001), alcohol consumption in the past year (P = 0.12), and asthma (P = 0.08) were all associated (P≤0.2) with shorter telomere length in bivariate analysis. In multivariate analysis adjusting for these five variables, HIV-positive participants had significantly shorter telomeres than HIV-negative participants (β = -0.0621, 95% CI -0.113 to -0.011, P = 0.02). Shortened telomeres were not associated with TB or short-term mortality. Conclusions The association between HIV infection and shorter telomeres suggests that HIV may play a role in cellular senescence and biological aging and

  7. Ageing and the telomere connection: An intimate relationship with inflammation.

    PubMed

    Zhang, Jingwen; Rane, Grishma; Dai, Xiaoyun; Shanmugam, Muthu K; Arfuso, Frank; Samy, Ramar Perumal; Lai, Mitchell Kim Peng; Kappei, Dennis; Kumar, Alan Prem; Sethi, Gautam

    2016-01-01

    Telomeres are the heterochromatic repeat regions at the ends of eukaryotic chromosomes, whose length is considered to be a determinant of biological ageing. Normal ageing itself is associated with telomere shortening. Here, critically short telomeres trigger senescence and eventually cell death. This shortening rate may be further increased by inflammation and oxidative stress and thus affect the ageing process. Apart from shortened or dysfunctional telomeres, cells undergoing senescence are also associated with hyperactivity of the transcription factor NF-κB and overexpression of inflammatory cytokines such as TNF-α, IL-6, and IFN-γ in circulating macrophages. Interestingly, telomerase, a reverse transcriptase that elongates telomeres, is involved in modulating NF-κB activity. Furthermore, inflammation and oxidative stress are implicated as pre-disease mechanisms for chronic diseases of ageing such as neurodegenerative diseases, cardiovascular disease, and cancer. To date, inflammation and telomere shortening have mostly been studied individually in terms of ageing and the associated disease phenotype. However, the interdependent nature of the two demands a more synergistic approach in understanding the ageing process itself and for developing new therapeutic approaches. In this review, we aim to summarize the intricate association between the various inflammatory molecules and telomeres that together contribute to the ageing process and related diseases. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Telomere Length, Current Perceived Stress, and Urinary Stress Hormones in Women

    PubMed Central

    Parks, Christine G.; Miller, Diane B.; McCanlies, Erin C.; Cawthon, Richard M.; Andrew, Michael E.; DeRoo, Lisa A.; Sandler, Dale P.

    2009-01-01

    Telomeres are repetitive DNA sequences that cap and protect the ends of chromosomes; critically short telomeres may lead to cellular senescence or carcinogenic transformation. Previous findings suggest a link between psychosocial stress, shorter telomeres, and chronic disease risk. This cross-sectional study examined relative telomere length in relation to perceived stress and urinary stress hormones in a sample of participants (n = 647) in the National Institute of Environmental Health Sciences Sister Study, a cohort of women ages 35 to 74 years who have a sister with breast cancer. Average leukocyte telomere length was determined by quantitative PCR. Current stress was assessed using the Perceived Stress Scale and creatinine-adjusted neuroendocrine hormones in first morning urines. Linear regression models estimated differences in telomere length base pairs (bp) associated with stress measures adjusted for age, race, smoking, and obesity. Women with higher perceived stress had somewhat shorter telomeres [adjusted difference of −129bp for being at or above moderate stress levels; 95% confidence interval (CI), −292 to 33], but telomere length did not decrease monotonically with higher stress levels. Shorter telomeres were independently associated with increasing age (−27bp/year), obesity, and current smoking. Significant stress-related differences in telomere length were seen in women ages 55 years and older (−289bp; 95% CI, −519 to −59), those with recent major losses (−420bp; 95% CI, −814 to −27), and those with above-average urinary catecholamines (e.g., epinephrine: −484bp; 95% CI, −709 to −259). Although current perceived stress was only modestly associated with shorter telomeres in this broad sample of women, our findings suggest the effect of stress on telomere length may vary depending on neuroendocrine responsiveness, external stressors, and age. PMID:19190150

  9. Interstitial telomeric repeats are not preferentially involved in radiation-induced chromosome aberrations in human cells.

    PubMed

    Desmaze, C; Pirzio, L M; Blaise, R; Mondello, C; Giulotto, E; Murnane, J P; Sabatier, L

    2004-01-01

    Telomeric repeat sequences, located at the end of eukaryotic chromosomes, have been detected at intrachromosomal locations in many species. Large blocks of telomeric sequences are located near the centromeres in hamster cells, and have been reported to break spontaneously or after exposure to ionizing radiation, leading to chromosome aberrations. In human cells, interstitial telomeric sequences (ITS) can be composed of short tracts of telomeric repeats (less than twenty), or of longer stretches of exact and degenerated hexanucleotides, mainly localized at subtelomeres. In this paper, we analyzed the radiation sensitivity of a naturally occurring short ITS localized in 2q31 and we found that this region is not a hot spot of radiation-induced chromosome breaks. We then selected a human cell line in which approximately 800 bp of telomeric DNA had been introduced by transfection into an internal euchromatic chromosomal region in chromosome 4q. In parallel, a cell line containing the plasmid without telomeric sequences was also analyzed. Both regions containing the transfected plasmids showed a higher frequency of radiation-induced breaks than expected, indicating that the instability of the regions containing the transfected sequences is not due to the presence of telomeric sequences. Taken together, our data show that ITS themselves do not enhance the formation of radiation-induced chromosome rearrangements in these human cell lines. Copyright 2003 S. Karger AG, Basel

  10. Telomere shortening associated with chromosome instability is arrested in immortal cells which express telomerase activity.

    PubMed Central

    Counter, C M; Avilion, A A; LeFeuvre, C E; Stewart, N G; Greider, C W; Harley, C B; Bacchetti, S

    1992-01-01

    Loss of telomeric DNA during cell proliferation may play a role in ageing and cancer. Since telomeres permit complete replication of eukaryotic chromosomes and protect their ends from recombination, we have measured telomere length, telomerase activity and chromosome rearrangements in human cells before and after transformation with SV40 or Ad5. In all mortal populations, telomeres shortened by approximately 65 bp/generation during the lifespan of the cultures. When transformed cells reached crisis, the length of the telomeric TTAGGG repeats was only approximately 1.5 kbp and many dicentric chromosomes were observed. In immortal cells, telomere length and frequency of dicentric chromosomes stabilized after crisis. Telomerase activity was not detectable in control or extended lifespan populations but was present in immortal populations. These results suggest that chromosomes with short (TTAGGG)n tracts are recombinogenic, critically shortened telomeres may be incompatible with cell proliferation and stabilization of telomere length by telomerase may be required for immortalization. Images PMID:1582420

  11. Telomere lengthening early in development.

    PubMed

    Liu, Lin; Bailey, Susan M; Okuka, Maja; Muñoz, Purificación; Li, Chao; Zhou, Lingjun; Wu, Chao; Czerwiec, Eva; Sandler, Laurel; Seyfang, Andreas; Blasco, Maria A; Keefe, David L

    2007-12-01

    Stem cells and cancer cells maintain telomere length mostly through telomerase. Telomerase activity is high in male germ line and stem cells, but is low or absent in mature oocytes and cleavage stage embryos, and then high again in blastocysts. How early embryos reset telomere length remains poorly understood. Here, we show that oocytes actually have shorter telomeres than somatic cells, but their telomeres lengthen remarkably during early cleavage development. Moreover, parthenogenetically activated oocytes also lengthen their telomeres, thus the capacity to elongate telomeres must reside within oocytes themselves. Notably, telomeres also elongate in the early cleavage embryos of telomerase-null mice, demonstrating that telomerase is unlikely to be responsible for the abrupt lengthening of telomeres in these cells. Coincident with telomere lengthening, extensive telomere sister-chromatid exchange (T-SCE) and colocalization of the DNA recombination proteins Rad50 and TRF1 were observed in early cleavage embryos. Both T-SCE and DNA recombination proteins decrease in blastocyst stage embryos, whereas telomerase activity increases and telomeres elongate only slowly. We suggest that telomeres lengthen during the early cleavage cycles following fertilization through a recombination-based mechanism, and that from the blastocyst stage onwards, telomerase only maintains the telomere length established by this alternative mechanism.

  12. Quantitative proteomic analysis of human breast epithelial cells with differential telomere length

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yu, Li-Rong; Chan, King C.; Tahara, Hidetoshi

    Telomeres play important functional roles in cell proliferation, cell cycle regulation, and genetic stability, in which telomere length is critical. In this study, quantitative proteome comparisons for the human breast epithelial cells with short and long telomeres (184-hTERT{sub L} vs. 184-hTERT{sub S} and 90P-hTERT{sub L} vs. 90P-hTERT{sub S}), resulting from transfection of the human telomerase reverse transcriptase (hTERT) gene, were performed using cleavable isotope-coded affinity tags. More than 2000 proteins were quantified in each comparative experiment, with approximately 77% of the proteins identified in both analyses. In the cells with long telomeres, significant and consistent alterations were observed in metabolismmore » (amino acid, nucleotide, and lipid metabolism), genetic information transmission (transcription and translation regulation, spliceosome and ribosome complexes), and cell signaling. Interestingly, the DNA excision repair pathway is enhanced, while integrin and its ligands are downregulated in the cells with long telomeres. These results may provide valuable information related to telomere functions.« less

  13. Opposing impacts on healthspan and longevity by limiting dietary selenium in Telomere Dysfunctional mice

    USDA-ARS?s Scientific Manuscript database

    Selenium (Se) is an essential trace element essential for optimal health. We investigated the role of Se in longevity and healthspan in a mouse model of healthy aging in humans with short telomeres. Telomere shortening is associated with aging, mortality and aging-related diseases. We found that whi...

  14. Regeneration of the Exocrine Pancreas Is Delayed in Telomere-Dysfunctional Mice

    PubMed Central

    von Figura, Guido; Wagner, Martin; Nalapareddy, Kodandaramireddy; Hartmann, Daniel; Kleger, Alexander; Guachalla, Luis Miguel; Rolyan, Harshvardhan; Adler, Guido; Rudolph, Karl Lenhard

    2011-01-01

    Introduction Telomere shortening is a cell-intrinsic mechanism that limits cell proliferation by induction of DNA damage responses resulting either in apoptosis or cellular senescence. Shortening of telomeres has been shown to occur during human aging and in chronic diseases that accelerate cell turnover, such as chronic hepatitis. Telomere shortening can limit organ homeostasis and regeneration in response to injury. Whether the same holds true for pancreas regeneration in response to injury is not known. Methods In the present study, pancreatic regeneration after acute cerulein-induced pancreatitis was studied in late generation telomerase knockout mice with short telomeres compared to telomerase wild-type mice with long telomeres. Results Late generation telomerase knockout mice exhibited impaired exocrine pancreatic regeneration after acute pancreatitis as seen by persistence of metaplastic acinar cells and markedly reduced proliferation. The expression levels of p53 and p21 were not significantly increased in regenerating pancreas of late generation telomerase knockout mice compared to wild-type mice. Conclusion Our results indicate that pancreatic regeneration is limited in the context of telomere dysfunction without evidence for p53 checkpoint activation. PMID:21364961

  15. Genetic variation in telomere maintenance genes, telomere length and breast cancer risk.

    PubMed

    Shen, Jing; Terry, Mary Beth; Liao, Yuyan; Gurvich, Irina; Wang, Qiao; Senie, Ruby T; Santella, Regina M

    2012-01-01

    Telomeres at the ends of eukaryotic chromosomes play a critical role in maintaining the integrity and stability of the genome and participate in the initiation of DNA damage/repair responses. We performed a case-control study to evaluate the role of three SNPs (TERT-07, TERT-54 and POT1-03) in telomere maintenance genes previously found to be significantly associated with breast cancer risk. We used sister-sets obtained from the New York site of the Breast Cancer Family Registry (BCFR). Among the 313 sister-sets, there were 333 breast cancer cases and 409 unaffected sisters who were evaluated in the current study. We separately applied conditional logistic regression and generalized estimating equations (GEE) models to evaluate associations between the three SNPs and breast cancer risk within sister-sets. We examined the associations between genotype, covariates and telomere length among unaffected sisters using a GEE model. We found no significant associations between the three SNPs in telomere maintenance genes and breast cancer risk by both conditional logistic regression and GEE models, nor were these SNPs significantly related to telomere length. Among unaffected sisters, shortened telomeres were statistically significantly correlated with never hormone replacement therapy (HRT) use. Increased duration of HRT use was significantly associated with reduced telomere length. The means of telomere length were 0.77 (SD = 0.35) for never HRT use, 0.67 (SD = 0.29) for HRT use < 5 yrs and 0.59 (SD = 0.24) for HRT use ≥ 5 yrs after adjusting for age of blood donation and race and ethnicity. We found that exogenous hormonal exposure was inversely associated with telomere length. No significant associations between genetic variants and telomere length or breast cancer risk were observed. These findings provide initial evidence to understand hormonal exposure in the regulation of telomere length and breast cancer risk but need replication in prospective studies.

  16. Telomeres, lifestyle, cancer, and aging

    PubMed Central

    Shammas, Masood A.

    2012-01-01

    Purpose of review There has been growing evidence that lifestyle factors may affect the health and lifespan of an individual by affecting telomere length. The purpose of this review was to highlight the importance of telomeres in human health and aging and to summarize possible lifestyle factors that may affect health and longevity by altering the rate of telomere shortening. Recent findings Recent studies indicate that telomere length, which can be affected by various lifestyle factors, can affect the pace of aging and onset of age-associated diseases. Summary Telomere length shortens with age. Progressive shortening of telomeres leads to senescence, apoptosis, or oncogenic transformation of somatic cells, affecting the health and lifespan of an individual. Shorter telomeres have been associated with increased incidence of diseases and poor survival. The rate of telomere shortening can be either increased or decreased by specific lifestyle factors. Better choice of diet and activities has great potential to reduce the rate of telomere shortening or at least prevent excessive telomere attrition, leading to delayed onset of age-associated diseases and increased lifespan. This review highlights the role of telomeres in aging and describes the lifestyle factors which may affect telomeres, human health, and aging. PMID:21102320

  17. Parallel telomere shortening in multiple body tissues owing to malaria infection.

    PubMed

    Asghar, Muhammad; Palinauskas, Vaidas; Zaghdoudi-Allan, Nadège; Valkiūnas, Gediminas; Mukhin, Andrey; Platonova, Elena; Färnert, Anna; Bensch, Staffan; Hasselquist, Dennis

    2016-08-17

    Several studies have shown associations between shorter telomere length in blood and weakened immune function, susceptibility to infections, and increased risk of morbidity and mortality. Recently, we have shown that malaria accelerates telomere attrition in blood cells and shortens lifespan in birds. However, the impact of infections on telomere attrition in different body tissues within an individual is unknown. Here, we tested whether malarial infection leads to parallel telomere shortening in blood and tissue samples from different organs. We experimentally infected siskins (Spinus spinus) with the avian malaria parasite Plasmodium ashfordi, and used real-time quantitative polymerase chain reaction (PCR) to measure telomere length in control and experimentally infected siskins. We found that experimentally infected birds showed faster telomere attrition in blood over the course of infection compared with control individuals (repeatedly measured over 105 days post-infection (DPI)). Shorter telomeres were also found in the tissue of all six major organs investigated (liver, lungs, spleen, heart, kidney, and brain) in infected birds compared with controls at 105 DPI. To the best of our knowledge, this is the first study showing that an infectious disease results in synchronous telomere shortening in the blood and tissue cells of internal organs within individuals, implying that the infection induces systemic stress. Our results have far-reaching implications for understanding how the short-term effects of an infection can translate into long-term costs, such as organ dysfunction, degenerative diseases, and ageing. © 2016 The Author(s).

  18. High frequency of X chromosome abnormalities in women with short stature and elevated liver enzymes.

    PubMed

    Roulot, Dominique; Malan, Valérie; Ziol, Marianne; Linglart, Agnès; Bourcier, Valérie; Beaugrand, Michel; Benzacken, Brigitte

    2014-08-01

    Paucisymptomatic forms of Turner's syndrome (TS), in which short stature is the predominant clinical abnormality, remain underdiagnosed. Abnormal liver tests are extremely frequent in adult TS patients reflecting various types of hepatic lesions. The objective of the study was to investigate whether unexplained elevated liver enzymes in women with short stature could reveal X chromosome abnormalities of undiagnosed TS. Thirty-one consecutive short stature women displaying elevated liver enzymes and no previous diagnosis of TS were compared with 31 age-matched controls in a prospective study. Liver biopsy was performed in 26 patients. Systematic karyotype analysis and fluorescence in situ hybridization. X chromosome abnormalities were found in 27 patients and one control (87.0% vs 3.2%, P < .0001), including a 45,X/46,XX mosaicism in 24 patients and isochromosome of the long arm in three. Liver histological analysis showed architectural changes in 17 patients with nodular regenerative hyperplasia in 12. Biliary lesions were present in 13 patients and liver steatosis in 20. X chromosome abnormalities indicative of cryptic TS are extremely frequent in short-stature women with unexplained elevated liver enzymes. In short-stature women, abnormal liver tests should lead to systematic karyotype analysis.

  19. Dicentric breakage at telomere fusions

    PubMed Central

    Pobiega, Sabrina; Marcand, Stéphane

    2010-01-01

    Nonhomologous end-joining (NHEJ) inhibition at telomeres ensures that native chromosome ends do not fuse together. But the occurrence and consequences of rare telomere fusions are not well understood. It is notably unclear whether a telomere fusion could be processed to restore telomere ends. Here we address the behavior of individual dicentrics formed by telomere fusion in the yeast Saccharomyces cerevisiae. Our approach was to first stabilize and amplify fusions between two chromosomes by temporarily inactivating one centromere. Next we analyzed dicentric breakage following centromere reactivation. Unexpectedly, dicentrics often break at the telomere fusions during progression through mitosis, a process that restores the parental chromosomes. This unforeseen result suggests a rescue pathway able to process telomere fusions and to back up NHEJ inhibition at telomeres. PMID:20360388

  20. Telomere biology: cancer firewall or aging clock?

    PubMed

    Mitteldorf, J J

    2013-09-01

    It has been a decade since the first surprising discovery that longer telomeres in humans are statistically associated with longer life expectancies. Since then, it has been firmly established that telomere shortening imposes an individual fitness cost in a number of mammalian species, including humans. But telomere shortening is easily avoided by application of telomerase, an enzyme which is coded into nearly every eukaryotic genome, but whose expression is suppressed most of the time. This raises the question how the sequestration of telomerase might have evolved. The predominant assumption is that in higher organisms, shortening telomeres provide a firewall against tumor growth. A more straightforward interpretation is that telomere attrition provides an aging clock, reliably programming lifespans. The latter hypothesis is routinely rejected by most biologists because the benefit of programmed lifespan applies only to the community, and in fact the individual pays a substantial fitness cost. There is a long-standing skepticism that the concept of fitness can be applied on a communal level, and of group selection in general. But the cancer hypothesis is problematic as well. Animal studies indicate that there is a net fitness cost in sequestration of telomerase, even when cancer risk is lowered. The hypothesis of protection against cancer has never been tested in animals that actually limit telomerase expression, but only in mice, whose lifespans are not telomerase-limited. And human medical evidence suggests a net aggravation of cancer risk from the sequestration of telomerase, because cells with short telomeres are at high risk of neoplastic transformation, and they also secrete cytokines that exacerbate inflammation globally. The aging clock hypothesis fits well with what is known about ancestral origins of telomerase sequestration, and the prejudices concerning group selection are without merit. If telomeres are an aging clock, then telomerase makes an

  1. Telomere Restriction Fragment (TRF) Analysis.

    PubMed

    Mender, Ilgen; Shay, Jerry W

    2015-11-20

    While telomerase is expressed in ~90% of primary human tumors, most somatic tissue cells except transiently proliferating stem-like cells do not have detectable telomerase activity (Shay and Wright, 1996; Shay and Wright, 2001). Telomeres progressively shorten with each cell division in normal cells, including proliferating stem-like cells, due to the end replication (lagging strand synthesis) problem and other causes such as oxidative damage, therefore all somatic cells have limited cell proliferation capacity (Hayflick limit) (Hayflick and Moorhead, 1961; Olovnikov, 1973). The progressive telomere shortening eventually leads to growth arrest in normal cells, which is known as replicative senescence (Shay et al. , 1991). Once telomerase is activated in cancer cells, telomere length is stabilized by the addition of TTAGGG repeats to the end of chromosomes, thus enabling the limitless continuation of cell division (Shay and Wright, 1996; Shay and Wright, 2001). Therefore, the link between aging and cancer can be partially explained by telomere biology. There are many rapid and convenient methods to study telomere biology such as Telomere Restriction Fragment (TRF), Telomere Repeat Amplification Protocol (TRAP) (Mender and Shay, 2015b) and Telomere dysfunction Induced Foci (TIF) analysis (Mender and Shay, 2015a). In this protocol paper we describe Telomere Restriction Fragment (TRF) analysis to determine average telomeric length of cells. Telomeric length can be indirectly measured by a technique called Telomere Restriction Fragment analysis (TRF). This technique is a modified Southern blot, which measures the heterogeneous range of telomere lengths in a cell population using the length distribution of the terminal restriction fragments (Harley et al. , 1990; Ouellette et al. , 2000). This method can be used in eukaryotic cells. The description below focuses on the measurement of human cancer cells telomere length. The principle of this method relies on the lack of

  2. Stochastic variation in telomere shortening rate causes heterogeneity of human fibroblast replicative life span.

    PubMed

    Martin-Ruiz, Carmen; Saretzki, Gabriele; Petrie, Joanne; Ladhoff, Juliane; Jeyapalan, Jessie; Wei, Wenyi; Sedivy, John; von Zglinicki, Thomas

    2004-04-23

    The replicative life span of human fibroblasts is heterogeneous, with a fraction of cells senescing at every population doubling. To find out whether this heterogeneity is due to premature senescence, i.e. driven by a nontelomeric mechanism, fibroblasts with a senescent phenotype were isolated from growing cultures and clones by flow cytometry. These senescent cells had shorter telomeres than their cycling counterparts at all population doubling levels and both in mass cultures and in individual subclones, indicating heterogeneity in the rate of telomere shortening. Ectopic expression of telomerase stabilized telomere length in the majority of cells and rescued them from early senescence, suggesting a causal role of telomere shortening. Under standard cell culture conditions, there was a minor fraction of cells that showed a senescent phenotype and short telomeres despite active telomerase. This fraction increased under chronic mild oxidative stress, which is known to accelerate telomere shortening. It is possible that even high telomerase activity cannot fully compensate for telomere shortening in all cells. The data show that heterogeneity of the human fibroblast replicative life span can be caused by significant stochastic cell-to-cell variation in telomere shortening.

  3. Human CST has independent functions during telomere duplex replication and C-strand fill-in

    PubMed Central

    Wang, Feng; Stewart, Jason A.; Kasbek, Christopher; Zhao, Yong; Wright, Woodring E.; Price, Carolyn M.

    2012-01-01

    Summary Human CST (CTC1-STN1-TEN1) is an RPA-like complex that is needed for efficient replication through the telomere duplex and genome-wide replication restart after fork stalling. Here we show that STN1/CST has a second function in telomere replication during G-overhang maturation. Analysis of overhang structure after STN1 depletion revealed normal kinetics for telomerase-mediated extension in S-phase but a delay in subsequent overhang shortening. This delay resulted from a defect in C-strand fill-in. Short telomeres exhibited the fill-in defect but normal telomere duplex replication, indicating that STN1/CST functions independently in these processes. Our work also indicates that the requirement for STN1/CST in telomere duplex replication correlates with increasing telomere length and replication stress. Our results provide the first direct evidence that STN1/CST participates in C-strand fill-in. They also demonstrate that STN1/CST participates in two mechanistically separate steps during telomere replication and identify CST as a novel replication factor that solves diverse replication-associated problems. PMID:23142664

  4. Telomere dynamics, end-to-end fusions and telomerase activation during the human fibroblast immortalization process.

    PubMed

    Ducray, C; Pommier, J P; Martins, L; Boussin, F D; Sabatier, L

    1999-07-22

    Loss of telomeric repeats during cell proliferation could play a role in senescence. It has been generally assumed that activation of telomerase prevents further telomere shortening and is essential for cell immortalization. In this study, we performed a detailed cytogenetic and molecular characterization of four SV40 transformed human fibroblastic cell lines by regularly monitoring the size distribution of terminal restriction fragments, telomerase activity and the associated chromosomal instability throughout immortalization. The mean TRF lengths progressively decreased in pre-crisis cells during the lifespan of the cultures. At crisis, telomeres reached a critical size, different among the cell lines, contributing to the peak of dicentric chromosomes, which resulted mostly from telomeric associations. We observed a direct correlation between short telomere length at crisis and chromosomal instability. In two immortal cell lines, although telomerase was detected, mean telomere length still continued to decrease whereas the number of dicentric chromosomes associated was stabilized. Thus telomerase could protect specifically telomeres which have reached a critical size against end-to-end dicentrics, while long telomeres continue to decrease, although at a slower rate as before crisis. This suggests a balance between elongation by telomerase and telomere shortening, towards a stabilized 'optimal' length.

  5. Genomic fragmentation and extrachromosomal telomeric repeats impact assessment of telomere length in human spermatozoa: quantitative experiments and systematic review.

    PubMed

    Kurjanowicz, P; Moskovtsev, S; Librach, C

    2017-11-01

    Can differences in DNA isolation alter assessment of sperm telomere length (spTL) and do they account for conflicting results in the literature on spTL and male fertility? DNA isolation methods preferentially include or exclude short, extrachromosomal (EC) telomere-specific sequences that alter spTL measurements, and are responsible for a proportion of the disparity observed between investigations. The relationship between spTL and male fertility has become an active area of research. The results across investigations, however, have been discordant, generating a need to critically evaluate the existing body of knowledge to guide future investigations. Quantitative experiments determined the effect of DNA isolation on the integrity of sperm DNA and measures of spTL, while a systematic analysis of the current literature evaluated the effect of DNA isolation and study design on experimental outcomes. Two DNA isolation methods were compared: Genomic Tips which isolate 'High Molecular Weight' (HMW) DNA exclusively, and QIAamp® DNA Mini which isolates 'Total' genomic DNA irrespective of size. DNA quality was assessed via field inversion gel electrophoresis (FIGE) and spTL was measured via terminal restriction fragment analysis. In addition, major databases in medicine, health and the life sciences were subject to a targeted search, and results were independently screened according to defined exclusion/inclusion criterion. Findings from primary articles were analyzed for concordance and study designs were compared across six moderator variables (sample size, participant age, fertility status, semen fraction, telomere population and type of analysis). HMW DNA spTL was significantly longer than spTL measured from total DNA (P < 0.01), indicating that Total DNA contained short, EC telomeric repeats that shifted downstream assessment towards shorter spTL. HMW DNA spTL reflected the length of intact, chromosomal telomeres. Major findings on spTL showed the greatest

  6. The role of telomeres and telomerase in hematologic malignancies and hematopoietic stem cell transplantation

    PubMed Central

    2014-01-01

    Telomeres are specific nucleoprotein structures at the ends of eukaryotic chromosomes. Telomeres and telomere-associated proteins maintain genome stability by protecting the ends of chromosomes from fusion and degradation. In normal somatic cells, the length of the telomeres gradually becomes shortened with cell division. In tumor cells, the shortening of telomeres length is accelerated under the increased proliferation pressure. However, it will be maintained at an extremely short length as the result of activation of telomerase. Significantly shortened telomeres, activation of telomerase, and altered expression of telomere-associated proteins are common features of various hematologic malignancies and are related with progression or chemotherapy resistance in these diseases. In patients who have received hematopoietic stem cell transplantation (HSCT), the telomere length and the telomerase activity of the engrafted donor cells have a significant influence on HSCT outcomes. Transplantation-related factors should be taken into consideration because of their impacts on telomere homeostasis. As activation of telomerase is widespread in tumor cells, it has been employed as a target point in the treatment of neoplastic hematologic disorders. In this review, the characteristics and roles of telomeres and telomerase both in hematologic malignancies and in HSCT will be summarized. The current status of telomerase-targeted therapies utilized in the treatment of hematologic malignancies will also be reviewed. PMID:25139287

  7. Reconstructing the in vivo dynamics of hematopoietic stem cells from telomere length distributions

    PubMed Central

    Werner, Benjamin; Beier, Fabian; Hummel, Sebastian; Balabanov, Stefan; Lassay, Lisa; Orlikowsky, Thorsten; Dingli, David; Brümmendorf, Tim H; Traulsen, Arne

    2015-01-01

    We investigate the in vivo patterns of stem cell divisions in the human hematopoietic system throughout life. In particular, we analyze the shape of telomere length distributions underlying stem cell behavior within individuals. Our mathematical model shows that these distributions contain a fingerprint of the progressive telomere loss and the fraction of symmetric cell proliferations. Our predictions are tested against measured telomere length distributions in humans across all ages, collected from lymphocyte and granulocyte sorted telomere length data of 356 healthy individuals, including 47 cord blood and 28 bone marrow samples. We find an increasing stem cell pool during childhood and adolescence and an approximately maintained stem cell population in adults. Furthermore, our method is able to detect individual differences from a single tissue sample, i.e. a single snapshot. Prospectively, this allows us to compare cell proliferation between individuals and identify abnormal stem cell dynamics, which affects the risk of stem cell related diseases. DOI: http://dx.doi.org/10.7554/eLife.08687.001 PMID:26468615

  8. Genetics Home Reference: Coats plus syndrome

    MedlinePlus

    ... of telomeres. However, it is unclear how CTC1 gene mutations impact telomere structure and function. Some studies have found that people with CTC1 gene mutations have abnormally short telomeres, while other studies have ...

  9. Epigenetic features of human telomeres.

    PubMed

    Cubiles, María D; Barroso, Sonia; Vaquero-Sedas, María I; Enguix, Alicia; Aguilera, Andrés; Vega-Palas, Miguel A

    2018-03-16

    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.

  10. Epigenetic features of human telomeres

    PubMed Central

    Cubiles, María D; Barroso, Sonia; Vaquero-Sedas, María I; Enguix, Alicia; Aguilera, Andrés; Vega-Palas, Miguel A

    2018-01-01

    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. PMID:29361030

  11. Behaviour of telomere and telomerase during aging and regeneration in zebrafish.

    PubMed

    Anchelin, Monique; Murcia, Laura; Alcaraz-Pérez, Francisca; García-Navarro, Esther M; Cayuela, María L

    2011-02-09

    Telomere length and telomerase activity are important factors in the pathobiology of human diseases. Age-related diseases and premature aging syndromes are characterized by short telomeres, which can compromise cell viability, whereas tumour cells can prevent telomere loss by aberrantly upregulating telomerase. The zebrafish (Danio rerio) offers multiple experimental manipulation advantages over other vertebrate models and, therefore, it has been recently considered as a potential model for aging, cancer, and regeneration studies. However, it has only partially been exploited to shed light on these fundamental biological processes. The aim of this study was, therefore, to investigate telomere length and telomerase expression and activity in different strains of zebrafish obtained from different stock centres to determine whether they undergo any changes during aging and regeneration. We found that although both telomerase expression and telomere length increased from embryo to adulthood stages, they drastically declined in aged fish despite telomerase activity was detected in different tissues of old fish. In addition, we observed a weaker upregulation of telomerase expression in regenerating fins of old fish, which well correlates with their impaired regeneration capacity. Strikingly, telomeres were elongated or maintained during the fin regeneration process at all ages and after repeated amputations, likely to support high cell proliferation rates. We conclude that the expression of telomerase and telomere length are closely related during the entire life cycle of the fish and that these two parameters can be used as biomarkers of aging in zebrafish. Our results also reveal a direct relationship between the expression of telomerase, telomere length and the efficiency of tissue regeneration.

  12. An H2A Histone Isotype, H2ac, Associates with Telomere and Maintains Telomere Integrity

    PubMed Central

    Tzeng, Tsai-Yu; Lin, I-Hsuan; Hsu, Ming-Ta

    2016-01-01

    Telomeres are capped at the ends of eukaryotic chromosomes and are composed of TTAGGG repeats bound to the shelterin complex. Here we report that a replication-dependent histone H2A isotype, H2ac, was associated with telomeres in human cells and co-immunoprecipitates with telomere repeat factor 2 (TRF2) and protection of telomeres protein 1 (POT1), whereas other histone H2A isotypes and mutations of H2ac did not bind to telomeres or these two proteins. The amino terminal basic domain of TRF2 was necessary for the association with H2ac and for the recruitment of H2ac to telomeres. Depletion of H2ac led to loss of telomeric repeat sequences, the appearance of dysfunctional telomeres, and chromosomal instability, including chromosomal breaks and anaphase bridges, as well as accumulation of telomere-associated DNA damage factors in H2ac depleted cells. Additionally, knockdown of H2ac elicits an ATM-dependent DNA damage response at telomeres and depletion of XPF protects telomeres against H2ac-deficiency-induced G-strand overhangs loss and DNA damage response, and prevents chromosomal instability. These findings suggest that the H2A isotype, H2ac, plays an essential role in maintaining telomere functional integrity. PMID:27228173

  13. Does oxidative stress shorten telomeres?

    PubMed

    Boonekamp, Jelle J; Bauch, Christina; Mulder, Ellis; Verhulst, Simon

    2017-05-01

    Oxidative stress shortens telomeres in cell culture, but whether oxidative stress explains variation in telomere shortening in vivo at physiological oxidative stress levels is not well known. We therefore tested for correlations between six oxidative stress markers and telomere attrition in nestling birds (jackdaws Corvus monedula ) that show a high rate of telomere attrition in early life. Telomere attrition was measured between ages 5 and 30 days, and was highly variable (average telomere loss: 323 bp, CV = 45%). Oxidative stress markers were measured in blood at age 20 days and included markers of oxidative damage (TBARS, dROMs and GSSG) and markers of antioxidant protection (GSH, redox state, uric acid). Variation in telomere attrition was not significantly related to these oxidative stress markers (| r | ≤ 0.08, n = 87). This finding raises the question whether oxidative stress accelerates telomere attrition in vivo The accumulation of telomere attrition over time depends both on the number of cell divisions and on the number of base pairs lost per DNA replication and, based on our findings, we suggest that in a growing animal cell proliferation, dynamics may be more important for explaining variation in telomere attrition than oxidative stress. © 2017 The Author(s).

  14. SLX4 Assembles a Telomere Maintenance Toolkit by Bridging Multiple Endonucleases with Telomeres

    PubMed Central

    Wan, Bingbing; Yin, Jinhu; Horvath, Kent; Sarkar, Jaya; Chen, Yong; Wu, Jian; Wan, Ke; Lu, Jian; Gu, Peili; Yu, Eun Young; Lue, Neal F.; Chang, Sandy

    2014-01-01

    Summary SLX4 interacts with several endonucleases to resolve structural barriers in DNA metabolism. SLX4 also interacts with telomeric protein TRF2 in human cells. The molecular mechanism of these interactions at telomeres remains unknown. Here, we report the crystal structure of the TRF2-binding motif of SLX4 (SLX4TBM) in complex with the TRFH domain of TRF2 (TRF2TRFH) and map the interactions of SLX4 with endonucleases SLX1, XPF, and MUS81. TRF2 recognizes a unique HxLxP motif on SLX4 via the peptide-binding site in its TRFH domain. Telomeric localization of SLX4 and associated nucleases depend on the SLX4-endonuclease and SLX4-TRF2 interactions and the protein levels of SLX4 and TRF2. SLX4 assembles an endonuclease toolkit that negatively regulates telomere length via SLX1-catalyzed nucleolytic resolution of telomere DNA structures. We propose that the SLX4-TRF2 complex serves as a double-layer scaffold bridging multiple endonucleases with telomeres for recombination-based telomere maintenance. PMID:24012755

  15. Single-cell telomere-length quantification couples telomere length to meristem activity and stem cell development in Arabidopsis.

    PubMed

    González-García, Mary-Paz; Pavelescu, Irina; Canela, Andrés; Sevillano, Xavier; Leehy, Katherine A; Nelson, Andrew D L; Ibañes, Marta; Shippen, Dorothy E; Blasco, Maria A; Caño-Delgado, Ana I

    2015-05-12

    Telomeres are specialized nucleoprotein caps that protect chromosome ends assuring cell division. Single-cell telomere quantification in animals established a critical role for telomerase in stem cells, yet, in plants, telomere-length quantification has been reported only at the organ level. Here, a quantitative analysis of telomere length of single cells in Arabidopsis root apex uncovered a heterogeneous telomere-length distribution of different cell lineages showing the longest telomeres at the stem cells. The defects in meristem and stem cell renewal observed in tert mutants demonstrate that telomere lengthening by TERT sets a replicative limit in the root meristem. Conversely, the long telomeres of the columella cells and the premature stem cell differentiation plt1,2 mutants suggest that differentiation can prevent telomere erosion. Overall, our results indicate that telomere dynamics are coupled to meristem activity and continuous growth, disclosing a critical association between telomere length, stem cell function, and the extended lifespan of plants. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  16. Telomere shortening unrelated to smoking, body weight, physical activity, and alcohol intake: 4,576 general population individuals with repeat measurements 10 years apart.

    PubMed

    Weischer, Maren; Bojesen, Stig E; Nordestgaard, Børge G

    2014-03-01

    Cross-sectional studies have associated short telomere length with smoking, body weight, physical activity, and possibly alcohol intake; however, whether these associations are due to confounding is unknown. We tested these hypotheses in 4,576 individuals from the general population cross-sectionally, and with repeat measurement of relative telomere length 10 years apart. We also tested whether change in telomere length is associated with mortality and morbidity in the general population. Relative telomere length was measured with quantitative polymerase chain reaction. Cross-sectionally at the first examination, short telomere length was associated with increased age (P for trend across quartiles = 3 × 10(-77)), current smoking (P = 8 × 10(-3)), increased body mass index (P = 7 × 10(-14)), physical inactivity (P = 4 × 10(-17)), but not with increased alcohol intake (P = 0.10). At the second examination 10 years later, 56% of participants had lost and 44% gained telomere length with a mean loss of 193 basepairs. Change in leukocyte telomere length during 10 years was associated inversely with baseline telomere length (P<1 × 10(-300)) and age at baseline (P = 1 × 10(-27)), but not with baseline or 10-year inter-observational tobacco consumption, body weight, physical activity, or alcohol intake. Prospectively during a further 10 years follow-up after the second examination, quartiles of telomere length change did not associate with risk of all-cause mortality, cancer, chronic obstructive pulmonary disease, diabetes mellitus, ischemic cerebrovascular disease, or ischemic heart disease. In conclusion, smoking, increased body weight, and physical inactivity were associated with short telomere length cross-sectionally, but not with telomere length change during 10 years observation, and alcohol intake was associated with neither. Also, change in telomere length did not associate prospectively with mortality or morbidity in the general population.

  17. Telomeric repeat-containing RNA/G-quadruplex-forming sequences cause genome-wide alteration of gene expression in human cancer cells in vivo.

    PubMed

    Hirashima, Kyotaro; Seimiya, Hiroyuki

    2015-02-27

    Telomere erosion causes cell mortality, suggesting that longer telomeres enable more cell divisions. In telomerase-positive human cancer cells, however, telomeres are often kept shorter than those of surrounding normal tissues. Recently, we showed that cancer cell telomere elongation represses innate immune genes and promotes their differentiation in vivo. This implies that short telomeres contribute to cancer malignancy, but it is unclear how such genetic repression is caused by elongated telomeres. Here, we report that telomeric repeat-containing RNA (TERRA) induces a genome-wide alteration of gene expression in telomere-elongated cancer cells. Using three different cell lines, we found that telomere elongation up-regulates TERRA signal and down-regulates innate immune genes such as STAT1, ISG15 and OAS3 in vivo. Ectopic TERRA oligonucleotides repressed these genes even in cells with short telomeres under three-dimensional culture conditions. This appeared to occur from the action of G-quadruplexes (G4) in TERRA, because control oligonucleotides had no effect and a nontelomeric G4-forming oligonucleotide phenocopied the TERRA oligonucleotide. Telomere elongation and G4-forming oligonucleotides showed similar gene expression signatures. Most of the commonly suppressed genes were involved in the innate immune system and were up-regulated in various cancers. We propose that TERRA G4 counteracts cancer malignancy by suppressing innate immune genes. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

  18. Genetic association of telomere length with hepatocellular carcinoma risk: A Mendelian randomization analysis.

    PubMed

    Cheng, Yue; Yu, Chengxiao; Huang, Mingtao; Du, Fangzhi; Song, Ci; Ma, Zijian; Zhai, Xiangjun; Yang, Yuan; Liu, Jibin; Bei, Jin-Xin; Jia, Weihua; Jin, Guangfu; Li, Shengping; Zhou, Weiping; Liu, Jianjun; Dai, Juncheng; Hu, Zhibin

    2017-10-01

    Observational studies show an association between telomere length and Hepatocellular carcinoma (HCC) risk, but the relationship is controversial. Particularly, it remains unclear whether the association is due to confounding or biases inherent in conventional epidemiological studies. Here, we applied Mendelian randomization approach to evaluate whether telomere length is causally associated with HCC risk. Individual-level data were from HBV-related HCC Genome-wide association studies (1,538 HBV positive HCC patients and 1,465 HBV positive controls). Genetic risk score, as proxy for actual measured telomere length, derived from nine telomere length-associated genetic variants was used to evaluate the effect of telomere length on HCC risk. We observed a significant risk signal between genetically increased telomere length and HBV-related HCC risk (OR=2.09, 95% CI 1.32-3.31, P=0.002). Furthermore, a U-shaped curve was fitted by the restricted cubic spline curve, which indicated that either short or long telomere length would increase HCC risk (P=0.0022 for non-linearity test). Subgroup analysis did not reveal significant heterogeneity between different age, gender, smoking status and drinking status groups. Our results indicated that a genetic background that favors longer or shorter telomere length may increase HBV-related HCC risk-a U-shaped association. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Ticking Telomeres/Telltale Telomerase.

    ERIC Educational Resources Information Center

    Biermann, Carol A.

    1997-01-01

    Discusses telomeres, complexes of DNA and protein that form the chromatin at the ends of chromosomes. Highlights telomeres as controllers of chromosome integrity, expendable telomeres, DNA replication requirements and their consequences, protection of structural genes, telomerase as indicators of immortality, cancer cells and other immortals, and…

  20. Cell Death During Crisis Is Mediated by Mitotic Telomere Deprotection

    PubMed Central

    Hayashi, Makoto T.; Cesare, Anthony J.; Rivera, Teresa; Karlseder, Jan

    2015-01-01

    Tumour formation is blocked by two barriers, replicative senescence and crisis1. Senescence is triggered by short telomeres and is bypassed by disruption of tumour suppressive pathways. After senescence bypass, cells undergo crisis, during which almost all of the cells in the population die. Cells that escape crisis harbor unstable genomes and other parameters of transformation. The mechanism of cell death during crisis remained elusive. We show that cells in crisis undergo spontaneous mitotic arrest, resulting in death during mitosis or in the following cell cycle. The phenotype was induced by loss of p53 function, and suppressed by telomerase overexpression. Telomere fusions triggered mitotic arrest in p53-compromised non-crisis cells, indicating such fusions as the underlying cause. Exacerbation of mitotic telomere deprotection by partial TRF2 knockdown2 increased the ratio of cells that died during mitotic arrest and sensitized cancer cells to mitotic poisons. We propose a crisis pathway wherein chromosome fusions induce mitotic arrest, resulting in mitotic telomere deprotection and cell death, thereby eliminating precancerous cells from the population. PMID:26108857

  1. Effect of telomere length on survival in idiopathic pulmonary fibrosis: an observational study with independent validation

    PubMed Central

    Stuart, Bridget D.; Lee, Joyce S.; Kozlitina, Julia; Noth, Imre; Devine, Megan S.; Glazer, Craig S.; Torres, Fernando; Kaza, Vaidehi; Girod, Carlos E.; Jones, Kirk D.; Elicker, Brett M.; Ma, Shwu-Fan; Vij, Rekha; Collard, Harold R.; Wolters, Paul J.; Garcia, Christine Kim

    2014-01-01

    Background Short telomere lengths are found in a subset of idiopathic pulmonary fibrosis (IPF) patients, but their clinical significance is unknown. The aim of this study was to investigate whether patients with various blood leukocyte telomere lengths had different overall survival. Methods Telomere lengths were measured in 370 genomic DNA samples isolated from peripheral blood collected from patients with interstitial lung disease (149 with IPF) at the time of their initial evaluation. Associations of telomere length with transplant-free survival were determined. Findings were validated in two independent IPF cohorts. Findings Patients with IPF had shorter telomere lengths than controls, but similar telomere lengths when compared to patients with other interstitial lung disease diagnoses after adjusting for age, male sex and ethnicity. Telomere length was independently associated with transplant-free survival time for patients with IPF (HR 0·22 [0·08–0·63], P-value = 0·0048), but not for patients with interstitial lung disease diagnoses other than IPF (HR 0·73 [0·16–3·41], P-value = 0·69). The association between telomere length and IPF survival was independent of age, male sex, forced vital capacity or diffusing capacity of carbon monoxide (and was replicated in two independent IPF cohorts (HR 0·11 [0·03–0·39], P-value 0·00066; HR 0·25 [0·07–0·87], P-value = 0·029). Addition of telomere length to clinical prediction models improved the integrative discrimination index, especially for IPF cohorts with milder disease. Interpretation These findings suggest that shorter leukocyte telomere lengths are associated with worse survival in IPF. Additional studies will be needed to determine clinically relevant thresholds for telomere length and how this biomarker may influence future risk stratification of IPF patients. Furthermore, this study offers mechanistic insight as disease progression in certain IPF patients may be related to aberrant

  2. DNA Excision Repair at Telomeres

    PubMed Central

    Jia, Pingping; Her, Chengtao; Chai, Weihang

    2015-01-01

    DNA damage is caused by either endogenous cellular metabolic processes such as hydrolysis, oxidation, alkylation, and DNA base mismatches, or exogenous sources including ultraviolet (UV) light, ionizing radiation, and chemical agents. Damaged DNA that is not properly repaired can lead to genomic instability, driving tumorigenesis. To protect genomic stability, mammalian cells have evolved highly conserved DNA repair mechanisms to remove and repair DNA lesions. Telomeres are composed of long tandem TTAGGG repeats located at the ends of chromosomes. Maintenance of functional telomeres is critical for preventing genome instability. The telomeric sequence possesses unique features that predispose telomeres to a variety of DNA damage induced by environmental genotoxins. This review briefly describes the relevance of excision repair pathways in telomere maintenance, with the focus on base excision repair (BER), nucleotide excision repair (NER), and mismatch repair (MMR). By summarizing current knowledge on excision repair of telomere damage and outlining many unanswered questions, it is our hope to stimulate further interest in a better understanding of excision repair processes at telomeres and in how these processes contribute to telomere maintenance. PMID:26422132

  3. Sod2 haploinsufficiency does not accelerate aging of telomere dysfunctional mice

    PubMed Central

    Guachalla, Luis Miguel; Ju, Zhenyu; Koziel, Rafal; von Figura, Guido; Song, Zhangfa; Fusser, Markus; Epe, Bernd; Jansen-Dűrr, Pidder; Rudolph, K. Lenhard

    2009-01-01

    Telomere shortening represents a causal factor of cellular senescence. At the same time, several lines of evidence indicate a pivotal role of oxidative DNA damage for the aging process in vivo. A causal connection between the two observations was suggested by experiments showing accelerated telomere shorting under conditions of oxidative stress in cultured cells, but has never been studied in vivo. We therefore have analysed whether an increase in mitochondrial derived oxidative stress in response to heterozygous deletion of superoxide dismutase (Sod2+/-) would exacerbate aging phenotypes in telomere dysfunctional (mTerc-/-) mice. Heterozygous deletion of Sod2 resulted in reduced SOD2 protein levels and increased oxidative stress in aging telomere dysfunctional mice, but this did not lead to an increase in basal levels of oxidative nuclear DNA damage, an accumulation of nuclear DNA breaks, or an increased rate of telomere shortening in the mice. Moreover, heterozygous deletion of Sod2 did not accelerate the depletion of stem cells and the impairment in organ maintenance in aging mTerc-/- mice. In agreement with these observations, Sod2 haploinsufficiency did not lead to a further reduction in lifespan of mTerc-/- mice. Together, these results indicate that a decrease in SOD2-dependent antioxidant defence does not exacerbate aging in the context of telomere dysfunction. PMID:20195488

  4. Leukocyte telomere length is inversely associated with post-load but not with fasting plasma glucose levels.

    PubMed

    Khalangot, Mykola; Krasnienkov, Dmytro; Vaiserman, Alexander; Avilov, Ivan; Kovtun, Volodymir; Okhrimenko, Nadia; Koliada, Alexander; Kravchenko, Victor

    2017-04-01

    Type 2 diabetes mellitus is characterized by shorter leukocyte telomere length, but the relationship between leukocyte telomere length and type 2 diabetes mellitus development is rather questioned. Fasting and post-load glycaemia associated with different types of insulin resistance and their relation with leukocyte telomere length remains unknown. We compared leukocyte telomere length and fasting or post-load glucose levels in persons who do not receive glucose lowering treatment. For 82 randomly selected rural residents of Ukraine, aged 45+, not previously diagnosed with type 2 diabetes mellitus, the WHO oral glucose tolerance test and anthropometric measurements were performed. Leukocyte telomere length was measured by standardized method of quantitative monochrome multiplex polymerase chain reaction in real time. Spearman's or Pearson's rank correlation was used for correlation analysis between fasting plasma glucose or 2-h post-load plasma glucose levels and leukocyte telomere length. Logistical regression models were used to evaluate risks of finding short or long telomeres associated with fasting plasma glucose or 2-h post-load plasma glucose levels. No association of fasting plasma glucose and leukocyte telomere length was revealed, whereas 2-h post-load plasma glucose levels demonstrated a negative correlation ( P < 0.01) with leukocyte telomere length. Waist circumference and systolic blood pressure were negatively related ( P = 0.03) with leukocyte telomere length in men. Oral glucose tolerance test result-based glycemic categories did not show differences between mean leukocyte telomere length in categories of normal fasting plasma glucose and 2-h post-load plasma glucose (NGT, n = 33); diabetes mellitus (DM), n = 18 and impaired fasting glucose/tolerance (IFG/IGT, n = 31) levels. A correlation relationship between leukocyte telomere length and 2-h post-load plasma glucose level in NGT; IFG/IGT and DM groups ( P = 0.027; 0

  5. Structural anatomy of telomere OB proteins.

    PubMed

    Horvath, Martin P

    2011-10-01

    Telomere DNA-binding proteins protect the ends of chromosomes in eukaryotes. A subset of these proteins are constructed with one or more OB folds and bind with G+T-rich single-stranded DNA found at the extreme termini. The resulting DNA-OB protein complex interacts with other telomere components to coordinate critical telomere functions of DNA protection and DNA synthesis. While the first crystal and NMR structures readily explained protection of telomere ends, the picture of how single-stranded DNA becomes available to serve as primer and template for synthesis of new telomere DNA is only recently coming into focus. New structures of telomere OB fold proteins alongside insights from genetic and biochemical experiments have made significant contributions towards understanding how protein-binding OB proteins collaborate with DNA-binding OB proteins to recruit telomerase and DNA polymerase for telomere homeostasis. This review surveys telomere OB protein structures alongside highly comparable structures derived from replication protein A (RPA) components, with the goal of providing a molecular context for understanding telomere OB protein evolution and mechanism of action in protection and synthesis of telomere DNA.

  6. Telomere content measurement in human hematopoietic cells: Comparative analysis of qPCR and Flow-FISH techniques.

    PubMed

    Wand, Taylor; Fang, Mike; Chen, Christina; Hardy, Nathan; McCoy, J Philip; Dumitriu, Bogdan; Young, Neal S; Biancotto, Angélique

    2016-10-01

    Abnormal telomere lengths have been linked to cancer and other hematologic disorders. Determination of mean telomere content (MTC) is traditionally performed by Southern blotting and densitometry, giving a mean telomere restriction fragment (TRF) value for the total cell population studied. Here, we compared a quantitative Polymerase Chain Reaction approach (qPCR) and a flow cytometric approach, fluorescence in situ hybridization (Flow-FISH), to evaluate telomere content distribution in total patient peripheral blood mononuclear cells or specific cell populations. Flow-FISH is based on in situ hybridization using a fluorescein-labeled peptide nucleic acid (PNA) (CCCTAA) 3 probe and DNA staining with propidium iodide. We showed that both qPCR and Flow-FISH provide a robust measurement, with Flow-FISH measuring a relative content longer than qPCR at a single cell approach and that TRF2 fluorescence intensity did not correlate with MTC. Both methods showed comparable telomere content reduction with age, and the rate of relative telomere loss was similar. Published 2016 Wiley Periodicals Inc. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals Inc. This article is a US government work and, as such, is in the public domain in the United States of America.

  7. Trypanosoma brucei RAP1 maintains telomere and subtelomere integrity by suppressing TERRA and telomeric RNA:DNA hybrids.

    PubMed

    Nanavaty, Vishal; Sandhu, Ranjodh; Jehi, Sanaa E; Pandya, Unnati M; Li, Bibo

    2017-06-02

    Trypanosoma brucei causes human African trypanosomiasis and regularly switches its major surface antigen, VSG, thereby evading the host's immune response. VSGs are monoallelically expressed from subtelomeric expression sites (ESs), and VSG switching exploits subtelomere plasticity. However, subtelomere integrity is essential for T. brucei viability. The telomeric transcript, TERRA, was detected in T. brucei previously. We now show that the active ES-adjacent telomere is transcribed. We find that TbRAP1, a telomere protein essential for VSG silencing, suppresses VSG gene conversion-mediated switching. Importantly, TbRAP1 depletion increases the TERRA level, which appears to result from longer read-through into the telomere downstream of the active ES. Depletion of TbRAP1 also results in more telomeric RNA:DNA hybrids and more double strand breaks (DSBs) at telomeres and subtelomeres. In TbRAP1-depleted cells, expression of excessive TbRNaseH1, which cleaves the RNA strand of the RNA:DNA hybrid, brought telomeric RNA:DNA hybrids, telomeric/subtelomeric DSBs and VSG switching frequency back to WT levels. Therefore, TbRAP1-regulated appropriate levels of TERRA and telomeric RNA:DNA hybrid are fundamental to subtelomere/telomere integrity. Our study revealed for the first time an important role of a long, non-coding RNA in antigenic variation and demonstrated a link between telomeric silencing and subtelomere/telomere integrity through TbRAP1-regulated telomere transcription. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  8. Paroxysmal nocturnal hemoglobinuria and telomere length predicts response to immunosuppressive therapy in pediatric aplastic anemia

    PubMed Central

    Narita, Atsushi; Muramatsu, Hideki; Sekiya, Yuko; Okuno, Yusuke; Sakaguchi, Hirotoshi; Nishio, Nobuhiro; Yoshida, Nao; Wang, Xinan; Xu, Yinyan; Kawashima, Nozomu; Doisaki, Sayoko; Hama, Asahito; Takahashi, Yoshiyuki; Kudo, Kazuko; Moritake, Hiroshi; Kobayashi, Masao; Kobayashi, Ryoji; Ito, Etsuro; Yabe, Hiromasa; Ohga, Shouichi; Ohara, Akira; Kojima, Seiji

    2015-01-01

    Acquired aplastic anemia is an immune-mediated disease characterized by severe defects in stem cell number resulting in hypocellular marrow and peripheral blood cytopenias. Minor paroxysmal nocturnal hemoglobinuria populations and a short telomere length were identified as predictive biomarkers of immunosuppressive therapy responsiveness in aplastic anemia. We enrolled 113 aplastic anemia patients (63 boys and 50 girls) in this study to evaluate their response to immunosuppressive therapy. The paroxysmal nocturnal hemoglobinuria populations and telomere length were detected by flow cytometry. Forty-seven patients (42%) carried a minor paroxysmal nocturnal hemoglobinuria population. The median telomere length of aplastic anemia patients was −0.99 standard deviation (SD) (range −4.01–+3.01 SD). Overall, 60 patients (53%) responded to immunosuppressive therapy after six months. Multivariate logistic regression analysis identified the absence of a paroxysmal nocturnal hemoglobinuria population and a shorter telomere length as independent unfavorable predictors of immunosuppressive therapy response at six months. The cohort was stratified into a group of poor prognosis (paroxysmal nocturnal hemoglobinuria negative and shorter telomere length; 37 patients) and good prognosis (paroxysmal nocturnal hemoglobinuria positive and/or longer telomere length; 76 patients), respectively. The response rates of the poor prognosis and good prognosis groups at six months were 19% and 70%, respectively (P<0.001). The combined absence of a minor paroxysmal nocturnal hemoglobinuria population and a short telomere length is an efficient predictor of poor immunosuppressive therapy response, which should be considered while deciding treatment options: immunosuppressive therapy or first-line hematopoietic stem cell transplantation. The trial was registered in www.umin.ac.jp with number UMIN000017972. PMID:26315930

  9. Paroxysmal nocturnal hemoglobinuria and telomere length predicts response to immunosuppressive therapy in pediatric aplastic anemia.

    PubMed

    Narita, Atsushi; Muramatsu, Hideki; Sekiya, Yuko; Okuno, Yusuke; Sakaguchi, Hirotoshi; Nishio, Nobuhiro; Yoshida, Nao; Wang, Xinan; Xu, Yinyan; Kawashima, Nozomu; Doisaki, Sayoko; Hama, Asahito; Takahashi, Yoshiyuki; Kudo, Kazuko; Moritake, Hiroshi; Kobayashi, Masao; Kobayashi, Ryoji; Ito, Etsuro; Yabe, Hiromasa; Ohga, Shouichi; Ohara, Akira; Kojima, Seiji

    2015-12-01

    Acquired aplastic anemia is an immune-mediated disease characterized by severe defects in stem cell number resulting in hypocellular marrow and peripheral blood cytopenias. Minor paroxysmal nocturnal hemoglobinuria populations and a short telomere length were identified as predictive biomarkers of immunosuppressive therapy responsiveness in aplastic anemia. We enrolled 113 aplastic anemia patients (63 boys and 50 girls) in this study to evaluate their response to immunosuppressive therapy. The paroxysmal nocturnal hemoglobinuria populations and telomere length were detected by flow cytometry. Forty-seven patients (42%) carried a minor paroxysmal nocturnal hemoglobinuria population. The median telomere length of aplastic anemia patients was -0.99 standard deviation (SD) (range -4.01-+3.01 SD). Overall, 60 patients (53%) responded to immunosuppressive therapy after six months. Multivariate logistic regression analysis identified the absence of a paroxysmal nocturnal hemoglobinuria population and a shorter telomere length as independent unfavorable predictors of immunosuppressive therapy response at six months. The cohort was stratified into a group of poor prognosis (paroxysmal nocturnal hemoglobinuria negative and shorter telomere length; 37 patients) and good prognosis (paroxysmal nocturnal hemoglobinuria positive and/or longer telomere length; 76 patients), respectively. The response rates of the poor prognosis and good prognosis groups at six months were 19% and 70%, respectively (P<0.001). The combined absence of a minor paroxysmal nocturnal hemoglobinuria population and a short telomere length is an efficient predictor of poor immunosuppressive therapy response, which should be considered while deciding treatment options: immunosuppressive therapy or first-line hematopoietic stem cell transplantation. The trial was registered in www.umin.ac.jp with number UMIN000017972. Copyright© Ferrata Storti Foundation.

  10. When Telomerase Causes Telomere Loss.

    PubMed

    Glousker, Galina; Lingner, Joachim

    2018-02-05

    Telomerase counteracts telomere shortening, preventing cellular senescence. Telomerase deficiency causes telomere syndromes because of premature telomere exhaustion in highly proliferative cells. Paradoxically, in a recent issue of Cell, Margalef et al. (2018) demonstrate that telomerase causes telomere loss in cells lacking the RTEL1 helicase, which is defective in Hoyeraal-Hreidarsson syndrome (HHS). Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Atrx deficiency induces telomere dysfunction, endocrine defects, and reduced life span

    PubMed Central

    Watson, L. Ashley; Solomon, Lauren A.; Li, Jennifer Ruizhe; Jiang, Yan; Edwards, Matthew; Shin-ya, Kazuo; Beier, Frank; Bérubé, Nathalie G.

    2013-01-01

    Human ATRX mutations are associated with cognitive deficits, developmental abnormalities, and cancer. We show that the Atrx-null embryonic mouse brain accumulates replicative damage at telomeres and pericentromeric heterochromatin, which is exacerbated by loss of p53 and linked to ATM activation. ATRX-deficient neuroprogenitors exhibited higher incidence of telomere fusions and increased sensitivity to replication stress–inducing drugs. Treatment of Atrx-null neuroprogenitors with the G-quadruplex (G4) ligand telomestatin increased DNA damage, indicating that ATRX likely aids in the replication of telomeric G4-DNA structures. Unexpectedly, mutant mice displayed reduced growth, shortened life span, lordokyphosis, cataracts, heart enlargement, and hypoglycemia, as well as reduction of mineral bone density, trabecular bone content, and subcutaneous fat. We show that a subset of these defects can be attributed to loss of ATRX in the embryonic anterior pituitary that resulted in low circulating levels of thyroxine and IGF-1. Our findings suggest that loss of ATRX increases DNA damage locally in the forebrain and anterior pituitary and causes tissue attrition and other systemic defects similar to those seen in aging. PMID:23563309

  12. Structural anatomy of telomere OB proteins

    PubMed Central

    Horvath, Martin P.

    2015-01-01

    Telomere DNA-binding proteins protect the ends of chromosomes in eukaryotes. A subset of these proteins are constructed with one or more OB folds and bind with G+T-rich single-stranded DNA found at the extreme termini. The resulting DNA-OB protein complex interacts with other telomere components to coordinate critical telomere functions of DNA protection and DNA synthesis. While the first crystal and NMR structures readily explained protection of telomere ends, the picture of how single-stranded DNA becomes available to serve as primer and template for synthesis of new telomere DNA is only recently coming into focus. New structures of telomere OB fold proteins alongside insights from genetic and biochemical experiments have made significant contributions towards understanding how protein-binding OB proteins collaborate with DNA-binding OB proteins to recruit telomerase and DNA polymerase for telomere homeostasis. This review surveys telomere OB protein structures alongside highly comparable structures derived from replication protein A (RPA) components, with the goal of providing a molecular context for understanding telomere OB protein evolution and mechanism of action in protection and synthesis of telomere DNA. PMID:21950380

  13. Telomere Shortening Unrelated to Smoking, Body Weight, Physical Activity, and Alcohol Intake: 4,576 General Population Individuals with Repeat Measurements 10 Years Apart

    PubMed Central

    Weischer, Maren; Bojesen, Stig E.; Nordestgaard, Børge G.

    2014-01-01

    Cross-sectional studies have associated short telomere length with smoking, body weight, physical activity, and possibly alcohol intake; however, whether these associations are due to confounding is unknown. We tested these hypotheses in 4,576 individuals from the general population cross-sectionally, and with repeat measurement of relative telomere length 10 years apart. We also tested whether change in telomere length is associated with mortality and morbidity in the general population. Relative telomere length was measured with quantitative polymerase chain reaction. Cross-sectionally at the first examination, short telomere length was associated with increased age (P for trend across quartiles = 3×10−77), current smoking (P = 8×10−3), increased body mass index (P = 7×10−14), physical inactivity (P = 4×10−17), but not with increased alcohol intake (P = 0.10). At the second examination 10 years later, 56% of participants had lost and 44% gained telomere length with a mean loss of 193 basepairs. Change in leukocyte telomere length during 10 years was associated inversely with baseline telomere length (P<1×10−300) and age at baseline (P = 1×10−27), but not with baseline or 10-year inter-observational tobacco consumption, body weight, physical activity, or alcohol intake. Prospectively during a further 10 years follow-up after the second examination, quartiles of telomere length change did not associate with risk of all-cause mortality, cancer, chronic obstructive pulmonary disease, diabetes mellitus, ischemic cerebrovascular disease, or ischemic heart disease. In conclusion, smoking, increased body weight, and physical inactivity were associated with short telomere length cross-sectionally, but not with telomere length change during 10 years observation, and alcohol intake was associated with neither. Also, change in telomere length did not associate prospectively with mortality or morbidity in the general population. PMID

  14. Predictors of telomere content in dragon lizards

    NASA Astrophysics Data System (ADS)

    Ballen, Cissy; Healey, Mo; Wilson, Mark; Tobler, Michael; Olsson, Mats

    2012-08-01

    Telomeres shorten as a consequence of DNA replication, in particular in cells with low production of telomerase and perhaps in response to physiological stress from exposure to reactive oxygen species, such as superoxide. This process of telomere attrition is countered by innate antioxidation, such as via the production of superoxide dismutase. We studied the inheritance of telomere length in the Australian painted dragon lizard ( Ctenophorus pictus) and the extent to which telomere length covaries with mass-corrected maternal reproductive investment, which reflects the level of circulating yolk precursor and antioxidant, vitellogenin. Our predictors of offspring telomere length explained 72 % of telomere variation (including interstitial telomeres if such are present). Maternal telomere length and reproductive investment were positively influencing offspring telomere length in our analyses, whereas flow cytometry-estimated superoxide level was negatively impacting offspring telomere length. We suggest that the effects of superoxide on hatchling telomere shortening may be partly balanced by transgenerational effects of vitellogenin antioxidation.

  15. Prostate stromal cell telomere shortening is associated with risk of prostate cancer in the placebo arm of the Prostate Cancer Prevention Trial*

    PubMed Central

    Heaphy, Christopher M.; Gaonkar, Gaurav; Peskoe, Sarah B.; Joshu, Corinne E.; De Marzo, Angelo M.; Lucia, M. Scott; Goodman, Phyllis J.; Lippman, Scott M.; Thompson, Ian M.; Platz, Elizabeth A.; Meeker, Alan K.

    2015-01-01

    Background Telomeres are repetitive nucleoproteins that help maintain chromosomal stability by inhibiting exonucleolytic degradation, prohibiting inappropriate homologous recombination, and preventing chromosomal fusions by suppressing double-strand break signals. We recently observed that men treated for clinically localized prostate cancer with shorter telomeres in their cancer-associated stromal cells, in combination with greater variation in cancer cell telomere lengths, were significantly more likely to progress to distant metastases and die from their disease. Here, we hypothesized that shorter stromal cell telomere length would be associated with prostate cancer risk at time of biopsy. Methods Telomere-specific fluorescence in situ hybridization (FISH) analysis was performed in normal-appearing stromal, basal epithelial, and luminal epithelial cells in biopsies from men randomized to the placebo arm of the Prostate Cancer Prevention Trial. Prostate cancer cases (N=32) were either detected on a biopsy performed for cause or at the end of the study per trial protocol, and controls (N=50), defined as negative for cancer on an end-of-study biopsy performed per trial protocol (e.g. irrespective of indication), were sampled. Logistic regression was used to estimate the association between mean telomere length of the particular cell populations, cell-to-cell telomere length variability, and risk of prostate cancer. Results Men with short stromal cell telomere lengths (below median) had 2.66 (95% CI 1.04-3.06; p=0.04) times the odds of prostate cancer compared with men who had longer lengths (at or above median). Conversely, we did not observe statistically significant associations for short telomere lengths in normal-appearing basal (OR=2.15, 95% CI 0.86-5.39; p=0.10) or luminal (OR=1.15, 95% CI 0.47-2.80; p=0.77) cells. Conclusions These findings suggest that telomere shortening in normal stromal cells is associated with prostate cancer risk. It is essential to

  16. Prostate stromal cell telomere shortening is associated with risk of prostate cancer in the placebo arm of the Prostate Cancer Prevention Trial.

    PubMed

    Heaphy, Christopher M; Gaonkar, Gaurav; Peskoe, Sarah B; Joshu, Corinne E; De Marzo, Angelo M; Lucia, M Scott; Goodman, Phyllis J; Lippman, Scott M; Thompson, Ian M; Platz, Elizabeth A; Meeker, Alan K

    2015-08-01

    Telomeres are repetitive nucleoproteins that help maintain chromosomal stability by inhibiting exonucleolytic degradation, prohibiting inappropriate homologous recombination, and preventing chromosomal fusions by suppressing double-strand break signals. We recently observed that men treated for clinically localized prostate cancer with shorter telomeres in their cancer-associated stromal cells, in combination with greater variation in cancer cell telomere lengths, were significantly more likely to progress to distant metastases, and die from their disease. Here, we hypothesized that shorter stromal cell telomere length would be associated with prostate cancer risk at time of biopsy. Telomere-specific fluorescence in situ hybridization (FISH) analysis was performed in normal-appearing stromal, basal epithelial, and luminal epithelial cells in biopsies from men randomized to the placebo arm of the Prostate Cancer Prevention Trial. Prostate cancer cases (N = 32) were either detected on a biopsy performed for cause or at the end of the study per trial protocol, and controls (N = 50), defined as negative for cancer on an end-of-study biopsy performed per trial protocol (e.g., irrespective of indication), were sampled. Logistic regression was used to estimate the association between mean telomere length of the particular cell populations, cell-to-cell telomere length variability, and risk of prostate cancer. Men with short stromal cell telomere lengths (below median) had 2.66 (95% CI 1.04-3.06; P = 0.04) times the odds of prostate cancer compared with men who had longer lengths (at or above median). Conversely, we did not observe statistically significant associations for short telomere lengths in normal-appearing basal (OR = 2.15, 95% CI 0.86-5.39; P= 0 .10) or luminal (OR = 1.15, 95% CI 0.47-2.80; P = 0.77) cells. These findings suggest that telomere shortening in normal stromal cells is associated with prostate cancer risk. It is essential

  17. Telomere length maintenance--an ALTernative mechanism.

    PubMed

    Royle, N J; Foxon, J; Jeyapalan, J N; Mendez-Bermudez, A; Novo, C L; Williams, J; Cotton, V E

    2008-01-01

    The Alternative Lengthening of Telomeres (ALT) mechanism is utilised by approximately 10% of human tumours and a higher proportion of some types of sarcomas. ALT+ cell lines and tumours show heterogeneous telomere length, extra-chromosomal circular and linear telomeric DNA, ALT associated promyelocytic bodies (APBs), a high frequency of post-replication exchanges in telomeres (designated as telomere-sister chromatid exchanges, T-SCE) and high instability at a GC-rich minisatellite, MS32 (D1S8). It is clear that there is a link between the minisatellite instability and the mechanism that underpins ALT, however currently the nature of this relationship is uncertain. Single molecule analysis of telomeric DNA from ALT+ cell lines and tumours has revealed complex telomere mutations that have not been seen in cell lines or tumours that express telomerase. These complex telomere mutations cannot be explained by T-SCE but must arise by another inter-molecular process. The break-induced replication (BIR) model that may explain the observed high frequency of T-SCE and the presence of complex telomere mutations is reviewed. Copyright 2008 S. Karger AG, Basel.

  18. On the chromatin structure of eukaryotic telomeres

    PubMed Central

    Vaquero-Sedas, María I

    2011-01-01

    Telomeres prevent chromosome fusions and degradation by exonucleases and are implicated in DNA repair, homologous recombination, chromosome pairing and segregation. All these functions of telomeres require the integrity of their chromatin structure, which has been traditionally considered as heterochromatic. In agreement with this idea, different studies have reported that telomeres associate with heterochromatic marks. However, these studies addressed simultaneously the chromatin structures of telomeres and subtelomeric regions or the chromatin structure of telomeres and Interstitial Telomeric Sequences (ITSs). The independent analysis of Arabidopsis telomeres, subtelomeric regions and ITSs has allowed the discovery of euchromatic telomeres. In Arabidopsis, whereas subtelomeric regions and ITSs associate with heterochromatic marks, telomeres exhibit euchromatic features. We think that this scenario could be found in other model systems if the chromatin organizations of telomeres, subtelomeric regions and ITSs are independently analyzed. PMID:21822057

  19. Drosophila: Retrotransposons Making up Telomeres.

    PubMed

    Casacuberta, Elena

    2017-07-19

    Drosophila and extant species are the best-studied telomerase exception. In this organism, telomere elongation is coupled with targeted retrotransposition of Healing Transposon (HeT-A) and Telomere Associated Retrotransposon (TART) with sporadic additions of Telomere Associated and HeT-A Related (TAHRE), all three specialized non-Long Terminal Repeat (non-LTR) retrotransposons. These three very special retroelements transpose in head to tail arrays, always in the same orientation at the end of the chromosomes but never in interior locations. Apparently, retrotransposon and telomerase telomeres might seem very different, but a detailed view of their mechanisms reveals similarities explaining how the loss of telomerase in a Drosophila ancestor could successfully have been replaced by the telomere retrotransposons. In this review, we will discover that although HeT-A, TART, and TAHRE are still the only examples to date where their targeted transposition is perfectly tamed into the telomere biology of Drosophila, there are other examples of retrotransposons that manage to successfully integrate inside and at the end of telomeres. Because the aim of this special issue is viral integration at telomeres, understanding the base of the telomerase exceptions will help to obtain clues on similar strategies that mobile elements and viruses could have acquired in order to ensure their survival in the host genome.

  20. Accelerated Telomere Shortening in Acromegaly; IGF-I Induces Telomere Shortening and Cellular Senescence.

    PubMed

    Matsumoto, Ryusaku; Fukuoka, Hidenori; Iguchi, Genzo; Odake, Yukiko; Yoshida, Kenichi; Bando, Hironori; Suda, Kentaro; Nishizawa, Hitoshi; Takahashi, Michiko; Yamada, Shozo; Ogawa, Wataru; Takahashi, Yutaka

    2015-01-01

    Patients with acromegaly exhibit reduced life expectancy and increased prevalence of age-related diseases, such as diabetes, hypertension, and cardiovascular disease. However, the underlying mechanism has not been fully elucidated. Telomere shortening is reportedly associated with reduced life expectancy and increased prevalence of these age-related diseases. We measured telomere length in patients with acromegaly using quantitative PCR method. The effect of GH and IGF-I on telomere length and cellular senescence was examined in human skin fibroblasts. Patients with acromegaly exhibited shorter telomere length than age-, sex-, smoking-, and diabetes-matched control patients with non-functioning pituitary adenoma (0.62 ± 0.23 vs. 0.75 ± 0.35, respectively, P = 0.047). In addition, telomere length in acromegaly was negatively correlated with the disease duration (R2 = 0.210, P = 0.003). In vitro analysis revealed that not GH but IGF-I induced telomere shortening in human skin fibroblasts. Furthermore, IGF-I-treated cells showed increased senescence-associated β-galactosidase activity and expression of p53 and p21 protein. IGF-I-treated cells reached the Hayflick limit earlier than GH- or vehicle-treated cells, indicating that IGF-I induces cellular senescence. Shortened telomeres in acromegaly and cellular senescence induced by IGF-I can explain, in part, the underlying mechanisms by which acromegaly exhibits an increased morbidity and mortality in association with the excess secretion of IGF-I.

  1. A POT1 mutation implicates defective telomere end fill-in and telomere truncations in Coats plus

    PubMed Central

    Takai, Hiroyuki; Jenkinson, Emma; Kabir, Shaheen; Babul-Hirji, Riyana; Najm-Tehrani, Nasrin; Chitayat, David A.; Crow, Yanick J.; de Lange, Titia

    2016-01-01

    Coats plus (CP) can be caused by mutations in the CTC1 component of CST, which promotes polymerase α (polα)/primase-dependent fill-in throughout the genome and at telomeres. The cellular pathology relating to CP has not been established. We identified a homozygous POT1 S322L substitution (POT1CP) in two siblings with CP. POT1CP induced a proliferative arrest that could be bypassed by telomerase. POT1CP was expressed at normal levels, bound TPP1 and telomeres, and blocked ATR signaling. POT1CP was defective in regulating telomerase, leading to telomere elongation rather than the telomere shortening observed in other telomeropathies. POT1CP was also defective in the maintenance of the telomeric C strand, causing extended 3′ overhangs and stochastic telomere truncations that could be healed by telomerase. Consistent with shortening of the telomeric C strand, metaphase chromosomes showed loss of telomeres synthesized by leading strand DNA synthesis. We propose that CP is caused by a defect in POT1/CST-dependent telomere fill-in. We further propose that deficiency in the fill-in step generates truncated telomeres that halt proliferation in cells lacking telomerase, whereas, in tissues expressing telomerase (e.g., bone marrow), the truncations are healed. The proposed etiology can explain why CP presents with features distinct from those associated with telomerase defects (e.g., dyskeratosis congenita). PMID:27013236

  2. Telomeres and mechanisms of Robertsonian fusion.

    PubMed

    Slijepcevic, P

    1998-05-01

    The Robertsonian (Rb) fusion, a chromosome rearrangement involving centric fusion of two acro-(telo)centric chromosomes to form a single metacentric, is one of the most frequent events in mammalian karyotype evolution. Since one of the functions of telomeres is to preserve chromosome integrity, a prerequisite for the formation of Rb fusions should be either telomere loss or telomere inactivation. Possible mechanisms underlying the formation of various types of Rb fusion are discussed here. For example, Rb fusion in wild mice involves complete loss of p-arm telomeres by chromosome breakage within minor satellite sequences. By contrast, interstitial telomeric sites are found in the pericentromeric regions of chromosomes originating from a number of vertebrate species, suggesting the occurrence of Rb-like fusion without loss of telomeres, a possibility consistent with some form of telomere inactivation. Finally, a recent study suggests that telomere shortening induced by the deletion of the telomerase RNA gene in the mouse germ-line leads to telomere loss and high frequencies of Rb fusion in mouse somatic cells. Thus, at least three mechanisms in mammalian cells lead to the formation of Rb fusions.

  3. Telomere Length in Leukocyte DNA in Gastric Cancer Patients and its Association with Clinicopathological Features and Prognosis.

    PubMed

    Tahara, Tomomitsu; Tahara, Sayumi; Horiguchi, Noriyuki; Kawamura, Tomohiko; Okubo, Masaaki; Ishizuka, Takamitsu; Yamada, Hyuga; Yoshida, Dai; Ohmori, Takafumi; Maeda, Kohei; Komura, Naruomi; Ikuno, Hirokazu; Jodai, Yasutaka; Kamano, Toshiaki; Nagasaka, Mitsuo; Nakagawa, Yoshihito; Tuskamoto, Tetsuya; Urano, Makoto; Shibata, Tomoyuki; Kuroda, Makoto; Ohmiya, Naoki

    2017-04-01

    Telomere shortening in leukocytes has been thought to be associated with reduced immune response capacity and increased chromosome instability. Several studies indicate that telomere length in the peripheral blood leukocyte DNA can predict clinical outcome of several cancers. We evaluated the potential association between telomere shortening in the leukocyte DNA and clinicopathological features and prognosis of gastric cancer (GC) in Japanese patients. Telomere length in leukocyte DNA was measured using quantitative real-time polymerase chain reaction (PCR) in 207 GC patients. The association between telomere length and clinicopathological features and prognosis was evaluated. These short-telomere group was significantly associated with advanced stage (p=0.015), worse overall survival (OS) and progression-free survival (PFS) (p=0.046 and 0.026, respectively). The same group was also weakly associated with overall and peritoneal recurrences (p=0.052 and 0.059, respectively). Telomere shortening in leukocyte DNA is associated with advanced stage and poor prognosis of GC, which may reflect their reduced immune response capacity or increased chromosome instability. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

  4. Analysis of Average Telomere Length in Human Telomeric Protein Knockout Cells Generated by CRISPR/Cas9.

    PubMed

    Xu, Jun; Songyang, Zhou; Liu, Dan; Kim, Hyeung

    2017-01-01

    Telomeres play an important role in ensuring the integrity of the genome. Telomere shortening can lead to loss of genetic information and trigger DNA damage responses. Cultured mammalian cells have served as critical model systems for studying the function of telomere binding proteins and telomerase. Tremendous heterogeneity can be observed both between species and within a single cell population. Recent advances in genome editing (such as the development of the CRISPR/Cas9 platform) have further enabled researchers to carry out loss-of-function analysis of how disrupting key players in telomere maintenance affects telomere length regulation. Here we describe the steps to be carried out in order to analyze the average length of telomeres in CRISPR-engineered human knockout (KO) cells (TRF analysis).

  5. Shelterin Protects Chromosome Ends by Compacting Telomeric Chromatin

    PubMed Central

    Bandaria, Jigar N.; Qin, Peiwu; Berk, Veysel; Chu, Steven; Yildiz, Ahmet

    2016-01-01

    SUMMARY Telomeres, repetitive DNA sequences at chromosome ends, are shielded against the DNA damage response (DDR) by the shelterin complex. To understand how shelterin protects telomere ends, we investigated the structural organization of telomeric chromatin in human cells using super-resolution microscopy. We found that telomeres form compact globular structures through a complex network of interactions between shelterin subunits and telomeric DNA, and not by DNA methylation, histone deacetylation or histone trimethylation at telomeres and subtelomeric regions. Mutations that abrogate shelterin assembly or removal of individual subunits from telomeres cause up to a 10-fold increase in telomere volume. Decompacted telomeres become more accessible to telomere-associated proteins and accumulate DDR signals. Recompaction of telomeric chromatin using an orthogonal method displaces DDR signals from telomeres. These results reveal the chromatin remodeling activity of shelterin and demonstrate that shelterin-mediated compaction of telomeric chromatin provides robust protection of chromosome ends against the DDR machinery. PMID:26871633

  6. Accelerated Telomere Shortening in Acromegaly; IGF-I Induces Telomere Shortening and Cellular Senescence

    PubMed Central

    Matsumoto, Ryusaku; Fukuoka, Hidenori; Iguchi, Genzo; Odake, Yukiko; Yoshida, Kenichi; Bando, Hironori; Suda, Kentaro; Nishizawa, Hitoshi; Takahashi, Michiko; Yamada, Shozo; Ogawa, Wataru; Takahashi, Yutaka

    2015-01-01

    Objective Patients with acromegaly exhibit reduced life expectancy and increased prevalence of age-related diseases, such as diabetes, hypertension, and cardiovascular disease. However, the underlying mechanism has not been fully elucidated. Telomere shortening is reportedly associated with reduced life expectancy and increased prevalence of these age-related diseases. Methods We measured telomere length in patients with acromegaly using quantitative PCR method. The effect of GH and IGF-I on telomere length and cellular senescence was examined in human skin fibroblasts. Results Patients with acromegaly exhibited shorter telomere length than age-, sex-, smoking-, and diabetes-matched control patients with non-functioning pituitary adenoma (0.62 ± 0.23 vs. 0.75 ± 0.35, respectively, P = 0.047). In addition, telomere length in acromegaly was negatively correlated with the disease duration (R 2 = 0.210, P = 0.003). In vitro analysis revealed that not GH but IGF-I induced telomere shortening in human skin fibroblasts. Furthermore, IGF-I-treated cells showed increased senescence-associated β-galactosidase activity and expression of p53 and p21 protein. IGF-I-treated cells reached the Hayflick limit earlier than GH- or vehicle-treated cells, indicating that IGF-I induces cellular senescence. Conclusion Shortened telomeres in acromegaly and cellular senescence induced by IGF-I can explain, in part, the underlying mechanisms by which acromegaly exhibits an increased morbidity and mortality in association with the excess secretion of IGF-I. PMID:26448623

  7. Regulation of Telomere Length Requires a Conserved N-Terminal Domain of Rif2 in Saccharomyces cerevisiae

    PubMed Central

    Kaizer, Hannah; Connelly, Carla J.; Bettridge, Kelsey; Viggiani, Christopher; Greider, Carol W.

    2015-01-01

    The regulation of telomere length equilibrium is essential for cell growth and survival since critically short telomeres signal DNA damage and cell cycle arrest. While the broad principles of length regulation are well established, the molecular mechanism of how these steps occur is not fully understood. We mutagenized the RIF2 gene in Saccharomyces cerevisiae to understand how this protein blocks excess telomere elongation. We identified an N-terminal domain in Rif2 that is essential for length regulation, which we have termed BAT domain for Blocks Addition of Telomeres. Tethering this BAT domain to Rap1 blocked telomere elongation not only in rif2Δ mutants but also in rif1Δ and rap1C-terminal deletion mutants. Mutation of a single amino acid in the BAT domain, phenylalanine at position 8 to alanine, recapitulated the rif2Δ mutant phenotype. Substitution of F8 with tryptophan mimicked the wild-type phenylalanine, suggesting the aromatic amino acid represents a protein interaction site that is essential for telomere length regulation. PMID:26294668

  8. Population mixture model for nonlinear telomere dynamics

    NASA Astrophysics Data System (ADS)

    Itzkovitz, Shalev; Shlush, Liran I.; Gluck, Dan; Skorecki, Karl

    2008-12-01

    Telomeres are DNA repeats protecting chromosomal ends which shorten with each cell division, eventually leading to cessation of cell growth. We present a population mixture model that predicts an exponential decrease in telomere length with time. We analytically solve the dynamics of the telomere length distribution. The model provides an excellent fit to available telomere data and accounts for the previously unexplained observation of telomere elongation following stress and bone marrow transplantation, thereby providing insight into the nature of the telomere clock.

  9. Telomere Capping Proteins are Structurally Related to RPA with an additional Telomere-Specific Domain

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gelinas, A.; Paschini, M; Reyes, F

    Telomeres must be capped to preserve chromosomal stability. The conserved Stn1 and Ten1 proteins are required for proper capping of the telomere, although the mechanistic details of how they contribute to telomere maintenance are unclear. Here, we report the crystal structures of the C-terminal domain of the Saccharomyces cerevisiae Stn1 and the Schizosaccharomyces pombe Ten1 proteins. These structures reveal striking similarities to corresponding subunits in the replication protein A complex, further supporting an evolutionary link between telomere maintenance proteins and DNA repair complexes. Our structural and in vivo data of Stn1 identify a new domain that has evolved to supportmore » a telomere-specific role in chromosome maintenance. These findings endorse a model of an evolutionarily conserved mechanism of DNA maintenance that has developed as a result of increased chromosomal structural complexity.« less

  10. Telomere length analysis in Down syndrome birth.

    PubMed

    Bhaumik, Pranami; Bhattacharya, Mandar; Ghosh, Priyanka; Ghosh, Sujay; Kumar Dey, Subrata

    2017-06-01

    Human reproductive fitness depends upon telomere chemistry. Maternal age, meiotic nondisjunction error and telomere length of mother of trisomic child are someway associated. Reports exhibiting maternal inheritance of telomere length in Down syndrome child are very scanty. To investigate this, we collected peripheral blood from 170 mothers of Down syndrome child and 186 age matched mothers of euploid child with their newly born babies. Telomere length was measured by restriction digestion - southern blotting technique. Meiotic nondisjunction error was detected by STR genotyping. Subjects are classified by age (old >35 years and young ˂35 years) and by meiotic error (MI and MII). Linear regression was run to explore the age - telomere length relationship in each maternal groups. The study reveals that with age, telomere erodes in length. Old MII mothers carry the shortest (p˂0.001), control mothers have the longest telomere and MI lies in between. Babies from older mother have longer telomere (p˂0.001) moreover; telomeres are longer in Down syndrome babies than control babies (p˂0.001). To conclude, this study represents not only the relation between maternal aging and telomere length but also explore the maternal heritability of telomere length in families with Down syndrome child. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Alternative lengthening of telomeres and loss of ATRX are frequent events in pleomorphic and dedifferentiated liposarcomas.

    PubMed

    Lee, Jen-Chieh; Jeng, Yung-Ming; Liau, Jau-Yu; Tsai, Jia-Huei; Hsu, Hung-Han; Yang, Ching-Yao

    2015-08-01

    Telomerase activation and alternative lengthening of telomeres are two major mechanisms of telomere length maintenance. Soft tissue sarcomas appear to use the alternative lengthening of telomeres more frequently. Loss of α-thalassemia/mental retardation syndrome X-linked (ATRX) or death domain-associated protein 6 (DAXX) expression has been implicated in the pathogenesis of alternative telomere lengthening in pancreatic endocrine neoplasm and glioma. The mechanism leading to the alternative lengthening of telomeres in liposarcoma remains unknown. Whereas alternative telomere lengthening was determined to be an indicator of poor prognosis in liposarcomas as a whole, its prognostic power has not been verified in any subtype of liposarcoma. In this study, we characterized the status of alternative telomere lengthening and expression of ATRX and DAXX in 111 liposarcomas (28 well-differentiated, 52 dedifferentiated, 20 myxoid or round cell, and 11 pleomorphic liposarcomas) by telomere fluorescence in situ hybridization and immunohistochemistry, respectively. Alternative lengthening of telomere was observed in 0% (0/16) of well-differentiated, 30% (14/46) of dedifferentiated, 5% (1/19) of myxoid or round cell, and 80% (8/10) of pleomorphic liposarcomas. Eighteen (16%) and one (1%) tumors were negative for ATRX and DAXX immunostaining, respectively. Remarkably, all cases with loss of either ATRX or DAXX expression had alternative lengthening of telomeres, and 83% (19/23) of tumors that had alternative lengthening of telomeres showed loss of either protein. The correlation between loss of either ATRX or DAXX and alternative telomere lengthening was 100% in dedifferentiated liposarcoma. The presence of alternative telomere lengthening in dedifferentiated liposarcoma suggested poor overall survival (hazard ratio=1.954, P=0.077) and was the most significant indicator of short progression-free survival (hazard ratio=3.119, P=0.003). In conclusion, we found that ATRX loss was

  12. Evolutionary ecology of telomeres: a review.

    PubMed

    Olsson, Mats; Wapstra, Erik; Friesen, Christopher R

    2018-06-01

    Telomere-induced selection could take place if telomere-associated disease risk shortens reproductive life span and differently reduces relative fitness among individuals. Some of these diseases first appear before reproductive senescence and could thus influence ongoing selection. We ask whether we can estimate the components of the breeder's equation for telomeres, in which the response to selection (R, by definition "evolution") is the product of ongoing selection (S) and heritability (h 2 ). However, telomere inheritance is a conundrum: in quantitative genetics, traits can usually be allocated to categories with relatively high or low heritability, depending on their association with relative fitness. Telomere traits, however, show wide variation in heritability from zero to one, across taxa, gender, ethnicity, age, and disease status. In spite of this, there is divergence in telomere length among populations, supporting past and ongoing telomere evolution. Rates of telomere attrition and elongation vary among taxa with some, but not complete, taxonomic coherence. For example, telomerase is commonly referred to as "restricted to the germ line in mammals," but inbred mice and beavers have telomerase upregulation in somatic tissue, as do many ectotherms. These observations provoke a simplistic understanding of telomere evolutionary biology-clearly much is yet to be discovered. © 2017 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals, Inc. on behalf of The New York Academy of Sciences.

  13. The cohering telomeres of Oxytricha.

    PubMed Central

    Oka, Y; Thomas, C A

    1987-01-01

    We have studied the process by which purified Oxytricha macronuclear DNA associates with itself to form large aggregates. The various macronuclear DNA molecules all have the same terminal or telomeric DNA sequences that are shown below. 5' C4A4C4A4C4--mean length----G4T4G4T4G4T4G4T4G4 G4T4G4T4G4T4G4T4G4-----2.4 kb------C4A4C4A4C4. When incubated at high concentrations, these telomeric sequences cohere with one another to form an unusual structure--one that is quite different from any DNA structure so far described. The evidence for this is the following: 1) These sequences cohere albeit slowly, in the presence of relatively high concentrations of Na+, and no other cation tested. This contrasts with the rapid coherence of complementary single-chain terminals of normal DNA (sticky ends) which occurs in the presence of any cation tested. 2) If the cohered form is transferred into buffers containing a special cation, K+, it becomes much more resistant to dissociation by heating. We estimate that K+ increases the thermal stability by 25 degrees or more. The only precedent known (to us) for a cation-specific stabilization is that seen in the quadruplex structure formed by poly I. The thermal stability of double helical macronuclear DNA depends on the cation concentration, but not the cation type. Limited treatment with specific nucleases show that the 3' and 5'-ended strands are essential for the formation of the cohering structure. Once in the cohered form, the telomeric sequences are protected from the action of nucleases. Coherence is inhibited by specific, but not by non-specific, synthetic oligomers, and by short telomeric fragments with or without their terminal single chains. We conclude that the coherence occurs by the formation of a novel condensed structure that involves the terminal nucleotides in three or four chains. Images PMID:3120149

  14. Single-strand DNA binding protein SSB1 facilitates TERT recruitment to telomeres and maintains telomere G-overhangs

    PubMed Central

    Pandita, Raj K.; Chow, Tracy T.; Udayakumar, Durga; Bain, Amanda L.; Cubeddu, Liza; Hunt, Clayton R.; Shi, Wei; Horikoshi, Nobuo; Zhao, Yong; Wright, Woodring E.; Khanna, Kum Kum; Shay, Jerry W.; Pandita, Tej K.

    2015-01-01

    Proliferating mammalian stem and cancer cells express telomerase (TERT) in an effort to extend chromosomal G-overhangs and maintain telomere ends. Telomerase-expressing cells also have higher levels of the single-stranded DNA binding protein SSB1, which has a critical role in DNA double-strand break repair. Here we report that SSB1 binds specifically to G-strand telomeric DNA in vitro and associates with telomeres in vivo. SSB1 interacted with the TERT catalytic subunit and regulates its interaction with telomeres. Deletion of SSB1 reduced TERT interaction with telomeres and lead to G-overhang loss. While SSB1 was recruited to DSB sites, we found no corresponding change in TERT levels at these sites, implying that SSB1-TERT interaction relied upon a specific chromatin structure or context. Our findings offer an explanation for how telomerase is recruited to telomeres to facilitate G-strand DNA extension, a critical step in maintaining telomere ends and cell viability in all cancer cells. PMID:25589350

  15. Telomere length and mortality in the Ludwigshafen Risk and Cardiovascular Health study

    PubMed Central

    Pusceddu, Irene; Kleber, Marcus; Delgado, Graciela; Herrmann, Wolfgang; März, Winfried; Herrmann, Markus

    2018-01-01

    Introduction Short telomeres have been associated with adverse lifestyle factors, cardiovascular risk factors and age-related diseases, including cardiovascular disease (CVD), myocardial infarction, atherosclerosis, hypertension, diabetes, and also with mortality. However, previous studies report conflicting results. Objectives The aim of the present study has been to investigate the involvement of telomere length in all-cause and CVD mortality in subjects hospitalized for diagnostic coronary angiography of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study. Methods Relative telomere length (RTL) was measured with a Q-PCR based method in 3,316 participants of the LURIC study. Age-corrected RTL was calculated as the ratio between RTL and age. Median follow-up was 9.9 years. Cox regression and Kaplan-Maier analyses were performed to evaluate the role of RTL for all-cause and cardiovascular mortality. Results RTL correlated negatively with age (r = -0.09; p<0.001). In surviving patients the correlation between age and RTL was statistically significant (r = -0.088; p<0.001), but not in patients who died during follow-up (r = -0.043; p = 0.20). Patients in quartiles 2–4 of RTL had a lower hazard ratio for all-cause mortality (HR:0.822; 95%CI 0.712–0.915; p = 0.008) and CVD-mortality (HR:0.836; 95%CI 0.722–0.969; p = 0.017) when compared to those in the 1st quartile. Adjustment for major cardiovascular risk factors did not change this result, however additional adjustment for age attenuated this effect. Patients in the 4th quartile of age-corrected RTL compared to those in the 1st quartile had a lower hazard ratio for all-cause mortality, even with adjustment for major cardiovascular risk factors. Conclusions The present study supports the hypothesis that short telomere length increases the risk of all-cause and CVD mortality. Age appears to be an important co-variate that explains a substantial fraction of this effect. It remains unclear whether short

  16. Influence of Telomere Length in Hepatocytes on Liver Regeneration after Partial Hepatectomy in Rats.

    PubMed

    Andert, Anne; Alizai, Hamid P; Ulmer, Tom Florian; Heidenhain, Christoph; Ziegler, Patrick; Brümmendorf, Tim H; Neumann, Ulf Peter; Beier, Fabian; Klink, Christian D

    2018-06-08

    The aim of this study was to investigate telomere length in hepatocytes as a biomarker for liver regeneration after partial hepatectomy (PH) in rats. Sixty male Wistar rats underwent a 70% PH. One-month-old rats were assigned to group Y (n = 30) and 4-month-old rats were assigned to group O (n = 30). The rats were euthanized, and their livers were then harvested at postoperative day (POD) 1, 2, 3, 4, or 7. Telomere lengths and established parameters for liver regeneration (residual liver weight and levels of proliferating cell nuclear antigen [PCNA], Ki67, and interleukin [IL]-6) were measured. We observed a significant increase in residual liver weight in group Y compared to that in group O (p = 0.001). The levels of Ki67 (p = 0.016), PCNA (p < 0.0001), and IL-6 (p < 0.001) were significantly higher in group Y. Furthermore, the rats in group Y had significantly earlier peak values of Ki67 and PCNA. Telomeres were significantly longer at the time of PH in group Y (p = 0.001). We showed a correlation between telomere length at the day of PH and liver regeneration. Animals with longer telomeres at the time of PH had better liver regeneration (p = 0.015). In group Y, animals with increased liver regeneration (median cut-off: > 122%) did not show any significant difference in telomere length (p = 0.587) compared to rats with regular regeneration (< 122%). However, in the older animals, rats with increased regeneration had significantly longer telomeres (p = 0.019) than rats with regular regeneration. Telomere length in rat hepatocytes depends on age, and animals with long telomeres had earlier and better regeneration of healthy liver tissue than rats with short telomeres. Our data confirms that telomere length in rat hepatocytes could be used as a possible predictive marker for liver regeneration, and could help to identify older individuals with a high capacity for hepatic regeneration. © 2018 S. Karger AG, Basel.

  17. Maternal telomere length inheritance in the king penguin.

    PubMed

    Reichert, S; Rojas, E R; Zahn, S; Robin, J-P; Criscuolo, F; Massemin, S

    2015-01-01

    Telomeres are emerging as a biomarker for ageing and survival, and are likely important in shaping life-history trade-offs. In particular, telomere length with which one starts in life has been linked to lifelong survival, suggesting that early telomere dynamics are somehow related to life-history trajectories. This result highlights the importance of determining the extent to which telomere length is inherited, as a crucial factor determining early life telomere length. Given the scarcity of species for which telomere length inheritance has been studied, it is pressing to assess the generality of telomere length inheritance patterns. Further, information on how this pattern changes over the course of growth in individuals living under natural conditions should provide some insight on the extent to which environmental constraints also shape telomere dynamics. To fill this gap partly, we followed telomere inheritance in a population of king penguins (Aptenodytes patagonicus). We tested for paternal and maternal influence on chick initial telomere length (10 days old after hatching), and how these relationships changed with chick age (at 70, 200 and 300 days old). Based on a correlative approach, offspring telomere length was positively associated with maternal telomere length early in life (at 10 days old). However, this relationship was not significant at older ages. These data suggest that telomere length in birds is maternally inherited. Nonetheless, the influence of environmental conditions during growth remained an important factor shaping telomere length, as the maternal link disappeared with chicks' age.

  18. Change in Leukocyte Telomere Length Predicts Mortality in Patients with Stable Coronary Heart Disease from the Heart and Soul Study.

    PubMed

    Goglin, Sarah E; Farzaneh-Far, Ramin; Epel, Elissa S; Lin, Jue; Blackburn, Elizabeth H; Whooley, Mary A

    2016-01-01

    Short telomere length independently predicts mortality in patients with coronary heart disease. Whether 5-year change in telomere length predicts subsequent mortality in patients with coronary heart disease has not been evaluated. In a prospective cohort study of 608 individuals with stable coronary artery disease, we measured leukocyte telomere length at baseline and after five years of follow-up. We divided the sample into tertiles of telomere change: shortened, maintained or lengthened. We used Cox survival models to evaluate 5-year change in telomere length as a predictor of mortality. During an average of 4.2 years follow-up, there were 149 deaths. Change in telomere length was inversely predictive of all-cause mortality. Using the continuous variable of telomere length change, each standard deviation (325 base pair) greater increase in telomere length was associated with a 24% reduction in mortality (HR 0.76, 95% CI 0.61-0.94; p = 0.01), adjusted for age, sex, waist to hip ratio, exercise capacity, LV ejection fraction, serum creatinine, and year 5 telomere length. Mortality occurred in 39% (79/203) of patients who experienced telomere shortening, 22% (45/203) of patients whose telomere length was maintained, and 12% (25/202) of patients who experienced telomere lengthening (p<0.001). As compared with patients whose telomere length was maintained, those who experienced telomere lengthening were 56% less likely to die (HR 0.44, 95% CI, 0.23-0.87). In patients with coronary heart disease, an increase in leukocyte telomere length over 5 years is associated with decreased mortality.

  19. The Drosophila telomere-capping protein Verrocchio binds single-stranded DNA and protects telomeres from DNA damage response

    PubMed Central

    Cicconi, Alessandro; Micheli, Emanuela; Vernì, Fiammetta; Jackson, Alison; Gradilla, Ana Citlali; Cipressa, Francesca; Raimondo, Domenico; Bosso, Giuseppe; Wakefield, James G.; Ciapponi, Laura; Cenci, Giovanni; Gatti, Maurizio

    2017-01-01

    Abstract Drosophila telomeres are sequence-independent structures maintained by transposition to chromosome ends of three specialized retroelements rather than by telomerase activity. Fly telomeres are protected by the terminin complex that includes the HOAP, HipHop, Moi and Ver proteins. These are fast evolving, non-conserved proteins that localize and function exclusively at telomeres, protecting them from fusion events. We have previously suggested that terminin is the functional analogue of shelterin, the multi-protein complex that protects human telomeres. Here, we use electrophoretic mobility shift assay (EMSA) and atomic force microscopy (AFM) to show that Ver preferentially binds single-stranded DNA (ssDNA) with no sequence specificity. We also show that Moi and Ver form a complex in vivo. Although these two proteins are mutually dependent for their localization at telomeres, Moi neither binds ssDNA nor facilitates Ver binding to ssDNA. Consistent with these results, we found that Ver-depleted telomeres form RPA and γH2AX foci, like the human telomeres lacking the ssDNA-binding POT1 protein. Collectively, our findings suggest that Drosophila telomeres possess a ssDNA overhang like the other eukaryotes, and that the terminin complex is architecturally and functionally similar to shelterin. PMID:27940556

  20. Single-strand DNA-binding protein SSB1 facilitates TERT recruitment to telomeres and maintains telomere G-overhangs.

    PubMed

    Pandita, Raj K; Chow, Tracy T; Udayakumar, Durga; Bain, Amanda L; Cubeddu, Liza; Hunt, Clayton R; Shi, Wei; Horikoshi, Nobuo; Zhao, Yong; Wright, Woodring E; Khanna, Kum Kum; Shay, Jerry W; Pandita, Tej K

    2015-03-01

    Proliferating mammalian stem and cancer cells express telomerase [telomerase reverse transcriptase (TERT)] in an effort to extend chromosomal G-overhangs and maintain telomere ends. Telomerase-expressing cells also have higher levels of the single-stranded DNA-binding protein SSB1, which has a critical role in DNA double-strand break (DSB) repair. Here, we report that SSB1 binds specifically to G-strand telomeric DNA in vitro and associates with telomeres in vivo. SSB1 interacts with the TERT catalytic subunit and regulates its interaction with telomeres. Deletion of SSB1 reduces TERT interaction with telomeres and leads to G-overhang loss. Although SSB1 is recruited to DSB sites, we found no corresponding change in TERT levels at these sites, implying that SSB1-TERT interaction relies upon a specific chromatin structure or context. Our findings offer an explanation for how telomerase is recruited to telomeres to facilitate G-strand DNA extension, a critical step in maintaining telomere ends and cell viability in all cancer cells. Cancer Res; 75(5); 858-69. ©2015 AACR. ©2015 American Association for Cancer Research.

  1. Rad6–Bre1-mediated H2B ubiquitination regulates telomere replication by promoting telomere-end resection

    PubMed Central

    Wu, Zhenfang; Liu, Jun; Zhang, Qiong-Di; Lv, De-Kang; Wu, Nian-Feng

    2017-01-01

    Abstract Rad6 and Bre1, ubiquitin-conjugating E2 and E3 enzymes respectively, are responsible for histone H2B lysine 123 mono-ubiquitination (H2Bub1) in Saccharomyces cerevisiae. Previous studies have shown that Rad6 and Bre1 regulate telomere length and recombination. However, the underlying molecular mechanism remains largely unknown. Here we report that H2BK123 mutation results in telomere shortening, while inactivation of Ubp8 and/or Ubp10, deubiquitinases of H2Bub1, leads to telomere lengthening in Rad6–Bre1-dependent manner. In telomerase-deficient cells, inactivation of Rad6–Bre1 pathway retards telomere shortening rate and the onset of senescence, while deletion of UBP8 and/or UBP10 accelerates senescence. Thus, Rad6–Bre1 pathway regulates both telomere length and recombination through its role in H2Bub1. Additionally, inactivation of both Rad6–Bre1–H2Bub1 and Mre11–Rad50–Xrs2 (MRX) pathways causes synthetic growth defects and telomere shortening in telomerase-proficient cells, and significantly accelerates senescence and eliminates type II telomere recombination in telomerase-deficient cells. Furthermore, RAD6 or BRE1 deletion, or H2BK123R mutation decreases the accumulation of ssDNA at telomere ends. These results support the model that Rad6–Bre1–H2Bub1 cooperates with MRX to promote telomere-end resection and thus positively regulates both telomerase- and recombination-dependent telomere replication. This study provides a mechanistic link between histone H2B ubiquitination and telomere replication. PMID:28180293

  2. Defects in lymphocyte telomere homeostasis contribute to cellular immune phenotype in patients with cartilage-hair hypoplasia.

    PubMed

    Aubert, Geraldine; Strauss, Kevin A; Lansdorp, Peter M; Rider, Nicholas L

    2017-10-01

    Mutations in the long noncoding RNA RNase component of the mitochondrial RNA processing endoribonuclease (RMRP) give rise to the autosomal recessive condition cartilage-hair hypoplasia (CHH). The CHH disease phenotype has some overlap with dyskeratosis congenita, a well-known "telomere disorder." RMRP binds the telomerase reverse transcriptase (catalytic subunit) in some cell lines, raising the possibility that RMRP might play a role in telomere biology. We sought to determine whether a telomere phenotype is present in immune cells from patients with CHH and explore mechanisms underlying these observations. We assessed proliferative capacity and telomere length using flow-fluorescence in situ hybridization (in situ hybridization and flow cytometry) of primary lymphocytes from patients with CHH, carrier relatives, and control subjects. The role of telomerase holoenzyme components in gene expression and activity were assessed by using quantitative PCR and the telomere repeat amplification protocol from PBMCs and enriched lymphocyte cultures. Lymphocyte cultures from patients with CHH display growth defects in vitro, which is consistent with an immune deficiency cellular phenotype. Here we show that telomere length and telomerase activity are impaired in primary lymphocyte subsets from patients with CHH. Notably, telomerase activity is affected in a gene dose-dependent manner when comparing heterozygote RMRP carriers with patients with CHH. Telomerase deficiency in patients with CHH is not mediated by abnormal telomerase gene transcript levels relative to those of endogenous genes. These findings suggest that telomere deficiency is implicated in the CHH disease phenotype through an as yet unidentified mechanism. Copyright © 2017 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  3. Leukocyte Telomere Length in the Neonatal Offspring of Mothers with Gestational and Pre-Gestational Diabetes.

    PubMed

    Gilfillan, Christopher; Naidu, Pratyusha; Gunawan, Florence; Hassan, Fadwa; Tian, Pei; Elwood, Ngaire

    2016-01-01

    Telomeres undergo shortening with cell division, accelerated by increased oxidative stress. We aimed to demonstrate shortened telomeres in the offspring of mothers who have diabetes as a consequence of exposure to increased oxidative stress during intrauterine development. We examined the level of glycaemia (glucose, HbA1c, fructosamine), oxidative stress (lipid peroxidation) and the levels of antioxidant enzymes (Superoxide dismutase (SOD) and Selenium dependent glutathione peroxidase) and correlate these findings with mean telomere length (TL) in maternal and foetal blood in groups of pregnant women with pre-gestational diabetes (PGD), gestational diabetes (GD) and a euglycaemic control group. Foetal and maternal glucose, maternal HbA1c, and foetal insulin and C-peptide were higher in the PGD group with the GD group being intermediate. Markers of oxidative stress did not vary between groups with the exception of foetal SOD activity that was highest in the GD group. There were no detectable differences in maternal or foetal TL between study groups. An exploratory analysis looking at correlations between glycaemic and oxidative stress parameters and TL revealed a negative correlation between maternal and foetal glucose and TL across the whole study population. This relationship held for the short-term marker of glycaemic control, fructosamine. We were unable to show significant telomere shortening in the offspring of mothers with PGD or GD. Exploratory analysis revealed a relationship between foetal TL and short-term glycaemia particularly in PGD. It is possible that increased telomerase activity can compensate for long-term increased oxidative stress but not for short-term dysglycaemia.

  4. Telomere length and telomere repeating factors: Cellular markers for post-traumatic stress disorder-like model.

    PubMed

    Dong, Yuanjun; Zhang, Guiqing; Yuan, Xiuyu; Zhang, Yueqi; Hu, Min

    2016-05-01

    The aim of the present study was to explore the telomere length of peripheral blood leukocytes from a rat model of post-traumatic stress disorder (PTSD), as well as the expression level of telomere-binding protein in the hippocampal CA1 region. The PTSD model was established with 42 adult male Wistar rats. The relative telomere length of the leukocytes was measured by real-time fluorescence quantitative polymerase chain reaction, and the expression levels of telomere repeating factor 1 (TRF1) and telomere repeating factor 2 (TRF2) in the hippocampal CA1 region of the PTSD rat model were determined by immunofluorescence technology. The covariance analysis of repeated measurements by the mixed model approach was used for the telomere length analysis. The comparison of averaged data among groups was performed using least significant difference and analysis of variance. The Student's t test or the Mann-Whitney U test was used for intragroup comparison. The association study among groups was conducted using the Spearman test. The shortening speed of telomere length significantly accelerated in rats after Single Prolonged Stress (SPS) stimulation (P<0.05). The expression levels of TRF1 and TRF2 increased with the progress of PTSD, and the expression peak was shown in day 14, which was significantly different from the control group (P<0.05). The shortening speed of the telomere length of peripheral blood leukocytes accelerated in PTSD rats, and the expression levels of TRF1 and TRF2 increased in hippocampus, both of which were closely associated with the pathological progress of the PTSD-like model and unfavorable prognosis. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Telomere Biology—Insights into an Intriguing Phenomenon

    PubMed Central

    Venkatesan, Shriram; Khaw, Aik Kia; Hande, Manoor Prakash

    2017-01-01

    Bacteria and viruses possess circular DNA, whereas eukaryotes with typically very large DNA molecules have had to evolve into linear chromosomes to circumvent the problem of supercoiling circular DNA of that size. Consequently, such organisms possess telomeres to cap chromosome ends. Telomeres are essentially tandem repeats of any DNA sequence that are present at the ends of chromosomes. Their biology has been an enigmatic one, involving various molecules interacting dynamically in an evolutionarily well-trimmed fashion. Telomeres range from canonical hexameric repeats in most eukaryotes to unimaginably random retrotransposons, which attach to chromosome ends and reverse-transcribe to DNA in some plants and insects. Telomeres invariably associate with specialised protein complexes that envelop it, also regulating access of the ends to legitimate enzymes involved in telomere metabolism. They also transcribe into repetitive RNA which also seems to be playing significant roles in telomere maintenance. Telomeres thus form the intersection of DNA, protein, and RNA molecules acting in concert to maintain chromosome integrity. Telomere biology is emerging to appear ever more complex than previously envisaged, with the continual discovery of more molecules and interplays at the telomeres. This review also includes a section dedicated to the history of telomere biology, and intends to target the scientific audience new to the field by rendering an understanding of the phenomenon of chromosome end protection at large, with more emphasis on the biology of human telomeres. The review provides an update on the field and mentions the questions that need to be addressed. PMID:28629193

  6. Binding polarity of RPA to telomeric sequences and influence of G-quadruplex stability.

    PubMed

    Safa, Layal; Delagoutte, Emmanuelle; Petruseva, Irina; Alberti, Patrizia; Lavrik, Olga; Riou, Jean-François; Saintomé, Carole

    2014-08-01

    Replication protein A (RPA) is a single-stranded DNA binding protein that plays an essential role in telomere maintenance. RPA binds to and unfolds G-quadruplex (G4) structures formed in telomeric DNA, thus facilitating lagging strand DNA replication and telomerase activity. To investigate the effect of G4 stability on the interactions with human RPA (hRPA), we used a combination of biochemical and biophysical approaches. Our data revealed an inverse relationship between G4 stability and ability of hRPA to bind to telomeric DNA; notably small G4 ligands that enhance G4 stability strongly impaired G4 unfolding by hRPA. To gain more insight into the mechanism of binding and unfolding of telomeric G4 structures by RPA, we carried out photo-crosslinking experiments to elucidate the spatial arrangement of the RPA subunits along the DNA strands. Our results showed that RPA1 and RPA2 are arranged from 5' to 3' along the unfolded telomeric G4, as already described for unstructured single-stranded DNA, while no contact is possible with RPA3 on this short oligonucleotide. In addition, these data are compatible with a 5' to 3' directionality in G4 unfolding by hRPA. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  7. Telomere Damage Response and Low-Grade Inflammation.

    PubMed

    Wang, Lihui; Yu, Xianhua; Liu, Jun-Ping

    2017-01-01

    Telomeres at the ends of chromosomes safeguard genome integrity and stability in human nucleated cells. However, telomere repeats shed off during cell proliferation and other stress responses. Our recent studies show that telomere attrition induces not only epithelial stem cell senescence but also low-grade inflammation in the lungs. The senescence-associated low-grade inflammation (SALI) is characteristic of alveolar stem cell replicative senescence, increased proinflammatory and anti-inflammatory cytokines, infiltrated immune cells, and spillover effects. To date, the mechanisms underlying SALI remain unclear. Investigations demonstrate that senescent epithelial stem cells with telomere erosion are not the source of secreted cytokines, containing no significant increase in expression of the genes coding for increased cytokines, suggesting an alternative senescence-associated secretory phenotype (A-SASP). Given that telomere loss results in significant alterations in the genomes and accumulations of the cleaved telomeric DNA in the cells and milieu externe, we conclude that telomere position effects (TPEs) on gene expression and damage-associated molecular patterns (DAMPs) in antigen presentation are involved in A-SASP and SALI in response to telomere damage in mammals.

  8. A subject with abnormally short stature from Imperial Rome.

    PubMed

    Ottini, L; Minozzi, S; Pantano, W B; Maucci, C; Gazzaniga, V; Angeletti, L R; Catalano, P; Mariani-Costantini, R

    2001-01-01

    In spite of the rich iconographic and literary documentation from ancient sources, the skeletal evidence concerning individuals of abnormally short stature in the Greco-Roman world is scarce. The necropolis of Viale della Serenissima/Via Basiliano in Rome, mostly referable to the II century AD, recently yielded the skeleton of an individual characterized by proportionate short stature, gracile features suggesting female gender, and delayed epiphysial closure, associated with full maturation of the permanent dentition. These characteristics could be compatible with the phenotype associated with female gonadal dysgenesis. The skeletal individual described here, although poorly preserved, represents the first evidence of a paleopathologic condition affecting skeletal growth documented for the population of ancient Rome.

  9. Human cancer cells utilize mitotic DNA synthesis to resist replication stress at telomeres regardless of their telomere maintenance mechanism

    PubMed Central

    Özer, Özgün; Bhowmick, Rahul; Liu, Ying; Hickson, Ian D.

    2018-01-01

    Telomeres resemble common fragile sites (CFSs) in that they are difficult-to-replicate and exhibit fragility in mitosis in response to DNA replication stress. At CFSs, this fragility is associated with a delay in the completion of DNA replication until early mitosis, whereupon cells are proposed to switch to a RAD52-dependent form of break-induced replication. Here, we show that this mitotic DNA synthesis (MiDAS) is also a feature of human telomeres. Telomeric MiDAS is not restricted to those telomeres displaying overt fragility, and is a feature of a wide range of cell lines irrespective of whether their telomeres are maintained by telomerase or by the alternative lengthening of telomeres (ALT) mechanism. MiDAS at telomeres requires RAD52, and is mechanistically similar to CFS-associated MiDAS, with the notable exception that telomeric MiDAS does not require the MUS81-EME1 endonuclease. We propose a model whereby replication stress initiates a RAD52-dependent form of break-induced replication that bypasses a requirement for MUS81-EME1 to complete DNA synthesis in mitosis. PMID:29662610

  10. Assessing Telomere Length Using Surface Enhanced Raman Scattering

    NASA Astrophysics Data System (ADS)

    Zong, Shenfei; Wang, Zhuyuan; Chen, Hui; Cui, Yiping

    2014-11-01

    Telomere length can provide valuable insight into telomeres and telomerase related diseases, including cancer. Here, we present a brand-new optical telomere length measurement protocol using surface enhanced Raman scattering (SERS). In this protocol, two single strand DNA are used as SERS probes. They are labeled with two different Raman molecules and can specifically hybridize with telomeres and centromere, respectively. First, genome DNA is extracted from cells. Then the telomere and centromere SERS probes are added into the genome DNA. After hybridization with genome DNA, excess SERS probes are removed by magnetic capturing nanoparticles. Finally, the genome DNA with SERS probes attached is dropped onto a SERS substrate and subjected to SERS measurement. Longer telomeres result in more attached telomere probes, thus a stronger SERS signal. Consequently, SERS signal can be used as an indicator of telomere length. Centromere is used as the inner control. By calibrating the SERS intensity of telomere probe with that of the centromere probe, SERS based telomere measurement is realized. This protocol does not require polymerase chain reaction (PCR) or electrophoresis procedures, which greatly simplifies the detection process. We anticipate that this easy-operation and cost-effective protocol is a fine alternative for the assessment of telomere length.

  11. Telomere Length Maintenance in Cancer: At the Crossroad between Telomerase and Alternative Lengthening of Telomeres (ALT)

    PubMed Central

    De Vitis, Marco; Berardinelli, Francesco; Sgura, Antonella

    2018-01-01

    Eukaryotic cells undergo continuous telomere shortening as a consequence of multiple rounds of replications. During tumorigenesis, cells have to acquire telomere DNA maintenance mechanisms (TMMs) in order to counteract telomere shortening, to preserve telomeres from DNA damage repair systems and to avoid telomere-mediated senescence and/or apoptosis. For this reason, telomere maintenance is an essential step in cancer progression. Most human tumors maintain their telomeres expressing telomerase, whereas a lower but significant proportion activates the alternative lengthening of telomeres (ALT) pathway. However, evidence about the coexistence of ALT and telomerase has been found both in vivo in the same cancer populations and in vitro in engineered cellular models, making the distinction between telomerase- and ALT-positive tumors elusive. Indeed, after the development of drugs able to target telomerase, the capability for some cancer cells to escape death, switching from telomerase to ALT, was highlighted. Unfortunately, to date, the mechanism underlying the possible switching or the coexistence of telomerase and ALT within the same cell or populations is not completely understood and different factors could be involved. In recent years, different studies have tried to shed light on the complex regulation network that controls the transition between the two TMMs, suggesting a role for embryonic cancer origin, epigenetic modifications, and specific genes activation—both in vivo and in vitro. In this review, we examine recent findings about the cancer-associated differential activation of the two known TMMs and the possible factors implicated in this process. Furthermore, some studies on cancers are also described that did not display any TMM. PMID:29463031

  12. Epigenetic Telomere Protection by Drosophila DNA Damage Response Pathways

    PubMed Central

    Oikemus, Sarah R; Queiroz-Machado, Joana; Lai, KuanJu; McGinnis, Nadine; Sunkel, Claudio; Brodsky, Michael H

    2006-01-01

    Analysis of terminal deletion chromosomes indicates that a sequence-independent mechanism regulates protection of Drosophila telomeres. Mutations in Drosophila DNA damage response genes such as atm/tefu, mre11, or rad50 disrupt telomere protection and localization of the telomere-associated proteins HP1 and HOAP, suggesting that recognition of chromosome ends contributes to telomere protection. However, the partial telomere protection phenotype of these mutations limits the ability to test if they act in the epigenetic telomere protection mechanism. We examined the roles of the Drosophila atm and atr-atrip DNA damage response pathways and the nbs homolog in DNA damage responses and telomere protection. As in other organisms, the atm and atr-atrip pathways act in parallel to promote telomere protection. Cells lacking both pathways exhibit severe defects in telomere protection and fail to localize the protection protein HOAP to telomeres. Drosophila nbs is required for both atm- and atr-dependent DNA damage responses and acts in these pathways during DNA repair. The telomere fusion phenotype of nbs is consistent with defects in each of these activities. Cells defective in both the atm and atr pathways were used to examine if DNA damage response pathways regulate telomere protection without affecting telomere specific sequences. In these cells, chromosome fusion sites retain telomere-specific sequences, demonstrating that loss of these sequences is not responsible for loss of protection. Furthermore, terminally deleted chromosomes also fuse in these cells, directly implicating DNA damage response pathways in the epigenetic protection of telomeres. We propose that recognition of chromosome ends and recruitment of HP1 and HOAP by DNA damage response proteins is essential for the epigenetic protection of Drosophila telomeres. Given the conserved roles of DNA damage response proteins in telomere function, related mechanisms may act at the telomeres of other organisms

  13. Epigenetic telomere protection by Drosophila DNA damage response pathways.

    PubMed

    Oikemus, Sarah R; Queiroz-Machado, Joana; Lai, KuanJu; McGinnis, Nadine; Sunkel, Claudio; Brodsky, Michael H

    2006-05-01

    Analysis of terminal deletion chromosomes indicates that a sequence-independent mechanism regulates protection of Drosophila telomeres. Mutations in Drosophila DNA damage response genes such as atm/tefu, mre11, or rad50 disrupt telomere protection and localization of the telomere-associated proteins HP1 and HOAP, suggesting that recognition of chromosome ends contributes to telomere protection. However, the partial telomere protection phenotype of these mutations limits the ability to test if they act in the epigenetic telomere protection mechanism. We examined the roles of the Drosophila atm and atr-atrip DNA damage response pathways and the nbs homolog in DNA damage responses and telomere protection. As in other organisms, the atm and atr-atrip pathways act in parallel to promote telomere protection. Cells lacking both pathways exhibit severe defects in telomere protection and fail to localize the protection protein HOAP to telomeres. Drosophila nbs is required for both atm- and atr-dependent DNA damage responses and acts in these pathways during DNA repair. The telomere fusion phenotype of nbs is consistent with defects in each of these activities. Cells defective in both the atm and atr pathways were used to examine if DNA damage response pathways regulate telomere protection without affecting telomere specific sequences. In these cells, chromosome fusion sites retain telomere-specific sequences, demonstrating that loss of these sequences is not responsible for loss of protection. Furthermore, terminally deleted chromosomes also fuse in these cells, directly implicating DNA damage response pathways in the epigenetic protection of telomeres. We propose that recognition of chromosome ends and recruitment of HP1 and HOAP by DNA damage response proteins is essential for the epigenetic protection of Drosophila telomeres. Given the conserved roles of DNA damage response proteins in telomere function, related mechanisms may act at the telomeres of other organisms.

  14. Leukocyte Telomere Length and Serum Levels of High-Molecular-Weight Adiponectin and Dehydroepiandrosterone-Sulfate Could Reflect Distinct Aspects of Longevity in Japanese Centenarians.

    PubMed

    Aoki, Yuji; Aoki, Masato; Yamada, Kazuya

    2017-01-01

    Leukocyte telomere length and serum levels of high-molecular-weight adiponectin and dehydroepiandrosterone-sulfate (DHEA-S) were assessed in association with nutrition and performance status (PS) in Japanese centenarians. Twenty-three centenarians (five men, 18 women) were classified according to their PS 1 (nearly fully ambulatory, n = 2), 2 (in bed less than 50% of daytime, n = 10), 3 (in bed greater than 50%, n = 6), and 4 (completely bedridden, n = 5). Leukocyte telomere length was determined by the hybridization protection assay, and the adiponectin and DHEA-S levels were measured by chemiluminescent enzyme immunoassay. Among variables of PS, body mass index (BMI), albumin, adiponectin, DHEA-S, and telomere length, there were significant correlations between PS and albumin ( r = -.694, p < .01), between telomere length and BMI ( r = .522, p < .05), between adiponectin and BMI ( r = -.574, p < .01), and between DHEA-S and albumin ( r = .530, p < .01). When excluding two cancer-bearing centenarians with short telomere, telomere length significantly correlated with PS ( r = -.632, p < .01). It was indicated that the short leukocyte telomere was associated with poor PS and cancer development and that the adiponectin or DHEA-S was associated with adiposity or nutritional status. Despite a small number of subjects, these biomarkers seemed to reflect distinct aspects of longevity in Japanese centenarians.

  15. Reactivation of Chromosomally Integrated Human Herpesvirus-6 by Telomeric Circle Formation

    PubMed Central

    Prusty, Bhupesh K.; Krohne, George; Rudel, Thomas

    2013-01-01

    More than 95% of the human population is infected with human herpesvirus-6 (HHV-6) during early childhood and maintains latent HHV-6 genomes either in an extra-chromosomal form or as a chromosomally integrated HHV-6 (ciHHV-6). In addition, approximately 1% of humans are born with an inheritable form of ciHHV-6 integrated into the telomeres of chromosomes. Immunosuppression and stress conditions can reactivate latent HHV-6 replication, which is associated with clinical complications and even death. We have previously shown that Chlamydia trachomatis infection reactivates ciHHV-6 and induces the formation of extra-chromosomal viral DNA in ciHHV-6 cells. Here, we propose a model and provide experimental evidence for the mechanism of ciHHV-6 reactivation. Infection with Chlamydia induced a transient shortening of telomeric ends, which subsequently led to increased telomeric circle (t-circle) formation and incomplete reconstitution of circular viral genomes containing single viral direct repeat (DR). Correspondingly, short t-circles containing parts of the HHV-6 DR were detected in cells from individuals with genetically inherited ciHHV-6. Furthermore, telomere shortening induced in the absence of Chlamydia infection also caused circularization of ciHHV-6, supporting a t-circle based mechanism for ciHHV-6 reactivation. PMID:24367281

  16. Spatially confined polymer chains: implications of chromatin fibre flexibility and peripheral anchoring on telomere telomere interaction

    NASA Astrophysics Data System (ADS)

    Gehlen, L. R.; Rosa, A.; Klenin, K.; Langowski, J.; Gasser, S. M.; Bystricky, K.

    2006-04-01

    We simulate the extension of spatially confined chromatin fibres modelled as polymer chains and examine the effect of the flexibility of the fibre and its degree of freedom. The developed formalism was used to analyse experimental data of telomere-telomere distances in living yeast cells in the absence of confining factors as identified by the proteins Sir4 and yKu70. Our analysis indicates that intrinsic properties of the chromatin fibre, in particular its elastic properties and flexibility, can influence the juxtaposition of the telomeric ends of chromosomes. However, measurements in intact yeast cells showed that the telomeres of chromosomes 3 and 6 come even closer together than the parameters of constraint imposed on the simulations would predict. This juxtaposition was specific to telomeres on one contiguous chromosome and overrode a tendency for separation that is imposed by anchoring.

  17. A heterochromatin domain forms gradually at a new telomere and is dynamic at stable telomeres.

    PubMed

    Wang, Jinyu; Eisenstatt, Jessica R; Audry, Julien; Cornelius, Kristen; Shaughnessy, Matthew; Berkner, Kathleen L; Runge, Kurt W

    2018-05-21

    Heterochromatin domains play important roles in chromosome biology, organismal development and aging, including centromere function, mammalian female X-chromosome inactivation and senescence-associated heterochromatin foci. In the fission yeast Schizosaccharomyces pombe and metazoans, heterochromatin contains histone H3 that is dimethylated at lysine 9. While factors required for heterochromatin have been identified, the dynamics of heterochromatin formation are poorly understood. Telomeres convert adjacent chromatin into heterochromatin. To form a new heterochromatic region in S. pombe , an inducible DNA double-strand break (DSB) was engineered next to 48 bp of telomere repeats in euchromatin, which caused formation of a new telomere and the establishment and gradual spreading of a new heterochromatin domain. However, spreading was dynamic even after the telomere had reached its stable length, with reporter genes within the heterochromatin domain showing variegated expression. The system also revealed the presence of repeats located near the boundaries of euchromatin and heterochromatin that are oriented to allow the efficient healing of a euchromatic DSB to cap the chromosome end with a new telomere. Telomere formation in S. pombe therefore reveals novel aspects of heterochromatin dynamics and failsafe mechanisms to repair subtelomeric breaks, with implications for similar processes in metazoan genomes. Copyright © 2018 Wang et al.

  18. Robust measurement of telomere length in single cells

    PubMed Central

    Wang, Fang; Pan, Xinghua; Kalmbach, Keri; Seth-Smith, Michelle L.; Ye, Xiaoying; Antumes, Danielle M. F.; Yin, Yu; Liu, Lin; Keefe, David L.; Weissman, Sherman M.

    2013-01-01

    Measurement of telomere length currently requires a large population of cells, which masks telomere length heterogeneity in single cells, or requires FISH in metaphase arrested cells, posing technical challenges. A practical method for measuring telomere length in single cells has been lacking. We established a simple and robust approach for single-cell telomere length measurement (SCT-pqPCR). We first optimized a multiplex preamplification specific for telomeres and reference genes from individual cells, such that the amplicon provides a consistent ratio (T/R) of telomeres (T) to the reference genes (R) by quantitative PCR (qPCR). The average T/R ratio of multiple single cells corresponded closely to that of a given cell population measured by regular qPCR, and correlated with those of telomere restriction fragments (TRF) and quantitative FISH measurements. Furthermore, SCT-pqPCR detected the telomere length for quiescent cells that are inaccessible by quantitative FISH. The reliability of SCT-pqPCR also was confirmed using sister cells from two cell embryos. Telomere length heterogeneity was identified by SCT-pqPCR among cells of various human and mouse cell types. We found that the T/R values of human fibroblasts at later passages and from old donors were lower and more heterogeneous than those of early passages and from young donors, that cancer cell lines show heterogeneous telomere lengths, that human oocytes and polar bodies have nearly identical telomere lengths, and that the telomere lengths progressively increase from the zygote, two-cell to four-cell embryo. This method will facilitate understanding of telomere heterogeneity and its role in tumorigenesis, aging, and associated diseases. PMID:23661059

  19. TopoIIα prevents telomere fragility and formation of ultra thin DNA bridges during mitosis through TRF1-dependent binding to telomeres.

    PubMed

    d'Alcontres, Martina Stagno; Palacios, Jose Alejandro; Mejias, Diego; Blasco, Maria A

    2014-01-01

    Telomeres are repetitive nucleoprotein structures at the ends of chromosomes. Like most genomic regions consisting of repetitive DNA, telomeres are fragile sites prone to replication fork stalling and generation of chromosomal instability. In particular, abrogation of the TRF1 telomere binding protein leads to stalled replication forks and aberrant telomere structures known as "multitelomeric signals". Here, we report that TRF1 deficiency also leads to the formation of "ultra-fine bridges" (UFB) during mitosis, and to an increased time to complete mitosis mediated by the spindle assembly checkpoint proteins (SAC). We find that topoisomerase IIα (TopoIIα), an enzyme essential for resolution of DNA replication intermediates, binds telomeres in a TRF1-mediated manner. Indeed, similar to TRF1 abrogation, TopoIIα downregulation leads to telomere fragility and UFB, suggesting that these phenotypes are due to decreased TopoIIα at telomeres. We find that SAC proteins bind telomeres in vivo, and that this is disrupted upon TRF1 deletion. These findings suggest that TRF1 links TopoIIα and SAC proteins in a pathway that ensures correct telomere replication and mitotic segregation, unveiling how TRF1 protects from telomere fragility and mitotic defects.

  20. Telomere length in bipolar disorder and lithium response.

    PubMed

    Squassina, Alessio; Pisanu, Claudia; Corbett, Nathan; Alda, Martin

    2017-06-01

    Telomeres consist of exanucleotide tandem repeats and proteins complexes at the end of chromosome ends. Telomeres shorten at each cell division, and as such telomere length is a marker of cellular age. Accelerated telomere shortening and cell senescence have been associated with a number of chronic medical conditions, including psychiatric disorders, where increased prevalence of age-related disorders and shorter telomere length have been reported. Shorter telomeres in psychiatric patients are thought to be the consequence of allostatic load, consisting in the overactivation of allostatic systems due to chronic exposure to severe medical conditions and failure to adapt to chronic stressful stimuli. Most of the studies on telomere length in psychiatry have focused on major depressive disorder, but recent findings have shown shorter leukocyte telomere length in bipolar disorder patients and suggested that lithium may counteract telomeres shortening. These findings provided new insights into the pathophysiology of bipolar disorder and the mechanism of action of lithium. In this review we will present findings from the literature on telomere length in bipolar disorder, with a specific focus on lithium. We will also discuss advances and limitations of published work as well as methodological issues and potential confounding factors that should be taken into account when designing research protocols to study telomere length. Copyright © 2015 Elsevier B.V. and ECNP. All rights reserved.

  1. Telomere Length in Aged Mayak PA Nuclear Workers Chronically Exposed to Internal Alpha and External Gamma Radiation.

    PubMed

    Scherthan, Harry; Sotnik, Natalia; Peper, Michel; Schrock, Gerrit; Azizova, Tamara; Abend, Michael

    2016-06-01

    Telomeres consist of GC-rich DNA repeats and the "shelterin" protein complex that together protect chromosome ends from fusion and degradation. Telomeres shorten with age due to incomplete end replication and upon exposure to environmental and intrinsic stressors. Exposure to ionizing radiation is known to modulate telomere length. However, the response of telomere length in humans chronically exposed to radiation is poorly understood. Here, we studied relative telomere length (RTL) by IQ-FISH to leukocyte nuclei in a group of 100 workers from the plutonium production facility at the Mayak Production Association (PA) who were chronically exposed to alpha-emitting ((239)Pu) radiation and/or gamma (photon) radiation, and 51 local residents serving as controls, with a similar mean age of about 80 years. We applied generalized linear statistical models adjusted for age at biosampling and the second exposure type on a linear scale and observed an age-dependent telomere length reduction. In those individuals with the lowest exposure, a significant reduction of about 20% RTL was observed, both for external gamma radiation (≤1 Gy) and internal alpha radiation (≤0.05-0.1 Gy to the red bone marrow). In highly exposed individuals (>0.1 Gy alpha, 1-1.5 Gy gamma), the RTL was similar to control. Stratification by gender revealed a significant (∼30%) telomere reduction in low-dose-exposed males, which was absent in females. While the gender differences in RTL may reflect different working conditions, lifestyle and/or telomere biology, absence of a dose response in the highly exposed individuals may reflect selection against cells with short telomeres or induction of telomere-protective effects. Our observations suggest that chronic systemic exposure to radiation leads to variable dose-dependent effects on telomere length.

  2. Depressive and Anxiety Disorders Showing Robust, but Non-Dynamic, 6-Year Longitudinal Association With Short Leukocyte Telomere Length.

    PubMed

    Verhoeven, Josine E; van Oppen, Patricia; Révész, Dóra; Wolkowitz, Owen M; Penninx, Brenda W J H

    2016-06-01

    Several cross-sectional studies have related depressive and anxiety disorders to shorter leukocyte telomere length (LTL) as an indicator of cellular aging. However, these studies have left many unresolved questions about underlying causality and ordering of associations. The objective of the present large, longitudinal study was to examine the relationship between depressive and anxiety disorders and LTL over a 6-year time period. Data are from the Netherlands Study of Depression and Anxiety, including 2,292 patients with remitted and current diagnoses of depressive or anxiety disorders and 644 healthy control subjects. LTL was assessed using quantitative PCR and measured at baseline and after 6 years; depressive and anxiety disorder diagnoses and characteristics (course, duration, and severity) were determined at baseline and after 2, 4, and 6 years. Results showed that persons with remitted (B=-52.6) and current (B=-60.8) depressive or anxiety disorder had consistently shorter LTL compared with healthy control subjects across baseline and at the 6-year follow-up, remaining significant when controlling for lifestyle and somatic health variables. Changes in the course of depressive or anxiety disorder characteristics over 6 years, however, were not associated with different LTL attrition rates. This study confirmed robust associations of depressive and anxiety disorders with shorter telomeres, but interestingly, it did not demonstrate that depressive and anxiety disorders and LTL change together over time, suggesting the absence of a direct within-person relationship. Short LTL is suggested to be either a long-term consequence or an underlying vulnerability factor for depressive or anxiety disorders.

  3. Silica inhalation altered telomere length and gene expression of telomere regulatory proteins in lung tissue of rats.

    PubMed

    Shoeb, Mohammad; Joseph, Pius; Kodali, Vamsi; Mustafa, Gul; Farris, Breanne Y; Umbright, Christina; Roberts, Jenny R; Erdely, Aaron; Antonini, James M

    2017-12-11

    Exposure to silica can cause lung fibrosis and cancer. Identification of molecular targets is important for the intervention and/or prevention of silica-induced lung diseases. Telomeres consist of tandem repeats of DNA sequences at the end of chromosomes, preventing chromosomal fusion and degradation. Regulator of telomere length-1 (RTEL1) and telomerase reverse transcriptase (TERT), genes involved in telomere regulation and function, play important roles in maintaining telomere integrity and length. The goal of this study was to assess the effect of silica inhalation on telomere length and the regulation of RTEL1 and TERT. Lung tissues and blood samples were collected from rats at 4, 32, and 44 wk after exposure to 15 mg/m 3 of silica × 6 h/d × 5 d. Controls were exposed to air. At all-time points, RTEL1 expression was significantly decreased in lung tissue of the silica-exposed animals compared to controls. Also, significant increases in telomere length and TERT were observed in the silica group at 4 and 32 wk. Telomere length, RTEL1 and TERT expression may serve as potential biomarkers related to silica exposure and may offer insight into the molecular mechanism of silica-induced lung disease and tumorigeneses.

  4. DNA Replication Origins and Fork Progression at Mammalian Telomeres

    PubMed Central

    Higa, Mitsunori; Fujita, Masatoshi; Yoshida, Kazumasa

    2017-01-01

    Telomeres are essential chromosomal regions that prevent critical shortening of linear chromosomes and genomic instability in eukaryotic cells. The bulk of telomeric DNA is replicated by semi-conservative DNA replication in the same way as the rest of the genome. However, recent findings revealed that replication of telomeric repeats is a potential cause of chromosomal instability, because DNA replication through telomeres is challenged by the repetitive telomeric sequences and specific structures that hamper the replication fork. In this review, we summarize current understanding of the mechanisms by which telomeres are faithfully and safely replicated in mammalian cells. Various telomere-associated proteins ensure efficient telomere replication at different steps, such as licensing of replication origins, passage of replication forks, proper fork restart after replication stress, and dissolution of post-replicative structures. In particular, shelterin proteins have central roles in the control of telomere replication. Through physical interactions, accessory proteins are recruited to maintain telomere integrity during DNA replication. Dormant replication origins and/or homology-directed repair may rescue inappropriate fork stalling or collapse that can cause defects in telomere structure and functions. PMID:28350373

  5. Distinct Responses of Stem Cells to Telomere Uncapping-A Potential Strategy to Improve the Safety of Cell Therapy.

    PubMed

    Liu, Chang Ching; Ma, Dong Liang; Yan, Ting-Dong; Fan, XiuBo; Poon, Zhiyong; Poon, Lai-Fong; Goh, Su-Ann; Rozen, Steve G; Hwang, William Ying Khee; Tergaonkar, Vinay; Tan, Patrick; Ghosh, Sujoy; Virshup, David M; Goh, Eyleen L K; Li, Shang

    2016-10-01

    In most human somatic cells, the lack of telomerase activity results in progressive telomere shortening during each cell division. Eventually, DNA damage responses triggered by critically short telomeres induce an irreversible cell cycle arrest termed replicative senescence. However, the cellular responses of human pluripotent stem cells to telomere uncapping remain unknown. We generated telomerase knockout human embryonic stem (ES) cells through gene targeting. Telomerase inactivation in ES cells results in progressive telomere shortening. Telomere DNA damage in ES cells and neural progenitor cells induces rapid apoptosis when telomeres are uncapped, in contrast to fibroblast cells that enter a state of replicative senescence. Significantly, telomerase inactivation limits the proliferation capacity of human ES cells without affecting their pluripotency. By targeting telomerase activity, we can functionally separate the two unique properties of human pluripotent stem cells, namely unlimited self-renewal and pluripotency. We show that the potential of ES cells to form teratomas in vivo is dictated by their telomere length. By controlling telomere length of ES cells through telomerase inactivation, we can inhibit teratoma formation and potentially improve the safety of cell therapies involving terminally differentiated cells as well as specific progenitor cells that do not require sustained cellular proliferation in vivo, and thus sustained telomerase activity. Stem Cells 2016;34:2471-2484. © 2016 AlphaMed Press.

  6. Telomere Length in Epidemiology: A Biomarker of Aging, Age-Related Disease, Both, or Neither?

    PubMed Central

    Sanders, Jason L.; Newman, Anne B.

    2013-01-01

    Telomeres are nucleoprotein caps flanking DNA. They are shortened by cell division and oxidative stress and are lengthened by the enzyme telomerase and DNA exchange during mitosis. Short telomeres induce cellular senescence. As an indicator of oxidative stress and senescence (2 processes thought to be fundamental to aging), telomere length is hypothesized to be a biomarker of aging. This hypothesis has been tested for more than a decade with epidemiologic study methods. In cross-sectional studies, researchers have investigated whether leukocyte telomere length (LTL) is associated with demographic, behavioral, and health variables. In prospective studies, baseline LTL has been used to predict mortality and occasionally other adverse health outcomes. Conflicting data have generated heated debate about the value of LTL as a biomarker of overall aging. In this review, we address the epidemiologic data on LTL and demonstrate that shorter LTL is associated with older age, male gender, Caucasian race, and possibly atherosclerosis; associations with other markers of health are equivocal. We discuss the reasons for discrepancy across studies, including a detailed review of methods for measuring telomere length as they apply to epidemiology. Finally, we conclude with questions about LTL as a biomarker of aging and how epidemiology can be used to answer these questions. PMID:23302541

  7. Break-induced replication and recombinational telomere elongation in yeast.

    PubMed

    McEachern, Michael J; Haber, James E

    2006-01-01

    When a telomere becomes unprotected or if only one end of a chromosomal double-strand break succeeds in recombining with a template sequence, DNA can be repaired by a recombination-dependent DNA replication process termed break-induced replication (BIR). In budding yeasts, there are two BIR pathways, one dependent on the Rad51 recombinase protein and one Rad51 independent; these two repair processes lead to different types of survivors in cells lacking the telomerase enzyme that is required for normal telomere maintenance. Recombination at telomeres is triggered by either excessive telomere shortening or disruptions in the function of telomere-binding proteins. Telomere elongation by BIR appears to often occur through a "roll and spread" mechanism. In this process, a telomeric circle produced by recombination at a dysfunctional telomere acts as a template for a rolling circle BIR event to form an elongated telomere. Additional BIR events can then copy the elongated sequence to all other telomeres.

  8. Assessment of Telomere Length, Phenotype, and DNA Content

    PubMed Central

    Kelesidis, Theodoros; Schmid, Ingrid

    2017-01-01

    Telomere sequences at the end of chromosomes control somatic cell division; therefore, telomere length in a given cell population provides information about its replication potential. This unit describes a method for flow cytometric measurement of telomere length in subpopulations using fluorescence in situ hybridization of fluorescently-labeled probes (Flow-FISH) without prior cell separation. After cells are stained for surface immunofluorescence, antigen-antibody complexes are covalently cross-linked onto cell membranes before FISH with a telomere-specific probe. Cells with long telomeres are included as internal standards. Addition of a DNA dye permits exclusion of proliferating cells during data analysis. DNA ploidy measurements of cells of interest and internal standard are performed on separate aliquots in parallel to Flow-FISH. Telomere fluorescence of G0/1 cells of subpopulations and internal standards obtained from Flow-FISH are normalized for DNA ploidy, and telomere length in subsets of interest is expressed as a fraction of the internal standard telomere length. PMID:28055113

  9. Moderate stem-cell telomere shortening rate postpones cancer onset in a stochastic model

    NASA Astrophysics Data System (ADS)

    Holbek, Simon; Bendtsen, Kristian Moss; Juul, Jeppe

    2013-10-01

    Mammalian cells are restricted from proliferating indefinitely. Telomeres at the end of each chromosome are shortened at cell division and when they reach a critical length, the cell will enter permanent cell cycle arrest—a state known as senescence. This mechanism is thought to be tumor suppressing, as it helps prevent precancerous cells from dividing uncontrollably. Stem cells express the enzyme telomerase, which elongates the telomeres, thereby postponing senescence. However, unlike germ cells and most types of cancer cells, stem cells only express telomerase at levels insufficient to fully maintain the length of their telomeres, leading to a slow decline in proliferation potential. It is not yet fully understood how this decline influences the risk of cancer and the longevity of the organism. We here develop a stochastic model to explore the role of telomere dynamics in relation to both senescence and cancer. The model describes the accumulation of cancerous mutations in a multicellular organism and creates a coherent theoretical framework for interpreting the results of several recent experiments on telomerase regulation. We demonstrate that the longest average cancer-free lifespan before cancer onset is obtained when stem cells start with relatively long telomeres that are shortened at a steady rate at cell division. Furthermore, the risk of cancer early in life can be reduced by having a short initial telomere length. Finally, our model suggests that evolution will favor a shorter than optimal average cancer-free lifespan in order to postpone cancer onset until late in life.

  10. DNA-PKcs is critical for telomere capping

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gilley, David; Tanaka, Hiromi; Hande, M. Prakash

    The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is critical for DNA repair via the non-homologous end joining (NHEJ) pathway. Previously, it was reported that bone marrow cells and spontaneously transformed fibroblasts from SCID (severe combined immunodeficiency) mice have defects in telomere maintenance. The genetically defective SCID mouse arose spontaneously from its parental strain CB17. One known genomic alteration in SCID mice is a truncation of the extreme carboxyl-terminus of DNA-PKcs, but other as yet unidentified alterations may also exist. We have used a defined system, the DNA-PKcs knockout mouse, to investigate specifically the role DNA-PKcs specifically plays in telomere maintenance.more » We report that primary mouse embryonic fibroblasts (MEFs) and primary cultured kidney cells from 6-8 month old DNA-PKcs deficient mice accumulate a large number of telomere fusions, yet still retain wildtype telomere length. Thus, the phenotype of this defect separates the two-telomere related phenotypes, capping and length maintenance. DNA-PKcs deficient MEFs also exhibit elevated levels of chromosome fragments and breaks, which correlate with increased telomere fusions. Based on the high levels of telomere fusions observed in DNA-PKcs deficient cells, we conclude that DNA-PKcs plays an important capping role at the mammalian telomere.« less

  11. Amplification of telomeric arrays via rolling-circle mechanism.

    PubMed

    Nosek, Jozef; Rycovska, Adriana; Makhov, Alexander M; Griffith, Jack D; Tomaska, Lubomir

    2005-03-18

    Alternative (telomerase-independent) lengthening of telomeres mediated through homologous recombination is often accompanied by a generation of extrachromosomal telomeric circles (t-circles), whose role in direct promotion of recombinational telomere elongation has been recently demonstrated. Here we present evidence that t-circles in a natural telomerase-deficient system of mitochondria of the yeast Candida parapsilosis replicate independently of the linear chromosome via a rolling-circle mechanism. This is supported by an observation of (i) single-stranded DNA consisting of concatameric arrays of telomeric sequence, (ii) lasso-shaped molecules representing rolling-circle intermediates, and (iii) preferential incorporation of deoxyribonucleotides into telomeric fragments and t-circles. Analysis of naturally occurring variant t-circles revealed conserved motifs with potential function in driving the rolling-circle replication. These data indicate that extrachromosomal t-circles observed in a wide variety of organisms, including yeasts, plants, Xenopus laevis, and certain human cell lines, may represent independent replicons generating telomeric sequences and, thus, actively participating in telomere dynamics. Moreover, because of the promiscuous occurrence of t-circles across phyla, the results from yeast mitochondria have implications related to the primordial system of telomere maintenance, providing a paradigm for evolution of telomeres in nuclei of early eukaryotes.

  12. Long-Term Effects of Radiation Exposure and Metabolic Status on Telomere Length of Peripheral Blood T Cells in Atomic Bomb Survivors.

    PubMed

    Yoshida, Kengo; Misumi, Munechika; Kubo, Yoshiko; Yamaoka, Mika; Kyoizumi, Seishi; Ohishi, Waka; Hayashi, Tomonori; Kusunoki, Yoichiro

    2016-10-01

    In a series of studies of atomic bomb survivors, radiation-dose-dependent alterations in peripheral T-cell populations have been reported. For example, reduced size in naïve T-cell pools and impaired proliferation ability of T cells were observed. Because these alterations are also generally observed with human aging, we hypothesized that radiation exposure may accelerate the aging process of the T-cell immune system. To further test this hypothesis, we conducted cross-sectional analyses of telomere length, a hallmark of cellular aging, of naïve and memory CD4 T cells and total CD8 T cells in the peripheral blood of 620 atomic bomb survivors as it relates to age and radiation dose, using fluorescence in situ hybridization with flow cytometry. Since telomere shortening has been recently demonstrated in obesity-related metabolic abnormalities and diseases, the modifying effects of metabolic status were also examined. Our results indicated nonlinear relationships between T-cell telomere length and prior radiation exposure, i.e., longer telomeres with lower dose exposure and a decreasing trend of telomere length with individuals exposed to doses higher than 0.5 Gy. There were associations between shorter T-cell telomeres and higher hemoglobin Alc levels or fatty liver development. In naïve and memory CD4 T cells, radiation dose and high-density lipoprotein (HDL) cholesterol were found to positively interact with telomere length, suggesting that the decreasing trend of telomere length from a higher radiation dose was less conspicuous in individuals with a higher HDL cholesterol. It is therefore likely that radiation exposure perturbs T-cell homeostasis involving telomere length maintenance by multiple biological mechanisms, depending on dose, and that long-term-radiation-induced effects on the maintenance of T-cell telomeres may be modified by the subsequent metabolic conditions of individuals.

  13. Recent progress in human telomere RNA structure and function.

    PubMed

    Xu, Yan

    2018-06-14

    Human telomeric DNA is transcribed into telomeric RNA in cells. Telomeric RNA performs the fundamental biological functions such as regulation and protection of chromosome ends. This digest highlights the human telomere RNA G-quadruplex structures, telomere RNA functions, G-quadruplex-binding small molecules, and future prospects. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Lifespan adversity and later adulthood telomere length in the nationally representative US Health and Retirement Study

    PubMed Central

    Gemmill, Alison; Weir, David; Adler, Nancy E.; Prather, Aric A.

    2016-01-01

    Stress over the lifespan is thought to promote accelerated aging and early disease. Telomere length is a marker of cell aging that appears to be one mediator of this relationship. Telomere length is associated with early adversity and with chronic stressors in adulthood in many studies. Although cumulative lifespan adversity should have bigger impacts than single events, it is also possible that adversity in childhood has larger effects on later life health than adult stressors, as suggested by models of biological embedding in early life. No studies have examined the individual vs. cumulative effects of childhood and adulthood adversities on adult telomere length. Here, we examined the relationship between cumulative childhood and adulthood adversity, adding up a range of severe financial, traumatic, and social exposures, as well as comparing them to each other, in relation to salivary telomere length. We examined 4,598 men and women from the US Health and Retirement Study. Single adversities tended to have nonsignificant relations with telomere length. In adjusted models, lifetime cumulative adversity predicted 6% greater odds of shorter telomere length. This result was mainly due to childhood adversity. In adjusted models for cumulative childhood adversity, the occurrence of each additional childhood event predicted 11% increased odds of having short telomeres. This result appeared mainly because of social/traumatic exposures rather than financial exposures. This study suggests that the shadow of childhood adversity may reach far into later adulthood in part through cellular aging. PMID:27698131

  15. Lifespan adversity and later adulthood telomere length in the nationally representative US Health and Retirement Study.

    PubMed

    Puterman, Eli; Gemmill, Alison; Karasek, Deborah; Weir, David; Adler, Nancy E; Prather, Aric A; Epel, Elissa S

    2016-10-18

    Stress over the lifespan is thought to promote accelerated aging and early disease. Telomere length is a marker of cell aging that appears to be one mediator of this relationship. Telomere length is associated with early adversity and with chronic stressors in adulthood in many studies. Although cumulative lifespan adversity should have bigger impacts than single events, it is also possible that adversity in childhood has larger effects on later life health than adult stressors, as suggested by models of biological embedding in early life. No studies have examined the individual vs. cumulative effects of childhood and adulthood adversities on adult telomere length. Here, we examined the relationship between cumulative childhood and adulthood adversity, adding up a range of severe financial, traumatic, and social exposures, as well as comparing them to each other, in relation to salivary telomere length. We examined 4,598 men and women from the US Health and Retirement Study. Single adversities tended to have nonsignificant relations with telomere length. In adjusted models, lifetime cumulative adversity predicted 6% greater odds of shorter telomere length. This result was mainly due to childhood adversity. In adjusted models for cumulative childhood adversity, the occurrence of each additional childhood event predicted 11% increased odds of having short telomeres. This result appeared mainly because of social/traumatic exposures rather than financial exposures. This study suggests that the shadow of childhood adversity may reach far into later adulthood in part through cellular aging.

  16. Mutations in XLF/NHEJ1/Cernunnos gene results in downregulation of telomerase genes expression and telomere shortening.

    PubMed

    Carrillo, Jaime; Calvete, Oriol; Pintado-Berninches, Laura; Manguan-García, Cristina; Sevilla Navarro, Julian; Arias-Salgado, Elena G; Sastre, Leandro; Guenechea, Guillermo; López Granados, Eduardo; de Villartay, Jean-Pierre; Revy, Patrick; Benitez, Javier; Perona, Rosario

    2017-05-15

    NHEJ1-patients develop severe progressive lymphocytopenia and premature aging of hematopoietic stem cells (HSCs) at a young age. Here we show a patient with a homozygous-NHEJ1 mutation identified by whole exome-sequencing that developed severe pancytopenia and bone marrow aplasia correlating with the presence of short telomeres. The mutation resulted in a truncated protein. In an attempt to identify the mechanism behind the short telomere phenotype found in the NHEJ1-patient we downregulated NHEJ1 expression in 293T and CD34+cells. This downregulation resulted in reduced telomerase activity and decreased expression of several telomerase/shelterin genes. Interestingly, cell lines derived from two other NHEJ1-deficient patients with different mutations also showed increased p21 expression, inhibition in expression of several telomerase complex genes and shortened telomeres. Decrease in expression of telomerase/shelterin genes did not occur when we inhibited expression of other NHEJ genes mutated in SCID patients: DNA-PK, Artemis or LigaseIV. Because premature aging of HSCs is observed only in NHEJ1 patients, we propose that is the result of senescence induced by decreased expression of telomerase/shelterin genes that lead to an inhibition of telomerase activity. Previous reports failed to find this connection because of the use of patient´s cells immortalized by TERT expression or recombined telomeres by ALT pathway. In summary, defective regulation of telomere biology together with defective V(D)J recombination can negatively impact on the evolution of the disease in these patients. Identification of telomere shortening is important since it may open new therapeutic interventions for these patients by treatments aimed to recover the expression of telomerase genes. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. Telomere fusion in Drosophila: The role of subtelomeric chromatin

    PubMed Central

    Marzullo, Marta; Gatti, Maurizio

    2015-01-01

    Drosophila telomeres are maintained by transposition to chromosome ends of the HeT-A, TART and TAHRE retrotransposons, collectively designated as HTT. Although all Drosophila telomeres terminate with HTT arrays and are capped by the terminin complex, they differ in the type of subtelomeric chromatin. The HTT sequences of YS, YL, XR, and 4L are juxtaposed to constitutive heterochromatin, while the HTTs of the other telomeres are linked to either the TAS repeat-associated chromatin (XL, 2L, 2R, 3L, 3R) or to the specialized 4R chromatin. We found that mutations in pendolino (peo) cause (telomeric fusions) that preferentially involve the heterochromatin-associated telomeres (Ha-telomeres), a telomeric fusion pattern never observed in the other 10 telomere-capping mutants characterized so far. Peo, is homologous to the E2 variant ubiquitin-conjugating enzymes and is required for DNA replication. Our analyses lead us to hypothesize that DNA replication in Peo-depleted cells results in specific fusigenic lesions concentrated in Ha-telomeres. These data provide the first demonstration that subtelomeres can affect telomere fusion. PMID:26786804

  18. Sexual differences in telomere selection in the wild.

    PubMed

    Olsson, Mats; Pauliny, Angela; Wapstra, Erik; Uller, Tobias; Schwartz, Tonia; Miller, Emily; Blomqvist, Donald

    2011-05-01

    Telomere length is restored primarily through the action of the reverse transcriptase telomerase, which may contribute to a prolonged lifespan in some but not all species and may result in longer telomeres in one sex than the other. To what extent this is an effect of proximate mechanisms (e.g. higher stress in males, higher oestradiol/oestrogen levels in females), or is an evolved adaptation (stronger selection for telomere length in one sex), usually remains unknown. Sand lizard (Lacerta agilis) females have longer telomeres than males and better maintain telomere length through life than males do. We also show that telomere length more strongly contributes to life span and lifetime reproductive success in females than males and that telomere length is under sexually diversifying selection in the wild. Finally, we performed a selection analysis with number of recruited offspring into the adult population as a response variable with telomere length, life span and body size as predictor variables. This showed significant differences in selection pressures between the sexes with strong ongoing selection in females, with these three predictors explaining 63% of the variation in recruitment. Thus, the sexually dimorphic telomere dynamics with longer telomeres in females is a result of past and ongoing selection in sand lizards. Finally, we compared the results from our selection analyses based on Telometric-derived data to the results based on data generated by the software ImageJ. ImageJ resulted in shorter average telomere length, but this difference had virtually no qualitative effect on the patterns of ongoing selection. © 2011 Blackwell Publishing Ltd.

  19. Exome Sequencing Links Mutations in PARN and RTEL1 with Familial Pulmonary Fibrosis and Telomere Shortening

    PubMed Central

    Stuart, Bridget D.; Choi, Jungmin; Zaidi, Samir; Xing, Chao; Holohan, Brody; Chen, Rui; Choi, Mihwa; Dharwadkar, Pooja; Torres, Fernando; Girod, Carlos E.; Weissler, Jonathan; Fitzgerald, John; Kershaw, Corey; Klesney-Tait, Julia; Mageto, Yolanda; Shay, Jerry W.; Ji, Weizhen; Bilguvar, Kaya; Mane, Shrikant; Lifton, Richard P.; Garcia, Christine Kim

    2015-01-01

    Idiopathic pulmonary fibrosis (IPF) is an age-related disease featuring progressive lung scarring. To elucidate the molecular basis of IPF, we performed exome sequencing of familial pulmonary fibrosis kindreds. Gene burden analysis comparing 78 European cases and 2,816 controls implicated PARN, an exoribonuclease with no prior connection to telomere biology or disease, with five novel heterozygous damaging mutations in unrelated cases and none in controls (P-value = 1.3 × 10−8); mutations were shared by all affected relatives (odds in favor of linkage = 4,096:1). RTEL1, an established locus for dyskeratosis congenita, harbored significantly more novel damaging and missense variants at conserved residues in cases than controls (P = 1.6 × 10−6). PARN and RTEL1 mutation carriers had shortened leukocyte telomere lengths and epigenetic inheritance of short telomeres was seen in family members. Together these genes explain ~7% of familial pulmonary fibrosis and strengthen the link between lung fibrosis and telomere dysfunction. PMID:25848748

  20. Exome sequencing links mutations in PARN and RTEL1 with familial pulmonary fibrosis and telomere shortening.

    PubMed

    Stuart, Bridget D; Choi, Jungmin; Zaidi, Samir; Xing, Chao; Holohan, Brody; Chen, Rui; Choi, Mihwa; Dharwadkar, Pooja; Torres, Fernando; Girod, Carlos E; Weissler, Jonathan; Fitzgerald, John; Kershaw, Corey; Klesney-Tait, Julia; Mageto, Yolanda; Shay, Jerry W; Ji, Weizhen; Bilguvar, Kaya; Mane, Shrikant; Lifton, Richard P; Garcia, Christine Kim

    2015-05-01

    Idiopathic pulmonary fibrosis (IPF) is an age-related disease featuring progressive lung scarring. To elucidate the molecular basis of IPF, we performed exome sequencing of familial kindreds with pulmonary fibrosis. Gene burden analysis comparing 78 European cases and 2,816 controls implicated PARN, an exoribonuclease with no previous connection to telomere biology or disease, with five new heterozygous damaging mutations in unrelated cases and none in controls (P = 1.3 × 10(-8)); mutations were shared by all affected relatives (odds in favor of linkage = 4,096:1). RTEL1, an established locus for dyskeratosis congenita, harbored significantly more new damaging and missense variants at conserved residues in cases than in controls (P = 1.6 × 10(-6)). PARN and RTEL1 mutation carriers had shortened leukocyte telomere lengths, and we observed epigenetic inheritance of short telomeres in family members. Together, these genes explain ~7% of familial pulmonary fibrosis and strengthen the link between lung fibrosis and telomere dysfunction.

  1. The coherence of synthetic telomeres.

    PubMed Central

    Acevedo, O L; Dickinson, L A; Macke, T J; Thomas, C A

    1991-01-01

    The chromosomal telomeres of Oxytricha were synthesized and their ability to cohere examined on non-denaturing acrylamide gels containing the stabilizing cation K+. At least 5 different mobility species were observed, in addition to that of the monomeric telomere. By cohering synthetic telomeres containing different lengths of subtelomeric DNA, we showed that each of the different mobility species was a dimer of two telomeres. Since the different mobility species did not differ in numbers or sequences of nucleotides, they must correspond to different molecular shapes probably caused by different degrees of bending of the dimer. Paradoxically, telomeres with longer subtelomeric stems cohered more efficiently. In the presence of K+, solutions had to be heated to over 90 degrees before the telomeres separated. Various synthetic constructs, restriction endonuclease and dimethyl sulfate protection experiments showed that the only nucleotides involved in the cohered structures were the 16 base 'tails' of sequence 3'G4T4G4T4. Extension of this motif was actually inimical to coherence. Oligomers containing 2 G4T4 motifs protected their GN7 positions by forming dimers, those with 5 G4T4 could do so by internal folding, but the 3' terminal group of G4 was left unprotected. This suggests that only four groups of G4 are necessary for the cohered structure. Single-chain specific nuclease, S1, as well as osmium tetroxide, which oxidizes the thymine residues of single chains, reacted less efficiently with the cohered structures. Synthetic telomeres containing inosine replacing guanosine were not observed to cohere, indicating that the C2-NH2 is strongly stabilizing. The cohered structures appear to be unusually compact and sturdy units in which four G4 blocks form quadruplexes stabilized by K+. A new model for the cohered structure is presented. Images PMID:1648206

  2. Long leukocyte telomere length in prostate cancer patients at diagnosis is associated with poor metastasis-free and cancer-specific survival.

    PubMed

    Svenson, Ulrika; Roos, Göran; Wikström, Pernilla

    2017-02-01

    Previous studies have suggested that leukocyte telomere length is associated with risk of developing prostate cancer. Investigations of leukocyte telomere length as a prognostic factor in prostate cancer are, however, lacking. In this study, leukocyte telomere length was investigated both as a risk marker, comparing control subjects and patient risk groups (based on serum levels of prostate-specific antigen, tumor differentiation, and tumor stage), and as a prognostic marker for metastasis-free and cancer-specific survival. Relative telomere length was measured by a well-established quantitative polymerase chain reaction method in 415 consecutively sampled individuals. Statistical evaluation included 162 control subjects without cancer development during follow-up and 110 untreated patients with newly diagnosed localized prostate cancer at the time of blood draw. Leukocyte telomere length did not differ significantly between control subjects and patients, or between patient risk groups. Interestingly, however, and in line with our previous results in breast and kidney cancer patients, relative telomere length at diagnosis was an independent prognostic factor. Patients with long leukocyte telomeres (⩾median) had a significantly worse prostate cancer-specific and metastasis-free survival compared to patients with short telomere length. In contrast, for patients who died of other causes than prostate cancer, long relative telomere length was not coupled to shorter survival time. To our knowledge, these results are novel and give further strength to our hypothesis that leukocyte telomere length might be used as a prognostic marker in malignancy.

  3. Assessment of Telomere Length, Phenotype, and DNA Content.

    PubMed

    Kelesidis, Theodoros; Schmid, Ingrid

    2017-01-05

    Telomere sequences at the end of chromosomes control somatic cell division; therefore, telomere length in a given cell population provides information about its replication potential. This unit describes a method for flow cytometric measurement of telomere length in subpopulations using fluorescence in situ hybridization of fluorescently-labeled probes (Flow-FISH) without prior cell separation. After cells are stained for surface immunofluorescence, antigen-antibody complexes are covalently cross-linked onto cell membranes before FISH with a telomere-specific probe. Cells with long telomeres are included as internal standards. Addition of a DNA dye permits exclusion of proliferating cells during data analysis. DNA ploidy measurements of cells of interest and internal standard are performed on separate aliquots in parallel to Flow-FISH. Telomere fluorescence of G 0/1 cells of subpopulations and internal standards obtained from Flow-FISH are normalized for DNA ploidy, and telomere length in subsets of interest is expressed as a fraction of the internal standard telomere length. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

  4. Telomere correlations during early life in a long-lived seabird.

    PubMed

    Schmidt, Jacob E; Sirman, Aubrey E; Kittilson, Jeffrey D; Clark, Mark E; Reed, Wendy L; Heidinger, Britt J

    2016-12-01

    Telomere dynamics in blood cells have been linked to aging in a variety of organisms. However, whether blood telomeres are correlated with telomeres in other parts of the body is not well known, especially during early life when telomere loss is expected to be most rapid. We investigated this question in Franklin's gulls (Leucophaeus pipixcan) by measuring telomere lengths in blood and several other tissues including: heart, liver, and skeletal muscle at the end of embryonic (n=31) and post-natal development (n=20). In late-stage embryos, blood telomeres were significantly positively correlated with heart and skeletal muscle, but not liver telomeres. However, at the end of post-natal development, there were no significant correlations among blood telomeres and telomeres in any other tissues. In late-stage embryos, heart telomeres were significantly longer than blood, liver, and skeletal muscle telomeres, but at the end of post-natal development telomere lengths did not significantly differ among tissues. These results suggest that blood telomere length is not necessarily indicative of other tissues at all stages of development and highlights the importance of understanding any functional consequences of tissue specific telomere dynamics in early life. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Telomere biology of trypanosomatids: beginning to answer some questions.

    PubMed

    Lira, Cristina B B; Giardini, Miriam A; Neto, Jair L Siqueira; Conte, Fábio F; Cano, Maria Isabel N

    2007-08-01

    Studies of telomere structure and maintenance in trypanosomatids have provided insights into the evolutionary origin and conservation of some telomeric components shared by trypanosomes and vertebrates. For example, trypanosomatid telomeres are maintained by telomerase and consist of the canonical TTAGGG repeats, which in Trypanosoma brucei can form telomeric loops (t-loops). However, the telomeric chromatin of trypanosomatids is composed of organism-specific proteins and other proteins that share little sequence similarity with their vertebrate counterparts. Because telomere maintenance mechanisms are essential for genome stability, we propose that the particular features shown by the trypanosome telomeric chromatin hold the key for the design of antiparasitic drugs.

  6. TP53-dependent chromosome instability is associated with transient reductions in telomere length in immortal telomerase-positive cell lines

    NASA Technical Reports Server (NTRS)

    Schwartz, J. L.; Jordan, R.; Liber, H.; Murnane, J. P.; Evans, H. H.

    2001-01-01

    Telomere shortening in telomerase-negative somatic cells leads to the activation of the TP53 protein and the elimination of potentially unstable cells. We examined the effect of TP53 gene expression on both telomere metabolism and chromosome stability in immortal, telomerase-positive cell lines. Telomere length, telomerase activity, and chromosome instability were measured in multiple clones isolated from three related human B-lymphoblast cell lines that vary in TP53 expression; TK6 cells express wild-type TP53, WTK1 cells overexpress a mutant form of TP53, and NH32 cells express no TP53 protein. Clonal variations in both telomere length and chromosome stability were observed, and shorter telomeres were associated with higher levels of chromosome instability. The shortest telomeres were found in WTK1- and NH32-derived cells, and these cells had 5- to 10-fold higher levels of chromosome instability. The primary marker of instability was the presence of dicentric chromosomes. Aneuploidy and other stable chromosome alterations were also found in clones showing high levels of dicentrics. Polyploidy was found only in WTK1-derived cells. Both telomere length and chromosome instability fluctuated in the different cell populations with time in culture, presumably as unstable cells and cells with short telomeres were eliminated from the growing population. Our results suggest that transient reductions in telomere lengths may be common in immortal cell lines and that these alterations in telomere metabolism can have a profound effect on chromosome stability. Copyright 2000 Wiley-Liss, Inc.

  7. Association between donor leukocyte telomere length and survival after unrelated allogeneic hematopoietic cell transplantation for severe aplastic anemia.

    PubMed

    Gadalla, Shahinaz M; Wang, Tao; Haagenson, Michael; Spellman, Stephen R; Lee, Stephanie J; Williams, Kirsten M; Wong, Jason Y; De Vivo, Immaculata; Savage, Sharon A

    2015-02-10

    Telomeres protect chromosome ends and are markers of cellular aging and replicative capacity. To evaluate the association between recipient and donor pretransplant leukocyte telomere length with outcomes after unrelated donor allogeneic hematopoietic cell transplantation (HCT) for patients with severe aplastic anemia. The study included 330 patients (235 acquired, 85 Fanconi anemia, and 10 Diamond-Blackfan anemia) and their unrelated donors who had pre-HCT blood samples and clinical and outcome data available at the Center for International Blood and Marrow Transplant Research. Patients underwent HCT between 1989 and 2007 in 84 centers and were followed-up to March 2013. Recipient and donor pre-HCT leukocyte telomere length classified into long (third tertile) and short (first and second tertiles combined) based on donor telomere length distribution. Overall survival, neutrophil recovery, and acute and chronic graft-vs-host disease, as ascertained by transplant centers through regular patient follow-up. Longer donor leukocyte telomere length was associated with higher survival probability (5-year overall survival, 56%; number at risk, 57; cumulative deaths, 50) than shorter donor leukocyte telomere length (5-year overall survival, 40%; number at risk, 71; cumulative deaths, 128; P = .009). The association remained statistically significant after adjusting for donor age, disease subtype, Karnofsky performance score, graft type, HLA matching, prior aplastic anemia therapy, race/ethnicity, and calendar year of transplant (hazard ratio [HR], 0.61; 95% CI, 0.44-0.86). Similar results were noted in analyses stratified on severe aplastic anemia subtype, recipient age, HLA matching, calendar year of transplant, and conditioning regimen. There was no association between donor telomere length and neutrophil engraftment at 28 days (cumulative incidence, 86% vs 85%; HR, 0.94; 95% CI, 0.73-1.22), acute graft-vs-host disease grades III-IV at 100 days (cumulative incidence

  8. The role of telomere dynamics in aging and cancer

    NASA Astrophysics Data System (ADS)

    Blagoev, Krastan; Goodwin, Edwin

    2006-03-01

    Telomere length changes are far more dynamic than previously thought. In addition to a gradual loss of ˜100 base pairs per telomere in each cell division, losses as well as gains may occur within a single cell cycle. We are investigating how telomere exchange, extension, and deletion affect the proliferative potential of telomerase-negative somatic cells. Experimental techniques are being devised to detect dynamic telomere processes and quantify both the frequency and length changes of each. In parallel, a ``dynamic telomere model'' is being used that incorporates telomere dynamics to study how the telomere size distribution evolves with time. This is an essential step towards understanding the role that telomere dynamics play in the normal aging of tissues and organisms. The model casts light on relationships not otherwise easily explained by a deterministic ``mitotic clock,'' or to what extent the shortest initial telomere determines the onset of senescence. We also expect to identify biomarkers that will correlate with aging better than average telomere length and to shed light on the transition to unlimited growth found in telomerase-negative tumor cells having the ALT (alternative lengthening of telomeres) phenotype, and to evaluate strategies to suppress the growth of these tumors.

  9. Telomere tracking from birth to adulthood and residential traffic exposure.

    PubMed

    Bijnens, Esmée M; Zeegers, Maurice P; Derom, Catherine; Martens, Dries S; Gielen, Marij; Hageman, Geja J; Plusquin, Michelle; Thiery, Evert; Vlietinck, Robert; Nawrot, Tim S

    2017-11-21

    Telomere attrition is extremely rapid during the first years of life, while lifestyle during adulthood exerts a minor impact. This suggests that early life is an important period in the determination of telomere length. We investigated the importance of the early-life environment on both telomere tracking and adult telomere length. Among 184 twins of the East Flanders Prospective Twin Survey, telomere length in placental tissue and in buccal cells in young adulthood was measured. Residential addresses at birth and in young adulthood were geocoded and residential traffic and greenness exposure was determined. We investigated individual telomere tracking from birth over a 20 year period (mean age (SD), 22.6 (3.1) years) in association with residential exposure to traffic and greenness. Telomere length in placental tissue and in buccal cells in young adulthood correlated positively (r = 0.31, P < 0.0001). Persons with higher placental telomere length at birth were more likely to have a stronger downward shift in telomere ranking over life (P < 0.0001). Maternal residential traffic exposure correlated inversely with telomere length at birth. Independent of birth placental telomere length, telomere ranking between birth and young adulthood was negatively and significantly associated with residential traffic exposure at the birth address, while traffic exposure at the residential address at adult age was not associated with telomere length. Longitudinal evidence of telomere length tracking from birth to adulthood shows inverse associations of residential traffic exposure in association with telomere length at birth as well as accelerated telomere shortening in the first two decades of life.

  10. DIRECT BINDING OF GLYCERALDEHYDE 3-PHOSPHATE DEHYDROGENASE TO TELOMERIC DNA PROTECTS TELOMERES AGAINST CHEMOTHERAPY-INDUCED RAPID DEGRADATION

    PubMed Central

    Demarse, Neil A.; Ponnusamy, Suriyan; Spicer, Eleanor K.; Apohan, Elif; Baatz, John E.; Ogretmen, Besim; Davies, Christopher

    2009-01-01

    GAPDH (glyceraldehyde 3-phosphate dehydrogenase) is a glycolytic enzyme that displays several non-glycolytic activities, including the maintenance and/or protection of telomeres. In this study, we determined the molecular mechanism and biological role of the interaction between GAPDH and human telomeric DNA. Using gel shift assays, we show that recombinant GAPDH binds directly with high affinity (Kd = 45 nM) to a single-stranded oligonucleotide comprising three telomeric DNA repeats and that nucleotides T1, G5 and G6 of the TTAGGG repeat are essential for binding. The stoichiometry of the interaction is 2:1 (DNA: GAPDH), and GAPDH appears to form a high-molecular weight complex when bound to the oligonucleotide. Mutation of Asp32 and Cys149, which are localized to the NAD-binding site and the active site center of GAPDH, respectively, produced mutants that almost completely lost their telomere-binding functions both in vitro and in situ (in A549 human lung cancer cells). Treatment of A549 cells with the chemotherapeutic agents gemcitabine and doxorubicin resulted in increased nuclear localization of expressed wild-type GAPDH, where it protected telomeres against rapid degradation, concomitant with increased resistance to the growth inhibitory effects of these drugs. The non-DNA-binding mutants of GAPDH also localized to the nucleus when expressed in A549 cells, but did not confer any significant protection of telomeres against chemotherapy-induced degradation or growth inhibition, and this occurred without the involvement of caspase activation or apoptosis regulation. Overall, these data demonstrate that GAPDH binds telomeric DNA directly in vitro and may have a biological role in the protection of telomeres against rapid degradation in response to chemotherapeutic agents in A549 human lung cancer cells. PMID:19800890

  11. RPA and POT1: friends or foes at telomeres?

    PubMed

    Flynn, Rachel Litman; Chang, Sandy; Zou, Lee

    2012-02-15

    Telomere maintenance in cycling cells relies on both DNA replication and capping by the protein complex shelterin. Two single-stranded DNA (ssDNA)-binding proteins, replication protein A (RPA) and protection of telomere 1 (POT1) play critical roles in DNA replication and telomere capping, respectively. While RPA binds to ssDNA in a non-sequence-specific manner, POT1 specifically recognizes singlestranded TTAGGG telomeric repeats. Loss of POT1 leads to aberrant accumulation of RPA at telomeres and activation of the ataxia telangiectasia and Rad3-related kinase (ATR)-mediated checkpoint response, suggesting that POT1 antagonizes RPA binding to telomeric ssDNA. The requirement for both POT1 and RPA in telomere maintenance and the antagonism between the two proteins raises the important question of how they function in concert on telomeric ssDNA. Two interesting models were proposed by recent studies to explain the regulation of POT1 and RPA at telomeres. Here, we discuss how these models help unravel the coordination, and also the antagonism, between POT1 and RPA during the cell cycle.

  12. Telomere lengthening and other functions of telomerase.

    PubMed

    Rubtsova, M P; Vasilkova, D P; Malyavko, A N; Naraikina, Yu V; Zvereva, M I; Dontsova, O A

    2012-04-01

    Telomerase is an enzyme that maintains the length of the telomere. The telomere length specifies the number of divisions a cell can undergo before it finally dies (i.e. the proliferative potential of cells). For example, telomerase is activated in embryonic cell lines and the telomere length is maintained at a constant level; therefore, these cells have an unlimited fission potential. Stem cells are characterized by a lower telomerase activity, which enables only partial compensation for the shortening of telomeres. Somatic cells are usually characterized by the absence of telomerase activity. Telomere shortening leads to the attainment of the Hayflick limit, the transition of cells to a state of senescence. The cells subsequently enter a state of crisis, accompanied by massive cell death. The surviving cells become cancer cells, which are capable both of dividing indefinitely and maintaining telomere length (usually with the aid of telomerase). Telomerase is a reverse transcriptase. It consists of two major components: telomerase RNA (TER) and reverse transcriptase (TERT). TER is a non-coding RNA, and it contains the region which serves as a template for telomere synthesis. An increasing number of articles focussing on the alternative functions of telomerase components have recently started appearing. The present review summarizes data on the structure, biogenesis, and functions of telomerase.

  13. Interactions between parental traits, environmental harshness and growth rate in determining telomere length in wild juvenile salmon.

    PubMed

    McLennan, D; Armstrong, J D; Stewart, D C; Mckelvey, S; Boner, W; Monaghan, P; Metcalfe, N B

    2016-11-01

    A larger body size confers many benefits, such as increased reproductive success, ability to evade predators and increased competitive ability and social status. However, individuals rarely maximize their growth rates, suggesting that this carries costs. One such cost could be faster attrition of the telomeres that cap the ends of eukaryotic chromosomes and play an important role in chromosome protection. A relatively short telomere length is indicative of poor biological state, including poorer tissue and organ performance, reduced potential longevity and increased disease susceptibility. Telomere loss during growth may also be accelerated by environmental factors, but these have rarely been subjected to experimental manipulation in the natural environment. Using a wild system involving experimental manipulations of juvenile Atlantic salmon Salmo salar in Scottish streams, we found that telomere length in juvenile fish was influenced by parental traits and by direct environmental effects. We found that faster-growing fish had shorter telomeres and there was a greater cost (in terms of reduced telomere length) if the growth occurred in a harsher environment. We also found a positive association between offspring telomere length and the growth history of their fathers (but not mothers), represented by the number of years fathers had spent at sea. This suggests that there may be long-term consequences of growth conditions and parental life history for individual longevity. © 2016 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  14. Telomere maintenance through recruitment of internal genomic regions.

    PubMed

    Seo, Beomseok; Kim, Chuna; Hills, Mark; Sung, Sanghyun; Kim, Hyesook; Kim, Eunkyeong; Lim, Daisy S; Oh, Hyun-Seok; Choi, Rachael Mi Jung; Chun, Jongsik; Shim, Jaegal; Lee, Junho

    2015-09-18

    Cells surviving crisis are often tumorigenic and their telomeres are commonly maintained through the reactivation of telomerase. However, surviving cells occasionally activate a recombination-based mechanism called alternative lengthening of telomeres (ALT). Here we establish stably maintained survivors in telomerase-deleted Caenorhabditis elegans that escape from sterility by activating ALT. ALT survivors trans-duplicate an internal genomic region, which is already cis-duplicated to chromosome ends, across the telomeres of all chromosomes. These 'Template for ALT' (TALT) regions consist of a block of genomic DNA flanked by telomere-like sequences, and are different between two genetic background. We establish a model that an ancestral duplication of a donor TALT region to a proximal telomere region forms a genomic reservoir ready to be incorporated into telomeres on ALT activation.

  15. Telomeres, Age and Reproduction in a Long-Lived Reptile

    PubMed Central

    Plot, Virginie; Criscuolo, François; Zahn, Sandrine; Georges, Jean-Yves

    2012-01-01

    A major interest has recently emerged in understanding how telomere shortening, mechanism triggering cell senescence, is linked to organism ageing and life history traits in wild species. However, the links between telomere length and key history traits such as reproductive performances have received little attention and remain unclear to date. The leatherback turtle Dermochelys coriacea is a long-lived species showing rapid growth at early stages of life, one of the highest reproductive outputs observed in vertebrates and a dichotomised reproductive pattern related to migrations lasting 2 or 3 years, supposedly associated with different environmental conditions. Here we tested the prediction of blood telomere shortening with age in this species and investigated the relationship between blood telomere length and reproductive performances in leatherback turtles nesting in French Guiana. We found that blood telomere length did not differ between hatchlings and adults. The absence of blood telomere shortening with age may be related to an early high telomerase activity. This telomere-restoring enzyme was formerly suggested to be involved in preventing early telomere attrition in early fast-growing and long-lived species, including squamate reptiles. We found that within one nesting cycle, adult females having performed shorter migrations prior to the considered nesting season had shorter blood telomeres and lower reproductive output. We propose that shorter blood telomeres may result from higher oxidative stress in individuals breeding more frequently (i.e., higher costs of reproduction) and/or restoring more quickly their body reserves in cooler feeding areas during preceding migration (i.e., higher foraging costs). This first study on telomeres in the giant leatherback turtle suggests that blood telomere length predicts not only survival chances, but also reproductive performances. Telomeres may therefore be a promising new tool to evaluate individual reproductive

  16. Measurement of Telomere Length in Colorectal Cancers for Improved Molecular Diagnosis

    PubMed Central

    Le Balc’h, Eric; Grandin, Nathalie; Demattei, Marie-Véronique; Guyétant, Serge; Tallet, Anne; Ouaissi, Mehdi; Lecomte, Thierry

    2017-01-01

    All tumors have in common to reactivate a telomere maintenance mechanism to allow for unlimited proliferation. On the other hand, genetic instability found in some tumors can result from the loss of telomeres. Here, we measured telomere length in colorectal cancers (CRCs) using TRF (Telomere Restriction Fragment) analysis. Telomeric DNA content was also quantified as the ratio of total telomeric (TTAGGG) sequences over that of the invariable Alu sequences. In most of the 125 CRCs analyzed, there was a significant diminution in telomere length compared with that in control healthy tissue. Only 34 tumors exhibited no telomere erosion and, in some cases, a slight telomere lengthening. Telomere length did not correlate with age, gender, tumor stage, tumor localization or stage of tumor differentiation. In addition, while telomere length did not correlate with the presence of a mutation in BRAF (V-raf murine sarcoma viral oncogene homolog B), PIK3CA (phosphatidylinositol 3-kinase catalytic subunit), or MSI status, it was significantly associated with the occurrence of a mutation in KRAS. Interestingly, we found that the shorter the telomeres in healthy tissue of a patient, the larger an increase in telomere length in the tumor. Our study points to the existence of two types of CRCs based on telomere length and reveals that telomere length in healthy tissue might influence telomere maintenance mechanisms in the tumor. PMID:28850092

  17. Measurement of Telomere Length in Colorectal Cancers for Improved Molecular Diagnosis.

    PubMed

    Balc'h, Eric Le; Grandin, Nathalie; Demattei, Marie-Véronique; Guyétant, Serge; Tallet, Anne; Pagès, Jean-Christophe; Ouaissi, Mehdi; Lecomte, Thierry; Charbonneau, Michel

    2017-08-29

    All tumors have in common to reactivate a telomere maintenance mechanism to allow for unlimited proliferation. On the other hand, genetic instability found in some tumors can result from the loss of telomeres. Here, we measured telomere length in colorectal cancers (CRCs) using TRF (Telomere Restriction Fragment) analysis. Telomeric DNA content was also quantified as the ratio of total telomeric (TTAGGG) sequences over that of the invariable Alu sequences. In most of the 125 CRCs analyzed, there was a significant diminution in telomere length compared with that in control healthy tissue. Only 34 tumors exhibited no telomere erosion and, in some cases, a slight telomere lengthening. Telomere length did not correlate with age, gender, tumor stage, tumor localization or stage of tumor differentiation. In addition, while telomere length did not correlate with the presence of a mutation in BRAF (V-raf murine sarcoma viral oncogene homolog B), PIK3CA (phosphatidylinositol 3-kinase catalytic subunit), or MSI status, it was significantly associated with the occurrence of a mutation in KRAS. Interestingly, we found that the shorter the telomeres in healthy tissue of a patient, the larger an increase in telomere length in the tumor. Our study points to the existence of two types of CRCs based on telomere length and reveals that telomere length in healthy tissue might influence telomere maintenance mechanisms in the tumor.

  18. Arabidopsis thaliana telomeres exhibit euchromatic features

    PubMed Central

    Vaquero-Sedas, María I.; Gámez-Arjona, Francisco M.; Vega-Palas, Miguel A.

    2011-01-01

    Telomere function is influenced by chromatin structure and organization, which usually involves epigenetic modifications. We describe here the chromatin structure of Arabidopsis thaliana telomeres. Based on the study of six different epigenetic marks we show that Arabidopsis telomeres exhibit euchromatic features. In contrast, subtelomeric regions and telomeric sequences present at interstitial chromosomal loci are heterochromatic. Histone methyltransferases and the chromatin remodeling protein DDM1 control subtelomeric heterochromatin formation. Whereas histone methyltransferases are required for histone H3K92Me and non-CpG DNA methylation, DDM1 directs CpG methylation but not H3K92Me or non-CpG methylation. These results argue that both kinds of proteins participate in different pathways to reinforce subtelomeric heterochromatin formation. PMID:21071395

  19. Cells with dysfunctional telomeres are susceptible to reactive oxygen species hydrogen peroxide via generation of multichromosomal fusions and chromosomal fragments bearing telomeres

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Woo, Seon Rang; Department of Biochemistry, College of Medicine, Korea University, Seoul 136-705; Park, Jeong-Eun

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Under conditions of telomere erosion, cells become extremely sensitive to H{sub 2}O{sub 2}. Black-Right-Pointing-Pointer Chromosomal regions adjacent to telomeres are cleaved by H{sub 2}O{sub 2} under such conditions. Black-Right-Pointing-Pointer H{sub 2}O{sub 2} thus causes multichromosomal fusions and generation of small chromosomal fragments. Black-Right-Pointing-Pointer N-acetylcysteine prevents H{sub 2}O{sub 2}-induced chromosomal aberrations. -- Abstract: During genotoxic stress, reactive oxygen species hydrogen peroxide (H{sub 2}O{sub 2}) is a prime mediator of the DNA damage response. Telomeres function both to assist in DNA damage repair and to inhibit chromosomal end-to-end fusion. Here, we show that telomere dysfunction renders cells susceptible to H{submore » 2}O{sub 2}, via generation of multichromosomal fusion and chromosomal fragments. H{sub 2}O{sub 2} caused formation of multichromosomal end-to-end fusions involving more than three chromosomes, preferentially when telomeres were erosive. Interestingly, extensive chromosomal fragmentation (yielding small-sized fragments) occurred only in cells exhibiting such multichromosomal fusions. Telomeres were absent from fusion points, being rather present in the small fragments, indicating that H{sub 2}O{sub 2} cleaves chromosomal regions adjacent to telomeres. Restoration of telomere function or addition of the antioxidant N-acetylcysteine prevented development of chromosomal aberrations and rescued the observed hypersensitivity to H{sub 2}O{sub 2}. Thus, chromosomal regions adjacent to telomeres become sensitive to reactive oxygen species hydrogen peroxide when telomeres are dysfunctional, and are cleaved to produce multichromosomal fusions and small chromosomal fragments bearing the telomeres.« less

  20. Tumour-cell apoptosis after cisplatin treatment is not telomere dependent.

    PubMed

    Jeyapalan, Jessie C; Saretzki, Gabriele; Leake, Alan; Tilby, Michael J; von Zglinicki, Thomas

    2006-06-01

    Cisplatin is a major chemotherapeutic agent, especially for the treatment of neuroblastoma. Telomeres with their sequence (TTAGGG)n are probable targets for cisplatin intrastrand cross-linking, but the role of telomeres in mediating cisplatin cytotoxicity is not clear. After exposure to cisplatin as single dose or continuous treatment, we found no loss of telomeres in either SHSY5Y neuroblastoma cells (telomere length, approximately 4 kbp), HeLa 229 cells (telomere length, 20 kbp) or in the acute lymphoblastic T cell line 1301 (telomere length, approximately 80 kbp). There was no induction of telomeric single strand breaks, telomeric overhangs were not degraded and telomerase activity was down-regulated only after massive onset of apoptosis. In contrast, cisplatin induced a delayed formation of DNA strand breaks and induced DNA damage foci containing gamma-H2A.X at nontelomeric sites. Interstitial DNA damage appears to be more important than telomere loss or telomeric damage as inducer of the signal pathway towards apoptosis and/or growth arrest in cisplatin-treated tumour cells.

  1. Prostate Cancer Cell Telomere Length Variability and Stromal Cell Telomere Length as Prognostic Markers for Metastasis and Death

    PubMed Central

    Heaphy, Christopher M.; Yoon, Ghil Suk; Peskoe, Sarah B.; Joshu, Corinne E.; Lee, Thomas K.; Giovannucci, Edward; Mucci, Lorelei A.; Kenfield, Stacey A.; Stampfer, Meir J.; Hicks, Jessica L.; De Marzo, Angelo M.; Platz, Elizabeth A.; Meeker, Alan K.

    2013-01-01

    Current prognostic indicators are imperfect predictors of outcome in men with clinicallylocalized prostate cancer. Thus, tissue-based markers are urgently needed to improve treatment and surveillance decision-making. Given that shortened telomeres enhance chromosomal instability and such instability is a hallmark of metastatic lesions, we hypothesized that alterations in telomere length in the primary cancer would predict risk of progression to metastasis and prostate cancer death. To test this hypothesis, we conducted a prospective cohort study of 596 surgically treated men who participated in the ongoing Health Professionals Follow-up Study. Men who had the combination of more variable telomere length among prostate cancer cells (cell-to-cell) and shorter telomere length in prostate cancer-associated stromal cells were substantially more likely to progress to metastasis or die of their prostate cancer. These findings point to the translational potential of this telomere biomarker for prognostication and risk stratification for individualized therapeutic and surveillance strategies. PMID:23779129

  2. DNA Repair at Telomeres: Keeping the Ends Intact

    PubMed Central

    Webb, Christopher J.; Wu, Yun; Zakian, Virginia A.

    2013-01-01

    The molecular era of telomere biology began with the discovery that telomeres usually consist of G-rich simple repeats and end with 3′ single-stranded tails. Enormous progress has been made in identifying the mechanisms that maintain and replenish telomeric DNA and the proteins that protect them from degradation, fusions, and checkpoint activation. Although telomeres in different organisms (or even in the same organism under different conditions) are maintained by different mechanisms, the disparate processes have the common goals of repairing defects caused by semiconservative replication through G-rich DNA, countering the shortening caused by incomplete replication, and postreplication regeneration of G tails. In addition, standard DNA repair mechanisms must be suppressed or modified at telomeres to prevent their being recognized and processed as DNA double-strand breaks. Here, we discuss the players and processes that maintain and regenerate telomere structure. PMID:23732473

  3. The Genetic Basis of Natural Variation in Caenorhabditis elegans Telomere Length

    PubMed Central

    Cook, Daniel E.; Zdraljevic, Stefan; Tanny, Robyn E.; Seo, Beomseok; Riccardi, David D.; Noble, Luke M.; Rockman, Matthew V.; Alkema, Mark J.; Braendle, Christian; Kammenga, Jan E.; Wang, John; Kruglyak, Leonid; Félix, Marie-Anne; Lee, Junho; Andersen, Erik C.

    2016-01-01

    Telomeres are involved in the maintenance of chromosomes and the prevention of genome instability. Despite this central importance, significant variation in telomere length has been observed in a variety of organisms. The genetic determinants of telomere-length variation and their effects on organismal fitness are largely unexplored. Here, we describe natural variation in telomere length across the Caenorhabditis elegans species. We identify a large-effect variant that contributes to differences in telomere length. The variant alters the conserved oligonucleotide/oligosaccharide-binding fold of protection of telomeres 2 (POT-2), a homolog of a human telomere-capping shelterin complex subunit. Mutations within this domain likely reduce the ability of POT-2 to bind telomeric DNA, thereby increasing telomere length. We find that telomere-length variation does not correlate with offspring production or longevity in C. elegans wild isolates, suggesting that naturally long telomeres play a limited role in modifying fitness phenotypes in C. elegans. PMID:27449056

  4. The Genetic Basis of Natural Variation in Caenorhabditis elegans Telomere Length.

    PubMed

    Cook, Daniel E; Zdraljevic, Stefan; Tanny, Robyn E; Seo, Beomseok; Riccardi, David D; Noble, Luke M; Rockman, Matthew V; Alkema, Mark J; Braendle, Christian; Kammenga, Jan E; Wang, John; Kruglyak, Leonid; Félix, Marie-Anne; Lee, Junho; Andersen, Erik C

    2016-09-01

    Telomeres are involved in the maintenance of chromosomes and the prevention of genome instability. Despite this central importance, significant variation in telomere length has been observed in a variety of organisms. The genetic determinants of telomere-length variation and their effects on organismal fitness are largely unexplored. Here, we describe natural variation in telomere length across the Caenorhabditis elegans species. We identify a large-effect variant that contributes to differences in telomere length. The variant alters the conserved oligonucleotide/oligosaccharide-binding fold of protection of telomeres 2 (POT-2), a homolog of a human telomere-capping shelterin complex subunit. Mutations within this domain likely reduce the ability of POT-2 to bind telomeric DNA, thereby increasing telomere length. We find that telomere-length variation does not correlate with offspring production or longevity in C. elegans wild isolates, suggesting that naturally long telomeres play a limited role in modifying fitness phenotypes in C. elegans. Copyright © 2016 by the Genetics Society of America.

  5. Problem-Solving Test: Telomere Replication

    ERIC Educational Resources Information Center

    Szeberenyi, Jozsef

    2010-01-01

    The Nobel Prize in Physiology or Medicine in 2009 was awarded to Elizabeth H. Blackburn, Carol W. Greider, and Jack W. Szostak for the discovery of "how chromosomes are protected by telomeres and the enzyme telomerase." The discovery has important implications in the processes of cellular aging and carcinogenesis. Telomeres are satellite DNA…

  6. Telomere Attrition in Isolated High-Grade Prostatic Intraepithelial Neoplasia and Surrounding Stroma Is Predictive of Prostate Cancer1

    PubMed Central

    Joshua, Anthony Michael; Vukovic, Bisera; Braudey, Ilan; Hussein, Sundus; Zielenska, Maria; Srigley, John; Evans, Andrew; Squire, Jeremy Andrew

    2007-01-01

    Abstract The causes of early genomic events underlying the development of prostate cancer (CaP) remain unclear. The onset of chromosomal instability is likely to facilitate the formation of crucial genomic aberrations both in the precursor lesion high-grade prostatic intraepithelial neoplasia (HPIN) and in CaP. Instability generated by telomere attrition is one potential mechanism that could initiate chromosomal rearrangements. In this study, normalized telomere length variation was examined in a cohort of 68 men without CaP who had HPIN only on prostatic biopsies. Multiple significant associations between telomere attrition and eventual diagnosis of CaP in the HPIN and in the surrounding stroma were found. Kaplan-Meier analysis of telomere length demonstrated a significantly increased risk for the development of cancer with short telomeres in the surrounding stroma [P = .035; hazard ratio (HR) = 2.12; 95% confidence interval (95% CI) = 0.231–0.956], and a trend for HPIN itself (P = .126; HR = 1.72; 95% CI = 0.287–1.168). Cox regression analysis also demonstrated significance between the time from the original biopsy to the diagnosis of cancer and telomere length in HPIN and in the surrounding stroma. These analyses showed significance, both alone and in combination with baseline prostate-specific antigen, and lend support to the hypothesis that telomere attrition in prostatic preneoplasia may be fundamental to the generation of chromosomal instability and to the emergence of CaP. PMID:17325746

  7. Relationship between interpersonal sensitivity and leukocyte telomere length.

    PubMed

    Suzuki, Akihito; Matsumoto, Yoshihiko; Enokido, Masanori; Shirata, Toshinori; Goto, Kaoru; Otani, Koichi

    2017-10-10

    Telomeres are repetitive DNA sequences located at the ends of chromosomes, and telomere length represents a biological marker for cellular aging. Interpersonal sensitivity, excessive sensitivity to the behavior and feelings of others, is one of the vulnerable factors to depression. In the present study, we examined the effect of interpersonal sensitivity on telomere length in healthy subjects. The subjects were 159 unrelated healthy Japanese volunteers. Mean age ± SD (range) of the subjects was 42.3 ± 7.8 (30-61) years. Interpersonal sensitivity was assessed by the Japanese version of the Interpersonal Sensitivity Measure (IPSM). Leukocyte telomere length was determined by a quantitative real-time PCR method. Higher scores of the total IPSM were significantly (β = -0.163, p = 0.038) related to shorter telomere length. In the sub-scale analysis, higher scores of timidity were significantly (β = -0.220, p = 0.044) associated with shorter telomere length. The present study suggests that subjects with higher interpersonal sensitivity have shorter leukocyte telomere length, implying that interpersonal sensitivity has an impact on cellular aging.

  8. Apollo-taking the lead in telomere protection.

    PubMed

    Sarthy, Jay F; Baumann, Peter

    2010-08-27

    The single-stranded overhangs at the ends of telomeres are thought to be critical for telomere maintenance, but how they are generated has been largely unclear. Two studies (one in this issue of Molecular Cell, Wu et al., 2010) have now implicated the Apollo nuclease in maintaining the overhang specifically at those telomeres generated by leading-strand DNA synthesis. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  9. Correlation of Chromosomal Instability, Telomere Length and Telomere Maintenance in Microsatellite Stable Rectal Cancer: A Molecular Subclass of Rectal Cancer

    PubMed Central

    Boardman, Lisa A.; Johnson, Ruth A.; Viker, Kimberly B.; Hafner, Kari A.; Jenkins, Robert B.; Riegert-Johnson, Douglas L.; Smyrk, Thomas C.; Litzelman, Kristin; Seo, Songwon; Gangnon, Ronald E.; Engelman, Corinne D.; Rider, David N.; Vanderboom, Russell J.; Thibodeau, Stephen N.; Petersen, Gloria M.; Skinner, Halcyon G.

    2013-01-01

    Introduction Colorectal cancer (CRC) tumor DNA is characterized by chromosomal damage termed chromosomal instability (CIN) and excessively shortened telomeres. Up to 80% of CRC is microsatellite stable (MSS) and is historically considered to be chromosomally unstable (CIN+). However, tumor phenotyping depicts some MSS CRC with little or no genetic changes, thus being chromosomally stable (CIN-). MSS CIN- tumors have not been assessed for telomere attrition. Experimental Design MSS rectal cancers from patients ≤50 years old with Stage II (B2 or higher) or Stage III disease were assessed for CIN, telomere length and telomere maintenance mechanism (telomerase activation [TA]; alternative lengthening of telomeres [ALT]). Relative telomere length was measured by qPCR in somatic epithelial and cancer DNA. TA was measured with the TRAPeze assay, and tumors were evaluated for the presence of C-circles indicative of ALT. p53 mutation status was assessed in all available samples. DNA copy number changes were evaluated with Spectral Genomics aCGH. Results Tumors were classified as chromosomally stable (CIN-) and chromosomally instable (CIN+) by degree of DNA copy number changes. CIN- tumors (35%; n=6) had fewer copy number changes (<17% of their clones with DNA copy number changes) than CIN+ tumors (65%; n=13) which had high levels of copy number changes in 20% to 49% of clones. Telomere lengths were longer in CIN- compared to CIN+ tumors (p=0.0066) and in those in which telomerase was not activated (p=0.004). Tumors exhibiting activation of telomerase had shorter tumor telomeres (p=0.0040); and tended to be CIN+ (p=0.0949). Conclusions MSS rectal cancer appears to represent a heterogeneous group of tumors that may be categorized both on the basis of CIN status and telomere maintenance mechanism. MSS CIN- rectal cancers appear to have longer telomeres than those of MSS CIN+ rectal cancers and to utilize ALT rather than activation of telomerase. PMID:24278232

  10. Double-stranded telomeric DNA binding proteins: Diversity matters.

    PubMed

    Červenák, Filip; Juríková, Katarína; Sepšiová, Regina; Neboháčová, Martina; Nosek, Jozef; Tomáška, L'ubomír

    2017-01-01

    Telomeric sequences constitute only a small fraction of the whole genome yet they are crucial for ensuring genomic stability. This function is in large part mediated by protein complexes recruited to telomeric sequences by specific telomere-binding proteins (TBPs). Although the principal tasks of nuclear telomeres are the same in all eukaryotes, TBPs in various taxa exhibit a surprising diversity indicating their distinct evolutionary origin. This diversity is especially pronounced in ascomycetous yeasts where they must have co-evolved with rapidly diversifying sequences of telomeric repeats. In this article we (i) provide a historical overview of the discoveries leading to the current list of TBPs binding to double-stranded (ds) regions of telomeres, (ii) describe examples of dsTBPs highlighting their diversity in even closely related species, and (iii) speculate about possible evolutionary trajectories leading to a long list of various dsTBPs fulfilling the same general role(s) in their own unique ways.

  11. Insights into Cdc13 Dependent Telomere Length Regulation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    M Mason; E Skordalakes

    Cdc13 is a single stranded telomere binding protein that specifically localizes to the telomere ends of budding yeasts and is essential for cell viability. It caps the ends of chromosomes thus preventing chromosome end-to-end fusions and exonucleolytic degradation, events that could lead to genomic instability and senescence, the hallmark of aging. Cdc13 is also involved in telomere length regulation by recruiting or preventing access of telomerase to the telomeric overhang. Recruitment of telomerase to the telomeres for G-strand extension is required for continuous cell division, while preventing its access to the telomeres through capping the chromosome ends prevents mitotic eventsmore » that could lead to cell immortality, the hall mark of carcinogenesis. Cdc13 and its putative homologues human CTC1 and POT1 are therefore key to many biological processes directly associated with life extension and cancer prevention and can be viewed as an ideal target for cancer and age related therapies.« less

  12. Acute exercise activates p38 MAPK and increases the expression of telomere-protective genes in cardiac muscle.

    PubMed

    Ludlow, Andrew T; Gratidão, Laila; Ludlow, Lindsay W; Spangenburg, Espen E; Roth, Stephen M

    2017-04-01

    What is the central question of this study? A positive association between telomere length and exercise training has been shown in cardiac tissue of mice. It is currently unknown how each bout of exercise influences telomere-length-regulating proteins. We sought to determine how a bout of exercise altered the expression of telomere-length-regulating genes and a related signalling pathway in cardiac tissue of mice. What is the main finding and its importance? Acute exercise altered the expression of telomere-length-regulating genes in cardiac tissue and might be related to altered mitogen-activated protein kinase signalling. These findings are important in understanding how exercise provides a cardioprotective phenotype with ageing. Age is the greatest risk factor for cardiovascular disease. Telomere length is shorter in the hearts of aged mice compared with young mice, and short telomere length has been associated with an increased risk of cardiovascular disease. One year of voluntary wheel-running exercise attenuates the age-associated loss of telomere length and results in altered gene expression of telomere-length-maintaining and genome-stabilizing proteins in heart tissue of mice. Understanding the early adaptive response of the heart to an endurance exercise bout is paramount to understanding the impact of endurance exercise on heart tissue and cells. To this end, we studied mice before (BL), immediately after (TP1) and 1 h after a treadmill running bout (TP2). We measured the changes in expression of telomere-related genes (shelterin components), DNA-damage-sensing (p53 and Chk2) and DNA-repair genes (Ku70 and Ku80) and mitogen-activated protein kinase (MAPK) signalling. The TP1 animals had increased TRF1 and TRF2 protein and mRNA levels, greater expression of DNA-repair and -response genes (Chk2 and Ku80) and greater protein content of phosphorylated p38 MAPK compared with both BL and TP2 animals. These data provide insights into how physiological stressors

  13. Chromothripsis and kataegis induced by telomere crisis

    PubMed Central

    Maciejowski, John; Li, Yilong; Bosco, Nazario; Campbell, Peter J.; de Lange, Titia

    2015-01-01

    Telomere crisis occurs during tumorigenesis when depletion of the telomere reserve leads to frequent telomere fusions. The resulting dicentric chromosomes have been proposed to drive genome instability. Here we examine the fate of dicentric human chromosomes in telomere crisis. We observed that dicentric chromosomes invariably persisted through mitosis and developed into 50-200 μm chromatin bridges connecting the daughter cells. Before their resolution at 3-20 h after anaphase, the chromatin bridges induced nuclear envelope rupture in interphase, accumulated the cytoplasmic 3' nuclease TREX1, and developed RPA-coated single stranded (ss) DNA. CRISPR knockouts showed that TREX1 contributed to the generation of the ssDNA and the resolution of the chromatin bridges. Post-crisis clones showed chromothripsis and kataegis, presumably resulting from DNA repair and APOBEC editing of the fragmented chromatin bridge DNA. We propose that chromothripsis in human cancer may arise through TREX1-mediated fragmentation of dicentric chromosomes formed in telomere crisis. PMID:26687355

  14. Apollo contributes to G overhang maintenance and protects leading-end telomeres.

    PubMed

    Wu, Peng; van Overbeek, Megan; Rooney, Sean; de Lange, Titia

    2010-08-27

    Mammalian telomeres contain a single-stranded 3' overhang that is thought to mediate telomere protection. Here we identify the TRF2-interacting factor Apollo as a nuclease that contributes to the generation/maintenance of this overhang. The function of mouse Apollo was determined using Cre-mediated gene deletion, complementation with Apollo mutants, and the TRF2-F120A mutant that cannot bind Apollo. Cells lacking Apollo activated the ATM kinase at their telomeres in S phase and showed leading-end telomere fusions. These telomere dysfunction phenotypes were accompanied by a reduction in the telomeric overhang signal. The telomeric functions of Apollo required its TRF2-interaction and nuclease motifs. Thus, TRF2 recruits the Apollo nuclease to process telomere ends synthesized by leading-strand DNA synthesis, thereby creating a terminal structure that avoids ATM activation and resists end-joining. These data establish that the telomeric overhang is required for the protection of telomeres from the DNA damage response. Copyright (c) 2010 Elsevier Inc. All rights reserved.

  15. SNMIB/Apollo protects leading-strand telomeres against NHEJ-mediated repair.

    PubMed

    Lam, Yung C; Akhter, Shamima; Gu, Peili; Ye, Jing; Poulet, Anaïs; Giraud-Panis, Marie-Josèphe; Bailey, Susan M; Gilson, Eric; Legerski, Randy J; Chang, Sandy

    2010-07-07

    Progressive telomere attrition or deficiency of the protective shelterin complex elicits a DNA damage response as a result of a cell's inability to distinguish dysfunctional telomeric ends from DNA double-strand breaks. SNMIB/Apollo is a shelterin-associated protein and a member of the SMN1/PSO2 nuclease family that localizes to telomeres through its interaction with TRF2. Here, we generated SNMIB/Apollo knockout mouse embryo fibroblasts (MEFs) to probe the function of SNMIB/Apollo at mammalian telomeres. SNMIB/Apollo null MEFs exhibit an increased incidence of G2 chromatid-type fusions involving telomeres created by leading-strand DNA synthesis, reflective of a failure to protect these telomeres after DNA replication. Mutations within SNMIB/Apollo's conserved nuclease domain failed to suppress this phenotype, suggesting that its nuclease activity is required to protect leading-strand telomeres. SNMIB/Apollo(-/-)ATM(-/-) MEFs display robust telomere fusions when Trf2 is depleted, indicating that ATM is dispensable for repair of uncapped telomeres in this setting. Our data implicate the 5'-3' exonuclease function of SNM1B/Apollo in the generation of 3' single-stranded overhangs at newly replicated leading-strand telomeres to protect them from engaging the non-homologous end-joining pathway.

  16. Human telomeres that contain (CTAGGG)n repeats show replication dependent instability in somatic cells and the male germline

    PubMed Central

    Mendez-Bermudez, Aaron; Hills, Mark; Pickett, Hilda A.; Phan, Anh Tuân; Mergny, Jean-Louis; Riou, Jean-François; Royle, Nicola J.

    2009-01-01

    A number of different processes that impact on telomere length dynamics have been identified but factors that affect the turnover of repeats located proximally within the telomeric DNA are poorly defined. We have identified a particular repeat type (CTAGGG) that is associated with an extraordinarily high mutation rate (20% per gamete) in the male germline. The mutation rate is affected by the length and sequence homogeneity of the (CTAGGG)n array. This level of instability was not seen with other sequence-variant repeats, including the TCAGGG repeat type that has the same composition. Telomeres carrying a (CTAGGG)n array are also highly unstable in somatic cells with the mutation process resulting in small gains or losses of repeats that also occasionally result in the deletion of the whole (CTAGGG)n array. These sequences are prone to quadruplex formation in vitro but adopt a different topology from (TTAGGG)n (see accompanying article). Interestingly, short (CTAGGG)2 oligonucleotides induce a DNA damage response (γH2AX foci) as efficiently as (TTAGGG)2 oligos in normal fibroblast cells, suggesting they recruit POT1 from the telomere. Moreover, in vitro assays show that (CTAGGG)n repeats bind POT1 more efficiently than (TTAGGG)n or (TCAGGG)n. We estimate that 7% of human telomeres contain (CTAGGG)n repeats and when present, they create additional problems that probably arise during telomere replication. PMID:19656953

  17. Mouse CCDC79 (TERB1) is a meiosis-specific telomere associated protein.

    PubMed

    Daniel, Katrin; Tränkner, Daniel; Wojtasz, Lukasz; Shibuya, Hiroki; Watanabe, Yoshinori; Alsheimer, Manfred; Tóth, Attila

    2014-05-22

    Telomeres have crucial meiosis-specific roles in the orderly reduction of chromosome numbers and in ensuring the integrity of the genome during meiosis. One such role is the attachment of telomeres to trans-nuclear envelope protein complexes that connect telomeres to motor proteins in the cytoplasm. These trans-nuclear envelope connections between telomeres and cytoplasmic motor proteins permit the active movement of telomeres and chromosomes during the first meiotic prophase. Movements of chromosomes/telomeres facilitate the meiotic recombination process, and allow high fidelity pairing of homologous chromosomes. Pairing of homologous chromosomes is a prerequisite for their correct segregation during the first meiotic division. Although inner-nuclear envelope proteins, such as SUN1 and potentially SUN2, are known to bind and recruit meiotic telomeres, these proteins are not meiosis-specific, therefore cannot solely account for telomere-nuclear envelope attachment and/or for other meiosis-specific characteristics of telomeres in mammals. We identify CCDC79, alternatively named TERB1, as a meiosis-specific protein that localizes to telomeres from leptotene to diplotene stages of the first meiotic prophase. CCDC79 and SUN1 associate with telomeres almost concurrently at the onset of prophase, indicating a possible role for CCDC79 in telomere-nuclear envelope interactions and/or telomere movements. Consistent with this scenario, CCDC79 is missing from most telomeres that fail to connect to SUN1 protein in spermatocytes lacking the meiosis-specific cohesin SMC1B. SMC1B-deficient spermatocytes display both reduced efficiency in telomere-nuclear envelope attachment and reduced stability of telomeres specifically during meiotic prophase. Importantly, CCDC79 associates with telomeres in SUN1-deficient spermatocytes, which strongly indicates that localization of CCDC79 to telomeres does not require telomere-nuclear envelope attachment. CCDC79 is a meiosis-specific telomere

  18. Mouse CCDC79 (TERB1) is a meiosis-specific telomere associated protein

    PubMed Central

    2014-01-01

    Background Telomeres have crucial meiosis-specific roles in the orderly reduction of chromosome numbers and in ensuring the integrity of the genome during meiosis. One such role is the attachment of telomeres to trans-nuclear envelope protein complexes that connect telomeres to motor proteins in the cytoplasm. These trans-nuclear envelope connections between telomeres and cytoplasmic motor proteins permit the active movement of telomeres and chromosomes during the first meiotic prophase. Movements of chromosomes/telomeres facilitate the meiotic recombination process, and allow high fidelity pairing of homologous chromosomes. Pairing of homologous chromosomes is a prerequisite for their correct segregation during the first meiotic division. Although inner-nuclear envelope proteins, such as SUN1 and potentially SUN2, are known to bind and recruit meiotic telomeres, these proteins are not meiosis-specific, therefore cannot solely account for telomere-nuclear envelope attachment and/or for other meiosis-specific characteristics of telomeres in mammals. Results We identify CCDC79, alternatively named TERB1, as a meiosis-specific protein that localizes to telomeres from leptotene to diplotene stages of the first meiotic prophase. CCDC79 and SUN1 associate with telomeres almost concurrently at the onset of prophase, indicating a possible role for CCDC79 in telomere-nuclear envelope interactions and/or telomere movements. Consistent with this scenario, CCDC79 is missing from most telomeres that fail to connect to SUN1 protein in spermatocytes lacking the meiosis-specific cohesin SMC1B. SMC1B-deficient spermatocytes display both reduced efficiency in telomere-nuclear envelope attachment and reduced stability of telomeres specifically during meiotic prophase. Importantly, CCDC79 associates with telomeres in SUN1-deficient spermatocytes, which strongly indicates that localization of CCDC79 to telomeres does not require telomere-nuclear envelope attachment. Conclusion CCDC79

  19. Dissecting the telomere-inner nuclear membrane interface formed in meiosis.

    PubMed

    Pendlebury, Devon F; Fujiwara, Yasuhiro; Tesmer, Valerie M; Smith, Eric M; Shibuya, Hiroki; Watanabe, Yoshinori; Nandakumar, Jayakrishnan

    2017-12-01

    Tethering telomeres to the inner nuclear membrane (INM) allows homologous chromosome pairing during meiosis. The meiosis-specific protein TERB1 binds the telomeric protein TRF1 to establish telomere-INM connectivity and is essential for mouse fertility. Here we solve the structure of the human TRF1-TERB1 interface to reveal the structural basis for telomere-INM linkage. Disruption of this interface abrogates binding and compromises telomere-INM attachment in mice. An embedded CDK-phosphorylation site within the TRF1-binding region of TERB1 provides a mechanism for cap exchange, a late-pachytene phenomenon involving the dissociation of the TRF1-TERB1 complex. Indeed, further strengthening this interaction interferes with cap exchange. Finally, our biochemical analysis implicates distinct complexes for telomere-INM tethering and chromosome-end protection during meiosis. Our studies unravel the structure, stoichiometry, and physiological implications underlying telomere-INM tethering, thereby providing unprecedented insights into the unique function of telomeres in meiosis.

  20. Suppression of telomere-binding protein TPP1 resulted in telomere dysfunction and enhanced radiation sensitivity in telomerase-negative osteosarcoma cell line

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qiang, Weiguang; Department of Oncology, The Third Affiliated Hospital, Soochow University, Changzhou; Wu, Qinqin

    Highlights: • Down-regulation of TPP1 shortened telomere length in telomerase-negative cells. • Down-regulation of TPP1 induced cell apoptosis in telomerase-negative cells. • Down-regulation of TPP1 increased radiosensitivity in telomerase-negative cells. - Abstract: Mammalian telomeres are protected by the shelterin complex that contains the six core proteins POT1, TPP1, TIN2, TRF1, TRF2 and RAP1. TPP1, formerly known as TINT1, PTOP, and PIP1, is a key factor that regulates telomerase recruitment and activity. In addition to this, TPP1 is required to mediate the shelterin assembly and stabilize telomere. Previous work has found that TPP1 expression was elevated in radioresistant cells and thatmore » overexpression of TPP1 led to radioresistance and telomere lengthening in telomerase-positive cells. However, the exact effects and mechanism of TPP1 on radiosensitivity are yet to be precisely defined in the ALT cells. Here we report on the phenotypes of the conditional deletion of TPP1 from the human osteosarcoma U2OS cells using ALT pathway to extend the telomeres.TPP1 deletion resulted in telomere shortening, increased apoptosis and radiation sensitivity enhancement. Together, our findings show that TPP1 plays a vital role in telomere maintenance and protection and establish an intimate relationship between TPP1, telomere and cellular response to ionizing radiation, but likely has the specific mechanism yet to be defined.« less

  1. A computational model for telomere-dependent cell-replicative aging.

    PubMed

    Portugal, R D; Land, M G P; Svaiter, B F

    2008-01-01

    Telomere shortening provides a molecular basis for the Hayflick limit. Recent data suggest that telomere shortening also influence mitotic rate. We propose a stochastic growth model of this phenomena, assuming that cell division in each time interval is a random process which probability decreases linearly with telomere shortening. Computer simulations of the proposed stochastic telomere-regulated model provides good approximation of the qualitative growth of cultured human mesenchymal stem cells.

  2. Ancestral telomere shortening: a countdown that will increase mean life span?

    PubMed

    Hertzog, Radu G

    2006-01-01

    Like cells, all mammals have a limited life span. Among cells there are a few exceptions (e.g., immortal cells), among mammals not, even if some of them live longer. Many in vitro and in vivo studies support the consensus that telomere length is strongly correlated with life span. At the somatic cellular level, long telomeres have been associated with longer life span. A different situation can be seen in immortal cells, such as cancer, germ and stem cells, where telomeres are maintained by telomerase, a specialized reverse transcriptase that is involved in synthesis of telomeres. Irrespective of telomere length, if telomerase is active, telomeres can be maintained at a sufficient length to ensure cell survival. To the contrary, telomeres shorten progressively with each cell division and when a critical telomere length (Hayflick limit) is reached, the cells undergo senescence and subsequently apoptosis. In mammals, those with the longest telomeres (e.g., mice) have the shortest life span. Furthermore, the shorter the mean telomere length, the longer the mean life span, as observed in humans (10-14 kpb) and bowhead-whales (undetermined telomere length), which have the longest mean life span among mammals. Over the past centuries, human average life span has increased. The hypothesis presented here suggests that this continual increase in the mean life span could be due to a decrease of mean telomere length over the last hundreds years. Actually, the life span is not directly influenced by length of telomeres, but rather by telomere length - dependent gene expression pattern. According to Greider, "rather than average telomere length, it is the shortest telomere length that makes the biggest difference to a cell". In the context of fast-growing global elderly population due to increase in life expectancy, it also seem to be an age related increase in cancer incidence. Nevertheless, extending healthy life span could depend on how good cells achieve, during the

  3. Air Pollution Stress and the Aging Phenotype: The Telomere Connection.

    PubMed

    Martens, Dries S; Nawrot, Tim S

    2016-09-01

    Aging is a complex physiological phenomenon. The question why some subjects grow old while remaining free from disease whereas others prematurely die remains largely unanswered. We focus here on the role of air pollution in biological aging. Hallmarks of aging can be grouped into three main categories: genomic instability, telomere attrition, and epigenetic alterations leading to altered mitochondrial function and cellular senescence. At birth, the initial telomere length of a person is largely determined by environmental factors. Telomere length shortens with each cell division and exposure to air pollution as well as low residential greens space exposure is associated with shorter telomere length. Recent studies show that the estimated effects of particulate air pollution exposure on the telomere mitochondrial axis of aging may play an important role in chronic health effects of air pollution. The exposome encompasses all exposures over an entire life. As telomeres can be considered as the cellular memories of exposure to oxidative stress and inflammation, telomere maintenance may be a proxy for assessing the "exposome". If telomeres are causally related to the aging phenotype and environmental air pollution is an important determinant of telomere length, this might provide new avenues for future preventive strategies.

  4. Suppression of telomere-binding protein TPP1 resulted in telomere dysfunction and enhanced radiation sensitivity in telomerase-negative osteosarcoma cell line.

    PubMed

    Qiang, Weiguang; Wu, Qinqin; Zhou, Fuxiang; Xie, Conghua; Wu, Changping; Zhou, Yunfeng

    2014-03-07

    Mammalian telomeres are protected by the shelterin complex that contains the six core proteins POT1, TPP1, TIN2, TRF1, TRF2 and RAP1. TPP1, formerly known as TINT1, PTOP, and PIP1, is a key factor that regulates telomerase recruitment and activity. In addition to this, TPP1 is required to mediate the shelterin assembly and stabilize telomere. Previous work has found that TPP1 expression was elevated in radioresistant cells and that overexpression of TPP1 led to radioresistance and telomere lengthening in telomerase-positive cells. However, the exact effects and mechanism of TPP1 on radiosensitivity are yet to be precisely defined in the ALT cells. Here we report on the phenotypes of the conditional deletion of TPP1 from the human osteosarcoma U2OS cells using ALT pathway to extend the telomeres.TPP1 deletion resulted in telomere shortening, increased apoptosis and radiation sensitivity enhancement. Together, our findings show that TPP1 plays a vital role in telomere maintenance and protection and establish an intimate relationship between TPP1, telomere and cellular response to ionizing radiation, but likely has the specific mechanism yet to be defined. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. High Mobility Group A2 protects cancer cells against telomere dysfunction

    PubMed Central

    Natarajan, Suchitra; Begum, Farhana; Gim, Jeonga; Wark, Landon; Henderson, Dana; Davie, James R.

    2016-01-01

    The non-histone chromatin binding protein High Mobility Group AT-hook protein 2 (HMGA2) plays important roles in the repair and protection of genomic DNA in embryonic stem cells and cancer cells. Here we show that HMGA2 localizes to mammalian telomeres and enhances telomere stability in cancer cells. We present a novel interaction of HMGA2 with the key shelterin protein TRF2. We found that the linker (L1) region of HMGA2 contributes to this interaction but the ATI-L1-ATII molecular region of HMGA2 is required for strong interaction with TRF2. This interaction was independent of HMGA2 DNA-binding and did not require the TRF2 interacting partner RAP1 but involved the homodimerization and hinge regions of TRF2. HMGA2 retained TRF2 at telomeres and reduced telomere-dysfunction despite induced telomere stress. Silencing of HMGA2 resulted in (i) reduced binding of TRF2 to telomere DNA as observed by ChIP, (ii) increased telomere instability and (iii) the formation of telomere dysfunction-induced foci (TIF). This resulted in increased telomere aggregation, anaphase bridges and micronuclei. HMGA2 prevented ATM-dependent pTRF2T188 phosphorylation and attenuated signaling via the telomere specific ATM-CHK2-CDC25C DNA damage signaling axis. In summary, our data demonstrate a unique and novel role of HMGA2 in telomere protection and promoting telomere stability in cancer cells. This identifies HMGA2 as a new therapeutic target for the destabilization of telomeres in HMGA2+ cancer cells. PMID:26799419

  6. Stress appraisals and cellular aging: A key role for anticipatory threat in the relationship between psychological stress and telomere length

    PubMed Central

    O’Donovan, Aoife; Tomiyama, A. Janet; Lin, Jue; Puterman, Eli; Adler, Nancy E.; Kemeny, Margaret; Wolkowitz, Owen M.; Blackburn, Elizabeth H.; Epel, Elissa S.

    2012-01-01

    Chronic psychological stressis a risk factor formultiple diseases of aging. Accelerated cellular aging as indexed by short telomere length has emerged as a potential common biological mechanism linking various forms of psychological stress and diseases of aging. Stress appraisals determine the degree and type of biological stress responses and altered stress appraisals may be a common psychological mechanism linking psychological stress and diseases of aging. However, no previous studies have examined the relationship between stress appraisals and telomere length. We exposed chronically stressed female caregivers and non-caregiving controls (N= 50; M age = 62.14±6.10) to a standardized acute laboratory stressor and measured their anticipatory and retrospective threat and challenge appraisals of the stressor. We hypothesized that threat and challenge appraisals would be associated with shorter and longer telomere length respectively, and that chronic care giving stress would influence telomere length through altered stress appraisals. Higher anticipatory threat appraisals were associated with shorter age-adjusted telomere length (β = −.32, p = .03), but challenge appraisals and retrospective threat appraisals showed no independent association with telomere length. Caregivers reported significantly higher anticipatory (β = −.36, p = .006)and retrospective (β = −.29, p = .03) threat appraisals than controls, but similar challenge appraisals. Although there was no significant main effect of caregiver status on telomere length, care giving had a significant indirect effect on telomere length through anticipatory threat appraisals. Exaggerated anticipatory threat appraisals may be a common and modifiable psychological mechanism of psychological stress effects on cellular aging. PMID:22293459

  7. [Telomere lengthening by trichostatin A treatment in cloned pigs].

    PubMed

    Xie, Bing-Teng; Ji, Guang-Zhen; Kong, Qing-Ran; Mao, Jian; Shi, Yong-Qian; Liu, Shi-Chao; Wu, Mei-Ling; Wang, Juan; Liu, Lin; Liu, Zhong-Hua

    2012-12-01

    Telomeres are repeated GC rich sequences at the end of chromosomes, and shorten with each cell division due to DNA end replication problem. Previously, reprogrammed somatic cells of cloned animals display variable telomere elongation. However, it was reported that the cloned animals including Dolly do not reset telomeres and show premature aging. In this study, we investigated telomere function in cloned or transgenic cloned pigs, including the cloned Northeast Min pigs, eGFP, Mx, and PGC1α transgenic cloned pigs, and found that the telomere lengths of cloned pigs were significantly shorter than the nuclear donor adult fibroblasts and age-matched noncloned pigs (P<0.05), indicating that nuclear reprogramming did not restore cellular age of donor cells after somatic cell nuclear transfer (SCNT). Trichostatin A (TSA), an inhibitor of histone deacetylase, has proven to enhance the efficiency of nuclear reprogramming in several species. In order to test whether TSA also can effectively enhance reprogramming of telomeres, TSA (40 nmol/L) was used to treat porcine cloned embryos at 1-cell stage for 24 h. Consistent with previous reports, the developmental rate of SCNT embryos to the blastocyst stage was significantly increased compared with those of the control group (16.35% vs. 27.09%, 21.60% vs. 34.90%, P<0.05). Notably, the telomere length of cloned porcine blastocysts was also significantly elongated (P<0.05). Although TSA did not improve the cloning efficiency (1.3% vs. 1.7%, TSA vs. control), the telomere lengths of cloned pig-lets were significantly longer compared with those of the control group and the donor fibroblasts (P<0.05). In conclusion, telomeres have not been effectively restored by SCNT in pigs but TSA can effectively lengthen the telomere lengths of cloned pigs.

  8. Leukocyte telomere length in relation to risk of lung adenocarcinoma incidence: Findings from the Singapore Chinese Health Study.

    PubMed

    Yuan, Jian-Min; Beckman, Kenneth B; Wang, Renwei; Bull, Caroline; Adams-Haduch, Jennifer; Huang, Joyce Y; Jin, Aizhen; Opresko, Patricia; Newman, Anne B; Zheng, Yun-Ling; Fenech, Michael; Koh, Woon-Puay

    2018-06-01

    Telomeres are crucial in the maintenance of chromosome integrity and genomic stability. Critically short telomeres can trigger programed cell death while cells with longer telomeres may have increased likelihood of replicative errors, resulting in genetic mutations and chromosomal alterations, and ultimately promoting oncogenesis. Data on telomere length and lung cancer risk from large prospective cohort studies are spare. Relative telomere length in peripheral blood leukocytes was quantified using a validated monochrome multiplex quantitative polymerase chain reaction (qPCR) method in 26,540 participants of the Singapore Chinese Health Study. After a follow-up of 12 years, 654 participants developed lung cancer including 288 adenocarcinoma, 113 squamous cell carcinoma and 253 other/unknown histological type. The Cox proportional hazard regression was used to estimate hazard ratio (HR) and 95% confidence interval (CI). HR of lung adenocarcinoma for individuals in the highest comparing the lowest 20 percentile of telomere length was 2.84 (95% CI 1.94-4.14, p trend  < 0.0001). This positive association was present in never smokers (p trend  < 0.0001), ever smokers (p trend  = 0.0010), men (p trend  = 0.0003), women (p trend  < 0.0001), and in shorter (p trend  = 0.0002) and longer (p trend  = 0.0001) duration of follow-up. There was no association between telomere length and risk of squamous cell carcinoma or other histological type of lung cancer in all or subgroups of individuals. The agreement of results from this prospective cohort study with those of previous prospective studies and Mendelian randomization studies suggest a possible etiological role of telomere length in the development of lung adenocarcinoma. © 2018 UICC.

  9. Presence of alternative lengthening of telomeres associated circular extrachromosome telomere repeats in primary leukemia cells of chronic myeloid leukemia

    PubMed Central

    2013-01-01

    Background The predominant mechanism by which human tumors maintain telomere length is via telomerase. In ~10% of tumor samples, however, telomere length is conserved, despite no detectable telomerase activity, in part through activation of the alternative lengthening of telomeres (ALT) pathway. Methods We studied the circular extra-chromosomal telomeric repeat (ECTR), an ALT hallmark, and telomerase activity in 24 chronic myeloid leukemia (CML) patients in chronic phase (CP). Results We identified the presence of ECTR in primary leukemia cells from some of these samples, which indicates the possible involvement of an ALT mechanism. Moreover, we found that some samples exhibited both circular ECTR and telomerase activities, suggesting that both mechanisms can contribute to the onset of CML. Conclusion We propose that ALT or the combined activities of ALT and telomerase might be required for the early stages of leukemogenesis. These findings shed new light into the oncogenic pathways responsible for the maintenance of telomere length in leukemia, which will ultimately determine the effectiveness of anti-telomerase-based treatment protocols. PMID:23547895

  10. Need telomere maintenance? Call 911.

    PubMed

    Francia, Sofia; Weiss, Robert S; d'Adda di Fagagna, Fabrizio

    2007-01-17

    "Natura non facit saltum" (nature makes no leap) the Latins used to say, meaning that nature does not like discontinuities. Cells make no exception and indeed any discontinuity in the DNA double helix is promptly detected, triggering an alteration of cell proliferation and an attempt to repair. Yet, linear chromosomes bear DNA ends that are compatible with normal cell proliferation and they escape, under normal conditions, any repair. How telomeres, the chromosomes tips, achieve that is not fully understood. We recently observed that the Rad9/Hus1/Rad1 (911) complex, previously known for its functions in DNA metabolism and DNA damage responses, is constitutively associated with telomeres and plays an important role in their maintenance. Here, we summarize the available data and discuss the potential mechanisms of 911 action at telomeres.

  11. Need telomere maintenance? Call 911

    PubMed Central

    Francia, Sofia; Weiss, Robert S; d'Adda di Fagagna, Fabrizio

    2007-01-01

    "Natura non facit saltum" (nature makes no leap) the Latins used to say, meaning that nature does not like discontinuities. Cells make no exception and indeed any discontinuity in the DNA double helix is promptly detected, triggering an alteration of cell proliferation and an attempt to repair. Yet, linear chromosomes bear DNA ends that are compatible with normal cell proliferation and they escape, under normal conditions, any repair. How telomeres, the chromosomes tips, achieve that is not fully understood. We recently observed that the Rad9/Hus1/Rad1 (911) complex, previously known for its functions in DNA metabolism and DNA damage responses, is constitutively associated with telomeres and plays an important role in their maintenance. Here, we summarize the available data and discuss the potential mechanisms of 911 action at telomeres. PMID:17229321

  12. Shorter leukocyte telomere length is associated with higher risk of infections: a prospective study of 75,309 individuals from the general population.

    PubMed

    Helby, Jens; Nordestgaard, Børge G; Benfield, Thomas; Bojesen, Stig E

    2017-08-01

    In the general population, older age is associated with short leukocyte telomere length and with high risk of infections. In a recent study of allogeneic hematopoietic cell transplantation for severe aplastic anemia, long donor leukocyte telomere length was associated with improved survival in the recipients. These findings suggest that leukocyte telomere length could possibly be a marker of immune competence. Therefore, we tested the hypothesis that shorter leukocyte telomere length is associated with higher risk of infectious disease hospitalization and infection-related death. Relative peripheral blood leukocyte telomere length was measured using quantitative polymerase chain reaction in 75,309 individuals from the general population and the individuals were followed for up to 23 years. During follow up, 9228 individuals were hospitalized with infections and infection-related death occurred in 1508 individuals. Shorter telomere length was associated with higher risk of any infection (hazard ratio 1.05 per standard deviation shorter leukocyte telomere length; 95% confidence interval 1.03-1.07) and pneumonia (1.07; 1.03-1.10) after adjustment for conventional infectious disease risk factors. Corresponding hazard ratios for infection-related death were 1.10 (1.04-1.16) for any infection and 1.11 (1.04-1.19) for pneumonia. Telomere length was not associated with risk of skin infection, urinary tract infection, sepsis, diarrheal disease, endocarditis, meningitis or other infections. In conclusion, our findings indicate that leukocyte telomere length may be a marker of immune competence. Further studies are needed to determine whether risk of infections in allogeneic hematopoietic cell transplantation recipients can be reduced by considering donor leukocyte telomere length when selecting donors. Copyright© 2017 Ferrata Storti Foundation.

  13. Snail1 transcription factor controls telomere transcription and integrity

    PubMed Central

    Mazzolini, Rocco; Gonzàlez, Núria; Garcia-Garijo, Andrea; Millanes-Romero, Alba; Peiró, Sandra; Smith, Susan

    2018-01-01

    Abstract Besides controlling epithelial-to-mesenchymal transition (EMT) and cell invasion, the Snail1 transcriptional factor also provides cells with cancer stem cell features. Since telomere maintenance is essential for stemness, we have examined the control of telomere integrity by Snail1. Fluorescence in situ hybridization (FISH) analysis indicates that Snail1-depleted mouse mesenchymal stem cells (MSC) have both a dramatic increase of telomere alterations and shorter telomeres. Remarkably, Snail1-deficient MSC present higher levels of both telomerase activity and the long non-coding RNA called telomeric repeat-containing RNA (TERRA), an RNA that controls telomere integrity. Accordingly, Snail1 expression downregulates expression of the telomerase gene (TERT) as well as of TERRA 2q, 11q and 18q. TERRA and TERT are transiently downregulated during TGFβ-induced EMT in NMuMG cells, correlating with Snail1 expression. Global transcriptome analysis indicates that ectopic expression of TERRA affects the transcription of some genes induced during EMT, such as fibronectin, whereas that of TERT does not modify those genes. We propose that Snail1 repression of TERRA is required not only for telomere maintenance but also for the expression of a subset of mesenchymal genes. PMID:29059385

  14. Loss of Wild-Type ATRX Expression in Somatic Cell Hybrids Segregates with Activation of Alternative Lengthening of Telomeres

    PubMed Central

    Cole, Sara L.; Dagg, Rebecca A.; Lau, Loretta M. S.; Duncan, Emma L.; Moy, Elsa L.; Reddel, Roger R.

    2012-01-01

    Alternative Lengthening of Telomeres (ALT) is a non-telomerase mechanism of telomere lengthening that occurs in about 10% of cancers overall and is particularly common in astrocytic brain tumors and specific types of sarcomas. Somatic cell hybridization analyses have previously shown that normal telomerase-negative fibroblasts and telomerase-positive immortalized cell lines contain repressors of ALT activity, indicating that activation of ALT results from loss of one or more unidentified repressors. More recently, ATRX or DAXX was shown to be mutated both in tumors with telomere lengths suggestive of ALT activity and in ALT cell lines. Here, an ALT cell line was separately fused to each of four telomerase-positive cell lines, and four or five independent hybrid lines from each fusion were examined for expression of ATRX and DAXX and for telomere lengthening mechanism. The hybrid lines expressed either telomerase or ALT, with the other mechanism being repressed. DAXX was expressed normally in all parental cell lines and in all of the hybrids. ATRX was expressed normally in each of the four telomerase-positive parental cell lines and in every telomerase-positive hybrid line, and was abnormal in the ALT parental cells and in all but one of the ALT hybrids. This correlation between ALT activity and loss of ATRX expression is consistent with ATRX being a repressor of ALT. PMID:23185534

  15. Molecular Dynamics Simulation of Telomere and TRF1

    NASA Astrophysics Data System (ADS)

    Kaburagi, Masaaki; Fukuda, Masaki; Yamada, Hironao; Miyakawa, Takeshi; Morikawa, Ryota; Takasu, Masako; Kato, Takamitsu A.; Uesaka, Mitsuru

    Telomeres play a central role in determining longevity of a cell. Our study focuses on the interaction between telomeric guanines and TRF1 as a means to observe the telomeric based mechanism of the genome protection. In this research, we performed molecular dynamics simulations of a telomeric DNA and TRF1. Our results show a stable structure with a high affinity for the specific protein. Additionally, we calculated the distance between guanines and the protein in their complex state. From this comparison, we found the calculated values of distance to be very similar, and the angle of guanines in their complex states was larger than that in their single state.

  16. Social Isolation Shortens Telomeres in African Grey Parrots (Psittacus erithacus erithacus)

    PubMed Central

    Aydinonat, Denise; Penn, Dustin J.; Smith, Steve; Moodley, Yoshan; Hoelzl, Franz; Knauer, Felix; Schwarzenberger, Franz

    2014-01-01

    Telomeres, the caps of eukaryotic chromosomes, control chromosome stability and cellular senescence, but aging and exposure to chronic stress are suspected to cause attrition of telomere length. We investigated the effect of social isolation on telomere length in the highly social and intelligent African Grey parrot (Psittacus erithacus erithacus). Our study population consisted of single-housed (n = 26) and pair-housed (n = 19) captive individuals between 0.75 to 45 years of age. Relative telomere length of erythrocyte DNA was measured by quantitative real-time PCR. We found that telomere length declined with age (p<0.001), and socially isolated parrots had significantly shorter telomeres compared to pair-housed birds (p<0.001) – even among birds of similar ages. Our findings provide the first evidence that social isolation affects telomere length, which supports the hypothesis that telomeres provide a biomarker indicating exposure to chronic stress. PMID:24705445

  17. Accelerated telomere shortening and replicative senescence in human fibroblasts overexpressing mutant and wild-type lamin A

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang Shurong; Risques, Rosa Ana; Martin, George M.

    2008-01-01

    LMNA mutations are responsible for a variety of genetic disorders, including muscular dystrophy, lipodystrophy, and certain progeroid syndromes, notably Hutchinson-Gilford Progeria. Although a number of clinical features of these disorders are suggestive of accelerated aging, it is not known whether cells derived from these patients exhibit cellular phenotypes associated with accelerated aging. We examined a series of isogenic skin fibroblast lines transfected with LMNA constructs bearing known pathogenic point mutations or deletion mutations found in progeroid syndromes. Fibroblasts overexpressing mutant lamin A exhibited accelerated rates of loss of telomeres and shortened replicative lifespans, in addition to abnormal nuclear morphology. Tomore » our surprise, these abnormalities were also observed in lines overexpressing wild-type lamin A. Copy number variants are common in human populations; those involving LMNA, whether arising meiotically or mitotically, might lead to progeroid phenotypes. In an initial pilot study of 23 progeroid cases without detectable WRN or LMNA mutations, however, no cases of altered LMNA copy number were detected. Nevertheless, our findings raise a hypothesis that changes in lamina organization may cause accelerated telomere attrition, with different kinetics for overexpession of wild-type and mutant lamin A, which leads to rapid replicative senescence and progroid phenotypes.« less

  18. Telomere Maintenance Mechanisms in Cancer.

    PubMed

    Gaspar, Tiago Bordeira; Sá, Ana; Lopes, José Manuel; Sobrinho-Simões, Manuel; Soares, Paula; Vinagre, João

    2018-05-03

    Tumour cells can adopt telomere maintenance mechanisms (TMMs) to avoid telomere shortening, an inevitable process due to successive cell divisions. In most tumour cells, telomere length (TL) is maintained by reactivation of telomerase, while a small part acquires immortality through the telomerase-independent alternative lengthening of telomeres (ALT) mechanism. In the last years, a great amount of data was generated, and different TMMs were reported and explained in detail, benefiting from genome-scale studies of major importance. In this review, we address seven different TMMs in tumour cells: mutations of the TERT promoter ( TERTp ), amplification of the genes TERT and TERC , polymorphic variants of the TERT gene and of its promoter, rearrangements of the TERT gene, epigenetic changes, ALT, and non-defined TMM (NDTMM). We gathered information from over fifty thousand patients reported in 288 papers in the last years. This wide data collection enabled us to portray, by organ/system and histotypes, the prevalence of TERTp mutations, TERT and TERC amplifications, and ALT in human tumours. Based on this information, we discuss the putative future clinical impact of the aforementioned mechanisms on the malignant transformation process in different setups, and provide insights for screening, prognosis, and patient management stratification.

  19. Telomere biology in aging and cancer: early history and perspectives.

    PubMed

    Hayashi, Makoto T

    2018-01-20

    The ends of eukaryotic linear chromosomes are protected from undesired enzymatic activities by a nucleoprotein complex called the telomere. Expanding evidence indicates that telomeres have central functions in human aging and tumorigenesis. While it is undoubtedly important to follow current advances in telomere biology, it is also fruitful to be well informed in seminal historical studies for a comprehensive understanding of telomere biology, and for the anticipation of future directions. With this in mind, I here summarize the early history of telomere biology and current advances in the field, mostly focusing on mammalian studies relevant to aging and cancer.

  20. P66SHC deletion improves fertility and progeric phenotype of late-generation TERC-deficient mice but not their short lifespan.

    PubMed

    Giorgio, Marco; Stendardo, Massimo; Migliaccio, Enrica; Pelicci, Pier Giuseppe

    2016-06-01

    Oxidative stress and telomere attrition are considered the driving factors of aging. As oxidative damage to telomeric DNA favors the erosion of chromosome ends and, in turn, telomere shortening increases the sensitivity to pro-oxidants, these two factors may trigger a detrimental vicious cycle. To check whether limiting oxidative stress slows down telomere shortening and related progeria, we have investigated the effect of p66SHC deletion, which has been shown to reduce oxidative stress and mitochondrial apoptosis, on late-generation TERC (telomerase RNA component)-deficient mice having short telomeres and reduced lifespan. Double mutant (TERC(-/-) p66SHC(-/-) ) mice were generated, and their telomere length, fertility, and lifespan investigated in different generations. Results revealed that p66SHC deletion partially rescues sterility and weight loss, as well as organ atrophy, of TERC-deficient mice, but not their short lifespan and telomere erosion. Therefore, our data suggest that p66SHC-mediated oxidative stress and telomere shortening synergize in some tissues (including testes) to accelerate aging; however, early mortality of late-generation mice seems to be independent of any link between p66SHC-mediated oxidative stress and telomere attrition. © 2016 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  1. Unusual chromosomal organization of telomeric sequences and expeditious karyotypic differentiation in the recently evolved Mus terricolor complex.

    PubMed

    Sharma, G G; Sharma, T

    1998-01-01

    The Mus terricolor complex displays a stable homozygous arrangement of autosomal heterochromatin variations in the form of accretion of definitive autosomal short arms among three nonoverlapping populations, in concert with an expeditious evolutionary differentiation into three chromosomal species: M. terricolor I, II, and III. In contrast to the highly conservative M. musculus-like chromosomes in the coexisting sibling species, M. booduga, reshuffling and differentiation of centric heterochromatin has occurred in harmony with a revision of centric configurations, resulting in acrocentric and submetacentric autosomes. The chromosomal distribution of the prevalent vertebrate telomeric sequence (TTAGGG)n was examined by fluorescence in situ hybridization to metaphase cells of M. terricolor I, II, and III. An unusual centric organization of internal telomeric sequences was detected in all the submetacentric and acrocentric autosomes. An auxiliary role of these presumably fragile, recombinogenic telomeric sequences in the evolutionary revision of centric configurations in the terricolor complex is hypothesized.

  2. Telomere- and Telomerase-Associated Proteins and Their Functions in the Plant Cell

    PubMed Central

    Procházková Schrumpfová, Petra; Schořová, Šárka; Fajkus, Jiří

    2016-01-01

    Telomeres, as physical ends of linear chromosomes, are targets of a number of specific proteins, including primarily telomerase reverse transcriptase. Access of proteins to the telomere may be affected by a number of diverse factors, e.g., protein interaction partners, local DNA or chromatin structures, subcellular localization/trafficking, or simply protein modification. Knowledge of composition of the functional nucleoprotein complex of plant telomeres is only fragmentary. Moreover, the plant telomeric repeat binding proteins that were characterized recently appear to also be involved in non-telomeric processes, e.g., ribosome biogenesis. This interesting finding was not totally unexpected since non-telomeric functions of yeast or animal telomeric proteins, as well as of telomerase subunits, have been reported for almost a decade. Here we summarize known facts about the architecture of plant telomeres and compare them with the well-described composition of telomeres in other organisms. PMID:27446102

  3. The molecular genetics of the telomere biology disorders.

    PubMed

    Bertuch, Alison A

    2016-08-02

    The importance of telomere function for human health is exemplified by a collection of Mendelian disorders referred to as the telomere biology disorders (TBDs), telomeropathies, or syndromes of telomere shortening. Collectively, the TBDs cover a spectrum of conditions from multisystem disease presenting in infancy to isolated disease presentations in adulthood, most notably idiopathic pulmonary fibrosis. Eleven genes have been found mutated in the TBDs to date, each of which is linked to some aspect of telomere maintenance. This review summarizes the molecular defects that result from mutations in these genes, highlighting recent advances, including the addition of PARN to the TBD gene family and the discovery of heterozygous mutations in RTEL1 as a cause of familial pulmonary fibrosis.

  4. Snail1 transcription factor controls telomere transcription and integrity.

    PubMed

    Mazzolini, Rocco; Gonzàlez, Núria; Garcia-Garijo, Andrea; Millanes-Romero, Alba; Peiró, Sandra; Smith, Susan; García de Herreros, Antonio; Canudas, Sílvia

    2018-01-09

    Besides controlling epithelial-to-mesenchymal transition (EMT) and cell invasion, the Snail1 transcriptional factor also provides cells with cancer stem cell features. Since telomere maintenance is essential for stemness, we have examined the control of telomere integrity by Snail1. Fluorescence in situ hybridization (FISH) analysis indicates that Snail1-depleted mouse mesenchymal stem cells (MSC) have both a dramatic increase of telomere alterations and shorter telomeres. Remarkably, Snail1-deficient MSC present higher levels of both telomerase activity and the long non-coding RNA called telomeric repeat-containing RNA (TERRA), an RNA that controls telomere integrity. Accordingly, Snail1 expression downregulates expression of the telomerase gene (TERT) as well as of TERRA 2q, 11q and 18q. TERRA and TERT are transiently downregulated during TGFβ-induced EMT in NMuMG cells, correlating with Snail1 expression. Global transcriptome analysis indicates that ectopic expression of TERRA affects the transcription of some genes induced during EMT, such as fibronectin, whereas that of TERT does not modify those genes. We propose that Snail1 repression of TERRA is required not only for telomere maintenance but also for the expression of a subset of mesenchymal genes. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  5. The relationship between telomere length and beekeeping among Malaysians.

    PubMed

    Nasir, Nurul Fatihah Mohamad; Kannan, Thirumulu Ponnuraj; Sulaiman, Siti Amrah; Shamsuddin, Shaharum; Azlina, Ahmad; Stangaciu, Stefan

    2015-06-01

    The belief that beekeepers live longer than anyone else is present since ages. However, no research has been done to explore the longevity of life in beekeepers. Here, we investigated the telomere length in 30 male beekeepers and 30 male non-beekeepers and associated them with the longevity of life using Southern analysis of terminal restriction fragments (TRFs) generated by Hinf I/Rsa I digestion of human genomic DNA using TeloTAGGG Telomere Length Assay. Interestingly, we found that the telomere length of male beekeepers was significantly longer than those of male non-beekeepers with a p value of less than 0.05, suggesting that beekeepers may have longer life compared to non-beekeepers. We further found that the consumption of bee products for a long period and frequent consumption of bee products per day are associated with telomere length. An increase of year in consuming bee products is associated with a mean increase in telomere length of 0.258 kbp. In addition, an increase in frequency of eating bee products per day was also associated with a mean increase of 2.66 kbp in telomere length. These results suggested that bee products might play some roles in telomere length maintenance.

  6. Study of telomere length and different markers of oxidative stress in patients with Parkinson's disease.

    PubMed

    Watfa, G; Dragonas, C; Brosche, T; Dittrich, R; Sieber, C C; Alecu, C; Benetos, A; Nzietchueng, R

    2011-04-01

    Many studies have shown that short telomere length (TL) is associated with high oxidative stress and various age-related diseases. Parkinson's disease (PD) is an age-related disease, and although its pathogenic mechanism is uncertain, oxidative stress is believed to be implicated in this pathology. The aim of this case-control study was to assess both TL and the different markers of oxidative stress in elderly patients with PD compared to age control subjects. 20 PD patients and 15 age-matched controls, >65 years were studied. TL was measured by Southern blotting from DNA samples extracted from white blood cells. Superoxide dismutase (SOD) activity and plasma levels of total glutathione and protein carbonyls were determined. There was a trend for lower TL in PD patients: 6.06 ± 0.81 kb in PD versus 6.45 ± 0.73 kb in controls (p = 0.08). No significant difference was found between the two groups in terms of oxidative stress markers. In controls, age was the main determinant of telomere shortening (r = -0.547; p = 0.03) whereas, in PD patients, telomere shortening was mainly dependent on plasmatic concentrations of carbonyl proteins (r= -0.544; p=0.044). In PD patients, a negative association was observed between plasma carbonyl protein levels and SOD activity (r= -0.622, p=0.004). In PD, TL is shorter in presence of high oxidative stress as measured by carbonyl protein levels. The absence of telomere attrition with age among patients with PD could reflect a telomere regulation by mechanisms other than age.

  7. Silencing is noisy: population and cell level noise in telomere-adjacent genes is dependent on telomere position and sir2.

    PubMed

    Anderson, Matthew Z; Gerstein, Aleeza C; Wigen, Lauren; Baller, Joshua A; Berman, Judith

    2014-07-01

    Cell-to-cell gene expression noise is thought to be an important mechanism for generating phenotypic diversity. Furthermore, telomeric regions are major sites for gene amplification, which is thought to drive genetic diversity. Here we found that individual subtelomeric TLO genes exhibit increased variation in transcript and protein levels at both the cell-to-cell level as well as at the population-level. The cell-to-cell variation, termed Telomere-Adjacent Gene Expression Noise (TAGEN) was largely intrinsic noise and was dependent upon genome position: noise was reduced when a TLO gene was expressed at an ectopic internal locus and noise was elevated when a non-telomeric gene was expressed at a telomere-adjacent locus. This position-dependent TAGEN also was dependent on Sir2p, an NAD+-dependent histone deacetylase. Finally, we found that telomere silencing and TAGEN are tightly linked and regulated in cis: selection for either silencing or activation of a TLO-adjacent URA3 gene resulted in reduced noise at the neighboring TLO but not at other TLO genes. This provides experimental support to computational predictions that the ability to shift between silent and active chromatin states has a major effect on cell-to-cell noise. Furthermore, it demonstrates that these shifts affect the degree of expression variation at each telomere individually.

  8. Association between leukocyte telomere length and serum carotenoid in US adults.

    PubMed

    Min, Kyoung-Bok; Min, Jin-Young

    2017-04-01

    Telomere length is a biomarker for aging. It is known that oxidative stress can accelerate telomere shortening, whereas antioxidants can delay their shortening. Carotenoids as antioxidants are favorably associated with health- and aging-related diseases caused by oxidative stress, but their association with telomere length is less certain. We investigated the association between blood carotenoid levels and leukocyte telomere length in a representative sample of US adults. We analyzed 3660 participants aged 20 years and older in the 1999-2002 National Health and Nutrition Examination Survey. The levels of carotenoids-alpha-carotene, beta-carotene (trans + cis), beta-cryptoxanthin, combined lutein/zeaxanthin, and trans-lycopene-were measured using high-performance liquid chromatography. The leukocyte telomere length (T/S ratio) was assayed using the quantitative polymerase chain reaction method. A doubling of blood alpha-carotene, beta-carotene (trans + cis), and beta-cryptoxanthin was associated with approximately 2 % longer telomeres. Compared with the lowest carotenoid quartile of alpha-carotene, beta-carotene (trans + cis), and beta-cryptoxanthin, telomere length for adults with the highest quartiles was significantly increased by 5-8 %. We found that increasing levels of blood carotenoid were significantly associated with longer leukocyte telomeres in US adults. High intake of carotenoid-rich food may play a role in protecting telomeres and regulating telomere length.

  9. Implications of telomeres and telomerase in endometrial pathology

    PubMed Central

    Hapangama, D.K.; Kamal, A.; Saretzki, G.

    2017-01-01

    Abstract BACKGROUND Eukaryotic chromosomal ends are linear and are protected by nucleoprotein complexes known as telomeres. The complex structural anatomy and the diverse functions of telomeres as well as the unique reverse transcriptase enzyme, telomerase that maintains telomeres are under intensive scientific scrutiny. Both are involved in many human diseases including cancer, but also in ageing and chronic disease such as diabetes. Their intricate involvement in many cellular processes and pathways is being dynamically deciphered in many organs including the endometrium. This review summarizes our current knowledge on the topic of telomeres and telomerase and their potential role in providing plausible explanations for endometrial aberrations related to common gynaecological pathologies. OBJECTIVE AND RATIONALE This review outlines the recent major findings in telomere and telomerase functions in the context of endometrial biology. It highlights the contemporary discoveries in hormonal regulation, normal endometrial regeneration, stem cells and common gynaecological diseases such as endometriosis, infertility, recurrent reproductive failure and endometrial cancer (EC). SEARCH METHODS The authors carried out systematic PubMed (Medline) and Ovid searches using the key words: telomerase, telomeres, telomere length, human telomerase reverse transcriptase, telomeric RNA component, with endometrium, hormonal regulation, endometrial stem/progenitor cells, endometrial regeneration, endometriosis, recurrent miscarriage, infertility, endometrial hyperplasia, EC and uterine cancer. Publications used in this review date from 1995 until 31st June 2016. OUTCOMES The human endometrium is a unique somatic organ, which displays dynamic telomerase activity (TA) related to the menstrual cycle. Telomerase is implicated in almost all endometrial pathologies and appears to be crucial to endometrial stem cells. In particular, it is vital for normal endometrial regeneration, providing

  10. Mathematical model of alternative mechanism of telomere length maintenance

    NASA Astrophysics Data System (ADS)

    Kollár, Richard; Bod'ová, Katarína; Nosek, Jozef; Tomáška, L'ubomír

    2014-03-01

    Biopolymer length regulation is a complex process that involves a large number of biological, chemical, and physical subprocesses acting simultaneously across multiple spatial and temporal scales. An illustrative example important for genomic stability is the length regulation of telomeres—nucleoprotein structures at the ends of linear chromosomes consisting of tandemly repeated DNA sequences and a specialized set of proteins. Maintenance of telomeres is often facilitated by the enzyme telomerase but, particularly in telomerase-free systems, the maintenance of chromosomal termini depends on alternative lengthening of telomeres (ALT) mechanisms mediated by recombination. Various linear and circular DNA structures were identified to participate in ALT, however, dynamics of the whole process is still poorly understood. We propose a chemical kinetics model of ALT with kinetic rates systematically derived from the biophysics of DNA diffusion and looping. The reaction system is reduced to a coagulation-fragmentation system by quasi-steady-state approximation. The detailed treatment of kinetic rates yields explicit formulas for expected size distributions of telomeres that demonstrate the key role played by the J factor, a quantitative measure of bending of polymers. The results are in agreement with experimental data and point out interesting phenomena: an appearance of very long telomeric circles if the total telomere density exceeds a critical value (excess mass) and a nonlinear response of the telomere size distributions to the amount of telomeric DNA in the system. The results can be of general importance for understanding dynamics of telomeres in telomerase-independent systems as this mode of telomere maintenance is similar to the situation in tumor cells lacking telomerase activity. Furthermore, due to its universality, the model may also serve as a prototype of an interaction between linear and circular DNA structures in various settings.

  11. NBS1 Phosphorylation Status Dictates Repair Choice of Dysfunctional Telomeres.

    PubMed

    Rai, Rekha; Hu, Chunyi; Broton, Cayla; Chen, Yong; Lei, Ming; Chang, Sandy

    2017-03-02

    Telomeres employ TRF2 to protect chromosome ends from activating the DNA damage sensor MRE11-RAD50-NBS1 (MRN), thereby repressing ATM-dependent DNA damage checkpoint responses. How TRF2 prevents MRN activation at dysfunctional telomeres is unclear. Here, we show that the phosphorylation status of NBS1 determines the repair pathway choice of dysfunctional telomeres. The crystal structure of the TRF2-NBS1 complex at 3.0 Å resolution shows that the NBS1 429 YQLSP 433 motif interacts specifically with the TRF2 TRFH domain. Phosphorylation of NBS1 serine 432 by CDK2 in S/G2 dissociates NBS1 from TRF2, promoting TRF2-Apollo/SNM1B complex formation and the protection of leading-strand telomeres. Classical-NHEJ-mediated repair of telomeres lacking TRF2 requires phosphorylated NBS1 S432 to activate ATM, while interaction of de-phosphorylated NBS1 S432 with TRF2 promotes alternative-NHEJ repair of telomeres lacking POT1-TPP1. Our work advances understanding of how the TRF2 TRFH domain orchestrates telomere end protection and reveals how the phosphorylation status of the NBS1 S432 dictates repair pathway choice of dysfunctional telomeres. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Telomeres, Nutrition, and Longevity: Can We Really Navigate Our Aging?

    PubMed

    Vidacek, Nikolina Škrobot; Nanic, Lucia; Ravlic, Sanda; Sopta, Mary; Geric, Marko; Gajski, Goran; Garaj-Vrhovac, Vera; Rubelj, Ivica

    2017-12-12

    Telomeres are dynamic chromosome-end structures that serve as guardians of genome stability. They are known to be one of the major determinants of aging and longevity in higher mammals. Studies have demonstrated a direct correlation between telomere length and life expectancy, stress, DNA damage, and onset of aging-related diseases. This review discusses the most important factors that influence our telomeres. Various genetic and environmental factors such as diet, physical activity, obesity, and stress are known to influence health and longevity as well as telomere dynamics. Individuals currently have the opportunity to modulate the dynamics of their aging and health span, monitor these processes, and even make future projections by following their telomere dynamics. As telomeres react to positive as well as negative health factors, we should be able to directly influence our telomere metabolism, slow their deterioration, and diminish our aging and perhaps extend our life and health span. © The Author(s) 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Clinical and cytogenetic findings in seven cases of inverted duplication of 8p with evidence of a telomeric deletion using fluorescence in situ hybridization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Guo, Wen-Jun; Callif-Daley, F.; Zapata, M.C.

    1995-09-11

    We report on the clinical and cytogenetic findings in 7 cases of inverted duplication of region 8p11.2-p23. The phenotype of inv dup (8p) compiled from this series and the literature (N = 29) consists of severe mental retardation (100%), minor facial alterations (97%), agenesis of the corpus callosum (80%), hypotonia (66%), orthopedic abnormalities (58%), scoliosis/kyphosis (40%), and congenital heart defect (26%). A telomeric deletion of region 8p23.3-pter was confirmed in 3 of our cases studied using fluorescent in situ hybridization with a telomeric probe for 8p. Thus, these karyotypes are inv dup del(8) (qter{r_arrow} p23.1::p23.1{r_arrow}p11.2:). Our findings suggest that mostmore » cases of inv dup(8p) probably have a telomeric deletion. 20 refs., 4 figs., 2 tabs.« less

  14. Frequency and Determinants of a Short-Interval Follow-up Recommendation After an Abnormal Screening Mammogram.

    PubMed

    Pelletier, Eric; Daigle, Jean-Marc; Defay, Fannie; Major, Diane; Guertin, Marie-Hélène; Brisson, Jacques

    2016-11-01

    After imaging assessment of an abnormal screening mammogram, a follow-up examination 6 months later is recommended to some women. Our aim was to identify which characteristics of lesions, women, and physicians are associated to such short-interval follow-up recommendation in the Quebec Breast Cancer Screening Program. Between 1998 and 2008, 1,839,396 screening mammograms were performed and a total of 114,781 abnormal screens were assessed by imaging only. Multivariate analysis was done with multilevel Poisson regression models with robust variance and generalized linear mixed models. A short-interval follow-up was recommended in 26.7% of assessments with imaging only, representing 2.3% of all screens. Case-mix adjusted proportion of short-interval follow-up recommendations varied substantially across physicians (range: 4%-64%). Radiologists with high recall rates (≥15%) had a high proportion of short-interval follow-up recommendation (risk ratio: 1.82; 95% confidence interval: 1.35-2.45) compared to radiologists with low recall rates (<5%). The adjusted proportion of short-interval follow-up was high (22.8%) even when a previous mammogram was usually available. Short-interval follow-up recommendation at assessment is frequent in this Canadian screening program, even when a previous mammogram is available. Characteristics related to radiologists appear to be key determinants of short-interval follow-up recommendation, rather than characteristics of lesions or patient mix. Given that it can cause anxiety to women and adds pressure on the health system, it appears important to record and report short-interval follow-up and to identify ways to reduce its frequency. Short-interval follow-up recommendations should be considered when assessing the burden of mammography screening. Copyright © 2016 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

  15. Live-cell CRISPR imaging in plants reveals dynamic telomere movements.

    PubMed

    Dreissig, Steven; Schiml, Simon; Schindele, Patrick; Weiss, Oda; Rutten, Twan; Schubert, Veit; Gladilin, Evgeny; Mette, Michael F; Puchta, Holger; Houben, Andreas

    2017-08-01

    Elucidating the spatiotemporal organization of the genome inside the nucleus is imperative to our understanding of the regulation of genes and non-coding sequences during development and environmental changes. Emerging techniques of chromatin imaging promise to bridge the long-standing gap between sequencing studies, which reveal genomic information, and imaging studies that provide spatial and temporal information of defined genomic regions. Here, we demonstrate such an imaging technique based on two orthologues of the bacterial clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR associated protein 9 (Cas9). By fusing eGFP/mRuby2 to catalytically inactive versions of Streptococcus pyogenes and Staphylococcus aureus Cas9, we show robust visualization of telomere repeats in live leaf cells of Nicotiana benthamiana. By tracking the dynamics of telomeres visualized by CRISPR-dCas9, we reveal dynamic telomere movements of up to 2 μm over 30 min during interphase. Furthermore, we show that CRISPR-dCas9 can be combined with fluorescence-labelled proteins to visualize DNA-protein interactions in vivo. By simultaneously using two dCas9 orthologues, we pave the way for the imaging of multiple genomic loci in live plants cells. CRISPR imaging bears the potential to significantly improve our understanding of the dynamics of chromosomes in live plant cells. © 2017 The Authors The Plant Journal published by John Wiley & Sons Ltd and Society for Experimental Biology.

  16. The longest telomeres: a general signature of adult stem cell compartments

    PubMed Central

    Flores, Ignacio; Canela, Andres; Vera, Elsa; Tejera, Agueda; Cotsarelis, George; Blasco, María A.

    2008-01-01

    Identification of adult stem cells and their location (niches) is of great relevance for regenerative medicine. However, stem cell niches are still poorly defined in most adult tissues. Here, we show that the longest telomeres are a general feature of adult stem cell compartments. Using confocal telomere quantitative fluorescence in situ hybridization (telomapping), we find gradients of telomere length within tissues, with the longest telomeres mapping to the known stem cell compartments. In mouse hair follicles, we show that cells with the longest telomeres map to the known stem cell compartments, colocalize with stem cell markers, and behave as stem cells upon treatment with mitogenic stimuli. Using K15-EGFP reporter mice, which mark hair follicle stem cells, we show that GFP-positive cells have the longest telomeres. The stem cell compartments in small intestine, testis, cornea, and brain of the mouse are also enriched in cells with the longest telomeres. This constitutes the description of a novel general property of adult stem cell compartments. Finally, we make the novel finding that telomeres shorten with age in different mouse stem cell compartments, which parallels a decline in stem cell functionality, suggesting that telomere loss may contribute to stem cell dysfunction with age. PMID:18283121

  17. Genomic stability and telomere regulation in skeletal muscle tissue.

    PubMed

    Trajano, Larissa Alexsandra da Silva Neto; Trajano, Eduardo Tavares Lima; Silva, Marco Aurélio Dos Santos; Stumbo, Ana Carolina; Mencalha, Andre Luiz; Fonseca, Adenilson de Souza da

    2018-02-01

    Muscle injuries are common, especially in sports and cumulative trauma disorder, and their repair is influenced by free radical formation, which causes damages in lipids, proteins and DNA. Oxidative DNA damages are repaired by base excision repair and nucleotide excision repair, ensuring telomeric and genomic stability. There are few studies on this topic in skeletal muscle cells. This review focuses on base excision repair and nucleotide excision repair, telomere regulation and how telomeric stabilization influences healthy muscle, injured muscle, exercise, and its relationship with aging. In skeletal muscle, genomic stabilization and telomere regulation seem to play an important role in tissue health, influencing muscle injury repair. Thus, therapies targeting mechanisms of DNA repair and telomeric regulation could be new approaches for improving repair and prevention of skeletal muscle injuries in young and old people. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

  18. The gene for achondroplasia maps to the telomeric region of chromosome 4p.

    PubMed

    Velinov, M; Slaugenhaupt, S A; Stoilov, I; Scott, C I; Gusella, J F; Tsipouras, P

    1994-03-01

    Achondroplasia is the most common type of genetic dwarfism. It is characterized by disproportionate short stature and other skeletal anomalies resulting from a defect in the maturation of the chondrocytes in the growth plate of the cartilage. We have now mapped the achondroplasia gene near the telomere of the short arm of chromosome 4 (4p16.3), by family linkage studies using 14 pedigrees. A positive lod score of z = 3.35 with no recombinants was obtained with an intragenic marker for IDUA. This localization will facilitate the positional cloning of the disease gene.

  19. Association of a Platinum Complex to a G-Quadruplex Ligand Enhances Telomere Disruption.

    PubMed

    Charif, Razan; Granotier-Beckers, Christine; Bertrand, Hélène Charlotte; Poupon, Joël; Ségal-Bendirdjian, Evelyne; Teulade-Fichou, Marie-Paule; Boussin, François D; Bombard, Sophie

    2017-08-21

    Telomeres protect the ends of chromosomes against illegitimate recombination and repair. They can be targets for G-quadruplex ligands and platinum complexes due to their repeated G-rich sequences. Protection of telomeres is ensured by a complex of six proteins, including TRF2, which inhibits the DNA damage response pathway. We analyzed telomere modifications induced in cancer cells by the experimental hybrid platinum complex, Pt-MPQ, comprising both an ethylene diamine monofunctional platinum complex and a G-quadruplex recognition moiety (MPQ). Pt-MPQ promotes the displacement of two telomeric proteins (TRF2 and TRF1) from telomeres, as well as the formation of telomere damage and telomere sister losses, whereas the control compound MPQ does not. This suggests that the platinum moiety potentiates the targeting of the G-quadruplex ligand to telomeres, opening a new perspective for telomere biology and anticancer therapy. Interestingly, the chemotherapy drug cisplatin, which has no specific affinity for G-quadruplex structures, partially induces the TRF2 delocalization from telomeres but produces less telomeric DNA damage, suggesting that this TRF2 displacement could be independent of G-quadruplex recognition.

  20. Telomere length and cortisol reactivity in children of depressed mothers.

    PubMed

    Gotlib, I H; LeMoult, J; Colich, N L; Foland-Ross, L C; Hallmayer, J; Joormann, J; Lin, J; Wolkowitz, O M

    2015-05-01

    A growing body of research demonstrates that individuals diagnosed with major depressive disorder (MDD) are characterized by shortened telomere length, which has been posited to underlie the association between depression and increased instances of medical illness. The temporal nature of the relation between MDD and shortened telomere length, however, is not clear. Importantly, both MDD and telomere length have been associated independently with high levels of stress, implicating dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis and anomalous levels of cortisol secretion in this relation. Despite these associations, no study has assessed telomere length or its relation with HPA-axis activity in individuals at risk for depression, before the onset of disorder. In the present study, we assessed cortisol levels in response to a laboratory stressor and telomere length in 97 healthy young daughters of mothers either with recurrent episodes of depression (i.e., daughters at familial risk for depression) or with no history of psychopathology. We found that daughters of depressed mothers had shorter telomeres than did daughters of never-depressed mothers and, further, that shorter telomeres were associated with greater cortisol reactivity to stress. This study is the first to demonstrate that children at familial risk of developing MDD are characterized by accelerated biological aging, operationalized as shortened telomere length, before they had experienced an onset of depression; this may predispose them to develop not only MDD but also other age-related medical illnesses. It is critical, therefore, that we attempt to identify and distinguish genetic and environmental mechanisms that contribute to telomere shortening.

  1. A role for heterochromatin protein 1γ at human telomeres

    PubMed Central

    Canudas, Silvia; Houghtaling, Benjamin R.; Bhanot, Monica; Sasa, Ghadir; Savage, Sharon A.; Bertuch, Alison A.; Smith, Susan

    2011-01-01

    Human telomere function is mediated by shelterin, a six-subunit complex that is required for telomere replication, protection, and cohesion. TIN2, the central component of shelterin, has binding sites to three subunits: TRF1, TRF2, and TPP1. Here we identify a fourth partner, heterochromatin protein 1γ (HP1γ), that binds to a conserved canonical HP1-binding motif, PXVXL, in the C-terminal domain of TIN2. We show that HP1γ localizes to telomeres in S phase, where it is required to establish/maintain cohesion. We further demonstrate that the HP1-binding site in TIN2 is required for sister telomere cohesion and can impact telomere length maintenance by telomerase. Remarkably, the PTVML HP1-binding site is embedded in the recently identified cluster of mutations in TIN2 that gives rise to dyskeratosis congenita (DC), an inherited bone marrow failure syndrome caused by defects in telomere maintenance. We show that DC-associated mutations in TIN2 abrogate binding to HP1γ and that DC patient cells are defective in sister telomere cohesion. Our data indicate a novel requirement for HP1γ in the establishment/maintenance of cohesion at human telomeres and, furthermore, may provide insight into the mechanism of pathogenesis in TIN2-mediated DC. PMID:21865325

  2. Multifunctional Role of ATM/Tel1 Kinase in Genome Stability: From the DNA Damage Response to Telomere Maintenance

    PubMed Central

    2014-01-01

    The mammalian protein kinase ataxia telangiectasia mutated (ATM) is a key regulator of the DNA double-strand-break response and belongs to the evolutionary conserved phosphatidylinositol-3-kinase-related protein kinases. ATM deficiency causes ataxia telangiectasia (AT), a genetic disorder that is characterized by premature aging, cerebellar neuropathy, immunodeficiency, and predisposition to cancer. AT cells show defects in the DNA damage-response pathway, cell-cycle control, and telomere maintenance and length regulation. Likewise, in Saccharomyces cerevisiae, haploid strains defective in the TEL1 gene, the ATM ortholog, show chromosomal aberrations and short telomeres. In this review, we outline the complex role of ATM/Tel1 in maintaining genomic stability through its control of numerous aspects of cellular survival. In particular, we describe how ATM/Tel1 participates in the signal transduction pathways elicited by DNA damage and in telomere homeostasis and its importance as a barrier to cancer development. PMID:25247188

  3. A meta-analysis of the relationship between anxiety and telomere length.

    PubMed

    Malouff, John M; Schutte, Nicola S

    2017-05-01

    Telomeres are protective caps at the ends of chromosomes, and shorter telomeres are associated with poor physical health. The present study set out to consolidate the varying effect sizes found so far in studies of anxiety and telomere length. A meta-analytic investigation of the relationship between anxiety and telomere length used information from 17 different samples comprising a total of 19,424 participants. The results showed a small but significant association, r = -.06, between higher anxiety and shorter telomeres. Studies comparing individuals diagnosed with an anxiety disorder with other individuals had a significant effect size, and studies that did not use this comparison threshold did not have a significant effect size. Anxiety is associated with an important biomarker related to health. Future experimental studies that examine the impact of interventions intended to reduce anxiety in conjunction with measurement of telomere length can further clarify the impact of anxiety on telomere length.

  4. Measuring telomere length and telomere dynamics in evolutionary biology and ecology

    PubMed Central

    Nussey, Daniel H; Baird, Duncan; Barrett, Emma; Boner, Winnie; Fairlie, Jennifer; Gemmell, Neil; Hartmann, Nils; Horn, Thorsten; Haussmann, Mark; Olsson, Mats; Turbill, Chris; Verhulst, Simon; Zahn, Sandrine; Monaghan, Pat

    2014-01-01

    Telomeres play a fundamental role in the protection of chromosomal DNA and in the regulation of cellular senescence. Recent work in human epidemiology and evolutionary ecology suggests adult telomere length (TL) may reflect past physiological stress and predict subsequent morbidity and mortality, independent of chronological age. Several different methods have been developed to measure TL, each offering its own technical challenges. The aim of this review is to provide an overview of the advantages and drawbacks of each method for researchers, with a particular focus on issues that are likely to face ecologists and evolutionary biologists collecting samples in the field or in organisms that may never have been studied in this context before. We discuss the key issues to consider and wherever possible try to provide current consensus view regarding best practice with regard to sample collection and storage, DNA extraction and storage, and the five main methods currently available to measure TL. Decisions regarding which tissues to sample, how to store them, how to extract DNA, and which TL measurement method to use cannot be prescribed, and are dependent on the biological question addressed and the constraints imposed by the study system. What is essential for future studies of telomere dynamics in evolution and ecology is that researchers publish full details of their methods and the quality control thresholds they employ. PMID:25834722

  5. Socioeconomic Status, Financial Strain, and Leukocyte Telomere Length in a Sample of African American Midlife Men.

    PubMed

    Schrock, Joshua M; Adler, Nancy E; Epel, Elissa S; Nuru-Jeter, Amani M; Lin, Jue; Blackburn, Elizabeth H; Taylor, Robert Joseph; Chae, David H

    2018-06-01

    African American men in the USA experience poorer aging-related health outcomes compared to their White counterparts, partially due to socioeconomic disparities along racial lines. Greater exposure to socioeconomic strains among African American men may adversely impact health and aging at the cellular level, as indexed by shorter leukocyte telomere length (LTL). This study examined associations between socioeconomic factors and LTL among African American men in midlife, a life course stage when heterogeneity in both health and socioeconomic status are particularly pronounced. Using multinomial logistic regression, we examined associations between multiple measures of SES and tertiles of LTL in a sample of 92 African American men between 30 to 50 years of age. Reports of greater financial strain were associated with higher odds of short versus medium LTL (odds ratio (OR)=2.21, p = 0.03). Higher income was associated with lower odds of short versus medium telomeres (OR=0.97, p = 0.04). Exploratory analyses revealed a significant interaction between educational attainment and employment status (χ 2  = 4.07, p = 0.04), with greater education associated with lower odds of short versus long telomeres only among those not employed (OR=0.10, p = 0.040). Cellular aging associated with multiple dimensions of socioeconomic adversity may contribute to poor aging-related health outcomes among African American men. Subjective appraisal of financial difficulty may impact LTL independently of objective dimensions of SES. Self-appraised success in fulfilling traditionally masculine gender roles, including being an economic provider, may be a particularly salient aspect of identity for African American men and have implications for cellular aging in this population.

  6. Unraveling secrets of telomeres: one molecule at a time

    PubMed Central

    Lin, Jiangguo; Kaur, Parminder; Countryman, Preston; Opresko, Patricia L.; Wang, Hong

    2016-01-01

    Telomeres play important roles in maintaining the stability of linear chromosomes. Telomere maintenance involves dynamic actions of multiple proteins interacting with long repetitive sequences and complex dynamic DNA structures, such as G-quadruplexes, T-loops and t-circles. Given the heterogeneity and complexity of telomeres, single-molecule approaches are essential to fully understand the structure-function relationships that govern telomere maintenance. In this review, we present a brief overview of the principles of single-molecule imaging and manipulation techniques. We then highlight results obtained from applying these single-molecule techniques for studying structure, dynamics and functions of G-quadruplexes, telomerase, and shelterin proteins. PMID:24569170

  7. The Huntington disease locus is most likely within 325 kilobases of the chromosome 4p telomere

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Doggett, N.A.; Cheng, J.F.; Smith, C.L.

    1989-12-01

    The genetic defect responsible for Huntington disease was originally localized near the tip of the short arm of chromosome 4 by genetic linkage to the locus D4S10. Several markers closer to Huntington disease have since been isolated, but these all appear to be proximal to the defect. A physical map that extends from the most distal of these loci, D4S90, to the telomere of chromosome 4 was constructed. This map identifies at least two CpG islands as markers for Huntington disease candidate genes and places the most likely location of the Huntington disease defect remarkably close (within 325 kilobases) tomore » the telomere.« less

  8. Alternative Lengthening of Telomeres Mediated by Mitotic DNA Synthesis Engages Break-Induced Replication Processes

    PubMed Central

    Min, Jaewon; Wright, Woodring E.

    2017-01-01

    ABSTRACT Alternative lengthening of telomeres (ALT) is a telomerase-independent telomere maintenance mechanism that occurs in a subset of cancers. By analyzing telomerase-positive cells and their human TERC knockout-derived ALT human cell lines, we show that ALT cells harbor more fragile telomeres representing telomere replication problems. ALT-associated replication defects trigger mitotic DNA synthesis (MiDAS) at telomeres in a RAD52-dependent, but RAD51-independent, manner. Telomeric MiDAS is a conservative DNA synthesis process, potentially mediated by break-induced replication, similar to type II ALT survivors in Saccharomyces cerevisiae. Replication stresses induced by ectopic oncogenic expression of cyclin E, G-quadruplexes, or R-loop formation facilitate the ALT pathway and lead to telomere clustering, a hallmark of ALT cancers. The TIMELESS/TIPIN complex suppresses telomere clustering and telomeric MiDAS, whereas the SMC5/6 complex promotes them. In summary, ALT cells exhibit more telomere replication defects that result in persistent DNA damage responses at telomeres, leading to the engagement of telomeric MiDAS (spontaneous mitotic telomere synthesis) that is triggered by DNA replication stress, a potential driver of genomic duplications in cancer. PMID:28760773

  9. Telomere length profiles in primary human peritoneal mesothelial cells are consistent with senescence.

    PubMed

    Lopez-Anton, Melisa; Rudolf, András; Baird, Duncan M; Roger, Laureline; Jones, Rhiannon E; Witowski, Janusz; Fraser, Donald J; Bowen, Timothy

    2017-06-01

    Mesothelial cell (MC) senescence contributes to malignancy and tissue fibrosis. The role of telomere erosion in MC senescence remains controversial, with evidence for both telomere-dependent and telomere-independent mechanisms reported. Single telomere length analysis revealed considerable telomere length heterogeneity in freshly isolated human peritoneal MCs, reflecting a heterogeneous proliferative history and providing high-resolution evidence for telomere-dependent senescence. By contrast the attenuated replicative lifespan, lack of telomere erosion and induction of p16 expression in in vitro-aged cells was consistent with stress-induced senescence. Given the potential pathophysiological impact of senescence in mesothelial tissues, high-resolution MC telomere length analysis may provide clinically useful information. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  10. Telomere Length, Proviral Load and Neurologic Impairment in HTLV-1 and HTLV-2-Infected Subjects.

    PubMed

    Usadi, Benjamin; Bruhn, Roberta; Lin, Jue; Lee, Tzong-Hae; Blackburn, Elizabeth; Murphy, Edward L

    2016-08-11

    Short or damaged telomeres have been implicated in degenerative conditions. We hypothesized that analysis of telomere length (TL) in human T-cell lymphotropic virus (HTLV) infection and HTLV-associated neuropathy might provide clues to the etiology of HTLV-associated disease and viral dynamics. A subset of 45 human T-cell lymphotropic virus type 1 (HTLV-1), 45 human T-cell lymphotropic virus type 2 (HTLV-2), and 45 seronegative subjects was selected from the larger HTLV Outcomes Study (HOST) cohort, matched on age, sex and race/ethnicity. Telomere-to-single-copy gene (T/S) ratio (a measure of TL) and HTLV-1 and HTLV-2 proviral loads were measured in peripheral blood mononuclear cells (PBMCs) using quantitative PCR (qPCR). Vibration sensation measured by tuning fork during neurologic examinations performed as part of the HOST study allowed for an assessment of peripheral neuropathy. TL was compared between groups using t-tests, linear and logistic regression. Mean T/S ratio was 1.02 ± 0.16 in HTLV-1, 1.03 ± 0.17 in HTLV-2 and 0.99 ± 0.18 in HTLV seronegative subjects (p = 0.322). TL was not associated with HTLV-1 or -2 proviral load. Shorter TL was significantly associated with impaired vibration sense in the HTLV-2 positive group only. Overall, we found no evidence that telomere length was affected by chronic HTLV-1 and HTLV-2 infection. That TL was only associated with peripheral neuropathy in the HTLV-2-positive group is intriguing, but should be interpreted cautiously. Studies with larger sample size and telomere length measurement in lymphocyte subsets may clarify the relationship between TL and HTLV-infection.

  11. Tiptoeing to chromosome tips: facts, promises and perils of today's human telomere biology.

    PubMed

    Fajkus, J; Simícková, M; Maláska, J

    2002-04-29

    The past decade has witnessed an explosion of knowledge concerning the structure and function of chromosome terminal structures-telomeres. Today's telomere research has advanced from a pure descriptive approach of DNA and protein components to an elementary understanding of telomere metabolism, and now to promising applications in medicine. These applications include 'passive' ones, among which the use of analysis of telomeres and telomerase (a cellular reverse transcriptase that synthesizes telomeres) for cancer diagnostics is the best known. The 'active' applications involve targeted downregulation or upregulation of telomere synthesis, either to mortalize immortal cancer cells, or to rejuvenate mortal somatic cells and tissues for cellular transplantations, respectively. This article reviews the basic data on structure and function of human telomeres and telomerase, as well as both passive and active applications of human telomere biology.

  12. Alternative lengthening of telomeres can be maintained by preferential elongation of lagging strands

    PubMed Central

    Min, Jaewon; Wright, Woodring E.

    2017-01-01

    Abstract Alternative lengthening of telomeres (ALT) is a telomerase independent telomere maintenance mechanism that occurs in ∼15% of cancers. The potential mechanism of ALT is homology-directed telomere synthesis, but molecular mechanisms of how ALT maintains telomere length in human cancer is poorly understood. Here, we generated TERC (telomerase RNA) gene knockouts in telomerase positive cell lines that resulted in long-term surviving clones acquiring the ALT pathway but at a very low frequency. By comparing these ALT cells with parental telomerase positive cells, we observed that ALT cells possess excessively long telomeric overhangs derived from telomere elongation processes that mostly occur during S phase. ALT cells exhibited preferential elongation of the telomeric lagging strands, whereas telomerase positive cells exhibited similar elongation between leading and lagging strands. We propose that the ALT pathway preferentially occurs at telomeric lagging strands leading to heterogeneous telomere lengths observed in most ALT cancers. PMID:28082393

  13. Telomere maintenance in liquid crystalline chromosomes of dinoflagellates.

    PubMed

    Fojtová, Miloslava; Wong, Joseph T Y; Dvorácková, Martina; Yan, Kosmo T H; Sýkorová, Eva; Fajkus, Jirí

    2010-10-01

    The organisation of dinoflagellate chromosomes is exceptional among eukaryotes. Their genomes are the largest in the Eukarya domain, chromosomes lack histones and may exist in liquid crystalline state. Therefore, the study of the structural and functional properties of dinoflagellate chromosomes is of high interest. In this work, we have analysed the telomeres and telomerase in two Dinoflagellata species, Karenia papilionacea and Crypthecodinium cohnii. Active telomerase, synthesising exclusively Arabidopsis-type telomere sequences, was detected in cell extracts. The terminal position of TTTAGGG repeats was determined by in situ hybridisation and BAL31 digestion methods and provides evidence for the linear characteristic of dinoflagellate chromosomes. The length of telomeric tracts, 25-80 kb, is the largest among unicellular eukaryotic organisms to date. Both the presence of long arrays of perfect telomeric repeats at the ends of dinoflagellate chromosomes and the existence of active telomerase as the primary tool for their high-fidelity maintenance demonstrate the general importance of these structures throughout eukaryotes. We conclude that whilst chromosomes of dinoflagellates are unique in many aspects of their structure and composition, their telomere maintenance follows the most common scenario.

  14. Ectothermic telomeres: it's time they came in from the cold.

    PubMed

    Olsson, Mats; Wapstra, Erik; Friesen, Christopher

    2018-03-05

    We review the evolutionary ecology and genetics of telomeres in taxa that cannot elevate their body temperature to a preferred level through metabolism but do so by basking or seeking out a warm environment. This group of organisms contains all living things on earth, apart from birds and mammals. One reason for our interest in this synthetic group is the argument that high, stable body temperature increases the risk of malignant tumours if long, telomerase-restored telomeres make cells 'live forever'. If this holds true, ectotherms should have significantly lower cancer frequencies. We discuss to what degree there is support for this 'anti-cancer' hypothesis in the current literature. Importantly, we suggest that ectothermic taxa, with variation in somatic telomerase expression across tissue and taxa, may hold the key to understanding ongoing selection and evolution of telomerase dynamics in the wild. We further review endotherm-specific effects of growth on telomeres, effects of autotomy ('tail dropping') on telomere attrition, and costs of maintaining sexual displays measured in telomere attrition. Finally, we cover plant ectotherm telomeres and life histories in a separate 'mini review'.This article is part of the theme issue 'Understanding diversity in telomere dynamics'. © 2018 The Authors.

  15. RTEL1 contributes to DNA replication and repair and telomere maintenance.

    PubMed

    Uringa, Evert-Jan; Lisaingo, Kathleen; Pickett, Hilda A; Brind'Amour, Julie; Rohde, Jan-Hendrik; Zelensky, Alex; Essers, Jeroen; Lansdorp, Peter M

    2012-07-01

    Telomere maintenance and DNA repair are important processes that protect the genome against instability. mRtel1, an essential helicase, is a dominant factor setting telomere length in mice. In addition, mRtel1 is involved in DNA double-strand break repair. The role of mRtel1 in telomere maintenance and genome stability is poorly understood. Therefore we used mRtel1-deficient mouse embryonic stem cells to examine the function of mRtel1 in replication, DNA repair, recombination, and telomere maintenance. mRtel1-deficient mouse embryonic stem cells showed sensitivity to a range of DNA-damaging agents, highlighting its role in replication and genome maintenance. Deletion of mRtel1 increased the frequency of sister chromatid exchange events and suppressed gene replacement, demonstrating the involvement of the protein in homologous recombination. mRtel1 localized transiently at telomeres and is needed for efficient telomere replication. Of interest, in the absence of mRtel1, telomeres in embryonic stem cells appeared relatively stable in length, suggesting that mRtel1 is required to allow extension by telomerase. We propose that mRtel1 is a key protein for DNA replication, recombination, and repair and efficient elongation of telomeres by telomerase.

  16. Computing the Length of the Shortest Telomere in the Nucleus

    NASA Astrophysics Data System (ADS)

    Dao Duc, K.; Holcman, D.

    2013-11-01

    The telomere length can either be shortened or elongated by an enzyme called telomerase after each cell division. Interestingly, the shortest telomere is involved in controlling the ability of a cell to divide. Yet, its dynamics remains elusive. We present here a stochastic approach where we model this dynamics using a Markov jump process. We solve the forward Fokker-Planck equation to obtain the steady state distribution and the statistical moments of telomere lengths. We focus specifically on the shortest one and we estimate its length difference with the second shortest telomere. After extracting key parameters such as elongation and shortening dynamics from experimental data, we compute the length of telomeres in yeast and obtain as a possible prediction the minimum concentration of telomerase required to ensure a proper cell division.

  17. Short Telomere Length is Associated with Aging, Central Obesity, Poor Sleep and Hypertension in Lebanese Individuals

    PubMed Central

    Zgheib, Nathalie K; Sleiman, Fatima; Nasreddine, Lara; Nasrallah, Mona; Nakhoul, Nancy; Isma’eel, Hussain; Tamim, Hani

    2018-01-01

    In Lebanon, data stemming from national cross-sectional surveys indicated significant increasing trends in the prevalence of cardiovascular diseases and associated behavioral and age-related risk factors. To our knowledge, no data are available on relative telomere length (RTL) as a potential biomarker for age-related diseases in a Lebanese population. The aim of this study was to evaluate whether there is an association between RTL and demographic characteristics, lifestyle habits and diseases in the Lebanese. This was a cross-sectional study of 497 Lebanese subjects. Peripheral blood RTL was measured by amplifying telomere and single copy gene using real-time PCR. Mean ± SD RTL was 1.42 ± 0.83, and it was categorized into 3 tertiles. Older age (P=0.002) and wider waist circumference (WC) (P=0.001) were statistically significantly associated with shorter RTL. Multinomial logistic regression showed that subjects who had some level of sleeping difficulty had a statistically significantly shorter RTL when compared to those with no sleeping difficulties at all [OR (95% CI): 2.01 (1.11-3.62) in the first RTL tertile]. Importantly, statistically significantly shorter RTL was found with every additional 10 cm of WC [OR (95% CI): 1.30 (1.11-1.52) for first RTL tertile]. In addition, and after performing the multivariate logistic regression and adjusting for “predictors” of RTL, the odds of having hypertension or being treated for hypertension were higher in patients who had shorter RTL: OR (95% CI): 2.45 (1.36-4.44) and 2.28 (1.22-4.26) in the first RTL tertiles respectively with a similar trend, though not statistically significant, in the second RTL tertiles. This is the first study in Lebanon to show an association between age, central obesity, poor sleep and hypertension and RTL. It is hoped that telomere length measurement be potentially used as a biomarker for biological age and age-related diseases and progression in the Lebanese. PMID:29392083

  18. Short stature, unusual face, delta phalanx, and abnormal vertebrae and ribs in a girl born to half-siblings.

    PubMed

    Pogue, Robert; Marques, Felipe A; Kopacek, Cristiane; Rosa, Rosana C M; Dorfman, Luiza E; Mazzeu, Juliana F; Flores, José A M; Zen, Paulo R G; Rosa, Rafael F M

    2017-05-01

    Delta phalanx is a rare abnormality typically associated with additional features. We describe a patient with a phenotype resembling Catel-Manzke syndrome, but with delta phalanx and abnormal vertebrae and ribs. The patient was the only child of half siblings born with a marked prenatal growth deficiency. At 10 years of age, she had a short stature, long face, long and tubular nose with small alae nasi, high palate, short and broad thorax, and short index fingers with radial deviation. There were hyperpigmentations following Blaschko's lines. Radiology showed a proximal delta phalanx in the index finger of hands, abnormal vertebrae, and fused and small ribs. GTG-Banding karyotype and microarray analysis yielded normal results. Exome sequencing identified 25 genes that harbored homozygous variants, but none of these is assumed to be a good candidate to explain (part of) the phenotype. The here described patient may have a new condition, possibly following an autosomal recessive pattern of inheritance, although due to the high degree of consanguinity a compound etiology of the phenotype by variants in various genes may be present as well. © 2017 Wiley Periodicals, Inc.

  19. Placental telomere shortening in stillbirth: a sign of premature senescence?

    PubMed

    Ferrari, Francesca; Facchinetti, Fabio; Saade, George; Menon, Ramkumar

    2016-01-01

    The objective of this study is to investigate placental telomere shortening in unexplained stillbirths (SBs) as an indication of premature senescence. Placentas were collected from 42 unexplained SB (>22 weeks), 43 term and 15 preterm live births, at the Policlinico Hospital of Modena (Italy). DNA extracted from placentae was studied for telomere length by real time PCR. Standard curves were generated for telomere lengths from single copy gene amplifications using a reference DNA. The telomere length for each sample was derived based on the ratio of telomere length between the sample and single copy gene standard (T/S ratio). The mean ratio of placental telomere in term live births was 5.181 ± 3.841. A twofold decrease in telomere length was seen in SBs (over all 2.455 ± 1.239; p < 0.001). For early SBs (above 34 weeks), the T/S was 2.8884 ± 1.224 and for late SBs, the T/S was 2.207 ± 1.201, both lower than term live births (both p < 0.01). T/S remained lower both in small for gestational age-SB (2.639 ± 1.619) and appropriate for gestational age-SB (2.653 ± 1.335) with no difference between these subgroups (p = ns). T/S was lower in SB compared with spontaneous preterm births (PTBs) (6.382 ± 5.525; p < 0.01), whereas SBs telomere length were similar to those of preterm premature rupture of membranes (pPROM) (3.296 ± 3.599; p = ns). Substantial reduction in telomere length in SBs is indicative of placental senescence. These data provide mechanistic insights that premature aging may lead to placental dysfunction as an initiator of fetal demise in unexplained SBs.

  20. Evaluation of telomere length in human cardiac tissues using cardiac quantitative FISH.

    PubMed

    Sharifi-Sanjani, Maryam; Meeker, Alan K; Mourkioti, Foteini

    2017-09-01

    Telomere length has been correlated with various diseases, including cardiovascular disease and cancer. The use of currently available telomere-length measurement techniques is often restricted by the requirement of a large amount of cells (Southern-based techniques) or the lack of information on individual cells or telomeres (PCR-based methods). Although several methods have been used to measure telomere length in tissues as a whole, the assessment of cell-type-specific telomere length provides valuable information on individual cell types. The development of fluorescence in situ hybridization (FISH) technologies enables the quantification of telomeres in individual chromosomes, but the use of these methods is dependent on the availability of isolated cells, which prevents their use with fixed archival samples. Here we describe an optimized quantitative FISH (Q-FISH) protocol for measuring telomere length that bypasses the previous limitations by avoiding contributions from undesired cell types. We have used this protocol on small paraffin-embedded cardiac-tissue samples. This protocol describes step-by-step procedures for tissue preparation, permeabilization, cardiac-tissue pretreatment and hybridization with a Cy3-labeled telomeric repeat complementing (CCCTAA) 3 peptide nucleic acid (PNA) probe coupled with cardiac-specific antibody staining. We also describe how to quantify telomere length by means of the fluorescence intensity and area of each telomere within individual nuclei. This protocol provides comparative cell-type-specific telomere-length measurements in relatively small human cardiac samples and offers an attractive technique to test hypotheses implicating telomere length in various cardiac pathologies. The current protocol (from tissue collection to image procurement) takes ∼28 h along with three overnight incubations. We anticipate that the protocol could be easily adapted for use on different tissue types.

  1. Nucleostemin inhibits TRF1 dimerization and shortens its dynamic association with the telomere

    PubMed Central

    Meng, Lingjun; Hsu, Joseph K.; Zhu, Qubo; Lin, Tao; Tsai, Robert Y. L.

    2011-01-01

    TRF1 is a key component of the telomere-capping complex and binds double-strand telomeric DNA as homodimers. So far, it is not clear whether TRF1 dimerization coincides with its telomere binding or is actively controlled before it binds the telomere, and in the latter case, how this event might affect its telomere association. We previously found that TRF1 dimerization and its telomere binding can be increased by GNL3L, which is the vertebrate paralogue of nucleostemin (NS). Here, we show that NS and GNL3L bind TRF1 directly but competitively through two separate domains of TRF1. In contrast to GNL3L, NS prevents TRF1 dimerization through a mechanism not determined by its ability to displace TRF1-bound GNL3L. Furthermore, NS is capable of shortening the dynamic association of TRF1 with the telomere in normal and TRF2ΔBΔM-induced telomere-damaged cells without affecting the amount of telomere-bound TRF1 proteins in vivo. Importantly, NS displays a protective function against the formation of telomere-dysfunction-induced foci. This work demonstrates that TRF1 dimerization is actively and oppositely regulated by NS and GNL3L extrachromosomally. Changing the relative amount of TRF1 monomers versus dimers in the nucleoplasm might affect the dynamic association of TRF1 with the telomere and the repair of damaged telomeres. PMID:22045740

  2. Disappearance of the telomere dysfunction-induced stress response in fully senescent cells.

    PubMed

    Bakkenist, Christopher J; Drissi, Rachid; Wu, Jing; Kastan, Michael B; Dome, Jeffrey S

    2004-06-01

    Replicative senescence is a natural barrier to cellular proliferation that is triggered by telomere erosion and dysfunction. Here, we demonstrate that ATM activation and H2AX-gamma nuclear focus formation are sensitive markers of telomere dysfunction in primary human fibroblasts. Whereas the activated form of ATM and H2AX-gamma foci were rarely observed in early-passage cells, they were readily detected in late-passage cells. The ectopic expression of telomerase in late-passage cells abrogated ATM activation and H2AX-gamma focus formation, suggesting that these stress responses were the consequence of telomere dysfunction. ATM activation was induced in quiescent fibroblasts by inhibition of TRF2 binding to telomeres, indicating that telomere uncapping is sufficient to initiate the telomere signaling response; breakage of chromosomes with telomeric associations is not required for this activation. Although ATM activation and H2AX-gamma foci were readily observed in late-passage cells, they disappeared once cells became fully senescent, indicating that constitutive signaling from dysfunctional telomeres is not required for the maintenance of senescence.

  3. Getting in (and out of) the loop: regulating higher order telomere structures.

    PubMed

    Luke-Glaser, Sarah; Poschke, Heiko; Luke, Brian

    2012-01-01

    The DNA at the ends of linear chromosomes (the telomere) folds back onto itself and forms an intramolecular lariat-like structure. Although the telomere loop has been implicated in the protection of chromosome ends from nuclease-mediated resection and unscheduled DNA repair activities, it potentially poses an obstacle to the DNA replication machinery during S-phase. Therefore, the coordinated regulation of telomere loop formation, maintenance, and resolution is required in order to establish a balance between protecting the chromosome ends and promoting their duplication prior to cell division. Until recently, the only factor known to influence telomere looping in human cells was TRF2, a component of the shelterin complex. Recent work in yeast and mouse cells has uncovered additional regulatory factors that affect the loop structure at telomeres. In the following "perspective" we outline what is known about telomere looping and highlight the latest results regarding the regulation of this chromosome end structure. We speculate about how the manipulation of the telomere loop may have therapeutic implications in terms of diseases associated with telomere dysfunction and uncontrolled proliferation.

  4. Telomere length of the colonial coral Galaxea fascicularis at different developmental stages

    NASA Astrophysics Data System (ADS)

    Tsuta, H.; Hidaka, M.

    2013-06-01

    The ability to estimate coral age using soft tissue would be useful for population biology or aging studies on corals. In this study, we investigated whether telomere length can be used to estimate coral age. We applied single telomere length analysis to a colonial coral, Galaxea fascicularis, and estimated telomere lengths of specific coral chromosomes at different developmental stages. If the telomere shortened at each cell division, the telomere length of the coral would be longest in sperm and shortest in adult colonies. However, the mean telomere length of sperm, planula larvae, and polyps was approximately 4 kb, with no significant differences among the developmental stages. The telomerase restriction fragment (TRF) analysis also showed no significant difference in the mean TRF length among the developmental stages. Our results suggested that telomere length is maintained during developmental stages and that estimating the age of colonial coral based on telomere length may not be possible. However, our findings can be used to examine avoidance of aging and rejuvenation during regeneration and asexual reproduction in colonial corals.

  5. Developmental telomere attrition predicts impulsive decision-making in adult starlings

    PubMed Central

    Bateson, Melissa; Brilot, Ben O.; Gillespie, Robert; Monaghan, Pat; Nettle, Daniel

    2015-01-01

    Animals in a poor biological state face reduced life expectancy, and as a consequence should make decisions that prioritize immediate survival and reproduction over long-term benefits. We tested the prediction that if, as has been suggested, developmental telomere attrition is a biomarker of state and future life expectancy, then individuals who have undergone greater developmental telomere attrition should display greater choice impulsivity as adults. We measured impulsive decision-making in a cohort of European starlings (Sturnus vulgaris) in which we had previously manipulated developmental telomere attrition by cross-fostering sibling chicks into broods of different sizes. We show that as predicted by state-dependent optimality models, individuals who had sustained greater developmental telomere attrition and who had shorter current telomeres made more impulsive foraging decisions as adults, valuing smaller, sooner food rewards more highly than birds with less attrition and longer telomeres. Our findings shed light on the biological embedding of early adversity and support a functional explanation for its consequences that could be applicable to other species, including humans. PMID:25473012

  6. ATLAS: An advanced PCR-method for routine visualization of telomere length in Saccharomyces cerevisiae.

    PubMed

    Zubko, Elena I; Shackleton, Jennifer L; Zubko, Mikhajlo K

    2016-12-01

    Measuring telomere length is essential in telomere biology. Southern blot hybridization is the predominant method for measuring telomere length in the genetic model Saccharomyces cerevisiae. We have further developed and refined a telomere PCR approach, which was rarely used previously (mainly in specific telomeric projects), into a robust method allowing direct visualisation of telomere length differences in routine experiments with S. cerevisiae, and showing a strong correlation of results with data obtained by Southern blot hybridization. In this expanded method denoted as ATLAS (A-dvanced T-elomere L-ength A-nalysis in S. cerevisiae), we have introduced: 1) set of new primers annealing with high specificity to telomeric regions on five different chromosomes; 2) new approach for designing reverse telomere primers that is based on the ligation of an adaptor of a fixed size to telomeric ends. ATLAS can be used at the scale of individual assays and high-throughput approaches. This simple, time/cost-effective and reproducible methodology will complement Southern blot hybridization and facilitate further progress in telomere research. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Telomeres shorten and then lengthen before fledging in Magellanic penguins (Spheniscus magellanicus)

    PubMed Central

    Cerchiara, Jack A.; Risques, Rosa Ana; Prunkard, Donna; Smith, Jeffrey R.; Kane, Olivia J.; Dee Boersma, P.

    2017-01-01

    For all species, finite metabolic resources must be allocated toward three competing systems: maintenance, reproduction, and growth. Telomeres, the nucleoprotein tips of chromosomes, which shorten with age in most species, are correlated with increased survival. Chick growth is energetically costly and is associated with telomere shortening in most species. To assess the change in telomeres in penguin chicks, we quantified change in telomere length of wild known-age Magellanic penguin (Spheniscus magellanicus) chicks every 15 days during the species’ growth period, from hatching to 60 days-of-age. Magellanic penguins continue to grow after fledging so we also sampled a set of 1-year-old juvenile penguins, and adults aged 5 years. Telomeres were significantly shorter on day 15 than on hatch day but returned to their initial length by 30 days old and remained at that length through 60 days of age. The length of telomeres of newly hatched chicks, chicks aged 30, 45 and 60 days, juveniles, and adults aged 5 years were similar. Chicks that fledged and those that died had similar telomere lengths. We show that while telomeres shorten during growth, Magellanic penguins elongate telomeres to their length at hatch, which may increase adult life span and reproductive opportunities. PMID:28186493

  8. Stress and telomere shortening among central Indian conservation refugees.

    PubMed

    Zahran, Sammy; Snodgrass, Jeffrey G; Maranon, David G; Upadhyay, Chakrapani; Granger, Douglas A; Bailey, Susan M

    2015-03-03

    Research links psychosocial stress to premature telomere shortening and accelerated human aging; however, this association has only been demonstrated in so-called "WEIRD" societies (Western, educated, industrialized, rich, and democratic), where stress is typically lower and life expectancies longer. By contrast, we examine stress and telomere shortening in a non-Western setting among a highly stressed population with overall lower life expectancies: poor indigenous people--the Sahariya--who were displaced (between 1998 and 2002) from their ancestral homes in a central Indian wildlife sanctuary. In this setting, we examined adult populations in two representative villages, one relocated to accommodate the introduction of Asiatic lions into the sanctuary (n = 24 individuals), and the other newly isolated in the sanctuary buffer zone after their previous neighbors were moved (n = 22). Our research strategy combined physical stress measures via the salivary analytes cortisol and α-amylase with self-assessments of psychosomatic stress, ethnographic observations, and telomere length assessment [telomere-fluorescence in situ hybridization (TEL-FISH) coupled with 3D imaging of buccal cell nuclei], providing high-resolution data amenable to multilevel statistical analysis. Consistent with expectations, we found significant associations between each of our stress measures--the two salivary analytes and the psychosomatic symptom survey--and telomere length, after adjusting for relevant behavioral, health, and demographic traits. As the first study (to our knowledge) to link stress to telomere length in a non-WEIRD population, our research strengthens the case for stress-induced telomere shortening as a pancultural biomarker of compromised health and aging.

  9. Pathways connecting telomeres and p53 in senescence, apoptosis, and cancer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Artandi, Steven E.; Attardi, Laura D.

    2005-06-10

    The ends of eukaryotic chromosomes are protected by specialized structures termed telomeres that serve in part to prevent the chromosome end from activating a DNA damage response. However, this important function for telomeres in chromosome end protection can be lost as telomeres shorten with cell division in culture or in self-renewing tissues with advancing age. Impaired telomere function leads to induction of a DNA damage response and activation of the tumor suppressor protein p53. p53 serves a critical role in enforcing both senescence and apoptotic responses to dysfunctional telomeres. Loss of p53 creates a permissive environment in which critically shortmore » telomeres are inappropriately joined to generate chromosomal end-to-end fusions. These fused chromosomes result in cycles of chromosome fusion-bridge-breakage, which can fuel cancer initiation, especially in epithelial tissues, by facilitating changes in gene copy number.« less

  10. Hybrid ligand-alkylating agents targeting telomeric G-quadruplex structures.

    PubMed

    Doria, Filippo; Nadai, Matteo; Folini, Marco; Di Antonio, Marco; Germani, Luca; Percivalle, Claudia; Sissi, Claudia; Zaffaroni, Nadia; Alcaro, Stefano; Artese, Anna; Richter, Sara N; Freccero, Mauro

    2012-04-14

    The synthesis, physico-chemical properties and biological effects of a new class of naphthalene diimides (NDIs) capable of reversibly binding telomeric DNA and alkylate it through an electrophilic quinone methide moiety (QM), are reported. FRET and circular dichroism assays showed a marked stabilization and selectivity towards telomeric G4 DNA folded in a hybrid topology. NDI-QMs' alkylating properties revealed a good reactivity on single nucleosides and selectivity towards telomeric G4. A selected NDI was able to significantly impair the growth of melanoma cells by causing telomere dysfunction and down-regulation of telomerase expression. These findings points to our hybrid ligand-alkylating NDIs as possible tools for the development of novel targeted anticancer therapies. This journal is © The Royal Society of Chemistry 2012

  11. Relationship between leukocyte telomere length and personality traits in healthy subjects.

    PubMed

    Sadahiro, R; Suzuki, A; Enokido, M; Matsumoto, Y; Shibuya, N; Kamata, M; Goto, K; Otani, K

    2015-02-01

    It has been shown that certain personality traits are related to mortality and disease morbidity, but the biological mechanism linking them remains unclear. Telomeres are tandem repeat DNA sequences located at the ends of chromosomes, and shorter telomere length is a predictor of mortality and late-life disease morbidity. Thus, it is possible that personality traits influence telomere length. In the present study, we examined the relationship of leukocyte telomere length with personality traits in healthy subjects. The subjects were 209 unrelated healthy Japanese who were recruited from medical students at 4th-5th grade. Assessment of personality traits was performed by the Revised NEO Personality Inventory (NEO-PI-R) and the Temperament and Character Inventory (TCI). Leukocyte relative telomere length was determined by a quantitative real-time PCR method for a ratio of telomere/single copy gene. In the stepwise multiple regression analysis, shorter telomere length was related to lower scores of neuroticism (P<0.01) and conscientiousness (P<0.05) of the NEO-PI-R, and lower scores of harm avoidance (P<0.05) and reward dependence (P<0.05) of the TCI. The present study suggests that leukocyte telomere length is associated with some personality traits, and this association may be implicated in the relationship between personality traits and mortality. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  12. Glyceraldehyde 3-phosphate dehydrogenase-telomere association correlates with redox status in Trypanosoma cruzi.

    PubMed

    Pariona-Llanos, Ricardo; Pavani, Raphael Souza; Reis, Marcelo; Noël, Vincent; Silber, Ariel Mariano; Armelin, Hugo Aguirre; Cano, Maria Isabel Nogueira; Elias, Maria Carolina

    2015-01-01

    Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a classical metabolic enzyme involved in energy production and plays a role in additional nuclear functions, including transcriptional control, recognition of misincorporated nucleotides in DNA and maintenance of telomere structure. Here, we show that the recombinant protein T. cruzi GAPDH (rTcGAPDH) binds single-stranded telomeric DNA. We demonstrate that the binding of GAPDH to telomeric DNA correlates with the balance between oxidized and reduced forms of nicotinamide adenine dinucleotides (NAD+/NADH). We observed that GAPDH-telomere association and NAD+/NADH balance changed throughout the T. cruzi life cycle. For example, in replicative epimastigote forms of T. cruzi, which show similar intracellular concentrations of NAD+ and NADH, GAPDH binds to telomeric DNA in vivo and this binding activity is inhibited by exogenous NAD+. In contrast, in the T. cruzi non-proliferative trypomastigote forms, which show higher NAD+ concentration, GAPDH was absent from telomeres. In addition, NAD+ abolishes physical interaction between recombinant GAPDH and synthetic telomere oligonucleotide in a cell free system, mimicking exogenous NAD+ that reduces GAPDH-telomere interaction in vivo. We propose that the balance in the NAD+/NADH ratio during T. cruzi life cycle homeostatically regulates GAPDH telomere association, suggesting that in trypanosomes redox status locally modulates GAPDH association with telomeric DNA.

  13. Glyceraldehyde 3-Phosphate Dehydrogenase-Telomere Association Correlates with Redox Status in Trypanosoma cruzi

    PubMed Central

    Pariona-Llanos, Ricardo; Pavani, Raphael Souza; Reis, Marcelo; Noël, Vincent; Silber, Ariel Mariano; Armelin, Hugo Aguirre; Cano, Maria Isabel Nogueira; Elias, Maria Carolina

    2015-01-01

    Glyceraldehyde 3-phosphate dehydrogenase (GAPDH) is a classical metabolic enzyme involved in energy production and plays a role in additional nuclear functions, including transcriptional control, recognition of misincorporated nucleotides in DNA and maintenance of telomere structure. Here, we show that the recombinant protein T. cruzi GAPDH (rTcGAPDH) binds single-stranded telomeric DNA. We demonstrate that the binding of GAPDH to telomeric DNA correlates with the balance between oxidized and reduced forms of nicotinamide adenine dinucleotides (NAD+/NADH). We observed that GAPDH-telomere association and NAD+/NADH balance changed throughout the T. cruzi life cycle. For example, in replicative epimastigote forms of T. cruzi, which show similar intracellular concentrations of NAD+ and NADH, GAPDH binds to telomeric DNA in vivo and this binding activity is inhibited by exogenous NAD+. In contrast, in the T. cruzi non-proliferative trypomastigote forms, which show higher NAD+ concentration, GAPDH was absent from telomeres. In addition, NAD+ abolishes physical interaction between recombinant GAPDH and synthetic telomere oligonucleotide in a cell free system, mimicking exogenous NAD+ that reduces GAPDH-telomere interaction in vivo. We propose that the balance in the NAD+/NADH ratio during T. cruzi life cycle homeostatically regulates GAPDH telomere association, suggesting that in trypanosomes redox status locally modulates GAPDH association with telomeric DNA. PMID:25775131

  14. Telomere extension by telomerase and ALT generates variant repeats by mechanistically distinct processes

    PubMed Central

    Lee, Michael; Hills, Mark; Conomos, Dimitri; Stutz, Michael D.; Dagg, Rebecca A.; Lau, Loretta M.S.; Reddel, Roger R.; Pickett, Hilda A.

    2014-01-01

    Telomeres are terminal repetitive DNA sequences on chromosomes, and are considered to comprise almost exclusively hexameric TTAGGG repeats. We have evaluated telomere sequence content in human cells using whole-genome sequencing followed by telomere read extraction in a panel of mortal cell strains and immortal cell lines. We identified a wide range of telomere variant repeats in human cells, and found evidence that variant repeats are generated by mechanistically distinct processes during telomerase- and ALT-mediated telomere lengthening. Telomerase-mediated telomere extension resulted in biased repeat synthesis of variant repeats that differed from the canonical sequence at positions 1 and 3, but not at positions 2, 4, 5 or 6. This indicates that telomerase is most likely an error-prone reverse transcriptase that misincorporates nucleotides at specific positions on the telomerase RNA template. In contrast, cell lines that use the ALT pathway contained a large range of variant repeats that varied greatly between lines. This is consistent with variant repeats spreading from proximal telomeric regions throughout telomeres in a stochastic manner by recombination-mediated templating of DNA synthesis. The presence of unexpectedly large numbers of variant repeats in cells utilizing either telomere maintenance mechanism suggests a conserved role for variant sequences at human telomeres. PMID:24225324

  15. Decoding telomere protein Rap1: Its telomeric and nontelomeric functions and potential implications in diabetic cardiomyopathy.

    PubMed

    Cai, Yin; Kandula, Vidya; Kosuru, Ramoji; Ye, Xiaodong; Irwin, Michael G; Xia, Zhengyuan

    2017-10-02

    Mammalian Rap1, the most conserved telomere-interacting protein, beyond its role within nucleus for the maintenance of telomeric functions, is also well known for its pleiotropic functions in various physiological and pathological conditions associated with metabolism, inflammation and oxidative stress. For all these, nowadays Rap1 is the subject of critical investigations aimed to unveil its molecular signaling pathways and to scrutinize the applicability of its modulation as a promising therapeutic strategy with clinical relevance. However, the underlying intimate mechanisms of Rap1 are not extensively studied, but any modulation of this protein level has been associated with pathologies like inflammation, oxidative stress and deregulated metabolism. This is considerably important in light of the recent discovery of Rap1 modulation in diseases like cancer and cardiac metabolic disorders. In this review, we focus on both the telomeric and nontelomeric functions of Rap1 and its modulation in various health risks, especially on the heart.

  16. No association between telomere length-related loci and number of cutaneous nevi.

    PubMed

    Li, Xin; Liang, Geyu; Du, Mengmeng; De Vivo, Immaculata; Nan, Hongmei

    2016-12-13

    Longer telomeres have been associated both with increased melanoma risk and increased nevus counts. Nevus count is one of the strongest risk factors for melanoma. Recent data showed that a genetic score derived by telomere length-related single nucleotide polymorphisms (SNPs) was strongly associated with melanoma risk; however, the relationships between these SNPs and number of cutaneous nevi have not been investigated. We evaluated the associations between telomere length-related SNPs reported by previous genome-wide association study (GWAS) and nevus counts among 15,955 participants of European Ancestry in the Nurses' Health Study and Health Professionals Follow-up Study. None of the SNPs was associated with nevus counts, nor was the genetic score combining the dosage of alleles related to increased telomere length. The telomere length-related SNPs identified by published GWAS do not appear to play an important role in nevus formation. Genetic determinants of telomere length reported by GWAS do not explain the observed epidemiologic association between telomere length and nevus counts.

  17. Time Lapse to Colorectal Cancer: Telomere Dynamics Define the Malignant Potential of Polyps.

    PubMed

    Druliner, Brooke R; Ruan, Xiaoyang; Johnson, Ruth; Grill, Diane; O'Brien, Daniel; Lai, Tsung-Po; Rashtak, Shahrooz; Felmlee-Devine, Donna; Washechek-Aletto, Jill; Malykh, Andrei; Smyrk, Thomas; Oberg, Ann; Liu, Hongfang; Shay, Jerry W; Ahlquist, David A; Boardman, Lisa A

    2016-09-01

    Whereas few adenomas become cancer, most colorectal cancers arise from adenomas. Telomere length is a recognized biomarker in multiple cancers, and telomere maintenance mechanisms (TMM) are exploited by malignant cells. We sought to determine whether telomere length and TMM distinguish cancer-associated adenomas from those that are cancer-free. Tissues were identified as cancer-adjacent polyp (CAP)-residual adenoma contiguous with cancer-and cancer-free polyp (CFP)-adenomas without malignancy. Telomere length, TMM, and expression were measured in 102 tissues including peripheral blood leukocytes (PBLs), normal colon epithelium, adenoma, and cancer (in CAP cases) from 31 patients. Telomere length was measured in a separate cohort of 342 PBL from CAP and CFP patients. The mean differences in telomere length between normal and adenoma were greater in CAP than in CFP cases, P=0.001; telomere length in PBL was 91.7 bp greater in CAP than in CFP, P=0.007. Each 100 bp telomere increase was associated with a 1.14 (1.04-1.26) increased odds of being a CAP, P=0.0063. The polyp tissue from CAP patients had shorter telomeres and higher Telomerase reverse transcriptase (hTERT) expression compared with polyps from CFP patients, P=0.05. There was a greater degree of alternative lengthening of telomere (ALT) level difference in CFP polyps than in CAP polyps. The polyp telomere lengths of aggressive CAPs were significantly different from the polyps of non-aggressive CAPs, P=0.01. Adenomas that progress to cancer exhibit distinct telomere length and TMM profiles. We report for the first time that PBL telomeres differ in patients with polyps that become malignant, and therefore may have clinical value in adenoma risk assessment and management.

  18. Telomeric attrition with age and temperature in Eastern mosquitofish ( Gambusia holbrooki)

    NASA Astrophysics Data System (ADS)

    Rollings, Nicky; Miller, Emily; Olsson, Mats

    2014-03-01

    Telomeric attrition has repeatedly been found to correlate with the ageing of organisms; however, recent research is increasingly showing that the determinants of attrition dynamics are not well understood. This study examined the relative telomere lengths in Eastern mosquitofish, Gambusia holbrooki, kept at different temperatures and at different ages. Newly born fry were randomly selected for one of four treatment groups: 20, 30, 20-30, and 30-20 °C, where the third and fourth treatment groups were gradually changed from their starting temperature to their final temperature between days 10 and 14. Telomere length was measured, and it was found that length decreased with age and that fish exposed to the 20 °C treatment had significantly shorter telomeres than those that received the 30-20 °C treatment. Telomeric attrition with age agrees with results previously found in studies of telomeres; however, the variation in attrition with temperature was not simply predictable and may be the synergistic effects of temperature and some other factor.

  19. Telomere Fragment Induced Amnion Cell Senescence: A Contributor to Parturition?

    PubMed Central

    Polettini, Jossimara; Behnia, Faranak; Taylor, Brandie D.; Saade, George R.; Taylor, Robert N.; Menon, Ramkumar

    2015-01-01

    Oxidative stress (OS)-induced senescence of the amniochorion has been associated with parturition at term. We investigated whether telomere fragments shed into the amniotic fluid (AF) correlated with labor status and tested if exogenous telomere fragments (T-oligos) could induce human and murine amnion cell senescence. In a cross-sectional clinical study, AF telomere fragment concentrations quantitated by a validated real-time PCR assay were higher in women in labor at term compared to those not in labor. In vitro treatment of primary human amnion epithelial cells with 40 μM T-oligos ([TTAGGG]2) that mimic telomere fragments, activated p38MAPK, produced senescence-associated (SA) β-gal staining and increased interleukin (IL)-6 and IL-8 production compared to cells treated with complementary DNA sequences (Cont-oligos, [AATCCC]2). T-oligos injected into the uteri of pregnant CD1 mice on day 14 of gestation, led to increased p38MAPK, SA-β-gal (SA β-gal) staining in murine amniotic sacs and higher AF IL-8 levels on day 18, compared to saline treated controls. In summary, term labor AF samples had higher telomere fragments than term not in labor AF. In vitro and in situ telomere fragments increased human and murine amnion p38MAPK, senescence and inflammatory cytokines. We propose that telomere fragments released from senescent fetal cells are indicative of fetal cell aging. Based on our data, these telomere fragments cause oxidative stress associated damages to the term amniotic sac and force them to release other DAMPS, which, in turn, provide a sterile immune response that may be one of the many inflammatory signals required to initiate parturition at term. PMID:26397719

  20. Association between kidney function and telomere length: the Heart and Soul Study

    PubMed Central

    Bansal, Nisha; Whooley, Mary A.; Regan, Mathilda; McCulloch, Charles E.; Ix, Joachim H.; Epel, Elissa; Blackburn, Elizabeth; Lin, Jue; Hsu, Chi-yuan

    2013-01-01

    Background Telomere attrition is a novel risk factor for cardiovascular disease. Studies of telomere length in relation to kidney function are limited. We explored the association of kidney function with telomere length and telomere shortening. Methods The Heart and Soul study is a longitudinal study of patients with stable coronary heart disease (CHD). Measures of baseline kidney function included: serum creatinine, creatinine-derived estimated glomerular filtration rate (eGFRCKD-EPI), 24-hour urine measured creatinine clearance, cystatin C, cystatin C-derived estimated glomerular filtration rate (eGFRcys) and urine albumin to creatinine ratio. Telomere length was measured from peripheral blood leukocytes at baseline (N=954) and 5 years later (N=608). Linear regression models were used to test the association of kidney function with i) baseline telomere length and ii) change in telomere length over 5 years. Results At baseline, mean eGFRCKD-EPI was 72.6 (± 21.5) ml/min/1.73 m2, eGFRcys was 71.0 (± 23.1) ml/min/1.73 m2 and ACR was 8.6 (±12.3) mg/gm. Only lower baseline eGFRCKD-EPI was associated with shorter baseline telomere length (9.1 [95% CI 1.2–16.9] fewer base pairs for every 5 ml/min/1.73 m2 lower eGFRCKD-EPI). Lower baseline eGFRCKD-EPI (and all other measures of kidney function) predicted more rapid telomere shortening (10.8 [95% CI 4.3–17.3] decrease in base pairs over 5 years for every 5 ml/min/1.73 m2 lower eGFRCKD-EPI). After adjustment for age, these associations were no longer statistically significant. Conclusions In patients with CHD, reduced kidney function is associated with i) shorter baseline telomere length and ii) more rapid telomere shortening over 5 years, however these associations are entirely explained by older age. PMID:23108000

  1. Sequential phosphorylation of CST subunits by different cyclin-Cdk1 complexes orchestrate telomere replication.

    PubMed

    Gopalakrishnan, Veena; Tan, Cherylin Ruiling; Li, Shang

    2017-07-03

    Telomeres are nucleoprotein structures that cap the ends of linear chromosomes. Telomere homeostasis is central to maintaining genomic integrity. In budding yeast, Cdk1 phosphorylates the telomere-specific binding protein, Cdc13, promoting the recruitment of telomerase to telomere and thereby telomere elongation. Cdc13 is also an integral part of the CST (Cdc13-Stn1-Ten1) complex that is essential for telomere capping and counteracting telomerase-dependent telomere elongation. Therefore, telomere length homeostasis is a balance between telomerase-extendable and CST-unextendable states. In our earlier work, we showed that Cdk1 also phosphorylates Stn1 which occurs sequentially following Cdc13 phosphorylation during cell cycle progression. This stabilizes the CST complex at the telomere and results in telomerase inhibition. Hence Cdk1-dependent phosphorylations of Stn1 acts like a molecular switch that drives Cdc13 to complex with Stn1-Ten1 rather than with telomerase. However, the underlying mechanism of how a single cyclin-dependent kinase phosphorylates Cdc13 and Stn1 in temporally distinct windows is largely unclear. Here, we show that S phase cyclins are necessary for telomere maintenance. The S phase and mitotic cyclins facilitate Cdc13 and Stn1 phosphorylation respectively, to exert opposing outcomes at the telomere. Thus, our results highlight a previously unappreciated role for cyclins in telomere replication.

  2. The roles of WRN and BLM RecQ helicases in the Alternative Lengthening of Telomeres

    PubMed Central

    Mendez-Bermudez, Aaron; Hidalgo-Bravo, Alberto; Cotton, Victoria E.; Gravani, Athanasia; Jeyapalan, Jennie N.; Royle, Nicola J.

    2012-01-01

    Approximately 10% of all cancers, but a higher proportion of sarcomas, use the recombination-based alternative lengthening of telomeres (ALT) to maintain telomeres. Two RecQ helicase genes, BLM and WRN, play important roles in homologous recombination repair and they have been implicated in telomeric recombination activity, but their precise roles in ALT are unclear. Using analysis of sequence variation present in human telomeres, we found that a WRN– ALT+ cell line lacks the class of complex telomere mutations attributed to inter-telomeric recombination in other ALT+ cell lines. This suggests that WRN facilitates inter-telomeric recombination when there are sequence differences between the donor and recipient molecules or that sister-telomere interactions are suppressed in the presence of WRN and this promotes inter-telomeric recombination. Depleting BLM in the WRN– ALT+ cell line increased the mutation frequency at telomeres and at the MS32 minisatellite, which is a marker of ALT. The absence of complex telomere mutations persisted in BLM-depleted clones, and there was a clear increase in sequence homogenization across the telomere and MS32 repeat arrays. These data indicate that BLM suppresses unequal sister chromatid interactions that result in excessive homogenization at MS32 and at telomeres in ALT+ cells. PMID:22989712

  3. The roles of WRN and BLM RecQ helicases in the Alternative Lengthening of Telomeres.

    PubMed

    Mendez-Bermudez, Aaron; Hidalgo-Bravo, Alberto; Cotton, Victoria E; Gravani, Athanasia; Jeyapalan, Jennie N; Royle, Nicola J

    2012-11-01

    Approximately 10% of all cancers, but a higher proportion of sarcomas, use the recombination-based alternative lengthening of telomeres (ALT) to maintain telomeres. Two RecQ helicase genes, BLM and WRN, play important roles in homologous recombination repair and they have been implicated in telomeric recombination activity, but their precise roles in ALT are unclear. Using analysis of sequence variation present in human telomeres, we found that a WRN- ALT+ cell line lacks the class of complex telomere mutations attributed to inter-telomeric recombination in other ALT+ cell lines. This suggests that WRN facilitates inter-telomeric recombination when there are sequence differences between the donor and recipient molecules or that sister-telomere interactions are suppressed in the presence of WRN and this promotes inter-telomeric recombination. Depleting BLM in the WRN- ALT+ cell line increased the mutation frequency at telomeres and at the MS32 minisatellite, which is a marker of ALT. The absence of complex telomere mutations persisted in BLM-depleted clones, and there was a clear increase in sequence homogenization across the telomere and MS32 repeat arrays. These data indicate that BLM suppresses unequal sister chromatid interactions that result in excessive homogenization at MS32 and at telomeres in ALT+ cells.

  4. Aurora Kinase B, a novel regulator of TERF1 binding and telomeric integrity

    PubMed Central

    Chan, Foong Lyn; Vinod, Benjamin; Novy, Karel; Schittenhelm, Ralf B.; Huang, Cheng; Udugama, Maheshi; Nunez-Iglesias, Juan; Lin, Jane I.; Hii, Linda; Chan, Julie; Pickett, Hilda A.; Daly, Roger J.

    2017-01-01

    Abstract AURKB (Aurora Kinase B) is a serine/threonine kinase better known for its role at the mitotic kinetochore during chromosome segregation. Here, we demonstrate that AURKB localizes to the telomeres in mouse embryonic stem cells, where it interacts with the essential telomere protein TERF1. Loss of AURKB function affects TERF1 telomere binding and results in aberrant telomere structure. In vitro kinase experiments successfully identified Serine 404 on TERF1 as a putative AURKB target site. Importantly, in vivo overexpression of S404-TERF1 mutants results in fragile telomere formation. These findings demonstrate that AURKB is an important regulator of telomere structural integrity. PMID:29040668

  5. Mitosis, double strand break repair, and telomeres: a view from the end: how telomeres and the DNA damage response cooperate during mitosis to maintain genome stability.

    PubMed

    Cesare, Anthony J

    2014-11-01

    Double strand break (DSB) repair is suppressed during mitosis because RNF8 and downstream DNA damage response (DDR) factors, including 53BP1, do not localize to mitotic chromatin. Discovery of the mitotic kinase-dependent mechanism that inhibits DSB repair during cell division was recently reported. It was shown that restoring mitotic DSB repair was detrimental, resulting in repair dependent genome instability and covalent telomere fusions. The telomere DDR that occurs naturally during cellular aging and in cancer is known to be refractory to G2/M checkpoint activation. Such DDR-positive telomeres, and those that occur as part of the telomere-dependent prolonged mitotic arrest checkpoint, normally pass through mitosis without covalent ligation, but result in cell growth arrest in G1 phase. The discovery that suppressing DSB repair during mitosis may function primarily to protect DDR-positive telomeres from fusing during cell division reinforces the unique cooperation between telomeres and the DDR to mediate tumor suppression. © 2014 The Author. Bioessays published by WILEY Periodicals, Inc.

  6. FTO associations with obesity and telomere length.

    PubMed

    Zhou, Yuling; Hambly, Brett D; McLachlan, Craig S

    2017-09-01

    This review examines the biology of the Fat mass- and obesity-associated gene (FTO), and the implications of genetic association of FTO SNPs with obesity and genetic aging. Notably, we focus on the role of FTO in the regulation of methylation status as possible regulators of weight gain and genetic aging. We present a theoretical review of the FTO gene with a particular emphasis on associations with UCP2, AMPK, RBL2, IRX3, CUX1, mTORC1 and hormones involved in hunger regulation. These associations are important for dietary behavior regulation and cellular nutrient sensing via amino acids. We suggest that these pathways may also influence telomere regulation. Telomere length (TL) attrition may be influenced by obesity-related inflammation and oxidative stress, and FTO gene-involved pathways. There is additional emerging evidence to suggest that telomere length and obesity are bi-directionally associated. However, the role of obesity risk-related genotypes and associations with TL are not well understood. The FTO gene may influence pathways implicated in regulation of TL, which could help to explain some of the non-consistent relationship between weight phenotype and telomere length that is observed in population studies investigating obesity.

  7. PSYCHIATRIC DISORDERS AND LEUKOCYTE TELOMERE LENGTH: UNDERLYING MECHANISMS LINKING MENTAL ILLNESS WITH CELLULAR AGING

    PubMed Central

    Lindqvist, Daniel; Epel, Elissa S.; Mellon, Synthia H.; Penninx, Brenda W.; Révész, Dóra; Verhoeven, Josine E.; Reus, Victor I.; Lin, Jue; Mahan, Laura; Hough, Christina M.; Rosser, Rebecca; Bersani, F. Saverio; Blackburn, Elizabeth H.; Wolkowitz, Owen M.

    2015-01-01

    Many psychiatric illnesses are associated with early mortality and with an increased risk of developing physical diseases that are more typically seen in the elderly. Moreover, certain psychiatric illnesses may be associated with accelerated cellular aging, evidenced by shortened leukocyte telomere length (LTL), which could underlie this association. Shortened LTL reflects a cell’s mitotic history and cumulative exposure to inflammation and oxidation as well as the availability of telomerase, a telomere-lengthening enzyme. Critically short telomeres can cause cells to undergo senescence, apoptosis or genomic instability, and shorter LTL correlates with poorer health and predicts mortality. Emerging data suggest that LTL may be reduced in certain psychiatric illnesses, perhaps in proportion to exposure to the psychiatric illnesses, although conflicting data exist. Telomerase has been less well characterized in psychiatric illnesses, but a role in depression and in antidepressant and neurotrophic effects has been suggested by preclinical and clinical studies. In this article, studies on LTL and telomerase activity in psychiatric illnesses are critically reviewed, potential mediators are discussed, and future directions are suggested. A deeper understanding of cellular aging in psychiatric illnesses could lead to re-conceptualizing them as systemic illnesses with manifestations inside and outside the brain and could identify new treatment targets. PMID:25999120

  8. Roles of telomeres and telomerase in cancer, and advances in telomerase-targeted therapies.

    PubMed

    Jafri, Mohammad A; Ansari, Shakeel A; Alqahtani, Mohammed H; Shay, Jerry W

    2016-06-20

    Telomeres maintain genomic integrity in normal cells, and their progressive shortening during successive cell divisions induces chromosomal instability. In the large majority of cancer cells, telomere length is maintained by telomerase. Thus, telomere length and telomerase activity are crucial for cancer initiation and the survival of tumors. Several pathways that regulate telomere length have been identified, and genome-scale studies have helped in mapping genes that are involved in telomere length control. Additionally, genomic screening for recurrent human telomerase gene hTERT promoter mutations and mutations in genes involved in the alternative lengthening of telomeres pathway, such as ATRX and DAXX, has elucidated how these genomic changes contribute to the activation of telomere maintenance mechanisms in cancer cells. Attempts have also been made to develop telomere length- and telomerase-based diagnostic tools and anticancer therapeutics. Recent efforts have revealed key aspects of telomerase assembly, intracellular trafficking and recruitment to telomeres for completing DNA synthesis, which may provide novel targets for the development of anticancer agents. Here, we summarize telomere organization and function and its role in oncogenesis. We also highlight genomic mutations that lead to reactivation of telomerase, and mechanisms of telomerase reconstitution and trafficking that shed light on its function in cancer initiation and tumor development. Additionally, recent advances in the clinical development of telomerase inhibitors, as well as potential novel targets, will be summarized.

  9. Modified Terminal Restriction Fragment Analysis for Quantifying Telomere Length Using In-gel Hybridization.

    PubMed

    Jenkins, Frank J; Kerr, Charles M; Fouquerel, Elise; Bovbjerg, Dana H; Opresko, Patricia L

    2017-07-10

    There are several different techniques for measuring telomere length, each with their own advantages and disadvantages. The traditional approach, Telomere Restriction Fragment (TRF) analysis, utilizes a DNA hybridization technique whereby genomic DNA samples are digested with restriction enzymes, leaving behind telomere DNA repeats and some sub-telomeric DNA. These are separated by agarose gel electrophoresis, transferred to a filter membrane and hybridized to oligonucleotide probes tagged with either chemiluminescence or radioactivity to visualize telomere restriction fragments. This approach, while requiring a larger quantity of DNA than other techniques such as PCR, can measure the telomere length distribution of a population of cells and allows measurement expressed in absolute kilobases. This manuscript demonstrates a modified DNA hybridization procedure for determining telomere length. Genomic DNA is first digested with restriction enzymes (that do not cut telomeres) and separated by agarose gel electrophoresis. The gel is then dried and the DNA is denatured and hybridized in situ to a radiolabeled oligonucleotide probe. This in situ hybridization avoids loss of telomere DNA and improves signal intensity. Following hybridization, the gels are imaged utilizing phosphor screens and the telomere length is quantified using a graphing program. This procedure was developed by the laboratories of Drs. Woodring Wright and Jerry Shay at the University of Texas Southwestern 1 , 2 . Here, we present a detailed description of this procedure, with some modifications.

  10. Mind the cell: Seasonal variation in telomere length mirrors changes in leucocyte profile.

    PubMed

    Beaulieu, Michaël; Benoit, Laure; Abaga, Steven; Kappeler, Peter M; Charpentier, Marie J E

    2017-10-01

    Leucocytes are typically considered as a whole in studies examining telomere dynamics in mammals. Such an approach may be precarious, as leucocytes represent the only nucleated blood cells in mammals, their composition varies temporally, and telomere length differs between leucocyte types. To highlight this limitation, we examined here whether seasonal variation in leucocyte composition was related to variation in telomere length in free-ranging mandrills (Mandrilllus sphinx). We found that the leucocyte profile of mandrills varied seasonally, with lower lymphocyte proportion being observed during the long dry season presumably because of the combined effects of high nematode infection and stress at that time of the year. Interestingly, this low lymphocyte proportion during the long dry season was associated with shorter telomeres. Accordingly, based on longitudinal data, we found that seasonal changes in lymphocyte proportion were reflected by corresponding seasonal variation in telomere length. Overall, these results suggest that variation in lymphocyte proportion in blood can significantly affect telomere measurements in mammals. However, lymphocyte proportion did not entirely explain variation in telomere length. For instance, a lower lymphocyte proportion with age could not fully explain shorter telomeres in older individuals. Overall, our results show that telomere length and leucocyte profile are strongly although imperfectly intertwined, which may obscure the relationship between telomere dynamics and ageing processes in mammals. © 2017 John Wiley & Sons Ltd.

  11. Inositol phosphate pathway controls transcription of telomeric expression sites in trypanosomes

    PubMed Central

    Cestari, Igor; Stuart, Ken

    2015-01-01

    African trypanosomes evade clearance by host antibodies by periodically changing their variant surface glycoprotein (VSG) coat. They transcribe only one VSG gene at a time from 1 of about 20 telomeric expression sites (ESs). They undergo antigenic variation by switching transcription between telomeric ESs or by recombination of the VSG gene expressed. We show that the inositol phosphate (IP) pathway controls transcription of telomeric ESs and VSG antigenic switching in Trypanosoma brucei. Conditional knockdown of phosphatidylinositol 5-kinase (TbPIP5K) or phosphatidylinositol 5-phosphatase (TbPIP5Pase) or overexpression of phospholipase C (TbPLC) derepresses numerous silent ESs in T. brucei bloodstream forms. The derepression is specific to telomeric ESs, and it coincides with an increase in the number of colocalizing telomeric and RNA polymerase I foci in the nucleus. Monoallelic VSG transcription resumes after reexpression of TbPIP5K; however, most of the resultant cells switched the VSG gene expressed. TbPIP5K, TbPLC, their substrates, and products localize to the plasma membrane, whereas TbPIP5Pase localizes to the nucleus proximal to telomeres. TbPIP5Pase associates with repressor/activator protein 1 (TbRAP1), and their telomeric silencing function is altered by TbPIP5K knockdown. These results show that specific steps in the IP pathway control ES transcription and antigenic switching in T. brucei by epigenetic regulation of telomere silencing. PMID:25964327

  12. Analysis of Poly(ADP-Ribose) Polymerases in Arabidopsis Telomere Biology

    PubMed Central

    Townley, Jennifer M.; Shippen, Dorothy E.

    2014-01-01

    Maintaining the length of the telomere tract at chromosome ends is a complex process vital to normal cell division. Telomere length is controlled through the action of telomerase as well as a cadre of telomere-associated proteins that facilitate replication of the chromosome end and protect it from eliciting a DNA damage response. In vertebrates, multiple poly(ADP-ribose) polymerases (PARPs) have been implicated in the regulation of telomere length, telomerase activity and chromosome end protection. Here we investigate the role of PARPs in plant telomere biology. We analyzed Arabidopsis thaliana mutants null for PARP1 and PARP2 as well as plants treated with the PARP competitive inhibitor 3-AB. Plants deficient in PARP were hypersensitive to genotoxic stress, and expression of PARP1 and PARP2 mRNA was elevated in response to MMS or zeocin treatment or by the loss of telomerase. Additionally, PARP1 mRNA was induced in parp2 mutants, and conversely, PARP2 mRNA was induced in parp1 mutants. PARP3 mRNA, by contrast, was elevated in both parp1 and parp2 mutants, but not in seedlings treated with 3-AB or zeocin. PARP mutants and 3-AB treated plants displayed robust telomerase activity, no significant changes in telomere length, and no end-to-end chromosome fusions. Although there remains a possibility that PARPs play a role in Arabidopsis telomere biology, these findings argue that the contribution is a minor one. PMID:24551184

  13. Telomere length and early severe social deprivation: linking early adversity and cellular aging

    PubMed Central

    Drury, SS; Theall, K; Gleason, MM; Smyke, AT; De Vivo, I; Wong, JYY; Fox, NA; Zeanah, CH; Nelson, CA

    2012-01-01

    Accelerated telomere length attrition has been associated with psychological stress and early adversity in adults; however, no studies have examined whether telomere length in childhood is associated with early experiences. The Bucharest Early Intervention Project is a unique randomized controlled trial of foster care placement compared with continued care in institutions. As a result of the study design, participants were exposed to a quantified range of time in institutional care, and represented an ideal population in which to examine the association between a specific early adversity, institutional care and telomere length. We examined the association between average relative telomere length, telomere repeat copy number to single gene copy number (T/S) ratio and exposure to institutional care quantified as the percent of time at baseline (mean age 22 months) and at 54 months of age that each child lived in the institution. A significant negative correlation between T/S ratio and percentage of time was observed. Children with greater exposure to institutional care had significantly shorter relative telomere length in middle childhood. Gender modified this main effect. The percentage of time in institutional care at baseline significantly predicted telomere length in females, whereas the percentage of institutional care at 54 months was strongly predictive of telomere length in males. This is the first study to demonstrate an association between telomere length and institutionalization, the first study to find an association between adversity and telomere length in children, and contributes to the growing literature linking telomere length and early adversity. PMID:21577215

  14. Cardiomyocyte-Specific Telomere Shortening is a Distinct Signature of Heart Failure in Humans.

    PubMed

    Sharifi-Sanjani, Maryam; Oyster, Nicholas M; Tichy, Elisia D; Bedi, Kenneth C; Harel, Ofer; Margulies, Kenneth B; Mourkioti, Foteini

    2017-09-07

    Telomere defects are thought to play a role in cardiomyopathies, but the specific cell type affected by the disease in human hearts is not yet identified. The aim of this study was to systematically evaluate the cell type specificity of telomere shortening in patients with heart failure in relation to their cardiac disease, age, and sex. We studied cardiac tissues from patients with heart failure by utilizing telomere quantitative fluorescence in situ hybridization, a highly sensitive method with single-cell resolution. In this study, total of 63 human left ventricular samples, including 37 diseased and 26 nonfailing donor hearts, were stained for telomeres in combination with cardiomyocyte- or α-smooth muscle cell-specific markers, cardiac troponin T, and smooth muscle actin, respectively, and assessed for telomere length. Patients with heart failure demonstrate shorter cardiomyocyte telomeres compared with nonfailing donors, which is specific only to cardiomyocytes within diseased human hearts and is associated with cardiomyocyte DNA damage. Our data further reveal that hypertrophic hearts with reduced ejection fraction exhibit the shortest telomeres. In contrast to other reported cell types, no difference in cardiomyocyte telomere length is evident with age. However, under the disease state, telomere attrition manifests in both young and older patients with cardiac hypertrophy. Finally, we demonstrate that cardiomyocyte-telomere length is better sustained in women than men under diseased conditions. This study provides the first evidence of cardiomyocyte-specific telomere shortening in heart failure. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

  15. Interstitial telomeric sequences in human chromosomes cluster with common fragile sites, mutagen sensitive sites, viral integration sites, cancer breakpoints, proto-oncogenes and breakpoints involved in primate evolution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Adekunle, S.S.A.; Wyandt, H.; Mark, H.F.L.

    1994-09-01

    Recently we mapped the telomeric repeat sequences to 111 interstitial sites in the human genome and to sites of gaps and breaks induced by aphidicolin and sister chromatid exchange sites detected by BrdU. Many of these sites correspond to conserved fragile sites in man, gorilla and chimpazee, to sites of conserved sister chromatid exchange in the mammalian X chromosome, to mutagenic sensitive sites, mapped locations of proto-oncogenes, breakpoints implicated in primate evolution and to breakpoints indicated as the sole anomaly in neoplasia. This observation prompted us to investigate if the interstitial telomeric sites cluster with these sites. An extensive literaturemore » search was carried out to find all the available published sites mentioned above. For comparison, we also carried out a statistical analysis of the clustering of the sites of the telomeric repeats with the gene locations where only nucleotide mutations have been observed as the only chromosomal abnormality. Our results indicate that the telomeric repeats cluster most with fragile sites, mutagenic sensitive sites and breakpoints implicated in primate evolution and least with cancer breakpoints, mapped locations of proto-oncogenes and other genes with nucleotide mutations.« less

  16. Telomeres and the ethics of human cloning.

    PubMed

    Allhoff, Fritz

    2004-01-01

    In search of a potential problem with cloning, I investigate the phenomenon of telomere shortening which is caused by cell replication; clones created from somatic cells will have shortened telomeres and therefore reach a state of senescence more rapidly. While genetic intervention might fix this problem at some point in the future, I ask whether, absent technological advances, this biological phenomenon undermines the moral permissibility of cloning.

  17. Telomere damage induced by the G-quadruplex ligand RHPS4 has an antitumor effect

    PubMed Central

    Salvati, Erica; Leonetti, Carlo; Rizzo, Angela; Scarsella, Marco; Mottolese, Marcella; Galati, Rossella; Sperduti, Isabella; Stevens, Malcolm F.G.; D’Incalci, Maurizio; Blasco, Maria; Chiorino, Giovanna; Bauwens, Serge; Horard, Béatrice; Gilson, Eric; Stoppacciaro, Antonella; Zupi, Gabriella; Biroccio, Annamaria

    2007-01-01

    Functional telomeres are required for the replicability of cancer cells. The G-rich strand of telomeric DNA can fold into a 4-stranded structure known as the G-quadruplex (G4), whose stabilization alters telomere function limiting cancer cell growth. Therefore, the G4 ligand RHPS4 may possess antitumor activity. Here, we show that RHPS4 triggers a rapid and potent DNA damage response at telomeres in human transformed fibroblasts and melanoma cells, characterized by the formation of several telomeric foci containing phosphorylated DNA damage response factors γ-H2AX, RAD17, and 53BP1. This was dependent on DNA repair enzyme ATR, correlated with delocalization of the protective telomeric DNA–binding protein POT1, and was antagonized by overexpression of POT1 or TRF2. In mice, RHPS4 exerted its antitumor effect on xenografts of human tumor cells of different histotype by telomere injury and tumor cell apoptosis. Tumor inhibition was accompanied by a strong DNA damage response, and tumors overexpressing POT1 or TRF2 were resistant to RHPS4 treatment. These data provide evidence that RHPS4 is a telomere damage inducer and that telomere disruption selectively triggered in malignant cells results in a high therapeutic index in mice. They also define a functional link between telomere damage and antitumor activity and reveal the key role of telomere-protective factors TRF2 and POT1 in response to this anti-telomere strategy. PMID:17932567

  18. Circulating leukocyte telomere length is highly heritable among families of Arab descent

    PubMed Central

    2012-01-01

    Background Telomere length, an indicator of ageing and longevity, has been correlated with several biomarkers of cardiometabolic disease in both Arab children and adults. It is not known, however, whether or not telomere length is a highly conserved inheritable trait in this homogeneous cohort, where age-related diseases are highly prevalent. As such, the aim of this study was to address the inheritability of telomere length in Saudi families and the impact of cardiometabolic disease biomarkers on telomere length. Methods A total of 119 randomly selected Saudi families (123 adults and 131 children) were included in this cross-sectional study. Anthropometrics were obtained and fasting blood samples were taken for routine analyses of fasting glucose and lipid profile. Leukocyte telomere length was determined using quantitative real time PCR. Results Telomere length was highly heritable as assessed by a parent-offspring regression [h2 = 0.64 (p = 0.0006)]. Telomere length was modestly associated with BMI (R2 0.07; p-value 0.0087), total cholesterol (R2 0.08; p-value 0.0033), and LDL-cholesterol (R2 0.15; p-value 3 x 10-5) after adjustments for gender, age and age within generation. Conclusion The high heritability of telomere length in Arab families, and the associations of telomere length with various cardiometabolic parameters suggest heritable genetic fetal and/or epigenetic influences on the early predisposition of Arab children to age-related diseases and accelerated ageing. PMID:22606980

  19. Circulating leukocyte telomere length is highly heritable among families of Arab descent.

    PubMed

    Al-Attas, Omar S; Al-Daghri, Nasser M; Alokail, Majed S; Alkharfy, Khalid M; Alfadda, Assim A; McTernan, Philip; Gibson, Greg C; Sabico, Shaun B; Chrousos, George P

    2012-05-18

    Telomere length, an indicator of ageing and longevity, has been correlated with several biomarkers of cardiometabolic disease in both Arab children and adults. It is not known, however, whether or not telomere length is a highly conserved inheritable trait in this homogeneous cohort, where age-related diseases are highly prevalent. As such, the aim of this study was to address the inheritability of telomere length in Saudi families and the impact of cardiometabolic disease biomarkers on telomere length. A total of 119 randomly selected Saudi families (123 adults and 131 children) were included in this cross-sectional study. Anthropometrics were obtained and fasting blood samples were taken for routine analyses of fasting glucose and lipid profile. Leukocyte telomere length was determined using quantitative real time PCR. Telomere length was highly heritable as assessed by a parent-offspring regression [h2 = 0.64 (p = 0.0006)]. Telomere length was modestly associated with BMI (R(2) 0.07; p-value 0.0087), total cholesterol (R(2) 0.08; p-value 0.0033), and LDL-cholesterol (R(2) 0.15; p-value 3 x 10(-5)) after adjustments for gender, age and age within generation. The high heritability of telomere length in Arab families, and the associations of telomere length with various cardiometabolic parameters suggest heritable genetic fetal and/or epigenetic influences on the early predisposition of Arab children to age-related diseases and accelerated ageing.

  20. Usefulness of telomere length in DNA from human teeth for age estimation.

    PubMed

    Márquez-Ruiz, Ana Belén; González-Herrera, Lucas; Valenzuela, Aurora

    2018-03-01

    Age estimation is widely used to identify individuals in forensic medicine. However, the accuracy of the most commonly used procedures is markedly reduced in adulthood, and these methods cannot be applied in practice when morphological information is limited. Molecular methods for age estimation have been extensively developed in the last few years. The fact that telomeres shorten at each round of cell division has led to the hypothesis that telomere length can be used as a tool to predict age. The present study thus aimed to assess the correlation between telomere length measured in dental DNA and age, and the effect of sex and tooth type on telomere length; a further aim was to propose a statistical regression model to estimate the biological age based on telomere length. DNA was extracted from 91 tooth samples belonging to 77 individuals of both sexes and 15 to 85 years old and was used to determine telomere length by quantitative real-time PCR. Our results suggested that telomere length was not affected by sex and was greater in molar teeth. We found a significant correlation between age and telomere length measured in DNA from teeth. However, the equation proposed to predict age was not accurate enough for forensic age estimation on its own. Age estimation based on telomere length in DNA from tooth samples may be useful as a complementary method which provides an approximate estimate of age, especially when human skeletal remains are the only forensic sample available.

  1. Telomere length and fetal programming: A review of recent scientific advances.

    PubMed

    Whiteman, Valerie E; Goswami, Anjali; Salihu, Hamisu M

    2017-05-01

    We sought to synthesize a comprehensive literature review comprising recent research linking fetal programming to fetal telomere length. We also explored the potential effects fetal telomere length shortening has on fetal phenotypes. Utilizing the PubMed database as our primary search engine, we retrieved and reviewed 165 articles of published research. The inclusion criteria limited the articles to those that appeared within the last ten years, were pertinent to humans, and without restriction to language of publication. Our results showed that socio-demographic factors like age, sex, genetic inheritance, and acquired disease impact telomere length. Further, we found several maternal characteristics to be associated with fetal telomere length shortening, and these include maternal chemical exposure (eg, tobacco smoke), maternal stress during pregnancy, maternal nutritional and sleeping disorders during pregnancy as well as maternal disease status. Due to paucity of data, our review could not synthesize evidence directly linking fetal phenotypes to telomere length shortening. Although the research summarized in this review shows some association between determinants of intrauterine programming and fetal telomere length, there is still significant work that needs to be done to delineate the direct relationship of telomere attrition with specific fetal phenotypes. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. Chiral metallohelices enantioselectively target hybrid human telomeric G-quadruplex DNA

    PubMed Central

    Zhao, Andong; Howson, Suzanne E.; Ren, Jinsong; Scott, Peter; Wang, Chunyu

    2017-01-01

    Abstract The design and synthesis of metal complexes that can specifically target DNA secondary structure has attracted considerable attention. Chiral metallosupramolecular complexes (e.g. helicates) in particular display unique DNA-binding behavior, however until recently few examples which are both water-compatible and enantiomerically pure have been reported. Herein we report that one metallohelix enantiomer Δ1a, available from a diastereoselective synthesis with no need for resolution, can enantioselectively stabilize human telomeric hybrid G-quadruplex and strongly inhibit telomerase activity with IC50 of 600 nM. In contrast, no such a preference is observed for the mirror image complex Λ1a. More intriguingly, neither of the two enantiomers binds specifically to human telomeric antiparallel G-quadruplex. To the best of our knowledge, this is the first example of one pair of enantiomers with contrasting selectivity for human telomeric hybrid G-quadruplex. Further studies show that Δ1a can discriminate human telomeric G-quadruplex from other telomeric G-quadruplexes. PMID:28398500

  3. Childhood adversity, social support, and telomere length among perinatal women.

    PubMed

    Mitchell, Amanda M; Kowalsky, Jennifer M; Epel, Elissa S; Lin, Jue; Christian, Lisa M

    2018-01-01

    Adverse perinatal health outcomes are heightened among women with psychosocial risk factors, including childhood adversity and a lack of social support. Biological aging could be one pathway by which such outcomes occur. However, data examining links between psychosocial factors and indicators of biological aging among perinatal women are limited. The current study examined the associations of childhood socioeconomic status (SES), childhood trauma, and current social support with telomere length in peripheral blood mononuclear cells (PBMCs) in a sample of 81 women assessed in early, mid, and late pregnancy as well as 7-11 weeks postpartum. Childhood SES was defined as perceived childhood social class and parental educational attainment. Measures included the Childhood Trauma Questionnaire, Center for Epidemiologic Studies-Depression Scale, Multidimensional Scale of Perceived Social Support, and average telomere length in PBMCs. Per a linear mixed model, telomere length did not change across pregnancy and postpartum visits; thus, subsequent analyses defined telomere length as the average across all available timepoints. ANCOVAs showed group differences by perceived childhood social class, maternal and paternal educational attainment, and current family social support, with lower values corresponding with shorter telomeres, after adjustment for possible confounds. No effects of childhood trauma or social support from significant others or friends on telomere length were observed. Findings demonstrate that while current SES was not related to telomeres, low childhood SES, independent of current SES, and low family social support were distinct risk factors for cellular aging in women. These data have relevance for understanding potential mechanisms by which early life deprivation of socioeconomic and relationship resources affect maternal health. In turn, this has potential significance for intergenerational transmission of telomere length. The predictive value of

  4. Growing old, yet staying young: The role of telomeres in bats' exceptional longevity.

    PubMed

    Foley, Nicole M; Hughes, Graham M; Huang, Zixia; Clarke, Michael; Jebb, David; Whelan, Conor V; Petit, Eric J; Touzalin, Frédéric; Farcy, Olivier; Jones, Gareth; Ransome, Roger D; Kacprzyk, Joanna; O'Connell, Mary J; Kerth, Gerald; Rebelo, Hugo; Rodrigues, Luísa; Puechmaille, Sébastien J; Teeling, Emma C

    2018-02-01

    Understanding aging is a grand challenge in biology. Exceptionally long-lived animals have mechanisms that underpin extreme longevity. Telomeres are protective nucleotide repeats on chromosome tips that shorten with cell division, potentially limiting life span. Bats are the longest-lived mammals for their size, but it is unknown whether their telomeres shorten. Using >60 years of cumulative mark-recapture field data, we show that telomeres shorten with age in Rhinolophus ferrumequinum and Miniopterus schreibersii , but not in the bat genus with greatest longevity, Myotis . As in humans, telomerase is not expressed in Myotis myotis blood or fibroblasts. Selection tests on telomere maintenance genes show that ATM and SETX , which repair and prevent DNA damage, potentially mediate telomere dynamics in Myotis bats. Twenty-one telomere maintenance genes are differentially expressed in Myotis , of which 14 are enriched for DNA repair, and 5 for alternative telomere-lengthening mechanisms. We demonstrate how telomeres, telomerase, and DNA repair genes have contributed to the evolution of exceptional longevity in Myotis bats, advancing our understanding of healthy aging.

  5. Cocaine use may induce telomere shortening in individuals with HIV infection.

    PubMed

    Lai, Shenghan; Heaphy, Christopher M; Rizzo, Anthony J; Celentano, David D; Gerstenblith, Gary; Li, Ji; Moore, Richard D; Treisman, Glenn; Chen, Shaoguang; Foster, Parker; Kickler, Thomas; Lai, Hong

    2018-06-08

    Although cocaine use may induce/accelerate HIV-associated comorbidities in HIV-infected individuals on antiretroviral therapy (ART), and that HIV itself may accelerate aging, the issue of whether cocaine use plays a role in HIV-associated aging in HIV-infected cocaine users has not been reported. The goals of this study were (1) to explore factor(s) associated with peripheral blood leukocyte telomere length, a marker of cellular replicative history, and telomere shortening in HIV-infected individuals, and (2) to assess whether cocaine use plays a role in accelerating telomere shortening in cocaine users with HIV infection. Between June 2010 and December 2016, 147 HIV-infected participants in Baltimore, Maryland, were enrolled in a cross-sectional study investigating factor(s) associated with telomere length. Of these 147, 93 participated in a follow-up study to examine factor(s) associated with telomere shortening. Robust regression model was used to analyze cross-sectional data and the generalized estimating equation approach was used to analyze follow-up data. Cross-sectional analyses demonstrated that (1) both daily alcohol consumption and use of non-nucleoside reverse transcriptase inhibitors (NNRTIs) were independently associated with telomere length, and cocaine use modified the associations of daily alcohol use and NNRTI use with telomere length. Longitudinal analyses suggested that both daily alcohol consumption and duration of NNRTI use were independently associated with telomere shortening, and (2) cocaine use induced/accelerated telomere shortening in HIV-infected individuals. Our findings suggest that cocaine use may promote premature aging in HIV-infected individuals who are on ART. Our results emphasize the importance of cocaine abstinence/reduced use, which may retard HIV-associated premature aging. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. On the Interplay of Telomeres, Nevi and the Risk of Melanoma

    PubMed Central

    Bodelon, Clara; Pfeiffer, Ruth M.; Bollati, Valentina; Debbache, Julien; Calista, Donato; Ghiorzo, Paola; Fargnoli, Maria Concetta; Bianchi-Scarra, Giovanna; Peris, Ketty; Hoxha, Mirjam; Hutchinson, Amy; Burdette, Laurie; Burke, Laura; Fang, Shenying; Tucker, Margaret A.; Goldstein, Alisa M.; Lee, Jeffrey E.; Wei, Qingyi; Savage, Sharon A.; Yang, Xiaohong R.; Amos, Christopher; Landi, Maria Teresa

    2012-01-01

    The relationship between telomeres, nevi and melanoma is complex. Shorter telomeres have been found to be associated with many cancers and with number of nevi, a known risk factor for melanoma. However, shorter telomeres have also been found to decrease melanoma risk. We performed a systematic analysis of telomere-related genes and tagSNPs within these genes, in relation to the risk of melanoma, dysplastic nevi, and nevus count combining data from four studies conducted in Italy. In addition, we examined whether telomere length measured in peripheral blood leukocytes is related to the risk of melanoma, dysplastic nevi, number of nevi, or telomere-related SNPs. A total of 796 cases and 770 controls were genotyped for 517 SNPs in 39 telomere-related genes genotyped with a custom-made array. Replication of the top SNPs was conducted in two American populations consisting of 488 subjects from 53 melanoma-prone families and 1,086 cases and 1,024 controls from a case-control study. We estimated odds ratios for associations with SNPs and combined SNP P-values to compute gene region-specific, functional group-specific, and overall P-value using an adaptive rank-truncated product algorithm. In the Mediterranean population, we found suggestive evidence that RECQL4, a gene involved in genome stability, RTEL1, a gene regulating telomere elongation, and TERF2, a gene implicated in the protection of telomeres, were associated with melanoma, the presence of dysplastic nevi and number of nevi, respectively. However, these associations were not found in the American samples, suggesting variable melanoma susceptibility for these genes across populations or chance findings in our discovery sample. Larger studies across different populations are necessary to clarify these associations. PMID:23300679

  7. Physical activity and telomere length: Impact of aging and potential mechanisms of action.

    PubMed

    Arsenis, Nicole C; You, Tongjian; Ogawa, Elisa F; Tinsley, Grant M; Zuo, Li

    2017-07-04

    Telomeres protect the integrity of information-carrying DNA by serving as caps on the terminal portions of chromosomes. Telomere length decreases with aging, and this contributes to cell senescence. Recent evidence supports that telomere length of leukocytes and skeletal muscle cells may be positively associated with healthy living and inversely correlated with the risk of several age-related diseases, including cancer, cardiovascular disease, obesity, diabetes, chronic pain, and stress. In observational studies, higher levels of physical activity or exercise are related to longer telomere lengths in various populations, and athletes tend to have longer telomere lengths than non-athletes. This relationship is particularly evident in older individuals, suggesting a role of physical activity in combating the typical age-induced decrements in telomere length. To date, a small number of exercise interventions have been executed to examine the potential influence of chronic exercise on telomere length, but these studies have not fully established such relationship. Several potential mechanisms through which physical activity or exercise could affect telomere length are discussed, including changes in telomerase activity, oxidative stress, inflammation, and decreased skeletal muscle satellite cell content. Future research is needed to mechanistically examine the effects of various modalities of exercise on telomere length in middle-aged and older adults, as well as in specific clinical populations.

  8. TRF1 and TRF2 binding to telomeres is modulated by nucleosomal organization

    PubMed Central

    Galati, Alessandra; Micheli, Emanuela; Alicata, Claudia; Ingegnere, Tiziano; Cicconi, Alessandro; Pusch, Miriam Caroline; Giraud-Panis, Marie-Josèphe; Gilson, Eric; Cacchione, Stefano

    2015-01-01

    The ends of eukaryotic chromosomes need to be protected from the activation of a DNA damage response that leads the cell to replicative senescence or apoptosis. In mammals, protection is accomplished by a six-factor complex named shelterin, which organizes the terminal TTAGGG repeats in a still ill-defined structure, the telomere. The stable interaction of shelterin with telomeres mainly depends on the binding of two of its components, TRF1 and TRF2, to double-stranded telomeric repeats. Tethering of TRF proteins to telomeres occurs in a chromatin environment characterized by a very compact nucleosomal organization. In this work we show that binding of TRF1 and TRF2 to telomeric sequences is modulated by the histone octamer. By means of in vitro models, we found that TRF2 binding is strongly hampered by the presence of telomeric nucleosomes, whereas TRF1 binds efficiently to telomeric DNA in a nucleosomal context and is able to remodel telomeric nucleosomal arrays. Our results indicate that the different behavior of TRF proteins partly depends on the interaction with histone tails of their divergent N-terminal domains. We propose that the interplay between the histone octamer and TRF proteins plays a role in the steps leading to telomere deprotection. PMID:25999344

  9. Telomere length is a prognostic biomarker in elderly advanced ovarian cancer patients: a multicenter GINECO study

    PubMed Central

    Falandry, Claire; Horard, Béatrice; Bruyas, Amandine; Legouffe, Eric; Cretin, Jacques; Meunier, Jérôme; Alexandre, Jérôme; Delecroix, Valérie; Fabbro, Michel; Certain, Marie-Noëlle; Maraval-Gaget, Raymonde; Pujade-Lauraine, Eric; Gilson, Eric; Freyer, Gilles

    2015-01-01

    Purpose Age induces a progressive decline in functional reserve and impacts cancer treatments. Telomere attrition leads to tissue senescence. We tested the hypothesis that telomere length (TL) could predict patient vulnerability and outcome with cancer treatment. Patients and methods An ancillary study in the Elderly Women GINECO Trial 3 was performed to evaluate the impact of geriatric covariates on survival in elderly advanced ovarian cancer patients receiving six cycles of carboplatin. TL was estimated from peripheral blood at inclusion using standard procedures. Results TL (in base pairs) was estimated for 109/111 patients (median 6.1 kb; range [4.5-8.3 kb]). With a cut-off of 5.77 kb, TL discriminated two patient groups, long telomere (LT) and short telomeres (ST), with significantly different treatment completion rates of 0.80 (95%CI [0.71-0.89]) and 0.59 (95%CI [0.41-0.76]), respectively (odds ratio [OR]=2.8, p=0.02). ST patients were at higher risk of serious adverse events (SAE, OR=2.7; p=0.02) and had more unplanned hospital admissions (OR=2.1; p=0.08). After adjustment on FIGO stage, TL shorter than 6 kb was a risk factor of premature death (HR=1.57; p=0.06). Conclusion This exploratory study identifies TL as predictive factor of decreased treatment completion, SAE risk, unplanned hospital admissions and OS after adjustment on FIGO stage. PMID:26638179

  10. Live-cell imaging reveals the dynamics and function of single-telomere TERRA molecules in cancer cells.

    PubMed

    Avogaro, Laura; Querido, Emmanuelle; Dalachi, Myriam; Jantsch, Michael F; Chartrand, Pascal; Cusanelli, Emilio

    2018-04-16

    Telomeres cap the ends of eukaryotic chromosomes, protecting them from degradation and erroneous recombination events which may lead to genome instability. Telomeres are transcribed giving rise to telomeric repeat-containing RNAs, called TERRA. The TERRA long noncoding RNAs have been proposed to play important roles in telomere biology, including heterochromatin formation and telomere length homeostasis. While TERRA RNAs are predominantly nuclear and localize at telomeres, little is known about the dynamics and function of TERRA molecules expressed from individual telomeres. Herein, we developed an assay to image endogenous TERRA molecules expressed from a single telomere in living human cancer cells. We show that single-telomere TERRA can be detected as TERRA RNA single particles which freely diffuse within the nucleus. Furthermore, TERRA molecules aggregate forming TERRA clusters. Three-dimensional size distribution and single particle tracking analyses revealed distinct sizes and dynamics for TERRA RNA single particles and clusters. Simultaneous time lapse confocal imaging of TERRA particles and telomeres showed that TERRA clusters transiently co-localize with telomeres. Finally, we used chemically modified antisense oligonucleotides to deplete TERRA molecules expressed from a single telomere. Single-telomere TERRA depletion resulted in increased DNA damage at telomeres and elsewhere in the genome. These results suggest that single-telomere TERRA transcripts participate in the maintenance of genomic integrity in human cancer cells.

  11. Older men with higher self-rated socioeconomic status have shorter telomeres

    PubMed Central

    Woo, Jean; Suen, Eddie W. C.; Leung, Jason C. S.; Tang, Nelson L. S.; Ebrahim, Shah

    2009-01-01

    Background: previous studies examining the relationship between socioeconomic status and telomere length showed conflicting results, one study finding shorter telomere length in subjects with lower socioeconomic status and one showing no relationship. Design: cross-sectional study. Setting: community-living elderly Chinese in Hong Kong. Objective: this study examines the relationship between self-rated social economic status and telomere length in Hong Kong Chinese men and women aged 65 years and over living in the community. Subjects and method: information was collected from 958 men and 978 women regarding possible confounding factors such as the presence of chronic diseases, smoking, physical activity level, dietary intake and body mass index. Telomere length was measured by quantitative PCR. Result: in men only, after adjustment for age and other confounding factors, a higher ranking in community standing was associated with shorter telomere length. Conclusion: men with higher self-rated socioeconomic status have shorter telomeres, possibly mediated through psychosocial rather than lifestyle factors or the presence of chronic disease. There may be cultural ethnic and age-related differences in social determinants of health. PMID:19556325

  12. Getting it done at the ends: Pif1 family DNA helicases and telomeres

    PubMed Central

    Geronimo, Carly L.; Zakian, Virginia A.

    2017-01-01

    It is widely appreciated that the ends of linear DNA molecules cannot be fully replicated by the conventional replication apparatus. Less well known is that semi-conservative replication of telomeric DNA also presents problems for DNA replication. These problems likely arise from the atypical chromatin structure of telomeres, the GC-richness of telomeric DNA that makes it prone to forming DNA secondary structures, and from RNA-DNA hybrids, formed by transcripts of one or both DNA strands. Given the different aspects of telomeres that complicate their replication, it is not surprising that multiple DNA helicases promote replication of telomeric DNA. This review focuses on one such class of DNA helicases, the Pif1 family of 5′–3′ DNA helicases. In budding and fission yeasts, Pif1 family helicases impact both telomerase-mediated and semi-conservative replication of telomeric DNA as well as recombination-mediated telomere lengthening. PMID:27233114

  13. Augmented telomerase activity, reduced telomere length and the presence of alternative lengthening of telomere in renal cell carcinoma: plausible predictive and diagnostic markers.

    PubMed

    Pal, Deeksha; Sharma, Ujjawal; Khajuria, Ragini; Singh, Shrawan Kumar; Kakkar, Nandita; Prasad, Rajendra

    2015-05-15

    In this study, we analyzed 100 cases of renal cell carcinoma (RCC) for telomerase activity, telomere length and alternative lengthening of telomeres (ALT) using the TRAP assay, TeloTTAGGG assay kit and immunohistochemical analysis of ALT associated promyelocytic leukemia (PML) bodies respectively. A significantly higher (P=0.000) telomerase activity was observed in 81 cases of RCC which was correlated with clinicopathological features of tumor for instance, stage (P=0.008) and grades (P=0.000) but not with the subtypes of RCC (P = 0.355). Notwithstanding, no correlation was found between telomerase activity and subtypes of RCC. Strikingly, the telomere length was found to be significantly shorter in RCC (P=0.000) to that of corresponding normal renal tissues and it is well correlated with grades (P=0.016) but not with stages (P=0.202) and subtypes (P=0.669) of RCC. In this study, telomere length was also negatively correlated with the age of patients (r(2)=0.528; P=0.000) which supports the notion that it could be used as a marker for biological aging. ALT associated PML bodies containing PML protein was found in telomerase negative cases of RCC. It suggests the presence of an ALT pathway mechanism to maintain the telomere length in telomerase negative RCC tissues which was associated with high stages of RCC, suggesting a prevalent mechanism for telomere maintenance in high stages. In conclusion, the telomerase activity and telomere length can be used as a diagnostic as well as a predictive marker in RCC. The prevalence of ALT mechanism in high stages of RCC is warranted for the development of anti-ALT inhibitors along with telomerase inhibitor against RCC as a therapeutic approach. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Ku must load directly onto the chromosome end in order to mediate its telomeric functions.

    PubMed

    Lopez, Christopher R; Ribes-Zamora, Albert; Indiviglio, Sandra M; Williams, Christopher L; Haricharan, Svasti; Bertuch, Alison A

    2011-08-01

    The Ku heterodimer associates with the Saccharomyces cerevisiae telomere, where it impacts several aspects of telomere structure and function. Although Ku avidly binds DNA ends via a preformed channel, its ability to associate with telomeres via this mechanism could be challenged by factors known to bind directly to the chromosome terminus. This has led to uncertainty as to whether Ku itself binds directly to telomeric ends and whether end association is crucial for Ku's telomeric functions. To address these questions, we constructed DNA end binding-defective Ku heterodimers by altering amino acid residues in Ku70 and Ku80 that were predicted to contact DNA. These mutants continued to associate with their known telomere-related partners, such as Sir4, a factor required for telomeric silencing, and TLC1, the RNA component of telomerase. Despite these interactions, we found that the Ku mutants had markedly reduced association with telomeric chromatin and null-like deficiencies for telomere end protection, length regulation, and silencing functions. In contrast to Ku null strains, the DNA end binding defective Ku mutants resulted in increased, rather than markedly decreased, imprecise end-joining proficiency at an induced double-strand break. This result further supports that it was the specific loss of Ku's telomere end binding that resulted in telomeric defects rather than global loss of Ku's functions. The extensive telomere defects observed in these mutants lead us to propose that Ku is an integral component of the terminal telomeric cap, where it promotes a specific architecture that is central to telomere function and maintenance.

  15. Ku Must Load Directly onto the Chromosome End in Order to Mediate Its Telomeric Functions

    PubMed Central

    Lopez, Christopher R.; Ribes-Zamora, Albert; Indiviglio, Sandra M.; Williams, Christopher L.; Haricharan, Svasti; Bertuch, Alison A.

    2011-01-01

    The Ku heterodimer associates with the Saccharomyces cerevisiae telomere, where it impacts several aspects of telomere structure and function. Although Ku avidly binds DNA ends via a preformed channel, its ability to associate with telomeres via this mechanism could be challenged by factors known to bind directly to the chromosome terminus. This has led to uncertainty as to whether Ku itself binds directly to telomeric ends and whether end association is crucial for Ku's telomeric functions. To address these questions, we constructed DNA end binding–defective Ku heterodimers by altering amino acid residues in Ku70 and Ku80 that were predicted to contact DNA. These mutants continued to associate with their known telomere-related partners, such as Sir4, a factor required for telomeric silencing, and TLC1, the RNA component of telomerase. Despite these interactions, we found that the Ku mutants had markedly reduced association with telomeric chromatin and null-like deficiencies for telomere end protection, length regulation, and silencing functions. In contrast to Ku null strains, the DNA end binding defective Ku mutants resulted in increased, rather than markedly decreased, imprecise end-joining proficiency at an induced double-strand break. This result further supports that it was the specific loss of Ku's telomere end binding that resulted in telomeric defects rather than global loss of Ku's functions. The extensive telomere defects observed in these mutants lead us to propose that Ku is an integral component of the terminal telomeric cap, where it promotes a specific architecture that is central to telomere function and maintenance. PMID:21852961

  16. Longitudinal telomere shortening and early Alzheimer's disease progression in adults with down syndrome.

    PubMed

    Jenkins, Edmund C; Marchi, Elaine J; Velinov, Milen T; Ye, Lingling; Krinsky-McHale, Sharon J; Zigman, Warren B; Schupf, Nicole; Silverman, Wayne P

    2017-12-01

    Telomere shortening was shown to parallel Alzheimer's disease (AD) associated dementia. By using a dual PNA Probe system we have developed a practical method for comparing telomere length in T-lymphocyte interphases from individuals with Down syndrome (DS) with and without "mild cognitive impairment" (MCI-DS) and demonstrated that telomere length can serve as a valid biomarker for the onset of MCI-DS in this high-risk population. To verify progressive cognitive decline we have now examined sequential changes in telomere length in 10 adults with DS (N = 4 Female, N = 6 Male) developing MCI-DS. Cases were selected blind to telomere length from a sample of adults with DS previously enrolled in a prospective longitudinal study at 18-month intervals with clinical and telomere assessments: (1) MCI-DS group data were collected approximately three years prior to development of MCI-DS; (2) 18 months later; (3) when MCI-DS was first observed. These telomere measures were compared to those from another 10 adults with DS matched by sex and approximate age but without indications of MCI-DS (Controls). PNA (peptide nucleic acid) probes for telomeres together with a chromosome two centromere probe were used. Findings indicated telomere shortening over time for both Cases and Controls. Group differences emerged by 18-months prior to recognition of MCI-DS onset and completely non-overlapping distributions of telomere measures were observed by the time of MCI-DS onset. This study adds to accumulating evidence of the value of telomere length, as an early biomarker of AD progression in adults with Down syndrome. © 2017 Wiley Periodicals, Inc.

  17. DNA damage response at telomeres contributes to lung aging and chronic obstructive pulmonary disease

    PubMed Central

    Birch, Jodie; Anderson, Rhys K.; Correia-Melo, Clara; Jurk, Diana; Hewitt, Graeme; Marques, Francisco Madeira; Green, Nicola J.; Moisey, Elizabeth; Birrell, Mark A.; Belvisi, Maria G.; Black, Fiona; Taylor, John J.; Fisher, Andrew J.; De Soyza, Anthony

    2015-01-01

    Cellular senescence has been associated with the structural and functional decline observed during physiological lung aging and in chronic obstructive pulmonary disease (COPD). Airway epithelial cells are the first line of defense in the lungs and are important to COPD pathogenesis. However, the mechanisms underlying airway epithelial cell senescence, and particularly the role of telomere dysfunction in this process, are poorly understood. We aimed to investigate telomere dysfunction in airway epithelial cells from patients with COPD, in the aging murine lung and following cigarette smoke exposure. We evaluated colocalization of γ-histone protein 2A.X and telomeres and telomere length in small airway epithelial cells from patients with COPD, during murine lung aging, and following cigarette smoke exposure in vivo and in vitro. We found that telomere-associated DNA damage foci increase in small airway epithelial cells from patients with COPD, without significant telomere shortening detected. With age, telomere-associated foci increase in small airway epithelial cells of the murine lung, which is accelerated by cigarette smoke exposure. Moreover, telomere-associated foci predict age-dependent emphysema, and late-generation Terc null mice, which harbor dysfunctional telomeres, show early-onset emphysema. We found that cigarette smoke accelerates telomere dysfunction via reactive oxygen species in vitro and may be associated with ataxia telangiectasia mutated-dependent secretion of inflammatory cytokines interleukin-6 and -8. We propose that telomeres are highly sensitive to cigarette smoke-induced damage, and telomere dysfunction may underlie decline of lung function observed during aging and in COPD. PMID:26386121

  18. A novel, simple and rapid nondenaturing FISH (ND-FISH) technique for the detection of plant telomeres. Potential used and possible target structures detected.

    PubMed

    Cuadrado, Angeles; Golczyk, Hieronim; Jouve, Nicolás

    2009-01-01

    We report a new technique-nondenaturing FISH (ND-FISH)-for the rapid detection of plant telomeres without the need for prior denaturation of the chromosomes. In its development, two modified, synthetic oligonucleotides, 21 nt in length, fluorescently labelled at their 5' and 3' ends and complementary to either the cytidine-rich (C(3)TA(3)) or guanosine-rich (T(3)AG(3)) telomeric DNA strands, were used as probes. The high binding affinity of these probes and the short hybridization time required allows the visualization of plant telomeres in less than an hour. In tests, both probes gave strong signals visualized as double spots at both chromosome ends; this was true of both the mitotic and meiotic chromosomes of barley, wheat, rye, maize, Brachypodium distachyon and Rhoeo spathacea. They were also able to detect telomere motifs at certain intercalary sites in the chromosomes of R. spathacea. To investigate the nature of the target structures detected, the chromosomes were treated with RNase A and single strand-specific nuclease S1 before ND-FISH experiments. Signal formation was resistant to standard enzymatic treatment, but sensitive when much higher enzyme concentrations were used. The results are discussed in relation to current knowledge of telomere structure.

  19. Recurrent Innovation at Genes Required for Telomere Integrity in Drosophila.

    PubMed

    Lee, Yuh Chwen G; Leek, Courtney; Levine, Mia T

    2017-02-01

    Telomeres are nucleoprotein complexes at the ends of linear chromosomes. These specialized structures ensure genome integrity and faithful chromosome inheritance. Recurrent addition of repetitive, telomere-specific DNA elements to chromosome ends combats end-attrition, while specialized telomere-associated proteins protect naked, double-stranded chromosome ends from promiscuous repair into end-to-end fusions. Although telomere length homeostasis and end-protection are ubiquitous across eukaryotes, there is sporadic but building evidence that the molecular machinery supporting these essential processes evolves rapidly. Nevertheless, no global analysis of the evolutionary forces that shape these fast-evolving proteins has been performed on any eukaryote. The abundant population and comparative genomic resources of Drosophila melanogaster and its close relatives offer us a unique opportunity to fill this gap. Here we leverage population genetics, molecular evolution, and phylogenomics to define the scope and evolutionary mechanisms driving fast evolution of genes required for telomere integrity. We uncover evidence of pervasive positive selection across multiple evolutionary timescales. We also document prolific expansion, turnover, and expression evolution in gene families founded by telomeric proteins. Motivated by the mutant phenotypes and molecular roles of these fast-evolving genes, we put forward four alternative, but not mutually exclusive, models of intra-genomic conflict that may play out at very termini of eukaryotic chromosomes. Our findings set the stage for investigating both the genetic causes and functional consequences of telomere protein evolution in Drosophila and beyond. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  20. An Integrative Review of Factors Associated with Telomere Length and Implications for Biobehavioral Research

    PubMed Central

    Starkweather, Angela R.; Alhaeeri, Areej A.; Montpetit, Alison; Brumelle, Jenni; Filler, Kristin; Montpetit, Marty; Mohanraj, Lathika; Lyon, Debra E.; Jackson-Cook, Colleen K.

    2014-01-01

    Background Although telomere shortening occurs as a natural part of aging, there is now a robust body of research that suggests that there is a relationship between psychosocial, environmental, and behavioral factors and changes in telomere length. These factors need to be considered when integrating telomere measurement in biobehavioral research studies. Objectives This article provides a brief summary of the known facts about telomere biology and an integrative review of current human research studies that assessed relationships between psychosocial, environmental, or behavioral factors and telomere length. Methods An integrative review was conducted to examine human research studies that focused on psychosocial, environmental, and behavioral factors affecting telomere length and telomerase activity using the electronic databases PubMed/Medline and CINAHL from 2003 to the present. In addition to the known individual factors that are associated with telomere length, the results of the integrative review suggest that perceived stress, childhood adversities, major depressive disorder, educational attainment, physical activity, and sleep duration should also be measured. Discussion Multiple factors have been shown to affect telomere length. To advance understanding of the role of telomere length in health and disease risk, it will be important to further elucidate the mechanisms that contribute to telomere shortening. PMID:24335912

  1. Telomerecat: A ploidy-agnostic method for estimating telomere length from whole genome sequencing data.

    PubMed

    Farmery, James H R; Smith, Mike L; Lynch, Andy G

    2018-01-22

    Telomere length is a risk factor in disease and the dynamics of telomere length are crucial to our understanding of cell replication and vitality. The proliferation of whole genome sequencing represents an unprecedented opportunity to glean new insights into telomere biology on a previously unimaginable scale. To this end, a number of approaches for estimating telomere length from whole-genome sequencing data have been proposed. Here we present Telomerecat, a novel approach to the estimation of telomere length. Previous methods have been dependent on the number of telomeres present in a cell being known, which may be problematic when analysing aneuploid cancer data and non-human samples. Telomerecat is designed to be agnostic to the number of telomeres present, making it suited for the purpose of estimating telomere length in cancer studies. Telomerecat also accounts for interstitial telomeric reads and presents a novel approach to dealing with sequencing errors. We show that Telomerecat performs well at telomere length estimation when compared to leading experimental and computational methods. Furthermore, we show that it detects expected patterns in longitudinal data, repeated measurements, and cross-species comparisons. We also apply the method to a cancer cell data, uncovering an interesting relationship with the underlying telomerase genotype.

  2. Dimensions of religious involvement and leukocyte telomere length.

    PubMed

    Hill, Terrence D; Ellison, Christopher G; Burdette, Amy M; Taylor, John; Friedman, Katherine L

    2016-08-01

    Although numerous studies suggest that religious involvement is associated with a wide range of favorable health outcomes, it is unclear whether this general pattern extends to cellular aging. In this paper, we tested whether leukocyte telomere length varies according to several dimensions of religious involvement. We used cross-sectional data from the Nashville Stress and Health Study (2011-2014), a large probability sample of 1252 black and white adults aged 22 to 69 living in Davidson County, TN, USA. Leukocyte telomere length was measured using the monochrome multiplex quantitative polymerase chain reaction method with albumin as the single-copy reference sequence. Dimensions of religious involvement included religiosity, religious support, and religious coping. Our multivariate analyses showed that religiosity (an index of religious attendance, prayer frequency, and religious identity) was positively associated with leukocyte telomere length, even with adjustments for religious support, religious coping, age, gender, race, education, employment status, income, financial strain, stressful life events, marital status, family support, friend support, depressive symptoms, smoking, heavy drinking, and allostatic load. Unlike religiosity, religious support and religious coping were unrelated to leukocyte telomere length across models. Depressive symptoms, smoking, heavy drinking, and allostatic load failed to explain any of the association between religiosity and telomere length. To our knowledge, this is the first population-based study to link religious involvement and cellular aging. Although our data suggest that adults who frequently attend religious services, pray with regularity, and consider themselves to be religious tend to exhibit longer telomeres than those who attend and pray less frequently and do not consider themselves to be religious, additional research is needed to establish the mechanisms underlying this association. Copyright © 2016 Elsevier

  3. Paternal age and telomere length in twins: the germ stem cell selection paradigm

    PubMed Central

    Hjelmborg, Jacob B; Dalgård, Christine; Mangino, Massimo; Spector, Tim D; Halekoh, Ulrich; Möller, Sören; Kimura, Masayuki; Horvath, Kent; Kark, Jeremy D; Christensen, Kaare; Kyvik, Kirsten O; Aviv, Abraham

    2015-01-01

    Telomere length, a highly heritable trait, is longer in offspring of older fathers. This perplexing feature has been attributed to the longer telomeres in sperm of older men and it might be an ‘epigenetic’ mechanism through which paternal age plays a role in telomere length regulation in humans. Based on two independent (discovery and replication) twin studies, comprising 889 twin pairs, we show an increase in the resemblance of leukocyte telomere length between dizygotic twins of older fathers, which is not seen in monozygotic twins. This phenomenon might result from a paternal age-dependent germ stem cell selection process, whereby the selected stem cells have longer telomeres, are more homogenous with respect to telomere length, and share resistance to aging. PMID:25865872

  4. Rb1 haploinsufficiency promotes telomere attrition and radiation-induced genomic instability.

    PubMed

    Gonzalez-Vasconcellos, Iria; Anastasov, Natasa; Sanli-Bonazzi, Bahar; Klymenko, Olena; Atkinson, Michael J; Rosemann, Michael

    2013-07-15

    Germline mutations of the retinoblastoma gene (RB1) predispose to both sporadic and radiation-induced osteosarcoma, tumors characterized by high levels of genomic instability, and activation of alternative lengthening of telomeres. Mice with haploinsufficiency of the Rb1 gene in the osteoblastic lineage reiterate the radiation susceptibility to osteosarcoma seen in patients with germline RB1 mutations. We show that the susceptibility is accompanied by an increase in genomic instability, resulting from Rb1-dependent telomere erosion. Radiation exposure did not accelerate the rate of telomere loss but amplified the genomic instability resulting from the dysfunctional telomeres. These findings suggest that telomere maintenance is a noncanonical caretaker function of the retinoblastoma protein, such that its deficiency in cancer may potentiate DNA damage-induced carcinogenesis by promoting formation of chromosomal aberrations, rather than simply by affecting cell-cycle control. ©2013 AACR.

  5. Can meditation slow rate of cellular aging? Cognitive stress, mindfulness, and telomeres

    PubMed Central

    Epel, Elissa; Daubenmier, Jennifer; Moskowitz, Judith T.; Folkman, Susan; Blackburn, Elizabeth

    2010-01-01

    Understanding the malleable determinants of cellular aging is critical to understanding human longevity. Telomeres may provide a pathway for exploring this question. Telomeres are the protective caps at the ends of chromosomes. The length of telomeres offers insight into mitotic cell and possibly organismal longevity. Telomere length has now been linked to chronic stress exposure and depression. This raises the question of how might cellular aging be modulated by psychological functioning. We consider two psychological processes or states that are in opposition to one another--threat cognition and mindfulness--and their effects on cellular aging. Psychological stress cognitions, particularly appraisals of threat and ruminative thoughts, can lead to prolonged states of reactivity. In contrast, mindfulness meditation techniques appear to shift cognitive appraisals from threat to challenge, decrease ruminative thought, and reduce stress arousal. Mindfulness may also directly increase positive arousal states. We review data linking telomere length to cognitive stress and stress arousal and present new data linking cognitive appraisal to telomere length. Given the pattern of associations revealed so far, we propose that some forms of meditation may have salutary effects on telomere length by reducing cognitive stress and stress arousal and increasing positive states of mind and hormonal factors that may promote telomere maintenance. Aspects of this model are currently being tested in ongoing trials of mindfulness meditation. PMID:19735238

  6. Getting it done at the ends: Pif1 family DNA helicases and telomeres.

    PubMed

    Geronimo, Carly L; Zakian, Virginia A

    2016-08-01

    It is widely appreciated that the ends of linear DNA molecules cannot be fully replicated by the conventional replication apparatus. Less well known is that semi-conservative replication of telomeric DNA also presents problems for DNA replication. These problems likely arise from the atypical chromatin structure of telomeres, the GC-richness of telomeric DNA that makes it prone to forming DNA secondary structures, and from RNA-DNA hybrids, formed by transcripts of one or both DNA strands. Given the different aspects of telomeres that complicate their replication, it is not surprising that multiple DNA helicases promote replication of telomeric DNA. This review focuses on one such class of DNA helicases, the Pif1 family of 5'-3' DNA helicases. In budding and fission yeasts, Pif1 family helicases impact both telomerase-mediated and semi-conservative replication of telomeric DNA as well as recombination-mediated telomere lengthening. Copyright © 2016. Published by Elsevier B.V.

  7. Regulated expression of the lncRNA TERRA and its impact on telomere biology.

    PubMed

    Oliva-Rico, Diego; Herrera, Luis A

    2017-10-01

    The telomere protects against genomic instability by minimizing the accelerated end resection of the genetic material, a phenomenon that results in severe chromosome instability that could favor the transformation of a cell by enabling the emergence of tumor-promoting mutations. Some mechanisms that avoid this fate, such as capping and loop formation, have been very well characterized; however, telomeric non-coding transcripts, such as long non-coding RNAs (lncRNAs), should also be considered in this context because they play roles in the organization of telomere dynamics, involving processes such as replication, degradation, extension, and heterochromatin stabilization. Although the mechanism through which the expression of telomeric transcripts regulates telomere dynamics is not yet clear, a non-coding RNA component opens the research options in telomere biology and the impact that it can have on telomere-associated diseases such as cancer. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

  8. The telomeric sync model of speciation: species-wide telomere erosion triggers cycles of transposon-mediated genomic rearrangements, which underlie the saltatory appearance of nonadaptive characters

    NASA Astrophysics Data System (ADS)

    Stindl, Reinhard

    2014-03-01

    Charles Darwin knew that the fossil record is not overwhelmingly supportive of genetic and phenotypic gradualism; therefore, he developed the core of his theory on the basis of breeding experiments. Here, I present evidence for the existence of a cell biological mechanism that strongly points to the almost forgotten European concept of saltatory evolution of nonadaptive characters, which is in perfect agreement with the gaps in the fossil record. The standard model of chromosomal evolution has always been handicapped by a paradox, namely, how speciation can occur by spontaneous chromosomal rearrangements that are known to decrease the fertility of heterozygotes in a population. However, the hallmark of almost all closely related species is a differing chromosome complement and therefore chromosomal rearrangements seem to be crucial for speciation. Telomeres, the caps of eukaryotic chromosomes, erode in somatic tissues during life, but have been thought to remain stable in the germline of a species. Recently, a large human study spanning three healthy generations clearly found a cumulative telomere effect, which is indicative of transgenerational telomere erosion in the human species. The telomeric sync model of speciation presented here is based on telomere erosion between generations, which leads to identical fusions of chromosomes and triggers a transposon-mediated genomic repatterning in the germline of many individuals of a species. The phenotypic outcome of the telomere-triggered transposon activity is the saltatory appearance of nonadaptive characters simultaneously in many individuals. Transgenerational telomere erosion is therefore the material basis of aging at the species level.

  9. Inherited mutations in the helicase RTEL1 cause telomere dysfunction and Hoyeraal–Hreidarsson syndrome

    PubMed Central

    Deng, Zhong; Glousker, Galina; Molczan, Aliah; Fox, Alan J.; Lamm, Noa; Dheekollu, Jayaraju; Weizman, Orr-El; Schertzer, Michael; Wang, Zhuo; Vladimirova, Olga; Schug, Jonathan; Aker, Memet; Londoño-Vallejo, Arturo; Kaestner, Klaus H.; Lieberman, Paul M.; Tzfati, Yehuda

    2013-01-01

    Telomeres repress the DNA damage response at the natural chromosome ends to prevent cell-cycle arrest and maintain genome stability. Telomeres are elongated by telomerase in a tightly regulated manner to ensure a sufficient number of cell divisions throughout life, yet prevent unlimited cell division and cancer development. Hoyeraal–Hreidarsson syndrome (HHS) is characterized by accelerated telomere shortening and a broad range of pathologies, including bone marrow failure, immunodeficiency, and developmental defects. HHS-causing mutations have previously been found in telomerase and the shelterin component telomeric repeat binding factor 1 (TRF1)-interacting nuclear factor 2 (TIN2). We identified by whole-genome exome sequencing compound heterozygous mutations in four siblings affected with HHS, in the gene encoding the regulator of telomere elongation helicase 1 (RTEL1). Rtel1 was identified in mouse by its genetic association with telomere length. However, its mechanism of action and whether it regulates telomere length in human remained unknown. Lymphoblastoid cell lines obtained from a patient and from the healthy parents carrying heterozygous RTEL1 mutations displayed telomere shortening, fragility and fusion, and growth defects in culture. Ectopic expression of WT RTEL1 suppressed the telomere shortening and growth defect, confirming the causal role of the RTEL1 mutations in HHS and demonstrating the essential function of human RTEL1 in telomere protection and elongation. Finally, we show that human RTEL1 interacts with the shelterin protein TRF1, providing a potential recruitment mechanism of RTEL1 to telomeres. PMID:23959892

  10. Inherited mutations in the helicase RTEL1 cause telomere dysfunction and Hoyeraal-Hreidarsson syndrome.

    PubMed

    Deng, Zhong; Glousker, Galina; Molczan, Aliah; Fox, Alan J; Lamm, Noa; Dheekollu, Jayaraju; Weizman, Orr-El; Schertzer, Michael; Wang, Zhuo; Vladimirova, Olga; Schug, Jonathan; Aker, Memet; Londoño-Vallejo, Arturo; Kaestner, Klaus H; Lieberman, Paul M; Tzfati, Yehuda

    2013-09-03

    Telomeres repress the DNA damage response at the natural chromosome ends to prevent cell-cycle arrest and maintain genome stability. Telomeres are elongated by telomerase in a tightly regulated manner to ensure a sufficient number of cell divisions throughout life, yet prevent unlimited cell division and cancer development. Hoyeraal-Hreidarsson syndrome (HHS) is characterized by accelerated telomere shortening and a broad range of pathologies, including bone marrow failure, immunodeficiency, and developmental defects. HHS-causing mutations have previously been found in telomerase and the shelterin component telomeric repeat binding factor 1 (TRF1)-interacting nuclear factor 2 (TIN2). We identified by whole-genome exome sequencing compound heterozygous mutations in four siblings affected with HHS, in the gene encoding the regulator of telomere elongation helicase 1 (RTEL1). Rtel1 was identified in mouse by its genetic association with telomere length. However, its mechanism of action and whether it regulates telomere length in human remained unknown. Lymphoblastoid cell lines obtained from a patient and from the healthy parents carrying heterozygous RTEL1 mutations displayed telomere shortening, fragility and fusion, and growth defects in culture. Ectopic expression of WT RTEL1 suppressed the telomere shortening and growth defect, confirming the causal role of the RTEL1 mutations in HHS and demonstrating the essential function of human RTEL1 in telomere protection and elongation. Finally, we show that human RTEL1 interacts with the shelterin protein TRF1, providing a potential recruitment mechanism of RTEL1 to telomeres.

  11. Distinct TERB1 Domains Regulate Different Protein Interactions in Meiotic Telomere Movement.

    PubMed

    Zhang, Jingjing; Tu, Zhaowei; Watanabe, Yoshinori; Shibuya, Hiroki

    2017-11-14

    Meiotic telomeres attach to the nuclear envelope (NE) and drive the chromosome movement required for the pairing of homologous chromosomes. The meiosis-specific telomere proteins TERB1, TERB2, and MAJIN are required to regulate these events, but their assembly processes are largely unknown. Here, we developed a germ-cell-specific knockout mouse of the canonical telomere-binding protein TRF1 and revealed an essential role for TRF1 in directing the assembly of TERB1-TERB2-MAJIN. Further, we identified a TERB2 binding (T2B) domain in TERB1 that is dispensable for the TRF1-TERB1 interaction but is essential for the subsequent TERB1-TERB2 interaction and therefore for telomere attachment to the NE. Meanwhile, cohesin recruitment at telomeres, which is required for efficient telomere movement, is mediated by the MYB-like domain of TERB1, but not by TERB2-MAJIN. Our results reveal distinct protein interactions through various domains of TERB1, which enable the sequential assembly of the meiotic telomere complex for their movements. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  12. Physical activity and telomere length: Impact of aging and potential mechanisms of action

    PubMed Central

    Arsenis, Nicole C.; You, Tongjian; Ogawa, Elisa F.; Tinsley, Grant M.; Zuo, Li

    2017-01-01

    Telomeres protect the integrity of information-carrying DNA by serving as caps on the terminal portions of chromosomes. Telomere length decreases with aging, and this contributes to cell senescence. Recent evidence supports that telomere length of leukocytes and skeletal muscle cells may be positively associated with healthy living and inversely correlated with the risk of several age-related diseases, including cancer, cardiovascular disease, obesity, diabetes, chronic pain, and stress. In observational studies, higher levels of physical activity or exercise are related to longer telomere lengths in various populations, and athletes tend to have longer telomere lengths than non-athletes. This relationship is particularly evident in older individuals, suggesting a role of physical activity in combating the typical age-induced decrements in telomere length. To date, a small number of exercise interventions have been executed to examine the potential influence of chronic exercise on telomere length, but these studies have not fully established such relationship. Several potential mechanisms through which physical activity or exercise could affect telomere length are discussed, including changes in telomerase activity, oxidative stress, inflammation, and decreased skeletal muscle satellite cell content. Future research is needed to mechanistically examine the effects of various modalities of exercise on telomere length in middle-aged and older adults, as well as in specific clinical populations. PMID:28410238

  13. Nature vs nurture: interplay between the genetic control of telomere length and environmental factors.

    PubMed

    Harari, Yaniv; Romano, Gal-Hagit; Ungar, Lior; Kupiec, Martin

    2013-11-15

    Telomeres are nucleoprotein structures that cap the ends of the linear eukaryotic chromosomes, thus protecting their stability and integrity. They play important roles in DNA replication and repair and are central to our understanding of aging and cancer development. In rapidly dividing cells, telomere length is maintained by the activity of telomerase. About 400 TLM (telomere length maintenance) genes have been identified in yeast, as participants of an intricate homeostasis network that keeps telomere length constant. Two papers have recently shown that despite this extremely complex control, telomere length can be manipulated by external stimuli. These results have profound implications for our understanding of cellular homeostatic systems in general and of telomere length maintenance in particular. In addition, they point to the possibility of developing aging and cancer therapies based on telomere length manipulation.

  14. Cardiac telomere length in heart development, function, and disease.

    PubMed

    Booth, S A; Charchar, F J

    2017-07-01

    Telomeres are repetitive nucleoprotein structures at chromosome ends, and a decrease in the number of these repeats, known as a reduction in telomere length (TL), triggers cellular senescence and apoptosis. Heart disease, the worldwide leading cause of death, often results from the loss of cardiac cells, which could be explained by decreases in TL. Due to the cell-specific regulation of TL, this review focuses on studies that have measured telomeres in heart cells and critically assesses the relationship between cardiac TL and heart function. There are several lines of evidence that have identified rapid changes in cardiac TL during the onset and progression of heart disease as well as at critical stages of development. There are also many factors, such as the loss of telomeric proteins, oxidative stress, and hypoxia, that decrease cardiac TL and heart function. In contrast, antioxidants, calorie restriction, and exercise can prevent both cardiac telomere attrition and the progression of heart disease. TL in the heart is also indicative of proliferative potential and could facilitate the identification of cells suitable for cardiac rejuvenation. Although these findings highlight the involvement of TL in heart function, there are important questions regarding the validity of animal models, as well as several confounding factors, that need to be considered when interpreting results and planning future research. With these in mind, elucidating the telomeric mechanisms involved in heart development and the transition to disease holds promise to prevent cardiac dysfunction and potentiate regeneration after injury. Copyright © 2017 the American Physiological Society.

  15. Gender and telomere length: Systematic review and meta-analysis☆

    PubMed Central

    Gardner, Michael; Bann, David; Wiley, Laura; Cooper, Rachel; Hardy, Rebecca; Nitsch, Dorothea; Martin-Ruiz, Carmen; Shiels, Paul; Sayer, Avan Aihie; Barbieri, Michelangela; Bekaert, Sofie; Bischoff, Claus; Brooks-Wilson, Angela; Chen, Wei; Cooper, Cyrus; Christensen, Kaare; De Meyer, Tim; Deary, Ian; Der, Geoff; Roux, Ana Diez; Fitzpatrick, Annette; Hajat, Anjum; Halaschek-Wiener, Julius; Harris, Sarah; Hunt, Steven C.; Jagger, Carol; Jeon, Hyo-Sung; Kaplan, Robert; Kimura, Masayuki; Lansdorp, Peter; Li, Changyong; Maeda, Toyoki; Mangino, Massimo; Nawrot, Tim S.; Nilsson, Peter; Nordfjall, Katarina; Paolisso, Giuseppe; Ren, Fu; Riabowol, Karl; Robertson, Tony; Roos, Goran; Staessen, Jan A.; Spector, Tim; Tang, Nelson; Unryn, Brad; van der Harst, Pim; Woo, Jean; Xing, Chao; Yadegarfar, Mohammad E.; Park, Jae Yong; Young, Neal; Kuh, Diana; von Zglinicki, Thomas; Ben-Shlomo, Yoav

    2015-01-01

    Background It is widely believed that females have longer telomeres than males, although results from studies have been contradictory. Methods We carried out a systematic review and meta-analyses to test the hypothesis that in humans, females have longer telomeres than males and that this association becomes stronger with increasing age. Searches were conducted in EMBASE and MEDLINE (by November 2009) and additional datasets were obtained from study investigators. Eligible observational studies measured telomeres for both females and males of any age, had a minimum sample size of 100 and included participants not part of a diseased group. We calculated summary estimates using random-effects meta-analyses. Heterogeneity between studies was investigated using sub-group analysis and meta-regression. Results Meta-analyses from 36 cohorts (36,230 participants) showed that on average females had longer telomeres than males (standardised difference in telomere length between females and males 0.090, 95% CI 0.015, 0.166; age-adjusted). There was little evidence that these associations varied by age group (p = 1.00) or cell type (p = 0.29). However, the size of this difference did vary by measurement methods, with only Southern blot but neither real-time PCR nor Flow-FISH showing a significant difference. This difference was not associated with random measurement error. Conclusions Telomere length is longer in females than males, although this difference was not universally found in studies that did not use Southern blot methods. Further research on explanations for the methodological differences is required. PMID:24365661

  16. Gender and telomere length: systematic review and meta-analysis.

    PubMed

    Gardner, Michael; Bann, David; Wiley, Laura; Cooper, Rachel; Hardy, Rebecca; Nitsch, Dorothea; Martin-Ruiz, Carmen; Shiels, Paul; Sayer, Avan Aihie; Barbieri, Michelangela; Bekaert, Sofie; Bischoff, Claus; Brooks-Wilson, Angela; Chen, Wei; Cooper, Cyrus; Christensen, Kaare; De Meyer, Tim; Deary, Ian; Der, Geoff; Diez Roux, Ana; Fitzpatrick, Annette; Hajat, Anjum; Halaschek-Wiener, Julius; Harris, Sarah; Hunt, Steven C; Jagger, Carol; Jeon, Hyo-Sung; Kaplan, Robert; Kimura, Masayuki; Lansdorp, Peter; Li, Changyong; Maeda, Toyoki; Mangino, Massimo; Nawrot, Tim S; Nilsson, Peter; Nordfjall, Katarina; Paolisso, Giuseppe; Ren, Fu; Riabowol, Karl; Robertson, Tony; Roos, Goran; Staessen, Jan A; Spector, Tim; Tang, Nelson; Unryn, Brad; van der Harst, Pim; Woo, Jean; Xing, Chao; Yadegarfar, Mohammad E; Park, Jae Yong; Young, Neal; Kuh, Diana; von Zglinicki, Thomas; Ben-Shlomo, Yoav

    2014-03-01

    It is widely believed that females have longer telomeres than males, although results from studies have been contradictory. We carried out a systematic review and meta-analyses to test the hypothesis that in humans, females have longer telomeres than males and that this association becomes stronger with increasing age. Searches were conducted in EMBASE and MEDLINE (by November 2009) and additional datasets were obtained from study investigators. Eligible observational studies measured telomeres for both females and males of any age, had a minimum sample size of 100 and included participants not part of a diseased group. We calculated summary estimates using random-effects meta-analyses. Heterogeneity between studies was investigated using sub-group analysis and meta-regression. Meta-analyses from 36 cohorts (36,230 participants) showed that on average females had longer telomeres than males (standardised difference in telomere length between females and males 0.090, 95% CI 0.015, 0.166; age-adjusted). There was little evidence that these associations varied by age group (p=1.00) or cell type (p=0.29). However, the size of this difference did vary by measurement methods, with only Southern blot but neither real-time PCR nor Flow-FISH showing a significant difference. This difference was not associated with random measurement error. Telomere length is longer in females than males, although this difference was not universally found in studies that did not use Southern blot methods. Further research on explanations for the methodological differences is required. Copyright © 2013. Published by Elsevier Inc.

  17. Short telomere length is associated with impaired cognitive performance in European ancestry cohorts.

    PubMed

    Hägg, S; Zhan, Y; Karlsson, R; Gerritsen, L; Ploner, A; van der Lee, S J; Broer, L; Deelen, J; Marioni, R E; Wong, A; Lundquist, A; Zhu, G; Hansell, N K; Sillanpää, E; Fedko, I O; Amin, N A; Beekman, M; de Craen, A J M; Degerman, S; Harris, S E; Kan, K-J; Martin-Ruiz, C M; Montgomery, G W; Adolfsson, A N; Reynolds, C A; Samani, N J; Suchiman, H E D; Viljanen, A; von Zglinicki, T; Wright, M J; Hottenga, J-J; Boomsma, D I; Rantanen, T; Kaprio, J A; Nyholt, D R; Martin, N G; Nyberg, L; Adolfsson, R; Kuh, D; Starr, J M; Deary, I J; Slagboom, P E; van Duijn, C M; Codd, V; Pedersen, N L

    2017-04-18

    The association between telomere length (TL) dynamics on cognitive performance over the life-course is not well understood. This study meta-analyses observational and causal associations between TL and six cognitive traits, with stratifications on APOE genotype, in a Mendelian Randomization (MR) framework. Twelve European cohorts (N=17 052; mean age=59.2±8.8 years) provided results for associations between qPCR-measured TL (T/S-ratio scale) and general cognitive function, mini-mental state exam (MMSE), processing speed by digit symbol substitution test (DSST), visuospatial functioning, memory and executive functioning (STROOP). In addition, a genetic risk score (GRS) for TL including seven known genetic variants for TL was calculated, and used in associations with cognitive traits as outcomes in all cohorts. Observational analyses showed that longer telomeres were associated with better scores on DSST (β=0.051 per s.d.-increase of TL; 95% confidence interval (CI): 0.024, 0.077; P=0.0002), and MMSE (β=0.025; 95% CI: 0.002, 0.047; P=0.03), and faster STROOP (β=-0.053; 95% CI: -0.087, -0.018; P=0.003). Effects for DSST were stronger in APOE ɛ4 non-carriers (β=0.081; 95% CI: 0.045, 0.117; P=1.0 × 10 -5 ), whereas carriers performed better in STROOP (β=-0.074; 95% CI: -0.140, -0.009; P=0.03). Causal associations were found for STROOP only (β=-0.598 per s.d.-increase of TL; 95% CI: -1.125, -0.072; P=0.026), with a larger effect in ɛ4-carriers (β=-0.699; 95% CI: -1.330, -0.069; P=0.03). Two-sample replication analyses using CHARGE summary statistics showed causal effects between TL and general cognitive function and DSST, but not with STROOP. In conclusion, we suggest causal effects from longer TL on better cognitive performance, where APOE ɛ4-carriers might be at differential risk.

  18. Yeast hnRNP-related proteins contribute to the maintenance of telomeres

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee-Soety, Julia Y., E-mail: jlee04@sju.edu; Jones, Jennifer; MacGibeny, Margaret A.

    Highlights: Black-Right-Pointing-Pointer Yeast hnRNP-related proteins are able to prevent faster senescence in telomerase-null cells. Black-Right-Pointing-Pointer The conserved RRMs in Npl3 are important for telomere maintenance. Black-Right-Pointing-Pointer Human hnRNP A1 is unable to complement the lack of NPL3 in yeast. Black-Right-Pointing-Pointer Npl3 and Cbc2 may work as telomere capping proteins. -- Abstract: Telomeres protect the ends of linear chromosomes, which if eroded to a critical length can become uncapped and lead to replicative senescence. Telomerase maintains telomere length in some cells, but inappropriate expression facilitates the immortality of cancer cells. Recently, proteins involved in RNA processing and ribosome assembly, such asmore » hnRNP (heterogeneous nuclear ribonucleoprotein) A1, have been found to participate in telomere maintenance in mammals. The Saccharomyces cerevisiae protein Npl3 shares significant amino acid sequence similarities with hnRNP A1. We found that deleting NPL3 accelerated the senescence of telomerase null cells. The highly conserved RNA recognition motifs (RRM) in Npl3 appear to be important for preventing faster senescence. Npl3 preferentially binds telomere sequences in vitro, suggesting that Npl3 may affect telomeres directly. Despite similarities between the two proteins, human hnRNP A1 is unable to complement the lack of Npl3 to rescue accelerated senescence in tlc1 npl3 cells. Deletion of CBC2, which encodes another hnRNP-related protein that associates with Npl3, also accelerates senescence. Potential mechanisms by which hnRNP-related proteins maintain telomeres are discussed.« less

  19. Association between telomere length and diabetes mellitus: A meta-analysis.

    PubMed

    Wang, Jianfei; Dong, Xu; Cao, Li; Sun, Yangyang; Qiu, Yu; Zhang, Yi; Cao, Ruoqiong; Covasa, Mihai; Zhong, Li

    2016-12-01

    Objective We investigated the relationship between diabetes and telomere length by meta-analysis. Methods We searched five popular databases for articles published between 1990 and 2015 using "diabetes" and "telomere" as search terms. Data were processed with RevMan5, and random- or fixed-effects meta-analysis was applied. The effects of geographical region, diabetes type, body mass index (BMI), age and sex were examined. Funnel plots were applied to evaluate publication bias. Results Seventeen articles were obtained from 571 references. We identified a significant association between telomere length and diabetes mellitus (standardized mean difference [SMD]: -3.41; 95% confidence interval [CI]: -4.01, -2.80; heterogeneity, I 2  = 99%) by comparing 5575 patients with diabetes and 6349 healthy individuals. The pooled SMD by geographic region indicated a significant association between shortened telomere length and diabetes mellitus (SMD: -3.41; 95% CI: -4.01, -2.80; heterogeneity, I 2  = 99%). In addition, telomere length was significantly associated with age (SMD: -3.41; 95% CI: -4.01, -2.80), diabetes type (SMD: -3.41; 95% CI: -4.01, -2.80), BMI (SMD: -1.61; 95% CI: -1.98, -1.23) and sex (SMD: -4.94; 95% CI: -9.47, -0.40). Conclusions The study demonstrated a close relationship between diabetes mellitus and telomere length, which was influenced by region, age, diabetes type, BMI and sex.

  20. Leukocyte telomere length and marital status among middle-aged adults

    PubMed Central

    Mainous, Arch G.; Everett, Charles J.; Diaz, Vanessa A.; Baker, Richard; Mangino, Massimo; Codd, Veryan; Samani, Nilesh J.

    2011-01-01

    Background: being unmarried is associated with worse health and increased mortality risk. Telomere length has emerged as a marker for biological ageing but it is unclear how telomere length relates to marital status. Objective: to examine the relationship between telomere length and marital status in a sample of middle-aged adults. Design and subjects: cross-sectional analysis among 321 adults aged 40–64 years. Methods: telomere length was measured by PCR (T/S ratio). Participants provided information on healthy lifestyle activities including smoking, alcohol use, diet, exercise, obesity as well as social support. Results: participants married or living with a partner had a mean T/S ratio of 1.70 and those widowed, divorced, separated or never married had a mean T/S ratio of 1.58 in a model adjusted for age, gender and race/ethnicity (P < 0.001). When the analysis was further adjusted for diet, alcohol consumption, exercise, smoking, social support, poverty and obesity, persons married or living with a partner had a higher mean T/S ratio of 1.69 than their unmarried counterparts (1.59) (P = 0.004). Conclusions: these results indicate that unmarried individuals have shorter telomeres. This relationship between marital status and telomere length is independent of presumed benefits of marriage such as social support and a healthier lifestyle. PMID:20817935

  1. The human CTC1/STN1/TEN1 complex regulates telomere maintenance in ALT cancer cells.

    PubMed

    Huang, Chenhui; Jia, Pingping; Chastain, Megan; Shiva, Olga; Chai, Weihang

    2017-06-15

    Maintaining functional telomeres is important for long-term proliferation of cells. About 15% of cancer cells are telomerase-negative and activate the alternative-lengthening of telomeres (ALT) pathway to maintain their telomeres. Recent studies have shown that the human CTC1/STN1/TEN1 complex (CST) plays a multi-faceted role in telomere maintenance in telomerase-expressing cancer cells. However, the role of CST in telomere maintenance in ALT cells is unclear. Here, we report that human CST forms a functional complex localizing in the ALT-associated PML bodies (APBs) in ALT cells throughout the cell cycle. Suppression of CST induces telomere instabilities including telomere fragility and elevates telomeric DNA recombination, leading to telomere dysfunction. In addition, CST deficiency significantly diminishes the abundance of extrachromosomal circular telomere DNA known as C-circles and t-circles. Suppression of CST also results in multinucleation in ALT cells and impairs cell proliferation. Our findings imply that the CST complex plays an important role in regulating telomere maintenance in ALT cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Regulation of Telomere Homeostasis during Epstein-Barr virus Infection and Immortalization.

    PubMed

    Kamranvar, Siamak A; Masucci, Maria G

    2017-08-09

    The acquisition of unlimited proliferative potential is dependent on the activation of mechanisms for telomere maintenance, which counteracts telomere shortening and the consequent triggering of the DNA damage response, cell cycle arrest, and apoptosis. The capacity of Epstein Barr virus (EBV) to infect B-lymphocytes in vitro and transform the infected cells into autonomously proliferating immortal cell lines underlies the association of this human gamma-herpesvirus with a broad variety of lymphoid and epithelial cell malignancies. Current evidence suggests that both telomerase-dependent and -independent pathways of telomere elongation are activated in the infected cells during the early and late phases of virus-induced immortalization. Here we review the interaction of EBV with different components of the telomere maintenance machinery and the mechanisms by which the virus regulates telomere homeostasis in proliferating cells. We also discuss how these viral strategies may contribute to malignant transformation.

  3. Effects of Telomerase and Telomere Length on Epidermal Stem Cell Behavior

    NASA Astrophysics Data System (ADS)

    Flores, Ignacio; Cayuela, María L.; Blasco, María A.

    2005-08-01

    A key process in organ homeostasis is the mobilization of stem cells out of their niches. We show through analysis of mouse models that telomere length, as well as the catalytic component of telomerase, Tert, are critical determinants in the mobilization of epidermal stem cells. Telomere shortening inhibited mobilization of stem cells out of their niche, impaired hair growth, and resulted in suppression of stem cell proliferative capacity in vitro. In contrast, Tert overexpression in the absence of changes in telomere length promoted stem cell mobilization, hair growth, and stem cell proliferation in vitro. The effects of telomeres and telomerase on stem cell biology anticipate their role in cancer and aging.

  4. Impaired Telomere Maintenance and Decreased Canonical WNT Signaling but Normal Ribosome Biogenesis in Induced Pluripotent Stem Cells from X-Linked Dyskeratosis Congenita Patients.

    PubMed

    Gu, Bai-Wei; Apicella, Marisa; Mills, Jason; Fan, Jian-Meng; Reeves, Dara A; French, Deborah; Podsakoff, Gregory M; Bessler, Monica; Mason, Philip J

    2015-01-01

    Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome characterized by the presence of short telomeres at presentation. Mutations in ten different genes, whose products are involved in the telomere maintenance pathway, have been shown to cause DC. The X-linked form is the most common form of the disease and is caused by mutations in the gene DKC1, encoding the protein dyskerin. Dyskerin is required for the assembly and stability of telomerase and is also involved in ribosomal RNA (rRNA) processing where it converts specific uridines to pseudouridine. DC is thought to result from failure to maintain tissues, like blood, that are renewed by stem cell activity, but research into pathogenic mechanisms has been hampered by the difficulty of obtaining stem cells from patients. We reasoned that induced pluripotent stem (iPS) cells from X-linked DC patients may provide information about the mechanisms involved. Here we describe the production of iPS cells from DC patients with DKC1 mutations Q31E, A353V and ΔL37. In addition we constructed "corrected" lines with a copy of the wild type dyskerin cDNA expressed from the AAVS1 safe harbor locus. We show that in iPS cells with DKC1 mutations telomere maintenance is compromised with short telomere lengths and decreased telomerase activity. The degree to which telomere lengths are affected by expression of telomerase during reprograming, or with ectopic expression of wild type dyskerin, is variable. The recurrent mutation A353V shows the most severe effect on telomere maintenance. A353V cells but not Q31E or ΔL37 cells, are refractory to correction by expression of wild type DKC1 cDNA. Because dyskerin is involved in both telomere maintenance and ribosome biogenesis it has been postulated that defective ribosome biogenesis and translation may contribute to the disease phenotype. Evidence from mouse and zebra fish models has supported the involvement of ribosome biogenesis but primary cells from human

  5. Impaired Telomere Maintenance and Decreased Canonical WNT Signaling but Normal Ribosome Biogenesis in Induced Pluripotent Stem Cells from X-Linked Dyskeratosis Congenita Patients

    PubMed Central

    Gu, Bai-Wei; Apicella, Marisa; Mills, Jason; Fan, Jian-Meng; Reeves, Dara A.; French, Deborah; Podsakoff, Gregory M.; Bessler, Monica; Mason, Philip J.

    2015-01-01

    Dyskeratosis congenita (DC) is an inherited bone marrow failure syndrome characterized by the presence of short telomeres at presentation. Mutations in ten different genes, whose products are involved in the telomere maintenance pathway, have been shown to cause DC. The X-linked form is the most common form of the disease and is caused by mutations in the gene DKC1, encoding the protein dyskerin. Dyskerin is required for the assembly and stability of telomerase and is also involved in ribosomal RNA (rRNA) processing where it converts specific uridines to pseudouridine. DC is thought to result from failure to maintain tissues, like blood, that are renewed by stem cell activity, but research into pathogenic mechanisms has been hampered by the difficulty of obtaining stem cells from patients. We reasoned that induced pluripotent stem (iPS) cells from X-linked DC patients may provide information about the mechanisms involved. Here we describe the production of iPS cells from DC patients with DKC1 mutations Q31E, A353V and ΔL37. In addition we constructed “corrected” lines with a copy of the wild type dyskerin cDNA expressed from the AAVS1 safe harbor locus. We show that in iPS cells with DKC1 mutations telomere maintenance is compromised with short telomere lengths and decreased telomerase activity. The degree to which telomere lengths are affected by expression of telomerase during reprograming, or with ectopic expression of wild type dyskerin, is variable. The recurrent mutation A353V shows the most severe effect on telomere maintenance. A353V cells but not Q31E or ΔL37 cells, are refractory to correction by expression of wild type DKC1 cDNA. Because dyskerin is involved in both telomere maintenance and ribosome biogenesis it has been postulated that defective ribosome biogenesis and translation may contribute to the disease phenotype. Evidence from mouse and zebra fish models has supported the involvement of ribosome biogenesis but primary cells from human

  6. High plasma folate is negatively associated with leukocyte telomere length in Framingham Offspring cohort.

    PubMed

    Paul, Ligi; Jacques, Paul F; Aviv, Abraham; Vasan, Ramachandran S; D'Agostino, Ralph B; Levy, Daniel; Selhub, Jacob

    2015-03-01

    Shortening of telomeres, the protective structures at the ends of eukaryotic chromosomes, is associated with age-related pathologies. Telomere length is influenced by DNA integrity and DNA and histone methylation. Folate plays a role in providing precursors for nucleotides and methyl groups for methylation reactions and has the potential to influence telomere length. We determined the association between leukocyte telomere length and long-term plasma folate status (mean of 4 years) in Framingham Offspring Study (n = 1,044, females = 52.1 %, mean age 59 years) using data from samples collected before and after folic acid fortification. Leukocyte telomere length was determined by Southern analysis and fasting plasma folate concentration using microbiological assay. There was no significant positive association between long-term plasma folate and leukocyte telomere length among the Framingham Offspring Study participants perhaps due to their adequate folate status. While the leukocyte telomere length in the second quintile of plasma folate was longer than that in the first quintile, the difference was not statistically significant. The leukocyte telomere length of the individuals in the fifth quintile of plasma folate was shorter than that of those in the second quintile by 180 bp (P < 0.01). There was a linear decrease in leukocyte telomere length with higher plasma folate concentrations in the upper four quintiles of plasma folate (P for trend = 0.001). Multivitamin use was associated with shorter telomeres in this cohort (P = 0.015). High plasma folate status possibly resulting from high folic acid intake may interfere with the role of folate in maintaining telomere integrity.

  7. The human CTC1/STN1/TEN1 complex regulates telomere maintenance in ALT cancer cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang, Chenhui; Jia, Pingping; Chastain, Megan

    Maintaining functional telomeres is important for long-term proliferation of cells. About 15% of cancer cells are telomerase-negative and activate the alternative-lengthening of telomeres (ALT) pathway to maintain their telomeres. Recent studies have shown that the human CTC1/STN1/TEN1 complex (CST) plays a multi-faceted role in telomere maintenance in telomerase-expressing cancer cells. However, the role of CST in telomere maintenance in ALT cells is unclear. Here, we report that human CST forms a functional complex localizing in the ALT-associated PML bodies (APBs) in ALT cells throughout the cell cycle. Suppression of CST induces telomere instabilities including telomere fragility and elevates telomeric DNAmore » recombination, leading to telomere dysfunction. In addition, CST deficiency significantly diminishes the abundance of extrachromosomal circular telomere DNA known as C-circles and t-circles. Suppression of CST also results in multinucleation in ALT cells and impairs cell proliferation. Our findings imply that the CST complex plays an important role in regulating telomere maintenance in ALT cells. - Highlights: • CST localizes at telomeres and ALT-associated PML bodies in ALT cells throughout the cell cycle. • CST is important for promoting telomeric DNA replication in ALT cells. • CST deficiency decreases ECTR formation and increases T-SCE. • CST deficiency impairs ALT cell proliferation and results in multinucleation.« less

  8. Contributions of recombination and repair proteins to telomere maintenance in telomerase-positive and negative Ustilago maydis.

    PubMed

    Yu, Eun Young; Hsu, Min; Holloman, William K; Lue, Neal F

    2018-01-01

    Homologous recombination and repair factors are known to promote both telomere replication and recombination-based telomere extension. Herein, we address the diverse contributions of several recombination/repair proteins to telomere maintenance in Ustilago maydis, a fungus that bears strong resemblance to mammals with respect to telomere regulation and recombination mechanisms. In telomerase-positive U. maydis, deletion of rad51 and blm separately caused shortened but stably maintained telomeres, whereas deletion of both engendered similar telomere loss, suggesting that the repair proteins help to resolve similar problems in telomere replication. In telomerase-negative cells, the loss of Rad51 or Brh2 caused accelerated senescence and failure to generate survivors on semi-solid medium. However, slow growing survivors can be isolated through continuous liquid culturing, and these survivors exhibit type II-like as well as ALT-like telomere features. In contrast, the trt1Δ blmΔ double mutant gives rise to survivors as readily as the trt1Δ single mutant, and like the single mutant survivors, exhibit almost exclusively type I-like telomere features. In addition, we observed direct physical interactions between Blm and two telomere-binding proteins, which may thus recruit or regulate Blm at telomeres. Our findings provide the basis for further analyzing the interplays between telomerase, telomere replication, and telomere recombination. © 2017 John Wiley & Sons Ltd.

  9. Does Telomere Shortening Precede the Onset of Hypertension in Spontaneously Hypertensive Mice?

    PubMed

    Chiu, Christine L; Hearn, Nerissa L; Paine, Devin; Steiner, Nicole; Lind, Joanne M

    2016-10-01

    Telomere length is widely considered as a marker of biological aging. Clinical studies have reported associations between reduced telomere length and hypertension. The aim of this study was to compare telomere length in hypertensive and normotensive mice at pre-disease and established disease time points to determine whether telomere length differs between the strains before and after the onset of disease. Genomic DNA was extracted from kidney and heart tissues of 4-, 12-, and 20-week-old male hypertensive (BPH/2J) and normotensive (BPN/3J) mice. Relative telomere length (T/S) was measured using quantitative PCR. Age was inversely correlated with telomere length in both strains. In 4-week-old pre-hypertensive animals, no difference in T/S was observed between BPH/2J and BPN/3J animals in kidney or heart tissue (kidney p = 0.14, heart p = 0.06). Once the animals had established disease, at 12 and 20 weeks, BPH/2J mice had significantly shorter telomeres when compared to their age-matched controls in both kidney (12 weeks p < 0.001 and 20 weeks p = 0.004) and heart tissues (12 weeks p < 0.001 and 20 weeks p < 0.001). This is the first study to show that differences in telomere lengths between BPH/2J and BPN/3J mice occur after the development of hypertension and do not cause hypertension in the BPH/2J mice.

  10. ATRX represses alternative lengthening of telomeres

    PubMed Central

    Napier, Christine E.; Huschtscha, Lily I.; Harvey, Adam; Bower, Kylie; Noble, Jane R.; Hendrickson, Eric A.; Reddel, Roger R.

    2015-01-01

    The unlimited proliferation of cancer cells requires a mechanism to prevent telomere shortening. Alternative Lengthening of Telomeres (ALT) is an homologous recombination-mediated mechanism of telomere elongation used in tumors, including osteosarcomas, soft tissue sarcoma subtypes, and glial brain tumors. Mutations in the ATRX/DAXX chromatin remodeling complex have been reported in tumors and cell lines that use the ALT mechanism, suggesting that ATRX may be an ALT repressor. We show here that knockout or knockdown of ATRX in mortal cells or immortal telomerase-positive cells is insufficient to activate ALT. Notably, however, in SV40-transformed mortal fibroblasts ATRX loss results in either a significant increase in the proportion of cell lines activating ALT (instead of telomerase) or in a significant decrease in the time prior to ALT activation. These data indicate that loss of ATRX function cooperates with one or more as-yet unidentified genetic or epigenetic alterations to activate ALT. Moreover, transient ATRX expression in ALT-positive/ATRX-negative cells represses ALT activity. These data provide the first direct, functional evidence that ATRX represses ALT. PMID:26001292

  11. UNG protects B cells from AID-induced telomere loss

    PubMed Central

    Cortizas, Elena M.; Zahn, Astrid; Safavi, Shiva

    2016-01-01

    Activation-induced deaminase (AID) initiates antibody gene diversification by creating G:U mismatches in the immunoglobulin loci. However, AID also deaminates nonimmunoglobulin genes, and failure to faithfully repair these off-target lesions can cause B cell lymphoma. In this study, we identify a mechanism by which processing of G:U produced by AID at the telomeres can eliminate B cells at risk of genomic instability. We show that telomeres are off-target substrates of AID and that B cell proliferation depends on protective repair by uracil-DNA glycosylase (UNG). In contrast, in the absence of UNG activity, deleterious processing by mismatch repair leads to telomere loss and defective cell proliferation. Indeed, we show that UNG deficiency reduces B cell clonal expansion in the germinal center in mice and blocks the proliferation of tumor B cells expressing AID. We propose that AID-induced damage at telomeres acts as a fail-safe mechanism to limit the tumor promoting activity of AID when it overwhelms uracil excision repair. PMID:27697833

  12. Is telomere length a molecular marker of past thermal stress in wild fish?

    PubMed

    Debes, Paul V; Visse, Marko; Panda, Bineet; Ilmonen, Petteri; Vasemägi, Anti

    2016-11-01

    Telomeres protect eukaryotic chromosomes; variation in telomere length has been linked (primarily in homoeothermic animals) to variation in stress, cellular ageing and disease risk. Moreover, telomeres have been suggested to function as biomarker for quantifying past environmental stress, but studies in wild animals remain rare. Environmental stress, such as extreme environmental temperatures in poikilothermic animals, may result in oxidative stress that accelerates telomere attrition. However, growth, which may depend on temperature, can also contribute to telomere attrition. To test for associations between multitissue telomere length and past water temperature while accounting for the previous individual growth, we used quantitative PCR to analyse samples from 112 young-of-the-year brown trout from 10 natural rivers with average water temperature differences of up to 6°C (and an absolute maximum of 23°C). We found negative associations between relative telomere length (RTL) and both average river temperature and individual body size. We found no indication of RTL-temperature association differences among six tissues, but we did find indications for differences among the tissues for associations between RTL and body size; size trends, albeit nonsignificant in their differences, were strongest in muscle and weakest in fin. Although causal relationships among temperature, growth, oxidative stress, and cross-sectional telomere length remain largely unknown, our results indicate that telomere-length variation in a poikilothermic wild animal is associated with both past temperature and growth. © 2016 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

  13. Cell-free DNA and telomere length among women undergoing in vitro fertilization treatment.

    PubMed

    Czamanski-Cohen, J; Sarid, O; Cwikel, J; Douvdevani, A; Levitas, E; Lunenfeld, E; Har-Vardi, I

    2015-11-01

    The current research is aimed at finding potential non-invasive bio-markers that will help us learn more about the mechanisms at play in failed assisted reproduction treatment. This exploratory pilot study examined the relationship between cell-free DNA (CFD) in plasma and telomere length in lymphocytes among women undergoing in vitro fertilization (IVF) and compared telomere length and CFD levels to a healthy control group. Blood of 20 women undergoing IVF was collected at three time points during the IVF cycle. We assessed the relationship between CFD and telomere length as well as controlling for morning cortisol levels. We also collected blood of 10 healthy controls at two time points (luteal and follicular phases of the menstrual cycle) and compared mean telomere length, CFD, and cortisol levels between the IVF patients and healthy controls. The results revealed an inverse relationship between CFD levels and telomere lengths at several time points that remained significant even after controlling for cortisol levels. Women undergoing IVF had statistically significant higher levels of CFD and shorter telomeres compared to healthy controls. The relationship between telomere length and CFD should be further explored in larger studies in order to uncover potential mechanisms that cause both shortened telomere length and elevated CFD in women undergoing IVF.

  14. Large-scale parent–child comparison confirms a strong paternal influence on telomere length

    PubMed Central

    Nordfjäll, Katarina; Svenson, Ulrika; Norrback, Karl-Fredrik; Adolfsson, Rolf; Roos, Göran

    2010-01-01

    Telomere length is documented to have a hereditary component, and both paternal and X-linked inheritance have been proposed. We investigated blood cell telomere length in 962 individuals with an age range between 0 and 102 years. Telomere length correlations were analyzed between parent–child pairs in different age groups and between grandparent–grandchild pairs. A highly significant correlation between the father's and the child's telomere length was observed (r=0.454, P<0.001), independent of the sex of the offspring (father–son: r=0.465, P<0.001; father–daughter: r=0.484, P<0.001). For mothers, the correlations were weaker (mother–child: r=0.148, P=0.098; mother–son: r=0.080, P=0.561; mother–daughter: r=0.297, P=0.013). A positive telomere length correlation was also observed for grandparent–grandchild pairs (r=0.272, P=0.013). Our findings indicate that fathers contribute significantly stronger to the telomere length of the offspring compared with mothers (P=0.012), but we cannot exclude a maternal influence on the daughter's telomeres. Interestingly, the father–child correlations diminished with increasing age (P=0.022), suggesting that nonheritable factors have an impact on telomere length dynamics during life. PMID:19826452

  15. ZBTB48 is both a vertebrate telomere-binding protein and a transcriptional activator.

    PubMed

    Jahn, Arne; Rane, Grishma; Paszkowski-Rogacz, Maciej; Sayols, Sergi; Bluhm, Alina; Han, Chung-Ting; Draškovič, Irena; Londoño-Vallejo, José Arturo; Kumar, Alan Prem; Buchholz, Frank; Butter, Falk; Kappei, Dennis

    2017-06-01

    Telomeres constitute the ends of linear chromosomes and together with the shelterin complex form a structure essential for genome maintenance and stability. In addition to the constitutive binding of the shelterin complex, other direct, yet more transient interactions are mediated by the CST complex and HOT1/HMBOX1, while subtelomeric variant repeats are recognized by NR2C/F transcription factors. Recently, the Kruppel-like zinc finger protein ZBTB48/HKR3/TZAP has been described as a novel telomere-associated factor in the vertebrate lineage. Here, we show that ZBTB48 binds directly both to telomeric and to subtelomeric variant repeat sequences. ZBTB48 is found at telomeres of human cancer cells regardless of the mode of telomere maintenance and it acts as a negative regulator of telomere length. In addition to its telomeric function, we demonstrate through a combination of RNAseq, ChIPseq and expression proteomics experiments that ZBTB48 acts as a transcriptional activator on a small set of target genes, including mitochondrial fission process 1 (MTFP1). This discovery places ZBTB48 at the interface of telomere length regulation, transcriptional control and mitochondrial metabolism. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  16. Opposing impacts on healthspan and longevity by limiting dietary selenium in telomere dysfunctional mice.

    PubMed

    Wu, Ryan T; Cao, Lei; Mattson, Elliot; Witwer, Kenneth W; Cao, Jay; Zeng, Huawei; He, Xin; Combs, Gerald F; Cheng, Wen-Hsing

    2017-02-01

    Selenium (Se) is a trace metalloid essential for life, but its nutritional and physiological roles during the aging process remain elusive. While telomere attrition contributes to replicative senescence mainly through persistent DNA damage response, such an aging process is mitigated in mice with inherently long telomeres. Here, weanling third generation telomerase RNA component knockout mice carrying short telomeres were fed a Se-deficient basal diet or the diet supplemented with 0.15 ppm Se as sodium selenate to be nutritionally sufficient throughout their life. Dietary Se deprivation delayed wound healing and accelerated incidence of osteoporosis, gray hair, alopecia, and cataract, but surprisingly promoted longevity. Plasma microRNA profiling revealed a circulating signature of Se deprivation, and subsequent ontological analyses predicted dominant changes in metabolism. Consistent with this observation, dietary Se deprivation accelerated age-dependent declines in glucose tolerance, insulin sensitivity, and glucose-stimulated insulin production in the mice. Moreover, DNA damage and senescence responses were enhanced and Pdx1 and MafA mRNA expression were reduced in pancreas of the Se-deficient mice. Altogether, these results suggest a novel model of aging with conceptual advances, whereby Se at low levels may be considered a hormetic chemical and decouple healthspan and longevity. © 2016 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.

  17. Clinicopathological characteristics of TERT promoter mutation and telomere length in hepatocellular carcinoma.

    PubMed

    Lee, Hye Won; Park, Tae In; Jang, Se Young; Park, Soo Young; Park, Won-Jin; Jung, Soo-Jung; Lee, Jae-Ho

    2017-02-01

    Promoter mutations in telomerase reverse transcriptase (TERT) and telomere length have been studied in various tumors. In the present study, the frequency and clinical characteristics of TERT promoter mutation and telomere length were studied in hepatocellular carcinoma (HCC). TERT promoter mutation and telomere length were analyzed in 162 tumor samples of the patients with HCC by sequencing and real-time PCR, respectively. The TERT promoter mutation rate was 28.8% (46/160) in HCC and was associated with males (P = 0.027). The telomere length was not significantly different in the presence of a TERT promoter mutation but was shorter in high-grade tumor stages (P = 0.048). Survival analyses showed that poor overall survival was associated with longer telomere length (P = 0.013). However, the TERT promoter mutation did not have a prognostic value for HCC. Multivariate survival analyses demonstrated that the telomere length was an independent prognostic marker for poor overall survival (hazard ratio = 1.75, 95% confidence interval: 1.046-2.913, P = 0.033). These data demonstrated that TERT promoter mutation is a frequent event in HCC; however, telomere length, but not the presence of a TERT promoter mutation, might have potential value as a prognostic indicator of HCC.

  18. Quantitative interaction screen of telomeric repeat-containing RNA reveals novel TERRA regulators

    PubMed Central

    Scheibe, Marion; Arnoult, Nausica; Kappei, Dennis; Buchholz, Frank; Decottignies, Anabelle; Butter, Falk; Mann, Matthias

    2013-01-01

    Telomeres are actively transcribed into telomeric repeat-containing RNA (TERRA), which has been implicated in the regulation of telomere length and heterochromatin formation. Here, we applied quantitative mass spectrometry (MS)–based proteomics to obtain a high-confidence interactome of TERRA. Using SILAC-labeled nuclear cell lysates in an RNA pull-down experiment and two different salt conditions, we distinguished 115 proteins binding specifically to TERRA out of a large set of background binders. While TERRA binders identified in two previous studies showed little overlap, using quantitative mass spectrometry we obtained many candidates reported in these two studies. To test whether novel candidates found here are involved in TERRA regulation, we performed an esiRNA-based interference analysis for 15 of them. Knockdown of 10 genes encoding candidate proteins significantly affected total cellular levels of TERRA, and RNAi of five candidates perturbed TERRA recruitment to telomeres. Notably, depletion of SRRT/ARS2, involved in miRNA processing, up-regulated both total and telomere-bound TERRA. Conversely, knockdown of MORF4L2, a component of the NuA4 histone acetyltransferase complex, reduced TERRA levels both globally and for telomere-bound TERRA. We thus identified new proteins involved in the homeostasis and telomeric abundance of TERRA, extending our knowledge of TERRA regulation. PMID:23921659

  19. Modulation of telomere binding proteins: a future area of research for skin protection and anti-aging target.

    PubMed

    Imbert, Isabelle; Botto, Jean-Marie; Farra, Claude D; Domloge, Nouha

    2012-06-01

    Telomere shortening is considered as one of the main characteristics of cellular aging by limiting cellular division. Besides the fundamental advances through the discoveries of telomere and telomerase, which were recognized by a Nobel Prize, telomere protection remains an essential area of research. Recently, it was evidenced that studying the cross-talks between the proteins associated with telomere should provide a better understanding of the mechanistic basis for telomere-associated aging phenotypes. In this review, we discuss the current knowledge on telomere shortening, telomerase activity, and the essential role of telomere binding proteins in telomere stabilization and telomere-end protection. This review highlights the capacity of telomere binding proteins to limit cellular senescence and to maintain skin tissue homeostasis, which is of key importance to reduce accelerated tissue aging. Future studies addressing telomere protection and limitation of DNA damage response in human skin should include investigations on telomere binding proteins. As little is known about the expression of telomere binding proteins in human skin and modulation of their expression with aging, it remains an interesting field of skin research and a key area for future skin protection and anti-aging developments. © 2012 Wiley Periodicals, Inc.

  20. Do glucocorticoids mediate the link between environmental conditions and telomere dynamics in wild vertebrates? A review.

    PubMed

    Angelier, Frédéric; Costantini, David; Blévin, Pierre; Chastel, Olivier

    2018-01-15

    Following the discoveries of telomeres and of their implications in terms of health and ageing, there has been a growing interest into the study of telomere dynamics in wild vertebrates. Telomeres are repeated sequences of non-coding DNA located at the terminal ends of chromosomes and they play a major role in maintaining chromosome stability. Importantly, telomeres shorten over time and shorter telomeres seem to be related with lower survival in vertebrates. Because of this potential link with longevity, it is crucial to understand not only the ecological determinants of telomere dynamics but also the regulatory endocrine mechanisms that may mediate the effect of the environment on telomeres. In this paper, we review the relationships that link environmental conditions, glucocorticoids (GC, the main hormonal mediator of allostasis) and telomere length in vertebrates. First, we review current knowledge about the determinants of inter-individual variations in telomere length. We emphasize the potential strong impact of environmental stressors and predictable life-history events on telomere dynamics. Despite recent progress, we still lack crucial basic data to fully understand the costs of several life-history stages and biotic and abiotic factors on telomere length. Second, we review the link that exists between GCs, oxidative stress and telomere dynamics in vertebrates. Although circulating GC levels may be closely and functionally linked with telomere dynamics, data are still scarce and somewhat contradictory. Further laboratory and field studies are therefore needed not only to better assess the proximate link between GC levels and telomere dynamics, but also to ultimately understand to what extent GCs and telomere length could be informative to measure the fitness costs of specific life-history stages and environmental conditions. Finally, we highlight the importance of exploring the functional links that may exist between coping styles, the GC stress response

  1. The Role of Telomeric Repeat Binding Factor 1 (TRF1) in Telomere Maintenance and as a Potential Prognostic Indicator in Human Breast Cancer

    DTIC Science & Technology

    2006-04-01

    for Specific Aim #3 have yet been initiated, and are proceeding on schedule. The PhD candidate has completed her educational goals. 13 Appendix A ... LEVELS OF TELOMERE PROTEIN MRNAS ARE PREDICTIVE OF TELOMERE CONTENT IN HUMAN BREAST TUMORS Kimberly S. Butler, William C. Hines, Diana Roberts

  2. Effects of transcutaneous electrical stimulation (1 pulse/sec) through custom-made disposable surface electrodes covering Omura's ST36 area of both legs on normal cell telomeres, oncogen C-fosAb2, integrin alpha5beta1, chlamydia trachomatis, etc. in breast cancer & alzheimer patients.

    PubMed

    Omura, Yoshiaki; Chen, Yemeng; Lermand, Olivia; Jones, Marilyn; Duvvi, Harsha; Shimotsuura, Yasuhiro

    2010-01-01

    Our previous study indicated that when extremely reduced normal cell (NC) telomeres in various cancer patients are increased over 500 ng BDORT units, abnormally high cancer cell telomeres and cancer-related markers such as Oncogen C-fosAb2 (Onco.)& Integrin alpha5beta1 (Integ.), & 8-OH-dG as well as bacterial & viral infections, mercury, asbestos, chromium, & beta-amyloid (1-42) markedly reduced due to improved circulation & excretion of these substances in urine. Since 1995, we have been using press-needle stimulation of Omura's ST36 with 200x press-release procedure 4x a day, with significant improvements in various cancer patients. In this study, Transcutaneous Electrical Stimulation (TES) at 60 pulses/min, which is close to patient's heart rate, was given between Omura's ST36 of both legs of the breast cancer & Alzheimer's patients. After about 10 minutes of TES, NC telomeres increased from 1 yg (= 10-24 g) to 500-525 ng; Integ. reduced from 85-75 ng to 0.5 ng & Chlamydia trachomatis (CT) reduced from 4500-3500 ng to 0.5 ng. An additional 10 minutes TES increased NC telomeres to 800-875 ng, while Integ. reduced to 0.5 yg & CT became less than 0.1 yg. After a total 30 minutes of TES, NC telomeres increased to 1000-1200ng BDORT units, with decreases in Integ. and Onco. to less than 0.1 yg. CT reduced to < 0.1 yg. About 24 hours later, NC telomeres were still 300 ng & both Integ. and Onco. were 2.5 ng. CT was approximately 20 ng. In Alzheimer patient, abnormally high beta-Amyloid (1-42) of 7-12 ng markedly reduced to within normal value of less than 1.5 ng by 20-30 min TES. Stimulation beyond 30 minutes gradually reduced NC telomeres. TES pulse rate of 4 pulses/sec for the same patient initially increased NC telomere up to 750-950 ng BDORT units within 20 minutes, but when stimulation continued more than 20 min, NC telomeres rapidly reduced to -150 ng in less than 10 min of TES with reduced beneficial effects.

  3. RTEL1 is a replisome-associated helicase that promotes telomere and genome-wide replication.

    PubMed

    Vannier, Jean-Baptiste; Sandhu, Sumit; Petalcorin, Mark I R; Wu, Xiaoli; Nabi, Zinnatun; Ding, Hao; Boulton, Simon J

    2013-10-11

    Regulator of telomere length 1 (RTEL1) is an essential DNA helicase that disassembles telomere loops (T loops) and suppresses telomere fragility to maintain the integrity of chromosome ends. We established that RTEL1 also associates with the replisome through binding to proliferating cell nuclear antigen (PCNA). Mouse cells disrupted for the RTEL1-PCNA interaction (PIP mutant) exhibited accelerated senescence, replication fork instability, reduced replication fork extension rates, and increased origin usage. Although T-loop disassembly at telomeres was unaffected in the mutant cells, telomere replication was compromised, leading to fragile sites at telomeres. RTEL1-PIP mutant mice were viable, but loss of the RTEL1-PCNA interaction accelerated the onset of tumorigenesis in p53-deficient mice. We propose that RTEL1 plays a critical role in both telomere and genome-wide replication, which is crucial for genetic stability and tumor avoidance.

  4. Donor Telomere Length SAA

    Cancer.gov

    A new NCI study has found that, among patients with severe aplastic anemia who received a hematopoietic cell transplant from an unrelated donor, those whose donor white blood cells had longer telomeres had higher survival rates five-years after transplant

  5. Moderate-to-severe obstructive sleep apnea is associated with telomere lengthening.

    PubMed

    Polonis, Katarzyna; Somers, Virend K; Becari, Christiane; Covassin, Naima; Schulte, Phillip J; Druliner, Brooke R; Johnson, Ruth A; Narkiewicz, Krzysztof; Boardman, Lisa A; Singh, Prachi

    2017-11-01

    Obstructive sleep apnea (OSA) is associated with cardiometabolic diseases. Telomere shortening is linked to hypertension, diabetes mellitus, and cardiovascular diseases. Because these conditions are highly prevalent in OSA, we hypothesized that telomere length (TL) would be reduced in OSA patients. We identified 106 OSA and 104 non-OSA subjects who underwent polysomnography evaluation. Quantitative PCR was used to measure telomere length in genomic DNA isolated from peripheral blood samples. The association between OSA and TL was determined using unadjusted and adjusted linear models. There was no difference in TL between the OSA and non-OSA (control) group. However, we observed a J-shaped relationship between TL and OSA severity: the longest TL in moderate-to-severe OSA [4,918 ± 230 (SD) bp] and the shortest TL in mild OSA (4,735 ± 145 bp). Mean TL in moderate-to-severe OSA was significantly longer than in the control group after adjustment for age, sex, body mass index, hypertension, dyslipidemia, and depression (β = 96.0, 95% confidence interval: 15.4-176.6, P = 0.020). In conclusion, moderate-to-severe OSA is associated with telomere lengthening. Our findings support the idea that changes in TL are not unidirectional processes, such that telomere shortening occurs with age and disease but may be prolonged in moderate-to-severe OSA. NEW & NOTEWORTHY Here, we show that moderate-to-severe obstructive sleep apnea is associated with longer telomeres, independent of age and cardiovascular risk factors, challenging the hypothesis that telomere shortening is a unidirectional process related to age/disease. A better understanding of the mechanisms underlying telomere dynamics may identify targets for therapeutic intervention in cardiovascular aging/other chronic diseases. Copyright © 2017 the American Physiological Society.

  6. Telomere biology and telomerase mutations in cirrhotic patients with hepatocellular carcinoma

    PubMed Central

    Alves-Paiva, Raquel M.; Podlevsky, Joshua D.; Logeswaran, Dhenugen; Santana, Barbara A.; Teixeira, Andreza C.; Chen, Julian J.-L.; Calado, Rodrigo T.; Martinelli, Ana L. C.

    2017-01-01

    Telomeres are repetitive DNA sequences at linear chromosome termini, protecting chromosomes against end-to-end fusion and damage, providing chromosomal stability. Telomeres shorten with mitotic cellular division, but are maintained in cells with high proliferative capacity by telomerase. Loss-of-function mutations in telomere-maintenance genes are genetic risk factors for cirrhosis development in humans and murine models. Telomerase deficiency provokes accelerated telomere shortening and dysfunction, facilitating genomic instability and oncogenesis. Here we examined whether telomerase mutations and telomere shortening were associated with hepatocellular carcinoma (HCC) secondary to cirrhosis. Telomere length of peripheral blood leukocytes was measured by Southern blot and qPCR in 120 patients with HCC associated with cirrhosis and 261 healthy subjects. HCC patients were screened for telomerase gene variants (in TERT and TERC) by Sanger sequencing. Age-adjusted telomere length was comparable between HCC patients and healthy subjects by both Southern blot and qPCR. Four non-synonymous TERT heterozygous variants were identified in four unrelated patients, resulting in a significantly higher mutation carrier frequency (3.3%) in patients as compared to controls (p = 0.02). Three of the four variants (T726M, A1062T, and V1090M) were previously observed in patients with other telomere diseases (severe aplastic anemia, acute myeloid leukemia, and cirrhosis). A novel TERT variant, A243V, was identified in a 65-year-old male with advanced HCC and cirrhosis secondary to chronic hepatitis C virus (HCV) and alcohol ingestion, but direct assay measurements in vitro did not detect modulation of telomerase enzymatic activity or processivity. In summary, constitutional variants resulting in amino acid changes in the telomerase reverse transcriptase were found in a small proportion of patients with cirrhosis-associated HCC. PMID:28813500

  7. Telomere Length from Blood Cells and Breast Cancer Risk: Investigations in two case-control studies

    PubMed Central

    Zheng, Yun-Ling; Ambrosone, Christine; Byrne, Celia; Davis, Warren; Nesline, Mary; McCann, Susan E.

    2013-01-01

    Purpose Telomere dysfunction, which leads to genomic instability, is hypothesized to play a causal role in the development of breast cancer. However, the few epidemiologic studies that assessed the relationship between telomere length in blood cells and breast cancer risk have been inconsistent. We conducted two case-control studies to further understand the role of telomere length and breast cancer risk. Methods Overall telomere lengths were measured by telomere quantitative fluorescent in situ hybridization (TQ-FISH) and telomere quantitative real-time PCR (TQ-PCR). The associations between telomere length from blood leucocytes and risk of breast cancer were examine in two breast cancer case-control studies that were conducted at Roswell Park Cancer Institute (RPCI) and Lombardi Comprehensive Cancer Center (LCCC). Results Using the 50th percentile value in controls as a cut point, women who had shorter telomere length were not at significantly increased risk of breast cancer compared with women who had longer telomere length in the RPCI study (odds ratio [OR] = 1.34, 95% confidence interval [CI] = 0.84 to 2.12), in the LCCC study (OR = 1.18, 95% CI = 0.73 to 1.91), or in the combined RPCI and LCCC studies (OR = 1.23, 95% CI = 0.89 to 1.71). There was no significant dose-response relationship across quartiles of telomere length and no significant difference when comparing women in the lowest to highest quartile of telomere length. Conclusions Overall telomere length from blood leucocytes was not significantly associated with the risk of breast cancer. PMID:19543829

  8. Mechanisms of breast cancer risk in shift workers: association of telomere shortening with the duration and intensity of night work.

    PubMed

    Samulin Erdem, Johanna; Notø, Heidi Ødegaard; Skare, Øivind; Lie, Jenny-Anne S; Petersen-Øverleir, Marte; Reszka, Edyta; Pepłońska, Beata; Zienolddiny, Shanbeh

    2017-08-01

    Occupational factors such as shiftwork and especially night work that involves disruption of the circadian rhythm may contribute to increased breast cancer risk. Circadian disruption may also affect telomere length (TL). While short TL generally is associated with increased cancer risk, its association with breast cancer risk is inconclusive. We suggest that working schedules might be an important factor in assessment of effects of TL on breast cancer risk. Moreover, telomere shortening might be a potential mechanism for night work-related breast cancer. In this study, effects of shift work on TL and its association with breast cancer risk were investigated in a nested breast cancer case-control study of Norwegian nurses. TL was assessed by qPCR in DNA from 563 breast cancer patients and 619 controls. Here, we demonstrate that TL is affected by intensive night work schedules, as work with six consecutive night for a period of more than 5 years was associated with decreased telomere lengths (-3.18, 95% CI: -6.46 to -0.58, P = 0.016). Furthermore, telomere shortening is associated with increased breast cancer risk in workers with long periods of consecutive night shifts. Thus, nurses with longer telomere lengths had a lower risk for breast cancer if they had worked more than four (OR: 0.37, 95% CI: 0.16-0.79, P = 0.014) or five (OR: 0.31, 95% CI: 0.10-0.83, P = 0.029) consecutive night shifts for a period of 5 years or more. These data suggest that telomere shortening is associated with the duration and intensity of night work and may be a contributing factor for breast cancer risk among female shift workers. © 2017 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

  9. Postnatal telomere dysfunction induces cardiomyocyte cell-cycle arrest through p21 activation

    PubMed Central

    Aix, Esther; Gutiérrez-Gutiérrez, Óscar; Sánchez-Ferrer, Carlota; Aguado, Tania

    2016-01-01

    The molecular mechanisms that drive mammalian cardiomyocytes out of the cell cycle soon after birth remain largely unknown. Here, we identify telomere dysfunction as a critical physiological signal for cardiomyocyte cell-cycle arrest. We show that telomerase activity and cardiomyocyte telomere length decrease sharply in wild-type mouse hearts after birth, resulting in cardiomyocytes with dysfunctional telomeres and anaphase bridges and positive for the cell-cycle arrest protein p21. We further show that premature telomere dysfunction pushes cardiomyocytes out of the cell cycle. Cardiomyocytes from telomerase-deficient mice with dysfunctional telomeres (G3 Terc−/−) show precocious development of anaphase-bridge formation, p21 up-regulation, and binucleation. In line with these findings, the cardiomyocyte proliferative response after cardiac injury was lost in G3 Terc−/− newborns but rescued in G3 Terc−/−/p21−/− mice. These results reveal telomere dysfunction as a crucial signal for cardiomyocyte cell-cycle arrest after birth and suggest interventions to augment the regeneration capacity of mammalian hearts. PMID:27241915

  10. Telomere length in normal and neoplastic canine tissues.

    PubMed

    Cadile, Casey D; Kitchell, Barbara E; Newman, Rebecca G; Biller, Barbara J; Hetler, Elizabeth R

    2007-12-01

    To determine the mean telomere restriction fragment (TRF) length in normal and neoplastic canine tissues. 57 solid-tissue tumor specimens collected from client-owned dogs, 40 samples of normal tissue collected from 12 clinically normal dogs, and blood samples collected from 4 healthy blood donor dogs. Tumor specimens were collected from client-owned dogs during diagnostic or therapeutic procedures at the University of Illinois Veterinary Medical Teaching Hospital, whereas 40 normal tissue samples were collected from 12 control dogs. Telomere restriction fragment length was determined by use of an assay kit. A histologic diagnosis was provided for each tumor by personnel at the Veterinary Diagnostic Laboratory at the University of Illinois. Mean of the mean TRF length for 44 normal samples was 19.0 kilobases (kb; range, 15.4 to 21.4 kb), and the mean of the mean TRF length for 57 malignant tumors was 19.0 kb (range, 12.9 to 23.5 kb). Although the mean of the mean TRF length for tumors and normal tissues was identical, tumor samples had more variability in TRF length. Telomerase, which represents the main mechanism by which cancer cells achieve immortality, is an attractive therapeutic target. The ability to measure telomere length is crucial to monitoring the efficacy of telomerase inhibition. In contrast to many other mammalian species, the length of canine telomeres and the rate of telomeric DNA loss are similar to those reported in humans, making dogs a compelling choice for use in the study of human anti-telomerase strategies.

  11. Endonuclease-independent LINE-1 retrotransposition at mammalian telomeres.

    PubMed

    Morrish, Tammy A; Garcia-Perez, José Luis; Stamato, Thomas D; Taccioli, Guillermo E; Sekiguchi, JoAnn; Moran, John V

    2007-03-08

    Long interspersed element-1 (LINE-1 or L1) elements are abundant, non-long-terminal-repeat (non-LTR) retrotransposons that comprise approximately 17% of human DNA. The average human genome contains approximately 80-100 retrotransposition-competent L1s (ref. 2), and they mobilize by a process that uses both the L1 endonuclease and reverse transcriptase, termed target-site primed reverse transcription. We have previously reported an efficient, endonuclease-independent L1 retrotransposition pathway (EN(i)) in certain Chinese hamster ovary (CHO) cell lines that are defective in the non-homologous end-joining (NHEJ) pathway of DNA double-strand-break repair. Here we have characterized EN(i) retrotransposition events generated in V3 CHO cells, which are deficient in DNA-dependent protein kinase catalytic subunit (DNA-PKcs) activity and have both dysfunctional telomeres and an NHEJ defect. Notably, approximately 30% of EN(i) retrotransposition events insert in an orientation-specific manner adjacent to a perfect telomere repeat (5'-TTAGGG-3'). Similar insertions were not detected among EN(i) retrotransposition events generated in controls or in XR-1 CHO cells deficient for XRCC4, an NHEJ factor that is required for DNA ligation but has no known function in telomere maintenance. Furthermore, transient expression of a dominant-negative allele of human TRF2 (also called TERF2) in XRCC4-deficient XR-1 cells, which disrupts telomere capping, enables telomere-associated EN(i) retrotransposition events. These data indicate that L1s containing a disabled endonuclease can use dysfunctional telomeres as an integration substrate. The findings highlight similarities between the mechanism of EN(i) retrotransposition and the action of telomerase, because both processes can use a 3' OH for priming reverse transcription at either internal DNA lesions or chromosome ends. Thus, we propose that EN(i) retrotransposition is an ancestral mechanism of RNA-mediated DNA repair associated with non

  12. Telomere Organization in the Ligninolytic Basidiomycete Pleurotus ostreatus▿ †

    PubMed Central

    Pérez, Gúmer; Pangilinan, Jasmyn; Pisabarro, Antonio G.; Ramírez, Lucía

    2009-01-01

    Telomeres are structural and functional chromosome regions that are essential for the cell cycle to proceed normally. They are, however, difficult to map genetically and to identify in genome-wide sequence programs because of their structure and repetitive nature. We studied the telomeric and subtelomeric organization in the basidiomycete Pleurotus ostreatus using a combination of molecular and bioinformatics tools that permitted us to determine 19 out of the 22 telomeres expected in this fungus. The telomeric repeating unit in P. ostreatus is TTAGGG, and the numbers of repetitions of this unit range between 25 and 150. The mapping of the telomere restriction fragments to linkage groups 6 and 7 revealed polymorphisms compatible with those observed by pulsed field gel electrophoresis separation of the corresponding chromosomes. The subtelomeric regions in Pleurotus contain genes similar to those described in other eukaryotic systems. The presence of a cluster of laccase genes in chromosome 6 and a bipartite structure containing a Het-related protein and an alcohol dehydrogenase are especially relevant; this bipartite structure is characteristic of the Pezizomycotina fungi Neurospora crassa and Aspergillus terreus. As far as we know, this is the first report describing the presence of such structures in basidiomycetes and the location of a laccase gene cluster in the subtelomeric region, where, among others, species-specific genes allowing the organism to adapt rapidly to the environment usually map. PMID:19114509

  13. Analysis of the age of Panax ginseng based on telomere length and telomerase activity.

    PubMed

    Liang, Jiabei; Jiang, Chao; Peng, Huasheng; Shi, Qinghua; Guo, Xiang; Yuan, Yuan; Huang, Luqi

    2015-01-23

    Ginseng, which is the root of Panax ginseng (Araliaceae), has been used in Oriental medicine as a stimulant and dietary supplement for more than 7,000 years. Older ginseng plants are substantially more medically potent, but ginseng age can be simulated using unscrupulous cultivation practices. Telomeres progressively shorten with each cell division until they reach a critical length, at which point cells enter replicative senescence. However, in some cells, telomerase maintains telomere length. In this study, to determine whether telomere length reflects ginseng age and which tissue is best for such an analysis, we examined telomerase activity in the main roots, leaves, stems, secondary roots and seeds of ginseng plants of known age. Telomere length in the main root (approximately 1 cm below the rhizome) was found to be the best indicator of age. Telomeric terminal restriction fragment (TRF) lengths, which are indicators of telomere length, were determined for the main roots of plants of different ages through Southern hybridization analysis. Telomere length was shown to be positively correlated with plant age, and a simple mathematical model was formulated to describe the relationship between telomere length and age for P. ginseng.

  14. NEIL3 Repairs Telomere Damage during S Phase to Secure Chromosome Segregation at Mitosis.

    PubMed

    Zhou, Jia; Chan, Jany; Lambelé, Marie; Yusufzai, Timur; Stumpff, Jason; Opresko, Patricia L; Thali, Markus; Wallace, Susan S

    2017-08-29

    Oxidative damage to telomere DNA compromises telomere integrity. We recently reported that the DNA glycosylase NEIL3 preferentially repairs oxidative lesions in telomere sequences in vitro. Here, we show that loss of NEIL3 causes anaphase DNA bridging because of telomere dysfunction. NEIL3 expression increases during S phase and reaches maximal levels in late S/G2. NEIL3 co-localizes with TRF2 and associates with telomeres during S phase, and this association increases upon oxidative stress. Mechanistic studies reveal that NEIL3 binds to single-stranded DNA via its intrinsically disordered C terminus in a telomere-sequence-independent manner. Moreover, NEIL3 is recruited to telomeres through its interaction with TRF1, and this interaction enhances the enzymatic activity of purified NEIL3. Finally, we show that NEIL3 interacts with AP Endonuclease 1 (APE1) and the long-patch base excision repair proteins PCNA and FEN1. Taken together, we propose that NEIL3 protects genome stability through targeted repair of oxidative damage in telomeres during S/G2 phase. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

  15. The Effect on Melanoma Risk of Genes Previously Associated With Telomere Length

    PubMed Central

    Bishop, D. Timothy; Taylor, John C.; Hayward, Nicholas K.; Brossard, Myriam; Cust, Anne E.; Dunning, Alison M.; Lee, Jeffrey E.; Moses, Eric K.; Akslen, Lars A.; Andresen, Per A.; Avril, Marie-Françoise; Azizi, Esther; Scarrà, Giovanna Bianchi; Brown, Kevin M.; Dębniak, Tadeusz; Elder, David E.; Friedman, Eitan; Ghiorzo, Paola; Gillanders, Elizabeth M.; Goldstein, Alisa M.; Gruis, Nelleke A.; Hansson, Johan; Harland, Mark; Helsing, Per; Hočevar, Marko; Höiom, Veronica; Ingvar, Christian; Kanetsky, Peter A.; Landi, Maria Teresa; Lang, Julie; Lathrop, G. Mark; Lubiński, Jan; Mackie, Rona M.; Martin, Nicholas G.; Molven, Anders; Montgomery, Grant W.; Novaković, Srdjan; Olsson, Håkan; Puig, Susana; Puig-Butille, Joan Anton; Radford-Smith, Graham L.; Randerson-Moor, Juliette; van der Stoep, Nienke; van Doorn, Remco; Whiteman, David C.; MacGregor, Stuart; Pooley, Karen A.; Ward, Sarah V.; Mann, Graham J.; Amos, Christopher I.; Pharoah, Paul D. P.; Demenais, Florence; Law, Matthew H.; Newton Bishop, Julia A.; Barrett, Jennifer H.

    2014-01-01

    Telomere length has been associated with risk of many cancers, but results are inconsistent. Seven single nucleotide polymorphisms (SNPs) previously associated with mean leukocyte telomere length were either genotyped or well-imputed in 11108 case patients and 13933 control patients from Europe, Israel, the United States and Australia, four of the seven SNPs reached a P value under .05 (two-sided). A genetic score that predicts telomere length, derived from these seven SNPs, is strongly associated (P = 8.92x10-9, two-sided) with melanoma risk. This demonstrates that the previously observed association between longer telomere length and increased melanoma risk is not attributable to confounding via shared environmental effects (such as ultraviolet exposure) or reverse causality. We provide the first proof that multiple germline genetic determinants of telomere length influence cancer risk. PMID:25231748

  16. Telomere shortening in hematopoietic stem cell transplantation: a potential mechanism for late graft failure?

    PubMed

    Awaya, Norihiro; Baerlocher, Gabriela M; Manley, Thomas J; Sanders, Jean E; Mielcarek, Marco; Torok-Storb, Beverly; Lansdorp, Peter M

    2002-01-01

    Telomeres serve to maintain the structural integrity of chromosomes, yet each somatic cell division is associated with a decrease in telomere length. The cumulative decrease in telomere length can impose an upper limit for the number of cell divisions that can occur before a cell senesces. When studied in vitro with fibroblasts, this limit is referred to as the Hayflick limit and usually occurs after 40 to 80 cell doublings. In theory, a similar replicative potential in a hematopoietic stem cell could support hematopoiesis in a person for more than 100 years. However, stem cells differentiate, and the telomere length differs among chromosomes within a single cell, among cell types, and among age-matched individuals. This variation in telomere length raises the possibility that long-term hematopoiesis by transplanted stem cells could, depending on the telomere length of the engrafted stem cell and the proliferative demand to which it is subjected, reach a Hayflick limit during the life span of the patient. Although significant shortening of telomeres is reported to occur within the first year posttransplantation, as yet no evidence has indicated that this shortening is associated with marrow function. In this review, we summarize reports on telomere shortening in stem cell transplantation recipients and report 2 cases in which graft failure is associated with significant telomere shortening.

  17. Molecular architecture of classical cytological landmarks: Centromeres and telomeres

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Meyne, J.

    1994-11-01

    Both the human telomere repeat and the pericentromeric repeat sequence (GGAAT)n were isolated based on evolutionary conservation. Their isolation was based on the premise that chromosomal features as structurally and functionally important as telomeres and centromeres should be highly conserved. Both sequences were isolated by high stringency screening of a human repetitive DNA library with rodent repetitive DNA. The pHuR library (plasmid Human Repeat) used for this project was enriched for repetitive DNA by using a modification of the standard DNA library preparation method. Usually DNA for a library is cut with restriction enzymes, packaged, infected, and the library ismore » screened. A problem with this approach is that many tandem repeats don`t have any (or many) common restriction sites. Therefore, many of the repeat sequences will not be represented in the library because they are not restricted to a viable length for the vector used. To prepare the pHuR library, human DNA was mechanically sheared to a small size. These relatively short DNA fragments were denatured and then renatured to C{sub o}t 50. Theoretically only repetitive DNA sequences should renature under C{sub o}t 50 conditions. The single-stranded regions were digested using S1 nuclease, leaving the double-stranded, renatured repeat sequences.« less

  18. Physical activity and telomere biology: exploring the link with aging-related disease prevention.

    PubMed

    Ludlow, Andrew T; Roth, Stephen M

    2011-02-21

    Physical activity is associated with reduced risk of several age-related diseases as well as with increased longevity in both rodents and humans. Though these associations are well established, evidence of the molecular and cellular factors associated with reduced disease risk and increased longevity resulting from physical activity is sparse. A long-standing hypothesis of aging is the telomere hypothesis: as a cell divides, telomeres shorten resulting eventually in replicative senescence and an aged phenotype. Several reports have recently associated telomeres and telomere-related proteins to diseases associated with physical inactivity and aging including cardiovascular disease, insulin resistance, and hypertension. Interestingly several reports have also shown that longer telomeres are associated with higher physical activity levels, indicating a potential mechanistic link between physical activity, reduced age-related disease risk, and longevity. The primary purpose of this review is to discuss the potential importance of physical activity in telomere biology in the context of inactivity- and age-related diseases. A secondary purpose is to explore potential mechanisms and important avenues for future research in the field of telomeres and diseases associated with physical inactivity and aging.

  19. CRISPR-Cas9 Mediated Telomere Removal Leads to Mitochondrial Stress and Protein Aggregation.

    PubMed

    Kim, Hyojung; Ham, Sangwoo; Jo, Minkyung; Lee, Gum Hwa; Lee, Yun-Song; Shin, Joo-Ho; Lee, Yunjong

    2017-10-03

    Aging is considered the major risk factor for neurodegenerative diseases including Parkinson's disease (PD). Telomere shortening is associated with cellular senescence. In this regard, pharmacological or genetic inhibition of telomerase activity has been used to model cellular aging. Here, we employed CRISPR-Cas9 technology to instantly remove the telomere to induce aging in a neuroblastoma cell line. Expression of both Cas9 and guide RNA targeting telomere repeats ablated the telomere, leading to retardation of cell proliferation. Instant deletion of telomere in SH-SY5Y cells impaired mitochondrial function with diminished mitochondrial respiration and cell viability. Supporting the pathological relevance of cell aging by CRISPR-Cas9 mediated telomere removal, alterations were observed in the levels of PD-associated proteins including PTEN-induced putative kinase 1, peroxisome proliferator-activated receptor γ coactivator 1-α, nuclear respiratory factor 1, parkin, and aminoacyl tRNA synthetase complex interacting multifunctional protein 2. Significantly, α-synuclein expression in the background of telomere removal led to the enhancement of protein aggregation, suggesting positive feed-forward interaction between aging and PD pathogenesis. Collectively, our results demonstrate that CRISPR-Cas9 can be used to efficiently model cellular aging and PD.

  20. Nek7 Protects Telomeres from Oxidative DNA Damage by Phosphorylation and Stabilization of TRF1.

    PubMed

    Tan, Rong; Nakajima, Satoshi; Wang, Qun; Sun, Hongxiang; Xue, Jing; Wu, Jian; Hellwig, Sabine; Zeng, Xuemei; Yates, Nathan A; Smithgall, Thomas E; Lei, Ming; Jiang, Yu; Levine, Arthur S; Su, Bing; Lan, Li

    2017-03-02

    Telomeric repeat binding factor 1 (TRF1) is essential to the maintenance of telomere chromatin structure and integrity. However, how telomere integrity is maintained, especially in response to damage, remains poorly understood. Here, we identify Nek7, a member of the Never in Mitosis Gene A (NIMA) kinase family, as a regulator of telomere integrity. Nek7 is recruited to telomeres and stabilizes TRF1 at telomeres after damage in an ATM activation-dependent manner. Nek7 deficiency leads to telomere aberrations, long-lasting γH2AX and 53BP1 foci, and augmented cell death upon oxidative telomeric DNA damage. Mechanistically, Nek7 interacts with and phosphorylates TRF1 on Ser114, which prevents TRF1 from binding to Fbx4, an Skp1-Cul1-F box E3 ligase subunit, thereby alleviating proteasomal degradation of TRF1, leading to a stable association of TRF1 with Tin2 to form a shelterin complex. Our data reveal a mechanism of efficient protection of telomeres from damage through Nek7-dependent stabilization of TRF1. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Normal Telomere Length Maintenance in Saccharomyces cerevisiae Requires Nuclear Import of the Ever Shorter Telomeres 1 (Est1) Protein via the Importin Alpha Pathway

    PubMed Central

    Hawkins, Charlene

    2014-01-01

    The Est1 (ever shorter telomeres 1) protein is an essential component of yeast telomerase, a ribonucleoprotein complex that restores the repetitive sequences at chromosome ends (telomeres) that would otherwise be lost during DNA replication. Previous work has shown that the telomerase RNA component (TLC1) transits through the cytoplasm during telomerase biogenesis, but mechanisms of protein import have not been addressed. Here we identify three nuclear localization sequences (NLSs) in Est1p. Mutation of the most N-terminal NLS in the context of full-length Est1p reduces Est1p nuclear localization and causes telomere shortening—phenotypes that are rescued by fusion with the NLS from the simian virus 40 (SV40) large-T antigen. In contrast to that of the TLC1 RNA, Est1p nuclear import is facilitated by Srp1p, the yeast homolog of importin α. The reduction in telomere length observed at the semipermissive temperature in a srp1 mutant strain is rescued by increased Est1p expression, consistent with a defect in Est1p nuclear import. These studies suggest that at least two nuclear import pathways are required to achieve normal telomere length homeostasis in yeast. PMID:24906415

  2. Peripheral telomere length and hippocampal volume in adolescents with major depressive disorder.

    PubMed

    Henje Blom, E; Han, L K M; Connolly, C G; Ho, T C; Lin, J; LeWinn, K Z; Simmons, A N; Sacchet, M D; Mobayed, N; Luna, M E; Paulus, M; Epel, E S; Blackburn, E H; Wolkowitz, O M; Yang, T T

    2015-11-10

    Several studies have reported that adults with major depressive disorder have shorter telomere length and reduced hippocampal volumes. Moreover, studies of adult populations without major depressive disorder suggest a relationship between peripheral telomere length and hippocampal volume. However, the relationship of these findings in adolescents with major depressive disorder has yet to be explored. We examined whether adolescent major depressive disorder is associated with altered peripheral telomere length and hippocampal volume, and whether these measures relate to one another. In 54 unmedicated adolescents (13-18 years) with major depressive disorder and 63 well-matched healthy controls, telomere length was assessed from saliva using quantitative polymerase chain reaction methods, and bilateral hippocampal volumes were measured with magnetic resonance imaging. After adjusting for age and sex (and total brain volume in the hippocampal analysis), adolescents with major depressive disorder exhibited significantly shorter telomere length and significantly smaller right, but not left hippocampal volume. When corrected for age, sex, diagnostic group and total brain volume, telomere length was not significantly associated with left or right hippocampal volume, suggesting that these cellular and neural processes may be mechanistically distinct during adolescence. Our findings suggest that shortening of telomere length and reduction of hippocampal volume are already present in early-onset major depressive disorder and thus unlikely to be only a result of accumulated years of exposure to major depressive disorder.

  3. A cloned DNA segment from the telomeric region of human chromosome 4p is not detectably rearranged in Huntington disease patients

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pritchard, C.; Casher, D.; Myers, R.M.

    1990-09-01

    Genetic linkage studies have mapped the Huntington disease (HD) mutation to the distal region of the short arm of human chromosome 4. Analysis of recombination events in this region has produced contradictory locations for HD. One possible location is in the region distal to the D4S90 marker, which is located within 300 kilobases of the telomere. Other crossover events predict a more centromeric position for HD. Here the authors analyze the telomeric region of 4p in detail. Cloned DNA segments were derived from this region by utilizing a radiation-induced somatic cell hybrid as a source of DNA combined with preparativemore » pulsed-field gel electrophoresis to enrich for the telmoeric fraction. Additional DNA was obtained by using the cloned segments as multiple start points for cosmid walks. This strategy proved to be an effective method for cloning 250 kilobases of DNA in the region telomeric to D4S90. Hybridization analysis with the cloned DNA did not provide any evidence for the presence of rearrangements of 100 base pairs or greater in the DNA of individuals affected with HD. They also found no charge in the size or structure of the 4p telomere in these samples.« less

  4. RTEL1: an essential helicase for telomere maintenance and the regulation of homologous recombination

    PubMed Central

    Uringa, Evert-Jan; Youds, Jillian L.; Lisaingo, Kathleen; Lansdorp, Peter M.; Boulton, Simon J.

    2011-01-01

    Telomere maintenance and DNA repair are crucial processes that protect the genome against instability. RTEL1, an essential iron–sulfur cluster-containing helicase, is a dominant factor that controls telomere length in mice and is required for telomere integrity. In addition, RTEL1 promotes synthesis-dependent strand annealing to direct DNA double-strand breaks into non-crossover outcomes during mitotic repair and in meiosis. Here, we review the role of RTEL1 in telomere maintenance and homologous recombination and discuss models linking RTEL1’s enzymatic activity to its function in telomere maintenance and DNA repair. PMID:21097466

  5. RTEL1: an essential helicase for telomere maintenance and the regulation of homologous recombination.

    PubMed

    Uringa, Evert-Jan; Youds, Jillian L; Lisaingo, Kathleen; Lansdorp, Peter M; Boulton, Simon J

    2011-03-01

    Telomere maintenance and DNA repair are crucial processes that protect the genome against instability. RTEL1, an essential iron-sulfur cluster-containing helicase, is a dominant factor that controls telomere length in mice and is required for telomere integrity. In addition, RTEL1 promotes synthesis-dependent strand annealing to direct DNA double-strand breaks into non-crossover outcomes during mitotic repair and in meiosis. Here, we review the role of RTEL1 in telomere maintenance and homologous recombination and discuss models linking RTEL1's enzymatic activity to its function in telomere maintenance and DNA repair.

  6. The Role of the Telomere End Protection Complex in Telomere Main

    DTIC Science & Technology

    2003-06-01

    identification of putative substrates of ATM kinase family members. J Biol Chem, 1999. 274(53): p. 37538-43. 9. Lei, M., E.R. Podell , P. Baumann, and T.R. Cech...DNA self-recognition in the structure of Pot1 bound to telomeric single-stranded DNA. Nature, 2003. 426(6963): p. 198-203. 10. Lei, M., E.R. Podell

  7. Longer leukocyte telomere length in Costa Rica's Nicoyan Peninsula: A population-based study

    PubMed Central

    Rehkopf, David H; Dow, William H; Rosero-Bixby, Luis; Lin, Jue; Epel, Elissa S; Blackburn, Elizabeth H

    2013-01-01

    Studies in humans suggest that leukocyte telomere length may act as a marker of biological aging. We investigated whether individuals in the Nicoya region of Costa Rica, known for exceptional longevity, had longer telomere length than those in other parts of the country. After controlling for age, age squared, rurality, rainy season and gender, mean leukocyte telomere length in Nicoya was substantially longer (81 base pairs, p<0.05) than in other areas of Costa Rica, providing evidence of a biological pathway to which this notable longevity may be related. This relationship remains unchanged (79 base pairs, p<0.05) after statistically controlling for nineteen potential biological, dietary and social and demographic mediators. Thus the difference in mean leukocyte telomere length that characterizes this unique region does not appear to be explainable by traditional behavioral and biological risk factors. More detailed examination of mean leukocyte telomere length by age shows that the regional telomere length difference declines at older ages. PMID:23988653

  8. Reproducibility of telomere length assessment: an international collaborative study.

    PubMed

    Martin-Ruiz, Carmen M; Baird, Duncan; Roger, Laureline; Boukamp, Petra; Krunic, Damir; Cawthon, Richard; Dokter, Martin M; van der Harst, Pim; Bekaert, Sofie; de Meyer, Tim; Roos, Goran; Svenson, Ulrika; Codd, Veryan; Samani, Nilesh J; McGlynn, Liane; Shiels, Paul G; Pooley, Karen A; Dunning, Alison M; Cooper, Rachel; Wong, Andrew; Kingston, Andrew; von Zglinicki, Thomas

    2015-10-01

    Telomere length is a putative biomarker of ageing, morbidity and mortality. Its application is hampered by lack of widely applicable reference ranges and uncertainty regarding the present limits of measurement reproducibility within and between laboratories. We instigated an international collaborative study of telomere length assessment: 10 different laboratories, employing 3 different techniques [Southern blotting, single telomere length analysis (STELA) and real-time quantitative PCR (qPCR)] performed two rounds of fully blinded measurements on 10 human DNA samples per round to enable unbiased assessment of intra- and inter-batch variation between laboratories and techniques. Absolute results from different laboratories differed widely and could thus not be compared directly, but rankings of relative telomere lengths were highly correlated (correlation coefficients of 0.63-0.99). Intra-technique correlations were similar for Southern blotting and qPCR and were stronger than inter-technique ones. However, inter-laboratory coefficients of variation (CVs) averaged about 10% for Southern blotting and STELA and more than 20% for qPCR. This difference was compensated for by a higher dynamic range for the qPCR method as shown by equal variance after z-scoring. Technical variation per laboratory, measured as median of intra- and inter-batch CVs, ranged from 1.4% to 9.5%, with differences between laboratories only marginally significant (P = 0.06). Gel-based and PCR-based techniques were not different in accuracy. Intra- and inter-laboratory technical variation severely limits the usefulness of data pooling and excludes sharing of reference ranges between laboratories. We propose to establish a common set of physical telomere length standards to improve comparability of telomere length estimates between laboratories. © The Author 2014. Published by Oxford University Press on behalf of the International Epidemiological Association.

  9. Association between objectively measured physical activity, chronic stress and leukocyte telomere length.

    PubMed

    von Känel, Roland; Bruwer, Erna J; Hamer, Mark; de Ridder, J Hans; Malan, Leoné

    2017-10-01

    Physical activity (PA) attenuates chronic stress and age-related and cardiovascular disease risks, whereby potentially slowing telomere shortening. We aimed to study the association between seven-day objectively measured habitual PA, chronic stress and leukocyte telomere length. Study participants were African (N.=96) and Caucasian (N.=107) school teachers of the Sympathetic activity and Ambulatory Blood Pressure in Africans study. All lifestyle characteristics (including PA) were objectively measured. The general health questionnaire and serum cortisol were assessed as psychological and physical measures of chronic stress. Leukocyte telomere length was measured using the quantitative real-time polymerase chain reaction. Africans had significantly shorter telomeres (P<.0001) and greater psychological distress (P=0.001) than Caucasians, whereas no group difference was seen for cortisol levels. Higher age (ß=-0.28 [-0.40, -0.16, P≤0.000), higher alcohol consumption (ß=-0.21 [-0.36, -0.08], P=0.003) and increased central obesity (ß=-0.17 [-0.30, -0.03], P=0.017) were all significantly associated with shorter telomeres. Habitual PA of different intensity was not significantly associated with markers of chronic stress or telomere length. However, more time spent with light intensity PA time was significantly and independently correlated with lower waist circumference (r=-0.21, P=0.004); in turn, greater waist circumference was significantly associated shorter telomeres (β=-0.17 [-0.30, -0.03], P=0.017). Habitual PA of different intensity was not directly associated with markers of chronic stress and leukocyte telomere length in this biethnic cohort. However, our findings suggest that light intensity PA could contribute to lowered age-related disease risk and healthy ageing by facilitating maintenance of a normal waist circumference.

  10. An experimental demonstration that early-life competitive disadvantage accelerates telomere loss.

    PubMed

    Nettle, Daniel; Monaghan, Pat; Gillespie, Robert; Brilot, Ben; Bedford, Thomas; Bateson, Melissa

    2015-01-07

    Adverse experiences in early life can exert powerful delayed effects on adult survival and health. Telomere attrition is a potentially important mechanism in such effects. One source of early-life adversity is the stress caused by competitive disadvantage. Although previous avian experiments suggest that competitive disadvantage may accelerate telomere attrition, they do not clearly isolate the effects of competitive disadvantage from other sources of variation. Here, we present data from an experiment in European starlings (Sturnus vulgaris) that used cross-fostering to expose siblings to divergent early experience. Birds were assigned either to competitive advantage (being larger than their brood competitors) or competitive disadvantage (being smaller than their brood competitors) between days 3 and 12 post-hatching. Disadvantage did not affect weight gain, but it increased telomere attrition, leading to shorter telomere length in disadvantaged birds by day 12. There were no effects of disadvantage on oxidative damage as measured by plasma lipid peroxidation. We thus found strong evidence that early-life competitive disadvantage can accelerate telomere loss. This could lead to faster age-related deterioration and poorer health in later life.

  11. Cdc13 N-Terminal Dimerization DNA Binding and Telomere Length Regulation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    M Mitchell; J Smith; M Mason

    The essential yeast protein Cdc13 facilitates chromosome end replication by recruiting telomerase to telomeres, and together with its interacting partners Stn1 and Ten1, it protects chromosome ends from nucleolytic attack, thus contributing to genome integrity. Although Cdc13 has been studied extensively, the precise role of its N-terminal domain (Cdc13N) in telomere length regulation remains unclear. Here we present a structural, biochemical, and functional characterization of Cdc13N. The structure reveals that this domain comprises an oligonucleotide/oligosaccharide binding (OB) fold and is involved in Cdc13 dimerization. Biochemical data show that Cdc13N weakly binds long, single-stranded, telomeric DNA in a fashion that ismore » directly dependent on domain oligomerization. When introduced into full-length Cdc13 in vivo, point mutations that prevented Cdc13N dimerization or DNA binding caused telomere shortening or lengthening, respectively. The multiple DNA binding domains and dimeric nature of Cdc13 offer unique insights into how it coordinates the recruitment and regulation of telomerase access to the telomeres.« less

  12. The Analysis of Pendolino (peo) Mutants Reveals Differences in the Fusigenic Potential among Drosophila Telomeres

    PubMed Central

    Marzullo, Marta; Raffa, Grazia D.; Morciano, Patrizia; Raimondo, Domenico; Burla, Romina; Saggio, Isabella; Gatti, Maurizio

    2015-01-01

    Drosophila telomeres are sequence-independent structures that are maintained by transposition to chromosome ends of three specialized retroelements (HeT-A, TART and TAHRE; collectively designated as HTT) rather than telomerase activity. Fly telomeres are protected by the terminin complex (HOAP-HipHop-Moi-Ver) that localizes and functions exclusively at telomeres and by non-terminin proteins that do not serve telomere-specific functions. Although all Drosophila telomeres terminate with HTT arrays and are capped by terminin, they differ in the type of subtelomeric chromatin; the Y, XR, and 4L HTT are juxtaposed to constitutive heterochromatin, while the XL, 2L, 2R, 3L and 3R HTT are linked to the TAS repetitive sequences; the 4R HTT is associated with a chromatin that has features common to both euchromatin and heterochromatin. Here we show that mutations in pendolino (peo) cause telomeric fusions (TFs). The analysis of several peo mutant combinations showed that these TFs preferentially involve the Y, XR and 4th chromosome telomeres, a TF pattern never observed in the other 10 telomere-capping mutants so far characterized. peo encodes a non-terminin protein homologous to the E2 variant ubiquitin-conjugating enzymes. The Peo protein directly interacts with the terminin components, but peo mutations do not affect telomeric localization of HOAP, Moi, Ver and HP1a, suggesting that the peo-dependent telomere fusion phenotype is not due to loss of terminin from chromosome ends. peo mutants are also defective in DNA replication and PCNA recruitment. However, our results suggest that general defects in DNA replication are unable to induce TFs in Drosophila cells. We thus hypothesize that DNA replication in Peo-depleted cells results in specific fusigenic lesions concentrated in heterochromatin-associated telomeres. Alternatively, it is possible that Peo plays a dual function being independently required for DNA replication and telomere capping. PMID:26110638

  13. A stochastic model of cell replicative senescence based on telomere shortening, oxidative stress, and somatic mutations in nuclear and mitochondrial DNA.

    PubMed

    Sozou, P D; Kirkwood, T B

    2001-12-21

    Human diploid fibroblast cells can divide for only a limited number of times in vitro, a phenomenon known as replicative senescence or the Hayflick limit. Variability in doubling potential is observed within a clone of cells, and between two sister cells arising from a single mitotic division. This strongly suggests that the process by which cells become senescent is intrinsically stochastic. Among the various biochemical mechanisms that have been proposed to explain replicative senescence, particular interest has been focussed on the role of telomere reduction. In the absence of telomerase--an enzyme switched off in normal diploid fibro-blasts-cells lose telomeric DNA at each cell division. According to the telomere hypothesis of cell senescence, cells eventually reach a critically short telomere length and cell cycle arrest follows. In support of this concept, forced expression of telomerase in normal fibroblasts appears to prevent cell senescence. Nevertheless, the telomere hypothesis in its basic form has some difficulty in explaining the marked stochastic variations seen in the replicative lifespans of individual cells within a culture, and there is strong empirical and theoretical support for the concept that other kinds of damage may contribute to cellular ageing. We describe a stochastic network model of cell senescence in which a primary role is played by telomere reduction but in which other mechanisms (oxidative stress linked particularly to mitochondrial damage, and nuclear somatic mutations) also contribute. The model gives simulation results that are in good agreement with published data on intra-clonal variability in cell doubling potential and permits an analysis of how the various elements of the stochastic network interact. Such integrative models may aid in developing new experimental approaches aimed at unravelling the intrinsic complexity of the mechanisms contributing to human cell ageing. Copyright 2001 Academic Press.

  14. SA1 and TRF1 synergistically bind to telomeric DNA and promote DNA-DNA pairing

    NASA Astrophysics Data System (ADS)

    Wang, Hong; Lin, Jiangguo; Countryman, Preston; Pan, Hai; Parminder Kaur Team; Robert Riehn Team; Patricia Opresko Team; Jane Tao Team; Susan Smith Team

    Impaired telomere cohesion leads to increased aneuploidy and early onset of tumorigenesis. Cohesion is thought to occur through the entrapment of two DNA strands within tripartite cohesin ring(s), along with a fourth subunit (SA1/SA2). Surprisingly, cohesion rings are not essential for telomere cohesion, which instead requires SA1 and shelterin proteins including TRF1. However, neither this unique cohesion mechanism at telomeres or DNA-binding properties of SA1 is understood. Here, using single-molecule fluorescence imaging of quantum dot-labeled proteins on DNA we discover that while SA1 diffuses across multiple telomeric and non-telomeric regions, the diffusion mediated through its N-terminal domain is slower at telomeric regions. However, addition of TRF1 traps SA1 within telomeric regions, which form longer DNA-DNA pairing tracts than with TRF1 alone, as revealed by atomic force microscopy. Together, these experimental results and coarse-grained molecular dynamics simulations suggest that TRF1 and SA1 synergistically interact with DNA to support telomere cohesion without cohesin rings.

  15. Genomic Organization of the Drosophila Telomere RetrotransposableElements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    George, J.A.; DeBaryshe, P.G.; Traverse, K.L.

    2006-10-16

    The emerging sequence of the heterochromatic portion of the Drosophila melanogaster genome, with the most recent update of euchromatic sequence, gives the first genome-wide view of the chromosomal distribution of the telomeric retrotransposons, HeT-A, TART, and Tahre. As expected, these elements are entirely excluded from euchromatin, although sequence fragments of HeT-A and TART 3 untranslated regions are found in nontelomeric heterochromatin on the Y chromosome. The proximal ends of HeT-A/TART arrays appear to be a transition zone because only here do other transposable elements mix in the array. The sharp distinction between the distribution of telomeric elements and that ofmore » other transposable elements suggests that chromatin structure is important in telomere element localization. Measurements reported here show (1) D. melanogaster telomeres are very long, in the size range reported for inbred mouse strains (averaging 46 kb per chromosome end in Drosophila stock 2057). As in organisms with telomerase, their length varies depending on genotype. There is also slight under-replication in polytene nuclei. (2) Surprisingly, the relationship between the number of HeT-A and TART elements is not stochastic but is strongly correlated across stocks, supporting the idea that the two elements are interdependent. Although currently assembled portions of the HeT-A/TART arrays are from the most-proximal part of long arrays, {approx}61% of the total HeT-A sequence in these regions consists of intact, potentially active elements with little evidence of sequence decay, making it likely that the content of the telomere arrays turns over more extensively than has been thought.« less

  16. TERRA and hnRNPA1 orchestrate an RPA-to-POT1 switch on telomeric single-stranded DNA.

    PubMed

    Flynn, Rachel Litman; Centore, Richard C; O'Sullivan, Roderick J; Rai, Rekha; Tse, Alice; Songyang, Zhou; Chang, Sandy; Karlseder, Jan; Zou, Lee

    2011-03-24

    Maintenance of telomeres requires both DNA replication and telomere 'capping' by shelterin. These two processes use two single-stranded DNA (ssDNA)-binding proteins, replication protein A (RPA) and protection of telomeres 1 (POT1). Although RPA and POT1 each have a critical role at telomeres, how they function in concert is not clear. POT1 ablation leads to activation of the ataxia telangiectasia and Rad3-related (ATR) checkpoint kinase at telomeres, suggesting that POT1 antagonizes RPA binding to telomeric ssDNA. Unexpectedly, we found that purified POT1 and its functional partner TPP1 are unable to prevent RPA binding to telomeric ssDNA efficiently. In cell extracts, we identified a novel activity that specifically displaces RPA, but not POT1, from telomeric ssDNA. Using purified protein, here we show that the heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) recapitulates the RPA displacing activity. The RPA displacing activity is inhibited by the telomeric repeat-containing RNA (TERRA) in early S phase, but is then unleashed in late S phase when TERRA levels decline at telomeres. Interestingly, TERRA also promotes POT1 binding to telomeric ssDNA by removing hnRNPA1, suggesting that the re-accumulation of TERRA after S phase helps to complete the RPA-to-POT1 switch on telomeric ssDNA. Together, our data suggest that hnRNPA1, TERRA and POT1 act in concert to displace RPA from telomeric ssDNA after DNA replication, and promote telomere capping to preserve genomic integrity.

  17. Universal Algorithm for Identification of Fractional Brownian Motion. A Case of Telomere Subdiffusion

    PubMed Central

    Burnecki, Krzysztof; Kepten, Eldad; Janczura, Joanna; Bronshtein, Irena; Garini, Yuval; Weron, Aleksander

    2012-01-01

    We present a systematic statistical analysis of the recently measured individual trajectories of fluorescently labeled telomeres in the nucleus of living human cells. The experiments were performed in the U2OS cancer cell line. We propose an algorithm for identification of the telomere motion. By expanding the previously published data set, we are able to explore the dynamics in six time orders, a task not possible earlier. As a result, we establish a rigorous mathematical characterization of the stochastic process and identify the basic mathematical mechanisms behind the telomere motion. We find that the increments of the motion are stationary, Gaussian, ergodic, and even more chaotic—mixing. Moreover, the obtained memory parameter estimates, as well as the ensemble average mean square displacement reveal subdiffusive behavior at all time spans. All these findings statistically prove a fractional Brownian motion for the telomere trajectories, which is confirmed by a generalized p-variation test. Taking into account the biophysical nature of telomeres as monomers in the chromatin chain, we suggest polymer dynamics as a sufficient framework for their motion with no influence of other models. In addition, these results shed light on other studies of telomere motion and the alternative telomere lengthening mechanism. We hope that identification of these mechanisms will allow the development of a proper physical and biological model for telomere subdynamics. This array of tests can be easily implemented to other data sets to enable quick and accurate analysis of their statistical characteristics. PMID:23199912

  18. Body weight status and telomere length in U.S. middle-aged and older adults.

    PubMed

    An, Ruopeng; Yan, Hai

    Telomere length has been proposed as a biomarker of biological aging. This study examined the relationship between body weight status and telomere length in U.S. middle-aged and older adults. Nationally representative data (N=2749) came from the Health and Retirement Study. Linear regressions were performed to examine the relationship between baseline body weight status reported in 1992 and telomere length measured in 2008 in the overall sample and by sex and racial/ethnic groups, adjusted for individual characteristics. Baseline overweight (25kg/m 2 ≤body mass index [BMI]<30kg/m 2 ) and obesity (BMI≥30kg/m 2 ) status positively predicted telomere length 17 years later. Compared with their normal weight counterparts, telomere length ratio was on average 0.062 (95% confidence interval=0.016, 0.109) and 0.125 (0.048, 0.202) larger among overweight and obese adults, respectively. In comparison to women and racial/ethnic minorities, the estimated positive associations between overweight and obesity status and telomere length were more salient among men and non-Hispanic whites, respectively. The positive association between body weight status and telomere length found in this study was opposite to what existing biological model predicts, and could partially relate to the nonlinear relationship between body weight status and telomere length across age cohorts, and/or the lack of reliability of BMI as an indicator for adiposity in the older population. Large-scale longitudinal studies with baseline telomere length measures are warranted to replicate this study finding and explore the potential heterogeneous relationship between body weight status and telomere length. Copyright © 2016 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

  19. Cigarette smoking and telomere length: A systematic review of 84 studies and meta-analysis.

    PubMed

    Astuti, Yuliana; Wardhana, Ardyan; Watkins, Johnathan; Wulaningsih, Wahyu

    2017-10-01

    Cigarette smoking is a risk factor for ageing-related disease, but its association with biological ageing, indicated by telomere length, is unclear. We systematically reviewed evidence evaluating association between smoking status and telomere length. Searches were performed in MEDLINE (Ovid) and EMBASE (Ovid) databases, combining variation of keywords "smoking" and "telomere". Data was extracted for study characteristics and estimates for association between smoking and telomere length. Quality of studies was assessed with a risk of bias score, and publication bias was assessed with a funnel plot. I 2 test was used to observe heterogeneity. Meta-analysis was carried out to compare mean difference in telomere length by smoking status, and a dose-response approach was carried out for pack-years of smoking and telomere length. A sensitivity analysis was carried out to examine sources of heterogeneity. A total of 84 studies were included in the review, and 30 among them were included in our meta-analysis. Potential bias was addressed in half of included studies, and there was little evidence of small study bias. Telomere length was shorter among ever smokers compared to never smokers (summary standard mean difference [SMD]: -0.11 (95% CI -0.16 to -0.07)). Similarly, shorter telomere length was found among smokers compared to non-smokers, and among current smokers compared to never or former smokers. Dose-response meta-analysis suggested an inverse trend between pack-years of smoking and telomere length. However, heterogeneity among some analyses was observed. Shorter telomeres among ever smokers compared to those who never smoked may imply mechanisms linking tobacco smoke exposure to ageing-related disease. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  20. Arsenic Exposure through Drinking Water Is Associated with Longer Telomeres in Peripheral Blood

    PubMed Central

    2012-01-01

    Inorganic arsenic is a strong carcinogen, possibly by interaction with the telomere length. The aim of the study was to evaluate how chronic arsenic exposure from drinking water as well as the arsenic metabolism efficiency affect the individual telomere length and the expression of telomere-related genes. Two hundred two women with a wide range in exposure to arsenic via drinking water (3.5–200 μg/L) were recruited. Concentrations of arsenic metabolites in urine [inorganic arsenic (iAs), methylarsonic acid (MMA), and dimethylarsinic acid (DMA)] were measured. The relative telomere length in blood was measured by quantitative real-time polymerase chain reaction. Genotyping (N = 172) for eight SNPs in AS3MT and gene expression of telomere-related genes (in blood; N = 90) were performed. Urinary arsenic (sum of metabolites) was positively associated with telomere length (β = 0.65 × 10–4, 95% CI = 0.031 × 10–4–1.3 × 10–4, adjusted for age and BMI). Individuals with above median fractions of iAs and MMA showed significantly longer telomeres by increasing urinary arsenic (β = 1.0 × 10–4, 95% CI = 0.21 × 10–4–1.8 × 10–4 at high % iAs; β = 0.88 × 10–4 95% CI = 0.12 × 10–4–1.6 × 10–4 at high % MMA) than those below the median (p = 0.80 and 0.44, respectively). Similarly, carriers of the slow and more toxic metabolizing AS3MT haplotype showed stronger positive associations between arsenic exposure and telomere length, as compared to noncarriers (interaction urinary arsenic and haplotype p = 0.025). Urinary arsenic was positively correlated with the expression of telomerase reverse transcriptase (TERT, Spearman r = 0.22, p = 0.037), but no association was found between TERT expression and telomere length. Arsenic in drinking water influences the telomere length, and this may be a mechanism for its carcinogenicity. A faster and less toxic arsenic metabolism diminishes arsenic-related telomere elongation. PMID:22917110

  1. Paroxysmal nocturnal haemoglobinuria phenotype cells and leucocyte subset telomere length in childhood acquired aplastic anaemia.

    PubMed

    Tutelman, Perri R; Aubert, Geraldine; Milner, Ruth A; Dalal, Bakul I; Schultz, Kirk R; Deyell, Rebecca J

    2014-03-01

    The significance of paroxysmal nocturnal haemoglobinuria (PNH(pos) ) cells and leucocyte subset telomere lengths in paediatric aplastic anaemia (AA) is unknown. Among 22 children receiving immunosuppressive therapy (IST) for AA, 73% (16/22) were PNH(pos) , of whom 94% achieved at least a partial response (PR) to IST; 11/16 (69%) achieved complete response (CR). Only 2/6 (33%) PNH(neg) patients achieved PR. PNH(pos) patients were less likely to fail IST compared to PNH(neg) patients (odds ratio 0·033; 95% confidence interval 0·002-0·468; P = 0·012). Children with AA had short granulocyte (P = 7·8 × 10(-9) ), natural killer cell (P = 6·0 × 10(-4) ), naïve T lymphocyte (P = 0·002) and B lymphocyte (P = 0·005) telomeres compared to age-matched normative data. © 2013 John Wiley & Sons Ltd.

  2. Skin phenotypes can offer some insight about the association between telomere length and cancer susceptibility.

    PubMed

    Ribero, S; Mangino, M; Bataille, V

    2016-12-01

    The role of telomere biology in cancer has been studied for a wide variety of different cancers but the association with telomere length has been controversial. This is because some cancers have been found to be associated with longer telomeres in circulating white cells whilst other cancer types are more common in individuals with shorter telomeres. Hence, there has been some skepticism as to whether telomere length may be helpful in estimating cancer risk. For melanoma, however, results have been fairly consistent showing that longer telomeres are associated with an increased risk. This link was first discovered because of a link between longer telomeres and a high number of naevi. In contrast, for cutaneous squamous cell carcinomas, the relationship is reversed with higher risk in individuals with shorter telomeres. Differences in skin phenotypes with the presence of high number of naevi versus photoageing with solar elastosis and solar keratoses have already been valuable for dermatologists as the former phenotype is associated with melanoma whilst the latter is more common in patients with squamous cell carcinoma of the skin. The hypothesis is that the differences in cutaneous phenotypes already observed by dermatologists for skin cancers may, in fact, be useful as well for cancer prediction in general as it may reflect underlying telomere biology. This manuscript will address the evidence for links between telomere biology, skin phenotypes and cancer risk. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. CTC1-mediated C-strand fill-in is an essential step in telomere length maintenance

    PubMed Central

    Feng, Xuyang; Hsu, Shih-Jui; Kasbek, Christopher; Chaiken, Mary

    2017-01-01

    Abstract To prevent progressive telomere shortening as a result of conventional DNA replication, new telomeric DNA must be added onto the chromosome end. The de novo DNA synthesis involves elongation of the G-rich strand of the telomere by telomerase. In human cells, the CST complex (CTC1-STN1-TEN1) also functions in telomere replication. CST first aids in duplication of the telomeric dsDNA. Then after telomerase has extended the G-rich strand, CST facilitates fill-in synthesis of the complementary C-strand. Here, we analyze telomere structure after disruption of human CTC1 and demonstrate that functional CST is essential for telomere length maintenance due to its role in mediating C-strand fill-in. Removal of CTC1 results in elongation of the 3΄ overhang on the G-rich strand. This leads to accumulation of RPA and telomeric DNA damage signaling. G-overhang length increases with time after CTC1 disruption and at early times net G-strand growth is apparent, indicating telomerase-mediated G-strand extension. In contrast, C-strand length decreases continuously, indicating a deficiency in C-strand fill-in synthesis. The lack of C-strand maintenance leads to gradual shortening of the telomeric dsDNA, similar to that observed in cells lacking telomerase. Thus, telomerase-mediated G-strand extension and CST-mediated C-strand fill-in are equally important for telomere length maintenance. PMID:28334750

  4. Early-Life Telomere Dynamics Differ between the Sexes and Predict Growth in the Barn Swallow (Hirundo rustica)

    PubMed Central

    Parolini, Marco; Romano, Andrea; Khoriauli, Lela; Nergadze, Solomon G.; Caprioli, Manuela; Rubolini, Diego; Santagostino, Marco; Saino, Nicola; Giulotto, Elena

    2015-01-01

    Telomeres are conserved DNA-protein structures at the termini of eukaryotic chromosomes which contribute to maintenance of genome integrity, and their shortening leads to cell senescence, with negative consequences for organismal functions. Because telomere erosion is influenced by extrinsic and endogenous factors, telomere dynamics may provide a mechanistic basis for evolutionary and physiological trade-offs. Yet, knowledge of fundamental aspects of telomere biology under natural selection regimes, including sex- and context-dependent variation in early-life, and the covariation between telomere dynamics and growth, is scant. In this study of barn swallows (Hirundo rustica) we investigated the sex-dependent telomere erosion during nestling period, and the covariation between relative telomere length and body and plumage growth. Finally, we tested whether any covariation between growth traits and relative telomere length depends on the social environment, as influenced by sibling sex ratio. Relative telomere length declined on average over the period of nestling maximal growth rate (between 7 and 16 days of age) and differently covaried with initial relative telomere length in either sex. The frequency distribution of changes in relative telomere length was bimodal, with most nestlings decreasing and some increasing relative telomere length, but none of the offspring traits predicted the a posteriori identified group to which individual nestlings belonged. Tail and wing length increased with relative telomere length, but more steeply in males than females, and this relationship held both at the within- and among-broods levels. Moreover, the increase in plumage phenotypic values was steeper when the sex ratio of an individual’s siblings was female-biased. Our study provides evidence for telomere shortening during early life according to subtly different dynamics in either sex. Furthermore, it shows that the positive covariation between growth and relative telomere

  5. QTL mapping and candidate gene analysis of telomere length control factors in maize (Zea mays L.)

    USDA-ARS?s Scientific Manuscript database

    Telomere length is under genetic control and important for essential telomere functions. Failure to regulate telomere length homeostasis contributes to cancers and aging-related diseases in animals, but the effects of telomere length defects in plants remains poorly understood. To learn more about t...

  6. Identification of small molecules capable of regulating conformational changes of telomeric G-quadruplex

    NASA Astrophysics Data System (ADS)

    Chen, Shuo-Bin; Liu, Guo-Cai; Gu, Lian-Quan; Huang, Zhi-Shu; Tan, Jia-Heng

    2018-02-01

    Design of small molecules targeted at human telomeric G-quadruplex DNA is an extremely active research area. Interestingly, the telomeric G-quadruplex is a highly polymorphic structure. Changes in its conformation upon small molecule binding may be a powerful method to achieve a desired biological effect. However, the rational development of small molecules capable of regulating conformational change of telomeric G-quadruplex structures is still challenging. In this study, we developed a reliable ligand-based pharmacophore model based on isaindigotone derivatives with conformational change activity toward telomeric G-quadruplex DNA. Furthermore, virtual screening of database was conducted using this pharmacophore model and benzopyranopyrimidine derivatives in the database were identified as a strong inducer of the telomeric G-quadruplex DNA conformation, transforming it from hybrid-type structure to parallel structure.

  7. Systematic correlation of environmental exposure and physiological and self-reported behaviour factors with leukocyte telomere length.

    PubMed

    Patel, Chirag J; Manrai, Arjun K; Corona, Erik; Kohane, Isaac S

    2017-02-01

    It is hypothesized that environmental exposures and behaviour influence telomere length, an indicator of cellular ageing. We systematically associated 461 indicators of environmental exposures, physiology and self-reported behaviour with telomere length in data from the US National Health and Nutrition Examination Survey (NHANES) in 1999-2002. Further, we tested whether factors identified in the NHANES participants are also correlated with gene expression of telomere length modifying genes. We correlated 461 environmental exposures, behaviours and clinical variables with telomere length, using survey-weighted linear regression, adjusting for sex, age, age squared, race/ethnicity, poverty level, education and born outside the USA, and estimated the false discovery rate to adjust for multiple hypotheses. We conducted a secondary analysis to investigate the correlation between identified environmental variables and gene expression levels of telomere-associated genes in publicly available gene expression samples. After correlating 461 variables with telomere length, we found 22 variables significantly associated with telomere length after adjustment for multiple hypotheses. Of these varaibales, 14 were associated with longer telomeres, including biomarkers of polychlorinated biphenyls([PCBs; 0.1 to 0.2 standard deviation (SD) increase for 1 SD increase in PCB level, P  < 0.002] and a form of vitamin A, retinyl stearate. Eight variables associated with shorter telomeres, including biomarkers of cadmium, C-reactive protein and lack of physical activity. We could not conclude that PCBs are correlated with gene expression of telomere-associated genes. Both environmental exposures and chronic disease-related risk factors may play a role in telomere length. Our secondary analysis found no evidence of association between PCBs/smoking and gene expression of telomere-associated genes. All correlations between exposures, behaviours and clinical factors and changes in

  8. TRF1 and TRF2 use different mechanisms to find telomeric DNA but share a novel mechanism to search for protein partners at telomeres.

    PubMed

    Lin, Jiangguo; Countryman, Preston; Buncher, Noah; Kaur, Parminder; E, Longjiang; Zhang, Yiyun; Gibson, Greg; You, Changjiang; Watkins, Simon C; Piehler, Jacob; Opresko, Patricia L; Kad, Neil M; Wang, Hong

    2014-02-01

    Human telomeres are maintained by the shelterin protein complex in which TRF1 and TRF2 bind directly to duplex telomeric DNA. How these proteins find telomeric sequences among a genome of billions of base pairs and how they find protein partners to form the shelterin complex remains uncertain. Using single-molecule fluorescence imaging of quantum dot-labeled TRF1 and TRF2, we study how these proteins locate TTAGGG repeats on DNA tightropes. By virtue of its basic domain TRF2 performs an extensive 1D search on nontelomeric DNA, whereas TRF1's 1D search is limited. Unlike the stable and static associations observed for other proteins at specific binding sites, TRF proteins possess reduced binding stability marked by transient binding (∼ 9-17 s) and slow 1D diffusion on specific telomeric regions. These slow diffusion constants yield activation energy barriers to sliding ∼ 2.8-3.6 κ(B)T greater than those for nontelomeric DNA. We propose that the TRF proteins use 1D sliding to find protein partners and assemble the shelterin complex, which in turn stabilizes the interaction with specific telomeric DNA. This 'tag-team proofreading' represents a more general mechanism to ensure a specific set of proteins interact with each other on long repetitive specific DNA sequences without requiring external energy sources.

  9. Mutations in Ran system affected telomere silencing in Saccharomyces cerevisiae

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hayashi, Naoyuki; Department of Molecular Oncology, Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa 920-0934; Kobayashi, Masahiko

    The Ran GTPase system regulates the direction and timing of several cellular events, such as nuclear-cytosolic transport, centrosome formation, and nuclear envelope assembly in telophase. To gain insight into the Ran system's involvement in chromatin formation, we investigated gene silencing at the telomere in several mutants of the budding yeast Saccharomyces cerevisiae, which had defects in genes involved in the Ran system. A mutation of the RanGAP gene, rna1-1, caused reduced silencing at the telomere, and partial disruption of the nuclear Ran binding factor, yrb2-{delta}2, increased this silencing. The reduced telomere silencing in rna1-1 cells was suppressed by a highmore » dosage of the SIR3 gene or the SIT4 gene. Furthermore, hyperphosphorylated Sir3 protein accumulated in the rna1-1 mutant. These results suggest that RanGAP is required for the heterochromatin structure at the telomere in budding yeast.« less

  10. ERK1/2/MAPK pathway-dependent regulation of the telomeric factor TRF2

    PubMed Central

    Picco, Vincent; Coste, Isabelle; Giraud-Panis, Marie-Josèphe; Renno, Toufic; Gilson, Eric; Pagès, Gilles

    2016-01-01

    Telomere stability is a hallmark of immortalized cells, including cancer cells. While the telomere length is maintained in most cases by the telomerase, the activity of a protein complex called Shelterin is required to protect telomeres against unsuitable activation of the DNA damage response pathway. Within this complex, telomeric repeat binding factor 2 (TRF2) plays an essential role by blocking the ataxia telangiectasia-mutated protein (ATM) signaling pathway at telomeres and preventing chromosome end fusion. We showed that TRF2 was phosphorylated in vitro and in vivo on serine 323 by extracellular signal-regulated kinase (ERK1/2) in both normal and cancer cells. Moreover, TRF2 and activated ERK1/2 unexpectedly interacted in the cytoplasm of tumor cells and human tumor tissues. The expression of non-phosphorylatable forms of TRF2 in melanoma cells induced the DNA damage response, leading to growth arrest and tumor reversion. These findings revealed that the telomere stability is under direct control of one of the major pro-oncogenic signaling pathways (RAS/RAF/MEK/ERK) via TRF2 phosphorylation. PMID:27366950

  11. Telomere-surrounding regions are transcription-permissive 3D nuclear compartments in human cells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Quina, Ana Sofia; Instituto Gulbenkian de Ciencia, 2781-901 Oeiras; Parreira, Leonor

    2005-07-01

    Positioning of genes relative to nuclear heterochromatic compartments is thought to help regulate their transcriptional activity. Given that human subtelomeric regions are rich in highly expressed genes, we asked whether human telomeres are related to transcription-permissive nuclear compartments. To address this question, we investigated in the nuclei of normal human lymphocytes the spatial relations of two constitutively expressed genes (ACTB and RARA) and three nuclear transcripts (ACTB, IL2RA and TCRB) to telomeres and centromeres, as a function of gene activity and transcription levels. We observed that genes and gene transcripts locate close to telomere clusters and away from chromocenters uponmore » activation of transcription. These findings, together with the observation that SC35 domains, which are enriched in pre-mRNA processing factors, are in close proximity to telomeres, indicate that telomere-neighboring regions are permissive to gene expression in human cells. Therefore, the associations of telomeres observed in the interphase nucleus might contribute, as opposed to chromocenters, for the establishment of transcription-permissive 3D nuclear compartments.« less

  12. Solution structure of telomere binding domain of AtTRB2 derived from Arabidopsis thaliana

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yun, Ji-Hye; Lee, Won Kyung; Kim, Heeyoun

    Highlights: • We have determined solution structure of Myb domain of AtTRB2. • The Myb domain of AtTRB2 is located in the N-terminal region. • The Myb domain of AtTRB2 binds to plant telomeric DNA without fourth helix. • Helix 2 and 3 of the Myb domain of AtTRB2 are involved in DNA recognition. • AtTRB2 is a novel protein distinguished from other known plant TBP. - Abstract: Telomere homeostasis is regulated by telomere-associated proteins, and the Myb domain is well conserved for telomere binding. AtTRB2 is a member of the SMH (Single-Myb-Histone)-like family in Arabidopsis thaliana, having an N-terminalmore » Myb domain, which is responsible for DNA binding. The Myb domain of AtTRB2 contains three α-helices and loops for DNA binding, which is unusual given that other plant telomere-binding proteins have an additional fourth helix that is essential for DNA binding. To understand the structural role for telomeric DNA binding of AtTRB2, we determined the solution structure of the Myb domain of AtTRB2 (AtTRB2{sub 1–64}) using nuclear magnetic resonance (NMR) spectroscopy. In addition, the inter-molecular interaction between AtTRB2{sub 1–64} and telomeric DNA has been characterized by the electrophoretic mobility shift assay (EMSA) and NMR titration analyses for both plant (TTTAGGG)n and human (TTAGGG)n telomere sequences. Data revealed that Trp28, Arg29, and Val47 residues located in Helix 2 and Helix 3 are crucial for DNA binding, which are well conserved among other plant telomere binding proteins. We concluded that although AtTRB2 is devoid of the additional fourth helix in the Myb-extension domain, it is able to bind to plant telomeric repeat sequences as well as human telomeric repeat sequences.« less

  13. TRF2 Recruits RTEL1 to Telomeres in S Phase to Promote T-Loop Unwinding

    PubMed Central

    Sarek, Grzegorz; Vannier, Jean-Baptiste; Panier, Stephanie; Petrini, John H.J.; Boulton, Simon J.

    2015-01-01

    Summary The helicase RTEL1 promotes t-loop unwinding and suppresses telomere fragility to maintain the integrity of vertebrate telomeres. An interaction between RTEL1 and PCNA is important to prevent telomere fragility, but how RTEL1 engages with the telomere to promote t-loop unwinding is unclear. Here, we establish that the shelterin protein TRF2 recruits RTEL1 to telomeres in S phase, which is required to prevent catastrophic t-loop processing by structure-specific nucleases. We show that the TRF2-RTEL1 interaction is mediated by a metal-coordinating C4C4 motif in RTEL1, which is compromised by the Hoyeraal-Hreidarsson syndrome (HHS) mutation, RTEL1R1264H. Conversely, we define a TRF2I124D substitution mutation within the TRFH domain of TRF2, which eliminates RTEL1 binding and phenocopies the RTEL1R1264H mutation, giving rise to aberrant t-loop excision, telomere length heterogeneity, and loss of the telomere as a circle. These results implicate TRF2 in the recruitment of RTEL1 to facilitate t-loop disassembly at telomeres in S phase. PMID:25620558

  14. TRF2 recruits RTEL1 to telomeres in S phase to promote t-loop unwinding.

    PubMed

    Sarek, Grzegorz; Vannier, Jean-Baptiste; Panier, Stephanie; Petrini, John H J; Boulton, Simon J

    2015-02-19

    The helicase RTEL1 promotes t-loop unwinding and suppresses telomere fragility to maintain the integrity of vertebrate telomeres. An interaction between RTEL1 and PCNA is important to prevent telomere fragility, but how RTEL1 engages with the telomere to promote t-loop unwinding is unclear. Here, we establish that the shelterin protein TRF2 recruits RTEL1 to telomeres in S phase, which is required to prevent catastrophic t-loop processing by structure-specific nucleases. We show that the TRF2-RTEL1 interaction is mediated by a metal-coordinating C4C4 motif in RTEL1, which is compromised by the Hoyeraal-Hreidarsson syndrome (HHS) mutation, RTEL1(R1264H). Conversely, we define a TRF2(I124D) substitution mutation within the TRFH domain of TRF2, which eliminates RTEL1 binding and phenocopies the RTEL1(R1264H) mutation, giving rise to aberrant t-loop excision, telomere length heterogeneity, and loss of the telomere as a circle. These results implicate TRF2 in the recruitment of RTEL1 to facilitate t-loop disassembly at telomeres in S phase. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  15. Universal algorithm for identification of fractional Brownian motion. A case of telomere subdiffusion.

    PubMed

    Burnecki, Krzysztof; Kepten, Eldad; Janczura, Joanna; Bronshtein, Irena; Garini, Yuval; Weron, Aleksander

    2012-11-07

    We present a systematic statistical analysis of the recently measured individual trajectories of fluorescently labeled telomeres in the nucleus of living human cells. The experiments were performed in the U2OS cancer cell line. We propose an algorithm for identification of the telomere motion. By expanding the previously published data set, we are able to explore the dynamics in six time orders, a task not possible earlier. As a result, we establish a rigorous mathematical characterization of the stochastic process and identify the basic mathematical mechanisms behind the telomere motion. We find that the increments of the motion are stationary, Gaussian, ergodic, and even more chaotic--mixing. Moreover, the obtained memory parameter estimates, as well as the ensemble average mean square displacement reveal subdiffusive behavior at all time spans. All these findings statistically prove a fractional Brownian motion for the telomere trajectories, which is confirmed by a generalized p-variation test. Taking into account the biophysical nature of telomeres as monomers in the chromatin chain, we suggest polymer dynamics as a sufficient framework for their motion with no influence of other models. In addition, these results shed light on other studies of telomere motion and the alternative telomere lengthening mechanism. We hope that identification of these mechanisms will allow the development of a proper physical and biological model for telomere subdynamics. This array of tests can be easily implemented to other data sets to enable quick and accurate analysis of their statistical characteristics. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  16. Apollo, an Artemis-related nuclease, interacts with TRF2 and protects human telomeres in S phase.

    PubMed

    van Overbeek, Megan; de Lange, Titia

    2006-07-11

    Human chromosome ends are protected by shelterin, an abundant six-subunit protein complex that binds specifically to the telomeric-repeat sequences, regulates telomere length, and ensures that chromosome ends do not elicit a DNA-damage response (reviewed in). Using mass spectrometry of proteins associated with the shelterin component Rap1, we identified an SMN1/PSO2 nuclease family member that is closely related to Artemis. We refer to this protein as Apollo and report that Apollo has the ability to localize to telomeres through an interaction with the shelterin component TRF2. Although its low abundance at telomeres indicates that Apollo is not a core component of shelterin, Apollo knockdown with RNAi resulted in senescence and the activation of a DNA-damage signal at telomeres as evidenced by telomere-dysfunction-induced foci (TIFs). The TIFs occurred primarily in S phase, suggesting that Apollo contributes to a processing step associated with the replication of chromosome ends. Furthermore, some of the metaphase chromosomes showed two telomeric signals at single-chromatid ends, suggesting an aberrant telomere structure. We propose that the Artemis-like nuclease Apollo is a shelterin accessory factor required for the protection of telomeres during or after their replication.

  17. Examining the association between anthropometric parameters and telomere length and mortality risk

    PubMed Central

    Wu, Chen-Jung; Kao, Tung-Wei; Lin, Yuan-Yung; Liaw, Fang-Yih; Wu, Li-Wei; Chang, Yaw-Wen; Peng, Tao-Chun; Chen, Wei-Liang

    2017-01-01

    A shorter telomere length is associated with several systemic disorders. Telomere length may be an informative biomarker for the maintenance of the overall health status and mortality. There are a limited number of empirical studies concerning the effect of anthropometric parameters on telomere length. The data are derived from the National Health and Nutrition Examination Survey from 1999 to 2002. The primary outcomes of this study were to examine the potential relationships between the anthropometric indices and the telomere length, while secondary outcomes of this study was to investigate the association between different anthropometric indices and mortality risk. A significant positive correlation was noted between the mean telomere length and the thigh circumference (TC) and calf circumference (CC) in all designed models. Participants in the highest TC and CC quartiles tended to have a longer telomere length and lowered the hazards for all-cause mortality to 43% and 57%, respectively. Notably, the anthropometric indices involving the CC with higher values seemed to be surrogate markers for the reduction of the risk of all-cause, cardiovascular and malignancy-related mortality (all P < 0.05). The CCmay be a valuable tool to guide public health policy and a clinical prognostic indicator for the risk of mortality. PMID:28423661

  18. Examining the association between anthropometric parameters and telomere length and mortality risk.

    PubMed

    Wu, Chen-Jung; Kao, Tung-Wei; Lin, Yuan-Yung; Liaw, Fang-Yih; Wu, Li-Wei; Chang, Yaw-Wen; Peng, Tao-Chun; Chen, Wei-Liang

    2017-05-23

    A shorter telomere length is associated with several systemic disorders. Telomere length may be an informative biomarker for the maintenance of the overall health status and mortality. There are a limited number of empirical studies concerning the effect of anthropometric parameters on telomere length. The data are derived from the National Health and Nutrition Examination Survey from 1999 to 2002. The primary outcomes of this study were to examine the potential relationships between the anthropometric indices and the telomere length, while secondary outcomes of this study was to investigate the association between different anthropometric indices and mortality risk. A significant positive correlation was noted between the mean telomere length and the thigh circumference (TC) and calf circumference (CC) in all designed models. Participants in the highest TC and CC quartiles tended to have a longer telomere length and lowered the hazards for all-cause mortality to 43% and 57%, respectively. Notably, the anthropometric indices involving the CC with higher values seemed to be surrogate markers for the reduction of the risk of all-cause, cardiovascular and malignancy-related mortality (all P < 0.05). The CCmay be a valuable tool to guide public health policy and a clinical prognostic indicator for the risk of mortality.

  19. Telomere length variation in tumor cells and cancer‐associated fibroblasts: potential biomarker for hepatocellular carcinoma

    PubMed Central

    Ma, Li‐Jie; Wang, Xiao‐Ying; Duan, Meng; Liu, Long‐Zi; Shi, Jie‐Yi; Dong, Liang‐Qing; Yang, Liu‐Xiao; Wang, Zhi‐Chao; Ding, Zhen‐Bin; Ke, Ai‐Wu; Cao, Ya; Zhang, Xiao‐Ming; Zhou, Jian; Fan, Jia

    2017-01-01

    Abstract The role of telomere dysfunction and aberrant telomerase activities in hepatocellular carcinoma (HCC) has been overlooked for many years. This study aimed to delineate the variation and prognostic value of telomere length in HCC. Telomere‐specific fluorescence in situ hybridization (FISH) and qPCR were used to evaluate telomere length in HCC cell lines, tumor tissues, and isolated non‐tumor cells within the tumor. Significant telomere attrition was found in tumor cells and cancer‐associated fibroblasts (CAFs) compared to their normal counterparts, but not in intratumor leukocytes or bile duct epithelial cells. Clinical relevance and prognostic value of telomere length were investigated on tissue microarrays of 257 surgically treated HCC patients. Reduced intensity of telomere signals in tumor cells or CAFs correlated with larger tumor size and the presence of vascular invasion (p < 0.05). Shortened telomeres in tumor cells or CAFs associated with reduced survival and increased recurrence, and were identified as independent prognosticators for HCC patients (p < 0.05). These findings were validated in an independent HCC cohort of 371 HCC patients from The Cancer Genome Atlas (TCGA) database, confirming telomere attrition and its prognostic value in HCC. We also showed that telomerase reverse transcriptase promoter (TERTp) mutation correlated with telomere shortening in HCC. Telomere variation in tumor cells and non‐tumor cells within the tumor microenvironment of HCC was a valuable prognostic biomarker for this fatal malignancy. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland. PMID:28833123

  20. Telomere length variation in tumor cells and cancer-associated fibroblasts: potential biomarker for hepatocellular carcinoma.

    PubMed

    Ma, Li-Jie; Wang, Xiao-Ying; Duan, Meng; Liu, Long-Zi; Shi, Jie-Yi; Dong, Liang-Qing; Yang, Liu-Xiao; Wang, Zhi-Chao; Ding, Zhen-Bin; Ke, Ai-Wu; Cao, Ya; Zhang, Xiao-Ming; Zhou, Jian; Fan, Jia; Gao, Qiang

    2017-12-01

    The role of telomere dysfunction and aberrant telomerase activities in hepatocellular carcinoma (HCC) has been overlooked for many years. This study aimed to delineate the variation and prognostic value of telomere length in HCC. Telomere-specific fluorescence in situ hybridization (FISH) and qPCR were used to evaluate telomere length in HCC cell lines, tumor tissues, and isolated non-tumor cells within the tumor. Significant telomere attrition was found in tumor cells and cancer-associated fibroblasts (CAFs) compared to their normal counterparts, but not in intratumor leukocytes or bile duct epithelial cells. Clinical relevance and prognostic value of telomere length were investigated on tissue microarrays of 257 surgically treated HCC patients. Reduced intensity of telomere signals in tumor cells or CAFs correlated with larger tumor size and the presence of vascular invasion (p < 0.05). Shortened telomeres in tumor cells or CAFs associated with reduced survival and increased recurrence, and were identified as independent prognosticators for HCC patients (p < 0.05). These findings were validated in an independent HCC cohort of 371 HCC patients from The Cancer Genome Atlas (TCGA) database, confirming telomere attrition and its prognostic value in HCC. We also showed that telomerase reverse transcriptase promoter (TERTp) mutation correlated with telomere shortening in HCC. Telomere variation in tumor cells and non-tumor cells within the tumor microenvironment of HCC was a valuable prognostic biomarker for this fatal malignancy. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland. © 2017 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.