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Vertebrate reproductive science and technology
RESEARCH ARTICLE

Telomere length regulation during cloning, embryogenesis and ageing

S. Schaetzlein A and K. L. Rudolph A B
+ Author Affiliations
- Author Affiliations

A Department of Gastroenterology, Hepatology and Endocrinology, Medical School Hannover, Carl-Neuberg Str. 1, 30625 Hannover, Germany.

B Corresponding author. Email: rudolph.lenhard@mh-hannover.de

Reproduction, Fertility and Development 17(2) 85-96 https://doi.org/10.1071/RD04112
Submitted: 1 August 2004  Accepted: 1 October 2004   Published: 1 January 2005

Abstract

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.

Extra keywords: Pot1, telomerase, telomere binding proteins, TRF1, TRF2.


References

Achi, M. V. , Ravindranath, N. , and Dym, M. (2000). Telomere length in male germ cells is inversely correlated with telomerase activity. Biol. Reprod. 63, 591–598.
PubMed |

Allsopp, R. C. , Vaziri, H. , Patterson, C. , Goldstein, S. , Younglai, E. V. , Futcher, A. B. , Greider, C. W. , and Harley, C. B. (1992). Telomere length predicts replicative capacity of human fibroblasts. Proc. Natl Acad. Sci. USA 89, 10 114–10 118.


Baumann, P. , and Cech, T. R. (2001). Pot1, the putative telomere end-binding protein in fission yeast and humans. Science 292, 1171–1175.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Betts, D. H. , and King, W. A. (1999). Telomerase activity and telomere detection during early bovine development. Dev. Genet. 25, 397–403.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Betts, D. , Bordignon, V. , Hill, J. , Winger, Q. , Westhusin, M. , Smith, L. , and King, W. (2001). Reprogramming of telomerase activity and rebuilding of telomere length in cloned cattle. Proc. Natl Acad. Sci. USA 98, 1077–1082.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Bilaud, T. , Brun, C. , Ancelin, K. , Koering, C. E. , Laroche, T. , and Gilson, E. (1997). Telomeric localization of TRF2, a novel human telobox protein. Nat. Genet. 17, 236–239.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Blackburn, E. H. (1991). Telomeres. Trends Biochem. Sci. 16, 378–381.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Blackburn, E. H. (2001). Switching and signaling at the telomere. Cell 106, 661–673.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Blasco, M. A. , Funk, W. , Villeponteau, B. , and Greider, C. W. (1995). Functional characterization and developmental regulation of mouse telomerase RNA. Science 269, 1267–1270.
PubMed |

Blasco, M. A. , Lee, H. W. , Hande, M. P. , Samper, E. , Lansdorp, P. M. , DePinho, R. A. , and Greider, C. W. (1997a). Telomere shortening and tumor formation by mouse cells lacking telomerase RNA. Cell 91, 25–34.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Blasco, M. A. , Lee, H. W. , Rizen, M. , Hanahan, D. , DePinho, R. , and Greider, C. W. (1997b). Mouse models for the study of telomerase. Ciba Found. Symp. 211, 160–170.
PubMed |

Boulton, S. J. , and Jackson, S. P. (1998). Components of the Ku-dependent non-homologous end-joining pathway are involved in telomeric length maintenance and telomeric silencing. EMBO J. 17, 1819–1828.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Boultwood, J. , Fidler, C. , Shepherd, P. , Watkins, F. , and Snowball, J. , et al. (1999). Telomere length shortening is associated with disease evolution in chronic myelogenous leukemia. Am. J. Hematol. 61, 5–9.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Broccoli, D. , Smogorzewska, A. , Chong, L. , and de Lange, T. (1997). Human telomeres contain two distinct Myb-related proteins, TRF1 and TRF2. Nat. Genet. 17, 231–235.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Brown, E. J. , and Baltimore, D. (2000). ATR disruption leads to chromosomal fragmentation and early embryonic lethality. Genes Dev. 14, 397–402.
PubMed |

Brummendorf, T. H. , Holyoake, T. L. , Rufer, N. , Barnett, M. J. , Schulzer, M. , Eaves, C. J. , Eaves, A. C. , and Lansdorp, P. M. (2000). Prognostic implications of differences in telomere length between normal and malignant cells from patients with chronic myeloid leukemia measured by flow cytometry. Blood 95, 1883–1890.
PubMed |

Budiyanto, A. , Bito, T. , Kunisada, M. , Ashida, M. , Ichihashi, M. , and Ueda, M. (2003). Inhibition of the epidermal growth factor receptor suppresses telomerase activity in HSC-1 human cutaneous squamous cell carcinoma cells. J. Invest. Dermatol. 121, 1088–1094.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Burger, A. M. , Bibby, M. C. , and Double, J. A. (1997). Telomerase activity in normal and malignant mammalian tissues: feasibility of telomerase as a target for cancer chemotherapy. Br. J. Cancer 75, 516–522.
PubMed |

Cawthon, R. M. , Smith, K. R. , O’Brien, E. , Sivatchenko, A. , and Kerber, R. A. (2003). Association between telomere length in blood and mortality in people aged 60 years or older. Lancet 361, 393–395.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Chi, N. W. , and Lodish, H. F. (2000). Tankyrase is a Golgi-associated mitogen-activated protein kinase substrate that interacts with IRAP in GLUT4 vesicles. J. Biol. Chem. 275, 38 437–38 444.
Crossref | GoogleScholarGoogle Scholar |

Chiang, Y. J. , Hemann, M. T. , Hathcock, K. S. , Tessarollo, L. , Feigenbaum, L. , Hahn, W. C. , and Hodes, R. J. (2004). Expression of telomerase RNA template, but not telomerase reverse transcriptase, is limiting for telomere length maintenance in vivo. Mol. Cell. Biol. 24, 7024–7031.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Chong, L. , van Steensel, B. , Broccoli, D. , Erdjument-Bromage, H. , Hanish, J. , Tempst, P. , and de Lange, T. (1995). A human telomeric protein. Science 270, 1663–1667.
PubMed |

Clark, A. J. , Ferrier, P. , Aslam, S. , Burl, S. , Denning, C. , Wylie, D. , Ross, A. , de Sousa, P. , Wilmut, I. , and Cui, W. (2003). Proliferative lifespan is conserved after nuclear transfer. Nat. Cell Biol. 5, 535–538.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Colgin, L. M. , Baran, K. , Baumann, P. , Cech, T. R. , and Reddel, R. R. (2003). Human POT1 facilitates telomere elongation by telomerase. Curr. Biol. 13, 942–946.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Cook, B. D. , Dynek, J. N. , Chang, W. , Shostak, G. , and Smith, S. (2002). Role for the related poly(ADP-ribose) polymerases tankyrase 1 and 2 at human telomeres. Mol. Cell. Biol. 22, 332–342.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Counter, C. M. , Avilion, A. A. , LeFeuvre, C. E. , Stewart, N. G. , Greider, C. W. , Harley, C. B. , and Bacchetti, S. (1992). Telomere shortening associated with chromosome instability is arrested in immortal cells which express telomerase activity. EMBO J. 11, 1921–1929.
PubMed |

Counter, C. M. , Gupta, J. , Harley, C. B. , Leber, B. , and Bacchetti, S. (1995). Telomerase activity in normal leukocytes and in hematologic malignancies. Blood 85, 2315–2320.
PubMed |

d’Adda di Fagagna, F. , Hande, M. P. , Tong, W. M. , Roth, D. , Lansdorp, P. M. , Wang, Z. Q. , and Jackson, S. P. (2001). Effects of DNA nonhomologous end-joining factors on telomere length and chromosomal stability in mammalian cells. Curr. Biol. 11, 1192–1196.
Crossref | GoogleScholarGoogle Scholar | PubMed |

d’Adda di Fagagna, F. , Reaper, P. M. , Clay-Farrace, L. , Fiegler, H. , Carr, P. , Von Zglinicki, T. , Saretzki, G. , Carter, N. P. , and Jackson, S. P. (2003). A DNA damage checkpoint response in telomere-initiated senescence. Nature 426, 194–198.
Crossref | GoogleScholarGoogle Scholar | PubMed |

de Lange, T. (2002). Protection of mammalian telomeres. Oncogene 21, 532–540.
Crossref | GoogleScholarGoogle Scholar | PubMed |

de Lange, T. , Shiue, L. , Myers, R. M. , Cox, D. R. , Naylor, S. L. , Killery, A. M. , and Varmus, H. E. (1990). Structure and variability of human chromosome ends. Mol. Cell. Biol. 10, 518–527.
PubMed |

Dimri, G. P. , Lee, X. , Basile, G. , Acosta, M. , and Scott, G. , et al. (1995). A biomarker that identifies senescent human cells in culture and in aging skin in vivo. Proc. Natl Acad. Sci. USA 92, 9363–9367.
PubMed |

Ding, H. , Schertzer, M. , Wu, X. , Gertsenstein, M. , and Selig, S. , et al. (2004). Regulation of murine telomere length by Rtel: an essential gene encoding a helicase-like protein. Cell 117, 873–886.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Djojosubroto, M. W. , Choi, Y. S. , Lee, H. W. , and Rudolph, K. L. (2003). Telomeres and telomerase in aging, regeneration and cancer. Mol. Cells 15, 164–175.
PubMed |

Dokal, I. (2001). Dyskeratosis congenita. A disease of premature ageing. Lancet 358 (Suppl. 1), 27.
Crossref | GoogleScholarGoogle Scholar |

Feng, J. , Funk, W. D. , Wang, S. S. , Weinrich, S. L. , and Avilion, A. A. , et al. (1995). The RNA component of human telomerase. Science 269, 1236–1241.
PubMed |

Frenck, R. W. , Blackburn, E. H. , and Shannon, K. M. (1998). The rate of telomere sequence loss in human leukocytes varies with age. Proc. Natl Acad. Sci. USA 95, 5607–5610.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Garcia-Cao, M. , O’Sullivan, R. , Peters, A. H. F. M. , Jenuwein, T. , and Blasco, M. A. (2004). Epigenetic regulation of telomere length in mammalian cells by the Suv39h1 and Suv39h2 histone methyltransferases. Nat. Genet. 36, 94–99.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Gravel, S. , Larrivee, M. , Labrecque, P. , and Wellinger, R. J. (1998). Yeast Ku as a regulator of chromosomal DNA end structure. Science 280, 741–744.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Greenberg, R. A. , Allsopp, R. C. , Chin, L. , Morin, G. B. , and DePinho, R. A. (1998). Expression of mouse telomerase reverse transcriptase during development, differentiation and proliferation. Oncogene 16, 1723–1730.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Greenberg, R. A. , O’Hagan, R. C. , Deng, H. , Xiao, Q. , Hann, S. R. , Adams, R. R. , Lichtsteiner, S. , Chin, L. , Morin, G. B. , and DePinho, R. A. (1999). Telomerase reverse transcriptase gene is a direct target of c-Myc but is not functionally equivalent in cellular transformation. Oncogene 18, 1219–1226.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Greenwell, P. W. , Kronmal, S. L. , Porter, S. E. , Gassenhuber, J. , Obermaier, B. , and Petes, T. D. (1995). TEL1, a gene involved in controlling telomere length in S. cerevisiae, is homologous to the human ataxia telangiectasia gene. Cell 82, 823–829.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Greider, C. W. , and Blackburn, E. H. (1985). Identification of a specific telomere terminal transferase activity in Tetrahymena extracts. Cell 43, 405–413.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Greider, C. W. , and Blackburn, E. H. (1989). A telomeric sequence in the RNA of Tetrahymena telomerase required for telomere repeat synthesis. Nature 337, 331–337.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Griffith, J. D. , Comeau, L. , Rosenfield, S. , Stansel, R. M. , Bianchi, A. , Moss, H. , and de Lange, T. (1999). Mammalian telomeres end in a large duplex loop. Cell 97, 503–514.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Hande, M. P. , Samper, E. , Lansdorp, P. , and Blasco, M. A. (1999). Telomere length dynamics and chromosomal instability in cells derived from telomerase null mice. J. Cell Biol. 144, 589–601.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Hande, M. P. , Balajee, A. S. , Tchirkov, A. , Wynshaw-Boris, A. , and Lansdorp, P. M. (2001). Extra-chromosomal telomeric DNA in cells from Atm(−/−) mice and patients with ataxia-telangiectasia. Hum. Mol. Genet. 10, 519–528.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Harle-Bachor, C. , and Boukamp, P. (1996). Telomerase activity in the regenerative basal layer of the epidermis in human skin and in immortal and carcinoma-derived skin keratinocytes. Proc. Natl Acad. Sci. USA 93, 6476–6481.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Harley, C. B. , Futcher, A. B. , and Greider, C. W. (1990). Telomeres shorten during ageing of human fibroblasts. Nature 345, 458–460.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Henderson, E. R. , and Blackburn, E. H. (1989). An overhanging 3′ terminus is a conserved feature of telomeres. Mol. Cell. Biol. 9, 345–348.
PubMed |

Hiyama, K. , Hirai, Y. , Kyoizumi, S. , Akiyama, M. , Hiyama, E. , Piatyszek, M. A. , Shay, J. W. , Ishioka, S. , and Yamakido, M. (1995). Activation of telomerase in human lymphocytes and hematopoietic progenitor cells. J. Immunol. 155, 3711–3715.
PubMed |

Hiyama, E. , Hiyama, K. , Yokoyama, T. , and Shay, J. W. (2001). Immunohistochemical detection of telomerase (hTERT) protein in human cancer tissues and a subset of cells in normal tissues. Neoplasia 3, 17–26.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Hsu, H. L. , Gilley, D. , Blackburn, E. H. , and Chen, D. J. (1999). Ku is associated with the telomere in mammals. Proc. Natl Acad. Sci. USA 96, 12 454–12 458.
Crossref | GoogleScholarGoogle Scholar |

Jaco, I. , Munoz, P. , Goytisolo, F. , Wesoly, J. , Bailey, S. , Taccioli, G. , and Blasco, M. A. (2003). Role of mammalian Rad54 in telomere length maintenance. Mol. Cell. Biol. 23, 5572–5580.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Joeng, K. S. , Song, E. J. , Lee, K. J. , and Lee, J. (2004). Long lifespan in worms with long telomeric DNA. Nat. Genet. 36, 607–611.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Kaminker, P. G. , Kim, S. H. , Taylor, R. D. , Zebarjadian, Y. , Funk, W. D. , Morin, G. B. , Yaswen, P. , and Campisi, J. (2001). TANK2, a new TRF1-associated poly(ADP-ribose) polymerase, causes rapid induction of cell death upon overexpression. J. Biol. Chem. 276, 35 891–35 899.
Crossref | GoogleScholarGoogle Scholar |

Karlseder, J. , Broccoli, D. , Dai, Y. , Hardy, S. , and de Lange, T. (1999). p53- and ATM-dependent apoptosis induced by telomeres lacking TRF2. Science 283, 1321–1325.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Karlseder, J. , Smogorzewska, A. , and de Lange, T. (2002). Senescence induced by altered telomere state, not telomere loss. Science 295, 2446–2449.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Kim, S. H. , Kaminker, P. , and Campisi, J. (1999). TIN2, a new regulator of telomere length in human cells. Nat. Genet. 23, 405–412.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Kirk, K. E. , Harmon, B. P. , Reichardt, I. K. , Sedat, J. W. , and Blackburn, E. H. (1997). Block in anaphase chromosome separation caused by a telomerase template mutation. Science 275, 1478–1481.
Crossref | GoogleScholarGoogle Scholar |

Kyo, S. , Kanaya, T. , Takakura, M. , Tanaka, M. , and Inoue, M. (1999). Human telomerase reverse transcriptase as a critical determinant of telomerase activity in normal and malignant endometrial tissues. Int. J. Cancer 80, 60–63.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Lanza, R. P. , Cibelli, J. B. , Blackwell, C. , Cristofalo, V. J. , and Francis, M. K. , et al. (2000). Extension of cell life-span and telomere length in animals cloned from senescent somatic cells. Science 288, 665–669.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Laroche, T. , Martin, S. G. , Gotta, M. , Gorham, H. C. , Pryde, F. E. , Louis, E. J. , and Gasser, S. M. (1998). Mutation of yeast Ku genes disrupts the subnuclear organization of telomeres. Curr. Biol. 8, 653–656.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Lendvay, T. S. , Morris, D. K. , Sah, J. , Balasubramanian, B. , and Lundblad, V. (1996). Senescence mutants of Saccharomyces cerevisiae with a defect in telomere replication identify three additional EST genes. Genetics 144, 1399–1412.
PubMed |

Li, B. , Oestreich, S. , and de Lange, T. (2000). Identification of human Rap1: implications for telomere evolution. Cell 101, 471–483.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Li, X. , Leteurtre, F. , Rocha, V. , Guardiola, P. , and Berger, R. , et al. (2003). Abnormal telomere metabolism in Fanconi’s anaemia correlates with genomic instability and the probability of developing severe aplastic anaemia. Br. J. Haematol. 120, 836–845.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Lieber, M. R. , and Karanjawala, Z. E. (2004). Ageing, repetitive genomes and DNA damage. Nat. Rev. Mol. Cell Biol. 5, 69–75.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Lin, S. Y. , and Elledge, S. J. (2003). Multiple tumor suppressor pathways negatively regulate telomerase. Cell 113, 881–889.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Loayza, D. , and de Lange, T. (2003). POT1 as a terminal transducer of TRF1 telomere length control. Nature 423, 1013–1018.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Loayza, D. , Parsons, H. , Donigian, J. , Hoke, K. , and de Lange, T. (2004). DNA binding features of human POT1: a nonamer 5′-TAGGGTTAG-3′ minimal binding site, sequence specificity, and internal binding to multimeric sites. J. Biol. Chem. 279, 13 241–13 248.
Crossref | GoogleScholarGoogle Scholar |

Lundblad, V. (2000). DNA ends: maintenance of chromosome termini versus repair of double strand breaks. Mutat. Res. 451, 227–240.
PubMed |

Makarov, V. L. , Hirose, Y. , and Langmore, J. P. (1997). Long G tails at both ends of human chromosomes suggest a C strand degradation mechanism for telomere shortening. Cell 88, 657–666.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Mallory, J. C. , Bashkirov, V. I. , Trujillo, K. M. , Solinger, J. A. , Dominska, M. , Sung, P. , Heyer, W. D. , and Petes, T. D. (2003). Amino acid changes in Xrs2p, Dun1p, and Rfa2p that remove the preferred targets of the ATM family of protein kinases do not affect DNA repair or telomere length in Saccharomyces cerevisiae. DNA Repair (Amst.) 2, 1041–1064.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Martin-Rivera, L. , Herrera, E. , Albar, J. P. , and Blasco, M. A. (1998). Expression of mouse telomerase catalytic subunit in embryos and adult tissues. Proc. Natl Acad. Sci. USA 95, 10 471–10 476.
Crossref | GoogleScholarGoogle Scholar |

Maser, R. S. , and DePinho, R. A. (2002). Connecting chromosomes, crisis, and cancer. Science 297, 565–569.
Crossref | GoogleScholarGoogle Scholar | PubMed |

McEachern, M. J. , Krauskopf, A. , and Blackburn, E. H. (2000). Telomeres and their control. Annu. Rev. Genet. 34, 331–358.
Crossref | GoogleScholarGoogle Scholar | PubMed |

McElligott, R. , and Wellinger, R. J. (1997). The terminal DNA structure of mammalian chromosomes. EMBO J. 16, 3705–3714.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Meyerson, M. (2000). Role of telomerase in normal and cancer cells. J. Clin. Oncol. 18, 2626–2634.
PubMed |

Meyerson, M. , Counter, C. M. , Eaton, E. N. , Ellisen, L. W. , and Steiner, P. , et al. (1997). hEST2, the putative human telomerase catalytic subunit gene, is up-regulated in tumor cells and during immortalization. Cell 90, 785–795.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Meyne, J. , Ratliff, R. L. , and Moyzis, R. K. (1989). Conservation of the human telomere sequence (TTAGGG)n among vertebrates. Proc. Natl Acad. Sci. USA 86, 7049–7053.
PubMed |

Miyashita, N. , Shiga, K. , Yonai, M. , Kaneyama, K. , and Kobayashi, S. , et al. (2002). Remarkable differences in telomere lengths among cloned cattle derived from different cell types. Biol. Reprod. 66, 1649–1655.
PubMed |

Morin, G. B. (1989). The human telomere terminal transferase enzyme is a ribonucleoprotein that synthesizes TTAGGG repeats. Cell 59, 521–529.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Moyzis, R. K. , Buckingham, J. M. , Cram, L. S. , Dani, M. , Deaven, L. L. , Jones, M. D. , Meyne, J. , Ratliff, R. L. , and Wu, J. R. (1988). A highly conserved repetitive DNA sequence, (TTAGGG)n, present at the telomeres of human chromosomes. Proc. Natl Acad. Sci. USA 85, 6622–6626.
PubMed |

Nakamura, T. M. , and Cech, T. R. (1998). Reversing time: origin of telomerase. Cell 92, 587–590.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Nakamura, T. M. , Morin, G. B. , Chapman, K. B. , Weinrich, S. L. , Andrews, W. H. , Lingner, J. , Harley, C. B. , and Cech, T. R. (1997). Telomerase catalytic subunit homologs from fission yeast and human. Science 277, 955–959.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Nakayama, J. , Tahara, H. , Tahara, E. , Saito, M. , Ito, K. , Nakamura, H. , Nakanishi, T. , Tahara, E. , Ide, T. , and Ishikawa, F. (1998). Telomerase activation by hTRT in human normal fibroblasts and hepatocellular carcinomas. Nat. Genet. 18, 65–68.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Nugent, C. I. , and Lundblad, V. (1998). The telomerase reverse transcriptase: components and regulation. Genes Dev. 12, 1073–1085.
PubMed |

Nugent, C. I. , Bosco, G. , Ross, L. O. , Evans, S. K. , Salinger, A. P. , Moore, J. K. , Haber, J. E. , and Lundblad, V. (1998). Telomere maintenance is dependent on activities required for end repair of double-strand breaks. Curr. Biol. 8, 657–660.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Ohashi, K. , Tsutsumi, M. , Nakajima, Y. , Kobitsu, K. , Nakano, H. , and Konishi, Y. (1996). Telomere changes in human hepatocellular carcinomas and hepatitis virus infected noncancerous livers. Cancer 77 (Suppl. 1), 1747–1751.


Ohyashiki, J. H. , Ohyashiki, K. , Fujimura, T. , Kawakubo, K. , Shimamoto, T. , Iwabuchi, A. , and Toyama, K. (1994). Telomere shortening associated with disease evolution patterns in myelodysplastic syndromes. Cancer Res. 54, 3557–3560.
PubMed |

O’Sullivan, J. N. , Bronner, M. P. , Brentnall, T. A. , Finley, J. C. , and Shen, W. T. , et al. (2002). Chromosomal instability in ulcerative colitis is related to telomere shortening. Nat. Genet. 32, 280–284.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Parrinello, S. , Samper, E. , Krtolica, A. , Goldstein, J. , Melov, S. , and Campisi, J. (2003). Oxygen sensitivity severely limits the replicative lifespan of murine fibroblasts. Nat. Cell Biol. 5, 741–747.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Plentz, R. R. , Wiemann, S. U. , Flemming, P. , Meier, P. N. , Kubicka, S. , Kreipe, H. , Manns, M. P. , and Rudolph, K. L. (2003). Telomere shortening of epithelial cells characterises the adenoma–carcinoma transition of human colorectal cancer. Gut 52, 1304–1307.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Plentz, R. R. , Caselitz, M. , Bleck, J. S. , Gebel, M. , Flemming, P. , Kubicka, S. , Manns, M. P. , and Rudolph, K. L. (2004). Hepatocellular telomere shortening correlates with chromosomal instability and the development of human hepatoma. Hepatology 40, 80–86.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Price, J. S. , Waters, J. G. , Darrah, C. , Pennington, C. , Edwards, D. R. , Donell, S. T. , and Clark, I. M. (2002). The role of chondrocyte senescence in osteoarthritis. Aging Cell 1, 57–65.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Prowse, K. R. , and Greider, C. W. (1995). Developmental and tissue-specific regulation of mouse telomerase and telomere length. Proc. Natl Acad. Sci. USA 92, 4818–4822.
PubMed |

Ranganathan, V. , Heine, W. F. , Ciccone, D. N. , Rudolph, K. L. , and Wu, X. , et al. (2001). Rescue of a telomere length defect of Nijmegen breakage syndrome cells requires NBS and telomerase catalytic subunit. Curr. Biol. 11, 962–966.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Reaper, P. M. , di Fagagna, F. , and Jackson, S. P. (2004). Activation of the DNA damage response by telomere attrition: a passage to cellular senescence. Cell Cycle 3, 543–546.
PubMed |

Reichenbach, P. , Hoss, M. , Azzalin, C. M. , Nabholz, M. , Bucher, P. , and Lingner, J. (2003). A human homolog of yeast Est1 associates with telomerase and uncaps chromosome ends when overexpressed. Curr. Biol. 13, 568–574.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Ren, J. G. , Xia, H. L. , Just, T. , and Dai, Y. R. (2001). Hydroxyl radical-induced apoptosis in human tumor cells is associated with telomere shortening but not telomerase inhibition and caspase activation. FEBS Lett. 488, 123–132.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Ritchie, K. B. , and Petes, T. D. (2000). The Mre11p/Rad50p/Xrs2p complex and the Tel1p function in a single pathway for telomere maintenance in yeast. Genetics 155, 475–479.
PubMed |

Rudolph, K. L. , Chang, S. , Lee, H. W. , Blasco, M. , Gottlieb, G. J. , Greider, C. , and DePinho, R. A. (1999). Longevity, stress response, and cancer in aging telomerase-deficient mice. Cell 96, 701–712.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Satyanarayana, A. , Manns, M. , and Rudolph, K. L. (2004). Telomeres and telomerase: a dual role in hepatocarcinogenesis. Hepatology 40, 276–283.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Sbodio, J. I. , and Chi, N. W. (2002). Identification of a tankyrase-binding motif shared by IRAP, TAB182, and human TRF1 but not mouse TRF1. NuMA contains this RXXPDG motif and is a novel tankyrase partner. J. Biol. Chem. 277, 31 887–31 892.
Crossref | GoogleScholarGoogle Scholar |

Sbodio, J. I. , Lodish, H. F. , and Chi, N. W. (2002). Tankyrase-2 oligomerizes with tankyrase-1 and binds to both TRF1 (telomere-repeat-binding factor 1) and IRAP (insulin-responsive aminopeptidase). Biochem. J. 361, 451–459.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Schaetzlein, S. , Lucas-Hahn, A. , Lemme, E. , Kues, W. A. , Dorsch, M. , Manns, M. P. , Niemann, H. , and Rudolph, K. L. (2004). Telomere length is reset during early mammalian embryogenesis. Proc. Natl Acad. Sci. USA 101, 8034–8038.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Schramke, V. , Luciano, P. , Brevet, V. , Guillot, S. , Corda, Y. , Longhese, M. P. , Gilson, E. , and Geli, V. (2004). RPA regulates telomerase action by providing Est1p access to chromosome ends. Nat. Genet. 36, 46–54.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Sedelnikova, O. A. , Horikawa, I. , Zimonjic, D. B. , Popescu, N. C. , Bonner, W. M. , and Barrett, J. C. (2004). Senescing human cells and ageing mice accumulate DNA lesions with unrepairable double-strand breaks. Nat. Cell Biol. 6, 168–170.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Seimiya, H. , and Smith, S. (2002). The telomeric poly(ADP-ribose) polymerase, tankyrase 1, contains multiple binding sites for telomeric repeat binding factor 1 (TRF1) and a novel acceptor, 182-kDa tankyrase-binding protein (TAB182). J. Biol. Chem. 277, 14 116–14 126.
Crossref | GoogleScholarGoogle Scholar |

Shay, J. W. , and Bacchetti, S. (1997). A survey of telomerase activity in human cancer. Eur. J. Cancer 33, 787–791.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Shay, J. W. , and Wright, W. E. (2004). Telomeres are double-strand DNA breaks hidden from DNA damage responses. Mol. Cell 14, 420–421.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Sherr, C. J. , and DePinho, R. A. (2000). Cellular senescence: mitotic clock or culture shock? Cell 102, 407–410.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Shiels, P. G. , Kind, A. J. , Campbell, K. H. , Waddington, D. , Wilmut, I. , Colman, A. , and Schnieke, A. E. (1999). Analysis of telomere lengths in cloned sheep. Nature 399, 316–317.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Smith, S. , and de Lange, T. (2000). Tankyrase promotes telomere elongation in human cells. Curr. Biol. 10, 1299–1302.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Smith, S. , Giriat, I. , Schmitt, A. , and de Lange, T. (1998). Tankyrase, a poly(ADP-ribose) polymerase at human telomeres. Science 282, 1484–1487.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Smogorzewska, A. , and de Lange, T. (2004). Regulation of telomerase by telomeric proteins. Annu. Rev. Biochem. 73, 177–208.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Stansel, R. M. , de Lange, T. , and Griffith, J. D. (2001). T-loop assembly in vitro involves binding of TRF2 near the 3′ telomeric overhang. EMBO J. 20, 5532–5540.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Takai, H. , Smogorzewska, A. , and de Lange, T. (2003). DNA damage foci at dysfunctional telomeres. Curr. Biol. 13, 1549–1556.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Tarsounas, M. , Munoz, P. , Claas, A. , Smiraldo, P. G. , Pittman, D. L. , Blasco, M. A. , and West, S. C. (2004). Telomere maintenance requires the RAD51D recombination/repair protein. Cell 117, 337–347.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Tian, X. C. , Xu, J. , and Yang, X. (2000). Normal telomere lengths found in cloned cattle. Nat. Genet. 26, 272–273.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Tong, W. M. , Hande, M. P. , Lansdorp, P. M. , and Wang, Z. Q. (2001). DNA strand break-sensing molecule poly(ADP-Ribose) polymerase cooperates with p53 in telomere function, chromosome stability, and tumor suppression. Mol. Cell. Biol. 21, 4046–4054.
Crossref | GoogleScholarGoogle Scholar | PubMed |

van Steensel, B. , and de Lange, T. (1997). Control of telomere length by the human telomeric protein TRF1. Nature 385, 740–743.
Crossref | GoogleScholarGoogle Scholar | PubMed |

van Steensel, B. , Smogorzewska, A. , and de Lange, T. (1998). TRF2 protects human telomeres from end-to-end fusions. Cell 92, 401–413.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Vaziri, H. , Schachter, F. , Uchida, I. , Wei, L. , Zhu, X. , Effros, R. , Cohen, D. , and Harley, C. B. (1993). Loss of telomeric DNA during aging of normal and trisomy 21 human lymphocytes. Am. J. Hum. Genet. 52, 661–667.
PubMed |

Wakayama, T. , Shinkai, Y. , Tamashiro, K. L. , Niida, H. , and Blanchard, D. C. , et al. (2000). Cloning of mice to six generations. Nature 407, 318–319.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Wang, S. , and Zhu, J. (2003). Evidence for a relief of repression mechanism for activation of the human telomerase reverse transcriptase promoter. J. Biol. Chem. 278, 18 842–18 850.
Crossref | GoogleScholarGoogle Scholar |

Wiemann, S. U. , Satyanarayana, A. , Tsahuridu, M. , Tillmann, H. L. , and Zender, L. , et al. (2002). Hepatocyte telomere shortening and senescence are general markers of human liver cirrhosis. FASEB J. 16, 935–942.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Wong, K. K. , Maser, R. S. , Bachoo, R. M. , Menon, J. , Carrasco, D. R. , Gu, Y. , Alt, F. W. , and DePinho, R. A. (2003). Telomere dysfunction and Atm deficiency compromises organ homeostasis and accelerates ageing. Nature 421, 643–648.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Wright, W. E. , and Shay, J. W. (1992). The two-stage mechanism controlling cellular senescence and immortalization. Exp. Gerontol. 27, 383–389.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Wright, W. E. , Piatyszek, M. A. , Rainey, W. E. , Byrd, W. , and Shay, J. W. (1996). Telomerase activity in human germline and embryonic tissues and cells. Dev. Genet. 18, 173–179.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Wright, W. E. , Tesmer, V. M. , Huffman, K. E. , Levenem, S. D. , and Shay, J. W. (1997). Normal human chromosomes have long G-rich telomeric overhangs at one end. Genes Dev. 11, 2801–2809.
PubMed |

Wu, L. , and Hickson, I. D. (2001). RecQ helicases and topoisomerases: components of a conserved complex for the regulation of genetic recombination. Cell. Mol. Life Sci. 5, 894–901.


Wu, K. J. , Grandori, C. , Amacker, M. , Simon-Vermot, N. , Polack, A. , Lingner, J. , and Dalla-Favera, R. (1999). Direct activation of TERT transcription by c-MYC. Nat. Genet. 21, 220–224.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Wu, X. , Amos, C. I. , Zhu, Y. , Zhao, H. , Grossman, B. H. , Shay, J. W. , Luo, S. , Hong, W. K. , and Spitz, M. R. (2003). Telomere dysfunction: a potential cancer predisposition factor. J. Natl Cancer Inst. 95, 1211–1218.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Wyllie, F. S. , Jones, C. J. , Skinner, J. W. , Haughton, M. F. , Wallis, C. , Wynford-Thomas, D. , Faragher, R. G. , and Kipling, D. (2000). Telomerase prevents the accelerated cell ageing of Werner syndrome fibroblasts. Nat. Genet. 24, 16–17.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Xu, J. , and Yang, X. (2001). Telomerase activity in early bovine embryos derived from parthenogenetic activation and nuclear transfer. Biol. Reprod. 64, 770–774.
PubMed |

Yatabe, N. , Kyo, S. , Maida, Y. , Nishi, H. , Nakamura, M. , Kanaya, T. , Tanaka, M. , Isaka, K. , Ogawa, S. , and Inoue, M. (2004). HIF-1-mediated activation of telomerase in cervical cancer cells. Oncogene 23, 3708–3715.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Youngren, K. , Jeanclos, E. , Aviv, H. , Kimura, M. , Stock, J. , Hanna, M. , Skurnick, J. , Bardeguez, A. , and Aviv, A. (1998). Synchrony in telomere length of the human fetus. Hum. Genet. 102, 640–643.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Zhu, L. , Hathcock, K. S. , Hande, P. , Lansdorp, P. M. , Seldin, M. F. , and Hodes, R. J. (1998). Telomere length regulation in mice is linked to a novel chromosome locus. Proc. Natl Acad. Sci. USA 95, 8648–8653.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Zhu, J. , Wang, H. , Bishop, J. M. , and Blackburn, E. H. (1999). Telomerase extends the lifespan of virus-transformed human cells without net telomere lengthening. Proc. Natl Acad. Sci. USA 96, 3723–3728.
Crossref | GoogleScholarGoogle Scholar | PubMed |

Zhu, X. D. , Niedernhofer, L. , Kuster, B. , Mann, M. , Hoeijmakers, J. H. , and de Lange, T. (2003). ERCC1/XPF removes the 3′ overhang from uncapped telomeres and represses formation of telomeric DNA-containing double minute chromosomes. Mol. Cell 12, 1489–1498.
Crossref | GoogleScholarGoogle Scholar | PubMed |