Telomeres, nucleoprotein structures at the ends of linear eukaryotic chromosomes, are important for the maintenance of genomic stability. Telomeres were considered as typical heterochromatic regions, but in light of recent results, this view should be reconsidered. Asymmetrically located cytosines in plant telomeric DNA repeats may be substrates for a DNA methyltransferase enzyme and indeed, it was shown that these repeats are methylated. Here, we analyse the methylation of telomeric cytosines and the length of telomeres in Arabidopsis thaliana methylation mutants (met 1-3 and ddm 1-8), and in their wild-type siblings that were germinated in the presence of hypomethylation drugs. Our results show that cytosine methylation in telomeric repeats depends on the activity of MET1 and DDM1 enzymes. Significantly shortened telomeres occur in later generations of methylation mutants as well as in plants germinated in the presence of hypomethylation drugs, and this phenotype is stably transmitted to the next plant generation. A possible role of compromised in vivo telomerase action in the observed telomere shortening is hypothesized based on telomere analysis of hypomethylated telomerase knockout plants. Results are discussed in connection with previous data in this field obtained using different model systems.

Mendel Centre for Plant Genomics and Proteomics Central European Institute of Technology Masaryk University Kamenice 5 62500 Brno Czech Republic Functional Genomics and Proteomics National Centre for Biomolecular Research Faculty of Science Masaryk University Kotlářská 2 611 37 Brno Czech Republic Institute of Organic Chemistry and Biochemistry Academy of Sciences of the Czech Republic v v i Flemingovo nám 2 166 10 Prague Czech Republic and Institute of Biophysics Academy of Sciences of the Czech Republic v v i Královopolská 135 612 65 Brno Czech Republic

Zobrazit více v PubMed

Blackburn EH. Switching and signaling at the telomere. Cell. 2001;106:661–673. PubMed

Bird A. Perceptions of epigenetics. Nature. 2007;447:396–398. PubMed

Martin C, Zhang Y. Mechanisms of epigenetic inheritance. Curr. Opin. Cell Biol. 2007;19:266–272. PubMed

Mattick JS, Makunin IV. Non-coding RNA. Hum. Mol. Genet. 2006;15(Spec No 1):R17–R29. PubMed

Lister R, Pelizzola M, Dowen RH, Hawkins RD, Hon G, Tonti-Filippini J, Nery JR, Lee L, Ye Z, Ngo QM, et al. Human DNA methylomes at base resolution show widespread epigenomic differences. Nature. 2009;462:315–322. PubMed PMC

Zhang X. The epigenetic landscape of plants. Science. 2008;320:489–492. PubMed

Cokus SJ, Feng S, Zhang X, Chen Z, Merriman B, Haudenschild CD, Pradhan S, Nelson SF, Pellegrini M, Jacobsen SE. Shotgun bisulphite sequencing of the Arabidopsis genome reveals DNA methylation patterning. Nature. 2008;452:215–219. PubMed PMC

Vrbsky J, Akimcheva S, Watson JM, Turner TL, Daxinger L, Vyskot B, Aufsatz W, Riha K. siRNA-mediated methylation of Arabidopsis telomeres. PLoS Genet. 2010;6:e1000986. PubMed PMC

Majerova E, Fojtova M, Mozgova I, Bittova M, Fajkus J. Hypomethylating drugs efficiently decrease cytosine methylation in telomeric DNA and activate telomerase without affecting telomere lengths in tobacco cells. Plant Mol. Biol. 2011;77:371–380. PubMed

Penterman J, Zilberman D, Huh JH, Ballinger T, Henikoff S, Fischer RL. DNA demethylation in the Arabidopsis genome. Proc. Natl Acad. Sci. U.S.A. 2007;104:6752–6757. PubMed PMC

Zheng X, Pontes O, Zhu J, Miki D, Zhang F, Li WX, Iida K, Kapoor A, Pikaard CS, Zhu JK. ROS3 is an RNA-binding protein required for DNA demethylation in Arabidopsis. Nature. 2008;455:1259–1262. PubMed PMC

Hajkova P, Jeffries SJ, Lee C, Miller N, Jackson SP, Surani MA. Genome-wide reprogramming in the mouse germ line entails the base excision repair pathway. Science. 2010;329:78–82. PubMed PMC

Onodera Y, Haag JR, Ream T, Costa Nunes P, Pontes O, Pikaard CS. Plant nuclear RNA polymerase IV mediates siRNA and DNA methylation-dependent heterochromatin formation. Cell. 2005;120:613–622. PubMed

Wierzbicki AT, Haag JR, Pikaard CS. Noncoding transcription by RNA polymerase Pol IVb/Pol V mediates transcriptional silencing of overlapping and adjacent genes. Cell. 2008;135:635–648. PubMed PMC

Cao F, Li X, Hiew S, Brady H, Liu Y, Dou Y. Dicer independent small RNAs associate with telomeric heterochromatin. RNA. 2009;15:1274–1281. PubMed PMC

O'Sullivan RJ, Kubicek S, Schreiber SL, Karlseder J. Reduced histone biosynthesis and chromatin changes arising from a damage signal at telomeres. Nat. Struct. Mol. Biol. 2010;17:1218–1225. PubMed PMC

Rosenfeld JA, Wang Z, Schones DE, Zhao K, DeSalle R, Zhang MQ. Determination of enriched histone modifications in non-genic portions of the human genome. BMC Genomics. 2009;10:143. PubMed PMC

Brock GJ, Charlton J, Bird A. Densely methylated sequences that are preferentially localized at telomere-proximal regions of human chromosomes. Gene. 1999;240:269–277. PubMed

de Lange T, Shiue L, Myers RM, Cox DR, Naylor SL, Killery AM, Varmus HE. Structure and variability of human chromosome ends. Mol. Cell. Biol. 1990;10:518–527. PubMed PMC

Benetti R, Garcia-Cao M, Blasco MA. Telomere length regulates the epigenetic status of mammalian telomeres and subtelomeres. Nat. Genet. 2007;39:243–250. PubMed

Benetti R, Gonzalo S, Jaco I, Schotta G, Klatt P, Jenuwein T, Blasco MA. Suv4-20h deficiency results in telomere elongation and derepression of telomere recombination. J. Cell Biol. 2007;178:925–936. PubMed PMC

Gonzalo S, Jaco I, Fraga MF, Chen T, Li E, Esteller M, Blasco MA. DNA methyltransferases control telomere length and telomere recombination in mammalian cells. Nat. Cell Biol. 2006;8:416–424. PubMed

Ng LJ, Cropley JE, Pickett HA, Reddel RR, Suter CM. Telomerase activity is associated with an increase in DNA methylation at the proximal subtelomere and a reduction in telomeric transcription. Nucleic Acids Res. 2009;37:1152–1159. PubMed PMC

Palacios JA, Herranz D, De Bonis ML, Velasco S, Serrano M, Blasco MA. SIRT1 contributes to telomere maintenance and augments global homologous recombination. J. Cell Biol. 2011;191:1299–1313. PubMed PMC

Vera E, Canela A, Fraga MF, Esteller M, Blasco MA. Epigenetic regulation of telomeres in human cancer. Oncogene. 2008;27:6817–6833. PubMed

Roberts AR, Blewitt ME, Youngson NA, Whitelaw E, Chong S. Reduced dosage of the modifiers of epigenetic reprogramming Dnmt1, Dnmt3L, SmcHD1 and Foxo3a has no detectable effect on mouse telomere length in vivo. Chromosoma. 2011;120:377–385. PubMed PMC

Kavi HH, Xie W, Fernandez HR, Birchler JA. Global analysis of siRNA-mediated transcriptional gene silencing. Bioessays. 2005;27:1209–1212. PubMed

Vaquero-Sedas MI, Gamez-Arjona FM, Vega-Palas MA. Arabidopsis thaliana telomeres exhibit euchromatic features. Nucleic Acids Res. 2010;39:2007–2017. PubMed PMC

Azzalin CM, Reichenbach P, Khoriauli L, Giulotto E, Lingner J. Telomeric repeat containing RNA and RNA surveillance factors at mammalian chromosome ends. Science. 2007;318:798–801. PubMed

Farnung BO, Brun CM, Arora R, Lorenzi LE, Azzalin CM. Telomerase efficiently elongates highly transcribing telomeres in human cancer cells. PLoS One. 2012;7:e35714. PubMed PMC

Schoeftner S, Blasco MA. Developmentally regulated transcription of mammalian telomeres by DNA-dependent RNA polymerase II. Nat. Cell Biol. 2008;10:228–236. PubMed

Redon S, Reichenbach P, Lingner J. The non-coding RNA TERRA is a natural ligand and direct inhibitor of human telomerase. Nucleic Acids Res. 2010;38:5797–5806. PubMed PMC

Pfeiffer V, Lingner J. TERRA promotes telomere shortening through exonuclease 1-mediated resection of chromosome ends. PLoS Genet. 2012;8:e1002747. PubMed PMC

Ronemus MJ, Galbiati M, Ticknor C, Chen J, Dellaporta SL. Demethylation-induced developmental pleiotropy in Arabidopsis. Science. 1996;273:654–657. PubMed

Mathieu O, Reinders J, Caikovski M, Smathajitt C, Paszkowski J. Transgenerational stability of the Arabidopsis epigenome is coordinated by CG methylation. Cell. 2007;130:851–862. PubMed

Jeddeloh JA, Stokes TL, Richards EJ. Maintenance of genomic methylation requires a SWI2/SNF2-like protein. Nat. Genet. 1999;22:94–97. PubMed

Vongs A, Kakutani T, Martienssen RA, Richards EJ. Arabidopsis thaliana DNA methylation mutants. Science. 1993;260:1926–1928. PubMed

Kim CH, Marquez VE, Mao DT, Haines DR, McCormack JJ. Synthesis of pyrimidin-2-one nucleosides as acid-stable inhibitors of cytidine deaminase. J. Med. Chem. 1986;29:1374–1380. PubMed

Yoo CB, Cheng JC, Jones PA. Zebularine: a new drug for epigenetic therapy. Biochem. Soc. Trans. 2004;32:910–912. PubMed

Cihak A. Biological effects of 5-azacytidine in eukaryotes. Oncology. 1974;30:405–422. PubMed

Baubec T, Pecinka A, Rozhon W, Mittelsten Scheid O. Effective, homogeneous and transient interference with cytosine methylation in plant genomic DNA by zebularine. Plant J. 2009;57:542–554. PubMed PMC

Holy A. Aliphatic analogues of nucleosides, nucleotides and oligonucleotides. Collect. Czech. Chem. C. 1975;40:187–214.

Kovarik A, Van Houdt H, Holy A, Depicker A. Drug-induced hypomethylation of a posttranscriptionally silenced transgene locus of tobacco leads to partial release of silencing. FEBS Lett. 2000;467:47–51. PubMed

Koukalova B, Votruba I, Fojtova M, Holy A, Kovarik A. Hypomethylation of CNG targets induced with dihydroxypropyladenine is rapidly reversed in the course of mitotic cell division in tobacco. Theor. Appl. Genet. 2002;105:796–801. PubMed

Fulnecek J, Matyasek R, Votruba I, Holy A, Krizova K, Kovarik A. Inhibition of SAH-hydrolase activity during seed germination leads to deregulation of flowering genes and altered flower morphology in tobacco. Mol. Genet. Genomics. 2011;285:225–236. PubMed

Fojtova M, Kovarik A, Votruba I, Holy A. Evaluation of the impact of S-adenosylhomocysteine metabolic pools on cytosine methylation of the tobacco genome. Eur. J. Biochem. 1998;252:347–352. PubMed

Alonso JM, Stepanova AN. T-DNA mutagenesis in Arabidopsis. Methods Mol. Biol. 2003;236:177–188. PubMed

Saze H, Mittelsten Scheid O, Paszkowski J. Maintenance of CpG methylation is essential for epigenetic inheritance during plant gametogenesis. Nat. Genet. 2003;34:65–69. PubMed

Jaske K, Mokros P, Mozgova I, Fojtova M, Fajkus J. A telomerase-independent component of telomere loss in chromatin assembly factor 1 mutants of Arabidopsis thaliana. Chromosoma. 2013;122:285–293. PubMed

Ruckova E, Friml J, Prochazkova Schrumpfova P, Fajkus J. Role of alternative telomere lengthening unmasked in telomerase knock-out mutant plants. Plant Mol. Biol. 2008;66:637–646. PubMed

Clark SJ, Harrison J, Paul CL, Frommer M. High sensitivity mapping of methylated cytosines. Nucleic Acids Res. 1994;22:2990–2997. PubMed PMC

Hetzl J, Foerster AM, Raidl G, Mittelsten Scheid O. CyMATE: a new tool for methylation analysis of plant genomic DNA after bisulphite sequencing. Plant J. 2007;51:526–536. PubMed

Fojtova M, Fulneckova J, Fajkus J, Kovarik A. Recovery of tobacco cells from cadmium stress is accompanied by DNA repair and increased telomerase activity. J. Exp. Bot. 2002;53:2151–2158. PubMed

Sykorova E, Fajkus J, Meznikova M, Lim KY, Neplechova K, Blattner FR, Chase MW, Leitch AR. Minisatellite telomeres occur in the family Alliaceae but are lost in Allium. Am. J. Bot. 2006;93:814–823. PubMed

Uchida W, Matsunaga S, Sugiyama R, Kawano S. Interstitial telomere-like repeats in the Arabidopsis thaliana genome. Genes Genet. Syst. 2002;77:63–67. PubMed

Gamez-Arjona FM, Lopez-Lopez C, Vaquero-Sedas MI, Vega-Palas MA. On the organization of the nucleosomes associated with telomeric sequences. Biochim. Biophys. Acta. 2010;1803:1058–1061. PubMed

Fitzgerald MS, Riha K, Gao F, Ren S, McKnight TD, Shippen DE. Disruption of the telomerase catalytic subunit gene from Arabidopsis inactivates telomerase and leads to a slow loss of telomeric DNA. Proc. Natl Acad. Sci. U.S.A. 1999;96:14813–14818. PubMed PMC

Fitzgerald MS, McKnight TD, Shippen DE. Characterization and developmental patterns of telomerase expression in plants. Proc. Natl Acad. Sci. U.S.A. 1996;93:14422–14427. PubMed PMC

Cifuentes-Rojas C, Kannan K, Tseng L, Shippen DE. Two RNA subunits and POT1a are components of Arabidopsis telomerase. Proc. Natl Acad. Sci. U.S.A. 2011;108:73–78. PubMed PMC

Surovtseva YV, Shakirov EV, Vespa L, Osbun N, Song X, Shippen DE. Arabidopsis POT1 associates with the telomerase RNP and is required for telomere maintenance. EMBO J. 2007;26:3653–3661. PubMed PMC

Kuchar M, Fajkus J. Interactions of putative telomere-binding proteins in Arabidopsis thaliana: identification of functional TRF2 homolog in plants. FEBS Lett. 2004;578:311–315. PubMed

Shakirov EV, Surovtseva YV, Osbun N, Shippen DE. The Arabidopsis Pot1 and Pot2 proteins function in telomere length homeostasis and chromosome end protection. Mol. Cell. Biol. 2005;25:7725–7733. PubMed PMC

Mozgova I, Schrumpfova PP, Hofr C, Fajkus J. Functional characterization of domains in AtTRB1, a putative telomere-binding protein in Arabidopsis thaliana. Phytochemistry. 2008;69:1814–1819. PubMed

Blasco MA. The epigenetic regulation of mammalian telomeres. Nat. Rev. Genet. 2007;8:299–309. PubMed

Stroud H, Greenberg MV, Feng S, Bernatavichute YV, Jacobsen SE. Comprehensive analysis of silencing mutants reveals complex regulation of the Arabidopsis methylome. Cell. 2013;152:352–364. PubMed PMC

Vyskot B, Koukalova B, Kovarik A, Sachambula L, Reynolds D, Bezdek M. Meiotic transmission of a hypomethylated repetitive DNA family in tobacco. Theor. Appl. Genet. 1995;91:659–664. PubMed

Majerova E, Fojtova M, Mandakova T, Fajkus J. Methylation of plant telomeric DNA: what do the results say? (Vaquero-Sedas, M.I. and Vega-Palas, M.A.: DNA methylation at tobacco telomeric sequences) Plant Mol. Biol. 2011;77:533–536. PubMed

Ogrocka A, Sykorova E, Fajkus J, Fojtova M. Developmental silencing of the AtTERT gene is associated with increased H3K27me3 loading and maintenance of its euchromatic environment. J. Exp. Bot. 2012;63:4233–4241. PubMed PMC

Pucci F, Gardano L, Harrington L. Short telomeres in ESCs lead to unstable differentiation. Cell Stem Cell. 2013;12:479–486. PubMed PMC

Riha K, McKnight TD, Griffing LR, Shippen DE. Living with genome instability: plant responses to telomere dysfunction. Science. 2001;291:1797–1800. PubMed

Fajkus J, Kovarik A, Kralovics R, Bezdek M. Organization of telomeric and subtelomeric chromatin in the higher plant Nicotiana tabacum. Mol. Gen. Genet. 1995;247:633–638. PubMed

Shakirov EV, Shippen DE. Length regulation and dynamics of individual telomere tracts in wild-type Arabidopsis. Plant Cell. 2004;16:1959–1967. PubMed PMC

Distinct Responses of Arabidopsis Telomeres and Transposable Elements to Zebularine Exposure

Telomeres in Plants and Humans: Not So Different, Not So Similar

Telomere elongation upon transfer to callus culture reflects the reprogramming of telomere stability control in Arabidopsis

Chromatin features of plant telomeric sequences at terminal vs. internal positions