Abstract
Telomere homeostasis is regulated at multiple levels, including the local chromatin structure of telomeres and subtelomeres. Recent reports demonstrated that a decrease in repressive chromatin marks, such as levels of cytosine methylation in subtelomeric regions, results in telomere elongation in mouse cells. Here we show that a considerable fraction of cytosines is methylated not only in subtelomeric, but also in telomeric DNA of tobacco BY-2 cells. Drug-induced hypomethylation (demonstrated at subtelomeric, telomeric, and global DNA levels) results in activation of telomerase. However, in contrast to mouse cells, the decrease in 5-methylcytosine levels and upregulation of telomerase do not result in any changes of telomere lengths. These results demonstrate the involvement of epigenetic mechanisms in the multilevel process of regulation of telomerase activity in plant cells and, at the same time, they indicate that changes in telomerase activity can be overridden by other factors governing telomere length stability.
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Acknowledgments
This work was supported by the Czech Science Foundation (P501/11/0289, P501/11/0596) the Czech Ministry of Education (MSM0021622415, LC06004 and LC 06035) and by the project “CEITEC—Central European Institute of Technology” (CZ.1.05/1.1.00/02.0068) from European Regional Development Fund. We thank Jana Kapustová for technical assistance, Dr. Ivan Votruba, Institute of Organic Chemistry and Biochemistry ASCR v.v.i., Prague, for providing us with DHPA and Dr. Aleš Kovařík, Institute of Biophysics, ASCR v.v.i., Brno, for providing us with a bacterial clone containing the subtelomeric repeat HRS60.
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Majerová, E., Fojtová, M., Mozgová, I. et al. Hypomethylating drugs efficiently decrease cytosine methylation in telomeric DNA and activate telomerase without affecting telomere lengths in tobacco cells. Plant Mol Biol 77, 371 (2011). https://doi.org/10.1007/s11103-011-9816-7
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DOI: https://doi.org/10.1007/s11103-011-9816-7