Telomeres are specialized structures at the ends of eukaryotic chromosomes. Telomeric DNA consists of short G-rich repeats (TTAGGG in vertebrates) and is elongated by the enzyme telomerase, which is formed by a reverse transcriptase moiety, an RNA component and the ribonucleoprotein dyskerin. A complex known as shelterin is specifically associated to human telomeres and includes the proteins TRF1, TRF2, POT1, TIN2, TPP1 and RAP1. The interaction of these proteins each other and/or with telomeric DNA is essential for maintaining telomere homeostasis and can be mediated by post-translational modifications. Some members of the poly(ADP-ribose) polymerase enzyme family, i.e. PARP-1, PARP-2, VPARP and Tankyrases, are localized at telomeres. The role of poly(ADP-ribosylation) in the regulation of telomere dynamics will be discussed.
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