ISSN 0006-2979, Biochemistry (Moscow), 2012, Vol. 77, No. 10, pp. 1120-1128. © Pleiades Publishing, Ltd., 2012. Published in Russian in Biokhimiya, 2012, Vol. 77, No. 10, pp. 1350-1361. REVIEW Telomerase RNA Biosynthesis and Processing E. M. Smekalova1, O. S. Shubernetskaya1, M. I. Zvereva1,2*, E. V. Gromenko1, M. P. Rubtsova1,2, and O. A. Dontsova1,2 1Chemical Faculty, Lomonosov Moscow State University, 119991 Moscow, Russia 2Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia; E-mail:
[email protected] Received April 13, 2012 Abstract—Telomerase synthesizes repetitive G-rich sequences (telomeric repeats) at the ends of eukaryotic chromosomes. This mechanism maintains the integrity of the genome, as telomere shortening leads to degradation and fusion of chromo- somes. The core components of telomerase are the telomerase catalytic subunit and telomerase RNA, which possesses a small template region serving for the synthesis of a telomeric repeat. Mutations in the telomerase RNA are associated with some cases of aplastic anemia and also cause dyskeratosis congenita, myelodysplasia, and pulmonary fibrosis. Telomerase is active in 85% of cancers, and telomerase activation is one of the first steps in cell transformation. The study of telomerase and pathways where this enzyme is involved will help to understand the mechanism of the mentioned diseases and to devel- op new approaches for their treatment. In this review we describe the modern conception of telomerase RNA biosynthesis, processing, and functioning in the three most studied systems – yeast, vertebrates, and ciliates. DOI: 10.1134/S0006297912100045 Key words: telomerase RNA, telomerase, telomeres Telomeres are specialized DNA–protein structures RNA/DNA duplex to allow for synthesis of the next that are localized at the ends of eukaryotic chromosomes; repeat (Fig.