title: Telomere structure and telomerase in health and disease (review).
abstract: Telomerase is the enzyme responsible for maintenance of the length of telomeres             by addition of guanine-rich repetitive sequences. Telomerase activity is exhibited             in gametes and stem and tumor cells. In human somatic cells, proliferation potential             is strictly limited and senescence follows approximately 50-70 cell divisions.             In most tumor cells, on the contrary, replication potential is unlimited. The             key role in this process of the system of the telomere length maintenance with             involvement of telomerase is still poorly studied. Undoubtedly, DNA polymerase             is not capable of completely copying DNA at the very ends of chromosomes; therefore,             approximately 50 nucleotides are lost during each cell cycle, which results in             gradual telomere length shortening. Critically short telomeres cause senescence,             following crisis and cell death. However, in tumor cells the system of telomere             length maintenance is activated. Much work has been done regarding the complex             telomere/telomerase as a unique target, highly specific in cancer cells. Telomeres             have additional proteins that regulate the binding of telomerase. Telomerase,             also associates with a number of proteins forming the sheltering complex having             a central role in telomerase activity. This review focuses on the structure and             function of the telomere/telomerase complex and its altered behavior leading to             disease, mainly cancer. Although telomerase therapeutics are not approved yet             for clinical use, we can assume that based on the promising in vitro and in vivo             results and successful clinical trials, it can be predicted that telomerase therapeutics             will be utilized soon in the combat against malignancies and degenerative diseases.             The active search for modulators is justified, because the telomere/telomerase             system is an extremely promising target offering possibilities to decrease or             increase the viability of the cell for therapeutic purposes.
authors.affiliation: Laboratory of Molecular Oncology, Department of Science and Technology, Quilmes National University, Buenos Aires, Argentina. degomez@unq.edu.ar
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Gomez
authors.forename: Romina G
authors.initials: RG
authors.lastname: Armando
authors.forename: Hernán G
authors.initials: HG
authors.lastname: Farina
authors.forename: Pablo Lorenzano
authors.initials: PL
authors.lastname: Menna
authors.forename: Carolina S
authors.initials: CS
authors.lastname: Cerrudo
authors.forename: P Daniel
authors.initials: PD
authors.lastname: Ghiringhelli
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Alonso
mesh_terms: D000818:Animals; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008322:Mammals; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000737:chemistry*; D059505:Telomere Homeostasis / Q000502:physiology*
chemical_list: D019098:Telomerase