Telomerase activity during the cell cycle and in gamma-irradiated hematopoietic cells.
Telomeric DNA protects chromosome ends from recombination events and its length serves as a mitotic clock that triggers exit from the cell cycle when telomeres become too short. Telomerase is the enzyme involved in telomere elongation, one of the events that permits unlimited cell proliferation. Variations in telomerase activity were quantified in hematopoietic cell lines after gamma-irradiation. Telomerase activity increased after irradiation of between 0 and 3 Gy in a dose-dependent manner, reaching a maximum at 3 Gy. The increase in telomerase activity was nearly maximum 8 h after irradiation, the peak being observed at around 24 h. Although this kinetics partly correlated with cell redistribution into the G2/M phase of the cell cycle, telomerase activity did not show significant variation over the cell cycle. Therefore, the activation of telomerase observed after gamma-irradiation may suggest the involvement of telomerase in DNA repair and chromosome healing.
Leteurtre
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Service de Recherches en HématoImmunologie, Laboratoire d'Immunoradiobiologie, DRM-DSV-CEA, Hôpital Saint-Louis, Paris, France.
Li
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Gluckman
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Carosella
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D002453:Cell Cycle / Q000502:physiology / Q000528:radiation effects; D002455:Cell Division / Q000187:drug effects / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D004260:DNA Repair; D015536:Down-Regulation / Q000528:radiation effects; D004789:Enzyme Activation / Q000528:radiation effects; D016195:G2 Phase / Q000502:physiology / Q000528:radiation effects; D005720:Gamma Rays; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000201:enzymology* / Q000528:radiation effects*; D006801:Humans; D008938:Mitosis / Q000502:physiology / Q000528:radiation effects; D019098:Telomerase / Q000378:metabolism* / Q000528:radiation effects*; D015854:Up-Regulation / Q000528:radiation effects
D019098:Telomerase