title: Identification of telomere-dependent "senescence-like" arrest in mouse embryonic fibroblasts.
abstract: In contrast to human primary cells, mouse embryonic fibroblasts (MEF) do not show telomere shortening-mediated replicative senescence due to the fact that they have telomerase activity and show sufficiently long telomeres. Instead, it is now generally accepted that the "senescence-like" arrest that occurs in MEF after 5-10 divisions in culture is mediated by telomere-length-independent mechanisms generally referred to as stress. Using telomerase-deficient MEF Terc(-/-), we show here that telomere shortening to a critical length leads to a premature senescence-like arrest in MEF, as well as has a negative effect on spontaneous immortalization. Similarly, elimination of the telomere end-capping protein Ku86 also leads to a premature senescence-like arrest and has a negative effect on spontaneous immortalization. Both Terc(-/-) MEF with short telomeres and Ku86(-/-) MEF show dysfunctional telomeres, as indicated by similarly increased frequencies of end-to-end fusions. These results suggest that loss of telomere function is a general mechanism leading to cell arrest. These observations also indicate that telomere dysfunction is interfering with successful cell division and thus interferes with tumor formation. In summary, we have identified here two different ways to induce a telomere-dependent senescence-like arrest in MEF.
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología-CSIC, Campus Cantoblanco, Madrid, Spain.
authors.forename: Silvia
authors.initials: S
authors.lastname: Espejel
authors.forename: María A
authors.initials: MA
authors.lastname: Blasco
mesh_terms: D000818:Animals; D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000235:genetics*; D002461:Cell Line, Transformed / Q000378:metabolism; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000235:genetics*; D019457:Chromosome Breakage / Q000235:genetics; D003114:Colony-Forming Units Assay; D004265:DNA Helicases; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics; D005260:Female; D005333:Fetus; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D000072200:Ku Autoantigen; D051379:Mice; D018345:Mice, Knockout; D009687:Nuclear Proteins / Q000172:deficiency / Q000235:genetics; D011247:Pregnancy; D012313:RNA / Q000235:genetics; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism*; D013312:Stress, Physiological / Q000235:genetics / Q000378:metabolism; D019098:Telomerase / Q000172:deficiency / Q000235:genetics; D016615:Telomere / Q000235:genetics* / Q000378:metabolism
chemical_list: D034961:Antigens, Nuclear; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; C422952:telomerase RNA; D012313:RNA; D019098:Telomerase; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606512:Xrcc5 protein, mouse; C000606509:Xrcc6 protein, human; C000606510:Xrcc6 protein, mouse; D000072200:Ku Autoantigen