title: No attenuation of the ATM-dependent DNA damage response in murine telomerase-deficient cells.
abstract: Inactivation of mammalian telomerase leads to telomere attrition, eventually culminating in uncapped telomeres, which elicit a DNA damage response and cell cycle arrest or death. In some instances, telomerase modulation evokes a response not obviously attributable to changes in telomere length. One such example is the suppression of the DNA damage response (DDR) and changes in histone modification that occur upon repression of the telomerase reverse transcriptase, TERT, in human primary cells [K. Masutomi, R. Possemato, J.M. Wong, J.L. Currier, Z. Tothova, J.B. Manola, S. Ganesan, P.M. Lansdorp, K. Collins and W.C. Hahn, The telomerase reverse transcriptase regulates chromatin state and DNA damage responses, Proc. Natl. Acad. Sci. U.S.A. 102 (2005) 8222-8227]. Here, we evaluate the contribution of TERT to the DDR in murine Tert(-/-) cells without critically shortened telomeres. We treated mTert(-/-) embryonic stem (ES) cells and murine embryonic fibroblasts (MEFs) with etoposide and irradiation, and assessed the status of p53(pS15), 53BP1, ATM(pS1981), SMC1(pS957), and gammaH2AX by indirect immunofluorescence or western blotting. In four independently derived mTert(-/-) ES cell lines, there was no significant difference in the induction of gammaH2AX, 53BP1 foci, or the phosphorylation of ATM targets (ATM, SMC1, p53) between wildtype and mTert(-/-) ES cells and MEFs. A slight difference in post-translational modification of histones H3 and H4 was observed in a subset of mTert(-/-) ES cells, however this difference was reflected in the cellular levels of H3 and H4. Thus, in contrast to previous studies in human cells, the absence of Tert does not overtly affect the ATM-dependent response to DNA damage in murine cells.
authors.affiliation: Department of Medical Biophysics, Ontario Cancer Institute and Campbell Family Institute for Breast Cancer Research, University of Toronto, Toronto, ON, Canada.
authors.forename: Natalie
authors.initials: N
authors.lastname: Erdmann
authors.forename: Lea A
authors.initials: LA
authors.lastname: Harrington
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006657:Histones / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D051379:Mice; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D019098:Telomerase / Q000172:deficiency*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D000071857:Tumor Suppressor p53-Binding Protein 1; D000098550:Structural Maintenance of Chromosome Protein 1
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006657:Histones; D047908:Intracellular Signaling Peptides and Proteins; C498302:Trp53bp1 protein, mouse; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D000071857:Tumor Suppressor p53-Binding Protein 1; C475961:gamma-H2AX protein, mouse; D000098550:Structural Maintenance of Chromosome Protein 1; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D019098:Telomerase