DNA damage response activation in mouse embryonic fibroblasts undergoing replicative senescence and following spontaneous immortalization

Raffaella Di Micco, Angelo Cicalese, Marzia Fumagalli, Miryana Dobreva, Alessandro Verrecchia, Pier Giuseppe Pelicci, F. D. Di Fagagna

Research output: Contribution to journalArticle

Abstract

Primary mouse embryonic fibroblasts (MEFs) are a popular tool for molecular and cell biology studies. However, when MEFs are grown in vitro under standard tissue culture conditions, they proliferate only for a limited number of population doublings (PD) and eventually undergo cellular senescence. Presently, the molecular mechanisms halting cell cycle progression and establishing cellular senescence under these conditions are unclear. Here, we show that a robust DNA damage response (DDR) is activated when MEFs undergo replicative cellular senescence. Senescent cells accumulate senescence-associated DDR foci (SDFs) containing the activated form of ATM, its phosphorylated substrates and γH2AX. In senescent MEFs, DDR markers do not preferentially accumulate at telomeres, the end of linear chromosomes. It has been observed that proliferation of MEFs is extended if they are cultured at low oxygen tension (3% O2). We observed that under these conditions, DDR is not observed and senescence is not established. Importantly, inactivation of ATM in senescent MEFs allows escape from senescence and progression through the S-phase. Therefore, MEFs undergoing cellular senescence arrest their proliferation due to the activation of a DNA damage checkpoint mediated by ATM kinase. Finally, we observed that spontaneously immortalized proliferating MEFs display markers of an activated DDR, indicating the presence of chromosomal DNA damage in these established cell lines.

Original languageEnglish
Pages (from-to)3601-3606
Number of pages6
JournalCell Cycle
Volume7
Issue number22
Publication statusPublished - Nov 15 2008

Keywords

  • Ataxia-telangiectasia mutated (ATM)
  • Cellular senescence
  • DNA damage response (DDR)
  • Mouse embryo fibroblasts (MEFs)
  • Oxidative stress

ASJC Scopus subject areas

  • Cell Biology
  • Developmental Biology
  • Molecular Biology

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