Autophagy through 4EBP1 and AMPK regulates oxidative stress-induced premature senescence in auditory cells

Nana Akagi Tsuchihashi, Ken Hayashi, Katsuaki Dan, Fumiyuki Goto, Yasuyuki Nomura, Masato Fujioka, Sho Kanzaki, Shizuo Komune, Kaoru Ogawa

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The aim of this study was to determine whether autophagy and AMPK contribute to premature senescence in auditory cells. Incubating HEI-OC1 auditory cells with 5 mM H2O2 for 1 h induced senescence, as demonstrated by senescence-associated β-galactosidase (SA-β-gal) staining. H2O2 treatment significantly delayed populationdoubling time, leaving cell viability unchanged. Furthermore, the proportion of SA-β-gal-positive cells significantly increased. Autophagy-related protein expression increased, with Atg7 and LC3-II peaking 6 h and Lamp2 peaking 24 h after H2O2 treatment. The expression of these proteins decreased 48 h after treatment. Transmission electron microscopy revealed lipofuscin and aggregates within autolysosomes, which accumulated markedly in the cytoplasm of HEI-OC1 cells 48 h after treatment. Akt and P70S6 phosphorylation markedly decreased after H2O2 treatment, but 4EBP1 phosphorylation significantly increased 48 h after treatment. After RNAi-mediated knockdown (KD) of Atg7 and AMPK, H2O2-treated cells displayed dense SA-β-gal staining. Also, premature senescence was significantly induced. These suggest that a negative feedback loop may exist between autophagy and AMPK signaling pathways in HEI-OC1 cells. In our model, oxidative stress-induced premature senescence occurred due to impaired autophagy function through 4EBP1 phosphorylation. Our results also indicate that AMPK may regulate premature senescence in auditory cells in an autophagy-dependent and independent manner.

Original languageEnglish
Pages (from-to)3644-3655
Number of pages12
JournalOncotarget
Volume6
Issue number6
DOIs
Publication statusPublished - 2015

Keywords

  • AMPK
  • Auditory cell
  • Autophagy
  • Oxidative stress
  • Premature senescence

ASJC Scopus subject areas

  • Oncology

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