Compensatory activation of ERK1/2 in Atg5-deficient mouse embryo fibroblasts suppresses oxidative stress-induced cell death

Autophagy. 2008 Apr;4(3):315-21. doi: 10.4161/auto.5525. Epub 2008 Jan 7.

Abstract

Despite of the increasing evidence that oxidative stress may induce non-apoptotic cell death or autophagic cell death, the mechanism of this process is unclear. Here, we report a role and a down-stream molecular event of Atg5 during oxidative stress-induced cell death. Compared to wild type (WT) cells, Atg5-deficient mouse embryo fibroblasts (Atg5-/- MEFs) and Atg5 knockdown HT22 neuronal cells were more resistant to cell death induced by H2O2. On the contrary, Atg5-/- MEFs were as sensitive to tumor necrosis factor (TNF)-alpha and cycloheximide as WT cells, and were more sensitive to cell death triggered by amino acid-deprivation than WT MEFs. Treatment with H2O2 induced the recruitment of a GFP-LC3 fusion protein and conversion of LC3 I to LC3 II, correlated with the extent of autophagosome formation in WT cells, but much less in Atg5-deficient cells. Among stress kinases, ERK1/2 was markedly activated in Atg5-/- MEFs and Atg5 knockdown HT22 and SH-SY5Y neuronal cells. The inhibition of ERK1/2 by MEK1 inhibitor (PD98059) or dominant negative ERK2 enhanced the susceptibility of Atg5-/- MEFs to H2O2-induced cell death. Further, reconstitution of Atg5 sensitized Atg5-/- MEFs to H2O2 and suppressed the activation of ERK1/2. These results suggest that the inhibitory effect of Atg5 deficiency on cell death is attributable by the compensatory activation of ERK1/2 in Atg5-/- MEFs during oxidative stress-induced cell death.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy
  • Autophagy-Related Protein 5
  • Cell Death
  • Cells, Cultured
  • Cycloheximide / pharmacology
  • Embryo, Mammalian
  • Enzyme Activation
  • Fibroblasts / drug effects
  • Fibroblasts / enzymology
  • Fibroblasts / physiology*
  • Flavonoids / pharmacology
  • Hydrogen Peroxide / pharmacology
  • Mice
  • Mice, Knockout
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Microtubule-Associated Proteins / physiology*
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3 / metabolism*
  • Neurons / drug effects
  • Neurons / enzymology
  • Oxidative Stress / drug effects
  • Oxidative Stress / physiology*
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • Atg5 protein, mouse
  • Autophagy-Related Protein 5
  • Flavonoids
  • Map1lc3b protein, mouse
  • Microtubule-Associated Proteins
  • Tumor Necrosis Factor-alpha
  • Cycloheximide
  • Hydrogen Peroxide
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one