Superoxide is the major reactive oxygen species regulating autophagy

Cell Death Differ. 2009 Jul;16(7):1040-52. doi: 10.1038/cdd.2009.49. Epub 2009 May 1.

Abstract

Autophagy is involved in human diseases and is regulated by reactive oxygen species (ROS) including superoxide (O(2)(*-)) and hydrogen peroxide (H(2)O(2)). However, the relative functions of O(2)(*-) and H(2)O(2) in regulating autophagy are unknown. In this study, autophagy was induced by starvation, mitochondrial electron transport inhibitors, and exogenous H(2)O(2). We found that O(2)(*-) was selectively induced by starvation of glucose, L-glutamine, pyruvate, and serum (GP) whereas starvation of amino acids and serum (AA) induced O(2)(*-) and H(2)O(2). Both types of starvation induced autophagy and autophagy was inhibited by overexpression of SOD2 (manganese superoxide dismutase, Mn-SOD), which reduced O(2)(*-) levels but increased H(2)O(2) levels. Starvation-induced autophagy was also inhibited by the addition of catalase, which reduced both O(2)(*-) and H(2)O(2) levels. Starvation of GP or AA also induced cell death that was increased following treatment with autophagy inhibitors 3-methyladenine, and wortamannin. Mitochondrial electron transport chain (mETC) inhibitors in combination with the SOD inhibitor 2-methoxyestradiol (2-ME) increased O(2)(*-) levels, lowered H(2)O(2) levels, and increased autophagy. In contrast to starvation, cell death induced by mETC inhibitors was increased by 2-ME. Finally, adding exogenous H(2)O(2) induced autophagy and increased intracellular O(2)(*-) but failed to increase intracellular H(2)O(2). Taken together, these findings indicate that O(2)(*-) is the major ROS-regulating autophagy.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 2-Methoxyestradiol
  • Antioxidants / pharmacology
  • Apoptosis Regulatory Proteins / genetics
  • Apoptosis Regulatory Proteins / metabolism
  • Autophagy / drug effects
  • Autophagy / physiology*
  • Autophagy-Related Protein 7
  • Beclin-1
  • Catalase / pharmacology
  • Cell Line
  • Cell Line, Tumor
  • Estradiol / analogs & derivatives
  • Estradiol / pharmacology
  • HeLa Cells
  • Humans
  • Hydrogen Peroxide / metabolism
  • Hydrogen Peroxide / pharmacology
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Microtubule-Associated Proteins / metabolism*
  • Oxidants / metabolism
  • Oxidants / pharmacology
  • RNA, Small Interfering / metabolism
  • Reactive Oxygen Species / metabolism
  • Superoxide Dismutase / antagonists & inhibitors
  • Superoxide Dismutase / genetics
  • Superoxide Dismutase / metabolism*
  • Superoxides / metabolism*
  • Ubiquitin-Activating Enzymes / genetics
  • Ubiquitin-Activating Enzymes / metabolism

Substances

  • Antioxidants
  • Apoptosis Regulatory Proteins
  • BECN1 protein, human
  • Beclin-1
  • Membrane Proteins
  • Microtubule-Associated Proteins
  • Oxidants
  • RNA, Small Interfering
  • Reactive Oxygen Species
  • light chain 3, human
  • Superoxides
  • Estradiol
  • 2-Methoxyestradiol
  • Hydrogen Peroxide
  • Catalase
  • Superoxide Dismutase
  • Atg7 protein, human
  • Autophagy-Related Protein 7
  • Ubiquitin-Activating Enzymes