Superoxide is the major reactive oxygen species regulating autophagy

Abstract

Autophagy is involved in human diseases and is regulated by reactive oxygen species (ROS) including superoxide (O 2 KÀ ) and hydrogen peroxide (H 2 O 2 ). However, the relative functions of O 2 KÀ 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 KÀ was selectively induced by starvation of glucose, L-glutamine, pyruvate, and serum (GP) whereas starvation of amino acids and serum (AA) induced O 2 KÀ 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 KÀ levels but increased H 2 O 2 levels. Starvation-induced autophagy was also inhibited by the addition of catalase, which reduced both O 2 KÀ 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 KÀ 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 KÀ but failed to increase intracellular H 2 O 2 . Taken together, these findings indicate that O 2 KÀ is the major ROS-regulating autophagy.

The Pan-Bcl-2 Inhibitor (−)-Gossypol Triggers Autophagic Cell Death in Malignant Glioma

“…Therefore, inhibition of prosurvival members of the Bcl-2 family by BH3 mimetics, especially by pan-Bcl-2 inhibitors, might also hamper the antioxidative capacity of cells. Given the fact that oxidative stress is also known to stimulate autophagy in several experimental paradigms (53,54), it is presumably involved in the prominent induction of gossypol-dependent autophagy observed in our experiments. Indeed, (−)-gossypol was previously shown to be a potent inductor of oxidative stress in colorectal cancer cells (22).…”

Bcl-2 family member Mcl-1 expression is reduced under hypoxia by the E3 ligase FBW7 contributing to BNIP3 induced cell death in glioma cells

“…37 Briefly, trypan blue is excluded from live cells but penetrates dead cells giving a red fluorescent signal that can be quantified by flow cytometry.…”

Molecular Mechanisms of Pesticide Toxicity

“…•O2 -is the major ROS regulating autophagy (Chen et al, 2009). Recent studies provide strong evidences for the involvement of mitochondrially-generated ROS production in the induction of autophagy (Chen & Gibson, 2008;Chen et al, 2009).…”

“…Recent studies provide strong evidences for the involvement of mitochondrially-generated ROS production in the induction of autophagy (Chen & Gibson, 2008;Chen et al, 2009). Recently, it has been demonstrated that targeting mETC complex I by rotenone, induces autophagic cell death through a ROS-mediated mechanism (Chen et al, 2007).…”