Hydrogen peroxide inhibits mTOR signaling by activation of AMPKalpha leading to apoptosis of neuronal cells.
Oxidative stress results in apoptosis of neuronal cells, leading to neurodegenerative disorders. However, the underlying molecular mechanism remains to be elucidated. Here, we show that hydrogen peroxide (H(2)O(2)), a major oxidant generated when oxidative stress occurs, induced apoptosis of neuronal cells (PC12 cells and primary murine neurons), by inhibiting the mammalian target of rapamycin (mTOR)-mediated phosphorylation of ribosomal p70 S6 kinase (S6K1) and eukaryotic initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1). N-acetyl-L-cysteine (NAC), a scavenger of reactive oxygen species (ROS), blocked H(2)O(2) inhibition of mTOR signaling. Ectopic expression of wild-type (wt) mTOR, constitutively active S6K1 or downregulation of 4E-BP1 partially prevented H(2)O(2) induction of apoptosis. Furthermore, we identified that H(2)O(2) induction of ROS inhibited the upstream kinases, Akt and phosphoinositide-dependent kinase 1 (PDK1), but not the type I insulin-like growth factor receptor (IGFR), and activated the negative regulator, AMP-activated protein kinase alpha (AMPKalpha), but not the phosphatase and tensin homolog (PTEN) in the cells. Expression of a dominant negative AMPKalpha or downregulation of AMPKalpha1 conferred partial resistance to H(2)O(2) inhibition of phosphorylation of S6K1 and 4E-BP1, as well as cell viability, indicating that H(2)O(2) inhibition of mTOR signaling is at least in part through activation of AMPK. Our findings suggest that AMPK inhibitors may be exploited for prevention of H(2)O(2)-induced neurodegenerative diseases.
Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA, USA.
Long
L
Chen
Baoshan
B
Xu
Lei
L
Liu
Yan
Y
Luo
Jun
J
Yin
Hongyu
H
Zhou
Wenxing
W
Chen
Tao
T
Shen
Xiuzhen
X
Han
Shile
S
Huang
D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002460:Cell Line; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016877:Oxidants / Q000494:pharmacology; D016716:PC12 Cells; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects*; D058570:TOR Serine-Threonine Kinases
D047908:Intracellular Signaling Peptides and Proteins; D016877:Oxidants; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; D006861:Hydrogen Peroxide; C546842:MTOR protein, human; C546843:mTOR protein, mouse; D017346:Protein Serine-Threonine Kinases; D019893:Ribosomal Protein S6 Kinases; D058570:TOR Serine-Threonine Kinases; D055372:AMP-Activated Protein Kinases