Multi-mechanisms are involved in reactive oxygen species regulation of  mTORC1 signaling.
The mammalian target of rapamycin complex 1(mTORC1) integrates diverse signals to control cell growth, proliferation, survival, and metabolism. Role of reactive oxygen species (ROS) on mTORC1 signaling remains obscure and mechanisms through which ROS modulate mTORC1 are not known.We demonstrate that low doses ROS exposure stimulate mTORC1 while high concentrations or long-term ROS treatment decrease mTORC1 activity in vivo and in a variety of cell lines. The dose/time needed for inhibition or activation are cell type dependent. In HEK293 cells hydrogen peroxide (H(2)O(2)) stimulates phosphorylation of AMP-activated kinase (AMPK) (T172) and Raptor (S792), enhances association of activated AMPK with Raptor. Furthermore, AMPK inhibitor compound c inhibits H(2)O(2)-induced Raptor (S792) phosphorylation and reverses H(2)O(2)-induced dephosphorylation of mTORC1 downstream targets p70-S6K1 (T389), S6 (S235/236) and 4E-BP1 (T37/46). H(2)O(2) also stimulates association of endogenous protein phosphatase 2A catalytic subunit (PP2Ac) with p70-S6K1. Like compound c, inhibitor of PP2A, okadaic acid partially reverses inactivation of mTORC1 substrates induced by H(2)O(2). Moreover, inhibition of PP2A and AMPK partially rescued cells from H(2)O(2)-induced cell death. High doses of H(2)O(2) inhibit while low doses of H(2)O(2) activate mTORC1 both in TSC2(-/-) P53(-/-) and TSC2(+/+) P53(-/-) MEFs. These data suggest that PP2A and AMPK-mediated phosphorylation of Raptor mediate H(2)O(2)-induced inhibition of mTORC1 signaling.
Li
Ming
M
Department of Cell Biology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China.
Zhao
Li
L
Liu
Jun
J
Liu
Anling
A
Jia
Chunhong
C
Ma
Dongzhu
D
Jiang
Yu
Y
Bai
Xiaochun
X
D055372:AMP-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D054648:Protein Phosphatase 2 / Q000037:antagonists & inhibitors / Q000502:physiology; D011506:Proteins / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism*; D000076223:Regulatory-Associated Protein of mTOR; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D015398:Signal Transduction; D058570:TOR Serine-Threonine Kinases; D014157:Transcription Factors / Q000378:metabolism*; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins / Q000502:physiology
D055372:AMP-Activated Protein Kinases; D048868:Adaptor Proteins, Signal Transducing; D006861:Hydrogen Peroxide; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases; D054648:Protein Phosphatase 2; D011506:Proteins; D017382:Reactive Oxygen Species; D000076223:Regulatory-Associated Protein of mTOR; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D014157:Transcription Factors; D000077005:Tuberous Sclerosis Complex 2 Protein; D025521:Tumor Suppressor Proteins; C463659:RPTOR protein, human; C000624653:TSC2 protein, human; C000624654:Tsc2 protein, mouse