Reference - Detail
|Author||Tripathi DN, Chowdhury R, Trudel LJ, Tee AR, Slack RS, Walker CL, Wogan GN.|
|Title||Reactive nitrogen species regulate autophagy through ATM-AMPK-TSC2-mediated suppression of mTORC1.|
|Journal||Proc Natl Acad Sci U S A|
Reactive intermediates such as reactive nitrogen species play essential roles in the cell as signaling molecules but, in excess, constitute a major source of cellular damage. We found that nitrosative stress induced by steady-state nitric oxide (NO) caused rapid activation of an ATM damage-response pathway leading to downstream signaling by this stress kinase to LKB1 and AMPK kinases, and activation of the TSC tumor suppressor. As a result, in an ATM-, LKB1-, TSC-dependent fashion, mTORC1 was repressed, as evidenced by decreased phosphorylation of S6K, 4E-BP1, and ULK1, direct targets of the mTORC1 kinase. Decreased ULK1 phosphorylation by mTORC1 at S757 and activation of AMPK to phosphorylate ULK1 at S317 in response to nitrosative stress resulted in increased autophagy: the LC3-II/LC3-I ratio increased as did GFP-LC3 puncta and acidic vesicles; p62 levels decreased in a lysosome-dependent manner, confirming an NO-induced increase in autophagic flux. Induction of autophagy by NO correlated with loss of cell viability, suggesting that, in this setting, autophagy was functioning primarily as a cytotoxic response to excess nitrosative stress. These data identify a nitrosative-stress signaling pathway that engages ATM and the LKB1 and TSC2 tumor suppressors to repress mTORC1 and regulate autophagy. As cancer cells are particularly sensitive to nitrosative stress, these data open another path for therapies capitalizing on the ability of reactive nitrogen species to induce autophagy-mediated cell death.
|MeSH||AMP-Activated Protein Kinase Kinases AMP-Activated Protein Kinases / metabolism* Animals Ataxia Telangiectasia Mutated Proteins Autophagy / drug effects Autophagy / physiology* Blotting, Western Cell Cycle Proteins / genetics Cell Cycle Proteins / metabolism* Cells, Cultured DNA-Binding Proteins / genetics DNA-Binding Proteins / metabolism* Embryo, Mammalian / cytology Fibroblasts / cytology Fibroblasts / drug effects Fibroblasts / metabolism HeLa Cells Humans MCF-7 Cells Mice Mice, Knockout Models, Biological Multiprotein Complexes / metabolism Nitric Oxide / metabolism Nitric Oxide / physiology Nitric Oxide Donors / metabolism Nitric Oxide Donors / pharmacology Phosphorylation / drug effects Protein Serine-Threonine Kinases / genetics Protein Serine-Threonine Kinases / metabolism* Reactive Oxygen Species / metabolism* Signal Transduction / drug effects Spermine / analogs & derivatives Spermine / metabolism Spermine / pharmacology TOR Serine-Threonine Kinases / metabolism* Tuberous Sclerosis Complex 2 Protein Tumor Suppressor Proteins / genetics Tumor Suppressor Proteins / metabolism*|
|Human and Animal Cells||MCF7(RCB1904)|