Abstract |
Autophagy is a fundamental cellular recycling process vulnerable to compromise in neurodegeneration. We now report that a cell-penetrating neurotrophic and neuroprotective derivative of the central nervous system (CNS) metabolite, lanthionine ketimine (LK), stimulates autophagy in RG2 glioma and SH-SY5Y neuroblastoma cells at concentrations within or below pharmacological levels reported in previous mouse studies. Autophagy stimulation was evidenced by increased lipidation of microtubule-associated protein 1 light chain 3 (LC3) both in the absence and presence of bafilomycin-A1 which discriminates between effects on autophagic flux versus blockage of autophagy clearance. LKE treatment caused changes in protein level or phosphorylation state of multiple autophagy pathway proteins including mTOR; p70S6 kinase; unc-51-like-kinase-1 (ULK1); beclin-1 and LC3 in a manner essentially identical to effects observed after rapamycin treatment. The LKE site of action was near mTOR because neither LKE nor the mTOR inhibitor rapamycin affected tuberous sclerosis complex ( TSC) phosphorylation status upstream from mTOR. Confocal immunofluorescence imaging revealed that LKE specifically decreased mTOR (but not TSC2) colocalization with LAMP2(+) lysosomes in RG2 cells, a necessary event for mTORC1-mediated autophagy suppression, whereas rapamycin had no effect. Suppression of the LK-binding adaptor protein CRMP2 ( collapsin response mediator protein-2) by means of shRNA resulted in diminished autophagy flux, suggesting that the LKE action on mTOR localization may occur through a novel mechanism involving CRMP2-mediated intracellular trafficking. These findings clarify the mechanism-of-action for LKE in preclinical models of CNS disease, while suggesting possible roles for natural lanthionine metabolites in regulating CNS autophagy.
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Authors | Marni E Harris-White, Kathie G Ferbas, Ming F Johnson, Pirooz Eslami, Aleksandra Poteshkina, Kalina Venkova, Alexandar Christov, Kenneth Hensley |
Journal | Neurobiology of disease
(Neurobiol Dis)
Vol. 84
Pg. 60-8
(Dec 2015)
ISSN: 1095-953X [Electronic] United States |
PMID | 25779968
(Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)
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Copyright | Copyright © 2015 Elsevier Inc. All rights reserved. |
Chemical References |
- Amino Acids, Sulfur
- Immunosuppressive Agents
- Intercellular Signaling Peptides and Proteins
- Multiprotein Complexes
- Nerve Tissue Proteins
- Neuroprotective Agents
- TSC2 protein, human
- Tsc2 protein, mouse
- Tsc2 protein, rat
- Tuberous Sclerosis Complex 2 Protein
- Tumor Suppressor Proteins
- collapsin response mediator protein-2
- lanthionine ketimine
- Mechanistic Target of Rapamycin Complex 1
- TOR Serine-Threonine Kinases
- Sirolimus
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Topics |
- Amino Acids, Sulfur
(chemistry, pharmacology)
- Animals
- Autophagy
(drug effects, physiology)
- Cell Line, Tumor
- Humans
- Immunosuppressive Agents
(pharmacology)
- Intercellular Signaling Peptides and Proteins
(metabolism)
- Lysosomes
(drug effects, metabolism)
- Mechanistic Target of Rapamycin Complex 1
- Multiprotein Complexes
(antagonists & inhibitors, metabolism)
- Nerve Tissue Proteins
(metabolism)
- Neuroprotective Agents
(pharmacology)
- Rats
- Sirolimus
(pharmacology)
- TOR Serine-Threonine Kinases
(antagonists & inhibitors, metabolism)
- Tuberous Sclerosis Complex 2 Protein
- Tumor Suppressor Proteins
(metabolism)
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