Autophagy-dependent and -independent involvement of AMP-activated protein kinase in 6-hydroxydopamine toxicity to SH-SY5Y neuroblastoma cells.
Biochim Biophys Acta
; 1822(11): 1826-36, 2012 Nov.
Article
en En
| MEDLINE
| ID: mdl-22917563
The role of the main intracellular energy sensor adenosine monophosphate (AMP)-activated protein kinase (AMPK) in the induction of autophagic response and cell death was investigated in SH-SY5Y human neuroblastoma cells exposed to the dopaminergic neurotoxin 6-hydroxydopamine (6-OHDA). The induction of autophagy in SH-SY5Y cells was demonstrated by acridine orange staining of intracellular acidic vesicles, the presence of autophagosome- and autophagolysosome-like vesicles confirmed by transmission electron microscopy, as well as by microtubule-associated protein 1 light-chain 3 (LC3) conversion and p62 degradation detected by immunoblotting. 6-OHDA induced phosphorylation of AMPK and its target Raptor, followed by the dephosphorylation of the major autophagy inhibitor mammalian target of rapamycin (mTOR) and its substrate p70S6 kinase (S6K). 6-OHDA treatment failed to suppress mTOR/S6K phosphorylation and to increase LC3 conversion, p62 degradation and cytoplasmatic acidification in neuroblastoma cells in which AMPK expression was downregulated by RNA interference. Transfection of SH-SY5Y cells with AMPK or LC3ß shRNA, as well as treatment with pharmacological autophagy inhibitors suppressed, while mTOR inhibitor rapamycin potentiated 6-OHDA-induced oxidative stress and apoptotic cell death. 6-OHDA induced phosphorylation of p38 mitogen-activated protein (MAP) kinase in an AMPK-dependent manner, and pharmacological inhibition of p38 MAP kinase reduced neurotoxicity, but not AMPK activation and autophagy triggered by 6-OHDA. Finally, the antioxidant N-acetyl cysteine antagonized 6-OHDA-induced activation of AMPK, p38 and autophagy. These data suggest that oxidative stress-mediated AMPK/mTOR-dependent autophagy and AMPK/p38-dependent apoptosis could be valid therapeutic targets for neuroprotection.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Autofagia
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Oxidopamina
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Apoptosis
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Proteínas Quinasas Activadas por AMP
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Neuroblastoma
Límite:
Humans
Idioma:
En
Revista:
Biochim Biophys Acta
Año:
2012
Tipo del documento:
Article
Pais de publicación:
Países Bajos