Autophagy protects the rotenone-induced cell death in α-synuclein overexpressing SH-SY5Y cells
ABSTRACT Loss of dopaminergic cells induced by alpha-synuclein accumulation in substantia nigra causes the development of Parkinson's disease (PD). To date, although autophagy has been implicated in the pathology of PD, the molecular mechanism is still unclear. To study the role of autophagy in PD pathogenesis, we established stable SH-SY5Y cell lines overexpressing wild-type or mutant alpha-synuclein proteins (A30P or A53T). Overexpression of mutant alpha-synuclein induced some protein aggregates and cell death in the absence of drug. LC3-II protein, a critical marker for autophagy, was produced in an autophagy-dependent manner. The rotenone-induced cell death was interrupted by autophagy stimulation. Autophagy activation also restored the mitochondrial membrane potential (MMP) impaired by rotenone in mutant alpha-synuclein expressing cells. Additionally, autophagy activation significantly relieved rotenone-induced ROS accumulation and HIF-1alpha expression in neuronal cells expressing mutant alpha-synuclein proteins. These findings indicate that autophagy plays an important scavenger role against harmful influence of toxic protein aggregates produced in rotenone-treated cells.
- SourceAvailable from: Joonki Kim
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- "Basal expression of autophagy acts as one of the cytoprotective mechanisms and participates in maintaining homeostasis (Hara et al., 2006; Dadakhujaev et al., 2010). Also in diseased conditions, autophagy enhancement is known to play a role as protective mechanism. "
ABSTRACT: Autophagy is a series of catabolic process mediating the bulk degradation of intracellular proteins and organelles through formation of a double-membrane vesicle, known as an autophagosome, and fusing with lysosome. Autophagy plays an important role of death-survival decisions in neuronal cells, which may influence to several neurodegenerative disorders including Parkinson's disease. Chebulagic acid, the major constituent of Terminalia chebula and Phyllanthus emblica, is a benzopyran tannin compound with various kinds of beneficial effects. This study was performed to investigate the autophagy enhancing effect of chebulagic acid on human neuroblastoma SH-SY5Y cell lines. We determined the effect of chebulagic acid on expression levels of autophago-some marker proteins such as, DOR/TP53INP2, Golgi-associated ATPase Enhancer of 16 kDa (GATE 16) and Light chain 3 II (LC3 II), as well as those of its upstream pathway proteins, AMP-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR) and Beclin-1. All of those proteins were modulated by chebulagic acid treatment in a way of enhancing the autophagy. Additionally in our study, chebulagic acid also showed a protective effect against 1-methyl-4-phenylpyridinium (MPP(+)) - induced cytotoxicity which mimics the pathological symptom of Parkinson's disease. This effect seems partially mediated by enhanced autophagy which increased the degradation of aggregated or misfolded proteins from cells. This study suggests that chebulagic acid is an attractive candidate as an autophagy-enhancing agent and therefore, it may provide a promising strategy to prevent or cure the diseases caused by accumulation of abnormal proteins including Parkinson's disease.Biomolecules and Therapeutics 07/2014; 22(4):275-81. DOI:10.4062/biomolther.2014.068 · 0.84 Impact Factor
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- "Recent studies have implicated macroautophagy, from here on referred to as " autophagy " , in the pathophysiology of PD (Lynch- Day et al., 2012). Still, there is an ongoing debate if alpha-synuclein itself would inhibit (Winslow and Rubinsztein, 2011; Winslow et al., 2010) or activate autophagy (Choubey et al., 2011; Stefanis et al., 2001; Xilouri et al., 2009) and whether increased autophagy would be protective (Dadakhujaev et al., 2010; Spencer et al., 2009) or harmful (Choubey et al., 2011; Li et al., 2011) for neurons. We report here that wild-type alpha-synuclein readily kills the human postmitotic dopaminergic neurons derived from primary precursor cells, and that pharmacologic activation of autophagy with trifluoperazine (10-[3-(4-methylpiperazin-1-yl) propyl]-2- (trifluoromethyl) phenothiazine) provides protection by reducing one specific oligomeric alpha-synuclein species. "
ABSTRACT: Parkinson's disease (PD) is the most frequent neurodegenerative movement disorder. Presently, there is no causal therapy available to slow down or halt disease progression. The presynaptic protein alpha-synuclein aggregates to form intraneuronal Lewy bodies in PD. It is generally believed that intermediates on the way from monomers to the large aggregates would mediate neurotoxicity, but the precise species and mechanism responsible for neuronal death are controversially debated. To study alpha-synuclein-mediated toxicity, we developed a new model in which moderate overexpression of wild-type alpha-synuclein led to gradual death of human postmitotic dopaminergic neurons. In accordance with findings in postmortem PD brains, small oligomeric species occurred and the autophagic flux was impaired in our model. The phenothiazine neuroleptic trifluoperazine, an activator of macroautophagy, selectively reduced one particular alpha-synuclein species and rescued cells. Inversely, blocking of autophagy led to an accumulation of this oligomeric species and increased cell death. These data show that activation of autophagy is a promising approach to protect against alpha-synuclein pathology and likely acts by targeting one specific alpha-synuclein species.Neurobiology of aging 01/2014; 35(7). DOI:10.1016/j.neurobiolaging.2014.01.027 · 4.85 Impact Factor
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- "Induction of autophagy mediated by rapamycin also prevents rotenone-dependent apoptosis in SH-SY5Y cells (Pan et al., 2009). Autophagy activation restores the mitochondrial membrane potential impaired by rotenone in SH-SY5Y cell lines overexpressing alpha-synuclein (Dadakhujaev et al., 2010). Aminochrome induces both apoptosis features and autophagy where apoptosis leads to the cell death and autophagy is working as a rescue mechanism to recycle damaged mitochondria in order to prevent the cell death. "
ABSTRACT: Aminochrome, the precursor of neuromelanin, has been proposed to be involved in the neurodegeneration neuromelanin-containing dopaminergic neurons in Parkinson's disease. We aimed to study the mechanism of aminochrome-dependent cell death in a cell line derived from rat substantia nigra. We found that aminochrome (50μM), in the presence of NAD(P)H-quinone oxidoreductase, EC 22.214.171.124 (DT)-diaphorase inhibitor dicoumarol (DIC) (100μM), induces significant cell death (62 ± 3%; p < 0.01), increase in caspase-3 activation (p < 0.001), release of cytochrome C, disruption of mitochondrial membrane potential (p < 0.01), damage of mitochondrial DNA, damage of mitochondria determined with transmission electron microscopy, a dramatic morphological change characterized as cell shrinkage, and significant increase in number of autophagic vacuoles. To determine the role of autophagy on aminochrome-induced cell death, we incubated the cells in the presence of vinblastine and rapamycin. Interestingly, 10μM vinblastine induces a 5.9-fold (p < 0.001) and twofold (p < 0.01) significant increase in cell death when the cells were incubated with 30μM aminochrome in the absence and presence of DIC, respectively, whereas 10μM rapamycin preincubated 24 h before addition of 50μM aminochrome in the absence and the presence of 100μM DIC induces a significant decrease (p < 0.001) in cell death. In conclusion, autophagy seems to be an important protective mechanism against two different aminochrome-induced cell deaths that initially showed apoptotic features. The cell death induced by aminochrome when DT-diaphorase is inhibited requires activation of mitochondrial pathway, whereas the cell death induced by aminochrome alone requires inhibition of autophagy-dependent degrading of damaged organelles and recycling through lysosomes.Toxicological Sciences 03/2011; 121(2):376-88. DOI:10.1093/toxsci/kfr060 · 4.48 Impact Factor