Autophagy protects the rotenone-induced cell death in α-synuclein overexpressing SH-SY5Y cells
Department of Biochemistry and Neurobiology and Institute of Health Sciences, Gyeongsang National University School of Medicine, 92 Chilam-Dong, Jinju, GyeongNam 660-751, Republic of Korea. Neuroscience Letters
(Impact Factor: 2.03).
03/2010; 472(1):47-52. DOI: 10.1016/j.neulet.2010.01.053
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.
Available from: Joonki Kim
- "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. "
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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.
Available from: Carsten Culmsee
- "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. "
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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.
Available from: Jae-Hyeon Park
- "To investigate the potential role of autophagy enhancement, we performed an MTS assay by pretreating cells with 100 nM rapamycin prior to FPN treatment in accordance with a previous study (Dadakhujaev et al., 2010). In this study, we used rapamycin as an autophagy inducer. "
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ABSTRACT: Oxidative stress created by environmental toxicants activates several signaling pathways. Autophagy is one of the first lines of defense against oxidative stress damage. The autophagy pathway can be induced and up-regulated in response to intracellular reactive oxygen species (ROS). Recently, we reported that fipronil (FPN)-induced mitochondria-dependent apoptosis is mediated through ROS in human neuroblastoma SH-SY5Y cells. In this study, we explored the role of autophagy to prevent FPN neurotoxicity. We investigated the modulation of FPN-induced apoptosis according to autophagy regulation. FPN activated caspase-9 and caspase-3, and induced nuclear fragmentation and condensation, all of which indicate that FPN-induced cell death was due to apoptosis. In addition, we observed FPN-induced autophagic cell death by monitoring the expression of LC3-II and Beclin-1. Exposure to FPN in SH-SY5Y cells led to the production of ROS. Treatment with N-acetyl-cysteine (NAC) effectively blocked both apoptosis and autophagy. Interestingly, pretreatment with rapamycin, an autophagy inducer, significantly enhanced the viability of FPN-exposed cells; the enhancement of cell viability was partially due to alleviation of FPN-induced apoptosis via a decrease in levels of cleaved caspase-3. However, pretreatment with 3-methyladenine (3MA) a specific inhibitor for autophagy, remarkably strengthened FPN toxicity and further induced activation of caspase-3 in these cells. Our studies suggest that FPN-induced cytotoxicity is modified by autophagy regulation and that rapamycin is neuroprotective against FPN-induced apoptosis through enhancing autophagy.
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