Autophagy protects the rotenone-induced cell death in alpha-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.
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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.Neurobiology of aging 01/2014; · 5.94 Impact Factor
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ABSTRACT: Since their discovery, Parkinsonian toxins (6-hydroxydopamine, MPP+, paraquat, and rotenone) have been widely employed as in vivo and in vitro chemical models of PD. Alterations in mitochondrial homeostasis, protein quality control pathways, and more recently, autophagy/mitophagy have been implicated in neurotoxin models of Parkinson’s disease (PD). Here, we highlight the molecular mechanisms by which different PD toxins dysregulate autophagy/mitophagy and how alterations of these pathways play beneficial or detrimental roles in dopamine neurons. The convergent and divergent effects of PD toxins on mitochondrial function and autophagy/mitophagy are also discussed in this review. Furthermore, we propose new diagnostic tools and discuss how pharmacological modulators of autophagy/mitophagy can be developed as disease-modifying treatments for PD. Finally, we discuss the critical need to identify endogenous and synthetic forms of PD toxins and develop efficient health preventive programs to mitigate the risk of developing PD.International Journal of Molecular Sciences 10/2013; · 2.46 Impact Factor
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ABSTRACT: Autophagy plays different roles in the growth and development process of different cells. The role of autophagy in the differentiation process of adult adipose-derived stromal cells (ADSCs) into astrocytes is unclear. We researched the role of autophagy in the induction process by adding autophagy agonist rapamycin, which was not added in the control group. Immunocytochemistry showed that the expression of glial fibrillary acidic protein (GFAP) was increased gradually with the extending reaction time and had reached the peak on the 14th day. Typical autophagy ultrastructure, including autophagic bodies and self-macrophage lysosomal, was shown under transmission electron microscopy (TEM) when cells were induced for 14 days. By methyl thiazolyl tetrazolium (MTT) assay, we found that the number of living cells was reduced gradually, and early apoptosis rate was increased by flow cytometry. We observed that the differentiation ratio, the number of living cells, and the positive expression rates of GFAP in the rapamycin group were higher than those in the control group when ADSCs were induced for 48 h and 7 days (P < 0.01); however, the rates of early apoptosis were lower than those in the control group. The positive rate of microtubule-associated protein light chain 3 (LC3) in the rapamycin group had been up to 88.87 % on the 7th day (P < 0.01), but not obvious with extending time. After 14 days of induction, the optical density (OD) value of surviving cells was declined, and early apoptosis rate was increased gradually. The results showed that adding autophagy agonist to the inducers may enhance intensity of autophagy, shorten the induction time, and improve the efficiency of differentiation.Journal of Molecular Neuroscience 01/2014; · 2.89 Impact Factor