Distinct Mechanisms of Neurodegeneration Induced by Chronic Complex I Inhibition in Dopaminergic and Non-dopaminergic Cells

Baylor University, Waco, Texas, United States
Journal of Biological Chemistry (Impact Factor: 4.57). 01/2005; 279(50):51783-92. DOI: 10.1074/jbc.M407336200
Source: PubMed


Chronic mitochondrial dysfunction, in particular of complex I, has been strongly implicated in the dopaminergic neurodegeneration in Parkinson's disease. To elucidate the mechanisms of chronic complex I disruption-induced neurodegeneration, we induced differentiation of immortalized midbrain dopaminergic (MN9D) and non-dopaminergic (MN9X) neuronal cells, to maintain them in culture without significant cell proliferation and compared their survivals following chronic exposure to nanomolar rotenone, an irreversible complex I inhibitor. Rotenone killed more dopaminergic MN9D cells than non-dopaminergic MN9X cells. Oxidative stress played an important role in rotenone-induced neurodegeneration of MN9X cells, but not MN9D cells: rotenone oxidatively modified proteins more in MN9X cells than in MN9D cells and antioxidants decreased rotenone toxicity only in MN9X cells. MN9X cells were also more sensitive to exogenous oxidants than MN9D cells. In contrast, disruption of bioenergetics played a more important role in MN9D cells: rotenone decreased mitochondrial membrane protential and ATP levels in MN9D cells more than in MN9X cells. Supplementation of cellular energy with a ketone body, D-beta-hydroxybutyrate, decreased rotenone toxicity in MN9D cells, but not in MN9X cells. MN9D cells were also more susceptible to disruption of oxidative phosphorylation or glycolysis than MN9X cells. These findings indicate that, during chronic rotenone exposure, MN9D cells die primarily through mitochondrial energy disruption, whereas MN9X cells die primarily via oxidative stress. Thus, intrinsic properties of individual cell types play important roles in determining the predominant mechanism of complex I inhibition-induced neurodegeneration.

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    • "The cells result from a fusion of rostral mesencephalic neurons from embryonic C57BL/6J (E14) mice with the N18TG2 neuroblastoma cells [21]. There are a number of important similarities between these cells and DA neurons [21], and we have found them be a valuable model for studies of the DA deficiency associated with PD [20], [27], [28], [29], as have many others [e.g., [30],[31], [32], [33]. "
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    ABSTRACT: Mild stress can protect against a larger insult, a phenomenon termed preconditioning or tolerance. To determine if a low intensity stressor could also protect cells against intense oxidative stress in a model of dopamine deficiency associated with Parkinson disease, we used methamphetamine to provide a mild, preconditioning stress, 6-hydroxydopamine (6-OHDA) as a source of potentially toxic oxidative stress, and MN9D cells as a model of dopamine neurons. We observed that prior exposure to subtoxic concentrations of methamphetamine protected these cells against 6-OHDA toxicity, whereas higher concentrations of methamphetamine exacerbated it. The protection by methamphetamine was accompanied by decreased uptake of both [(3)H] dopamine and 6-OHDA into the cells, which may have accounted for some of the apparent protection. However, a number of other effects of methamphetamine exposure suggest that the drug also affected basic cellular survival mechanisms. First, although methamphetamine preconditioning decreased basal pERK1/2 and pAkt levels, it enhanced the 6-OHDA-induced increase in these phosphokinases. Second, the apparent increase in pERK1/2 activity was accompanied by increased pMEK1/2 levels and decreased activity of protein phosphatase 2. Third, methamphetamine upregulated the pro-survival protein Bcl-2. Our results suggest that exposure to low concentrations of methamphetamine cause a number of changes in dopamine cells, some of which result in a decrease in their vulnerability to subsequent oxidative stress. These observations may provide insights into the development of new therapies for prevention or treatment of PD.
    Full-text · Article · Oct 2011 · PLoS ONE
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    • "Administration of 4 mmol/L β-OHB increased the survival of cultured neurons from 1- methyl-4-phenylpyridinium toxicity (Kashiwaya et al, 2000). Another in vitro model of Parkinson's disease utilizes rotenone, which inhibits mitochondrial complex I. Application of 8 mmol/L β-OHB to this model of Parkinson's increased cell survival, improved mitochondrial membrane potential and reduced cytochrome c release in mouse neuronal cultures (Imamaura et al, 2006), and increased cell survival by 60% in human neuroblastoma cell culture (Kweon et al, 2004). More recently, 24 h infusion of β-OHB in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine mice showed 45% decrease in motor deficits and a decrease in dopaminergic neurodegeneration (Tieu et al, 2003). "
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    • "Additionally, the rotenone induced-degeneration of dopaminergic neurons in the nigrostriatal region may also be attributed to the activation of microglia, the resident macrophages in the brain, in response to the widespread oxidative damage provoked by rotenone [Gao et al., 2002; 2003; Sherer et al., 2003a]. In cell culture models, inhibition of complex I with rotenone causes cell death in a variety of cell types, including dopaminergic and non-dopaminergic neurons, via distinct mechanisms [Kweon et al., 2004]. The multiple effects caused by rotenone on cell survival and integrity triggers the assumption that the common use/exposure to rotenone may be a risk factor contributing to the development of neurodegenerative diseases. "
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