Region specific mitochondrial impairment in mice with widespread overexpression of alpha-synuclein

NEUROBIOLOGY OF DISEASE

卷:70

Article

Subramaniam, Sudhakar Raja¹  Vergnes, Laurent²  Franich, Nicholas R.¹  Reue, Karen²  Chesselet, Marie-Francoise¹ 

[1] Univ Calif Los Angeles, David Geffen Sch Med, Dept Neurol, Los Angeles, CA 90095 USA

[2] Univ Calif Los Angeles, David Geffen Sch Med, Dept Human Genet, Los Angeles, CA 90095 USA

关键词: Alpha synuclein;    Mitochondrial dysfunction;    Peroxiredoxin;    Lipid peroxidation;    Oxidative damage;   

DOI  :  10.1016/j.nbd.2014.06.017

来源: Elsevier

【 摘 要 】

Parkinson's disease (PD) is characterized by the progressive degeneration of nigrostriatal dopaminergic neurons leading to motor deficits. The mechanisms underlying the preferential vulnerability of nigrostriatal dopaminergic neurons in PD remain poorly understood. Recent evidence supports a role for mitochondrial dysfunction and increased oxidative stress in PD pathogenesis. Genetic and pathological studies also point to alpha-synuclein as a critical factor in both familial and sporadic forms of the disease; alpha-synuclein pathology affects mitochondrial function but is widespread in PD brain, raising the question of its role in the greater vulnerability of nigrostriatal neurons in PD. We have examined mitochondrial function and oxidative damage in mice overexpressing human wild type alpha-synuclein broadly throughout the nervous system under the Thy1 promoter (Thy1-aSyn mice) between 4 and 8 months of age. Similar levels of alpha-synuclein accumulation in mitochondria were detected in the ventral midbrain, striatum and cortex of Thy1-aSyn mice. However, analysis of mitochondrial respiration using Seahorse XF analyzer showed defects in mitochondrial respiratory complexes I, II, IV and V specifically in the midbrain, and IV and V in the striatum, of Thy1-aSyn mice compared to wild type littermates; mitochondria( complex I activity assay by ELISA confirmed a 40% inhibition specifically in the ventral midbrain. Mitochondrial dysfunction can contribute to oxidative stress and we observed a 40% increase in 4-hydroxynenal and 2-fold increase in malondialdehyde levels, indicative of a high level of lipid peroxidation, specifically in the ventral midbrain of Thy1-aSyn mice. The levels of peroxiredoxin 2, a neuronal antioxidant enzyme that is involved in removal of H2O2 and other toxic peroxides were decreased in the midbrain whereas its oxidized form increased 4-fold, suggesting that antioxidant defenses were compromised in this region. In contrast peroxiredoxin 2 increased in the striatum and cortex, which may contribute to their protection in the presence of high levels of alpha-synuclein. Thus, in mice over-expressing alpha-synudein, mitochondrial dysfunction occurred preferentially in nigrostriatal dopaminergic neurons many months before striatal dopamine loss occurs at 14 months of age. This may contribute to a higher level of oxidative stress that overwhelms antioxidant defense in these neurons, leading to their increased vulnerability in PD. (C) 2014 Elsevier Inc. All rights reserved.

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