Parkinson’s disease (PD) is a neurodegenerative disorder characterized by alpha-synuclein accumulation and loss of dopaminergic neurons in the substantia nigra (SN) region of the brain. Increased levels of alpha-synuclein have been shown to result in loss of mitochondrial electron transport chain complex I activity leading to increased reactive oxygen species (ROS) production. WT alpha-synuclein was stably overexpressed in human BE(2)-M17 neuroblastoma cells resulting in increased levels of an alpha-synuclein multimer, but no increase in alpha-synuclein monomer levels. Oxygen consumption was decreased by alpha-synuclein overexpression, but ATP levels did not decrease and ROS levels did not increase. Treatment with ferrous sulfate, a ROS generator, resulted in decreased oxygen consumption in both control and alpha-synuclein overexpressing cells. However, this treatment only decreased ATP levels and increased ROS production in the cells overexpressing alpha-synuclein. Similarly, paraquat, another ROS generator, decreased ATP levels in the alpha-synuclein overexpressing cells, but not in the control cells, further demonstrating how alpha-synuclein sensitized the cells to oxidative insult. Proteomic analysis yielded molecular insights into the cellular adaptations to alpha-synuclein overexpression, such as the increased abundance of many mitochondrial proteins. Many amino acids and citric acid cycle intermediates and their ester forms were individually supplemented to the cells with l-serine, l-proline, l-aspartate, or l-glutamine decreasing ROS production in oxidatively stressed alpha-synuclein overexpressing cells, while diethyl oxaloacetate or l-valine supplementation increased ATP levels. These results suggest that dietary supplementation with individual metabolites could yield bioenergetic improvements in PD patients to delay loss of dopaminergic neurons.
|Number of pages||23|
|State||Published - Sep 1 2017|
Bibliographical noteFunding Information:
This study was supported by East Tennessee State University and University of South Florida funds provided to PCB. VD, JG, and PB conceived the experiments. VD, SZ, YZ, TP, CR, VBD, JC, EC, EF, and HG performed the ATP, ROS, and oxygen consumption assays in the main section of the paper. JG performed the ATP, ROS, and viability assays in the supplemental data. VD, DC, SS, HM, and PB contributed to the proteomics experiments and data analysis. UJ and DL constructed and provided the stably transfected M17 cell line, respectively. DP and DL performed and supervised the Western blot analysis, respectively. VD and PB wrote the paper.
© 2017, Springer Science+Business Media, LLC.
- Amino acids
- Citric acid cycle
- Metabolic therapy
- Parkinson’s disease
ASJC Scopus subject areas
- Molecular Medicine
- Cellular and Molecular Neuroscience