The long-term goal of this proposal is to elucidate the mechanism by which mitochondrial oxidative stress produces dopaminergic neuronal death in Parkinson's Disease (PD). The precise mechanism by which mitochondrial oxidative stress, bioenergetic decline and iron overload arise and collaborate to produce age-related neuronal death in Parkinson's disease remains unclear. It is hypothesized that neuronal damage in Parkinson's disease results, in part from direct superoxide radical toxicity due to oxidative inactivation of mitochondrial aconitase. The hypothesis predicts that superoxide production, arising from Complex I inhibition or abnormal dopamine metabolism, inactivates [4Fe-4S]Z+-containing mitochondrial aconitase, resulting in loss of aconitase activity and release Fe z+ and H202. Posttranslational modification of this key TCA cycle enzyme can therefore result in an increased iron load, oxidant burden and bioenergetic decline. The presence of an iron responsive element (IRE) in the 5' untranslated region of the mitochondrial aconitase Mrna provides an additional mechanism for iron dysregulation in Parkinson's disease. The proposal will utilize human PD samples, animal models of PD (1-methyl-4-phenyl-l,2,3,6-tetrahydropyridine and 6-hydroxydopamine) and dopaminergic cell culture models in conjunction with a diversity of tools and techniques that include biochemical analyses, confocal microscopy, molecular biology and transgenic/knockout/aging mice.
Specific Aim 1 will determine whether mitochondrial aconitase is inactivated in human and experimental Parkinson's disease. The influence of aging and chronic mitochondrial oxidative stress will be determined using mice deficient in MnSOD, a critical mitochondrial antioxidant.
Specific Aim 2 will determine whether mitochondrial aconitase inactivation contributes to impaired iron homeostasis.
Specific Aim 3 will determine whether scavenging mitochondrial superoxide using native or synthetic antioxidants (e.g. MnSOD transgenic mice or metalloporphyrins) protect against mitochondrial aconitase inactivation in a manner that correlates with decreased iron overload and neuronal death in experimental Parkinson's disease.
Specific Aim 4 will determine the downstream consequences of mitochondrial aconitase inactivation in experimental Parkinson's disease. Specifically, regulation of brain mitochondrial aconitase synthesis by the 5' IRE in its mRNA, impact on the TCA cycle capacity and direct neurotoxicity of aconitase gene silencing will be examined. These studies can advance our understanding of the oxidative mechanisms of neuronal death in Parkinson's disease and suggest novel therapeutic strategies for rescuing neurons from age-related neurodegeneration. Additionally, this line of investigation may explain Parkinson's disease arising from genetic factors uncovered by aging as well as environmental factors. ? ?

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Special Emphasis Panel (ZRG1-BDCN-3 (01))
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Refolo, Lorenzo
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University of Colorado Denver
Schools of Pharmacy
United States
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Liang, Li-Ping; Huang, Jie; Fulton, Ruth et al. (2017) Pre-clinical therapeutic development of a series of metalloporphyrins for Parkinson's disease. Toxicol Appl Pharmacol 326:34-42
McElroy, Pallavi B; Sri Hari, Ashwini; Day, Brian J et al. (2017) Post-translational Activation of Glutamate Cysteine Ligase with Dimercaprol: A NOVEL MECHANISM OF INHIBITING NEUROINFLAMMATION IN VITRO. J Biol Chem 292:5532-5545
Lopert, Pamela; Patel, Manisha (2016) Mitochondrial mechanisms of redox cycling agents implicated in Parkinson's disease. J Neural Transm (Vienna) 123:113-23
Shrotriya, Sangeeta; Deep, Gagan; Lopert, Pamela et al. (2015) Grape seed extract targets mitochondrial electron transport chain complex III and induces oxidative and metabolic stress leading to cytoprotective autophagy and apoptotic death in human head and neck cancer cells. Mol Carcinog 54:1734-47
Lopert, Pamela; Patel, Manisha (2014) Brain mitochondria from DJ-1 knockout mice show increased respiration-dependent hydrogen peroxide consumption. Redox Biol 2:667-72
Ryan, Kristen; Liang, Li-Ping; Rivard, Christopher et al. (2014) Temporal and spatial increase of reactive nitrogen species in the kainate model of temporal lobe epilepsy. Neurobiol Dis 64:8-15
Lopert, Pamela; Patel, Manisha (2014) Nicotinamide nucleotide transhydrogenase (Nnt) links the substrate requirement in brain mitochondria for hydrogen peroxide removal to the thioredoxin/peroxiredoxin (Trx/Prx) system. J Biol Chem 289:15611-20
Liang, Li-Ping; Kavanagh, Terrance J; Patel, Manisha (2013) Glutathione deficiency in Gclm null mice results in complex I inhibition and dopamine depletion following paraquat administration. Toxicol Sci 134:366-73
Lopert, Pamela; Day, Brian J; Patel, Manisha (2012) Thioredoxin reductase deficiency potentiates oxidative stress, mitochondrial dysfunction and cell death in dopaminergic cells. PLoS One 7:e50683
Cantu, David; Fulton, Ruth E; Drechsel, Derek A et al. (2011) Mitochondrial aconitase knockdown attenuates paraquat-induced dopaminergic cell death via decreased cellular metabolism and release of iron and H?O?. J Neurochem 118:79-92

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