Our long term goal is to study the mechanism of neurodegeneration induced by environmental neurotoxicants. This proposal is submitted to investigate gene-environment interactions in the pathogenesis of Parkinson's disease mediated through the mitochondrial pathway. Mitochondrial dysfunction has been proposed as a major mechanism of neurodegeneration in PD for years, but direct evidence in humans was inadequate until the recent discoveries of mutations in PTEN-induced putative kinase 1 (PINK1), which encodes a mitochondrial kinase. Although PINK1 mutations are associated with autosomal recessive PD, interestingly, an increasing number of PD patients carrying single heterozygous mutations have been reported. These observations suggest that a heterozygous PINK1 mutation may act as a susceptibility factor that interplays with environmental insults. To determine the interactions between PINK1 mutations and environmental toxicants, we have created stable cell lines with inducible over-expression of various PINK1 mutants. Based on our preliminary results, we hypothesize that PINK1 mutations increase cell susceptibility to environmental toxicants such as paraquat (PQ) through a novel mechanism: mitochondrial fragmentation via the mitochondrial fission / fusion machinery. In the first specific aim, we will characterize neurotoxicity induced by PQ and MPP+ (two toxicants representing different mechanisms of toxicity) through the mitochondrial fission and fusion pathway in N27 cells with a PINK1 mutation (L347P) and empty vector control, as well as in N27 cells with PINK1 knockdown mediated by siRNA. We will assess cell viability, functional outcomes (ATP production, dopamine release and electron transport chain activity), as well as mitochondrial fragmentation (size/shape) and alterations in mitochondrial fission and fusion proteins.
In specific aim 2, we will perform neuroprotective experiments against PQ and MPP+ toxicity in mutant PINK1 cells by targeting the mitochondrial fission and fusion pathway, through genetic manipulations and a small molecule. We will transfect cells with relevant constructs and use a chemical inhibitor to attenuate mitochondrial fragmentation. The neuroprotective effects of these two strategies against MPP+ and PQ toxicity will be determined using cell viability and functional assays as described in specific aim 1.
This research may provide insights into the complexity of gene-environment interactions in the cause of cell death as seen in Parkinson's disease by unraveling a still unrecognized molecular pathway. Furthermore, this novel mechanism may offer an additional avenue to develop neuroprotective therapy for patients with Parkinson's disease.
| Rappold, Phillip M; Cui, Mei; Grima, Jonathan C et al. (2014) Drp1 inhibition attenuates neurotoxicity and dopamine release deficits in vivo. Nat Commun 5:5244 |
| Tieu, Kim; Xia, Xu-Gang (2014) Cytosolic PINK1 escapes from mitochondria to promote dendritic outgrowth. J Neurochem 128:787-9 |
| Rappold, Phillip M; Cui, Mei; Chesser, Adrianne S et al. (2011) Paraquat neurotoxicity is mediated by the dopamine transporter and organic cation transporter-3. Proc Natl Acad Sci U S A 108:20766-71 |
| Tieu, Kim (2011) A guide to neurotoxic animal models of Parkinson's disease. Cold Spring Harb Perspect Med 1:a009316 |
| Lim, Soyeon; Chesser, Adrianne S; Grima, Jonathan C et al. (2011) D-?-hydroxybutyrate is protective in mouse models of Huntington's disease. PLoS One 6:e24620 |
| Goldman, Nanna; Chen, Michael; Fujita, Takumi et al. (2010) Adenosine A1 receptors mediate local anti-nociceptive effects of acupuncture. Nat Neurosci 13:883-8 |
| Rappold, Phillip M; Tieu, Kim (2010) Astrocytes and therapeutics for Parkinson's disease. Neurotherapeutics 7:413-23 |
| Vives-Bauza, Cristofol; Zhou, Chun; Huang, Yong et al. (2010) PINK1-dependent recruitment of Parkin to mitochondria in mitophagy. Proc Natl Acad Sci U S A 107:378-83 |
| Cui, Mei; Tang, Xiangna; Christian, Whitney V et al. (2010) Perturbations in mitochondrial dynamics induced by human mutant PINK1 can be rescued by the mitochondrial division inhibitor mdivi-1. J Biol Chem 285:11740-52 |
| Fang, Fang; Christian, Whitney V; Gorman, Sadie G et al. (2010) Neurosteroid transport by the organic solute transporter OSTýý-OSTýý. J Neurochem 115:220-33 |
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