a-synuclein (a-syn) mutations or gene amplification cause a small subset of Parkinson's disease (PD), with Lewy body (LB) formation, neurodegeneration and often an associated dementia. a-syn aggregation in LB is also widespread in sporadic PD and other LB diseases without apparent upregulation of transcription. a-syn overexpression leads to its aggregation and/or neurotoxicity in various animal models. Reduction of a-syn is neuroprotective in animal models. These observations suggest a therapeutic potential of reducing a-syn in treatment of PD and other LB diseases. Our long-term objective is to determine the mechanisms and regulation of a-synucleinopathy in neurodegenerative diseases, and to provide novel and effective treatment strategies. We focused on the lysosomal function in modulating neuronal a-syn aggregation and toxicity, because lysosomes are high capacity organelles responsible for clearance of damaged and aggregated proteins, and are implicated in aging and several neurodegenerative diseases. We found that mice with deficient lysosomal cathepsin D (CD) exhibited significant a-syn accumulation in the brains, indicating a critical role for CD in mediating a-syn metabolism. In vitro we have shown that overexpression of CD reduces a-syn aggregation and protects against a-syn-mediated toxicity. To further establish CD as a therapeutic target against a-synucleinopathy, we will examine its effects in vivo, and define the mechanisms of its action in vitro. We hypothesize that CD protects against a-syn neurotoxicity by increasing autophagic clearance of toxic species of a-syn. We will test this hypothesis by performing experiments with the following aims: 1. Test the hypothesis that CD haploinsufficiency increases sensitivity to a-syn-induced neurotoxicity in vivo. 2. Test the hypothesis that stereotaxic delivery of AAV-CD to the SN attenuates a-syn-mediated neurotoxicity in vivo. 3. Test the hypothesis that neuroprotection by CD is through clearance of a-syn by autophagy. Completion of these studies will determine the effect of partial loss-of-CD in a-syn-induced DA neuron death, and the effect of gain-of-function of CD in neuroprotection in vivo. Furthermore, insights into the potential molecular mechanisms of CD-mediated neuroprotection and the molecular mechanisms and regulation of clearance of aggregation-prone proteins, will be gained that will permit further refinement of CD therapeutic strategies.

Public Health Relevance

a-synuclein mutations or gene amplification cause a small ubset of Parkinson's diseases, and aggregates in other neurodegenerative diseases with a-synucleinopathy and sometimes an associated dementia even in an absence of gene mutation. Our work will determine the function of the autophagy-lysosomal pathway in reducing a-syn level and toxicity, a strategy relevant to improving treatment of PD and other a-synucleinopathies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS064090-03
Application #
8244500
Study Section
Cell Death in Neurodegeneration Study Section (CDIN)
Program Officer
Sutherland, Margaret L
Project Start
2010-04-15
Project End
2015-03-31
Budget Start
2012-04-01
Budget End
2013-03-31
Support Year
3
Fiscal Year
2012
Total Cost
$314,059
Indirect Cost
$99,684
Name
University of Alabama Birmingham
Department
Pathology
Type
Schools of Medicine
DUNS #
063690705
City
Birmingham
State
AL
Country
United States
Zip Code
35294
Crabtree, Donna; Dodson, Matthew; Ouyang, Xiaosen et al. (2014) Over-expression of an inactive mutant cathepsin D increases endogenous alpha-synuclein and cathepsin B activity in SH-SY5Y cells. J Neurochem 128:950-61
Redmann, Matthew; Dodson, Matthew; Boyer-Guittaut, Michaël et al. (2014) Mitophagy mechanisms and role in human diseases. Int J Biochem Cell Biol 53:127-33
Boyer-Guittaut, Michaël; Poillet, Laura; Liang, Qiuli et al. (2014) The role of GABARAPL1/GEC1 in autophagic flux and mitochondrial quality control in MDA-MB-436 breast cancer cells. Autophagy 10:986-1003
Levonen, Anna-Liisa; Hill, Bradford G; Kansanen, Emilia et al. (2014) Redox regulation of antioxidants, autophagy, and the response to stress: implications for electrophile therapeutics. Free Radic Biol Med 71:196-207
Chacko, Balu K; Kramer, Philip A; Ravi, Saranya et al. (2014) The Bioenergetic Health Index: a new concept in mitochondrial translational research. Clin Sci (Lond) 127:367-73
Liang, Qiuli; Benavides, Gloria A; Vassilopoulos, Athanassios et al. (2013) Bioenergetic and autophagic control by Sirt3 in response to nutrient deprivation in mouse embryonic fibroblasts. Biochem J 454:249-57
Le Grand, Jaclyn Nicole; Bon, Karine; Fraichard, Annick et al. (2013) Specific distribution of the autophagic protein GABARAPL1/GEC1 in the developing and adult mouse brain and identification of neuronal populations expressing GABARAPL1/GEC1. PLoS One 8:e63133
Zhang, Jianhua (2013) Autophagy and Mitophagy in Cellular Damage Control. Redox Biol 1:19-23
Parekh, Vrajesh V; Wu, Lan; Boyd, Kelli L et al. (2013) Impaired autophagy, defective T cell homeostasis, and a wasting syndrome in mice with a T cell-specific deletion of Vps34. J Immunol 190:5086-101
Benavides, Gloria A; Liang, Qiuli; Dodson, Matthew et al. (2013) Inhibition of autophagy and glycolysis by nitric oxide during hypoxia-reoxygenation impairs cellular bioenergetics and promotes cell death in primary neurons. Free Radic Biol Med 65:1215-28

Showing the most recent 10 out of 19 publications