Dopaminergic (DA) neurons represent a rather small but important population of cells in our brain. Their death leads to Parkinson's disease (POD), a neurodegenerative disorder characterized by rigidity, difficulty in initiating movements, and a resting tremor. Molecular genetic studies of families with autosomal dominant inheritance of PD have identified mutations in alpha-synuclein, a phospho-protein normally found in all presynaptic neurons, to be responsible for the disease phenotype. Alpha- nuclein is also the main component of Lewy bodies, the pathological hallmark of PK. Whereas the fruit flies that over-express alpha-synuclein represent a good invertebrate model for PD, efforts to create such models in mammals only had limited success. In this exploratory grant, we propose to develop a vertebrate model of PD by over-expressing alpha- synuclein in the zebrafish, Danio rerio. The feasibility of generating transgenic fish expressing exogenous proteins in neurons and the small size and transparent nature of juvenile zebrafish (the fry) provides us with an excellent opportunity to determine the cellular mechanisms underlying (the fry) provides us with an excellent opportunity to determine the cellular mechanisms underlying alpha-synuclein aggregate formation and DA neuron degeneration. Furthermore, the facile genetic analysis that can be carried out with zebrafish will allow us to subsequently identify genes and pathways that are involved. The ability of zebrafish to produce a large number of offspring also permits large- scale in vivo screens for pharmaceutical compounds that can halt DA neuron degeneration. In this proposal, we would like to create double transgenic fish that express alpha-synuclein-GFP (green fluorescent protein) fusion protein in all the neurons and Tau-RFP (red fluorescent protein) in DA and noradrenergic (NA) neurons and use this model to achieve the following specific aims: 1. Determine the location of alpha-synuclein aggregates and the time course of their formation in living transgenic fish. We would like to test whether the formation of alpha-synuclein aggregates is genetically controlled and therefore occurs in a consistent pattern of whether their formation occurs in a stochastic fashion, which would suggest epigenetic control. 2. Compare the kinetics of DA neuronal degeneration to that of alpha- synuclein aggregate formation and determine if modulation of the level of neuronal oxidative stress will affect the time course of alpha- synuclein aggregation and DA neuron degeneration. 3. Determine the behavioral consequence of over-expressing alpha- synuclein in zebrafish.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Exploratory/Developmental Grants (R21)
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Special Emphasis Panel (ZNS1-SRB-K (03))
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Murphy, Diane
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University of California San Francisco
Schools of Pharmacy
San Francisco
United States
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Bretaud, Sandrine; Lee, Susie; Guo, Su (2004) Sensitivity of zebrafish to environmental toxins implicated in Parkinson's disease. Neurotoxicol Teratol 26:857-64