Objective: To develop a novel transgenic C. elegans model to study dopaminergic neurodegeneration mediated by alpha-synuclein.

Background: Targeting alpha-synuclein could be a disease-modifying strategy for Parkinson’s disease but few drugs have been identified that reduce alpha-synuclein toxicity. One approach not yet optimally utilized to find candidate drugs is using invertebrate animal models in small molecule screens. C. elegans models of alpha-synuclein-mediated dopaminergic neurodegeneration have been previously developed. However the utility of these earlier models is limited because they only capture advanced morphological features of neurodegeneration (e.g., neurite or cell body loss) thus modelling a late stage of disease.

Methods: We generated C. elegans expressing lower or higher levels of human wild-type, A53T, or A30P alpha-synuclein under the control of the dat-1 promoter. Genotypes were determined by DNA sequencing of the products from single-worm PCR. Protein expression of alpha-synuclein was assessed by immunohistochemistry of fixed animals and by immunoprecipitation from worm lysates. Lifespan assays were performed. We used high-resolution multi-worm tracking and custom imaging processing to characterize the motor phenotype.

Results: Human alpha-synuclein immunoreactivity was present exclusively within dopaminergic neurons of the transgenic C. elegans. Monomers as well as oligomers of alpha-synuclein were detected by immunoblot. Lifespan of the alpha-synuclein transgenic C. elegans was not significantly different from control animals. Motor phenotype was characterized at a time point prior to neurite or cell body loss by extracting 99 features of the animal’s motor behaviour. The severity of the motor phenotype was greater in the higher alpha-synuclein expressing animals compared to the lower alpha-synuclein expressors. Treatment of the animals with dopamine reversed the abnormal motor behaviour.

Conclusions: These data demonstrate that our C. elegans model has a scorable motor phenotype that correlates with alpha-synuclein expression and is reversible with dopamine treatment. The motor phenotype occurs in advance of severe dopaminergic neurodegeneration. Thus this novel C. elegans system models an earlier stage of disease and is expected to fill an unmet need for an invertebrate animal model in primary and secondary screens for disease-modifying drugs for Parkinson’s disease.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/a-novel-c-elegans-model-for-identification-of-small-molecules-that-target-alpha-synuclein-mediated-toxicity/