Identifying therapeutic targets and causes of dopaminergic neuronal degeneration using C. elegans high-throughput genetic approaches

Understanding the molecular mechanisms responsible for neurodegenerative diseases, like Parkinson?s disease, is still an area of active investigation. Currently, no disease modifying interventions are available but only symptomatic treatments. The use of small animals to study neurodegenerative disease, facilitates fast discovery and allows genetic manipulations that would be difficult in mammalian models. This work used C. elegans to study dopamine producing neurons, which are mostly affected in Parkinson?s disease. C. elegans is a small, transparent nematode, suitable for high-throughput approaches, with a simple nervous system that is highly conserved at the level of gene expression and pathology with humans. This study also utilized a mutation in a gene that codes for a Transient Receptor Potential (TRP) channel. In animals that carry this mutation, dopamine producing neurons progressively degenerate with age. Our goal was to discover neuroprotective mutations using the TRP channel model of neurodegeneration. During the final year of the project, our screens led to the identification of several genes involved in channel function and trafficking. We found that when these genes are mutated, they prevent neuronal damage and thus lead to increased survival of nerve cells. These findings are of special importance of the field of neurodegeneration but also for understanding the function of TRP channels in general, which are important for regulating sensory functions in humans. Finally, our team came across important and unexpected discoveries on how environment and specifically the type of bacteria that inhabit the gastrointestinal tract affect neurodegeneration. This new exciting area of research will add new insights in the field of gut-brain interactions and has the potential to have immediate impact for prognosis and therapy.

Parkinson's Disease, characterized by the progressive degeneration of dopaminergic neurons, afflicts millions of people. Yet, no effective therapeutic strategies are available. This work uses Caenorhabditis elegans to study dopaminergic degeneration. C. e legans is a small nematode, highly amenable to genetics and high-throughput approaches, with a simple nervous system that is highly conserved at the level of gene expression and pathology with humans. This study also utilizes a mutant in a Transient Recep tor Potential (TRP) channel, trp-4(d), in which dopaminergic neurons properly develop but later on progressively degenerate. OBJECTIVES: 1. Understand the molecular mechanisms of dopaminergic neurodegeneration 2. Identify potential therapeutic targets 3. Uncover novel causes of neuronal cell death STRATEGIES: 1. We will use a candidate approach to investigate which of the known cell death pathways (apoptosis, autophagy, necrosis) mediate trp-4(d) dopaminergic degeneration. 2. We will use an unbiased 'for ward genetic screening' approach, i.e. use trp-4(d) mutants and target the genomes with mutagens to identify genes that when mutated, stop dopaminergic cell death. High-throughput genetic technology (automated screening and Whole Genome Sequencing) will b e employed for rapid mutant isolation and identification. Characterization of the retrieved genes will elucidate molecular mechanisms that block dopaminergic degeneration. 3. We will use similar high-throughput genetic screening approaches to find more ge nes like trp-4(d), that when mutated have detrimental effect to the survival of DA neurons either in isolation or in the presence of known Parkinsonism genes. IMPACT The expected outcomes are of high medical significance and relevance to human neurodegene rative conditions. The proposed work, employing state of the art methodology, will not only enhance Norwegian competitiveness in disease related research but also contribute to Norwegian technological exc