The most common hereditary form of Parkinson’s Disease (PD) results from mutations of the LRRK2 gene in humans. The model genetic organism, Drosophila melanogaster (fruit fly), possess a very similar gene called dLRRK.Given the evolutionary conservation of the human and fly LRRK genes, we propose to utilize the power and pace of Drosophila genetics to introduce human disease-causing mutations into the fly counterpart and generate the most accurate fly LRRK-based PD model possible.
Our approach relies on the fact that certain genes and processes are highly conserved between flies and humans. We determined that the human LRRK2 gene mutations that cause PD reside in positions within the protein that are highly conserved in the fly LRRK gene. Therefore, we will engineer the same disease-causing mutations into the fly genome using the powerful technique of homologous recombination (HR). Drosophila HR allows the experimenter to make surgical changes to the fly genome - specifically designed mutations - without perturbing other aspects of gene function. Thus, we can mimic the case of single point mutations found in human patients with inherited disease. We will then determine whether such mutations confer behavioral disease-like phenotypes and whether the disease model develops brain/neuronal pathologies.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
Neurons in both flies and humans have very similar jobs- sending and receiving electrical and chemical signals within the complex structure of the brain. Given the shared ancestry of genes and processes, we hope to first show that human LRRK2 mutations cause a PD-like disease in flies. Having established this, we can then proceed to find mutations in other genes that suppress the deleterious effects of such mutations. In effect, we will be able to harness the power of Drosophila forward-genetics to identify genetic "cures". These new suppressor genes may identify novel proteins or pathways that serve as targets for therapeutic intervention in human PD.
We are confident, given our extensive experience with Drosophila HR, that we can generate several mutated alleles of dLRRK within the timeframe of this RRIA. If evolutionary conservation is any indicator, we expect that the introduced PD-causing mutations should perturb some aspect of neuronal physiology in the fly. In effect, we will be generating a rapid and cost-effective research tool in the search for the mechanisms and treatment of PD.