Functional Analysis of Neuroprotective Genes Using Caenorhabditis Elegans and Mammalian Models of Parkinson's Disease

Download or read book Functional Analysis of Neuroprotective Genes Using Caenorhabditis Elegans and Mammalian Models of Parkinson's Disease written by Adam John Harrington and published by . This book was released on 2011 with total page 187 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dysfunction of the protein degradation machinery has emerged as a leading cellular defect associated with age-onset proteotoxicity in neurodegenerative diseases, including Parkinson's disease (PD). While the etiology of PD is not fully understood, the protein alpha-synuclein (alpha-syn) is thought to play a central role in the pathology associated with this disease, in that accumulation of alpha-syn is observed in both familial and sporadic forms of PD and mutations or overexpression of alpha-syn result in enhanced dopaminergic (DA) neurodegeneration. Without an effective therapeutic treatment for the progression of PD, we set out to identify and validate potential genetic and chemical modifiers of key pathological features of PD, including alpha-syn accumulation and DA neurodegeneration using Caenorhabditis elegans in vivo; studies and mammalian cell culture in vitro; assays. Using these approaches, we validated the lysosomal trafficking protein, VPS41, as a potential neuroprotective candidate, in that overexpression of VPS41 suppressed both alpha-syn and chemical neurotoxicity in C. elegans; and mammalian cell culture, as well as suppressed alpha-syn accumulation in mammalian cells. Through a structure/function analysis, we identified the minimal domains required for the protective function of human VPS41. Using worms engineered to enable DA-neuron specific RNAi, we showed that post-Golgi trafficking of AP-3 vesicles to the lysosome affected alpha-syn-induced neurodegeneration, indicating that VPS41 may be mechanistically eliciting protection via Golgi to lysosome trafficking. Furthermore, we functionally analyzed two VPS41 single nucleotide polymorphisms (SNPs) that naturally occur in human populations and found that both SNPs prevent VPS41 from suppressing alpha-syn accumulation and neurotoxicity in mammalian cells and C. elegans, respectively. These SNP data may represent additional genetic susceptibility factors for PD onset or progression. Additionally, using our C. elegans model of alpha-syn-induced DA neurodegeneration, we analyzed other genetic and chemicals for potential neuroprotective capacity. In this regard, the protein 14-3-3 Theta and the small molecule bafilomycin, originally identified in mammalian experiments, were functionally validated in C. elegans. Taken together, these studies support the predictive nature of C. elegans in validating potential modifiers of alpha-syn neurotoxicity, and highlight the importance of lysosomal function in maintaining alpha;-syn homeostasis and its implications for suppressing the pathology associated with PD.