Proteomic analysis of accumulated proteins in dopaminergic neurons using a pre-clinical model ofubiquitin-proteasome system dysfunction

Damaged or unnecessary proteins are normally removed from a cell after they are tagged by attachment of a small protein called ubiquitin. These ubiquitin-tagged proteins are then recognized by a large protein complex, the proteasome that degrades them. Failure of this protein degradation system in dopamine neurons is believed to contribute to the progression of Parkinson's disease (PD). As a result of this failure, proteins are believed to accumulate to toxic levels, causing these dopamine neurons to die. We are developing a genetic pre-clinical model to study the role of protein degradation in PD. We will introduce a modified ubiquitin gene into the mouse genome so it will be produced specifically in dopamine neurons. Instead of facilitating protein degradation, this modified ubiquitin is designed to interrupt degradation and lead to an accumulation of proteins as seen in PD. The modified ubiquitin will also contain a unique molecular handle that will enable us to isolate and identify potentially toxic proteins that accumulate. Our research should provide a pre-clinical model to study the cause of dopamine neuron degeneration in PD, and elucidate specific proteins that accumulate in PD â€" those proteins may serve as potential drug targets to prevent dopamine neuron loss in PD.