Parkinson's disease (PD) is the most common neurodegenerative movement disorder. Our understanding of the disease has been enhanced by the discovery of gene mutations in rare families with eariy-onset autosomal recessive juvenile parkinsonism (ARJP). The first gene to be identified was parkin and two further genes have been identified namely, DJ-1 and PINK1. The latter was discovered in our laboratory. The work of this thesis has aimed to increase our understanding of how these newly discovered genes play a role in neuronal survival and how disease-causing mutations result in neurodegenerarJon. Utilising gene transfer techniques and transient and stable cell culture expression systems, the function of parkin and PINK1 was investigated in human dopaminergic SH-SY5Y neuroblastoma cell lines. The work of this thesis has confirmed and extended previous reports that parkin over-expression confers neuroprotection against a variety of cellular stresses implicated in PD. Moreover, this work has showed for the first time that endogenous parkin protein can localize to aggregates known as "aggresomes' following stress and that the formation of these parkin positive aggresomes can be dissociated from parkin's effect on neuronal survival. Furthermore, this work describes the first functional characterization of PINK1. It demonstrates that PINK1 localizes to the mitochondria in neuronal cells where it may play a neuroprotective role against cellular stress. Moreover, this effect is abrogated by disease causing mutations in PINK1. This work also reports on the characterisation of novel PINK1 antibodies and shows for the first time that PINK1 can localize to aggresomes and the mechanism is linked to mitochondrial recruitment. The work of this thesis sheds light on the increasing importance of the ubiquitin proteasome system and mitochondria in the pathogenesis of PD. Improved understanding of these cellular processes should lead to more effective treatments for this devastating disease
