Parkinson's disease; molecular mechanisms and anti-aggregation therapies.
University of Oxford
Alpha-synuclein is a major component of Lewy bodies and drives dopaminergic neuronal loss in the Substantia Nigra Pars Compacta (SNPc) of Parkinson's patients. While much research has focused on the mechanisms behind aggregation, our understanding of the molecular mechanisms by which the disease progresses is still poor and disease modifying therapies are lacking. Therefore, our research focuses on highlighting novel molecular mechanisms leading to neurodegeneration in Parkinson's, and therapeutic avenues that tackle drivers of the disease.
We firstly investigated the biochemical changes underpinning α-synuclein-induced neurodegeneration in mice overexpressing α-synuclein (SNCA-OVX). Biochemical and proteomic analysis of SNCA-OVX midbrain revealed mitochondrial dysfunction, which was found to be age and region dependent and downstream of the transcription factor REST. We determined that vulnerable SNPc dopaminergic neurons display low REST levels correlated with disrupted mitochondrial morphology and a-synuclein aggregation, which is enhanced in SNCA-OVX mice, compared neighbouring neurons and those of wild-type mice. Furthermore, REST knockdown impaired mitochondrial morphology and mitophagy. Conversely, REST overexpression attenuated mitochondrial toxicity and mitochondrial morphology disruption through PGC1a. In conclusion, we found that increased levels of α-synuclein cause dopaminergic neuronal-specific dysfunction through mitochondrial toxicity, which is attenuated by REST through PGC1a, highlighting a protective role for REST in PD.
In order to tackle disease-driving molecular mechanisms, we have studied the use of molecular tweezers as anti-aggregation therapeutic agents for Parkinson's. Molecular tweezers have shown high potential as anti-aggregation agents targeting positively charged residues of proteins undergoing amyloidogenic processes. We therefore investigated whether the molecular tweezer CLR01 could ameliorate phenotypes in vitro and in vivo in human and mouse models of PD. In vitro, CLR01 decreased alpha-synuclein aggregation in induced pluripotent stem cell-derived dopaminergic cultures. We insulted dopaminergic neuronal cultures with alpha-synuclein aggregates purified from post-mortem PD brain protein extracts pre-treated with PBS or CLR01. CLR01 pre-treatment resulted in a reduction of alpha-synuclein aggregates and toxicity. We then tested CLR01 in vivo in a humanized alpha-synuclein overexpressing mouse model; mice treated for two months at 12 months of age, when motor defects are mild, exhibited an improvement in motor defects and a decreased oligomeric alpha-synuclein burden. At 18 months of age, when dopaminergic neurons have already been lost in this model, CLR01 treatment still reduced alpha-synuclein oligomeric burden. Finally, CLR01 was able to reduce alpha-synuclein-associated pathology in mice injected with either mouse or human alpha-synuclein aggregates into the striatum or substantia nigra. Altogether, these results highlight that CLR01 represents a disease-modifying therapy for PD and support development of molecular tweezers in human clinical trials.
In summary, our studies show that REST could be an important neuroprotective factor for Parkinson's, and that molecular tweezers, and more specifically CLR01, could be interesting therapeutic agents for the treatment of Parkinson's.
Host: Fabio Cavaliere