To understand and ultimately treat neurodegenerative diseases characterised by protein aggregates, one must understand how these aggregates accumulate, how they become toxic to brain cells and the mechanisms which allow them to spread. There are two projects available within the McMahon group to pursue these goals.
The first project will build on our previous discovery of a mechanism for aggregate uptake into cells, which we call Aggregation-Dependent Endocytosis. In pilot experiments, we have used this approach to visualise the uptake of size-defined α-synuclein aggregates. We have also developed an assay for the quantification of protein aggregates in cells. We would like to use these assays to investigate the receptors responsible for aggregate binding, the relationship between aggregate size and endocytosis, the mechanisms underlying aggregate uptake, and ways in which this process might be prevented. The project will apply quantitative approaches both in cells and in vitro. There will also be opportunities to extend the work from cell lines to neurons and to examine the effects of disease-relevant mutations on aggregate uptake mechanisms and pathways.
The second project focusses on a potential mechanism of toxicity whereby ordered protein assemblies interact with different cellular partners from those of the corresponding monomeric proteins. We have developed methods to investigate assemblies of target proteins, including α-synuclein and β-amyloid, both in vitro and in cells. Using mass spectrometry, we will identify their major interaction partners and investigate whether sequestration or altered regulation of these partners contributes to cellular toxicity. We have also established a live-cell assay of protein aggregation in which illumination triggers rapid aggregation of a target protein, followed by the recruitment of cellular factors. We would like to combine this approach with biochemical methods to isolate relevant membrane compartments and identify associated interaction partners.
Both projects will give experience in a range of biochemical techniques, experiments using cultured cell lines and neurons and structural studies of protein aggregates and their interaction partners.