Promising Outcomes of Original Grant:
The formation of large alpha-synuclein protein inclusions in the brain is the pathological hallmark of Parkinson’s disease but whether those inclusions are the actual culprits remains unknown. We have now reasons to believe that smaller forms of asyn with altered structure, known as oligomers, may be more toxic for cells. In our original project we set out to establish a system in which to visualize these smaller forms, which had not been observed in living cells. We performed a pilot RNAi screen and identified genes which interfere with the formation of those forms of asyn, either promoting or inhibiting their formation.
Objectives for Supplemental Investigation:
The major goal for this supplemental investigation is to complete the RNAi screen with the full library of knock down constructs in order to identify additional genes which influence the formation of asyn oligomers. Using the system we established in the initial funding period, we will now extend the pilot study to cover the whole set of genes available in the library. We expect to identify both genes which promote or prevent the formation of oligomeric species. Once the screen is concluded, we will erform follow up experiments to validate the results and to confirm the effects of the most promising genes. Importantly, we will investigate whether modifiers of asyn oligomerization also affect the formation of large asyn inclusions (similar to Lewy bodies), to understand the origin of cellular toxicity, which remains a central question in PD research.
Importance of This Research for the Development of a New PD Therapy:
Previous intervention strategies have used asyn aggregation as a therapeutic target, but the question still remains of whether those are the toxic culprits. This research will enable us to use pre-aggregated forms of asyn as targets, and to identify genes which modify their formation. Once these genes are identified, we will be able to develop small molecules capable of modifying the levels of those genes, in the hope that this strategy may provide the underpinnings for novel PD therapies.
This second period of funding enabled us to proceed with the RNAi screen and to identify additional modifiers of alpha-synuclein oligomerization. Interestingly, in the different categories of genes identified, we found both genes which promote and reduce the formation of alpha-synuclein oligomers, suggesting it might be possible to interfere with the process in different ways. We also discovered that some of the modifiers altered the intracellular distribution pattern of alpha-synuclein, and we are now exploring these effects in more detail in follow-up studies. Ultimately, we expect to be able to design small molecules that are capable of inducing similar effects, to be tested in vivo in pre-clinical models of PD.