We have identified a small molecule, designated J3, which shows promising neuroprotection in an acute animal model of Parkinson’s disease. To reach our ultimate goal of developing a disease-modifying drug for PD, we need to generate analogs with better potency and selectivity than J3. To facilitate this effort, we propose to identify the cellular processes and components that are altered by J3 and use this information to implement more sensitive and selective assays for compound potency and selectivity, thereby accelerating the optimization of the J-compound series.
J3 was originally identified in a cellular PD model in which yeast expressed alpha-synuclein, a protein implicated in the neurotoxicty associated with PD. Because J3 is active in yeast, we were able to use unbiased genomic screening methods available only for yeast to characterize the effects of J3 on cells and obtained data suggesting that J3 affects the assembly and/or function of the plasma membrane and actin cytoskeleton. In our proposed research, we will test this hypothesis in yeast cells using a combination of well-established assays to monitor whether treatment with J3 affects specific cellular pathways. In addition, we will perform another type of genomic screen to obtain a second unbiased data set.
Relevance to Diagnosis/Treatment of Parkinson’s Disease:
The J series is neuroprotective in a new animal model in which the overexpression of alpha-synuclein--a protein that is a causative factor in PD--kills dopamine-producing neurons in the substantia nigra, the area of the brain that is destroyed by PD. To the best of our knowledge, J3 is the only compound reported to date that has protective activity in this new PD animal model. Knowing how J3 achieves its effect will facilitate development of more potent analogs, accelerating the selection of a drug candidate. In addition, this work will identify cellular pathways and/or proteins that can be modulated to protect cells from the toxicity of alpha-synuclein, providing new targets for neuroprotective agents for PD.
We expect to confirm or refute our current hypothesis that J3 affects the assembly of the plasma membrane and/or action cytoskeleton. If we refute our current hypothesis, we expect that data from the proposed studies will generate a modified, alternative hypothesis for the mode of action of J3.
We identified two targets of the J series. A subset of J compounds inhibit the TOR pathway; this is unlikely to be the mechanism of alpha-synuclein rescue but may explain the cytoxicity observed in some compounds. J compounds potently inhibit CK1 epsilon with some activity against delta. Additional studies are required to determine if this is the mechanism of alpha-synuclein rescue.