An iPSC Model of Early Onset Parkinson's Disease

Early onset Parkinson’s Disease (onset <50 years) accounts for between 10-20 percent of all patients. While some of these cases are associated with specific mutations, the majority are sporadic where the cause is unknown. We generated induced pluripotent stem cells from sporadic early onset patients and differentiated them to dopamine neurons. At early stages in culture (30 days) we found significant elevations in soluble α-synuclein protein levels when compared to controls. This was associated with reductions in lysosomal membrane proteins such as LAMP1 and an increase in phosphorylated protein kinase C-α (p-PKCα). Testing activators of lysosomal function showed that specific phorbal esters reduced both α-synuclein and p-PKCα levels and increased LAMP1 expression. Interestingly, very low doses of the drug PEP005 were able to reduce α-synuclein levels without affecting p-PKCα. Similar effects of PEP005 on α-synuclein expression were seen following infusion into the mouse brain. Our data show that early onset sporadic Parkinson’s Disease can be accurately predicted using a ratio of α-synuclein and p-PKCα in dopamine neural cultures derived from patient iPSC’s and that specific phorbal esters can alter both biomarkers making these drugs promising candidates to treat Parkinson’s Disease.