α-Synuclein pathology and mitochondrial dysfunction: Studies in cell models for Parkinson’s disease

The development of Parkinson’s disease (PD) is linked to mitochondrial dysfunction in dopaminergic (DA) neurons of the ventral midbrain. Etiology of the disease remains poorly understood and the link between mitochondrial dysfunction and the disease causing protein α-synuclein remains elusive. Using an SH-SY5Y overexpression model, we show α-synuclein A53T significantly inhibits mitochondrial trafficking and leads to an increase reactive oxygen species production. Treatment with davunetide, a microtubule stabilizing peptide, rescues this phenotype. To confirm these results in human induced pluripotent stem cell derived neurons we first introduce a purification system based on the metabolic profile of neuronal cells. Using glucose deprivation and lactate supplementation we efficiently enrich for neuronal populations. Using a long-term (90 days) culture approach, we subsequently analysed mitochondrial trafficking in cultured dopaminergic neurons. We demonstrated that mitochondrial trafficking is impaired in PD neurons when compared to control neurons, and that mitochondria are frequently fragmented in patient-derived DA neurons. These results support the findings in the SH-SY5Y overexpression model and suggest that mitochondrial fragmentation and impaired trafficking are early events that contribute to mitochondrial dysfunction in PD. A major hurdle in the implementation of pluripotent stem cells is the rejuvenated phenotype of differentiated cells. To overcome this hurdle we introduce an in-vitro model to accelerate ageing of iPSC-derived somatic cells using transgenic expression of progerin. Differentiated cells that express progerin displayed several hallmarks of ageing, including nuclear folding, chromosomal instability and mitochondrial dysfunction. This technique presents the stem cell community with additional tools to study ageing differentiated cells.