gms | German Medical Science

Parkinson's disease (PD) is the most common movement disorder and second most common neurodegenerative disorder caused by loss of dopaminergic neurons in the substantia nigra. The major neuropathological hallmark is the excessive intracellular accumulation of the presynaptic protein alpha-synuclein (aSyn) in Lewy bodies and neurites. In order to investigate the toxic effect of aSyn oligomers and aggregates on dopaminergic neurons we established an inducible cell culture model stably expressing aSyn in Lund human mesencephalic (LUHMES) cells. LUHMES cells are conditionally immortalized and can be differentiated to post-mitotic neurons acquiring a dopaminergic phenotype. We transduced LUHMES cells with lentiviral constructs encoding non-aggregating wildtype aSyn (WT-aSyn) and aggregating C-terminally tagged aSyn (SynT). Aggregation and toxicity of both variants were characterized using biochemical and immunocytochemical methods. Single cells showing transgene expression have been selected for clonal amplification and further examined regarding their proliferation and dopaminergic differentiation potential. Whereas under proliferative conditions transduced LUHMES cells do not express aSyn, 12 to 21 hours after induction of differentiation aSyn expression could be observed resulting in decreased survival compared to non-transgenic control cells after nine days. These differentiating LUHMES cells express tyrosine hydroxylase (TH), dopamine transporter (DAT) and vesicular monoamine transporter 2 (VMAT2). aSyn overexpression reduced TH expression levels. To determine the effect of aSyn expression on the cellular protein metabolism we also analyzed the expression markers for the autophagy-lysosomal pathway and the ubiquitin-proteasome system. Further studies will focus on detailed analysis of aggregation and its impact on neuronal survival. Taken together, these cells stably expressing aSyn can be used as a model to study the toxic effect of aSyn on dopaminergic neurons thereby providing new insights in the disease mechanisms of PD.