Impaired neuronal differentiation in an induced pluripotent neural stem cell model derived from a Parkinson’s disease patient with a SNCA gene triplication

OLIVEIRA LMA; FALOMIR LOCKHART LJ; BOTELHO MG; FRIERL A; MAK S; ARNDT-JOVIN DJ; SCHUELE B; JOVIN TM

Munich

Workshop; 100 Years of Lewy Bodies meeting: Where are we now?; 2012

Ludwing Maximilian University (Munich)

-Synuclein (aSyn), the main protein component of Lewy bodies, is thought to play a major role in neuropathology as missense mutations and extra copies of the SNCA gene result in autosomal-dominant Parkinson’s disease (PD). So far, research has been mainly focused on identifying mechanisms that lead to neurodegeneration. However, overexpression of aSyn was found to impair neurogenesis1 and neuronal differentiation2. This suggests that accumulation of aSyn may deregulate the balance between neuronal death and neuronal replacement, having a dual role in PD onset. We are studying neuroprogenitor cells (NSCs) derived from patient-derived induced pluripotent stem cells of individuals affected with PD with known genetic alterations and age-matched control lines3. These cells proliferate and maintain the capability to differentiate into the major cell types of the brain, including neurons, astrocytes, and oligodendrocytes. The effect of PD-predisposing genetic alterations on neurogenesis and neurodegeneration are being investigated using light microscopy and flow cytometry of fixed and live cells. We have observed differences during the differentiation process into dopaminergic neurons between a cell line derived from a PD patient with a triplication of the SNCA gene (1754) and a control line from a healthy control sibling (sister, 1761). As NSCs both lines have equivalent morphology and proliferative capacity but present mild differences regarding mitochondria function and basal oxidative stress. Induction of differentiation in a completely defined medium resulted in a lower yield of TH+ and Tuj+ cells in the 1754 line in comparison to the 1761 line. The impairment in the capacity of the 1754 line to differentiate appears to have a dual origin. On the one hand, selective cell death is enhanced in the 1754 cells that initiate differentiation as judged by the appearance of dying Tuj+ cells. On the other hand, under differentiation stimuli by BDNF and GDNF, a proportion of 1754 cells maintain nestin expression and their proliferative capacity. These data suggest that increased expression of aSyn due to a gene triplication event may impair neurogenesis, and thus result in a failure to replace dopaminergic neurons with a consequent predisposition for early onset PD.