Characterisation of Oxidative Stress, DNA Damage and Inflammation in a Cellular Model of Parkinson’s Disease

Abstract

Background: Parkinson’s disease (PD) is the second most commonly occurring neurodegenerative disease and is classed as a synucleinopathy due to the critical role of α-synuclein (α-Syn) in its pathology. α-Syn is able to translocate from the cytoplasm to the nucleus and cause DNA damage. Methods: SH-SY5Y cells were stably transfected with plasmids containing wildtype α-Syn and A53T mutant α-Syn as fusion proteins with EGFP and an EGFP only control vector. The cells were treated with hydrogen peroxide (H2O2) and analysed in a differentiated state for the effects of oxidative stress using flow cytometry, DNA damage using H2A.X staining and inflammatory and senescence markers using qPCR. Results: Cells expressing the A53T mutation exhibited a higher sensitivity to treatment with H2O2 with significantly higher amounts of DNA damage. Importantly, WT α-Syn seemed to have a protective effect in differentiated cells under increased stress with no increase in DNA damage after H2O2 treatment. In line with these results, inflammatory markers of COX-2, IL-6 and TNF-α as well as stress-and senescence markers p21 and p16 were all significantly increased in differentiated treated cells expressing mutated α-Syn while there were no changes in cells expressing wildtype α-Syn. Interestingly, both forms of α-Syn increased the levels of mitochondrial ROS already in untreated conditions while there were no differences between the two α-Syn forms. Conclusions: Our data demonstrate a higher stress sensitivity of SH-SY5Y neuroblastoma cells harbouring an A53T mutant α-Syn for DNA damage and selected inflammatory marker. In contrast, wildtype α-Syn seemed to provide protection against oxidative stress in a neurone-like cellular model. Thus, these neuroblastoma cells differentiated with retinoid acid seem to be a good model for studying various pathological effects of α-Syn.