Nei-like 1 inhibition results in motor dysfunction and promotes inflammation in Parkinson's disease mice model

Parkinson's disease (PD) is well known as a neurodegenerative disorder with progressive loss of dopaminergic (DA) neurons. Nei-like 1 (NEIL1) is one of four mammalian DNA glycosylases involved in the progression of various diseases, including neuroinflammation. However, it is still unknown if the expression changes of NEIL1 could contribute to PD progression. In the present study, we established mouse model with PD using 6-hydroxydopamine (6-OHDA) and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) to explore the effects of NEIL1 on PD development. Here, we found that NEIL1 deletion significantly promoted the motor dysfunction in the wild type mice treated with 6-OHDA. Furthermore, DA neuronal loss was further accelerated by NEIL1 deletion in 6-OHDA-injected mice, as evidenced by the significantly reduced expression of tyrosine hydroxylase (TH) and dopamine transporter (DAT). Furthermore, in PD mice induced by MPTP, remarkably reduced expression of NEIL1 was observed in nigra and striatum of mice. A strong positive correlation was detected in the expression of NEIL1 and the survival rate of DA neurons. Also, NEIL1 ablation further elevated the DA neuronal loss in MPTP-treated mice, accompanied with higher glial activation, as evidenced by the obvious up-regulation of glial fibrillary acidic protein (GFAP) and Ionized calcium-Binding Adapter molecule 1 (Iba1). Moreover, MPTP-triggered inflammation was highly aggravated by the loss of NEIL1 through inducing the expression of pro-inflammatory cytokines and chemokines. In contrast, promoting NEIL1 expression effectively reversedPD progression induced by MPTP in mice. Together, these results demonstrated that NEIL1 insufficiency might be a contributing factor for the progression of PD, which therefore could be considered as a novel candidate to develop effective treatments against PD progression.