Endonuclease VIII-like 1 deficiency potentiates nigrostriatal dopaminergic neuron degeneration in a male mouse model of Parkinson's disease

Parkinson's disease (PD) is a common movement disorder caused by a characteristic loss of dopaminergic neurons in the substantia nigra and degeneration of dopamine terminals in the dorsal striatum. Previous studies have suggested that oxidative stress-induced DNA damage may be involved in PD pathogenesis, as steady-state levels of several types of oxidized nucleobases were shown to be elevated in PD brain tissues. These DNA lesions are normally removed from the genome by base excision repair, which is initiated by DNA glycosylase enzymes such as endonuclease VIII-like 1 (Neil1). In this study, we show that Neil1 plays an important role in limiting oxidative stress-induced degeneration of dopaminergic neurons. In particular, Neil1-deficient male mice exhibited enhanced sensitivity to nigrostriatal degeneration after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) administration, and Neil1-deficient animals had higher levels of gamma H2AX-marked DNA damage than wild-type (WT) controls, regardless of treatment status. Moreover, MPTP-treated Neil1(-/-) male mice had slightly elevated expression of genes related to the nuclear factor erythroid 2-related factor 2 (Nrf2)-dependent antioxidant pathway. Treatment with the Nrf2 activator, monomethyl fumarate, reduced PD-like behaviors and pathology in Neil1(-/-) male mice, suggesting that Neil1 is an important defense molecule in an oxidative cellular environment. Taken together, these results suggest that Neil1 DNA glycosylase may play an important role in limiting oxidative stress-mediated PD pathogenesis.