Nuclear translocation of DJ-1 protects adult neuronal stem cells in an MPTP mouse model of Parkinson's disease

DJ-1, originally identified as an oncogene product, is involved in multiple processes, including cellular transformation, the oxidative stress response, and transcriptional regulation. We had previously found that DJ-1 was closely associated with the proliferation and differentiation of cultured neuronal stem cells. In this study, we further investigated the functions of DJ-1 to determine how adult neurogenesis was affected in the subgranular zones (SGZ), subventricular zone (SVZ), and olfactory bulb (OB), which are brain areas closely related to early nonmotor symptoms of Parkinson's disease, using a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of Parkinson's disease. The results showed that the numbers of 5-bromo-2-deoxyuridine-positive (BrdU(+)) cells in the SGZ and SVZ of mice in the MPTP group were not significantly different from those in the saline controls, whereas the number of BrdU(+) cells in the olfactory granule cell layer and glomerulus layer of the OB in the MPTP group changed markedly. We also found that DJ-1 was translocated into the nuclei of BrdU(+) cells in the SGZ and SVZ, but not in the OB. This may indicate that the nuclear translocation of DJ-1 in the SGZ and SVZ protects adult neuronal stem cells from damage caused by MPTP so that the normal number is maintained, but is not involved in the protective mechanism in the OB.