DJ-1 was first identified by our group as a novel oncogene. Deletion and point mutations of DJ-1 have been shown to be responsible for onset of familial Parkinson's disease(PD). DJ-1 plays many functions. DJ-1 is located in the cytoplasm, nucleus and mitochondria in cells, and secreted DJ-1 has been observed in various cultured cells and tissues, including cancer cells and tissues, astrocytes and serum of patients with Parkinson's disease. But, the mechanism of DJ-1 secretion is still unkown.
Previously, we reported that DJ-1 was found to be secreted into culture media of various cells. Furthermore, the oxidative status of more than 90% of the DJ-1 secreted from cells was SOH and SO₂H forms of cysteine at 106(C106).
In this study, the effect of secreted DJ-1 from astrocytes on viability of neurons and production of reactive oxygen species(ROS) was examined in the non-contact co-cultured system of astrocytes an neurons. The results showed that astrocytes from DJ-1(+/+) mouse but not from DJ-1(-/-) mouse restored neuroprotective activity that has reduced under an oxidative condition and that secreted wild-type DJ-1 but not C106S from DJ-1-transfeted astrocytes into culture media protects H₂O₂-induced neuronal cell death and decreased production of ROS in neurons.