Protection against nonylphenol-induced cell death by DJ-1 in cultured Japanese medaka ( Oryzias latipes) cells

Abstract

The Japanese medaka ( Oryzias latipes) has been used to investigate diverse aspects of toxicology, genetics and developmental biology and to monitor biological changes caused by endocrine disruptors. In this study, we analyzed a medaka homolog of human DJ-1 (meDJ-1) in cultured medaka cells into which nonylphenol (NP) was added. Like human DJ-1, meDJ-1 was found to be oxidized by treatment with H 2O 2 and its p I was shifted to acidic points. NP was found to induce cell death with kinetics similar to that of H 2O 2 in cultured medaka OLHE-13 cells. After OLHE-13 cells had been treated with sub-lethal concentrations of H 2O 2 and NP, production of reactive oxygen species and oxidation of meDJ-1 were observed. meDJ-1 knockdown by short interfering RNA rendered OLHE-13 cells susceptible to H 2O 2 and NP-induced cell death, suggesting a protective role of DJ-1 against oxidative stress-induced cell death in medaka cells. These results suggest that meDJ-1 is a suitable biomarker for oxidative stress reactions in medaka.