Protein disulfide isomerase mediates glutathione depletion-induced cytotoxicity.
Glutathione depletion is a distinct cause underlying many forms of pathogenesis associated with oxidative stress and cytotoxicity. Earlier studies showed that glutamate-induced glutathione depletion in immortalized murine HT22 hippocampal neuronal cells leads to accumulation of reactive oxygen species (ROS) and ultimately cell death, but the precise mechanism underlying these processes is not clear. Here we show that during the induction of glutathione depletion, nitric oxide (NO) accumulation precedes ROS accumulation. While neuronal NO synthase (nNOS) in untreated HT22 cells exists mostly as a monomer, glutathione depletion results in increased formation of the dimer nNOS, accompanied by increases in the catalytic activity. We identified that nNOS dimerization is catalyzed by protein disulfide isomerase (PDI). Inhibition of PDI's isomerase activity effectively abrogates glutathione depletion-induced conversion of monomer nNOS into dimer nNOS, accumulation of NO and ROS, and cytotoxicity. Furthermore, we found that PDI is present in untreated cells in an inactive S-nitrosylated form, which becomes activated following glutathione depletion via S-denitrosylation. These results reveal a novel role for PDI in mediating glutathione depletion-induced oxidative cytotoxicity, as well as its role as a valuable therapeutic target for protection against oxidative cytotoxicity.
University of Kansas Medical Center, Department of Pharmacology, Toxicology and Therapeutics, Kansas City, 66160, USA; South University of Science and Technology of China, Department of Biology, Shenzhen, 518055, China.
Kazushi
K
Okada
University of Kansas Medical Center, Department of Pharmacology, Toxicology and Therapeutics, Kansas City, 66160, USA.
Masayuki
M
Fukui
University of Kansas Medical Center, Department of Pharmacology, Toxicology and Therapeutics, Kansas City, 66160, USA; South University of Science and Technology of China, Department of Biology, Shenzhen, 518055, China; The Chinese University of Hong Kong (Shenzhen), School of Science and Engineering, Division of Biomedicine and Bioengineering, Shenzhen, 518172, China. Electronic address: BTZhu@CUHK.edu.cn.
Bao-Ting
BT
Zhu
D000818:Animals; D005978:Glutathione / Q000378:metabolism*; D019704:Protein Disulfide-Isomerases / Q000378:metabolism*; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D019704:Protein Disulfide-Isomerases; D005978:Glutathione
Glutamate toxicity; Glutathione; Nitric oxide; Protein disulfide isomerase; Reactive oxygen species; S-nitrosylation