title: Hydrogen Peroxide-Induced Oxidative Stress Activates Proteasomal Trypsin-Like Activity in Human U373 Glioma Cells.
abstract: Degradation of oxidized or oxidatively modified proteins is an essential part of the cellular antioxidant defense system. 4-Hydroxy-2-nonenal, a major reactive aldehyde formed by lipid peroxidation, causes many types of cellular damage. The major proteolytic system for modified protein degradation is the ubiquitin-proteasome pathway. However, our previous studies using U937 human leukemic cells showed that 4-hydroxy-2-nonenal-modified glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is degraded by cathepsin G. In the present study, U373 human glioma cells were cultured in the presence of hydrogen peroxide (H2O2) to investigate the relationships of proteasome and/or cathepsin G activities and H2O2-induced GAPDH degradation. Treatment of cells with H2O2 for 5 h in culture decreased GAPDH activity as well as its protein concentration in a concentration-dependent manner. Two proteasomal activities (peptidylglutamyl-peptide hydrolase and chymotrypsin-like hydrolase activities) and cathepsin G activity were decreased by H2O2 treatment in a concentration-dependent manner, but proteasomal trypsin-like hydrolase activity increased with cell exposure to high H2O2 concentrations. Among the protease inhibitors examined here, H2O2-induced activation of trypsin-like activity and GAPDH degradation were inhibited by the proteasome inhibitor lactacystin. Furthermore, H2O2-induced activation of trypsin-like activity was also inhibited by another proteasome inhibitor MG-132. These results suggested that proteasomal trypsin-like activity played an important role in eliminating oxidatively modified GAPDH formed in these cells during H2O2 exposure.
authors.affiliation: Department of Analytical Chemistry of Medicines, Showa Pharmaceutical University, 3-3165 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Nakayama
authors.affiliation: Department of Analytical Chemistry of Medicines, Showa Pharmaceutical University, 3-3165 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan.
authors.forename: Saki
authors.initials: S
authors.lastname: Yamaguchi
authors.affiliation: Department of Analytical Chemistry of Medicines, Showa Pharmaceutical University, 3-3165 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan.
authors.forename: Yuta
authors.initials: Y
authors.lastname: Sasaki
authors.affiliation: Department of Analytical Chemistry of Medicines, Showa Pharmaceutical University, 3-3165 Higashi-tamagawagakuen, Machida, Tokyo, 194-8543, Japan. chikuma@ac.shoyaku.ac.jp.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Chikuma
mesh_terms: D056649:Cathepsin G / Q000378:metabolism; D045744:Cell Line, Tumor; D005910:Glioma / Q000201:enzymology / Q000378:metabolism*; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D009474:Neurons / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D018384:Oxidative Stress; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D061988:Proteasome Inhibitors / Q000494:pharmacology; D059748:Proteolysis; D014357:Trypsin / Q000378:metabolism*
chemical_list: D061988:Proteasome Inhibitors; D006861:Hydrogen Peroxide; D024581:Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating); D056649:Cathepsin G; D014357:Trypsin; D046988:Proteasome Endopeptidase Complex
keywords: Glyceraldehyde-3-phosphate dehydrogenase; Hydrogen peroxide; Lactacystin; MG-132; Proteasome; Trypsin-like activity; U373