| Co-Investigator(Kenkyū-buntansha) |
NISHIZAWA Yuji Nagoya University School of Medicine, Department of Cell Biology and Molecular Pathology, Lecturer, 医学部, 助手 (80252229)
WAKABAYASHI Takashi Nagoya University School of Medicine, Department of Cell Biology and Molecular Pathology, Professor, 医学部, 教授 (00079998)
ISHIKAWA Tetsuya Aichi Medical University School of Medicine, Department of Medicine, Lecturer, 医学部, 講師 (10288508)
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| Research Abstract |
Toxic effects of chloramphenicol, an antibiotic inhibitor of mitochondrial protein synthesis, on rat liver derived RL-34 cell line were completely blocked by a combined treatment with substances endowed with direct or indirect antioxidant properties. A stable, nitroxide free radical scavenger, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and a protein synthesis inhibitor, cycloheximide, suppressed in a similar manner the following manifestations of the chloramphenicol cytotoxicity : (1) Oxidative stress state as evidenced by FACS analysis of cells loaded with carboxy-dichlorodihydrofluorescein diacetate and Mito Tracker CMTH_2MRos ; (2) megamitochondoria formation detected by staining of mitochondria with Mito Tracker CMXRos under a laser confocal microscopy and electron microscopy ; (3) apoptotic changes of the cell detected by the phase contrast microscopy, DNA laddering analysis and cell cycle analysis. Since increases of ROS generation in chloramphenicol-treated cells were the first sign of the chloramphenicol toxicity, we assume that oxidative stress state is a mediator of above described alternations of RL-34 cells including MG formation. Pretreatment of cells with cycloheximide or 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, which is known to be localized into mitochondria, inhibited the megamitochondria formation and succeeding apoptotic changes of the cell. Protective effects of cycloheximide, which enhances the expression of Bcl-2 protein, may further confirm our hypothesis that the megamitochondria formation is a cellular response to an increased ROS generation and raise a possibility that antiapoptotic action of the drug is exerted via the protection of the mitochondria functions.
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