• Kosuke Inoue, Hitoshi Kuwana, Yoshiko Shimamura, Koji Ogata, Yoshinori Taniguchi, Toru Kagawa, Taro Horino, Toshihiro Takao, Tatsuhito Morita, Sei Sasaki, Noboru Mizushima, and Yoshio Terada.
• The Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi 783-8505, Japan.
• Clin. Exp. Nephrol. 2010 Apr 1;14(2):112-22.

BackgroundAutophagy is an intracellular bulk degradation process induced by cell starvation. Autophagy was recently reported to be induced by various stresses such as hypoxia, ischemia/reperfusion, toxins, and denatured proteins, and to affect cell survival and death. Light chain 3-II (LC3-II) is specifically located on double membrane-bound autophagosomes that envelop disused proteins or organelles.MethodTransgenic mice in which green fluorescent protein (GFP) was fused to LC3 (LC3-GFP) were administered cisplatin (20 mg/kg). After euthanasia at times between 0 and 72 h, kidneys were excised for immunohistochemical analyses. Microscopic examinations of the generated NRK-52E cell lines stably transfected with LC3-GFP, and Western blot analyses of NRK-52E cells, were undertaken after cisplatin treatment with or without autophagy inhibitors and beclin 1 small interfering RNA (siRNA).ResultsAutophagosomes increased in the proximal tubular cells of transgenic mice from 12 h after cisplatin injection (20 mg/kg). The time course for this was faster than those for tubular necrosis and apoptosis. Autophagosomes also increased in NRK-52E cells after cisplatin treatment, with the time course for this being faster than that for apoptosis. When autophagy was suppressed by autophagy inhibitors or beclin 1 siRNA, the level of apoptosis was also suppressed.ConclusionAutophagy occurs in proximal tubular cells after cisplatin treatment and is involved in cell death in renal tubular injury. Our data suggest that autophagy is a kind of cell damage index and that cells with activated autophagy will be scavenged by apoptosis.

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