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Ken Hayashi, Katsuaki Dan, Fumiyuki Goto, Sho Kanzaki and Kaoru Ogawa
Scientific Tracks Abstracts: J Cell Sci Ther
Th e purposes of this study are to elucidate how oxidative stress exerts its cytotoxic eff ects on auditory cell line (HEI-OC1) and to uncover the molecular mechanism of autophagy in auditory cells under oxidative stress. We used HEI-OC1 in this study. Th e viability of HEI-OC1 was determined by cell viability assays. Th e samples aft er treatment of HEI-OC1 were analyzed by a FACscan fl ow cytometer. Electron microscopy and morphometric analysis were performed at x6000. Immunofl uorescent confocal laser microscopy was used. For protein analysis, western blot was performed. HEI-OC1 treated with diff erent concentrations of H 2 O 2 for 0.5 h and 1 h exhibited the dose- and time-dependent cell death. Aft er H 2 O 2 treatment, not apoptotic cell but necrotic cell was detected by FACscan analysis. H 2 O 2 treatment induced formation of autophagic vacuoles in HEI-OC1. On the other hand, the pretreatment of HEI-OC1 with ATP and rapamycin protect against H 2 O 2 ?induced necrotic cell death. In addition, not only the treatment with H 2 O 2 but also the pretreatment with ATP and rapamycin induced autophagy. Th e expression of GFP-LC3 was induced in not only H 2 O 2 but also ATP and rapamycin- treated HEI-OC1 under immunofl uorescent confocal laser microscope. Aft er treatment with ATP and rapamycin, the accumulation of LC3-I/II ratio was observed, and the expression of ATG7 was induced in H 2 O 2 -treated HEI-OC1. Consequently, we demonstrated a promotion of autophagy through the mTOR signaling pathway to enhance cell survival in auditory cells under oxidative stress. Th ese fi ndings are believed to bear relationships for understanding the complex relationship among oxidative stress, autophagy and cell death in auditory cells.
Ken Hayashi has completed his MD from Tokai University in 1995, his PhD from Hiroshima University in 2000 and postdoctoral studies from University of California, San Diego. He is an assistant director of Shinkawa Clinic. He has published more than 20 papers in reputed journals and serving as an editorial board member of Journal of Cell Science & Therapy