Intracellular-produced hydroxyl radical mediates H2O2-induced Ca2+ influx and cell death in rat beta-cell line RIN-5F.
The melastatin-related transient receptor potential channel TRPM2 is a Ca(2+)-permeable channel that is activated by H(2)O(2), and the Ca(2+) influx through TRPM2 mediates cell death. However, the responsible oxidants for TRPM2 activation remain to be identified. In the present study, we investigated the involvement of hydroxyl radical on TRPM2 activation in TRPM2-expressing HEK293 cells and the rat beta-cell line RIN-5F. In both cell types, H(2)O(2) induced Ca(2+) influx in a concentration-dependent manner. However, the addition of hydroxyl radical, which was produced by mixing FeSO(4) and H(2)O(2), to the cells, did not increase intracellular Ca(2+) concentration. Interestingly, when H(2)O(2) was added to the cells under intracellular Fe(2+)-accumulated conditions, Ca(2+) influx was markedly enhanced compared to H(2)O(2) alone. In addition, the H(2)O(2)-induced Ca(2+) influx was reduced by hydroxyl radical scavengers and an iron chelator. Under intracellular Fe(2+)-accumulated conditions, H(2)O(2)-induced RIN-5F cell death through TRPM2 activation was also markedly enhanced. Hydroxyl radical scavengers and an iron chelator suppressed the RIN-5F cell death by H(2)O(2). These results strongly suggest that the intracellular hydroxyl radical plays a key role in the activation of TRPM2 during H(2)O(2) treatment, and TRPM2 activation mediated by hydroxyl radical is implicated in H(2)O(2)-induced cell death in the beta-cell line RIN-5F.
Department of Pathophysiology, School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan. masakazu@pharm.showa-u.ac.jp
Masakazu
M
Ishii
Shunichi
S
Shimizu
Yuji
Y
Hara
Tamio
T
Hagiwara
Akira
A
Miyazaki
Yasuo
Y
Mori
Yuji
Y
Kiuchi
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects*; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D017665:Hydroxyl Radical / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000166:cytology* / Q000187:drug effects*; D007502:Iron Chelating Agents / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D050053:TRPM Cation Channels / Q000378:metabolism
D016166:Free Radical Scavengers; D007502:Iron Chelating Agents; D050053:TRPM Cation Channels; C121934:TRPM2 protein, human; D017665:Hydroxyl Radical; D011189:Potassium Chloride; D000255:Adenosine Triphosphate; D006861:Hydrogen Peroxide; D002118:Calcium