title: Inositol 1,4,5-trisphosphate receptor-mediated initial Ca(2+) mobilization constitutes a triggering signal for hydrogen peroxide-induced apoptosis in INS-1 β-cells.
abstract: Reactive oxygen species, including hydrogen peroxide (H(2)O(2)), are known to induce β-cell apoptosis. The present study investigated the role of Ca(2+) in H(2)O(2)-induced apoptosis of the β-cell line INS-1. Annexin V assay with flow cytometry and DNA ladder assay demonstrated that treatment of INS-1 cells with 100 µM H(2)O(2) for 18 h significantly increased apoptotic cells. A comparable level of apoptosis was also observed after 18 h when the cells were treated with 100 µM H(2)O(2) only for initial 30 min. The H(2)O(2)-induced apoptosis was abolished by 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetra(acetoxymethyl)ester (BAPTA/AM), a chelator of intracellular Ca(2+), by 2-aminoethoxydiphenylborate (2-APB), a blocker of inositol 1,4,5-trisphosphate (IP(3)) receptors and cation channels, and by xestospongin D, a blocker of IP(3) receptors, and was partially blocked by SKF-96365, a non-selective cation channel blocker. However, nicardipine, an L-type voltage-dependent Ca(2+) channel blocker, or N-(p-amylcinnamoyl)anthranilic acid (ACA), a TRPM2 blocker, had little effect on the apoptosis. The inhibitory effect of BAPTA/AM or 2-APB on the H(2)O(2)-induced apoptosis was largely attenuated when the drug was added 30 min or 1 h after start of the treatment with H(2)O(2). These results suggest that the initial intracellular Ca(2+) elevation induced by H(2)O(2), which is mediated via IP(3) receptors and store-operated cation channels, plays an obligatory role in the induction of β-cell apoptosis.
authors: Department of Pharmacology, Graduate School of Pharmaceutical Sciences, University of Shizuoka, 52–1 Yada, Surugaku, Shizuoka, Shizuoka 422–8526, Japan.
authors: Masahiro
authors: M
authors: Takada
authors: Akiko
authors: A
authors: Noguchi
authors: Yurie
authors: Y
authors: Sayama
authors: Yukiko
authors: Y
authors: Kurohane Kaneko
authors: Tomohisa
authors: T
authors: Ishikawa
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D053496:Inositol 1,4,5-Trisphosphate Receptors / Q000378:metabolism*; D007515:Islets of Langerhans / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D053496:Inositol 1,4,5-Trisphosphate Receptors; D006861:Hydrogen Peroxide; D002118:Calcium