Imidazole-induced cell death, associated with intracellular acidification, caspase-3 activation, DFF-45 cleavage, but not oligonucleosomal DNA fragmentation.
Intracellular acidification is known to be involved in the initiation phase of apoptosis. However, the necessity of intracellular acidic conditions in the execution phase of apoptosis remains unknown. In this study, we found that in HL-60 cells imidazole induces cell death, associated with intracellular acidification, caspase-3 activation and DFF-45 cleavage, but not oligonucleosomal DNA fragmentation. A caspase inhibitor prevented cell death but not intracellular acidification. When pHi was neutralized by changing from imidazole-containing medium to fresh medium, oligonucleosomal DNA fragmentation and increased caspase-3 activity was observed in the imidazole-treated HL-60 cells. Furthermore, the DNA fragmentation induced by intracellular neutralization was inhibited by caspase inhibitor treatment. These results indicate that imidazole induces caspase-dependent cell death, and suggest that maintaining pHi in the neutral range is essential for the induction of oligonucleosomal DNA fragmentation in the execution phase of apoptosis.
Iguchi
K
K
Laboratory of Pharmaceutics, Gifu Pharmaceutical University, 5-6-1 Mitahora-higashi, Gifu 502-8585, Japan.
Usui
S
S
Ishida
R
R
Hirano
K
K
D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000378:metabolism; D011506:Proteins / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D007093:Imidazoles; D011506:Proteins; C109664:caspase-activated DNase inhibitor; C029899:imidazole; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases