Involvement of intracellular labile zinc in suppression of DEVD-caspase activity in human neuroblastoma cells

Age-related tissue Zn deficiency may contribute to neuronal and glial cell death by apoptosis in Alzheimer's dementia. To investigate this, we studied the effects of increasing or decreasing the levels of intracellular labile Zn on apoptosis of human neuroblastoma BE(2)-C cells in vitro. BE(2)-C cel ls were primed for 18 h with butyrate (1 mM) before addition of staurospori ne (1 mu M), an effector enzyme of apoptosis, for a further 3 h to induce D EVD-caspase activity. An increase in intracellular Zn using Zn ionophore py rithione suppressed DEVD-caspase activity, while a decrease in intracellula r Zn induced by Zn chelator TPEN mimicked staurosporine by activating DEVD- caspase in butyrate-primed cells. The distribution of intracellular Zn in t he cells was demonstrated with the UV-excitable Zn-specific fluorophore Zin quin. Confocal images showed distinct cytoplasmic and cytoskeletal fluoresc ence. We propose that Zn decreases the level of apoptosis in neuronal cells exposed to toxins, possibly by stabilizing their cytoskeleton. (C) 2000 Ac ademic Press.