CALCIUM AND REACTIVE OXYGEN SPECIES MEDIATE STAUROSPORINE-INDUCED MITOCHONDRIAL DYSFUNCTION AND APOPTOSIS IN PC12 CELLS

The bacterial alkaloid staurosporine is widely employed as an inducer of apoptosis in many cell types including neurons, The intracellular c ascades that mediate staurosporine-induced apoptosis are largely unkno wn, Exposure of cultured PC12 cells to staurosporine resulted in a rap id (min) and prolonged (1-6 hr) elevation of intracellular free calciu m levels [Ca2+](i), accumulation of mitochondrial reactive oxygen spec ies (ROS), and decreased mitochondrial (4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) reduction (1-4 hr), These early even ts were followed by membrane lipid peroxidation, loss of mitochondrial transmembrane potential, and nuclear apoptotic changes, Treatment of cells with serum or nerve growth factor within 1-2 hr of staurosporine exposure resulted in recovery of [Ca2+](i) and ROS levels, and rescue d the cells from apoptosis, The increased [Ca2+](i) and ROS production were required for staurosporine-induced apoptosis because the intrace llular calcium chelator BAPTA and uric acid (an agent that scavenges p eroxynitrite) each protected cells against apoptosis, The caspase inhi bitor zVAD-fmk and the anti-apoptotic gene product Bcl-2 prevented the sustained [Ca2+](i) increase and ROS accumulation induced by staurosp orine indicating that caspases act very early in the apoptotic process , Our data indicate that a [Ca2+](i) increase is an early and critical event in staurosporine-induced apoptosis that engages a cell death pa thway involving ROS production, oxidative stress, and mitochondrial dy sfunction, (C) 1998 Wiley-Liss, Inc.