THAPSIGARGIN INDUCES APOPTOSIS IN SH-SY5Y NEUROBLASTOMA-CELLS AND CEREBROCORTICAL CULTURES

Thapsigargin, a specific inhibitor of the endoplasmic reticular Ca2+-A TPase, has been used previously to mobilize calcium release from intra cellular calcium stores. We now show that thapsigargin (1-10 mu M) ind uces apoptosis in a neuroblastoma cell line (SH-SY5Y) and in fetal rat cerebrocortical cultures. Cell death measured by lactate dehydrogenas e release was observed 24-48 hours after treatment with thapsigargin. In both cases, DNA extracts from thapsigargin treated cells showed lad dering, typical of endonuclease-mediated internucleosomal cleavages. T he presence of DNA fragments was also confirmed by an ELISA designed f or detecting nucleosomes in apoptotic cells. Cycloheximide reduced the extent of DNA fragmentation and injury in thapsigargin-treated cells. Dantrolene, an inhibitor of calcium release from intracellular stores partially abolished the effect of thapsigargin, suggesting that the i nitial Ca2+ rise may be the signalling event in this apoptotic cell de ath pathway. We propose that thapsigargin-induced cell death in cultur ed neuronal cells maybe a useful system to study the molecular and gen etic events involved in apoptosis.