Chloroquine-induced neuronal cell death is p53 and Bcl-2 family-dependent but caspase-independent

Chloroquine is a lysosomotropic agent that causes marked changes in intrace llular protein processing and trafficking and extensive autophagic vacuole formation. Chloroquine may be cytotoxic and has been used as a model of lys osomal-dependent cell death. Recent studies indicate that autophagic cell d eath may involve Bcl-2 family members and share some features with caspase- dependent apoptotic death. To determine the molecular pathway of chloroquin e-induced neuronal cell death, we examined the effects of chloroquine on pr imary telencephalic neuronal cultures derived from mice with targeted gene disruptions in p53, and various caspase and bcl-2 family members. In wild-t ype neurons, chloroquine produced concentration- and time-dependent accumul ation of autophagosomes, caspase-3 activation, and cell death. Cell death w as inhibited by 3-methyladenine, an inhibitor of autophagic vacuole formati on, but not by Boc-Asp-FMK (BAF), a broad caspase inhibitor. Targeted gene disruptions of b53 and bax inhibited and bcl-x potentiated chloroquine-indu ced neuron death. Caspase-9- and caspase-3-deficient neurons were not prote cted from chloroquine cytotoxicity. These studies indicate that chloroquine activates a regulated cell death pathway that partially overlaps with the apoptotic cascade.