CXCL10-induced cell death in neurons: role of calcium dysregulation

Chemokines play a key role in the regulation of central nervous system disease. CXCL10 over‐expression has been observed in several neurodegenerative diseases, including multiple sclerosis, Alzheimer's disease and HIV‐associated dementia. More recent studies by others and us have shown that CXCL10 elicits apoptosis in fetal neurons. The mechanism of CXCL10‐mediated neurotoxicity, however, remains unclear. In this study, we provide evidence for the direct role of Ca2+ dysregulation in CXCL10‐mediated apoptosis. We demonstrate that treatment of fetal neuronal cultures with exogenous CXCL10 produced elevations in intracellular Ca2+ and that this effect was modulated via the binding of CXCL10 to its cognate receptor, CXCR3. We further explored the association of intracellular Ca2+ elevations with the caspases that are involved in CXC10‐induced neuronal apoptosis. Our data showed that increased Ca2+, which is available for uptake by the mitochondria, is associated with membrane permeabilization and cytochrome c release from this compartment. The released cytochrome c then activates the initiator active caspase‐9. This initiator caspase sequentially activates the effector caspase‐3, ultimately leading to apoptosis. This study identifies the temporal signaling cascade involved in CXCL10‐mediated neuronal apoptosis and provides putative targets for pharmaceutical intervention of neurological disorders associated with CXCL10 up‐regulation.