A critical role of TRPM2 in neuronal cell death by hydrogen peroxide

A brief exposure to hydrogen peroxide (H₂O₂) induces severe deterioration of primary cultured neurons in vitro. We have investigated a link between the H₂O₂-induced neuronal death and Ca ²⁺-permeable TRPM2 channels regulated by ADP-ribose (ADPR). In cultured cerebral cortical neurons from fetal rat, TRPM2 proteins were detected at cell bodies and neurite extensions. Application of H₂O₂ to the cultured neurons elicited an increase in intracellular Ca²⁺ concentration ([Ca²⁺]_i) caused by Ca²⁺ influx and the Ca²⁺-dependent neuronal death in a similar concentration range. Molecular cloning of TRPM2 cDNA from rat brain revealed several differences in amino acid sequences within the Nudix box region as compared with those of human and mouse TRPM2. ADPR-induced current responses, H ₂O₂-induced Ca²⁺ influx, and H ₂O₂-induced cell death were induced in human embryonic kidney cells heterologously expressing rat TRPM2. Treatment of cultured neurons with small interfering RNA against rat TRPM2, which efficiently suppressed immunoreactive TRPM2 content and the H₂O₂-induced Ca ²⁺ influx, significantly inhibited H₂O₂-induced neuronal death. These results suggest that TRPM2 plays a pivotal role in H ₂O₂-induced neuronal death as redox-sensitive Ca ²⁺-permeable channels expressed in neurons.