Stress hormone potentiates Zn2+-induced neurotoxicity via TRPM7 channel in dopaminergic neuron

Zinc toxicity is one of the key factors responsible for the neuronal injuries associated with various neurological conditions. Zinc accumulation in some cells is accompanied by the increase of blood stress hormone levels, which might indicate a functional connection between stress and zinc toxicity. However, the cellular mechanism for the effect of stress on zinc toxicity is not known. Recently, it was reported that the zinc permeable transient receptor potential melastatin 7 (TRPM7) channel may represent a novel target for neurological disorders where zinc toxicity plays an important role. To investigate the effect of stress hormone on zinc-induced cell death, neuroblastoma SH-SY5Y cells were pretreated with urocortin, a corticotropin releasing factor (CRF)-related peptide. Urocortin potentiated zinc-induced cell death at μM range of extracellular zinc concentrations. It significantly increased TRPM7 channel expression, and zinc influx into cytosol. Moreover, application of TRPM7 channel blockers and RNA interference of TRPM7 channel expression attenuated the zinc-induced cell death in urocortin-pretreated cells, indicating that TRPM7 channel may serve as a zinc influx pathway. These results suggest that TRPM7 channel may play a critical role for zinc toxicity associated with stress.