Extended survival of SH‐SY5Y cells following overexpression of Lys67Glu neuroglobin is associated with stabilization of ΔψM

Overwhelming evidence indicates that a high level of expression of the protein neuroglobin protects neurons in vitro, in animal models, and in humans, against cell death associated with hypoxic and amyloid insult. We have previously showed that neuroglobin protects neuronal cells from the mitochondrial pathway of apoptosis induced by the BH3 mimetic, by preventing cytochrome c‐triggered activation of caspase 9. Here, using cell and molecular biology approaches, we generated a particular neuroglobin mutant, Lys67Glu, overexpression of which confers a significant protection from the BH3 mimetic (TW‐37)‐induced apoptosis in human neuroblastoma SH‐SY5Y cells. The cumulative inhibition of caspase 9 activation is significantly enhanced in Lys67Glu neuroglobin‐expressing cells, as compared to wild‐type neuroglobin expressing cells. A multiparameter flow cytometry analysis of TW‐37‐treated cells revealed that inhibition of caspase 9 activity by Lys67Glu neuroglobin is associated with the preservation of the mitochondrial transmembrane potential (ΔψM), as well as a decreased rate of cytochrome crelease from the mitochondria. © 2012 International Society for Advancement of Cytometry