Prohibitin S-nitrosylation is required for the neuroprotective effect of nitric oxide in neuronal cultures.

Prohibitin (PHB) is a critical protein involved in many cellular activities. In brain, PHB resides in mitochondria, where it forms a large protein complex with PHB2 in the inner TFmembrane, which serves as a scaffolding platform for proteins involved in mitochondrial structural and functional integrity. PHB overexpression at moderate levels provides neuroprotection in experimental brain injury models. In addition, PHB expression is involved in ischemic preconditioning, as its expression is enhanced in preconditioning paradigms. However, the mechanisms of PHB functional regulation are still unknown. Observations that nitric oxide (NO) plays a key role in ischemia preconditioning compelled us to postulate that the neuroprotective effect of PHB could be regulated by NO. Here, we test this hypothesis in a neuronal model of ischemia-reperfusion injury and show that NO and PHB are mutually required for neuronal resilience against oxygen and glucose deprivation stress. Further, we demonstrate that NO post-translationally modifies PHB through protein S-nitrosylation and regulates PHB neuroprotective function, in a nitric oxide synthase-dependent manner. These results uncover the mechanisms of a previously unrecognized form of molecular regulation of PHB that underlies its neuroprotective function.