Salubrinal, ER stress inhibitor, attenuates kainic acid-induced hippocampal cell death

Kainic acid (KA)-induced neuronal death is closely linked to endoplasmic reticulum (ER) and mitochondrial dysfunction. Parkin is an ubiquitin E3 ligase that mediates the ubiquitination of the Bcl-2 family of proteins and its mutations are associated with neuronal apoptosis in neurodegenerative diseases. We investigated the effect of salubrinal, an ER stress inhibitor, on the regulation of ER stress and mitochondrial apoptosis induced by KA, in particular, by controlling parkin expression. We showed that salubrinal significantly reduced seizure activity and increased survival rates of mice with KA-induced seizures. We found that salubrinal protected neurons against apoptotic death by reducing expression of mitochondrial apoptotic factors and elF2α-ATF4-CHOP signaling proteins. Interestingly, we showed that salubrinal decreased the KA-induced parkin expression and inhibited parkin translocation to mitochondria, which suggests that parkin may regulate a cross-talk between ER and mitochondria. Collectively, inhibition of ER stress attenuates mitochondrial apoptotic and ER stress pathways and controls parkin-mediated neuronal death following KA-induced seizures.