Nuclear translocation of GluA2/ GAPDH promotes neurotoxicity after pilocarpine-induced epilepsy

Abstract

Recent studies have identified that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) exerts multiple functions besides its role in energy metabolism. It can form a protein complex with GluA2 subunit of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs), translocate into nucleus and confer neurotoxicity in a cerebral ischemia model. We postulate that GAPDH may also induce neurotoxicity by forming a coupling with GluA2 in pilocarpine-induced epileptic model, and disruption of the GluA2/GAPDH coupling can protect against neuronal injury. In this study, induced status epilepticus (SE) in rats by the systemic administration of pilocarpine, collected hippocampal tissues at different time points after SE, and assessed the relationship between GluA2/GAPDH coupling and neuronal apoptosis in SE rats. Then, we interrupted the GluA2/GAPDH coupling by a special interfering peptide and determined whether neuronal injury can be rescued and hippocampus-depended memory function can be improved. We also evaluated the concentrations of GAPDH in nuclear and cytoplasmatic proteins in SE group, non-SE group and after interruption of GluA2/GAPDH coupling, to verify the nuclear translocation of GAPDH in SE model. We found that the apoptosis of hippocampal neurons was most significant at 72 h after SE, which was also the peak time of GluA2/GAPDH coupling expression and GluA2 consumption. After interruption of GluA2/GAPDH coupling, the apoptosis and memorial function of hippocampal neurons were improved and nuclear translocation of GluA2/GAPDH coupling was reduced. In conclusion, GAPDH can be translocated into nucleus in the form of GluA2/GAPDH, which plays an important role in regulating pilocarpine-induced epilepsy via neurotoxicity pathway.