SIRT1 Overexpression Together with EX527 Reduce Excitotoxicity-Induced Neuronal Loss in Cortical Neurons

Abstract

Silent information regulator 1 (SIRT1) is a NAD+-dependent histone deacetylase that represses gene expression, regulates metabolism, prevents apoptosis and mitigates aging. SIRT1 beneficial effect in neurodegenerative diseases has been widely described, however a protective role in brain ischemia is still questionable. Here, we studied the SIRT1 expression pattern after exposure to NMDA, which receptor is highly activated after ischemia, and the effect of SIRT1 modulation, using lentiviral vectors and pharmacological strategies, on NMDA toxicity in mouse cortical neurons. We observed that SIRT1 levels decline in the cytoplasm, but not in the nucleus from 2h after NMDA addition. Therefore, we transduced neurons with lentiviral vectors that overexpress wt SIRT1 (SIRT1) or a mutant form of the protein with a deletion in the N-terminal sequence (ΔSIRT1). wt SIRT1 that is predominantly expressed in the nucleus and ΔSIRT1 that accumulates in the cytoplasm and the nucleus were not protective against NMDA lesion. However, the combination of increased wt SIRT1 with Ex527, a specific inhibitor of SIRT1 enzymatic activity, reduced neuronal loss. We are currently investigating the mechanisms underlying the protective effect of this treatment