We previously demonstrated that
Pre-B-cell colony-enhancing factor (PBEF), also known as
nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting
enzyme in mammalian
NAD(+) biosynthesis pathway, plays a brain and neuronal protective role in
ischemic stroke. In this study, we further investigated the mechanism of its
neuroprotective effect after
ischemia in the primary cultured mouse cortical neurons. Using apoptotic cell death assay, fluorescent imaging, molecular biology, mitochondrial biogenesis measurements and Western blotting analysis, our results show that the overexpression of PBEF in neurons can significantly promote neuronal survival, reduce the translocation of
apoptosis inducing factor (AIF) from mitochondria to nuclei and inhibit the activation of capase-3 after
glutamate-induced excitotoxicity. We further found that the overexpression of PBEF can suppress
glutamate-induced mitochondrial fragmentation, the loss of
mitochondrial DNA (
mtDNA) content and the reduction of PGC-1 and NRF-1 expressions. Furthermore, these beneficial effects by PBEF are dependent on its enzymatic activity of
NAD(+) synthesis. In summary, our study demonstrated that PBEF ameliorates
ischemia-induced neuronal death through inhibiting
caspase-dependent and independent apoptotic signaling pathways and suppressing mitochondrial damage and dysfunction. Our study provides novel insights into the mechanisms underlying the
neuroprotective effect of PBEF, and helps to identify potential targets for
ischemic stroke therapy.