Soy isoflavone daidzein protects Neuro2a cells from NO stress via activation of AMPK-PGC1α pathway followed by mitochondrial enhancement

Abstract

BackgroundSoy isoflavone daidzein protects cells from oxidative stress. Oxidative stress causes several neurodegenerative diseases via damaging mitochondria and inducing cell death. MethodsIn this study, we analyzed protective mechanisms of daidzein on nitric oxide (NO) induced neuronal Neuro2a cell death, and quantitated mitochondrial amount, that was analyzed by cytometric analysis and western blots of mitochondrial molecules. ResultsDaidzein reduced cell death against NO stress and increased mitochondrial amount even in the presence of NO. Regarding the mechanism of mitochondrial increase, daidzein increased the expression of mitochondrial biogenesis regulator Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) and induced nuclear translocation of PGC1α. Following this, we analyzed if the reduction of PGC1α reduces the protective function of daidzein against oxidative stress. Knockdown of PGC1α abolished the cell-protective function. It strongly suggests that PGC1α activation followed by the mitochondrial increase is critical for the cell protection. Next, we focused on 5′-adenosine monophosphate-activated protein kinase (AMPK) for clarifying how daidzein activates PGC1α. Daidzein increased the expression and phosphorylation of AMPK, indicating that daidzein stimulates AMPK activation. AMPK inhibitor dorsomorphin abolished the cell protection and suppressed the nuclear translocation of PGC1α. Additionally, dorsomorphin prevented the increase of mitochondria by daidzein. ConclusionOur study strongly suggests that daidzein protects Neuro2a cells via AMPK activation followed by PGC1α activation and mitochondrial biogenesis.