Abstract
Oxidative stress is a well-established event in the pathology of several neurobiological diseases. Sirt3 is a nicotinamide adenine nucleotide (NAD+)-dependent protein deacetylase that regulates mitochondrial function and metabolism in response to caloric restriction and stress. This study aims to investigate the role of Sirt3 in H2O2 induced oxidative neuronal injury in primary cultured rat cortical neurons. We found that H2O2 treatment significantly increased the expression of Sirt3 in a time-dependent manner at both mRNA and protein levels. Knockdown of Sirt3 with a specific small interfering RNA (siRNA) exacerbated H2O2-induced neuronal injury, whereas overexpression of Sirt3 by lentivirus transfection inhibited H2O2-induced neuronal damage reduced the generation of reactive oxygen species (ROS), and increased the activities of endogenous antioxidant enzymes. In addition, the intra-mitochondrial Ca2+ overload, but not cytosolic Ca2+ increase after H2O2 treatment, was strongly attenuated after Sirt3 overexpression. Overexpression of Sirt3 also increased the content of mitochondrial DNA (mtDNA) and the expression of mitochondrial biogenesis related transcription factors. All these results suggest that Sirt3 acts as a prosurvival factor playing an essential role to protect cortical neurons under H2O2 induced oxidative stress, possibly through regulating mitochondrial Ca2+ homeostasis and mitochondrial biogenesis.
Highlights
Reactive oxygen species (ROS), including superoxide, hydroxyl radicals, and peroxides, are a group of molecules generated in the process of oxygen metabolism [1]
The levels of sirt3 mRNA and protein were both significantly increased within 24 h of the start of H2O2 treatment, and peaked at 6 or 12 h, respectively (Figure 1B,C)
The results showed that knockdown of Sirt3 significantly increased the release of cytochrome c from mitochondria into cytoplasma (Figure 2D,E), and further increased the activation of caspase-3 induced by H2O2 (Figure 2F)
Summary
Reactive oxygen species (ROS), including superoxide, hydroxyl radicals, and peroxides, are a group of molecules generated in the process of oxygen metabolism [1]. H2O2 results in cell injury by damaging key cellular molecules, such as DNA and lipids, and by inducing apoptosis, necrosis or autophagy [3,4]. H2O2 and other ROS-induced neuronal damage has been demonstrated to be involved in the etiology of several neurobiological disorders, ranging from acute insults, such as ischemic and traumatic brain injury to chronic neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease [5,6,7,8]. It has become increasingly clear that there are many complex signaling pathways involved in apoptosis after oxidative neuronal injury, including the intrinsic and extrinsic pathways. Several previous studies have demonstrated that many pharmacological agents and mitochondria associated molecules exert protective effects against neuronal injury through preservation of mitochondria function, and this might be an ideal neuroprotective strategy [14,15]
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