Neuronal Sirt3 protects against excitotoxic injury in mouse cortical neuron culture

• Published in: PloS one Vol. 6; no. 3; p. e14731
• Main Authors: Kim, Sun Hee, Lu, Hua Fei, Alano, Conrad C
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.03.2011; Public Library of Science (PLoS)
• Subjects: Adenine; Adenosine diphosphate; Alzheimer's disease; Alzheimers disease; Animals; Apoptosis; Cell Biology/Cellular Death and Stress Responses; Cell Biology/Neuronal Signaling Mechanisms; Cell culture; Cell death; Cell Death - drug effects; Cell survival; Cell Survival - drug effects; Cells, Cultured; Cerebral Cortex - pathology; Cortex; Cytoprotection - drug effects; Energy metabolism; Enzyme Activation - drug effects; Enzymes; Excitation; Excitotoxicity; Genes; Injuries; Isoforms; Life span; Metabolism; Mice; Mice, Inbred C57BL; Mitochondria; Mitochondria - drug effects; Mitochondria - metabolism; Monosaccharides; N-Methyl-D-aspartic acid; N-Methylaspartate - pharmacology; NAD; NAD - deficiency; NAD - pharmacology; Neurology; Neurons; Neurons - drug effects; Neurons - metabolism; Neurons - pathology; Neuroprotection; Neuroscience; Neuroscience/Neuronal and Glial Cell Biology; Neuroscience/Neuronal Signaling Mechanisms; Neurotoxins - toxicity; Niacinamide; Nicotinamide; Oxidation; Oxidative stress; Oxidative Stress - drug effects; Oxygen; Permeability; Physiological aspects; Plasmids; Poly(ADP-ribose) polymerase; Poly(ADP-ribose) Polymerase 1; Poly(ADP-ribose) Polymerases - metabolism; Polymerase; Proteins; Purines; Reactive oxygen species; Ribose; Rodents; siRNA; SIRT1 protein; Sirtuin 3 - metabolism; Sirtuins; Stress; Studies; Veterans; United States > US; San Francisco California; California
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0014731

Sirtuins (Sirt), a family of nicotinamide adenine nucleotide (NAD) dependent deacetylases, are implicated in energy metabolism and life span. Among the known Sirt isoforms (Sirt1-7), Sirt3 was identified as a stress responsive deacetylase recently shown to play a role in protecting cells under stress conditions. Here, we demonstrated the presence of Sirt3 in neurons, and characterized the role of Sirt3 in neuron survival under NMDA-induced excitotoxicity. To induce excitotoxic injury, we exposed primary cultured mouse cortical neurons to NMDA (30 µM). NMDA induced a rapid decrease of cytoplasmic NAD (but not mitochondrial NAD) in neurons through poly (ADP-ribose) polymerase-1 (PARP-1) activation. Mitochondrial Sirt3 was increased following PARP-1 mediated NAD depletion, which was reversed by either inhibition of PARP-1 or exogenous NAD. We found that massive reactive oxygen species (ROS) produced under this NAD depleted condition mediated the increase in mitochondrial Sirt3. By transfecting primary neurons with a Sirt3 overexpressing plasmid or Sirt3 siRNA, we showed that Sirt3 is required for neuroprotection against excitotoxicity. This study demonstrated for the first time that mitochondrial Sirt3 acts as a prosurvival factor playing an essential role to protect neurons under excitotoxic injury.