Mitochondrial superoxide dismutase SOD2, but not cytosolic SOD1, plays a critical role in protection against glutamate-induced oxidative stress and cell death in HT22 neuronal cells

• Published in: Free radical biology & medicine Vol. 48; no. 6; pp. 821 - 830
• Main Authors: Fukui, Masayuki, Zhu, Bao Ting
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15.03.2010
• Subjects: Animals; Cell Death - drug effects; Cells, Cultured; Free radicals; Glutamate; Glutamic Acid - toxicity; HT22; Mice; Mitochondria - enzymology; Neuronal cell death; Neurons - drug effects; Neurons - enzymology; Neurons - metabolism; Oxidative stress; Oxidative Stress - drug effects; SOD2; Superoxide Dismutase - metabolism; Oxidative stress; Free radicals; Neuronal cell death; SOD; siRNA; HO-1; Glutamate; SOD2; HT22; GFP; MMP; shRNA; ROS; GSH; TEM
• ISSN: 0891-5849; 1873-4596
• DOI: 10.1016/j.freeradbiomed.2009.12.024

Oxidative cell death is an important contributing factor in neurodegenerative diseases. Using HT22 mouse hippocampal neuronal cells as a model, we sought to demonstrate that mitochondria are crucial early targets of glutamate-induced oxidative cell death. We show that when HT22 cells were transfected with shRNA for knockdown of the mitochondrial superoxide dismutase (SOD2), these cells became more susceptible to glutamate-induced oxidative cell death. The increased susceptibility was accompanied by increased accumulation of mitochondrial superoxide and loss of normal mitochondrial morphology and function at early time points after glutamate exposure. However, overexpression of SOD2 in these cells reduced the mitochondrial superoxide level, protected mitochondrial morphology and functions, and provided resistance against glutamate-induced oxidative cytotoxicity. The change in the sensitivity of these SOD2-altered HT22 cells was neurotoxicant-specific, because the cytotoxicity of hydrogen peroxide was not altered in these cells. In addition, selective knockdown of the cytosolic SOD1 in cultured HT22 cells did not appreciably alter their susceptibility to either glutamate or hydrogen peroxide. These findings show that the mitochondrial SOD2 plays a critical role in protecting neuronal cells from glutamate-induced oxidative stress and cytotoxicity. These data also indicate that mitochondria are important early targets of glutamate-induced oxidative neurotoxicity.