title: Mitochondrial function and energy metabolism in neuronal HT22 cells resistant to oxidative stress.
abstract: OBJECTIVE
  The hippocampal cell line HT22 is an excellent model for studying the consequences of endogenous oxidative stress. Extracellular glutamate depletes cellular glutathione by blocking the glutamate/cystine antiporter system xc-. Glutathione depletion induces a well-defined programme of cell death characterized by an increase in reactive oxygen species and mitochondrial dysfunction.
  
  
  METHODS
  We compared the mitochondrial shape, the abundance of mitochondrial complexes and the mitochondrial respiration of HT22 cells, selected based on their resistance to glutamate, with those of the glutamate-sensitive parental cell line.
  
  
  RESULTS
  Glutamate-resistant mitochondria were less fragmented and displayed seemingly contradictory features: mitochondrial calcium and superoxide were increased while high-resolution respirometry suggested a reduction in mitochondrial respiration. This was interpreted as a reverse activity of the ATP synthase under oxidative stress, leading to hydrolysis of ATP to maintain or even elevate the mitochondrial membrane potential, suggesting these cells endure ineffective energy metabolism to protect their membrane potential. Glutamate-resistant cells were also resistant to oligomycin, an inhibitor of the ATP synthase, but sensitive to deoxyglucose, an inhibitor of hexokinases. Exchanging glucose with galactose rendered resistant cells 1000-fold more sensitive to oligomycin. These results, together with a strong increase in cytosolic hexokinase 1 and 2, a reduced lactate production and an increased activity of glucose-6-phosphate dehydrogenase, suggest that glutamate-resistant HT22 cells shuttle most available glucose towards the hexose monophosphate shunt to increase glutathione recovery.
  
  
  CONCLUSIONS
  These results indicate that mitochondrial and metabolic adaptations play an important role in the resistance of cells to oxidative stress.
authors: Department of Neurology, University Medical Center and Focus Program Translational Neuroscience (FTN) of the Johannes Gutenberg-University Mainz, Mainz, Germany.
authors: Annika
authors: A
authors: Pfeiffer
authors: Martin
authors: M
authors: Jaeckel
authors: Jan
authors: J
authors: Lewerenz
authors: Rebecca
authors: R
authors: Noack
authors: Alireza
authors: A
authors: Pouya
authors: Teresa
authors: T
authors: Schacht
authors: Christina
authors: C
authors: Hoffmann
authors: Jennifer
authors: J
authors: Winter
authors: Susann
authors: S
authors: Schweiger
authors: Michael K E
authors: MK
authors: Schäfer
authors: Axel
authors: A
authors: Methner
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D002452:Cell Count; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D019069:Cell Respiration / Q000187:drug effects / Q000502:physiology; D003847:Deoxyglucose / Q000494:pharmacology; D004351:Drug Resistance / Q000502:physiology; D004734:Energy Metabolism / Q000187:drug effects / Q000502:physiology*; D005954:Glucosephosphate Dehydrogenase / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology; D005978:Glutathione / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000503:physiopathology*; D019344:Lactic Acid / Q000378:metabolism; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D046912:Multiprotein Complexes / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*; D009840:Oligomycins / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology*; D010101:Oxygen Consumption / Q000187:drug effects; D013481:Superoxides / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D046912:Multiprotein Complexes; D009840:Oligomycins; D013481:Superoxides; D019344:Lactic Acid; D018698:Glutamic Acid; D003847:Deoxyglucose; D005954:Glucosephosphate Dehydrogenase; C515658:HK1 protein, mouse; D006593:Hexokinase; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D005978:Glutathione; D002118:Calcium
keywords: cell death; fusion/fission; glycolysis; mitochondria; oxidative phosphorylation; oxidative stress