Neuroglobin overexpression in cultured human neuronal cells protects against hydrogen peroxide insult via activating phosphoinositide-3 kinase and opening the mitochondrial K(ATP) channel.
Cultured neurons tolerate low H(2)O(2) concentrations (< or =50 microM) through the activity of constitutive antioxidant response elements (ARE). At H(2)O(2) levels (> or =100 microM), neurons increase expression of the gene encoding for inducible hemoxygenase-1 while superoxide dismutase-2 and catalase remain unchanged. Despite this adaptive response, the endogenous antioxidant systems are overwhelmed, leading to decreased viability. Elevating the neuronal cell content of human neuroglobin (Ngb) prior to insult with 100 or 200 microM H(2)O(2) enhanced cell viability and this resulted in a significant decrease in oxidative stress and an increase in the intracellular ATP concentration, whereas in parental cells exposed to the same H(2)O(2)-insult, oxidative stress and ATP increased and decreased, respectively. The mechanism for this increase in ATP involves sustained activation of the mito-K(ATP) channel and an increase in phosphoinositide-3 kinase (PI3K)-mediated phosphorylation of Akt. Pharmacological inhibitors directed toward PI3K (wortmannin and LY294002), or the mito-K(ATP) channel (glybenclamide) inhibited the H(2)O(2)-mediated increase in ATP in cells overexpressing human Ngb and consequently cell viability decreased. Neuroglobin's ability to bolster the intracellular pool of ATP in response to added H(2)O(2) is central to the preservation of cytoskeletal integrity and cell viability.
Antao
Shane T
ST
Redox Biology Group, Discipline of Pathology, Bosch Institute, Faculty of Medicine, The University of Sydney, Sydney, Australia.
Duong
T T Hong
TT
Aran
Roshanak
R
Witting
Paul K
PK
D000255:Adenosine Triphosphate / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D005914:Globins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D015640:Ion Channel Gating / Q000187:drug effects*; D054086:KATP Channels / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D000078787:Neuroglobin; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*
D054086:KATP Channels; D009419:Nerve Tissue Proteins; D000078787:Neuroglobin; D000255:Adenosine Triphosphate; D005914:Globins; D006861:Hydrogen Peroxide; D019869:Phosphatidylinositol 3-Kinases