Rapid activation of heat shock factor-1 DNA binding by H2O2 and modulation by glutathione in human neuroblastoma and Alzheimer's disease cybrid cells.
Because cellular signaling systems are critical mediators of responses to oxidative stress, a condition associated with neurodegenerative disorders, the redox-dependent regulation of heat shock factor-1 (HSF-1) was investigated in human neuroblastoma SH-SY5Y cells. Exposure of cells to 200 microM H2O2 caused a rapid increase in HSF-1 DNA binding that was evident within 10 min, and caused a robust increase that reached levels 8-fold the basal activity. In comparison, the transcription factors, activator protein-1 (AP-1) and early growth response-1 (EGR-1), were activated more slowly and to a lesser extent. Activation of HSF-1 DNA binding activity was associated with a cytosolic to nuclear translocation of HSF-1 protein, and was detected with concentrations of H2O2 of 100 microM and greater. Intracellular glutathione modulated H2O2-induced HSF-1 DNA binding activity, as depletion of glutathione caused HSF-1 to be activated with lower concentrations of H2O2 (25 microM) and supplementation of glutathione blocked HSF-1 activation by 100 to 400 microM H2O2. Alzheimer's disease (AD) and control cybrid cells (SH-SY5Y cells in which the mitochondria were replaced with platelet mitochondria from AD or matched control subjects) were used to test the effects of the chronic oxidative stress caused by the excessive production of reactive oxygen intermediates (ROIs) in AD cybrids on HSF-1 activity. Basal and maximal (induced by H2O2 in glutathione-depleted cells) HSF-1 DNA binding activity were lower in AD than control cybrids, suggesting that the cells had compensated for excessive ROIs. These results indicate that the activation of HSF-1 is highly sensitive to oxidative stress and is regulated by endogenous antioxidant mechanisms.
Bijur
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Department of Psychiatry and Behavioral Neurobiology, Sparks Center 1057, University of Alabama at Birmingham, Birmingham, AL 35294-0017, USA.
Davis
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Jope
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D000544:Alzheimer Disease; D001932:Brain Neoplasms; D002478:Cells, Cultured; D004247:DNA / Q000187:drug effects / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D005978:Glutathione / Q000378:metabolism* / Q000494:pharmacology; D000076249:Heat Shock Transcription Factors; D006801:Humans; D006822:Hybrid Cells; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D017874:Immediate-Early Proteins; D007700:Kinetics; D009447:Neuroblastoma; D018808:Transcription Factor AP-1 / Q000187:drug effects / Q000378:metabolism; D014157:Transcription Factors / Q000187:drug effects / Q000378:metabolism; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D000076249:Heat Shock Transcription Factors; D017874:Immediate-Early Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D004247:DNA; D006861:Hydrogen Peroxide; D005978:Glutathione