Role of glutathione in intracellular amyloid-alpha precursor protein/carboxy-terminal fragment aggregation and associated cytotoxicity.
Abstract Alterations in glutathione (GSH) metabolism are associated with neurodegeneration in Alzheimer's disease (AD), and GSH depletion follows application of exogenous fibrillar amyloid beta (Abeta) peptides in experimental systems; these results are commonly cited as evidence of oxidative damage in AD. We used MC65 human neuroblastoma cells that conditionally express carboxy-terminal fragments of the Abeta precursor protein (Abeta/CTFs) to directly test the hypothesis that GSH is part of the cellular response to stressors associated with Abeta/CTF accumulation and not simply a marker of oxidative damage. Our data showed that Abeta/CTFs accumulated by post-translational processes and were associated with progressive increases in oxidative damage and cytotoxicity. Ethycrinic acid (EA) or diethyl maleate (DEM), reagents that deplete GSH through non-specific thiol adduction, gave rise to dose-dependent cytotoxicity that was independent of Abeta/CTF expression and minimally responsive to alpha-tocopherol (AT). In contrast, buthionine sulfoximine (BSO), a selective inhibitor of GSH synthase, not only augmented Abeta/CTF-associated cell death but unexpectedly potentiated Abeta/CTF accumulation; both outcomes were completely suppressed by AT. These data suggest that antioxidants may serve as 'Abeta targeting' therapies that suppress toxic protein aggregation rather than simply acting as downstream radical scavengers.
Woltjer
Randall L
RL
Department of Pathology, University of Washington, Seattle, 98104, USA. rwoltjer@u.washington.edu
Nghiem
William
W
Maezawa
Izumi
I
Milatovic
Dejan
D
Vaisar
Tomas
T
Montine
Kathleen S
KS
Montine
Thomas J
TJ
D016564:Amyloid beta-Protein Precursor / Q000737:chemistry / Q000378:metabolism*; D000704:Analysis of Variance; D000975:Antioxidants / Q000494:pharmacology; D015153:Blotting, Western / Q000379:methods; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism*; D028441:F2-Isoprostanes / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000502:physiology; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D009447:Neuroblastoma; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013752:Tetracycline / Q000494:pharmacology; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D024505:Tocopherols; D024502:alpha-Tocopherol / Q000031:analogs & derivatives* / Q000494:pharmacology
D016564:Amyloid beta-Protein Precursor; D000975:Antioxidants; D004791:Enzyme Inhibitors; D028441:F2-Isoprostanes; D010446:Peptide Fragments; D011500:Protein Synthesis Inhibitors; D013778:Tetrazolium Salts; D013844:Thiazoles; D019328:Buthionine Sulfoximine; C022616:thiazolyl blue; D013752:Tetracycline; D005978:Glutathione; D024502:alpha-Tocopherol; D024505:Tocopherols