Abstract
Intracellular protein inclusions in Alzheimer's disease and progressive supranuclear palsy contain UBB+1, a variant ubiquitin. UBB+1 is able block the 26S proteasome in cell lines. Proteasome inhibition by drug action has previously been shown to induce a heat-shock response and render protection against stress. We investigated UBB+1 by developing a stable, conditional expression model in SH-SY5Y human neuroblastoma cells. Induction of UBB+1 expression caused proteasome inhibition as was confirmed by reduced ability to process misfolded canavanyl proteins, accumulation of GFPu, a proteasome substrate, and reduced cleavage of a fluorogenic substrate. We show that expression of UBB+1 induces expression of heat-shock proteins. This priming of the chaperone system in these cells promotes a subsequent resistance to tert-butyl hydroperoxide-mediated oxidative stress. We conclude that although UBB+1-expressing cells have a compromised ubiquitin-proteasome system, they are protected against oxidative stress conditions.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Alzheimer Disease / metabolism*
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Canavanine / pharmacology
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Cell Survival / drug effects
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Enzyme Inhibitors / metabolism
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Enzyme Inhibitors / pharmacology
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Gene Expression Regulation / drug effects
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Gene Expression Regulation / physiology
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Green Fluorescent Proteins
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Heat-Shock Proteins / biosynthesis
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Heat-Shock Proteins / genetics
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Humans
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Luminescent Proteins / genetics
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Luminescent Proteins / metabolism
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Molecular Chaperones / biosynthesis*
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Molecular Chaperones / genetics
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Neuroblastoma / metabolism*
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Neuroblastoma / pathology
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Oxidative Stress / genetics
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Oxidative Stress / physiology
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Peptide Hydrolases / drug effects
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Peptide Hydrolases / metabolism*
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Proteasome Endopeptidase Complex*
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RNA, Messenger / metabolism
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Transfection
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Transgenes
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Tumor Cells, Cultured
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Ubiquitin / genetics
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Ubiquitin / metabolism*
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Ubiquitin / pharmacology
Substances
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Enzyme Inhibitors
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Heat-Shock Proteins
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Luminescent Proteins
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Molecular Chaperones
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RNA, Messenger
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Ubiquitin
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Green Fluorescent Proteins
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Canavanine
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Peptide Hydrolases
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Proteasome Endopeptidase Complex
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ATP dependent 26S protease