title: Alzheimer's associated variant ubiquitin causes inhibition of the 26S proteasome and chaperone expression.
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.
authors.affiliation: Reta Lila Weston Institute of Neurological Studies, University College, London, UK. a.hope@ucl.ac.uk
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Hope
authors.forename: Rohan
authors.initials: R
authors.lastname: de Silva
authors.forename: David F
authors.initials: DF
authors.lastname: Fischer
authors.forename: Elly M
authors.initials: EM
authors.lastname: Hol
authors.forename: Fred W
authors.initials: FW
authors.lastname: van Leeuwen
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Lees
mesh_terms: D000544:Alzheimer Disease / Q000378:metabolism*; D002172:Canavanine / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000378:metabolism / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D049452:Green Fluorescent Proteins; D006360:Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018832:Molecular Chaperones / Q000096:biosynthesis* / Q000235:genetics; D009447:Neuroblastoma / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology; D010447:Peptide Hydrolases / Q000187:drug effects / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D012333:RNA, Messenger / Q000378:metabolism; D014162:Transfection; D019076:Transgenes; D014407:Tumor Cells, Cultured; D025801:Ubiquitin / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D006360:Heat-Shock Proteins; D008164:Luminescent Proteins; D018832:Molecular Chaperones; D012333:RNA, Messenger; D025801:Ubiquitin; D049452:Green Fluorescent Proteins; D002172:Canavanine; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease