title: Impairment of the ubiquitin-proteasome system by protein aggregation.
abstract: Intracellular deposition of aggregated and ubiquitylated proteins is a prominent cytopathological feature of most neurodegenerative disorders. Whether protein aggregates themselves are pathogenic or are the consequence of an underlying molecular lesion is unclear. Here, we report that protein aggregation directly impaired the function of the ubiquitin-proteasome system. Transient expression of two unrelated aggregation-prone proteins, a huntingtin fragment containing a pathogenic polyglutamine repeat and a folding mutant of cystic fibrosis transmembrane conductance regulator, caused nearly complete inhibition of the ubiquitin-proteasome system. Because of the central role of ubiquitin-dependent proteolysis in regulating fundamental cellular events such as cell division and apoptosis, our data suggest a potential mechanism linking protein aggregation to cellular disregulation and cell death.
authors.affiliation: Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, USA.
authors.forename: N F
authors.initials: NF
authors.lastname: Bence
authors.forename: R M
authors.initials: RM
authors.lastname: Sampat
authors.forename: R R
authors.initials: RR
authors.lastname: Kopito
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000595:Amino Acid Sequence; D016923:Cell Death; D002460:Cell Line; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D016195:G2 Phase; D049452:Green Fluorescent Proteins; D006801:Humans; D000071058:Huntingtin Protein; D002479:Inclusion Bodies / Q000378:metabolism; D007976:Leupeptins / Q000494:pharmacology; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: C505032:CFTR protein, human; D015853:Cysteine Proteinase Inhibitors; C086055:HTT protein, human; D000071058:Huntingtin Protein; D007976:Leupeptins; D008164:Luminescent Proteins; D009097:Multienzyme Complexes; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D014452:Ubiquitins; C063261:acetylleucyl-leucyl-norleucinal; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; C067713:lactacystin; D049452:Green Fluorescent Proteins; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D000111:Acetylcysteine