title: Increased expression of p62 in expanded polyglutamine-expressing cells and its association with polyglutamine inclusions.
abstract: Huntington's disease is a progressive neurodegenerative disorder that is associated with a CAG repeat expansion in the gene encoding huntingtin. We found that a 60-kDa protein was increased in Neuro2a cells expressing the N-terminal portion of huntingtin with expanded polyglutamine. We purified this protein, and, using mass spectrometry, identified it as p62, an ubiquitin-associated domain-containing protein. A specific p62 antibody stained the ubiquitylated polyQ inclusions in expanded polyglutamine-expressing cells, as well as in the brain of the huntingtin exon 1 transgenic mice. Furthermore, the level of p62 protein and mRNA was increased in expanded polyglutamine-expressing cells. We also found that p62 formed aggresome-like inclusions when p62 was increased in normal Neuro2a cells by a proteasome inhibitor. Knock-down of p62 does not affect the formation of aggresomes or polyglutamine inclusions, suggesting that p62 is recruited to the aggresome or inclusions secondary to their formation. These results suggest that p62 may play important roles as a responsive protein to a polyglutamine-induced stress rather than as a cross-linker between ubiquitylated proteins.
authors.affiliation: Laboratory for Structural Neuropathology, RIKEN Brain Science Institute, Wako-shi, Saitama, Japan.
authors.forename: Utako
authors.initials: U
authors.lastname: Nagaoka
authors.forename: Ken
authors.initials: K
authors.lastname: Kim
authors.forename: Nihar Ranjan
authors.initials: NR
authors.lastname: Jana
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Doi
authors.forename: Mieko
authors.initials: M
authors.lastname: Maruyama
authors.forename: Kenichi
authors.initials: K
authors.lastname: Mitsui
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Oyama
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Nukina
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001921:Brain / Q000166:cytology / Q000378:metabolism; D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D002452:Cell Count / Q000379:methods; D002458:Cell Fractionation / Q000379:methods; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004268:DNA-Binding Proteins; D004347:Drug Interactions; D005091:Exons / Q000235:genetics; D005455:Fluorescent Antibody Technique / Q000379:methods; D005786:Gene Expression Regulation / Q000502:physiology*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D000071058:Huntingtin Protein; D015151:Immunoblotting / Q000379:methods; D047468:Immunoprecipitation / Q000379:methods; D002479:Inclusion Bodies / Q000737:chemistry / Q000378:metabolism*; D007211:Indoles / Q000378:metabolism; D007976:Leupeptins / Q000494:pharmacology; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D051379:Mice; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000235:genetics; D009447:Neuroblastoma; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D015739:Nocodazole / Q000494:pharmacology; D009687:Nuclear Proteins / Q000235:genetics; D010455:Peptides / Q000378:metabolism*; D034622:RNA Interference / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D020539:Sequence Analysis, Protein / Q000379:methods; D013997:Time Factors; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*; D014162:Transfection / Q000379:methods; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; C091732:BCL2-associated athanogene 1 protein; D002352:Carrier Proteins; D015853:Cysteine Proteinase Inhibitors; D004268:DNA-Binding Proteins; C490981:Gtf2h1 protein, mouse; C506812:Htt protein, mouse; D000071058:Huntingtin Protein; D007211:Indoles; D007976:Leupeptins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; D012333:RNA, Messenger; D014157:Transcription Factors; D025801:Ubiquitin; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D051758:Transcription Factor TFIIH; C097188:polyglutamine; C007293:DAPI; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D015739:Nocodazole