title: Arfaptin 2 regulates the aggregation of mutant huntingtin protein.
abstract: Huntington's disease (HD) is an inherited neurodegenerative disorder. Here we demonstrate that expression of arfaptin 2/POR1 (partner of Rac1) in cultured cells induces the formation of pericentriolar and nuclear aggregates, which morphologically resemble mutant huntingtin aggregates characteristic of HD. Endogenous arfaptin 2 localizes to aggregates induced by expression of an abnormal amino-terminal fragment of huntingtin that contains polyglutamine (polyQ) expansions. A dominant inhibitory mutant of arfaptin 2 inhibits aggregation of mutant huntingtin, but not in the presence of proteasome inhibitors. Using cell-free biochemical assays, we show that arfaptin 2 inhibits proteasome activity. Finally, we show that expression of arfaptin 2 is increased at sites of neurodegeneration and the protein localizes to huntingtin aggregates in HD transgenic mouse brains. Our data suggest that arfaptin 2 is involved in regulating huntingtin protein aggregation, possibly by impairing proteasome function.
authors.affiliation: Division of Tumor Biology, Netherlands Cancer Institute, Amsterdam, The Netherlands.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Peters
authors.forename: Ke
authors.initials: K
authors.lastname: Ning
authors.forename: Felipe
authors.initials: F
authors.lastname: Palacios
authors.forename: Rita L
authors.initials: RL
authors.lastname: Boshans
authors.forename: Aleksey
authors.initials: A
authors.lastname: Kazantsev
authors.forename: Leslie M
authors.initials: LM
authors.lastname: Thompson
authors.forename: Ben
authors.initials: B
authors.lastname: Woodman
authors.forename: Gillian P
authors.initials: GP
authors.lastname: Bates
authors.forename: Crislyn
authors.initials: C
authors.lastname: D'Souza-Schorey
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001921:Brain / Q000378:metabolism / Q000473:pathology; D016466:CHO Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D006224:Cricetinae; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D046911:Macromolecular Substances; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008822:Mice, Transgenic; D016253:Microscopy, Immunoelectron; D009154:Mutation; D009410:Nerve Degeneration / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D016716:PC12 Cells; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: C101158:ARFIP2 protein, human; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; C086055:HTT protein, human; C506812:Htt protein, mouse; C499524:Htt protein, rat; D000071058:Huntingtin Protein; D046911:Macromolecular Substances; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins