title: Cell cycle arrest enhances the in vitro cellular toxicity of the truncated Machado-Joseph disease gene product with an expanded polyglutamine stretch.
abstract: Machado-Joseph disease (MJD) is an inherited neurodegenerative disorder caused by the expansion of the polyglutamine stretch in the MJD gene-encoded protein, ataxin-3. Using a series of deletion constructs expressing ataxin-3 fragments with expanded polyglutamine stretches, we observed aggregate formation and cell death in cultured BHK-21 cells. The cytotoxic effect of N-terminal-truncated ataxin-3 with the expanded polyglutamine tract was enhanced under serum starvation culture, in which cells were arrested in the G(0)/G(1)phase. Coexpression of p21 (waf1/cip1/sdi1), a cyclin-Cdk inhibitor that induced cell cycle arrest in the G(1)phase, also increased the cell death susceptibility produced by the mutant ataxin-3 fragment in BHK-21 cells. The elevated susceptibility to cell death in the G(0)/G(1)phase was confirmed in nerve growth factor-treated, postmitotic neuronal PC12 cells compared with undifferentiated proliferating PC12 cells. These results strongly suggest that the cellular toxicity of truncated ataxin-3 with an expanded polyglutamine stretch is enhanced by cell cycle arrest in the G(0)/G(1)phase. Mutant ataxin-3 may confer a higher susceptibility to cell death on cells in the G(0)/G(1)phase.
authors.affiliation: Department of Neurology, Institute of Clinical Medicine, University of Tsukuba, Tsukuba 305-8575, Japan. toshi-yo@md.tsukuba.ac.jp
authors.forename: T
authors.initials: T
authors.lastname: Yoshizawa
authors.forename: Y
authors.initials: Y
authors.lastname: Yamagishi
authors.forename: N
authors.initials: N
authors.lastname: Koseki
authors.forename: J
authors.initials: J
authors.lastname: Goto
authors.forename: H
authors.initials: H
authors.lastname: Yoshida
authors.forename: F
authors.initials: F
authors.lastname: Shibasaki
authors.forename: S
authors.initials: S
authors.lastname: Shoji
authors.forename: I
authors.initials: I
authors.lastname: Kanazawa
mesh_terms: D000818:Animals; D000067699:Ataxin-3; D001483:Base Sequence; D002453:Cell Cycle / Q000235:genetics*; D016923:Cell Death / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D006224:Cricetinae; D016895:Culture Media, Serum-Free; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000378:metabolism; D006801:Humans; D017827:Machado-Joseph Disease / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D020932:Nerve Growth Factor / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D009687:Nuclear Proteins; D010455:Peptides / Q000235:genetics; D010673:Pheochromocytoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins
chemical_list: C493956:CDKN1A protein, human; D016895:Culture Media, Serum-Free; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; D011994:Recombinant Proteins; D012097:Repressor Proteins; C097188:polyglutamine; D020932:Nerve Growth Factor; C092341:ATXN3 protein, human; D000067699:Ataxin-3