title: Dominant negative effect of polyglutamine expansion perturbs normal function of ataxin-3 in neuronal cells.
abstract: The physiological function of Ataxin-3 (ATXN3), a deubiquitylase (DUB) involved in Machado-Joseph Disease (MJD), remains elusive. In this study, we demonstrate that ATXN3 is required for neuronal differentiation and for normal cell morphology, cytoskeletal organization, proliferation and survival of SH-SY5Y and PC12 cells. This cellular phenotype is associated with increased proteasomal degradation of α5 integrin subunit (ITGA5) and reduced activation of integrin signalling and is rescued by ITGA5 overexpression. Interestingly, silencing of ATXN3, overexpression of mutant versions of ATXN3 lacking catalytic activity or bearing an expanded polyglutamine (polyQ) tract led to partially overlapping phenotypes. In vivo analysis showed that both Atxn3 knockout and MJD transgenic mice had decreased levels of ITGA5 in the brain. Furthermore, abnormal morphology and reduced branching were observed both in cultured neurons expressing shRNA for ATXN3 and in those obtained from MJD mice. Our results show that ATXN3 rescues ITGA5 from proteasomal degradation in neurons and that polyQ expansion causes a partial loss of this cellular function, resulting in reduced integrin signalling and neuronal cytoskeleton modifications, which may be contributing to neurodegeneration.
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and.
authors.forename: Andreia
authors.initials: A
authors.lastname: Neves-Carvalho
authors.affiliation: Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal.
authors.forename: Elsa
authors.initials: E
authors.lastname: Logarinho
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and.
authors.forename: Ana
authors.initials: A
authors.lastname: Freitas
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and.
authors.forename: Sara
authors.initials: S
authors.lastname: Duarte-Silva
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI, USA and.
authors.forename: Maria do Carmo
authors.initials: Mdo C
authors.lastname: Costa
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and.
authors.forename: Anabela
authors.initials: A
authors.lastname: Silva-Fernandes
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and.
authors.forename: Margarida
authors.initials: M
authors.lastname: Martins
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and.
authors.forename: Sofia Cravino
authors.initials: SC
authors.lastname: Serra
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and.
authors.forename: André T
authors.initials: AT
authors.lastname: Lopes
authors.affiliation: Department of Neurology, University of Michigan, Ann Arbor, MI, USA and.
authors.forename: Henry L
authors.initials: HL
authors.lastname: Paulson
authors.affiliation: German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Heutink
authors.affiliation: Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal.
authors.forename: João B
authors.initials: JB
authors.lastname: Relvas
authors.affiliation: Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, 4710-057 Braga ICVS/3B's-PT Government Associate Laboratory, Braga/Guimarães and pmaciel@ecsaude.uminho.pt.
authors.forename: Patrícia
authors.initials: P
authors.lastname: Maciel
mesh_terms: D000818:Animals; D000067699:Ataxin-3; D002454:Cell Differentiation; D002478:Cells, Cultured; D005727:Ganglia, Spinal / Q000166:cytology / Q000378:metabolism; D057809:HEK293 Cells; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D006801:Humans; D039482:Integrin alpha5 / Q000378:metabolism; D051379:Mice; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D016716:PC12 Cells; D010455:Peptides / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D039482:Integrin alpha5; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D010455:Peptides; D012097:Repressor Proteins; D014157:Transcription Factors; C097188:polyglutamine; C092341:ATXN3 protein, human; D000067699:Ataxin-3; C511594:Atxn3 protein, mouse; C511593:Atxn3 protein, rat; D046988:Proteasome Endopeptidase Complex