title: Cellular prion protein inhibits proapoptotic Bax conformational change in human neurons and in breast carcinoma MCF-7 cells.
abstract: Prion protein (PrP) prevents Bcl-2-associated protein X (Bax)-mediated cell death, but the step at which PrP inhibits is not known. We first show that PrP is very specific for Bax and cannot prevent Bak (Bcl-2 antagonist killer 1)-, tBid-, staurosporine- or thapsigargin-mediated cell death. As Bax activation involves Bax conformational change, mitochondrial translocation, cytochrome c release and caspase activation, we investigated which of these events was inhibited by PrP. PrP inhibits Bax conformational change, cytochrome c release and cell death in human primary neurons and MCF-7 cells. Serum deprivation-induced Bax conformational change is more rapid in PrP-null cells. PrP does not prevent active caspase-mediated cell death. PrP does not colocalize with Bax in normal or apoptotic primary neurons and cannot prevent Bax-mediated cytochrome c release in a mitochondrial cell-free system. We conclude that PrP protects against Bax-mediated cell death by preventing the Bax proapoptotic conformational change that occurs initially in Bax activation.
authors.affiliation: The Bloomfield Center for Research in Aging, Lady Davis Institute for Medical Research, The Sir Mortimer B Davis Jewish General Hospital, Montréal, Québec, Canada.
authors.forename: X
authors.initials: X
authors.lastname: Roucou
authors.forename: P N
authors.initials: PN
authors.lastname: Giannopoulos
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Jodoin
authors.forename: C G
authors.initials: CG
authors.lastname: Goodyer
authors.forename: A
authors.initials: A
authors.lastname: LeBlanc
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D051023:BH3 Interacting Domain Death Agonist Protein; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D002352:Carrier Proteins / Q000378:metabolism; D053178:Caspase 6; D045744:Cell Line, Tumor; D003546:Cysteine Endopeptidases / Q000378:metabolism; D045304:Cytochromes c / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D018621:PrPC Proteins / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D021381:Protein Transport / Q000187:drug effects; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D019284:Thapsigargin / Q000494:pharmacology; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein
chemical_list: C494772:BAK1 protein, human; C494826:BAX protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D002352:Carrier Proteins; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D018621:PrPC Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D050998:bcl-2 Homologous Antagonist-Killer Protein; D051028:bcl-2-Associated X Protein; D019284:Thapsigargin; D045304:Cytochromes c; C505514:CASP6 protein, human; D053178:Caspase 6; D003546:Cysteine Endopeptidases