title: Association of Bcl-2 with misfolded prion protein is linked to the toxic potential of cytosolic PrP.
abstract: Protein misfolding is linked to different neurodegenerative disorders like Alzheimer's disease, polyglutamine, and prion diseases. We investigated the cytotoxic effects of aberrant conformers of the prion protein (PrP) and show that toxicity is specifically linked to misfolding of PrP in the cytosolic compartment and involves binding of PrP to the anti-apoptotic protein Bcl-2. PrP targeted to different cellular compartments, including the cytosol, nucleus, and mitochondria, adopted a misfolded and partially proteinase K-resistant conformation. However, only in the cytosol did the accumulation of misfolded PrP induce apoptosis. Apoptotic cell death was also induced by two pathogenic mutants of PrP, which are partially localized in the cytosol. A mechanistic analysis revealed that the toxic potential is linked to an internal domain of PrP (amino acids 115-156) and involves coaggregation of cytosolic PrP with Bcl-2. Increased expression of the chaperones Hsp70 and Hsp40 prevented the formation of PrP/Bcl-2 coaggregates and interfered with PrP-induced apoptosis. Our study reveals a compartment-specific toxicity of PrP misfolding that involves coaggregation of Bcl-2 and indicates a protective role of molecular chaperones.
authors.affiliation: Department of Biochemistry, Neurobiochemistry, Ludwig-Maximilians-Universität München, D-80336 München, Germany.
authors.forename: Angelika S
authors.initials: AS
authors.lastname: Rambold
authors.forename: Margit
authors.initials: M
authors.lastname: Miesbauer
authors.forename: Doron
authors.initials: D
authors.lastname: Rapaport
authors.forename: Till
authors.initials: T
authors.lastname: Bartke
authors.forename: Michael
authors.initials: M
authors.lastname: Baier
authors.forename: Konstanze F
authors.initials: KF
authors.lastname: Winklhofer
authors.forename: Jörg
authors.initials: J
authors.lastname: Tatzelt
mesh_terms: D000818:Animals; D017209:Apoptosis; D002451:Cell Compartmentation; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D051379:Mice; D008810:Mice, Inbred C57BL; D018832:Molecular Chaperones / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D018621:PrPC Proteins / Q000737:chemistry* / Q000378:metabolism*; D017096:Prion Diseases / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D017433:Protein Structure, Secondary; D021381:Protein Transport; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*
chemical_list: D018832:Molecular Chaperones; D018621:PrPC Proteins; D019253:Proto-Oncogene Proteins c-bcl-2