1
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Garcia DM, Campbell EA, Jakobson CM, Tsuchiya M, Shaw EA, DiNardo AL, Kaeberlein M, Jarosz DF. A prion accelerates proliferation at the expense of lifespan. eLife 2021; 10:e60917. [PMID: 34545808 PMCID: PMC8455135 DOI: 10.7554/elife.60917] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Accepted: 08/12/2021] [Indexed: 12/23/2022] Open
Abstract
In fluctuating environments, switching between different growth strategies, such as those affecting cell size and proliferation, can be advantageous to an organism. Trade-offs arise, however. Mechanisms that aberrantly increase cell size or proliferation-such as mutations or chemicals that interfere with growth regulatory pathways-can also shorten lifespan. Here we report a natural example of how the interplay between growth and lifespan can be epigenetically controlled. We find that a highly conserved RNA-modifying enzyme, the pseudouridine synthase Pus4/TruB, can act as a prion, endowing yeast with greater proliferation rates at the cost of a shortened lifespan. Cells harboring the prion grow larger and exhibit altered protein synthesis. This epigenetic state, [BIG+] (better in growth), allows cells to heritably yet reversibly alter their translational program, leading to the differential synthesis of dozens of proteins, including many that regulate proliferation and aging. Our data reveal a new role for prion-based control of an RNA-modifying enzyme in driving heritable epigenetic states that transform cell growth and survival.
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Affiliation(s)
- David M Garcia
- Department of Chemical & Systems Biology, Stanford University School of Medicine, Stanford, United States
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, United States
| | - Edgar A Campbell
- Department of Chemical & Systems Biology, Stanford University School of Medicine, Stanford, United States
| | - Christopher M Jakobson
- Department of Chemical & Systems Biology, Stanford University School of Medicine, Stanford, United States
| | - Mitsuhiro Tsuchiya
- Department of Pathology, University of Washington, Seattle, United States
| | - Ethan A Shaw
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, United States
| | - Acadia L DiNardo
- Institute of Molecular Biology, Department of Biology, University of Oregon, Eugene, United States
| | - Matt Kaeberlein
- Department of Pathology, University of Washington, Seattle, United States
| | - Daniel F Jarosz
- Department of Chemical & Systems Biology, Stanford University School of Medicine, Stanford, United States
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, United States
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2
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Kabani M. Extracellular Vesicles and the Propagation of Yeast Prions. Curr Top Microbiol Immunol 2021; 432:57-66. [DOI: 10.1007/978-3-030-83391-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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3
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Extracellular Vesicles-Encapsulated Yeast Prions and What They Can Tell Us about the Physical Nature of Propagons. Int J Mol Sci 2020; 22:ijms22010090. [PMID: 33374854 PMCID: PMC7794690 DOI: 10.3390/ijms22010090] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 12/14/2020] [Accepted: 12/20/2020] [Indexed: 12/25/2022] Open
Abstract
The yeast Saccharomyces cerevisiae hosts an ensemble of protein-based heritable traits, most of which result from the conversion of structurally and functionally diverse cytoplasmic proteins into prion forms. Among these, [PSI+], [URE3] and [PIN+] are the most well-documented prions and arise from the assembly of Sup35p, Ure2p and Rnq1p, respectively, into insoluble fibrillar assemblies. Yeast prions propagate by molecular chaperone-mediated fragmentation of these aggregates, which generates small self-templating seeds, or propagons. The exact molecular nature of propagons and how they are faithfully transmitted from mother to daughter cells despite spatial protein quality control are not fully understood. In [PSI+] cells, Sup35p forms detergent-resistant assemblies detectable on agarose gels under semi-denaturant conditions and cytosolic fluorescent puncta when the protein is fused to green fluorescent protein (GFP); yet, these macroscopic manifestations of [PSI+] do not fully correlate with the infectivity measured during growth by the mean of protein infection assays. We also discovered that significant amounts of infectious Sup35p particles are exported via extracellular (EV) and periplasmic (PV) vesicles in a growth phase and glucose-dependent manner. In the present review, I discuss how these vesicles may be a source of actual propagons and a suitable vehicle for their transmission to the bud.
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4
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Bousset L, Luckgei N, Kabani M, Gardiennet C, Schütz AK, Melki R, Meier BH, Böckmann A. Prion Amyloid Polymorphs - The Tag Might Change It All. Front Mol Biosci 2020; 7:190. [PMID: 32850974 PMCID: PMC7423878 DOI: 10.3389/fmolb.2020.00190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/20/2020] [Indexed: 11/13/2022] Open
Abstract
Sup35p is a protein from Saccharomyces cerevisiae. It can propagate using a prion-like mechanism, which means that it can recruit non-prion soluble Sup35p into insoluble fibrils. Sup35p is a large protein showing three distinct domains, N, M and an extended globular domain. We have previously studied the conformations of the full-length and truncated NM versions carrying poly-histidine tags on the N-terminus. Comparison with structural data from C-terminally poly-histidine tagged NM from the literature surprisingly revealed discrepancies. Here we investigated fibrils from the untagged, as well as a C-terminally poly-histidine tagged NM construct, using solid-state NMR. We find that the conformation of untagged NM is very close to the N-terminally tagged NM and confirms our previous findings. The C-terminal poly-histidine tag, in contrast, drastically changes the NM fibril structure, and yields data consistent with results obtained previously on this construct. We conclude that the C-terminally located Sup35p globular domain influences the structure of the fibrillar core at the N domain, as previously shown. We further conclude, based on the present data, that small tags on NM C-terminus have a substantial, despite different, impact. Modifications at this remote localization thus shows an unexpected influence on the fibril structure, and importantly also its propensity to induce [PSI+].
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Affiliation(s)
- Luc Bousset
- Institut Francois Jacob (MIRCen), CEA and Laboratory of Neurodegenerative Diseases, CNRS, Fontenay-aux-Roses, France
| | - Nina Luckgei
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS, Universite de Lyon, Lyon, France
| | - Mehdi Kabani
- Institut Francois Jacob (MIRCen), CEA and Laboratory of Neurodegenerative Diseases, CNRS, Fontenay-aux-Roses, France
| | - Carole Gardiennet
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS, Universite de Lyon, Lyon, France
| | - Anne K Schütz
- ETH Zürich, Laboratory of Physical Chemistry, Zurich, Switzerland
| | - Ronald Melki
- Institut Francois Jacob (MIRCen), CEA and Laboratory of Neurodegenerative Diseases, CNRS, Fontenay-aux-Roses, France
| | - Beat H Meier
- ETH Zürich, Laboratory of Physical Chemistry, Zurich, Switzerland
| | - Anja Böckmann
- Molecular Microbiology and Structural Biochemistry, UMR 5086 CNRS, Universite de Lyon, Lyon, France
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5
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Kabani M, Pilard M, Melki R. Glucose availability dictates the export of the soluble and prion forms of Sup35p via periplasmic or extracellular vesicles. Mol Microbiol 2020; 114:322-332. [PMID: 32339313 DOI: 10.1111/mmi.14515] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/25/2020] [Accepted: 04/06/2020] [Indexed: 11/28/2022]
Abstract
The yeast [PSI+ ] prion originates from the self-perpetuating transmissible aggregates of the translation termination factor Sup35p. We previously showed that infectious Sup35p particles are exported outside the cells via extracellular vesicles (EV). This finding suggested a function for EV in the vertical and horizontal transmission of yeast prions. Here we report a significant export of Sup35p within periplasmic vesicles (PV) upon glucose starvation. We show that PV are up to three orders of magnitude more abundant than EV. However, PV and EV are different in terms of size and protein content, and their export is oppositely regulated by glucose availability in the growth medium. Overall, our work suggests that the export of prion particles to both the periplasm and the extracellular space needs to be considered to address the physiological consequences of vesicle-mediated yeast prions trafficking.
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Affiliation(s)
- Mehdi Kabani
- Institut de Biologie François Jacob, Molecular Imaging Research Center (MIRCen), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Laboratoire des Maladies Neurodégénératives, Centre National de la Recherche Scientifique (CNRS), Fontenay-aux-Roses, France
| | - Marion Pilard
- Institut de Biologie François Jacob, Molecular Imaging Research Center (MIRCen), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Laboratoire des Maladies Neurodégénératives, Centre National de la Recherche Scientifique (CNRS), Fontenay-aux-Roses, France
| | - Ronald Melki
- Institut de Biologie François Jacob, Molecular Imaging Research Center (MIRCen), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Laboratoire des Maladies Neurodégénératives, Centre National de la Recherche Scientifique (CNRS), Fontenay-aux-Roses, France
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6
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Trubitsina NP, Zemlyanko OM, Bondarev SA, Zhouravleva GA. Nonsense Mutations in the Yeast SUP35 Gene Affect the [ PSI+] Prion Propagation. Int J Mol Sci 2020; 21:E1648. [PMID: 32121268 PMCID: PMC7084296 DOI: 10.3390/ijms21051648] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/20/2020] [Accepted: 02/26/2020] [Indexed: 11/16/2022] Open
Abstract
The essential SUP35 gene encodes yeast translation termination factor eRF3. Previously, we isolated nonsense mutations sup35-n and proposed that the viability of such mutants can be explained by readthrough of the premature stop codon. Such mutations, as well as the prion [PSI+], can appear in natural yeast populations, and their combinations may have different effects on the cells. Here, we analyze the effects of the compatibility of sup35-n mutations with the [PSI+] prion in haploid and diploid cells. We demonstrated that sup35-n mutations are incompatible with the [PSI+] prion, leading to lethality of sup35-n [PSI+] haploid cells. In diploid cells the compatibility of [PSI+] with sup35-n depends on how the corresponding diploid was obtained. Nonsense mutations sup35-21, sup35-74, and sup35-218 are compatible with the [PSI+] prion in diploid strains, but affect [PSI+] properties and lead to the formation of new prion variant. The only mutation that could replace the SUP35 wild-type allele in both haploid and diploid [PSI+] strains, sup35-240, led to the prion loss. Possibly, short Sup351-55 protein, produced from the sup35-240 allele, is included in Sup35 aggregates and destabilize them. Alternatively, single molecules of Sup351-55 can stick to aggregate ends, and thus interrupt the fibril growth. Thus, we can conclude that sup35-240 mutation prevents [PSI+] propagation and can be considered as a new pnm mutation.
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Affiliation(s)
- Nina P. Trubitsina
- Department of Genetics and Biotechnology, Saint Petersburg State University, 199034 St. Petersburg, Russia; (N.P.T.); (O.M.Z.); (S.A.B.)
| | - Olga M. Zemlyanko
- Department of Genetics and Biotechnology, Saint Petersburg State University, 199034 St. Petersburg, Russia; (N.P.T.); (O.M.Z.); (S.A.B.)
- Laboratory of Amyloid Biology, Saint Petersburg State University, 199034 St. Petersburg, Russia
| | - Stanislav A. Bondarev
- Department of Genetics and Biotechnology, Saint Petersburg State University, 199034 St. Petersburg, Russia; (N.P.T.); (O.M.Z.); (S.A.B.)
- Laboratory of Amyloid Biology, Saint Petersburg State University, 199034 St. Petersburg, Russia
| | - Galina A. Zhouravleva
- Department of Genetics and Biotechnology, Saint Petersburg State University, 199034 St. Petersburg, Russia; (N.P.T.); (O.M.Z.); (S.A.B.)
- Laboratory of Amyloid Biology, Saint Petersburg State University, 199034 St. Petersburg, Russia
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7
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Wang K, Melki R, Kabani M. Growth phase‐dependent changes in the size and infectivity of SDS‐resistant Sup35p assemblies associated with the [
PSI
+
] prion in yeast. Mol Microbiol 2019; 112:932-943. [DOI: 10.1111/mmi.14329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/09/2019] [Indexed: 10/26/2022]
Affiliation(s)
| | - Ronald Melki
- Institut de Biologie François Jacob, Molecular Imaging Research Center (MIRCen), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Laboratoire des Maladies Neurodégénératives Centre National de la Recherche Scientifique (CNRS) Paris Fontenay‐aux‐RosesF‐92265France
| | - Mehdi Kabani
- Institut de Biologie François Jacob, Molecular Imaging Research Center (MIRCen), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Direction de la Recherche Fondamentale (DRF), Laboratoire des Maladies Neurodégénératives Centre National de la Recherche Scientifique (CNRS) Paris Fontenay‐aux‐RosesF‐92265France
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8
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Okamoto A, Hosoda N, Hoshino SI. Proteolysis: a double-edged sword for the development of amyloidoses. Prion 2018; 12:1-7. [PMID: 30198379 PMCID: PMC6277189 DOI: 10.1080/19336896.2018.1521234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Revised: 08/17/2018] [Accepted: 08/23/2018] [Indexed: 10/28/2022] Open
Abstract
The yeast Saccharomyces cerevisiae has proven to be a useful model system to investigate the mechanism of prion generation and inheritance, to which studies in Sup35 made a great contribution. Recent studies demonstrated that 'protein misfolding and aggregation' (i.e. amyloidogenesis) is a common principle underlying the pathogenesis of neurodegenerative diseases including prion, amyotrophic lateral sclerosis (ALS), Perkinson's (PD), Alzheimer's (AD) diseases and polyglutamine (polyQ) diseases such as spinocerebellar ataxia (SCA) and Hantington's disease (HD). By these findings, the yeast has again been drawing increased attention as a useful system for studying neurodegenerative proteinopathies. So far, it has been reported that proteolytic cleavage of causative amyloidogenic proteins might affect the pathogenesis of the respective neurodegenerative diseases. Although those reports provide a clear phenomenological description, in the majority of cases, it has remained elusive if proteolysis is directly involved in the pathogenesis of the diseases. Recently, we have demonstrated in yeast that proteolysis suppresses prion generation. The yeast-based strategy might make a breakthrough to the unsolved issues.
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Affiliation(s)
- Atsushi Okamoto
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Nao Hosoda
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
| | - Shin-ichi Hoshino
- Department of Biological Chemistry, Graduate School of Pharmaceutical Sciences, Nagoya City University, Nagoya, Japan
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9
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Wang K, Melki R, Kabani M. A prolonged chronological lifespan is an unexpected benefit of the [PSI+] prion in yeast. PLoS One 2017; 12:e0184905. [PMID: 28910422 PMCID: PMC5599042 DOI: 10.1371/journal.pone.0184905] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/01/2017] [Indexed: 11/19/2022] Open
Abstract
Self-replicating ‘proteinaceous infectious particles’ or prions are responsible for complex heritable traits in the yeast Saccharomyces cerevisiae. Our current understanding of the biology of yeast prions stems from studies mostly done in the context of actively dividing cells in optimal laboratory growth conditions. Evidence suggest that fungal prions exist in the wild where most cells are in a non-dividing quiescent state, because of imperfect growth conditions, scarcity of nutrients and competition. We know little about the faithful transmission of yeast prions in such conditions and their physiological consequences throughout the lifespan of yeast cells. We addressed this issue for the [PSI+] prion that results from the self-assembly of the translation release factor Sup35p into insoluble fibrillar aggregates. [PSI+] leads to increased nonsense suppression and confers phenotypic plasticity in response to environmental fluctuations. Here, we report that while [PSI+] had little to no effect on growth per se, it dramatically improved the survival of yeast cells in stationary phase. Remarkably, prolonged chronological lifespan persisted even after [PSI+] was cured from the cells, suggesting that prions may facilitate the acquisition of complex new traits. Such an important selective advantage may contribute to the evolutionary conservation of the prion-forming ability of Sup35p orthologues in distantly related yeast species.
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Affiliation(s)
- Kai Wang
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Université Paris-Saclay, Gif-sur-Yvette, France
| | - Ronald Melki
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail: (MK); (RM)
| | - Mehdi Kabani
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Université Paris-Saclay, Gif-sur-Yvette, France
- * E-mail: (MK); (RM)
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10
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Chernova TA, Wilkinson KD, Chernoff YO. Prions, Chaperones, and Proteostasis in Yeast. Cold Spring Harb Perspect Biol 2017; 9:cshperspect.a023663. [PMID: 27815300 DOI: 10.1101/cshperspect.a023663] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Prions are alternatively folded, self-perpetuating protein isoforms involved in a variety of biological and pathological processes. Yeast prions are protein-based heritable elements that serve as an excellent experimental system for studying prion biology. The propagation of yeast prions is controlled by the same Hsp104/70/40 chaperone machinery that is involved in the protection of yeast cells against proteotoxic stress. Ribosome-associated chaperones, proteolytic pathways, cellular quality-control compartments, and cytoskeletal networks influence prion formation, maintenance, and toxicity. Environmental stresses lead to asymmetric prion distribution in cell divisions. Chaperones and cytoskeletal proteins mediate this effect. Overall, this is an intimate relationship with the protein quality-control machinery of the cell, which enables prions to be maintained and reproduced. The presence of many of these same mechanisms in higher eukaryotes has implications for the diagnosis and treatment of mammalian amyloid diseases.
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Affiliation(s)
- Tatiana A Chernova
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Keith D Wilkinson
- Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Yury O Chernoff
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia 30332-2000.,Laboratory of Amyloid Biology and Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg 199034, Russia
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11
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Kabani M, Melki R. More than just trash bins? Potential roles for extracellular vesicles in the vertical and horizontal transmission of yeast prions. Curr Genet 2015; 62:265-70. [PMID: 26553335 PMCID: PMC4826420 DOI: 10.1007/s00294-015-0534-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Revised: 10/28/2015] [Accepted: 10/31/2015] [Indexed: 01/05/2023]
Abstract
In the yeast Saccharomyces cerevisiae, an ensemble of structurally and functionally diverse cytoplasmic proteins has the ability to form self-perpetuating protein aggregates (e.g. prions) which are the vectors of heritable non-Mendelian phenotypic traits. Whether harboring these prions is deleterious—akin to mammalian degenerative disorders—or beneficial—as epigenetic modifiers of gene expression—for yeasts has been intensely debated and strong arguments were made in support of both views. We recently reported that the yeast prion protein Sup35p is exported via extracellular vesicles (EV), both in its soluble and aggregated infectious states. Herein, we discuss the possible implications of this observation and propose several hypotheses regarding the roles of EV in both vertical and horizontal propagation of ‘good’ and ‘bad’ yeast prions.
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Affiliation(s)
- Mehdi Kabani
- Centre National de la Recherche Scientifique (CNRS), Paris-Saclay Institute of Neuroscience, Université Paris-Saclay, Bât. 32-33, Avenue de la Terrasse, 91190, Gif-sur-Yvette, France.
| | - Ronald Melki
- Centre National de la Recherche Scientifique (CNRS), Paris-Saclay Institute of Neuroscience, Université Paris-Saclay, Bât. 32-33, Avenue de la Terrasse, 91190, Gif-sur-Yvette, France.
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12
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Speldewinde SH, Doronina VA, Grant CM. Autophagy protects against de novo formation of the [PSI+] prion in yeast. Mol Biol Cell 2015; 26:4541-51. [PMID: 26490118 PMCID: PMC4678013 DOI: 10.1091/mbc.e15-08-0548] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 10/14/2015] [Indexed: 11/11/2022] Open
Abstract
The molecular basis by which prions arise spontaneously is poorly understood. The present data point toward oxidative protein damage as one of the triggers of de novo prion formation. Autophagy functions to clear oxidatively damaged proteins before their conversion to the prion form. Prions are self-propagating, infectious proteins that underlie several neurodegenerative diseases. The molecular basis underlying their sporadic formation is poorly understood. We show that autophagy protects against de novo formation of [PSI+], which is the prion form of the yeast Sup35 translation termination factor. Autophagy is a cellular degradation system, and preventing autophagy by mutating its core components elevates the frequency of spontaneous [PSI+] formation. Conversely, increasing autophagic flux by treating cells with the polyamine spermidine suppresses prion formation in mutants that normally show a high frequency of de novo prion formation. Autophagy also protects against the de novo formation of another prion, namely the Rnq1/[PIN+] prion, which is not related in sequence to the Sup35/[PSI+] prion. We show that growth under anaerobic conditions in the absence of molecular oxygen abrogates Sup35 protein damage and suppresses the high frequency of [PSI+] formation in an autophagy mutant. Autophagy therefore normally functions to remove oxidatively damaged Sup35, which accumulates in cells grown under aerobic conditions, but in the absence of autophagy, damaged/misfolded Sup35 undergoes structural transitions favoring its conversion to the propagatable [PSI+] form.
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Affiliation(s)
- Shaun H Speldewinde
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Victoria A Doronina
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
| | - Chris M Grant
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom
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13
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Abstract
The yeast Saccharomyces cerevisiae harbors several prions that constitute powerful models to investigate the mechanisms of epigenetic structural inheritance. [PSI+] is undoubtedly the best-known yeast prion and results from the conversion of the translation termination factor Sup35p into self-perpetuating protein aggregates. Structurally different conformers of Sup35p aggregates can lead to [PSI+] strains with weak or strong prion phenotypes. Yeast prions are faithfully transmitted from mother to daughter cells during cell division, upon cytoplasmic mixing during mating, or when Sup35p fibrils made in test tubes are introduced into spheroplasts. Virtually all living cells in the three domains of life, Bacteria, Archaea, and Eukarya, secrete small membrane vesicles in the extracellular space. These extracellular vesicles (EV) have gained increasing interest as vehicles for the intercellular transfer of signaling molecules, nucleic acids, and pathogenic factors, as well as prion-like protein aggregates associated with neurodegenerative diseases. To begin to explore the question of whether EV could represent a natural mean for yeast prion transmission from cell to cell, we purified these extracellular vesicles and assessed whether they contained Sup35p. Here, we show that Sup35p is secreted within EV released in the extracellular medium of yeast cultures. We demonstrate that Sup35p within EV isolated from strong and weak [PSI+] cells is in an infectious prion conformation. Among the possible implications of our work is the possibility of previously unsuspected EV-mediated horizontal cell-to-cell transfer of fungal prions. Most living cells in the three domains of life, Bacteria, Archaea, and Eukarya, secrete small membrane vesicles in the extracellular space. These extracellular vesicles (EV) were long viewed as “trash cans” by which cells disposed of unwanted macromolecules. EV gained renewed interest as their roles as vehicles for the cell-to-cell transfer of nucleic acids, signaling molecules, and pathogenic factors were recently uncovered. Of particular interest is their proposed role in the prion-like propagation of toxic protein aggregates in neurodegenerative diseases. Yeasts naturally harbor prion proteins that are excellent models to investigate the mechanisms of formation, propagation, and elimination of self-perpetuating protein aggregates. Here we show for the first time that a yeast prion is secreted within EV in its infectious aggregated state. A major implication of our work is the possibility of EV-mediated horizontal spread of fungal prions.
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14
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Wang K, Redeker V, Madiona K, Melki R, Kabani M. The 26S Proteasome Degrades the Soluble but Not the Fibrillar Form of the Yeast Prion Ure2p In Vitro. PLoS One 2015; 10:e0131789. [PMID: 26115123 PMCID: PMC4482727 DOI: 10.1371/journal.pone.0131789] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 06/08/2015] [Indexed: 12/02/2022] Open
Abstract
Yeast prions are self-perpetuating protein aggregates that cause heritable and transmissible phenotypic traits. Among these, [PSI+] and [URE3] stand out as the most studied yeast prions, and result from the self-assembly of the translation terminator Sup35p and the nitrogen catabolism regulator Ure2p, respectively, into insoluble fibrillar aggregates. Protein quality control systems are well known to govern the formation, propagation and transmission of these prions. However, little is known about the implication of the cellular proteolytic machineries in their turnover. We previously showed that the 26S proteasome degrades both the soluble and fibrillar forms of Sup35p and affects [PSI+] propagation. Here, we show that soluble native Ure2p is degraded by the proteasome in an ubiquitin-independent manner. Proteasomal degradation of Ure2p yields amyloidogenic N-terminal peptides and a C-terminal resistant fragment. In contrast to Sup35p, fibrillar Ure2p resists proteasomal degradation. Thus, structural variability within prions may dictate their ability to be degraded by the cellular proteolytic systems.
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Affiliation(s)
- Kai Wang
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | - Virginie Redeker
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | - Karine Madiona
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | - Ronald Melki
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
- * E-mail: (RM); (MK)
| | - Mehdi Kabani
- Paris-Saclay Institute of Neuroscience, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
- * E-mail: (RM); (MK)
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15
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Li W, Fu J, Zhang S, Zhao J, Xie N, Cai G. The proteasome inhibitor bortezomib induces testicular toxicity by upregulation of oxidative stress, AMP-activated protein kinase (AMPK) activation and deregulation of germ cell development in adult murine testis. Toxicol Appl Pharmacol 2015; 285:98-109. [PMID: 25886977 DOI: 10.1016/j.taap.2015.04.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/18/2015] [Accepted: 04/04/2015] [Indexed: 01/02/2023]
Abstract
Understanding how chemotherapeutic agents mediate testicular toxicity is crucial in light of compelling evidence that male infertility, one of the severe late side effects of intensive cancer treatment, occurs more often than they are expected to. Previous study demonstrated that bortezomib (BTZ), a 26S proteasome inhibitor used to treat refractory multiple myeloma (MM), exerts deleterious impacts on spermatogenesis in pubertal mice via unknown mechanisms. Here, we showed that intermittent treatment with BTZ resulted in fertility impairment in adult mice, evidenced by testicular atrophy, desquamation of immature germ cells and reduced caudal sperm storage. These deleterious effects may originate from the elevated apoptosis in distinct germ cells during the acute phase and the subsequent disruption of Sertoli-germ cell anchoring junctions (AJs) during the late recovery. Mechanistically, balance between AMP-activated protein kinase (AMPK) activation and Akt/ERK pathway appeared to be indispensable for AJ integrity during the late testicular recovery. Of particular interest, the upregulated testicular apoptosis and the following disturbance of Sertoli-germ cell interaction may both stem from the excessive oxidative stress elicited by BTZ exposure. We also provided the in vitro evidence that AMPK-dependent mechanisms counteract follicle-stimulating hormone (FSH) proliferative effects in BTZ-exposed Sertoli cells. Collectively, BTZ appeared to efficiently prevent germ cells from normal development via multiple mechanisms in adult mice. Employment of antioxidants and/or AMPK inhibitor may represent an attractive strategy of fertility preservation in male MM patients exposed to conventional BTZ therapy and warrants further investigation.
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Affiliation(s)
- Wei Li
- Department of Human Anatomy, Histology and Embryology, Fourth Military Medical University, Xi'an 710032, PR China
| | - Jianfang Fu
- Department of Endocrinology, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China
| | - Shun Zhang
- Reproductive Medicine Center, Department of Gynecology and Obstetrics, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, PR China
| | - Jie Zhao
- Department of Human Anatomy, Histology and Embryology, Fourth Military Medical University, Xi'an 710032, PR China
| | - Nianlin Xie
- Department of Thoracic Surgery, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, PR China.
| | - Guoqing Cai
- Department of Gynaecology and Obstetrics, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, PR China.
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16
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Ali M, Chernova TA, Newnam GP, Yin L, Shanks J, Karpova TS, Lee A, Laur O, Subramanian S, Kim D, McNally JG, Seyfried NT, Chernoff YO, Wilkinson KD. Stress-dependent proteolytic processing of the actin assembly protein Lsb1 modulates a yeast prion. J Biol Chem 2014; 289:27625-39. [PMID: 25143386 PMCID: PMC4183801 DOI: 10.1074/jbc.m114.582429] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 08/06/2014] [Indexed: 11/06/2022] Open
Abstract
Yeast prions are self-propagating amyloid-like aggregates of Q/N-rich protein that confer heritable traits and provide a model of mammalian amyloidoses. [PSI(+)] is a prion isoform of the translation termination factor Sup35. Propagation of [PSI(+)] during cell division under normal conditions and during the recovery from damaging environmental stress depends on cellular chaperones and is influenced by ubiquitin proteolysis and the actin cytoskeleton. The paralogous yeast proteins Lsb1 and Lsb2 bind the actin assembly protein Las17 (a yeast homolog of human Wiskott-Aldrich syndrome protein) and participate in the endocytic pathway. Lsb2 was shown to modulate maintenance of [PSI(+)] during and after heat shock. Here, we demonstrate that Lsb1 also regulates maintenance of the Sup35 prion during and after heat shock. These data point to the involvement of Lsb proteins in the partitioning of protein aggregates in stressed cells. Lsb1 abundance and cycling between actin patches, endoplasmic reticulum, and cytosol is regulated by the Guided Entry of Tail-anchored proteins pathway and Rsp5-dependent ubiquitination. Heat shock-induced proteolytic processing of Lsb1 is crucial for prion maintenance during stress. Our findings identify Lsb1 as another component of a tightly regulated pathway controlling protein aggregation in changing environments.
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Affiliation(s)
- Moiez Ali
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Tatiana A Chernova
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322,
| | - Gary P Newnam
- the School of Biology and Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332
| | - Luming Yin
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - John Shanks
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Tatiana S Karpova
- the Center for Cancer Research Core Fluorescence Imaging Facility, Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Andrew Lee
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Oskar Laur
- the Division of Microbiology, Yerkes Research Center, Emory University, Atlanta, Georgia 30329, and
| | - Sindhu Subramanian
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Dami Kim
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - James G McNally
- the Center for Cancer Research Core Fluorescence Imaging Facility, Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Nicholas T Seyfried
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322
| | - Yury O Chernoff
- the School of Biology and Parker H. Petit Institute for Bioengineering & Bioscience, Georgia Institute of Technology, Atlanta, Georgia 30332, the Laboratory of Amyloid Biology, St. Petersburg State University, St. Petersburg, Russia 199034
| | - Keith D Wilkinson
- From the Department of Biochemistry, Emory University School of Medicine, Atlanta, Georgia 30322,
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