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Loh D, Reiter RJ. Melatonin: Regulation of Prion Protein Phase Separation in Cancer Multidrug Resistance. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27030705. [PMID: 35163973 PMCID: PMC8839844 DOI: 10.3390/molecules27030705] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/11/2022] [Accepted: 01/17/2022] [Indexed: 12/13/2022]
Abstract
The unique ability to adapt and thrive in inhospitable, stressful tumor microenvironments (TME) also renders cancer cells resistant to traditional chemotherapeutic treatments and/or novel pharmaceuticals. Cancer cells exhibit extensive metabolic alterations involving hypoxia, accelerated glycolysis, oxidative stress, and increased extracellular ATP that may activate ancient, conserved prion adaptive response strategies that exacerbate multidrug resistance (MDR) by exploiting cellular stress to increase cancer metastatic potential and stemness, balance proliferation and differentiation, and amplify resistance to apoptosis. The regulation of prions in MDR is further complicated by important, putative physiological functions of ligand-binding and signal transduction. Melatonin is capable of both enhancing physiological functions and inhibiting oncogenic properties of prion proteins. Through regulation of phase separation of the prion N-terminal domain which targets and interacts with lipid rafts, melatonin may prevent conformational changes that can result in aggregation and/or conversion to pathological, infectious isoforms. As a cancer therapy adjuvant, melatonin could modulate TME oxidative stress levels and hypoxia, reverse pH gradient changes, reduce lipid peroxidation, and protect lipid raft compositions to suppress prion-mediated, non-Mendelian, heritable, but often reversible epigenetic adaptations that facilitate cancer heterogeneity, stemness, metastasis, and drug resistance. This review examines some of the mechanisms that may balance physiological and pathological effects of prions and prion-like proteins achieved through the synergistic use of melatonin to ameliorate MDR, which remains a challenge in cancer treatment.
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Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA
- Correspondence: (D.L.); (R.J.R.)
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, UT Health San Antonio, San Antonio, TX 78229, USA
- Correspondence: (D.L.); (R.J.R.)
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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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Mutations Outside the Ure2 Amyloid-Forming Region Disrupt [URE3] Prion Propagation and Alter Interactions with Protein Quality Control Factors. Mol Cell Biol 2020; 40:MCB.00294-20. [PMID: 32868289 DOI: 10.1128/mcb.00294-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 08/21/2020] [Indexed: 12/22/2022] Open
Abstract
The yeast prion [URE3] propagates as a misfolded amyloid form of the Ure2 protein. Propagation of amyloid-based yeast prions requires protein quality control (PQC) factors, and altering PQC abundance or activity can cure cells of prions. Yeast antiprion systems composed of PQC factors act at normal abundance to restrict establishment of the majority of prion variants that arise de novo While these systems are well described, how they or other PQC factors interact with prion proteins remains unclear. To gain insight into such interactions, we identified mutations outside the Ure2 prion-determining region that destabilize [URE3]. Despite residing in the functional domain, 16 of 17 mutants retained Ure2 activity. Four characterized mutations caused rapid loss of [URE3] yet allowed [URE3] to propagate under prion-selecting conditions. Two sensitized [URE3] to Btn2, Cur1, and Hsp42, but in different ways. Two others reduced amyloid formation in vitro Of these, one impaired prion replication and the other apparently impaired transmission. Thus, widely dispersed sites outside a prion's amyloid-forming region can contribute to prion character, and altering such sites can disrupt prion propagation by altering interactions with PQC factors.
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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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Kabani M, Melki R. The Yarrowia lipolytica orthologs of Sup35p assemble into thioflavin T-negative amyloid fibrils. Biochem Biophys Res Commun 2020; 529:533-539. [PMID: 32736670 DOI: 10.1016/j.bbrc.2020.06.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 06/05/2020] [Indexed: 11/26/2022]
Abstract
The translation terminator Sup35p assembles into self-replicating fibrillar aggregates that are responsible for the [PSI+] prion state. The Q/N-rich N-terminal domain together with the highly charged middle-domain (NM domain) drive the assembly of Sup35p into amyloid fibrils in vitro. NM domains are highly divergent among yeasts. The ability to convert to a prion form is however conserved among Sup35 orthologs. In particular, the Yarrowia lipolytica Sup35p stands out with an exceptionally high prion conversion rate. In the present work, we show that different Yarrowia lipolytica strains contain one of two Sup35p orthologs that differ by the number of repeats within their NM domain. The Y. lipolytica Sup35 proteins are able to assemble into amyloid fibrils. Contrary to S. cerevisiae Sup35p, fibrils made of full-length or NM domains of Y. lipolytica Sup35 proteins did not bind Thioflavin-T, a well-known marker of amyloid aggregates.
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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), F-92265, 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), F-92265, Fontenay-aux-Roses, France
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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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8
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Manjrekar J, Shah H. Protein-based inheritance. Semin Cell Dev Biol 2019; 97:138-155. [PMID: 31344459 DOI: 10.1016/j.semcdb.2019.07.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Accepted: 07/08/2019] [Indexed: 01/17/2023]
Abstract
Epigenetic mechanisms of inheritance have come to occupy a prominent place in our understanding of living systems, primarily eukaryotes. There has been considerable and lively discussion of the possible evolutionary significance of transgenerational epigenetic inheritance. One particular type of epigenetic inheritance that has not figured much in general discussions is that based on conformational changes in proteins, where proteins with altered conformations can act as templates to propagate their own structure. An increasing number of such proteins - prions and prion-like - are being discovered. Phenotypes due to the structurally altered proteins are transmitted along with their structures. This review discusses the properties and implications of "classical" amyloid-forming prions, as well as the broader class of proteins with intrinsically disordered domains, which are proving to have fascinating properties that appear to play important roles in cell organisation and function, especially during stress responses.
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Affiliation(s)
- Johannes Manjrekar
- Microbiology Department and Biotechnology Centre, The Maharaja Sayajirao University of Baroda, Vadodara, 390002, India.
| | - Hiral Shah
- Microbiology Department and Biotechnology Centre, The Maharaja Sayajirao University of Baroda, Vadodara, 390002, India
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9
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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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10
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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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11
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Tikhodeyev ON, Tarasov OV, Bondarev SA. Allelic variants of hereditary prions: The bimodularity principle. Prion 2017; 11:4-24. [PMID: 28281926 PMCID: PMC5360123 DOI: 10.1080/19336896.2017.1283463] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 01/04/2017] [Accepted: 01/10/2017] [Indexed: 12/26/2022] Open
Abstract
Modern biology requires modern genetic concepts equally valid for all discovered mechanisms of inheritance, either "canonical" (mediated by DNA sequences) or epigenetic. Applying basic genetic terms such as "gene" and "allele" to protein hereditary factors is one of the necessary steps toward these concepts. The basic idea that different variants of the same prion protein can be considered as alleles has been previously proposed by Chernoff and Tuite. In this paper, the notion of prion allele is further developed. We propose the idea that any prion allele is a bimodular hereditary system that depends on a certain DNA sequence (DNA determinant) and a certain epigenetic mark (epigenetic determinant). Alteration of any of these 2 determinants may lead to establishment of a new prion allele. The bimodularity principle is valid not only for hereditary prions; it seems to be universal for any epigenetic hereditary factor.
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Affiliation(s)
- Oleg N. Tikhodeyev
- Department of Genetics & Biotechnology, Saint-Petersburg State University, Saint-Petersburg, Russia
| | - Oleg V. Tarasov
- Department of Genetics & Biotechnology, Saint-Petersburg State University, Saint-Petersburg, Russia
- Saint-Petersburg Scientific Center of RAS, Saint-Petersburg, Russia
| | - Stanislav A. Bondarev
- Department of Genetics & Biotechnology, Saint-Petersburg State University, Saint-Petersburg, Russia
- The Laboratory of Amyloid Biology, Saint-Petersburg State University, Saint-Petersburg, Russia
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12
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Abstract
Although prions were first discovered through their link to severe brain degenerative diseases in animals, the emergence of prions as regulators of the phenotype of the yeast Saccharomyces cerevisiae and the filamentous fungus Podospora anserina has revealed a new facet of prion biology. In most cases, fungal prions are carried without apparent detriment to the host cell, representing a novel form of epigenetic inheritance. This raises the question of whether or not yeast prions are beneficial survival factors or actually gives rise to a "disease state" that is selected against in nature. To date, most studies on the impact of fungal prions have focused on laboratory-cultivated "domesticated" strains of S. cerevisiae. At least eight prions have now been described in this species, each with the potential to impact on a wide range of cellular processes. The discovery of prions in nondomesticated strains of S. cerevisiae and P. anserina has confirmed that prions are not simply an artifact of "domestication" of this species. In this review, I describe what we currently know about the phenotypic impact of fungal prions. I then describe how the interplay between host genotype and the prion-mediated changes can generate a wide array of phenotypic diversity. How such prion-generated diversity may be of benefit to the host in survival in a fluctuating, often hazardous environment is then outlined. Prion research has now entered a new phase in which we must now consider their biological function and evolutionary significance in the natural world.
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Affiliation(s)
- Mick F Tuite
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, United Kingdom.
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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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14
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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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15
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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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16
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Genome-wide translational changes induced by the prion [PSI+]. Cell Rep 2014; 8:439-48. [PMID: 25043188 DOI: 10.1016/j.celrep.2014.06.036] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 04/14/2014] [Accepted: 06/19/2014] [Indexed: 12/11/2022] Open
Abstract
Prions are infectious proteins that can adopt a structural conformation that is then propagated among other molecules of the same protein. [PSI(+)] is an aggregated conformation of the translational release factor eRF3. [PSI(+)] modifies cellular fitness, inducing various phenotypes depending on genetic background. However, the genes displaying [PSI(+)]-controlled expression remain unknown. We used ribosome profiling in isogenic [PSI(+)] and [psi(-)] strains to identify the changes induced by [PSI(+)]. We found 100 genes with stop codon readthrough events and showed that many stress-response genes were repressed in the presence of [PSI(+)]. Surprisingly, [PSI(+)] was also found to affect reading frame selection independently of its effect on translation termination efficiency. These results indicate that [PSI(+)] has a broader impact than initially anticipated, providing explanations for the phenotypic differences between [psi(-)] and [PSI(+)] strains.
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Kabani M, Redeker V, Melki R. A role for the proteasome in the turnover of Sup35p and in [PSI(+) ] prion propagation. Mol Microbiol 2014; 92:507-28. [PMID: 24589377 DOI: 10.1111/mmi.12572] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2014] [Indexed: 01/21/2023]
Abstract
Yeast prions are superb models for understanding the mechanisms of self-perpetuating protein aggregates formation. [PSI(+) ] stands among the most documented yeast prions and results from self-assembly of the translation termination factor Sup35p into protein fibrils. A plethora of cellular factors were shown to affect [PSI(+) ] formation and propagation. Clearance of Sup35p prion particles is however poorly understood and documented. Here, we investigated the role of the proteasome in the degradation of Sup35p and in [PSI(+) ] prion propagation. We found that cells lacking the RPN4 gene, which have reduced intracellular proteasome pools, accumulated Sup35p and have defects in [PSI(+) ] formation and propagation. Sup35p is degraded in vitro by the 26S and 20S proteasomes in a ubiquitin-independent manner, generating an array of amyloidogenic peptides derived from its prion-domain. We also demonstrate the formation of a proteasome-resistant fragment spanning residues 83-685 which is devoid of the prion-domain that is essential for [PSI(+) ] propagation. Most important was the finding that the 26S and 20S proteasomes degrade Sup35p fibrils in vitro and abolish their infectivity. Our results point to an overlooked role of the proteasome in clearing toxic protein aggregates, and have important implications for a better understanding of the life cycle of infectious protein assemblies.
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Affiliation(s)
- Mehdi Kabani
- Laboratoire d'Enzymologie et Biochimie Structurales, CNRS, Bât. 34, Avenue de la Terrasse, F-91190, Gif-sur-Yvette, France
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Yeast prions and human prion-like proteins: sequence features and prediction methods. Cell Mol Life Sci 2014; 71:2047-63. [PMID: 24390581 DOI: 10.1007/s00018-013-1543-6] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 12/12/2013] [Accepted: 12/16/2013] [Indexed: 11/27/2022]
Abstract
Prions are self-propagating infectious protein isoforms. A growing number of prions have been identified in yeast, each resulting from the conversion of soluble proteins into an insoluble amyloid form. These yeast prions have served as a powerful model system for studying the causes and consequences of prion aggregation. Remarkably, a number of human proteins containing prion-like domains, defined as domains with compositional similarity to yeast prion domains, have recently been linked to various human degenerative diseases, including amyotrophic lateral sclerosis. This suggests that the lessons learned from yeast prions may help in understanding these human diseases. In this review, we examine what has been learned about the amino acid sequence basis for prion aggregation in yeast, and how this information has been used to develop methods to predict aggregation propensity. We then discuss how this information is being applied to understand human disease, and the challenges involved in applying yeast prediction methods to higher organisms.
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Na I, Reddy KD, Breydo L, Xue B, Uversky VN. A putative role of the Sup35p C-terminal domain in the cytoskeleton organization during yeast mitosis. ACTA ACUST UNITED AC 2014; 10:925-40. [DOI: 10.1039/c3mb70515c] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Based on structural analysis of several effectors and partners, Sup35pC is proposed to serve as actin modulator during mitosis.
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Affiliation(s)
- Insung Na
- Department of Molecular Medicine
- Morsani College of Medicine
- University of South Florida
- Tampa, USA
| | - Krishna D. Reddy
- Department of Molecular Medicine
- Morsani College of Medicine
- University of South Florida
- Tampa, USA
| | - Leonid Breydo
- Department of Molecular Medicine
- Morsani College of Medicine
- University of South Florida
- Tampa, USA
| | - Bin Xue
- Department of Cell Biology
- Microbiology, and Molecular Biology
- College of Arts and Science
- University of South Florida
- Tampa, USA
| | - Vladimir N. Uversky
- Department of Molecular Medicine
- Morsani College of Medicine
- University of South Florida
- Tampa, USA
- USF Health Byrd Alzheimer's Research Institute
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Luckgei N, Schütz AK, Bousset L, Habenstein B, Sourigues Y, Gardiennet C, Meier BH, Melki R, Böckmann A. Die Konformation der Prionendomäne von Sup35: isoliert und im Kontext des Volllängen-Proteins. Angew Chem Int Ed Engl 2013. [DOI: 10.1002/ange.201304699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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21
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Luckgei N, Schütz AK, Bousset L, Habenstein B, Sourigues Y, Gardiennet C, Meier BH, Melki R, Böckmann A. The Conformation of the Prion Domain of Sup35 p in Isolation and in the Full-Length Protein. Angew Chem Int Ed Engl 2013; 52:12741-4. [DOI: 10.1002/anie.201304699] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 07/24/2013] [Indexed: 11/08/2022]
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22
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Abstract
The concept of a prion as an infectious self-propagating protein isoform was initially proposed to explain certain mammalian diseases. It is now clear that yeast also has heritable elements transmitted via protein. Indeed, the "protein only" model of prion transmission was first proven using a yeast prion. Typically, known prions are ordered cross-β aggregates (amyloids). Recently, there has been an explosion in the number of recognized prions in yeast. Yeast continues to lead the way in understanding cellular control of prion propagation, prion structure, mechanisms of de novo prion formation, specificity of prion transmission, and the biological roles of prions. This review summarizes what has been learned from yeast prions.
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Affiliation(s)
- Susan W Liebman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Nevada 89557, USA.
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[PSI+] Prion transmission barriers protect Saccharomyces cerevisiae from infection: intraspecies 'species barriers'. Genetics 2011; 190:569-79. [PMID: 22095075 DOI: 10.1534/genetics.111.136655] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
[PSI+] is a prion of Sup35p, an essential translation termination and mRNA turnover factor. The existence of lethal [PSI+] variants, the absence of [PSI+] in wild strains, the mRNA turnover function of the Sup35p prion domain, and the stress reaction to prion infection suggest that [PSI+] is a disease. Nonetheless, others have proposed that [PSI+] and other yeast prions benefit their hosts. We find that wild Saccharomyces cerevisiae strains are polymorphic for the sequence of the prion domain and particularly in the adjacent M domain. Here we establish that these variations within the species produce barriers to prion transmission. The barriers are partially asymmetric in some cases, and evidence for variant specificity in barriers is presented. We propose that, as the PrP 129M/V polymorphism protects people from Creutzfeldt-Jakob disease, the Sup35p polymorphisms were selected to protect yeast cells from prion infection. In one prion incompatibility group, the barrier is due to N109S in the Sup35 prion domain and several changes in the middle (M) domain, with either the single N109S mutation or the group of M changes (without the N109S) producing a barrier. In another, the barrier is due to a large deletion in the repeat domain. All are outside the region previously believed to determine transmission compatibility. [SWI+], a prion of the chromatin remodeling factor Swi1p, was also proposed to benefit its host. We find that none of 70 wild strains carry this prion, suggesting that it is not beneficial.
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Abstract
Prions are infectious proteins with altered conformations converted from otherwise normal host proteins. While there is only one known mammalian prion protein, PrP, a handful of prion proteins have been identified in the yeast Saccharomyces cerevisiae. Yeast prion proteins usually have a defined region called prion domain (PrD) essential for prion properties, which are typically rich in glutamine (Q) and asparagine (N). Despite sharing several common features, individual yeast PrDs are generally intricate and divergent in their compositional characteristics, which potentially implicates their prion phenotypes, such as prion-mediated transcriptional regulations.
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Affiliation(s)
- Zhiqiang Du
- Department of Molecular Pharmacology and Biological Chemistry, Northwestern University, Chicago, IL, USA.
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25
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Abstract
The unexpected discovery of two prions, [URE3] and [PSI+], in Saccharomyces cerevisiae led to questions about how many other proteins could undergo similar prion-based structural conversions. However, [URE3] and [PSI+] were discovered by serendipity in genetic screens. Cataloging the full range of prions in yeast or in other organisms will therefore require more systematic search methods. Taking advantage of some of the unique features of prions, various researchers have developed bioinformatic and experimental methods for identifying novel prion proteins. These methods have generated long lists of prion candidates. The systematic testing of some of these prion candidates has led to notable successes; however, even in yeast, where rapid growth rate and ease of genetic manipulation aid in testing for prion activity, such candidate testing is laborious. Development of better methods to winnow the field of prion candidates will greatly aid in the discovery of new prions, both in yeast and in other organisms, and help us to better understand the role of prions in biology.
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Affiliation(s)
- Kyle S MacLea
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, USA
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Kabani M, Melki R. Yeast prions assembly and propagation: contributions of the prion and non-prion moieties and the nature of assemblies. Prion 2011; 5:277-84. [PMID: 22052349 DOI: 10.4161/pri.18070] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Yeast prions are self-perpetuating protein aggregates that are at the origin of heritable and transmissible non-Mendelian phenotypic traits. 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. Fibril assembly depends on the presence of N- or C-terminal prion domains (PrDs) which are not homologous in sequence but share unusual amino-acid compositions, such as enrichment in polar residues (glutamines and asparagines) or the presence of oligopeptide repeats. Purified PrDs form amyloid fibrils that can convert prion-free cells to the prion state upon transformation. Nonetheless, isolated PrDs and full-length prion proteins have different aggregation, structural and infectious properties. In addition, mutations in the "non-prion" domains (non-PrDs) of Sup35p, Ure2p and Rnq1p were shown to affect their prion properties in vitro and in vivo. Despite these evidences, the implication of the functional non-PrDs in fibril assembly and prion propagation has been mostly overlooked. In this review, we discuss the contribution of non-PrDs to prion assemblies, and the structure-function relationship in prion infectivity in the light of recent findings on Sup35p and Ure2p assembly into infectious fibrils from our laboratory and others.
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Affiliation(s)
- Mehdi Kabani
- Laboratoire d'Enzymologie et Biochimie Structurales, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.
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Abstract
Prions are infectious proteins with altered conformations converted from otherwise normal host proteins. While there is only one known mammalian prion protein, PrP, a handful of prion proteins have been identified in the yeast Saccharomyces cerevisiae. Yeast prion proteins usually have a defined region called prion domain (PrD) essential for prion properties, which are typically rich in glutamine (Q) and asparagine (N). Despite sharing several common features, individual yeast PrDs are generally intricate and divergent in their compositional characteristics, which potentially implicates their prion phenotypes, such as prion-mediated transcriptional regulations.
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