1
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Takallou S, Hajikarimlou M, Al-Gafari M, Wang J, Jagadeesan SK, Kazmirchuk TDD, Moteshareie H, Indrayanti AM, Azad T, Holcik M, Samanfar B, Smith M, Golshani A. Hydrogen peroxide sensitivity connects the activity of COX5A and NPR3 to the regulation of YAP1 expression. FASEB J 2024; 38:e23439. [PMID: 38416461 DOI: 10.1096/fj.202300978rr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 12/13/2023] [Accepted: 01/09/2024] [Indexed: 02/29/2024]
Abstract
Reactive oxygen species (ROS) are among the most severe types of cellular stressors with the ability to damage essential cellular biomolecules. Excess levels of ROS are correlated with multiple pathophysiological conditions including neurodegeneration, diabetes, atherosclerosis, and cancer. Failure to regulate the severely imbalanced levels of ROS can ultimately lead to cell death, highlighting the importance of investigating the molecular mechanisms involved in the detoxification procedures that counteract the effects of these compounds in living organisms. One of the most abundant forms of ROS is H2 O2 , mainly produced by the electron transport chain in the mitochondria. Numerous genes have been identified as essential to the process of cellular detoxification. Yeast YAP1, which is homologous to mammalian AP-1 type transcriptional factors, has a key role in oxidative detoxification by upregulating the expression of antioxidant genes in yeast. The current study reveals novel functions for COX5A and NPR3 in H2 O2 -induced stress by demonstrating that their deletions result in a sensitive phenotype. Our follow-up investigations indicate that COX5A and NPR3 regulate the expression of YAP1 through an alternative mode of translation initiation. These novel gene functions expand our understanding of the regulation of gene expression and defense mechanism of yeast against oxidative stress.
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Affiliation(s)
- Sarah Takallou
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Maryam Hajikarimlou
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Mustafa Al-Gafari
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Jiashu Wang
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Sasi Kumar Jagadeesan
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Thomas David Daniel Kazmirchuk
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Houman Moteshareie
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
- Biotechnology Laboratory, Environmental Health Science and Research Bureau, Healthy Environments and Consumer Safety Branch, Health Canada, Ottawa, Ontario, Canada
| | | | - Taha Azad
- Faculty of Medicine and Health Sciences, Department of Microbiology and Infectious Diseases, Université de Sherbrooke, Sherbrooke, Quebec, Canada
- Research Center of the Centre Hospitalier Universitaire de Sherbrooke (CHUS), Sherbrooke, Quebec, Canada
| | - Martin Holcik
- Department of Health Sciences, Carleton University, Ottawa, Ontario, Canada
| | - Bahram Samanfar
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
- Agriculture and Agri-Food Canada, Ottawa Research and Development Centre (ORDC), Ottawa, Ontario, Canada
| | - Myron Smith
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Ashkan Golshani
- Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
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2
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Bayandina SV, Mukha DV. Saccharomyces cerevisiae as a Model for Studying Human Neurodegenerative Disorders: Viral Capsid Protein Expression. Int J Mol Sci 2023; 24:17213. [PMID: 38139041 PMCID: PMC10743263 DOI: 10.3390/ijms242417213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 11/30/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
In this article, we briefly describe human neurodegenerative diseases (NDs) and the experimental models used to study them. The main focus is the yeast Saccharomyces cerevisiae as an experimental model used to study neurodegenerative processes. We review recent experimental data on the aggregation of human neurodegenerative disease-related proteins in yeast cells. In addition, we describe the results of studies that were designed to investigate the molecular mechanisms that underlie the aggregation of reporter proteins. The advantages and disadvantages of the experimental approaches that are currently used to study the formation of protein aggregates are described. Special attention is given to the similarity between aggregates that form as a result of protein misfolding and viral factories-special structural formations in which viral particles are formed inside virus-infected cells. A separate part of the review is devoted to our previously published study on the formation of aggregates upon expression of the insect densovirus capsid protein in yeast cells. Based on the reviewed results of studies on NDs and related protein aggregation, as well as viral protein aggregation, a new experimental model system for the study of human NDs is proposed. The core of the proposed system is a comparative transcriptomic analysis of changes in signaling pathways during the expression of viral capsid proteins in yeast cells.
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Affiliation(s)
| | - Dmitry V. Mukha
- Vavilov Institute of General Genetics Russian Academy of Sciences, 119991 Moscow, Russia
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3
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Del Vecchio M, Amado L, Cogan AP, Meert E, Rosseels J, Franssens V, Govers SK, Winderickx J, Montoro AG. Multiple tethers of organelle contact sites are involved in α-synuclein toxicity in yeast. Mol Biol Cell 2023; 34:ar84. [PMID: 37074954 PMCID: PMC10398879 DOI: 10.1091/mbc.e23-01-0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/05/2023] [Accepted: 04/12/2023] [Indexed: 04/20/2023] Open
Abstract
The protein α-synuclein (α-syn) is one of the major factors linked to Parkinson's disease, yet how its misfolding and deposition contribute to the pathology remains largely elusive. Recently, contact sites among organelles were implicated in the development of this disease. Here, we used the budding yeast Saccharomyces cerevisiae, in which organelle contact sites have been characterized extensively, as a model to investigate their role in α-syn cytotoxicity. We observed that lack of specific tethers that anchor the endoplasmic reticulum to the plasma membrane resulted in cells with increased resistance to α-syn expression. Additionally, we found that strains lacking two dual-function proteins involved in contact sites, Mdm10 and Vps39, were resistant to the expression of α-syn. In the case of Mdm10, we found that this is related to its function in mitochondrial protein biogenesis and not to its role as a contact site tether. In contrast, both functions of Vps39, in vesicular transport and as a tether of the vacuole-mitochondria contact site, were required to support α-syn toxicity. Overall, our findings support that interorganelle communication through membrane contact sites is highly relevant for α-syn-mediated toxicity.
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Affiliation(s)
- Mara Del Vecchio
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
- Department of Biology, Microbial Systems Cell Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Lucia Amado
- Department of Biology/Chemistry, Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany
| | - Alexandra P. Cogan
- Department of Biology/Chemistry, Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany
| | - Els Meert
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Joelle Rosseels
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Vanessa Franssens
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Sander K. Govers
- Department of Biology, Microbial Systems Cell Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Joris Winderickx
- Department of Biology, Functional Biology Laboratory, KU Leuven, 3001 Heverlee, Belgium
| | - Ayelén González Montoro
- Department of Biology/Chemistry, Cellular Communication Laboratory, Osnabrück University, 49076 Osnabrück, Germany
- Center of Cellular Nanoanalytics Osnabrück, 49076 Osnabrück, Germany
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4
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Ring J, Tadic J, Ristic S, Poglitsch M, Bergmann M, Radic N, Mossmann D, Liang Y, Maglione M, Jerkovic A, Hajiraissi R, Hanke M, Küttner V, Wolinski H, Zimmermann A, Domuz Trifunović L, Mikolasch L, Moretti DN, Broeskamp F, Westermayer J, Abraham C, Schauer S, Dammbrueck C, Hofer SJ, Abdellatif M, Grundmeier G, Kroemer G, Braun RJ, Hansen N, Sommer C, Ninkovic M, Seba S, Rockenfeller P, Vögtle F, Dengjel J, Meisinger C, Keller A, Sigrist SJ, Eisenberg T, Madeo F. The HSP40 chaperone Ydj1 drives amyloid beta 42 toxicity. EMBO Mol Med 2022; 14:e13952. [PMID: 35373908 PMCID: PMC9081910 DOI: 10.15252/emmm.202113952] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/12/2022] [Accepted: 02/15/2022] [Indexed: 01/22/2023] Open
Abstract
Amyloid beta 42 (Abeta42) is the principal trigger of neurodegeneration during Alzheimer's disease (AD). However, the etiology of its noxious cellular effects remains elusive. In a combinatory genetic and proteomic approach using a yeast model to study aspects of intracellular Abeta42 toxicity, we here identify the HSP40 family member Ydj1, the yeast orthologue of human DnaJA1, as a crucial factor in Abeta42-mediated cell death. We demonstrate that Ydj1/DnaJA1 physically interacts with Abeta42 (in yeast and mouse), stabilizes Abeta42 oligomers, and mediates their translocation to mitochondria. Consequently, deletion of YDJ1 strongly reduces co-purification of Abeta42 with mitochondria and prevents Abeta42-induced mitochondria-dependent cell death. Consistently, purified DnaJ chaperone delays Abeta42 fibrillization in vitro, and heterologous expression of human DnaJA1 induces formation of Abeta42 oligomers and their deleterious translocation to mitochondria in vivo. Finally, downregulation of the Ydj1 fly homologue, Droj2, improves stress resistance, mitochondrial morphology, and memory performance in a Drosophila melanogaster AD model. These data reveal an unexpected and detrimental role for specific HSP40s in promoting hallmarks of Abeta42 toxicity.
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Flønes IH, Tzoulis C. Mitochondrial Respiratory Chain Dysfunction—A Hallmark Pathology of Idiopathic Parkinson’s Disease? Front Cell Dev Biol 2022; 10:874596. [PMID: 35433702 PMCID: PMC9010539 DOI: 10.3389/fcell.2022.874596] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 03/10/2022] [Indexed: 12/21/2022] Open
Abstract
Parkinson’s disease (PD) is the most common age-dependent neurodegenerative synucleinopathy. Loss of dopaminergic neurons of the substantia nigra pars compacta, together with region- and cell-specific aggregations of α-synuclein are considered main pathological hallmarks of PD, but its etiopathogenesis remains largely unknown. Mitochondrial dysfunction, in particular quantitative and/or functional deficiencies of the mitochondrial respiratory chain (MRC), has been associated with the disease. However, after decades of research in this field, the pervasiveness and anatomical extent of MRC dysfunction in PD remain largely unknown. Moreover, it is not known whether the observed MRC defects are pathogenic, compensatory responses, or secondary epiphenomena. In this perspective, we give an overview of current evidence for MRC dysfunction in PD, highlight pertinent knowledge gaps, and propose potential strategies for future research.
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Affiliation(s)
- Irene H. Flønes
- Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
- K.G Jebsen Center for Translational Research in Parkinson’s Disease, University of Bergen, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
| | - Charalampos Tzoulis
- Neuro-SysMed, Department of Neurology, Haukeland University Hospital, Bergen, Norway
- K.G Jebsen Center for Translational Research in Parkinson’s Disease, University of Bergen, Bergen, Norway
- Department of Clinical Medicine, University of Bergen, Bergen, Norway
- *Correspondence: Charalampos Tzoulis,
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6
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Bhatia-Kissova I, Camougrand N. Mitophagy in Yeast: Decades of Research. Cells 2021; 10:3541. [PMID: 34944049 PMCID: PMC8700663 DOI: 10.3390/cells10123541] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/06/2021] [Accepted: 12/10/2021] [Indexed: 12/02/2022] Open
Abstract
Mitophagy, the selective degradation of mitochondria by autophagy, is one of the most important mechanisms of mitochondrial quality control, and its proper functioning is essential for cellular homeostasis. In this review, we describe the most important milestones achieved during almost 2 decades of research on yeasts, which shed light on the molecular mechanisms, regulation, and role of the Atg32 receptor in this process. We analyze the role of ROS in mitophagy and discuss the physiological roles of mitophagy in unicellular organisms, such as yeast; these roles are very different from those in mammals. Additionally, we discuss some of the different tools available for studying mitophagy.
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Affiliation(s)
- Ingrid Bhatia-Kissova
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 84215 Bratislava, Slovakia;
| | - Nadine Camougrand
- CNRS, UMR 5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France
- Institut de Biochimie et de Génétique Cellulaires, Université de Bordeaux, UMR 5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France
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7
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Habernig L, Broeskamp F, Aufschnaiter A, Diessl J, Peselj C, Urbauer E, Eisenberg T, de Ory A, Büttner S. Ca2+ administration prevents α-synuclein proteotoxicity by stimulating calcineurin-dependent lysosomal proteolysis. PLoS Genet 2021; 17:e1009911. [PMID: 34780474 PMCID: PMC8629384 DOI: 10.1371/journal.pgen.1009911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 11/29/2021] [Accepted: 10/25/2021] [Indexed: 12/02/2022] Open
Abstract
The capacity of a cell to maintain proteostasis progressively declines during aging. Virtually all age-associated neurodegenerative disorders associated with aggregation of neurotoxic proteins are linked to defects in the cellular proteostasis network, including insufficient lysosomal hydrolysis. Here, we report that proteotoxicity in yeast and Drosophila models for Parkinson's disease can be prevented by increasing the bioavailability of Ca2+, which adjusts intracellular Ca2+ handling and boosts lysosomal proteolysis. Heterologous expression of human α-synuclein (αSyn), a protein critically linked to Parkinson's disease, selectively increases total cellular Ca2+ content, while the levels of manganese and iron remain unchanged. Disrupted Ca2+ homeostasis results in inhibition of the lysosomal protease cathepsin D and triggers premature cellular and organismal death. External administration of Ca2+ reduces αSyn oligomerization, stimulates cathepsin D activity and in consequence restores survival, which critically depends on the Ca2+/calmodulin-dependent phosphatase calcineurin. In flies, increasing the availability of Ca2+ discloses a neuroprotective role of αSyn upon manganese overload. In sum, we establish a molecular interplay between cathepsin D and calcineurin that can be activated by Ca2+ administration to counteract αSyn proteotoxicity.
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Affiliation(s)
- Lukas Habernig
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Filomena Broeskamp
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Andreas Aufschnaiter
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Jutta Diessl
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Carlotta Peselj
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Elisabeth Urbauer
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Tobias Eisenberg
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
- Field of Excellence BioHealth–University of Graz, Graz, Austria
| | - Ana de Ory
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Sabrina Büttner
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
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8
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Khan A, Kuriachan G, Mahalakshmi R. Cellular Interactome of Mitochondrial Voltage-Dependent Anion Channels: Oligomerization and Channel (Mis)Regulation. ACS Chem Neurosci 2021; 12:3497-3515. [PMID: 34503333 DOI: 10.1021/acschemneuro.1c00429] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Voltage-dependent anion channels (VDACs) of the outer mitochondrial membrane are known conventionally as metabolite flux proteins. However, research findings in the past decade have revealed the multifaceted regulatory roles of VDACs, from governing cellular physiology and mitochondria-mediated apoptosis to directly regulating debilitating cancers and neurodegenerative diseases. VDACs achieve these diverse functions by establishing isoform-dependent stereospecific interactomes in the cell with the cytosolic constituents and endoplasmic reticulum complexes, and the machinery of the mitochondrial compartments. VDACs are now increasingly recognized as regulatory hubs of the cell. Not surprisingly, even the transient misregulation of VDACs results directly in mitochondrial dysfunction. Additionally, human VDACs are now implicated in interaction with aggregation-prone cytosolic proteins, including Aβ, tau, and α-synuclein, contributing directly to the onset of Alzheimer's and Parkinson's diseases. Deducing the interaction dynamics and mechanisms can lead to VDAC-targeted peptide-based therapeutics that can alleviate neurodegenerative states. This review succinctly presents the latest findings of the VDAC interactome, and the mode(s) of VDAC-dependent regulation of biochemical physiology. We also discuss the relevance of VDACs in pathophysiological states and aggregation-associated diseases and address how VDACs will facilitate the development of next-generation precision medicines.
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Affiliation(s)
- Altmash Khan
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462066, India
| | - Gifty Kuriachan
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462066, India
| | - Radhakrishnan Mahalakshmi
- Molecular Biophysics Laboratory, Department of Biological Sciences, Indian Institute of Science Education and Research, Bhopal 462066, India
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9
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Popova B, Galka D, Häffner N, Wang D, Schmitt K, Valerius O, Knop M, Braus GH. α-Synuclein Decreases the Abundance of Proteasome Subunits and Alters Ubiquitin Conjugates in Yeast. Cells 2021; 10:cells10092229. [PMID: 34571878 PMCID: PMC8468666 DOI: 10.3390/cells10092229] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 08/25/2021] [Accepted: 08/25/2021] [Indexed: 01/18/2023] Open
Abstract
Parkinson’s disease (PD) is the most prevalent movement disorder characterized with loss of dopaminergic neurons in the brain. One of the pathological hallmarks of the disease is accumulation of aggregated α-synuclein (αSyn) in cytoplasmic Lewy body inclusions that indicates significant dysfunction of protein homeostasis in PD. Accumulation is accompanied with highly elevated S129 phosphorylation, suggesting that this posttranslational modification is linked to pathogenicity and altered αSyn inclusion dynamics. To address the role of S129 phosphorylation on protein dynamics further we investigated the wild type and S129A variants using yeast and a tandem fluorescent timer protein reporter approach to monitor protein turnover and stability. Overexpression of both variants leads to inhibited yeast growth. Soluble S129A is more stable and additional Y133F substitution permits αSyn degradation in a phosphorylation-independent manner. Quantitative cellular proteomics revealed significant αSyn-dependent disturbances of the cellular protein homeostasis, which are increased upon S129 phosphorylation. Disturbances are characterized by decreased abundance of the ubiquitin-dependent protein degradation machinery. Biotin proximity labelling revealed that αSyn interacts with the Rpt2 base subunit. Proteasome subunit depletion by reducing the expression of the corresponding genes enhances αSyn toxicity. Our studies demonstrate that turnover of αSyn and depletion of the proteasome pool correlate in a complex relationship between altered proteasome composition and increased αSyn toxicity.
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Affiliation(s)
- Blagovesta Popova
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
- Correspondence: (B.P.); (G.H.B.)
| | - Dajana Galka
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Nicola Häffner
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Dan Wang
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Kerstin Schmitt
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Oliver Valerius
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
| | - Michael Knop
- Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Heidelberg University, 69120 Heidelberg, Germany;
| | - Gerhard H. Braus
- Department of Molecular Microbiology and Genetics, Institute for Microbiology and Genetics, University of Göttingen, 37077 Göttingen, Germany; (D.G.); (N.H.); (D.W.); (K.S.); (O.V.)
- Correspondence: (B.P.); (G.H.B.)
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10
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Burtscher J, Syed MMK, Keller MA, Lashuel HA, Millet GP. Fatal attraction - The role of hypoxia when alpha-synuclein gets intimate with mitochondria. Neurobiol Aging 2021; 107:128-141. [PMID: 34428721 DOI: 10.1016/j.neurobiolaging.2021.07.017] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 07/21/2021] [Accepted: 07/24/2021] [Indexed: 12/21/2022]
Abstract
Alpha-synuclein aggregation and mitochondrial dysfunction are main pathological hallmarks of Parkinson's disease (PD) and several other neurodegenerative diseases, collectively known as synucleinopathies. However, increasing evidence suggests that they may not be sufficient to cause PD. Here we propose the role of hypoxia as a missing link that connects the complex interplay between alpha-synuclein biochemistry and pathology, mitochondrial dysfunctions and neurodegeneration in PD. We review the partly conflicting literature on alpha-synuclein binding to membranes and mitochondria and its impact on mitochondrial functions. From there, we focus on adverse changes in cellular environments, revolving around hypoxic stress, that may trigger or facilitate PD progression. Inter-dependent structural re-arrangements of mitochondrial membranes, including increased cytoplasmic exposure of mitochondrial cardiolipins and changes in alpha-synuclein localization and conformation are discussed consequences of such conditions. Enhancing cellular resilience could be an integral part of future combination-based therapies of PD. This may be achieved by boosting the capacity of cellular and specifically mitochondrial processes to regulate and adapt to altered proteostasis, redox, and inflammatory conditions and by inducing protective molecular and tissue re-modelling.
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Affiliation(s)
- Johannes Burtscher
- Department of Biomedical Sciences, University of Lausanne, Lausanne, Switzerland; Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland.
| | - Muhammed Muazzam Kamil Syed
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Markus A Keller
- Institute of Human Genetics, Medical University of Innsbruck, Innsbruck, Austria
| | - Hilal A Lashuel
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Grégoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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11
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Callewaert G, D'hooge P, Ma TY, Del Vecchio M, Van Eyck V, Franssens V, Winderickx J. Decreased Vacuolar Ca 2+ Storage and Disrupted Vesicle Trafficking Underlie Alpha-Synuclein-Induced Ca 2+ Dysregulation in S. cerevisiae. Front Genet 2020; 11:266. [PMID: 32457789 PMCID: PMC7225347 DOI: 10.3389/fgene.2020.00266] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 03/05/2020] [Indexed: 11/13/2022] Open
Abstract
The yeast Saccharomyces cerevisiae is a powerful model to study the molecular mechanisms underlying α-synuclein (α-syn) cytotoxicity. This is due to the high degree of conservation of cellular processes with higher eukaryotes and the fact that yeast does not endogenously express α-synuclein. In this work, we focused specifically on the interplay between α-syn and intracellular Ca2+ homeostasis. Using temperature-sensitive SEC4 mutants and deletion strains for the vacuolar Ca2+ transporters Pmc1 and Vcx1, together with aequorin-based Ca2+ recordings, we show that overexpression of α-syn shifts the predominant temporal pattern of organellar Ca2+ release from a biphasic to a quasi-monophasic response. Fragmentation and vesiculation of vacuolar membranes in α-syn expressing cells can account for the faster release of vacuolar Ca2+. α-Syn further significantly reduced Ca2+ storage resulting in increased resting cytosolic Ca2+ levels. Overexpression of the vacuolar Ca2+ ATPase Pmc1 in wild-type cells prevented the α-syn-induced increase in resting Ca2+ and was able to restore growth. We propose that α-syn-induced disruptions in Ca2+ signaling might be an important step in initiating cell death.
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Affiliation(s)
| | | | - Tien-Yang Ma
- The Yeast Hub Lab, KU Leuven, Kortrijk, Belgium.,Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
| | - Mara Del Vecchio
- Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
| | | | - Vanessa Franssens
- Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
| | - Joris Winderickx
- Functional Biology, Department of Biology, KU Leuven, Heverlee, Belgium
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12
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Garabadu D, Agrawal N, Sharma A, Sharma S. Mitochondrial metabolism: a common link between neuroinflammation and neurodegeneration. Behav Pharmacol 2020; 30:642-652. [PMID: 31625975 DOI: 10.1097/fbp.0000000000000505] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Neurodegenerative disorders have been considered as a growing health concern for decades. Increasing risk of neurodegenerative disorders creates a socioeconomic burden to both patients and care givers. Mitochondria are organelle that are involved in both neuroinflammation and neurodegeneration. There are few reports on the effect of mitochondrial metabolism on the progress of neurodegeneration and neuroinflammation. Therefore, the present review summarizes the potential contribution of mitochondrial metabolic pathways in the pathogenesis of neuroinflammation and neurodegeneration. Mitochondrial pyruvate metabolism plays a critical role in the pathogenesis of neurodegenerative disorders such as Parkinson's disease and Alzheimer's disease. However, there its potential contribution in other neurodegenerative disorders is as yet unproven. The mitochondrial pyruvate carrier and pyruvate dehydrogenase can modulate mitochondrial pyruvate metabolism to attenuate neuroinflammation and neurodegeneration. Further, it has been observed that the mitochondrial citric acid cycle can regulate the pathogenesis of neuroinflammation and neurodegeneration. Additional research should be undertaken to target tricarboxylic acid cycle enzymes to minimize the progress of neuroinflammation and neurodegeneration. It has also been observed that the mitochondrial urea cycle can potentially contribute to the progression of neurodegenerative disorders. Therefore, targeting this pathway may control the mitochondrial dysfunction-induced neuroinflammation and neurodegeneration. Furthermore, the mitochondrial malate-aspartate shuttle could be another target to control mitochondrial dysfunction-induced neuroinflammation and neurodegeneration in neurodegenerative disorders.
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Affiliation(s)
- Debapriya Garabadu
- Division of Pharmacology, Institute of Pharmaceutical Research, GLA University, Mathura, India
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13
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Theocharopoulou G. The ubiquitous role of mitochondria in Parkinson and other neurodegenerative diseases. AIMS Neurosci 2020; 7:43-65. [PMID: 32455165 PMCID: PMC7242057 DOI: 10.3934/neuroscience.2020004] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Accepted: 02/05/2020] [Indexed: 12/14/2022] Open
Abstract
Orderly mitochondrial life cycle, plays a key role in the pathology of neurodegenerative diseases. Mitochondria are ubiquitous in neurons as they respond to an ever-changing demand for energy supply. Mitochondria constantly change in shape and location, feature of their dynamic nature, which facilitates a quality control mechanism. Biological studies in mitochondria dynamics are unveiling the mechanisms of fission and fusion, which essentially arrange morphology and motility of these organelles. Control of mitochondrial network homeostasis is a critical factor for the proper function of neurons. Disease-related genes have been reported to be implicated in mitochondrial dysfunction. Increasing evidence implicate mitochondrial perturbation in neuronal diseases, such as AD, PD, HD, and ALS. The intricacy involved in neurodegenerative diseases and the dynamic nature of mitochondria point to the idea that, despite progress toward detecting the biology underlying mitochondrial disorders, its link to these diseases is difficult to be identified in the laboratory. Considering the need to model signaling pathways, both in spatial and temporal level, there is a challenge to use a multiscale modeling framework, which is essential for understanding the dynamics of a complex biological system. The use of computational models in order to represent both a qualitative and a quantitative structure of mitochondrial homeostasis, allows to perform simulation experiments so as to monitor the conformational changes, as well as the intersection of form and function.
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14
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Cerium Oxide Nanoparticles Rescue α-Synuclein-Induced Toxicity in a Yeast Model of Parkinson's Disease. NANOMATERIALS 2020; 10:nano10020235. [PMID: 32013138 PMCID: PMC7075201 DOI: 10.3390/nano10020235] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 01/25/2020] [Accepted: 01/26/2020] [Indexed: 12/21/2022]
Abstract
Over the last decades, cerium oxide nanoparticles (CeO2 NPs) have gained great interest due to their potential applications, mainly in the fields of agriculture and biomedicine. Promising effects of CeO2 NPs are recently shown in some neurodegenerative diseases, but the mechanism of action of these NPs in Parkinson's disease (PD) remains to be investigated. This issue is addressed in the present study by using a yeast model based on the heterologous expression of the human α-synuclein (α-syn), the major component of Lewy bodies, which represent a neuropathological hallmark of PD. We observed that CeO2 NPs strongly reduce α-syn-induced toxicity in a dose-dependent manner. This effect is associated with the inhibition of cytoplasmic α-syn foci accumulation, resulting in plasma membrane localization of α-syn after NP treatment. Moreover, CeO2 NPs counteract the α-syn-induced mitochondrial dysfunction and decrease reactive oxygen species (ROS) production in yeast cells. In vitro binding assay using cell lysates showed that α-syn is adsorbed on the surface of CeO2 NPs, suggesting that these NPs may act as a strong inhibitor of α-syn toxicity not only acting as a radical scavenger, but through a direct interaction with α-syn in vivo.
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15
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Liu Y, Zhang Y, Zhu K, Chi S, Wang C, Xie A. Emerging Role of Sirtuin 2 in Parkinson's Disease. Front Aging Neurosci 2020; 11:372. [PMID: 31998119 PMCID: PMC6965030 DOI: 10.3389/fnagi.2019.00372] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Accepted: 12/19/2019] [Indexed: 12/17/2022] Open
Abstract
Parkinson’s disease (PD), the main risk factor of which is age, is one of the most common neurodegenerative diseases, thus presenting a substantial burden on the health of affected individuals as well as an economic burden. Sirtuin 2 (SIRT2), a subtype in the family of sirtuins, belongs to class III histone deacetylases (HDACs). It is known that SIRT2 levels increase with aging, and a growing body of evidence has been accumulating, showing that the activity of SIRT2 mediates various processes involved in PD pathogenesis, including aggregation of α-synuclein (α-syn), microtubule function, oxidative stress, inflammation, and autophagy. There have been conflicting reports about the role of SIRT2 in PD, in that some studies indicate its potential to induce the death of dopaminergic (DA) neurons, and that inhibition of SIRT2 may, therefore, have protective effects in PD. Other studies suggest a protective role of SIRT2 in the context of neuronal damage. As current treatments for PD are directed at alleviating symptoms and are very limited, a comprehensive understanding of the enzymology of SIRT2 in PD may be essential for developing novel therapeutic agents for the treatment of this disease. This review article will provide an update on our knowledge of the structure, distribution, and biological characteristics of SIRT2, and highlight its role in the pathogenesis of PD.
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Affiliation(s)
- Yumei Liu
- Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yingying Zhang
- Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Konghua Zhu
- Department of Neurology, The Eighth People Hospital of Qingdao City, Qingdao, China
| | - Song Chi
- Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Chong Wang
- Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Anmu Xie
- Department of Neurology, The Affiliated Hospital of Qingdao University, Qingdao, China
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16
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Delenclos M, Burgess JD, Lamprokostopoulou A, Outeiro TF, Vekrellis K, McLean PJ. Cellular models of alpha-synuclein toxicity and aggregation. J Neurochem 2019; 150:566-576. [PMID: 31265132 DOI: 10.1111/jnc.14806] [Citation(s) in RCA: 59] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 06/19/2019] [Accepted: 07/04/2019] [Indexed: 12/11/2022]
Abstract
Misfolding and aggregation of alpha-synuclein (α-synuclein) with concomitant cytotoxicity is a hallmark of Lewy body related disorders such as Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Although it plays a pivotal role in pathogenesis and disease progression, the function of α-synuclein and the molecular mechanisms underlying α-synuclein-induced neurotoxicity in these diseases are still elusive. Many in vitro and in vivo experimental models mimicking α-synuclein pathology such as oligomerization, toxicity and more recently neuronal propagation have been generated over the years. In particular, cellular models have been crucial for our comprehension of the pathogenic process of the disease and are beneficial for screening of molecules capable of modulating α-synuclein toxicity. Here, we review α-synuclein based cell culture models that reproduce some features of the neuronal populations affected in patients, from basic unicellular organisms to mammalian cell lines and primary neurons, to the cutting edge models of patient-specific cell lines. These reprogrammed cells known as induced pluripotent stem cells (iPSCs) have garnered attention because they closely reproduce the characteristics of neurons found in patients and provide a valuable tool for mechanistic studies. We also discuss how different cell models may constitute powerful tools for high-throughput screening of molecules capable of modulating α-synuclein toxicity and prevention of its propagation. This article is part of the Special Issue "Synuclein".
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Affiliation(s)
- Marion Delenclos
- Department of Neuroscience, Mayo Clinic, Jacksonville, Florida, USA
| | - Jeremy D Burgess
- Department of Neuroscience, Mayo Clinic, Jacksonville, Florida, USA.,Neuroscience PhD Program, Mayo Clinic Graduate School of Biomedical Sciences, Jacksonville, Florida, USA
| | - Agaristi Lamprokostopoulou
- Department of Neuroscience, Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Tiago F Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany.,Max Planck Institute for Experimental Medicine, Göttingen, Germany.,Institute of Neuroscience, The Medical School, Newcastle University, Newcastle upon Tyne, UK
| | - Kostas Vekrellis
- Department of Neuroscience, Center for Basic Research, Biomedical Research Foundation, Academy of Athens, Athens, Greece
| | - Pamela J McLean
- Department of Neuroscience, Mayo Clinic, Jacksonville, Florida, USA.,Neuroscience PhD Program, Mayo Clinic Graduate School of Biomedical Sciences, Jacksonville, Florida, USA
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17
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Alecu I, Bennett SAL. Dysregulated Lipid Metabolism and Its Role in α-Synucleinopathy in Parkinson's Disease. Front Neurosci 2019; 13:328. [PMID: 31031582 PMCID: PMC6470291 DOI: 10.3389/fnins.2019.00328] [Citation(s) in RCA: 141] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/21/2019] [Indexed: 12/23/2022] Open
Abstract
Parkinson's disease (PD) is the second most common neurodegenerative disease, the main pathological hallmark of which is the accumulation of α-synuclein (α-syn) and the formation of filamentous aggregates called Lewy bodies in the brainstem, limbic system, and cortical areas. Lipidomics is a newly emerging field which can provide fresh insights and new answers that will enhance our capacity for early diagnosis, tracking disease progression, predicting critical endpoints, and identifying risk in pre-symptomatic persons. In recent years, lipids have been implicated in many aspects of PD pathology. Biophysical and lipidomic studies have demonstrated that α-syn binds preferentially not only to specific lipid families but also to specific molecular species and that these lipid-protein complexes enhance its interaction with synaptic membranes, influence its oligomerization and aggregation, and interfere with the catalytic activity of cytoplasmic lipid enzymes and lysosomal lipases, thereby affecting lipid metabolism. The genetic link between aberrant lipid metabolism and PD is even more direct, with mutations in GBA and SMPD1 enhancing PD risk in humans and loss of GALC function increasing α-syn aggregation and accumulation in experimental murine models. Moreover, a number of lipidomic studies have reported PD-specific lipid alterations in both patient brains and plasma, including alterations in the lipid composition of lipid rafts in the frontal cortex. A further aspect of lipid dysregulation promoting PD pathogenesis is oxidative stress and inflammation, with proinflammatory lipid mediators such as platelet activating factors (PAFs) playing key roles in arbitrating the progressive neurodegeneration seen in PD linked to α-syn intracellular trafficking. Lastly, there are a number of genetic risk factors of PD which are involved in normal lipid metabolism and function. Genes such as PLA2G6 and SCARB2, which are involved in glycerophospholipid and sphingolipid metabolism either directly or indirectly are associated with risk of PD. This review seeks to describe these facets of metabolic lipid dysregulation as they relate to PD pathology and potential pathomechanisms involved in disease progression, while highlighting incongruous findings and gaps in knowledge that necessitate further research.
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Affiliation(s)
- Irina Alecu
- Neural Regeneration Laboratory, Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis and Research Innovation, University of Ottawa, Ottawa, ON, Canada
| | - Steffany A. L. Bennett
- Neural Regeneration Laboratory, Department of Biochemistry, Microbiology and Immunology, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, Brain and Mind Research Institute, University of Ottawa, Ottawa, ON, Canada
- Department of Chemistry and Biomolecular Sciences, Centre for Catalysis and Research Innovation, University of Ottawa, Ottawa, ON, Canada
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18
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Yeast at the Forefront of Research on Ageing and Age-Related Diseases. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 2019; 58:217-242. [PMID: 30911895 DOI: 10.1007/978-3-030-13035-0_9] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Ageing is a complex and multifactorial process driven by genetic, environmental and stochastic factors that lead to the progressive decline of biological systems. Mechanisms of ageing have been extensively investigated in various model organisms and systems generating fundamental advances. Notably, studies on yeast ageing models have made numerous and relevant contributions to the progress in the field. Different longevity factors and pathways identified in yeast have then been shown to regulate molecular ageing in invertebrate and mammalian models. Currently the best candidates for anti-ageing drugs such as spermidine and resveratrol or anti-ageing interventions such as caloric restriction were first identified and explored in yeast. Yeasts have also been instrumental as models to study the cellular and molecular effects of proteins associated with age-related diseases such as Parkinson's, Huntington's or Alzheimer's diseases. In this chapter, a review of the advances on ageing and age-related diseases research in yeast models will be made. Particular focus will be placed on key longevity factors, ageing hallmarks and interventions that slow ageing, both yeast-specific and those that seem to be conserved in multicellular organisms. Their impact on the pathogenesis of age-related diseases will be also discussed.
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19
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Abstract
The budding yeast Saccharomyces cerevisiae (S. cerevisiae) has been a remarkable experimental model for the discovery of fundamental biological processes. The high degree of conservation of cellular and molecular processes between the budding yeast and higher eukaryotes has made it a valuable system for the investigation of the molecular mechanisms behind various types of devastating human pathologies. Genetic screens in yeast provided important insight into the toxic mechanisms associated with the accumulation of misfolded proteins. Thus, using yeast genetics and high-throughput screens, novel molecular targets with therapeutic potential have been identified. Here, we describe a yeast screen protocol for the identification of genetic modifiers of alpha-synuclein (aSyn) toxicity, thereby accelerating the identification of novel potential targets for intervention in Parkinson's disease (PD) and other synucleinopathies.
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Affiliation(s)
- Inês Caldeira Brás
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany
| | - Blagovesta Popova
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Goettingen, Germany
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, Göttingen, Germany
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Goettingen, Germany
| | - Tiago F Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Goettingen, Goettingen, Germany.
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain, Goettingen, Germany.
- Max Planck Institute for Experimental Medicine, Goettingen, Germany.
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20
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From Yeast to Humans: Leveraging New Approaches in Yeast to Accelerate Discovery of Therapeutic Targets for Synucleinopathies. Methods Mol Biol 2019; 2049:419-444. [PMID: 31602625 DOI: 10.1007/978-1-4939-9736-7_24] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Neurodegenerative diseases (ND) represent a growing, global health crisis, one that lacks any disease-modifying therapeutic strategy. This critical need for new therapies must be met with an exhaustive approach to exploit all tools available. A yeast (Saccharomyces cerevisiae) model of α-synuclein toxicity-the protein causally linked to Parkinson's disease and other synucleinopathies-offers a powerful approach that takes advantage of the unique offerings of this system: tractable genetics, robust high-throughput screening strategies, unparalleled data repositories, powerful computational tools, and extensive evolutionary conservation of fundamental biological pathways. These attributes have enabled genetic and small molecule screens that have revealed toxic phenotypes and drug targets that translate directly to patient-derived iPSC neurons. Extending these insights, recent advances in genetic network analyses have generated the first "humanized" α-synuclein network, which has identified druggable proteins and led to validation of the toxic phenotypes in patient-derived cells. Unbiased phenotypic small molecule screens can identify compounds targeting critical proteins within α-synuclein networks. While identification of direct drug targets for phenotypic screen hits represents a bottleneck, high-throughput chemical genetic methods provide a means to uncover cellular targets and pathways for large numbers of compounds in parallel. Taken together, the yeast α-synuclein model and associated tools can reveal insights into underlying cellular pathologies, lead molecules and their cognate targets, and strategies to translate mechanisms of toxicity and cytoprotection into complex neuronal systems.
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21
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Derf A, Sharma A, Bharate SB, Chaudhuri B. Aegeline, a natural product from the plant Aegle marmelos, mimics the yeast SNARE protein Sec22p in suppressing α-synuclein and Bax toxicity in yeast. Bioorg Med Chem Lett 2018; 29:454-460. [PMID: 30579794 DOI: 10.1016/j.bmcl.2018.12.028] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 12/12/2018] [Indexed: 02/06/2023]
Abstract
Herein, we have identified yeast Sec22p (ySec22p), a SNARE protein essential for endoplasmic reticulum to Golgi trafficking, as a suppressor of Bax-induced yeast apoptosis and corroborated published observations that ySec22p suppresses α-synuclein's toxicity in yeast. It has been suggested that compounds which enhance expression, in neurons, of human homologues of ySec22p (Sec22Bp/Sec22p/Sec22A) would prevent synucleinopathies, such as Parkinson's disease. With the aim of finding a small molecule that would mimic ySec22p, a library of natural products consisting of 394-compounds was screened using yeast cells that express either human α-synuclein or human Bax. The antioxidant aegeline, an alkaloid-amide occurring in the leaves of the plant Aegle marmelos Correa, was the only molecule that overcame apoptosis induced by both α-synuclein and Bax in yeast. Besides, aegeline also prevented growth block in cells expressing the more toxic A53T α-synuclein mutant. Restoration of cell growth occurred through inhibition of increased ROS levels, mitochondrial membrane potential loss and nuclear DNA fragmentation, characteristics of apoptosis manifested in α-synuclein or Bax-expressing cells. These results highlight the importance of yeast systems to identify rapidly molecules that may prevent the onset of apoptosis that occurs in Parkinson's disease.
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Affiliation(s)
- Asma Derf
- Leicester School of Pharmacy, De Montfort University, Leicester LE1 9BH, UK
| | - Ankita Sharma
- Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India
| | - Sandip B Bharate
- Medicinal Chemistry Division, CSIR-Indian Institute of Integrative Medicine, Canal Road, Jammu 180001, India.
| | - Bhabatosh Chaudhuri
- Leicester School of Pharmacy, De Montfort University, Leicester LE1 9BH, UK.
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22
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Ruetenik A, Barrientos A. Exploiting Post-mitotic Yeast Cultures to Model Neurodegeneration. Front Mol Neurosci 2018; 11:400. [PMID: 30450036 PMCID: PMC6224518 DOI: 10.3389/fnmol.2018.00400] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/12/2018] [Indexed: 12/19/2022] Open
Abstract
Over the last few decades, the budding yeast Saccharomyces cerevisiae has been extensively used as a valuable organism to explore mechanisms of aging and human age-associated neurodegenerative disorders. Yeast models can be used to study loss of function of disease-related conserved genes and to investigate gain of function activities, frequently proteotoxicity, exerted by non-conserved human mutant proteins responsible for neurodegeneration. Most published models of proteotoxicity have used rapidly dividing cells and suffer from a high level of protein expression resulting in acute growth arrest or cell death. This contrasts with the slow development of neurodegenerative proteotoxicity during aging and the characteristic post-mitotic state of the affected cell type, the neuron. Here, we will review the efforts to create and characterize yeast models of neurodegeneration using the chronological life span model of aging, and the specific information they can provide regarding the chronology of physiological events leading to neurotoxic proteotoxicity-induced cell death and the identification of new pathways involved.
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Affiliation(s)
- Andrea Ruetenik
- Department of Neurology, School of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States.,Neuroscience Graduate Program, School of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
| | - Antonio Barrientos
- Department of Neurology, School of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States.,Neuroscience Graduate Program, School of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States.,Department of Biochemistry, School of Medicine, University of Miami Miller School of Medicine, Miami, FL, United States
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23
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An Apoptotic and Endosymbiotic Explanation of the Warburg and the Inverse Warburg Hypotheses. Int J Mol Sci 2018; 19:ijms19103100. [PMID: 30308966 PMCID: PMC6213112 DOI: 10.3390/ijms19103100] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 10/03/2018] [Accepted: 10/05/2018] [Indexed: 12/12/2022] Open
Abstract
Otto Warburg, a Nobel prize winner, observed that cancer cells typically “switch” from aerobic to anaerobic respiration. He hypothesized that mitochondrial damage induces neoplastic transformation. In contrast, pathological aging is observed mainly in neuron cells in neurodegenerative diseases. Oxidative respiration is particularly active in neurons. There is inverse comorbidity between cancer and neurodegenerative diseases. This led to the creation of the “inverse Warburg hypothesis”, according to which excessive mitochondrial activity induces pathological aging. The findings of our studies suggest that both the Warburg effect and the “inverse Warburg hypothesis” can be elucidated by the activation or suppression of apoptosis through oxidative respiration. The key outcome of our phylogenetic studies was the discovery that apoptosis and apoptosis-like cell death evolved due to an evolutionary “arms race” conducted between “prey” protomitochondrion and “predator” primitive eukaryotes. The ancestral protomitochondrial machinery produces and releases toxic mitochondrial proteins. Extant apoptotic factors evolved from these toxins. Our experiments indicate that the mitochondrial machinery is directly involved in adaptation to aerobic conditions. Additionally, our hypothesis is supported by the fact that different apoptotic factors are directly involved in respiration.
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Dumit VI, Zerbes RM, Kaeser-Pebernard S, Rackiewicz M, Wall MT, Gretzmeier C, Küttner V, van der Laan M, Braun RJ, Dengjel J. Respiratory status determines the effect of emodin on cell viability. Oncotarget 2018; 8:37478-37490. [PMID: 28415582 PMCID: PMC5514923 DOI: 10.18632/oncotarget.16396] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Accepted: 03/01/2017] [Indexed: 12/20/2022] Open
Abstract
The anthraquinone emodin has been shown to have antineoplastic properties and a wealth of unconnected effects have been linked to its use, most of which are likely secondary outcomes of the drug treatment. The primary activity of emodin on cells has remained unknown. In the present study we demonstrate dramatic and extensive effects of emodin on the redox state of cells and on mitochondrial homeostasis, irrespectively of the cell type and organism, ranging from the yeast Saccharomyces cerevisiae to human cell lines and primary cells. Emodin binds to redox-active enzymes and its effectiveness depends on the oxidative and respiratory status of cells. We show that cells with efficient respiratory metabolism are less susceptible to emodin, whereas cells under glycolytic metabolism are more vulnerable to the compound. Our findings indicate that emodin acts in a similar way as known uncouplers of the mitochondrial electron transport chain and causes oxidative stress that particularly disturbs cancer cells.
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Affiliation(s)
- Verónica I Dumit
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany.,Center for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Department of Dermatology, Medical Center, University of Freiburg, Freiburg, Germany.,Core Facility Proteomics, ZBSA, University of Freiburg, Freiburg, Germany
| | - Ralf M Zerbes
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,Faculty of Biology, University of Freiburg, Freiburg, Germany
| | | | - Michal Rackiewicz
- Center for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Department of Dermatology, Medical Center, University of Freiburg, Freiburg, Germany.,Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Mona T Wall
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany.,Center for Biological Systems Analysis (ZBSA), Freiburg, Germany
| | - Christine Gretzmeier
- Center for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Department of Dermatology, Medical Center, University of Freiburg, Freiburg, Germany
| | - Victoria Küttner
- Center for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Department of Dermatology, Medical Center, University of Freiburg, Freiburg, Germany
| | - Martin van der Laan
- Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany.,Medical Biochemistry and Molecular Biology, Center for Molecular Signaling, PZMS, Saarland University, Homburg, Germany
| | - Ralf J Braun
- Institute of Cell Biology, University of Bayreuth, Bayreuth, Germany
| | - Jörn Dengjel
- Freiburg Institute for Advanced Studies (FRIAS), University of Freiburg, Freiburg, Germany.,Center for Biological Systems Analysis (ZBSA), Freiburg, Germany.,Department of Dermatology, Medical Center, University of Freiburg, Freiburg, Germany.,BIOSS Centre for Biological Signalling Studies, University of Freiburg, Freiburg, Germany.,Department of Biology, University of Fribourg, Fribourg, Switzerland
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25
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Tenreiro S, Franssens V, Winderickx J, Outeiro TF. Yeast models of Parkinson's disease-associated molecular pathologies. Curr Opin Genet Dev 2018; 44:74-83. [PMID: 28232272 DOI: 10.1016/j.gde.2017.01.013] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 01/30/2017] [Indexed: 12/15/2022]
Abstract
The aging of the human population is resulting in an increase in the number of people afflicted by neurodegenerative disorders such as Parkinson's disease (PD), creating tremendous socio-economic challenges. This requires the urgent for the development of effective therapies, and of tools for early diagnosis of the disease. However, our understanding of the molecular mechanisms underlying PD pathogenesis is still incomplete, hampering progress in those areas. In recent years, the progression made in genetics has considerably contributed to our knowledge, by identifying several novel PD genes. Furthermore, many cellular and animal models have proven their value to decipher pathways involved in PD development. In this review we highlight the value of the yeast Saccharomyces cerevisiae as a model for PD. This unicellular eukaryote has contributed to our understanding of the cellular mechanisms targeted by most important PD genes and offers an excellent tool for discovering novel players via powerful and informative high throughput screens that accelerate further validation in more complex models.
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Affiliation(s)
- Sandra Tenreiro
- CEDOC-Chronic Diseases Research Center, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Vanessa Franssens
- Department of Biology, Functional Biology, KU Leuven, 3001 Heverlee, Belgium
| | - Joris Winderickx
- Department of Biology, Functional Biology, KU Leuven, 3001 Heverlee, Belgium
| | - Tiago Fleming Outeiro
- CEDOC-Chronic Diseases Research Center, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Lisboa, Portugal; Department of Neurodegeneration and Restorative Research, University Medical Center Goettingen, Goettingen, Germany.
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26
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Ring J, Rockenfeller P, Abraham C, Tadic J, Poglitsch M, Schimmel K, Westermayer J, Schauer S, Achleitner B, Schimpel C, Moitzi B, Rechberger GN, Sigrist SJ, Carmona-Gutierrez D, Kroemer G, Büttner S, Eisenberg T, Madeo F. Mitochondrial energy metabolism is required for lifespan extension by the spastic paraplegia-associated protein spartin. MICROBIAL CELL (GRAZ, AUSTRIA) 2017; 4:411-422. [PMID: 29234670 PMCID: PMC5722644 DOI: 10.15698/mic2017.12.603] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 11/20/2017] [Indexed: 01/11/2023]
Abstract
Hereditary spastic paraplegias, a group of neurodegenerative disorders, can be caused by loss-of-function mutations in the protein spartin. However, the physiological role of spartin remains largely elusive. Here we show that heterologous expression of human or Drosophila spartin extends chronological lifespan of yeast, reducing age-associated ROS production, apoptosis, and necrosis. We demonstrate that spartin localizes to the proximity of mitochondria and physically interacts with proteins related to mitochondrial and respiratory metabolism. Interestingly, Nde1, the mitochondrial external NADH dehydrogenase, and Pda1, the core enzyme of the pyruvate dehydrogenase complex, are required for spartin-mediated cytoprotection. Furthermore, spartin interacts with the glycolysis enhancer phospo-fructo-kinase-2,6 (Pfk26) and is sufficient to complement for PFK26-deficiency at least in early aging. We conclude that mitochondria-related energy metabolism is crucial for spartin's vital function during aging and uncover a network of specific interactors required for this function.
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Affiliation(s)
- Julia Ring
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Patrick Rockenfeller
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, UK
| | - Claudia Abraham
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Jelena Tadic
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Michael Poglitsch
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Katherina Schimmel
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Institute of Molecular and Translational Therapeutic Strategies (IMTTS), IFB-Tx, Hannover Medical School, Hannover, Germany
| | - Julia Westermayer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Simon Schauer
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Bettina Achleitner
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Christa Schimpel
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- BioNanoNet Forschungsgesellschaft mbH, Graz, Austria
| | - Barbara Moitzi
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - Gerald N. Rechberger
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Omics Center Graz, BioTechMed-Graz, Graz, Austria
| | - Stephan J. Sigrist
- Institute for Biology, Freie Universität Berlin, Berlin, Germany
- NeuroCure, Charité, Berlin, Germany
| | | | - Guido Kroemer
- BioTechMed Graz, Graz, Austria
- Cell Biology and Metabolomics Platforms, Gustave Roussy Comprehensive Cancer Center, Villejuif, France
- INSERM, U1138, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
- Université Pierre et Marie Curie, Paris, France
- Pôle de Biologie, Hôpital Européen Georges Pompidou, Paris, France
- Karolinska Institute, Department of Women's and Children's Health, Karolinska University Hospital Stockholm, Sweden
| | - Sabrina Büttner
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
| | - Tobias Eisenberg
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
| | - Frank Madeo
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
- BioTechMed Graz, Graz, Austria
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27
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Patel M, McElroy PB. Mitochondrial Dysfunction in Parkinson’s Disease. OXIDATIVE STRESS AND REDOX SIGNALLING IN PARKINSON’S DISEASE 2017. [DOI: 10.1039/9781782622888-00061] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Parkinson’s disease (PD) is one of the most common neurodegenerative disorders where oxidative stress and mitochondrial dysfunction have been implicated as etiological factors. Mitochondria are the major producers of reactive oxygen species (ROS) that can have damaging effects to cellular macromolecules leading to neurodegeneration. The most compelling evidence for the role of mitochondria in the pathogenesis of PD has been derived from toxicant-induced models of parkinsonism. Over the years, epidemiological studies have suggested a link between exposure to environmental toxins such as pesticides and the risk of developing PD. Data from human and experimental studies involving the use of chemical agents like paraquat, diquat, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, rotenone and maneb have provided valuable insight into the underlying mitochondrial mechanisms contributing to PD and associated neurodegeneration. In this review, we have discussed the role of mitochondrial ROS and dysfunction in the pathogenesis of PD with a special focus on environmental agent-induced parkinsonism. We have described the various mitochondrial mechanisms by which such chemicals exert neurotoxicity, highlighting some landmark epidemiological and experimental studies that support the role of mitochondrial ROS and oxidative stress in contributing to these effects. Finally, we have discussed the significance of these studies in understanding the mechanistic underpinnings of PD-related dopaminergic neurodegeneration.
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Affiliation(s)
- Manisha Patel
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus Aurora CO 80045 USA
| | - Pallavi Bhuyan McElroy
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus Aurora CO 80045 USA
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28
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Aufschnaiter A, Habernig L, Kohler V, Diessl J, Carmona-Gutierrez D, Eisenberg T, Keller W, Büttner S. The Coordinated Action of Calcineurin and Cathepsin D Protects Against α-Synuclein Toxicity. Front Mol Neurosci 2017; 10:207. [PMID: 28713240 PMCID: PMC5491553 DOI: 10.3389/fnmol.2017.00207] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 06/12/2017] [Indexed: 11/24/2022] Open
Abstract
The degeneration of dopaminergic neurons during Parkinson’s disease (PD) is intimately linked to malfunction of α-synuclein (αSyn), the main component of the proteinaceous intracellular inclusions characteristic for this pathology. The cytotoxicity of αSyn has been attributed to disturbances in several biological processes conserved from yeast to humans, including Ca2+ homeostasis, general lysosomal function and autophagy. However, the precise sequence of events that eventually results in cell death remains unclear. Here, we establish a connection between the major lysosomal protease cathepsin D (CatD) and the Ca2+/calmodulin-dependent phosphatase calcineurin. In a yeast model for PD, high levels of human αSyn triggered cytosolic acidification and reduced vacuolar hydrolytic capacity, finally leading to cell death. This could be counteracted by overexpression of yeast CatD (Pep4), which re-installed pH homeostasis and vacuolar proteolytic function, decreased αSyn oligomers and aggregates, and provided cytoprotection. Interestingly, these beneficial effects of Pep4 were independent of autophagy. Instead, they required functional calcineurin signaling, since deletion of calcineurin strongly reduced both the proteolytic activity of endogenous Pep4 and the cytoprotective capacity of overexpressed Pep4. Calcineurin contributed to proper endosomal targeting of Pep4 to the vacuole and the recycling of the Pep4 sorting receptor Pep1 from prevacuolar compartments back to the trans-Golgi network. Altogether, we demonstrate that stimulation of this novel calcineurin-Pep4 axis reduces αSyn cytotoxicity.
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Affiliation(s)
| | - Lukas Habernig
- Institute of Molecular Biosciences, University of GrazGraz, Austria.,Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm UniversityStockholm, Sweden
| | - Verena Kohler
- Institute of Molecular Biosciences, University of GrazGraz, Austria
| | - Jutta Diessl
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm UniversityStockholm, Sweden
| | | | - Tobias Eisenberg
- Institute of Molecular Biosciences, University of GrazGraz, Austria
| | - Walter Keller
- Institute of Molecular Biosciences, University of GrazGraz, Austria
| | - Sabrina Büttner
- Institute of Molecular Biosciences, University of GrazGraz, Austria.,Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm UniversityStockholm, Sweden
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29
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Fruhmann G, Seynnaeve D, Zheng J, Ven K, Molenberghs S, Wilms T, Liu B, Winderickx J, Franssens V. Yeast buddies helping to unravel the complexity of neurodegenerative disorders. Mech Ageing Dev 2017; 161:288-305. [DOI: 10.1016/j.mad.2016.05.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 04/22/2016] [Accepted: 05/02/2016] [Indexed: 12/31/2022]
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30
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Aufschnaiter A, Kohler V, Diessl J, Peselj C, Carmona-Gutierrez D, Keller W, Büttner S. Mitochondrial lipids in neurodegeneration. Cell Tissue Res 2017; 367:125-140. [PMID: 27449929 PMCID: PMC5203858 DOI: 10.1007/s00441-016-2463-1] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2016] [Accepted: 06/24/2016] [Indexed: 01/10/2023]
Abstract
Mitochondrial dysfunction is a common feature of many neurodegenerative diseases, including proteinopathies such as Alzheimer's or Parkinson's disease, which are characterized by the deposition of aggregated proteins in the form of insoluble fibrils or plaques. The distinct molecular processes that eventually result in mitochondrial dysfunction during neurodegeneration are well studied but still not fully understood. However, defects in mitochondrial fission and fusion, mitophagy, oxidative phosphorylation and mitochondrial bioenergetics have been linked to cellular demise. These processes are influenced by the lipid environment within mitochondrial membranes as, besides membrane structure and curvature, recruitment and activity of different proteins also largely depend on the respective lipid composition. Hence, the interaction of neurotoxic proteins with certain lipids and the modification of lipid composition in different cell compartments, in particular mitochondria, decisively impact cell death associated with neurodegeneration. Here, we discuss the relevance of mitochondrial lipids in the pathological alterations that result in neuronal demise, focussing on proteinopathies.
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Affiliation(s)
- Andreas Aufschnaiter
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria
| | - Verena Kohler
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria
| | - Jutta Diessl
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Carlotta Peselj
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden
| | - Didac Carmona-Gutierrez
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria
| | - Walter Keller
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria
| | - Sabrina Büttner
- Institute of Molecular Biosciences, University of Graz, Humboldtstraße 50, 8010, Graz, Austria.
- Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Svante Arrheniusväg 20C, 106 91, Stockholm, Sweden.
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31
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Kainz K, Tadic J, Zimmermann A, Pendl T, Carmona-Gutierrez D, Ruckenstuhl C, Eisenberg T, Madeo F. Methods to Assess Autophagy and Chronological Aging in Yeast. Methods Enzymol 2016; 588:367-394. [PMID: 28237110 DOI: 10.1016/bs.mie.2016.09.086] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Autophagy is a catabolic process that is crucial for cellular homeostasis and adaptive response to changing environments. Importantly, autophagy has been shown to be induced in many longevity-associated scenarios and to be required to maintain lifespan extension. Notably, autophagy is a highly conserved cellular process among eukaryotes, and the yeast Saccharomyces cerevisiae has become a universal model system for unraveling the molecular machinery underlying autophagic mechanisms. Here, we discuss different protocols to monitor survival and autophagy of yeast cells upon chronological aging. These include the use of propidium iodide to assess the loss of cell membrane integrity, as well as clonogenic assays to directly determine survival rates. Additionally, we describe methods to quantify autophagic flux, including the alkaline phosphatase activity or the GFP liberation assays, which measure the delivery of autophagosomal cargo to the vacuole. In sum, we have recapped established protocols used to evaluate a link between lifespan extension and autophagy in yeast.
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Affiliation(s)
- K Kainz
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - J Tadic
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - A Zimmermann
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - T Pendl
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - D Carmona-Gutierrez
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - C Ruckenstuhl
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria
| | - T Eisenberg
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - F Madeo
- Institute of Molecular Biosciences, NAWI Graz, University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria.
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32
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Exploring the power of yeast to model aging and age-related neurodegenerative disorders. Biogerontology 2016; 18:3-34. [PMID: 27804052 DOI: 10.1007/s10522-016-9666-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 10/24/2016] [Indexed: 12/12/2022]
Abstract
Aging is a multifactorial process determined by molecular, cellular and systemic factors and it is well established that advancing age is a leading risk factor for several neurodegenerative diseases. In fact, the close association of aging and neurodegenerative disorders has placed aging as the greatest social and economic challenge of the 21st century, and age-related diseases have also become a key priority for countries worldwide. The growing need to better understand both aging and neurodegenerative processes has led to the development of simple eukaryotic models amenable for mechanistic studies. Saccharomyces cerevisiae has proven to be an unprecedented experimental model to study the fundamental aspects of aging and to decipher the intricacies of neurodegenerative disorders greatly because the molecular mechanisms underlying these processes are evolutionarily conserved from yeast to human. Moreover, yeast offers several methodological advantages allowing a rapid and relatively easy way of establishing gene-protein-function associations. Here we review different aging theories, common cellular pathways driving aging and neurodegenerative diseases and discuss the major contributions of yeast to the state-of-art knowledge in both research fields.
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33
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Ruetenik AL, Ocampo A, Ruan K, Zhu Y, Li C, Zhai RG, Barrientos A. Attenuation of polyglutamine-induced toxicity by enhancement of mitochondrial OXPHOS in yeast and fly models of aging. MICROBIAL CELL 2016; 3:338-351. [PMID: 28357370 PMCID: PMC5349013 DOI: 10.15698/mic2016.08.518] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Defects in mitochondrial biogenesis and function are common in many neurodegenerative disorders, including Huntington's disease (HD). We have previously shown that in yeast models of HD, enhancement of mitochondrial biogenesis through overexpression of Hap4, the catalytic subunit of the transcriptional complex that regulates mitochondrial gene expression, alleviates the growth arrest induced by expanded polyglutamine (polyQ) tract peptides in rapidly dividing cells. However, the mechanism through which HAP4 overexpression exerts this protection remains unclear. Furthermore, it remains unexplored whether HAP4 overexpression and increased respiratory function during growth can also protect against polyQ-induced toxicity during yeast chronological lifespan. Here, we show that in yeast, mitochondrial respiration and oxidative phosphorylation (OXPHOS) are essential for protection against the polyQ-induced growth defect by HAP4 overexpression. In addition, we show that not only increased HAP4 levels, but also alternative interventions, including calorie restriction, that result in enhanced mitochondrial biogenesis confer protection against polyQ toxicity during stationary phase. The data obtained in yeast models guided experiments in a fly model of HD, where we show that enhancement of mitochondrial biogenesis can also protect against neurodegeneration and behavioral deficits. Our results suggest that therapeutic interventions aiming at the enhancement of mitochondrial respiration and OXPHOS could reduce polyQ toxicity and delay disease onset.
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Affiliation(s)
- Andrea L Ruetenik
- Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Alejandro Ocampo
- Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Kai Ruan
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Molecular and Cellular Pharmacology Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Yi Zhu
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Molecular and Cellular Pharmacology Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Chong Li
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Human Genetics and Genomics Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - R Grace Zhai
- Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Molecular and Cellular Pharmacology Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Human Genetics and Genomics Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Antoni Barrientos
- Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Department of Neurology, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Department of Biochemistry and Molecular Biology, University of Miami Miller School of Medicine, Miami, FL 33136, USA. ; Molecular and Cellular Pharmacology Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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34
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Falcone C, Mazzoni C. External and internal triggers of cell death in yeast. Cell Mol Life Sci 2016; 73:2237-50. [PMID: 27048816 PMCID: PMC4887522 DOI: 10.1007/s00018-016-2197-y] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/18/2016] [Indexed: 01/30/2023]
Abstract
In recent years, yeast was confirmed as a useful eukaryotic model system to decipher the complex mechanisms and networks occurring in higher eukaryotes, particularly in mammalian cells, in physiological as well in pathological conditions. This article focuses attention on the contribution of yeast in the study of a very complex scenario, because of the number and interconnection of pathways, represented by cell death. Yeast, although it is a unicellular organism, possesses the basal machinery of different kinds of cell death occurring in higher eukaryotes, i.e., apoptosis, regulated necrosis and autophagy. Here we report the current knowledge concerning the yeast orthologs of main mammalian cell death regulators and executors, the role of organelles and compartments, and the cellular phenotypes observed in the different forms of cell death in response to external and internal triggers. Thanks to the ease of genetic manipulation of this microorganism, yeast strains expressing human genes that promote or counteract cell death, onset of tumors and neurodegenerative diseases have been constructed. The effects on yeast cells of some of these genes are also presented.
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Affiliation(s)
- Claudio Falcone
- Pasteur Institute-Cenci Bolognetti Foundation; Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy
| | - Cristina Mazzoni
- Pasteur Institute-Cenci Bolognetti Foundation; Department of Biology and Biotechnology "Charles Darwin", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
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35
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Shrestha A, Megeney LA. Yeast proteinopathy models: a robust tool for deciphering the basis of neurodegeneration. MICROBIAL CELL 2015; 2:458-465. [PMID: 28357271 PMCID: PMC5354604 DOI: 10.15698/mic2015.12.243] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Protein quality control or proteostasis is an essential determinant of basic cell health and aging. Eukaryotic cells have evolved a number of proteostatic mechanisms to ensure that proteins retain functional conformation, or are rapidly degraded when proteins misfold or self-aggregate. Disruption of proteostasis is now widely recognized as a key feature of aging related illness, specifically neurodegenerative disease. For example, Alzheimer’s disease, Huntington’s disease, Parkinson’s disease and Amyotrophic Lateral Sclerosis (ALS) each target and afflict distinct neuronal cell subtypes, yet this diverse array of human pathologies share the defining feature of aberrant protein aggregation within the affected cell population. Here, we review the use of budding yeast as a robust proxy to study the intersection between proteostasis and neurodegenerative disease. The humanized yeast model has proven to be an amenable platform to identify both, conserved proteostatic mechanisms across eukaryotic phyla and novel disease specific molecular dysfunction. Moreover, we discuss the intriguing concept that yeast specific proteins may be utilized as bona fide therapeutic agents, to correct proteostasis errors across various forms of neurodegeneration.
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Affiliation(s)
- Amit Shrestha
- Ottawa Hospital Research Institute, Regenerative Medicine Program, Sprott Centre for Stem Cell Research, The Ottawa Hospital, Ottawa, Ontario, Canada. ; Department of Cellular and Molecular Medicine University of Ottawa, Ottawa, Ontario, Canada
| | - Lynn A Megeney
- Ottawa Hospital Research Institute, Regenerative Medicine Program, Sprott Centre for Stem Cell Research, The Ottawa Hospital, Ottawa, Ontario, Canada. ; Department of Cellular and Molecular Medicine University of Ottawa, Ottawa, Ontario, Canada ; Department of Medicine, University of Ottawa, Ottawa, Ontario, Canada
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36
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Intracellular Dynamics of Synucleins: "Here, There and Everywhere". INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 320:103-69. [PMID: 26614873 DOI: 10.1016/bs.ircmb.2015.07.007] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Synucleins are small, soluble proteins expressed primarily in neural tissue and in certain tumors. The synuclein family consists of three members: α-, β-, and γ-synucleins present only in vertebrates. Members of the synuclein family have high sequence identity, especially in the N-terminal regions. The synuclein gene family came into the spotlight, when one of its members, α-synuclein, was found to be associated with Parkinson's disease and other neurodegenerative disorders, whereas γ-synuclein was linked to several forms of cancer. There are a lot of controversy and exciting debates concerning members of the synuclein family, including their normal functions, toxicity, role in pathology, transmission between cells and intracellular localization. Important findings which remain undisputable for many years are synuclein localization in synapses and their role in the regulation of synaptic vesicle trafficking, whereas their presence and function in mitochondria and nucleus is a debated topic. In this review, we present the data on the localization of synucleins in two intracellular organelles: the nucleus and mitochondria.
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37
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Menezes R, Tenreiro S, Macedo D, Santos CN, Outeiro TF. From the baker to the bedside: yeast models of Parkinson's disease. MICROBIAL CELL 2015; 2:262-279. [PMID: 28357302 PMCID: PMC5349099 DOI: 10.15698/mic2015.08.219] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The baker’s yeast Saccharomyces cerevisiae has been extensively explored for our understanding of fundamental cell biology processes highly conserved in the eukaryotic kingdom. In this context, they have proven invaluable in the study of complex mechanisms such as those involved in a variety of human disorders. Here, we first provide a brief historical perspective on the emergence of yeast as an experimental model and on how the field evolved to exploit the potential of the model for tackling the intricacies of various human diseases. In particular, we focus on existing yeast models of the molecular underpinnings of Parkinson’s disease (PD), focusing primarily on the central role of protein quality control systems. Finally, we compile and discuss the major discoveries derived from these studies, highlighting their far-reaching impact on the elucidation of PD-associated mechanisms as well as in the identification of candidate therapeutic targets and compounds with therapeutic potential.
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Affiliation(s)
- Regina Menezes
- Instituto de Biologia Experimental e Tecnológica, Apartado 12, Oeiras 2781-901, Portugal. ; Instituto de Tecnologia Química e Biológica António Xavier, Av. da República, 2780-157 Oeiras, Universidade Nova de Lisboa, Portugal
| | - Sandra Tenreiro
- Instituto de Medicina Molecular, Av. Prof. Egas Moniz, Lisboa 1649-028, Portugal. ; CEDOC - Chronic Diseases Research Center, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Campo dos Mártires da Pátria, 130, Lisboa 1169-056, Portugal
| | - Diana Macedo
- Instituto de Tecnologia Química e Biológica António Xavier, Av. da República, 2780-157 Oeiras, Universidade Nova de Lisboa, Portugal
| | - Cláudia N Santos
- Instituto de Biologia Experimental e Tecnológica, Apartado 12, Oeiras 2781-901, Portugal. ; Instituto de Tecnologia Química e Biológica António Xavier, Av. da República, 2780-157 Oeiras, Universidade Nova de Lisboa, Portugal
| | - Tiago F Outeiro
- Instituto de Fisiologia, Faculdade de Medicina da Universidade de Lisboa, Lisboa 1649-028, Portugal. ; CEDOC - Chronic Diseases Research Center, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Campo dos Mártires da Pátria, 130, Lisboa 1169-056, Portugal. ; Department of NeuroDegeneration and Restorative Research, University Medical Center Göttingen, Waldweg 33, Göttingen 37073, Germany
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38
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Rostovtseva TK, Gurnev PA, Protchenko O, Hoogerheide DP, Yap TL, Philpott CC, Lee JC, Bezrukov SM. α-Synuclein Shows High Affinity Interaction with Voltage-dependent Anion Channel, Suggesting Mechanisms of Mitochondrial Regulation and Toxicity in Parkinson Disease. J Biol Chem 2015; 290:18467-77. [PMID: 26055708 DOI: 10.1074/jbc.m115.641746] [Citation(s) in RCA: 149] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Indexed: 12/20/2022] Open
Abstract
Participation of the small, intrinsically disordered protein α-synuclein (α-syn) in Parkinson disease (PD) pathogenesis has been well documented. Although recent research demonstrates the involvement of α-syn in mitochondrial dysfunction in neurodegeneration and suggests direct interaction of α-syn with mitochondria, the molecular mechanism(s) of α-syn toxicity and its effect on neuronal mitochondria remain vague. Here we report that at nanomolar concentrations, α-syn reversibly blocks the voltage-dependent anion channel (VDAC), the major channel of the mitochondrial outer membrane that controls most of the metabolite fluxes in and out of the mitochondria. Detailed analysis of the blockage kinetics of VDAC reconstituted into planar lipid membranes suggests that α-syn is able to translocate through the channel and thus target complexes of the mitochondrial respiratory chain in the inner mitochondrial membrane. Supporting our in vitro experiments, a yeast model of PD shows that α-syn toxicity in yeast depends on VDAC. The functional interactions between VDAC and α-syn, revealed by the present study, point toward the long sought after physiological and pathophysiological roles for monomeric α-syn in PD and in other α-synucleinopathies.
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Affiliation(s)
- Tatiana K Rostovtseva
- From the Program in Physical Biology, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892,
| | - Philip A Gurnev
- From the Program in Physical Biology, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892, the Physics Department, University of Massachusetts, Amherst, Massachusetts 01003
| | - Olga Protchenko
- the Liver Diseases Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - David P Hoogerheide
- From the Program in Physical Biology, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892, the Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, and
| | - Thai Leong Yap
- the Laboratory of Molecular Biophysics, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Caroline C Philpott
- the Liver Diseases Branch, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Jennifer C Lee
- the Laboratory of Molecular Biophysics, NHLBI, National Institutes of Health, Bethesda, Maryland 20892
| | - Sergey M Bezrukov
- From the Program in Physical Biology, Eunice Kennedy Shriver NICHD, National Institutes of Health, Bethesda, Maryland 20892
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Werner-Washburne M, Roy S, Davidson GS. Aging and the survival of quiescent and non-quiescent cells in yeast stationary-phase cultures. Subcell Biochem 2015; 57:123-43. [PMID: 22094420 DOI: 10.1007/978-94-007-2561-4_6] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In this chapter, we argue that with careful attention to cell types in stationary-phase cultures of the yeast, S. cerevisiae provide an excellent model system for aging studies and hold much promise in pinpointing the set of causal genes and mechanisms driving aging. Importantly, a more detailed understanding of aging in this single celled organism will also shed light on aging in tissue-complex model organisms such as C. elegans and D. melanogaster. We feel strongly that the relationship between aging in yeast and tissue-complex organisms has been obscured by failure to notice the heterogeneity of stationary-phase cultures and the processes by which distinct cell types arise in these cultures. Although several studies have used yeast stationary-phase cultures for chronological aging, the majority of these studies have assumed that cultures in stationary phase are homogeneously composed of a single cell type. However, genome-scale analyses of yeast stationary-phase cultures have identified two major cell fractions: quiescent and non-quiescent, which we discuss in detail in this chapter. We review evidence that cell populations isolated from these cultures exhibit population-specific phenotypes spanning a range of metabolic and physiological processes including reproductive capacity, apoptosis, differences in metabolic activities, genetic hyper-mutability, and stress responses. The identification, in S. cerevisiae, of multiple sub-populations having differentiated physiological attributes relevant to aging offers an unprecedented opportunity. This opportunity to deeply understand yeast cellular (and population) aging programs will, also, give insight into genomic and metabolic processes in tissue-complex organism, as well as stem cell biology and the origins of differentiation.
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Affiliation(s)
- M Werner-Washburne
- Department of Biology, University of New Mexico, Albuquerque, NM, 87131, USA,
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40
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Pyatrikas DV, Fedoseeva IV, Varakina NN, Rusaleva TM, Stepanov AV, Fedyaeva AV, Borovskii GB, Rikhvanov EG. Relation between cell death progression, reactive oxygen species production and mitochondrial membrane potential in fermenting Saccharomyces cerevisiae cells under heat-shock conditions. FEMS Microbiol Lett 2015; 362:fnv082. [DOI: 10.1093/femsle/fnv082] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2015] [Indexed: 12/21/2022] Open
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Popova B, Kleinknecht A, Braus GH. Posttranslational Modifications and Clearing of α-Synuclein Aggregates in Yeast. Biomolecules 2015; 5:617-34. [PMID: 25915624 PMCID: PMC4496687 DOI: 10.3390/biom5020617] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 04/01/2015] [Accepted: 04/14/2015] [Indexed: 12/20/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae represents an established model system to study the molecular mechanisms associated to neurodegenerative disorders. A key-feature of Parkinson’s disease is the formation of Lewy bodies, which are cytoplasmic protein inclusions. Misfolded α-synuclein is one of their main constituents. Expression of α-synuclein protein in yeast leads to protein aggregation and cellular toxicity, which is reminiscent to Lewy body containing human cells. The molecular mechanism involved in clearance of α-synuclein aggregates is a central question for elucidating the α-synuclein-related toxicity. Cellular clearance mechanisms include ubiquitin mediated 26S proteasome function as well as lysosome/vacuole associated degradative pathways as autophagy. Various modifications change α-synuclein posttranslationally and alter its inclusion formation, cytotoxicity and the distribution to different clearance pathways. Several of these modification sites are conserved from yeast to human. In this review, we summarize recent findings on the effect of phosphorylation and sumoylation of α-synuclein to the enhanced channeling to either the autophagy or the proteasome degradation pathway in yeast model of Parkinson’s disease.
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Affiliation(s)
- Blagovesta Popova
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany.
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), D-37077 Göttingen, Germany.
| | - Alexandra Kleinknecht
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany.
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), D-37077 Göttingen, Germany.
| | - Gerhard H Braus
- Department of Molecular Microbiology and Genetics, Institute of Microbiology and Genetics, Georg-August-Universität Göttingen, D-37077 Göttingen, Germany.
- Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), D-37077 Göttingen, Germany.
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Braun RJ. Ubiquitin-dependent proteolysis in yeast cells expressing neurotoxic proteins. Front Mol Neurosci 2015; 8:8. [PMID: 25814926 PMCID: PMC4357299 DOI: 10.3389/fnmol.2015.00008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Accepted: 02/24/2015] [Indexed: 01/16/2023] Open
Abstract
Critically impaired protein degradation is discussed to contribute to neurodegenerative disorders, including Parkinson's, Huntington's, Alzheimer's, and motor neuron diseases. Misfolded, aggregated, or surplus proteins are efficiently degraded via distinct protein degradation pathways, including the ubiquitin-proteasome system, autophagy, and vesicular trafficking. These pathways are regulated by covalent modification of target proteins with the small protein ubiquitin and are evolutionary highly conserved from humans to yeast. The yeast Saccharomyces cerevisiae is an established model for deciphering mechanisms of protein degradation, and for the elucidation of pathways underlying programmed cell death. The expression of human neurotoxic proteins triggers cell death in yeast, with neurotoxic protein-specific differences. Therefore, yeast cell death models are suitable for analyzing the role of protein degradation pathways in modulating cell death upon expression of disease-causing proteins. This review summarizes which protein degradation pathways are affected in these yeast models, and how they are involved in the execution of cell death. I will discuss to which extent this mimics the situation in other neurotoxic models, and how this may contribute to a better understanding of human disorders.
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Affiliation(s)
- Ralf J Braun
- Institut für Zellbiologie, Universität Bayreuth Bayreuth, Germany
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A yeast model of the Parkinson's disease-associated protein Parkin. Exp Cell Res 2015; 333:73-9. [PMID: 25728007 DOI: 10.1016/j.yexcr.2015.02.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Revised: 02/17/2015] [Accepted: 02/18/2015] [Indexed: 11/20/2022]
Abstract
Mutations in Parkin, an E3 ubiquitin ligase, are associated to autosomal recessive Parkinson's disease (PD). Parkin has been mainly implicated, along with Pink1, in mitochondrial autophagy in response to stress. In this study, a yeast model was developed to analyse the biological function of human Parkin. We observed that Parkin increases yeast chronological lifespan and oxidative stress resistance, through a mitochondrial-dependent pathway. Moreover, in response to H2O2, Parkin translocate to mitochondria, leading to a higher mitochondrial degradation. Parkin-induced H2O2 resistance is dependent on the autophagic pathway and on the mitochondrial protein Por1p. Although expression of Pink1 induces an H2O2 resistance phenotype similar to Parkin, co-expression of both proteins does not result in a synergistic effect. Concerning H2O2 resistance, this may indicate that these two proteins independently affect the same pathway. Altogether, this work establishes a yeast model for Parkin, which may provide new insights on Parkin function and potential mechanisms of pathogenicity.
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Wijayanti I, Watanabe D, Oshiro S, Takagi H. Isolation and functional analysis of yeast ubiquitin ligase Rsp5 variants that alleviate the toxicity of human α-synuclein. J Biochem 2014; 157:251-60. [PMID: 25398992 DOI: 10.1093/jb/mvu069] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The essential ubiquitin ligase Rsp5 is a key enzyme involved in the degradation of abnormal or unfavourable proteins in the yeast Saccharomyces cerevisiae. Overexpression of human α-synuclein (α-syn), a small lipid-binding protein implicated in several neurodegenerative diseases, in S. cerevisiae leads to growth inhibition due to many intracellular defects, including accumulation of reactive oxygen species (ROS). Here, to understand the mechanism of Rsp5-mediated detoxification of α-syn, we isolated novel Rsp5 variants (T255A, D295G, P343S and N427D), which conferred α-syn tolerance to yeast cells. Interestingly, these mutants were phenotypically distinguished from our previously identified RSP5(T357A) mutation, which increases ubiquitination of the general amino acid permease Gap1. Among them, the RSP5(P343S) substitution accelerated the degradation of α-syn, suppressed the accumulation of intracellular ROS and enhanced the interaction with α-syn and its ubiquitination. In contrast, the RSP5(T255A) mutation did not contribute to degradation of α-syn, but improved cell growth under acetate stress conditions, possibly leading to alleviation of the α-syn toxicity. Thus, these novel mutations might be useful not only in elucidating the molecular basis by which disused proteins are specifically recognized and effectively removed but also in screening drug candidates for neurodegenerative diseases or in improving ethanol production under acidic fermentation conditions.
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Affiliation(s)
- Indah Wijayanti
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Daisuke Watanabe
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Satoshi Oshiro
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
| | - Hiroshi Takagi
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara 630-0192, Japan
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45
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Shen J, Du T, Wang X, Duan C, Gao G, Zhang J, Lu L, Yang H. α-Synuclein amino terminus regulates mitochondrial membrane permeability. Brain Res 2014; 1591:14-26. [PMID: 25446002 DOI: 10.1016/j.brainres.2014.09.046] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 09/05/2014] [Accepted: 09/19/2014] [Indexed: 12/22/2022]
Abstract
Parkinson's disease (PD) is a common neurodegenerative movement disorder affecting an increasing number of elderly. Various studies have shown that mitochondrial dysfunction and abnormal protein aggregation are two major contributors to the progression of PD. The N terminus of α-synuclein (α-Syn/N), which adopts an α-helical conformation upon lipid binding, is essential for membrane interaction; yet its role in mitochondria remains poorly defined. A functional characterization of the α-Syn N-terminal domain and investigation of its effect on mitochondrial membrane permeability were undertaken in this study. α-Syn/N and α-Syn/delN (amino acids 1-65 and 61-140, respectively) constructs were overexpressed in dopaminergic MN9D cells and primary cortical neurons. A decrease in cell viability was observed in cells transfected with α-Syn/N but not α-Syn/delN. In addition, an α-Syn/N-induced increase in the level of intracellular reactive oxygen species, alteration in mitochondrial morphology, and decrease in mitochondrial membrane potential were accompanied by the activation of mitochondrial permeability transition pores (mPTP). These changes were also associated with a decline in mitochondrial cardiolipin content and interaction with the voltage-dependent anion channel and adenine nucleotide translocator in the mitochondrial membrane. The activation of mPTPs and reduction in cell viability were partially reversed by bongkrekic acid, an inhibitor of adenine nucleotide translocator (ANT), suggesting that the interaction between α-Syn and ANT promoted mPTP activation and was toxic to cells. BKA treatment reduced interaction of α-Syn/N with ANT and VDAC. These results suggest that the N terminus of α-Syn is essential for the regulation of mitochondrial membrane permeability and is a likely factor in the neurodegeneration associated with PD.
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Affiliation(s)
- Jiamei Shen
- Center for Parkinson׳s Disease, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Department of Neurobiology Capital Medical University, Beijing 100069, China
| | - Tingting Du
- Center for Parkinson׳s Disease, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Department of Neurobiology Capital Medical University, Beijing 100069, China
| | - Xue Wang
- Center for Parkinson׳s Disease, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Department of Neurobiology Capital Medical University, Beijing 100069, China
| | - Chunli Duan
- Center for Parkinson׳s Disease, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Department of Neurobiology Capital Medical University, Beijing 100069, China
| | - Ge Gao
- Center for Parkinson׳s Disease, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Department of Neurobiology Capital Medical University, Beijing 100069, China
| | - Jianliang Zhang
- Center for Parkinson׳s Disease, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Department of Neurobiology Capital Medical University, Beijing 100069, China
| | - Lingling Lu
- Center for Parkinson׳s Disease, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Department of Neurobiology Capital Medical University, Beijing 100069, China
| | - Hui Yang
- Center for Parkinson׳s Disease, Beijing Institute for Brain Disorders, Key Laboratory for Neurodegenerative Diseases of the Ministry of Education, Department of Neurobiology Capital Medical University, Beijing 100069, China.
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Bitto A, Lerner CA, Nacarelli T, Crowe E, Torres C, Sell C. P62/SQSTM1 at the interface of aging, autophagy, and disease. AGE (DORDRECHT, NETHERLANDS) 2014; 36:9626. [PMID: 24557832 PMCID: PMC4082582 DOI: 10.1007/s11357-014-9626-3] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Accepted: 01/28/2014] [Indexed: 06/02/2023]
Abstract
Advanced age is characterized by increased incidence of many chronic, noninfectious diseases that impair the quality of living of the elderly and pose a major burden on the healthcare systems of developed countries. These diseases are characterized by impaired or altered function at the tissue and cellular level, which is a hallmark of the aging process. Age-related impairments are likely due to loss of homeostasis at the cellular level, which leads to the accumulation of dysfunctional organelles and damaged macromolecules, such as proteins, lipids, and nucleic acids. Intriguingly, aging and age-related diseases can be delayed by modulating nutrient signaling pathways converging on the target of rapamycin (TOR) kinase, either by genetic or dietary intervention. TOR signaling influences aging through several potential mechanisms, such as autophagy, a degradation pathway that clears the dysfunctional organelles and damaged macromolecules that accumulate with aging. Autophagy substrates are targeted for degradation by associating with p62/SQSTM1, a multidomain protein that interacts with the autophagy machinery. p62/SQSTM1 is involved in several cellular processes, and its loss has been linked to accelerated aging and to age-related pathologies. In this review, we describe p62/SQSTM1, its role in autophagy and in signaling pathways, and its emerging role in aging and age-associated pathologies. Finally, we propose p62/SQSTM1 as a novel target for aging studies and age-extending interventions.
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Affiliation(s)
- Alessandro Bitto
- />Department of Pathology, University of Washington, Health Science Building D-514, Box 357470, Seattle, WA USA
| | | | - Timothy Nacarelli
- />Department of Pathology, Drexel University College of Medicine, 245 N 15th Street, Philadelphia, PA 19102 USA
| | - Elizabeth Crowe
- />Department of Pathology, Drexel University College of Medicine, 245 N 15th Street, Philadelphia, PA 19102 USA
| | - Claudio Torres
- />Department of Pathology, Drexel University College of Medicine, 245 N 15th Street, Philadelphia, PA 19102 USA
| | - Christian Sell
- />Department of Pathology, Drexel University College of Medicine, 245 N 15th Street, Philadelphia, PA 19102 USA
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Tenreiro S, Reimão-Pinto MM, Antas P, Rino J, Wawrzycka D, Macedo D, Rosado-Ramos R, Amen T, Waiss M, Magalhães F, Gomes A, Santos CN, Kaganovich D, Outeiro TF. Phosphorylation modulates clearance of alpha-synuclein inclusions in a yeast model of Parkinson's disease. PLoS Genet 2014; 10:e1004302. [PMID: 24810576 PMCID: PMC4014446 DOI: 10.1371/journal.pgen.1004302] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 02/28/2014] [Indexed: 12/02/2022] Open
Abstract
Alpha-synuclein (aSyn) is the main component of proteinaceous inclusions known as Lewy bodies (LBs), the typical pathological hallmark of Parkinson's disease (PD) and other synucleinopathies. Although aSyn is phosphorylated at low levels under physiological conditions, it is estimated that ∼90% of aSyn in LBs is phosphorylated at S129 (pS129). Nevertheless, the significance of pS129 in the biology of aSyn and in PD pathogenesis is still controversial. Here, we harnessed the power of budding yeast in order to assess the implications of phosphorylation on aSyn cytotoxicity, aggregation and sub-cellular distribution. We found that aSyn is phosphorylated on S129 by endogenous kinases. Interestingly, phosphorylation reduced aSyn toxicity and the percentage of cells with cytosolic inclusions, in comparison to cells expressing mutant forms of aSyn (S129A or S129G) that mimic the unphosphorylated form of aSyn. Using high-resolution 4D imaging and fluorescence recovery after photobleaching (FRAP) in live cells, we compared the dynamics of WT and S129A mutant aSyn. While WT aSyn inclusions were very homogeneous, inclusions formed by S129A aSyn were larger and showed FRAP heterogeneity. Upon blockade of aSyn expression, cells were able to clear the inclusions formed by WT aSyn. However, this process was much slower for the inclusions formed by S129A aSyn. Interestingly, whereas the accumulation of WT aSyn led to a marked induction of autophagy, cells expressing the S129A mutant failed to activate this protein quality control pathway. The finding that the phosphorylation state of aSyn on S129 can alter the ability of cells to clear aSyn inclusions provides important insight into the role that this posttranslational modification may have in the pathogenesis of PD and other synucleinopathies, opening novel avenues for investigating the molecular basis of these disorders and for the development of therapeutic strategies. Protein aggregation is a common hallmark in neurodegenerative disorders, but is also associated with phenotypic plasticity in a variety of organisms, including yeasts. Alpha-synuclein (aSyn) forms aggregates that are typical of synucleinopathies, and is phosphorylated at S129, but the significance of phosphorylation in the biology and pathophysiology of the protein is still controversial. Exploring the power of budding yeast, we found phosphorylation reduced aSyn toxicity and inclusion formation. While inclusions formed by WT aSyn were homogeneous, those formed by S129A aSyn were larger and heterogeneous. Interestingly, clearance of aSyn inclusions was reduced in cells expressing S129A aSyn, correlating with deficient autophagy activation. The finding that phosphorylation alters the ability of cells to clear aSyn inclusions provides novel insight into the role phosphorylation may have in synucleinopathies, and suggests posttranslational modifications might constitute switches cells use to control the aggregation and clearance of key proteins, opening novel avenues for the development of therapeutic strategies for these devastating disorders.
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Affiliation(s)
- Sandra Tenreiro
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- * E-mail: (ST); (TFO)
| | - Madalena M. Reimão-Pinto
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Pedro Antas
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - José Rino
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Donata Wawrzycka
- Department of Genetics and Cell Physiology, Institute of Experimental Biology, University of Wroclaw, Wroclaw, Poland
| | - Diana Macedo
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Rita Rosado-Ramos
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Triana Amen
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Meytal Waiss
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Filipa Magalhães
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
| | - Andreia Gomes
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
| | - Cláudia N. Santos
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal
- Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal
| | - Daniel Kaganovich
- Department of Cell and Developmental Biology, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Tiago Fleming Outeiro
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- Instituto de Fisiologia, Faculdade de Medicina da Universidade de Lisboa, Lisboa, Portugal
- Department of NeuroDegeneration and Restorative Research, Center for Nanoscale Microscopy and Molecular Physiology of the Brain, University Medical Center Göttingen, Göttingen, Germany
- * E-mail: (ST); (TFO)
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48
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Song Y, Ding H, Yang J, Lin Q, Xue J, Zhang Y, Chan P, Cai Y. Pyrosequencing analysis of SNCA methylation levels in leukocytes from Parkinson's disease patients. Neurosci Lett 2014; 569:85-8. [DOI: 10.1016/j.neulet.2014.03.076] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Accepted: 03/29/2014] [Indexed: 12/20/2022]
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Camilleri A, Vassallo N. The centrality of mitochondria in the pathogenesis and treatment of Parkinson's disease. CNS Neurosci Ther 2014; 20:591-602. [PMID: 24703487 DOI: 10.1111/cns.12264] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Revised: 03/07/2014] [Accepted: 03/08/2014] [Indexed: 12/14/2022] Open
Abstract
Parkinson's disease (PD) is an incurable neurodegenerative disorder leading to progressive motor impairment and for which there is no cure. From the first postmortem account describing a lack of mitochondrial complex I in the substantia nigra of PD sufferers, the direct association between mitochondrial dysfunction and death of dopaminergic neurons has ever since been consistently corroborated. In this review, we outline common pathways shared by both sporadic and familial PD that remarkably and consistently converge at the level of mitochondrial integrity. Furthermore, such knowledge has incontrovertibly established mitochondria as a valid therapeutic target in neurodegeneration. We discuss several mitochondria-directed therapies that promote the preservation, rescue, or restoration of dopaminergic neurons and which have been identified in the laboratory and in preclinical studies. Some of these have progressed to clinical trials, albeit the identification of an unequivocal disease-modifying neurotherapeutic is still elusive. The challenge is therefore to improve further, not least by more research on the molecular mechanisms and pathophysiological consequences of mitochondrial dysfunction in PD.
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Affiliation(s)
- Angelique Camilleri
- Department of Physiology and Biochemistry, University of Malta, Msida 2080, Malta
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50
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Saleh AA, Bhadra AK, Roy I. Cytotoxicity of mutant huntingtin fragment in yeast can be modulated by the expression level of wild type huntingtin fragment. ACS Chem Neurosci 2014; 5:205-15. [PMID: 24377263 PMCID: PMC3963126 DOI: 10.1021/cn400171d] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Revised: 12/26/2013] [Indexed: 12/23/2022] Open
Abstract
Conflicting reports exist in the literature regarding the role of wild-type huntingtin in determining the toxicity of the aggregated, mutant huntingtin in Huntington's disease (HD). Some studies report the amelioration of toxicity of the mutant protein in the presence of the wild-type protein, while others indicate sequestration of the wild-type protein by mutant huntingtin. Over the years, yeast has been established as a valid model organism to study molecular changes associated with HD, especially at the protein level. We have used an inducible system to express human huntingtin fragments harboring normal (25Q) and pathogenic (103Q) polyglutamine lengths under the control of a galactose promoter in a yeast model of HD. We show that the relative expression level of each allele (wild-type/mutant) decides the cellular phenotype. When the expression level of wild-type huntingtin is high, an increase in the solubility of the mutant protein is observed. Fluorescence-recovery-after-photobleaching (FRAP) studies show that solubility reaches ∼94% in these cells. This leads to reduction in oxidative stress and cytotoxicity, and increases cell viability. In-cell FRET studies show that interaction between these proteins does not require the presence of a mediator. When the expression of wild-type huntingtin is low, it is sequestered into aggregates by the mutant protein. Even under these conditions, cytotoxicity is attenuated. Our findings indicate that the presence of wild-type huntingtin has a beneficial role even when its relative expression level is lower than that of the mutant protein.
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Affiliation(s)
- Aliabbas Ahmedbhai Saleh
- Department of Biotechnology, National Institute
of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India
| | - Ankan Kumar Bhadra
- Department of Biotechnology, National Institute
of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India
| | - Ipsita Roy
- Department of Biotechnology, National Institute
of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, Punjab 160 062, India
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